bluuebunny/crossref_metadata_2025 huggingface dataset:
Poly(vinylpyrrolidone)‐stabilized silver nanoparticles for strained‐silicon surface enhanced Raman spectroscopy
Authors: Corr Stuart J. , O'Reilly Lisa , Dillon Eoghan P. , Barron Andrew R. , McNally Patrick J.
Published: June 2011

Poly(vinylpyrrolidone)‐stabilized silver nanoparticles deposited onto strained‐silicon layers grown on graded Si1−xGex virtual substrates are utilized for selective amplification of the Si–Si vibration mode of strained silicon via surface‐enhanced Raman scattering spectroscopy. This solution‐based technique allows rapid, highly sensitive and accurate characterization of strained silicon whose Raman signal would usually be overshadowed by the underlying bulk SiGe Raman spectra. The analysis was performed on strained silicon samples of thickness 9, 17.5 and 42 nm using a 488 nm Ar+ micro‐Raman excitation source. The quantitative determination of strained‐silicon enhancement factors was also made. Copyright © 2011 John Wiley & Sons, Ltd.
Cavity‐backed slot array antenna in substrate‐integrated waveguide technology
Authors: Jiménez‐Fernández Manuel J. , Torres‐Sánchez Roberto , Otero Pablo
Published: June 2011

A slot array placed on the face of a cavity realized in substrate‐integrated waveguide technology is presented. Guidelines to design similar antennas are provided. The design has been done with the help of commercial software. The result is a low‐cost, directive array antenna with a single feeding microstrip‐line. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26165
FET Frequency doubler with out‐of‐phase switchable output and application in balanced frequency doubler
Authors: Yang Ning , Caloz Christophe , Wu Ke
Published: June 2011

A field effect transistor (FET) frequency doubler, with 180° out‐of‐phase alternate output by switching the bias status of FET at pinch‐off (Vgg ≈ Vt) or saturation (Vgg ≈ 0) is proposed.With such bias conditions, the former conducts in the positive half‐cycle of the input signal, while the latter conducts in the negative half‐cycle. Based on this concept, a new frequency doubler architecture is proposed. Without an input balun, it is more compact than conventional balanced frequency doubler. In addition, it provides an alternate doubler with differential output. To demonstrate this concept, a single‐ended 5–10 GHz doubler tested at the two bias conditions is designed and demonstrated experimentally to provide opposite‐phase outputs for the two cases. The output phase difference error is less than 4° and over 42‐dB fundamental frequency rejection is achieved. The conversion gain measured at 10 GHz is 2.5 dB for an input power of 5 dBm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26172
A study of erbium–ytterbium‐codoped polymer waveguide amplifier
Authors: Zhang Dan , Zhang Daming , Liang Xu , Wang Fei , Guo Donghui
Published: June 2011

In this article, organic/inorganic hybrid matrix doped with Er3+,Yb3+ nanoparticles was synthesized and used as the core material to fabricate the waveguide amplifier. The absorption and luminescence spectra of the material were characterized. An X‐ray photoelectron spectroscopy analysis was performed to characterize the changes on the surface elemental composition of the material in the reactive ion etching processes. An embedded channel waveguides based on this material were demonstrated. Optical gains of 2.3 and 3.5 dB/cm at 1534 and 1550 nm wavelengths, respectively, were obtained in different dimensions of waveguides. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26193
Printed two monopole‐antenna system with a decoupling neutralization line for 2.4‐GHz MIMO applications
Authors: Su Saou‐Wen , Lee Cheng‐Tse
Published: June 2011

A multiantenna system with two printed monopoles decoupled by using the neutralization‐line technique for 2.4‐GHz‐MIMO USB dongles is presented. The two monopoles are located on the two opposite corners of the PCB and spaced 10.5 mm apart by a small ground portion, which provides a layout area for antenna feeding network and optional I‐PEX connectors for the use of standalone antennas. It was found that by removing only 1‐mm‐long inwards from the edge and linking two monopoles therein by a thin printed line, the antenna port isolation can be effectively improved. This decoupling line occupies little board space such that there requires no conventional modification to the system ground plane for mitigating the mutual coupling. The proposed design is very suitable for the wireless module‐card solution in the form factor of a USB dongle. Details of the design prototype are discussed in the article. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26199
Novel triple‐bandpass microstrip filter with flexible passband assignment
Authors: Liang Fei , Luo Bin , Lu Wen‐Zhong
Published: June 2011

A novel approach for designing triple‐bandpass filters has been presented in this letter.The triple‐bandpass filters are constructed by stepped impedance resonators and common half‐wavelength resonators. The stepped‐impedance resonators operate at the first and third passband and some coupled resonators are introduced to increase the degrees of freedom in extracting coupling coefficients of the first and third passband. The other resonators are designed to operate at the second passband. This structure improves design freedom to fit easily the specific coupling coefficients at all passbands simultaneously and the locations of each passband can also be tuned in a large region. To verify the presented concept, two experimental examples of filters with a triple‐band Chebyshev and triple‐band quasi‐elliptic response operating at 2.4, 3.6, and 5.2 GHz was designed and fabricated with microstrip technology. The measured results are in good agreement with the full‐wave simulation results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26207
Full‐wave analysis of a microwave rectifying circuit using finite difference time domain algorithm
Authors: Cai Peng , Yang Xue‐Xia , Huang Jian , Zhang Yong , Chen Bin , Guan Xuehui
Published: June 2011

This article presents a study on calculating the conversion efficiency of a microwave rectifying circuit by using finite difference time domain (FDTD) algorithm. To properly descript the lumped device in FDTD algorithm, the nonlinear lumped network (NL2N)‐FDTD method is further extended to model Schottky diode placed across multiple FDTD cells. As a result, a group of formulae are obtained and applied to analyze a typical microwave rectifying circuit, including a nonlinear lumped device of Schottky diode HSMS‐282. The good agreement between FDTD analysis results and ADS simulated ones illustrates the validation of the derived formulae and method. This FDTD analytical method can be used to design and optimize rectifying circuits with high radio frequency–direct current conversion efficiency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26209
Design and implementation of second‐order microwave integrators
Authors: Tsai Lin‐Chuan , Fang Han‐Sheng
Published: June 2011

In this letter, we propose the second‐order integrators in the Z domain; the second‐order integrators are obtained by interpolating the traditional Simpson's‐ and trapezoidal‐rule integrators. This formulation, in conjunction with the representations of transmission‐line elements in the Z domain, leads to the transmission‐line configuration that is eligible for a microwave integrator. We implement second‐order integrators in the microstrip format that has an operating frequency up to 8.5 GHz. The frequency responses of the second‐order integrators were measured to validate this new formulation. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26210
Broadband planar antenna with T‐shaped strip and capacitively coupled shorted strip
Authors: Kim Woo‐Su , Yoon Cheol , Oh Soon‐Soo , Kang Suk‐Youb , Park Hyo‐Dal
Published: June 2011

This letter describes a broadband planar antenna embedded in LTE700/GSM handheld terminals. The antenna consists of a T‐shaped strip fed by a 50‐Ω coaxial cable and a shorted strip excited by capacitive coupling. The capacitively coupled shorted strip shows the resonance at the lower frequency band, and the T‐shaped strip presents good matching at the higher frequency band, because the characteristics of input impedance are affected by the capacitive coupling. The proposed antenna was simulated and fabricated. The measured bandwidth based on 3:1 VSWR was 0.62–1.53 GHz, which covers the frequencies used for LTE700, GSM800/850/900 mobile communications as well as the military applications. This antenna would be also useful for broadband wireless communications using the technique such as software‐defined radio or cognitive radio. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26211
New microstrip fractal‐shaped square patch resonators filters
Authors: La Dong‐sheng , Lu Ying‐hua , Liu Ning , Cui Dong‐nuan , Zhang Jin‐ling
Published: June 2011

This article proposes and optimizes two types of band‐pass filters using fractal‐shaped square resonators. The filters have many remarkable advantages by using etched fractal‐shaped defected structures in the square patch resonators, such as compact size, high selectivity, and simple structure. The resonant characteristics of the filters are reported and can be adjusted by changing the parameters of the fractal‐shaped structures. Good agreement between the simulation results and the measurement results is achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26212
Monopole antenna based on the modified ground plane for wireless local‐area network application
Authors: Jiang Wen , Gong Shu‐Xi , Yu Song‐Tao
Published: June 2011

A monopole antenna with modified ground plane is presented for 2.4 and 5 GHz wireless local area network applications in this article.A trapezoid patch and a quasifractal slotted patch are printed on two FR‐4 dielectric substrates as the radiator and the ground plane of the antenna, respectively. The element of the quasifractal slot structure is a circular ring with four branches. The radiation characteristics are simulated and experimentally verified, and the results show that the proposed antenna has good radiation performance. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26216
Design of microstrip‐fed monopole antenna with two branch strips and a rectangular slit ground for dual‐band WLAN operations
Authors: Yoon Joong Han , Oh Sang Jin , Kim Woo Su
Published: June 2011

A dual‐band planar antenna that was developed for wireless local area network (WLAN) application is presented in this article.The proposed antenna, which has two strip lines for resonance and a rectangular ring strip for matching, was designed to cover the popular frequency spectra of the 2.4 and 5 GHz WLAN bands. Also, an asymmetric ground and a rectangular slit in the ground are introduced to enhance the performance of the proposed antenna. The proposed antenna, which is capable of dual‐frequency operation, is fed by a strip line. The obtained numerical results agree well with the experiment data. It was validated that the configuration can meet the demands of WLAN systems and effectively enhanced the impedance bandwidth to 16.8% for the lower band and 58.14% for the upper band when VSWR < 2. This article also presents and discusses the 2D radiation patterns and gains according to the results of the experiment. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26225
UWB true‐time‐delay lines inspired by CRLH TL unit cells
Authors: Zhang J. , Cheung S.W. , Yuk T.I.
Published: June 2011

This article presents the design of ultra‐wideband (UWB) true‐time‐delay lines (TTDLs) operating in microwave frequency.The design is inspired by the use of composite right/left‐handed transmission line (CRLH TL) unit cells as the true‐time‐delay elements to obtain large time delay. A rotated version of the CRLH TL unit cell is used to achieve UWB operation. A periodic microstrip line (PML) employing a sawtooth‐shaped periodic pattern is used to further increase the time delay. For comparison, TTDLs using the conventional CRLH TL unit cells, the PML and the right‐handed transmission line (RH TL) are also designed, optimized and fabricated. Simulation and measurement results show that, for a same length of 60 mm, our proposed TTDL has an ultrawide operating bandwidth and much larger time delay than those of the PML and RH TL ones. Moreover, it has the advantages of high return loss and low insertion loss. Finally, for easily fitting to practical circuits which normally occupy rather even widths and lengths on the printed circuit boards, the proposed straight UWB TTDL is bent to form different shapes such as circular, rectangular and meander. Results show that the performance of the TTDL is not degraded by bending into these shapes. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26228
Ewing sarcoma/primitive neuroectodermal tumor arising from the adrenal gland in an adolescent
Authors: Stephenson Jacob , Gow Kenneth W. , Meehan John , Hawkins Douglas S. , Avansino Jeffrey
Published: June 2011

We review the case of an adolescent who presented with flank pain, fatigue and a discrete nonfunctioning adrenal lesion which was found to be an adrenal Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). The patient was treated with a minimally invasive adrenalectomy as a component of multimodal therapy, including seven courses of chemotherapy and whole abdominal radiation. She is currently disease free 14 months after the operation and 3 months off therapy. Pediatr Blood Cancer 2011; 57: 691–692. © 2011 Wiley‐Liss, Inc.
Overcoming splits in our understanding of schizophrenia and its management
Authors: de Silva Prasanna N
Published: June 2011

Here, Dr de Silva discusses the discrepancies in our knowledge of the pathogenesis of schizophrenia and the different approaches to its management, and suggests some solutions on how these differences may be overcome. Copyright © 2011 Wiley Interface Ltd
Gel‐based proteomics analysis of the heterogeneity of 20S proteasomes from four human pancreatic cancer cell lines
Authors: Wang Xinli , Zhao Zhiyun , Luo Yuanming , Chen Guoqiang , Li Zhili
Published: June 2011

Purpose: The 20S proteasome is a multicatalytic protein complex, which plays a major role in intracellular protein degradation. In mammalian cells, it consists of 28 subunits arranged in four stacked rings (α1‐7β1‐7β1‐7α1‐7). The aim of this study is to characterize and compare subunit composition and heterogeneity (or subtypes) of the 20S proteasome from four human pancreatic cancer cell lines.

Experimental design: To study subunit compositions and heterogeneity of 20S proteasome from human pancreatic cancer cell lines, in the present study, 20S proteasome from four different pancreatic cancer cell lines (SW1990, a human exocrine adenocarcinoma, derived from spleen metastasis; PANC‐1, a human ductal carcinoma in situ; BxPC‐3, a human ductal carcinoma in situ; and CFPAC‐1, a human ductal adenocarcinoma, derived from liver metastasis) were subjected to a gel‐based proteomics analysis, respectively.

Results: It was found that the differences in the subunit compositions and subtypes of the 20S proteasomes among four pancreatic cancer cell lines exist. Gel‐based proteomics analysis showed that more than 60 subunits spots were separated and identified by MS. Our study revealed the presence of various isoforms for each of the subunits and different subtypes of the 20S proteasome. The significant differences among four cell lines are the relative abundances of immunoproteasome subunits, β1i and β2i, indicating that different subtypes of immunoproteasome among four cell lines exist.

Conclusions and clinical relevance: The 20S proteasome from four human pancreatic cancer cell lines was characterized. The different expression levels of immunoproteasome subunits, β1i and β2i, indicate that the 20S proteasome may have different subtypes among four cell lines, which may be related to cancer cell property and be useful for the establishment of personalized therapy using proteasome inhibitors in future.
Acute bacterial inflammation of the mouse prostate
Authors: Boehm Bayli J. , Colopy Sara A. , Jerde Travis J. , Loftus Christopher J. , Bushman Wade
Published: June 2011

BACKGROUND

Prostatic inflammation is gaining increasing attention as a potential etiologic factor in prostate cancer, benign prostatic hyperplasia, lower urinary tract symptoms, and CPPS. This study was performed to address the need for a well characterized model of acute prostatic inflammation that may be used to study the effect of acute inflammation on epithelial and stromal cell proliferation, voiding behavior, and neurovascular physiology.

METHODS

Uropathogenic E. coli 1677 was instilled transurethrally into adult C57BL/6J male mice. Prostates were analyzed at 1, 2, 3, 5, 7, or 14 days post‐instillation and compared to saline‐instilled and naïve controls. Time course and severity of inflammation were characterized by the quantity and type of inflammatory infiltrate present, hemorrhage, proliferation, and reactive hyperplasia. RT‐PCR was performed to characterize inflammatory mediators including IL‐1α, IL‐1β, IL‐1RA, IL‐18, IL‐6, IL‐10, IL‐8, TNFα, and COX‐2.

RESULTS

Inflammation was evident in all lobes of the prostate with the DLP most severely affected. Infection consistently led to a significant increase in neutrophils and macrophages in the early stages of prostate infection, followed by lymphocytic inflammation at the later time points. Inflammation was accompanied by induction of several inflammatory genes, including IL‐1 family members, IL‐6, and COX‐2, and induced a significant increase in epithelial proliferation and reactive hyperplasia in all three prostate lobes.

CONCLUSIONS

Transurethral inoculation of uropathogenic E. coli 1677 reliably infects the mouse prostate, produces a significant inflammatory response, and induces quantifiable epithelial proliferation and reactive hyperplasia. Prostate 72:307–317, 2012. © 2011 Wiley Periodicals, Inc.
Does absolute neutrophil count predict high tumor grade in African‐American men with prostate cancer?
Authors: Sadeghi Neda , Badalato Gina M. , Hruby Gregory , Grann Victor , McKiernan James M.
Published: June 2011

BACKGROUND

African‐Americans (AA) are at risk for benign ethnic neutropenia (BEN), which has been implicated as a potential source of disparity in cancer outcomes among AAs. Since AAs with prostate cancer (PCa) are more likely to have aggressive pathological features, this investigation sought to determine if absolute neutrophil count (ANC) is associated with adverse pathologic findings at radical prostatectomy (RP) within a cohort of AA men.

METHODS

A single‐institution, retrospective review was conducted of all AA patients undergoing RP who had a pre‐operative CBC with differential and known RP pathology. Neutropenia was defined as ANC ≤1.5 × 109/L (1.5). Clinical and pathologic variables were characterized for the study cohort, and Cox regression and Kaplan–Meier analyses performed to evaluate the association between ANC and adverse pathology.

RESULTS

A total of 336 patients were included, and 18 patients (5.4%) had ANC ≤1.5. Mean age was 59.8 ± 7.5 years; mean follow‐up time 47.4 ± 43.3 months. Neutropenic patients had significantly higher clinical stages and pathologic Gleason scores (P < 0.05). On multivariable analysis, ANC ≤1.5 was significantly predictive of high tumor grade (HR 1.22, CI 1.01–1.48).

CONCLUSIONS

Neutropenia in AAs predicts high tumor grade at prostatectomy. Further studies are necessary to further characterize the importance of these findings with regard to the pathogenesis of PCa, particularly as it relates to the AA population. Prostate 72:386–391, 2012. © 2011 Wiley Periodicals, Inc.
GPRC6A regulates prostate cancer progression
Authors: Pi Min , Quarles L. Darryl
Published: June 2011

BACKGROUND

GPRC6A is a nutrient sensing GPCR that is activated in vitro by a variety of ligands, including amino acids, calcium, zinc, osteocalcin (OC), and testosterone. The association between nutritional factors and risk of prostate cancer, the finding of increased expression of OC in prostate cancer cells, and the association between GPRC6A and risk of prostate cancer in Japanese men implicates a role of GPRC6A in prostate cancer.

METHODS

We examined if GPRC6A is expressed in human prostate cancer cell lines and used siRNA‐mediated knockdown GPRC6A expression in prostate cancer cells to explore the function of GPRC6A in vitro. To assess the role of GPRC6A in prostate cancer progression in vivo, we intercrossed Gprc6a−/− mice onto the TRAMP mouse prostate cancer model.

RESULTS

GPRC6A transcripts were markedly increased in prostate cancer cell lines 22Rv1, PC‐3, and LNCaP, compared to the normal prostate RWPE‐1 cell line. In addition, a panel of GPRC6A ligands, including calcium, OC, and arginine, exhibited in prostate cancer cell lines a dose‐dependent stimulation of ERK activity, cell proliferation, chemotaxis, and prostate specific antigen and Runx2 gene expression. These responses were inhibited by siRNA‐mediated knockdown of GPRC6A. Finally, transfer of Gprc6a deficiency onto a TRAMP mouse model of prostate cancer significantly retarded prostate cancer progression and improved survival of compound Gprc6a−/−/TRAMP mice.

CONCLUSIONS

GPRC6A is a novel molecular target for regulating prostate growth and cancer progression. Increments in GPRC6A may augment the ability of prostate cancer cells to proliferate in response to dietary and bone derived ligands. Prostate 72:399–409, 2012. © 2011 Wiley Periodicals, Inc.
Effects of glycosylation on heparin binding and antithrombin activation by heparin
Authors: Pol‐Fachin Laercio , Franco Becker Camila , Almeida Guimarães Jorge , Verli Hugo
Published: June 2011

Antithrombin (AT), a serine protease inhibitor, circulates in blood in two major isoforms, α and β, which differ in their amount of glycosylation and affinity for heparin. After binding to this glycosaminoglycan, the native AT conformation, relatively inactive as a protease inhibitor, is converted to an activated form. In this process, β‐AT presents the higher affinity for heparin, being suggested as the major AT glycoform inhibitor in vivo. However, either the molecular basis demonstrating the differences in heparin binding to both AT isoforms or the mechanism of its conformational activation are not fully understood. Thus, the present work evaluated the effects of glycosylation and heparin binding on AT structure, function, and dynamics. Based on the obtained data, besides the native and activated forms of AT, an intermediate state, previously proposed to exist between such conformations, was also spontaneously observed in solution. Additionally, Asn135‐linked oligosaccharide caused a bending in AT‐bounded heparin, moving such polysaccharide away from helix D, which supports its reduced affinity for α‐AT. The obtained data supported the proposal of an atomic‐level, solvent and amino acid residues accounting, putative model for the transmission of the conformational signal from heparin binding exosite to β‐sheet A and the reactive center loop, also supporting the identification of differences in such transmission between the serpin glycoforms involving helix D, where the Asn135‐linked oligosaccharide stands. Such intramolecular rearrangements, together with heparin dynamics over AT surface, may support an atomic‐level explanation for the Asn135‐linked glycan influence over heparin binding and AT activation. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Spinosad resistance in female Musca domestica L. from a field‐derived population
Authors: Markussen Mette DK , Kristensen Michael
Published: June 2011

BACKGROUND: Bait‐formulated spinosad is currently being introduced for housefly (Musca domestica L.) control around the world. Spinosad resistance was evaluated in a multiresistant field population and strains derived from this by selection with insecticides. Constitutive and spinosad‐induced expression levels of three cytochrome P450 genes, CYP6A1, CYP6D1 and CYP6D3, previously reported to be involved in insecticide resistance, were examined.

RESULTS: In 2004 a baseline for spinosad toxicity of Danish houseflies where all field populations were considered to be susceptible was established. In the present study, females of a multiresistant field population 791a were, however, 27‐fold spinosad resistant at LC50, whereas 791a male houseflies were susceptible. Strain 791a was selected with spinosad, thiamethoxam, fipronil and imidacloprid, resulting in four strains with individual characteristics. Selection of 791a with spinosad did not alter spinosad resistance in either males or females, but counterselected against resistance to the insecticides thiamethoxam and imidacloprid targeting nicotinic acetylcholine receptors. A synergist study with piperonyl butoxide, as well as gene expression studies of CYP6A1, CYP6D1 and CYP6D3, indicated a partial involvement of cytochrome P450 genes in spinosad resistance.

CONCLUSION: This study reports female‐linked spinosad resistance in Danish houseflies. Negative cross‐resistance was observed between spinosad and neonicotinoids in one multiresistant housefly strain. Spinosad resistance involved alterations of cytochrome P450 gene expression. Copyright © 2011 Society of Chemical Industry
Ammonothermal GaN substrates: Growth accomplishments and applications
Authors: Dwiliński Robert , Doradziński Roman , Garczyński Jerzy , Sierzputowski Leszek , Kucharski Robert , Zając Marcin , Rudziński Mariusz , Kudrawiec Robert , Strupiński Włodzimierz , Misiewicz Jan
Published: June 2011

We are presenting some physical and chemical basis of ammonothermal method of bulk gallium nitride (GaN) synthesis in ammonobasic route. The substrates of polar, non‐polar, and semi‐polar orientation can be obtained by this method. Excellent structural and wide spectrum of electrical parameters of truly bulk GaN crystals obtained this way are revealed. Large progress in manufacturing of large size (1‐in.) non‐polar ammonothermal crystals is reported. A preliminary results on performance of the devices grown on ammonothermal GaN substrates will be shown.
AC conductivity and dielectric spectroscopic studies of polypyrrole–titanium dioxide hybrid nanocomposites
Authors: Kumar A. , Sarmah S.
Published: June 2011

Dielectric spectroscopy and AC conductivity measurements have been employed to investigate the electrical properties of disordered materials in a wide range of temperature. In this work, conducting polypyrrole–titanium dioxide (PPy–TiO2) hybrid nanocomposites have been synthesized by oxidizing pyrrole in presence of different concentration (wt%) of TiO2 nanoparticles. Thermal stability of the nanocomposites increases with the increase in TiO2 wt%. The dielectric and electric modulus studies of as prepared samples were carried out over a frequency range of 42 Hz–5 MHz. The dielectric constant and dielectric loss for all the nanocomposite samples were observed to decrease with the increase of frequency. Electric modulus analysis has been carried out to understand the electrical relaxation processes. The dielectric relaxation time of nanocomposites decreases with the increase of TiO2 nanoparticles concentration. AC conductivity measurements show that correlated barrier hopping conduction mechanism can be employed for pure PPy and PPy‐5 wt% TiO2 nanocomposites, whereas large polaron tunnelling mechanism is applicable for higher concentration of TiO2 (10–25 wt%) in PPy–TiO2 nanocomposites.
Preparation and optical characterization of PbCl2–Sb2O3–TeO2 glasses doped with rare earth elements
Authors: Kostka Petr , Zavadil Jiri , Pedlikova Jitka , Poulain Marcel
Published: June 2011

Glasses in the PbCl2–Sb2O3–TeO2 ternary system were prepared, characterized and their characteristic temperatures and glass stability were determined by thermal analysis. The most stable glass compositions were found in the TeO2 rich area of the ternary diagram. Selected glass compositions from this group were doped with Er3+, Nd3+ or Pr3+ ions. Changes in composition during the melting process were investigated, and the chemical analysis was performed using an electron microscope coupled with an EDS analyser. Optical characterizations include the transmission spectroscopy and low temperature photoluminescence (PL) measurements. The studied glasses are transparent up to 80%, and their transparency region falls between 400 nm and 6 µm. The refraction index was found to be around 2.2. A broad band centred around 970 nm was observed in the PL spectra of base glass systems. Rare earth doped samples exhibit all absorption bands in the investigated region of spectra (300–1100 nm) and also emission peaks in the range of 800–1800 nm. The re‐absorption of base glass luminescence, in the case of Er3+ doped samples, was observed at low temperature and it correlates well with 4I11/2 → 4I15/2 transition at 980 nm. The re‐absorption effect disappears above 200 K.
Surface photovoltage within a monolayer of CdSe quantum dots
Authors: Zillner Elisabeth , Dittrich Thomas
Published: June 2011

Layers of pyridine terminated CdSe quantum dots (QDs) with thicknesses from a monolayer (ML) to 80 nm were deposited on ITO substrates by dip coating. Transient surface photovoltage measurements showed dominant charge separation within the first ML of QDs at short times and an increasing influence of layer thickness at long times. Auger recombination limited the maximum of separated charge carriers to about 1 × 1012 cm‐2.

magnified image

Separation of photo‐generated electron‐hole pairs within a ML of CdSe‐QDs. Electrons were either trapped on ITO surface states or separated due to a built‐in electrical field created by a transferred electron from the ITO to a trap state at the QD. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A DFT study on the structure‐property relationship of aminonitropyrazole‐2‐oxides
Authors: Ravi P. , Gore Girish M. , Sikder Arun K. , Tewari Surya P.
Published: June 2011

Density functional theory (DFT) calculations at the B3LYP/aug‐cc‐pVDZ level have been carried out to study the geometry and electronic structures, stability, sensitivity and band gap of the possible isomers of aminonitropyrazole‐2‐oxides. Kamlet‐Jacob equations were used to determine the performance properties of model compounds. The performance properties of model compounds P5, P18, P20, P21, P22, and P23 are higher compared with 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and octanitrocubane (ONC). The heat of explosion, density, detonation velocity and detonation pressure are related to the number and positions of NO2 and NH2 groups in pyrazole‐2‐oxide. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Quantification of meCCNU‐induced dG‐dC crosslinks in oligonucleotide duplexes by liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Bai Baoqing , Zhao Lijiao , Zhong Rugang
Published: June 2011

Chloroethynitrosoureas (CENUs) are important alkylating agents widely used in the treatment of cancers. Decomposition of CENUs generates active electrophilic ions that damage DNA, including the formation of dG‐dC crosslinks which represents the most important cytotoxic mechanism of CENUs. In this work, a high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI‐MS/MS) method was employed to analyze the dG‐dC crosslinks induced by 1‐(2‐chloroethyl)‐3‐(4‐methylcyclohexyl)‐1‐nitrosourea (meCCNU, Semustine). The direct quantitation of dG‐dC crosslinks in oligonucleotide duplexes was achieved by the selected reaction monitoring (SRM) mode using synthesized 15N3‐labeled dG‐dC as an internal standard. Methods of enzymatic digestion and HPLC separation were developed for obtaining separation and reproducibility of the dG‐dC peak in chromatograms. The limit‐of‐detection (LOD) was determined to be 0.08 nM and the limit‐of‐quantification (LOQ) was determined to be 0.16 nM. The linearity of the calibration curve was 0.9997 over the range of 0.08 to 32 nM. The precision and accuracy of the method ranged from 1.1 to 6.6% and 96 to 109%, respectively. The recovery of the dG‐dC crosslink in the enzymatic hydrolysates from the oligonucleotide duplex was determined to be from 91 to 106%. The results of the validation study indicate that the method is suitable for quantifying dG‐dC crosslinks in DNA. Consequently, this method was used to determine meCCNU‐induced dG‐dC crosslinks in four duplexes with different GC contents. The results showed that the crosslinking fraction (CF) increased as the GC content in the duplex increased, and a relatively low CF was observed in the early period of the reaction. Copyright © 2011 John Wiley & Sons, Ltd.
The study on vulcanization fouling behavior of nanocrystalline layer
Authors: Mai Yong‐jin , Jie Xiao‐hua , Liu Li‐li , Yu Neng , Zheng Xiang‐xin
Published: June 2011

Mold fouling can degrade the physical properties and reduce the aesthetic value of the molded product. A plethora of research efforts have tried addressing these drawbacks, however, an effective method to prevent the foregoing adverse effects of mold fouling is still a challenge. Here, the fouling performance of aluminum alloy with a nanocrystalline surface layer fabricated by High Pressure Shot Peening (HPSP) during vulcanization has been investigated. Results indicate that an HPSP‐treated sample shows excellent resistance of mold fouling with only 1/8 weight gain after 25 cycles, compared to its HPSP‐free counterpart. The improved release performance can be attributed to the compact passivation layer with a larger thickness and low‐energy surface obtained after HPSP treatment, as well as the strengthened surface with a lower friction coefficient. Copyright © 2011 John Wiley & Sons, Ltd.
Scanning Tunneling Luminescence of Individual CdSe Nanowires
Authors: Lutz Theresa , Kabakchiev Alexander , Dufaux Thomas , Wolpert Christian , Wang Zhe , Burghard Marko , Kuhnke Klaus , Kern Klaus
Published: June 2011

The local luminescence properties of individual CdSe nanowires composed of segments of zinc blende and wurtzite crystal structures are investigated by low‐temperature scanning tunneling luminescence spectroscopy. Light emission from the wires is achieved by the direct injection of holes and electrons, without the need for coupling to tip‐induced plasmons in the underlying metal substrate. The photon energy is found to increase with decreasing wire diameter due to exciton confinement. The bulk bandgap extrapolated from the energy versus diameter dependence is consistent with photon emission from the zinc blende‐type CdSe sections.
Plasmonic Nickel Nanoantennas
Authors: Chen Jianing , Albella Pablo , Pirzadeh Zhaleh , Alonso‐González Pablo , Huth Florian , Bonetti Stefano , Bonanni Valentina , Åkerman Johan , Nogués Josep , Vavassori Paolo , Dmitriev Alexandre , Aizpurua Javier , Hillenbrand Rainer
Published: June 2011

The fundamental optical properties of pure nickel nanostructures are studied by far‐field extinction spectroscopy and optical near‐field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near‐field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near‐field and far‐field spectra, dramatic shifts are found between the near‐field and far‐field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.
Re‐centring capacity of dual‐steel frames
Authors: Dubina Dan , Stratan Aurel , Dinu Florea
Published: June 2011

Capacity design principles used in modern seismic design codes are deemed to confine plastic deformations to dissipative elements only. In conventional structures, this can be undesirable as the plastic deformations mean damage to structural elements, interruption to building operations and substantial repair works. If these elements are removable and can be replaced, the structure has the ability to return to the initial undeformed shape after an earthquake, provided restoring forces are supplied by part of the structure still within the elastic range. The objective of the present work, which continues the previous research of the authors, is to present a general methodology for designing structures with removable dissipative elements and re‐centring capability. Two applications are also presented.
Punch Problem for Planar Anisotropic Elastic Half-Plane
Authors: Lin R.-L.
Published: June 2011

The two dimensional punch problem for planar anisotropic elastic half-plane is revisited using the Lekhnitskii's formulation with aid of the Fourier transform and boundary integral equation. Four different conditions of contact problem for the rigid punch are analyzed in this study. From the combination of surface Green's function of half-plane and Hooke's law of anisotropic material, a set of Fredholm integral equations are obtained for mixed boundary value problems. After solving the integral equation according to specified contact condition, the explicit distributions of surface traction under the punch are obtained in closed-form. From the surface traction and Green's function of anisotropic half-plane, the full-field solutions of stresses are constructed. Numerical calculations of surface traction under the rigid punch are presented base on the analysis and are discussed in detail.
On the Use of Temporal Reachout Technique for Characteristics Method with Time-Line Cubic Spline Interpolation
Authors: Tsai T.-L. , Chen J.-Y.
Published: June 2011

The study had indicated that the computational performances of the characteristics method with the time-line cubic spline interpolation are related to the endpoint constraint, especially for large Courant number in which the foot of the characteristic trajectory is located near the endpoint. The first derivative endpoint constraint with higher-order central difference approximation provides better simulation results among various endpoint constraints, but it still induces some degree of numerical error. In this study, by locating the foot of the characteristic trajectory away from the endpoint, the temporal reachout technique is proposed to avoid the effect of endpoint constraint on the time-line cubic spline interpolation. Modeling the transport of a Gaussian concentration distribution in a uniform flow with constant diffusion coefficient and the viscous Burgers equation is used to examine the temporal reachout technique. The outcomes show that the temporal reachout technique yields much better simulation results than the first derivative endpoint constraint with higher-order central difference approximation. The effect of endpoint constraint on the time-line cubic spline interpolation can be greatly diminished by the use of the temporal reachout technique.
ON A PROBLEM ON NORMAL NUMBERS RAISED BY IGOR SHPARLINSKI
Authors: DE KONINCK JEAN-MARIE , KÁTAI IMRE
Published: June 2011

Given an integer d≥2, a d-normal number, or simply a normal number, is an irrational number whosed-ary expansion is such that any preassigned sequence, of length k≥1, taken within this expansion occurs at the expected limiting frequency, namely 1/dk. Answering questions raised by Igor Shparlinski, we show that 0.P(2)P(3)P(4)…P(n)… and 0.P(2+1)P(3+1)P(5+1)…P(p+1)…, where P(n) stands for the largest prime factor of n, are both normal numbers.
Triple manifestation of extramedullary plasmacytoma in the upper airway: an unusual clinical entity
Authors: Morariu I , Burns P , Roche P , Hone S
Published: June 2011

Objective:

We report an extremely rare case of extramedullary plasmacytoma.

Method:

Case report and review of the English-literature concerning extramedullary plasmacytoma and multiple myeloma.

Result:

We present an unusual case of multiple extramedullary plasmacytomas, which, over a protracted course of 30 years, presented on different occasions at three separate sites in the head and neck. The patient was managed surgically on all occasions, and was disease-free at the time of writing.

Conclusion:

Following review of the literature, we believe this to be the only case with this extremely unusual presentation. This case is noteworthy, not only because of the rarity of extramedullary plasmacytoma, but also because it highlights a number of important clinical issues. The diagnosis and management of extramedullary plasmacytoma require close cooperation between multiple disciplines.
Environmental and genetic pathways between early pubertal timing and dieting in adolescence: distinguishing between objective and subjective timing
Authors: Harden K. P. , Mendle J. , Kretsch N.
Published: June 2011

Background

Early pubertal timing in girls is associated with elevated risk for dieting and eating pathology. The relative importance of biologicalversussocio-environmental mechanisms in explaining this association remains unclear. Moreover, these mechanisms may differ between objective measures of pubertal development and girls' subjective perceptions of their own maturation.

Method

The sample comprised 924 sister pairs from the National Longitudinal Study of Adolescent Health. Objective pubertal timing (menarcheal age), girls' perceptions of pubertal status and timing relative to peers, dieting and disordered eating behaviors were assessed during a series of confidential in-home interviews.

Results

Behavioral genetic models indicated that common genetic influences accounted for the association between early menarcheal age and increased risk for dieting in adolescence. In contrast, girls' subjective perceptions of their timing relative to peers were associated with dieting through an environmental pathway. Overall, subjective and objective measures of pubertal timing accounted for 12% of the variance in dieting.

Conclusions

Genetic differences in menarcheal age increase risk for dieting among adolescent girls, while girls' perceptions of their maturation represent an environmentally mediated risk.
Relativistic guidance of an intense laser beam through an axially non-uniform plasma channel
Authors: Singh Arvinder , Singh Navpreet
Published: June 2011

The effect of relativistic nonlinearity on the guiding of a laser beam in a plasma channel formed by a short ionizing pulse is investigated. The plasma channel formed is axially non-uniform due to self defocusing of the prepulse. When a second delayed laser pulse propagates through the plasma channel formed by the prepulse, the competition between refraction and diffraction results into alternate convergence and divergence of the guided beam. Second-order nonlinear differential equations for the beam width parameter of the prepulse and guided pulse are derived by moment theory approach. The effect of the guided pulse intensities as well as the axial nonuniformity of the plasma channel on the propagation of the guided laser pulse has been investigated. Relativistic laser guidance up to several Rayleigh lengths is observed.
Angular Dependence of the Ion-Induced Secondary Electron Emission for He+ and Ga+ Beams
Authors: Castaldo Vincenzo , Withagen Josephus , Hagen Cornelius , Kruit Pieter , van Veldhoven Emile
Published: June 2011

In recent years, novel ion sources have been designed and developed that have enabled focused ion beam machines to go beyond their use as nano-fabrication tools. Secondary electrons are usually taken to form images, for their yield is high and strongly dependent on the surface characteristics, in terms of chemical composition and topography. In particular, the secondary electron yield varies characteristically with the angle formed by the beam and the direction normal to the sample surface in the point of impact. Knowledge of this dependence, for different ion/atom pairs, is thus the first step toward a complete understanding of the contrast mechanism in scanning ion microscopy. In this article, experimentally obtained ion-induced secondary electron yields as a function of the incidence angle of the beam on flat surfaces of Al and Cr are reported, for usual conditions in Ga+ and He+ microscopes. The curves have been compared with models and simulations, showing a good agreement for most of the angle range; deviations from the expected behavior are addressed and explanations are suggested. It appears that the maximum value of the ion-induced secondary electron yield is very similar in all the studied cases; the yield range, however, is consistently larger for helium than for gallium, which partially explains the enhanced topographical contrast of helium microscopes over the gallium focused ion beams.
A dynamic analysis of the effects on pensioners’ welfare of social security reforms
Authors: PEINADO PATRICIA , SERRANO FELIPE
Published: June 2011

The aim of this paper is to analyze the dynamic effects of the different parametric reforms oriented to reach the financial balance of public pension systems on the well-being of the retired population. Using the Spanish social security system as a case study, a duration analysis is implemented to look for a causal relationship and then estimate separately the effects of an effective retirement age delay and a replacement rate reduction as well as the combined effect of these two measures. We also estimate the effects of a delay on the reforms. We find that a change in the effective retirement age would have positive effects on the individual welfare of retired population, while a reduction of the replacement rate would diminish it. The combined effect of the two measures would finally translate into a welfare lost of the retired population. The delay on the reforms implies higher welfare loss (to the affected generations) than the analyzed reforms.
Profitability of pension contributions – evidence from real-life employment biographies
Authors: SCHRÖDER CARSTEN
Published: June 2011

Micro-econometric intra-cohort profitability analyses of pay-as-you-go (PAYG) pension contributions are rare. We use representative employment histories of German PAYG pension insurants retiring in year 2005 to examine the determinants of the profitability of contributions using nominal internal rates of return (IRR) as measure. When future nominal pension entitlements are frozen at today's level, average IRR is about three percent. It increases in beneficiaries' remaining life expectancies at retirement and in the length of non-contribution periods resulting, for example, from child care. Interestingly, IRR is decreasing in insurants' earnings capacity, indicating that the system entails an intra-cohort progressive element.