HPLC with fluorescence detection assay of perampanel,a novel AMPA receptor antagonist,in human plasma for clinical pharmacokinetic studies

Perampanel (Fycompa®), a novel α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor antagonist, is registered for the adjunctive treatment of patients (aged ≥12 years) with refractory partial‐onset seizures. To support therapeutic drug monitoring, a simple high‐performance liquid chromatography (HPLC) assay with fluorescence detection was developed to determine perampanel concentrations in human plasma and validated to support clinical trials. Human plasma samples (1.0 mL) were processed by liquid extraction using diethyl ether, followed by chromatographic separation on a YMC Pack Pro C₁₈ column (150 × 4.6 mm i.d., 5 µm) with isocratic elution of acetonitrile–water–acetic acid–sodium acetate (840:560:3:1.8, v/v/v/w) at a flow rate of 1.0 mL/min. Column eluent was monitored at excitation and emission wavelengths of 290 and 430 nm, respectively. The assay was linear (range 1.0–500 ng/mL) and this could be extended to 25 µg/mL by 50‐fold dilution integrity. No endogenous peaks were detected in the elution of analytes in drug‐free blank human plasma from six individuals and no interference was observed with co‐medications tested. Intra‐ and inter‐batch reproducibility studies demonstrated accuracy and precision within the acceptance criteria of bioanalytical guidelines. Validation data demonstrated that our assay is simple, selective, reproducible and suitable for therapeutic drug monitoring of perampanel. Copyright © 2015 John Wiley & Sons, Ltd.     

Constructing finitely presented monoids which have no finite complete presentation

Squier (1987) showed that if a monoid is defined by a finite complete rewriting system, then it satisfies the homological finiteness condition FP₃, and using this fact he gave monoids (groups) which have solvable word problems but cannot be presented by finite complete systems. In the present paper we show that a monoid cannot have a finite complete presentation if it contains certain special elements. This observation enables us to construct monoids without finite complete presentation in a direct and elementary way. We give a finitely presented monoid which has (1) a word problem solvable in linear time and (2) linear growth but (3) no finite complete presentation. We also give a finitely presented monoid which has (1) a word problem solvable in linear time, (2) finite derivation type in the sense of Squier and (3) the property FP_∞, but (4) no finite complete presentation.     

High-throughput characterization of local conductivity of Nd0.9Ca0.1Ba2Cu3O7−δ thin film by the low-temperature scanning microwave microscope

We developed a scanning microwave microscope (SμM) designed for high-throughput electric-property screening as well as for rapid construction of electronic phase diagrams at low temperatures. As a sensor probe, we used a high-Qλ/4 coaxial cavity resonator to which a thin needle with ball-tip end was attached. The sensor module was mounted on the low-temperature XYZ stage, which allowed us to map out the change of resonance frequency and quality factor due to the local tip-sample interaction at low temperatures. From the measurements of combinatorial thin films, such as Ti_1−xCo_xO_2−δ and Nd_0.9Ca_0.1Ba₂Cu₃O_7−δ (NCBCO), it was demonstrated that this SμM system has enough performance for the high-throughput characterization of sample conductance under variable temperature conditions.     

Rugged distal tips for CO2 laser medicine

Low-loss and rugged distal tips for CO₂ laser have been proposed and fabricated based on a commercially available stainless steel (St) pipe. A method of smoothening the inner surface of the St pipe with a rough inner surface is put forward. Fabrication parameters, transmission properties, and mechanical strength of the cyclic olefin polymer-coated silver hollow St distal tip are experimentally discussed.     

Photocarrier injection and the I-V characteristics of La0.8Sr0.2MnO3/SrTiO3:Nb heterojunctions

Oxide heterojunctions made of p-type La_0.8Sr_0.2MnO₃ (LSMO) and niobium-doped n-type SrTiO₃ (STO:Nb) have been fabricated by the pulsed laser deposition (PLD) technique and characterized under UV light irradiation by measuring the current-voltage, photovoltaic properties and the junction capacitance. It is shown that the heterojunctions work as an efficient UV photodiode, in which photogenerated holes in the STO:Nb substrate are injected to the LSMO film. The maximum surface hole density Q/e and external quantum efficiency γ are estimated to be 8.3×10¹² cm⁻² and 11% at room temperature, respectively. They are improved significantly in a p-i-n junction of LSMO/STO/STO:Nb, where Q/e and γ are 3.0×10¹³ cm⁻² and 27%, respectively.     

Preparation and condensation reactions of a new light-fluorous Mukaiyama reagent: reliable purification with fluorous solid phase extraction for esters and amides

A modified light-fluorous Mukaiyama reagent bearing a C₈F₁₇ tag was prepared and examined in ester and amide forming condensation reactions. Following the reactions, the desired product was effectively separated from the fluorous pyridone by-product using a simple fluorous solid phase extraction.     

A structural study of CN treated amorphous silicon

Recently, a remarkable technique to overcome the problem of light-induced degradation in amorphous silicon (a-Si) solar cells using a cyanide (CN) treatment has been developed. Structural and bonding characteristics of CN in a-Si has been studied using ab initio molecular dynamics simulations. It was found that CN incorporation results in more than just the termination of dangling bonds. The connectivity of the covalent random network increases because the CN changes from triply bonded, which is a common form in molecular CN, to the singly bonded form. This may be the mechanism by which CN incorporation produces significant reductions in light-induced degradation.     

Solutions of sturm-liouville boundary value problems for higher-order differential equations

The existence of solutions of a class of two-point boundary value problems for higher order differential equations is studied. Sufficient conditions for the existence of at least one solution are established. It is of interest that the nonlinearityf in the equation depends on all lower derivatives, and the growth conditions imposed onf are allowed to be super-linear (the degrees of phases variables are allowed to be greater than 1 if it is a polynomial). The results are different from known ones since we don’t apply the Green’s functions of the corresponding problem and the method to obtain a priori bound of solutions are different enough from known ones. Examples that can not be solved by known results are given to illustrate our theorems.     

Improved coating method for uniform polymer layer in infrared hollow fiber

An improved coating method was proposed in order to form a uniform polymer layer in the fabrication of cyclic olefin polymer-coated silver (COP/Ag) hollow fiber. A COP solution was flowed in a closed loop, in which the silver-coated tube was used as a part of the loop. Owing to the constant flowing speed of the COP solution and the airtight flowing environment, a COP layer was uniformly formed. The hollow fibers attain high performance and deliver multi-wavelength laser light from the infrared to the visible simultaneously. The method was successfully applied to the fabrication of practical hollow fibers with 2 m length for the near and mid-infrared lasers.     

Synthesis and properties of poly(amic acid)s and polyimides based on 2,2′,6,6′‐biphenyltetracarboxylic dianhydride

Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2′,6,6′‐biphenyltetracarboxylic dianhydride (2,2′,6,6′‐BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2′,6,6′‐BPDA and 4,4′‐(1,3‐phenylenedioxy)dianiline was converted to the polyimide by thermal treatment. The heating at 300 °C under nitrogen did not complete thermal imidization of PAAs having glass‐transition temperatures (T_g)s higher than 300 °C to the corresponding PIs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6385–6393, 2006