H2O2–Ng dynamics predictions using an accurate potential energy surface

ABSTRACT

Based on ab initio calculations, our research group has built an analytical ground-state potential energy surface (PES) for hydrogen peroxide– noble gas (Ng) interactions, such as H₂O₂–He, H₂O₂–Ne, H₂O₂–Ar, H₂O₂–Kr, and H₂O₂–Xe complexes. From this PES, it was verified that the Ng presence does not affect the equilibrium values of the H₂O₂ dihedral angles. This happens because the H₂O₂ intramolecular barriers have much higher energies than the atom–bond interaction within these complexes. From this point of view, it is indeed reasonable to consider the H₂O₂ system as a rigid rotor, frozen at its equilibrium configuration. We present in this work the torsional motion for the H₂O₂ isolated system, the vibration–rotation energy levels and spectroscopic constants for hydrogen peroxide–noble gas by using the aforementioned PES. The predicted H₂O₂ torsional motions are in good agreement with both theoretical and experimental results available in the literature. Regarding H₂O₂–Ng ro-vibrational energies and spectroscopic constants, it is the first time that these calculations are presented in the literature. The current theoretical predictions are expected to be useful in the future experimental investigations.     

Application of FTIR Spectroscopy for Identification of Blood and Leukemia Biomarkers: A Review over the Past 15 Years

Abstract

Fourier transform infrared (FTIR) spectroscopy is an effective and nondestructive method for monitoring cellular alterations. Combining the advantages of FTIR spectroscopy with the challenge of cellular characterization, the main objective of this review is to collect information related to the spectroscopic identification of blood cells, focusing on specific biochemical features of leukemia cells detected through FTIR spectral analysis. Some interesting results obtained by different authors regarding human promyelocytic leukemia, white blood cells, chronic lymphocytic leukemia, and human peripheral blood mononuclear cells are presented. In addition, the characterization of two types of cells, namely, leukemia T and a healthy human blood cells, is reported and the identification of biochemical markers provides important information that, associated with clinical examination, can assist in the diagnosis of diseases.     

Synthesis of bifunctional chelating agents based on mono and diphosphonic derivatives of diethylenetriaminepentaacetic acid

Bifunctional chelating agents (BFCAs) are small molecules containing a chelating unit, able to strongly coordinate a metal ion, and a reactive functional group, devised to form a stable covalent bond with another molecule. BFCAs are widely employed since their conjugation to a suitable biomolecule (e.g., a peptide or an antibody) allows the synthesis of diagnostic or therapeutic agents that specifically target diseased tissue with metals or radiometals. For this reason, BFCAs find application in diagnostic imaging, molecular imaging, and radiotherapy of cancer. The synthesis of new BFCAs based on a diethylenetriaminepentaacetic acid (DTPA) structure in which one or two carboxylic groups are replaced with phosphonic units is described. The phosphonic group, aside from being a classical isostere of the carboxylic acid in coordination chemistry, allows to modulate the physico-chemical properties of the ligands and of the corresponding complexes.     

Smart Coatings Prepared via MAPLE Deposition of Polymer Nanocapsules for Light-Induced Release

Herein, smart coatings based on photo-responsive polymer nanocapsules (NC) and deposited by laser evaporation are presented. These systems combine remotely controllable release and high encapsulation efficiency of nanoparticles with the easy handling and safety of macroscopic substrates. In particular, azobenzene-based NC loaded with active molecules (thyme oil and coumarin 6) were deposited through Matrix-Assisted Pulsed Laser Evaporation (MAPLE) on flat inorganic (KBr) and organic (polyethylene, PE) and 3D (acrylate-based micro-needle array) substrates. SEM analyses highlighted the versatility and performance of MAPLE in the fabrication of the designed smart coatings. DLS analyses, performed on both MAPLE- and drop casting-deposited NC, demonstrated the remarkable adhesion achieved with MAPLE. Finally, thyme oil and coumarin 6 release experiments further demonstrated that MAPLE is a promising technique for the realization of photo-responsive coatings on various substrates.     

Alkaloids and Colon Cancer: Molecular Mechanisms and Therapeutic Implications for Cell Cycle Arrest

Cancer is the second most fatal disease worldwide, with colon cancer being the third most prevalent and fatal form of cancer in several Western countries. The risk of acquisition of resistance to chemotherapy remains a significant hurdle in the management of various types of cancer, especially colon cancer. Therefore, it is essential to develop alternative treatment modalities. Naturally occurring alkaloids have been shown to regulate various mechanistic pathways linked to cell proliferation, cell cycle, and metastasis. This review aims to shed light on the potential of alkaloids as anti-colon-cancer chemotherapy agents that can modulate or arrest the cell cycle. Preclinical investigated alkaloids have shown anti-colon cancer activities and inhibition of cancer cell proliferation via cell cycle arrest at different stages, suggesting that alkaloids may have the potential to act as anticancer molecules.     

On the continuous extension of Adams–Bashforth methods and the event location in discontinuous ODEs

The interpolation polynomial in the $k$-step Adams–Bashforth method may be used to compute the numerical solution at off grid points. We show that such a numerical solution is equivalent to the one obtained by the Nordsieck technique for changing the step size. We also provide an application of this technique to the event location in discontinuous differential systems.     

Elasticity of flexible and semiflexible polymers with extensible bonds in the Gibbs and Helmholtz ensembles

Stretching experiments on single molecules of arbitrary length opened the way for studying the statistical mechanics of small systems. In many cases in which the thermodynamic limit is not satisfied, different macroscopic boundary conditions, corresponding to different statistical mechanics ensembles, yield different force-displacement curves. We formulate analytical expressions and develop Monte Carlo simulations to quantitatively evaluate the difference between the Helmholtz and the Gibbs ensembles for a wide range of polymer models of biological relevance. We consider generalizations of the freely jointed chain and of the worm-like chain models with extensible bonds. In all cases we show that the convergence to the thermodynamic limit upon increasing contour length is described by a suitable power law and a specific scaling exponent, characteristic of each model.     

Cycloruthenated Complexes from Imine‐Based Heterocycles: Synthesis,Characterization, and Reactivity toward Alkynes

Novel cycloruthenated complexes 2 a – c , 4 a – c , and 6 a, b based on heteroaromatic cores have been synthesized by reaction of a series of heterocycle‐based imines with [{RuCl(η⁶‐p‐cymene)}₂(μ? Cl)₂] and Cu(OAc)₂. This approach has proved efficient for the cyclometalation of thiophene, benzothiophene, furan, benzofuran, pyrrole, and indole derivatives. In addition, even a double cyclometalation process over the same heterocyclic ring is possible, yielding unprecedented bimetallic complexes. These ruthenacycles react with 3‐hexyne through an unexpected pathway, which involves the coupling of the original imino heterocycle and acetylene followed by dearomatization to afford fused hetero‐hydropyridyl ligands bonded to the {Ru(p‐cymene)} organometallic moiety (i.e., 7 a – c and 8 a – c ). These complexes represent, as far as we know, the first examples of this type of compound within the context of cyclometalation, and an exhaustive analysis of their structure was carried out in solution and solid state. Furthermore, these unique species react with CuCl₂, which promotes the rearomatization and the release of highly valuable aromatic fused bis‐heterocycles (i.e., 9 a – c , 10 a – c, 11 a , and 12 a/12 a′ ), providing a novel and appealing synthetic route to this extraordinary family of molecules.     

Effect of testing conditions on the laser flash thermal diffusivity measurements of ceramics

Several experimental techniques either under steady state or transient heat transfer conditions, have been developed to evaluate thermal conductivity and thermal diffusivity of materials. However, testing difficulties resulting from specimen size, extended testing time and heat losses, have somewhat impaired the applicability of many of them. In this respect, the use of the laser flash technique for thermal diffusivity measurements, is a very convenient alternative, considering its basic modeling equation is independent of the temperature gradient as well as the heat flow, and in addition the heat losses can be analytically treated. Another important advantage of the technique is its rapid experimental execution. In this work, it is presented as an investigation concerning how the testing conditions such as specimen coating, laser power and pulse duration, base line adoption, heat losses correction methods, and specimen thickness, may affect the thermal diffusivity measurements of some ceramic materials using the laser flash technique.