Hydrogenation to convert CO2 to C1 chemicals: Technical comparison of different alternatives by process simulation

Carbon dioxide (CO₂) conversion by catalytic reaction with hydrogen to produce different C1 chemicals is a promising strategy in view of the development of a sustainable chemical industry. In this work, two CO₂ hydrogenation routes are investigated in detail, respectively syngas and formic acid syntheses. Starting from published experimental reaction data, simulation models based on a kinetic analysis were developed and implemented in Aspen Plus process simulator. The two processes are analyzed according to a number of selected technological indicators, comprising CO₂ conversion, specific H₂ consumption, product yield, energy duties, and carbon emissions. To extend our study, three additional CO₂ conversion pathways are considered, respectively methanol, methane, and urea syntheses, whose technological performances were retrieved from similar studies available in the scientific literature. Under the assumption that H₂ is available from renewable sources, our results highlight that CO₂ conversion routes towards fuel compounds (ie, syngas and methane) look particularly appealing from the energy balance point of view. If non-renewable energy is used to produce H₂, the actual environmental benefits (in terms of net CO₂ emissions) strongly depend on the country-specific carbon intensity for electricity generation.     

Targeting Adenosine Receptors: A Potential Pharmacological Avenue for Acute and Chronic Pain

Adenosine is a purine nucleoside, responsible for the regulation of multiple physiological and pathological cellular and tissue functions by activation of four G protein-coupled receptors (GPCR), namely A₁, A_2A, A_2B, and A₃ adenosine receptors (ARs). In recent years, extensive progress has been made to elucidate the role of adenosine in pain regulation. Most of the antinociceptive effects of adenosine are dependent upon A₁AR activation located at peripheral, spinal, and supraspinal sites. The role of A_2AAR and A_2BAR is more controversial since their activation has both pro- and anti-nociceptive effects. A₃AR agonists are emerging as promising candidates for neuropathic pain. Although their therapeutic potential has been demonstrated in diverse preclinical studies, no AR ligands have so far reached the market. To date, novel pharmacological approaches such as adenosine regulating agents and allosteric modulators have been proposed to improve efficacy and limit side effects enhancing the effect of endogenous adenosine. This review aims to provide an overview of the therapeutic potential of ligands interacting with ARs and the adenosinergic system for the treatment of acute and chronic pain.     

Zirconium nano building blocks based on the 3‐butynoic acid ligand: Synthesis and thermomechanical studies of the resulting inorganic–organic hybrid material

A new zirconium nano building block (ZrNBB) was prepared by the reaction of Zirconium tetrapropoxide with 3‐butynoic acid in an alkoxide/acid at a 1 : 3 or 1 : 6 molar ratio. The complex was characterized by FTIR, ¹H‐NMR and ¹³C‐NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, energy‐dispersive X‐ray analysis, and elementary analysis. A spontaneous alkyne‐to‐allene isomerization process was observed for ZrNBB. A bulk sample was also prepared and analyzed via dynamical mechanical spectroscopy in compression mode. The zirconium complex was then embedded in a polymeric matrix by radical copolymerization with vinyl trimethoxysilane. The inorganic–organic hybrid material was chemically and thermally stable. The shear storage modulus and loss modulus were measured to determine the mechanical properties of the material. The preliminary results are presented. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Docosahexaenoic Acid Supplementation during Pregnancy: A Potential Tool to Prevent Membrane Rupture and Preterm Labor

Polyunsaturated fatty acids (PUFAs) are required to maintain the fluidity, permeability and integrity of cell membranes. Maternal dietary supplementation with ω-3 PUFAs during pregnancy has beneficial effects, including increased gestational length and reduced risk of pregnancy complications. Significant amounts of ω-3 docosahexaenoic acid (DHA) are transferred from maternal to fetal blood, hence ensuring high levels of DHA in the placenta and fetal bloodstream and tissues. Fetal DHA demand increases exponentially with gestational age, especially in the third trimester, due to fetal development. According to the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO), a daily intake of DHA is recommended during pregnancy. Omega-3 PUFAs are involved in several anti-inflammatory, pro-resolving and anti-oxidative pathways. Several placental disorders, such as intrauterine growth restriction, premature rupture of membranes (PROM) and preterm-PROM (pPROM), are associated with placental inflammation and oxidative stress. This pilot study reports on a preliminary evaluation of the significance of the daily DHA administration on PROM and pPROM events in healthy pregnant women. Further extensive clinical trials will be necessary to fully elucidate the correlation between DHA administration during pregnancy and PROM/pPROM occurrence, which is related in turn to gestational duration and overall fetal health.     

Carbon nanohorn-based nanofluids: characterization of the spectral scattering albedo

The full characterization of the optical properties of nanofluids consisting of single-wall carbon nanohorns of different morphologies in aqueous suspensions is carried out using a novel spectrophotometric technique. Information on the nanofluid scattering and absorption spectral characteristics is obtained by analyzing the data within the single scattering theory and validating the method by comparison with previous monochromatic measurements performed with a different technique. The high absorption coefficient measured joint to the very low scattering albedo opens promising application perspectives for single-wall carbon nanohorn-based fluid or solid suspensions. The proposed approximate approach can be extended also to other low-scattering turbid media.     

Modelling fluidized bed combustion of high-volatile solid fuels

A model of an atmospheric bubbling fluidized bed combustor operated with high-volatile solid fuel feedings is presented. It aims at the assessment of axial burning profiles along the reactor and of the associated temperature profiles, relevant to combustor performance and operability. The combustor is divided into three sections: the dense bed, the splashing region and the freeboard. Three combustible phases are considered: volatile matter, relatively large non-elutriable char particles and fine char particles of elutriable size. The model takes into account phenomena that assume particular importance with high-volatile solid fuels, namely fuel particle fragmentation and attrition in the bed and volatile matter segregation and postcombustion above the bed. An energy balance on the splashing zone is set up, taking into account volatile matter and elutriated fines postcombustion and radiative and convective heat fluxes to the bed and the freeboard.Results from calculations with a high-volatile biomass fuel indicate that combustion occurs to comparable extents in the bed and in the splashing region of the combustor. Due to volatile matter segregation with respect to the bed, a significant fraction of the heat is released into the splashing region of the combustor and this results in an increase of the temperature in this region. Extensive bed solids recirculation associated to solids ejection/falling back due to bubbles bursting at bed surface promotes thermal feedback from this region to the bed of as much as 80-90% of the heat released by afterburning of volatile matter and elutriated fines. Depending on the operating conditions a significant fraction of the volatile matter may burn in the freeboard or in the cyclone.     

A three-dimensional model of Suppressor Of Cytokine Signalling 1 (SOCS-1)

Suppressor Of Cytokine Signalling 1 (SOCS-1) is one of the proteinsresponsible for the negative regulation of the JAK-STAT pathwaytriggered by many cytokines. This important inhibition involvescomplex formation between SOCS-1 and JAK2, which requires particularstructural domains (KIR, ESS and SH2) on SOCS-1. A three-dimensionaltheoretical model of SOCS-1 is presented here. The model wasgenerated by the application of different modelling techniques,including threading, structure-based modelling, surface analysisand protein docking. The structure accounts for the interactionsbetween SOCS-1 and two other key proteins in the JAK-STAT pathway,namely JAK2 and Elongin BC. The proposed model for the interactionbetween SOCS-1 and JAK2 suggests that the SOCS-1 suppress thekinase activity of JAK2 by obstructing the catalytic grooveof the tyrosine kinase. Subsequent interaction of the JAK–SOCScomplex with Elongin BC was also modelled. A sequence and structuralcomparison between the SH2 domain of SOCS-1 and the SH2 domainsof other proteins highlights key residues that could be responsiblefor SOCS-1 specificity. Currently available mutational dataare evaluated. The results are consistent with the experimentaldata and they provide deeper insights into the inhibitory functionof SOCS-1 at a molecular level.     

Effects of radio frequency and heat on wood bonding with a poly(vinyl acetate) dispersion adhesive

Water‐based poly(vinyl acetate) dispersions are widely used as wood adhesives with dielectric heating systems. However, little is known about the effects of radio frequency (RF) exposure or heat on the adhesive characteristics and on the performances of bonded joints. In this study, the properties of bonded joints exposed to RF were compared with hot pressing and with standard drying, and the observed behavior was explained. Joint characteristics were evaluated by means of both conventional (e.g., shear strength in both dry and wet conditions, etc.) and unconventional (e.g., bondline temperature, moisture content at interface, etc.) procedures, and also selected properties of polymeric film were measured (e.g., water absorption, analysis of the fraction dissolved in water, glass transition temperature [T_g], etc.) to explicate the observed differences. Results evidenced that the effect of both RF and heating was to appreciably speed up the drying process. However, when high values of energetic impulse (owing to both hot pressing and RF) were given to the assemblies, permanent changes were induced into the polymeric glueline. This occurrence was a time‐driven process and reflected mainly on the mechanical performance in wet conditions, which improved appreciably in comparison to the standard reference series. The reason of such behavior was connected to the poly(vinyl alcohol) phase present inside the polymer, and a role was also assigned to AlCl₃, used as complexing agent of the polymeric protective colloid. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Gene Expression Profiling as a Tool to Investigate the Molecular Machinery Activated during Hippocampal Neurodegeneration Induced by Trimethyltin (TMT) Administration

Trimethyltin (TMT) is an organotin compound exhibiting neurotoxicant effects selectively localized in the limbic system and especially marked in the hippocampus, in both experimental animal models and accidentally exposed humans. TMT administration causes selective neuronal death involving either the granular neurons of the dentate gyrus or the pyramidal cells of the Cornu Ammonis, with a different pattern of localization depending on the different species studied or the dosage schedule. TMT is broadly used to realize experimental models of hippocampal neurodegeneration associated with cognitive impairment and temporal lobe epilepsy, though the molecular mechanisms underlying the associated selective neuronal death are still not conclusively clarified. Experimental evidence indicates that TMT-induced neurodegeneration is a complex event involving different pathogenetic mechanisms, probably acting differently in animal and cell models, which include neuroinflammation, intracellular calcium overload, and oxidative stress. Microarray-based, genome-wide expression analysis has been used to investigate the molecular scenario occurring in the TMT-injured brain in different in vivo and in vitro models, producing an overwhelming amount of data. The aim of this review is to discuss and rationalize the state-of-the-art on TMT-associated genome wide expression profiles in order to identify comparable and reproducible data that may allow focusing on significantly involved pathways.