bluuebunny/crossref_metadata_2025 huggingface dataset:
The Los Alamos Neutron Science Center neutron rheometer in the cone and plate geometry to examine tethered polymers/polymer melt interfaces via neutron reflectivity
Authors: Sasa Leslie A. , Yearley Eric J. , Welch Cynthia F. , Taylor Mark A. , Gilbertson Robert D. , Hammeter Christopher , Majewski Jaroslaw , Hjelm Rex P.
Published: May 2010

Although several other neutron rheometers have been built to study soft matter under nonequilibrium conditions, none of them have the ability to measure the structure and behavior of the polymeric interfacial regions in highly viscous polymer melts which require high torques/high strain rates and high temperatures. A neutron rheometer in the cone and plate geometry has been constructed at the Los Alamos Neutron Science Center to rectify this lack of experimental instrumentation. It is also the first-of-its-kind to perform neutron reflectivity studies concurrently with rheological measurements. The details of both the development and testing of the Los Alamos Neutron Science Center neutron rheometer in the cone and plate configuration are described. Proof of principle neutron reflectivity results of end-grafted polystyrene against an identical melt under shear are presented, showing qualitatively that the structural attributes of the end-grafted polymer change when exposed to shear.
X-ray microfabrication and measurement of a terahertz mode converter
Authors: Chang T. H. , Shew B. Y. , Wu C. Y. , Chen N. C.
Published: May 2010

Mode converters are critical for frequency-tunable terahertz gyrotrons. This study reports the development of a broadband TE02 mode converter centered at 0.2 THz. An octafeed sidewall coupling structure was employed and the mode purity was analyzed. The converter was built using the technique of x-ray microfabrication. The x rays irradiated on the SU-8 resist and generated a template of very high thickness of 1.295 mm. Pulse electroplating technique was used to deposit copper on the structure along the template. The parts then went through precise machining and the residual resist was removed via high-flux radical etching. A computer-aided diagnostic system was introduced to measure the performance of the converter. Results suggest that the frequency response of resistivity should be taken into consideration for the devices in terahertz region.
Formation of cold ion-neutral clusters using superfluid helium nanodroplets
Authors: Falconer Travis M. , Lewis William K. , Bemish Raymond J. , Miller Roger E. , Glish Gary L.
Published: May 2010

A strategy for forming and detecting cold ion-neutral clusters using superfluid helium nanodroplets is described. Sodium cations generated via thermionic emission are directed toward a beam of helium droplets that can also pick up neutral molecules and form a cluster with the captured Na+. The composition of the clusters is determined by mass spectrometric analysis following a desolvation step. It is shown that the polar molecules H2O and HCN are picked up and form ion-neutral clusters with sizes and relative abundances that are in good agreement with those predicted by the statistics used to describe neutral cluster formation in helium droplets. [Na(H2O)n]+ clusters containing six to 43 water molecules were observed, a size range of sodiated water clusters difficult to access in the gas phase. Clusters containing N2 were in lower abundance than expected, suggesting that the desolvation process heats the clusters sufficiently to dissociate those containing nonpolar molecules.
Strategies for state space restriction in densely coupled spin systems with applications to spin chemistry
Authors: Hogben H. J. , Hore P. J. , Kuprov Ilya
Published: May 2010

We propose three basis screening methods for state space restriction in Liouville space simulations of large densely coupled spin systems encountered in electron paramagnetic resonance (EPR) spectroscopy and spin chemistry. The methods are based on conservation law analysis, symmetry factorization, and the analysis of state space connectivity graphs. A reduction in matrix dimensions by several orders of magnitude is demonstrated for common EPR and spin chemistry systems.
A reactive molecular dynamics simulation of the silica-water interface
Authors: Fogarty Joseph C. , Aktulga Hasan Metin , Grama Ananth Y. , van Duin Adri C. T. , Pandit Sagar A.
Published: May 2010

We report our study of a silica-water interface using reactive molecular dynamics. This first-of-its-kind simulation achieves length and time scales required to investigate the detailed chemistry of the system. Our molecular dynamics approach is based on the ReaxFF force field of van Duin et al. [J. Phys. Chem. A 107, 3803 (2003)]. The specific ReaxFF implementation (SERIALREAX) and force fields are first validated on structural properties of pure silica and water systems. Chemical reactions between reactive water and dangling bonds on a freshly cut silica surface are analyzed by studying changing chemical composition at the interface. In our simulations, reactions involving silanol groups reach chemical equilibrium in ∼250 ps. It is observed that water molecules penetrate a silica film through a proton-transfer process we call “hydrogen hopping,” which is similar to the Grotthuss mechanism. In this process, hydrogen atoms pass through the film by associating and dissociating with oxygen atoms within bulk silica, as opposed to diffusion of intact water molecules. The effective diffusion constant for this process, taken to be that of hydrogen atoms within silica, is calculated to be 1.68×10−6 cm2/s. Polarization of water molecules in proximity of the silica surface is also observed. The subsequent alignment of dipoles leads to an electric potential difference of ∼10.5 V between the silica slab and water.
An efficient algorithm to accelerate the discovery of complex material formulations
Authors: Brell George , Li Genyuan , Rabitz Herschel
Published: May 2010

The identification of complex multicomponent material formulations that possess specific optimal properties is a challenging task in materials discovery. The high dimensional composition space needs to be adequately sampled and the properties measured with the goal of efficiently identifying effective formulations. This task must also take into account mass fraction and possibly other constraints placed on the material components. Either combinatorial or noncombinatorial sampling of the composition space may be employed in practice. This paper introduces random sampling-high dimensional model representation (RS-HDMR) as an algorithmic tool to facilitate these nonlinear multivariate problems. RS-HDMR serves as a means to accurately interpolate over sampled materials, and simulations of the technique show that it can be very efficient. A variety of simulations is carried out modeling multicomponent→property relationships, and the results show that the number of sampled materials to attain a given level of accuracy for a predicted property does not significantly depend on the number of components in the formulation. Although RS-HDMR best operates in the laboratory by guided iterative rounds of random sampling of the composition space along with property observation, the technique was tested successfully on two existing databases of a seven component phosphor material and a four component deNOx catalyst for reduction of NO with C3H6.
Phase behavior of symmetric disk-coil molecules
Authors: Kim Yongjoo , Alexander-Katz Alfredo
Published: May 2010

We investigate the self-assembly of symmetric disk-coil molecules using Monte Carlo simulations in the NPT ensemble. Our molecules are composed of a planar disk (head) that is covalently bonded to a single coil (tail), and can be regarded as disk-coil copolymers. For this system, we observe a variety of phases depending on the temperature and the effective interactions between the disk and coil regions. In particular, we find a disordered, a lamellar, a perforated lamellar, and a crystal phase. Furthermore, the orientational correlation (or ordering) of the disks within the crystal phase is found to be stronger compared to the pure disk case, which we also explicitly simulate. The enhanced order is due to the confinement imposed by the mesophase formation. Our results are relevant for organic photoactive (typically planar) molecules that are functionalized with alkyl tails to improve their processing properties as well as their long-range order in the solid phase, and can also help to rationalize some biologically observed phases of chlorophyll seen in the photosynthetic apparatus of green bacteria.
Conformation of a tethered polymer in a leaky nanocavity
Authors: Nakamura Issei , Shi An-Chang
Published: May 2010

The conformation of an ideal polymer chain confined in a box with a D×D hole is studied by N-step random walk simulations. For a polymer chain tethered inside the box, three conformational states are observed when the chain length is increased. For short chains the polymer assumes “mushroom” configurations. Increasing the chain length leads to a state in which the polymer fills the box. When the chain is long enough, the polymer escapes from the box, assuring an overall random walk state. Probability distributions of the free end and end-to-end distance are used to characterize polymer conformations. The escape transition is determined by the disappearance of the bimodal feature in the end-to-end probability density function. A crossover of the free energy difference between the confined and escaped states signals an escape transition analogous to the coil-globule transition of a free ideal chain.
Possible states in the flow around two circular cylinders in tandem with separations in the vicinity of the drag inversion spacing
Authors: Carmo B. S. , Meneghini J. R. , Sherwin S. J.
Published: May 2010

The possible states in the flow around two identical circular cylinders in tandem arrangements are investigated for configurations in the vicinity of the drag inversion separation. By means of numerical simulations, the hysteresis in the transition between the shedding regimes is studied and the relationship between (three-dimensional) secondary instabilities and shedding regime determination is addressed. The differences observed in the behavior of two- and three-dimensional flows are analyzed, and the regions of bistable flow are delimited. Very good agreement is found between the proposed scenario and results available in the literature.
Climate relationships with tree-ring width and δ13C of three Callitris species from semiarid woodlands in south-western Australia
Authors: Sgherza Ciaran , Cullen Louise E. , Grierson Pauline F.
Published: May 2010

Proxy measures of climate based on tree rings can allow reconstruction of climate back past the limit of instrumental records, thereby improving understanding of natural climate variability. We assessed the dendroclimatic potential of tree-ring widths and δ13C of three broadly co-occurring species of Callitris in south-western Western Australia. Ring width chronologies of C. columellaris F.Muell., C. canescens (Parl.) S.T. Blake and C. preissii Miq. met standard measures of dendrochronological acceptability. For all three species, the Expressed Population Signal (EPS) was >0.93 and mean correlations between series in each chronology was >0.79. In contrast, δ13C chronologies were of poorer statistical quality (EPS ranged 0.59 to 0.88, mean correlations ranged 0.33 to 0.65) with both less year-to-year and lower-frequency information (lower mean sensitivity and standard deviation values). The dominant climatic signal in the ring width chronologies was related to rainfall and was strongest over the March–September season (correlations ranged 0.27 to 0.70, all P < 0.05). Consistent with the poorer quality of the δ13C chronologies compared with those from ring widths, tree-ring δ13C was also less strongly correlated with rainfall and rarely significant (P = 0.05). The weaker δ13C correlations may be due to a strong water conservation strategy by Callitris. Our analysis of the whole ring rather than latewood and low sampling effort may also have dampened the δ13C response. However, combining the ring width and δ13C chronologies using Principal Components Analysis did not enhance the extraction of a climatic signal. While the variance explained by the first principal component (PC) was high for all three species (76 to 87%), correlations between the first PC and rainfall were not stronger than for ring widths alone. Tree-ring δ13C, in conjunction with δ18O in particular, may nevertheless provide insight into physiological responses of Callitris to climate variation. However, dendroclimatic studies using Callitris to develop past rainfall records should focus on developing chronologies from ring widths. Further effort to find sites with old trees (250 years or more) should be undertaken and are likely to provide much needed information on past rainfall in Australia.
The influences of device geometry and p-type doping on a solution-processed polymer space-charge-limited transistor
Authors: Chao Yu-Chiang , Chen Chun-Yu , Zan Hsiao-Wen , Meng Hsin-Fei
Published: May 2010

A polymer vertical transistor with an on/off current ratio higher than 104 is demonstrated. The proposed space-charge limited transistor (SCLT) uses a metal-grid base containing high-density submicrometre openings to modulate the vertical space-charge-limited current (SCLC). The key to obtaining a high on/off current ratio is to reduce the leakage current of SCLT. In this paper, an improved device structure that isolates the grid metal by using both top and bottom insulating layers is demonstrated. Then, with an identical proposed structure, the geometric design is also found to significantly influence the on/off ratio over 3 orders of magnitude. The competition between the SCLC and the grid to collector leakage current is analysed. Finally, the influence of tetrafluoro-tetracyano-quinodimethane doping on the transistor characteristics is investigated. The results are important for the design of polymer vertical transistors with high on/off ratios.
A very simple and chromatic-stable white organic light-emitting diode with a colour conversion hole injection layer based on solution process
Authors: Zhu Wenqing , Wang Qiang , Li Bo , Zhang Xiaowen , Lu Lin , Wei Bin , Zhang Jianhua , Li Chong
Published: May 2010

A chromatic-stable and easily fabricated white organic light-emitting diode with a colour conversion hole injection layer (CC-HIL) has been investigated. The emission layer (EML) was composed of the fluorescent dye p-bis(p − N,N-diphenyl-aminostyryl)benzene doped into the host 2-(t-butyl)-9,10-di(2-naphthyl)anthracene. A red fluorescent polymer poly(2-methoxy-5-[2′-ethylhexyloxy]-p-phenylenevinylene) (MEH-PPV) with hole transport characteristics and relatively high absorbance to blue electroluminescence was used as the CC-HIL. The CIE colour coordinates at (0.33, 0.35) almost remained unchanged under driving current densities from 20 mA cm−2 to 400 mA cm−2 while the current efficiencies reached 3.5 cd A−1 and 4.65 cd A−1 at 20 mA cm−2 and 400 mA cm−2, respectively. The improved performance was attributed mainly to an enhanced out-coupling efficiency and better carrier balance in the EML.
Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures
Authors: Mao M , Bogaerts A
Published: May 2010

A hybrid model, called the hybrid plasma equipment model (HPEM), was used to study an inductively coupled plasma in gas mixtures of H2 or NH3 with CH4 or C2H2 used for the synthesis of carbon nanotubes or carbon nanofibres (CNTs/CNFs). The plasma properties are discussed for different gas mixtures at low and moderate pressures, and the growth precursors for CNTs/CNFs are analysed. It is found that C2H2, C2H4 and C2H6 are the predominant molecules in CH4 containing plasmas besides the feedstock gas, and serve as carbon sources for CNT/CNF formation. On the other hand, long-chain hydrocarbons are observed in C2H2-containing plasmas. Furthermore, the background gases CH4 and C2H2 show a different decomposition rate with H2 or NH3 addition at moderate pressures.
Structural improvement of zinc oxide films produced by ion beam assisted reactive sputtering
Authors: Köhl D , Luysberg M , Wuttig M
Published: May 2010

Reactively sputtered zinc oxide thin films exhibit low crystalline order when deposited on unheated substrates. To improve the structural order, films are usually deposited onto heated substrates at temperatures of about 200–300 °C. Nevertheless, techniques that enable room temperature deposition of ZnO films with high structural quality would be advantageous. In this work ion bombardment from an auxiliary ion gun during film growth is employed to improve the crystalline quality. Xe+ ion bombardment under appropriate conditions leads to the growth of films with high crystalline order. Based on our structural investigations employing x-ray diffraction, atomic force microscopy and transmission electron microscopy, a growth model is proposed which explains the impact of ion bombardment on the structural evolution. We prove that it is especially the nucleation stage of the growth process which is susceptible to this ion bombardment.
Properties of morphotropic phase boundary Pb(Mg1/3Nb2/3)O3–PbTiO3 films with submicrometre range thickness on Si-based substrates
Authors: Algueró M , Stewart M , Cain M G , Ramos P , Ricote J , Calzada M L
Published: May 2010

The electrical properties of (1 − x)Pb(Mg1/3 Nb2/3)O3 − xPbTiO3 films with composition in the morphotropic phase boundary region around x = 0.35, submicrometre thickness and columnar microstructure, prepared on Si-based substrates by chemical solution deposition are presented and discussed in relation to the properties of coarse and fine grained ceramics. The films show relaxor characteristics that are proposed to result from a grain size effect on the kinetics of the relaxor to ferroelectric transition. The transition is slowed down for grain sizes in the submicrometre range, and as a consequence intermediate polar domain configurations with typical length scales in the submicrometre- and nanoscales are stabilized. A high saturation polarization can be attained under field, but fast polarization relaxation occurs after its removal, and negligible remanent values are obtained. At the same time, they also show spontaneous piezoelectricity and pyroelectricity. Self-polarization is thus present, which indicates the existence of an internal electric field that is most probably a substrate effect. Films would then be in a phase instability, at an intermediate state between the relaxor and ferroelectric ones, and under a bias electric field, which would explain the very high spontaneous pyroelectric response found.
ICRH beatwave excited toroidicity induced Alfvén eigenmodes in ASDEX Upgrade
Authors: Sassenberg K. , Maraschek M. , Carthy P.J. Mc , Bobkov W. , García-Muñoz M. , Hicks N. , Igochine V. , Lauber P. , Günter S.
Published: May 2010

Experimental evidence is presented demonstrating that an ion cyclotron resonance heating (ICRH) beatwave can drive toroidicity induced Alfvén eigenmodes (TAEs) to a finite amplitude and also increase the amplitude of TAEs already excited by fast ions. The radial structure of a beatwave driven TAE reconstructed from soft x-ray measurements is shown to agree with simulations from the gyro-kinetic code LIGKA. Thus beatwaves provide the means to excite TAEs which can be used to diagnose the plasma's safety factor profile through MHD-spectroscopic techniques without significantly perturbing the plasma or to influence the stability of existing TAEs allowing their effect on the fast ion population to be studied.
Hydrogenic retention of high-Z refractory metals exposed to ITER divertor-relevant plasma conditions
Authors: Wright G.M. , Alves E. , Alves L.C. , Barradas N.P. , Carvalho P.A. , Mateus R. , Rapp J.
Published: May 2010

Tungsten (W) and molybdenum (Mo) targets are exposed to the plasma conditions expected at the strike point of a detached ITER divertor (n
e ∼ 1020 m−3, T
e ∼ 2 eV) in the linear plasma device Pilot-PSI. The peak surface temperatures of the targets are ∼1600 K for W and ∼1100 K for Mo. The surface temperatures and plasma flux densities decrease radially towards the edges of the target due to the Gaussian distribution of electron density (n
e) and temperature (T
e) in the plasma column. A 2D spatial scan of the W and Mo targets using nuclear reaction analysis (NRA) shows D retention is strongly influenced by surface temperature in the range 800–1600 K and this dependence dominates over any plasma flux dependence. NRA and thermal desorption spectroscopy (TDS) show no clear dependence of retention on incident plasma fluence for the W targets with retained fractions ranging from 10−8–10−5
D
retained/D
incident. NRA and TDS for the Mo targets show retention rates a factor of 4–5 higher than the W targets and this is likely due to the lower surface temperatures for the Mo plasma exposures. NRA also reveals a thin boron layer on the Mo targets but the presence of boron does not correspond to a significant increase in D retention. Overall hydrogenic retention in W and Mo is shown to be low (D
retained = 1019–1020 D m−2) despite exposure to high plasma flux densities (∼1024 D m−2 s−1). This is likely due to the elevated surface temperature due to plasma thermal loading during exposure.
Drosophila Histone Deacetylase 6 Protects Dopaminergic Neurons against α-Synuclein Toxicity by Promoting Inclusion Formation
Authors: Du Guiping , Liu Xiang , Chen Xinping , Song Mei , Yan Yan , Jiao Renjie , Wang Chih-chen
Published: May 2010

Parkinson's disease (PD) is associated with progressive degeneration of dopaminergic (DA) neurons. We report for the first time that the Drosophila histone deacetylase 6 (dHDAC6) plays a critical role in the protection of DA neurons and the formation of α-synuclein inclusions by using a Drosophila PD model constructed by ectopic expression of human α-synuclein. Depletion of dHDAC6 significantly enhances the effects caused by ectopic expression of α-synuclein, namely, loss of DA neurons, retinal degeneration, and locomotor dysfunction. Expression of α-synuclein in the DA neurons leads to fewer inclusions in the brains of dHDAC6 mutant flies than in wild-type flies. Conversely, overexpression of dHDAC6 is able to suppress the α-synuclein–induced DA neuron loss and retinal degeneration and promote inclusion formation. Furthermore, mutation of dHDAC6 reinforces the accumulation of oligomers that are suggested to be a toxic form of α-synuclein. We propose that α-synuclein inclusion formation in the presence of dHDAC6 protects DA neurons from being damaged by oligomers, which may uncover a common mechanism for synucleinopathies.
Novel Screening Assay Performance in Pediatric Celiac Disease and Adult Dermatitis Herpetiformis
Authors: Jaskowski Troy D , Donaldson Matthew R , Hull Christopher M , Wilson Andrew R , Hill Harry R , Zone John J , Book Linda S
Published: May 2010

Objectives:

Several serologic assays are commercially available to aid in the diagnosis of gluten‐sensitive enteropathy (GSE). Our objective in this study was to assess the performance of a novel combined antigen‐screening assay for GSE.

Patients and Methods:

Deidentified sera from 111 pediatric patients suspected of having celiac disease (CD), 130 adults diagnosed with dermatitis herpetiformis (DH), and 77 pediatric and 49 adult normal controls were included in the study. Sera from 10 patients submitted to our laboratory for GSE testing with IgA deficiency and IgG antibodies against 1 or more of the traditional serologic markers associated with GSE were also included. All sera were screened for antibodies (IgA and IgG) against tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP) by enzyme immunoassay (EIA) in a single test well. In addition, all sera were assessed for each individual marker and isotype using separate EIAs.

Results:

The IgA/IgG anti‐tTG/DGP EIA screen was 92.6% sensitive and 94.3% specific in pediatric CD and detected 1 patient (Marsh 3c) who was IgA anti‐tTG negative; this patient was not IgA deficient (<7.0 mg/dL). All 10 IgA‐deficient sera gave positive results by the tTG/DGP EIA screen. Sensitivity and specificity of the tTG/DGP EIA screen in retrospective and prospective DH were 65% and 100% versus 62% and 100%, respectively.

Conclusions:

The new IgA/IgG anti‐tTG/DGP EIA screen was slightly more sensitive than IgA anti‐tTG alone in pediatric CD. This novel screening assay may allow the current recommendation of measuring total serum IgA in suspected GSE patients to be eliminated.
VSL#3 Improves Symptoms in Children With Irritable Bowel Syndrome: A Multicenter, Randomized, Placebo‐Controlled, Double‐Blind, Crossover Study
Authors: Guandalini Stefano , Magazzù Giuseppe , Chiaro Andrea , La Balestra Valeria , Di Nardo Giovanni , Gopalan Sarath , Sibal A , Romano Claudio , Canani Roberto Berni , Lionetti Paolo , Setty Mala
Published: May 2010

Background and Objectives:

Irritable bowel syndrome (IBS) is a common problem in pediatrics, for which no safe and effective treatment is available. Probiotics have shown some promising results in adult studies, but no positive study has been published on pediatric age. We aimed at investigating the efficacy of VSL#3 in a population of children and teenagers affected by IBS, in a randomized, double‐blind, placebo‐controlled, crossover study conducted in 7 pediatric gastroenterology divisions.

Patients and Methods:

Children 4 to 18 years of age, meeting eligibility criteria, were enrolled. The patients were assessed by a questionnaire for a 2‐week baseline period. They were then randomized to receive either VSL#3 or a placebo for 6 weeks, with controls every 2 weeks. At the end, after a “wash‐out” period of 2 weeks, each patient was switched to the other group and followed for a further 6 weeks.

Results:

A total of 59 children completed the study. Although placebo was effective in some of the parameters and in as many as half of the patients, VSL#3 was significantly superior to it (P < 0.05) in the primary endpoint, the subjective assessment of relief of symptoms; as well as in 3 of 4 secondary endpoints: abdominal pain/discomfort (P < 0.05), abdominal bloating/gassiness (P < 0.05), and family assessment of life disruption (P < 0.01). No significant difference was found (P = 0.06) in the stool pattern. No untoward adverse effect was recorded in any of the patients.

Conclusions:

VSL#3 is safe and more effective than placebo in ameliorating symptoms and improving the quality of life in children affected by IBS.
Extraintestinal Manifestations of Pediatric Inflammatory Bowel Disease and Their Relation to Disease Type and Severity
Authors: Dotson Jennifer L , Hyams Jeffrey S , Markowitz James , LeLeiko Neal S , Mack David R , Evans Jonathan S , Pfefferkorn Marian D , Griffiths Anne M , Otley Anthony R , Bousvaros Athos , Kugathasan Subra , Rosh Joel R , Keljo David , Carvalho Ryan S , Tomer Gitit , Mamula Petar , Kay Marsha H , Kerzner Benny , Oliva‐Hemker Maria , Langton Christine R , Crandall Wallace
Published: May 2010

Objectives:

Although it is known that extraintestinal manifestations (EIMs) commonly occur in pediatric inflammatory bowel disease (IBD), little research has examined rates of EIMs and their relation to other disease‐related factors in this population. The purpose of this study was to determine the rates of EIMs in pediatric IBD and examine correlations with age, sex, diagnosis, disease severity, and distribution.

Patients and Methods:

Data were prospectively collected as part of the Pediatric IBD Collaborative Research Group Registry, an observational database enrolling newly diagnosed IBD patients <16 years old since 2002. Rates of EIM (occurring anytime during the period of enrollment) and the aforementioned variables (at baseline) were examined. Patients with indeterminate colitis were excluded from the analysis given the relatively small number of patients.

Results:

One thousand nine patients were enrolled (mean age 11.6 ± 3.1 years, 57.5% boys, mean follow‐up 26.2 ± 18.2 months). Two hundred eighty‐five (28.2%) patients experienced 1 or more EIMs. Eighty‐seven percent of EIM occurred within the first year. Increased disease severity at baseline (mild vs moderate/severe) was associated with the occurrence of any EIM (P < 0.001), arthralgia (P = 0.024), aphthous stomatitis (P = 0.001), and erythema nodosum (P = 0.009) for both Crohn disease (CD) and ulcerative colitis (UC) during the period of follow‐up. Statistically significant differences in the rates of EIMs between CD and UC were seen for aphthous stomatitis, erythema nodosum, and sclerosing cholangitis.

Conclusions:

EIMs as defined in this study occur in approximately one quarter of pediatric patients with IBD. Disease type and disease severity were commonly associated with the occurrence of EIMs.
Influence of Gestational Age, Cesarean Section, and Type of Feeding on Fecal Human β‐Defensin 2 and Tumor Necrosis Factor‐α
Authors: Richter Markus , Topf Hans‐Georg , Gröschl Michael , Fröhlich Thorsten , Tzschoppe Anja , Wenzl Tobias G , Köhler Henrik
Published: May 2010

Objective:

Development of the mucosal immune system is essential for controlling antigenic response. External factors are known to influence the immune system, such as breast‐feeding or the mode of delivery. The aim of the present study was to investigate maturation of the enteric immune system.

Patients and Methods:

In stool samples of 59 preterm and term‐born infants we measured the concentration of human β‐defensin 2 (HBD 2), an endogenous antimicrobial peptide, and tumor necrosis factor‐α (TNF‐α), a cytokine playing a central role in mucosal inflammation, by enzyme‐linked immunosorbent assay.

Results:

Mode of delivery as well as nutrition (breast‐feeding or formula) had no influence on the fecal concentration of HBD‐2 or TNF‐α, but there was a significant increase in the concentration of HBD‐2 in correlation with gestational age. TNF‐α showed no change in concentration.

Conclusions:

Low fecal HBD‐2 may be a risk factor in preterm infants to develop neonatal enteric disease, such as necrotizing enterocolitis.
Symmetry analysis of extinction rules in diffuse-scattering experiments
Authors: Withers R. L. , Aroyo M. I. , Perez-Mato J. M. , Orobengoa D.
Published: May 2010

Structured diffuse-scattering intensities, whether of compositional or of pure displacive origin, static or dynamic, contain important information about the symmetry of the individual compositional and/or displacive modes responsible for the observed intensities. However, the interpretation of the experimental data is very often impeded by the lack of a symmetry-based approach to the analysis of the structured diffuse-scattering distributions. Recently, we have demonstrated the existence of systematic phonon selection rules for diffuse scattering that depend on the symmetries of the mode and the scattering vector, and not on the specific structure. Here, we show that such symmetry analysis can be successfully extended and also applied to structure-dependent diffuse scattering associated with `disordered' materials: the combination of theoretically determined, diffuse-scattering extinction conditions with the concept of non-characteristic orbits proves to be very useful in the interpretation of the observed diffuse-scattering extinctions. The utility of this approach is illustrated by the analysis of diffuse-scattering data from ThAsSe, FeOF and FeF2. The essential part of the associated calculations are performed by the computer programsNEUTRON(systematic phonon extinction rules in inelastic scattering) andNONCHAR(non-characteristic orbits of space groups) that are available on the Bilbao crystallographic server (http://www.cryst.ehu.es).
Oral non-typable Haemophilus influenzae enhances physiological mechanism of airways protection
Authors: Clancy R L , Dunkley M L
Published: May 2010

Oral immunotherapy with inactivated non-typeable Haemophilus influenzae (NTHi) prevents exacerbations of chronic obstructive pulmonary disease, but the mechanism is unclear. The aim of this study was to determine the mechanism of protection. This was a placebo versus active prospective study over 3 months in 64 smokers. The active treatment was three courses of oral NTHi given at monthly intervals, followed by measurement of bacteriological and immunological parameters. The results can be summarized: (i) NTHi-specific T cells increased in the placebo treatment group over time (P < 0·05); (ii) the T cell response in the oral NTHi group started earlier than that in the placebo group (P < 0·05); and (iii) serum NTHi-specific immunoglobulin (Ig)G had significantly greater variation in the placebo group (P < 0·0001). The increase in antibody in placebos over time correlated with exposure to live H. influenzae (P < 0·05) determined from culture of gargles; (iv) reduction in saliva lysozyme over time (P < 0·05) was detected only in the oral NTHi treatment group. These data are consistent with T cell priming of gut lymphoid tissue by aspiration of bronchus content into the gut, with oral immunotherapy augmenting this process leading to enhanced bronchus protection. The evidence for protection was a stable IgG antibody level through the study in the oral NTHi treatment group, contrasting with an increase in antibody correlating with exposure of the airways to H. influenzae in the placebo group. Saliva lysozyme was a useful biomarker of mucosal inflammation, falling after oral NTHi consistent with a reduction in the level of intralumenal inflammation.
The outcome of retained instrument removal in a specialist practice
Authors: Cujé J. , Bargholz C. , Hülsmann M.
Published: May 2010

Cujé J, Bargholz C, Hülsmann M. The outcome of retained instrument removal in a specialist practice. International Endodontic Journal, 43, 545–554, 2009.

Aim  To determine the success rate of a microendodontic technique for the removal of fractured instruments from root canals.

Methodology  Removal was attempted on a total of 170 consecutive referral cases with fractured instruments. All removal attempts were performed using an operating microscope and ultrasonic tips using a technique described by Ruddle (2003).

Results  Of the 170 fractured instruments, 162 could be removed without perforation of the root canal, corresponding to a success rate of 95%. At a failure rate of 5%, eight instruments could not be removed, with root wall perforation occurring in one case. The lowest success rate of 93% was found in maxillary molars, the highest success rate of 100% in maxillary premolars and anterior and canine teeth of the maxillary and mandibular jaw. All removal failures occurred in cases where the fractured instruments were located apically or in the middle and apical part of the root. Regarding the angle of root canal curvature, the lowest success rates were found between 21° and 50°.

Conclusions  The position of the instrument within the root canal, the angle of the curvature of the root canal and the location of the fractured instrument in relation to the root canal curvature were the decisive factors that had a negative influence on the treatment outcome.The removal method tested represents a highly effective technique for the retrival of fractured instruments.
Prostaglandin F2α stimulates MEK‐ERK signalling but decreases the expression of alkaline phosphatase in dental pulp cells
Authors: Chang M. C. , Chen Y. J. , Lee M. Y. , Lin L. D. , Wang T. M. , Chan C. P. , Tsai Y. L. , Wang C. Y. , Lin B. R. , Jeng J. H.
Published: May 2010

Chang MC, Chen YJ, Lee MY, Lin LD, Wang TM, Chan CP, Tsai YL, Wang CY, Lin BR, Jeng JH. Prostaglandin F2α stimulates MEK‐ERK signalling but decreases the expression of alkaline phosphatase in dental pulp cells. International Endodontic Journal, 43, 461–468, 2010.

Aim  To study prostaglandin F2α (PGF2α) receptor expression and downstream signalling in cultured human dental pulp cells and the effect of PGF2α on the alkaline phosphatase (ALP) activity of dental pulp cells.

Methodology  Human dental pulp cells were cultured and exposed to PGF2α. The expression of PGF2α (FP) receptors was analysed by reverse transcriptase polymerase chain reaction (RT‐PCR) and Western blotting. The activation of extracellular regulated kinase (ERK) and cAMP responsive element binding protein/activating transcription factor‐1 (CREB/ATF‐1) signalling was determined by Western blotting. The expression of ALP in pulp cells after exposure to PGF2α was evaluated by ALP staining and PCR.

Results  Dental pulp cells expressed FP receptor mRNA and protein. Exposure to PGF2α revealed little cytotoxicity to pulp cells. PGF2α induced both ERK and CREB/ATF‐1 phosphorylation in pulp cells. Exposure to PGF2α (>1 μmol L−1) further decreased the ALP activity and mRNA expression. However, U0126 (an inhibitor of MEK1) showed little preventive effect on the decline of ALP activity in dental pulp cells by PGF2α.

Conclusion  PGF2α may potentially activate FP receptors leading to ERK/CREB‐ATF‐1 activation during its production in inflamed dental pulp. PGF2α attenuated the ALP activity of pulp cells possibly via pathways not solely by MEK/ERK activation. PGF2α is a contributing factor of pulpal inflammation by regulating the activities of pulp cells.
Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolars
Authors: Bitter K. , Meyer‐Lueckel H. , Fotiadis N. , Blunck U. , Neumann K. , Kielbassa A. M. , Paris S.
Published: May 2010

Bitter K, Meyer‐Lueckel H, Fotiadis N, Blunck U, Neumann K, Kielbassa AM, Paris S. Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolars. International Endodontic Journal, 43, 469–477, 2010.

Aim  To investigate the effects of endodontic treatment, post placement and ceramic restoration type on the fracture resistance of premolars.

Methodology  One hundred and twenty teeth maxillary premolars were allocated to four groups (A–D; n = 30). In group A, mesio‐occlusal‐distal‐inlays with a buccal and palatal wall of 2 mm (MOD), in group B partial onlays with palatal cusp coverage and in group C total onlays with buccal and palatal cusp coverage were prepared. Group D served as untreated controls. Groups A–C were divided into three subgroups (n = 10): (i) teeth received solely the described preparations, (ii) teeth were root filled, (iii) teeth were root filled and quartz fibre posts were placed. Teeth were restored using Computer‐assisted design/computer‐assisted machining‐ceramic‐restorations and subjected to thermo‐mechanical‐loading; subsequently, the buccal cusp was loaded until fracture.

Results  Group D revealed significantly higher fracture resistance [mean (standard deviation)] [738 (272) N] compared to all other groups (P < 0.05; post hoc test Dunnett). For groups A–C, fracture resistance was significantly affected by the restoration type (P = 0.043) and endodontic treatment/post placement (P = 0.039; 2‐way anova). Group A [380 (146) N] showed significantly lower fracture resistance compared to group B [470 (158) N] (P = 0.048; post hoc test Tukey). Compared to non‐endodontically treated teeth [487 (120) N], root filled teeth revealed significantly lower fracture resistance [389 (171) N] (P = 0.031).

Conclusion  The restoration of cavities with a remaining wall thickness of 2 mm using ceramic MOD‐inlays is inferior with respect to the fracture resistance compared to partial onlay restorations. Root filled teeth without post placement show lower fracture resistance compared to non‐endodontically treated teeth.
What are the concerns of prospective responsible officers about their role in medical revalidation?
Authors: Shepherd Annabel , Cameron Niall
Published: May 2010

Introduction  The Health and Social Care Act 2008 sets out the requirement for the introduction of responsible officers for the NHS. The paper states that these individuals will be responsible for ensuring that doctors who are revalidated meet the required standards. It is not known how well prepared prospective responsible officers are for their new role.

Methods  Semi‐structured interviews were conducted with 12 medical directors from Scottish health boards who agreed to participate.

Results  Prospective responsible officers remain uncertain about their role in medical revalidation. Specific concerns were raised: (1) What will responsible officers be responsible for? (2) How can appraisal be quality assured? (3) How will the information requirements for revalidation be met? and (4) How can organizations meet the requirement for revalidation?

Conclusion  We found important issues regarding the arrangements for revalidation which have not previously been described which may impact on the effectiveness of prospective responsible officers.
Central Responsiveness to a Ghrelin Mimetic (GHRP‐6) is Rapidly Altered by Acute Changes in Nutritional Status in Rats
Authors: Tung Y. C. L. , Hewson A. K. , Carter R. N. , Dickson S. L.
Published: May 2010

The hypothalamus appears to be more responsive to ghrelin and growth hormone secretagogues (GHS) in fasting, as reflected by a two‐ to three‐fold increase in the number of cells detected that express Fos protein in the arcuate nucleus, in 48‐h fasted rats compared to fed controls. Moreover, this increased hypothalamic responsiveness to GHS in fasting is regulated by the central action of exogenous leptin and insulin, although it is unknown whether these hormones mediate the changes in hypothalamic responsiveness to GHS associated with the fasting/fed state. In the present study, we show that refeeding with normal rat chow for only 2 h at the end of a 48‐h fast reversed the potentiation of the Fos response to GHRP‐6 observed in fasted rats. Circulating leptin and insulin levels remained significantly lower in refed rats compared to ad lib‐fed rats, suggesting that the change in the hypothalamic sensitivity brought about by refeeding was independent of these hormones. By contrast, 2 h of chow refeeding at the end of a fast restored plasma glucose levels to those of the fed state. Refeeding with sugar alone for 2 h at the end of a 48‐h fast also reduced the potentiated Fos response in fasting, indicating that elevated blood glucose can influence the central responsiveness to ghrelin/GHS. By contrast, infusion of the ileal satiety factor, PYY3‐36 (known to increase postprandially) did not alter the central responsiveness to GHRP‐6, although it suppressed feeding and body weight as expected. This study highlights the importance of nutritional status in regulating the action of exogenous GHS (and presumably endogenous ghrelin) on the hypothalamic circuits controlling food intake.
Noradrenergic Regulation of Hypothalamic Cells that Produce Growth Hormone‐Releasing Hormone and Somatostatin and the Effect of Altered Adiposity in Sheep
Authors: Iqbal J. , Manley T. R. , Yue Q. , Namavar M. R. , Clarke I. J.
Published: May 2010

The growth hormone (GH) axis is sensitive to alteration in body weight and there is evidence that central noradrenergic systems regulate neurones that produce growth hormone‐releasing hormone (GHRH) and somatostatin (SRIF). This study reports semiquantitative estimates of the noradrenergic input to neuroendocrine GHRH and SRIF neurones in the sheep of different body weights. We also studied the effects of altered body weight on expression of dopamine β‐hydroxylase (DBH), the enzyme that produces noradrenalin from dopamine. Ovariectomised ewes were made Lean (39.6 ± 2.6 kg; Mean ± SEM) by dietary restriction, whereas Normally Fed animals (61.2 ± 0.8 kg) were maintained on a regular diet. Brains were perfused for immunohistochemistry and in situ hybridisation. The Mean ± SEM number of GHRH‐immunoreactive (‐IR) cells was lower in Normally Fed (65 ± 7) than in Lean (115 ± 14) animals, whereas the number of SRIF‐IR cells was similar in the two groups (Normally Fed, 196 ± 17; Lean 230 ± 21). Confocal microscopic analysis revealed that the percentage of GHRH‐IR cells (Normally Fed 36 ± 1.5% versus Lean 32 ± 4.6%) and percentage of SRIF‐IR cells (Normally Fed 30 ± 40.4% versus Lean 32 ± 2.3%) contacted by noradrenergic fibres did not change with body weight. FluoroGold retrograde tracer injections confirmed that noradrenergic projections to the arcuate nucleus are from ventrolateral medulla and noradrenergic projections to periventricular nucleus arise from the ventrolateral medulla, nucleus of solitary tract, locus coeruleus (LC) and the parabrachial nucleus (PBN). DBH expressing cells were identified using immunohistochemistry and in situ hybridisation and the level of expression (silver grains/cell) quantified by image analysis. The number of DBH cells was similar in Normally Fed and Lean animals, but the level of expression/cell was lower (P < 0.02) in the PBN and LC of Lean animals. These results provide an anatomical basis for the noradrenergic regulation of GHRH and SRIF cells and GH secretion. Altered activity or noradrenergic neurones in the PBN and LC that occur with reduced body weight may be relevant to the control of GH axis.
Early Oestrogens in Shaping Reproductive Networks: Evidence for a Potential Organisational Role of Oestradiol in Female Brain Development
Authors: Bakker J. , Brock O.
Published: May 2010

A central tenet of contemporary theories on mammalian brain and behavioural sexual differentiation is that an organisational action of testosterone, secreted by the male’s testes, controls male‐typical aspects of brain and behavioural development, whereas no active perinatal sex hormone signalling is required for female‐typical sexual differentiation. Furthermore, the available evidence suggests that many, although not all, of the perinatal organisational actions of testosterone on the development of the male brain result from the cellular effects of oestradiol formed via neural aromatisation of testosterone. However, a default developmental programme for the female brain has been criticised. Indeed, we review new results obtained in aromatase knockout mice indicating that oestradiol actively contributes to the differentiation of female‐typical aspects of brain and behavioural sexual differentiation. Furthermore, we propose that male‐typical neural and behavioural differentiation occurs prenatally in genetic males under the influence of oestradiol, which is avoided in foetal genetic females by the neuroprotective actions of α‐fetoprotein, whereas female‐typical neural and behavioural differentiation normally occurs postnatally in genetic females under the influence of oestradiol that is presumably produced by the ovaries.