New ent-Verticillane Diterpenoids from the Japanese Liverwort Jackiella javanica

Three new ent-verticillane diterpenoids have been isolated from the Japanese liverwort Jackiella javanica, together with known sesqui- and diterpenoids. Their absolute configurations were established by X-ray crystallographic analysis and circular dichroism spectroscopy.     

Thermal recovery of iodopsin from photobleaching intermediates

The chloride effect on the photobleaching process of iodopsin, a chicken red-sensitive cone visual pigment, was studied in detail by time-resolved low-temperature spectroscopy at -40 degrees C to -10 degrees C. Decay-associated difference spectra obtained by kinetic analysis using the singular value decomposition method were composed of spectra of BL-iodopsin, lumiiodopsin, metaiodopsin I, metaiodopsin II and metaiodopsin III, essentially identical to those at room temperature. In each conversion step however, iodopsin was partially regenerated, which is not observed in the bleaching process for other visual pigments or iodopsin at room temperature. Moreover, iodopsin was slowly regenerated from the bleached species. The reverse reactions were completely suppressed by substitution of lyotropic NO(3)(-) for Cl(-), suggesting that Cl(-) binding to iodopsin interferes with light-induced cis-trans isomerization of the chromophore. It is likely that the water molecule hydrating Cl(-) forms the additional hydrogen bond(s), by which the protein conformational change necessary to release this steric hindrance becomes enthalpic. As progress of the bleaching process is a consequence of protein conformational change, it is suppressed at low temperatures, resulting in thermal back-isomerization.     

A simple and rapid determination of valproic acid in human plasma using a non-porous silica column and liquid chromatography with tandem mass spectrometric detection

A liquid chromatographic tandem mass spectrometric (LC-MS/MS) assay was developed and validated to determine valproic acid in human plasma. The method involved a solid-phase extraction of valproic acid and betamethasone valerate, an internal standard, from plasma and detection using an LC-MS/MS system with electrospray ionization source in negative ion mode. Separation was achieved within 3 min on a non-porous silica column with mobile phase containing ammonium acetate and methanol. Multiple reaction monitoring was utilized for detection monitoring at 142.89-142.89 for valproic acid and 457.21-457.21 for the internal standard. The calibration curve for valproic acid was linear over the range of 0.5-150 microg/mL. The limit of detection was 0.17 microg/mL and the lower limit of quantification was 0.5 microg/mL, when 0.2 mL plasma was used for extraction. The percentage coefficient of validation for accuracy and precision (inter- and intra-day) for this method was less than 9.5% with recovery ranging from 82.3 to 86.9% for valproic acid.     

Dry tin dioxide hollow microshells and extreme ultraviolet radiation induced by CO2 laser illumination

Low-density tin dioxide (SnO2) is required for radiating monochromatic extreme ultraviolet (EUV) light with low debris and high conversion efficiency from a laser. In this paper, tin dioxide nanoparticle hollow microcapsules were successfully fabricated by a layer-by-layer template technique. The obtained capsules have a rougher surface (30 nm in rms) compared to the freshly prepared polyelectrolyte capsules. Based on the X-ray diffraction (XRD) results, the tin dioxide nanoparticles well maintained their size after they were assembled on the capsules' surfaces. In order to remove the polymer template, a heat treatment was introduced, and after the heat treatment the capsule sizes shrank about 71% (the average size was from 4.9 to 3.5 mum), and the obtained capsules maintained their round shape after water evaporation. The narrowest bandwidth at the 13.5 nm emission in the EUV region was observed when the capsules were irradiated by a CO2 laser with an intensity of 2.9 x 10(10) W/cm (2).     

A rational reciprocity law over function fields

In the classical case, reciprocity laws for power residue symbols are called rational, which means that the power residue symbols only assume the values \({\pm 1}\) and have entries in \({\mathbb{Z}}\). We establish a rational reciprocity law over function fields.     

Stimuli-responsive polymeric materials functioning via host–guest interactions

Molecular recognition is essential for realizing functional supramolecular materials. Non-covalent host–guest interactions are an effective tool to introduce switching and functional properties into materials. This review focuses on the achievement of selective molecular adhesion, self-healing, toughness, and actuation properties. These functions have been achieved by reversible bond formation with cyclodextrins (CDs). Self-healing materials with host–guest interactions involving CDs have been used to achieve redox-responsive healing properties and healing efficiency. Furthermore, the materials, which undergo self-healing by chemical and physical mechanisms, exhibit rapid and efficient self-healing properties under semi-dry conditions. To prepare a supramolecular actuator using host–guest complexes, two approaches have been introduced. The first is the functionalization of a supramolecular gel actuator by changing the cross-linking density, and the second is the functionalization of a topological gel actuator by changing distances between the cross-linking points. Both actuators exhibit contractive bending behavior. This review summarizes advancements within the past 10 years in supramolecular materials that function via the chemical mechanism of host–guest interactions and the physical mechanism of the sliding motion of ring molecules.     

Highly Flexible,Tough, and Self‐Healing Supramolecular Polymeric Materials Using Host–Guest Interaction

Flexible, tough, and self‐healable polymeric materials are promising to be a solution to the energy problem by substituting for conventional heavy materials. A fusion of supramolecular chemistry and polymer chemistry is a powerful method to create such intelligent materials. Here, a supramolecular polymeric material using multipoint molecular recognition between cyclodextrin (CD) and hydrophobic guest molecules at polymer side chain is reported. A transparent, flexible, and tough hydrogel (host–guest gel) is formed by a simple preparation procedure. The host–guest gel shows self‐healing property in both wet state and dry state due to reversible nature of host–guest interaction. The practical utility of the host–guest gel as a scratch curable coating is demonstrated.

     

Self‐Healing,Expansion–Contraction,and Shape‐Memory Properties of a Preorganized Supramolecular Hydrogel through Host–Guest Interactions

Supramolecular materials cross‐linked between polymer chains by noncovalent bonds have the potential to provide dynamic functions that are not produced by covalently cross‐linked polymeric materials. We focused on the formation of supramolecular polymeric materials through host–guest interactions: a powerful method for the creation of nonconventional materials. We employed two different kinds of host–guest inclusion complexes of β‐cyclodextrin (βCD) with adamantane (Ad) and ferrocene (Fc) to bind polymers together to form a supramolecular hydrogel (βCD‐Ad‐Fc gel). The βCD‐Ad‐Fc gel showed self‐healing ability when damaged and responded to redox stimuli by expansion or contraction. Moreover, the βCD‐Ad‐Fc gel showed a redox‐responsive shape‐morphing effect. We thus succeeded in deriving three functions from the introduction of two kinds of functional units into a supramolecular material.     

Error analysis for the computation of zeros of regular Coulomb wave function and its first derivative

In 1975 one of the coauthors, Ikebe, showed that the problem of computing the zeros of the regular Coulomb wave functions and their derivatives may be reformulated as the eigenvalue problem for infinite matrices. Approximation by truncation is justified but no error estimates are given there.

The class of eigenvalue problems studied there turns out to be subsumed in a more general problem studied by Ikebe et al. in 1993, where an extremely accurate asymptotic error estimate is shown.

In this paper, we apply this error formula to the former case to obtain error formulas in a closed, explicit form.

     

Detection of Label Area by Comb-Shaped Illumination

We have developed a non-contacting technique to detect small steps on a surface such as label edges on a letter by using a spatially modulated illumination. Steps can be detected correctly with this new technique even if there are printed patterns on the same surface. Thus the technique is effective for determining label areas that are often seen on pieces of direct mail.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15–17, at the International Conference Center, Tokyo, Waseda University, Japan.