bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural network estimation of RF electromagnetic pollution near TV broadcast transmitters
Authors: Çolak İlhami , Koçsalay İlhan
Published: February 2008

A set of measurements to investigate the Radio Frequency (RF) electromagnetic pollution in an area surrounding a TV broadcast transmitter has been given. The RF electromagnetic fields at different transmitter output power and time, in and out of the measurement points, were estimated and visualized by the developed visual software, which has 3D screening unit, based on Artificial Neural Network and Grid Data. The software enables users to estimate the RF electromagnetic field distributions in and out of the measurement points. Electric and magnetic field components of RF radiation value at any point/area can be compared with national/international standard limits easily using the software developed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1004–1010, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23301
Dispersion‐compensating photonic crystal fibers with special characteristics
Authors: Zhang Yejin , Yang Sigang , Xie Shizhong , Zheng Wanghua , Lianghui Chen
Published: February 2008

Based on the modified dual core structure, three kinds of special photonic crystal fibers are presented, which are extremely large negative dispersion, super‐broad band, and large area mode field dispersion‐compensating photonic crystal fibers (DCPCF). For extremely large negative dispersion DCPCF, the peak of negative dispersion reaches −5.9 × 104ps/(nm km). Super‐broad band DCPCF has broadband large negative dispersion and the dispersion value varies linearly from −380 ps/(nm km) to −420 ps/(nm km) in the C band. The designed large area mode field DCPCF has a peak dispersion of −1203 ps/(nm km) with the inner core mode area of 47 μm2and outer core mode area of 835 μm2. Furthermore, for the large area mode field DCPCF, the experimental result is also obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1073–1078, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23306
Z‐restored spin‐echo 13C 1D spectrum of straight baseline free of hump, dip and roll
Authors: Xia Youlin , Moran Sean , Nikonowicz Edward P. , Gao Xiaolian
Published: February 2008

A pulse sequence of z‐restored spin echo, − π− β− τ− π− τ−, employing a π pulse in the middle of the delay (2τ) to form a spin echo and the two π pulses together to restore the residual longitudinal magnetization back to + z direction, is described. 13C spectra of organic compounds provide a wealth of structural information; however, 13C 1D spectra acquired using reverse geometry probes can have significant baseline humps or rolls because of pulse ring‐down within the coil. The baseline distortions are especially apparent in spectra acquired using cryogenically enhanced probes. The baseline problem may be alleviated by extending the delay between the last pulse and the starting point of acquisition. However, uses of long delay times introduce large negative first‐order phase corrections which themselves produce baseline roll. The prescribed experiment can be used to completely remove the hump, roll or dip in the baseline of the 13C spectrum and at the same time obtain sensitivity similar to the experiment of a single β pulse. We believe that this experiment will be of general applications in acquiring high‐quality 13C NMR data with reverse geometry probes and spectral interpretation. Copyright © 2008 John Wiley & Sons, Ltd.
Melatonin receptor genes (mel‐1a, mel‐1b, mel‐1c) are differentially expressed in the avian germ line
Authors: Kawashima Takaharu , Stępińska Urszula , Kuwana Takashi , Olszańska BoŻenna
Published: February 2008

The presence of melatonin receptor transcripts (mel‐1a, mel‐1b and mel‐1c) was investigated in primordial germ cells (PGCs), immature and mature oocytes, and sperm of Japanese quail by reverse transcription ‐ polymerase chain reaction (RT‐PCR). The mel‐1a transcript was detected in as few as in a thousand PGCs. Significant differences in the expression of melatonin receptor genes were found in differentiating germ cells: in PGCs only the mel‐1a receptor was expressed, in blastoderms and immature oocytes all three transcripts (mel‐1a, mel‐1b, mel‐1c) were present, while in mature ovulated oocytes the predominant transcript was mel‐1c (with sporadic occurrence of mel‐1a and mel‐1b). In sperm, mel‐1a and mel‐1c were present but mel‐1b was absent. This indicates that the expression of melatonin receptor genes changes throughout the differentiation of PGCs into adult gametes: during oocyte differentiation two additional transcripts, mel‐1b and mel‐1c, are synthesized in addition to mel‐1a, but at oocyte maturation, mel‐1a and mel‐1b are degraded and only mel‐1c remains. During male line (spermatozoa) differentiation mel‐1c is transcribed in addition to mel‐1a, with mel‐1b being completely absent. Since melatonin and the activities of enzymes participating in melatonin synthesis are present in the avian yolk, it is reasonable to suggest a role for this molecule in early avian development and germ line differentiation. We propose that melatonin may act as a signaling molecule regulating some differentiation processes (e.g., cell proliferation, migration, etc.) before the formation of neural and hormonal systems. Mol. Reprod. Dev. 75: 1408–1417, 2008. © 2008 Wiley‐Liss, Inc.
Characterization of glycoside residues of porcine zona pellucida and ooplasm during follicular development and atresia
Authors: Pastor Luis M. , Lucas Xiomara , Pallares Jacinto , Bernal‐Mañas Carmen M. , A. Martinez Emilio , Roca Jordi , Vazquez Juan Maria , Morales Eva , Beltran Esther , Zuasti Adelina , Ferrer Concepcion
Published: February 2008

The glycoside residues (glycoconjugates, GC) of the zona pellucida (ZP) glycoproteins are important during the first phases of fecundation. Our aim in this work was to determine the lectin affinity pattern of porcine ZP in order to analyze the changes that take place during: (a) preantral folliculogenesis, (b) the follicular atresia process, and (c) antral growth. Several prepubertal and adult pig ovaries and different sized antral follicles were used. Conventional carbohydrate histochemical techniques and peroxidase and digoxigenin (DIG) lectins were used to reveal the acid groups and the glycosidic residues of the ZP. It was seen that the ZP forms in the preantral follicles throughout their growth period. In primordial and primary follicles, ZP in the process of formation showed neutral GC. SBA, RCA‐I, MAA, WGA lectins, and AAA after methylation‐saponification (MS) were positive in the ZP of primordial and primary follicles. The affinity for SBA, RCA‐I, MAA, and WGA increased in the multilaminar‐primary follicles and new affinities for UEA‐I and LFA were observed. After MS, AAA, SNA, PNA, and SBA reactivity was observed. The ZP of antral follicle oocytes of different sizes showed the same lectin pattern as multilaminar‐primary follicles. The oocyte ooplasm and the follicular fluid of large antral follicles showed less affinity for WGA and LFA lectins and less intensive staining with AB (pH 2.5). Atresia did not change the antral or preantral follicle oocyte ZP lectin pattern. In conclusion, the follicles showed substantial changes in their ZP glycosidic composition as they developed, especially, during the change from primary to multilaminar‐primary follicles. The ZP glycosidic composition showed no significant change during the growth of antral follicles and follicular atresia in our study. Mol. Reprod. Dev. 75: 1473–1483, 2008. © 2008 Wiley‐Liss, Inc.
Production of alpha 1,3‐Galactosyltransferase gene‐deficient pigs by somatic cell nuclear transfer: A novel selection method for gal alpha 1,3‐Gal antigen‐deficient cells
Authors: Fujimura Tatsuya , Takahagi Yoichi , Shigehisa Tamotsu , Nagashima Hiroshi , Miyagawa Shuji , Shirakura Ryota , Murakami Hiroshi
Published: February 2008

The objective of the present study was to isolate alpha 1,3‐galactosyltransferase (GalGT)‐gene double knockout (DKO) cells using a novel simple method of cell selection method. To obtain GalGT‐DKO cells, GalGT‐gene single knockout (SKO) fetal fibroblast cells were cultured for three to nine passages and GalGT‐null cells were separated using a biotin‐labeled IB4 lectin attached to streptavidin‐coated magnetic beads. After 15–17 days of additional cultivation, seven GalGT‐DKO cell colonies were obtained from a total of 2.5 × 107 GalGT‐SKO cells. A total of 926 somatic nuclear transferred embryos reconstructed with the DKO cells were transferred into eight recipient pigs, producing four farrowed, three liveborns, and six stillborns. Absence of GalGT gene in the cloned pigs was confirmed by PCR and Southern blotting. Flow cytometric analysis revealed that αGal antigens were not present in the cells of the cloned DKO pigs. Mol. Reprod. Dev. 75: 1372–1378, 2008. © 2008 Wiley‐Liss, Inc.
Characterization of a cis‐acting element involved in cell‐specific expression of the zebrafish brain aromatase gene
Authors: Le Page Yann , Menuet Arnaud , Kah Olivier , Pakdel Farzad
Published: February 2008

The cytochrome P450 Aromatase is the key enzyme catalyzing the conversion of androgens into estrogens. In zebrafish, the brain aromatase is encoded by cyp19b. Expression of cyp19b is restricted to radial glial cells bordering forebrain ventricles and is strongly stimulated by estrogens during development. At the promoter level, we have previously shown that an estrogen responsive element (ERE) is required for induction by estrogens. Here, we investigated the role of ERE flanking regions in the control of cell‐specific expression. First, we show that a 20 bp length motif, named G×RE (glial × responsive element), acts in synergy with the ERE to mediate the estrogenic induction specifically in glial cells. Second, we demonstrate that, in vitro, this sequence binds factors exclusively present in glial or neuro‐glial cells and is able to confer a glial specificity to an artificial estrogen‐dependent gene. Taken together, these results contribute to the understanding of the molecular mechanisms allowing cyp19b regulation by estrogens and allowed to identify a promoter sequence involved in the strong estrogen inducibility of cyp19b which is specific for glial cells. The exceptional aromatase activity measured in the brain of teleost fish could rely on such mechanisms. Mol. Reprod. Dev. 75: 1549–1557 © 2008 Wiley‐Liss, Inc.
Autoimmune‐mediated polyneuropathy triggered by borrelial infection?
Authors: Rupprecht Tobias A. , Elstner Matthias , Weil Sabine , Pfister Hans‐Walter
Published: February 2008

A patient with proven borrelial infection of the central nervous system (CNS) and progressive weakness of the arms was treated with antibiotics. Although the initially elevated CXCL13 concentration in the cerebrospinal fluid decreased, indicating effective treatment of the infection, weakness progressed. Investigation revealed multiple nerve conduction blocks and the presence of GM1 antibodies, suggesting a multifocal motor neuropathy; the patient improved on treatment with intravenous immunoglobulins. This report of an autoimmune‐mediated polyneuropathy in a patient with borrelial CNS infection indicates that such patients might respond to immunomodulatory therapy if antibiotic treatment is not effective. © 2007 Wiley Periodicals, Inc. Muscle Nerve, 2007
A clinical study of hirayama disease in Taiwan
Authors: Huang Ying‐Chih , Ro Long‐Sun , Chang Hong‐Shiu , Chen Chiung‐Mei , Wu Yih‐Ru , Lee Jian‐Der , Lyu Rong‐Kuo
Published: February 2008

The purpose of this study was to review the clinical manifestations of 40 patients who fulfilled the clinical criteria for Hirayama disease (juvenile muscular atrophy of distal upper extremities), identified in our neuromuscular clinic between February 1995 and December 2005. Of these 40 patients, 87.5% were male. The mean age at onset was 16.8 years, which was 4.5 years later than the peak age of the normal growth curve. Progressive muscle weakness and wasting were characteristic and occurred predominantly in the distal part of the right upper limb. Neurogenic symptoms ceased to progress within 5 years in most patients (92.5%). About one third of patients had participated frequently in heavy physical activity before onset of muscle symptoms. Reduced amplitude of the compound muscle action potential of the ulnar nerve was the most prominent finding in nerve conduction studies. Electromyography showed acute or chronic neurogenic changes, most frequently in muscles supplied by the C7–T1 segments. Magnetic resonance imaging showed anterior shifting of the posterior dura and engorged posterior venous plexus at the cervical level in 95% of patients. Our results support the belief that Hirayama disease is a self‐limited, focal lower motor neuron disease involving the lower cervical segments. Disproportionate growth between the vertebral column and the contents of the spinal canal may be the underlying cause, and strenuous physical activity may be a precipitating factor. Muscle Nerve, 2008
Tape functionality: Sonographic tape characteristics and outcome after TVT incontinence surgery
Authors: Kociszewski Jacek , Rautenberg Oliver , Perucchini Daniele , Eberhard Jakob , Geissbühler Verena , Hilgers Reinhard , Viereck Volker
Published: February 2008

Aim

To investigate tension‐free vaginal tape (TVT) position and shape using ultrasound (US) and correlate the findings to outcome.

Material and Methods

The results of TVT surgery were investigated in 72 women with urodynamic stress urinary incontinence. The main outcome parameters were US tape position in relation to the urethra and dynamic changes in TVT shape at rest and during straining.

Results

Sixty‐two patients (86%) were continent, 6 (8%) significantly improved, and the operation failed in four cases (6%). The median tape position was at 66% of the urethral length measured by US. The median tape‐urethra‐lumen distance was 3.8 mm at rest. Tape placement in the upper or lower quarter of the urethra was associated with a higher failure rate. Tapes positioned less than 3 mm from the urethra significantly increased postoperative complications (P < 0.0001). The tape was flat at rest and curved during straining in 44 (61%) patients; 98% (43/44) of these women were continent after surgery. An unchanged tape shape was associated with a poorer outcome (P = 0.00038). Patients with a flat tape at rest and during straining failed in 25% and patients with a permanent curved shape in 10%.

Conclusions

TVT position relative to the patient's urethra seems to play a role in treatment outcome. Outcome was best in patients with dynamic change in tape shape during straining and location of the tape at the junction between the lower and middle urethra and at least 3 mm from the urethral lumen. Neurourol. Urodynam. 27:485–490, 2008. © 2008 Wiley‐Liss, Inc.
A 19F‐NMR approach using reporter molecule pairs to assess β‐galactosidase in human xenograft tumors in vivo
Authors: Yu Jian‐Xin , Kodibagkar Vikram D. , Liu Li , Mason Ralph P.
Published: February 2008

Gene therapy has emerged as a promising strategy for treatment of various diseases. However, widespread implementation is hampered by difficulties in assessing the success of transfection in the target tissue and the longevity of gene expression. Thus, there is increasing interest in the development of non‐invasive in vivo reporter techniques to assay gene expression. We recently demonstrated the ability to detect β‐galactosidase activity in stably transfected human prostate tumor xenografts in mice in vivo using 19F NMR. We now extend the studies to human MCF7 breast cancer cells growing as xenografts in nude mice. Moreover, by using two spectrally resolved reporters (o‐fluoro‐p‐nitrophenyl‐β‐D‐galactopyranoside and an isomer), two tumors could be interrogated simultaneously revealing lacZ transgene activity in a stably transfected tumor versus no activity in a wild‐type tumor. Most significantly, hydrolytic activity observed by 19F NMR corresponded to differential activity in lacZ‐expressing tumors. Copyright © 2008 John Wiley & Sons, Ltd.
Constructive model predictive control for constrained nonlinear systems
Authors: He De‐Feng , Ji Hai‐Bo
Published: February 2008

This paper develops a new model predictive control (MPC) design for stabilization of continuous‐time nonlinear systems subject to state and input constraints. The key idea is to construct an analytic form of the controller with some undetermined parameters and to calculate the parameters by minimizing online a performance index. By using the method of control Lyapunov functions (CLFs), we construct an appropriate variation on Sontag's formula, with one degree of freedom reflecting ‘decay rate’ of CLFs. Moreover, the constructed univariate control law is used to characterize the terminal region that guarantees the feasibility of the optimal control problem. Provided that the initial feasibility of the optimization problem is satisfied, the stability of the control scheme can be guaranteed. An example is given to illustrate the application of the constructive MPC design. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of the gene coding for the BRCA2‐Interacting protein PALB2 in hereditary prostate cancer
Authors: Tischkowitz Marc , Sabbaghian Nelly , Ray Anna M. , Lange Ethan M. , Foulkes William D. , Cooney Kathleen A.
Published: February 2008

BACKGROUND

The genetic basis of susceptibility to prostate cancer (PRCA) remains elusive. Mutations in BRCA2 have been associated with increased prostate cancer risk and account for around 2% of young onset (<56 years) prostate cancer cases. PALB2 is a recently identified breast cancer susceptibility gene whose protein is closely associated with BRCA2 and is essential for BRCA2 anchorage to nuclear structures. This functional relationship made PALB2 a candidate PRCA susceptibility gene.

METHODS

We sequenced PALB2 in probands from 95 PRCA families, 77 of which had two or more cases of early onset PRCA (age at diagnosis <55 years), and the remaining 18 had one case of early onset PRCA and five or more total cases of PRCA.

RESULTS

Two previously unreported variants, K18R and V925L were identified, neither of which is in a known PALB2 functional domain and both of which are unlikely to be pathogenic. No truncating mutations were identified.

CONCLUSIONS

These results indicate that deleterious PALB2 mutations are unlikely to play a significant role in hereditary prostate cancer. Prostate 68: 675–678, 2008. © 2008 Wiley‐Liss, Inc.
Potentiation of 2‐Methoxyestradiol‐Induced cytotoxicity by blocking endothelin A receptor in prostate cancer cells
Authors: Mabjeesh Nicola J. , Shefler Alexander , Amir Sharon , Matzkin Haim
Published: February 2008

BACKGROUND

2‐Methoxyestradiol (2ME2) is an antitumoral and antiangiogenic compound that inhibits hypoxia‐inducible factor (HIF)‐1, a key regulator of the hypoxic response that promotes tumor progression. HIF‐1α, the regulated subunit of HIF‐1, is overexpressed in premalignant, cancerous and metastatic lesions of prostate. Endothelin (ET)‐1 is a HIF target gene and one that plays an important role during prostate bone metastasis via its interaction with endothelin A (ETA) receptor. We reasoned that 2ME2 combined with an ETA receptor antagonist would induce potent cytotoxic effects in prostate cancer cells.

METHODS

PC‐3 and LNCaP cells were grown alone or cocultured with human osteoblasts. The cells were treated with 2ME2, with an ETA receptor antagonist (BQ‐123) or with combinations of both compounds. The cells were then evaluated for cytotoxicity, HIF‐1α protein expression and HIF‐1 transcriptional activity.

RESULTS

The combination of 2ME2 with BQ‐123 induced synergistic cytotoxic effects in prostate cancer cells and in their cocultures with osteoblasts. No synergism was observed when 2ME2 was combined with the ETB selective antagonist, BQ‐788. These results correlated with inhibition of HIF‐1α protein expression, HIF‐1 transcriptional activity, and PSA mRNA expression.

CONCLUSIONS

The ETA receptor antagonist was capable of potentiating the cytotoxic effects of 2ME2 in prostate cancer cells. These effects were apparently mediated through the inhibition of the HIF‐1 pathway. Our in vitro data strengthen the rationale for using 2ME2 in combination with ETA receptor antagonists for the treatment of metastatic prostate cancer. Prostate 68: 679–689, 2008. © 2008 Wiley‐Liss, Inc.
Potent Oncolytic activity of human enteroviruses against human prostate cancer
Authors: Berry Linda J. , Au Gough G. , Barry Richard D. , Shafren Darren R.
Published: February 2008

BACKGROUND

Oncolytic virotherapy offers a unique treatment modality for prostate cancer, especially stages that are resistant to current therapies, with the additional benefit of preferentially targeting tumor cells amongst an environment of healthy tissue. Herein, the low pathogenic enteroviruses; Coxsackievirus A21 (CVA21), as well as a bio‐selected variant of Coxsackievirus A21 (CVA21‐DAFv) and Echovirus 1 (EV1) are evaluated as novel oncolytic agents against human prostate cancer.

METHODS

The surface expression of viral receptors required for enterovirus cell attachment/entry, including intercellular adhesion molecule‐1 (ICAM‐1), decay‐accelerating factor (DAF) and integrin alpha2beta1 on a number of human prostate cancer lines was assessed by flow cytometry. Susceptibility to viral oncolysis was determined via in vitro cell lysis assays performed on cell monolayers cultured in micro titer plates. The in vivo oncolytic efficacy of the enteroviruses was assessed using xenograft models in immune compromized SCID‐mice following systemic challenge.

RESULTS

The majority of prostate cancer lines tested expressed surface ICAM‐1 and/or DAF, or alpha2beta1, facilitating significant degrees of oncolysis following in vitro viral challenge. Systemic delivery of each of the three viruses induced reduction of xenograft tumor burdens in vivo, and a therapeutic dose‐response was demonstrated for escalating doses of EV1 in the LNCaP animal model.

CONCLUSION

Enteroviruses CVA21, CVA21‐DAFv, and EV1 are potentially potent oncolytic agents against human prostate cancer. Prostate 68: 577–587, 2008. © 2008 Wiley‐Liss, Inc.
Mutations on N‐terminal region of Taiwan cobra phospholipase A2 result in structurally distorted effects
Authors: Chiou Yi‐Ling , Lin Shinne‐Ren , Chang Long‐Sen
Published: February 2008

In the present study, three Taiwan cobra PLA2 variants were prepared by adding an extra N‐terminal Met, substituting Asn‐1 by Met or deleting the N‐terminal heptapeptide. Recombinant PLA2 mutants were expressed in Escherichia coli (E. coli), and purified to homogeneity by reverse phase HPLC. Fluorescence measurement showed that the hydrophobic character of the catalytic site, the microenvironment of Trp residues and energy transfer from excited Trp to 8‐anilinonaphthalene sulfonate (ANS) were affected by N‐terminal mutations. An alteration in the structural flexibility of the active site was noted with the mutants lacking the N‐terminal heptapeptide or with an extra N‐terminal Met added as evidenced by the inability of the two variants to bind with Ba2+. Moreover, modification of Lys residues and energy transfer within the protein‐ANS complex revealed that the Ca2+‐induced change in the global structure of PLA2 was different from that in N‐terminal variants. Together with the fact that an ‘activation network’ connects the N‐terminus with the active site, our data suggest that mutagenesis on the N‐terminal region affects directly the fine structure of the catalytic site, which subsequently transmits its influence in altering the structure outside the active site of PLA2. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Facile detection of specific RNA‐polypeptide interactions by MALDI‐TOF mass spectrometry
Authors: Sugaya Maki , Saito Ryota , Matsumura Yuriko , Harada Kazuo , Katoh Akira
Published: February 2008

A simple method for the detection of specific RNA‐polypeptide interactions using MALDI‐TOF mass spectroscopy is described. Instead of direct observation of the RNA‐polypeptide complex, we attempted the indirect observation of the binding event by focusing on the disappearance of the free polypeptide signal upon interaction with RNA. As a result, specific binding of the Rev‐response element (RRE) RNA of the HIV with two RRE‐binding peptide aptamers, DLA and RLA peptides, as well as the bacteriophage λ boxB RNA with the λ N peptide was observed. We also show that specific RNA‐binding peptides can be identified from a mixture of peptides with varying RNA‐binding affinity, showing that the method could be applied to high‐throughput screening from simple peptide libraries. The method described in this study provides a quick and simple method for detecting specific RNA–polypeptide interactions that avoids difficulties associated with direct observation of RNA and RNA–polypeptide complexes, which may find various applications in the analysis of RNA–polypeptide interactions and in the identification of novel RNA‐binding polypeptides. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Creating and preserving multi‐partite entanglement with spin chains
Authors: D'Amico Irene , Lovett Brendon W. , Spiller Timothy P.
Published: February 2008

We show how multi‐partite entanglement, such as of W‐state form, can be created in branched spin chain systems. We also discuss the preservation of such entanglement, once created.

The technique could be applied to actual spin chain systems, or to other physical systems such as strings of coupled quantum dots, molecules or atoms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐photon processes in quantum dots: biexciton Rabi oscillations and exciton polarization flipping
Authors: Machnikowski Paweł
Published: February 2008

The paper discusses two‐photon Rabi oscillations between the ground state of a quantum dot and the biexciton state, as well as two‐photon oscillations between the two single‐exciton states with different circular polarizations. The effect of phonon‐induced decoherence on these processes is also described. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nuclear field effect on the spin dynamics of electron localized on a donor in a single quantum well
Authors: Testelin C. , Aubry E. , Bernardot F. , Chamarro M. , Karczewski G.
Published: February 2008

We use photoinduced Faraday rotation (PFR) in presence of an applied magnetic field to study the spin dynamics of localized electrons. The sample is a CdTe/CdMgTe quantum well (QW) of width 80 Å containing a layer of iodine donors at its center, with concentration 1011 cm–2. The spin polarization of donor‐bound electrons is built via the optical polarization of donor‐bound excitons, their hole spin relaxation, and their recombination. In a transverse (in‐plane) magnetic field, PFR shows damped Larmor oscillations from which we deduce a 18 ns electron‐spin decoherence time, and a transverse Landé factor of 1.29. In addition, for oblique optical incidence the electron‐nuclei hyperfine interaction builds a nuclear spin polarization in presence of polarized electrons. This leads to the construction of an effective magnetic field, the Overhauser field, acting on the electronic spins. The Larmor frequency is then different for σ+ or σ– polarizations of the exciting light. The dependence of the phenomenon on the optical incidence allows the determination of the maximal Overhauser field, which is about 10 mT, at least two orders of magnitude weaker than for III‐V semiconductors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalous resonant nonlinear absorption of excitons in CdSe/ZnS quantum dots
Authors: Dneprovskii V. , Kabanin D. , Lyaskovskii V. , Wumaier T. , Zhukov E.
Published: February 2008

We have explained the observed anomalous dependence of colloidal CdSe/ZnS quantum dots' (QDs) absorption upon the intensity of input picosecond laser pulses in the case of one‐photon resonant excitation of exciton 1S3/2(h) – 1S (e) transition – the linear absorption at low intensity is replaced by nonlinear decreasing and then increasing of absorption (!) at high intensities – by saturation effect (state filling) of two‐level system with variable lifetime of the excited state (variable saturation intensity). The lifetime decreases at high excitation due to nonradiative Auger recombination. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear absorption and refraction of CdSe/ZnS quantum dots at two‐photon resonant excitation of excitons
Authors: Dneprovskii V. , Kabanin D. , Lyaskovskii V. , Santalov A. , Wumaier T. , Dang Thai Giang , Zhukov E.
Published: February 2008

The observed nonlinear absorption, optical limiting and nonlinear refraction of colloidal CdSe/ZnS quantum dots in the case of two‐photon resonant excitation of 1S3/2(h) – 1S (e) exciton transition by powerful picosecond laser pulses have been explained by two‐photon absorption and self‐defocusing effect. The results of experiments have allowed to separate self‐defocusing effects arising due to the change of nonlinear refractive index of bound electrons and nonlinear refraction from two‐photon generated carriers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of matrix parameters on mesoporous matrix based quantum computation
Authors: Hodgson T. E. , Bertino M. F. , Leventis N. , D'Amico I.
Published: February 2008

We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. We study the feasibility of performing quantum computation with different mesoporous matrices.

We analyse which matrix materials ensure that each individual stack of quantum dots can be considered isolated from the rest of the ensemble‐a key requirement of our scheme. This requirement is satisfied for all matrix materials for feasible structure parameters and GaN/AlN based quantum dots. We also show that one dimensional ensembles substantially improve performances, even of CdSe/CdS based quantum dots. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong excitonic mixing effect in asymmetric double quantum wells: On the optimization of electroabsorption modulators
Authors: Kim Dong Kwon , Citrin D. S.
Published: February 2008

We investigate the mixing of excitons originating in different subband pairs in asymmetric double quantum wells (ADQWs) in a range of electric field where the two lowest exciton states anticross. This excitonic mixing is mainly attributed to the Coulomb interactions between subbands and the valence‐subband nonparabolicity. Results show that excluding the excitonic mixing effect results in significant error in both the energies and the oscillator strengths of the excitons in an ADQW with thick barrier (3 nm). Even in an ADQW with a fairly thin barrier (1.2 nm), the error in the oscillator strengths can be substantial, although the errors in the computed energies may be tolerable. We find that including the mixing of excitons is indispensable in optimizing the structures of the asymmetric double quantum well electroabsorption modulators. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical and optical charging of CdTe quantum dots
Authors: Kłopotowski Ł. , Kudelski A. , Wojnar P. , Krebs O. , Voisin P. , Karczewski G. , Wojtowicz T.
Published: February 2008

We study two charging mechanisms of CdTe self assembled quantum dots embedded in a field effect structure: A standard electrical injection of carriers from the back contact resulting from an application of a gate voltage and a novel all‐optical effect. The optical charging results from a reduction of the built in electric field by an above barrier illumination, which enables the tunneling of carriers from the back contact. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Near‐field control of the light emission properties of a symmetric semiconductor quantum dot
Authors: Pistone G. , Savasta S. , Di Stefano O. , Martino G. , Girlanda R. , Portolan S.
Published: February 2008

We study the carrier capture and distribution among the available energy levels of a symmetric semiconductor quantum dot under continuous‐wave optical excitation resonant with the barrier energy levels. We find that at low temperature all the dot level‐occupations but one decrease monotonically with energy. The uncovered exception, corresponding to the second (dark) energy level, displays a steady‐state carrier density exceeding that of the lowest level more than a factor two. The root cause is not radiative recombination before relaxation to lower energy levels, but at the opposite, carrier trapping due to the symmetry‐induced suppression of radiative recombination. We show that spatially resolved photoluminescence spectroscopy can detect the evanescent waves generated by dark states occupations, allowing the observation of such effects. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence and energy structure of ultrathin InAs/AlAs quantum wells
Authors: Shamirzaev T. S. , Gilinsky A. M. , Kalagin A. K. , Zhuravlev K. S.
Published: February 2008

The energy spectrum of thin InAs/AlAs quantum wells (QWs) has been studied by photoluminescence (PL). It has been found that the PL spectra of the QWs consist of intense lines related to a no‐phonon excitonic transition accompanied with its phonon replicas. The band alignment in the QWs with the lowest conduction band states belonging to the indirect minimum is shown to be of type I. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of the concentration of protons intercalated into tungsten oxide thin films during deposition
Authors: Yamada Y. , Tajima K. , Okada M. , Bao S. , Tazawa M. , Yoshimura K. , Roos A.
Published: February 2008

Tungsten oxide thin films with protons intercalated during deposition (Hx WO3) were prepared using reactive direct‐current magnetron sputtering in a gas mixture of argon, oxy‐gen, and hydrogen. The as‐deposited films were tungsten bronze. The concentration of intercalated protons, given by the x ‐values in Hx WO3, was evaluated by electrochemically ejecting protons from the films. The x ‐value was proportional to the hydrogen flow ratio at the deposition. The dispersion of the extinction coefficient (κ) of the films was estimated by analyzing the experimental spectra measured with spectroscopic ellipsometry using the model composed of a homogeneous tungsten bronze layer with an additional surface roughness layer. As a result of this analysis, the κ ‐value increases strongly with intercalated protons, and a linear dependence existed between the x ‐value and κ ‐value. Therefore, it is possible to evaluate the x ‐value of the Hx WO3 films using this dependence without ejecting protons. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry of silicon‐containing diamond‐like carbon (DLC‐Si) films
Authors: Kato Naohiko , Mori Hiroyuki , Takahashi Naoko
Published: February 2008

To clarify optical properties of DLC‐Si film, we have studied the change in optical constants of the DLC‐Si films as a function of the Si content using spectroscopic ellipsometry. Using the 4 layered structure model (substrate/interface/film/surface roughness/adsorbed water/air), the thickness of each layer and the parameters of the Tauc‐Lorentz oscillator of the film were estimated. The calculated spectra agreed well with the measured one using the layered model with adsorbed water on the DLC‐Si films, compared to the model without water. The thickness of the adsorbed water was in the range from 1nm to 4nm on the DLC‐Si films. However, there was no adsorbed water on the DLC film. This fact is consistent with the larger content of silanol (Si‐OH) measured by the derivatization‐XPS of the DLC‐Si films, compared to that of the DLC film. We have clarified that the refractive index increased at the broad range of 200‐850 nm, the extinction coefficient at the broad range of 200‐1700 nm decreased with an increase in the Si content of the DLC‐Si films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry analysis of multilayered TiO2‐Ag thin films for photochromic application
Authors: Miao L. , Jiang T. , Tanemura S. , Tanemura M. , Nabatova‐Gabain N. , Xu G.
Published: February 2008

By altering the surrounding media of metal particles, the wavelength of surface plasma resonance can be tailored, which offers the potential for utilizing of plasma resonance related phenomenon, such as photochromism. Both sandwiched (TiO2/Ag/TiO2) and overcoated (TiO2/Ag) films with different thicknesses were deposited on quartz substrate by rf helicon magnetron sputtering method. The structure of multilayered TiO2‐Ag films and the concentration of loaded metal Ag in each layer were determined by spectroscopic ellipsometry in high accuracy. The spectral dependent dielectric functions of each layer were obtained, which exhibited typical semiconductor TiO2, metal Ag and mixture TiO2‐Ag behaviors, respectively. The surface plasma resonance peak was observed for several extremely thin mixture layers. The apparent redshift of SPR peak from 700 nm to 780 nm was happened with increasing of Ag amount from 35% to 50%. The broadening of SPR peak was found for layer 3 in sample 1 with low concentration Ag embedded in TiO2 media. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical quantities of rough films calculated by Rayleigh‐Rice theory
Authors: Franta Daniel , Ohlídal Ivan , Necas David
Published: February 2008

Experimental ellipsometric and spectroscopic data of a randomly rough silicon substrate are treated using several theoretical approaches. It is shown that the effective medium approximation and scalar diffraction theory are unsuitable approaches for treating the experimental data of rough surfaces containing spatial frequencies comparable with the wavelength of incident light. Using the Rayleigh‐Rice theory one can obtain an excellent fit of the experimental data and very close agreement between the values of the statistical parameters determined using the optical method and atomic force microscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of phase changing Ge2Sb2Te5 chalcogenide films
Authors: Franta Daniel , Hrdlicka Martin , Necas David , Frumar Miloslav , Ohlídal Ivan , Pavli šta Martin
Published: February 2008

The variable angle spectroscopic ellipsometry and spectroscopic reflectometry is used for the optical characterization of the as‐deposited and annealed Ge2Sb2Te5 (GST) films. The dispersion model of the GST films is based on the parameterization of the density of electronic states. As a consequence of annealing, roughness of the upper boundaries of the GST films originates. This annealing also causes the evident redistribution of the density of electronic states from the higher energies to lower energies. The roughening and redistribution of the electrons are explained by means of the phase change of the GST films from amorphous to polycrystalline structure. This phase change is accompanied by changing the conductivity of the films that was proved by introducing the terms of the free carriers in the dispersion model of the GST films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry and reflectometry of statistically rough surfaces exhibiting wide intervals of spatial frequencies
Authors: Ohlídal Ivan , Necas David , Franta Daniel
Published: February 2008

Two optical methods for the optical characterization of the statistically rough surfaces exhibiting wide intervals of spatial frequencies are presented. These methods employ the combination of variable angle spectroscopic ellipsometry and near‐normal spectroscopic reflectometry. The first method is based on combining the scalar diffraction theory and effective medium theory while the second method combines the scalar diffraction theory with Rayleigh‐Rice theory.

Both the methods are applied to the optical characterization of statistically rough GaAs surfaces prepared by thermal oxidation. It is shown that both the methods can be utilized for characterization of these surfaces in a reasonable way, however, the latter is more suitable for this purpose. The results of the optical characterization of the selected rough GaAs surface are supported by those obtained using atomic force microscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometric study of Ge nanocrystals embedded in SiO2 using parametric models
Authors: Basa P. , Petrik P. , Fried M. , Dâna A. , Aydinli A. , Foss S. , Finstad T. G.
Published: February 2008

Ge‐rich SiO2 layers on top of Si substrates were deposited using plasma enhanced chemical vapour deposition. Ge nanocrystals embedded in the SiO2 layers were formed by high temperature annealing. The samples were measured and evaluated by spectroscopic ellipsometry. Effective medium theory (EMT) and parametric semiconductor models have been used to model the dielectric function of the layers. Systematic dependences of the layer thickness and the oscillator parameters have been found on the annealing temperature (nanocrystal size). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of NiCrOx thin films
Authors: Dahmouchène Nora , Voué Michel , Stehlé Jean‐Louis , Defranoux Christophe , Nouvellon Corinne , De Coninck Joel
Published: February 2008

The optical properties of thin NiCrOx layers were investigated by spectroscopic ellipsometry (SE). The layers were coated on float glass by magnetron sputtering at different oxygen partial pressures (20% to 30% oxygen in the sputtering gas) and the influence of the degree of oxidation was considered in details. The optical constants of the films n and k, in the visible to near infrared spectral range (0.35 to 1.7 mm), appear to be extremely sensitive to their chemical composition. Complementary studies were carried out using Fourier transform infrared ellipsometry (FTIR‐SE) to determine the optical conductivity of the films and compare it with four‐points‐probe measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An automatic imaging spectroscopic ellipsometer for characterization of nano‐film pattern on solid substrate
Authors: Meng Y. H. , Chen Y. Y. , Qi C. , Liu L. , Jin G.
Published: February 2008

In order to characterize the physical and spatial properties of nano‐film pattern on solid substrates, an automatic imaging spectroscopic ellipsometer (ISE) based on a polarizer ‐ compensator ‐ specimen ‐ analyzer configuration in the visible region is presented. It can provide the spectroscopic ellipsometric parameters ψ (x, y, λ) and Δ (x, y, λ) of a large area specimen with a lateral resolution in the order of some microns. A SiO2 stepped layers pattern is used to demonstrate the function of the ISE which shows potential application in thin film devices such as high‐throughput bio‐chips. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
QSAR Models for Prediction of Glycogen Synthase Kinase‐3β Inhibitory Activity of Indirubin Derivatives
Authors: Lather Viney , Kristam Rajendra , Saini Jagmohan Singh , Kristam Rajendra , Karthikeyan Narasingapuram Arumugam , Balaji Vitukudi Narayana
Published: February 2008

Glycogen Synthase (GS) Kinase‐3 (GSK‐3), a serine/threonine kinase, isolated and purified as an enzyme capable of phosphorylating and inactivating the enzyme GS is a fascinating enzyme with diverse biological actions in intracellular signaling pathways. A large body of evidence supports speculation that pharmacological inhibitors of GSK‐3 could be used to treat several disorders including Alzheimer's disease and other neurodegenerative diseases, bipolar affective disorder, diabetes, various types of cancer, and diseases caused by unicellular parasites that express GSK‐3 homologues. In the present work, we have carried out a Quantitative Structure–Activity Relationship (QSAR) study on indirubin derivatives reported as potent GSK‐3β inhibitors using molecular descriptors calculated by CODESSA and Molconn‐Z. Also a novel Three‐Dimensional QSAR (3D‐QSAR) study based on the principle of the alignment of pharmacophoric features by PHASE module of Schrödinger suite has been carried out on the same set of inhibitors. Statistically significant 2‐D (R2=0.93) and 3‐D (R2=0.97) QSAR models were generated using 36 molecules in the training set. The predictive ability of both models was determined using a randomly chosen test set of eight molecules which gave predictive correlation coefficients ($\rm{ R_{{\rm{pred}}}^{\rm{2}} }$) of 0.6 and 0.91, respectively for 2‐D and 3‐D models, indicating good predictive power. The cocrystallographic data of GSK‐3β with indirubin‐3′‐monoxime ligand allowed us to compare the PHASE pharmacophore model with experimental intermolecular interactions. The results of PHASE pharmacophore hypothesis AADDRR correspond very closely to the interactions recorded in the active site of the ligand bound complex. This relation between the crystallographic data and pharmacophore hypothesis allowed us to confirm the preferential binding mode of indirubins inside the active site. These studies showed that 3D‐QSAR model is a better predictive model for the indirubins compared to 2D‐QSAR model.
Comment on the connected‐moments polynomial approach
Authors: Marmorino M. G.
Published: February 2008

Bartashevich has recently proposed two new methods for approximating eigenvalues of a Hamiltonian. The first method uses Hamiltonian moments generated from a trial function and his second method is a generalization of local energy methods. We show that the first method is equivalent to a variational one, a matrix eigenvalue problem using a Lanzcos subspace. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Simultaneous quantitative determination of amphetamines, ketamine, opiates and metabolites in human hair by gas chromatography/mass spectrometry
Authors: Wu Ya‐Hsueh , Lin Keh‐Liang , Chen Su‐Chin , Chang Yan‐Zin
Published: February 2008

A gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the determination of common drugs of abuse in Asia. The method was able to simultaneously quantify amphetamines (amphetamine; AP, methamphetamine; MA, methylenedioxy amphetamine; MDA, methylenedioxymeth mphetamine; MDMA, methylenedioxy ethylamphetamine; MDEA), ketamine (ketamine; K, norketamine; NK), and opiates (morphine; MOR, codeine; COD, 6‐acetylmorphine; 6‐AM) in human hair. Hair samples (25 mg) were washed, cut, and incubated overnight at 25°C in methanol/trifluoroacetic acid (methanol/TFA). The samples were extracted by solid‐phase extraction (SPE), derivatized using heptafluorobutyric acid anhydride (HFBA) at 70°C for 30 min, and the derivatives were analyzed by electron ionization (EI) GC/MS in selected ion monitoring mode. Confirmation was accomplished by comparing retention times and the relative abundances of selected ions with those of standards. Deuterated analogs of the analytes were used as internal standards for quantification. Calibration curves for ten analytes were established in the concentration range 0.1–10 ng/mg with high correlation coefficients (r2 > 0.999). The intra‐day and inter‐day precisions were within 12.1% and 15.8%, respectively. The intra‐day and inter‐day accuracies were between −8.7% and 10.7%, and between −5.9% and 13.8%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) obtained were 0.03 and 0.05 ng/mg for AP, MA, MDA, MDMA and MDEA; 0.05 and 0.08 ng/mg for K, NK, MOR and COD; and 0.08 and 0.1 ng/mg for 6‐AM. The recoveries were above 88.6% for all the compounds, except K and NK which were in the range of 71.7–72.7%. Eight hair samples from known polydrug abusers were examined by this method. These results show that the method is suitable for broad‐spectrum drug testing in a single hair specimen. Copyright © 2008 John Wiley & Sons, Ltd.