Input-output linearization of retarded non-linear systems by using an extension of Lie derivative

This paper considers the input-output linearization problem for retarded non-linear systems, which have time-delays in the state. By using an extension of the Lie derivative for functional differential equations, we derive a coordinates transformation and a static state feedback to obtain linear input-output behaviour for a class of retarded non-linear systems. The obtained coordinates transformation is allowed to contain not only the current value of the state variables but also the past values of ones. In addition, we show that the coordinates transformation is invertible in a neighbourhood of the origin and examine the stability condition of the closed loop system with the static state feedback. The effectiveness of the proposed technique is demonstrated through numerical simulations.     

Performance of nitrogen- and sulfur-containing carbon material derived from thiourea and formaldehyde as electrochemical capacitor

In order to investigate the performance of an electrochemical capacitor consisting of a nitrogen- and sulfur-containing carbon material, the carbon material derived from thiourea and urea was synthesized by a polymerization process of the urea resin. No solid appeared after the polymerization process. When the dried sample after the polymerization process was heated in flowing N2 gas, we obtained carbon material. However, there was no product when only thiourea was heated under the same conditions. The percentages of nitrogen and sulfur in all the samples synthesized from thiourea were roughly 5-20 wt.% and 3-8 wt.% even after washing with hot water, respectively. No specific peak derived from the redox reaction appeared in the CV graphs for the samples. The capacitance value of T-urea800W, which was synthesized by the heat treatment at 800 °C and then wash with hot water, was 138.8 F g⁻¹ at the current density of 50 mA g⁻¹ in a 1 M H₂SO₄ water solution whereas that value of a commercial activated carbon was 107.1 F g⁻¹ under the same conditions. It was presumed from the XPS measurements that the status of the nitrogen and sulfur in the materials are a pyridine-like nitrogen at the edge part of the graphitic structure, a quaternary nitrogen in the graphitic-layered structure, and S⁰, S⁴⁺, and S²⁻, respectively.     

Mismatch repair deficiency leads to a unique mode of colorectal tumorigenesis characterized by intratumoral heterogeneity

In order to determine the effects of mismatch repair (MMR) deficiencies in sporadic colorectal carcinomas, 45 such cancers were examined using a sensitive method called crypt isolation technique. Loss of heterozygosity (LOH) in the MSH2 or MLH1 gene was more frequently observed in replication error (RER) (+) carcinomas than in RER (-) carcinomas, which implied that loss of one normal allele could partly affect repair capacity. MSH2 gene defects at both alleles were observed in two carcinomas, which showed severe repair deficiencies. Interestingly, unlike the situation observed in the p53 gene, the MSH2 and MLH1 genes did not show complete LOH. Novel crypt isolation-based subpopulation (CISP) analysis demonstrated that at least two distinct carcinoma subpopulations existed in most carcinomas that showed incomplete LOH; one with and one without LOH. In one carcinoma that had germline mutation and somatic incomplete LOH of the MSH2 gene, the mutator phenotype was only observed in populations affected in both alleles. Thus, the MSH2 gene appears to possess the two hits mechanism of tumor suppressor genes. However, unlike the tumor suppressor genes, MMR gene defects lead to a unique mode of colorectal tumorigenesis characterized by intratumoral heterogeneity.     

Effect of plasma surface modification on electrical conduction in polyethylene

High-density polyethylene films 50 μm thick were exposed to the downstream plasma flow of RF glow discharges in argon, hydrogen, or oxygen. It was found that many transvinylene and unreacted radicals remain after the argon or hydrogen plasma treatment, and that carbonyl groups are formed in the oxygen plasma treatment. The conduction current was smaller in the hydrogen-plasma treated samples and the samples exposed to oxygen or ozone after hydrogen-plasma treatment than in the untreated samples. Thermal pulse current measurements indicate that the treated surface layer traps electrons or holes and reduces the field strength at the electrode surface, thus suppressing further injection of electrons or holes.     

Adhesion improvement of HIVIPP C targets on Au backings

Accurate measurement of the cross-section of the ¹²C(α, γ)¹⁶O reaction is very important in nuclear astrophysics. Enriched ¹²C targets prepared with the high energy vibrationl powder plating [HIVIPP] method for this purpose have been used successfully. Initially, however, the ¹²C deposits for studying this small cross-section partially peeled from their Au backings when irradiated with beam currents≥2 times the 7 μA pulsed α-beam used previously. This problem was solved when the amorphous ¹²C powders were converted to graphite by heat-treatment in a high-temperature furnace. We investigated powder heat treatments at temperatures of 2600-3500 °C to reveal, which conditions resulted in uniform and highly adhesive depositions on Au backings.     

Measurement method of Stokes parameters using a quarter-wave plate with phase difference errors

The Stokes parameters (S0, S1, S2, and S3) of monochromatic light can be measured using the adjustable azimuth settings of a quarter-wave plate and a polarizer. When measuring the Stokes parameters of light of an arbitrary wavelength, the measurement of S3 is affected by the phase difference error Δq(λi), due to the mismatch with respect to wavelength with the quarter-wave plate. In this method, Δq(λi), due to such a mismatch of incident light of arbitrary wavelength, can be overcome by a judicious choice of azimuth settings of the quarter-wave plate and the use of a polarizer; however, the use of a precision quarter-wave plate is necessary. The present paper proposes a measurement method of Stokes parameters of incident light of arbitrary wavelength using a quarter-wave plate with phase difference errors.     

Nonmechanical transverse scanning laser Doppler velocimeter using wavelength change

A transverse scanning laser Doppler velocimeter (LDV) that does not require any moving mechanism in its sensor probe is proposed, and the scanning function is demonstrated theoretically and experimentally. In the proposed scanning LDV, the measurement position is transversely scanned on the basis of a wavelength change induced by a tunable laser and a combination of a grating and a Dove prism. To demonstrate the scanning function in the transverse direction, an experiment was carried out using a setup of the sensor probe consisting of bulk optical components. The experimental results indicate that a transverse scanning function was successfully obtained. The scanning range in the vertical direction is estimated to be 11.3 mm over wavelengths of 1520 to 1570 nm.     

Microsatellite instability in the mitochondrial DNA of colorectal carcinomas: evidence for mismatch repair systems in mitochondrial genome

The role, if any, that mitochondrial (mt) DNA alterations play in the carcinogenic process remains unclear. To determine whether mtDNA instability occurs in cancers, nine microsatellite sequences in the mtDNA were examined in 45 sporadic colorectal carcinomas. Alteration in a polycytidine (C)n tract within a non-coding displacement-loop (D-loop) region was detected in 20 carcinomas (44%), three of which also exhibited frameshift mutations in a polyadenosine (A)8 or polycytidine (C)6 tract within NADH dehydrogenase (ND) genes. Interestingly, all three mutant genes were predicted to encode truncated ND proteins, which lacked a large portion of the C-terminus. These results suggested that certain repair systems, like the mismatch repair systems in the nuclear genome, are required for mtDNA maintenance and that defects in these systems can lead to target mitochondrial gene mutations in colorectal carcinomas.     

The burst-phase intermediate in the refolding of beta-lactoglobulin studied by stopped-flow circular dichroism and absorption spectroscopy

The kinetics of the guanidine hydrochloride-induced unfolding and refolding of bovine beta-lactoglobulin, a predominantly beta-sheet protein in the native state, have been studied by stopped-flow circular dichroism and absorption measurements at pH 3.2 and 4.5 degrees C. The refolding reaction was a complex process composed of different kinetic phases, while the unfolding was a single-phase reaction. Most notably, a burst-phase intermediate of refolding, which was formed during the dead time of stopped-flow measurements (approximately 18 ms), showed more intense ellipticity signals in the peptide region below 240 nm than the native state, yielding overshoot behavior in the refolding curves. We have investigated the spectral properties and structural stability of the burst-phase intermediate and also the structural properties in the unfolded state in 4.0 M guanidine hydrochloride of the protein and its disulfide-cleaved derivative. The main conclusions are: (1) the more intense ellipticity of the intermediate in the peptide region arises from formation of non-native alpha-helical structure in the intermediate, apparently suggesting that the folding of beta-lactoglobulin is not represented by a simple sequential mechanism. (2) The burst-phase intermediate has, however, a number of properties in common with the folding intermediates or with the molten globule states of other globular proteins whose folding reactions are known to be represented by the sequential model. These properties include: the presence of the secondary structure without the specific tertiary structure; formation of a hydrophobic core; broad unfolding transition of the intermediate; and rapidity of formation of the intermediate. The burst-phase intermediate of beta-lactoglobulin is thus classified as the same species as the molten globule state. (3) The circular dichroism spectra of beta-lactoglobulin and its disulfide-cleaved derivative in 4.0 M guanidine hydrochloride suggests the presence of the residual beta-structure in the unfolded state and the stabilization of the beta-structure by disulfide bonds. Thus; if this residual beta-structure is part of the native beta-structure and forms a folding initiation site, the folding reaction of beta-lactoglobulin may not necessarily be inconsistent with the sequential model. The non-native alpha-helices in the burst-phase intermediate may be formed in an immature part of the protein molecule because of the local alpha-helical propensity in this part.