bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron backscatter diffraction on femtosecond laser sulfur hyperdoped silicon
Authors: Gimpel Thomas , Höger Ingmar , Falk Fritz , Schade Wolfgang , Kontermann Stefan
Published: September 2012

This paper analyzes the impact of femtosecond laser pulse irradiation on the crystallinity of silicon wafers by means of electron backscatter diffraction (EBSD) measurements. EBSD based image quality maps and orientation imaging microscopy maps are correlated to the grade of the silicon crystallinity. We analyze the impact of accumulated net laser irradiation originating from a laser spot overlap that is necessary to process macroscopic areas, e.g., for sulfur doping of semiconductor devices. Furthermore, we demonstrate that post processing annealing recovers crystallinity and therefore allows fs-laser processed silicon to be used in semiconductor device manufacturing.
Contact charging of silica glass particles in a single collision
Authors: Hu W. , Xie L. , Zheng X.
Published: September 2012

Based on asymmetric contact, we present a contact charge model of high-energy trapped holes to predict the contact charging and explain the net charge transfer between identical silica glass surfaces in a single normal collision. Furthermore, the contact charging measurements are investigated on normal collisions of glassy particle-glassy particle-steel plane and glassy particle-glassy plane. The predicted results agree well with our experiments qualitatively and quantitatively: the impacting velocity and the particle size are two important factors affecting the magnitude of the contact charging.
Convergent beam electron-diffraction investigation of lattice mismatch and static disorder in GaAs/GaAs1−xNx intercalated GaAs/GaAs1−xNx:H heterostructures
Authors: Frabboni S. , Grillo V. , Gazzadi G. C. , Balboni R. , Trotta R. , Polimeni A. , Capizzi M. , Martelli F. , Rubini S. , Guzzinati G. , Glas F.
Published: September 2012

Hydrogen incorporation in diluted nitride semiconductors dramatically modifies the electronic and structural properties of the crystal through the creation of nitrogen-hydrogen complexes. We report a convergent beam electron-diffraction characterization of diluted nitride semiconductor-heterostructures patterned at a sub-micron scale and selectively exposed to hydrogen. We present a method to determine separately perpendicular mismatch and static disorder in pristine and hydrogenated heterostructures. The roles of chemical composition and strain on static disorder have been separately assessed.
Analysis of surface plasmon excitation at terahertz frequencies with highly doped graphene sheets via attenuated total reflection
Authors: How Gan Choon
Published: September 2012

Excitation of surface plasmons supported by doped graphene sheets at terahertz frequencies is investigated numerically. To alleviate the momentum mismatch between the highly confined plasmon modes and the incident radiation, it is proposed to increase the surface conductivity of graphene through high doping levels or with few-layer graphene. For currently achievable doping levels, our analysis shows that surface plasmons on monolayer graphene may be excited at operating frequencies up to about 10 THz (∼41.3 meV) with a high-index coupling prism, and higher frequencies/energies are possible for few-layer graphene. These highly confined surface modes are promising for sensing and waveguiding applications in the terahertz regime.
Low-energy electron transmission imaging of clusters on free-standing graphene
Authors: Longchamp Jean-Nicolas , Latychevskaia Tatiana , Escher Conrad , Fink Hans-Werner
Published: September 2012

We investigated the utility of free-standing graphene as a transparent sample carrier for imaging nanometer-sized objects by means of low-energy electron holography. The sample preparation for obtaining contamination-free graphene as well as the experimental setup and findings are discussed. For incoming electrons with 66 eV kinetic energy, graphene exhibits 27% opacity per layer. Hence, electron holograms of nanometer-sized objects adsorbed on free-standing graphene can be recorded and numerically reconstructed to reveal the object's shapes and distribution. Furthermore, a Moiré effect has been observed with free-standing graphene multi-layers.
Wall-less liquid pathways formed with three-dimensional microring arrays
Authors: Lee W. C. , Heo Y. J. , Takeuchi S.
Published: September 2012

This paper describes a method to construct microfluidic pathways without physical walls—wall-less microchannels. Compared to the previous wall-less microfluidics based on two-dimensional patterns, this method uses three-dimensional ring arrays and two immiscible liquids. The distant rings generate free-standing liquid pathways in order to minimize liquid surfaces contacted to solid walls. In the experimental study, we reduced the liquid-solid interface area per volume to 17.3% of that of the conventional microchannels with squared cross-sections. We envision that this aspect would be significant in micro/nano-fluidics, whose surface-area-to-volume ratio is extremely large.
Temperature dependent graphene suspension due to thermal Casimir interaction
Authors: Phan Anh D. , Woods Lilia M. , Drosdoff D. , Bondarev I. V. , Viet N. A.
Published: September 2012

Thermal effects contributing to the Casimir interaction between objects are usually small at room temperature, and they are difficult to separate from quantum mechanical contributions. We propose that the thermal Casimir force effect can be observed for a graphene flake suspended in a fluid between substrates at the room temperature regime. The properly chosen materials for the substrates and fluid induce a Casimir repulsion. The balance with the other forces, such as gravity and buoyancy, results in a stable temperature dependent equilibrium separation. The suspended graphene is a promising system due to its potential for observing thermal Casimir effects at room temperature.
Charge trapping-detrapping induced resistive switching in Ba0.7Sr0.3TiO3
Authors: Zou Xi , Ong Hock Guan , You Lu , Chen Weigang , Ding Hui , Funakubo Hiroshi , Chen Lang , Wang Junling
Published: September 2012

Intensive research has been devoted to the resistive switching phenomena observed in many transitional metal oxides because of its potential for non-volatile memory application. To clarify the underlying mechanism of resistive switching, a planar device can provide information that is not accessible in conventional vertical sandwich structures. Here we report the observation of resistive switching behavior in a Pt/Ba0.7Sr0.3TiO3/Pt planar device. Using in-situ scanning Kelvin probe microscopy, we demonstrate that charge trapping/detrapping around the Pt/Ba0.7Sr0.3TiO3 interface modulates the Schottky barrier, resulting in the observed resistive switching. The findings are valuable for the understanding of resistive switching in oxide materials.
Who Makes the (New) Metropolis? Cross-Border Coalition and Urban Development in Paris
Authors: Savini Federico
Published: September 2012

In fragmented agglomerations, urban development in peripheral areas tends to express the hegemony of the core city over its suburbs. However, this paper demonstrates that, despite deep-rooted political conflicts, intermunicipal cooperation can still take place in the context of cross-border development. I argue that cross-border development has a political and economic logic that is driven by a different power configuration in the metropolis: cross-border coalitions. These coalitions emerge when the redevelopment of areas around municipal borders provides an opportunity for political interests to strengthen their electoral alliances and for business interests to exploit possibilities of growth. This paper investigates urban development in Paris North East, an area on the periphery of Paris that crosses municipal boundaries. It examines how a coalition of public and private actors is cooperating based on the shared benefits they can derive from developments in this area. The case study captures the complex political and economic dynamics driving intermunicipal cooperation by examining the role of local political coalitions, their link with planning agencies, and the behavior of emergent metropolitan entrepreneurs.
Molecular mapping of quantitative trait loci for adult-plant resistance to powdery mildew in Italian wheat cultivar Libellula
Authors: Asad M. A. , Bai B. , Lan C. X. , Yan J. , Xia X. C. , Zhang Y. , He Z. H.
Published: September 2012

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a fungal disease that causes significant yield losses in many wheat-growing regions of the world. Previously, five quantitative trait loci (QTLs) for adult-plant resistance (APR) to stripe rust resistance were identified in Italian wheat cultivar Libellula. The objectives of this study were to map QTLs for APR to powdery mildew in 244 F2 : 3 lines of Libellula/Huixianhong, to analyse the stability of detected QTLs across environments, and to assess the association of these QTLs with stripe rust resistance. Powdery mildew response was evaluated for 2 years in Beijing and for 1 year in Anyang. The correlation between averaged maximum disease severity (MDS) and averaged area under disease progress curve (AUDPC) over 2 years in Beijing was 0.98, and heritabilities of MDS and AUDPC were 0.65 and 0.81, respectively, based on the mean values averaged across environments. SSR markers were used to screen the parents and mapping population. Five QTLs were identified by inclusive composite interval mapping, designated as QPm.caas-2DS, QPm.caas-4BL.1, QPm.caas-6BL.1, QPm.caas-6BL.2, and QPm.caas-7DS. Three QTLs (QPm.caas-2DS and QPm.caas-6BL.1, and QPm.caas-6BL.2) seem to be new resistance loci for powdery mildew. QTLs QPm.caas-2DS and QPm.caas-4BL.1 were identified at the same position as previously mapped QTLs for stripe rust resistance in Libellula. The QTL QPm.caas-7DS, derived from Libellula, coincided with the slow rusting and slow mildewing locus Lr34/Yr18/Pm38. These results and the identified markers could be useful for wheat breeders aiming for durable resistance to both powdery mildew and stripe rust.
Polymer scaling laws of unfolded and intrinsically disordered proteins quantified with single-molecule spectroscopy
Authors: Hofmann Hagen , Soranno Andrea , Borgia Alessandro , Gast Klaus , Nettels Daniel , Schuler Benjamin
Published: September 2012

The dimensions of unfolded and intrinsically disordered proteins are highly dependent on their amino acid composition and solution conditions, especially salt and denaturant concentration. However, the quantitative implications of this behavior have remained unclear, largely because the effective theta-state, the central reference point for the underlying polymer collapse transition, has eluded experimental determination. Here, we used single-molecule fluorescence spectroscopy and two-focus correlation spectroscopy to determine the theta points for six different proteins. While the scaling exponents of all proteins converge to 0.62 ± 0.03 at high denaturant concentrations, as expected for a polymer in good solvent, the scaling regime in water strongly depends on sequence composition. The resulting average scaling exponent of 0.46 ± 0.05 for the four foldable protein sequences in our study suggests that the aqueous cellular milieu is close to effective theta conditions for unfolded proteins. In contrast, two intrinsically disordered proteins do not reach the Θ-point under any of our solvent conditions, which may reflect the optimization of their expanded state for the interactions with cellular partners. Sequence analyses based on our results imply that foldable sequences with more compact unfolded states are a more recent result of protein evolution.
Dietary Lipid Levels Affect Growth and Fatty Acid Profiles of Malaysian Mahseer Tor tambroides
Authors: Ramezani-Fard Ehsan , Kamarudin Mohd Salleh , Saad Che Roos , Harmin Sharr Azni , Meng Goh Yong
Published: September 2012

After protein, the second major essential macronutrient in fish diet is lipid. This study was conducted to determine the optimum level of dietary lipid for the best growth performance of juvenile Malaysian mahseer Tor tambroides. Four isonitrogenous diets containing 40% crude protein were formulated to contain different levels of lipid (5, 10, 15, or 20% on an as-fed basis). Cod liver oil was incorporated into the feed as the main dietary lipid source used to formulate the diets while residual oil coming from other ingredients contributed about 5% of dietary lipid. The experimental diets were labeled as L5, L10, L15, or L20 to denote the levels of dietary lipid. Fish were fed the experimental diets in triplicate groups for 63 d. Growth performance, survival rate, and daily feed intake by Malaysian mahseer significantly decreased when fed diets in which levels of dietary lipid increased from 5% to 20%. However, the growth performance did not vary significantly between fish fed the L5 and L10 diets. The increase in dietary lipid significantly increased the hepatosomatic index but did not influence the viscerosomatic index. Increasing dietary lipid levels also decreased the lipid content in the whole body composition of fish. The monounsaturated fatty acid (MUFA) and n-3 polyunsaturated fatty acid (PUFA) contents of fish liver significantly increased with the increase of dietary lipid. The results of this study suggested that 5% dietary lipid is sufficient for the best survival rate and growth performance of juvenile Malaysian mahseer.
Photodissociation of 2-Bromobutane at ∼265 nm by Ion-velocity Map Imaging Technique
Authors: Zhou Dan-na , Mao Rui , Zhang Li-min , Zhang Qun , Chen Yang
Published: September 2012

The photodissociation dynamics of 2-bromobutane has been investigated at 264.77 and 264.86 nm by ion-velocity map imaging technique coupled with resonance-enhanced multi-photon ionization. The speed and angular distributions have been derived from the velocity map images of Br and Br*. The speed distributions of Br and Br* atoms in the photodissociation of 2-bromobutane at ∼265 nm can be fitted using only one Gaussian function indicating that bromine fragments were produced via direct dissociation of C—Br bond. The contributions of the excited 3Q0, 3Q1, and 1Q1 states to the products (Br and Br*) were discussed. It is found that the nonadiabatic 1Q1 ← 3Q0 transition plays an important role for Br photofragment in the dissociation of 2-C4H9Br at ∼265 nm. Relative quantum yield of 0.621 for Br(2P3/2) at ∼265 nm in the photodissociation of 2-bromobutane is derived. By comparing the photodissociation of 2-C4H9Br at ∼265 nm and that that at ∼234 nm, the anisotropy parameter β(Br) and β(Br*), and relative quantum yield Φ(Br) decrease with increasing wavelength, the probability of curve crossing between 3Q0 and 1Q1 decreases with increasing laser wavelength.
First-principle Studies on Enhanced Optical Stability of BaMgAl10O17:Eu2+ Phosphor by SiN Doping
Authors: Wang Yi-fei , Wang Yi-fei , Gao Jing-kun , Lee Ming-Hsien , He Wei , Xu Xin , Hao Lu-yuan , Chen Jun-hua
Published: September 2012

Using density functional theory, we studied band structure, density of states, optical properties and Mulliken population of the pure and SiN doped BaMgAl10O17:Eu2+ (BAM:Eu2+) phosphors. Calculation results showed that the bands of BAM:Eu2+ were of low band energy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM:Eu2+ showed stronger absorption intensity while Eu2+ occupied the BR sites instead of the mO sites. The concentration of Eu2+ at BR sites increased while that at mO sites decreased after Si—N doping. The influence of the variation of Eu2+ distribution on the spectra was stronger than the influence of the decrease of Eu2+ PDOS when SiN concentration was lower than 0.25, therefore the absorption and luminescence intensity of BAM:Eu2+ were enhanced. Mulliken population of Si—N bond was higher than Al—O bond, while that of Eu—N bond was higher than Eu—O bond as well, indicating that Si—N bonds and Eu—N bonds possessed higher covalence than Al—O bonds and Eu—N bonds respectively. The existence of Si—N bonds and Eu—N bonds enhanced the local covalence of Eu2+, hence the optical stability of BAM:Eu2+.
First-principles Study of Geometric and Electronic Structures of Si(111)-√7 × √3-In Surface Reconstruction
Authors: Shang Bo , Yuan Lan-feng , Yang Jin-long
Published: September 2012

In order to determine the structures of Si(111)-√7 × √3-In surfaces and to understand their electronic properties, we construct six models of both hexagonal and rectangular types and perform first-principles calculations. Their scanning tunneling microscopic images and work functions are simulated and compared with experimental results. In this way, the hex-H3′ and rect-T1 models are identified as the experimental configurations for the hexagonal and rectangular types, respectively. The structural evolution mechanism of the In/Si(111) surface with indium coverage around 1.0 monolayer is discussed. The 4×1 and √7 × √3 phases are suggested to have two different types of evolution mechanisms, consistent with experimental results.
Nucleation of Kinetic Ising Model under Oscillating Field
Authors: Li Kun , Jiang Hui-jun , Chen Han-shuang , Hou Zhong-huai
Published: September 2012

We have studied the nucleation process of a two-dimensional kinetic Ising model subject to a bias oscillating external field, focusing on how the nucleation time depends on the oscillation frequency. It is found that the nucleation time shows a clear-cut minimum with the variation of oscillation frequency, wherein the average size of the critical nuclei is the smallest, indicating that an oscillating external field with an optimal frequency can be much more favorable to the nucleation process than a constant field. We have also investigated the effect of the initial phase of the external field, which helps to illustrate the occurrence of such an interesting finding.
Coverage-dependent Orientations of Dy@C82 Molecules on Au(111) Surface
Authors: Chen Feng-yun , Hu Zhen-peng
Published: September 2012

The adsorption and molecular orientation of Dy@C82 isomer I on Au(111) has been investigated using ultrahigh-vacuum scanning tunneling microscopy at 80 K. At low coverages, the Dy@C82 molecules tend to grow along the step edges of Au(111), forming small clusters and molecular chains. Adsorption of Dy@C82 on the edges is dominated by the fullerene-substrate interaction and presents various molecular orientations. At higher coverages, the Dy@C82 is found to form ordered islands consisting of small domains of equally oriented molecules. The Dy@C82 molecules in the islands prefer the adsorption configurations with the major C2 axis being approximately parallel to the surface of the substrate. Three preferable orientations of the Dy@C82 molecules are found in a two-dimensional hexagonal close packed overlayer. These observations are attributed to the interplay of the fullerene-substrate interaction and dipole-dipole interaction between the metallofullerenes.
Effect of Potassium Oleate on Rheological Behavior of Cationic Guar in Aqueous Solution with Varying Temperatures
Authors: Wang Qin , Li Hua-zhen , Xie Yong-jun , Li Hua-yu , Yang Hai-yang
Published: September 2012

The rheology of the cationic guar (CG) solution was measured and the effects of potassium oleate (KOA) upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc (corresponding to either storage modulus G′ or loss modulus G″ at the frequency ωc where G′ equals G″) for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time τapp (=1/ωc) increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfactant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.
Nanosized Spinel Li4Ti5O12 Anode Material Prepared by Gel-polymer Method using Furfuryl Alcohol as Polymerizable Solvent
Authors: Ding Chu-xiong , Bai Yao-cai , Wei Cong , Chen Chun-hua
Published: September 2012

Nanosized Li4Ti5O12 powders are synthesized by a polymerization-based method using titanium butoxide and lithium nitrate as precursors and furfuryl alcohol as a polymerizable solvent. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Braunauer-Emmett-Teller (BET) analysis. The electrochemical performances of these Li4Ti5O12 powders are also studied. The effect of different surfactants including citric acid, polyvinylpyrrolidone, and cetyltrimethyl ammonium bromide on the structure and properties is also investigated. It is found that pure spinel phase of Li4Ti5O12 is obtained at an annealing temperature of 700 ï¿½C or higher. The use of surfactants can improve the powder morphology of nanosized particles with less agglomeration. With suitable annealing temperature and the addition of surfactant, Li4Ti5O12 powders with high BET surface area and favorable electrochemical performance can be obtained.
Phase Transition of Poly(acrylic acid-co-N-isopropylacrylamide) Core-shell Nanogels
Authors: Liu Xiao-bing , Zhou Jian-feng , Ye Xiao-dong
Published: September 2012

A series of poly(acrylic acid) macromolecular chain transfer agents with different molecular weights were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by 1H NMR and gel permeation chromatography. Multiresponsive core-shell nanogels were prepared by dispersion polymerization of N-isopropylacrylamide in water using these poly(potassium acrylate) macro-RAFT agents as the electrosteric stabilizer. The size of the nanogels decreases with the amount of the macro-RAFT agent, indicating that the surface area occupied by per polyelectrolyte group is a critical parameter for stabilizing the nanogels. The volume phase transition and the zeta potentials of the nanogels in aqueous solutions were studied by dynamic light scattering and zetasizer analyzer, respectively.
A Green and Mild Approach of Synthesis of Highly-Conductive Graphene Film by Zn Reduction of Exfoliated Graphite Oxide
Authors: Geng Zhi-gang , Zhang Guang-hui , Lin Yue , Yu Xin-xin , Ren Wen-zhen , Wu Yu-kun , Pan Nan , Wang Xiao-ping
Published: September 2012

We report a simple and green approach to synthesize reduced graphene oxide (RGO) nanosheets at room temperature based on Zn reduction of exfoliated GO. The evolution of GO to RGO has been characterized by X-ray diffraction, UV-Vis absorption spectroscopy and Raman spectroscopy. The results of X-ray photoelectron spectroscopy reveal that the atomic ratio of carbon to oxygen in the RGO can be tuned from 1.67 to 13.7 through controlling the reduction time. Moreover, the conductivity of the RGO is measured to be 26.9±2.2 kS/m, much larger than those previously obtained by chemical reduction through other reducing agents. More importantly, the resistance of the RGO film with 20 nm thickness can be as low as 2 kΩ/square, while a high transparency over 70% within a broad spectral range from 0.45 μm to 1.50 μm can be retained. The proposed method is low-cost, eco-friendly and highly-efficient, the as-prepared thinner RGO films are useful in a variety of potential application fields such as optoelectronics, photovoltaics and electrochemistry by serving as an ultralight, flexible and transparent electrode material.
Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement
Authors: Bi Xia , Zuo Jian , Yang Qing
Published: September 2012

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine (OAm) and oleic acid (OA). The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum (SERS) property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.
Effects of carvedilol on heart failure with preserved ejection fraction: the Japanese Diastolic Heart Failure Study (J‐DHF)
Authors: Yamamoto Kazuhiro , Origasa Hideki , Hori Masatsugu ,   on behalf of the J‐DHF Investigators
Published: September 2012

Aims

The therapeutic strategy for heart failure with preserved ejection fraction (HFPEF) has not been established. The Japanese Diastolic Heart Failure Study (J‐DHF) is a multicentre, prospective, randomized, open, blinded‐endpoint trial, designed to assess the effects of carvedilol in HFPEF patients.

Methods and results

A total of 245 patients with heart failure and ejection fraction >40% were randomly assigned into those treated with (carvedilol group, n = 120) and without carvedilol (control group, n = 125). The primary outcome is a composite of cardiovascular death and unplanned hospitalization for heart failure. During a median follow‐up of 3.2 years, the primary endpoint occurred in 29 patients in the carvedilol group and in 34 patients in the control group [adjusted hazard ratio (HR) 0.902, 95% confidence interval (CI) 0.546–1.488, P = 0.6854]. Another major composite endpoint, cardiovascular death and unplanned hospitalization for any cardiovascular causes, occurred in 38 patients of the carvedilol group and 52 patients of the control group (HR 0.768, 95% CI 0.504–1.169; P = 0.2178). The target dose of carvedilol was 20 mg/day, but the median prescribed dose was 7.5 mg/day. In the patients treated with standard doses (carvedilol >7.5 mg/day, n = 58), this composite outcome was significantly less than in the controls (HR 0.539, 95% CI 0.303–0.959; P = 0.0356), whereas it was comparable with the controls in the patients treated with carvedilol ≤7.5 mg/day (n = 62, HR 1.070, 95% CI 0.650–1.763; P = 0.7893).

Conclusions

Carvedilol did not improve prognosis of HFPEF patients overall; however, the standard dose, not the low dose, prescription might be effective. This may facilitate further investigation.

UMIN number: C000000318.
Restoration of dopamine release deficits during object recognition memory acquisition attenuates cognitive impairment in a triple transgenic mice model of Alzheimer's disease
Authors: Guzmán-Ramos Kioko , Moreno-Castilla Perla , Castro-Cruz Monica , McGaugh James L. , Martínez-Coria Hilda , LaFerla Frank M. , Bermúdez-Rattoni Federico
Published: September 2012

Previous findings indicate that the acquisition and consolidation of recognition memory involves dopaminergic activity. Although dopamine deregulation has been observed in Alzheimer's disease (AD) patients, the dysfunction of this neurotransmitter has not been investigated in animal models of AD. The aim of this study was to assess, by in vivo microdialysis, cortical and hippocampal dopamine, norepinephrine, and glutamate release during the acquisition of object recognition memory (ORM) in 5- and 10-mo-old triple-transgenic Alzheimer's disease mice (3xTg-AD) and to relate the extracellular changes to 24-h memory performance. Five- and 10-mo-old wild-type mice and 5-mo-old 3xTg-AD showed significant cortical but not hippocampal dopamine increase during object exploration. On a 24-h ORM test, these three groups displayed significant ORM. In contrast, 10-mo-old 3xTg-AD mice showed impaired dopamine release in the insular cortex during ORM acquisition, as well as significant impairment in ORM. In addition, cortical administration of a dopamine reuptake blocker produced an increase of dopamine levels in the 10-mo-old 3xTg-AD mice and attenuated the memory impairment. These data suggest that activation of the dopaminergic system in the insular cortex is involved in object recognition memory, and that dysfunction of this system contributes to the age-related decline in cognitive functioning of the 3xTg-AD mice.
Spontaneous object recognition memory in aged rats: Complexity versus similarity
Authors: Gámiz Fernando , Gallo Milagros
Published: September 2012

Previous work on the effect of aging on spontaneous object recognition (SOR) memory tasks in rats has yielded controversial results. Although the results at long-retention intervals are consistent, conflicting results have been reported at shorter delays. We have assessed the potential relevance of the type of object used in the performance of aged rats in SOR tasks. Using standard objects, 24-mo-old rats did not exhibit retention impairment at a 1-h delay. At this retention interval no differences between young and old rats were found in a high-similarity SOR task, but aged rats exhibited deficits when clearly different complex forms were applied.
Acclimation of Leaf Nitrogen to Vertical Light Gradient at Anthesis in Wheat Is a Whole-Plant Process That Scales with the Size of the Canopy
Authors: Moreau Delphine , Allard Vincent , Gaju Oorbessy , Le Gouis Jacques , Foulkes M. John , Martre Pierre
Published: September 2012

Vertical leaf nitrogen (N) gradient within a canopy is classically considered as a key adaptation to the local light environment that would tend to maximize canopy photosynthesis. We studied the vertical leaf N gradient with respect to the light gradient for wheat (Triticum aestivum) canopies with the aims of quantifying its modulation by crop N status and genetic variability and analyzing its ecophysiological determinants. The vertical distribution of leaf N and light was analyzed at anthesis for 16 cultivars grown in the field in two consecutive seasons under two levels of N. The N extinction coefficient with respect to light (b) varied with N supply and cultivar. Interestingly, a scaling relationship was observed between b and the size of the canopy for all the cultivars in the different environmental conditions. The scaling coefficient of the b-green area index relationship differed among cultivars, suggesting that cultivars could be more or less adapted to low-productivity environments. We conclude that the acclimation of the leaf N gradient to the light gradient is a whole-plant process that depends on canopy size. This study demonstrates that modeling leaf N distribution and canopy expansion based on the assumption that leaf N distribution parallels that of the light is inappropriate. We provide a robust relationship accounting for vertical leaf N gradient with respect to vertical light gradient as a function of canopy size.
Effects of Reduced Chloroplast Gene Copy Number on Chloroplast Gene Expression in Maize
Authors: Udy Dylan B. , Belcher Susan , Williams-Carrier Rosalind , Gualberto José M. , Barkan Alice
Published: September 2012

Chloroplasts and other members of the plastid organelle family contain a small genome of bacterial ancestry. Young chloroplasts contain hundreds of genome copies, but the functional significance of this high genome copy number has been unclear. We describe molecular phenotypes associated with mutations in a nuclear gene in maize (Zea mays), white2 (w2), encoding a predicted organellar DNA polymerase. Weak and strong mutant alleles cause a moderate (approximately 5-fold) and severe (approximately 100-fold) decrease in plastid DNA copy number, respectively, as assayed by quantitative PCR and Southern-blot hybridization of leaf DNA. Both alleles condition a decrease in most chloroplast RNAs, with the magnitude of the RNA deficiencies roughly paralleling that of the DNA deficiency. However, some RNAs are more sensitive to a decrease in genome copy number than others. The rpoB messenger RNA (mRNA) exhibited a unique response, accumulating to dramatically elevated levels in response to a moderate reduction in plastid DNA. Subunits of photosynthetic enzyme complexes were reduced more severely than were plastid mRNAs, possibly because of impaired translation resulting from limiting ribosomal RNA, transfer RNA, and ribosomal protein mRNA. These results indicate that chloroplast genome copy number is a limiting factor for the expression of a subset of chloroplast genes in maize. Whereas in Arabidopsis (Arabidopsis thaliana) a pair of orthologous genes function redundantly to catalyze DNA replication in both mitochondria and chloroplasts, the w2 gene is responsible for virtually all chloroplast DNA replication in maize. Mitochondrial DNA copy number was reduced approximately 2-fold in mutants harboring strong w2 alleles, suggesting that w2 also contributes to mitochondrial DNA replication.
Developing genomic resources for the common bottlenose dolphin (Tursiops truncatus): isolation and characterization of 153 single nucleotide polymorphisms and 53 genotyping assays
Authors: Vollmer N. L. , Rosel P. E.
Published: September 2012

Although single nucleotide polymorphisms (SNPs) are commonly used in human genetics, they have only recently been incorporated into genetic studies of non‐model organisms, including cetaceans. SNPs have several advantages over other molecular markers for studies of population genetics: they are quicker and more straightforward to score, cross‐laboratory comparisons of data are less complicated, and they can be used successfully with low‐quality DNA. We screened portions of the genome of one of the most abundant cetaceans in U.S. waters, the common bottlenose dolphin (Tursiops truncatus), and identified 153 SNPs resulting in an overall average of one SNP every 463 base pairs. Custom TaqMan® Assays were designed for 53 of these SNPs, and their performance was tested by genotyping a set of bottlenose dolphin samples, including some with low‐quality DNA. We found that in 19% of the loci examined, the minor allele frequency (MAF) estimated during initial SNP ascertainment using a DNA pool of 10 individuals differed significantly from the final MAF after genotyping over 100 individuals, suggesting caution when making inferences about MAF values based on small data sets. For two assays, we also characterized the basis for unusual clustering patterns to determine whether their data could still be utilized for further genetic studies. Overall results support the use of these SNPs for accurate analysis of both poor and good‐quality DNA. We report the first SNP markers and genotyping assays for use in population and conservation genetic studies of bottlenose dolphins.
Role of imbalance of eicosanoid pathways and staphylococcal superantigens in chronic rhinosinusitis
Authors: Pezato R. , Świerczyńska‐Krępa M. , Niżankowska‐Mogilnicka E. , Derycke L. , Bachert C. , Pérez‐Novo C. A.
Published: September 2012

Chronic rhinosinusitis (CRS) is a multifactorial disease of the upper airways with a high prevalence (approximately 11%) in the general population. Different immune and inflammatory mechanisms are involved in its pathogenesis. Alterations in the arachidonic acid pathway (leading to an imbalanced production of eicosanoids) have been linked to the pathophysiology of different diseases especially nasal polyposis, asthma, and aspirin‐exacerbated respiratory disease. Furthermore, viral and bacterial infections have been identified as important factors amplifying the pro‐inflammatory reactions in these pathologies. This review summarizes the impact of an imbalance in the eicosanoid pathway and the effect of Staphylococcus aureus enterotoxins on the regulation of the pro‐inflammatory network in CRS and their translation into disease severity.
Feasibility and clinical effects of laparoscopic abdominal cerclage: an observational study
Authors: RIISKJAER MADS , PETERSEN OLAV B. , ULDBJERG NIELS , HVIDMAN LONE , HELMIG RIKKE B. , FORMAN AXEL
Published: September 2012

Objective. To evaluate the effect of laparoscopic abdominal cerclage performed as an interval procedure in non‐pregnant women at high risk of second trimester spontaneous abortion and early preterm birth. Design. Observational study. Sample. Fifty‐two consecutive patients at high risk of preterm birth. Setting. Department of Obstetrics and Gynecology, Aarhus University Hospital. Methods. Patients were registered prospectively. Indications for surgery included classical cervical insufficiency, preterm premature rupture of membranes (PPROM) or two conizations/cervical amputation. Outcome of subsequent pregnancies was registered. Main outcome measures. Gestational age in subsequent pregnancies. Results. No operative or postoperative complications were observed. A total of 45 pregnancies were registered during the observation period. Among 36 pregnancies lasting beyond the 16th week of gestation, 30 women (83.3%) gave birth by cesarean section after 36 weeks of gestation and the overall mean gestational age was 37.4 weeks compared with a mean gestational age of 25.2 weeks of the pregnancies prior to the cerclage. The cesarean sections were uncomplicated in all but one patient, where a re‐laparotomy was needed six hours later due to atonic postpartum hemorrhage without evident bleeding through the cervix. Conclusion. Laparoscopic abdominal cerclage is a feasible and safe procedure. Obstetrical outcomes are encouraging but prospective studies are needed to define the effectiveness of the laparoscopic cerclage compared with the traditional transvaginal approach.
Systematic review: managing suboptimal treatment responses in autoimmune hepatitis with conventional and nonstandard drugs
Authors: Selvarajah V. , Montano‐Loza A. J. , Czaja A. J.
Published: September 2012

Background

Corticosteroid treatment for autoimmune hepatitis has been shown by randomised controlled clinical trials to ameliorate symptoms, normalise liver tests, improve histological findings and extend survival. Nevertheless, suboptimal responses to corticosteroid treatment still occur.

Aim

To describe the current definitions, frequencies, clinical relevance and treatment options for suboptimal responses, and to discuss alternative medications that have been used off‐label for these occurrences.

Methods

Literature search was made for full‐text papers published in English using the keyword ‘autoimmune hepatitis’. Authors' personal experience and investigational studies also helped to identify important contributions to the literature.

Results

Suboptimal responses to standard therapy include treatment failure (7%), incomplete response (14%), drug toxicity (13%) and relapse after drug withdrawal (50–86%). The probability of a suboptimal response prior to treatment is higher in young patients and in patients with a severe presentation, jaundice, high MELD score at diagnosis, multilobular necrosis or cirrhosis, antibodies to soluble liver antigen, or inability to improve by clinical indices within two weeks or by MELD score within 7 days of conventional corticosteroid treatment. Management strategies have been developed for the adverse responses and nonstandard drugs, including mycophenolate mofetil, budesonide, ciclosporin, tacrolimus, sirolimus and rituximab, are emerging as rescue therapies or alternative frontline agents.

Conclusions

Once diagnosed, the suboptimal response should be treated by a highly individualised and well‐monitored regimen, preferentially using first‐line therapy. Nonstandard drugs warrant consideration as salvage or second‐line therapies.
Sdf‐1 (CXCL12) improves skeletal muscle regeneration via the mobilisation of Cxcr4 and CD34 expressing cells
Authors: Brzoska Edyta , Kowalewska Magdalena , Markowska‐Zagrajek Agnieszka , Kowalski Kamil , Archacka Karolina , Zimowska Małgorzata , Grabowska Iwona , Czerwińska Areta M. , Czarnecka‐Góra Magdalena , Stremińska Władysława , Jańczyk‐Ilach Katarzyna , Ciemerych Maria A.
Published: September 2012

Background information

The regeneration of skeletal muscles involves satellite cells, which are muscle‐specific precursor cells. In muscles, injured either mechanically or as a consequence of a disease, such as muscular dystrophy, local release of the growth factors and cytokines leads to satellite cells activation, proliferation and differentiation of the resulting myoblasts, followed by the formation of new myofibres. Various cell types, such as stem and progenitor cells, originating from other tissues different than the muscle, are also able to follow a myogenic program. Participation of these cells in the repair process depends on their precise mobilisation to the site of the injury.

Results

In this study, we showed that stromal‐derived factor‐1 (Sdf‐1) impacts on the mobilisation of CXC chemokine receptor (Cxcr)4‐positive cells and improves skeletal muscle regeneration. Analysis of isolated and in vitro cultured satellite cells showed that Sdf‐1 did not influence myoblasts proliferation and expression of myogenic regulatory transcription factors but induced migration of the myoblasts in Cxcr4‐dependent ways. This phenomenon was also associated with the increased activity of crucial extracellular matrix modifiers, i.e. metalloproteases Mmp‐2 and Mmp‐9.

Conclusions

Thus, positive impact of Sdf‐1 on muscle regeneration is related to the mobilisation of endogenous cells, that is satellite cells and myoblasts, as well as non‐muscle stem cells, expressing Cxcr4 and CD34.
Extraperitoneal resection of the right colon for locally advanced colon cancer
Authors: Taflampas P. , Moran B. J.
Published: September 2012

Aim  Optimal colon cancer surgery correlates with a reduction in recurrence rate and improved overall prognosis. This technical note describes the extraperitoneal approach for locally advanced right colon cancer.

Method  The retroperitoneal technique, mainly used in pseudomyxoma peritonei resectional surgery, is described in three surgical steps and it is compared with existing surgical approaches for right colon cancer.

Results  This approach has the advantages of early entry in the retroperitoneal plane well away from the tumour, early recognition and protection of the ureter and minimal manipulation of the tumour‐bearing right colon.

Conclusion  Extraperitoneal resection of the right colon for locally advanced colon cancer is technically feasible, safe and achieves tumour‐free retroperitoneal margins.
Hereditary gynaecological malignancies: advances in screening and treatment
Authors: Folkins Ann K , Longacre Teri A
Published: September 2012

In the last two decades there have been significant advances in our understanding of female genital tract tumours. The discovery of BRCA1 and BRCA2 genes in ovarian cancer and the mismatch repair genes in endometrial carcinoma has revolutionized our approach to the diagnosis and screening of women for ovarian and uterine cancers. This review discusses the pathogenesis of these two hereditary syndromes in depth and explains how the molecular genetics is tailoring the manner in which these diseases are diagnosed and potentially treated. Other, less common hereditary conditions associated with gynaecological tract manifestations, such as Cowden syndrome, Peutz–Jeghers syndrome, Gorlin syndrome and hereditary leiomyomatosis and renal cell carcinoma, are also summarized briefly.
Bullous pyoderma gangrenosum: A case report and review of the published work
Authors: Sakiyama Masayuki , Kobayashi Takashi , Nagata Yuiko , Fujimoto Norihiro , Satoh Takahiro , Tajima Shingo
Published: September 2012

Pyoderma gangrenosum (PG) is an ulcerative skin disorder characterized by neutrophilic infiltrations. PG is generally classified into four types: (i) ulcerative; (ii) pustular; (iii) bullous; and (iv) vegetative. Among them, bullous PG is known as a rare type. Herein, we report a case of bullous PG together with a summary of the 12 PG cases treated in our department over the previous 15 years, and we review 38 well‐documented bullous PG cases (65.8% female; aged 18–80 years [mean ± standard deviation, 51.6 ± 16.8]) in the published work, including the present case, from 1972–2011. Although the disease most frequently associated with PG is inflammatory bowel disease, bullous PG is most commonly associated with hematological disorders (25/38, 65.8%), which indicates the characteristic pathophysiology specific to bullous PG.
Pharmacological treatments in pathological gambling
Authors: Grant Jon E. , Odlaug Brian L. , Schreiber Liana R. N.
Published: September 2012

Pathological gambling (PG) is a relatively common and often disabling psychiatric condition characterized by intrusive urges to engage in deleterious gambling behaviour. Although common and financially devastating to individuals and families, there currently exist no formally approved pharmacotherapeutic interventions for this disorder. This review seeks to examine the history of medication treatments for PG. A systematic review of the 18 double‐blind, placebo‐controlled pharmacotherapy studies conducted for the treatment of pathological gambling was conducted. Study outcome and the mean dose of medication administered was documented in an effort to determine a preferred medication choice in this population. A variety of medication classes have been examined in the treatment of PG with varying results. Antidepressants, atypical antipsychotics and mood stabilizers have demonstrated mixed results in controlled clinical trials. Although limited information is available, opioid antagonists and glutamatergic agents have demonstrated efficacious outcomes, especially for individuals with PG suffering from intense urges to engage in the behaviour. Given that several studies have demonstrated their efficacy in treating the symptoms associated with PG, opioid antagonists should be considered the first line treatment for PG at this time. Most published studies, however, have employed relatively small sample sizes, are of limited duration and involve possibly non‐representative clinical groups (e.g. those without co‐occurring psychiatric disorders). Response measures have varied across studies. Heterogeneity of PG treatment samples may also complicate identification of effective treatments. Identification of factors related to treatment response will help inform future studies and advance treatment strategies for PG.