Base‐Pairing Behavior of a Carbocyclic Janus‐AT Nucleoside Analogue Capable of Recognizing A and T within a DNA Duplex

Janus‐type nucleosides are heterocycles with two faces, each of which is designed to complement the H‐bonding interactions of natural nucleosides comprising a canonical Watson–Crick base pair. By intercepting all of the hydrogen bonds contained within the base pair, oligomeric Janus nucleosides are expected to achieve sequence‐specific DNA recognition through the formation of J‐loops that will be more stable than D‐loops, which simply replaces one base‐pair with another. Herein, we report the synthesis of a novel Janus‐AT nucleoside analogue, J_AT, affixed on a carbocyclic analogue of deoxyribose that was converted to the corresponding phosphoramidite. A single J_AT was successfully incorporated into a DNA strand by solid phase for targeting both A and T bases, and characterized through biophysical and computational methods. Experimental UV‐melting and circular dichroism data demonstrated that within the context of a standard duplex, J_AT associates preferentially with T over A, and much more poorly with C and G. Density functional theory calculations confirm that the J_AT structure is well suited to associate only with A and T thereby highlighting the importance of the electronic structure in terms of H‐bonding. Finally, molecular dynamics simulations validated the observation that J_AT can substitute more effectively as an A‐analogue than as a T‐analogue without substantial distortion of the B‐helix. Overall, this new Janus nucleotide is a promising tool for the targeting of A–T base pairs in DNA, and will lead to the development of oligo‐Janus‐nucleotide strands for sequence‐specific DNA recognition.     

Thermo-mechanical characteristics of concrete at elevated temperatures up to 310 °C

Both, the normal strength concretes (NSC) and high strength concretes (HSC) have been used in structures which may be exposed to elevated temperatures. Concretes have also been used in the construction of radiation shielding structures. Data on the behaviour of concrete at high temperature is of prime concern in predicting the constructions and safety of buildings in response to certain accidents or particular service conditions. Prediction of mechanical behaviour, thermo-mechanical deformations and moisture migration in non-uniformly heated concrete is important for safe operation of concrete containment.This paper presents the results of an experimental investigation carried out to predict the behaviour of concrete intended for nuclear applications. For this purpose, normal concrete having compressive strength of 40 MPa was designed using limestone aggregates. Cylindrical specimens (110 mm × 22 mm) were made and subjected to heating-cooling cycles at 110, 210 and 310 °C. Measurements were taken for thermal gradient, mass loss, deformations, residual mechanical properties, thermal conductivity, and porosity. This investigation developed some important data on the properties of concrete exposed to elevated temperatures up to 310 °C. Comparisons and interesting conclusions were drawn about the thermal stability at high temperature and the residual mechanical properties of the tested concrete.     

Modelling mechanical properties of spruce and Douglas fir timber by means of X-ray and grain angle measurements for strength grading purpose

This study proposes a model using data from a scanner (X-ray and grain angle measurements) to perform strength grading. The research also includes global measurements of modulus of elasticity (obtained by vibrations and ultrasound methods), static bending stiffness and bending strength of 805 boards of Douglas fir and 437 boards of spruce. This model can be used in an industrial context since it requires low computational time. The results of this study show that the developed model gives better results than the global non-destructive measurements of the elastic modulus commonly used in the industry. It also shows that this improvement is particularly higher in the case of Douglas fir than for spruce. The comparison has been made on both the quality of the mechanical properties assessment and on the improvement of the grading process according to the European standards by using different index.     

Mechanical behaviour of fired clay materials subjected to freeze–thaw cycles

The aim of this paper is to study the frost durability of fired clay materials. The behaviour of five fired clay materials with different physical and mechanical properties (porosity, permeability, mechanical strengths and elasticity modulus) subjected to freeze–thaw cycles is analysed. The strains of specimens and the evolution of the main properties with the number of cycles are assessed. The analysis shows that the pore distribution is not the only important parameter but that the tensile strength is also significant. A complete data bank is thus built up to study the effects of the physical and mechanical parameters on frost resistance and to determine how these parameters are affected by frost cycles. It will be possible to use these data to improve the modelling of coupled thermo-hydro-mechanical phenomena involved during the freezing and thawing process in porous media.     

Physical market determinants of the price of crude oil and the market premium

We analyze the determinants of the real price of crude oil by means of an equilibrium correction model over the last two decades where we focus on the aspects of the physical market that impact on the clearing price. We find that two cointegrating relations affect the changes in prices: one refers to OPEC's behavior, attempting to control prices using its market power and quotas; the other to the coverage rate of OECD expected future demand using inventory behaviors. We derive a forecasting equation for the change in oil prices which we use to assess the speculative elements of the price increases of the period 2000–05. We show that worries alien to the physical markets were the causes of the increase in oil prices and we quantify their overall impact.     

Thermal grafting of organic monolayers on amorphous carbon and silicon (111) surfaces: A comparative study

Thermally-assisted (160 °C) liquid phase grafting of linear alkene molecules has been performed simultaneously on amorphous carbon (a-C) and hydrogen passivated crystalline silicon Si(111):H surfaces. Atomically flat a-C films with a high sp³ average surface hybridization, sp³ / (sp² + sp³) = 0.62, were grown using pulsed laser deposition (PLD). Quantitative analysis of X-ray photoelectron spectroscopy, X-ray reflectometry and spectroscopic ellipsometry data show the immobilization of a densely packed (> 3 × 10¹⁴ cm^? 2) single layer of organic molecules. In contrast with crystalline Si(111):H and other forms of carbon films, no surface preparation is required for the thermal grafting of alkene molecules on PLD amorphous carbon. The molecular grafted a-C surface is stable against ambient oxidation, in contrast with the grafted crystalline silicon surface.     

Elimination protocols in atopic dermatitis

Both dacryocystography and dacryoscintigraphy are well established in the evaluation of stenoses of the lacrimal drainage system. They provide limited information about the ductal anatomy itself and about periductal structures. MR imaging was evaluated for its capability to directly visualize the lacrimal drainage system in detail and simultaneously provide functional characterization of dacryostenosis. SUBJECTS AND METHODS: Twenty-seven lacrimal drainage systems of 23 patients suffering from epiphora were examined in an MR unit before and after conjunctival and intravenous application of Gd-DTPA using a surface coil. RESULTS: Dacryostenosis was found in 23 of 27 lacrimal systems. Stenoses were localized to the canalicular (n = 3), saccular (n = 8), and ductal (n = 12) level, and were classified as stenosis or occlusion. CONCLUSION: MR imaging with conjunctival contrast application allows within one examination both detailed morphological and functional assessment of the lacrimal drainage system with depiction of surrounding structures. Limitations arise mainly from demands on technical and patient-related preconditions.