bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnesium alloys: Predicting in vivo corrosion with in vitro immersion testing
Authors: Walker Jemimah , Shadanbaz Shaylin , Kirkland Nicholas T. , Stace Edward , Woodfield Tim , Staiger Mark P. , Dias George J.
Published: February 2012

Magnesium (Mg) and its alloys have been proposed as degradable replacements to commonly used orthopedic biomaterials such as titanium alloys and stainless steel. However, the corrosion of Mg in a physiological environment remains a difficult characteristic to accurately assess with in vitro methods. The aim of this study was to identify a simple in vitro immersion test that could provide corrosion rates similar to those observed in vivo. Pure Mg and five alloys (AZ31, Mg‐0.8Ca, Mg‐1Zn, Mg‐1Mn, Mg‐1.34Ca‐3Zn) were immersed in either Earle's balanced salt solution (EBSS), minimum essential medium (MEM), or MEM‐containing 40 g/L bovine serum albumin (MEMp) for 7, 14, or 21 days before removal and assessment of corrosion by weight loss. This in vitro data was compared to in vivo corrosion rates of the same materials implanted in a subcutaneous environment in Lewis rats for equivalent time points. The results suggested that, for the alloys investigated, the EBSS buffered with sodium bicarbonate provides a rate of degradation comparable to those observed in vivo. In contrast, the addition of components such as (4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid) (HEPES), vitamins, amino acids, and albumin significantly increased corrosion rates. Based on these findings, it is proposed that with this in vitro protocol, immersion of Mg alloys in EBSS can be used as a predictor of in vivo corrosion. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Asbestos exposure induces alveolar epithelial cell plasticity through MAPK/Erk signaling
Authors: Tamminen Jenni A. , Myllärniemi Marjukka , Hyytiäinen Marko , Keski‐Oja Jorma , Koli Katri
Published: February 2012

The inhalation of asbestos fibers is considered to be highly harmful, and lead to fibrotic and/or malignant disease. Epithelial‐to‐mesenchymal transition (EMT) is a common pathogenic mechanism in asbestos associated fibrotic (asbestosis) and malignant lung diseases. The characterization of molecular pathways contributing to EMT may provide new possibilities for prognostic and therapeutic applications. The role of asbestos as an inducer of EMT has not been previously characterized. We exposed cultured human lung epithelial cells to crocidolite asbestos and analyzed alterations in the expression of epithelial and mesenchymal marker proteins and cell morphology. Asbestos was found to induce downregulation of E‐cadherin protein levels in A549 lung carcinoma cells in 2‐dimensional (2D) and 3D cultures. Similar findings were made in primary small airway epithelial cells cultured in 3D conditions where the cells retained alveolar type II cell phenotype. A549 cells also exhibited loss of cell–cell contacts, actin reorganization and expression of α‐smooth muscle actin (α‐SMA) in 2D cultures. These phenotypic changes were not associated with increased transforming growth factor (TGF)‐β signaling activity. MAPK/Erk signaling pathway was found to mediate asbestos‐induced downregulation of E‐cadherin and alterations in cell morphology. Our results suggest that asbestos can induce epithelial plasticity, which can be interfered by blocking the MAPK/Erk kinase activity. J. Cell. Biochem. 113: 2234–2247, 2012. © 2012 Wiley Periodicals, Inc.
A DNA binding mutation in estrogen receptor‐α Leads to suppression of Wnt signaling via β‐catenin destabilization in osteoblasts
Authors: Mödder Ulrike I. , Rudnik Volha , Liu Gang , Khosla Sundeep , Monroe David G.
Published: February 2012

Estrogen receptors (ERs) play vital roles in the function and remodeling of bone. Their cellular mechanisms can broadly be categorized into those involving direct DNA binding (classical) or indirect DNA binding (non‐classical). The generation of non‐classical ER knock‐in (ERα−/NERKI) mice provides a unique opportunity to define these pathways in bone. We previously demonstrated that ERα−/NERKI mice exhibit an osteoporotic phenotype; however, the mechanism(s) for this remain unresolved. Gene expression analyses of cortical bone from ERα−/NERKI mice revealed suppression of lymphoid enhancer factor‐1 (Lef1), a classic Wnt‐responsive transcription factor that associates with β‐catenin. Since Wnt signaling is generally considered bone anabolic, this observation leads to the hypothesis that NERKI‐induced suppression of Wnt signaling may contribute to the low bone mass phenotype. We generated ERα−/NERKI mice crossed with the Wnt‐responsive TOPGAL transgenic mouse model and observed significantly less β‐galactosidase activity in ERα−/NERKI mice, confirming suppression of Wnt activity in vivo. Adenoviral expression of the NERKI receptor using an in vitro cell system resulted in the induction of several secreted antagonists of Wnt signaling. Furthermore, expression of NERKI abrogated Wnt10b‐dependent Wnt activation using a lentiviral‐mediated reporter assay. Finally, expression of NERKI destabilized β‐catenin cellular protein levels and disrupted ER/β‐catenin interactions. Collectively, these data suggest the osteoporotic phenotype of ERα−/NERKI mice may involve the suppression of Lef1‐mediated Wnt signaling through both the stimulation of secreted Wnt inhibitors and/or disruption of normal β‐catenin function. J. Cell. Biochem. 113: 2248–2255, 2012. © 2012 Wiley Periodicals, Inc.
Inhibition of inducible nitric oxide synthase prevents lipid peroxidation in osteoarthritic chondrocytes
Authors: Bentz Mireille , Zaouter Charlotte , Shi Qin , Fahmi Hassan , Moldovan Florina , Fernandes Julio C. , Benderdour Mohamed
Published: February 2012

Nitric oxide (NO) and the lipid peroxidation (LPO) product 4‐hydroxynonenal (HNE) are considered to be key mediators of cartilage destruction in osteoarthritis (OA). NO is also known to be an important intermediary in LPO initiation through peroxynitrite formation. The aim of the present study was to assess the ability of the inducible NO synthase (iNOS) inhibitor N‐iminoethyl‐L‐lysine (L‐NIL) to prevent HNE generation via NO suppression in human OA chondrocytes and cartilage explants. Human OA chondrocytes and cartilage explants were treated with L‐NIL and thereafter with or without interleukin‐1beta (IL‐1β) or HNE at cytotoxic or non‐cytotoxic concentrations. Parameters related to oxidative stress, apoptosis, inflammation, and catabolism were investigated. L‐NIL stifled IL‐1β‐induced NO release, iNOS activity, nitrated proteins, and HNE generation in a dose‐dependent manner. It also blocked IL‐1β‐induced inactivation of the HNE‐metabolizing glutathione‐s‐transferase (GST). L‐NIL restored both HNE and GSTA4‐4 levels in OA cartilage explants. Interestingly, it also abolished IL‐1β‐evoked reactive oxygen species (ROS) generation and p47 NADPH oxidase activation. Furthermore, L‐NIL significantly attenuated cell death and markers of apoptosis elicited by exposure to a cytotoxic dose of HNE as well as the release of prostaglandin E2 and metalloproteinase‐13 induced by a non‐cytotoxic dose of HNE. Altogether, our findings support a beneficial effect of L‐NIL in OA by (i) preventing the LPO process and ROS production via NO‐dependent and/or independent mechanisms and (ii) attenuating HNE‐induced cell death and different mediators of cartilage damage. J. Cell. Biochem. 113: 2256–2267, 2012. © 2012 Wiley Periodicals, Inc.
Imaging of central nervous system viral diseases
Authors: Gupta Rakesh Kumar , Soni Neetu , Kumar Sunil , Khandelwal Niranjan
Published: February 2012

Viral infections of the central nervous system (CNS) are commonly encountered and there has been continued emergence of new neurotropic viruses which are being frequently recognized. These may present clinically as encephalitis, meningitis, encephalomyelitis, and encephalomyeloradiculitis. The clinical manifestations are usually nonspecific and diagnosis is usually based on the laboratory investigations. Imaging plays a role in its early detection and at times suggests the specific diagnosis that may help in early institution of appropriate therapy. In this review, we summarize the pathology, clinical, and imaging features of the common viral infections that affect the CNS. J. Magn. Reson. Imaging 2012;35:477‐491. © 2012 Wiley Periodicals, Inc.
Hepatobiliary MR imaging with gadolinium‐based contrast agents
Authors: Frydrychowicz Alex , Lubner Meghan G. , Brown Jeffrey J. , Merkle Elmar M. , Nagle Scott K. , Rofsky Neil M. , Reeder Scott B.
Published: February 2012

The advent of gadolinium‐based “hepatobiliary” contrast agents offers new opportunities for diagnostic magnetic resonance imaging (MRI) and has triggered great interest for innovative imaging approaches to the liver and bile ducts. In this review article we discuss the imaging properties of the two gadolinium‐based hepatobiliary contrast agents currently available in the U.S., gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared toward optimizing workflow and imaging quality are also discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents and will stimulate the reader's pursuit of new applications for future benefit. J. Magn. Reson. Imaging 2012;35:492‐511. © 2011 Wiley Periodicals, Inc.
DIfferential subsampling with cartesian ordering (DISCO): A high spatio‐temporal resolution dixon imaging sequence for multiphasic contrast enhanced abdominal imaging
Authors: Saranathan Manojkumar , Rettmann Dan W. , Hargreaves Brian A. , Clarke Sharon E. , Vasanawala Shreyas S.
Published: February 2012

Purpose:

To develop and evaluate a multiphasic contrast‐enhanced MRI method called DIfferential Sub‐sampling with Cartesian Ordering (DISCO) for abdominal imaging.

Materials and Methods:

A three‐dimensional, variable density pseudo‐random k‐space segmentation scheme was developed and combined with a Dixon‐based fat‐water separation algorithm to generate high temporal resolution images with robust fat suppression and without compromise in spatial resolution or coverage. With institutional review board approval and informed consent, 11 consecutive patients referred for abdominal MRI at 3 Tesla (T) were imaged with both DISCO and a routine clinical three‐dimensional SPGR‐Dixon (LAVA FLEX) sequence. All images were graded by two radiologists using quality of fat suppression, severity of artifacts, and overall image quality as scoring criteria. For assessment of arterial phase capture efficiency, the number of temporal phases with angiographic phase and hepatic arterial phase was recorded.

Results:

There were no significant differences in quality of fat suppression, artifact severity or overall image quality between DISCO and LAVA FLEX images (P > 0.05, Wilcoxon signed rank test). The angiographic and arterial phases were captured in all 11 patients scanned using the DISCO acquisition (mean number of phases were two and three, respectively).

Conclusion:

DISCO effectively captures the fast dynamics of abdominal pathology such as hyperenhancing hepatic lesions with a high spatio‐temporal resolution. Typically, 1.1 × 1.5 × 3 mm spatial resolution over 60 slices was achieved with a temporal resolution of 4–5 s. J. Magn. Reson. Imaging 2012;35:1484–1492. © 2012 Wiley Periodicals, Inc.
Measurement of liver T1 and T2 relaxation times in an experimental mouse model of liver fibrosis
Authors: Chow April M. , Gao Darwin S. , Fan Shu Juan , Qiao Zhongwei , Lee Frank Y. , Yang Jian , Man Kwan , Wu Ed X.
Published: February 2012

Purpose:

To characterize changes in relaxation times of liver using quantitative magnetic resonance imaging (MRI) in an experimental mouse model of liver fibrosis. Quantitative MRI is a potentially robust method to characterize liver fibrosis. However, correlation between relaxation times and fibrosis stage has been controversial.

Materials and Methods:

Liver fibrosis was induced in male adult C57BL/6N mice (22–25 g; n = 12) by repetitive dosing of carbon tetrachloride (CCl4). The animals were examined with a series of spin‐echo (SE) images with varying TRs and multiecho SE imaging sequence at 7 T before and 2, 4, 6, and 8 weeks after CCl4 insult. Hepatic T1 and T2 values were measured. Histology was performed with hematoxylin‐eosin staining and Masson's trichrome staining.

Results:

Significant increase (P < 0.001) in hepatic T1 was found at 2, 4, 6, and 8 weeks following CCl4 insult as compared with that before insult. Meanwhile, hepatic T2 at 2, 4, 6, and 8 weeks after CCl4 insult was significantly higher (P < 0.001) than that before the insult. Liver histology showed collagen deposition, edema, and infiltration of inflammatory cells in livers with CCl4 insult.

Conclusion:

Both longitudinal and transverse relaxation times may serve as robust markers for liver fibrosis. With the advent of single breath‐hold sequences for MR relaxometry, quantitative mapping of relaxation times can be routinely and reliably performed in abdominal organs and hence may be valuable and robust in detecting liver fibrosis at early phase and monitoring its progression. J. Magn. Reson. Imaging 2012;36:152–158. © 2012 Wiley Periodicals, Inc.
Liver fibrosis: An intravoxel incoherent motion (IVIM) study
Authors: Chow April M. , Gao Darwin S. , Fan Shu Juan , Qiao Zhongwei , Lee Frank Y. , Yang Jian , Man Kwan , Wu Ed X.
Published: February 2012

Purpose:

To characterize longitudinal changes in molecular water diffusion, blood microcirculation, and their contributions to the apparent diffusion changes using intravoxel incoherent motion (IVIM) analysis in an experimental mouse model of liver fibrosis.

Materials and Methods:

Liver fibrosis was induced in male adult C57BL/6N mice (22–25 g; n = 12) by repetitive dosing of carbon tetrachloride (CCl4). The respiratory‐gated diffusion‐weighted (DW) images were acquired using single‐shot spin‐echo EPI (SE‐EPI) with 8 b‐values and single diffusion gradient direction. True diffusion coefficient (Dtrue), blood pseudodiffusion coefficient (Dpseudo), and perfusion fraction (Pfraction) were measured. Diffusion tensor imaging (DTI) was also performed for comparison. Histology was performed with hematoxylin‐eosin and Masson's trichrome staining.

Results:

A significant decrease in Dtrue was found at 2 weeks and 4 weeks following CCl4 insult, as compared with that before insult. Similarly, Dpseudo values before injury was significantly higher than those at 2 weeks and 4 weeks after CCl4 insult. Meanwhile, Pfraction values showed no significant differences over different timepoints. For DTI, significant decrease in ADC was observed following CCl4 administration. Fractional anisotropy at 2 weeks after CCl4 insult was significantly lower than that before insult, and subsequently normalized at 4 weeks after the insult. Liver histology showed collagen deposition, the presence of intracellular fat vacuoles, and cell necrosis/apoptosis in livers with CCl4 insult.

Conclusion:

Both molecular water diffusion and blood microcirculation contribute to the alteration in apparent diffusion changes in liver fibrosis. Reduction in Dtrue and Dpseudo values resulted from diffusion and perfusion changes, respectively, during the progression of liver fibrosis. IVIM analysis may serve as valuable and robust tool in detecting and characterizing liver fibrosis at early stages, monitoring its progression in a noninvasive manner. J. Magn. Reson. Imaging 2012;36:159–167. © 2012 Wiley Periodicals, Inc.
Dummy molecularly imprinted polymers as the coating of stir bar for sorptive extraction of bisphenol A in tap water
Authors: Sheng Na , Wei Fangdi , Zhan Wen , Cai Zheng , Du Shuhu , Zhou Xuemin , Li Fei , Hu Qin
Published: February 2012

A unique stir bar coated with dummy molecularly imprinted polymers for bisphenol A was prepared by sol‐gel technique. The scanning electron microscopic image of the coating presented a homogeneous surface with a thickness of about 57 ± 2.5 μm. The Fourier transform infrared spectrum of the coating proved the incorporating of dummy molecularly imprinted polymers with the sol‐gel network. When used to extract bisphenol A from aqueous solution containing bisphenol A and its three analogs (4‐tert‐butylphenol, 4,4′‐dihydroxybiphenyl, and 3,3′,5,5′‐tetrabromo‐bisphenol A). Dummy molecularly imprinted polymers‐coated stir bar showed better selectivity than the bars coated with polydimethylsiloxane or non‐imprinted polymers. The extraction conditions including stirring speed, pH, and extraction time were optimized. After back extraction with methanol, the extracts were analyzed by high‐performance liquid chromatography‐fluorescence detection. The linear range was 0.0228–0.456 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 5.70 × 10−3 ng/mL based on three times ratio of signal‐to‐noise. The method was applied to the determination of trace bisphenol A in tap water.
Sample stacking with in‐column silylation for less volatile polar compounds using GC‐MS
Authors: Cho Seungil
Published: February 2012

This paper presents sample stacking with in‐column silylation (SIS) for quantitative analysis of less volatile polar compounds using gas chromatography‐mass spectrometry (GC‐MS). This was achieved by the combination of sandwiched in‐column silylation and multiple injections (up to 100 times or 100 μL in total). N,O‐bis(trimethylsilyl)trifluoroacetamide (BSTFA) was used as a silylating reagent. For the SIS technique, samples were introduced multiple N times (N = 2∼100) into a capillary column in between BSTFA injections. The quantitative characteristic of SIS technique was studied using bisphenol A (BPA) as a model compound. The sandwiched in‐column silylation for the less volatile polar compounds effectively replaced polar hydrogen with trimethylsilyl group to reduce sample adsorption and band broadening. Meanwhile, multiple injections at the SIS technique contributed to increase the sensitivity quantitatively. The capability and limitation of this analytical approach were further investigated with various types of compounds such as hydroxyls, carboxylic acids, and amine.
One‐step multiple component isolation from the oil of Crinitaria tatarica (Less.) Sojak by preparative capillary gas chromatography with characterization by spectroscopic and spectrometric techniques and evaluation of biological activity
Authors: Özek Gulmira , Ishmuratova Margarita , Tabanca Nurhayat , Radwan Mohammed M. , Göger Fatih , Özek Temel , Wedge David E. , Becnel James J. , Cutler Stephen J. , Can Başer Kemal H.
Published: February 2012

Gas chromatographic analysis revealed that the oil of Crinitaria tatarica was rich in sabinene (32.1%), β‐pinene (8.8%), and two unknown (M+200) compounds (I) and (II) (21.4% and 3.4%). One‐step multiple fractionation of the oil and separation of two unknown constituents were performed using preparative capillary gas chromatography connected to preparative fraction collector system. This combination allowed separation and recover of sufficient quantities of two unknown compounds with high purity from complex oil matrix. Separation conditions (column temperature, cooling temperature, flow rate, injection volume, cut time) were optimized to achieve the best isolation and successful collection. The target compounds were separated from the oil using a HP Innowax (Walt & Jennings Scientific, Wilmington, DE, USA) preparative capillary column in rapid one‐step manner with 95.0% purity. Trapping of the isolated compounds in collector system was facilitated by cooling with liquid nitrogen. Structure determination was accomplished by spectral analysis including ultraviolet, nuclear magnetic rezonance, and high‐resolution electrospray ionization mass spectrometry. Z‐ (I) and E‐artemidin (II) were isolated for the first time from this species. Crinitaria tatarica oil and Z‐ (I) and E‐artemidin (II) were evaluated for biological activity.
Preclinical in vivo evaluation of Npe6‐mediated photodynamic therapy on normal vasculature
Authors: Moy Wesley J. , Patel Shreyas J. , Lertsakdadet Ben S. , Arora Rajan P. , Nielsen Katherine M. , Kelly Kristen M. , Choi Bernard
Published: February 2012

Background and Objective

Current treatments of port‐wine stain birthmarks typically involve use of a pulsed dye laser (PDL) combined with cooling of the skin. Currently, PDL therapy protocols result in varied success, as some patients experience complete blanching, while others do not. Over the past decade, we have studied the use of photodynamic therapy (PDT) as either a replacement or adjuvant treatment option to photocoagulate both small and large vasculature. The objective of the current study was to evaluate a PDT protocol that involves use of an alternate intravascular photosensitizer mono‐L‐aspartylchlorin‐e6 (NPe6) activated by an array of low‐cost light emitting diodes.

Study Design/Materials and Methods

To monitor the microvasculature, a dorsal window chamber model was installed on 22 adult male mice. The light source consisted of a custom‐built LED array that emitted 10 W at a center wavelength of 664 nm (FWHM = 20 nm). The light source was positioned at a fixed distance from the window chamber to achieve a fixed irradiance of 127 mW/cm2. A retroorbital injection of NPe6 (5 mg/kg) was performed to deliver the drug into the bloodstream. Laser irradiation was initiated immediately after injection. To monitor blood‐flow dynamics in response to PDT, we used laser speckle imaging. We employed a dose–response experimental design to evaluate the efficacy of NPe6‐mediated PDT.

Results

We observed three general hemodynamic responses to PDT: (1) At low radiant exposures, we did not observe any persistent vascular shutdown; (2) at intermediate radiant exposures, we observed an acute decrease in blood flow followed by gradual restoration of blood flow over the 7‐day monitoring period; and (3) at high radiant exposures, we observed acute vascular shutdown that persisted during the entire 7‐day monitoring period. Dose–response analysis enabled identification of 85 J/cm2 as a characteristic radiant exposure required to achieve persistent vascular shutdown at Day 7 following PDT.

Conclusion

The experimental data suggest that NPe6‐mediated PDT can achieve persistent vascular shutdown of normal microvasculature. Lasers Surg. Med. 44:158–162, 2012. © 2012 Wiley Periodicals, Inc.
Materials and Corrosion 2/2012
Authors: Schneider M. , Schroth S. , Schubert N. , Michaelis A.
Published: February 2012

Cover: The cover shows an illustration of the experimental set up for in‐situ investigations of the anodic metal dissolution under ECM conditions

A specially designed channel flow cell is placed under an optical microscope with long distance lens. A gold disc with a small conical glass lens in the centre is embedded in the glass lid of the channel flow cell and works as cathode. The sample is placed beneath the cathode and works as anode. The gap width of the channel amounts 0.35mm. A maximum electrolyte flow rate of 12.3m/s was realized. The anodic dissolution was carried out by current controlled pulses. The test assembly allows the observation of the surface topography development of the anode as well as possible interface reactions (e.g. gas evolution). More detailed information can be found in: M. Schneider, S. Schroth, N. Schubert, A. Michaelis, In‐situ investigation of the surface‐topography during anodic dissolution of copper under near‐ECM conditions, Materials and Corrosion 2012, 63, 96.
Nano‐/Microscale Investigation of Tribological and Mechanical Properties of Epoxy/MWNT Nanocomposites
Authors: Ayatollahi Majid Reza , Doagou‐Rad Saeed , Shadlou Shahin
Published: February 2012

The effects of MWNT content and aspect ratio on the properties of epoxy‐based nanocomposites are investigated using nanoindentation and nanoscratch methods. The Halpin‐Tsai model for predicting the elastic modulus and hardness is modified to include the effective aspect ratio factor. The modified model predicts the experimental results more accurately. The frictional behavior is investigated and a new equation is proposed that correlates the ploughing friction with the plasticity index. The dispersion state of MWNTs and the surface features of residual grooves are investigated using scanning electron micrographs and AFM profiles. The mechanisms of improvements in the properties are also discussed.

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The Singapore Mental Health Study: an overview of the methodology
Authors: Subramaniam Mythily , Vaingankar Janhavi , Heng Derrick , Kwok Kian Woon , Lim Yee Wei , Yap Mabel , Chong Siow Ann
Published: February 2012

The Singapore Mental Health Study (SMHS) is a population‐based, cross‐sectional, epidemiological study on the Singapore multi‐ethnic adult population. This article provides an overview of the research design and methods used which took into consideration the unique characteristics of the country and its multi‐ethnic population. A face‐to‐face household survey of Singapore residents aged 18 years and above was undertaken from 2009 to 2010. The nationally representative probability sample was derived using a disproportionate stratified sampling method. In order to increase precision for subgroup estimations the design was stratified with over‐sampling of Malays, Indians and those aged 65 years and above. Respondents were assessed using the English, Chinese (computerized) and Malay (paper and pencil based) version of the Composite International Diagnostic Interview (CIDI) 3.0 to establish lifetime and 12‐month prevalence of mental disorders, the current use of mental health services (both Western and traditional services), the treatment gaps and loss of role functioning. Copyright © 2012 John Wiley & Sons, Ltd.
Spectra edited by relative signs of homonuclear couplings of low abundance nuclei
Authors: Blechta Vratislav , Kurfürst Milan , Schraml Jan
Published: February 2012

The proposed homonuclear coupling sign edited (HCSE) experiment can detect signed homonuclear couplings between low abundant nuclei like 13C, 29Si and 15N in linear spin systems, that is, in systems where two nuclei are coupled by the measured coupling, and one of them is coupled by a second coupling to a nucleus of different kind. The third nucleus is usually high abundant hydrogen. Two spectra are measured during the HCSE experiment. Their weighed sum and difference yield two other spectra, one containing peaks coupled only by positive measured couplings and the other having peaks coupled by negative measured couplings. The usual E.COSY‐type experiment requires all three couplings in the three spin system (triangular spin system) and not only two couplings as the HCSE experiment. The experiment was successfully tested on known carbon–carbon and silicon–silicon two bond couplings. A set of six simple siloxanes with |2J(Si‐O‐Si)| couplings ranging from 0.5 to 9.0 Hz was measured for the first time, and all the couplings were found to be positive. Copyright © 2012 John Wiley & Sons, Ltd.
The effect of leptin on maturing porcine oocytes is dependent on glucose concentration
Authors: Silva Elena , Paczkowski Melissa , Krisher Rebecca L.
Published: February 2012

Increased body weight is often accompanied by increased circulating levels of leptin and glucose, which alters glucose metabolism in various tissues, including perhaps the oocyte. Alteration of glucose metabolism impacts oocyte function and may contribute to the subfertility often associated with obese individuals. The objective of this study was to determine the effect of leptin (0, 10, and 100 ng/ml) on the oocyte and cumulus cells during in vitro maturation under differing glucose concentrations. We examined the effects of leptin on oocyte maturation, blastocyst development, and/or gene expression in oocytes and cumulus cells (IRS1, IGF1, PPARγ, IL6, GLUT1) in a physiological glucose (2 mM) and high glucose (50 mM) environment. We also evaluated the effect of leptin on glucose metabolism via glycolysis and the pentose phosphate pathway. In a physiological glucose environment, leptin did not have an influence on oocyte maturation, blastocyst development, or oocyte gene expression. Expression of GLUT1 in cumulus cells was downregulated with 100 ng/ml leptin treatment, but did not affect oocyte glucose metabolism. In a high glucose environment, oocyte maturation and glycolysis were decreased, but in the presence of 100 ng/ml leptin, these parameters were improved to levels similar to control. This effect is potentially mediated by an upregulation of oocyte IRS1 and a correction of cumulus cell IGF1 expression. The present study demonstrates that in a physiological glucose concentration, leptin plays a negligible role in oocyte function. However, leptin appears to modulate the deleterious impact of a high glucose environment on oocyte function. Mol. Reprod. Dev. 79: 296–307, 2012. © 2012 Wiley Periodicals, Inc.
Model‐based analysis of multishell diffusion MR data for tractography: How to get over fitting problems
Authors: Jbabdi Saad , Sotiropoulos Stamatios N. , Savio Alexander M. , Graña Manuel , Behrens Timothy E. J.
Published: February 2012

In this article, we highlight an issue that arises when using multiple b‐values in a model‐based analysis of diffusion MR data for tractography. The non‐monoexponential decay, commonly observed in experimental data, is shown to induce overfitting in the distribution of fiber orientations when not considered in the model. Extra fiber orientations perpendicular to the main orientation arise to compensate for the slower apparent signal decay at higher b‐values. We propose a simple extension to the ball and stick model based on a continuous gamma distribution of diffusivities, which significantly improves the fitting and reduces the overfitting. Using in vivo experimental data, we show that this model outperforms a simpler, noise floor model, especially at the interfaces between brain tissues, suggesting that partial volume effects are a major cause of the observed non‐monoexponential decay. This model may be helpful for future data acquisition strategies that may attempt to combine multiple shells to improve estimates of fiber orientations in white matter and near the cortex. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Spectral decomposition of susceptibility artifacts for spectral‐spatial radiofrequency pulse design
Authors: Yang Cungeng , Poser Benedikt A. , Deng Weiran , Stenger V. Andrew
Published: February 2012

Susceptibility induced signal loss is a limitation in gradient echo functional MRI. The through‐plane artifact in axial slices is particularly problematic due to the inferior position of air cavities in the brain. Spectral‐spatial radiofrequency pulses have recently been shown to reduce signal loss in a single excitation. The pulses were successfully demonstrated assuming a linear relationship between susceptibility gradient and frequency, however, the exact frequency and spatial distribution of the susceptibility gradient in the brain is unknown. We present a spiral spectroscopic imaging sequence with a time‐shifted radiofrequency pulse that can spectrally decompose the through‐plane susceptibility gradient for spectral‐spatial radiofrequency pulse design. Maps of the through‐plane susceptibility gradient as a function of frequency were generated for the human brain at 3T. We found that the linear relationship holds well for the whole brain with an optimal slope of −1.0 μT/m/Hz. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
In Vitro Susceptibility of Important Skin and Wound Pathogens Against Low Temperature Atmospheric Pressure Plasma Jet (APPJ) and Dielectric Barrier Discharge Plasma (DBD)
Authors: Daeschlein Georg , Scholz Sebastian , Arnold Andreas , von Podewils Sebastian , Haase Hermann , Emmert Steffen , von Woedtke Thomas , Weltmann Klaus‐Dieter , Jünger Michael
Published: February 2012

Plasma medicine has become an emerging field in medical sciences since cold plasma has demonstrated anti‐inflammatory, anti‐tumor as well as antimicrobial effects. In the light of increasing resistance of many pathogens like methicillin‐resistant Staphylococcus aureus (MRSA) to a multitude of antimicrobial therapies cold plasma therapy with complete different modes of action could constitute an alternative to conventional external antibiotic and antiseptic therapies. As plasma susceptibility data of human skin and wound pathogens are not available, the susceptibility of 105 typical isolates from dermatologic patients' wounds to low temperature atmospheric pressure plasma (APPJ device) and dielectric barrier discharge plasma device are tested in vitro. Plasma treatment proved to be highly effective in eradicating all (n = 105) strains including Escherichia coli, Pseudomonas aeruginosa, Klebsiella group (K. pneumoniae ssp. pneumoniae, K. oxytoca), S. aureus, hemolysing Lancefield Streptococci (group A and B), Proteus group (P. mirabilis, P. vulgaris), Acinetobacter spp., Stenotrophomonas spp., Enterococcus faecalis, Candida albicans and Staphylococcus epidermidis. In conclusion, cold plasma treatment exhibited strong and rapid antimicrobial effects against clinical most relevant skin and wound pathogens in vitro. Cold plasma may constitute an effective alternative to antiseptics in the attempt to eradicate skin and wound pathogens.

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Growth and optical properties of gadolinium aluminum nitride thin films
Authors: Chen Yigang , Shi Xiaolei , Yang Jing , Chen Yiner
Published: February 2012

In this study, c‐axis oriented AlN, GdxAl1‐xN and AlN/Gd0.05Al0.95N films have been successfully grown on both Si(100) and quartz glass substrates by DC magnetron reactive sputtering method. The XRD patterns show that the crystal structure of the film has changed after doping Gd3+. The optical constants were obtained by ellipsometry measurements. The high extinction coefficient k in the deep UV range is just in agreement with the low transmittance in the range of 250‐300 nm. The refractive index n increases as well with increasing Gd concentrations. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and optimization of electric current spreading in III‐nitride LEDs
Authors: Suslov S. S. , Bougrov V. E. , Odnoblyudov M. A. , Romanov A. E.
Published: February 2012

In this work, we perform numerical simulations of a conventional GaN LED chip within the framework of the combined electrical/thermal/light approach. A GaN LED chip grown on a sapphire substrate is investigated. We calculate the dependencies of the forward voltage, light output power, wall‐plug efficiency, and uniformity of current spreading on the variations in the electrode geometry. Modelling is performed using a self‐developed software based on the Finite Volume method and the Monte Carlo ray tracing technique. The simulation results show that a well‐designed electrode pattern can provide more than 8% improvement in the wall‐plug efficiency. The implementation of contact optimization is required for designing highly efficient LED devices. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cd doping of AlN via ion implantation studied with perturbed angular correlation
Authors: Kessler P. , Lorenz K. , Miranda S. M. C. , Simon R. , Correia J. G. , Johnston K. , Vianden R. , the ISOLDE collaboration
Published: February 2012

AlN with a wide bandgap of 6.2 eV is a promising candidate for ultraviolet light‐emitting diodes and laser diodes. However, the production of the required p‐type AlN is still challenging. As a possible dopant Cd was suggested among other Group II atoms (Be, Mg, and Zn). In this study the annealing condition of implanted Cd in AlN was investigated with the method of the perturbed angular correlation (PAC). Therefore radioactive 117Cd or 111mCd ions were implanted into thin AlN films on sapphire substrate with an energy of 30 keV and fluences in the range of 1011 ions/cm2.

After thorough annealing with a proximity cap of the same material most of the Cd‐probes occupy substitutional lattice sites and almost all implantation damage can be annealed. This results in a distinct frequency in the PAC spectra which increases with temperature. In contrast to the formation of an indium nitrogen‐vacancy complex observed with the probe 111In on substitutional Al‐sites no defects are bound to substitutional Cd impurities. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural characterization of InN epilayers grown on r ‐plane sapphire by plasma‐assisted MBE
Authors: Lotsari A. , Dimitrakopulos G. P. , Kehagias Th. , Ajagunna A. O. , Iliopoulos E. , Georgakilas A. , Komninou Ph.
Published: February 2012

The structural properties of InN films grown on r ‐plane (1$\bar 1$02) sapphire by plasma‐assisted molecular beam epitaxy (PAMBE) using low temperature buffer layers are studied. Nonpolar a ‐plane (1$\bar 1$20) and semipolar s ‐plane (10$\bar 1$1) films were deposited depending on buffer layer and growth conditions. Single crystalline a ‐plane InN was grown using a GaN buffer layer following sapphire nitridation. Transmission electron microscopy (TEM) observations showed three‐dimensional growth and interactions of inclined threading dislocations emanating from the buffer layer. The defect interactions gradually reduced the threading dislocation density. Semipolar s ‐plane was grown when a thin InN buffer layer was employed. The epilayer was found to comprise two s ‐plane variants. Semipolar nucleation directly on the sapphire was observed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Complete controllability for abstract measure differential systems
Authors: Wan Xiaojun , Sun Jitao
Published: February 2012

In this paper, we investigate the complete controllability for abstract measure differential systems. Firstly, we introduce several new concepts about complete controllability for abstract measure differential systems. Then, on the basis of the Sadovskii fixed‐point theorem, we give sufficient conditions for complete controllability for a class of abstract measure differential systems. The compactness of the semigroup generated by some operator is unnecessary in this paper, and we show that our results, dealing with complete controllability problem for an ordinary differential system in infinite‐dimensional Banach space, are also less conservative than that in the previous literature. Copyright © 2012 John Wiley & Sons, Ltd.
Tuning Electron Transport in Graphene‐Based Field‐Effect Devices using Block Co‐polymers
Authors: Guo Shirui , Ghazinejad Maziar , Qin Xiangdong , Sun Huaxing , Wang Wei , Zaera Francisco , Ozkan Mihrimah , Ozkan Cengiz S.
Published: February 2012

Graphene possesses many remarkable properties and shows promise as the future material for building nanoelectronic devices. For many applications such as graphene‐based field‐effect transistors (GFET), it is essential to control or modulate the electronic properties by means of doping. Using spatially controlled plasma‐assisted CF4doping, the Dirac point shift of a GFET covered with a polycrystalline PS‐P4VP block co‐polymer (BCP) [poly(styrene‐b‐4‐vinylpyridine)] having a cylindrical morphology can be controlled. By changing the chemical component of the microdomain (P4VP) and the major domain (PS) with the CF4plasma technique, the doping effect is demonstrated. This work provides a methodology where the Dirac point can be controlled via the different sensitivities of the PS and P4VP components of the BCP subjected to plasma processing.
Air‐Grid Surface Patterning Provided by Superhydrophobic Surfaces
Authors: Chen Li , Yang Gao , Wang Shutao
Published: February 2012

Recently, several unique studies on surface patterning have been developed based on superhydrophobic surfaces, where air was introduced as the separating barrier for the surface pattern. This new type of surface patterning approach is called “air‐grid surface patterning.” Traditional technologies of surface patterning always utilize the solid or liquid phase as the separating barrier, for example, a 2D chemical molecular barrier in soft lithography, a 3D solid barrier in photolithography, or a liquid barrier in microfluidic, laminar flow patterning methods. These recent studies reveal that air can act as a gas‐phase separating barrier. This concept is expected to open up a new branch of applications of superhydrophobic surfaces, and it exhibits promising potential for functional micropatterning of various materials, from nanomaterials to crystals to cells.
Intermediate transverse stiffeners in plate girders
Authors: Sinur Franc , Beg Darko
Published: February 2012

The aim of this paper is to study the design requirements for rigid intermediate transverse stiffeners in longitudinally stiffened plate girders. Firstly, two representative design codes, AASHTO and EN 1933‐1‐5, are discussed and compared. Then the results of two tests on 1.5 m deep plate girders and the results of the extensive numerical parametric study are presented. The analysis of the results shows that the axial force in the stiffener due to tension field action is overestimated in the design codes and that all the design requirements for rigid transverse stiffeners can be covered by defining a minimum required second moment of area.
Ligand‐specific differential regulation of 5‐hydroxytryptamine receptors: functional selectivity in serotonergic signaling
Authors: Stroth Nikolas , Svenningsson Per
Published: February 2012

Pharmacological theory has recently undergone an important revision. It is now clear that certain ligands can exert differential regulation of the effector mechanisms that are coupled to their cognate receptors, enabling functional selectivity in the control of distinct cellular outputs. Ligands at receptors for the biogenic amine serotonin (5‐hydroxytryptamine, 5‐HT) have provided convincing examples of functional selectivity, and key experiments from this area are the subject of the present review. Given that signaling through 5‐HT receptors is implicated in many diseases, functionally selective modulation of such signaling may be a promising avenue for the development of improved therapeutics. WIREs Membr Transp Signal 2012, 1:453–466. doi: 10.1002/wmts.39

For further resources related to this article, please visit the WIREs website.
Diverse functional networks of Tbx3 in development and disease
Authors: Washkowitz Andrew J. , Gavrilov Svetlana , Begum Salma , Papaioannou Virginia E.
Published: February 2012

The T‐box transcription factor Tbx3 plays multiple roles in normal development and disease. In order to function in different tissues and on different target genes, Tbx3 binds transcription factors or other cofactors specific to temporal or spatial locations. Examining the development of the mammary gland, limbs, and heart as well as the biology of stem cells and cancer provides insights into the diverse and common functions that Tbx3 can perform. By either repressing or activating transcription of target genes in a context‐dependent manner, Tbx3 is able to modulate differentiation of immature progenitor cells, control the rate of cell proliferation, and mediate cellular signaling pathways. Because the direct regulators of these cellular processes are highly context‐dependent, it is essential that Tbx3 has the flexibility to regulate transcription of a large group of targets, but only become a active on a small cohort of them at any given time or place. Moreover, Tbx3 must be responsive to the variety of different upstream factors that are present in different tissues. Only by understanding the network of genes, proteins, and molecules with which Tbx3 interacts can we hope to understand the role that Tbx3 plays in normal development and how its aberrant expression can lead to disease. Because of its myriad functions in disparate developmental and disease contexts, Tbx3 is an ideal candidate for a systems‐based approach to genetic function and interaction. WIREs Syst Biol Med 2012. doi: 10.1002/wsbm.1162

This article is categorized under:

Developmental Biology > Developmental Processes in Health and Disease

Developmental Biology > Stem Cell Biology and Regeneration
Nutrition issues in Codex: health claims, nutrient reference values and WTO agreements: a conference report
Authors: Aggett Peter J. , Hathcock John , Jukes David , Richardson David P. , Calder Philip C. , Bischoff-Ferrari Heike , Nicklas Theresa , Mühlebach Stefan , Kwon Oran , Lewis Janine , Lugard Maurits J. F. , Prock Peter
Published: February 2012

Background

Codex documents may be used as educational and consensus materials for member governments. Also, the WTO SPS Agreement recognizes Codex as the presumptive international authority on food issues. Nutrient bioavailability is a critical factor in determining the ability of nutrients to provide beneficial effects. Bioavailability also influences the quantitative dietary requirements that are the basis of nutrient intake recommendations and NRVs.

Health claims

Codex, EFSA and some national regulatory authorities have established guidelines or regulations that will permit several types of health claims. The scientific basis for claims has been established by the US FDA and EFSA, but not yet by Codex. Evidence-based nutrition differs from evidence-based medicine, but the differences are only recently gaining recognition. Health claims on foods may provide useful information to consumers, but many will interpret the information to mean that they can rely upon the food or nutrient to eliminate a disease risk.

Nutrient reference values

NRVs are designed to provide a quantitative basis for comparing the nutritive values of foods, helping to illustrate how specific foods fit into the overall diet. The INL-98 and the mean of adult male and female values provide NRVs that are sufficient when used as targets for individual intakes by most adults.

World Trade Organization agreements

WTO recognizes Codex as the primary international authority on food issues. Current regulatory schemes based on recommended dietary allowances are trade restrictive. A substantial number of decisions by the EFSA could lead to violation of WTO agreements.
Unravelling the dynamics of organisms in a changing world using ecological modelling
Authors: Amano Tatsuya
Published: February 2012

Understanding and predicting the dynamics of organisms is a central objective in ecology and conservation biology, and modelling provides a solution to tackling this problem. However, the complex nature of ecological systems means that for a thorough understanding of ecological dynamics at hierarchical scales, a set of modeling approaches need to be adopted. This review illustrates how modelling approaches can be used to understand the dynamics of organisms in applied ecological problems, focussing on mechanistic models at a local scale and statistical models at a broad scale. Mechanistic models incorporate ecological processes explicitly and thus are likely to be robust under novel conditions. Models based on behavioural decisions by individuals represent a typical example of the successful application of mechanistic models to applied problems. Considering the data‐hungry nature of such mechanistic models, model complexity and parameterisation need to be explored further for a quick and widespread implementation of this model type. For broad‐scale phenomena, statistical models play an important role in dealing with problems that are often inherent in data. Examples include models for quantifying population trends from long‐term, large‐scale data and those for comparative methods of extinction risk. Novel statistical approaches also allow mechanistic models to be parameterised using readily obtained data at a macro scale. In conclusion, the complementary use and improvement of multiple model types, the increased use of novel model parameterisation, the examination of model transferability and the achievement of wider biodiversity information availability are key challenges for the effective use of modelling in applied ecological problems.