Dissolution behaviour of iron silicate glass

A relationship between the water purifying effect and structure of 0.5xNa₂O·0.5xCaO·5Fe₂O₃·(95–x)SiO₂ glass (Na₂O/CaO = 1; NCFS glass) with ‘x’ of 20 and 50 were investigated by means of ⁵⁷Fe-Mössbauer spectroscopy, X-ray diffraction (XRD), induced coupled plasma optical emission spectroscopy (ICP-OES), as well as absorption spectroscopy, pH and oxidation-reduction potential (ORP) measurements. In the case NCFS glass with ‘x’ of 20, dissolved amounts of total Fe, Na^?+?, and Ca^2?+? were respectively estimated to be 13.6, 39.1 and 36.7 mg/l, after 10 day-leaching test. On the other hand, the dissolved amounts of total Fe, Na^?+? and Ca^2?+? were determined to be 34.3, 647.6 and 667.6 mg/l, respectively when ‘x’ was 50. The original pH value of 6.0 was increased to 10.0 and 11.6 after leaching test of NCFS glasses with ‘x’ of 20 and 50, respectively. At the same time, the ORP value was decreased from 30.0 to ?195.8 and ?284.7 mV in the glasses with ‘x’ of 20 and 50, respectively.     

Synthesis,Characterization, and Properties of Aligned Polyacetylene Films

Highly aligned polyacetylene films are synthesized by three different methods in which nematic liquid crystals are used as an ordered matrix solvent: Method 1, polymerization of acetylene is carried out in a quiescent nematic solution in which a Ti(OBu)₄-AlEt₃ Ziegler-Natta catalyst is dissolved homogeneously; Method 2, macroscopic alignment is attained by gravity flow of the nematic liquid crystal-catalyst system; and Method 3, the nematic liquid crystal-catalyst solution is aligned under a magnetic field. Characterization of these films is carried out through SEM observation and measurements of polarized visible and infrared absorption spectra. Results indicate that as-prepared films have highly aligned fibrils. Upon doping by I₂ and AsF₅, these films exhibit high electrical condactivity of the order of 10₄ S/cm.     

Formation of unimer nanoparticles by controlling the self-association of hydrophobically modified poly(amino acid)s

Amphiphilic block or graft copolymers have been demonstrated to form a variety of self-assembled nano/microstructures in selective solvents. In this study, the self-association behavior of biodegradable graft copolymers composed of poly(γ-glutamic acid) (γ-PGA) as the hydrophilic segment and L-phenylalanine (Phe) as the hydrophobic segment in aqueous solution was investigated. The association behavior and unimer nanoparticle formation of these γ-PGA-graft-Phe (γ-PGA-Phe) copolymers in aqueous solution were characterized with a focus on the effect of the Phe grafting degree on the intra- and interpolymer association of γ-PGA-Phe. The particle size and number of polymer aggregates (N(agg)) in one particle of the γ-PGA-Phe depended on the Phe grafting degree. The size of γ-PGA-Phe with 12, 27, 35, or 42% Phe grafting (γ-PGA-Phe-12, -27, -35, or -42) was about 8-14 nm and the N(agg) was about 1, supporting the presence of a unimolecular graft copolymer in PBS. The pyrene fluorescence data indicated that γ-PGA-Phe-35 and -42 have hydrophobic domains formed by the intrapolymer association of Phe attached to γ-PGA. These results suggest that the Phe grafting degree is critical to the association behavior of γ-PGA-Phe and that γ-PGA-Phe-35 and -42 could form unimer nanoparticles. Moreover, when γ-PGA-Phe-42 dissolved in DMSO was added to various concentrations of NaCl solution, the particle size and N(agg) could be easily controlled by changing the NaCl concentration during the formation of the particles. These results suggest that biodegradable γ-PGA-Phe is useful for the fabrication of very small nanoparticles. It is expected that γ-PGA-Phe nanoparticles, including unimer particles, will have great potential as multifunctional carriers for pharmaceutical and biomedical applications, such as drug and vaccine delivery systems.     

Polyampholyte Nanoparticles Prepared by Self‐Complexation of Cationized Poly(γ‐glutamic acid) for Protein Carriers

A novel amphoteric poly(amino acid) is synthesized by grafting a cationic amino acid (L ‐Arg) to γ‐PGA to prepare charged NPs. γ‐PGA‐Arg NPs can be prepared by the self‐complexation of a single polymer by intra‐/inter‐molecular electrostatic interactions when the polymer is dispersed in water. The size and surface charge of the NPs can be regulated by the grafting degree of Arg (41, 56, and 83%). The smallest NPs are obtained at 56% grafting degree of the γ‐PGA‐Arg copolymer. The 56 and 83% grafting degree NPs are stable for at least 1 week. Depending on their surface charge, these NPs can selectively adsorb anionically or cationically charged proteins.

     

Isotope-selective ionization utilizing molecular alignment and non-resonant multiphoton ionization

We demonstrate laser nitrogen isotope separation, which is based on field-free alignment and angular-dependent ionization of ¹⁴N₂ and ¹⁵N₂ isotopologues. A linearly polarized short laser pulse (???~?795?nm, ?????~?60?fs) creates rotational wave packets in the isotopologues, which periodically revive with different revival times as a result of different moments of inertia. Another linearly polarized short laser pulse (???~?795?nm, ?????~?60?fs) ionizes one of the isotopologues selectively as a result of their different angular distributions. In the present experiments, the ion yield ratio R [=I(¹⁵N₂ ⁺)/I(¹⁴N₂ ⁺)] can be changed in the range from 0.85 to 1.22, depending on the time delay between the two laser pulses.     

Certification of the methylmercury content in SRM 2977 Mussel Tissue (organic contaminants and trace elements) and SRM 1566b Oyster Tissue

The methylmercury content in two new marine bivalve mollusk tissue Standard Reference Materials (SRMs) has been certified using results of analyses from the National Institute of Standards and Technology (NIST) and two other laboratories. The certified concentrations of methylmercury were established based on the results from four and six different (independent) analytical methods, respectively, for SRM 1566b Oyster Tissue (13.2 ± 0.7 μg/kg) and SRM 2977 Mussel Tissue (organic contaminants and trace elements) (36.2 ± 1.7 μg/kg). The certified concentration of methylmercury in SRM 1566b is among the lowest in any certified reference material (CRM).     

Dynamic Switching of the Circularly Polarized Luminescence of Disubstituted Polyacetylene by Selective Transmission through a Thermotropic Chiral Nematic Liquid Crystal

The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) can be dynamically switched and amplified from left‐ to right‐handed CPL and vice versa through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell and tuning the selective reflection band of the N*‐LC phase to coincide with the CPL emission band, a CPL‐switchable cell was constructed. The phase change induced by the thermotropic N*‐LC cell by varying the temperature leads to a change in the selective transmission of CPL, which enables the dynamic switching and amplification of CPL. It is anticipated that CPL‐switchable devices might find applications in switchable low‐threshold lasers and optical memory devices.