An uracil-linked hydroxyflavone probe for the recognition of ATP

Background: Nucleotides are essential molecules in living systems due to their paramount importance in various physiological processes. In the past years, numerous attempts were made to selectively recognize and detect these analytes, especially ATP using small-molecule fluorescent chemosensors. Despite the various solutions, the selective detection of ATP is still challenging due to the structural similarity of various nucleotides. In this paper, we report the conjugation of a uracil nucleobase to the known 4’-dimethylamino-hydroxyflavone fluorophore.Results: The complexation of this scaffold with ATP is already known. The complex is held together by stacking and electrostatic interactions. To achieve multi-point recognition, we designed the uracil-appended version of this probe to include complementary base-pairing interactions. The theoretical calculations revealed the availability of multiple complex structures. The synthesis was performed using click chemistry and the nucleotide recognition properties of the probe were evaluated using fluorescence spectroscopy.Conclusions: The first, uracil-containing fluorescent ATP probe based on a hydroxyflavone fluorophore was synthesized and evaluated. A selective complexation with ATP was observed and a ratiometric response in the excitation spectrum

Effects of land use changes on soil properties based on reambulated soil profiles

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Az önszabályozó tanulás fejlettségének összefüggései a tanulási eredményességgel és az IKT-használat gyakoriságával

Háttér és célok: Új típusú pedagógiai problémákat vet fel az infokommunikációs technológiák elterjedésével általánossá váló önálló információkeresés és feldolgozás. A tanuló oldaláról feltételezi az önálló tanulást, az információk hatékony feldolgozását, megértését. A tanár oldaláról pedig a tudásátadó szerep helyett a tanulásirányító szerep hangsúlyosabbá válását (Molnár, 2011). Az élethosszig tartó tanulás iránti társadalmi igény az önszabályozó tanulási készség fejlődése nélkül nem teljesülhet. Ugyanakkor a tanulók önreflektív és önszabályozó képessége a tanulás, tanítás folyamatában még kiaknázatlan (Molnár, 2002). A cikkben bemutatjuk egy keresztmetszeti összehasonlító kutatás eredményeit, melynek célja a tanulás eredményessége, az infokommunikációs eszközök használatának sajátosságai és az önszabályozó tanulás fejlettsége közötti összefüggések feltárása

Adsorption of an active molecule on the surface of halloysite for controlled release application: Interaction, orientation, consequences

The goal of the study was to check the possible use of halloysite (Hal) nanotubes as a controlled release natural antioxidant device with quercetin as the active component. The mineral was thoroughly characterized by various techniques including the determination of particle and tube morphology, specific surface area, pore size and volume, and surface energy. The high surface energy of Hal predicted strong adsorption of active molecules on its surface and consequently difficult release. FTIR spectroscopy confirmed the existence of strong interactions, energetically heterogeneous Hal surface and multilayer coverage at large loadings. FTIR and XRD experiments proved the complete lack of intercalation and showed that below 3.5 wt% quercetin loading, most of the molecules are located within the Hal tubes. Molecular modeling indicated the parallel orientation of quercetin molecules with the surface. Critical concentrations derived from various measurements agreed well with each other further confirming that up to about 4.0 wt% loading, quercetin is bonded very strongly to the Hal surface. As a consequence, the dissolution of active molecules is very difficult or impossible, especially into apolar media; thus, neither stabilization nor controlled release effect can be expected below that concentration

Reduced-Scaling Approach for Configuration Interaction Singles and Time-Dependent Density Functional Theory Calculations Using Hybrid Functionals

An approximation is presented which can efficiently decrease the computational expenses of configuration interaction singles (CIS) and time-dependent density functional theory (TDDFT) methods employing hybrid functionals. The approach is the adaptation of the local density fitting scheme developed for Hartree−Fock (HF) calculations for excited states and reduces the quartic scaling of the methods to cubic. It can also be applied to related methods, such as the time-dependent HF and Tamm−Dancoff approximation TDDFT approaches. Our benchmark calculations show that, for molecules of 50−100 atoms, average speedups of 2−4 can be achieved for CIS and TDDFT calculations at the expense of negligible errors in the calculated excitation energies and oscillator strengths, but for bigger systems or molecules of localized electronic structure significantly larger speedups can be gained. We also demonstrate that the approximation enables excited-state calculations on a single processor even for molecules of 1000 atoms using basis sets augmented with diffuse functions including more than 17 000 atomic orbitals

Unconventional bond functions for quantum chemical calculations

New types of bond function (BF) basis sets are proposed and tested for quantum chemical applications. First, BF basis sets constituted of conventional Gaussiantype orbitals (GTO) are considered. Both the exponents and the positions of the BFs are optimized, but, in contrast to previous studies, the position of each BF shell is varied separately. Second, new types of basis functions, the general ellipsoidal Gaussian-type orbitals (EGTOs), are proposed for quantum chemical applications. The EGTOs are distorted spherical GTOs and, as such, are expected to be well suited for describing the polarized charge densities in molecular environments. EGTOs can be used either as atom-centered (AC) basis functions or as BFs. In this study, the latter possibility is explored, and BF basis sets including EGTOs are optimized and compared to those containing only conventional GTO BFs. The performance of the developed GTO and EGTO BF basis sets is assessed for Hartree-Fock and density functional calculations against conventional AC GTO basis sets. Our results show that using GTO BF basis sets, the results are significantly improved, while the number of the basis functions can be decreased by about 10 %, which is not dramatic; however, the average angular momentum quantum number in the BF sets is significantly lower. The accuracy of the computed energies can be further increased by about 15 % if EGTO BFs are used