bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafast all-optical control of the magnetization in magnetic dielectrics
Authors: Kirilyuk Andrei , Kimel Alexey , Hansteen Fredrik , Rasing Theo , Pisarev Roman V.
Published: October 2006

The purpose of this review is to summarize the recent progress on laser-induced magnetization dynamics in magnetic dielectrics. Due to the slow phonon-magnon interaction in these materials, direct thermal effects of the laser excitation can only be seen on the time scale of almost a nanosecond and thus are clearly distinguished from the ultrafast nonthermal effects. However, laser pulses are shown to indirectly modify the magnetic anisotropy in rare-earth orthoferrites via the crystal field, and to bring about spin reorientation within a few picoseconds. More interesting, however, are the direct nonthermal effects of light on spin systems. We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on a femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites. In addition, circularly polarized pulses are shown to act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. An all-optical scheme of excitation and detection of different antiferromagnetic resonance modes with frequencies of up to 500GHz will be discussed as well. The reported effects open new and exciting possibilities for ultrafast manipulation of spins by light and provide new insight into the physics of magnetism on ultrafast time scales.
Percolation and the Josephson effect in high-Tc superconducting composites based on yttrium ceramics
Authors: Sanikidze J. G. , Kokhreidze R. G. , Odenov S. V.
Published: October 2006

Percolation processes and the magnetic susceptibility are investigated in composites based on yttrium high-Tc superconductors (Y-HTSCs). The superconducting fraction in the composites is determined for different amounts of an added nonsuperconducting fraction. The limit of percolation conduction via superconducting grains for a HTSC–insulator composite is (17±2)% superconducting fraction by volume. The Josephson properties of composite superconductors near the percolation limit are investigated.
Giant parametric amplification of the nonlinear response in a single crystal of beryllium in a quantizing magnetic field
Authors: Tsindlekht M. I. , Logoboy N. , Egorov V. S. , Kramer R. B. G. , Joss W. , Jansen A. G. M.
Published: October 2006

The nonlinear response to an ac magnetic field with and without parametric pumping was studied experimentally on a rod-like beryllium single crystal at low temperatures in a quantizing magnetic field applied parallel to the hexagonal axis. At low temperatures (⩽3K) giant parametric amplification of the nonlinear response is observed in narrow windows near de Haas-van Alphen (dHvA) beating antinodes, where the amplitude of the magnetic oscillations is maximal. This effect is of threshold character with respect to the amplitude of the dHvA oscillations and occurs as a result of a diamagnetic phase transition of a strongly correlated electron gas into nonuniform state, with the formation of Condon domain structure. It is shown that the nonuniform phase appears periodically in a magnetic field. The components of the rectified signal field reproduce the envelope of H-T critical curves and can be used for reconstruction of diamagnetic phase diagrams.
Liquid crystal lens prepared utilizing patterned molecular orientations on cell walls
Authors: Ye Mao , Yokoyama Yoshitaka , Sato Susumu
Published: October 2006

A liquid crystal (LC) lens prepared using patterned molecular orientations on cell walls is proposed. On each wall, the LC directors in a circular area are aligned to be parallel, while those outside the area are perpendicular, to the wall. A spatially varying director orientation and a lenslike distribution of refractive index may appear in the LC layer. The LC cell then becomes an optical lens even in the absence of any applied voltages. The focal length of the lens is electrically tunable. The size of the lens prepared in this way can become very small.
Fast ac electro-osmotic micropumps with nonplanar electrodes
Authors: Urbanski John Paul , Thorsen Todd , Levitan Jeremy A. , Bazant Martin Z.
Published: October 2006

This letter demonstrates dramatic improvements in flow rate and frequency range over conventional planar ac electro-osmotic (ACEO) pumps by exploiting three-dimensional (3D) stepped electrodes. A 3D ACEO pump was fabricated by electroplating steps on a symmetric electrode array and tested against a state-of-the-art asymmetric planar ACEO pump in a microfluidic loop. For all frequencies (0.1–100kHz), the 3D pump had a faster flow rate, in some cases by an order of magnitude. Their experimental results suggest that, after some optimization, mm/s velocities will be attainable with alternating battery voltages, which presents an exciting opportunity for microfluidics.
Dielectric properties and abnormal C-V characteristics of Ba0.5Sr0.5TiO3–Bi1.5ZnNb1.5O7 composite thin films grown on MgO (001) substrates by pulsed laser deposition
Authors: Tian Huyong , Wang Yu , Wang Danyang , Miao Jun , Qi Jianquan , Chan H. L. W. , Choy C. L.
Published: October 2006

Highly c-axis oriented Ba0.5Sr0.5TiO3-based composite thin films were grown on MgO (001) single-crystal substrates by pulsed laser deposition and the in-plane dielectric properties of the films evaluated. X-ray diffraction characterization revealed a good crystallinity. The dielectric constant and loss were found to be 200 and 0.001–0.007 at room temperature, respectively. The butterfly-shaped C-V characteristic curve evidenced an enhanced in-plane dielectric tunability of >90% in the films at 1MHz under a dc bias field of 0.8MV∕cm. A brief discussion is given on the abnormal C-V curves. Various tunable microwave applications of Ba0.5Sr0.5TiO3–Bi1.5ZnNb1.5O7 composite thin films are expected.
Room temperature, continuous wave operation of distributed feedback quantum cascade lasers with widely spaced operation frequencies
Authors: Wittmann Andreas , Giovannini Marcella , Faist Jérôme , Hvozdara Lubos , Blaser Stéphane , Hofstetter Daniel , Gini Emilio
Published: October 2006

Lasing properties of room temperature, continuous wave operated distributed feedback (DFB) quantum cascade lasers are reported. A bound-to-continuum active region was used to generate a broad gain spectrum. As a result, first-order DFB lasers employing different periods allowed us to achieve single mode continuous wave emission at several wavelengths ranging from 7.7to8.3μm at a temperature of +30°C. The frequency span corresponds to 8% of the center frequency.
Ablation of molecular solids under nanosecond laser pulses: The role of inertial confinement
Authors: Perez Danny , Lewis Laurent J. , Lorazo Patrick , Meunier Michel
Published: October 2006

The thermal routes to ablation in molecular solids having a long (micron scale) optical penetration depth are investigated under nanosecond laser pulses using a two-dimensional molecular-dynamics model. The authors demonstrate that the mechanisms of matter removal are mainly determined by the local degree of inertial confinement; by increasing level of confinement, these are (trivial) fragmentation, phase explosion, and heterogeneous nucleation of vapor bubbles at solid-liquid boundaries. The thermodynamic pathways to ablation are shown to be different from those predicted by the model of Miotello and Kelly [Appl. Phys. Lett. 67, 3535 (1995); Appl. Phys. A: Mater. Sci. Process. 69, S67 (1999)].
Development of Modal and Amodal Completion in Infants
Authors: Otsuka Yumiko , Kanazawa So , Yamaguchi Masami K
Published: October 2006

Visual completion has been divided into two types: modal and amodal. While psychophysical studies with adults provided several common properties between modal and amodal completion, studies with infants showed differential trends in the development of these perceptual abilities. In the present study, we further examined the development of these two kinds of visual completion in infants aged 3 to 6 months. We created a display composed of a partially overlapping circle and square. The display induced either modal or amodal completion depending on the colour. Infants were familiarised with either the modal or the amodal display. After this familiarisation, the infants were tested on their discrimination between the complete figure and the broken figure. If the infants could perceptually complete the figures in the familiarisation display, they were expected to show a novelty preference for the broken figure. A total of thirty-two infants participated in the present study. Our results suggest that modal completion develops by 3 – 4 months of age, whereas amodal completion develops by 5 – 6 months of age.
The chemistry of Eremophila spp. XVIII. A new class of diterpenes from Eremophila viscida
Authors: Ghisalberti EL , Hocart CH , Jefferies PR , Proudfoot GM , Skelton BW , White AH
Published: October 2006

Two new diterpenes have
been isolated from the resin of E. viscida Endl. Evidence for
their structure was obtained from spectroscopic data and from X-ray
crystallographic analysis which show them to be members of a new class of
diterpenes containing a C 5 extended acorane skeleton.
Crystal structure of aristoserratine
Authors: Bick IRC , Hai MA , Patrick VA , White AH
Published: October 2006

The crystal structure of
the alkaloid aristoserratine,* C20H24N2O,
has been determined by single-crystal X-ray diffraction methods at 295 K, the
structure being refined to a residual of 0.034 for 1107 independent 'observed'
reflections. Crystals are monoclinic, P21, a 14.836(5), b 8.568(3),
c 6.633(3) �, β 98.05(3)�, Z 2.
The relative configuration is established and, by inference, by comparison of
the circular dichroism spectrum with that of aristoteline, the absolute configuration is assigned.
Chiral induction in the addition of the anion from 3-(p-Methylbenzenesulfinyl)prop-1-ene with substituted benzaldehydes
Authors: Ridley DD , Smal MA
Published: October 2006

Addition of the anion from
3-(p-methylbenzenesu1finyl)prop-1-ene to substituted benzaldehydes affords
mixtures of α- and γ-products. The diastereoisomeric ratios. which
were determined by 1H n.m.r. spectroscopy, appeared relatively
independent of electronic factors. Possible transition state models to account
for the stereochemical aspects of the reaction are discussed.
Intrinsic chemistry of peptide ions: Field desorption and collision-induced decomposition of bradykinin
Authors: Neumann GM , Derrick PJ
Published: October 2006

The field desorption mass spectrum of bradykinin
and collision-induced decomposition spectra of ions formed from bradykinin during field desorption
are reported. Low-energy fragmentation pathways of bradykinin
are identified. It is proposed that bradykinin can
undergo rearrangement to a novel ion structure, characterized by a propensity
for cleavage at one specific site within the peptide.
The structure and function of oestrogens. VIII. Synthesis of 5,5, 10b-Trimethyl-cis-4b,5,6,10b,11,12-hexahydrochrysene-2,8-diol from 6-Methoxy-3,4-dihydronaphthalen-1(2H)-one
Authors: Collins DJ , Cullen JD , Fallon GD , Gatehouse BM
Published: October 2006

Treatment of
2-hydroxymethylene-6-methoxy-3,4-dihydronaphthalen-1(2H)-one (13a) with p-meth-oxyphenyllead triacetate afforded 93% of
2-formyl-6-methoxy-2-(p-methoxyphenyl)-3,4-dihydro- naphthalen-1(2H)-one
(14a) which upon deformylation and methylation gave
60% of 6-methoxy- 2-(p-methoxyphenyl)-2-methyl-3,4-dihydronaphthalen-1(2H)-one (17). An alternative route to the
α α'-disubstituted ketone (17) by way of
6-methoxy-2-methyl-3,4-dihydronaphthalen-1(2H)-one (15) and
2-chloro-6-methoxy-2-methyl-3,4-dihydronaphthalen-1(2H)-one (16) was less
efficient. Lithium aluminium hydride reduction of the ketone (17) followed by
acetylation yielded 80% of 1 ξ acetoxy- 6-methoxy-2-(p-methoxyphenyl)-2-methyl-1,2,3,4-tetrahydronaphthalene (23),
treatment of which with the trimethylsilyl enol ether of ethyl
2-methylpropanoate in the presence of zinc iodide afforded 71% of ethyl
(1SR,2RS)-2-methyl-2-[6'-methoxy-2'-(p-methoxyphenyl)-2'-methyl-1',2
',3',4'-tetrahydronaphthalen-yl'ξ-yl]propanoate (26a). Treatment of the ester (26a) or the
corresponding acid (26b) with methanesulfonic acid
yielded 68 or 82% respectively, of 2*-dimethoxy-5,5,10b-trimethyl-
cis-4b,10b,11,12-tetrahydrochrysen-6(5H)-one (27a); Clemmensen
reduction of this followed by demethylation with hydrobromicacidin aceticacid gave
49% of cis-5,5,10b-trimethyl-4b,5,6,10b,11,12-
hexahydrochrysene-2,8-diol (7a). The sterochemistry
of the ring junction in compound (7a) was established by X-ray crystallography
of the corresponding dimethyl ether (27b).
The reactivity of 3-Ethenyl-4-methylcyclohex-2-en-1-one and related compounds towards some carbanionic nucleophiles
Authors: Brown RFC , Burge GL , Collins DJ
Published: October 2006

The reaction of
3-ethenyl-4-methylcyclohex-2-en-1-one (4) with 2-methylcyclopentane-1,3-dione
in refluxing toluene containing pyridine gave 6% of 9bξ-hydroxy-3a,6-dimethyl-3a,4,5,6,7,9b-hexahydro-1H-benz[e]indene-3,9(2H,8H)-dione
(10). When the same reactants were heated at 100-110� (sealed tube) in benzene
containing t-butyl alcohol and diethylamine the main product (61%) was
5',6-dimethylspiro[bicyclo[3.2.1]octane-1,2'-cyclohexane]-3,6',8'-trione (11);
the yield of (11) was 72% when the reaction was carried out in the presence of
silica gel. Attempts to effect a similar reaction of the dienone (4) with
methyl 1β-t-butoxy-7aβ-methyl-5-oxo-1,2,3,3aα,4β,6,7,7a-octahydro-indene-4-carboxylate
(21a) gave no conjugate Michael addition product, but (21a) underwent aminolysis to the corresponding diethylamide (21b).
Attempts to alkylate the t-butoxy
β-keto ester (21a) under various conditions with 7-acetyloxy-7-ethenyl-8 ξ
methyl-1,4-dioxaspiro[4,5]decane
(41) failed. Similarly, attempts to effect alkylation
of the anion of the t-butoxy keto ester (21a) with
7-ethenyl-8-methyl-1,4-dioxaspiro[4,5]dec-6-ene (43) under Lewis acid catalysis
were also unsuccessful.
Oxidation of thiols by superoxide ion
Authors: Crank G , Makin MIH
Published: October 2006

Superoxide ion oxidizes aromatic thiols to disulfides or sulfonic acids. Benzene-1,2-dithiol and its
4-methyl analogue formed the cyclic disulfides dibenzo[c,g]tetrathiocins. Aliphatic thiols gave
disulfides, and ethane-1,2-dithiol and propane-1,3-dithiol formed the cyclic disulfides 1,2,5,6-
tetrathiocan and 1,2,6,7-tetrathiecan respectively. Butane-1,4-dithiol underwent an intramolecular
cyclization to 1,2-dithian. Cysteine was oxidized by O2-· to cysteic acid.
Cannabinoid studies. IV. Stereoselective and regiospecific syntheses of (±)-Δ9-trans- and (±)-Δ9-cis-6a, 10a-Tetrahydrocannabinol
Authors: Moore M , Rickards RW , R°nneberg H
Published: October 2006

Efficient syntheses of the
title compounds are achieved through the intermediate alcohols (13) and (15),
prepared by reaction of citral (10) with the
lithiated olivetol dimethyl and di(methoxymethy1)
ethers (4) and (6). Reaction of the alcohol (13) with boron tribromide
yields (�)-∆9-trans-6a,10a-
tetrahydrocannabinol (1) after regiospecific
dehydrobromination of its hydrogen bromide adduct,
whilst treatment of the alcohol (15) with trimethylsilyl bromide affords (�)-∆9-cis-6a,10a-tetra-hydrocannabinol(11).
The complementary stereoselectivity of these reactions may provide insight into
the nature of cannabinoid cyclization processes.
Two new diphenyl ethers and a new depside from the lichen Micarea prasina Fr
Authors: Elix JA , Jones AJ , Lajide LCBJ , James PW
Published: October 2006

Two new diphenyl ethers,
4-(2-carboxy-3-heptyl-5-methoxyphenoxy)-2-heptyl-6-hydroxybenzoic acid (micareic acid) (13),
4-(2-carboxy-3-heptyl-5-methoxyphenoxy)-2-heptyl-6-hydroxy-3-methoxybenzoic
acid (methoxymicareic acid) (27) and a new depside,
4-(2-heptyl-6-hydroxy-4-methoxybenzoyloxy)- 2-heptyl-6-hydroxybenzoic acid (prasinic acid) (34) have been detected in chemical races of
the lichen Micarea prasina
Fr. and isolated and characterized as the corresponding methyl esters. The
structure of the latter compounds has been confirmed by total synthesis. The
key steps in the synthesis of the diphenyl ethers (14), (26) involved Ullmann-like condensation between the 3-chloro 2-enone (17)
and the phenols (11), (31), and subsequent aromatization of the enol ethers (23) and (32). A biomimetic-type synthesis of
methyl micareate (48) has also been achieved by
treatment of the depside (33) with sodium hydride in dimethylformamide.
The Boc/Solid Phase Synthesis of Glu-Abu(P)-Leu
Authors: Perich JW , Reynolds EC
Published: October 2006

The synthesis of the 4-phosphono-2-aminobutanoyl-containing tripeptide , H- Glu -Abu(P)- Leu-OH.CF3C02H was accomplished by the use of Boc-Abu(PO3Me2)-OH in Boc /solid phase peptide synthesis. Peptide synthesis was performed by using Boc-Leu-polystyrene as the polymer support with the peptide assembled by the use of 1H-benzotriazol-1-yloxytris(pyrro1idin-1-yl) phosphonium hexafluorophosphate ( PyBOPR ) for the coupling of Boc amino acids and 50% CF3C02H/CH2C12 for cleavage of the Boc group from the Boc -peptide after each coupling cycle. The protected peptide was cleaved from the polymer support by hydrogen bromide in trifluoroacetic acid and final cleavage of the methyl groups from Glu-Abu(PO2Me2)-Leu was effected by silylitic treatment with 30% bromotrimethylsilane in acetonitrile.
Aluminum(III)-Malonate Equilibria: a Potentiometric Study
Authors: Powell HKJ , Town RM
Published: October 2006

The aluminium(III)-malonic acid (H2L) equilibria have been studied by potentiometric titration in aqueous solution at 25°C (I = 0.10 M KCl ). Data were consistent with the formation of simple binary complexes AlL + (log K1 = 6.711), AlL2- (log K2 = 4.815) and AlL33- (logβ3 = 14.104) in the pH range 2.2-5.5. There was also evidence for a minor species AlL2(OH)2- at pH > 5.8 for solutions with [Al3+]:[LH2] < 3.0 (log KD= -6.68). The protonation constants determined for malonic acid were log K1 = 5.43 and log K2 = 2.60 (corrected for K+ ion pairing).
Structural Study of an ent-Kaurane Lactone
Authors: Ghisalberti EL , Wen H , Skelton BW , White AH
Published: October 2006

The structure of the methyl ester derivative (2) of ent-20-hydroxy-16βH-kaurane-17,19-dioic acid 19,20-lactone has been determined by X-ray crystallographic methods. The δ-lactone ring adopts the chair conformation both in the solid state and in solution.
Diet of the bilby (Macrotis lagotis) in relation to substrate, fire and rainfall characteristics in the Tanami Desert
Authors: Southgate Richard , Carthew Susan M.
Published: October 2006

This study uses analysis of faecal pellets to assess the diet of the bilby (Macrotis lagotis) in an area spanning over 230 000 km2 in the Tanami Desert, Northern Territory. More specifically, we examine the link between diet composition, bilby prevalence and the landscape variables of fire, rainfall and substrate. Seed promoted by fire, particularly of Yakirra australiense, was found to be one of the most important components of the diet and constituted ~36% of the relative abundance of identifiable food particles. Bulb from Cyperus bulbosus was also an important component of the diet (18.5% relative abundance). Invertebrates accounted for 39% of the identifable food particles, and termites and beetles were the most common types. Bulb and seed formed a greater component of the diet in the central part of the study area where bilbies were more prevalent. Conversely, invertebrates were more dominant in the bilby diet on the northern and southern periphery of the Tanami Desert. Substrate type and antecedent rainfall associated significantly with the amount of seed from fire-promoted plants and total plant contained in the diet. Time since fire was an additional factor associated with the abundance of dietary fire-promoted seed. This suggests that the spatial and temporal variability of these landscape variables play an important role in controlling the availability of seed and bulb resources used by the bilby, and thus affect bilby prevalence. The results support the proposition that seed and bulb plant foods are exploited opportunistically and invertebrates, especially termites, are relied upon when plant food resources are scarce. Furthermore, the findings indicate that fire management could be used as a means to increase the favourability of habitat for the bilby in parts of its current range.
Habitat factors related to wild rabbit population trends after the initial impact of rabbit haemorrhagic disease
Authors: Calvete Carlos , Pelayo Enrique , Sampietro Javier
Published: October 2006

The European wild rabbit (Oryctolagus cuniculus) is an introduced pest species in Australia and New Zealand. Rabbits have a devastating negative impact on agricultural production and biodiversity in these countries, and Rabbit Haemorrhagic Disease (RHD) is currently included in control strategies for rabbit populations. On the other hand, the European wild rabbit is a key native prey species in the Iberian Peninsula. Since the arrival of RHD, however, rabbit populations have undergone dramatic decreases and several predator species at risk of extinction are currently dependent on the rabbit population density. Therefore, from the point of view of biodiversity conservation, evaluating habitat correlates and trends of rabbit populations after the first RHD epizootic is of great interest to improve the long-term control or promotion of wild rabbit populations. We estimated the relationship between habitat factors and long-term population trends as well as the relationships between habitat factors and rabbit abundance 2 and 14 years after the arrival of RHD in several Iberian rabbit populations. We observed that only 26% of surveyed populations seemed to experience an increase in rabbit abundance over the last 12 years and that this increase was higher in the low-rabbit-abundance areas of l992, leading to high rabbit abundance in 2004. Our results suggested that short- and long-term impacts of RHD were related to habitat quality. The initial impact of RHD was higher in more suitable habitats, but increasing long-term population trends were positively related to good habitat quality.
Sex-ratio bias across populations of a freshwater turtle (Testudines : Chelidae) with genotypic sex determination
Authors: Georges Arthur , Guarino Fiorenzo , White Melissa
Published: October 2006

Adult sex ratios vary considerably among populations of single species and across years, but the best evidence is drawn from species with temperature-dependent sex determination. It is difficult to disentangle the effects of bias in the production of the sexes and the effects of a range of other factors contributing to biased adult sex ratios. In this paper, we survey sex ratios across populations of a species constrained to produce 1 : 1 offspring sex ratios by genotypic sex determination and show considerable variation in adult sex ratios. Raw adult sex ratios of Emydura macquarii emmottii were significantly biased in nine of the 11 populations examined. In all but one case, the bias was strongly in favour of males. Part of the bias in sex ratio was attributed to the differing ages of maturity of males and females – males mature younger than females – which leads to more male cohorts being included in the calculations of sex ratio than female cohorts. However, correcting for this effect brought the sex ratios of the populations closer to parity, as expected, and accounted for an overall 62% of the male surplus evident in the adult sex ratio. Even so, it was insufficient to explain the strong male bias (1.2–2.9) in five of the nine populations initially showing such bias. This provides support to those who advise caution in interpreting adult sex ratio data for freshwater turtles in the context of demography, sex allocation or evaluating the impact of climate change.
Misclassification of occupation-based socioeconomic position and gender comparisons of socioeconomic risk
Authors: Ljung Rickard , Hallqvist Johan
Published: October 2006

Aims: Because occupational classification systems tend to be less precise in the female sector of the working market there has been concern that this might imply more misclassification of socioeconomic position among women, biasing comparisons of gender-specific socioeconomic differences in risk. Methods: The Stockholm Heart Epidemiology Program (SHEEP) is a population-based case-control study of risk factors for incident myocardial infarction. The study base included all Swedish citizens aged 45—70 in Stockholm County during 1992—94, 550 female and 1201 male cases, and 776 female and 1538 male controls. The use of an occupational classification as the base for categorizing socioeconomic position was compared with socioeconomic position based on detailed self-reported information on job titles and work tasks. Results: Women are categorized into fewer occupational categories than men and the socioeconomic heterogeneity within occupational categories is substantial for women as has been reported by others. However, despite more occupational categories for male types of jobs the socioeconomic heterogeneity within occupational categories is actually larger for men, implying larger misclassification among men. In simulations with different levels of socioeconomic misclassification among women, the effects on the gender comparison of socioeconomic differences in disease risk were small and they were mostly compensated for by less misclassification among men. Conclusions: The findings do not support the assumption that misclassification of socioeconomic position among women due to a restricted working market and a crude occupational classification for female jobs is an important issue when comparing measures of socioeconomic inequalities in health between men and women.
Human Bocavirus Infection in Young Children in the United States: Molecular Epidemiological Profile and Clinical Characteristics of a Newly Emerging Respiratory Virus
Authors: Kesebir Deniz , Vazquez Marietta , Weibel Carla , Shapiro Eugene D. , Ferguson David , Landry Marie L. , Kahn Jeffrey S.
Published: October 2006

BackgroundHuman bocavirus (HBoV) is a newly identified human parvovirus that was originally identified in the respiratory secretions of children with respiratory tract disease. To further investigate the epidemiological profile and clinical characteristics of HBoV infection, we screened infants and children <2 years of age (hereafter referred to as “children”) for HBoV

MethodsChildren for whom respiratory specimens submitted to a diagnostic laboratory tested negative for respiratory syncytial virus, parainfluenza viruses (types 1–3), influenza A and B viruses, and adenovirus, as well as asymptomatic children, underwent screening for HBoV by use of polymerase chain reaction (PCR). Respiratory specimens were obtained from the children from 1 January 2004 through 31 December 2004

ResultsTwenty-two (5.2%) of the 425 children who had a respiratory specimen submitted to the diagnostic laboratory and 0 of the 96 asymptomatic children were found to be positive for HBoV by PCR (P=.02). Fever, rhinorrhea, cough, and wheezing were observed in ⩾50% of the HBoV-positive children. Of the 17 children who had chest radiography performed, 12 (70.6%) had abnormal findings. HBoV appeared to have a seasonal distribution. Nucleotide polymorphisms were detected in the viral capsid protein (VP) 1/VP2 genes. Two distinct HBoV genotypes circulated during the study period

ConclusionsHBoV is circulating in the United States and is associated with both upper and lower respiratory tract disease in infants and young children
Preparation of SiO2 Glass from Model Powder Compacts: II, Sintering
Authors: SACKS MICHAEL D. , TSENG TSEUNG‐YUEN
Published: October 2006

The sintering behavior of powder compacts formed from spherical, nearly monosized SiO2 particles was investigated. Highly ordered compacts sintered to high density and translucency at 1000°C. In contrast, less homogeneous samples prepared from flocculated suspensions remained highly porous after sintering under the same conditions. Densification kinetics were determined over the temperature range 900° to 1050°C for ordered compacts. The viscosity at each sintering temperature and the activation energy for viscous flow were determined using available sintering models. Sintering of ordered compacts is divided into several stages. Densification, mercury porosimetry, and electron microscopy results indicate that the first stage is dominated by the shrinkage of three‐particle pore channels, whereas the second stage primarily involves the shrinkage of four‐particle pore channels.
Isothermal Sintering of Cordierite‐Type Glass Powders
Authors: GIESS EDWARD A. , FLETCHER JOSEPH P. , HERRON L. WYNN
Published: October 2006

Uniaxially pressed pellets of cordierite‐type glass powders were sintered in air at 800°, 820°, 840°, and 860°C. There was pronounced anisotropy of shrinkage for these pellets composed of nonspherical crushed glass particles, and the initial axial shrinkage rate was one‐half that of the diameter, as though axial particles had twice the radius of diametral ones. The total fractional shrinkage along axes was only 0.12, whereas that of diameters was 0.17. The temperature dependence of sintering followed that of the solid glass viscosity, which is described by the Fulcher equation using independently measured viscosity data. Viscosity decreased approximately an order of magnitude for every 40°C temperature increase. Surface tension calculated from published coefficients for the molar constituents was 0.36 N/m. Linear shrinkage obeyed the Frenkel viscous flow sintering model well, until complete densification was approached, where particles coalesced and thereby lost their identity. A Mackenzie‐Shuttleworth analysis, which is based on pore shrinkage, demonstrates the departure of these real powders from ideality. A simple Avrami‐type equation permits an empirical fit of data for the entire sintering range when the shrinkage value for 100% densification is known.
Impact Behavior of Coated Low‐Density Bodies
Authors: GREEN DAVID J.
Published: October 2006

Impact failure of the coating of space shuttle thermal protection tiles was confirmed to occur by a flexure process at low projectile velocities. The critical projectile velocity was measured for a variety of projectile sizes. The same failure process and damage sequence was observed in quasi‐static indentation tests. In these tests, the mechanical behavior agreed reasonably well with the elastic model of an infinite plate bonded to a semiinfinite foundation. The model indicates that the critical fracture load could be increased by increasing coating strength, thickness, or foundation stiffness, or by decreasing the Young's modulus of the coating.
Disproportionation of SO2 in Bubbles Within Soda‐Containing Glasses
Authors: GOLOB HELEN R. , SWARTS E. LOWELL
Published: October 2006

Deposits of S0; and Na2SO4 together in bubbles within production float glass are generated by disproportionation of SO2, derived from dissolved SO3, in company with Na2O from the interior bubble surfaces. This reaction proceeds rapidly in molten glass and also at temperatures well below Tg.
Computational Model for the Oxygen Potentials of Mixed Uranium‐Plutonium Oxide
Authors: KRISHNAIAH M. V. , SRIRAMAMURTI P.
Published: October 2006

A model based on simple thermodynamic considerations for calculating oxygen potentials of mixed uranium‐plutonium oxide fuel was developed. Oxygen potential values obtained using this model are presented as a function of temperature and O/M ratio for mixed oxide fuel containing 15 to 30 mol% plutonium oxides. Comparison with experimental data from the literature shows reasonably good agreement.
Improvements in Mechanical Properties in SiC by the Addition of TiC Particles
Authors: WEI G.C. , BECHER P.F.
Published: October 2006

Silicon carbide ceramics containing up to 24.6 vol% dispersed TiC particles yielded fully dense composites by hot‐pressing at 2000°C with 1 wt% Al and 1 wt% C added. The micro‐structure consists of fine TiC particles in a fine‐grained SiC matrix. Addition of TiC particles increases the critical fracture toughness of SiC (to ∼6 MPa·m1/2 at 24.6 vol% TiC) and yields high flexure strength (≥680 MPa), with both properties increasing with increasing volume fraction of TiC. The strengths at high temperatures are also improved by the TiC additions. Observations of the fracture path indicate that the improved toughness and strength are a result of crack deflection by the TiC particles.
Effect of pH on Crystal Phase of ZrO2 Precipitated from Solution and Calcined at 600°C
Authors: Davis Burtron H.
Published: October 2006

The pH of the solution from which the gel is precipitated determines the calcined zirconia crystal phase. Monoclinic zirconia is produced from materials precipitated in the 6.5 to 10.4 pH range; the tetragonal precursor is obtained for the 3 to 4 or 13 to 14 pH range. The calcination atmosphere, temperature history during calcination, and the presence of alkali do not appear to play a dominant role in determining the zirconia phase composition.
Fracture Mirror‐Failure Stress Relations in Weathered and Unweathered Window Glass Panels
Authors: Reed Dorothy A. , Bradt Richard C.
Published: October 2006

Published results for window glass panel failures were analyzed by using finite‐difference methods to determine the stress states at the fracture origins. Although the state of stress was often complex, it was found that the maximum principal tensile stress at the fracture origin correlated with the fracture mirror. size. Fracture mirror constants were calculated and found to agree closely with published values.
Occurrence of Ti3+ and Fe2+ in Mullite
Authors: Schneider Hartmut , Rager Helmut
Published: October 2006

Electron paramagnetic studies showed that Ti3+ and Fe2+ occur in mullites taken from a refractory material which was fused‐cast under a reducing atmosphere. Exposure of the mullite samples to temperatures >1600°C caused oxidation of Ti3+ and Fe2+ to Ti4+ and Fe3+, respectively.
High‐Temperature Failure of Polycrystalline Alumina: III, Failure Times
Authors: JOHNSON S. M. , DALGLEISH B. J. , EVANS A. G.
Published: October 2006

High‐temperature failure data have been obtained for two polycrystalline aluminas, revealing a strongly stress‐dependent failure time. The observed stress dependence has been compared with the dependence predicted by models of the nucleation, growth, and coalescence stages of failure. Only models of the coalescence phase indicate sufficient nonlinearity to be a plausible explanation of the data. Further observations and measurements of coalescence, involving continuous crack nucleation and shear‐band formation, are identified as requirements for further understanding of the rupture process.
Fracture of Brittle Solids in the Presence of Thermoelastic Stresses
Authors: KRSTIC VLADIMIR D.
Published: October 2006

A micromechanical model for strength behavior as a function of grain size in two‐phase materials with thermal expansion mismatch and in single‐phase materials with thermal expansion anisotropy is presented. The strength vs grain‐size plot is interpreted in terms of internal stresses and the ratio of grain to flaw size. The strength of thermally isotropic material is predicted to exhibit a weak grain‐size dependence with a negative grain‐size exponent normally different from 0.5. In thermally anisotropic poly crystalline solids, before the critical grain size for spontaneous cracking is reached, there will be a region of decreasing strength with increasing grain size due to an increase in the grain‐to‐flaw size ratio. When a critical grain size is reached, the ratio of grain to flaw size will decrease instantaneously and the strength will decrease in the same fashion. Very good agreement was obtained between predicted and experimentally observed strength behavior for TiO2 and MgO ceramics.
Thermal Decomposition in the System Si‐Y‐AI‐O‐N
Authors: MESSIER DONALD R. , DEGUIRE EILEEN J.
Published: October 2006

The limited transparency of high N (13.3 at.%) glasses in the system Si‐Y‐AI‐O‐N was found to be due to Si precipitates that resulted from thermal decomposition during melting. Thermodynamic analysis supported experimental findings that decomposition in N2 at 200 kPa resulted from oxide‐nitride reactions and not from simple dissociation of Si3N4. The Si content of the glass was reduced much more by substitution of AIN for Si3N4 in the glass batch and melting at low N2 pressure (200 kPa) than it was by merely melting in N2 at high pressure (1.6 MPa). The thermodynamic analysis suggested that decomposition could be minimized effectively by melting under a modest partial pressure of SiO(g), but this could not be verified experimentally.
Phase Relations in the System ZrO2‐Y2O3 at Low Y2O3 Contents
Authors: RUH ROBERT , MAZDIYASNI K. S. , VALENTINE P. G. , BIELSTEIN H. O.
Published: October 2006

Subsolidus phase relations in the low‐Y2O3 portion of the system ZrO2‐Y2O3 were studied using DTA with fired samples and X‐ray phase identification and lattice parameter techniques with quenched samples. Approximately 1.5% Y2O3 is soluble in monoclinic ZrO2, a two‐phase monoclinic solid solution plus cubic solid solution region exists to ∼7.5% Y2O3 below ∼500°C, and a two‐phase tetragonal solid solution plus cubic solid solution exists from ∼1.5 to 7.5% Y2O3 from ∼500° to ∼1600°C. At higher Y2O3 compositions, cubic ZrO2 solid solution occurs.
A “Compressed‐Spring” Analogy for Residual Stress Effects on the Extension of Indenter Flaws
Authors: SHETTY DINESH K. , VIRKAR ANIL V. , ROSENFIELD ALAN R. , DUCKWORTH WINSTON
Published: October 2006

The residual driving force of plastic zones associated with indenter flaws was modeled as that of a compressed spring. The limiting case of a zero‐stiffness spring converges to the constant‐force model and predicts maximum stable crack extension before instability and corresponding maximum strength degradation. An infinitely stiff spring, i.e. a rigid wedge, causes no stable crack growth or strength degradation. Comparison with stable‐crack‐growth data suggests that an appropriate‐stiffness spring model gives a better fit than the constant‐force model.
An Indentation Method for Measuring Matrix‐Fiber Frictional Stresses in Ceramic Composites
Authors: Marshall David B.
Published: October 2006

A simple method for measuring frictional stresses between the mairix and individual fibers in a ceramic composite is described. A standard microhardness indenter is used to apply a force to the end of the fiber and depress it below the matrix surface. The frictional stress is calculated from measurement of the applied force and the amount of slipping between the fiber and matrix.
Toughening Behavior in Sic‐Whisker‐Reinforced Alumina
Authors: Becher Paul F. , Wei George C.
Published: October 2006

The development of hot‐pressed Sic‐whisker‐reinforced alumina has resulted in composites with fracture toughness values ∼;8.7 MPa·m112 at 20 vol% SiC. Whisker orientation during processing leads to anisotropy in both fracture toughness and fracture strength. Fracture strengths are also limited by the ability to disperse the Sic whiskers; however, use of both fine alumina powders and ultrasonic dispersion techniques yields strengths ∼;800 MPa.
Leaching of E‐Glass
Authors: ELMER THOMAS H.
Published: October 2006

The extraction of acid‐soluble oxide constituents in E‐glass fibers was studied as a function of acid strength and time. Leaching was found to be diffusion controlled. Surface area, moisture adsorption, and weight loss measurements show that the porous structure that results on leaching is controlled by acid strength and time. Polymerization occurring on leaching and aging accounts for structural changes in the porous product.
Concurrent validity of the Alcohol Use Disorders Identification Test (AUDIT) and AUDIT zones in defining levels of severity among out‐patients with alcohol dependence in the COMBINE study
Authors: Donovan Dennis M. , Kivlahan Daniel R. , Doyle Suzanne R. , Longabaugh Richard , Greenfield Shelly F.
Published: October 2006

Aims  To examine among alcohol‐dependent out‐patient clients the concurrent validity of the Alcohol Use Disorders Identification Test (AUDIT) total score and ‘zones’ suggested by the World Health Organization for defining levels of severity of alcohol use problems.

Design  Participants were classified into AUDIT zones (AUDIT total score = 8–15, 16–19, 20–40) and compared on measures of demographics, treatment goals, alcohol consumption, alcohol‐related consequences, severity of dependence, physiological dependence, tolerance, withdrawal and biomarkers of alcohol use.

Setting  Eleven out‐patient academic clinical research centers across the United States.

Participants  Alcohol dependent individuals (n = 1335) entering out‐patient treatment in the Combined Pharmacotherapies and Behavioral Interventions (COMBINE) study.

Measurements  The AUDIT was administered as part of an initial screening. Baseline measures used for concurrent validation included the Structured Clinical Interview for Diagnostic and Statistical Manual, 4th edition (DSM‐IV) Disorders, the Alcohol Dependence Scale, the Drinker Inventory of Consequences, the Obsessive‐Compulsive Drinking Scale, the University of Rhode Island Change Assessment, the Thoughts about Abstinence Scale, the Form‐90, %carbohydrate‐deficient transferrin and gamma‐glutamyl transferase.

Findings  Indicators of severity of dependence and alcohol‐related problems increased linearly with total score and differed significantly across AUDIT zones. The highest zone, with scores of 20 and above, was markedly different with respect to severity from the other two zones and members of this group endorsed an abstinence goal more strongly.

Conclusions  The AUDIT total score is a brief measure that appears to provide an index of severity of dependence in a sample of alcohol‐dependent individuals seeking out‐patient treatment, extending its potential utility beyond its more traditional role as a screening instrument in general populations.
A pilot study of psychopathology in Developmental Coordination Disorder
Authors: Green D. , Baird G. , Sugden D.
Published: October 2006

Background  This paper explores the prevalence of emotional and behavioural disorders in children referred to a Community Paediatric Occupational Therapy service for assessment and treatment of problems with development of motor skills.

Methods  Parents of 47 children from a clinical sample of children who had been identified with Developmental Coordination Disorder (DCD) returned the Strengths and Difficulties Questionnaire (SDQ) – a brief measure of the pro‐social behaviour and psychopathology that can be completed by parents, teachers or youths.

Results  Significant emotional and behavioural problems were reported by 29 parents (62%) with a further six (13%) reporting problems in the borderline range. Seven children (15%) were without significant problems in one or more area although only four of these (9%) were outside the borderline range for all of the sub‐domains of the SDQ.

Discussion  A significant proportion of children with DCD were reported by their parents to be at risk of psychopathology. Further research is needed to understand the relationship between motor difficulties and emotional and behavioural symptoms; however, it is recommended that interventions for children with DCD should support mental health and behavioural problems as well as motor development.
The TRENDS Project: development of a methodology to reliably monitor the obesity epidemic in childhood
Authors: Binnie Karena
Published: October 2006

.
 
Rudolf M.C.J.,
Levine R.,
Feltbower R.,
Connor A. &
Robinson M.
(
2006
)

,
91
,
309
–
311
.

Aims  The government has set a target to halt the rise in childhood obesity in those aged under 11 years by 2010, but no system is in place to ascertain if this has been achieved. We aimed to develop a simple and reproducible methodology to monitor trends in childhood obesity.

Methods  A purposive sample of 10 primary schools and three secondary schools was selected. Children were measured with parental ‘opt out’ consent in reception class, year 4 and year 8 (aged 5, 9 and 13 years old respectively). Measurements were compared with those obtained locally in 1996–2001. Calculations were then performed to ascertain the sample size required to confidently identify a halt in the rise in obesity using three growth measures.

Results  A total of 999 children were measured with ascertainment of 95% in primary and 85% in secondary schools. The proportion of overweight and obese children aged 9 and 13 years old had increased since 1996–2001, although only 9‐year‐olds showed a significant rise. A general trend of an increase in obesity was observed with increasing age. Calculations showed that 1900–2400 children per age group are needed to detect a halt in the rise in obesity based on mean body mass index (BMI) standard deviation scores (SDS) by 2010 with 90% power, whereas 4200–10 500 children are needed for other measures.

Conclusion  We have developed a simple, cost‐effective methodology for accurately measuring the epidemic and recommend the use of mean BMI SDS for demonstrating if a halt has been achieved.
Walking, cycling and transport safety: an analysis of child road deaths
Authors: Reading Richard
Published: October 2006

.
 
Sonkin B.,
Edwards P.,
Roberts I. &
Green J.
(
2006
)

,
99
,
402
–
405
.

Objective  To examine trends in road death rates for child pedestrians, cyclists and car occupants.

Design  Analysis of road traffic injury death rates per 100 000 children and death rates per 10 million passenger miles travelled.

Setting  England and Wales between 1985 and 2003.

Participants  Children aged 0–14 years old.

Interventions  None.

Main outcome measures  Death rates per 100 000 children and per 10 million child passenger miles for pedestrians, cyclists and car occupants.

Results  Death rates per head of population have declined for child pedestrians, cyclists and car occupants but pedestrian death rates remain higher (0.55 deaths/100 000 children; 95% CI 0.42–0.72 deaths) than those for car occupants (0.34 deaths; 95% CI 0.23–0.48 deaths) and cyclists (0.16 deaths; 95% CI 0.09–0.27 deaths). Since 1985, the average distance children travelled as a car occupant has increased by 70%; the average distance walked has declined by 19%; and the average distance cycled has declined by 58%. Taking into account distance travelled, there are about 50 times more child cyclist deaths (0.55 deaths/10 million passenger miles; 0.32–0.89) and nearly 30 times more child pedestrian deaths (0.27 deaths; 0.20–0.35) than there are deaths to child car occupants (0.01 deaths; 0.007–0.014). In 2003, children from families without access to a vehicle walked twice the distance walked by children in families with access to two or more vehicles.

Conclusions  More needs to be carried out to reduce the traffic injury death rates for child pedestrians and cyclists. This might encourage more walking and cycling and also has the potential to reduce social class gradients in injury mortality.