bluuebunny/crossref_metadata_2025 huggingface dataset:
The interrogation system for FBG sensing based on the InGaAs linear image sensor
Authors: Li Guoyu , Zhang Hao , Liu Bo , Zhang Jian , Yuan ShuZhong , Kai Guiyun , Dong Xiaoyi
Published: February 2008

This article presents an interrogation system based on the InGaAs linear image sensor. By applying SDM and WDM techniques, the interrogation system based on the InGaAs linear image sensor is designed and the system performance is analyzed. Experimental results show that the interrogation system can be used to interrogate the FBG sensors with wavelength bandwidth of 42 nm, SNR of 43 dB, wavelength accuracy of ±10 pm, and wavelength stability of ±15 pm. The system shows a good prospect for smart sensing. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1101–1104, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23282
Design and analysis of high‐power InP‐based heterostructure barrier varactor multipliers
Authors: Emadi Tahereh Arezoo
Published: February 2008

The heterostructure barrier varactor design method aims at finding optimum epitaxial layer structure and device geometry to improve the diode power handling capability. The nonlinear thermal resistance of the HBV and an empirical expression introducing the leakage current are proposed and added to the electro‐thermal HBV model. Finally, the HBV model is used to simulate various devices. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1017–1022, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23293
New basis functions for the electromagnetic solution of arbitrarily‐shaped, three dimensional conducting bodies using method of moments
Authors: Mackenzie Anne I. , Baginski Michael E. , Rao Sadasiva M.
Published: February 2008

In this work, we present a new set of basis functions, defined over a pair of planar triangular patches, for the solution of electromagnetic scattering and radiation problems associated with arbitrarily‐shaped surfaces using the method of moments solution procedure. The basis functions are constant over the function subdomain and resemble pulse functions for one and two dimensional problems. Further, another set of basis functions, point‐wise orthogonal to the first set, is also defined over the same function space. The primary objective of developing these basis functions is to utilize them for the electromagnetic solution involving conducting, dielectric, and composite bodies. However, in the present work, only the conducting body solution is presented and compared with other data. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1121–1124, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23295
Sparse factorization of finite element matrices using overlapped localizing solution modes
Authors: Choi J.‐S. , Adams R. J. , Canning F. X.
Published: February 2008

Local‐global solution (LOGOS) modes provide a computationally efficient framework for developing fast, direct solution methods for electromagnetic simulations. In this article, we demonstrate that the LOGOS framework yields fast direct solutions for finite element discretizations of the wave equation in two dimensions. For fixed‐frequency applications, numerical examples demonstrate that the memory and CPU complexities of the proposed solver are nearly linear. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1050–1054, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23298
The resonant behavior of the Fibonacci fractal tree antennas
Authors: Ozbakis Basak , Kustepeli Alp
Published: February 2008

An investigation of a novel fractal tree antenna with the application to two different geometries is presented. The antenna is designed by using the special Fibonacci number sequence which leads to nonuniform branch length ratios to form the fractal tree. This new approach gives better performance, especially in the miniaturization of the antenna, when compared with the conventional designs. The results obtained from the experiments are also compared with the computed ones and there is a very good agreement between the numerical and measured data. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1046–1050, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23299
A compact multi‐band meanderline antenna for wireless communications applications
Authors: Eldek Abdelnasser A.
Published: February 2008

This study presents a compact, multi‐band, and single‐feed microstrip antenna for wireless communications applications. The proposed antenna consists of microstrip feedline, two step power coupler, rectangular loop, and meander line. The meander line is shorted in specific positions with the loop. All these components together provide multi‐paths for the current resulting in providing multiple resonances. The meander line is used to lengthen the electrical paths while maintaining a compact size. The simulation and measurements of this design will be presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1117–1121, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23303
Broadband VCO using electronically controlled metamaterial transmission line based on varactor‐loaded split‐ring resonator
Authors: Choi Jaewon , Seo Chulhun
Published: February 2008

In this article, the broadband voltage‐controlled oscillator (VCO) using electronically controlled metamaterial transmission line based on varactor‐loaded split‐ring resonator (VLSRR) is presented. It is demonstrated that VLSRR coupled to microstrip line can lead to metamaterial transmission line with tuning capability. The negative effective permeability is realized by the VLSRR in a narrow band above the resonant frequency. The bias of VLSRR is controlled by the varactor diodes. The phase noise of VCO is −108.84 to −106.84 dBc/Hz at 100 kHz in the tuning range, 5.407–5.84 GHz. The figure of merit (FOM) called power‐frequency‐tuning‐normalized (PFTN) is 20.144 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1078–1082, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23305
Wideband circular polarization patch antenna for access point of 802.11B, G WLAN
Authors: Park Su Bin , Kim Sung Min , Yang Woon Geun
Published: February 2008

A wideband patch antenna using circular polarization was designed and implemented. To enhance the operation bandwidth of the proposed antenna, probe feeding and air gap (capacitive gap) were used. The air gap was composed of a rectangular shape near the feed point. The impedance bandwidth (VSWR < 2) was 29.01% ranging from 2.163 to 2.897 GHz and the axial ratio bandwidth (AR < 3 dB) was 5.48% ranging from 2.394 to 2.529 GHz. Measured maximum gain was approximately 6.92 dBic at 2.480 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1042–1046, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23307
Long‐range 1H1H NMR correlation: extending connectivities to remote bonds via an intermediate heterospin
Authors: Parella Teodor , Espinosa Juan Félix
Published: February 2008

An out‐and‐stay 2D proton–proton NMR correlation experiment is proposed to detect long‐range proton–proton connectivities up to six and seven bonds away. The magnetization flow pathway is based on a consecutive, dual‐step J(CH)transfer mechanism and it allows one to trace out 1H1H connectivities between protons belonging to different spin systems. This novel experimental scheme will be particularly useful in cases when carbon resonances overlap, providing connectivity information that could not be obtained in a HMBC experiment. The success of the experiment is demonstrated in the structural studies of a wide variety of chemical compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Characterization of human hair melanin and its degradation products by means of magnetic resonance techniques
Authors: Ghiani Simona , Baroni Simona , Burgio Daniela , Digilio Giuseppe , Fukuhara Masaki , Martino Paola , Monda Keiji , Nervi Carlo , Kiyomine Akira , Aime Silvio
Published: February 2008

Melanin granules (MGs) have been extracted from human Chinese black hairs by either acid hydrolysis (CH‐type MGs) or enzymatic digestion (CP‐type MGs), and their chemical structure investigated at the solid state by means of 13C cross polarization magic angle spinning (CPMAS NMR) and EPR spectroscopy. Both types of MGs contain a large amount of protein that is tightly bound to the true melanin polymer, with CP‐type MGs having a larger protein content than CH‐type ones. Moreover, MGs may also contain variable amounts of lipid‐like material. A high amount of paramagnetic metals is detected by EPR in CP‐type MGs, in particular Fe(III). Iron can be bound in two chemical forms: as isolated high spin Fe(III) ions with rhombic symmetry and as small oxy‐hydroxy Fe(III) aggregates. Iron is poorly available to chelators. CH‐type MGs contain much fewer metals. CP‐type MGs have then been subjected to partial bleaching by hydrogen peroxide in ammonia, yielding a residual solid, called residual oxidized melanin (ROM) and a soluble but still pigmented fraction called melanin free acid (MFA). MFA can be isolated by precipitation at acidic pH. The 13C‐CPMAS NMR and EPR spectra of these derivatives indicated that ROM has a structure very similar to that of parent MGs, whereas MFA shows a decrease of the protein content with respect to the melanin and a decreased amount of bound iron. Thus, the oxidative degradation of CP‐type MGs is a process not involving the bulk of MGs, but rather it proceeds from the solvent‐exposed outer parts to the interior. Copyright © 2008 John Wiley & Sons, Ltd.
The influence of embryo presence on prostaglandins synthesis and prostaglandin E2 and F2α content in corpora lutea during periimplantation period in the pig
Authors: Wasielak M. , Glowacz M. , Kaminska K. , Waclawik A. , Bogacki M.
Published: February 2008

We determined the expression of PGE2 synthase (mPGES‐1), PGF synthase (PGFS), carbonyl reductase/prostaglandin 9‐ketoreductase (CBR1) genes and the content of PGE2, PGF2α in porcine corpora lutea on Days 12–14 of pregnancy and Days 12–14 of the estrous cycle. For this study we used a surgically‐generated model in which one of the uterine horns was cut transversely and a part of this horn was detached from the uterine corpus. The expression of mPGES‐1, PGFS, and CBR1 genes and mPGES‐1/PGFS ratio were significantly higher in corpora lutea of the pregnant gilts compared to the corpora lutea from the parallel ovaries of the cyclic gilts. There was no difference in mPGES‐1, PGFS, CBR1 genes expression and mPGES‐1/PGFS ratio between corpora lutea ipsi‐(CL1) and contralateral (CL2) to the uterine horn with the developing embryos. The highest content of PGE2 was found in CL1 of the pregnant gilts. The PGE2/PGF2α ratio was significantly higher in CL1 of the pregnant gilts compared to corpora lutea from parallel ovary of the cyclic gilts. We suggest that the activity of the investigated genes is induced by compounds of embryonic origin which are not distributed only to the ipsilateral ovary but are transported within the mesometrium to both ovaries in a more systemic manner. Mol. Reprod. Dev. 75: 1208–1216, 2008. © 2008 Wiley‐Liss, Inc.
Pattern of metalloprotease activity and myofiber regeneration in skeletal muscles of mdx mice
Authors: Bani Cristiane , Lagrota‐Candido Jussara , Pinheiro Douglas Florindo , Leite Paulo Emílio Correa , Salimena Maria Cristina , Henriques‐Pons Andrea , Quirico‐Santos Thereza
Published: February 2008

Matrix metalloproteases (MMPs) are key regulatory molecules in the formation, remodeling, and degradation of extracellular matrix components in both physiological and pathological processes. Skeletal muscles of mdx dystrophic mice show distinct patterns of inflammation and regeneration, suggesting that factors within the microenvironment influence the adaptive responses of muscles with predominantly slow‐twitch or fast‐twitch fibers. This study aimed to verify the pattern of MMP activity in gastrocnemius, soleus, and diaphragm muscles and correlate it with the regenerative capability at distinct stages of the mdx myopathy. Marked inflammation and myonecrosis was associated with increased MMP‐9 activity and TNF‐α (tumor necrosis factor‐alpha) production, whereas muscle regeneration, evidenced by NCAM (neural cell adhesion molecule) expression and MMP‐2 activity, varied at different stages of the disease. Soleus muscles showed a high percentage of NCAM‐positive myofibers in the early stages (2 weeks) of the disease, but they appeared in the gastrocnemius muscles at 12 weeks and in the diaphragm at 24 weeks. Increased MMP‐2 activity in the diaphragm throughout all stages of the disease suggests important tissue remodeling, which is probably associated with persistent inflammation. The results indicate that the microenvironment of distinct skeletal muscle may influence a particular kinetic pattern of MMP activity, which ultimately favors persistent inflammation and myofiber regeneration at different stages of the myopathy in mdx mice. Muscle Nerve, 2008
Ten‐second exercise is superior to 30‐second exercise for post‐exercise facilitation in diagnosing Lambert–Eaton myasthenic syndrome
Authors: Hatanaka Yuki , Oh Shin J.
Published: February 2008

An incremental response after brief exercise or high‐rate stimulation on the repetitive nerve stimulation (RNS) test is a critical diagnostic criterion for Lambert–Eaton myasthenic syndrome (LEMS). This prospective study was performed to determine what duration of exercise shows the highest diagnostic sensitivity for LEMS. The compound muscle action potential amplitude in the abductor digiti quinti muscle was obtained at rest and after 5 s, 10 s, 15 s, 20 s, 25 s, and 30 s of exercise. Incremental responses were compared for the different exercise durations in 24 studies performed in nine LEMS patients. The increment was highest with 5‐s and 10‐s exercises (244%–243%) and lowest with 30‐s exercise (84%). A gradual decrease in the increment was noted from 5‐ to 30‐s exercise. A significant difference in the increment was noted between 5‐ to 10‐s and 20‐s to 30‐s exercise. There was significantly higher diagnostic sensitivity with the 10‐s exercise compared with 30‐s exercise at 100% increment and 60% increment levels. Higher increment and diagnostic sensitivity were achieved with 10‐s exercise than with 30‐s exercise. Thus, 10‐s exercise should be the standard protocol for the RNS test for LEMS. Muscle Nerve, 2008
Maturation of stretch‐induced contractile activity and its muscarinic regulation in isolated whole bladder strips from rat
Authors: Gevaert Thomas , Owsianik Grzegorz , Hutchings Graham , Everaerts Wouter , Nilius Bernd , De Ridder Dirk
Published: February 2008

Aim

Besides the establishment of neural reflex pathways, developmental changes in local bladder properties probably also contribute to the onset of mature voiding reflexes. Here we explored the behavior of stretch‐induced contractile activity (SIC) and its muscarinic regulation in neonatal and adult rat bladders.

Methods

SIC was studied in bladder strips from D0, D7, D28 rat pups and adult rats (15 weeks). The responses to a non‐selective [Carbachol (CA), 10−8.5–10−6 M] and an M2‐selective muscarinic agonist [arecaidine but‐2‐ynyl ester tosylate (ABET), 10−9.5–10−7 M] were studied. The expression of M2 and M3 mRNA was investigated using quantitative PCR in whole bladders. The response of SIC to KCl (50 mM) and to the non‐adrenergic non‐cholinergic (NANC) drugs Substance P (1 µM) and α,β‐Methyleneadenosine 5′‐triphosphate lithium salt (MATP) (1 µM) were also studied.

Results

We found evidence for an enhanced response to the muscarinic agonists CA and ABET in neonatal bladders. This might be due to the onset of a direct contractile role for M2, given the moderate M2‐properties of ABET and the absence of ABET‐effects on adult bladder strips. Further data showed an increased expression of both M2 and M3 at the mRNA level and a changed response of SIC to NANC drugs in neonatal bladder.

Conclusions

This study reveals a changed response of SIC to muscarinic and NANC drugs in neonatal rat bladder together with changes at the muscarinic mRNA level, which might all contribute to a better insight in the role of SIC in the onset of mature voiding. Neurourol. Urodynam. 29:789–796, 2010. © 2010 Wiley‐Liss, Inc.
The minimal important change of the PRAFAB questionnaire in women with stress urinary incontinence: Results from a prospective cohort study
Authors: Hendriks Erik J.M. , Bernards Arnold T.M. , de Bie Rob A. , de Vet Henrica C.W.
Published: February 2008

Aim

To estimate the minimal important change (MIC) of the total PRAFAB questionnaire (PRAFAB‐Q) score in women referred for physiotherapy intervention following primary or recurrent episodes of stress urinary incontinence. MIC values could be applied to individual patients and used as a threshold by which practitioners decide to continue, change or end a specific intervention.

Methods

Data were derived from a prospective cohort study of 279 mainly Caucasian women. MIC values were determined by: (1) the ‘mean change’ method, (2) the ROC method, and (3) the 95% limit cut‐off point, visualized by the ‘anchor‐based MIC distribution’. These MIC values were compared to the smallest detectable change (SDC) accounting for measurement error. The effect of initial baseline scores on the MIC was assessed.

Results

The results of all methods used to define the MIC ranged from 1.9 to 2.7 points (SDC = 1.6) for the non‐severe and 3.6–4.1 (SDC = 2.3) for the severe stratified patients. All MIC estimates were larger than the measurement error as determined by the SDC.

Conclusions

The total PRAFAB‐Q score is a brief and simple outcome measure that easily can be used to monitor progress and to interpret meaningful improvement in individual women with stress UI in everyday clinical practice. Neurourol. Urodynam. 27:379–387, 2008. © 2008 Wiley‐Liss, Inc.
Incontinence and pelvic organ prolapse in parous/nulliparous pairs of identical twins
Authors: Buchsbaum Gunhilde M. , Duecy Erin E.
Published: February 2008

Aim

To evaluate the role of vaginal delivery in the development of urinary incontinence and pelvic organ prolapse in four sets of identical twins.

Methods

Four sets of identical twins were identified from 101 pairs of parous/nulliparous postmenopausal sister pairs, who completed a comprehensive questionnaire, and underwent clinical evaluation of urinary incontinence and pelvic organ prolapse as part of a study. Findings of identical twin sisters were compared to each other.

Results

Ages ranged from 52 to 56 years; the parous sister in each pair had two vaginal deliveries. Two twin pairs reported no incontinence. One pair reported incontinence with activities and stress incontinence was confirmed with VLPP of 120 and 130 cm H2O in the nulliparous and parous sister respectively. In one pair only the nulliparous sister reported incontinence, however both sisters were diagnosed with stress incontinence with VLLP of 130 and 120 cm in the nulliparous and parous sister respectively. Using POP‐Q staging for relaxation of the pelvic support system, only one twin pair had a greater than 1 stage difference in any compartment.

Conclusions

All four pairs of identical twins were diagnosed with identical continence status. Three pairs were identical with regard to support in all three compartments. Vaginal delivery was not associated with urinary incontinence or clinically relevant differences in relaxation of the pelvic support system within four sets of postmenopausal identical twins with different parity status. Neurourol. Urodynam. 27:496–498, 2008. © 2008 Wiley‐Liss, Inc.
The detrusor glycogen content of a de‐obstructed bladder reflects the functional history of that bladder during PBOO
Authors: de Jong Bas W.D. , Wolffenbuttel Katja P. , Scheepe Jeroen R. , Kok Dirk J.
Published: February 2008

Aims

To determine if detrusor glycogen content in a bladder after removal of a urethral obstruction reflects the situation of bladder dysfunction as it existed during the period of obstruction.

Methods

The glycogen content of the detrusor was scored using a Periodic Acid Schiff's (PAS) staining. It was related to the functional history of the bladder. Bladder tissue was obtained from a guinea‐pig model for posterior urethral valves where animals had been obstructed for up to 10 weeks, de‐obstructed and allowed to recover for 2‐‐8 weeks. Bladder urodynamic function had been documented with multiple measurements for the complete period of obstruction and de‐obstruction.

Results

The degree of glycogen deposition in a bladder after de‐obstruction correlated directly with bladder function during obstruction. The strongest glycogen deposition was found in bladders having experienced the highest pressures, most instabilities, lowest compliance and highest contractility. In contrast, the bladder glycogen content was not related to the function of the bladder at the day the tissue was obtained, except for a relation between high glycogen content and continuing low compliance.

Conclusions

The glycogen content of a bladder reflects the history of bladder dysfunction, also when measured during a recovery period. This window on the functional history of a bladder may be of clinical value for picking out potential bad‐responders to therapy in patients with incomplete data on bladder function during a previous period of bladder obstruction. Neurourol. Urodynam. 27:454–460, 2008. © 2008 Wiley‐Liss, Inc.
Prehistoric dental modification in West Africa – early evidence from Karkarichinkat Nord, Mali
Authors: Finucane B. C. , Manning K. , Touré M.
Published: February 2008

This paper reports the earliest securely dated evidence for intentional dental modification in West Africa. Human remains representing 11 individuals were recovered from the sites of Karkarichikat Nord (KN05) and Karkarichinkat Sud (KS05) in the lower Tilemsi Valley of eastern Mali. The modified anterior maxillary dentitions of four individuals were recovered from KN05. The dental modification involved the removal of the mesial and distal angles of the incisor, as well as the mesial angles of the canines. The modifications did not result from task‐specific wear or trauma, but appear instead to have been produced for aesthetic purposes. All of the filed teeth belonged to probable females, suggesting the possibility of sex‐specific cultural modification. Radiocarbon dates from the site indicate that the remains pertain to the Late Stone Age (ca. 4500–4200 BP). Dental modification has not previously been reported from this region of West Africa and our findings indicate that the practice was more widespread during prehistory. Copyright © 2008 John Wiley & Sons, Ltd.
Neuroendocrine transdifferentiation induced by VPA is mediated by PPARγ activation and confers resistance to antiblastic therapy in prostate carcinoma
Authors: Angelucci Adriano , Muzi Paola , Cristiano Loredana , Millimaggi Danilo , Cimini AnnaMaria , Dolo Vincenza , Miano Roberto , Vicentini Carlo , Cerù Maria Paola , Bologna Mauro
Published: February 2008

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the Western Countries. When prostatectomy fails to eradicate the primary tumor, PCa is generally refractory to all therapeutic approaches. Valproic acid (VPA) is a promising anticancer agent recently assigned to the class of histone deacetylase (HDAC) inhibitors. However molecular mechanisms underlying VPA action in PCa cells are largely unknown and further experimental validation to prove its potential application in clinic practice is needed.

RESULTS

In our study we show that VPA is a potent inducer of neuro‐endocrine transdifferentiation (NET) in androgen receptor null PCa cells, both in vitro and in vivo. NET was an early event detectable through the expression of neuro‐endocrine (NE) markers within 72 hr after VPA treatment and it was associated to a reduction in the overall cell proliferation. When we interrupted VPA treatment we observed the recovery in residual cells of the basal proliferation rate both in vitro and in a xenograft model. The NET process was related to Bcl‐2 over‐expression in non‐NE PCa cells and to the activation of PPARγ in NE cells. The use of specific PPARγ antagonist was able to reduce significantly the expression of NE markers induced by VPA.

CONCLUSIONS

Our data indicate that the use of VPA as monotherapy in PCa has to be considered with extreme caution, since it may induce an unfavorable NET. In order to counteract the VPA‐induced NET, the inhibition of PPARγ may represent a suitable adjuvant treatment strategy and awaits further experimental validation. Prostate 68: 588–598, 2008. © 2008 Wiley‐Liss, Inc.
Functional angiotensin II type 2 receptors inhibit growth factor signaling in LNCaP and PC3 prostate cancer cell lines
Authors: Chow L. , Rezmann L. , Imamura K. , Wang L. , Catt K. , Tikellis C. , Louis W.J. , Frauman A.G. , Louis S.N.S.
Published: February 2008

BACKGROUND

There is clear evidence of a tissue‐based renin‐angiotensin system in the prostate and studies to date suggest that AT1‐receptor blocking drugs inhibit the growth of some prostate cancer cell lines and delay the development of prostate cancer. The present studies examine the action of Ang II in two prostate cancer cell lines and report the presence of functional AT2‐receptors that regulate the actions of growth factors.

METHODS

Immunohistochemistry was used to identify the presence of Ang II and QPCR techniques to examine AT1‐ and AT2‐receptor mRNA expression in androgen‐dependent (LNCaP) and independent (PC3) cell lines. The effects of AT1‐ and AT2‐receptor activation upon EGF‐induced DNA synthesis and ERK2 phosphorylation in these cells were also examined.

RESULTS

Functional AT2‐receptors together with Ang II were identified in both cell lines and stimulation of these receptors inhibited EGF‐induced DNA synthesis and ERK2 phosphorylation. AT1‐receptors, although present in both cell lines, were only functional in LNCaP cells where activation stimulated DNA synthesis.

CONCLUSIONS

Functional AT2‐receptors are present and have the capacity to inhibit EGF‐induced prostate cancer cell growth in LNCaP and fast growing androgen‐independent PC3 cell lines, whereas functional AT1‐receptors are found only in LNCaP cells where their activation stimulates DNA synthesis. Prostate 68: 651–660, 2008. © 2008 Wiley‐Liss, Inc.
Many body effects in the optical behavior of quantum well excitons
Authors: Kochereshko V. P. , Andronikov D. A. , Klochikhin A. A. , Crooker S. A. , Karczewski G. , Kossut J.
Published: February 2008

Modulation‐doped CdTe/Cd0.7Mg0.3Te quantum well structures with a two dimensional electron gas of low and moderate density (from ne = 3 × 1010 cm–2 up to ne ≈ 1012 cm–2) have been studied. Photoluminescence spectra taken from the quantum well in magnetic fields from 0 T to 45 T at different electron densities were studied. The observed spectra were analyzed in terms of combined exciton‐electron processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of recapture on the emission statistics of short radiative lifetime quantum dots
Authors: Peter E. , Laurent S. , Bloch J. , Hours J. , Varoutsis S. , Martrou D. , Robert‐Philip I. , Beveratos A. , Lemaître A. , Cavanna A. , Patriarche G. , Senellart P.
Published: February 2008

Single photon emission is investigated for fast radiative quantum dots. A simple model including capture process shows that the probability that a second photon is emitted increases when decreasing the exciton radiative lifetime. This effect is experimentally demonstrated through photon correlation measurements on single GaAs quantum dots presenting various radiative lifetime. The same model is used to estimate the second order autocorrelation function for an InAs quantum dot experiencing strong Purcell effect. The calculation shows the limitations of using Purcell effect to realize efficient single photon sources. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence of a single InAs/AlAs quantum dot
Authors: Shamirzaev T. S. , Zhuravlev K. S. , Larsson M. , Holtz P. O.
Published: February 2008

Micro‐photoluminescence (μ‐PL) of a simple InAs/AlAs quantum dot (QD) has been studied. It has been found that the μ‐PL emission related to the recombination in a single QD is strongly broadened probably due to spectral diffusion. Emissions related to the recombination of biexcitons and excitons occupying excited levels of the QD are observed in μ‐PL spectra at high excitation power densities. A red shift of the μ‐PL emissions related to recombination of excitons in the ground and excited levels of the QD with increasing excitation power gives clear evidence for type I alignment of the InAs/AlAs QD. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electromagnetically induced transparency in asymmetric double quantum wells in the transient regime
Authors: Silvestri Leonardo , Czajkowski Gerard
Published: February 2008

We report computation of the nonlinear response of a probe light in the presence of a driving field satisfying the Electromagnetically Induced Transparency (EIT) condition in the Λ configuration appropriate to an Asymmetric Double Quantum Well (ADQW). The novelty of the present results with respect to those of previous calculations is to consider the transient regime in which both the pump and the probe radiation are pulses of picosecond duration.We investigate the dependence of the transparency on pump and probe duration and also on the delay of the latter with respect to the former. We show the advantages of properly choosing the duration of the pump and the probe light and the asymmetry in the delay time of the probe. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new type of liquid refractometer
Authors: Lin Jiun‐You , Chen Jing‐Heng , Chen Kun‐Huang , Su Der‐Chin
Published: February 2008

A new liquid refractometer is proposed based on the phenomenon of total‐internal reflection and the technique of heterodyne interferometry. A special designed glass probe is immersed in the tested liquid, and a light beam is guided within this probe due to the total internal reflections. After the light beam is totally reflected at the other end of the probe, it goes back in an anti‐parallel direction of the original path. Because of multiple total‐internal reflections, the phase dif‐ ference, which is determined by the heterodyne interferometry between the p ‐ and s ‐polarizations, is greatly enhanced to result in an accurate refractive index. The feasibility of this method was demonstrated by our experimental results, and a resolution of 5×10–3 is obtained with our method. This method should, therefore, bear the merits of high accuracy, high stability, and easy operation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An alternative method for simultaneously measuring cell parameters of a twisted‐nematic liquid crystal cell
Authors: Chen Kun‐Huang , Chen Jing‐Heng , Lin Jiun‐You , Su Der‐Chin , Su Jung‐Chieh
Published: February 2008

A phase‐sensitive method is developed to simultaneously measure the cell parameters of a TNLC (twisted‐nematic liquid crystal) cell based on Jones calculus and the heterodyne interferometric ellisometry. These cell parameters include the twist angle, the cell gap, and the angle of the entrance LC director. When a circularly polarized heterodyne light beam normally passes through a TNLC cell, the phase difference between the p ‐ and s ‐ polarization of the interference signal can be measured accurately with an analyzer and the heterodyne interferometric ellisometry. The phase difference de‐ pends on the azimuth angle of the analyzer and the parameters. By substituting the measured values of the phase differences at three different azimuth angles of the analyzer into the special equations derived with Jones calculus. Hence these three parameters can be estimated by using a personal computer with numerical analysis technique. Because of its common path optical configuration and its heterodyne interferometric ellisometry, this method has many merits such as high stability against the surrounding vibration, high resolution, and easy operation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry and ellipsometric porosimetry studies of CVD low‐k dielectric films
Authors: Marsik P. , Verdonck P. , Schneider D. , De Roest D. , Kaneko S. , Baklanov M. R.
Published: February 2008

Aurora® ELK, a porous low‐k SiCOH film deposited by CVD, was used to study the effect of UV curing. Samples were cured for various curing times and the purpose of this work is to observe the effects of UV curing on optical, mechanical and structural properties of the low‐k film. We have used 1) ellipsometric porosimetry to determine the porosity and the pore‐size distribution and 2) nitrogen purged UV ellipsometry in a range from 2 to 9 eV to observe the changes of the dielectric function of the cured material. Additional FTIR and laser‐induced surface acoustic wave measurements were performed. The porogen removal and the increase of porosity were observed, and a k‐value of 2.3 was reached for the optimum curing time. However for longer curing times, densification and reduction of the porosity occurs. The growth of the hydrogen incorporation has been observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of T. Lanuginosus lipase growth on octadecanthiol using surface plasmon resonance ellipsometry
Authors: Balevicius Z. , Vaicikauskas V. , Valincius G. , Ignatjev I.
Published: February 2008

Surface plasmon resonance ellipsometry (SPRE) was used to investigate a multilayer system produced by Thermomyces Lanuginosus lipase (TLL) deposited from buffer solution onto chemically formed octadecanthiole (ODT) self‐assembled monolayer grown on a gold surface. The angular dependence of the ellipsometric parameters ψ and Δ was also investigated at a fixed wavelength (800 nm) when the TLL molecules were deposited on ODT from a buffer solution having a TLL concentration of 0.05 μM/L. Modelling the dependence of ψ and Δ on the angle of incidence using the Fresnel equations for a layered media showed that the system formed after 10 min can be imagined to be a two well defined layers: a self‐assembled ODT monolayer and a layer consisting of TLL and the buffer solution mixture. In the case of a system formed after 24 h, it was necessary to introduce an intermediate layer containing ODT and TLL molecules. The dependence of the ellipsometric parameters on angle measured at various wavelengths in the range from 750 nm to 950 nm demonstrated that the system formed in 24 h was more vitreous than a system formed in 10 min. It was concluded that for investigation of TLL and ODT molecules interaction by means of SPRE, the exposition time has to be taken into consideration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantifying the accuracy of ellipsometer systems
Authors: Johs Blaine , Herzinger C. M.
Published: February 2008

As the diversity and complexity of ellipsometric applications continue to increase, so do the requirements for ellipsometric data accuracy. In the previous ICSE‐3 conference, Aspnes identified this issue, and suggested a 0.1% target for ellipsometric accuracy [1]. Unfortunately, there is no generally accepted method for characterizing or quantifying ellipsometric data accuracy. In this paper, a simple method and metric are proposed for quantifying the accuracy of an ellipsometer system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry of anodized layer on single crystal InAsSb layer grown by melt epitaxy
Authors: Postava K. , Gao Y. Z. , Gong X. Y. , Halagačka L. , Pištora J. , Nakaoka A. , Yamaguchi T.
Published: February 2008

Anodized layers on InAsSb, InSb, and InAs surfaces are characterized using phase modulation spectroscopic ellipsometry in a wide spectral range from 0.6 to 6.5 eV. Single crystal InAs0.04Sb0.94 layer was grown using melt‐epitaxy (ME). Optical properties of anodized layer prepared on InAsSb single crystal are compared with those on pure single crystals of InAs and InSb. Ellipsometric spectra of were fitted to the Tauc‐Lorentz model describing the anodizing layer optical functions. Clear tendency of ultraviolet shift of the band gap energy with decreasing antimony content is observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of non‐stoichiometric silicon nitride films
Authors: Necas David , Perina Vratislav , Franta Daniel , Ohlídal Ivan , Zemek Josef
Published: February 2008

Characterizations of non‐stoichiometric silicon nitride films prepared by PECVD method onto silicon single crystal substrates are performed using variable angle spectroscopic ellipsometry and spectroscopic reflectometry and Rutherford backscattering spectrometry (RBS). The optical characterization employs a dispersion model based on the parametrization of the density of electronic states of the valence and conduction bands. The thin overlayers onto the upper boundaries of the films are taken into account. The values of the dispersion parameters of the SiNx films and thicknesses of these films and overlayers are determined. The ratios of Si and N atomic fractions in the individual films are evaluated using RBS. The results from the optical method and RBS are correlated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma flow induced local variation of dispersion constants of ITO‐films observed with spectroscopic imaging ellipsometry
Authors: Vaupel M. , Vinnichenko M.
Published: February 2008

The influence of the intentionally inhomogeneous plasma flow on the spatial distribution of the ITO optical properties has been investigated. The oscillator force has a minimum at low plasma flow and maxima at the high plasma flow regions of the sample. The free electron density increases at the edges of the wafer compared to the low plasma flow area of the sample. The changes are explained by varying the film microstructure and stoichiometry on macro‐ and microscopic scales. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
IR‐VIS‐UV ellipsometry, XRD and AES investigation of In/Cu and In/Pd thin films
Authors: Wronkowska A. A. , Arwin H. , Bukaluk A. , Skowroński Ł. , Trzcinski M. , Okulewicz K. , Wronkowski A.
Published: February 2008

Optical and compositional properties of In, In/Pd and Pd/In/Pd thin films evaporated on Cu and SiO2 substrates in vacuum were investigated by means of X‐ray diffractometry, Auger electron spectroscopy and spectroscopic ellipsometry methods. Auger depth profile studies were performed in order to determine the composition of InCu and InPd structures. In both systems interdiffusion of metals was detected at room temperature. The XRD patterns indicated formation of CuIn2 and PdIn3 phases in the samples. Optical properties of the composite layers containing intermetallic phases were derived from ellipsometric quantities Ψ and Δ measured in the photon energy range 0.1‐6.0 eV at different angles of incidence using suitable multilayer models for the examined samples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanism for the gas‐phase reaction between OH and 3‐methylfuran: A theoretical study
Authors: Zhang Weichao , Du Benni , Mu Lailong , Feng Changjun
Published: February 2008

The mechanism for the OH + 3‐methylfuran reaction has been studied via ab initio calculations to investigate various reaction pathways on the doublet potential energy surface. Optimizations of the reactants, products, intermediates, and transition structures are conducted using the MP2 level of theory with the 6‐311G(d,p) basis set. The single‐point electronic energy of each optimized geometry is refined with G3MP2 and G3MP2B3 calculations. The theoretical study suggests that the OH + 3‐methylfuran reaction is dominated by the formation of HC(O)CHC(CH3)CHOH (P7) and CH(OH)CHC(CH3)C(O)H (P9), formed from two low‐lying adducts, IM1 and IM2. The direct hydrogen abstraction pathways and the SN2 reaction may play a minor or negligible role in the overall reaction of OH with 3‐methylfuran. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Whether proton transition to the triphosphate tail of ATP occurs at protein kinase environment: A Car‐Parrinello ab initio molecular dynamics study
Authors: Yang Sheng‐Yong , Zou Jun , Xiang Ming‐Li , Xie Guo‐Bin , Shi Bing , Wei Yu‐Quan
Published: February 2008

Protonation state of the triphosphate tail of ATP (adenosine triphosphate) in protein environment is a fundamental issue, which has significant impact on the mechanism investigation of biochemical processes with ATP involved. Proton transition from surroundings (water molecule coordinating to magnesium, HW; amino group of Lys, HL) to the ATP tail in the catalytic core of protein kinase found recently disproved the commonly accepted deprotonation state of ATP tail. In this account, Car‐Parrinello ab initio molecular dynamics (CP‐AIMD) method has been employed to examine whether the proton transition occurs. To provide a comparison basis for the dynamics simulations, static quantum mechanics (QM), and combined quantum mechanics and molecular mechanics (QM/MM) calculations have also been carried out. Consistent results have been obtained that complete transition of hydrogen from the surroundings to the triphosphate tail of ATP is not allowed. The most dominant conformations correspond to the ones with HW bonding to O(W) and H‐bonding to O(ATP), [O(W)‐HW···O(ATP)], HL bonding to N(Lys) and H‐bonding to O(ATP), [N(Lys)‐HL···O(ATP)]. Metastable structures with one hydrogen atom bonding with two heavy atoms (hydrogen acceptors) were also located by our dynamic simulations. This bonding mode can satisfy the hungering for hydrogen of the two heavy atoms simultaneously. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Dissociation of a diatomic molecule induced by discontinuous reversals of a static electric field
Authors: Ghosh S. , Bhattacharyya S. P.
Published: February 2008

A diatomic molecule modeled by a Morse oscillator is shown to undergo dissociation if the external electric field, in which the molecule is placed, undergoes discontinuous reversals. A threshold frequency of reversal is found to exist. The classical behavior is compared with its quantum counterpart. The mechanism of dissociation is analyzed. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Theoretical studies on the binding models of tetramethylammonium with phenol: Cation‐π and hydrogen‐bond interactions
Authors: Jiang Yanke , Wu Jun , Zou Jianwei , Lu Yunxiang , Hu Guixiang , Yu Qingsen
Published: February 2008

A series of computations on the tetramethylammonium (TMA)‐phenol system were carried out with density functional theory (DFT) and Möller‐Plesset second order perturbation (MP2) methods at level of 6‐31+G**. The optimized structures obtained by the MP2 method are different from that obtained by the DFT method because of the influence of dispersion forces. Electron correlation contributes over 50% of total binding energy, and its influence on TMA–phenol system is similar to TMA–furan (50%) system, whereas much more significant than that in the TMA–imidazole (20%). Four different configurations for the TMA–phenol complex have been located. The interconverting barriers among the four binding models are less than 1 kcal/mol, significantly lower than those for the complex NH4+‐phenol. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Density functional theory study on hydrogen‐bonded complexes of adenine with polyformamide molecules
Authors: Tang Ke , Sun Haitao , Zhou Zhengyu , Wang Zhizhong
Published: February 2008

The structures of hydrogen‐bonded complexes A–Fn(n= 2–7) of adenine with polyformamide molecules have been fully optimized at B3LYP/6‐31G(d) basis set level. All the formamide molecules prefer to be NH proton donor rather than CH proton donor and are favorably bound to the five‐numbered moiety of adenine. A displacement of formamide molecules to one side of adenine mean plane has happened with an increasing number of formamide molecules. An obvious effect of hydrogen‐bonding cooperativity can be seen during the complex process. The most interesting geometrical change of adenine upon the complex is the shortening of the bond C4N6 resulting from the strengthening of the conjugation between the π system of the adenine ring and the lone pair of the nitrogen atom. An existence of weak NH···π bonding interaction between the π system of adenine and NH bond of F7 is found and further conformed by an natural bond orbital analysis specially carried out on A–F7. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Speciation of Energetic Materials on a Microcantilever Using Surface Reduction
Authors: Yi Dechang , Senesac Larry , Thundat Thomas
Published: February 2008

Although microcantilevers have been used to detect explosives with extremely high sensitivity using variations in adsorption‐induced bending and resonance frequency, obtaining selectivity remains a challenge. Reversible chemoselectivity at ambient temperatures based on receptor‐based detection provides only limited selectivity due to the generality of chemical interactions. The oxygen imbalance in secondary explosives presents a means to achieve receptor‐free speciation of explosives using surface reduction of adsorbed molecules. We demonstrate highly selective and real‐time detection of Trinitrotoluene (TNT) using a copper oxide‐coated cantilever with a surface reduction approach. Not only can this technique exclusively differentiate explosives from nonexplosives, but also it has the potential to specify individual explosives such as TNT, pentaerythritol tetranitrate (PETN), and RDX. This technique together with receptor‐based detection techniques provides a multimodal approach for achieving very high selectivity. SCANNING 30: 000–000, 2008. © 2008 Wiley Periodicals, Inc.
Study of oxide protective layers on stainless steel by AES, EDS and XPS
Authors: Mandrino Djordje , Godec Matjaž , Torkar Matjaž , Jenko Monika
Published: February 2008

A protective oxide layer was formed on the surface of stainless steel by standard industrial‐type thermal treatment. Additional post‐thermal treatment annealing and polishing followed by annealing were applied in an attempt to improve characteristics of the layers. Oxide layers formed on samples without and with different types of post‐thermal treatment processing were analysed and compared. Several techniques were employed. SEM was used to image the surface; AES, XPS and energy‐dispersive spectroscopy (EDS) were all used to probe the elemental composition of the oxide layers. AES was also used as the most straightforward method to obtain depth profiles. Low beam energy EDS was used in an attempt to obtain some fast averaged volume information from the layers. XPS was mainly used for determining chemical states on the surface of the sample but not for depth profiling (low sputtering rate due to large illuminated area). Analysed samples differed with regard to surface morphology of the oxide layers, oxide layer compositions and thicknesses. An attempt was made to relate these differences to differences in post‐thermal treatment procedures. Copyright © 2008 John Wiley & Sons, Ltd.