Two Families of Entanglement-Assisted Quantum MDS Codes from Cyclic Codes

International Journal of Theoretical Physics - With entanglement-assisted (EA) formalism, arbitrary classical linear codes are allowed to transform into EAQECCs by using pre-shared entanglement...     

Sorption of radioeuropium onto attapulgite: effect of experimental conditions

Batch sorption experiments were performed to remove Eu(III) ions from aqueous solutions by using attapulgite under ambient conditions. Different experimental conditions, such as contact time, solid content, foreign ions, pH, ionic strength, fulvic acid and temperature, have been investigated to study their effect on the sorption property. The results indicated that the sorption of Eu(III) onto attapulgite was strongly dependent on pH, ionic strength and temperature. The sorption increased from about 8.9 to 90% at pH ranging from 2 to 6 in 0.01 mol/L NaNO₃ solution. The Eu(III) kinetic sorption on attapulgite was fitted by the pseudo-second-order model better than by the pseudo-first-order model. The sorption of Eu(III) onto attapulgite increased with increasing temperature and decreasing ionic strength. The Langmuir and Freundlich models were used to simulate the sorption isotherms, and the results indicated that the Freundlich model simulated the data better than the Langmuir model. The thermodynamic parameters (∆G ^o, ∆S ^o, ∆H ^o) were determined from the temperature dependent isotherms at 298.15, 318.15 and 338.15 K, and the results indicated that the sorption reaction was an endothermic and spontaneous process. The results suggest that the attapulgite is a suitable material as an adsorbent for preconcentration and immobilization of Eu(III) from aqueous solutions.     

Dual Illumination Enhances Transformation of an Engineered Green-to-Red Photoconvertible Fluorescent Protein

The molecular mechanisms for the photoconversion of fluorescent proteins remain elusive owing to the challenges of monitoring chromophore structural dynamics during the light-induced processes. We implemented time-resolved electronic and stimulated Raman spectroscopies to reveal two hidden species of an engineered ancestral GFP-like protein LEA, involving semi-trapped protonated and trapped deprotonated chromophores en route to photoconversion in pH 7.9 buffer. A new dual-illumination approach was examined, using 400 and 505 nm light simultaneously to achieve faster conversion and higher color contrast. Substitution of UV irradiation with visible light benefits bioimaging, while the spectral benchmark of a trapped chromophore with characteristic ring twisting and bridge-H bending motions enables rational design of functional proteins. With the improved H-bonding network and structural motions, the photoexcited chromophore could increase the photoswitching-aided photoconversion while reducing trapped species.     

Preparation and characterization of nanosized TiO2 powder as an inorganic adsorbent for aqueous radionuclide Co(II) ions

In this research TiO₂ sample was synthesized by a simple sol–gel method and was characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques. The XRD result indicated that the obtained product was anatase titanium dioxide with high purity, the TEM image clearly showed that the particle sizes of TiO₂ nanoparticles were in the range of 30–70 nm, and the measured BET surface area of the heated TiO₂ nanoparticles was 147.14 m²/g. In this work, the prepared TiO₂ sample was used as a new adsorbent for the adsorption of radionuclide Co(II) ions from aqueous solutions, and the influence of pH, contact time, ionic strength and temperature in the presence or absence of humic acid/fulvic acid (HA/FA) were also investigated. The experimental results indicated that the adsorption of Co(II) ions onto TiO₂ was strongly pH-dependent. Based on the surface complexation, the presence of HSs enhanced the adsorption of Co(II) ions and the influence of Co(II) adsorption onto FA–TiO₂ hybrids was much stronger than that of HA–TiO₂ at pH values of 2.0–9.0. Adsorption of Co(II) ions onto TiO₂ powder was strongly dependent on ionic strength. The adsorption process mainly occured in the first contact time of 2 h and could be fitted by a pseudo-second-order rate model. The calculated thermodynamic data indicated that the adsorption of Co(II) ions onto TiO₂ was a spontaneous process and favorable at high temperatures.     

Virgatolides A-C, benzannulated spiroketals from the plant endophytic fungus Pestalotiopsis virgatula

Virgatolides A-C (1-3), unique metabolites with a 3',4',5',6'-tetrahydrospiro[chroman-2,2'-pyran] core, were isolated from cultures of the plant endophytic fungus Pestalotiopsis virgatula. Compounds 1-3 possess two previously undescribed skeletons originating from a benzannulated 6,6-spiroketal and one (2 and 3) and two (1) γ-lactone units, respectively. The structure of 1 was secured by X-ray crystallography.     

Nickel-catalyzed carboannulation reaction of o-bromobenzyl zinc bromide with unsaturated compounds

A number of indenes have been prepared in good yields by treating o-bromobenzyl zinc bromide 1 with various terminal and internal alkynes in the presence of a nickel catalyst. The nickel-catalyzed carboannulation reaction was successfully extended to the synthesis of indane derivatives by reaction of 1 with acrylates and styrene.     

Effect of polysaccharide nanocrystals on structure, properties, and drug release kinetics of alginate-based microspheres

Polysaccharide nanocrystals, such as rod-like cellulose nanocrystals and chitin whiskers and platelet-like starch nanocrystals, were incorporated into alginate-based nanocomposite microspheres with the aim of enhancing mechanical strength and regulating drug release behavior. The structures and properties of the sols and the resultant nanocomposite microspheres were characterized by rheological testing, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The presence of polysaccharide nanocrystals increased the stability of the crosslinked network structure, and the nanocomposite microspheres consequently exhibited prominent sustained release profiles, as demonstrated by inhibited diffusion of theophylline. Furthermore, based on the drug release results, the release kinetics and transport mechanisms were analyzed and discussed.     

Nitrogen heterocycles via palladium-catalyzed carbocyclization. Formal synthesis of (+)-alpha-allokainic acid

[reaction: see text] The Pd-catalyzed carbocyclization of ketoamides was investigated and found to be highly dependent on the phosphine ligand as well as the presence of coordinating counterions. Nitrogen heterocycles were formed without erosion of the stereochemical integrity. The utility of the lactam products was demonstrated by the formal synthesis of (+)-alpha-allokainic acid.     

Spline adaptive filters based on real-time over-sampling strategy for nonlinear system identification

Nonlinear Dynamics - In this paper, a new spline adaptive filter (SAF) used for identifying the nonlinear systems is presented, in which a real-time over-sampling (RTOS) strategy is proposed in...     

The effect of melt drawing ratio on the crystal structural change and performance of polyketone extrusion cast film

In this paper, the polyketone (POK) extrusion cast film is manufactured by melt stretching method, and the evolution process of the crystal morphology and mechanical properties with the increase of melt drawing ratio (MDR) are followed. The results show that the melt stretching process produces many micro shish-kebab crystals in the POK. The length of the shish crystal and the thickness of the kebab crystal hardly increase with MDR, but the lateral length of the kebab crystal shows linear growth when MDR exceeds 40. The crystalline morphology of POK is mainly affected by melt relaxation. The molecular chain has sufficient relaxation during cooling at a low MDR (20–40). At this time, micro shish-kebab crystals are mainly randomly arranged. When MDR exceeds 40, the rapid melt stretching shortens the relaxation time of the tie chain between the neighborhood shish crystal, and the atomic force microscopy image shows a typical shish-kebab structure. This experimental result indicates that the formation of the oriented lamella structure may be related to the relaxation of the molecular chains between the micro-shish. When the length of the shish axis and the thickness of the kebab lamellae are similar, it is difficult to distinguish the two.