Rational design of a triple helix-specific intercalating ligand

DNA triple helices offer new perspectives toward oligonucleotide-directed gene regulation. However, the poor stability of some of these structures might limit their use under physiological conditions. Specific ligands can intercalate into DNA triple helices and stabilize them. Molecular modeling and thermal denaturation experiments suggest that benzo[f]pyrido[3, 4-b]quinoxaline derivatives intercalate into triple helices by stacking preferentially with the Hoogsteen-paired bases. Based on this model, it was predicted that a benzo[f]quino[3,4-b]quinoxaline derivative, which possesses an additional aromatic ring, could engage additional stacking interactions with the pyrimidine strand of the Watson-Crick double helix upon binding of this pentacyclic ligand to a triplex structure. This compound was synthesized. Thermal denaturation experiments and inhibition of restriction enzyme cleavage show that this new compound can indeed stabilize triple helices with great efficiency and specificity and/or induce triple helix formation under physiological conditions.     

A quantitative treatment of oscillatory phenomena in coarse-grained ion-exchanger membranes

The treatment developed in this text concerns the ion flux, volume flux and electric current through the highly porous ion-exchanger membrane of the Teorell membrane oscillator. It is based on the concept that inside the membrane exists a concentration profile of defined shape depending mainly on the volume flux caused by the hydrostatic pressure and the electro-osmotic effect of the membrane potential within the reach of the electric charge of the ion-exchanger grains forming the membrane texture.In particular it is shown that under conditions of zero volume flux the effective fixed charge responsible for the electro-osmotic driving force can be determined directly by measuring the hydrostatic pressure and its compensating electric potential. Like the electro-osmotic effect, also the derived flux equations proved to be independent of the special feature of the grain texture.The simultaneous differential equations describing the temporal (oscillatory) behaviour of the Teorell membrane system are derived on the basis of these flux equations leading to analog computer solutions which agree well with the experimental data.     

Study of normal incidence of three-component multilayer mirrors in the range 20-40 nm

We study theoretically and experimentally the increase of normal incidence reflectivity generated by addition of a third material in the period of a standard periodic multilayer, for wavelengths in the range 20 to 40 nm. The nature and thickness of the three materials has been optimized to provide the best enhancement of reflectivity. Theoretical reflectivity of an optimized B4C/Mo/Si multilayer reaches 42% at 32 nm. B4C/Mo/Si multilayers have been deposited with a magnetron sputtering system and a reflectivity of 34% at 32 nm has been measured on a synchrotron radiation source.     

Some concepts for languages more powerful than context-free

Some new restrictive devices for grammars are introduced: standard control-sets, G-control-sets, checking state grammars, besides the wellknown ones: matrix-sets, regular control-sets, programs. All these concepts turn out to be equivalent with respect to their generative power. So we get further characterizations of the class of recursively enumerable sets. The generative power of context-freelabel-grammars and Chomsky-grammars both with these restrictive devices is found to be equal. New characterizations of the unconditional-transfer programmed-grammars are introduced, namely unconditional-transfer programs correspond to all the other devices mentioned above under so-called “full-checking possibility” — i.e. the whole set of labels is the checking-set.     

Updated estimates of HAL n and RN− effects on pork quality: Fresh and processed loin and ham

A 1000-pig F2 intercross QTL detection experimental population was generated using two commercial sire lines. Independent carriers of HAL n and RN− mutations (10% and 14%, respectively) were included in this population as control genotypes. The effects of HAL n and RN− heterozygous genotypes on fresh and transformed loins and hams were estimated using a mixed model methodology. The results document the unfavorable effects of both mutations on meat quality. Smaller effects of HAL Nn genotype compared to HAL nn or RN−rn+ genotypes were estimated. Interestingly, effects of HAL Nn genotype on meat pH and loin color could be insignificant at 24-h postmortem, but translate into higher water losses on storage and cooking, and result in tougher cooked loin. Using the same methodology, significant effects of the PRKAG3 (RN) I199 allele on ultimate pH values but not on glycolytic potential were observed.     

Small-animal MRI: signal-to-noise ratio comparison at 7 and 1.5 T with multiple-animal acquisition strategies

Objective: The purpose of this study was to compare the signal-to-noise ratio (SNR) of phantom and rat brain images performed at 1.5 T on a clinical MR system and at 7 T on a small-animal experimental system. Comparison was carried out by taking into account SNR values based on a single sample acquisition at 1.5 and 7 T as well as on simultaneous imaging of multiple samples at 1.5 T. Methods: SNR was experimentally assessed on a phantom and rat brains at 1.5 and 7 T using 25 mm surface coils and compared to theoretical SNR gain estimations. The feasibility of multiple-animal imaging, using the hardware capabilities available on the 1.5 T system, was demonstrated. Finally, rat brain images obtained on a single animal at 7 T and on multiple animals acquired simultaneously at 1.5 T were compared. Results: Experimentally determined SNR at 7 T was far below theoretical estimations. Taking into account chemical shift, susceptibility artifacts and modifications of T1 and T2 relaxation times at higher field, a 7-T system holds limited advantage over a 1.5-T system. Instead, a multiple-animal acquisition methodology was demonstrated on a clinical 1.5-T scanner. This acquisition method significantly increases imaging efficiency and competes with single animal acquisitions at higher field. Conclusion: Multiple-animal imaging using a standard clinical scanner has a great potential as a high-throughput acquisition method for small animals.     

Thermal decomposition kinetics of dynamically vulcanized polyamide 6–acrylonitrile butadiene rubber–halloysite nanotube nanocomposites

Thermally stable thermoplastic elastomer nanocomposites based on polyamide 6 (PA6), acrylonitrile butadiene rubber (NBR), and halloysite nanotubes (HNTs) were dynamically vulcanized, and their nonisothermal decomposition kinetics were examined. The Friedman, Kissinger–Akahira–Sunose (KAS), Ozawa–Wall–Flynn (FWO), and modified Coats–Redfern (m-CR) isoconversional models were used to obtain information about the kinetics of the thermal decomposition of PA6–NBR–HNTs in terms of the activation energy per partial mass loss monitored through thermogravimetric analyses performed at different heating rates. An erratic trend was due to the Friedman model, especially for systems having higher HNT loadings, whereas the KAS, FWO, and m-CR models revealed very similar meaningful thermal decomposition kinetics. A relatively high activation energy corroborating a reliable thermal stability was obtained by the addition of HNTs to PA6–NBR, and the resistance against decomposition was higher for systems containing more HNT. This signified the role of the HNTs as thermal stability modifiers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47483.