Selection of meaningless steady noise for masking of speech

This paper focuses on masking speech with meaningless steady noise as a way of realizing a comfortable sound environment. As a basis for research, meaningless steady noise at minimum sound pressure levels for masking of male or female meaningful speech is considered, based on psychological experiments using a method of adjustment. From the results, band-limited pink noise can be selected as the most effective noise for masking of speech. In the case of speech with a lower sound pressure level, the sound pressure level of the meaningless steady noise needs to be a little higher.     

Molecule-Responsive Fluorescent Sensors of α-Helix Peptides Bearing α-Cyclodextrin, Pyrene and Nitrobenzene Units in Their Side Chains

-Helix peptides bearing one unit of -cyclodextrin (-CD), one unit of pyrene and one unit of nitrobenzene (NB) in their side chains have been designed and synthesized as novel molecule-responsive devices.In both the CD-peptides, -PR17 and -PL17, the NB unit is separated from the CD unit by two turns of the helix. Two reference peptides (PL17, and -P17,) have also been synthesized. The circular dichroism studies in the peptide absorption region (200–250 nm)of -PR17 and -PL17 suggestthat the CD-peptides form stable-helixstructures (83–77%), which was destabilized by accommodating guest molecules (e.g., n-pentanol) into the CD cavity. It suggests that formation of intramolecular host–guest(CD–NB) complex stabilized thehelical structure and exogenous guest molecule excluded the appending NB moiety from inside to outside of the CD cavity, thereby causing destabilization of the helical structure and increasing the random coil content. The ICD spectra of the peptides in the pyrene and nitrobenzene absorption region (250–40 nm) suggest that NB forms inclusion complex with CD. The fluorescence studies revealed that the fluorescence of the pyrene unit is quenched by the NB unit in -PR17 and -PL17. The fluorescence intensity increases with increasing guest concentration for the CD-peptides.This guest-responsiveenhancement in the fluorescence intensity can be explained in terms of increased distance between the pyrene and NB moieties, which is caused by exclusion of the NB moiety from the CD cavity by guest accommodation. Using the guest-responsive fluorescence quenching properties of the CD-peptides, we have obtained binding constants for various short chain alkanols. -PL17 has higher binding affinity to the guest molecules than its isomer, -PR17, indicating that the location of functional groups on the peptide scaffold is important in molecule detection.     

Analysis of the release process of phenylpropanolamine hydrochloride from ethylcellulose matrix granules

The release properties of phenylpropanolamine hydrochloride (PPA) from ethylcellulose (EC, ethylcellulose 10 cps (EC#10) and/or 100 cps (EC#100)) matrix granules prepared by the extrusion granulation method were examined. The release process could be divided into two parts, and was well analyzed by applying square-root time law and cube root law equations, respectively. The validity of the treatments was confirmed by the fitness of the simulation curve with the measured curve. At the initial stage, PPA was released from the gel layer of swollen EC in the matrix granules. At the second stage, the drug existing below the gel layer dissolved, and was released through the gel layer. Also, the time and release ratio at the connection point of the simulation curves was examined to determine the validity of the analysis. Comparing the release properties of PPA from the two types of EC matrix granules, EC#100 showed more effective sustained release than EC#10. On the other hand, changes in the release property of the EC#10 matrix granule were relatively more clear than that of the EC#100 matrix granule. Thus, it was supposed that EC#10 is more available for controlled and sustained release formulations than EC#100.     

Release from or through a wax matrix system. V. Applicability of the square-root time law equation for release from a wax matrix tablet

To obtain basic and clear release properties, wax matrix tablets were prepared from a physical mixture of drug and wax powder at a fixed mixing ratio. Properties of release from the single flat-faced surface, curved side surface, and/or whole surface of the wax matrix tablet were examined. Then tortuosity and the applicability of Higuchi's square-root time law equation were examined. The Higuchi equation well analyzed the release processes of different release manners. However, the region fitted to the Higuchi equation differed with the release manner. Tortuosity obtained with release from the single flat-faced surface and curved side surface was comparable with that obtained with the release from a reservoir device tablet, whereas tortuosity obtained with release from the whole surface was larger. As the wax matrix tablets were prepared at a fixed mixing ratio, their internal structures should be similar. Therefore changes in the matrix volume or volume fraction with release were examined, and an extra volume where dissolved drug stray becomes large with release time in the case of release from the whole surface. These factors should be taken into account for evaluation of applicability and release properties. Furthermore, the entire release process should be analyzed using a combination of the square-root time law and other suitable equations in accordance with release manner or condition.     

Release from or through a wax matrix system. IV. Generalized expression of the release process for a reservoir device tablet

Generalization of the release process through the wax matrix layer was examined by use of a reservoir device tablet. The wax matrix layer of the reservoir device tablet was prepared from a physical mixture of lactose and hydrogenated castor oil to simplify the release properties. Release through the wax matrix layer showed zero-order kinetics in a steady state after a given lag time, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time obtained by applying the square root law equation was well connected with the amount of the matrix layer and mixed weight ratio of components in this layer. The second stage was the zero-order release process of drug in the reservoir through the wax matrix layer, because the effective surface area was fixed. The release rate constants were connected with thickness of the matrix layer and permeability coefficient, and the permeability coefficients were connected with the diffusion coefficient of drug and porosity. Hence the release rate constant could be connected with the amount of matrix layer and the mixed weight ratio of components in the matrix layer. It was therefore suggested that the release process could be generalized using the amount of matrix layer and the mixed weight ratio of components in the matrix layer.     

Release from or through a wax matrix system. II. Basic properties of release from or through the wax matrix layer

In order to examine basic properties of release from and through wax matrix layer, reservoir device matrix tablet was prepared from a physical mixture of hydrogenated caster oil and drug that was the same one in the reservoir. Release process could be divided into two stages. The first stage was the formation process of water channel by dissolving the drug in the wax matrix layer, and dissolved drug was released from the matrix layer following the square-root-of-time law equation. Hence, the drug penetration coefficient and tortuosity in the matrix layer were estimated. The second stage was the zero order release process of drug in the reservoir through the wax matrix layer. The release rate constant was calculated from the slope of line. Hence, the drug permeability coefficient and tortuosity were estimated. Fundamentally, tortuosity can not be expressed by some meaningful factors, and is obtained as an experimental result. By preparing wax matrix system from a physical mixture other than melted granule method, it was suggested that the matrix structure was uniform three-dimensionally. As a result, tortuosity could be expressed by a function of porosity, because unrecognized factors such as the surface coverage and thickness of melted wax on the soluble component should not be involved.     

Thallium-201 chloride dynamic analysis using thallium-201 chloride and sodium iodide-131 thyroid subtraction scintigraphy

The mechanism of 201Tl chloride accumulation is unclear in thyroid gland and thyroid tumor. This report examines 108 patients that received thyroid scintigraphy examinations with both 201Tl chloride and sodium 131I. The patients were diagnosed clinically and histologically whenever possible. The ROI were obtained by subtraction imaging with both isotopes and by subtraction positive and negative areas of imaging. Dynamic curves were obtained for 201Tl chloride per square unit of each ROI. The dynamic curve in the radioiodide-accumulated area was examined. The data indicate that the clearance rate of 201Tl chloride (T15) was correlated with the sodium 131I uptake rate at 24 h (r = 0.70).     

Well‐Defined Iron Complexes as Efficient Catalysts for “Green” Atom‐Transfer Radical Polymerization of Styrene,Methyl Methacrylate,and Butyl Acrylate with Low Catalyst Loadings and Catalyst Recycling

Environmentally friendly iron(II) catalysts for atom‐transfer radical polymerization (ATRP) were synthesized by careful selection of the nitrogen substituents of N,N,N‐trialkylated‐1,4,9‐triazacyclononane (R₃TACN) ligands. Two types of structures were confirmed by crystallography: “[(R₃TACN)FeX₂]” complexes with relatively small R groups have ionic and dinuclear structures including a [(R₃TACN)Fe(μ‐X)₃Fe(R₃TACN)]⁺ moiety, whereas those with more bulky R groups are neutral and mononuclear. The twelve [(R₃TACN)FeX₂]_n complexes that were synthesized were subjected to bulk ATRP of styrene, methyl methacrylate (MMA), and butyl acrylate (BA). Among the iron complexes examined, [{(cyclopentyl)₃TACN}FeBr₂] ( 4 b ) was the best catalyst for the well‐controlled ATRP of all three monomers. This species allowed easy catalyst separation and recycling, a lowering of the catalyst concentration needed for the reaction, and the absence of additional reducing reagents. The lowest catalyst loading was accomplished in the ATRP of MMA with 4 b (59 ppm of Fe based on the charged monomer). Catalyst recycling in ATRP with low catalyst loadings was also successful. The ATRP of styrene with 4 b (117 ppm Fe atom) was followed by precipitation from methanol to give polystyrene that contained residual iron below the calculated detection limit (0.28 ppm). Mechanisms that involve equilibria between the multinuclear and mononuclear species were also examined.     

Fabrication of nanofibers with uniform morphology by self-assembly of designed peptides

Fabrication of controlled peptide nanofibers with homogeneous morphology has been demonstrated. Amphiphilic beta-sheet peptides were designed as sequences of Pro-Lys-X(1)-Lys-X(2)-X(2)-Glu-X(1)-Glu-Pro. X(1) and X(2) were hydrophobic residues selected from Phe, Ile, Val, or Tyr. The peptide FI (X(1)=Phe; X(2)=Ile) self-assemble into straight fibers with 80-120 nm widths and clear edges, as examined by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The fiber formation is performed in a hierarchical manner: beta-sheet peptides form a protofibril, the protofibrils assemble side-by-side to form a ribbon, and the ribbons then coil in a left-handed fashion to make up a straight fiber. These type of fibers are formed from peptides possessing hydrophobic aromatic Phe residue(s). Furthermore, a peptide with Ala residues at both N and C termini does not form fibers (100 nm scale) with clear edges; this causes random aggregation of small pieces of fibers instead. Thus, the combination of unique amphiphilic sequences and terminal Pro residues determine the fiber morphology.