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.     

Formulation Optimization of a Palm-Based Nanoemulsion System Containing Levodopa

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%–12% w/w), lecithin (1%–3% w/w), and Cremophor EL (0.5%–1.5% w/w) as well as the preparation method; addition rate (2–20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.     

Recent trends in steel fibered high-strength concrete

Steel fibered high-strength concrete (SFHSC) became in the recent decades a very popular material in structural engineering. High strength attracts designers and architects as it allows improving the durability as well as the esthetics of a construction. As a result of increased application of SFHSC, many experimental studies are conducted to investigate its properties and to develop new rules for proper design. One of the trends in SFHSC structures is to provide their ductile behavior that is desired for proper structural response to dynamic loadings. An additional goal is to limit development and propagation of macro-cracks in the body of SFHSC elements. SFHSC is tough and demonstrates high residual strengths after appearance of the first crack. Experimental studies were carried out to select effective fiber contents as well as suitable fiber types, to study most efficient combination of fiber and regular steel bar reinforcement. Proper selection of other materials like silica fume, fly ash and super plasticizer has also high importance because of the influence on the fresh and hardened concrete properties. Combination of normal-strength concrete with SFHSC composite two-layer beams leads to effective and low cost solutions that may be used in new structures as well as well as for retrofitting existing ones. Using modern nondestructive testing techniques like acoustic emission and nonlinear ultrasound allows verification of most design parameters and control of SFHSC properties during casting and after hardening. This paper presents recent experimental results, obtained in the field SFHSC and non-destructive testing. It reviews the experimental data and provisions of existing codes and standards. Possible ways for developing modern design techniques for SFHSC structures are emphasized.     

Evaluation of the strength of explosion‐welded bimetallic sheets produced under combined loading conditions

In this paper, conditions for vertical weld defectless formation at horizontal electron-beam welding (EBW) are shown and power-complex selection methods to weld thick-walled constructions by electron beam are developed. Dependences to estimate EBW optimal conditions are obtained.     

Dynamics of support perceptions among couples coping with cardiac illness: The effect on recovery outcomes.

Objective: The current prospective study explored how male cardiac patients' perceptions of received support (i.e., active engagement, protective buffering, and overprotection) moderated the associations between female partners' perceptions of provided support and patients' recovery outcomes: psychological well-being, cholesterol levels, and smoking cessation. Methods: Couples (N = 86) completed surveys at the initial hospitalization after patients' Acute Coronary Syndrome (ACS), and 1 and 6 months later. Partners' ways of providing support and patients' concurrent perceptions of these ways were measured using the Ways of Giving Support Questionnaire; patients' depressive and anxiety symptoms were measured using the Brief Symptom Inventory (BSI). Patients' cholesterol levels were assessed during hospitalization and 6 months later, and smoking habits were reported by the patients. Results: Female partners' protective buffering was positively associated with male patients' depressive symptoms at follow-up only when male patients' own perceptions of partners' protective buffering were low. Female partners' active engagement was positively associated with better odds for male patients' cessation of smoking only when patients' own perceptions of partners' active engagement were high. Finally, female partners' overprotection was associated with higher levels of male patients' harmful blood lipids at follow-up, but only when patients' own perceptions of partners' overprotection were high. Conclusions: As hypothesized, the effect of partners' perceptions of support provided on patients' recovery was moderated by patients' own perceptions of the support received. The effect of this interaction was determined by the specific types of support provided or received and by the specific recovery outcome that was measured. The clinical and theoretical implications of the findings are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Evaluation of the corrosion resistance of explosion‐welded bimetals

New equipment and technologies for low-frequency vibrational treatment of components in engineering are examined. The design of new equipment and its technological characteristics are described, the technology of stress relieving after welding, casting, machining, etc. is discussed, and equipment for inspecting the stresses prior to and after treatment is analysed.     

Physicochemical properties of fermented Arabian mares' milk

Due to its numerous benefits, including health-promoting characteristics, there is increasing interest in finding product applications for mares' milk. In the present study, the physicochemical properties, turbidity and conductivity of Arabian mares' milk were studied during acidification by fermentation at 30 °C and compared with those of bovine milk. The data for the acidification rate were modelled using a logistic equation. Mares' milk showed a longer latency phase (284 min) and lower acidification rate (μ_max = 0.0052 dpH min^?1) compared with bovine milk (194 min and 0.0098 dpH min^?1 respectively). The general shape of the curves of the turbidity versus time and pH were similar in nature for the acidification of both milks. However, the characteristic points were different, due to the differences in casein micelle composition. Measurement of electrical conductivity during acidification showed that maximum demineralization of casein micelles started around pH 6.09 and 5.31, for mares' and bovine milk, respectively. In conclusion, the technological characteristics of mares' milk were very different from those of bovine milk, due to intrinsic physicochemical properties of both milks.     

Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations

Using ab initio calculations on Zn_{0.975? x} Fe_0.025Cu _x O (x = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn_{0.975? x} Fe_0.025Cu _x O.     

Biexciton emission and crystalline quality of ZnO nano-objects

The design of cost-effective standards for the quality of nano-objects is currently a key issue toward their massive use for optoelectronic applications. The observation by photoluminescence of narrow excitonic and biexcitonic emission lines in semiconductor nanowires is usually accepted as evidence for high structural quality. Here, we perform time-resolved cathodoluminescence experiments on isolated ZnO nanobelts grown by chemical vapor deposition. We observe narrow emission lines at low temperature, together with a clear biexciton line. Still, drastic alterations in both the CL intensity and lifetime are observed locally along the nano-object. We attribute these to non-radiative recombinations at edge dislocations, closing basal plane stacking faults, inhomogeneously distributed along the NB length. This leads us to the conclusion that the observation of narrow excitonic and biexcitonic emission lines is far from sufficient to grade the quality of a nano-object.     

On the realizability of reynolds stress turbulence closures

The realizability of Reynolds stress models in homogeneous turbulence is critically assessed from a theoretical standpoint. It is proven that a well known second-order closure model formulated using the strong realizability constraints of Schumann (1977) and Lumley (1978) is, in fact, not a realizable model. The problem arises from the failure to properly satisfy the necessary positive second time derivative constraint when a principal Reynolds stress vanishes-a flaw that becomes apparent when the nonanalytic terms in the model are made single-valued as required on physical grounds. More importantly, arguments are advanced which suggest that it is impossible to identically satisfy the strong from of realizability in any version of the present generation of second-order closures. On the other hand, models properly formulated to satisfy the weak form of realizability—wherein states of one or two component turbulence are made inaccessible in finite time via the imposition of a positive first derivative condition—are found to be realizable. However, unlike the simpler and more commonly used second-order closures, these models can be ill-behaved near the extreme limits of realizable turbulence due to the way that higher-degree nonlinearities are often unnecessarily introduced to satisfy realizability. Illustrative computations of homogeneous shear flow are presented to demonstrate these points which can have important implications for turbulence modeling.