Implications of enzymatic, acidic and thermal hydrolysis of DNA on the occurrence of cross-linked melphalan DNA adducts

Calf thymus DNA was treated with melphalan, a nitrogen mustard, and the formation of melphalan cross-linked DNA adducts was investigated. These cross-linked adducts could not be detected either in the enzymatically or in the thermally generated DNA hydrolysates. However, a search for DNA cross-linked adducts in the hydrolysates obtained under acidic conditions revealed the presence of different types of cross-links, mainly containing an adenine moiety. These results are very important because they show that the detection of cross-links is dependent on the hydrolytic procedure used and that these cross-linked adducts are formed under totally different reaction conditions from those in in vivo situations. This can explain the very low abundance or even the absence of cross-linked adducts in nitrogen mustard treated animals. The generally accepted theory that the anti-cancer activity of bifunctional mustards such as melphalan is due to cross-linking of DNA strands remains therefore from our point of view questionable.     

Synthesis of Clicked Imidazolium‐Containing Biosourced Copolymers and Application in Carbon Nanotube Dispersion

New polyesters incorporating a variable quantity of imidazolium rings along the backbone are synthesized by Huisgen 1,3‐dipolar cycloaddition (“click” reaction). Subsequently, the imidazolium‐grafted copolymers reveal an efficient dispersing ability toward the carbon nanotubes (CNTs) through supramolecular interactions in organic media. Interestingly, these compounds offer a simple and reliable strategy to control the quantity of dispersed CNTs as a function of imidazolium content. This approach is particularly suitable for the elaboration of biosourced and biodegradable materials based on poly(butylene succinate) with high‐performance properties.     

Tolerance of continuous-variables quantum key distribution to the noise in state preparation

We address the applicability of the continuous-variables quantum key distribution in the realistic conditions of noisy preparation, channel loss and detection noise and investigate the possibility to increase its tolerance to the state preparation noise. The two types of preparation noise, either phase-sensitive or phase-insensitive excess noise, are considered in the assumption of optimal attacks performed by an eavesdropper within the setup based on the entangled source and either homodyne or heterodyne measurements. We show that preparation noise is destructive for the secure channel upon even low noise variances in the conditions of channel loss, while detection noise just decreases the key rate. We propose the method of sender-side attenuation to suppress the preparation noise in the entanglements-based scheme and show that it enables the secure key transmission upon arbitrary high preparation noise of both types and any pure channel loss against both individual and collective attacks.     

Families Of K3 surfaces and Lyapunov exponents

Consider a family of K3 surfaces over a hyperbolic curve (i.e., Riemann surface). Their second cohomology groups form a local system, and we show that its top Lyapunov exponent is a rational number. One proof uses the Kuga–Satake construction, which reduces the question to Hodge structures of weight 1. A second proof uses integration by parts. The case of maximal Lyapunov exponent corresponds to modular families coming from the Kummer construction.     

Porosity and the L p -conjecture

Recently, Abtahi, Nasr-Isfahani, and Rejali [1] have shown that if G is a locally compact but not compact topological group and p > 2, then there are two functions, f and g, such that the convolution f*g{f\star g} is equal to ∞ on some set of positive measure. In the paper we show the nonexistence of f*g{f\star g} on a set of positive measure for (f, g) from a complement of a σ-porous set.     

Epistemic irrelevance in credal nets: The case of imprecise Markov trees

We focus on credal nets, which are graphical models that generalise Bayesian nets to imprecise probability. We replace the notion of strong independence commonly used in credal nets with the weaker notion of epistemic irrelevance, which is arguably more suited for a behavioural theory of probability. Focusing on directed trees, we show how to combine the given local uncertainty models in the nodes of the graph into a global model, and we use this to construct and justify an exact message-passing algorithm that computes updated beliefs for a variable in the tree. The algorithm, which is linear in the number of nodes, is formulated entirely in terms of coherent lower previsions, and is shown to satisfy a number of rationality requirements. We supply examples of the algorithm’s operation, and report an application to on-line character recognition that illustrates the advantages of our approach for prediction. We comment on the perspectives, opened by the availability, for the first time, of a truly efficient algorithm based on epistemic irrelevance.     

Relaxation of signed integral functionals in BV

For integral functionals initially defined for ${u \in {\rm W}^{1,1}(\Omega; \mathbb{R}^m)}$ by $$\int_{\Omega} f(\nabla u) \, {\rm d}x$$ we establish strict continuity and relaxation results in ${{\rm BV}(\Omega; \mathbb{R}^m)}$ . The results cover the case of signed continuous integrands ${f : \mathbb{R}^{m \times d} \to \mathbb{R}}$ of linear growth at infinity. In particular, it is not excluded that the integrands are unbounded below.     

Anti-hydroxyl radical activity,redox potential and anti-AChE activity of Amanita strobiliformis polysaccharide extract

This study outlines antioxidant and anti-AChE activities of the polysaccharide (PSH) extract from the mushroom species Amanita strobiliformis. Both the presence of α and ß glucans within the aforementioned extract was recorded. PSH extract displayed a profound scavenging activity of OH radicals (IC₅₀ value, 11.86 ± 0.59 μg/mL) and high potential for reduction of Fe³⁺ ions (174.11 ± 8.70 mg eq. AA/g d.w.) being almost 48- and 5-fold more effective than mannitol and butylated hydroxytoluene used as a positive control, respectively. Compared with galanthamine (0.001 μg), the same extract exhibited a moderate anti-AChE activity (10 μg) in solid. Since purified PSH extract exhibited higher bioactivity (IC₅₀ value 7.27 ± 0.31 μg/mL, 197.68 ± 9.47 mg eq. AA/g d.w. and 0.1 μg, respectively), it can be predominantly ascribed to the polysaccharide compounds. A. strobiliformis PSH extract may be considered as a promising resource of potent bioactive polysaccharides of natural origin successfully addressing both oxidative stress and lack of acetylcholine.