bluuebunny/crossref_metadata_2025 huggingface dataset:
Static and Cyclic Fatigue of Alumina at High Temperatures: II, Failure Analysis
Authors: Lin Chih‐Kuang Jack , Socie Darrell F. , Xu Youren , Zangvil Avigdor
Published: April 2005

Failure mechanisms of an alumina, tested at 1200°C under static and various cyclic loading conditions, were examined. Slow crack growth of a single crack is the dominant mechanism for the failure in specimens under cyclic loading with a short duration of maximum stress at all applied stress levels, as well as at high applied loads for static loading and cyclic loading with a longer hold time at maximum stress. At low stress levels, failure of static loading and cyclic loading with a longer hold time at maximum stress might occur by formation and/or growth of multiple macrocracks. More importantly, for all the given loading conditions. The viscous glassy phase behind the crack tip could have a bridging effect on the crack surfaces. A simplified model for calculating effective stress intensity factor at the crack tip under static and various cyclic loading demonstrated a trend consistent with the stress–life data.
Kinetics of Anatase TiO2 Surface Area Reduction in a Mixture of HCI, H2O, and O2: II, Quantitative Modeling
Authors: Gruy Frédéric , Pijolat Michèle
Published: April 2005

From the experimental rate for surface area reduction of anatase TiO2, expressed versus the partial pressure in H2O and the surface content of chloride ion, a kinetic model is proposed in which two parallel mechanisms are involved. Two ways of material transport appear to contribute to the surface area loss: in the vapor phase and at the surface of the oxide. The related rate‐determining steps are attributed to the formation of the volatile compound Ti(OH)2Cl2 in the first case, and to the diffusion of hydroxyl ions in the second one. At high partial pressure of water, the rate is enhanced by surface interactions between water molecules and chlorine‐containing species.
Fracture and Contact Adhesion Energies of Mica‐Mica, Silica‐Silica, and Mica‐Silica Interfaces in Dry and Moist Atmospheres
Authors: Wan Kai‐Tak , Smith Douglas T. , Lawn Brain R.
Published: April 2005

A study is made of the factors that contribute to the energy of mica‐mica, silica‐silica, and mica‐silica interfaces in the presence of moist atmospheres. Energies are measured using brittle fracture and contact adhesion techniques. Both “virgin” and “healed” interfaces are investigated, with special attention on the latter. The fracture and adhesion data overlap, reflecting a common underlying separation process by “sharp‐crack propagation.” The study identifies several contributors to the interface adhesion energies. At virgin mica‐mica and silica‐silica interfaces the energy is determined by primary ionic‐covalent attraction, and by the screening of this attraction by condensed moisture from the atmosphere. At healed interfaces the energy depends on both environmental interaction and “lattice” coherence. At retracted cracks in mica‐mica most of the virgin ionic attraction is retained. On misorienting separated cleavage halves prior to recontact the interaction energy drops substantially: in “dry” atmosphers (relative humidity <5%) a portion of the Coulombic interaction persists in the form of “macroscopic domains” of electrostatic charge, attributable to long‐range order in the cation sublattice; in “wet” atmospheres (relative humidity >50%) capillary forces dominate. The dissimilar mica‐silica system exhibits the same dominance by capillary forces in wet atmospheres. However, in dry atmospheres the adhesion energy becomes inordinately high, from spontaneous transfer of electronic charge from one surface to the other. The implications of these observations concerning mechanical properties of brittle ceramics are discussed.
Formation of Reaction‐Bonded Silicon Nitride from Silane‐Derived Silicon Powders: Macroscopic Kinetics and Related Transport Phenomena
Authors: Sheldon Brian W. , Szekely Julian , Haggerty John S.
Published: April 2005

Reaction‐bonded silicon nitride (RBSN) with little or no residual silicon was formed from laser‐synthesized silicon powders and N2, at low temperatures and in short times (<10 min at 1250°C, <1 h at 1150°C). The nitriding kinetics were studied with thermogravimetric analysis (TGA). Samples formed in the TGA furnace between 1150° and 1350°C were completely converted to silicon nitride near their centers, with residual silicon near the external surfaces. These unusual composition profiles were not observed in samples that were formed in a higher‐purity atmosphere. Various experimental observations were compared to analyses of heat and mass transport, and it was determined that these composition in the nitriding gas. These analyses also indicated that heat transfer, N2 diffusion, and Si evaporation and transport all affect the nitriding kinetics under certain conditions.
High‐Density Yttria for Practical Ceramic Applications
Authors: Micheli Adolph L. , Dungan Dennis F. , Mantese Joseph V.
Published: April 2005

This paper describes a process by which highly reactive yttria powder can be sintered to high density at a relatively low firing temperature to form a variety of useful ceramic items. The process utilizes an aqueous polymer to precipitate a yttrium precursor. The yttrium precursor is thermally treated to form a friable oxide ash. After a double‐calcination‐grind procedure, high‐density yttria items such as substrates, crucibles, and nozzles can be fabricated.
T‐pO2 Topologic Analysis of Phase Relations in the System CaO–CrO–Cr2O3–SiO2
Authors: Nell Johan , de Villiers Johan P. R.
Published: April 2005

A temperature (T)− oxygen partial pressure (pO2) topologic analysis of phase relations in the system CaO–CrO–Cr2O3–SiO2, involving divalent and trivalent chromium, was undertaken to determine the relative positions of isobaric invariant points and univariant lines in T‐pO2 space. Liquidus phase relationships in equilibrium with metallic chromium, CO2–H2 gas mixtures, and air were used to identify the univariant and invariant assemblages involving Cr2+ and Cr3+. The T‐pO2 grid was constructed using Schreine‐makers rules for the disposition of univariant lines about an invariant point. The topological relationship between univariant lines and invariant points assists in the interpretation of phase relationships over the T‐pO2 regions that were not experimentally investigated. For example, the effect of pO2 on the liquidus phase relationships involving CaSiO3 (wollastonite), Cr2O3 (eskolaite), and Ca3Cr23+Si3O12 (uvarovite) is clearly illustrated by the grid; these details are not borne out by the experimentally determined phase diagrams. The grid furthermore illustrates the stability fields of the Cr2+ ‐bearing phases, (Ca0.4Cr0.62+)Cr23+ O4 and CaCr2+Si4O10 as a function of temperature and pO2 and demonstrates the observed increase in liquidus temperatures with increasing pO2.
Fibrous Monolithic Ceramics: I, Fabrication, Microstructure, and Indentation Behavior
Authors: Baskaran Suresh , Nunn Stephen D. , Popovic Dragan , Halloran John W.
Published: April 2005

Monolithic ceramics have been fabricated from coated green fibers to create fibrous microstructures. The fibrous monoliths consist of high aspect ratio polycrystalline regions (cells) of a primary phase regions (cell boundaries) designed to improve fracture resistance. The cells are the remnants of the green fiber which consists of ceramic powder and a polymer binder. The coating applied on the green fiber forms the cell boundaries. Fabrication and microstructure are described for fibrous monoliths in the SiC/graphite, silicon nitride/BN, alumina/alumina–zirconia, alumina/aluminum titanate, alumina/nickel and Ce‐TZP/alumina–Ce–zirconia systems. The SiC/graphite fibrous monolith displays noncatastrophic failure in flexure, with shear delamination along the weak graphite layers. Indentations in SiC/graphite cause cells to spall, with crack arrest and extrusion of graphite from the cell boundaries. Crack deflection and spalling of cells are also observed in alumina/alumina–zirconia fibrous monoliths. In the Ce‐TZP/alumina system, transformed regions around indentations are significantly modified by the alumina‐containing cell boundaries.
High‐Temperature Healing of Cracklike Flaws in Titanium Ion‐Implanted Sapphire
Authors: Powers James D. , Glaeser Andreas M.
Published: April 2005

Controlled‐geometry voids were introduced into unim‐planted and Ti‐implanted high‐purity c‐axis sapphire substrates using microfabrication techniques and ion beam etching, and subsequently transferred to an internal interface by hot‐pressing. The morphological evolution of crack‐like and channellike defects oriented parallel to the basal plane in response to anneals at 1700°C was studied. The healing behavior of defects in the unimplanted and Ti‐ion‐implanted samples differs significantly. Ti additions appear to reverse the directional dependence of the healing characteristics in undoped sapphire, greatly stabilizing defects with edges aligned along the [1100] direction, while reducing the stability of defects with edges aligned parallel to the [1120] direction relative to unimplanted sapphire. The healing characteristics of unimplanted and Ti‐implanted sapphire substrates are compared and contrasted with those observed previously in Ca‐ and Mg‐ion‐implanted sapphire.
Mechanism of AlN Formation through the Carbothermal Reduction of Al2O3 in a Flowing N2 Atmosphere
Authors: Lefort Pierre , Billy Michel
Published: April 2005

Mixtures of Al2O3, and C powders in a molar ratio of 1:3 were reduced in a N2 atmosphere. The effects of time, temperature, particle size of both reactants, and N2 flow rate were investigated. Kinetics show that the rate‐limiting process is the combustion of carbon, which leads to the reaction mechanism through the following basic steps:

Al2O3= 2Al + 3/2 O2

3C + 3/2 O2→ 3CO (slow, with or without intermediate formation of CO2)

2Al + N2= 2AlN (fast)

All of the experimental results have been discussed on the basis of this model, which allows one to predict the best conditions for preparing AlN powders.
Synthesis and Processing Characteristics of Ba0.65Sr0.35TiO3Powders from Catecholate Precursors
Authors: Ali Naseef J. , Milne Steven J.
Published: April 2005

Powders of composition Ba0.65Sr0.35TiO3were prepared from catecholate precursor phases, BaTi(C6H4O2)3and SrTi (C6H4O2)3. The physical and chemical properties of the base powders, and those doped with 0.2 wt% manganese, are reported in detail. The dimensions of the primary particles in the starting powders were of the order of 20–50 nm, but the occurrence of abnormal grain growth during sintering promoted grain sizes in the ceramic of up to ∼100 μm. In some microstructures, coarse grains coexisted with a ∼1‐μm fraction to produce a characteristic bimodal grain size distribution. By contrast, under comparable sintering conditions, namely 1350° or 1400°C for 1 h, grain growth in Mn‐doped samples was suppressed, leading to uniform microstructures with a grain size of only a few micrometers. The pellet densities were nevertheless similar, 97% of theoretical in both doped and undoped samples. No significant difference was observed in the dielectric permittivity of the two compositions: the peak relative permittivity occurred at ∼20°C, with a maximum value of ∼22 000.
Wear of Some Advanced Ceramics under a Sharp Indenter in Unidirectional Sliding
Authors: Mukerji J. , Das P. K.
Published: April 2005

The wear of reaction‐bonded SiC (RSSiC), dense silicon nitride (DSN), tetragonal zirconia ZrO2 (t), and alumina‐titanium nitride (Al2O3–TiN) composites have been studied under a sliding diamond indenter having an included angle of 90° and a tip radius of 6 μm at a sliding speed of 8 mm/s. The relative wear resistance as measured from the track diameter was in the order DSN > Al2O3–TiN > RSSiC > ZrO2(t). The track width showed a straight‐line relationship with the square root of load, implying that lateral cracking was responsible for the wear. The wear rates decreased with load and varied from 1 × 10−5 to 2 × 10−5mm/(m.g) for the above ceramics. The wear rate increased sharply as the velocity increased over 1 m/min at a load of 300 g and above due to frictional heat generated because of the work of sliding.
High‐Thermal‐Expansion Polycrystalline Leucite Ceramic
Authors: Ota Toshitaka , Takahashi Minoru , Yamai Iwao , Suzuki Hisao
Published: April 2005

A high‐thermal‐expansion ceramic consisting of leucite crystals was prepared by sintering leucite powder. The densification was promoted by adding Li2CO3 or Na2CO3. The leucite ceramic obtained had a thermal expansion coefficient of about 2.4 × 10−5/°C from room temperature to 600°C. Some of the Li+ and Na+ ions were incorporated into the leucite crystal lattice to form solid solutions, and the characteristic tetragonal‐cubic inversion point shifted from ca. 600° to 650°C.
Is buscopan effective in meat bolus obstruction?
Authors: Thomas L. , Webb C. , Duvvi S. , Jones T. , Reddy K.T.V.
Published: April 2005

Objective:  To assess the efficacy of hyoscine butyl bromide (buscopan) in relieving oesophageal meat bolus obstruction.

Design:  Retrospective review of case notes.

Setting:  Secondary otorhinolaryngology care.

Participants:  Twenty‐nine patients who presented to the Accidents & Emergency department satisfying, inclusion criteria: (i) ≥16 years old, (ii) patients with only meat bolus obstruction and (iii) had either only buscopan or no medications. Exclusion criteria were: (i) <16 years of age, (ii) patients who received any medications other than or in addition to buscopan, (iii) other foreign body obstructions and (iv) any patient in whom the approximate time of resolution of obstruction was not documented.

Results:  Twenty‐nine patients with 31 episodes of obstruction were analysed. Twenty‐two episodes were treated with buscopan and in 18 (82%) the obstruction was relieved. Two had spontaneous relief >24 h later and two had surgical disimpaction. In nine episodes, where no medications were given, seven (78%) cleared spontaneously and two had surgical removal. Fisher's exact test failed to show any significant difference between the two groups. The study groups were too small and power calculation showed that the number required for statistically validated result would be 140 in each group.

Conclusion:  Routine use of buscopan in oesophageal obstruction especially in the upper two‐thirds needs to be reviewed because of the possibility of side‐effects and lack of objective evidence of its efficacy.
Dental side‐effects of mandibular advancement splint wear in patients who snore
Authors: Battagel J.M. , Kotecha B.
Published: April 2005

Objectives:  (a) To evaluate the longer term orthodontic side‐effects of a Herbst mandibular advancement splint (MAS) in subjects with sleep disordered breathing. (b) To determine whether these are related to dental occlusion, degree of mandibular advancement or duration of appliance wear.

Design:  Retrospective, cohort study.

Setting: Teaching hospital dental school.

Participants:  Subjects with sleep disordered breathing who had been wearing an MAS regularly (a minimum of 5 h per night, six nights a week) for at least 2 years. Of 192 subjects who were identified, 30 fulfilled the inclusion criteria and were prepared to attend for review.

Interventions:  Dental casts were obtained and BMI and Epworth Sleepiness Scale scores recorded. These data were compared with those collected when the subject was first referred. A questionnaire was completed concerning MAS use, side‐effects and any problems associated with the device.

Main outcome measures:  Changes in incisor tooth position.

Results:  Median duration of MAS wear was 3.64 years. Small, statistically significant reductions in both vertical (−0.4 mm) and horizontal (−0.5 mm) overlap of the incisor teeth were found. This correlated with the degree of vertical opening of the MAS but was not related to the amount of mandibular protrusion or the duration of appliance wear.

Conclusions:  Patients who are considered suitable for MAS should be warned that dental changes may occur. Thus referring surgeons should also be aware of this possibility.
Veterinary pharmacovigilance. Part 3. Adverse effects of veterinary medicinal products in animals and on the environment
Authors: WOODWARD K. N.
Published: April 2005

Like humans, animals may experience adverse effects when treated with medicinal products. These effects may be related to the pharmacological or toxicological properties of the substances used or they may arise because of hypersensitivity. Veterinary medicinal products may also possess the ability to harm the environment. This paper reviews the potential of veterinary medicinal products to cause adverse effects in animals and on the environment.
Veterinary pharmacovigilance. Part 4. Adverse reactions in humans to veterinary medicinal products
Authors: WOODWARD K. N.
Published: April 2005

Although seemingly rare, adverse reactions to veterinary products do occur. These may arise from inadvertent exposure during use or as a result of occupational accidents. They are often mild in nature and include adverse effects such as minor skin reactions. However, more serious reactions may occur, and they are not restricted to the effects of the veterinary medicines themselves. For example, high‐pressure injection injuries may occur as a result of accidents occurring during animal vaccination operations. This paper reviews some of these events, mentions where appropriate the regulatory actions taken, and describes some of the measures used to minimise such effects in the future, and serves to bring the issues discussed here to the attention of pharmacologists, pharmacoepidemiologists and others who train those who use veterinary medicinal products.
Itraconazole in the treatment of acute and recurrent vulvovaginal candidosis: comparison of a 1‐day and a 3‐day regimen
Authors: Spacek J. , Buchta V.
Published: April 2005

Itraconazole is a systemic triazole with a broad‐spectrum antifungal effect which belongs to a standard choice for the treatment of vulvovaginal candidosis. Thirty‐four patients with acute and 26 patients with recurrent form of culture documented attacks of vulvovaginal candidosis were evaluated. There was frequent discrepancy between severe symptoms and weaker signs in patients with recurrent form than in the group with acute sporadic form. Eighteen patients with the acute form and 13 patients with the recurrent form of vulvovaginal candidosis received 1‐day therapy (twice 200 mg of itraconazole in 1 day). Sixteen patients with the acute form and 13 patients with the recurrent form received 3‐day therapy (200 mg of itraconazole daily for three following days). The cure rates 1 month after treatment were 97.1 and 76.9% in patients with the acute sporadic and recurrent form of vulvovaginal candidosis, respectively. Positive cultures in the latter group documented relapses. These clinical failures were not related to the resistance of yeasts to itraconazole. With the exception of one case of alopecia areata, side effects were minimal. The application of the long‐term regimens and suppressive therapy with azole drugs is suggested in patients with recurrent vulvovaginal candidosis.
Place(ment) matters: students’ clinical experiences and their preferences for first employers
Authors: Andrews G. J. , Brodie D. A. , Andrews J. P. , Wong J. , Thomas B. G.
Published: April 2005

Background  Although a significant volume of nursing research has focused on students’ experiences of clinical placements, to date, none has considered these experiences in the context of workforce recruitment and specifically how they may impact upon preferences for working for health care providers.

Methods  In this context, the research used a place‐sensitive geographical perspective and a combined questionnaire (n = 650), interview (n = 30) and focus group (n = 7) method to collect data on the complex range of clinical experiences which together impact upon the perceived attractiveness of different health care settings.

Findings  The data identified a range of experiential factors associated with mentorship, ward management, learning opportunities and racism. An important finding was that although students’ experiences are obtained at the micro ward level, even if they may not necessarily reflect what happens throughout the hospital, they potentially impact, both positively and negatively, upon their broader perceptions of the hospital and the likelihood of seeking work there.

Implications  The study highlighted a variety of issues that should be addressed by both higher education institutions and hospitals so that they may be able to provide a more consistent and positive experience for students. In the longer term, this may pay dividends through increased recruitment of new graduates.
Implicit Bayesian Inference Using Option Prices
Authors: Martin Gael M. , Forbes Catherine S. , Martin Vance L.
Published: April 2005

Abstract.  A Bayesian approach to option pricing is presented in which posterior inference about the underlying returns process is conducted implicitly via observed option prices. A range of models allowing for conditional leptokurtosis, skewness and time‐varying volatility in returns are considered, with posterior parameter distributions and model probabilities backed out from the option prices. Models are ranked according to several criteria, including out‐of‐sample predictive and hedging performance. The methodology accommodates heteroscedasticity and autocorrelation in the option pricing errors, as well as regime shifts across contract groups. The method is applied to intraday option price data on the S&P500 stock index for 1995. While the results provide support for models that accommodate leptokurtosis and skewness, no one model dominates when all criteria are considered.
Evolution of fluid chemistry during travertine formation in the Troll thermal springs, Svalbard, Norway
Authors: HAMMER Ø. , JAMTVEIT B. , BENNING L. G. , DYSTHE D. K.
Published: April 2005

Arctic hydrothermal springs at Bockfjorden, Svalbard, have isotope and trace element signatures indicative of derivation from glacial melt waters with minor contribution from seawater. Downstream gradients in water chemistry, isotopic composition and carbonate precipitation rates have been documented for the Troll spring and travertine terrace system. The main controls on the downstream evolution of these parameters are carbon dioxide degassing, calcite precipitation, evaporation and biological activity. The carbonate precipitation rates not only show an approximately parabolic dependence on the calcite supersaturation levels, but depend also on local hydrodynamics. Downstream loss of light isotopes of oxygen and hydrogen can be explained as an effect of evaporation, as estimated using chloride as a conservative marker. Biological activity affects nitrate and bromide concentrations and influences the morphology of calcite precipitates.
Impact of different pasteurization temperatures on the survival of microbial contaminants isolated from pasteurized milk
Authors: DUMALISILE PHOLISA , WITTHUHN R CORLI , BRITZ TREVOR J
Published: April 2005

The thermal inactivation of selected microbes was studied using the low temperature long time (LTLT), high temperature short time (HTST) and ‘pot’ pasteurization methods. Survivors were enumerated after heating for up to 40 min for the LTLT and HTST pasteurization methods and after heating for up to 30 min for the ‘pot’ pasteurization method. With the exception of the Bacillus cereus strain, the selected microbes did not survive the LTLT and HTST pasteurization methods. The results from the ‘pot’ pasteurizer showed that B. cereus, Chryseobacterium meningosepticum, Pseudomonas putida, Acinetobacter baumannii and Escherichia coli strains survived the pasteurization conditions applied, showing that the ‘pot’ pasteurizer does not pasteurize effectively.
Influence of trypsin action in yoghurt milk on the release of caseinophosphopeptide‐rich fractions and physical properties of the fermented products
Authors: LORENZEN PETER CHR , MEISEL HANS
Published: April 2005

The influence of trypsin action in yoghurt milk on the release of caseinophosphopeptide (CPP)‐rich fractions was studied and the physical properties of the fermented products determined. Trypsin treatment of skim milk led to increased fermentation times and a substantially lowered production of l‐lactic acid as well as to delayed and reduced proteolysis caused by peptidases of the starter cultures. The functional properties of the milk proteins were decreased and the sensory properties less pronounced in yoghurt from trypsin‐treated milk, but were described as less bitter than samples from nontreated milk. The CPP sequences β‐CN(1–25)‐4P and α

s1

‐CN(43–79)‐7P were released during enzyme treatment.
Comparative study of the efficacy of three coagulants in treating dairy factory waste water
Authors: HAMDANI A , MOUNTADAR M , ASSOBHEI O
Published: April 2005

The treatment of dairy factory waste water by coagulation and decantation has shown that calcium hydroxide at a weak dose of 0.49–0.63 g provides the highly efficient removal of suspended matter (SM) (94%) and total phosphorus (Tp‐P) (89%) accompanied by an average elimination of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN‐N), faecal coliforms (FC) and faecal streptococci (FS). This is within the Moroccan limits for the first two parameters (SM and TP‐P). The dose necessary to obtain optimal removal is 0.8–1.2 g when using aluminium sulfate and 0.6–0.75 g with iron chloride and the percentage elimination of chemical and bacteriological pollutants is not substantial. However, coagulation by calcium hydroxide induced less sludge (0.93 g/L) than either aluminium sulfate (1.21 g/L) or iron chloride (1.38 g/L). In terms of cost, the price of treating 1 m3 of dairy effluent by using calcium hydroxide is lower (approximately 25 times less expensive) than when using the other two coagulants.
Induction of hypoxia inducible factor‐1 attenuates metabolic insults induced by 3‐nitropropionic acid in rat C6 glioma cells
Authors: Yang Ya‐Ting , Ju Tzyh‐Chwen , Yang Ding‐I
Published: April 2005

Compromised mitochondrial function in neurons and glia has been observed in several neurodegenerative disorders, including Huntington's disease and Alzheimer's disease. Chemical/hypoxic preconditioning may afford protection against subsequently more severe oxidative damages. In this study, we tested whether induction of hypoxia inducible factor‐1 (HIF‐1) may exert cytoprotective effects against mitochondrial dysfunction caused by 3‐nitropropionic acid (3‐NP) in glial cells. Preconditioning of C6 astroglial cells with cobalt chloride, mimosine (MIM), and desferrioxamine (DFO), all of which known to activate HIF‐1, significantly attenuated cytotoxicity induced by 3‐NP, an irreversible inhibitor of mitochondrial complex II, and antimycin A, a mitochondrial complex III inhibitor. Application of cadmium chloride capable of neutralizing cobalt‐induced HIF‐1 activation, HIF‐specific oligodeoxynucleotide (ODN) decoy, and antisense phosphorothioate ODN against HIF‐1α abolished the protective effect mediated by preconditioning with cobalt chloride. Preloading of C6 cells with SN50, PD98059, or SB202190, the respective inhibitor of nuclear factor‐κB (NF‐κB), p44/p42 extracellular signal‐regulated kinase (ERK), and p38 mitogen‐activated protein kinase (MAPK), failed to affect the protection afforded by cobalt preconditioning. Taken together, these results suggest that HIF‐1 induction secondary to preconditioning with cobalt chloride or iron chelators may mediate the protective effects against metabolic insult induced by the mitochondrial inhibitor 3‐NP in C6 astroglial cells.
Decreased expression of hypothalamic neuropeptides in Huntington disease transgenic mice with expanded polyglutamine‐EGFP fluorescent aggregates
Authors: Kotliarova Svetlana , Jana Nihar R. , Sakamoto Naoaki , Kurosawa Masaru , Miyazaki Haruko , Nekooki Munenori , Doi Hiroshi , Machida Yoko , Wong Hon Kit , Suzuki Taishi , Uchikawa Chiharu , Kotliarov Yuri , Uchida Kazuyo , Nagao Yoshiro , Nagaoka Utako , Tamaoka Akira , Oyanagi Kiyomitsu , Oyama Fumitaka , Nukina Nobuyuki
Published: April 2005

Huntington disease is caused by polyglutamine (polyQ) expansion in huntingtin. Selective and progressive neuronal loss is observed in the striatum and cerebral cortex in Huntington disease. We have addressed whether expanded polyQ aggregates appear in regions of the brain apart from the striatum and cortex and whether there is a correlation between expanded polyQ aggregate formation and dysregulated transcription. We generated transgenic mouse lines expressing mutant truncated N‐terminal huntingtin (expanded polyQ) fused with enhanced green fluorescent protein (EGFP) and carried out a high‐density oligonucleotide array analysis using mRNA extracted from the cerebrum, followed by TaqMan RT‐PCR and in situ hybridization. The transgenic mice formed expanded polyQ‐EGFP fluorescent aggregates and this system allowed us to directly visualize expanded polyQ aggregates in various regions of the brain without performing immunohistochemical studies. We show here that polyQ‐EGFP aggregates were intense in the hypothalamus, where the expression of six hypothalamic neuropeptide mRNAs, such as oxytocin, vasopressin and cocaine‐amphetamine‐regulated transcript, was down‐regulated in the transgenic mouse brain without observing a significant loss of hypothalamic neurons. These results indicate that the hypothalamus is susceptible to aggregate formation in these mice and this may result in the down‐regulation of specific genes in this region of the brain.
Tryptophan metabolism and oxidative stress in patients with Huntington's disease
Authors: Stoy N. , Mackay G. M. , Forrest C. M. , Christofides J. , Egerton M. , Stone T. W. , Darlington L. G.
Published: April 2005

Abnormalities in the kynurenine pathway may play a role in Huntington's disease (HD). In this study, tryptophan depletion and loading were used to investigate changes in blood kynurenine pathway metabolites, as well as markers of inflammation and oxidative stress in HD patients and healthy controls. Results showed that the kynurenine : tryptophan ratio was greater in HD than controls in the baseline state and after tryptophan depletion, indicating increased indoleamine dioxygenase activity in HD. Evidence for persistent inflammation in HD was provided by elevated baseline levels of C‐reactive protein, neopterin and lipid peroxidation products compared with controls. The kynurenate : kynurenine ratio suggested lower kynurenine aminotransferase activity in patients and the higher levels of kynurenine in patients at baseline, after depletion and loading, do not result in any differences in kynurenic acid levels, providing no supportive evidence for a compensatory neuroprotective role for kynurenic acid. Quinolinic acid showed wide variations in blood levels. The lipid peroxidation data indicate a high level of oxidative stress in HD patients many years after disease onset. Levels of the free radical generators 3‐hydroxykynurenine and 3‐hydroxyanthranilic acid were decreased in HD patients, and hence did not appear to contribute to the oxidative stress. It is concluded that patients with HD exhibit abnormal handling of tryptophan metabolism and increased oxidative stress, and that these factors could contribute to ongoing brain dysfunction.
Adenosine A2A receptors control the extracellular levels of adenosine through modulation of nucleoside transporters activity in the rat hippocampus
Authors: Pinto‐Duarte António , Coelho Joana E. , Cunha Rodrigo A. , Ribeiro Joaquim Alexandre , Sebastião Ana M.
Published: April 2005

Adenosine, a neuromodulator of the CNS, activates inhibitory‐A1 receptors and facilitatory‐A2A receptors; its synaptic levels are controlled by the activity of bi‐directional equilibrative nucleoside transporters. To study the relationship between the extracellular formation/inactivation of adenosine and the activation of adenosine receptors, we investigated how A1 and A2A receptor activation modifies adenosine transport in hippocampal synaptosomes. The A2A receptor agonist, CGS 21680 (30 nm), facilitated adenosine uptake through a PKC‐dependent mechanism, but A1 receptor activation had no effect. CGS 21680 (30 nm) also increased depolarization‐induced release of adenosine. Both effects were prevented by A2A receptor blockade. A2A receptor‐mediated enhancement of adenosine transport system is important for formatting adenosine neuromodulation according to the stimulation frequency, as: (1) A1 receptor antagonist, DPCPX (250 nm), facilitated the evoked release of [3H]acetylcholine under low‐frequency stimulation (2 Hz) from CA3 hippocampal slices, but had no effect under high‐frequency stimulation (50 Hz); (2) either nucleoside transporter or A2A receptor blockade revealed the facilitatory effect of DPCPX (250 nm) on [3H]acetylcholine evoked‐release triggered by high‐frequency stimulation. These results indicate that A2A receptor activation facilitates the activity of nucleoside transporters, which have a preponderant role in modulating the extracellular adenosine levels available to activate A1 receptors.
Nanomolar concentrations of kynurenic acid reduce extracellular dopamine levels in the striatum
Authors: Rassoulpour Arash , Wu Hui‐Qiu , Ferrė Sergi , Schwarcz Robert
Published: April 2005

Precise regulation of dopaminergic activity is of obvious importance for the physiology and pathology of basal ganglia. We report here that nanomolar concentrations of the astrocyte‐derived neuroinhibitory metabolite kynurenic acid (KYNA) potently reduce the extracellular levels of striatal dopamine in unanesthetized rats in vivo. This effect, which is initiated by the KYNA‐induced blockade of α7 nicotinic acetylcholine receptors, highlights the functional relevance of glia–neuron interactions in the striatum and indicates that even modest increases in the brain levels of endogenous KYNA are capable of interfering with dopaminergic neurotransmission.
Adjunctive effect of a polylactide/polyglycolide copolymer in the treatment of deep periodontal intra‐osseous defects: a randomized clinical trial
Authors: Minenna Luigi , Herrero Federico , Sanz Mariano , Trombelli Leonardo
Published: April 2005

Aim: The aim of this study was to evaluate the clinical outcome of re‐constructive surgery in human deep intra‐osseous defects with the use of a polylactide/polyglycolide (PLA/PGA) copolymer graft in conjunction with an open flap debridement (OFD) procedure (test group) as compared with OFD procedure alone (control group).

Materials and Methods: Thirty‐two patients, each contributing one defect, were selected and completed the 12‐month follow‐up period. Sixteen patients (eight males, mean age: 49.9 years) received the test treatment, 16 patients (nine males, mean age: 42.8 years) received the control treatment. Clinical recordings, assessed at baseline, 6 and 12 months post‐surgery, included defect‐specific plaque score, defect‐specific bleeding score, probing depth (PD), clinical attachment level (CAL), and recession depth. Surgical procedure aimed to preserve supra‐crestal soft tissues at defect site in order to ensure primary closure was used in all cases.

Results: Test and control treatment produced a significant CAL decrease and PD reduction at both 6 and 12 months with respect to baseline value (p<0.000). At 6 months CAL was significantly greater in test compared with control group (p=0.019). Twelve‐month CAL gain was 3.6±1.5 and 3.4±1.4 mm for the test and control group, respectively. At 12 months no significant differences in any of the clinical parameters were observed between groups.

Conclusion: The results indicate that OFD with and without PLA/PGA graft provide clinically and statistically significant improvements in PD and CAL measurements. However, the additional use of PLA/PGA did not provide an additional benefit in terms of CAL gain and PD reduction compared with OFD procedure.
Interleukin‐1 levels in gingival crevicular fluid adjacent to restorations of calcium aluminate cement and resin composite
Authors: Konradsson Katarina , Van Dijken Jan W. V.
Published: April 2005

Objectives: The aim of this clinical study was to intra‐individually compare Class V restorations of a calcium aluminate cement (CAC), resin composite and enamel with respect to the adjacent levels of interleukin (IL)‐1α, IL‐1β and IL‐1 receptor antagonist (IL‐1ra) in gingival crevicular fluid (GCF). The hypothesis was that there are higher IL‐1 levels adjacent to resin composite, compared with CAC and enamel.

Materials and methods: In 15 subjects, at least one set of two Class V restorations with subgingival margins, one CAC and one universal hybrid resin composite, and one control surface of enamel were included. In a cross‐sectional study and on days 0, 3 and 7 of an experimental gingivitis study, GCFs were collected with Periopaper for 30 s. The GCF concentrations of IL‐1α, IL‐1β and IL‐1ra were quantified with enzyme linked immunosorbent assays.

Results: Neither the cross‐sectional study nor the experimental gingivitis study showed any significant differences in the levels of IL‐1α, IL‐1β and IL‐1ra between CAC, resin composite and enamel sites (p>0.05). In the cross‐sectional study, low IL‐1 concentrations were observed. The IL‐1 levels increased significantly during the experimental gingivitis.

Conclusion: Regardless of CAC or resin composite, the restorations per se did not affect the GCF levels of IL‐1 and IL‐1ra, neither at healthy gingiva, nor at initiation of plaque‐related gingival inflammation.
Clinical and radiographic performance of delayed‐immediate single‐tooth implant placement associated with peri‐implant bone defects. A 2‐year prospective, controlled, randomized follow‐up report
Authors: Schropp Lars , Kostopoulos Lambros , Wenzel Ann , Isidor Flemming
Published: April 2005

Objectives: The aim of the present study was to compare the delayed‐immediate (Im) and the delayed (De) protocols for placement of single‐tooth implants.

Material and methods: After allocation to the Im and De groups by random, 46 patients were treated with a single‐tooth implant with acid etched surfaces (Osseotite®) in the anterior or pre‐molar region of the maxilla or the mandible on average 10 days (Im) or 3 months (De) following tooth extraction, respectively. Forty‐one patients attended a follow‐up visit 2 years after implant placement corresponding to 1½ years of loading of the implant restorations. Peri‐implant and prosthetic parameters were evaluated clinically and marginal bone levels measured on radiographs.

Results: Three implants were lost, all before mounting of the crown. None of the implant restorations had failed after 1½ years of function. Probing pocket depths were reduced by up to 1.4 mm on average from the time of loading to the 2‐year follow‐up and at that time, no significant difference between the Im and De groups was found (4.2 versus 4.1 mm). A statistically significant radiographic marginal bone loss had occurred in the Im group (mean=0.8 mm) as well as in the De group (mean=0.7 mm) in the follow‐up period. However, a mean marginal bone level of approx. 1.5 mm in both groups measured from the implant–abutment junction was found to be acceptable. It was demonstrated that probing pocket depths and marginal bone levels after 1½ years of loading of the implant‐retained crowns were not influenced by the presence of peri‐implant bone defects immediately after implant placement. Furthermore, no severe prosthodontic complications, such as screw loosening or porcelain fractures, arose in this study material.

Conclusion: High success rates of single‐tooth implants after 1½ years of function were achieved using the delayed‐immediate and delayed implant placement techniques.
Coronally positioned flap procedures with or without a biodegradable membrane in the treatment of human gingival recession. A 6‐year follow‐up study
Authors: Leknes Knut N. , Amarante Evandro S. , Price Daniel E. , Bøe Olav E. , Skavland Ragnfrid J. , Lie Tryggve
Published: April 2005

Background: Short‐term data have indicated that treatment of gingival recession type defects by coronally positioned flap procedures with or without biodegradable membranes may result in similar treatment outcome. The aim of this study was to compare 12‐month and 6‐year follow‐up results for these two treatment approaches.

Methods: Twenty patients with buccal bilateral Miller Class I or Class II gingival recession defects in cuspids or bicuspids were treated randomly by coronally positioned flap alone (20 sites) or in combination with a biodegradable membrane (20 sites). Clinical measurements at baseline, 6, 12 months and 6 years included apical extent of gingival recession, width of the defect at the cemento‐enamel junction (CEJ), width of keratinized tissue, as well as attachment level and probing depth. Eleven patients were available for the 6‐year evaluation.

Results: At 12 months (20 sites), both treatments resulted in significant gain of root coverage (p<0.001), stable probing depth, and increased attachment level (p<0.001). The 6‐year evaluation (11 sites) showed a significant gain of root coverage for the non‐membrane group only (p<0.05). No significant between‐group differences were detected for any other treatment variable regardless of smoking status (p>0.05). Compared with baseline, the 6‐year results showed that seven membrane sites gained root coverage, three were unchanged and one lost root coverage. For the 11 non‐membrane sites, eight gained root coverage, and three were unchanged. The five membrane and the 10 non‐membrane sites exhibiting complete root coverage at 6 months were reduced to two and one, respectively, at the 6‐year evaluation.

Conclusions: The coronally positioned flap procedure offers a simple and reliable treatment alternative as a root coverage procedure in Class I and Class II recession type defects. Placement of a biodegradable membrane underneath the flap does not seem to improve neither the short‐ nor the long‐term results. Long‐term outcome stability seems to be critically dependent on a continuous follow‐up program with re‐instruction in non‐traumatic brushing habits.
COMPARISON OF DISCRIMINATION ABILITY BETWEEN A PANEL OF BLIND ASSESSORS AND A PANEL OF SIGHTED ASSESSORS
Authors: MUCCI ANDREA , GARITTA LORENA , HOUGH GUILLERMO , SAMPAYO SOLEDAD
Published: April 2005

The objective of this work was to compare a panel of blind assessors with one of sighted assessors in the discrimination of food products. Each panel had 20 screened and trained assessors. Five commercial food products were used: crackers, liver paste, powdered orange juice mix, Reggiano cheese and yogurt. Slight flavor and/or texture modifications were introduced for adequate discrimination difficulty. Each pair of products was tested by both panels using the triangle test and a scaled difference from control test. Numbers of correct answers for the triangle test were similar for both panels. There were minor differences between the panels in the difference from control test, due to the sighted panel having more training in the use of the scale. Overall the panels of trained blind and sighted assessors were equivalent in their performance.
AN EFFECTIVE WAY TO MINIMIZE DRIFTING AND MONITOR THE PERFORMANCE OF A SENSORY PANEL DURING LONG‐TERM PROJECTS – A CASE STUDY FROM A PROJECT ON HERRING QUALITY
Authors: NIELSEN DURITA , HYLDIG GRETHE , SØRENSEN RIE
Published: April 2005

A quick and easy way to monitor the performance of individual sensory assessors during long‐term fishery projects was presented. By serving the same product as a reference before each session, assessors could easily recapitulate the descriptors and recalibrate their evaluations to the same scale. No drifting was found during an evaluation period of 19 months, and this was a result of the continuous use of the reference. Serving the reference as an unknown sample made it possible to monitor the performance of the panel. Multivariate data analytical techniques allowed for quick calculations, and results were easily interpreted with the visual layout. Assessors differing from the rest of the panel could be quickly identified as well as the descriptors involved in the deviations. Three assessors were found to use different parts of the scale than the main panel, and one assessor evaluated one descriptor differently than the average panel. After correction for level effect, no difference existed between assessors.
THE CONSUMER SENSORY PERCEPTION OF PASSION‐FRUIT JUICE USING FREE‐CHOICE PROFILING
Authors: DELIZA ROSIRES , MacFIE HAL , HEDDERLEY DUNCAN
Published: April 2005

Free‐choice profiling (FCP) was carried out in order to investigate how naive consumers (who had never tried the product before) described and perceived passion‐fruit juice. This method allows participants to use their own attributes to describe and quantify food products and beverages. The study used four different samples of passion‐fruit juice, analyzed by 10 consumers in three replicates. The data were analyzed by using generalized Procrustes analysis. The first and second dimension accounted for 78.7% of the variance. The product consensus configuration revealed that assessors were able to reproduce samples’ description, and also to differentiate samples. Free‐choice profiling is a useful method for describing consumer perception of passion‐fruit juice.
RECOGNIZING MACROECONOMIC FLUCTUATIONS IN VALUE BASED MANAGEMENT
Authors: Oxelheim Lars , Wihlborg Clas
Published: April 2005

Value Based Management (VBM) has become a common tool for evaluating corporate strategies and projects from the perspective of shareholder value maximization, and can be an important input for corporate compensation systems. But traditional VBM frameworks make no systematic effort to distinguish between changes in performance attributable to macroeconomic fluctuations beyond management's control and changes in performance that reflect the intrinsic competitive position of the firm.

The authors have developed an approach for “filtering out” the impact of macroeconomic fluctuations on cash flows for purposes of performance evaluation. Such fluctuations are captured by changes in exchange rates, interest rates, and aggregate price levels (both domestically and abroad) that are significantly correlated with a particular company's cash flows. The authors also provide a method for distinguishing between expected and unanticipated cash flow effects of macro events and recommend insulating managers' performance only from the changes they cannot anticipate and manage. In applying the framework to Electrolux, a Swedish multinational, the authors show that unanticipated changes in the krona/pound exchange rate and various interest rates contribute significantly to the variability of the firm's cash flows; and with the help of the sensitivity coefficients used to measure such exposures, they calculate measures of “intrinsic” cash flow that are purged of such macro effects.
Measurement of the radiation from thermal and nonthermal radio sources
Authors: Pratap Preethi , McIntosh Gordon
Published: April 2005

The widespread use of the internet has enabled complex instrumentation to be available remotely and made it possible for students to use facilities to which they might otherwise not have access. Internet access to radio astronomical observatories, including the 37 m radio telescope at the Massachusetts Institute of Technology Haystack Observatory, has opened up new possibilities for undergraduate laboratory activities and research. This capability allows undergraduates to acquire and analyze radio astronomical data and investigate astrophysical systems that cannot be investigated using optical telescopes. We describe a radio astronomical activity using the spectral index to investigate the difference between thermal and nonthermal radiation and the sources that emit these forms of radiation.