bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of vitamin E on bone turnover markers among US postmenopausal women
Authors: Hamidi Maryam S , Corey Paul N , Cheung Angela M
Published: February 2012

Increased oxidative stress and inflammation resulting from aging and declining estrogen levels can lead to increased bone loss in postmenopausal women. Alpha-tocopherol and gamma-tocopherol, the two predominant isomers of vitamin E, have antioxidant and anti-inflammatory properties, but their effects on bone metabolism have not been well studied in humans. We examined the associations between dietary and total (diet and supplements) alpha-tocopherol intake, serum alpha-tocopherol and gamma-tocopherol levels and their ratio, and bone turnover markers (BTMs) among postmenopausal women aged ≥45 years. We used cross-sectional data from the National Health and Nutrition Examination Survey 1999–2002. Multiple regression models with adjustments for relevant confounders were used to examine the associations between intake and serum levels of tocopherols, and serum bone-specific alkaline phosphatase (BAP), a biomarker of bone formation, and urinary N-telopeptides/creatinine (uNTx/Cr), a biomarker of bone resorption. The study sample included 497 postmenopausal women who were not taking estrogen, steroids, or osteoporosis medications, were free from kidney and liver disease, cancer, and rheumatoid arthritis, and were fasting >9 hours prior to examination. Participants had a mean age of 65.5 ± 0.6 years and over 45% used vitamin E (alpha-tocopherol) supplements in the past month. Vitamin E supplement users had significantly lower serum gamma-tocopherol, higher serum alpha-tocopherol levels, and higher ratio of serum alpha-tocopherol to gamma-tocopherol than nonusers. High serum gamma-tocopherol levels and low ratio of serum alpha-tocopherol to gamma-tocopherol were associated with increased BAP levels (p < 0.01 for both). There were no associations between any of the vitamin E variables and uNTx/Cr. In conclusion, we hypothesize that gamma-tocopherol may uncouple bone turnover, resulting in more bone formation than resorption. Vitamin E supplements in the form of alpha-tocopherol suppress serum gamma-tocopherol levels and may have negative effects on bone formation. Further research is needed to investigate the potential anabolic effect of gamma-tocopherol from food sources on bone. © 2012 American Society for Bone and Mineral Research.
Demonstration of osteocytic perilacunar/canalicular remodeling in mice during lactation
Authors: Qing Hai , Ardeshirpour Laleh , Divieti Pajevic Paola , Dusevich Vladimir , Jähn Katharina , Kato Shigeaki , Wysolmerski John , Bonewald Lynda F
Published: February 2012

Osteoclasts are thought to be solely responsible for the removal of bone matrix. However, we show here that osteocytes can also remove bone matrix by reversibly remodeling their perilacunar/canalicular matrix during the reproductive cycle. In contrast, no osteocytic remodeling was observed with experimental unloading despite similar degrees of bone loss. Gene array analysis of osteocytes from lactating animals revealed an elevation of genes known to be utilized by osteoclasts to remove bone, including tartrate-resistant acid phosphatase (TRAP) and cathepsin K, that returned to virgin levels upon weaning. Infusion of parathyroid hormone–related peptide (PTHrP), known to be elevated during lactation, induced TRAP activity and cathepsin K expression in osteocytes concurrent with osteocytic remodeling. Conversely, animals lacking the parathyroid hormone type 1 receptor (PTHR1) in osteocytes failed to express TRAP or cathepsin K or to remodel their osteocyte perilacunar matrix during lactation. These studies show that osteocytes remove mineralized matrix through molecular mechanisms similar to those utilized by osteoclasts. © 2012 American Society for Bone and Mineral Research.
Synthesis of 3‐(3,5‐dinitropyrazol‐4‐yl)‐4‐nitrofurazan and its salts
Authors: Sheremetev Aleksei B. , Yudin Igor L. , Palysaeva Nadezhda V. , Yu. Suponitsky Kyrill
Published: February 2012

The annulation reaction of vinamidinium salt containing nitrofurazanyl moiety at the β‐position gives access to the corresponding pyrazole. At nitration, two nitro groups were installed to the pyrazole ring. The synthesized 3‐(3,5‐dinitropyrazol‐4‐yl)‐4‐nitrofurazan13is strong NH acid and a new family energetic salts was prepared by direct neutralization with high nitrogen bases. Compound13crystallizes in the monoclinic space groupP21/c, and charaterized by high density of 1.979 g/cm3(at 100 K). J. Heterocyclic Chem., (2012).
Is apparent diffusion coefficient reliable and accurate for monitoring effects of antiangiogenic treatment in a longitudinal study?
Authors: Suh Ji‐Yeon , Cho Gyunggoo , Song Youngkyu , Lee Chang Kyung , Kang Jong Soon , Kang Moo Rim , Park Sung Bin , Kim Young Ro , Kim Jeong Kon
Published: February 2012

Purpose:

To evaluate the reliability and accuracy of the apparent diffusion coefficient (ADC) for monitoring antiangiogenic treatment in a longitudinal study.

Materials and Methods:

Tumor volume and ADC were monitored by T2‐weighted magnetic resonance imaging (MRI) and diffusion‐weighted MRI, respectively, in 18 mice with angiogenesis‐dependent tumors (U118MG) before (day 0) and after 2, 7, 14, and 21 days of administration of the antiangiogenic agent sunitinib maleate (n = 12) or vehicle (n = 6). Percent changes in tumor volume and ADC were calculated and correlations between tumor volume and ADC were evaluated.

Results:

Tumor volume and ADC showed a negative correlation at 69 of the 72 (96%) follow‐up measurements. In the 13 mice with tumor regrowth, ADC started to decrease before (27%) or at the same time (73%) as tumor regrowth. Pretreatment ADC and percent change in ADC change on days 0–2 were similar in mice with positive and negative responses to treatment (0.851 vs. 0.999, 24% vs. 16%). Percent change of ADC showed significant negative correlation with percent change in tumor volume in both the control (r = −0.69) and treated (r = −0.65) groups.

Conclusion:

Percent change in ADC is a reliable and accurate marker for monitoring the effects of antiangiogenic treatment, whereas pretreatment ADC and early changes in ADC (ie, days 0–2) are limited in predicting treatment outcome. J. Magn. Reson. Imaging 2012;35:1430–1436. © 2012 Wiley Periodicals, Inc.
Increased [3H]D‐aspartate release and changes in glutamate receptor expression in the hippocampus of the mnd mouse
Authors: Bigini Paolo , Milanese Marco , Gardoni Fabrizio , Longhi Annalisa , Bonifacino Tiziana , Barbera Sara , Fumagalli Elena , Di Luca Monica , Mennini Tiziana , Bonanno Giambattista
Published: February 2012

Neuronal ceroid lipofuscinoses (NCLs) are a group of hereditary childhood diseases characterized mainly by lipopigment accumulation and a multisystemic pattern of symptoms including mental retardation, seizures, motor impairment, and blindness. The mnd mouse, carrying a mutation in the Cln8 gene, has been proposed as a model of epilepsy with mental retardation (EPMR, ornorthern epilepsy). We recently showed neuronal hyperexcitability and seizure hypersusceptibility in mnd mice. To elucidate the cellular mechanisms related to hippocampal hyperexcitability, the glutamatergic transmission and the expression of postsynaptic glutamate receptors were investigated in hippocampus. A significant increase in either spontaneous or KCl‐stimulated overflow of [3H]D‐aspartate was found in mnd mice compared with controls. This increase was maintained after DL‐threo‐β‐benzyloxyaspartic acid (TBOA) treatment, suggesting a nonrelevant role for transporter‐mediated release and supporting the involvement of exocytotic [3H]D‐aspartate release. Accordingly, Ca2+‐dependent overflow induced by ionomycin was also increased in mnd mice. Levels of glutamate 1–3 AMPA receptor subunits were increased, and levels of the NR2A NMDA receptor subunit were decreased in the hippocampus of mnd mice, suggesting an adaptive response to glutamate overstimulation. © 2012 Wiley Periodicals, Inc.
Effect of long‐term betaine supplementation on chemical and physical characteristics of three muscles from the Alentejano pig
Authors: Martins José M , Neves José A , Freitas Amadeu , Tirapicos José L
Published: February 2012

BACKGROUND: The use of betaine as a dietary supplement to reduce fat deposition and increase lean muscle mass in pigs is increasing. However, there is no available information on its effect on the physical and chemical (i.e. fatty acid (FA) profile) characteristics of pork.

RESULTS: The effects of long‐term betaine intake (1 g betaine kg−1 diet for 20 weeks) on the chemical and physical characteristics of Musculus longissimus dorsi, M. biceps femoris and M. semimembranosus from the Alentejano pig were investigated. The contents of total protein, intramuscular lipids (neutral and polar), myoglobin and total collagen as well as the water‐holding capacity, physical colour characteristics and FA profile of the three muscles were determined. With the exception of a significant increase in the intramuscular lipid content of M. longissimus dorsi and M. biceps femoris, betaine supplementation did not influence muscle chemical and colour characteristics or body fat deposition.

CONCLUSION: These data suggest that long‐term betaine supplementation selectively increases intramuscular lipid deposition (a trait related to meat quality) while not affecting other chemical (including the atheroprotective FA profile) and physical characteristics of the Alentejano pig muscles studied. Copyright © 2012 Society of Chemical Industry
Growth and mineral acquisition response of grapevine rootstocks (Vitis spp.) to inoculation with different strains of plant growth‐promoting rhizobacteria (PGPR)
Authors: Sabir Ali , Yazici M Atilla , Kara Zeki , Sahin Fikrettin
Published: February 2012

BACKGROUND: Effects of the plant growth‐promoting rhizobacteria (PGPR) strains Burkholderia gladii BA‐7, Bacillus subtilis OSU‐142, Bacillus megatorium M‐3 and Azospirillum brasilense Sp 245 on vegetative development and mineral uptake of 1103 P and 41 B grapevine rootstocks were investigated. The roots of nursery plants of the grapevine rootstocks were immersed in bacterial solutions and transplanted to a sterilised peat and perlite mixture in 5 L pots. Plants were cultivated in a semi‐controlled glasshouse during the vegetation period.

RESULTS: Vegetative development of grapevine rootstocks was obviously promoted by bacterial inoculation, with the maximum increase induced by Sp 245. Inoculation with Sp 245 also significantly improved the chlorophyll concentrations of the leaves of the two rootstocks. Among the bacteria, OSU‐142 also significantly stimulated vegetative development and mineral acquisition of the plants. Nutrient contents of the leaf blades of the plants were generally higher than those of control plants.

CONCLUSION: Overall investigations revealed that A. brasilense Sp 245 and B. subtilis OSU‐142 performed more efficiently than the other strains. Therefore these bacteria seem to have considerable potential in reducing the need for inorganic fertiliser. Copyright © 2012 Society of Chemical Industry
Factors influencing survival in patients undergoing palliative bypass for pancreatic adenocarcinoma
Authors: Gray Phillip J. , Wang Jingya , Pawlik Timothy M. , Edil Barish H. , Schulick Richard , Hruban Ralph H. , Dao Harry , Cameron John , Wolfgang Christopher , Herman Joseph M.
Published: February 2012

Purpose

The purpose of this study is to identify factors predictive of early mortality following palliative bypass in patients with previously unsuspected advanced pancreatic adenocarcinoma to provide a basis for the selection of appropriate therapies.

Methods

All patients with pancreatic adenocarcinoma who underwent a bypass procedure at our institution between 9/30/1994 and 1/31/2006 were reviewed. Patients with peri‐operative mortality were excluded from the analysis. Univariate analysis was performed on peri‐operative data to identify factors associated with early mortality (death within 6 months of surgery). Patients having multiple risk factors were assigned an overall prognostic score based on the sum of these factors.

Results

Of the 397 patients with pancreatic adenocarcinoma analyzed, four factors were found to predict early mortality following palliative bypass: Presence of distant metastatic disease (HR 2.59, P < 0.0001), poor tumor differentiation (HR 1.71, P = 0.009), severe pre‐operative nausea and vomiting (HR 1.48, P = 0.013), and lack of previous placement of a biliary stent (HR 1.36, P = 0.048). Patients with a prognostic score of 0 were significantly more likely to survive past 6 months than patients with a prognostic score of 1 (HR 2.71, P < 0.0001), 2 (HR 3.70, P < 0.0001), or ≥3 (HR 5.63, P < 0.0001).

Conclusions

In a cohort of patients undergoing a palliative bypass procedure, specific peri‐operative factors can be used to identify patients who are at risk of early mortality. These factors may be helpful in selecting appropriate interventions for this group of patients. J. Surg. Oncol. 2012; 106:66–71. © 2012 Wiley Periodicals, Inc.
From anti‐Stokes photoluminescence to resonant Raman scattering in GaN single crystals and GaN‐based heterostructures
Authors: Ding Y.J. , Khurgin J.B.
Published: February 2012

The progress on anti‐Stokes photoluminescence and Stokes and anti‐Stokes Raman scattering in GaN single crystals and GaN/AlN heterostructures is reviewed. Anti‐Stokes photoluminescence investigated in the past was primarily attributed to two‐photon absorption, three‐photon absorption, and phonon‐assisted absorption. On the other hand, anti‐Stokes Raman scattering was used to determine electron‐phonon scattering time and decay time constant for longitudinal‐optical phonons. In a typical high electron mobility transistor based on GaN/AlN heterostructures, strong resonances were reached for first‐order and second‐order Raman scattering processes. Therefore, both Stokes and anti‐Stokes Raman intensities were dramatically enhanced. The feasibility of laser cooling of a nitride structure has been demonstrated. Anti‐Stokes photoluminescence and Raman scattering have potential applications in upconversion lasers and laser cooling of nitride ultrafast electronic and optoelectronic devices.
Preparation of Responsive Micrometer‐Sized Microgel Particles with a Highly Functionalized Shell
Authors: Li Zifu , Kwok Man‐Hin , Ngai To
Published: February 2012

We describe a facile approach for the synthesis of micrometer‐sized (∼3.5 μm), pH‐responsive microgel particles, which have functional carboxylic acid groups concentrated in the shell. The large size offers the possibility to directly study the interactions between individual, isolated microgel particles with active ingredients by optical microscopy. Our results show that the synthesized microgel particles can load and release active ingredients via changing pH values. The complexation of Ca2+ with the ‐COOH functional groups located at the microgel surfaces not only regulates the active ingredient's uptake efficiency, but also provides a novel way to reveal the spatial distribution of the functional groups inside the microgel particles.
Nonrigid motion correction in 3D using autofocusing withlocalized linear translations
Authors: Cheng Joseph Y. , Alley Marcus T. , Cunningham Charles H. , Vasanawala Shreyas S. , Pauly John M. , Lustig Michael
Published: February 2012

MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from nonrigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online reconstruction. On a sufficiently small spatial scale, the different types of motion can be well approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric — more specifically, the proposed localized gradient‐entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to the motion measured from multichannel navigator data. The novel navigation strategy is based on the so‐called “Butterfly” navigators, which are modifications of the spin‐warp sequence that provides intrinsic translational motion information with negligible overhead. With a 32‐channel abdominal coil, sufficient number of motion measurements were found to approximate possible linear motion paths for every image voxel. The correction scheme was applied to free‐breathing abdominal patient studies. In these scans, a reduction in artifacts from complex, nonrigid motion was observed. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Thiol‐ene/clay nanocomposite thin film as novel transparent barrier
Authors: Bae Joonwon
Published: February 2012

Thiol‐ene/clay (TE/clay) nanocomposite thin films were prepared by a simple photocuring process for use as transparent barrier films. In this work, tetrafunctional thiol and triene monomer were employed and organic clay surface modified with octadecylamine was mixed by sonication and a mechanical method as a reinforcing filler. The successful formation of the TE structure was confirmed by differential scanning calorimetry and X‐ray diffraction. The homogeneous dispersion (intercalation and exfoliation) of clay into the TE polymer matrix was observed with transmission electron microscopy. Atomic force microscopy images displayed the surface properties of the TE/clay nanocomposite thin films. The thermal expansion behavior of the resulting hybrid film was monitored by thermomechanical analysis. In addition, gas permeation properties as well as light transmittance of the TE/clay films were measured for potential applications in various fields as dimensionally stable films under heating and as a transparent barrier. Copyright © 2012 Society of Chemical Industry
Towards ultrathin copper indium gallium diselenide solar cells: proof of concept study by chemical etching and gold back contact engineering
Authors: Li‐Kao Zacharie Jehl , Naghavi Negar , Erfurth Felix , Guillemoles Jean François , Gérard Isabelle , Etcheberry Arnaud , Pelouard Jean Luc , Collin Stephane , Voorwinden Georg , Lincot Daniel
Published: February 2012

An innovative approach combining chemical etching and a “lift‐off” process, which allows back contact processing after CIGSe deposition, permitted to use Au as a highly reflective back contact in ultrathin CIGSe solar cells. The Au back contact does not degrade the other parameters of the cell, as good ohmicity on CIGSe is achieved. An important photocurrent increase compared with regular Mo back contact solar cells is achieved by the enhanced light trapping effect due to the back reflector, leading to an absolute efficiency increase of +2.5% for a CIGSe thickness of 0.4 µm. This approach could be used for further investigations in improving the back side of ultrathin CIGSe solar cells. Copyright © 2012 John Wiley & Sons, Ltd.
Large electro‐optic activity and enhanced temporal stability of methacrylate‐based crosslinking hyperbranched nonlinear optical polymer
Authors: Mori Yuichi , Nakaya Kosei , Piao Xianqing , Yamamoto Kazuhiro , Otomo Akira , Yokoyama Shiyoshi
Published: February 2012

A methacrylate‐based crosslinking hyperbranced polymers have been synthesized through initiator‐fragment incorporation radical polymerization and used for the temperature stable electro‐optic (EO) polymer application. This polymer consists of methyl methacrylate, 2‐metacryloxyethyl isocyanate, and ethylene glycol dimethacrylate (EGDMA) monomers. The use of EGDMA as a bifunctional unit resulted in the solvent‐soluble crosslinking hyperbranched chain, so that the EO polymer enhanced glass transition temperatures. A phenyl vinylene thiophene vinylene bridge nonlinear optical chromophore was attached to the polymer backbone as the side‐chain by a post‐functionalization reaction. The loading concentration of the chromophore was varied between 30 and 50 wt % by simply changing the mixing ratio of the precursor polymer to the chromophore. The synthesized EO polymers produced optical quality films with a light propagation loss of 0.61 dB/cm in a slab waveguide at 1.31 μm. The electrically poled film had an EO coefficient (r33) of 139 pm/V at 1.31 μm. The EO crosslinking hyperbranced polymer had a high‐glass transition temperature of 170 °C, and exhibited excellent temporal stability of the EO activity at 85 °C for 500 h. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Assessing health‐related quality of life of Chinese‐American breast cancer survivors: a measurement validation study
Authors: Ashing‐Giwa Kimlin , Lam Chun Nok , Xie Bin
Published: February 2012

Background

This study reports on the internal consistency and construct validity of the Functional Assessment of Cancer Therapy – General (FACT‐G v.4) and 12‐item Short Form Health Survey (SF‐12 v.2) health‐related quality of life (HRQOL) instruments with Chinese‐American breast cancer survivors (BCS).

Methods

Participants completed mailed questionnaires at baseline and 12‐month follow‐up. HRQOL was measured using the FACT‐G and the SF‐12. The measures were evaluated by construct validity and reliability tests. Factor analyses were performed in a two‐wave assessment through exploratory and confirmatory analyses at baseline and follow‐up.

Results

Seventy‐four Chinese‐American BCS participated. Excellent internal consistency (α > 0.85) and good construct validity for the FACT‐G (five factors) and the SF‐12 (two factors) were observed. Factor structure of both measures accounted for 70% of the common variance in physical, social/family, emotional, and functional well‐being subscales for the FACT‐G and in physical and mental components for the SF‐12.

Conclusions

Our data demonstrated good internal consistency and construct validity of the measures. The psychometric findings demonstrate the utility of the FACT‐G and the SF‐12 to assess HRQOL among Chinese‐American BCS. Copyright © 2012 John Wiley & Sons, Ltd.
Holographic quark‐gluon plasmas at finite quark density
Authors: Bigazzi F. , Cotrone A. , Mas J. , Tarrio J. , Mayerson D.
Published: February 2012

Gravity solutions holographically dual to strongly coupled Quark‐Gluon Plasmas with non‐zero quark density are reviewed. They are motivated by the urgency of finding novel tools to explore the phase diagram of QCD‐like theories at finite chemical potential. After presenting the solutions and their regime of validity, some of their physical properties are discussed.
A joint effect of new western diet and retinoid X receptor alpha prostate‐specific knockout with development of high‐grade prostatic intraepithelial neoplasia in mice—A preliminary study
Authors: Mao Gloria E. , Harris Diane M. , Moro Aune , Heber David , Roy‐Burman Pradip , Zhang Zuo‐Feng , Rao Jianyu
Published: February 2012

BACKGROUND

The “New Western‐style Diet” (NWD) characterized by high in fat and low in fiber, vitamin D, calcium, and methyl donors—are considered as a risk factor for prostate cancer. Previous studies have shown that premalignant lesions of human prostate have decreased expression of the Retinoid X Receptor alpha (RXRα). This study was to determine the effect of diet in RXRα knockout mice in developing high‐grade prostate intraepithelial neoplasia (mPIN).

METHODS

Male mice (n = 54) with or without the RXRα prostate null mutation were fed either NWD or AIN‐76A control diet for 10 months; prostates were harvested at 11 months of age and examined for prostate mPIN.

RESULTS

mPIN was seen in 79% of RXRα prostate null mice fed NWD (n = 19), 30.8% RXRα prostate null mice fed AIN‐76A (n = 13), 42.9% RXRα wild‐type mice fed NWD (n = 14), and 12.5% RXRα wild‐type mice fed AIN‐76A (n = 8). Unconditional Logistic analysis showed a significant joint effect of NWD and RXRα status in developing mPIN 26.3 (95% CI: 2.5–280), but interaction was not significant owing to the small sample size 1.6 (0.09–27.7, P = 0.7441).

CONCLUSION

This study provides preliminary data to support a joint RXRα‐diet effect in prostate carcinogenesis. Prostate 72:1052–1059, 2012. © 2012 Wiley Periodicals, Inc.
Interactions between the root pathogen Rhizoctonia solani AG‐8 and acetolactate‐synthase‐inhibiting herbicides in barley
Authors: Lee Hyejin , Ullrich Steven E , Burke Ian C , Yenish Joseph , Paulitz Timothy C
Published: February 2012

BACKGROUND: The widespread acceptance of reduced‐tillage farming in cereal cropping systems in the Pacific Northwest of the United States has resulted in increased use of herbicides for weed control. However, soil residual concentrations of widely used imidazalone herbicides limit the cultivation of barley, which is more sensitive than wheat. In addition, increased severity of the root rot disease caused by Rhizoctonia solani is associated with reduction in tillage. Many crops exhibit altered disease responses after application of registered herbicides. In this study, the injury symptoms in barley caused by sublethal rates of two acetolactate synthase (ALS)‐inhibiting herbicides, imazamox and propoxycarbazone‐sodium, were assessed in factorial combinations with a range of inoculum concentrations of the root rot pathogen Rhizoctonia solani AG‐8.

RESULTS: Both herbicides and pathogen had negative impacts on plant growth parameters such as root and shoot dry weight, shoot height and first leaf length, and interactions between pathogen and herbicide were detected.

CONCLUSIONS: The results suggested that sublethal rates of herbicides and R. solani could alter severity of injury symptoms, possibly owing to the herbicide predisposing the plant to the pathogen. Copyright © 2012 Society of Chemical Industry
Raman scattering characterization of ZnSe/Zn0.6Cd0.4Se multilayers prepared by thermal vacuum evaporation
Authors: Nesheva Diana , Šćepanović Maja , Aneva Zdravka , Levi Zelma , Popović Zoran V. , Miloushev Ilko
Published: February 2012

Nanocrystalline multilayers from ZnSe/Zn0.6Cd0.4Se with three different layer thicknesses (3.5, 5.0, 10.0 nm) and, for comparison, 400 nm thick Zn0.6Cd0.4Se nanocrystalline single layers have been prepared by thermal evaporation of ZnSe and CdSe in vacuum. Raman scattering spectra have been measured in the range 100–1000 cm−1 under excitation with the 488 and 514.5 nm lines of an Ar+ laser. Series of four bands have been seen in the spectra of all samples. They have been related to replicas of the longitudinal optical LO‐phonon in the ZnxCd1−xSe layers and interpreted as an indication for crystallinity of both kinds of samples. A blue shift of the 1 LO maximum has been observed, which has been connected with an increase of the compressive stress in the ternary layers when the layer thickness decreases. It has also been obtained that the ratio of the integrated intensity of the 1 LO band in the spectra taken with the 488 and 514.5 nm lines decreases with decreasing Zn0.6Cd0.4Se layer thickness. The result has been assigned to size‐induced increase of the optical band gap of the layers. This conclusion has been confirmed by spectral photocurrent and optical transmission measurements.
Properties of ultraviolet anti‐Stokes photoluminescence in ZnO single crystals
Authors: Fujii Katsushi , Goto Takenari , Yao Takafumi
Published: February 2012

Ultraviolet (UV) anti‐Stokes photoluminescence (ASPL) was observed in ZnO single crystals at low temperature. The ASPL spectrum was essentially the same as the normal photoluminescence (PL) spectrum under excitation in the band to band transition. By analogy to the ASPL of GaN, a two‐step two‐photon absorption process is suggested to occur in ZnO. The ratio of re‐excited electrons in the intermediate state is, however, smaller than that for GaN from the excitation intensity dependence of the ASPL. This difference is probably due to the carrier lifetime of the intermediate state for ZnO being shorter than that for GaN.
Optical parametric oscillaton in 1D semiconductor microcavities
Authors: Ardizzone Vincenzo , Abbarchi Marco , Lecomte Timothee , Lemaitre Aristide , Sagnes Isabelle , Senellart Pascale , Bloch Jacqueline , Roussignol Philippe , Tignon Jerome
Published: February 2012

We present an experimental investigation of parametric scattering processes and optical parametric oscillations in wire shaped, one‐dimensional semiconductor microcavities. Far field emission patterns and corresponding band dispersion are studied by polarization resolved measurements and power dependence measurements under resonant and non‐resonant excitation. The multiplicity of the photonic bands allows for an efficient engineering of interbranch parametric scattering processes. We demonstrate the onset of optical parametric oscillation of perfectly balanced twin beams, degenerate in energy and split in momentum space.
Carrier dynamics in active regions for ultraviolet optoelectronics grown on thick, relaxed AlGaN on semipolar bulk GaN
Authors: Garrett Gregory A. , Rotella Paul , Shen Hongen , Wraback Michael , Haeger Daniel A. , Chung Roy B. , Pfaff Nathan , Young Erin C. , DenBaars Steven P. , Speck James S. , Cohen Daniel A.
Published: February 2012

Active regions for mid‐ultraviolet laser diodes grown on bulk AlGaN templates are investigated by time‐resolved photoluminescence. The active regions were grown pseudomorphically on thick, relaxed AlGaN on bulk GaN in the semi‐polar ($20{\bar {2}}1$) orientation where it has been shown that the glide of dislocations create strain relieving defects confined to the AlGaN/GaN interface, away from the active region. The photoluminescence lifetimes were found to have mono‐exponential decays of around 500 ps and calculated radiative and non‐radiative lifetimes are compared to previously reported results for active regions on bulk m‐plane GaN.
Electron scattering on the short‐range potential of crystal lattice defects in gallium nitride
Authors: Malyk Orest
Published: February 2012

The processes of the charge carrier scattering on the short‐range potential caused by interaction with polar and nonpolar optical phonons, piezoelectric and acoustic phonons, static strain, neutral and ionized impurities in wurtzite n‐GaN with impurity concentration 4×1016–2×1019 cm‐3 are considered. The temperature dependences of electron mobility in the range 40–500 K are calculated. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma‐assisted electroepitaxy as a novel method for the growth of GaN layers
Authors: Novikov S. V. , Staddon C. R. , Powell R. E. L. , Akimov A. V. , Kent A. J. , Foxon C. T.
Published: February 2012

In the current study we have demonstrated the feasibility of a novel approach for the growth of GaN layers, namely plasma‐assisted electroepitaxy (PAEE). In this method, we have combined the advantages of the plasma process for producing high concentrations of active N species in the Ga melt with the advantages of electroepitaxy in transferring the N species from the Ga surface to the growth interface, without spontaneous crystallisation on the surface or within the solution. We have designed and built a new growth chamber which allows us to combine the plasma‐assisted molecular beam epitaxy process with a liquid phase electroepitaxy system. We have demonstrated that it is possible to grow GaN layers by PAEE at growth temperatures as low as ∼650 oC and with low nitrogen overpressures of ∼3×10‐5 Torr. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Normally‐off AlGaN/GaN power tunnel‐junction FETs
Authors: Chen Hongwei , Yuan Li , Zhou Qi , Zhou Chunhua , Chen Kevin J.
Published: February 2012

We present normally‐off AlGaN/Gan power tunnel‐junction FETs (TJ‐FETs) with high breakdown voltage, low off‐state leakage current and low specific on‐resistance. The TJ‐FETs exhibit normally‐off operation in an otherwise normally‐on as‐grown sample owing to a current controlling scheme different from the conventional FETs. The high 2DEG density in AlGaN/GaN heterostructure results in a thin tunnel barrier whose effective thickness is controlled by an overlaying gate electrode. This tunnel junction is controlled by an overlapping gate and deliver highly efficient quantum tunnelling, enabling normally‐off operation. A positive gate bias results in a nanometer‐thick barrier with high tunnelling current, while a zero gate bias leads to a thicker barrier that effectively blocks the current flow. High tunnel current (326 mA/mm), low off‐state leakage (10‐8 mA/mm) and high off‐state breakdown voltage (557 V) are obtained on a standard GaN‐on‐Si platform featuring a 1.8 μm buffer. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High nitrogen pressure solution growth of GaN in multi feed‐seed configuration
Authors: Bockowski M. , Lucznik B. , Sochacki T. , Sadovyi B. , Nowak G. , Litwin‐Staszewska E. , Grzegory I.
Published: February 2012

The results of High Nitrogen Pressure Solution (HNPS) growth of GaN in multi feed‐seed (MFS) configuration are presented. The idea of this configuration is based on the conversion of the free standing HVPE‐GaN crystals (seeds) to the free standing HNPS‐GaN of much higher quality than the seeds. A new arrangement of the seeds in the MFS configuration is shown. The influence of the experimental conditions (i.e. growth temperature, temperature gradient) on the growth rate, growth mode and electrical properties of HNPS‐GaN is presented. The regrowth procedure is introduced in order to increase the lattice bowing radii of the HNPS‐GaN crystals and finally obtain crystalographically flat (bowing radius of 30 meters) pressure grown GaN substrates (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical studies of quantum dot‐like emission from localisation centres in InGaN/GaN nanorod array LEDs
Authors: Chan Christopher C. S. , Shields Philip A. , Holmes Mark J. , Zhuang YiDing , Wang Xu , Reid Benjamin P. L. , Kim HeeDae , Allsopp Duncan W. E. , Taylor Robert A.
Published: February 2012

Microphotoluminescence with one‐photon and two‐photon excitation has been employed to investigate localisation centres found in nanorod array LEDs. Quantum dot‐like features with spectral width less than 1 meV were observed originating from low dimensional carrier confinement within the nanorods. Two‐photon excitation was used to probe the individual localisation centres. The narrow peak PL energy does not shift with increasing excitation density, but rather an increase of discrete new peaks on the high energy side of the spectrum is observed. There is no temperature dependent emission energy shift observed from 4.3 K to 25 K. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase diagram on phase purity of InN grown pressurized‐reactor MOVPE
Authors: Kimura Takeshi , Prasertsuk Kiattiwut , Zhang Yuantao , Liu Yuhuai , Hanada Takashi , Katayama Ryuji , Matsuoka Takashi
Published: February 2012

InN epitaxial films are directly grown on sapphire (0001) substrates by using Pressurised‐Reactor metalorganic vapour phase epitaxy (PR‐MOVPE) system originally developed by ourselves. This system makes it possible to control the side wall of islands perpendicular to the substrate surface, which is important in the heteroepitaxial growth with large lattice‐mismatch from the analogy of the GaN growth on sapphire substrates. This high pressure also leads to the growth at the higher temperature than that at the atmospheric pressure. In this paper, InN films are grown by PR‐MOVPE at 2,400 Torr. Its polarity is nitrogen one, which has the superior efficiency to indium polarity in the capture of nitrogen at the growth front. To crystallographically identify films using the diffractions from sapphire (006), wurtzite (WZ) InN (002), zincblende (ZB) InN (111) and metallic indium (101), 2θ–ω scans and the pole figure measurements in X‐ray diffraction are measured. From the pole figure measurements, the orientation and crystalline phases of grains in crystals are determined. The phase diagram between trimethylindium as an indium source flow rate and the growth temperature is drawn. The regions with pure WZ InN and with the incorporation of ZB phase and the metallic indium into WZ phase and the metal‐indium are observed. It is also observed that the grains with WZ phase have c‐axis normal to the (111) plane at the side wall of the ZB grains. Finally, the growth conditions for pure WZ InN make it clear by using PR‐MOVPE. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement‐mode m ‐plane AlGaN/GaN HFETs with regrown n+‐GaN contact layer
Authors: Fujiwara Tetsuya , Keller Stacia , Speck James S. , DenBaars Steven P. , Mishra Umesh K.
Published: February 2012

High performance enhancement‐mode m ‐plane AlGaN/GaN heterojunction field‐effect transistors were reported in this letter. +3 V threshold voltages, 230 mA/mm of maximum drain‐source current (Ids(max)), and 58 mS/mm of maximum transconductance (gm(max)) were obtained. High Ids(max) and gm(max) were due to the regrown n+‐GaN contact layer. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anti‐corrosive stainless steel separator coated with MOCVD InGaN for polymer electrolyte fuel cell (PEFC)
Authors: Shimahashi M. , Matsui K. , Okada K. , Sugita K. , Sasaki H. , Yamamoto A.
Published: February 2012

This paper reports the application of InGaN films to a polymer electrolyte cells (PEFC) stainless steel (SS) separator for the first time. Using MOCVD, InGaN films with In content of 0‐1 are grown at 600 °C on sapphire and stainless steel substrates. Sputtered TiN is used as a buffer for the InGaN growth on stainless steel. For InGaN on sapphire substrates, electrical resistivity and dissolution rate in a H2SO4 solution at 60 °C are measured, and films with In content in the range 0.2‐0.5 are found to have both high electric conductivity and high corrosion resistance. The anti‐corrosive properties of In0.3Ga0.7N/TiN/SS structures are also confirmed by the inductively coupled plasma spectrometry (ICP) chemical analysis of the H2SO4 solution in which the In0.3Ga0.7N/TiN/SS samples are dipped for 100 h. The levels of both Ga and In atoms are under the detection limits. The I‐V characteristics of a single cell using an In0.3Ga0.7N/TiN/SS separator is measured in comparison with those using bare stainless steel or carbon separators. The performance of the cell with the In0.3Ga0.7N/TiN/SS separator is much superior to that with a bare stainless steel. Compared with the cell using the carbon separator, the cell using the In0.3Ga0.7N/TiN/SS separator has a little larger ohmic loss (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the role of tuning in parametrizations of unresolved diffusive processes in atmospheric models
Authors: Termonia P. , Smet G. , Van den Bergh J.
Published: February 2012

This article addresses the role of the tuning of the parameters of the subgrid parametrizations of diffusive processes in numerical models. To this end, it examines the stability and accuracy of a set of fractional time‐split integration schemes for the nonlinear diffusion equation. The best values of the time‐decentring parameters are established. The dependency of the diffusion on the exchange coefficient is tuned to get the most accurate simulation of the steady‐state solution and this is then tested in a non‐steady‐state model integration. The following questions are then addressed: (i) what is the relative role of parameter ‘tuning’ compared to the choice of the numerical scheme? and (ii) what is the effect of using a parametrization in one model that has been tuned in another model?

The presented tests suggest that the best results are obtained by controlling the details of the numerics while taking the physical value of the exchange coefficient, instead of tuning the physics parametrization. This suggests that it is beneficial to consider ‘tuning’ the physics parametrization schemes via the freedom in the numerics as an alternative to tuning the parameters of the physical processes. Copyright © 2012 Royal Meteorological Society
Federated‐filter‐based unmanned ground vehicle localization using 3D range registration with digital elevation model in outdoor environments
Authors: Choi Ji‐Hoon , Park Yong‐Woon , Kim Jun , Choe Tok‐Sun , Song Jae‐Bok
Published: February 2012

An integrated GPS/INS does not guarantee localization robustness in outdoor environments, because GPS is vulnerable to external disturbances. However, a digital elevation model (DEM) contains 3D data on the terrain over a specified area and hence can provide in‐depth localization information during GPS blockage. This paper proposes federated‐filter‐based localization using three‐dimensional (3D) range registration with a DEM. A no‐reset‐feedback method is used and a 3D LIDAR sensor, magnetic compass, and odometer are used to correct INS errors in GPS blockage. For 3D range registration with DEM, this paper presents a framework based on the weighted registration scheme of two transformations, pairwise registration and registration with DEM, with the INS position and attitude information. The transformation is first determined by comparing the results of two registration methods with the INS position and is then modified to replace the orientation result of 3D registration with the INS attitude. A multilayered DEM approach using the height of the integrated system is also used to constrain the search range of DEM into three layers near the current unmanned ground vehicle (UGV) position when the corresponding point is searched for in the DEM. Experimental results show that the proposed localization algorithm can greatly enhance the robustness and accuracy of UGV localization in outdoor environments. © 2012 Wiley Periodicals, Inc.
Vapour‐mediated ion activation for enhanced SIMS imaging
Authors: Vaidyanathan Seetharaman , Salim Malinda , Hurley Claire , Pugh John
Published: February 2012

The success of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) imaging is dependent on effective sputtering and ionisation of analytes from the sample surface imaged. Although there have been significant advances in SIMS analysis, thanks to the advent of cluster ion beams, this has largely been in the sputtering process. Ionisation is still largely ineffective, and improvements in this direction would significantly enhance SIMS imaging. We are specifically interested in improving the capabilities of SIMS imaging for detecting metabolites (small molecular weight components of metabolism) in biological cells and tissues. Here, we report a method to enhance the signal intensities of diagnostic ions and improve SIMS imaging of metabolites using a vapour‐mediated ion activation approach. Exposure of a synthetic cocktail of metabolites to ammonia vapour showed a greater than threefold increase in the deprotonated ion signals for some of the metabolites in the cocktail. However, room temperature exposure resulted in changes to the sample morphology, indicating that the sample surface was disrupted. It was possible to increase the ion yield and retain the sample morphology when the treatment was carried out at 4 °C. Application of the methodology to a plant tissue section showed the detection of signals that were not observed in the samples that were not treated. This is a promising approach that can be applied to enhance the detection of diagnostic ions for the ToF‐SIMS analysis of organic and biological samples. Copyright © 2012 John Wiley & Sons, Ltd.
Zur Entwicklung und zum Einsatz des Liquid‐V‐Dampers zur Tilgung von vertikalen Brückenschwingungen
Authors: Kuss Stefan , Fink Josef
Published: February 2012

In jüngster Zeit gewinnt die Kenntnis über das dynamische Verhalten von Bauwerken immer mehr an Bedeutung. Dies trifft insbesondere auf Brücken zu, die durch den Einsatz von hochfesten Materialien sowie komplexen Computerprogrammen schlanker und leichter denn je geplant und gebaut werden können. Dadurch wird die Berücksichtigung dynamischer Kriterien in der Planung und Bauwerksüberwachung unumgänglich. Eine Möglichkeit der Minimierung der auftretenden Schwingungen ist die Anordnung von Schwingungsdämpfern am Tragwerk, die bis dato hauptsächlich in der Form des Masse‐Feder‐Dämpfer‐Systems realisiert wurden. In diesem zweiteiligen Bericht soll der alternative Einsatz von Flüssigkeitsschwingungstilgern mit V‐Form (Liquid‐V‐Damper) gegen vertikale Brückenschwingungen, speziell für den Einsatz bei Fachwerkbrücken, dargestellt werden. Dabei wurde der Schwerpunkt im bereits veröffentlichten ersten Teil des Beitrags [1] auf die mechanische Wirkungsweise gelegt. Der vorliegende zweite Teil beschäftigt sich mit den zugehörigen Großversuchen sowie der praktischen Anwendung der Tilger. Auf die baupraktische Einsatzmöglichkeit der Liquid‐V‐Damper wird dabei besonderes Augenmerk gelegt.

Development and use of the Liquid‐V‐Damper against vertical bridge vibrations. Part 2 – Practical application and tests. Nowadays the acknowledgment of the dynamical behavior of structures, in special for bridges, becomes more important because of the use of high strength materials and complex computer simulations. Due to that reasons these structures can be planed and build more slender and light weighted than ever. So the consideration of dynamical effects in the planning phase and the structure monitoring is indispensable. One possible method to reduce structural vibrations is the arrangement of dampers on the structure. The common type of dampers is the mass‐spring damper. In this two‐part paper the alternative use of tuned liquid column damper (Liquid‐V‐Damper) against vertical bridge vibrations, in special designed for truss bridges is presented. The already published first part of the paper concerns with the mechanical mode of operation, the available second part presents the corresponding testing series and the optimal tuning of the damper. Special attention is paid to the practical use of the Liquid‐V‐Damper.
Prospective risk of late stillbirth in monochorionic twins: a regional cohort study
Authors: OBSTETRIC RESEARCH COLLABORATIVE (STORK) SOUTHWEST THAMES
Published: February 2012

Objective

Monochorionic (MC) pregnancies are routinely delivered electively at late preterm gestation with the aim of avoiding stillbirth at term. The aim of this study was to evaluate the prospective risk of late stillbirth in a large regional cohort of twin pregnancies of known chorionicity.

Methods

This was a retrospective study of all twin pregnancy births of known chorionicity between 2000 and 2009 from a large regional cohort consisting of nine hospitals. Prospective risk was calculated per 1000 fetuses rather than pregnancies, as each twin pregnancy had two gestations at risk of stillbirth.

Results

A total of 3005 twin pregnancies delivered after 26 weeks' gestation in the Southwest Thames Obstetric Research Collaborative. The total risk of stillbirth after 26 weeks in MC twins (19.1 per 1000 fetuses) was significantly higher than in dichorionic (DC) twins (6.5 per 1000 fetuses), with an odds ratio (OR) of 2.97 (95% CI, 1.71–5.18). The risk of stillbirth in MC twins did not change significantly between 26 weeks (1.8 per 1000 fetuses) and 36 weeks (3.4 per 1000 fetuses), with an OR of 1.85 (95% CI, 0.3–13.2). The equivalent figures for DC twins were 0.6 per 1000 fetuses and 2.1 per 1000 fetuses, respectively (OR, 3.4 (95% CI, 0.9–13.2)).

Conclusions

The risk of stillbirth in MC twins does not appear to increase significantly near term. This may be due to a policy of routine surveillance and elective delivery from 36 weeks. The data do not support a policy of elective delivery before 36 weeks' gestation in MC pregnancies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.