Ground-state properties of neutron magic nuclei

A systematic study of the ground-state properties of the entire chains of even–even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82, and 126 has been carried out using relativistic mean-field plus Bardeen–Cooper–Schrieffer approach. Our present investigation includes deformation, binding energy, two-proton separation energy, single-particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using nonrelativistic approach (Skyrme–Hartree–Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip-lines, the (Z, N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.     

Simulation of Fibrillation of PC/LCP/Kevlar Blends and Its Characterizations

Kevlar fiber was fluorinated and oxy-fluorinated directly in presence of undiluted fluorine and fluorine gas mixture and processed with Polycarbonate and LCP at 320 °C under 20 rpm in a twin-screw extruder. The composites were then injection molded into dumbbell shaped specimens under different conditions like various mold temperatures, injection temperatures, injection speeds and mold filling rates. Various physico-chemical characterizations have been performed under definite processing parameter. Orientation of fibers under different injection parameters was evaluated using mold flow simulation technique. Most injection molded or extruded structures however, exhibit non-uniform fiber orientation across the final parts, with a diverging variety of different local fiber orientation states. Distinct skin and core regions were observed in the injection molded parts and it has also been found out that fiber orientation is different in skin and core region for both unmodified and modified derivative, which affects the flow behavior. Processing parameters significantly affect the fiber orientation pattern in the skin and core region for all blended materials. It is worth mentioning that the maximum fiber orientation occurred during the extrusion process at the wall but different extent of fiber orientation is observed during the injection molding depending on the shape of the dumbbell specimen. This fibrillation has been corroborated by the SEM study in both the skin and core region.     

Nanostructured zirconium oxide based genosensor for Escherichia coli detection

A deoxyribonucleic acid (DNA) biosensor has been fabricated via immobilization of 17 base terminal single stranded DNA (ssDNA) identified from the 16s rRNA coding region of Escherichia coli onto sol–gel derived nanostructured zirconium oxide (NanoZrO₂) film. An oligonucleotide probe with a terminal 5′-phosphate group has been attached to the surface of the electrode via affinity of NanoZrO₂ for phosphate. The results of hybridization studies carried out with the complementary, non-complementary and genomic DNA reveal that ssDNA/NanoZrO₂/ITO bioelectrode has a high selectivity and sensitivity towards hybridization detection with limits of 10^?6–10⁶ pM of complementary DNA.     

Supramolecular self-assembly of dendronized polymers: reversible control of the polymer architectures through acid-base reactions

Acid-base switchable supramolecular dendronized polyacetylenes (DPAs) with increasing steric bulk on going from generation one [G1] to three [G3], were constructed using multiple self-assembly processes between Fréchet-type [G1]-[G3]-dendritic dialkylammonium salts and a dibenzo[24]crown-8-containing polymer. The formation of the supramolecular systems is acid-base switchable to either an ON (rodlike dendronized polymers) or an OFF (flexible polymers) state. Thus, by controlling the superstructures of the supramolecular polymers with the [G1]-[G3] dendrons, it is possible to induce conformational changes within the polymer backbones. The supramolecular dendronized polymers, as well as their threading-dethreading properties, were characterized by (1)H NMR and UV absorption spectroscopies, gel permeation chromatography (GPC) and light scattering (LS). Independent measures of molecular weight (GPC, LS) indicate that DPAs behave as increasingly rigid macromolecules with each generation in solution. Molecular dynamics simulations of each DPA suggest that the lengths of the polymer backbones increase accordingly. Atomic force microscopy of the [G3]-dendronized polystyrene (DPS), as well as the DPAs, reveal surface morphologies indicative of aggregated superstructures.     

Nanofibril self-assembly of an arylene ethynylene macrocycle

Nanofibril structures have been fabricated from an arylene ethynylene macrocycle (AEM), which consists of a square frame corner-joined by four carbazole moieties. The fabrication was performed through a gelating process by cooling a warm, homogeneous solution in cyclohexane at high temperature (e.g., 100 degrees C) to room temperature. During the gelation, the molecules become organized, with optimal pi-pi stacking in cooperation with the side-chain association. The favorable pi-pi stacking facilitates the 1D growth of molecular assembly.     

An improved method to detect ethyl glucuronide in urine using reversed-phase liquid chromatography and pulsed electrochemical detection

Pulsed electrochemical detection (PED) following reversed-phase liquid chromatography (LC) has been applied recently to the detection of ethyl glucuronide (EtG) in the urine of live and deceased individuals. In this paper, several key improvements to the method are made to enhance sensitivity, reproducibility, and accuracy. These improvements include (i) further optimization of the sample preparation procedure that has increased the recovery from ca. 50% to 84 ± 3% in synthetic urine matrix; (ii) changing the internal standard from methyl glucuronide (MetG) to propyl glucuronide (ProG), which does not elute within the interference of the matrix; and (iii) altering the mobile phase of the separation from acetonitrile to t-butanol to virtually eliminate signal suppression in PED. As a consequence, detection limits have been reduced to 0.01 μg mL⁻¹, reproducibility has been improved by a factor of two, and sample size has been reduced five-fold. Blind studies in synthetic urine showed no significant difference between the amount recovered and the true value determined at the 95% confidence level for all samples. Importantly, PED requires no derivatization, and it can detect virtually all glucuronides.     

PNIPAM Copolymers Containing Light‐Responsive Chromophores: A Method Toward Molecular Logic Gates

A series of thermo‐responsive PNIPAM copolymers containing different amounts of fulgimide moieties has been synthesized via a polymer analogous reaction of poly(pentafluorophenyl acrylate). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in water, which was only weakly dependent on the amount of incorporated chromophoric fulgimide groups. The copolymers showed a photocyclization of the fulgimide side groups upon irradiation with UV‐light accompanied with a color change. The closed form of the chromophore had a halftime of 136 min for the visible reisomerization and did not affect the LCST of the polymer. This led to the realization of a logic “NOT A” for the fulgimide containing PNIPAM, while a corresponding azobenzene containing PNIPAM resulted in a different logic “A implies B”.

     

On the Sachs bound in stress-induced phase transformations in polycrystalline scalar shape-memory alloys

We consider stress–induced transformations of polycrystalline shape–memory alloys which are so–called scalar materials. In this case the Sachs bound on the phase transformation yield stress turns out to be sharp. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)