An investigation into sintering of PA6 nanocomposite powders for rotational molding

The objective of this work is to study the sintering behavior of polyamide 6 (PA6) powders and PA6 nanocomposites by means of thermomechanical (TMA) and dimensionless analysis in view of its technological application in rotational molding. TMA analysis was used to monitor the bulk density evolution of PA6 powders and PA6 nanocomposites when heated above the melting temperature. Experimental TMA results indicate that the sintering of PA6 and PA6 nanocomposites occurs in two different steps, namely powder coalescence and void removal. Furthermore, TMA analysis showed that relevant degradation phenomena occur during the sintering of PA6 and PA6 nanocomposites, leading to gas formation in the molten polymer. The suitability of these materials in rotational molding was then assessed by defining a processing window, as the temperature difference between the endset sintering and the onset degradation. The heating rate dependence of the processing window was explained by means of dimensionless analysis, showing that powder coalescence is influenced by the viscosity evolution of the matrix, whereas void removal is influenced by the gas diffusivity inside the molten matrix. Therefore, the diffusion activation energy correlates the endset sintering temperature to the heating rate. On the other hand, the onset degradation temperature depends on the heating rate, due to the characteristic activation energy of the degradation process. Accordingly, the width of the processing window mainly depends on the values of the activation energies for diffusivity and degradation. The width of the processing window for neat PA6 was found to be too narrow to candidate this polymer for rotational molding. The addition of nanofiller causes a narrowing of the processing window, whereas the PA6 matrix modified with a thermal stabilizer showed a sufficiently broad processing window, compatible for use in rotational molding.     

Divisor class group and canonical class of rings defined by ideals of pfaffians

In this paper we study the rings defined by ideals of pfaffians of a skew symmetric matrix of indeterminates. We analyze the case in which the pfaffians are not necessarily of fixed size. We prove that such rings are Cohen-Macaulay normal domains and we compute the divisor class group and the canonical class. It allows us to determine which of our rings are Gorenstein.     

Self-assembly and branching of sucrose stabilized silver nanoparticles by microwave assisted synthesis: From nanoparticles to branched nanowires structures

Silver nanostructures were synthesized under microwave irradiation from a solution of silver nitrate and sucrose, with any other reducing or capping agent. The size and morphology of nanostructures changed continuously during the irradiation time. The obtained nanostructures at the different irradiation time were characterized by X-Ray diffraction, UV–vis spectroscopy, scanning and transmission electron microscopy and selected area diffraction pattern. It was evidenced that initially Ag nanoparticles were formed, which, as reaction time elapsed, self-assembled and fused with each other to yield nanowires and further branched nanowires. The formation of the silver branched nanostructures can be explained as a process of initial reduction–nucleation–adsorption–growth–branching growth.     

A new pilot flow reactor for high-intensity ultrasound irradiation. Application to the synthesis of biodiesel

In recent years, chemistry in flowing systems has become more prominent as a method of carrying out chemical transformations, ranging in scale from microchemistry up to kilogram-scale processes. Compared to classic batch ultrasound reactors, flow reactors stand out for their greater efficiency and flexibility as well as lower energy consumption. This paper presents a new ultrasonic flow reactor developed in our laboratory, a pilot system well suited for reaction scale up. This was applied to the transesterification of soybean oil with methanol for biodiesel production. This reaction is mass-transfer-limited initially because the two reactants are immiscible with each other, then because the glycerol phase separates together with most of the catalyst (Na or K methoxide). In our reactor a mixture of oil (1.6 L), methanol and sodium methoxide 30% in methanol (wt/wt ratio 80:19.5:0.5, respectively) was fully transesterified at about 45 °C in 1 h (21.5 kHz, 600 W, flow rate 55 mL/min). The same result could be achieved together with a considerable reduction in energy consumption, by a two-step procedure: first a conventional heating under mechanical stirring (30 min at 45 °C), followed by ultrasound irradiation at the same temperature (35 min, 600 W, flow rate 55 mL/min).Our studies confirmed that high-throughput ultrasound applications definitively require flow reactors.     

Ginger,a Possible Candidate for the Treatment of Dementias?

As the human life expectancy increases, age-linked diseases have become more and more frequent. The worldwide increment of dementia cases demands medical solutions, but the current available drugs do not meet all the expectations. Recently the attention of the scientific community was attracted by natural compounds, used in ancient medicine, known for their beneficial effects and high tolerability. This review is focused on Ginger (Zingiber officinale) and explore its properties against Alzheimer’s Disease and Vascular Dementia, two of the most common and devastating forms of dementia. This work resumes the beneficial effects of Ginger compounds, tested in computational in vitro and in vivo models of Alzheimer’s Disease and Vascular Dementia, along with some human tests. All these evidences suggest a potential role of the compounds of ginger not only in the treatment of the disease, but also in its prevention.     

Recruitment of monocytes primed to express heme oxygenase-1 ameliorates pathological lung inflammation in cystic fibrosis

Overwhelming neutrophilic inflammation is a leading cause of lung damage in many pulmonary diseases, including cystic fibrosis (CF). The heme oxygenase-1 (HO-1)/carbon monoxide (CO) pathway mediates the resolution of inflammation and is defective in CF-affected macrophages (MΦs). Here, we provide evidence that systemic administration of PP-007, a CO releasing/O₂ transfer agent, induces the expression of HO-1 in a myeloid differentiation factor 88 (MyD88) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)-dependent manner. It also rescues the reduced HO-1 levels in CF-affected cells induced in response to lipopolysaccharides (LPS) or Pseudomonas aeruginosa (PA). Treatment of CF and muco-obstructive lung disease mouse models with a single clinically relevant dose of PP-007 leads to effective resolution of lung neutrophilia and to decreased levels of proinflammatory cytokines in response to LPS. Using HO-1 conditional knockout mice, we show that the beneficial effect of PP-007 is due to the priming of circulating monocytes trafficking to the lungs in response to infection to express high levels of HO-1. Finally, we show that PP-007 does not compromise the clearance of PA in the setting of chronic airway infection. Overall, we reveal the mechanism of action of PP-007 responsible for the immunomodulatory function observed in clinical trials for a wide range of diseases and demonstrate the potential use of PP-007 in controlling neutrophilic pulmonary inflammation by promoting the expression of HO-1 in monocytes/macrophages.Subject terms: Innate immune cells, Diseases     

Inosine in Neurodegenerative Diseases: From the Bench to the Bedside

Neurodegenerative diseases, such as Alzheimer′s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), currently represent major unmet medical needs. Therefore, novel therapeutic strategies are needed in order to improve patients’ quality of life and prognosis. Since oxidative stress can be strongly involved in neurodegenerative diseases, the potential use of inosine, known for its antioxidant properties, in this context deserves particular attention. The protective action of inosine treatment could be mediated by its metabolite urate. Here, we review the current preclinical and clinical studies investigating the use of inosine in AD, PD, ALS, and MS. The most important properties of inosine seem to be its antioxidant action and its ability to raise urate levels and to increase energetic resources by improving ATP availability. Inosine appears to be generally safe and well tolerated; however, the possible formation of kidney stones should be monitored, and data on its effectiveness should be further explored since, so far, they have been controversial. Overall, inosine could be a promising potential strategy in the management of neurodegenerative diseases, and additional studies are needed in order to further investigate its safety and efficacy and its use as a complementary therapy along with other approved drugs.     

X‐ray fluorescence analysis on a group of coins from the ancient roman city of Tridentum (Trento,Italy)

A group of 83 coins, found in the archeological excavations of the ancient Roman city of Tridentum (Trento, Italy), was studied for the determination of their composition, finalized to their classification and cataloging. The coins, mainly made of copper‐based alloys, were minted between the republican period (II century BC) and the last decades of the western empire (V century AD). The X‐Ray Fluorescence archaeometric analysis has allowed a revision of the typological classification of the coins through the identification of six broad groups, each one characterized by a peculiar composition of the coins in the group. A tentative assignation of all the unreadable coins to one of the groups identified was proposed, in a way that could suggest also a possible dating of these coins. Copyright © 2014 John Wiley & Sons, Ltd.     

New Experimental and Mechanistic Investigation on the KSCN‐H2O2‐NaOH‐Cu(II)‐Catalyzed Oscillating System (Orbàn–Epstein Reaction): Inhibitory Effects by Diphenols

The KSCN‐H₂O₂‐NaOH‐Cu(II)‐catalyzed system is one of the few reactions in which chemical oscillations can be observed in batch conditions. In the present paper, this oscillating reaction was revisited in a wide range of initial concentrations of all components in batch. A mixture with a long lasting oscillation time (1 h 34 min) and a great number of oscillations (24) was found and used to investigate the effect of temperature. An Arrhenius‐type temperature dependence was observed from which an apparent “average activation energy” E_av = 76 ± 5 kJ for the overall oscillatory reaction was observed. A mechanistic study based on a modified model analyzed by the stoichiometric network analysis approach gave a satisfactory agreement between calculated and experimental oscillating behaviors and temperature dependence. The addition of the three diphenols (catechol, resorcinol, and hydroquinone) causes perturbations similar to those observed in the Briggs‐Rauscher oscillating system, i.e., an inhibition of the oscillatory regime. These inhibitory effects were described in detail, and a reasonable qualitative interpretation is given.