Chemical Bonding by the Chemical Orthogonal Space of Reactivity

The fashionable Parr–Pearson (PP) atoms-in-molecule/bonding (AIM/AIB) approach for determining the exchanged charge necessary for acquiring an equalized electronegativity within a chemical bond is refined and generalized here by introducing the concepts of chemical power within the chemical orthogonal space (COS) in terms of electronegativity and chemical hardness. Electronegativity and chemical hardness are conceptually orthogonal, since there are opposite tendencies in bonding, i.e., reactivity vs. stability or the HOMO-LUMO middy level vs. the HOMO-LUMO interval (gap). Thus, atoms-in-molecule/bond electronegativity and chemical hardness are provided for in orthogonal space (COS), along with a generalized analytical expression of the exchanged electrons in bonding. Moreover, the present formalism surpasses the earlier Parr–Pearson limitation to the context of hetero-bonding molecules so as to also include the important case of covalent homo-bonding. The connections of the present COS analysis with PP formalism is analytically revealed, while a numerical illustration regarding the patterning and fragmentation of chemical benchmarking bondings is also presented and fundamental open questions are critically discussed.     

One-step synthesis of graphene supported platinum nanoparticles as electrocatalyst for PEM fuel cells

Here in, we describe an ultrafast, single-step microwave irradiation route (MW) to prepare graphene supported Pt nanoparticles, during which the small Pt nanoparticles are distributed uniformly on a reduced graphene oxide surface. This route provides evident advantages namely low cost, easiness, low time consuming and high yield in comparison to actual chemical methods to develop efficient Pt/rGO catalyst with Pt content close to state-of-the-art commercial composition. The structure and composition of prepared samples have been studied by specific techniques, while the electrocatalytic stability has been studied using ex-situ and in-situ measurements. High performance and electrochemically stable catalyst for PEM fuel cells was developed using the sample with highest loading and good dispersion. The fabricated Pt-rGO-based MEA was investigated for durability under fuel starvation in comparison with commercial Pt/C-based MEA. The electrocatalytic activity was investigated and the electrochemical response revealed the higher stability during accelerated degradation test under fuel starvation in comparison with commercial Pt/C. This study promotes the applicability of described preparation method to noble or transition metal nanoparticles embedded on graphene-based materials.     

Surface Chemistry Dictates the Osteogenic and Antimicrobial Properties of Palladium-, Platinum-, and Titanium-Based Bulk Metallic Glasses

Titanium alloys are commonly used as biomaterials in musculoskeletal applications, but their long-term efficacy can be limited by wear and corrosion, stress shielding, and bacterial colonization. As a promising alternative, bulk metallic glasses (BMGs) offer superior strength and corrosion resistance, but the influence of their chemical composition on their bioactivity remains largely unexplored. This study, therefore, aims to examine how the surface chemistry of palladium (Pd)-, platinum (Pt)-, and titanium (Ti)-based BMGs can steer their response to biological systems. The chemical composition of BMGs governs their thermophysical and mechanical properties, with Pd-based BMGs showing exceptional glass-forming ability suitable for larger implants, and all BMGs exhibiting a significantly lower Young's modulus than Ti-6Al-4 V (Ti64), suggesting a potential to reduce stress shielding. Although BMGs feature copper depletion at the near surface, their surface chemistry remains more stable than that of Ti64 and supports blood biocompatibility. Fibrin network formation is heavily dependent on BMGs’ chemical composition and Ti-based BMGs support thicker fibrin network formation than Ti64. Furthermore, BMGs outperform Ti64 in promoting mineralization of human bone progenitor cells and demonstrate antimicrobial properties against Staphylococcus aureus in a surface chemistry-dependent manner, thereby indicating their great potential as biomaterials for musculoskeletal applications.     

Synthesis and characterization of a titanium phosphate-tellurite glass for Faraday rotators

This work is focused on investigation of thermal, structural, optical, magnetic, and magneto-optical properties of novel titanium phosphate-tellurite glass applied as Faraday rotators. The glass belonging to the system 35Li₂O–10Al₂O₃–5TiO₂–45P₂O₅–5TeO₂ was prepared by a nonconventional wet route of raw materials processing, followed by melting-quenching-annealing steps. Some important physical properties of the investigated glass have been measured and calculated, providing knowledge related to glass compactness, electronic structure, glass forming capability, etc. XRD analysis evidenced an amorphous network structure of the investigated glass. The optical absorption in the Vis domain is mainly due to Ti³⁺ ions and Te₂ clusters formed during the glass melting process. A relatively low optical absorption is noticed over 600 nm that activates a significant Faraday magneto-optical effect. Photoluminescence bands in the blue, red, and infrared domains are observed, caused by Te₂ clusters formed during the glass melting process. The magnetization in dependency on applied magnetic field reveals a complex behavior of the glass, depending on temperature. Thus, it is found a ferromagnetic behavior up to 2000 Oe, a paramagnetic component up to 40 000 Oe, followed by a diamagnetic one over 40 000 Oe. Faraday rotation angle and Verdet constant values in the visible domain are correlated with the reduced TeO₂ content of the glass.     

Debonding of cellular structures with fibre-reinforced cell walls under shear deformation

Many natural structures are cellular solids at millimetre scale and fibre-reinforced composites at micrometre scale. For these structures, mechanical properties are associated with cell strength, and phenomena such as cell separation through debonding of the middle lamella in cell walls are key in explaining some important characteristics or behaviour. To explore such phenomena, we model cellular structures with non-linear hyperelastic cell walls under large shear deformations, and incorporate cell wall material anisotropy and unilateral contact between neighbouring cells in our models. Analytically, we show that, for two cuboid walls in unilateral contact and subject to generalised shear, gaps can appear at the interface between the deforming walls. Numerically, when finite element models of periodic structures with hexagonal cells are sheared, significant cell separation is captured diagonally across the structure. Our analysis further reveals that separation is less likely between cells with high internal cell pressure (e.g. in fresh and growing fruit and vegetables) than between cells where the internal pressure is low (e.g. in cooked or ageing plants).     

Calcium carbonate and wood reinforced hybrid PVC composites

In this article, poly(vinyl chloride) (PVC) sandwich‐structured hybrid composites with amorphous calcium carbonate and wood‐filled cores were obtained by compression molding. It has been determined that wood addition up to a weight ratio of 33% reported to the total filler amount is beneficial in improving both the inter‐filler and filler‐matrix interfacial adhesion, which alongside with the promoting of the amorphous PVC matrix crystallization is responsible for an increase up to 34% in the flexural strength of the composites, compared to unfilled PVC. The hybrid filled composites present up to 35% lower friction coefficients and up to 20% higher Brinell hardness values than the composites filled with calcium carbonate alone. Subsequently, wood addition determines an increase in the oxidation onset temperature for PVC and an increase with up to 20% in the sound and thermal‐insulative properties of the composites, compared to unfilled PVC. The dominating dispersive part of the composites surface energy aids in improving the mass and dimensional stability of the assembly to both water and dilute hydrochloric acid aqueous solutions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46317.     

Synthesis of polysulfone block copolymers containing polydimethylsiloxane

The synthesis of polysulfone-polydimethylsiloxane (PSU-PDMS)linear block copolymers has been carried out in solution by condensation of chloro-terminated bisphenol A, diphenylsulfone and , -di (hydrogensilyl)-polydimethylsiloxane with Si–C bond. ¹H-NMR spectra of the block copolymers allow the estimation of siloxane and polysulfone ratio. The molecular weight of the polysulfone and polysiloxane oligomers and the block copolymers was determined by GPC. Thermogravimetric analysis indicates a thermal stability of block copolymers up to 400°C and allows estimation of the process activation energy. Microphase separation of the block copolymers was observed by differential scanning calorimetry (DSC).     

Quantum particles on graphenic systems. Part 1. roadmap for semiconductor based graphenes

Advances in green nano-technologies is the main field under which the present paper series is firstly envisaged; therefore, advanced, research-progressive nano-science is aimed to shorten the distance from fundamental concepts to applications, devices and their implementations. It however would gather both physics and chemistry fundamental and applicative fields in dealing with solar/black body radiation as well as with new materials based on inorganic-organic hybrids, composites and electron quantum features (excitons, bondons, diffusion, electrical circuits, semiconductors, quantum dots, etc.). Such research is therefore equally highly necessary for both communities (physical engineering and chemical engineering) enlightening the dedicated international forums on quantum-dots based solar cells, as well as for giving further impetus to this new field of photovoltaics by gathering active international scientists in solar energy. The present paper offers a review on the progresses regarding the application of defective graphene and other defect-doped carbon nanostructures in the construction of solar cells devices towards introducing the semiconductor based graphenes. Competitiveness and eco-ecological aspects of such projects are also considered in a resumed scientific and innovative research.     

Optimizing at the end-points the Akima's interpolation method of smooth curve fitting

In this paper we propose an optimized version, at the end-points, of the Akima's interpolation method for experimental data fitting. Comparing with the Akima's procedure, the error estimate, in terms of the modulus of continuity, is improved. Similarly, we optimize at the end points the Catmull–Rom's cubic spline. The properties of the obtained splines are illustrated on a numerical experiment.