Insights into intrastrand cross-link lesions of DNA from QM/MM molecular dynamics simulations

DNA damages induced by oxidative intrastrand cross-links have been the subject of intense research during the past decade. Yet, the currently available experimental protocols used to isolate such lesions only allow to get structural information about linked dinucleotides. The detailed structure of the damaged DNA macromolecule has remained elusive. In this study we generated in silico the most frequent oxidative intrastrand cross-link adduct, G[8,5-Me]T, embedded in a solvated DNA dodecamer by means of quantum mechanics/molecular mechanics (QM/MM) Car-Parrinello simulations. The free energy of activation required to bring the reactant close together and to form the C-C covalent-bond is estimated to be ~10 kcal/mol. We observe that the G[8,5-Me]T tandem lesion is accommodated with almost no perturbation of the Watson-Crick hydrogen-bond network and induces bend and unwinding angles of ~20° and 8°, respectively. This rather small structural distortion of the DNA macromolecule compared to other well characterized intrastrand cross-links, such as cyclobutane pyrimidines dimers or cisplatin-DNA complex adduct, is a probable rationale for the known lack of efficient repair of oxidative damages.     

Click-Modified Anandamide siRNA Enables Delivery and Gene Silencing in Neuronal and Immune Cells

Click chemistry of alkyne-modified RNA with different receptor ligand azides was used to prepare 3'-folate, 3'-cholesterol, and, as a new entity, 3'-anandamide-modified RNA in high yields and excellent purity. The anandamide-modified RNA shows surprisingly high transfection properties and enables the delivery of siRNA even into difficult-to-transfect RBL-2H3 cells which model neuronal uptake. Furthermore, the system was employed in human immune cells (BJAB), demonstrating silencing effects similar to those of a cationic, benchmark transfection reagent. In addition, the anandamide conjugates were found to be nontoxic. The reported chemistry and the described properties of the anandamide siRNA extend the possibilities of using siRNA-based gene silencing in neuronal and immune cells.     

Perceived parental influence and students' dispositions to study mathematically-demanding courses in Higher Education

We explore the influence of family on adolescent students' mathematical habitus by investigating the association between students' perceptions of parental influence and their dispositions towards mathematics. A construct measuring ‘perceived parental influence’ was validated using Rasch methodology on data from 563 Cypriot students on ‘core’ and ‘advanced’ mathematics pre-university courses, and was then used to predict students' dispositions towards future study of mathematically-demanding courses at university. In most of the regression models, perceived parental influence was not associated significantly with students' dispositions towards mathematics, when other variables were included in the models. However, further statistical analysis showed that perceived parental influence is mediated by (i) the mathematics course students are studying and (ii) their mathematical inclination. We suggest that family influences on students' dispositions are significantly accounted for by students' prior choice of mathematics course and the family's inculcation of their mathematical inclination; these are important factors influencing university choices.     

Catalytic ignition of light hydrocarbons over Rh/Al2O3 studied in a stagnation-point flow reactor

The ignition (light-off) temperatures of catalytic oxidation reactions provide very useful information for understanding their surface reaction mechanism. In this study, the ignition behavior of the oxidation of hydrogen (H₂), carbon monoxide (CO), methane (CH₄), ethane (C₂H₆), and propane (C₃H₈) over Rh/alumina catalysts is examined in a stagnation-point flow reactor. The light-off temperatures are identified by means of the sudden increase of the catalyst temperature when linearly heating the catalyst for various fuel/oxygen ratios. For hydrogen and all hydrocarbons studied, the results show a rise of ignition temperature with increasing fuel/oxygen ratio, whereas the opposite trend is observed for the light-off of CO oxidation. Hydrogen oxidation, however, shows an opposite trend compared to previous investigations, performed on platinum [1], [2].     

Optical system design and experimental evaluation of a coherent Doppler wind Lidar system for the predictive control of wind turbine

The control of wind turbine blade pitch systems by Lidar assisted wind speed prediction has been proposed to increase the electric power generation and reduce the mechanical fatigue load on wind turbines. However, the sticking point of such Lidar systems is the price. Hence, our objective is to develop a more cost efficient Lidar system to support the pitch control of horizontal axis wind turbines and therefore to reduce the material requirement, lower the operation and maintenance costs and decrease the cost of wind energy in the long term. Compared to the state of the art Lidar systems, a laser with a shorter coherence length and a corresponding fiber delay line is introduced for reducing the costs. In this paper we present the experimental evaluation of different sending and receiving optics designs for such a system from a free space laboratory setup.     

Optimal lower bounds on asymptotic support propagation rates for the thin-film equation

We derive lower bounds on asymptotic support propagation rates for strong solutions of the Cauchy problem for the thin-film equation. The bounds coincide up to a constant factor with the previously known upper bounds and thus are sharp. Our results hold in case of at most three spatial dimensions and n∈(1,2.92)$n\in (1,2.92)$. The result is established using weighted backward entropy inequalities with singular weight functions to yield a differential inequality; combined with some entropy production estimates, the optimal rate of propagation is obtained. To the best of our knowledge, these are the first lower bounds on asymptotic support propagation rates for higher-order nonnegativity-preserving parabolic equations.     

Chemically fueled materials with a self-immolative mechanism: transient materials with a fast on/off response

There is an increasing demand for transient materials with a predefined lifetime like self-erasing temporary electronic circuits or transient biomedical implants. Chemically fueled materials are an example of such materials; they emerge in response to chemical fuel, and autonomously decay as they deplete it. However, these materials suffer from a slow, typically first order decay profile. That means that over the course of the material''s lifetime, its properties continuously change until it is fully decayed. Materials that have a sharp on–off response are self-immolative ones. These degrade rapidly after an external trigger through a self-amplifying decay mechanism. However, self-immolative materials are not autonomous; they require a trigger. We introduce here materials with the best of both, i.e., materials based on chemically fueled emulsions that are also self-immolative. The material has a lifetime that can be predefined, after which it autonomously and rapidly degrades. We showcase the new material class with self-expiring labels and drug-delivery platforms with a controllable burst-release.

We describe a design strategy for transient materials with a predefined lifetime and a fast on–off-response.     

La(Ni2/3Nb1/3)O3 by neutron powder diffraction

Lanthanum nickel niobium trioxide has been synthesized and its structure refined for the first time. It was found to be a member of the family of technologically important `double perovskites', crystallizing in the monoclinic space group P2₁/n. The structure is characterized by a strong orthorhombic pseudosymmetry and a concurrent exhibition of both 1:1 B‐cation ordering and a⁻a⁻c⁺‐type tilting of the (Ni/Nb)O₆ structural units. Trivalent lanthanum resides on the perovskite A site, which is strongly distorted owing to the tilting of the (Ni/Nb)O₆ sublattice. Ordering of divalent nickel and pentavalent niobium on the B sublattice is described in terms of two twofold special positions (2c and 2d), with nickel taking almost complete occupancy of the 2d site and the 2c position being occupied by a statistical distribution of nickel and niobium.