Phase-matching properties of KNbO3 in the mid-infrared

KNbO(3) has been found to be phase matchable for type 1 second-harmonic generation up to 2.4 mum at 22 degrees C. The improved Sellmeier equations that correctly reproduce the nonlinear experiments thus far reported in the literature and our new experimental results for harmonic generation of CO(2) laser harmonics between 3.5303 and 5.2955 mum are presented.     

One Method for Selection of Circuit Parameters of a Self-Commutated Rectifier

A method of selecting the circuit parameters of a self-commutated rectifier circuit which aims at improving the power factor is proposed.     

A Pulsewidth Controlled AC-to-DC Converter to Improve Power Factor and Waveform of AC Line Current

As a method for improving power factor and waveform of ac line current drawn by an ac-to-dc converter a new pulsewidth controlled converter is proposed, its commutation mechanism is described, and experimental results are given which show a good power factor, a good waveform of the line current, and a wide adjustable range of dc output voltage.     

Photoluminescence and scintillation properties of Eu2O3–BaO–Nb2O5–TeO2 glass and glass ceramics

Journal of Materials Science: Materials in Electronics - 1Eu2O3–3BaO–20Nb2O5–76TeO2 glass and the corresponding glass-ceramics were synthesized with the aim to investigate the...     

FEM-aided identification of gauge factors of unidirectional CFRP through multi-point potential measurements

Carbon fiber reinforced plastic (CFRP) has electrical conductivity in both the parallel and transverse directions of the fiber. Because an electrical network may be changed with the applied strain, the electrical conductivity of the CFRP will also be changed for the piezoresistivity. Strain monitoring of CFRP can therefore be conducted, not by using an additional sensor, but by measuring the change in electrical resistance. There have been many studies on the gauge factors of unidirectional CFRPs, although significant mutual differences have been determined in the results reported. It is thought that the differences may be caused by the strong electrical anisotropy and inhomogeneity of the unidirectional CFRP. In this study, a new concept was introduced to precisely measure the gauge factors of a unidirectional CFRP. A finite element analysis was utilized to take into consideration a non-uniform electrical potential field in a unidirectional CFRP. The gauge factors were obtained as a result of minimizing the error sum of the squares of the electrical potentials between the experimental and analytical results. The gauge factor in the fiber direction was affected by this factor in the thickness direction depending on the specimen configuration. The results of the finite element analysis showed the possibility of a unidirectional CFRP showing both positive and negative gauge factors in the fiber direction.     

Mutation induction in human cells after low dose X ray exposure

Mutations induced after low dose ionising radiation exposure have been intensively analysed not only for radiation risk estimation but also for basic understanding of cellular responses. Human lymphoblastoid TK6-20C cells were irradiated with 100 mGy of X rays and mutation at the heterozygous thymidine kinase (TK) locus was selected by trifluorothymidine (TFT) resistance. Although the mutation frequency at the TK locus increased from 5.6 x 10(-6) to 7.4 x 10(-6), this increase was not statistically significant. However, molecular analysis of TK mutants exhibiting loss of heterozygocity (LOH) demonstrated a clear effect of such low dose IR exposure. Exposure to 100 mGy X ray increased the fraction of hemizygous-LOH from 10% to 42%. In previous experiments, a similar tendency in the increase of hemizygous-LOH was also observed in TK6 cells after exposure to a 2 Gy dose of X rays. This type of LOH can be considered as a result of end-joining repair of DNA double strand breaks.     

Behavioral responses of the ciliated protozoan Paramecium caudatum to 2,4-dichlorophenoxyacetic acid and its analogues

We found that the ciliated protozoan Paramecium caudatum ON-1 was repelled by 2,4-dichlorophenoxyacetic acid (2,4-D). P. caudatum was also repelled by phenoxyacetic acid, while it was attracted to benzoic acid. No significant behavioral response was detected with 2,4-dichlorophenol (2,4-DP) and phenol. These results suggested that the substitution of-OH of phenol with -OCH2COOH, but not the chlorination of phenol, was important for eliciting the avoiding response to 2,4-D in P. caudatum. Electrophysiological analysis revealed that 2,4-D and phenoxyacetic acid were able to trigger the action potential in P. caudatum, whereas 2,4-DP and phenol failed to elicit electrical responses in this organism. Well test assays suggested that the avoiding reactions allowed P. caudatum to escape from the harm caused by this herbicide.     

Hidden Markov model-based prediction of antigenic peptides that interact with MHC class II molecules

Elucidating the interaction between major histocompatibility complex (MHC) molecules and antigenic peptides is fundamental to better understanding of the processes involved in immune responses and for the development of innovative immunotherapies. In the present study, hidden Markov models (HMM) were combined with the successive state splitting (SSS) algorithm for optimization of the HMM structure, to predict peptide binders to the human MHC class II molecule HLA-DRB1*0101. The predictive performance of our model (S-HMM) was compared with fully connected HMM and artificial neural network (ANN) methods using the relative operating characteristic (ROC) analysis. The S-HMM predictions had values of ROC > or = 0.85 which was at least as good, or better than the comparison methods. In addition, S-HMM is trained on positive data only and does not require exhaustive data preprocessing, such as peptide alignment. Our results demonstrated that S-HMM combines the high accuracy of predictions with the simplicity of implementation and is therefore useful for analyzing MHC class II binding peptides. In particular the S-HMM may be trained using only positive data and, the preprocessing of training data, such as peptide alignment and the selection of binding cores, is not required in this method.     

A protein-encapsulation technique by the sol-gel method for the preparation of monolithic columns for capillary electrochromatography

A novel protein-encapsulation technique using sol-gels was developed for the preparation of monolithic capillary columns for capillary electrochromatography. Two chiral compounds, bovine serum albumin (BSA) and ovomucoid (OVM) from chicken egg white, were encapsulated in tetramethoxysilane-based hydrogel and their chiral selectivity was evaluated for the separation of some selected enantiomers (tryptophan, benzoin, eperisone, chlorpheniramine). The protein encapsulation was carried out within a capillary in a single step under mild conditions. The resultant monolithic columns showed adequate chromatographic performance, including mechanical strength, penetration of pressurized flow, and chiral separation. Two different proteins, BSA and OVM, were successfully encapsulated into the gel matrixes by changing the alkoxysilane compositions of the gel. Run-to-run repeatability was quite satisfactory. The consecutive analysis of the neutral compound, benzoin, by the OVM-encapsulated column showed good repeatability in the retention time (RSD = 1.23% for the first peak, N = 10). Under optimized conditions, the theoretical plate number for the first peak of benzoin reached 72,000 plates/m.