A Simple Method for the Determination of Adsorption Kinetic Parameters Using Recycle Fixed-Bed Adsorber

This study focuses on the development of a novel analysis technique for determining the intraparticle diffusivity \((D_{\mathrm{S}})\) and fluid film mass transfer coefficient \((k_\mathrm{F})\) from a concentration history curve of a recycle fixed-bed reactor without using the linear driving force approximation and empirical equations for the estimation of \(k_\mathrm{F}\). The recycle fixed-bed method requires lesser amounts of working fluid for experiment purposes, which is an advantage over the usual fixed-bed method. Based on the characterization results of the concentration history curves, simulated by rigorous numerical calculations, a novel analysis technique was established. The \(D_{\mathrm{S}}\) value can be determined from the experimentally obtained time at which the concentration of the curve is minimal \((t_{C\mathrm{min}})\). The \(k_\mathrm{F}\) value can be determined from the \(D_{\mathrm{S}}\) value and Biot number (Bi), which can be estimated from the experimental ratio of the maximum concentration to the minimum concentration \((c_{\max }/c_{\min })\). The \(D_{\mathrm{S}}\) and \(k_\mathrm{F}\) values of phenol adsorption on an activated carbon material were determined experimentally using the proposed analysis method. This method enables the determination of reliable adsorption kinetic parameters through a simple and economical experiment. However, appropriate experimental data must be acquired under regulated experimental conditions, especially in the case of fluctuation of the concentration history curve.     

Living Ring‐Opening Metathesis Polymerization of Norbornenes Containing Acetyl‐Protected Carbohydrates Using Well‐Defined Molybdenum and Ruthenium Initiators

Summary: Homopolymers and diblock copolymers that contain maltose or glucose residues have been prepared by ring‐opening metathesis polymerization of norbornene derivatives using a molybdenum–alkylidene initiator, Mo(CHCMe₂Ph)(N‐2,6‐iPr₂C₆H₃)(OtBu)₂ ( A ). These polymerizations took place not only in a living fashion ( = < 1.2) but also with almost quantitative initiation. Two types of ruthenium initiators, (Cy₃P)₂RuCl₂(CHPh) ( B ) and (IMesH₂)(Cy₃P)RuCl₂(CHPh) ( C ), have also been used to compare initiator performance under the same conditions.

Structures for the polymers studied here.     

Experimental Tests of Parity Violation at Helical Polysilylene Level

The author would like to announce the following corrections: On page 671, right column, line 2, the sentence should read “For a certain polysilylene, ΔE_ST is reported to be 0.32 eV”. The insets in Figure 3d should read “S‐1” and “R‐1” instead of “S‐1L” and “R‐1L” . In the reference section, [34] reads correctly “Y. Ishimaru, S. Sumida, T. Iida, Chem. Commun. 1997 , 2187‐‐2188”.     

Creation of Circularly Polarized Luminescence from an Achiral Polyfluorene Derivative through Complexation with Helix‐Forming Polysaccharides: Importance of the meta‐Linkage Chain for Helix Formation

A circularly polarized luminescence (CPL) material has been created by polymer–polymer complexation between a helix‐forming polysaccharide, schizophyllan (SPG), and a meta‐phenylene‐linked polyfluorene derivative (mPFS). Computational modeling revealed that mPFS can adopt a helical structure although a conventional polyfluorene derivative with a para‐phenylene linkage tends to enjoy a rigid rodlike conformation. Our detailed experimental examination showed that mPFS forms a chiral nanowire complex through cohelix formation with SPG. We have found, as expected, that this cohelical complex emits highly efficient CPL even in an aqueous solution. The appearance of the high CPL property is due to 1) a high quantum yield of the fluorene unit and 2) immobilization of the helically twisted conformation of mPFS in an isolated manner through cohelix formation with SPG. One can propose, therefore, that the SPG/mPFS complex acts as a new high‐performance CPL material with a solvent‐dispersible nanowire structure.     

Optically Active Conjugated Polymer from Solvent Chirality Transfer Polymerization in Monoterpenes

Disubstituted acetylene monomers [1,2‐diphenylacetylenes (DPAs: DPA‐pC1, DPA‐mC1, DPA‐pC8); 1‐phenyl‐2‐hexylacetylene (PHA‐pC1)] are tested for asymmetric polymerization in chiral monoterpenes used as solvents and compared with the corresponding monosubstituted acetylene monomer [1‐phenylacetylene (PA‐pC1)]. DPA‐pC1 containing a trimethylsilyl group in the para‐position of the phenyl ring produces an optically active polymer with a large Cotton effect, despite the absence of a stereogenic center. The polymer sample obtained by polymerization in 87% ee (–)‐α‐pinene shows the strongest CD signal (g_CD value at 385 nm: ∼3.2 × 10⁻³). The Cotton bands of the polymers obtained in (–)‐ and (+)‐α‐pinenes show the opposite sign in the CD signals. Theoretical calculations show that only the cis‐cisoid model adopts a helical conformation. A time‐correlated single photon counting experiment shows that the emission of the chiral polymer originates from a virtually single excited species with a 98% component fraction. This polymer solution does not show any significant decrease in g_CD value over a wide temperature range of 20 to 80 °C. No noticeable decrease in the g_CD value is detected when the polymer solution is kept at relatively low temperatures for a prolonged period (35 d). In contrast, the other polymers show no CD signal.

     

Influence of desorption and sorption of water on the purity of perfluorooctanoic acid

The composition of impurities in perfluorooctanoic acid (PFOA) was measured and determined to be notably different between lots. Since the purity of PFOA varied, the accuracy of prepared calibration solution concentrations was reduced. In this study, factors influencing the purity were investigated using a Karl Fischer titrator and a LC/MS to support the development of reference materials. The results showed variances of water and isomer/homologue contents under different ambient conditions during sample handling. Moreover, these variances, especially for water, greatly affected the purity of PFOA (0.95–0.99 kg kg^?1). Therefore, PFOA of reliable purity should be used for the preparation of calibration solutions.     

Water content variation of p-n-heptylphenol reference material

Water content variation of candidate p-n-heptylphenol (HP) reference material (ampoule form) for preparation of a primary standard solution based on the Japan Calibration Service System, a national standards dissemination system, under the Measurement Law of Japan, was examined by a Karl-Fischer water content meter. As prepared samples, liquid-phase HP and upper, middle, and lower layers of solid-phase HP were measured since characteristic phase transition occurs near room temperature (melting point: 28.98 °C). As a result of water content in liquid- and solid-phase HP, water content variation among three layers of solid-phase is found in within ampoules, though water content variation of liquid-phase is not found. Between-ampoule variation of water content is also found using total ampoules of liquid-phase HP used to eliminate within-ampoule variation. Moreover, water content variation is secondarily confirmed by the results of the amount-of-substance fraction of HP based on a differential scanning calorimeter. From these results in this study, it is concluded that within- and between-ampoule variations of water content may depend on phase transition and water loss during ampouling of candidate reference material, respectively.     

Crystal Engineering Approach To Design Colorimetric Indicator Array To Discriminate Positional Isomers of Aromatic Organic Molecules

Discriminating by color : A 2D colorimetric indicator array has been designed by a crystal engineering approach (N???H? O hydrogen bonding and charge‐transfer complexation) involving solid‐state co‐grinding for the visual discrimination of positional isomers of dihydroxynaphthalene. Factors governing the close packing of π planes, and hence color of the complex, were determined by single‐crystal X‐ray analysis, allowing fine tuning by crystal engineering.

     

Optically active, lyotropic liquid crystalline poly(diphenylacetylene) derivative: hierarchical chiral ordering from isotropic solution to anisotropic solid films

The side chain chirality of a poly(diphenylacetylene) derivative was transferred and amplified spontaneously from solution to a bulk film due to lyotropic liquid crystallinity.     

Switching in molecular shapes: main chain length driven rod-circle transition of isolated helical polysilanes

Unique conformations such as rod, semicircle, and circle structures of isolated semi-flexible helical polysilanes were observed by atomic force microscopy (AFM); the chain topology was significantly related to the chain length (molecular weight) on the surfaces.