bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared spectroscopy of acetone-hexane liquid mixtures
Authors: Max Jean-Joseph , Chapados Camille
Published: April 2007

Acetone and hexane mixtures covering the whole solubility range were studied by Fourier transform infrared attenuated total reflectance spectroscopy. Factor analysis separates the spectra into four principal factor spectra and multiplying factors. Those containing negative factors are abstract, but the spectra are real. A statistical distribution model of the molecules in the solutions rendered the factors real. From these we define the intermediate species that occur in a 1:2 molar ratio of acetone in hexane, present principally in the low acetone concentration regions, and in a 2:1 molar ratio of acetone in hexane, present principally in the higher acetone concentration region. However, except at the concentration range limits where only pure acetone and pure hexane are present, the four species are present over the whole solubility range. The IR spectra of the species indicated very little displacement of the CH stretch bands, HCH deformation bands, and CC stretch bands, although there are some small intensity variations. Most of the modifications are observed on the acetone CO stretch band. From the gas phase position, a strong bathochromic shift of 19cm−1 of the pure liquid is assigned to dipole-dipole interactions. In the 2:1 groupings, the shift that decreases to 15cm−1 is due to the diminished dipole-dipole interactions. In the 1:2 groupings, no dipole-dipole interaction can exist, and the bathochromic displacement of 9cm−1 is attributed to van der Waals interactions. In the one acetone to two hexanes grouping, no dipole-dipole interaction can exist, and the bathochromic displacement of 9cm−1 is attributed to van der Waals interactions. From the statistical distribution of the molecules, we determine that mixtures of hexane and acetone form a random organization with no preferred association or complex.
A microscopic model for the behavior of nanostructured organic photovoltaic devices
Authors: Marsh R. A. , Groves C. , Greenham N. C.
Published: April 2007

We present a Monte Carlo model of carrier separation and recombination in nanostructured organic photovoltaic (OPV) devices which takes into account all electrostatic interactions, energetic disorder, and polaronic effects. This permits a detailed analysis of the strong morphology dependence of carrier collection efficiency. We find that performance is determined both by the orientation of the heterojunction relative to the external electric field as well as by carrier confinement due to polymer intermixing. The model predicts that an idealized interdigitated structure could achieve overall efficiencies twice as high as blends. The model also reproduces the weakly sublinear intensity dependence of short-circuit photocurrent (ISC) seen in experiment. We show that this is not the result of space-charge effects but of bimolecular recombination. Disconnected islands of polymer in coarser blends result in bimolecular recombination even at low intensities and should therefore be minimized. By including a microscopic description of dark injection, the model can describe the full current-voltage (J-V) characteristics of different OPV structures. We examine the effect of morphology, intensity, mobility, and recombination rate on key parameters such as short-circuit current, open-circuit voltage (VOC), and fill factor (FF). The model reproduces the intensity-dependent contribution to VOC in a bilayer above that of a blend observed in experiment. We find that performance in both bilayers and blends is very sensitive to the recombination rate across the heterojunction. The model also predicts a striking dependence of performance on mobility. Indeed it is shown that a tenfold increase in mobility dramatically improves ISC and FF and doubles the maximum power output in a bilayer device. As well as informing routes for improving device performance, the model also offers an improved microscopic understanding of OPV operation.
Thermal properties of natural nanostructured hydroxyapatite extracted from fish bone waste
Authors: Coelho T. M. , Nogueira E. S. , Weinand W. R. , Lima W. M. , Steimacher A. , Medina A. N. , Baesso M. L. , Bento A. C.
Published: April 2007

In a previous study, natural hydroxyapatite (HAp) from the bones of Brazilian river fish was calcined at 900 °C (4–12 h), and optical characterization using the near infrared photoacoustic spectroscopy technique enabled the establishment of 8 h as the best calcination time for nanostructure stabilization when milled in a high-energy milling device [T. M. Coelho, E. S. Nogueira, W. R. Weinand, W. M. Lima, A. Steimacher, A. N. Medina, M. L. Baesso, and A. C. Bento, J. Appl. Phys. 100, 094312 (2006)]. The fish wastes used were from species such as pintado (Pseudoplatystoma corruscans), jaú (Paulicea lutkeni), and cachara (Pseudoplatystoma fasciatum). In this study, the characterization of the thermal properties of the same natural HAp is discussed for samples milled from 0 to 32 h, with nanostructures from 80 to 24 nm. The powders were pressed into disks at 350 MPa and sintered for 4 h at 1000 °C. Thermophysical parameters were obtained by thermal wave interferometry and nonadiabatic relaxation calorimetry. Results for thermal diffusivity and thermal conductivity showed that the parameters increase with milling time, although they present a transition (a plateau) in the interval from 8 to 16 h. Two different slopes were observed and this was interpreted as being due to the size of the crystallites, which fall rapidly, dropping from 80 nm to near 22 nm when milling time is increased from 0 to 16 h, and forming agglomerates up to 32 h.
Enhancement of hole injection using ozone treated Ag nanodots dispersed on indium tin oxide anode for organic light emitting diodes
Authors: Moon Jong-Min , Bae Jung-Hyeok , Jeong Jin-A , Jeong Soon-Wook , Park No-Jin , Kim Han-Ki , Kang Jae-Wook , Kim Jang-Joo , Yi Min-Su
Published: April 2007

The authors report the enhancement of hole injection using an indium tin oxide (ITO) anode covered with ultraviolet (UV) ozone-treated Ag nanodots for fac tris (2-phenylpyridine) iridium Ir(ppy)3-doped phosphorescent organic light-emitting diodes (OLEDs). X-ray photoelectron spectroscopy and UV-visible spectrometer analysis exhibit that UV-ozone treatment of the Ag nanodots dispersed on the ITO anode leads to formation of Ag2O nanodots with high work function and high transparency. Phosphorescent OLEDs fabricated on the Ag2O nanodot-dispersed ITO anode showed a lower turn-on voltage and higher luminescence than those of OLEDs prepared with a commercial ITO anode. It was thought that, as Ag nanodots changed to Ag2O nanodots by UV-ozone treatment, the decrease of the energy barrier height led to the enhancement of hole injection in the phosphorescent OLEDs.
Self-guiding of 100TW femtosecond laser pulses in centimeter-scale underdense plasma
Authors: Chen L. M. , Kotaki H. , Nakajima K. , Koga J. , Bulanov S. V. , Tajima T. , Gu Y. Q. , Peng H. S. , Wang X. X. , Wen T. S. , Liu H. J. , Jiao C. Y. , Zhang C. G. , Huang X. J. , Guo Y. , Zhou K. N. , Hua J. F. , An W. M. , Tang C. X. , Lin Y. Z.
Published: April 2007

An experiment for studying laser self-guiding has been carried out for the high power ultrashort pulse laser interaction with an underdense plasma slab. Formation of an extremely long plasma channel and its bending are observed when the laser pulse power is much higher than the critical power for relativistic self-focusing. The long self-guiding channel formation is accompanied by electron acceleration with a low transverse emittance and high electric current. Particle-in-cell simulations show that laser bending occurs when the accelerated electrons overtake the laser pulse and modify the refractive index in the region in front of the laser pulse.
Low temperature phases of the Andelman–de Gennes model of chiral discrimination: Rigorous results
Authors: Medved’ Igor , Trník Anton , Belkasri Abdel K. , Huckaby Dale A.
Published: April 2007

We determine the ordered low temperature phases of the Andelman–de Gennes model of chiral discrimination, using rigorous statistical mechanical methods. The system is considered in the close-packed regime, equivalent to placing the molecules at every site of a honeycomb lattice. If the system contains an equimolar mixture of each of a pair of enantiomers, we prove in general that a heterochiral phase (disfavoring enantiomeric segregation) as well as a homochiral phase (favoring the segregation) is possible, depending on the types of intermolecular interactions. We apply our general results to the specific examples of the interactions considered by Andelman and de Gennes and provide a comparison with their conjectures that were based on two-molecule partition functions.
A distributed algorithm for multi-tau autocorrelation
Authors: Culbertson Michael J. , Burden Daniel L.
Published: April 2007

Network data-transfer times in distributed simulation environments can be reduced by performing data analysis at the remote source, if the analytical technique does not require the entire set of data at once. This novel multi-tau autocorrelation algorithm allows time-domain data records to be processed in discrete, distributed segments and combined at a later point in time. The new approach agrees with autocorrelation results performed by concatenating the discrete segments before correlation, but it operates with significantly shortened processing times. The multi-tau algorithm also benefits from reduced memory requirements since it does not require access to the entire data record at once, and from improved scalability since the multi-tau algorithm has order O(N), while fast Fourier transform autocorrelation algorithms have order O(N log N). This distributed algorithm has particular utility in simulations of fluorescence correlation spectroscopy or photon correlation spectroscopy.
Gauge invariant calculations of nuclear magnetic shielding constants using the continuous transformation of the origin of the current density approach. II. Density functional and coupled cluster theory
Authors: Ligabue Andrea , Sauer Stephan P. A. , Lazzeretti Paolo
Published: April 2007

The quantum mechanical current density induced in a molecule by an external magnetic field is invariant to translations of the coordinate system. This fundamental symmetry is exploited to formally annihilate the diamagnetic contribution to the current density via the approach of “continuous transformation of the origin of the current density-diamagnetic zero” (CTOCD-DZ). The relationships obtained by this method for the magnetic shielding at the nuclei are intrinsically independent of the origin of the coordinate system for any approximate computational scheme relying on the algebraic approximation. The authors report for the first time an extended series of origin-independent estimates of nuclear magnetic shielding constants using the CTOCD-DZ approach at the level of density functional theory (DFT) with four different types of functionals and unrelaxed coupled cluster singles and doubles linear response (CCSD-LR) theory. The results obtained indicate that in the case of DFT the procedure employed is competitive with currently adopted computational methods allowing for basis sets of gauge-including atomic orbitals, whereas larger differences between CTOCD-DZ and common origin CCSD-LR results are observed due to the incomplete fulfillment of hypervirial relations in standard CCSD-LR theory. It was found furthermore that the unrelaxed CCSD-LR calculations predict larger correlation corrections for the shielding constants of almost all nonhydrogen atoms in their set of molecules than the usual relaxed energy derivative CCSD calculations. Finally the results confirm the excellent performance of Keal and Tozer’s third functional, in particular, for the multiply bonded systems with a lot of electron correlation, but find also that the simple local density functional gives even better results for the few singly bonded molecules in their study where correlation effects are small.
Electrically small split ring resonator antennas
Authors: Alici Kamil Boratay , Ozbay Ekmel
Published: April 2007

We studied electrically small resonant antennas composed of split ring resonators (SRR) and monopoles. The antennas considered have the same ring radius, but slightly different geometry. The resonance frequency depends on the geometry of the SRRs. Two SRR antennas are designed. The first one, which operates at 3.62 GHz, is demonstrated theoretically and experimentally. The size of this antenna is 0.095λ0×0.100λ0 and is low profile at the other dimension. The gain and directivity of the antenna was 2.38 and 5.46, respectively. The corresponding efficiency was 43.6%. The estimated radiation Q (rad Q=23.03) was much larger than the minimum radiation Q (min Q=1.78). The second one is a rather small SRR antenna in which the capacitance between the rings is increased. The size is reduced to 0.074λ0×0.079λ0. This structure is called serrated SRR (SSRR). Both antennas have similar far-field patterns but the efficiency of the SSRR antenna is less.
Time- and temperature-dependent domain evolutions in poled (111)-cut (Pb(Mg1∕3Nb2∕3)O3)0.7(PbTiO3)0.3 single crystal
Authors: Wong K. S. , Dai J. Y. , Zhao X. Y. , Luo H. S.
Published: April 2007

Ferroelectric domain evolution in poled (111)-cut (Pb(Mg1∕3Nb2∕3)O3)0.7(PbTiO3)0.3 single crystal has been studied by means of piezoresponse force microscopy (PFM). A time-dependent development of lamellar ferroelectric domains from a single domain structure of the just-poled sample has been observed, and it reveals that the formation of the lamellar macrodomains is via the accumulation of well-aligned speckle-shaped nanodomains grown from polar nanosized regions (PNRs). The domain evolutions from macrodomain to microdomain, and from ferroelectric to paraelectric phase at different temperatures, have been revealed in temperature-dependent PFM imaging, and the results are consistent with temperature-dependent relative permittivity measurement. PNRs are believed to play a key role in the domain evolution of depolarization process.
Negative bias temperature instability and Fowler-Nordheim injection in silicon oxynitride insulators
Authors: Busani T. , Devine R. A. B. , Hughes H. L.
Published: April 2007

Negative bias temperature instability and Fowler-Nordheim injection measurements have been performed on p-channel field effect transistors. For Fowler-Nordheim injection a comparison of the threshold voltage shift and the reduced channel transconductance shows similar linear behavior to that observed for hot electron stressing of n-channel devices. Comparison for bias temperature instability shows dramatically different behaviors. Simultaneous negative bias temperature instability and Fowler-Nordheim injection lead to potentially significant errors in the estimation of the reliability lifetime.
High-throughput assembly of nanoelements in nanoporous alumina templates
Authors: Gultepe Evin , Nagesha Dattatri , Menon Latika , Busnaina Ahmed , Sridhar Srinivas
Published: April 2007

The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50nm inside nanopore arrays of height of 250nm and diameter of 80nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.
High performance flexible pentacene thin-film transistors fabricated on titanium silicon oxide gate dielectrics
Authors: Na Jong H. , Kitamura M. , Lee D. , Arakawa Y.
Published: April 2007

Pentacene thin-film transistors (TFTs) with a high dielectric constant gate insulator, titanium silicon oxide (TiSiO2), were fabricated on flexible polyethylene naphthalate films coated with indium tin oxide layers. In order to define the device characteristics, the thickness dependence of the gate dielectric properties was studied. The pentacene TFT with a 132-nm-thick TiSiO2 film showed high performance with a threshold voltage of −0.88V, an inverse subthreshold slope of 317mV/decade. From the current-voltage characteristics, the field-effect mobility was obtained, resulting in an impressive mobility of 0.67cm2∕Vs at an operating voltage as low as −5V.
Hidden features of the catalyst nanoparticles favorable for single-walled carbon nanotube growth
Authors: Harutyunyan Avetik R. , Mora Elena , Tokune Toshio , Bolton Kim , Rosén Arne , Jiang Aiqin , Awasthi Neha , Curtarolo Stefano
Published: April 2007

Combining in situ studies of the catalyst activity during single-walled carbon nanotube (SWCNT) growth by mass spectrometry with differential scanning calorimetry and Raman spectroscopy results, the authors expose the favorable features of small catalyst for SWCNT growth and their relationship with synthesis parameters. The sequential introduction of C12 and C13 labeled hydrocarbon reveals the influence of catalyst composition on its lifetime and the growth termination path. Ab initio and molecular dynamics simulations corroborate “V”-shape liquidus line of metal-carbon nanoparticle binary phase diagram, which explains observed carbon-induced solid-liquid-solid phase transitions during nanotube growth.
Analysis of current conduction mechanisms in atomic-layer-deposited Al2O3 gate on 4H silicon carbide
Authors: Cheong Kuan Yew , Moon Jeong Hyun , Kim Hyeong Joon , Bahng Wook , Kim Nam-Kyun
Published: April 2007

Current conduction mechanisms of an atomic-layer-deposited Al2O3 gate on n-type 4H SiC have been systematically investigated, analyzed, and reported in this letter. It has been revealed that space charge limited, Poole-Frenkel (PF) emission, combination of PF emission and Fowler-Nordheim tunneling are the dominate current conduction mechanisms in the dielectric. Besides, Schottky emission has also been proposed as a possible leakage path at temperature beyond the investigated range. A relationship among the conduction mechanism, temperature, and applied electric field has been presented.
Suppressing the field-induced agglomeration in the magnetic fluid by doping the nonmagnetic particles
Authors: Di Ziyun , Chen Xianfeng , Chen Jingfei , Xia Yuxing , Pu Shengli
Published: April 2007

A method for suppressing the field-induced agglomeration of magnetic particles in a magnetic fluid is proposed in this letter. After the magnetic fluid is doped with nonmagnetic silica particles, the field-induced agglomeration effect is weakened, and this suppressing effect is expressed by the measured birefringence magnitude and the simulation results of the agglomeration parameter. The optical properties of this system such as the optical transmission and response time are analyzed. With this method, the quality of the magnetic-fluid-based optical devices might be improved.
Deterministic characterization of stochastic genetic circuits
Authors: Scott Matthew , Hwa Terence , Ingalls Brian
Published: April 2007

For cellular biochemical reaction systems where the numbers of molecules is small, significant noise is associated with chemical reaction events. This molecular noise can give rise to behavior that is very different from the predictions of deterministic rate equation models. Unfortunately, there are few analytic methods for examining the qualitative behavior of stochastic systems. Here we describe such a method that extends deterministic analysis to include leading-order corrections due to the molecular noise. The method allows the steady-state behavior of the stochastic model to be easily computed, facilitates the mapping of stability phase diagrams that include stochastic effects, and reveals how model parameters affect noise susceptibility in a manner not accessible to numerical simulation. By way of illustration we consider two genetic circuits: a bistable positive-feedback loop and a negative-feedback oscillator. We find in the positive feedback circuit that translational activation leads to a far more stable system than transcriptional control. Conversely, in a negative-feedback loop triggered by a positive-feedback switch, the stochasticity of transcriptional control is harnessed to generate reproducible oscillations.
Thermal expansion of iron-rich alloys and implications for the Earth's core
Authors: Chen Bin , Gao Lili , Funakoshi Ken-ichi , Li Jie
Published: April 2007

Understanding the thermal–chemical state of the Earth's core requires knowledge of the thermal expansion of iron-rich alloys at megabar pressures and high temperatures. Our survey of literature revealed a significant lack of such data. We have determined the unit-cell parameters of the iron–sulfur compound Fe3S by using synchrotron x-ray diffraction techniques and externally heated diamond–anvil cells at pressures up to 42.5 GPa and temperatures up to 900 K. The zero-pressure thermal expansivity of Fe3S is determined in the form α =a1+a2T, wherea1= 3.0 ± 1.3 × 10−5K−1anda2= 2.8 ± 1.5 × 10−8K−2. The temperature dependence of isothermal bulk modulus (∂KT,0/∂T)Pis estimated at −3.75 ± 1.80 × 10−2GPa K−1. Our data at 42.5 GPa and 900 K suggest that ≈2.1 at. % (1.2 wt. %) sulfur produces 1% density deficit in iron. We have also carried out energy-dispersive x-ray diffraction measurements on pure iron and Fe0.864Si0.136alloy samples that were placed symmetrically in the same multianvil cell assemblies, using the SPring-8 synchrotron facility in Japan. Based on direct comparison of unit cell volumes under presumably identical pressures and temperatures, our data suggest that at most 3.2 at. % (1.6 wt. %) silicon is needed to produce 1% density deficit with respect to pure iron.
Epstein–Barr virus and virus human protein interaction maps
Authors: Calderwood Michael A. , Venkatesan Kavitha , Xing Li , Chase Michael R. , Vazquez Alexei , Holthaus Amy M. , Ewence Alexandra E. , Li Ning , Hirozane-Kishikawa Tomoko , Hill David E. , Vidal Marc , Kieff Elliott , Johannsen Eric
Published: April 2007

A comprehensive mapping of interactions among Epstein–Barr virus (EBV) proteins and interactions of EBV proteins with human proteins should provide specific hypotheses and a broad perspective on EBV strategies for replication and persistence. Interactions of EBV proteins with each other and with human proteins were assessed by using a stringent high-throughput yeast two-hybrid system. Overall, 43 interactions between EBV proteins and 173 interactions between EBV and human proteins were identified. EBV–EBV and EBV–human protein interaction, or “interactome” maps provided a framework for hypotheses of protein function. For example, LF2, an EBV protein of unknown function interacted with the EBV immediate early R transactivator (Rta) and was found to inhibit Rta transactivation. From a broader perspective, EBV genes can be divided into two evolutionary classes, “core” genes, which are conserved across all herpesviruses and subfamily specific, or “noncore” genes. Our EBV–EBV interactome map is enriched for interactions among proteins in the same evolutionary class. Furthermore, human proteins targeted by EBV proteins were enriched for highly connected or “hub” proteins and for proteins with relatively short paths to all other proteins in the human interactome network. Targeting of hubs might be an efficient mechanism for EBV reorganization of cellular processes.
Niacin Nutritional Status in HIV Type 1–Positive Children: Preliminary Data
Authors: Tremeschin Marina Hjertquist , Cervi Maria Célia , Júnior José Simon Camelo , de Moura Negrini Bento Vidal , Martinez Francisco Eulógio , Motta Fabrízio , de Souza Meirelles Mônica Silva , Vanucchhi Helio , Monteiro Jacqueline Pontes
Published: April 2007

Objective:

HIV infection induces a state of pellagra in cell culture models. This study compared the nutritional status and the 24‐hour urine excretion of N1‐methylnicotinamide between HIV‐positive children and HIV‐negative children who were or were not born of mothers with HIV‐1 infection.

Patients and Methods:

Forty patients were included in the study: HIV‐positive children (group 1; n = 20), HIV‐negative children born to infected mothers (group 2; n = 10), and HIV‐negative control children (group 3; n = 10). Usual dietary intake was assessed by a semiquantitative food‐frequency questionnaire. Weight and height were assessed and compared with the reference data of the U.S. National Center for Health Statistics/Centers for Disease Control and Prevention. For the estimation of fat‐free mass and total body water, bioelectrical impedance technique was used. N1‐methylnicotinamide was measured by a modified method of high‐performance liquid chromatography.

Results:

Groups were matched in relation to age, sex, percentage of malnutrition, anthropometric measures, and body composition. Daily niacin intake did not differ statistically across groups (group 1 = 18.0 ± 11.4 mg/day; group 2 = 18.9 ± 8.0 mg/day; group 3 = 14.2 ± 5.2 mg/day), nor did intake of tryptophan, vitamin B6, and zinc. The values of urinary niacin per gram of creatinine were similar and adequate across the groups (group 1 = 4.68 [0.75–14.9]; group 2 = 3.74 [1.13–5.69]; group 3 = 3.85 [1.80–8.19]).

Conclusions:

HIV‐positive children excreted the same amount of N1‐methylnicotinamide in urine as did the control children. These findings may be attributed to similarities in nutritional status, adequate intestinal absorption (no children experienced diarrhea) and stable clinical condition.
Transpyloric Feeding in the Pediatric Intensive Care Unit
Authors: Babbitt Christopher
Published: April 2007

The approach to achieving and maintaining nutritional support in pediatric intensive care unit patients continues to evolve with newer techniques such as transpyloric feeding. We reviewed our transpylorically fed patients over a 4‐year period and found that we achieved adequate nutritional support in 96% of them. We did find an increase in necrotizing enterocolitis in cyanotic patients and recommend that these patients be fed with caution when transpyloric feeding is used.
Amplification of Bacterial DNA Does Not Distinguish Patients with Ascitic Fluid Infection From Those Colonized by Bacteria
Authors: Vieira Sandra MG , da Silveira Themis R , Matte Ursula , Kieling Carlos O , Ferreira Cristina T , Taniguchi Adriano , dos Santos Oliveira Fernanda , Barth Afonso L
Published: April 2007

Objective:

To evaluate 16S ribosomal RNA (rRNA) gene amplification to diagnose spontaneous bacterial peritonitis (SBP).

Patients and Methods:

According to a retrospective protocol, 31 patients with portal hypertensive ascites (serum to ascites albumin gradient ≥1.1 g/dL) were studied. Ascitic fluid was analyzed as follows: Gram stain, aerobic and anaerobic cultures, polymorphonuclear cell count, and biochemical tests. Bacterial DNA was detected by polymerase chain reaction.

Results:

There were 8 episodes of SBP and 4 episodes of bacterascites (BA). Culture was positive in 4 of 8 cases of SBP and bacterial DNA was positive in 7 of 8 cases of SBP. Bacterial DNA was positive in 3 of 4 cases of BA and in 8 of 28 cases of culture‐negative non‐neutrocytic ascites (CNNNA). The PELD score, serum to albumin ascites gradient, and mortality showed no statistical difference between patients with CNNNA and the result of the bacterial DNA analysis.

Conclusions:

Although the 16S rRNA gene amplification was better than culture to diagnose SBP, bacterial DNA does not seem to allow a distinction between ascites infection and ascites colonization.
Minimally Invasive Surgery for Achalasia: Combined Experience of Two European Centers
Authors: Garzi Alfredo , Valla Jean Stephan , Molinaro Francesco , Amato Giovanna , Messina Mario
Published: April 2007

Background:

The present report summarizes 12 cases with achalasia treated with laparoscopic Heller myotomy and anterior fundoplication according to the method of Thal and Dor.

Patients and Methods:

From 1997 to 2005 at 2 institutions in Europe, 12 patients (7 male and 5 female, ages ranging from 3.5 to 7 years) were treated for esophageal achalasia (EA) with laparoscopic Heller myotomy and anterior fundoplication according to Thal and Dor. In 1 case a perforation of the esophageal mucosa occurred, which was promptly treated during surgery. Follow‐up ranged from 18 to 60 months and included clinical examination and barium radiography of the upper digestive tract.

Results:

Postoperatively, 10 patients showed a normal weight curve and complete resolution of symptoms. All patients showed complete regression of digestive and respiratory symptoms from the first examination, with a normal oral meal intake and an improvement of weight and height parameters. One case required repeat intervention after 2 years because of persisting pain; in this case surgery revealed an insufficient myotomy.

Conclusions:

Modified extramucosal Heller cardiomyotomy associated with 180° anterior antireflux plastic surgery (according to Thal and Dor's procedures) is a useful and safe procedure in the treatment of EA in pediatric patients. Our data, which are supported by long‐term follow‐up, also stress the relevance of anterior fundoplication in preventing postoperative gastroesophageal reflux.
Disease Presentation and Clinical Course in Black and White Children With Inflammatory Bowel Disease
Authors: Eidelwein Alexandra P , Thompson Richard , Fiorino Kristin , Abadom Vivian , Oliva‐Hemker Maria
Published: April 2007

Objectives:

To compare the disease presentation, disease phenotype, and clinical course between black and white children with inflammatory bowel disease (IBD).

Patients and Methods:

A 10‐year retrospective review was undertaken of the medical records of 245 pediatric patients with IBD studied at a tertiary care center.

Results:

In this patient population 24% were black and 76% were white. There were no differences between black and white patients in terms of anatomic distribution of IBD, symptom presentation, and extraintestinal manifestations. A family history of IBD (36.4% vs 17.5%; P = 0.006) was more common in white children. Mean erythrocyte sedimentation rate of black patients with Crohn disease was higher at diagnosis compared with whites (P < 0.001) and a greater proportion of African Americans presented with a body mass index z‐score less than −2 (P < 0.009). At 12 months following diagnosis 22.5% of African American children had a hemoglobin level lower than 10 g/dL compared with 4.3% of whites (P = 0.001). African Americans had evidence of more complicating stricturing and penetrating Crohn disease behavior (51.3% vs 27.4%; P = 0.006). African Americans received significantly more corticosteroids and infliximab to treat their IBD compared with whites (P < 0.04).

Conclusions:

This study suggests that for pediatric IBD, there may be racial differences in prevalence of family history and in disease phenotype.
Effectiveness and Safety of Lactobacillus LB in the Treatment of Mild Acute Diarrhea in Children
Authors: Salazar‐Lindo Eduardo , Figueroa‐Quintanilla Dante , Caciano Maria Isabel , Reto‐Valiente Victoria , Chauviere Gilles , Colin Patrick ,   Lacteol Study Group
Published: April 2007

Background:

Acute diarrhea is an important cause of morbidity and mortality in children. Oral rehydration salts (ORS) have lowered mortality without having an effect on the duration or severity of diarrhea. Some studies have reported that heat‐killed Lactobacillus bacteria have a beneficial effect in the treatment of acute diarrhea. In this placebo‐controlled study the duration of diarrhea was compared for 2 types of treatment: Lactobacillus LB (Lacteol) in association with oral rehydration and oral rehydration alone.

Patients and Methods:

A total of 80 nondehydrated children between the ages of 3 months and 4 years with acute watery diarrhea were randomly assigned to be treated with Lactobacillus LB or placebo plus ORS. The primary endpoint was the duration of diarrhea; intake of ORS and change in body weight between the time of randomization and the last assessment were also measured.

Results:

In 71 of the 80 patients, diarrhea was resolved: 36 in the Lactobacillus LB group and 35 in the placebo group. Several clinical characteristics of the 2 treatment groups were comparable at baseline. Median duration of diarrhea was 16.6 hours in the placebo group compared with 10.0 hours in the Lactobacillus LB group (P = 0.275). In the subgroup with a duration of diarrhea of more than 24 hours at inclusion, duration of diarrhea measured from that point was shorter for the Lactobacillus LB group (30.4 h vs 8.2 h; P = 0.044). ORS intake was similar for both groups. Lactobacillus LB was well tolerated, with only one patient experiencing an adverse effect.

Conclusions:

Lactobacillus LB is an effective and safe treatment for children with well‐established diarrhea (>24 h).
Functional Consequences of NOD2/CARD15 Mutations in Crohn Disease
Authors: Quaglietta Lucia , te Velde Anje , Staiano Annamaria , Troncone Riccardo , Hommes Daan W
Published: April 2007

Crohn disease (CD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract. Its etiology remained obscure until recently, when, through an overwhelming body of research, the main theme of its origin became clear. CD develops in individuals who carry risk alleles for the disease that can cause a loss of physiological tolerance to commensal bacteria. As a consequence, immune responses develop that activate a whole range of immunocompetent cells, resulting in the secretion of proinflammatory mediators that ultimately cause mucosal breaks and the formation of ulceration, edema, and loss of proper function.
Effects of the Probiotic Formulation VSL#3 on Colitis in Weanling Rats
Authors: Fitzpatrick Leo R , Hertzog Kristy L , Quatse Angela L , Koltun Walter A , Small Jeffrey S , Vrana Kent
Published: April 2007

Background:

Only a few studies have used models of inflammatory bowel disease (IBD) with weanling animals. Previously, the effects of probiotics have not been assessed in such IBD models. The objectives of our study were 2‐fold: to establish a suitable model of dextran sulfate sodium (DSS)–induced colitis in weanling rats and to determine the effects of the probiotic formulation VSL#3 on DSS‐induced colitis in weanling animals.

Materials and Methods:

Rats were weaned on postnatal day 21 and administered 2%, 2.5%, or 3% (wt/vol) DSS in drinking water. In subsequent experiments, newly weaned animals were administered vehicle or VSL#3 (0.06, 0.6, or 6 mg) by orogastric gavage. These treatments were given to animals maintained on water (postnatal days 21–28) and then on DSS (postnatal days 28–35). Disease activity indices were determined on a routine basis. On day 35, rats were euthanized. The total colon length was determined. Other parameters of colitis were measured from the distal colon. These parameters included myeloperoxidase (MPO), interleukin (IL)–1β, inhibitory κB‐α (IκB‐α), and histological assessment of crypt damage and inflammation.

Results:

DSS 2% was optimal for inducing colitis in weanling rats without significant morbidity. VSL#3 treatments improved various parameters of 2% DSS–induced colitis in weanling rats. The 0.6‐ and 6‐mg doses of VSL#3 were most effective for attenuating this colitis.

Conclusions:

The probiotic formulation VSL#3 improved DSS‐induced colitis in weanling rats. This improvement of colitis involved changes in colonic IκB‐α, IL‐1β, and MPO, which are suggestive of immune modulation by VSL#3.
Usefulness of Ultrasonography in Acute Appendicitis in Early Childhood
Authors: Chang Yi‐Jung , Kong Man‐Shan , Hsia Shao‐Hsuan , Wu Chang‐Teng , Lai Ming‐Wei , Yan Dah‐Chin , Chao Hsun‐Chin , Chen Chien‐Chang , Chen Shih‐Yann
Published: April 2007

Objective:

Acute appendicitis is an uncommon diagnosis in early childhood. It is frequently complicated by delays in diagnosis, perforation, and prolonged hospital stay. The aim of this study was to evaluate the usefulness of ultrasonography (US) in the management of suspected appendicitis in children younger than 3 years of age.

Patients and Methods:

Seventy‐one children under age 3 with acute abdomen and possible acute appendicitis, but with atypical findings, were included. All of the children underwent a US scan to rule out appendicitis.

Results:

There were 41 positive US results for appendicitis. Three children had false‐positive scan results and 2 children had false‐negative results. Twenty‐eight patients had ruptured appendicitis with tumor formation on US. Eighteen of the 28 patients received emergency appendectomy and the other 10 patients received initial conservative treatment with interval appendectomy. Compared with those who received emergency appendectomy, patients who received initial conservative treatment had a significantly smoother postoperative course, including shorter postoperative hospital stay and earlier postoperative oral intake. The overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of abdominal US to diagnose acute appendicitis in cases of atypical findings in early childhood are 95.0%, 90.3%, 92.9%, 92.6%, and 93.3%, respectively.

Conclusions:

US is a useful and highly accurate tool to assess acute appendicitis in early childhood. US has the potential to aid in diagnosis of early childhood appendicitis to avoid the frequent rupture with tumor formation seen at this age. Initial conservative treatment for ruptured appendicitis with tumor formation is safe and is associated with a smoother postoperative course in early childhood.
Impact of Diet on the Intestinal Microbiota in 10‐month‐old Infants
Authors: Nielsen Susanne , Nielsen Dennis S , Lauritzen Lotte , Jakobsen Mogens , Michaelsen Kim Fleischer
Published: April 2007

Objective:

To investigate whether diet influences the composition of the intestinal microbiota in 10‐month‐old infants.

Patients and Methods:

Fecal samples were collected from sixty‐five 10‐month‐old infants participating in a randomized 2 × 2 intervention study comparing cow's milk (CM) with infant formula (IF) with or without fish oil (FO) supplement. Infants randomized to CM received a daily iron supplement. Bacterial DNA was extracted from the feces. Polymerase chain reaction was performed with primers targeting the V3 and V6–8 region of the 16S rRNA gene and analyzed by denaturing gradient gel electrophoresis (DGGE). Cluster analysis of the DGGE gels was performed by use of the Pearson correlation coefficient.

Results:

Samples from infants receiving CM clustered differently than did those from the IF group in the V3‐based DGGE gels (P < 0.001) and showed a different distribution with or without FO in the CM group (P = 0.001) but not in the IF group (P = 0.39). Repeat analysis with the V6–8‐based DGGE gels showed the same pattern, although the V3 gels had 2.5 times as many bands as the V6–8 gels.

Conclusions:

Consumption of CM or IF has a decisive influence on the composition of the intestinal microbiota. Supplementation with FO showed an effect on the microbiota only in the CM group. We speculate that these differences could be influenced by the intake of iron and n‐3 polyunsaturated fatty acids, respectively.
Fasting Glucagon‐like Peptide‐1 and Its Relation to Insulin in Obese Children Before and After Weight Loss
Authors: Reinehr Thomas , de Sousa Gideon , Roth Christian L
Published: April 2007

Objective:

To study the relationships between glucagon‐like peptide‐1 (GLP‐1), weight status, insulin, and insulin resistance in the fasting state.

Patients and Methods:

Fasting GLP‐1, glucose and insulin concentrations, insulin resistance index as homeostasis model assessment (HOMA), body mass index (BMI), and percentage body fat based on skinfold thickness measurements were determined in 42 obese (median age 11 years) and in 16 lean children of the same age. The HOMA model was used to calculate degree of insulin resistance. Furthermore, the changes in GLP‐1, glucose, insulin, and HOMA in the course of 1 year were analyzed in the 42 obese children participating in an obesity intervention.

Results:

GLP‐1 concentrations did not differ significantly between obese and lean children. In multiple linear regression analyses, GLP‐1 was significantly related to insulin (P = 0.028) and HOMA (P = 0.019) but not to glucose, age, sex, pubertal stage, BMI, or percentage body fat. The 15 obese children with substantial weight reduction demonstrated significantly (P < 0.05) decreased GLP‐1, insulin, and HOMA levels, whereas these parameters did not change in 27 obese children without substantial weight loss. Changes in GLP‐1 correlated significantly with changes in insulin (r = 0.46, P = 0.001) and HOMA (r = 0.28, P = 0.036) but not with changes in glucose, BMI, or percentage of body fat.

Conclusions:

In children, fasting GLP‐1 concentrations are independent of age, sex, and pubertal stage. Although GLP‐1 did not differ between lean and obese children, weight loss was associated with decreasing GLP‐1. Inasmuch as GLP‐1 levels were related to insulin concentrations in both cross‐sectional and longitudinal analyses, we hypothesize a relationship between GLP‐1 and insulin in the fasting state.
Conditions of Bifidobacterial Colonization in Preterm Infants: A Prospective Analysis
Authors: Butel Marie‐José , Suau Antonia , Campeotto Florence , Magne Fabien , Aires Julio , Ferraris Laurent , Kalach Nicolas , Leroux Bernard , Dupont Christophe
Published: April 2007

Background:

Premature birth results in a delayed and abnormal qualitative pattern of gut colonization. This abnormal pattern is thought to affect intestinal development and contribute to a higher risk of gastrointestinal infectious diseases such as neonatal necrotizing enterocolitis (NEC). In particular, bifidobacteria are thought to play a major role. We therefore studied bifidobacterial colonization in preterm infants during the first month of life.

Patients and Methods:

Fecal samples were prospectively analyzed in 52 infants born at a gestational age ranging from 30 to 35 weeks fed with a preterm formula alone and, in 18, with their mother's milk. Fecal samples were collected twice per week during the hospital stay. Bifidobacterial colonization was analyzed with culture and a molecular method.

Results:

Bifidobacterial colonization occurred in 18 infants at a median age of 11 days, always greater than the corrected mean gestational age of 35.4 weeks (SD, 0.9) and greater than 34 weeks for 16 of 18. Colonization by bifidobacteria was affected by neither birthweight nor mode of delivery nor antibiotics given to the mother or infant. In contrast, birth gestational age had a significant impact on colonization by bifidobacteria (P < 0.05), which always occurred in children born at a birth gestational age greater than 32.9 weeks (P < 0.05).

Conclusions:

Birth gestational age seems to act as a major determinant of bifidobacterial colonization in the premature infant, suggesting the role of gut maturation, a finding that should probably be taken into account in manipulations of the gut flora aimed at reducing NEC.
Wilson Disease in Children: Serum Aminotransferases and Urinary Copper on Triethylene Tetramine Dihydrochloride (Trientine) Treatment
Authors: Arnon Ronen , Calderon Judith Flores , Schilsky Michael , Emre Sukru , Shneider Benjamin L
Published: April 2007

Objectives:

To evaluate the efficacy of and adherence to trientine and/or zinc therapy in children with Wilson disease (WD).

Materials and Methods:

We retrospectively reviewed the clinical records of all children with WD in the pediatric liver/liver transplant program at our institution between 1998 and 2006.

Results:

A total of 22 children with WD were evaluated and treated. Seven with fulminant disease required liver transplantation and 15 were treated with trientine and/or zinc. Ten of those 15 had follow‐up for 12 to 60 months and 6 of the latter 10 were followed for 12 to 18 months. All 10 patients were started on a trientine treatment regimen. Mean alanine aminotransferase (ALT) levels decreased from 183 ± 103 IU at presentation (n = 10) to 80 ± 46 IU at 12 months (n = 10) and 66 ± 40 IU at 18 months (n = 7). Mean 24‐hour urinary copper levels increased from 156 μg at presentation to 494 μg at 1 to 2 months, then decreased to 71 μg after 21 to 24 months of treatment. Three of 10 patients had normalized ALT levels and 1 patient with cirrhosis continued with normal ALT levels since presentation. Four of 10 patients were documented to be nonadherent, as manifested by increased ALT levels (99 ± 31 IU); 1 patient had previously normalized ALT levels. In 3 of 10 patients, ALT level decreased but remained at an abnormal level (93 ± 53 IU).

Conclusions:

Trientine and/or zinc therapy is effective for children with WD. Nonadherence is a common cause of increased aminotransferase levels in patients with WD.
Public forum mediation: a training exercise for conflict facilitation skills
Authors: Hartman Rosanne L. , Crume Alice L.
Published: April 2007

Purpose

The purpose of this paper is to describe the use of public forum mediation as a model for training in and improvement of conflict facilitation skills.

Design/methodology/approach

The training strategy integrates continuous involvement of all the trainees through the use of a reflective team. The team and trainees focus on recognizing communication patterns used by individuals engaged in conflict.

Findings

Identifying communication patterns and strategies strengthens the trainees' ability to alter language use and nonverbal behavior during the facilitation process.

Originality/value

The use of public forum mediation strategies within the training context offers new and different ways for examining communication in the process of conflict facilitation.
Information behaviour of primary health care providers in rural Uganda
Authors: Musoke Maria G.N.
Published: April 2007

Purpose

The purpose of this paper is to investigate the accessibility and use of health information among primary health care providers. The study focused on women and health workers' experiences with information in rural Uganda.

Design/methodology/approach

Face‐to‐face interviews (82) were conducted using an interview schedule that consisted of open questions and one relating to health information critical incidents. A holistic inductive paradigm was used with a grounded theory analysis. An “Interaction‐value model” emerged from the study. The model was driven by the value and impact of information, unlike previous information models which have been driven by information needs.

Findings

The findings have a number of implications for improving information provision, and further research.

Originality/value

This study has demonstrated that, although an information need could trigger off an information activity, the subsequent information processes could only be sustained by the value of information. The study has also shown that health workers were generally active information seekers, whereas women were mainly passive.