An annotated checklist of fishes of the family Sciaenidae

A checklist of the croakers of the world, family Sciaenidae, is presented. A total of 584 nominal species belonging to 289 valid species and 69 genera is included. Four genera, Johnius with 32 species, Cynoscion 25, Stellifer 24, and Umbrina 17 contains 30% of the species, whereas 43% of the genera (31) are monotypic. Eques is a valid genus-name and should be used instead of Equetus. Fourteen nominal species remain unidentifiable and are placed in incertae sedis, whereas 12 nominal species currently described in sciaenid genera lay outside the family. Among this latter group two of them represent senior synonyms of well-established species: Sciaena guttata Bloch and Schneider, 1801 and Sciaena pallida Walbaum, 1792 predate Giuris margaritaceus (Valenciennes, 1837) and Cymolutes praetextatus (Quoy and Gaimard, 1824), respectively, and they are here declared nomina oblita

An LCA model to assess the environmental improvement of new farming systems

The environmental impact of new farming practices is compared with that of conventional one. The approach is that of LCA and the assessing procedure is based on two cross-interaction matrices relating system inputs with emissions and impacts. With the aim to allow its application also at farm level by non-expert users, the procedure has been implemented in software that facilitate it use. Furthermore, the definition of standard impact values and a total environmental effects index make it easier to compare different systems and to evaluate the improvement achieved with a new agricultural practice. As an example, the model has been applied to compare the environmental effects generated in the production of sunflower using ecological, integrated and conventional farming techniques. Both Ecological and Integrated technique present lower impact than conventional even if for some specific impact the results are inverted. The application highlights the importance of the functional unit: when environmental effects are referred to the unit of production (ton), the total impact of the integrated technique is higher than the conventional one. Energy and CO2 efficiency are also computed, which are resulted to be good indicators of the overall environmental impact of a cultivation syste

Kinetics of leucine transport in brush border membrane vesicles from lepidopteran larvae midgut.

The kinetics of K(+)-leucine cotransport in the midgut of lepidopteran larvae was investigated using brush border membrane vesicles. Initial rate (3 s) of leucine uptake was determined under experimental conditions similar to those occurring in vivo, i.e. in the presence of delta psi much greater than 0 (inside negative) and a delta pH of 1.4 units (7.4in/8.8out). Leucine and K+ bind to the carrier according to a sequential mechanism, and the binding of one substrate changed the dissociation constant for the other substrate by a factor of 0.15. Both trans-K+ and trans-leucine were mixed-type inhibitors of leucine uptake. Moreover, a portion of total leucine uptake was K+ independent, and it was competitively inhibited by trans-leucine. We interpret the trans inhibitory effects to mean that the partially loaded K+ only form is virtually unable to translocate across the membrane, whereas the binary complex carrier, leucine, can isomerize from the trans to the cis side of the membrane. However, the K(+)-independent leucine uptake occurs with a Keq greater than 1, i.e. the efflux route through the partially loaded leucine only form is slower than the rate of isomerization of the unloaded carrier from trans to cis side. Taken together, these results suggest a model in which transport occurs by an iso-random Bi Bi system. Since K+ does not act as a pure competitive activator, this model is different from that proposed for most of the Na(+)-linked solutes transport agencies and may be related to the broadening of the cation specificity of the amino acid transporters in lepidopteran larvae

Micro-milling Machinability of DED Additive Titanium Ti-6Al-4V

This work investigates the micro-milling machinability of Ti-6Al-4V alloy produced by a Laser Engineered Net Shaping (LENS) additive manufacturing (AM) process with a specific focus on surface quality, cutting forces and burr formation. The effects of additive deposition parameters are also investigated since the material thermal history during processing can affect porosity and mechanical behavior of the samples, giving different milling performances. The material characterization of samples is done through micrographies, hardness tests and porosity evaluation. The roughness of the machined surfaces shows a statistical distinction between the AM and wrought titanium samples. Similar behavior is seen with the cutting forces, which increase with an increase of hardness of the AM samples. The results also show an increased trend towards burr formation in case of down milling of AM samples compared to wrought titanium samples. The future prospective is to take into account the machinability properties as functional material characteristics to optimize through the deposition process

3D Finite Element Simulation of Micro End-Milling by Considering the Effect of Tool Run-Out

Understanding the micro milling phenomena involved in the process is critical and difficult through physical experiments. This study presents a 3D finite element modeling (3D FEM) approach for the micro end-milling process on Al6082-T6. The proposed model employs a Lagrangian explicit finite element formulation to perform coupled thermo-mechanical transient analyses. FE simulations were performed at different cutting conditions to obtain realistic numerical predictions of chip formation, temperature distribution, and cutting forces by considering the effect of tool run-out in the model. The radial run-out is a significant issue in micro milling processes and influences the cutting stability due to chip load and force variations. The Johnson-Cook (JC) material constitutive model was applied and its constants were determined by an inverse method based on the experimental cutting forces acquired during the micro end-milling tests. The FE model prediction capability was validated by comparing the numerical model results with experimental tests. The maximum tool temperature was predicted in a different angular position of the cutter which is difficult or impossible to obtain in experiments. The predicted results of the model, involving the run-out influence, showed a good correlation with experimental chip formation and the signal shape of cutting forces

Cooled pads with bioinspired gyroid lattice for tilting pad journal bearings: Experimental validation of numerical model for heat transfer

Hydrodynamic journal bearings are essential components for industrial rotating machineries. Continuously growing specific power allows more compact and efficient machines to be obtained, by reducing the environmental footprint of production plants. The aim of this work is to provide a new design of an innovative pad for Tilting Pad Journal Bearings (TPJBs) with an embedded cooling circuit, able to limit the oil film temperature. As a result, specific load can be increased leading to a possible downsizing of the bearing and reduction of lubricant quantity. The heat exchange in the cooling circuit of the pad has been enhanced using bioinspired gyroid lattice. The thermo-mechanical study of the pad has been performed with both numerical and experimental analysis. The resulting thermal and mechanical performances have been calculated and discussed. The tested components have been manufactured in stainless steel by using a metal 3D printing technology, based on polymer-metal feedstock extrusion. A performance analysis is conducted to catch differences between the nominal and the printed geometry. The prototype is able to dissipate the generated heat with a higher efficiency, and the pressure drop inside the cooling circuit can be estimated with the numerical model here proposed

Finite element modeling of micro-orthogonal cutting process with dead metal cap

Dead metal cap plays an important role in the microcutting process because target material piled up on the tool–chip– workpiece interface can alter the cutting geometry. The target of this study is to model and simulate the microorthogonal cutting process in the presence of dead metal cap in order to investigate the effects of this phenomenon on the micromachining process outputs (cutting force, thrust force and chip thickness) and stress distribution, equivalent plastic strain and temperature inside the workpiece shear zones. For this purpose, the finite element method with explicit dynamic solution and adiabatic heating effect along with arbitrary Lagrangian–Eulerian approach is used. It is shown that the finite element models with current state-of-the-art assumptions cannot take into account the dead metal cap by default. For this reason, dead metal cap is artificially introduced on the rounded tool edge in this study for carrying out a proper analysis. Several simulations with different dead metal cap geometries are performed and obtained results show that prediction of cutting force, thrust force and chip thickness are sensitive to the presence of dead metal cap and its geometry. Micro-orthogonal cutting experiments are carried out on tubular AISI 1045 workpieces for validating and interpreting simulated results. The error between predicted and experimental data is calculated, and it is shown that simulation performances can be improved by considering the dead metal cap into the process model. For example, it is possible to reduce the error to less than 5% in case of thrust force prediction. This study points out how the target material’s Von Mises stress, equivalent plastic strain and temperature distribution are sensitive to any alteration of the edge geometry due to the dead metal cap. The best dead metal cap configuration in terms of agreement with experiments is also the one introducing a more homogeneous distribution of these quantities along the shear plane