A Sub-Nanosecond Gate Bias-Switching Circuit for GaN RF Power Amplifiers

In this letter, we present a design of a fast gate-switching power amplifier (GSPA) aimed at reducing its power consumption. This GSPA features a dedicated fast gate-switching circuit that commutates the gallium nitride (GaN) transistor between a nominal gate bias voltage (GSPA ON) and a strong negative voltage (GSPA OFF), thereby generating two discrete output power levels in an RF-pulsewidth modulation (PWM) fashion. A fast gate-switching circuit, including a commercial digital voltage isolator, is designed to switch between two gate bias voltages. The gate stability resistor and transmission line (TL) are carefully placed and designed to reduce the GSPA parasitic bias line and enable fast switching. Measured results provided a rise and fall time of 750 and 950 ps, respectively, and achieved RF pulsewidths as narrow as 5.88 ns, thus corresponding to a 170-MHz bandwidth

A new design approach to the use of composite materials for heavy transport vehicles

In order to keep or to reach a high level of competitiveness and performance of a product, it is necessary to explore all the possible solutions that allow the best compromise between costs and project requirements. By this point of view the study of alternative designs and/or materials to use, is an important aspect that can identify a new concept or way of thinking about a product. This paper presents how to make use of composite materials in the field of heavy vehicles transportation. A new semitrailer in composite material has been designed, using a methodical redesign approach and an optimisation process. The main innovation in this project is, besides the use of the Glass Fibre Reinforced Plastics (GFRPs), also a new topology of the vehicle frame; the designed semitrailer, in fact. has a monocoque structur

Aroma characterization of mold resistant basewines for sparkling wine produced in a warm-temperate area at two different altitudes

In a recent context where consumers pay an increasing attention to sustainability and eco-friendly aspects in the decision-making process, the use of the resistant varieties in the winesector have returned to the attention. In this context, the use of mould-resistant grape varietieswould be an opportunity for sparkling wine producers as it can reduced the pesticideutilization in grape management and hence production costs. However, the use of the resistant varieties to produce the base wine may be strongly infl uenceddue to its requirements for a particular balance between sugars and acidity to ensure thequality of the fi nal product. In addition, the aromatic profi le of base wine plays a crucial rolein the perception of the quality of the sparkling wine. This work aims to study the volatile composition of base wines produced from fi ve resistantvarieties (Bronner, Solaris, Johanniter, Souvignier Gris, Vinera) cultivated in two experimentalvineyards located in Trentino (IT): one situated on the valley bottom and one in the hill. Theresults were comparing with those of Chardonnay, the main variety used in this areanowadays for this product, cultivated in the same plots. The volatiles were extracted from thebase wines and the GC-MS/MS analysis allowed to quantify the aromatic compoundsbelonging to six different chemical classes: acetates, ethyl esters, alcohols, fatty acids, terpenesand norisoprenoids. Among the varieties, Souvignier Gris was characterised by methyl salicylate and 1-hexanol,while Solaris stood out for the concentration of β-damascone, acetates and ethyl esters.Bronner showed signifi cant contents of some grape-derived metabolites, such as β-damasconeand linalool. This terpene was also present in higher quantities in Solaris and Johanniter.Regarding the location, acetates and ethyl esters were higher in base wines of the valleybottom and fatty acids, higher alcohols and terpenes in the hilly plot wines

Comparative study of haematology of two teleost fish (Mugil cephalus and Carassius auratus) from different environments and feeding habits

Haematological parameters are valuable indicators of fish health status. This study is aimed to provide baseline data of the blood profile of two teleost fish species living in different environments and with divergent feeding behaviour, namely the flathead grey mullet Mugil cephalus Linnaeus, 1758, a marine herbivorous fish, and the goldfish Carassius auratus (Linnaeus, 1758), a freshwater omnivorous fish. Using an automated system coupled with flow cytometry and light microscopy, significant variations were found between M. cephalus and C. auratus blood parameters, except for haemoglobin concentration (Hgb). A significant increase in red blood cell count (RBC) and haematocrit (Hct) levels, associated with reduced mean corpuscular volume (MCV), was revealed in mullets in respect to goldfish. These data may be attributable to differences in fish species, or to their divergent physiological activeness as high RBC values are associated with fast movement and high activity with streamlined bodies, or to environmental factors such as water salinity, an increase in which may lead to erythropoiesis as an adaptive process in seawater fish. Additionally, lower values of white blood cell count (WBC) and thrombocyte count (TC) were recorded in mullets with respect to goldfish, and these changes may be due to divergent feeding habits of the two fish species, or to their different environments since increased salinity may inversely affect WBC. Overall, findings from this study provide a better understanding of the influences of divergent environmental conditions and feeding habits on fish blood parameters. The combined use of an automatic haematological count with flow cytometry was demonstrated to be effective for an early assessment of blood parameters in different fish species

Pen shell Pinna nobilis L. (Mollusca: Bivalvia) from different peculiar environments: adaptive mechanisms of osmoregulation and neurotransmission

The pen shell Pinna nobilis (Linnaeus, 1758) is the largest endemic bivalve mollusc of the Mediterranean Sea, listed as an endangered species in the European Union. Because no information is available about the adaptation of pen shells to different habitats, herein the fundamental conditions of adaptation of P. nobilis to peculiar natural environments, such as the Strait of Messina (SM) and the meromictic Faro Lake (FL; Sicily, Italy), were explored by assessing the morphology, mucous production, osmoregulation and neurotransmission of their gills. Although gills of the pen shells from both sites exhibited a regular morphology, a higher presence of acid mucous cells was detected in P. nobilis from FL than SM, as well as higher levels of osmolytes but without interfering the osmoregulatory processes. About the functioning of gills, the cholinergic (i.e. acetylcholine and AChE) neuronal system was unaltered between individuals from the two sites, whereas the GABAergic neurotransmission (i.e. 4-aminobutyrate or GABA) was significantly augmented in gills of P. nobilis from FL than SM. This may be an adaptive response to hypoxic conditions in FL, as supported by the increased hypoxia-inducible factor (HIF-1α) in gills of pen shells from FL than SM. Noteworthy, this study reports for the first time the presence of the GABA neurotransmitter within the metabolite profile, obtained by application of a protonic Nuclear Magnetic Resonance (1H NMR)-based metabolomics approach, of a marine bivalve. Therefore, GABA may be suggested as a metabolite biomarker in pen shells. Overall, findings from this study provide new insights on the behavioural and adaptive responses of the pen shell Pinna nobilis settled in different peculiar environments