X-ray absorption near-edge structure (XANES) spectroscopy identifies differential sulfur speciation in corneal tissue

The chemical composition of tissues can influence their form and function. As a prime example, the lattice-like arrangement of collagen fibrils required for corneal transparency is controlled, in part, by sulfated proteoglycans, which, via core proteins, bind to the collagen at specific locations along the fibril axis. However, to date, no studies have been able to directly identify and characterize sulfur (S) in the cornea as a function of tissue location. In this study, X-ray absorption near-edge structure spectroscopy and micro-beam X-ray fluorescence (μ-XRF) chemical contrast imaging were employed to probe the nature of the mature (bovine) cornea as a function of position from the anterior sub-epithelial region into the deep stroma. Data indicate an inhomogeneity in the composition of S species in the first ≈50 μm of stromal depth. In μ-XRF chemical contrast imaging, S did not co-localize with phosphorous (P) in the deep stroma where sulfates are prominent. Rather, P is present only as isolated micrometric spots, presumably identifiable as keratocytes. This study lends novel insights into the elemental physiology of mature cornea, especially in relation to its S distribution; future studies could be applied to human tissues. Moreover, it defines an analytical protocol for the interrogation of S species in biological tissues with micrometric resolution.

Effectiveness of measures of performance during speculative bubbles

Statistical analysis of financial data mostly focused on testing the validity of Brownian motion (Bm). Analyses performed on several time series have shown deviation from the Bm hypothesis, that is at the base of the evaluation of many financial derivatives. We analyze the behavior of performance measures based on maximum drawdown movements (MDD(T)), testing their stability when the underlying process deviates from the Bm hypothesis. In particular we consider the fractional Brownian motion (fBm), and fluctuations estimated empirically on raw market data. The case study of the rising part of speculative bubbles is reported.     

Dielectric properties of ice and liquid water from first-principles calculations

We present a first-principles study of the static dielectric properties of ice and liquid water. The eigenmodes of the dielectric matrix E are analyzed in terms of maximally localized dielectric functions similar, in their definition, to maximally localized Wannier orbitals obtained from Bloch eigenstates of the electronic Hamiltonian. We show that the lowest eigenmodes of E (-1) are localized in real space and can be separated into groups related to the screening of lone pairs, intra-, and intermolecular bonds, respectively. The local properties of the dielectric matrix can be conveniently exploited to build approximate dielectric matrices for efficient, yet accurate calculations of quasiparticle energies.     

Precise predictions for same-sign W-boson scattering at the LHC

Vector-boson scattering processes are of great importance for the current run-II and future runs of the Large Hadron Collider. The presence of triple and quartic gauge couplings in the process gives access to the gauge sector of the Standard Model (SM) and possible new-physics contributions there. To test any new-physics hypothesis, sound knowledge of the SM contributions is necessary, with a precision which at least matches the experimental uncertainties of existing and forthcoming measurements. In this article we present a detailed study of the vector-boson scattering process with two positively-charged leptons and missing transverse momentum in the final state. In particular, we first carry out a systematic comparison of the various approximations that are usually performed for this kind of process against the complete calculation, at LO and NLO QCD accuracy. Such a study is performed both in the usual fiducial region used by experimental collaborations and in a more inclusive phase space, where the differences among the various approximations lead to more sizeable effects. Afterwards, we turn to predictions matched to parton showers, at LO and NLO: we show that on the one hand, the inclusion of NLO QCD corrections leads to more stable predictions, but on the other hand the details of the matching and of the parton-shower programs cause differences which are considerably larger than those observed at fixed order, even in the experimental fiducial region. We conclude with recommendations for experimental studies of vector-boson scattering processes.     

Universal Low-energy Behavior in a Quantum Lorentz Gas with Gross-Pitaevskii Potentials

We consider a quantum particle interacting with N obstacles, whose positions are independently chosen according to a given probability density, through a two-body potential of the form N²V (Nx) (Gross-Pitaevskii potential). We show convergence of the N dependent one-particle Hamiltonian to a limiting Hamiltonian where the quantum particle experiences an effective potential depending only on the scattering length of the unscaled potential and the density of the obstacles. In this sense our Lorentz gas model exhibits a universal behavior for N large. Moreover we explicitely characterize the fluctuations around the limit operator. Our model can be considered as a simplified model for scattering of slow neutrons from condensed matter.     

Co(Salox)-Catalyzed Enantioselective Reduction of α,β-Unsaturated Esters

Co-Salox complexes are suitable catalysts for the reduction of prochiral α,β-unsaturated esters. These ligands can be prepared in a single step from available and inexpensive materials, thus representing an easily accessible alternative to previously reported Co-catalysts. NaBH₄ is employed as reducing agent in the presence of EtOH as proton source, leading to the stereoselective formation of chiral esters, amides, and nitriles in up to 99 % yield and 96.5 : 3.5 er. The concentration of the reductant counter cation (Na⁺) and the solvent polarity have been shown to correlate with reactivity and enantioselectivity, suggesting that a relatively complex mechanistic manifold is in place.     

C−H Fluoromethoxylation of Arenes by Photoredox Catalysis

Redox-active N-(fluoromethoxy)benzotriazoles were made accessible from fluoroacetic acid and hydroxybenzotriazoles via electrodecarboxylative coupling. After alkylation, they become effective monofluoromethoxylation reagents, enabling the photocatalytic C−H functionalization of arenes. Thus, irradiation of 1-(OCH₂F)-3-Me-6-(CF₃)benzotriazolium triflate with blue LED light in the presence of [Ru(bpy)₃(PF₆)₂] promotes the synthesis of diversely functionalized aryl monofluoromethyl ethers. This method allows the late-stage functionalization of biologically relevant structures without relying on ecologically problematic halofluorocarbons.     

Site-Specific Ubiquitination of Tau Amyloids Promoted by the E3 Ligase CHIP

Post-translational modifications of Tau are emerging as key players in determining the onset and progression of different tauopathies such as Alzheimer's disease, and are recognized to mediate the structural diversity of the disease-specific Tau amyloids. Here we show that the E3 ligase CHIP catalyzes the site-specific ubiquitination of Tau filaments both in vitro and in cellular models, proving that also Tau amyloid aggregates are direct substrate of PTMs. Transmission electron microscopy and mass spectrometry analysis on ubiquitin-modified Tau amyloids revealed that the conformation of the filaments restricts CHIP-mediated ubiquitination to specific positions of the repeat domain, while only minor alterations in the structure of the fibril core were inferred using seeding experiments in vitro and in a cell-based tauopathy model. Overexpression of CHIP significantly increased the ubiquitination of exogenous PHF, proving that the ligase can interact and modify Tau aggregates also in a complex cellular environment.     

Point-of-Care Testing for the Detection of MicroRNAs: Towards Liquid Biopsy on a Chip

Point-of-care (PoC) testing is revolutionizing the healthcare sector improving patient care in daily hospital practice and allowing reaching even remote geographical areas. In the frame of cancer management, the design and validation of PoC enabling the non-invasive, rapid detection of cancer markers is urgently required to implement liquid biopsy in clinical practice. Therefore, focusing on stable blood-based markers with high-specificity, such as microRNAs, is of crucial importance. In this work, we highlight the potential impact of circulating microRNAs detection on cancer management and the crucial role of PoC testing devices, especially for low-income countries. A detailed discussion about the challenges that should be faced to promote the technological transfer and clinical use of these tools has been added, to provide the readers with a complete overview of potentialities and current limitations.