New Oxaliplatin-Pyrophosphato Analogs with Improved In Vitro Cytotoxicity

Two new Pt(II)-pyrophosphato complexes containing the carrier ligands cis-1,3-diaminocyclohexane (cis-1,3-DACH) and trans-1,2-diamine-4-cyclohexene (1,2-DACHEX), variants of the 1R,2R-diaminocyclohexane ligand present in the clinically used Pt-drug oxaliplatin, have been synthesized with the aim of developing new potential antitumor drugs with high bone tropism. The complexes are more stable at physiological pH than in acid conditions, with Na₂[Pt(pyrophosphato)(cis-1,3-DACH)] (1) slightly more stable than [Pt(dihydrogenpyrophosphato)(1,2-DACHEX)] (2). The greater reactivity at acidic pH ensures a greater efficacy at the tumor site. Preliminary NMR studies indicate that 1 and 2 react slowly with 5’-GMP (used as a model of nucleic acids), releasing the pyrophosphate ligand and affording the bis 5’-GMP adduct. In vitro cytotoxicity assays performed against a panel of four human cancer cell lines have shown that both compounds are more active than oxaliplatin. Flow cytometry studies on HCT116 cells showed that the pyrophosphato compounds with the non-classical 1,3- and 1,4-diaminocyclohexane ligands (1 and 4) are the most capable to induce cells’ death by apoptosis and necrosis.     

Improvement of Contact Tracing with Citizen’s Distributed Risk Maps

The rapid spread of COVID-19 has demonstrated the need for accurate information to contain its diffusion. Technological solutions are a complement that can help citizens to be informed about the risk in their environment. Although measures such as contact traceability have been successful in some countries, their use raises society’s resistance. This paper proposes a variation of the consensus processes in directed networks to create a risk map of a determined area. The process shares information with trusted contacts: people we would notify in the case of being infected. When the process converges, each participant would have obtained the risk map for the selected zone. The results are compared with the pilot project’s impact testing of the Spanish contact tracing app (RadarCOVID). The paper also depicts the results combining both strategies: contact tracing to detect potential infections and risk maps to avoid movements into conflictive areas. Although some works affirm that contact tracing apps need 60% of users to control the propagation, our results indicate that a 40% could be enough. On the other hand, the elaboration of risk maps could work with only 20% of active installations, but the effect is to delay the propagation instead of reducing the contagion. With both active strategies, this methodology is able to significantly reduce infected people with fewer participants.     

DNA interactions and anticancer screening of copper(II) complexes of <Emphasis Type="Italic">N</Emphasis>-(methylpyridin-2-yl)-amidino-<Emphasis Type="Italic">O</Emphasis>-methylurea

Cu(II) complexes of the tridentate ligand N-(methylpyridin-2-yl)-amidino-O-methylurea (L), namely [Cu(L)Cl₂] and [Cu(L)ClO₄]ClO₄, have been investigated for interactions with DNA by spectroscopic methods and viscosity measurements. Both complexes bind to DNA through non-intercalative interactions. [Cu(L)Cl₂] (K _b = 2.81 × 10⁵ M^?1) shows similar DNA-binding potential to [Cu(L)ClO₄]ClO₄ (K _b = 1.57 × 10⁵ M^?1). Investigation of the chemical nuclease properties toward plasmid pBR322 DNA by gel electrophoresis and atomic force microscopy (AFM) suggests that both complexes are able to cleave the supercoiled form (Form I) to the nicked (Form II) and linear forms (Form III) through an oxidative pathway. The possible reactive oxygen species have been investigated by the use of scavengers, indicating that hydroxyl radicals may be involved in the DNA cleavage mechanism. Both of these complexes show similar activities against selected human cancer cell lines.     

The Representation Type of Determinantal Varieties

This work is entirely devoted to construct huge families of indecomposable arithmetically Cohen-Macaulay (resp. Ulrich) sheaves \(\mathcal {E}\) of arbitrary high rank on a general standard (resp. linear) determinantal scheme \(X\subset \mathbb {P}^{n}\) of codimension c ≥ 1, n ? c ≥ 1 and defined by the maximal minors of a t × (t + c?1) homogeneous matrix \(\mathcal {A}\). The sheaves \(\mathcal {E}\) are constructed as iterated extensions of sheaves of lower rank. As applications: (1) we prove that any general standard determinantal scheme \(X\subset \mathbb {P}^{n}\) is of wild representation type provided the degrees of the entries of the matrix \(\mathcal {A}\) satisfy some weak numerical assumptions; and (2) we determine values of t, n and n ? c for which a linear standard determinantal scheme \(X\subset \mathbb {P}^{n}\) is of wild representation type with respect to the much more restrictive category of its indecomposable Ulrich sheaves, i.e. X is of Ulrich wild representation type.     

Insights for diastereoselective synthesis of cyclic α-sulfinyl and sulfanyl oximes

The comparison in several reaction conditions for synthesis of nonracemic α-methylsulfinylation of 3,4-dihydronaphthalen-1(2H)-one was achieved. The sulfanylation reactions of 3,4-dihydronaphthalen-1(2H)-one-O-methyloxime and 2-(methylsulfinyl)-3,4-dihydronaphthalen-1(2H)-one-O-methyloxime by homogenous reaction medium are reported. The products were obtained in good yields and de. The yields, diastereoselectivity and theoretical calculations to all obtained compounds to support the experimental data are compared and discussed.     

Synthesis,Crystal Structure,and Catalytic Properties of Porous 3d‐4f Heterometallic Coordination Polymers Constructed from Pyrazine‐2,3‐dicarboxylic Acid

Reactions of pyrazine‐2,3‐dicarboxylic acid (H₂pzdc), cobalt nitrate and lanthanide (Ln) oxide under hydrothermal conditions result in four new 3d‐4f heterometal coordination polymers, namely, [Ln₂Co(pzdc)₄(H₂O)₆] · 2H₂O [Ln = La ( 1 ), Pr ( 2 ), Eu ( 3 ) and Gd ( 4 )]. All compounds were characterized by elemental analysis, infrared spectroscopy, thermal gravimetric analysis, and X‐ray diffraction. The compounds exhibit a three‐dimensional (3D) brick‐like structure with rectangular‐shaped nano‐scale channels along a axis direction, made up of wave‐like layers containing [Ln(pzdc)]⁺ units, which are connected by one‐dimensional (1D) chain of [Co(pzdc)₂]^2–. The catalytic properties of compounds 1 and 3 were investigated in the synthesis of cyanohydrins at room temperature under solventless conditions. They showed similar catalytic activities with very high conversions of benzaldehyde and high selectivity towards cyanohydrin. The control experiment without addition of the coordination polymers only reached 16 % conversion. Other aldehydes could also be converted totally under shorter reaction times also with very high selectivities for the corresponding cyanohydrins. Compound 1 could also be recycled in another catalytic cycle.     

Experimental implementation of non-Gaussian attacks on a continuous-variable quantum-key-distribution system

An intercept-resend attack on a continuous-variable quantum-key-distribution protocol is investigated experimentally. By varying the interception fraction, one can implement a family of attacks where the eavesdropper totally controls the channel parameters. In general, such attacks add excess noise in the channel, and may also result in non-Gaussian output distributions. We implement and characterize the measurements needed to detect these attacks, and evaluate experimentally the information rates available to the legitimate users and the eavesdropper. The results are consistent with the optimality of Gaussian attacks resulting from the security proofs.     

Histological approaches for high-quality imaging of zooplanktonic organisms

The investigation of the internal organization of zooplankton communities provides important information on the plankton biology with special interest for the study of ecological processes. Zooplanktoners can play a structural function as indicators for ecosystem health or stress, but their study using histological techniques is still limited. Here we report that the internal structure of zooplanktonic organisms can be facilely observed by a histological approach that combines optimal fixation and processing with a plastic resin (glycol methacrylate) embedding, resulting in increased tissue resolution. Using copepods, organisms that can dominate zooplankton assemblages, as models, collected from a tropical ecosystem (Paraibuna river, Brazil), we showed fine histological details of their muscular, nervous and digestive systems, structure of appendages and cell features. Critical advantages of this approach are that it permits optimal preservation and adequate handling of the organisms (embedded in agar after fixation) for further histological processing and investigation. This is important because it prevents both mechanically induced artifacts and loss of these diminutive organisms during the different steps of processing. Moreover, embedding in plastic resin showed a superior imaging of copepod internal structures compared to paraffin embedding. The use of glycol methacrylate is advantageous over paraffin/paraplast embedding by avoiding heat damage, tissue retraction and allowing faster embedding procedure and better tissue resolution. The value of histological approaches in enabling high-quality imaging of the internal structure of copepods is particularly important because these organisms can be used as indicators of environmental changes.     

The insertion reaction of acetonitrile on aryl nickel complexes stabilized by bidentate N,N'-chelating ligands

Organometallic complexes to be used as single component precursors in the catalytic dimerization/polymerization of olefins usually must contain a labile ligand that can easily be displaced by the olefin. This is the first step in the activation of the precursor. One commonly used labile ligand is a nitrile. Here we report an example of incompatibility between the nickel or palladium aryl bond and acetonitrile. Neutral [MBr(Mes)NN] complexes in which Mes=2,4,6-Me3C6H2, NN=diazabutadiene (DAD), pyridinylimine (PIM), 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen) gave the expected [M(Mes)(3,5-lut)(NN)][BF4] compounds and the unexpected [Ni(Mes){NH=C(Me)(2,4,6-Me3C6H2)}(NN)][BF4] complexes in the presence of TlBF4 and 3,5-lutidine or acetonitrile. The sequence of reactions that leads to the imine ligand must include an initial insertion of the nitrile on the sigma(Ni-Mes) bond. These ionic complexes remain stable under 20 bar of ethylene.