Nonlinear phononic crystals based on chains of disks alternating with toroidal structures

We study experimentally the acoustic response of a load-bearing, phononic crystal composed of alternating steel disks, and polytetrafluoroethylene o-rings under precompression. The crystal allows for axial, rocking, and shear-polarized wavemodes when excited by a broad-band signal applied off-axis. Finite element analysis is employed to determine the system’s wave modes. The nonlinear interaction between disks and o-rings supports a dynamic response that is tunable with variations in static precompression, leading to controllable frequency shifts in a large band gap. A modal analysis reveals that four of the six principal wave modes are susceptible to external precompression while two modes are not

Wave Propagation in Auxetic Tetrachiral Honeycombs

This paper describes a numerical and experimental investigation on the flexural wave propagation properties of a novel class of negative Poisson's ratio honeycombs with tetrachiral topology. Tetrachiral honeycombs are structures defined by cylinders connected by four tangent ligaments, leading to a negative Poisson's ratio (auxetic) behavior in the plane due to combined cylinder rotation and bending of the ribs. A Bloch wave approach is applied to the representative unit cell of the honeycomb to calculate the dispersion characteristics and phase constant surfaces varying the geometric parameters of the unit cell. The modal density of the tetrachiral lattice and of a sandwich panel having the tetrachiral as core is extracted from the integration of the phase constant surfaces, and compared with the experimental ones obtained from measurements using scanning laser vibrometers

Mars surface sample return missions via solar electric propulsion

The characteristics and capabilities are described of solar electric propulsion (SEP) for performing Mars Surface Sample Return (MSSR) missions. The scope of the study emphasizes trajectory/payload analysis and the comparison of mission/system tradeoff options. The MSSR mission is examined only for the 1981-82 launch opportunity. Several other study constraints which bear directly on the results obtained are: (1) return samples in the range 5-25 kg, (2) use of lifting (offset C.G.) atmospheric entry at Mars which allows a low ratio (1.25) of entry weight to landed weight, and (3) rendezvous and docking in Mars orbit. Major results of the study are presented as performance curves of earth departure mass versus sample size for a number of different mission/system options. These options represent a spectrum of trip time, launch vehicle capability, combinations of low-thrust and ballistic maneuvers, chemical retro type, and earth recovery mode

Innovative solutions for the wine sector: the role of startups

The economic globalisation has opened new pathways for commerce and triggered a logistical revolution, which in turn has produced enormous technological innovations. In this context, the role of startups is becoming increasingly crucial since they are positioning themselves as innovation enablers among large and small companies. Between these innovations, IoT, Big Data Analytics and Blockchain can be used in various domains, among which the logistics of the whole wine supply chain. Here we will consider some of the issues and needs that arise in this market sector, showing how Wenda, a startup born in Bologna in February 2015 that works to improve sustainability and traceability in Food & Beverage supply chains, has been able to leverage IoT, Big Data Analytics and Blockchain to empower the wine supply chain with solutions that enable wine traceability throughout the distribution and the after-buying-in preservation and commercialisation phases

Adiponectin levels are reduced in children born small for gestational age and are inversely related to postnatal catch-up growth

Adiponectin is an adipocytokine with insulin-sensitizing and antiatherogenic properties. Reduced concentrations of adiponectin precede the onset of type 2 diabetes and the development of atherosclerosis. Our aim was to quantify adiponectin concentrations in small for gestational age (SGA) children. Fifty-one SGA children, 24 obese, and 17 short-normal children with birth weight appropriate for gestational age (short-AGA) were studied. The statures of the SGA children were corrected for their midparental height and subdivided into two groups according to their corrected height: catch-up growth group, children with corrected height of 0 z-score or greater (n = 17); and noncatch-up growth group, subjects with corrected height less than 0 z-score (n = 34). SGA children showed adiponectin levels significantly lower than short-normal children (35.2 +/- 3.5 vs. 80.4 +/- 26.6 mug/ml; P < 0.0001) and obese children (77.5 +/- 39.4 μg/ml; P < 0.0001). Catch-up growth children showed adiponectin levels significantly lower than noncatch-up growth subjects (29.4 +/- 10.3 vs. 38.1 +/- 11.5 mug/ml; P = 0.01). Adiponectin concentrations were inversely related to height z-score, corrected stature, weight, and body mass index and were positively related to birth weight. Our results suggest that adiponectin levels are reduced in SGA children and are even lower in those with postnatal catch-up growth. Whether this finding implies a higher risk of developing type 2 diabetes and atherosclerosis remains to be established

40. The gas-phase ammoxidation of n-hexane to unsaturated C6 dinitriles, intermediates for hexamethylenediamine synthesis

This paper reports about an investigation on the catalytic gas-phase ammoxidation of n-hexane aimed at the production of 1,6-C6 dinitriles, precursors for the synthesis of hexamethylenediamine. Catalysts tested were those also active and selective in the ammoxidation of propane to acrylonitrile: rutile-type V/Sb and Sn/V/Nb/Sb mixed oxides. Several N-containing compounds formed; however, the selectivity to cyano-containing aliphatic linear C6 compounds was low, due to the relevant contribution of side reactions such as combustion, cracking and formation of heavy compounds.INGLES

N-Acylethanolamine Acid Amidase (NAAA): Structure, Function, and Inhibition

N-Acylethanolamine acid amidase (NAAA) is an N-terminal cysteine hydrolase primarily found in the endosomal-lysosomal compartment of innate and adaptive immune cells. NAAA catalyzes the hydrolytic deactivation of palmitoylethanolamide (PEA), a lipid-derived peroxisome proliferator-activated receptor-α (PPAR-α) agonist that exerts profound anti-inflammatory effects in animal models. Emerging evidence points to NAAA-regulated PEA signaling at PPAR-α as a critical control point for the induction and the resolution of inflammation and to NAAA itself as a target for anti-inflammatory medicines. The present Perspective discusses three key aspects of this hypothesis: the role of NAAA in controlling the signaling activity of PEA; the structural bases for NAAA function and inhibition by covalent and noncovalent agents; and finally, the potential value of NAAA-targeting drugs in the treatment of human inflammatory disorders

Antidepressant-like effects of pharmacological inhibition of FAAH activity in socially isolated female rats

Pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid N-arachidonoylethanolamine (or anandamide, AEA), exerts favourable effects in rodent models of stress-related depression. Yet although depression seems to be more common among women than men and in spite of some evidence of sex differences in treatment efficacy, preclinical development of FAAH inhibitors for the pharmacotherapy of stress-related depression has been predominantly conducted in male animals. Here, adult female rats were exposed to six weeks of social isolation and, starting from the second week, treated with the FAAH inhibitor URB694 (0.3 mg/kg/day, i.p.) or vehicle. Compared to pair-housed females, socially isolated female rats treated with vehicle developed behavioral (mild anhedonia, passive stress coping) and physiological (reduced body weight gain, elevated plasma corticosterone levels) alterations. Moreover, prolonged social isolation provoked a reduction in brain-derived neurotrophic factor (BDNF) and AEA levels within the hippocampus. Together, these changes are indicative of an increased risk of developing a depressive-like state. Conversely, pharmacological inhibition of FAAH activity with URB694 restored both AEA and BDNF levels within the hippocampus of socially isolated rats and prevented the development of behavioral and physiological alterations. These results suggest a potential interplay between AEA-mediated signaling and hippocampal BDNF in the pathogenesis of depression-relevant behaviors and physiological alterations and antidepressant action of FAAH inhibition in socially isolated female rats

Vibration and Wave Propagation Control of Plates with Periodic Arrays of Shunted Piezoelectric Patches

Periodic arrays of shunted, piezoelectric patches are employed to control waves propagating over the surface of plate structures, and corresponding vibrations. The shunted, piezoelectric patches act as sources of impedance mismatch, which gives rise to interference phenomena resulting from the interaction between incident, reflected and transmitted waves. Periodically distributed mismatch zones, i.e., the piezo patches, produce frequency dependent, wave-dynamic characteristics, which include the generation of band gaps, or stop bands in the frequency domain. The extent of induced band gaps depends on the mismatch in impedance generated by each patch. The total impedance mismatch, in turn, is determined by the added mass and stiffness of each patch as well as the shunting electrical impedance. Proper selection of the shunting electric-circuit thus provides control over the attenuation capabilities of the piezo-plate structure, as well as the ability to adapt to changing excitation conditions. Control of wave-propagation attenuation and vibration reduction for plates with periodic, shunted, piezoelectric patches is demonstrated numerically, employing finite-element models of the considered structures