Adler–Bardeen theorem and manifest anomaly cancellation to all orders in gauge theories

We reconsider the Adler–Bardeen theorem for the cancellation of gauge anomalies to all orders, when they vanish at one loop. Using the Batalin–Vilkovisky formalism and combining the dimensional-regularization technique with the higher-derivative gauge invariant regularization, we prove the theorem in the most general perturbatively unitary renormalizable gauge theories coupled to matter in four dimensions, and we identify the subtraction scheme where anomaly cancellation to all orders is manifest, namely no subtractions of finite local counterterms are required from two loops onwards. Our approach is based on an order-by-order analysis of renormalization, and, differently from most derivations existing in the literature, does not make use of arguments based on the properties of the renormalization group. As a consequence, the proof we give also applies to conformal field theories and finite theories.     

Cathodic pseudopolarography: A new tool for the identification and quantification of cysteine,cystine and other low molecular weight thiols in seawater

Thiols are compounds of paramount importance in the cellular metabolism due to their double detoxifying role as radical scavengers and trace metal ligands. However, we have scarce information about their extracellular cycling as limited data are available about their concentration, stability and speciation in the aquatic medium. In natural waters, they form part of the pool of reduced sulfur substance (RSS) whose presence has been documented by voltammetric and chromatographic methods. Traditional use of cathodic stripping voltammetry (CSV) for the analysis of RSS could only give an overall concentration due to the coalescence of their CSV peaks. Recently, it has been shown that the use of multiple deposition potentials could take voltammetry of RSS to a higher level, permitting the identification and quantification of the mixtures of RSS despite showing as a single coalescent peak. Here, due to its similarity with classical pseudopolarography, we propose to rename this analytical strategy as cathodic pseudopolarography (CP) and we present for the first time its use for the analysis of mixes of low molecular weight thiols (LMWT) at the nanomolar level. Despite limitations caused by the identical behavior of some LMWT, the CP allowed to isolate the contribution of cysteine and cystine from a coalescent signal in LMWT mixtures. Sample handling with clean protocols allowed the direct determination of the cystine:cysteine ratio without sample modification. Finally, we show the application of CP to identify LMWT in seawater samples extracted from benthic chambers and suggest future applications in other areas of environmental electroanalysis.     

Retinal in bacteriorhodopsin and related molecular models investigated with Raman spectroscopy and density functional theory calculations

A first‐principles assisted study of the Raman spectrum associated with the photoactive chromophore in bacteriorhodopsin (bR) allowed the elucidation of the effective coupling existing between the π electrons of the retinylidene chromophore and the local environment of the Schiff base. The role of the counter‐ion on the electronic and vibrational structure of the chromophore is investigated by means of density functional theory (DFT) calculations. Several molecular models of the retinylidene chromophore interacting with different counter‐ions facing the Schiff base have been considered. The counter‐ion induces a strong modulation of the position of both the UV–vis absorption maximum and the strong Raman active collective CC stretching mode, related to the effective conjugation coordinate (ECC). Experimental Raman and UV–vis absorption data are interpreted in the light of these theoretical findings. The data collected in this paper provide an interesting accumulation of points along the optical gap versus ECC wavenumber relationship. Copyright © 2011 John Wiley & Sons, Ltd.     

Design and development of a low cost,high performance UV digester prototype: Application to the determination of trace elements by stripping voltammetry

A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its main features include limited costs (around 600 € for all the parts) and high efficiency toward total organic carbon (TOC) abatement. As a result the TOC of typical natural waters is reduced to less than 10% of its initial value with half an hour treatment. Easiness of use, temperature control and flexibility in sample size (up to 25 mL) and number (up to twelve 12 mL test tube) are other important characteristics of the developed UV digester.This apparatus was tested as a pretreatment method for the determination of the total content of trace elements such as copper, uranium and platinum in natural waters by cathodic adsorptive stripping voltammetry. The voltammetric technique was chosen because it is strongly interfered by the presence of even low levels of natural organic complexing molecules. As a result, a 30 minute UV treatment yielded results non distinguishable from ICP-MS data.     

Mild, convenient and versatile Cu-mediated synthesis of N-aryl-2-imidazolidinones

A mild, general, convenient and practical methodology for the selective copper-mediated mono N-arylation of unprotected 2-imidazolidinone was developed. Strong electron-donating groups and free hydroxy and amino groups on the aryl iodide substrates were well tolerated. The use of n-butanol as the solvent for the copper-catalysed mono-arylation of 2-imidazolidinone is unprecedented.     

Optimal asset allocation aid system: From “one-size” vs “tailor-made” performance ratio

Optimal asset allocation well-fitting investors’ goals is a pressing challenge in risk management. Making a step forward to the Sharpe ratio, the parameter-dependent Sortino–Satchell, Generalized Rachev and Farinelli–Tibiletti performance ratios are suggested for personalizing asset allocation. Tailor-made optimal asset paths for five different investor risk profiles are traced over a rolling 12 month investing horizon. Our simulations show a satisfactorily good match between asset allocation and correspondent risk profile. Specifically, Generalized Rachev ratios outperform in personalized allocation for “extreme” risk profiles, i.e. conservative and aggressive investors, whereas Sortino–Satchell and Farinelli–Tibiletti ratios for those that are more moderate. Sharpe ratio confirms its ability in constructing steady-diversified portfolios, although underperformed.     

Theoretical investigation and computational evaluation of overtone and combination features in resonance Raman spectra of polyenes and carotenoids

We review the theory for overtones and combinations in resonant Raman spectroscopy introduced by Nafie, Stein and Peticolas in 1971 on the basis of time‐ordered diagrams, and we apply it to β‐carotene with the support of density functional theory calculations. Comparison with experimental results obtained by Tasumi's group in 1994 is provided. The theory here presented allows a prompt evaluation of resonant Raman intensities with presently available quantum chemistry tools. Copyright © 2014 John Wiley & Sons, Ltd.     

Protonated Porphyrins: Bifunctional Catalysts for the Metal-Free Synthesis of N-Alkyl-Oxazolidinones

The protonation of commercially available porphyrin ligands yields a class of bifunctional catalysts able to promote the synthesis of N-alkyl oxazolidinones by CO₂ cycloaddition to corresponding aziridines. The catalytic system does not require the presence of any Lewis base or additive, and shows interesting features both in terms of cost effectiveness and eco-compatibility. The metal-free methodology is active even with a low catalytic loading of 1 % mol, and the chemical stability of the protonated porphyrin allowed it to be recycled three times without any decrease in performance. In addition, a DFT study was performed in order to suggest how a simple protonated porphyrin can mediate CO₂ cycloaddition to aziridines to yield oxazolidinones.     

Pushing Up the Size Limit of Boron-doped peri-Acenes: Modular Synthesis and Characterizations

Heteroatom-doped peri-acenes (PAs) have recently attracted considerable attention considering their fascinating physical properties and chemical stability. However, the precise sole addition of boron atoms along the zigzag edges of PAs remains challenging, primarily due to the limited synthetic approach. Herein, we present a novel one-pot modular synthetic strategy toward unprecedented boron-doped PAs (B-PAs), including B-[4,2]PA ( 1 a-2 ), B-[4,3]PA ( 1 b-2 ) and B-[7,2]PA ( 1 c-3 ) derivatives, through efficient intramolecular electrophilic borylation. Their chemical structures are unequivocally confirmed with a combination of mass spectrometry, NMR, and single-crystal X-ray diffraction analysis. Notably, 1 b-2 exhibits an almost planar geometry, whereas 1 a-2 displays a distinctive bowl-like distortion. Furthermore, the optoelectronic properties of this series of B-PAs are thoroughly investigated by UV/Vis absorption and fluorescence spectroscopy combined with DFT calculation. Compared with their parent all-carbon analogs, the obtained B-PAs exhibit high stability, wide energy gaps, and high photoluminescence quantum yields of up to 84 %. This study reveals the exceptional ability of boron doping to finely tune the physicochemical properties of PAs, showcasing their potential applications in optoelectronics.