Time evolution of the classical and quantum mechanical versions of diffusive anharmonic oscillator: an example of Lie algebraic techniques

We present the general solutions for the classical and quantum dynamics of the anharmonic oscillator coupled to a purely diffusive environment. In both cases, these solutions are obtained by the application of the Baker-Campbell-Hausdorff (BCH) formulas to expand the evolution operator in an ordered product of exponentials. Moreover, we obtain an expression for the Wigner function in the quantum version of the problem. We observe that the role played by diffusion is to reduce or to attenuate the the characteristic quantum effects yielded by the nonlinearity, as the appearance of coherent superpositions of quantum states (Schr?dinger cat states) and revivals.     

Synthesis, photophysical studies and anticancer activity of a new halogenated water-soluble porphyrin

A water-soluble halogenated porphyrin, namely 5,10,15,20-tetrakis(2-chloro-3-sulfophenyl)porphyrin (TCPPSO(3)H), was prepared and evaluated as sensitizer for photodynamic therapy (PDT). Photophysical properties of TCPPSO(3)H, such as high photostability, long triplet lifetime and high singlet oxygen quantum yield suggest high effectiveness of this class of halogenated porphyrins in PDT. TCPPSO(3)H is non-toxic in the dark and causes a significant photodynamic effect examined against MCF7 (human breast carcinoma), SKMEL 188 (human melanoma) and S91(mouse melanoma) cell lines upon red light irradiation (cutoff < 600 nm) at low light doses. Time-dependent cellular uptake of TCPPSO(3)H reached plateau at 120 min and was the highest for S91, 20% lower for MCF7 and 70% lower for SKMEL 188. Our results show that this halogenated water-soluble porphyrin is an efficient photosensitizer and reveal the potential of this class of compounds as PDT agents.     

An empirical model to predict soil bulk density profiles in field conditions using penetration resistance, moisture content and soil depth

Cylindrical soil probes measuring 300 mm in diameter by 300 mm in height were prepared in the laboratory using samples extracted from a well drained loamy soil (FAO classification: Vertic Luvisol). These probes were compacted at different moisture contents [3, 6, 9, 12, 15 and 18 (% w/w)] and using different compaction energies (9.81, 49.05, 98.1 and 981 J). The soil penetration resistance was determined by means of the ASAE 129 mm² base area cone and seven other different cones with base sizes of 175, 144, 124, 98, 74, 39 and 26 mm². The variability of the penetration resistance measurements increased as the size of the cone decreased. Nevertheless, the penetration resistance values proved to be independent of the cone used, as long as the size of the latter was equal to or greater than 98 mm². This confirms the possibility of using cones with areas smaller than the ASAE standard when measurements are to be carried out in dry soils with high levels of mechanical resistance. The experimental data were used to develop an empirical model, a linear additive model on a log–log plane, capable of estimating soil bulk density depending on soil penetration resistance, soil moisture content and depth. This model has provided good results under field conditions and has allowed soil bulk density profiles and accumulated water profiles to be accurately estimated.     

Theoretical and Experimental Investigation of the Production of PMMA-Based Bone Cement

Poly(methyl methacrylate) (PMMA)-based polymers have been extensively used for manufacturing of artificial bone cements for treatment of osteoporosis. A typical bone cement recipe contains methyl methacrylate, which polymerizes in situ during cement application. An inherent problem of this reaction is the high amount of heat released during the cement preparation, which may lead to irreparable damage of living tissues. Optimization of PMMA-based bone cement (PMMABC) recipes is thus an important step towards safe and reliable clinical usage of these materials. A theoretical and experimental investigation is performed here to unveil the influence of some preparation variables on the production of PMMABC and to allow for future optimization of the PMMABC recipe. It is shown that the degree of mixing of the components of the recipe plays a fundamental role on the development of the temperature profile. For this reason, the PMMABC obtained with the in-situ blending of PMMA and barium sulfate during the suspension polymerization leads to much better homogeneity of the final test pieces and improved control of the temperature profile.     

Modeling protein binding and elution over a chromatographic surface probed by surface plasmon resonance

Surface plasmon resonance (SPR) spectroscopy is used as a scaled-down, analytical, pseudo-chromatography tool for analyzing protein binding and elution over an ion-exchange surface under cyclic sorption conditions. A micrometric-scale adsorption surface was produced by immobilizing a typical ion exchange ligand – diethylaminoethyl (DEAE) – onto commercially available planar gold sensor chip surfaces pre-derivatized with a self-assembled monolayer of 11-mercaptoundecanoic acid with known density. An explicit mathematical formulation is provided for the deconvolution and interpretation of the SPR sensorgrams. An adsorption rate model is proposed to describe the SPR sensorgrams for bovine serum albumin, used here as model protein, when the DEAE surface is subjected to a cyclic series of binding and elution steps. Overall, we demonstrate that the adsorption rate model is capable of quantitatively describing BSA binding and elution for protein titers from dilute conditions up to overloaded conditions and a broad range of salt concentrations.     

Modern Methods for the Sustainable Synthesis of Metalloporphyrins

Metalloporphyrins are involved in many and diverse applications that require the preparation of these compounds in an efficient manner, which nowadays, also involves taking into consideration sustainability issues. In this context, we use ball milling mechanochemistry and sonochemistry for the rational development of synthetic strategies for the sustainable preparation of metalloporphyrins. Zinc, copper, cobalt and palladium complexes of hydrophobic porphyrins were obtained in high yields and under mechanical action with a moderate excess of the metal salt, without any solvent or additive. Sonochemistry prove to be a good alternative for the preparation of metal complexes of water-soluble porphyrins in good yields and short reaction times. Both strategies have good sustainability scores, close to the ideal values, which is useful in comparing and helping to choose the more adequate method.     

Activation of surface hydroxyl groups by modification of H-terminated Si(111) surfaces

Chemical functionalization of semiconductor surfaces, particularly silicon oxide, has enabled many technologically important applications (e.g., sensing, photovoltaics, and catalysis). For such processes, hydroxyl groups terminating the oxide surface constitute the primary reaction sites. However, their reactivity is often poor, hindering technologically important processes, such as surface phosphonation requiring a lengthy postprocessing annealing step at 140 °C with poor control of the bonding geometry. Using a novel oxide-free surface featuring a well-defined nanopatterned OH coverage, we demonstrate that hydroxyl groups on oxide-free silicon are more reactive than on silicon oxide. On this model surface, we show that a perfectly ordered layer of monodentate phosphonic acid molecules is chemically grafted at room temperature, and explain why it remains completely stable in aqueous environments, in contrast to phosphonates grafted on silicon oxides. This fundamental understanding of chemical activity and surface stability suggests new directions to functionalize silicon for sensors, photovoltaic devices, and nanoelectronics.     

Synthesis of Ortho-alkoxy-aryl Carboxamides via Palladium-Catalyzed Aminocarbonylation

Various aryl carboxamides with alkoxy substituents at the ortho-position, applicable as direct intermediates toward novel ligands, were synthesised via aminocarbonylation of aryl-iodides (2-iodoanisole, 5-chloro-7-iodo-8-methoxy-quinoline, and 5-chloro-7-iodo-8-benzyloxy-quinoline) in the presence of in situ generated palladium(0) catalysts. Simple primary and secondary amines as well as aminoacid esters were used as N-nucleophiles. The optimization of the reaction conditions allowed the preferential formation of carboxamides or ketocarboxamides by simple or double carbon monoxide insertion, respectively. A strong dependence of the chemoselectivity on carbon monoxide pressure was observed.     

On the preparation of clean tungsten single crystals

The cleaning procedure consists of two-step-flashing: (i) cycles of low power flashes at an oxygen partial pressure of , to remove the carbon from the surface, and (ii) a single high power flash , to remove the oxide layer. The removal of carbon from the surface through the chemical reaction with oxygen during low power flash cycles is monitored by thermal desorption spectroscopy. The exposure to O₂ leads to the oxidation of the W surface. Using a high power flash, the volatile W-oxides and the atomic oxygen are desorbed, leaving a clean crystal surface at the end of procedure. The method may also be used for cleaning other refractory metals like Mo, Re and Ir.     

Modelling hematopoiesis in health and disease

Hematopoiesis is the process responsible for maintaining the number of circulating blood cells that are undergoing continuous turnover. At the root of this process are the hematopoietic stem cells (HSC), that replicate slowly to self-renew and give rise to progeny cells that proceed along the path of differentiation. The process is complex, with the cells responding to a wide variety of cytokines and growth factors. We discuss the mathematics of hematopoiesis based on stochastic cell behavior. Multiple compartments are introduced to keep track of each cell division process and increasing differentiation. The same mathematical model that describes normal hematopoiesis across mammals as a stable steady state of a hierarchical stochastic process is also used to understand the detailed dynamics of various disorders both in humans and in animal models. The microecology of the multitude of cell lineages that constitute what we call troubled hematopoiesis evolves in time under mutation and selection, the paradigmatic components of Darwinian evolution. Thus, the present approach provides a novel perspective for looking at cancer progression and cure.