Chemical functionalization of graphene surface as filler for rubber compounds

Over the last few years, the surface modification of fillers for high-level technological applications such as polymer composites for tyre industry, conductive inks and coatings has seen a considerable increase in interest since it can increase mechanical, electrical, and thermal properties of the final material. Nano-sized carbon allotropes such as graphene and carbon nanotubes are a suitable class of compounds for these purposes: high thermal and electrical conductivity along with considerable mechanical reinforcement are the main improvements that these fillers bring to the composite and their elevated surface area allows to reduce the filler volume ratio compared to more common alternatives. An efficient and reliable method to modify the surface of these nano-fillers is the so-called pyrrole methodology, a mild procedure that involves bio-sourced reagents to introduce functional groups on the graphitic planes and that has been recently employed in the fabrication of elastomeric composites with improved mechanical properties. In order to understand the mechanism beneath the interaction between the pyrrole and the substrate and thus the behavior of the functionalized filler, a more in-depth analysis is requested. A theoretical work based on molecular dynamics simulations and a DFT study were performed in order to investigate the interaction energy, the geometry of interaction and the mobility of N-substituted pyrrole molecules adsorbed on the graphene planes. This theoretical study at atomistic level can help design a new class of high-performance fillers by better understanding the interaction mechanism given the important role of supramolecular interactions

Anharmonic calculations of vibrational spectra for molecular adsorbates: A divide-and-conquer semiclassical molecular dynamics approach

The vibrational spectroscopy of adsorbates is becoming an important investigation tool for catalysis and material science. This paper presents a semiclassical molecular dynamics method able to reproduce the vibrational energy levels of systems composed by molecules adsorbed on solid surfaces. Specifically, we extend our divide-and-conquer semiclassical method for power spectra calculations to gas-surface systems and interface it with plane-wave electronic structure codes. The Born-Oppenheimer classical dynamics underlying the semiclassical calculation is full dimensional, and our method includes not only the motion of the adsorbate but also those of the surface and the bulk. The vibrational spectroscopic peaks related to the adsorbate are accounted together with the most coupled phonon modes to obtain spectra amenable to physical interpretations. We apply the method to the adsorption of CO, NO, and H2O on the anatase-TiO2 (101) surface. We compare our semiclassical results with the single-point harmonic estimates and the classical power spectra obtained from the same trajectory employed in the semiclassical calculation. We find that CO and NO anharmonic effects of fundamental vibrations are similarly reproduced by the classical and semiclassical dynamics and that H2O adsorption is fully and properly described in its overtone and combination band relevant components only by the semiclassical approach

Transition metal nanoparticles on pyrrole-decorated sp2 carbon allotropes for selective hydrogen isotopic exchange

Compared to homogeneous catalysts, heterogeneous systems possess more attractiveness in the chemical industry because of the easier separation from the reaction products, lower amount of wastes, larger recyclability and lower toxicity and corrosiveness. Preparation of supported metal nanoparticles often requires energy demanding techniques such as laser ablation, electrochemical reduction, and high temperature heat treatments. In this work we present a facile and sustainable method to functionalize multi-walled carbon nanotubes (MWCNTs) and exploit the novel surface reactivity to deposit Ruthenium nanoparticles. Serinol pyrrole (SP) was synthesized and, through a Domino reaction, grafted on carbon nanotubes’ surface. Mild reducing conditions were employed to decorate CNT-SP with Ruthenium nanoparticles. The latter adduct was characterized by means of X-ray diffraction and transmission electron microscopy. Ru/CNT-SP was then tested in the selective deuteration of quinoline. High selectivity and conversion, determined through H-NMR, were achieved compared to commercial Ru/C catalysts. The results obtained in this work led to the filing of two patent applications

Transition metal nanoparticles on pyrrole-decorated sp2 carbon allotropes for selective hydrogen isotopic exchange

Compared to homogeneous catalysts, heterogeneous systems possess more attractiveness in the chemical industry because of the easier separation from the reaction products, lower amount of wastes, larger recyclability, and lower toxicity and corrosiveness. Objective of this research was to prepare more efficient and more selective heterogeneous catalysts, by anchoring transition metal cations and nanoparticles on nitrogen decorated sp2 carbon allotrope (CA), which were functionalized with pyrrole compounds. Triethylenetetramine pyrrole (TETAP) was selected as the pyrrole compound: it was synthesized and grafted onto multiwalled carbon nanotubes and high surface area graphite with efficient and viable methodology. The CA/TEPAP adduct was used as the support of transition metal nanoparticles. It is here reported the example of ruthenium supported catalyst, investigated by means of elemental and surface area analyses, X-ray diffraction, transmission electron microscopy. The catalyst was used for the Hydrogen Isotopic Exchange (HIE) of aromatic compounds of pharmaceutical interest. Outstanding selectivity was obtained

Difference between stable and exotic nuclei: medium polarization effects

The bare NN-potential, parametrized so as to reproduce the nuclear phase shifts leads to a sizable Cooper pair binding energy in nuclei along the stability valley. It is a much debated matter whether this value accounts for the "empirical" value of the pairing gap or whether a similarly important contribution arises from the exchange of collective vibrations between Cooper pair partners. In keeping with the fact that two-particle transfer reactions are the specific probe of pairing in nuclei, and that exotic halo nuclei like 11Li are extremely polarizable, we find that the recent studied reaction, namely 11Li+p -> 9Li+t, provides direct evidence of phonon mediated pairing in nuclei

Copper Single Atoms Chelated on Ligand-Modified Carbon for Ullmann-type C−O Coupling

Cross-coupling reactions are of great importance in chemistry due to their ability to facilitate the construction of complex organic molecules. Among these reactions, the Ullmann-type C−O coupling between phenols and aryl halides is particularly noteworthy and useful for preparing diarylethers. However, this reaction typically relies on homogeneous catalysts that rapidly deactivate under harsh reaction conditions. In this study, we introduce a novel heterogeneous catalyst for the Ullmann-type C−O coupling reaction, comprised of isolated Cu atoms chelated to a tetraethylenepentamine-pyrrole ligand that is immobilized on graphite nanoplatelets. The catalytic study reveals the recyclability of the material, and demonstrates the crucial role of the pyrrole linker in stabilizing the Cu sites. The work expands the potential of single-atom catalyst nanoarchitectures and underscores the significance of ligands in stabilizing metals in cationic forms, providing a novel, tailored catalyst for cross-coupling chemistries

Precision-based exercise as a new therapeutic option for children and adolescents with haematological malignancies

Children and adolescents with haematological malignancies (pedHM) are characterized by a severe loss of exercise ability during cancer treatment, lasting throughout their lives once healed and impacting their social inclusion prospects. The investigation of the effect of a precision-based exercise program on the connections between systems of the body in pedHM patients is the new frontier in clinical exercise physiology. This study is aimed at evaluating the effects of 11 weeks (3 times weekly) of combined training (cardiorespiratory, resistance, balance and flexibility) on the exercise intolerance in PedHM patients. Two-hundred twenty-six PedHM patients were recruited (47% F). High or medium frequency participation (HAd and MAd) was considered when a participant joined; > 65% or between 30% and < 64% of training sessions, respectively. The \u201cup and down stairs\u2019\u2019 test (TUDS), \u201c6 min walking\u201d test (6MWT), the \u201c5 Repetition Maximum strength\u201d leg extension and arm lateral raise test (5RM-LE and 5RM-ALR), flexibility (stand and reach), and balance (stabilometry), were performed and evaluated before and after training. The TUDS, the 5RM-LE and 5RM-ALR, and the flexibility exercises showed an increase in HAd and MAd groups (P < 0.05), while the 6MWT and balance tests showed improvement only in HAd group (P < 0.0001). these results support the ever\u2010growing theory that, in the case of the treatment of PedHM, \u2018exercise is medicine\u2019 and it has the potential to increase the patient\u2019s chances of social inclusion

Peripheral Arterial and Venous Response to Tilt Test after a 60-Day Bedrest with and without Countermeasures (ES-IBREP)

We quantified the impact of 60-day head-down bed rest (HDBR) with countermeasures on arterial and venous response to tilt. Methods: Twenty-one males: 7 control (Con), 7 resistive vibration exercise (RVE) and 7 Chinese herb (Herb) were assessed. Subjects were identified as finisher (F) or non-finishers (NF) at the post-HDBR 20-min tilt test. The cerebral (MCA), femoral (FEM) arterial flow velocity and leg vascular resistance (FRI), the portal vein section (PV), the flow redistribution ratios (MCA/FEM; MCA/PV), the tibial (Tib), gastrocnemius (Gast), and saphenous (Saph) vein sections were measured by echography and Doppler ultrasonography. Arterial and venous parameters were measured at 3-min pre-tilt in the supine position, and at 1 min before the end of the tilt. Results: At post-HDBR tilt, MCA decreased more compared with pre-HDBR tilt in the Con, RVE, and Herb groups, the MCA/FEM tended to decrease in the Con and Herb groups (not significant) but remained stable in the RVE gr. FRI dropped in the Con gr, but remained stable in the Herb gr and increased in the RVE gr. PV decreased less in the Con and Herb groups but remained unchanged in the RVE gr. MCA/PV decreased in the Con and Herb groups, but increased to a similar extent in the RVE gr. Gast section significantly increased more in the Con gr only, whereas Tib section increased more in the Con and Herb groups but not in the RVE gr. The percent change in Saph section was similar at pre- and post-HDBR tilt. Conclusion: In the Con gr, vasoconstriction was reduced in leg and splanchnic areas. RVE and Herb contributed to prevent the loss of vasoconstriction in both areas, but the effect of RVE was higher. RVE and Herb contributed to limit Gast distension whereas only RVE had a protective effect on the Tib

Magnetic resonance imaging (MRI) contrast agents for tumor diagnosis

10.1260/2040-2295.4.1.23Journal of Healthcare Engineering4123-4

Chemical functionalization of graphene surface with pyrrole compounds. Modeling of supramolecular interactions

In the last decade, the surface modification of fillers for high-level technological applications such as polymer composites for tyre industry has seen a considerable increase in interest since it can boost the properties of the final material. Nano-sized carbon allotropes such as graphene and carbon nanotubes are a suitable class of compounds for these purposes: high thermal and electrical conductivity along with considerable mechanical reinforcement are the main enhancements that these fillers bring to the composite and their elevated surface area allows to reduce the filler volume ratio compared to more common alternatives. An efficient and reliable procedure to tweak the surface of these nano-fillers is the so-called pyrrole methodology, [1] a mild procedure that involves bio-sourced reagents to introduce functional groups on the graphitic planes and that has been recently employed in the fabrication of elastomeric composites with improved mechanical properties [2]. In order to understand the mechanism beneath the interaction between the pyrrole and the substrate and thus the behavior of the functionalized filler, a more in-depth analysis is requested. A theoretical work based on molecular dynamics simulations and a DFT study were performed to investigate the interaction energy, the geometry of interaction and the mobility of N-substituted pyrrole molecules adsorbed on the graphene planes. This theoretical study at atomistic level can help design a new class of high-performance fillers by better understanding the interaction mechanism [3] given the important role of supramolecular interactions. Results N-substituted pyrroles and pyrrolidines with increasing carbon atoms in the substituent alkyl chain were adsorbed on a pristine graphene surface. Two main stabilizing effects were found to be relevant: pyrrole sp2 configuration allowed π-π bonding with the graphene surface and longer alkyl chains promoted dispersion interactions. Molecular dynamics was then used to study the behavior of 20 molecules of different pyrroles. Polarity of the nitrogen substituent and temperature were found to be central for the spreading of the substances on the graphene surface