A Redox‐Activated G‐Quadruplex DNA Binder Based on a Platinum(IV)–Salphen Complex

There has been increasing interest in the development of small molecules that can selectively bind to G‐quadruplex DNA structures. The latter have been associated with a number of key biological processes and therefore are proposed to be potential targets for drug development. Herein, we report the first example of a reduction‐activated G‐quadruplex DNA binder. We show that a new octahedral platinum(IV)–salphen complex does not interact with DNA in aqueous media at pH 7.4; however, upon addition of bioreductants such as ascorbic acid or glutathione, the compound is readily reduced to the corresponding square planar platinum(II) complex. In contrast to the parent platinum(IV) complex, the in situ generated platinum(II) complex has good affinity for G‐quadruplex DNA.     

Diagnosis of public programs focused on herbal medicines in Brazil

The present study is aimed to diagnose the current public programs focused on herbal medicines in Brazil by means of in loco visits to 10 programs selected by means of questionnaires sent to 124 municipalities that count on herbal medicine services. The main purpose of the implementation of program programs is related to the development of medicinal herbs. 70% of them are intended for the production of herbal medicines and 50% are aimed to ensure the access of the population to medicinal plants and or herbal medicines. The initiative of the implementation of these programs was related to the managers (60%). The difficulties in this implementation were due to the lack of funding (100%) of the programs. In 60% of the programs, the physicians did not adhere to herbal medicine services due to the lack of knowledge of the subject. Training courses were proposed (80%) to increase the adhesion of prescribers to the system. Some municipalities use information obtained from patients to assess the therapeutic efficiency of medicinal plants and herbal medicines. Of the programs underway, cultivation of medicinal plants was observed in 90% and 78% of them adopt quality control. In most programs, this control is not performed in accordance with the legal requirements. The programs focused on medicinal plants and herbal medicines implemented in Brazil face some chronic problems of infrastructure, management, operational capacity and self-sustainability, which can be directly related to the absence of a national policy on medicinal plants and herbal medicines.     

Electropolymerization of <Emphasis Type="Italic">trans</Emphasis>-[RuCl<Subscript>2</Subscript>(vpy)<Subscript>4</Subscript>] complex—EQCM and Raman studies

The electropolymerization of trans-[RuCl₂(vpy)₄] (vpy=4-vinylpyridine) on Au or Pt electrodes was studied by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) technique, and Raman spectroscopy. Cyclic voltammetry of the monomer at a microelectrode shows the typical Ru(III/II) and Ru(IV/III) waves, together with the vinyl reduction waves at −1.5 and −2.45 V and adsorption wave at −0.8 V. Electrodeposition on EQCM technique performed under potential cycling between −0.9 and −2.0 V revealed that the polymerization proceeded well in advance of the vinyl reduction waves. At potentials more positive than −0.9 V, soluble oligomers were deposited irreversibly on the electrode during the oxidative sweep. The film also showed reversible mass changes due to the oxidation and accompanying ingress of charge-balancing anions and solvent into the film. In contrast, potentiostatic growth of the polymer at −1.6 V was slower because the oligomeric material was lost completely from the electrode. Unreacted vinyl groups were detected by in situ Raman spectroscopy for films grown at −0.7, −0.9, and −1.6 V but were absent when the polymerization was carried out at −2.9 V vs Ag/Ag⁺.     

Computation of sparse low degree interpolating polynomials and their application to derivative-free optimization

Interpolation-based trust-region methods are an important class of algorithms for Derivative-Free Optimization which rely on locally approximating an objective function by quadratic polynomial interpolation models, frequently built from less points than there are basis components. Often, in practical applications, the contribution of the problem variables to the objective function is such that many pairwise correlations between variables are negligible, implying, in the smooth case, a sparse structure in the Hessian matrix. To be able to exploit Hessian sparsity, existing optimization approaches require the knowledge of the sparsity structure. The goal of this paper is to develop and analyze a method where the sparse models are constructed automatically. The sparse recovery theory developed recently in the field of compressed sensing characterizes conditions under which a sparse vector can be accurately recovered from few random measurements. Such a recovery is achieved by minimizing the ℓ ₁-norm of a vector subject to the measurements constraints. We suggest an approach for building sparse quadratic polynomial interpolation models by minimizing the ℓ ₁-norm of the entries of the model Hessian subject to the interpolation conditions. We show that this procedure recovers accurate models when the function Hessian is sparse, using relatively few randomly selected sample points. Motivated by this result, we developed a practical interpolation-based trust-region method using deterministic sample sets and minimum ℓ ₁-norm quadratic models. Our computational results show that the new approach exhibits a promising numerical performance both in the general case and in the sparse one.     

Simple versus composite nature of the magnetic coupling in copper and nickel-based metallic chains. Over- and underestimation of J

Extended metal atom chains (EMACs) are molecular linear arrangements of metal atoms featuring magnetic properties. By means of the density functional theory (DFT), we have studied the magnetic coupling constants for [Cu₃(dpa)₄Cl₂]⁺, Ni₃(dpa)₄Cl₂ and Ni₅(tpda)₄Cl₂ to understand which is the origin of the previously reported theoretical underestimation of J for nickel complexes. We have decomposed J = J_σ + J_δ, finding that the former contribution is underestimated and the latter part is overestimated at the DFT/B3LYP level of computation. Varying the amount of Hartree-Fock exchange, we show that the B3LYP functional fails to describe the σ interaction properly, whereas the δ coupling is exaggerated.     

Vibrational Spectroscopy of Xanthoxyline Crystals and DFT Calculations

The Fourier transform infrared and Fourier transform Raman spectra of xanthoxyline crystals are reported, along with ab initio computations of the vibrational spectrum of the xanthoxyline molecule. The infrared and Raman spectra were recorded at 300?K in the 400- to 4,000- and 40- to 4,000-cm^?1 intervals, respectively. The vibrational wave numbers and wave vectors were obtained from a density functional computation with the 6-31 G(d,p) basis set and the B3LYP approximation to the exchange correlation functional. Comparison with the theoretical results allows assignment of normal modes to the prominent features of the recorded spectra.     

Derandomizing Restricted Isometries via the Legendre Symbol

The restricted isometry property (RIP) is an important matrix condition in compressed sensing, but the best matrix constructions to date use randomness. This paper leverages pseudorandom properties of the Legendre symbol to reduce the number of random bits in an RIP matrix with Bernoulli entries. In this regard, the Legendre symbol is not special—our main result naturally generalizes to any small-bias sample space. We also conjecture that no random bits are necessary for our Legendre symbol-based construction.