bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Precursors and Dopants on the Synthesis and Grain Growth of Calcium Hexaluminate
Authors: Cinibulk Michael K.
Published: February 2008

A variety of colloidal and polymeric sols, some doped with transition‐metal oxides, were investigated as potential precursors to calcium hexaluminate (CaAl12O19) in an attempt to enhance reactivity and lower the formation and texturing temperatures of phase‐pure powders and films. One undoped polymeric sol was found to yield CaAl12O19, free of any intermediate phases, at temperatures as low as 1300°C in 1 h. Doping the same mixed‐metal, citrate‐based precursor with a variety of transition‐metal cations was found either to enhance the γ‐ →α‐Al2O3 phase transformation or to enhance the formation of CaAl12O19. Incorporation of MnO, Fe2O3, CoO, NiO, CuO, ZnO, or SiO2 into the citrate precursor resulted in significant hexaluminate formation within 1 h at 1100°C, compared with negligible formation using the undoped precursor. Fe2O3‐doped precursors gave the highest hexaluminate yields at 1100°C. Phase‐pure hibonite was obtained at temperatures as low as 1000°C with 25 at.% Fe substituting for Al in the hexaluminate structure. Textured CaAl11.5Fe0.5O19 films with (0001) planes parallel to the substrate surface were obtained on YAG substrates in 1 h at 1200°C. In comparison, undoped citrate‐derived films first textured at 1300°C. Enhanced CaAl12O19 formation was attributed to rapid reaction of the constituents, due to the uniform dispersion of cations on an atomistic scale throughout the citrate‐based precursor, prior to completion of the γ‐ →α‐Al2O3 phase transformation. Solid‐solution dopants were believed to further enhance reactivity and grain growth by increasing diffusive mass transport.
Citrate Route to Sn‐Doped BaTi4O9 with Microwave Dielectric Properties
Authors: Choy Jin‐Ho , Han Yang‐Su , Hwang Sung‐Ho , Byeon Song‐Ho , Demazeau Gerard
Published: February 2008

Highly reactive and nanometer‐sized (30–50 nm) Sn‐doped BaTi4O9 (BaTi4‐xSnxO9; x = 0.0–0.03) powders have been prepared by the citrate‐precursor method. The effect of Sn substitution on the crystallization and microwave dielectric properties has also been investigated on the basis of microstructure and crystal structure. Addition of a small amount of SnO2 resulted in a lowering of the sintering temperature of BaTi4O9, and at 1250–1300°C for 2–5 h, dense compounds with a theoretical density up to 99% could be obtained. The Sn‐doped BaTi4O9 materials were found to have excellent microwave dielectric properties with epsilonr = 34–37, Q = 8300–8900 at 11 GHz and tauf = 3.6–16.1 ppm/°C.
Processing, Microstructures, and Properties of Molybdenum Aluminosilicide
Authors: Fu Ming , Sekhar Jainagesh A.
Published: February 2008

A ternary intermetallic compound‐molybdenum aluminosilicide, Mo(Si0.8,Al0.2)2‐was synthesized via micropyretic synthesis. The reaction constituents were elemental molybdenum, silicon, and aluminum powders in an atomic mixture of Mo + 1.6Si + 0.4Al. With the appropriate processing parameters, a highly dense product (up to 94% theoretical density) was obtained in a short time without applying external pressure. The synthesized product had a uniform microstructure, with a grain size of ∼16 μm. X‐ray diffractometry and energy‐dispersive spectroscopy confirmed the formation of Mo(Si0.8,Al0.2)2. In addition, small amounts of secondary phases (Mo5Si3 and Al2O3) were also identified in the product. The synthesized Mo(Si0.8,Al0.2)2 was then subjected to various property measurements, including elastic moduli, Vickers hardness, indentation fracture toughness, and oxidation resistance. The measured property data, whenever possible, were compared to the corresponding values for MoSi2.
Observation of Subcritical Spall Propagation of a Thermal Barrier Coating
Authors: Sergo Valter , Clarke David R.
Published: February 2008

Observations are reported of the room‐temperature propagation of a spalling failure mode of a thermal barrier coating (TBC) from its bond coat after oxidation. The coating is a Y2O3‐stabilized ZrO2 coating formed by electron‐beam deposition on a Ni‐Co‐Cr‐Al‐Y bond coat. The spall shape evolution and stress redistribution as the spall propagates are reported. The failure propagates primarily as an interface crack between the bond coat and the thermally grown aluminum oxide (TGO) formed on the underside of the TBC during oxidation. The observations are consistent with subcritical propagation of an interface crack between the TGO and bond coat assisted by the presence of moisture. An estimate of 9 J/m2 is made of the fracture resistance in air of the interface.
Solid‐State Phase Relationships in the Calcia‐Titania‐Zirconia System at 1200°C
Authors: Swenson Douglas , Nieh Tai‐Gang , Fournelle John H.
Published: February 2008

Phase relationships were investigated in the CaO–TiO2–ZrO2 system at 1200°C for compositions containing <50 mol% CaO using X‐ray diffraction and electron probe microanalysis. The existence of two previously reported ternary phases, zirconolite (CaZrTi2O7) and calzirtite (Ca2Zr5Ti2O16), was confirmed. Each of these phases exhibited a significant range of homogeneity between TiO2 and ZrO2, while maintaining a nearly constant concentration of CaO. The ternary solubilities of the constituent binary phases were found to be small (typically <1 mol%), with the exceptions of the perovskites (CaTiO3 and CaZrO3). These latter phases displayed mutual solubilities of at least 22 mol% but exhibited significant variations in composition from grain to grain. Thermodynamic equilibrium was clearly not established in several samples, although most of the phase relationship information obtained was self‐consistent.
Formation of Tough Composite Joints
Authors: Brun Milivoj K.
Published: February 2008

Joints that exhibited tough fracture behavior were formed in a Si/SiC matrix reinforced with Textron SCS‐6 fibers with either boron nitride or silicon nitride fiber coatings. Lapped joints (joints with overlapping ‘fingers’) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure were proposed. Joints with a simple overlap geometry (only a few fingers) had to be very long in order to prevent brittle failure. Joints with an optimized stepped sawtooth geometry produced composite‐like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength, by changing the fiber coating, significantly increased matrix cracking and ultimate strength of the joints. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints should permit building of structures containing joints with only a minor reduction of design stresses.
Characterization of Nanoscale Titanium Nitride Dispersions by Small‐Angle Neutron Scattering
Authors: Wagner Joachim , Janβen Stefan , Rupp Roman , May Roland , Hempelmann Rolf
Published: February 2008

Suspensions of nanoscale titanium nitride (TiN) with a high solids content can be prepared by using guanidino propionic acid (GPA) as a stabilizing agent. The steric effect of an organic shell with polar groups on the surface of TiN spheres has been suggested in the literature as being a reason for the colloidal stability. To verify this hypothesis experimentally, we have performed small‐angle neutron scattering (SANS) on this system; there is no evidence of an organic shell. Even at higher concentrations, in accordance with the Percus‐Yevick theory, we could not observe any significant interparticular ordering. A plausible explanation for the stabilization of TiN suspensions is the buffer action of the amino acid GPA.
Fatigue Behavior of PZT‐Based Nanocomposites with Fine Platinum Particles
Authors: Hwang Hae Jin , Tajima Ken‐ichi , Sando Mutsuo , Toriyama Motohiro , Niihara Koichi
Published: February 2008

Nanocomposites of lead zirconate titanate (Pb(Zrx,Ti1−x)O3, PZT) with secondary‐phase dispersoids of metallic platinum were fabricated. Fatigue (crack‐growth) behavior of the unpoled PZT/platinum nanocomposite that contained precracks produced by a Vickers diamond indenter under electrical cyclic loading was investigated. The crack growth was monitored via optical microscopy and was dependent on the number of cycles to which the sample was subjected. The growth of the indentation crack was significantly reduced in the PZT/platinum nanocomposite.
Effects of increased temperature and nutrient enrichment on the stoichiometry of primary producers and consumers in temperate shallow lakes
Authors: VENTURA M. , LIBORIUSSEN L. , LAURIDSEN T. , SØNDERGAARD M. , SØNDERGAARD M. , JEPPESEN E.
Published: February 2008

1. We studied the effects of increased water temperatures (0–4.5 °C) and nutrient enrichment on the stoichiometric composition of different primary producers (macrophytes, epiphytes, seston and sediment biofilm) and invertebrate consumers in 24 mesocosm ecosystems created to mimic shallow pond environments. The nutrient ratios of primary producers were used as indicative of relative nitrogen (N) or phosphorus (P) limitation. We further used carbon stable isotopic composition (δ13C) of the different primary producers to elucidate differences in the degree of CO2 limitation.

2. Epiphytes were the only primary producer with significantly higher δ13C in the enriched mesocosms. No temperature effects were observed in δ13C composition of any primary producer. Independently of the treatment effects, the four primary producers had different δ13C signatures indicative of differences in CO2 limitation. Seston had signatures indicating negligible or low CO2 limitation, followed by epiphytes and sediment biofilm, with moderate CO2 limitation, while macrophytes showed the strongest CO2 limitation. CO2 together with biomass of epiphytes were the key variables explaining between 50 and 70% of the variability in δ13C of the different primary producers, suggesting that epiphytes play an important role in carbon flow of temperate shallow lakes.

3. The ratio of carbon to chlorophyll a decreased with increasing temperature and enrichment in both epiphytes and seston. The effects of temperature were mainly attributed to changes in algal Chl a content, while the decrease with enrichment was probably a result of a higher proportion of algae in the seston and epiphytes.

4. Macrophytes, epiphytes and seston decreased their C : N with enrichment, probably as an adaptation to the different N availability levels. The C : N of epiphytes and Elodea canadensis decreased with increasing temperature in the control mesocosms. Sediment biofilm was the only primary producer with lower C : P and N : P with enrichment, probably as a result of higher P accumulation in the sediment.

5. Independently of nutrient level and increased temperature effects the four primary producers had significantly different stoichiometric compositions. Macrophytes had higher C : N and C : P and, together with epiphytes, also the highest N : P. Seston had no N or P limitation, while macrophytes and epiphytes may have been P limited in a few mesocosms. Sediment biofilm indicated strong N deficiency.

6. Consumers had strongly homeostatic stoichiometric compositions in comparison to primary producers, with weak or no significant treatment effects in any of the groups (insects, leeches, molluscs and crustaceans). Among consumers, predators had significantly higher N content and lower C : N than grazers.
Canal preparation using only one Ni‐Ti rotary instrument: preliminary observations
Authors: Yared G.
Published: February 2008

Aim  To describe a novel canal preparation technique using only one Ni‐Ti rotary instrument.

Summary  In this novel technique, the canal is negotiated to the working length with a size 08 hand file. Then, the canal preparation is completed with an F2 ProTaper instrument used in a reciprocating movement. In larger canals, the use of additional hand files may be required to complete the apical enlargement.

Key learning points 

A novel canal preparation technique is introduced using only one Ni‐Ti rotary instrument in a reciprocating movement.

The advantages of the technique include a reduced number of instruments, lower cost, a reduced instrument fatigue and the elimination of possible prion cross‐contamination associated with the single use of endodontic instruments.
Degradation of trans‐polyisoprene after root filling with thermoplasticized techniques
Authors: Maniglia‐Ferreira C. , Bönecker G. , Silva J. B. A. , De Paula R. C. M. , Feitosa J. P. A. , Souza‐Filho F. J.
Published: February 2008

Aim  To evaluate ex vivo degradation of gutta‐percha following six thermoplastic obturation techniques.

Methodology  Ninety human‐extracted mandibular premolars were selected and divided randomly into nine groups for filling. Group 1: thermomechanical compaction for 3 s with Konne gutta‐percha points (Konne Ind. e Com. de Mat. Odontol., Belo Horizonte, MG, Brazil); Group 2: thermomechanical compaction for 3 s with Dentsply TP gutta‐percha points (Dentsply Indústria e Comércio Ltda, Petrópolis, R.J. Brazil); Group 3: thermomechanical compaction for 10 s with Konne; Group 4: thermomechanical compaction for 10 s with Dentsply TP; Group 5: warm vertical condensation using System B (EIE/Analytic, Richmond, WA, USA) with Konne; Group 6: warm vertical condensation using System B with Dentsply TP; Group 7: vertical condensation with Konne; Group 8: vertical condensation with Dentsply TP; Group 9: Microseal cone (Analytic Endodontics, Glendora, CA, USA). A further four groups were assessed without using teeth, Group 10: Microseal microflow (Analytic Endodontics); Group 11: Obtura (Obtura Corporation, Penton, MO, USA); Group 12: Obtura flow (Obtura Corporation); Group 13: Thermafil (Dentsply Maillefer, Tulsa, OK, USA). The filling material was removed from the root canal and trans‐1,4‐polyisoprene isolated by solubilization of the root filling remnants in chloroform followed by filtration and centrifugation. By gel permeation chromatography and infrared spectroscopy, the occurrence and degree of degradation were assessed. The results were analysed statistically using the Kruskal–Wallis test. With differential scanning calorimetry, the thermal behaviour of the gutta‐percha was determined.

Results  A significant decrease in polymer molar mass and the production of carboxyl and hydroxyl groups in the polymer were observed with thermomechanical compaction used for 10 s and vertical condensation filling techniques (P = 0.0001 and P = 0.0005, respectively). Other techniques caused no polymer degradation.

Conclusion  Polyisoprene degrades with high temperature. Thermomechanical compaction for 10 s and vertical condensation were associated with the greatest degradative process.
Replantation of three avulsed permanent incisors with complicated crown fractures
Authors: Walter C. , Krastl G. , Izquierdo A. , Hecker H. , Weiger R.
Published: February 2008

Aim  To report a rare case of multiple avulsions of permanent teeth associated with complicated crown fractures.

Summary  The case describes a 3‐year follow‐up of the treatment of three avulsed maxillary incisors with complicated crown fractures. The teeth were replanted after an extra‐oral time of 90 min (extra‐oral dry time 6 min). After root canal treatment, the fractured maxillary incisors were restored with a layered hybrid composite material to re‐establish aesthetics and function. Follow‐up visits showed signs of replacement resorption affecting the maxillary central incisors but only minor signs of root resorption on the maxillary right lateral incisor. These findings were supported by digital volume tomography, which was performed 18 and 36 months post‐trauma in order to assess extent, severity and progression of root resorption more accurately.

Key learning points 

Healing of avulsed teeth depends on the degree of periodontal ligament (PDL) damage.

Digital volume tomography might improve diagnostics of root resorption.
Influence of surface remodelling using burs on the macro and micro surface morphology of anatomically formed fibre posts
Authors: Plotino G. , Grande N. M. , Pameijer C. H. , Somma F.
Published: February 2008

Aim  To evaluate the effect of modifying preformed fibre‐reinforced composite (FRC) endodontic posts on their surface morphology and to determine how this procedure affects the integrity of the posts.

Summary  Surfaces of 10 preformed glass‐fibre posts (group 1) and carbon‐fibre posts (group 2) were compared with those of individually formed glass‐fibre posts (group 3). Ten FRC posts were modelled in order to give them a shape as close as possible to the anatomy of oval root canals. Starting from a preformed cylindrical fibre post 2.5 mm in diameter, it was modelled in such a way as to passively occupy the entire post‐space length, using a cast previously created as a guide. Microscopic analyses (optical stereomicroscope and scanning electron microscope) of the post surfaces revealed similar features in all three groups. All posts had regular surfaces after cutting with a diamond bur. Smear layer mainly attributable to the cutting procedures covered the cut surface of some specimens. In conclusion, modulation of a fibre post using a diamond‐coated bur did not show a loss of integrity of the post.

Key learning points 

Because of the importance of micromechanical retention, the surface integrity of fibre posts may be important for adhesion between post and composite resin.

Modification of a fibre post using a diamond‐coated bur did not damage the surface integrity of the posts.

Fibre posts can be ground to a different shape without losing their surface integrity, resulting in posts with a surface that is not visibly different from unmodified commercially available fibre posts.
The influence of grazing intensity and landscape composition on the diversity and abundance of flower‐visiting insects
Authors: Sjödin N. Erik , Bengtsson Jan , Ekbom Barbara
Published: February 2008

The loss of semi‐natural grasslands in agro‐ecosystems has increased the importance of adequate management of remaining grasslands. Recommendations for intensive grazing have been debated because the effects of different management practices may differ between taxa and species. The increased fragmentation of grasslands suggests that the influence of management practices should be studied in a landscape context.

We studied four groups of flower visitors, many of which are pollinators, bees (Apoidea), butterflies (Lepidoptera), hoverflies (Syrphidae) and beetles (Coleoptera), in semi‐natural grasslands managed at three intensity levels in eight areas in central Sweden. Local characteristics of the grasslands were recorded and landscape diversity was quantified. Vegetation height was correlated with grazing intensity: intensive grazing with the shortest vegetation and abandoned grassland with the tallest.

The insect groups responded differently to grazing intensity. Species richness and abundance differed between management regimes for beetles and hoverflies but not for bees and butterflies.

The effects of local habitat and landscape composition on species richness, abundance and composition differed between groups. Bee diversity responded to both local and landscape factors. Butterflies were mainly affected by local vegetation height and linear elements in the landscape. More species of hoverflies were recorded in tall vegetation and in landscapes with high forest cover. Beetles responded only to local environment characteristics.

Synthesis and applications. We demonstrate the importance of studying different insect groups simultaneously when evaluating habitat and landscape qualities for diversity. The results suggest that planning for conservation of biodiversity at landscape scales may be better than implementing grazing guidelines for individual grasslands. Grazing intensity should vary within or between landscapes to preserve pollinator diversity. Conservation management to encourage flower visitors cannot be generalized to include all groups simultaneously.
Bayesian modelling procedures for the evaluation of changes in wildlife habitat suitability: a case study of roe deer in the Italian Alps
Authors: Morgia Valentina La , Bona Francesca , Badino Guido
Published: February 2008

Combining species protection with land management is a central concern for nature conservation but requires a collaborative, problem‐solving approach. Existing procedures do not guarantee the participation of stakeholders in the decision‐making process and, thus, do not necessarily support the development of acceptable management strategies. An analytical framework is required to assess the consequences of human land use for wildlife habitats, incorporating a quantitative structure for including stakeholder opinions. We provide such a framework.

As an example, we used the procedure to evaluate the consequences of different building scenarios for the Turin 2006 Winter Olympic Games on potential roe deer Capreolus capreolus habitats. The analysis involved four steps: (i) three Bayesian models were developed to assess the suitability of six study areas for roe deer; (ii) the outcome of the models was converted into a habitat suitability index (HSI) for each study area; (iii) for each area, the building scenario chosen by the Olympic Games organizers was compared with alternative scenarios by means of HSI values; (iv) an HSI value was chosen as a benchmark to evaluate the ecological consequences of landscape changes.

The building projects chosen by the Olympic Games organizers caused changes in HSI values in each study area, especially at one site. In three of the six study areas, the chosen projects minimized the loss of suitable roe deer habitat, while in the remaining areas the alternative building locations could have reduced the negative consequences of human activities.

Synthesis and applications. A habitat suitablility index calculated with our procedure can be used to (i) compare different hypothetical land‐use scenarios and make decisions about the location of human infrastructures to minimize habitat loss; and (ii) assess the consequences of human activities in relation to an ecological benchmark. The Bayesian approach provides a way to involve local stakeholders in the decision‐making process, and thus is a useful tool for discussion of land‐use policies. Our procedure could be applied to rare and common species and to assessing the consequences of all human activities involving reductions in natural habitat.
Direct visualization of the dynamics of membrane‐anchor proteins in living cells
Authors: WANG C. , FU G. , WANG J. , WANG G. , CHENG Y. , XU Z.‐Z.
Published: February 2008

Dynamic properties of proteins have crucial roles in understanding protein function and molecular mechanism within cells. In this paper, we combined total internal reflection fluorescence microscopy with oblique illumination fluorescence microscopy to observe directly the movement and localization of membrane‐anchored green fluorescence proteins in living cells. Total internal reflect illumination allowed the observation of proteins in the cell membrane of living cells since the penetrate depth could be adjusted to about 80 nm, and oblique illumination allowed the observation of proteins both in the cytoplasm and apical membrane, which made this combination a promising tool to investigate the dynamics of proteins through the whole cell. Not only individual protein molecule tracks have been analyzed quantitatively but also cumulative probability distribution function analysis of ensemble trajectories has been done to reveal the mobility of proteins. Finally, single particle tracking has acted as a compensation for single molecule tracking. All the results exhibited green fluorescence protein dynamics within cytoplasm, on the membrane and from cytoplasm to plasma membrane.
New controlled environment vitrification system for preparing wet samples for cryo‐SEM
Authors: GE H. , SUSZYNSKI W. J. , DAVIS H. T. , SCRIVEN L. E.
Published: February 2008

A new controlled environment vitrification system (CEVS) has been designed and constructed to facilitate examination by cryogenic scanning electron microscopy (Cryo‐SEM) of initial suspension state and of microstructure development in latex, latex–composite and other coatings while they still contain solvent. The new system has a main chamber with provisions for coating as well as drying, and for well‐controlled plunging into cryogen. An added subsidiary chamber holds samples for drying or annealing over minutes to days before they are returned to the main chamber and plunged from it. In the main chamber, samples are blade‐coated on 5 × 7 mm pieces of silicon wafer and held at selected temperature and humidity for successively longer times, either there or after transfer along a rail into the subsidiary chamber. They are then placed in the sample holder mounted on the plunge rod, so as to permit adjustment of the sample's attitude when it plunges, at controlled speed, into liquid ethane at its freezing point, to a chosen depth, in order to solidify the sample without significant shear or freezing artifacts. The entries of plunging samples and related sample holders into liquid ethane were recorded with a high‐speed, high‐resolution Photron digital camera. The data were interpreted with a new hypothesis about the width of the band of extremely rapid cooling by deeply subcooled nucleate boiling below the line of entry. Complementary cryo‐SEM images revealed that the freezing rate and surface shearing of a sample need to be balanced by adjusting the plunging attitude.
Scanning‐less wide‐field single‐photon counting device for fluorescence intensity, lifetime and time‐resolved anisotropy imaging microscopy
Authors: SPITZ J.‐A. , YASUKUNI R. , SANDEAU N. , TAKANO M. , VACHON J.‐J. , MEALLET‐RENAULT R. , PANSU R.B.
Published: February 2008

A scanning‐less single‐photon counting system for FLIM and fluorescence anisotropy wide‐field imaging is described and characterized in this paper. The two polarizations of the fluorescence are divided by a Glan prism and acquired at the same time by the QA detector. Fluorescence decay profiles can be reconstructed for any desired area up to each pixel and used to calculate time‐resolved fluorescence anisotropy decays.
Measuring the velocity of fluorescently labelled red blood cells with a keyhole tracking algorithm
Authors: REYES‐ALDASORO C. C. , AKERMAN S. , TOZER G. M.
Published: February 2008

In this paper we propose a tracking algorithm to measure the velocity of fluorescently labelled red blood cells travelling through microvessels of tumours, growing in dorsal skin flap window chambers, implanted on mice. Preprocessing removed noise and artefacts from the images and then segmented cells from background. The tracking algorithm is based on a ‘keyhole’ model that describes the probable movement of a segmented cell between contiguous frames of a video sequence. When a history of cell movement exists, past, present and a predicted landing position of the cells will define two regions of probability that resemble the shape of a keyhole. This keyhole model was used to determine if cells in contiguous frames should be linked to form tracks and also as a postprocessing tool to join split tracks and discard links that could have been formed due to noise or uncertainty. When there was no history, a circular region around the centroid of the parent cell was used as a region of probability. Outliers were removed based on the distribution of the average velocities of the tracks. Since the position and time of each cell is recorded, a wealth of statistical measures can be obtained from the tracks. The algorithm was tested on two sets of experiments. First, the vasculatures of eight tumours with different geometries were analyzed; average velocities ranged from 86 to 372 μm s−1, with minimum and maximum track velocities 7 and 1212 μm s−1, respectively. Second, a longitudinal study of velocities was performed after administering a vascular disrupting agent to two tumours and the time behaviour was analyzed over 24 h. In one of the tumours there is a complete shutdown of the vasculature whereas in the other there is a clear decrease of velocity at 30 min, with subsequent recovery by 6 h. The tracking algorithm enabled the simultaneous measurement of red blood cell velocity in multiple vessels within an intravital video sequence, enabling analysis of heterogeneity of flow and response to treatment in mouse models of cancer.
Analysis of photopolymerized acrylic films by AFM in pulsed force mode
Authors: JRADI S. , SOPPERA O. , LOUGNOT D. J.
Published: February 2008

This paper highlights the potential of atomic force microscopy in the pulsed force mode to investigate the photopatterning of acrylic‐based films. The pulsed force mode is a nonresonant mode designed to allow approach curves to be recorded along the scanning path. It thereby provides the topography of the sample and a direct and simple local characterization of adhesion and stiffness. This mode can be used either for imaging or for locally probing the mechanical properties of a surface. In particular, a correlation between stiffness and conversion of the monomer was established. The close examination of the pulsed force mode signal brought accurate information on the photoinduced modification of the film. Polymer films with submicron photopatterning generated by interferometric illumination were analyzed by pulsed force mode. It was established that the gradient of mechanical properties throughout the films was strongly dependant on the irradiation conditions.
Surface plasmon‐assisted widefield non‐linear imaging of gold structures
Authors: QIAN C. , VELINOV T. S. , PITTER M. C. , SOMEKH M. G.
Published: February 2008

In this paper, we demonstrate how the confinement and enhancement of optical fields by surface plasmon resonance can allow non‐linear microscopy to be performed in a simple, cost‐effective widefield configuration, rather than the more usual laser‐scanning arrangement. We present second harmonic and two‐photon luminescence widefield images of dielectric and gold samples obtained with both prism‐based and high numerical aperture objective (‘prismless’) microscope arrangements.
Concentrated dyes as a source of two‐dimensional fluorescent field for characterization of a confocal microscope
Authors: MODEL M. A. , BLANK J. L.
Published: February 2008

The axial spread function is a useful tool for evaluation of a confocal microscope. It can be obtained experimentally by scanning a uniform fluorescent layer whose thickness is significantly below the resolution limit. Previous researchers have created thin fluorescent films by chemical synthesis. We show here that concentrated fluorescent dyes with a strong absorption at the excitation wavelength can serve as a good approximation of thin fluorescent films. The vertical intensity profiles of such dyes are symmetrical and represent the true axial resolution of a microscope. Solutions of dyes sufficiently opaque to test confocal microscopes with high‐NA objectives can be prepared from sodium fluorescein, acid fuchsin and acid blue 9 for excitation at 488 nm, 543 nm and 633 nm, respectively.
Patient ethnicity and three psychiatric intensive care units compared: the Tompkins Acute Ward Study
Authors: BOWERS L. , SIMPSON A. , NIJMAN H. , HALL C.
Published: February 2008

Psychiatric care units provide care to disturbed patients in a context of higher security and staffing levels. Although such units are numerous, few systematic comparisons have been made, and there are indications that ethnic minority groups may be over‐represented. The aim of this study was to compare the rates of adverse incidents and patterns of usage of three psychiatric intensive care units. The study used a triangulation or multi‐method design, bringing together data from official statistics, local audit and interviews conducted with staff. Intensive care patients were more likely to be young, male and suffering a psychotic disorder, as compared with general acute ward patients. Caribbean patients were twice as likely, and Asian patients half as likely, to receive intensive care (age, gender and diagnosis controlled). There were large differences in service levels, staffing, team functioning and adverse incidents between the three units. Various aspects of physical security were important in preventing absconds. More evaluative research is required in order to define effective service levels, and to explore the nature of the interaction between ethnicity and inpatient care provision during acute illness.
Increased EEG spectral power density during sleep following short‐term sleep deprivation in pigeons (Columba livia): evidence for avian sleep homeostasis
Authors: MARTINEZ‐GONZALEZ DOLORES , LESKU JOHN A. , RATTENBORG NIELS C.
Published: February 2008

Birds provide a unique opportunity to evaluate current theories for the function of sleep. Like mammalian sleep, avian sleep is composed of two states, slow‐wave sleep (SWS) and rapid eye‐movement (REM) sleep that apparently evolved independently in mammals and birds. Despite this resemblance, however, it has been unclear whether avian SWS shows a compensatory response to sleep loss (i.e., homeostatic regulation), a fundamental aspect of mammalian sleep potentially linked to the function of SWS. Here, we prevented pigeons (Columba livia) from taking their normal naps during the last 8 h of the day. Although time spent in SWS did not change significantly following short‐term sleep deprivation, electroencephalogram (EEG) slow‐wave activity (SWA; i.e., 0.78–2.34 Hz power density) during SWS increased significantly during the first 3 h of the recovery night when compared with the undisturbed night, and progressively declined thereafter in a manner comparable to that observed in similarly sleep‐deprived mammals. SWA was also elevated during REM sleep on the recovery night, a response that might reflect increased SWS pressure and the concomitant ‘spill‐over’ of SWS‐related EEG activity into short episodes of REM sleep. As in rodents, power density during SWS also increased in higher frequencies (9–25 Hz) in response to short‐term sleep deprivation. Finally, time spent in REM sleep increased following sleep deprivation. The mammalian‐like increase in EEG spectral power density across both low and high frequencies, and the increase in time spent in REM sleep following sleep deprivation suggest that some aspects of avian and mammalian sleep are regulated in a similar manner.
Treatment of chronic delta hepatitis with lamivudine vs lamivudine + interferon vs interferon
Authors: Yurdaydın C. , Bozkaya H. , Önder F. O. , Şentürk H. , Karaaslan H. , Akdoğan M. , Çetinkaya H. , Erden E. , Erkan‐Esin Ö. , Yalçın K. , Bozdayı A. M. , Schinazi R. F. , Gerin J. L. , Uzunalimoğlu Ö. , Özden A.
Published: February 2008

Summary.  Chronic delta hepatitis is the most severe form of chronic viral hepatitis for which interferon (IFN) is the only available treatment. In 39 patients (25 were treatment‐naïve, 14 had previously used IFN), efficacy of 1‐year treatment with IFN (9 MU, t.i.w.) or lamivudine (LAM; 100 mg, q.d.) alone was compared with IFN and LAM combination (2 months of LAM to be followed by combination treatment). IFN monotherapy was given only to treatment‐naïve patients. In both treatment‐naïve and previous IFN users, end of treatment virological and biochemical responses were similar with IFN–LAM combination and superior to LAM monotherapy (P < 0.05). Improvement in liver histology occurred more often with IFN ± LAM than with LAM alone (P < 0.05). In treatment‐naïve patients, combination treatment was not superior to IFN monotherapy. After treatment discontinuation, virological and biochemical response rates decreased in LAM and IFN combination and IFN monotherapy. On treatment virological response at month 6 of treatment predicted sustained virological response. The results of this study suggest that addition of LAM to IFN for the treatment of delta hepatitis is of no additional value and that both treatment modalities are superior to LAM monotherapy.
Severe weight loss in HIV / HCV‐coinfected patients treated with interferon plus ribavirin: incidence and risk factors
Authors: Bani‐Sadr F. , Lapidus N. , Melchior J.‐C. , Ravaux I. , Bensalem M. , Rosa I. , Cacoub P. , Pol S. , Perronne C. , Carrat F.
Published: February 2008

Summary. Weight loss is reported by more than 20% of hepatitis C virus (HCV)‐monoinfected patients treated with the peg‐interferon (peg‐IFN) and ribavirin combination. The aim of this study was to determine the incidence and risk factors of severe weight loss (≥10%) in human immunodeficiency virus (HIV) / HCV‐coinfected patients participating in a randomized, controlled 48‐week trial comparing peg‐IFN alpha 2b plus ribavirin with IFN alpha‐2b plus ribavirin. Univariate and multivariate analyses were used to identify links with antiretroviral treatments, anti‐HCV therapy and clinical and laboratory findings. One hundred eleven (28.9%) of 383 patients who received at least one dose of anti‐HCV treatment subsequently had severe weight loss. Among patients who took at least 80% of the planned total dose, severe weight loss occurred in 74 patients (32.7%). In multivariate analysis, age >40 years [hazard ratio (HR), 1.59; 95% CI 1.09 to 2.31;P = 0.016], body mass index (BMI) >22 (HR, 1.72; 95% CI, 1.16 to 2.55;P = 0.0069), peg‐IFN alpha‐2b (HR, 1.82; 95% CI, 1.24 to 2.69;P = 0.0022) and female sex (HR, 1.60; 95% CI, 1.05 to 2.43;P = 0.027) were associated with severe weight loss. In contrast, patients taking non‐nucleoside reverse transcriptase inhibitors (NNRTI)‐containing antiretroviral regimens were less likely to lose weight (HR, 0.62; 95% CI, 0.39 to 0.96;P = 0.034). Lipodystrophy tended to occur more frequently in patients who had severe weight loss than in the other patients (26.1%vs17.6%;P = 0.0682) and patients whose weight loss >5% persisted 24 weeks after the completion of anti‐HCV therapy (n = 58 / 111) were more likely to be receiving stavudine‐based antiretroviral therapy, suggesting that mitochondrial toxicity plays some role in weight loss. These findings show that severe weight loss is a frequent side effect of anti‐HCV therapy in HIV / HCV‐coinfected patients. The underlying mechanisms remain to be identified.
Methamphetamine enhances Hepatitis C virus replication in human hepatocytes
Authors: Ye L. , Peng J. S. , Wang X. , Wang Y. J. , Luo G. X. , Ho W. Z.
Published: February 2008

Summary.  Very little is known about the interactions between hepatitis C virus (HCV) and methamphetamine, which is a highly abused psychostimulant and a known risk factor for human immunodeficiency virus (HIV)/HCV infection. This study examined whether methamphetamine has the ability to inhibit innate immunity in the host cells, facilitating HCV replication in human hepatocytes. Methamphetamine inhibited intracellular interferon alpha expression in human hepatocytes, which was associated with the increase in HCV replication. In addition, methamphetamine also compromised the anti‐HCV effect of recombinant interferon alpha. Further investigation of mechanism(s) responsible for the methamphetamine action revealed that methamphetamine was able to inhibit the expression of the signal transducer and activator of transcription 1, a key modulator in interferon‐mediated immune and biological responses. Methamphetamine also down‐regulated the expression of interferon regulatory factor‐5, a crucial transcriptional factor that activates the interferon pathway. These in vitro findings that methamphetamine compromises interferon alpha‐mediated innate immunity against HCV infection indicate that methamphetamine may have a cofactor role in the immunopathogenesis of HCV disease.
Response rates to combination therapy for chronic HCV infection in a clinical setting and derivation of probability tables for individual patient management
Authors: Thomson B. J. , Kwong G. , Ratib S. , Sweeting M. , Ryder S. D. , De Angelis D. , Grieve R. , Irving W. L. ,   the Trent HCV Study Group
Published: February 2008

Summary.  Evidence for efficacy of established treatment guidelines for chronic hepatitis C virus (HCV) disease is based on multinational randomized controlled trials (RCTs). Strategies for managing HCV, however, require an assessment of the effectiveness of intervention in routine clinical practice. We report the outcomes of combination therapy in a large cohort of HCV‐infected individuals in the UK. A total of 347 (113 genotype 1, 234 genotype non‐1) patients were treated with pegylated interferon and ribavirin according to current guidelines. Forty‐two (37.2%) of those with genotype 1 infection and 164 (70.1%) with genotype non‐1 infection achieved sustained viral response (SVR). Thirty‐nine (11%) patients withdrew from treatment. In addition to viral genotype, factors predictive of a response to therapy were age at start of treatment and disease stage on pretreatment liver biopsy. Multivariate regression analysis demonstrated that the effects of age [odds ratio 0.5; 95% confidence interval (0.31–0.82) per 10‐year increment (P = 0.006)] were confined to genotype 1 disease. In order to further inform the management of the individual patient, a multivariate logistic model was used to predict the probability of SVR for subgroups defined by disease stage, genotype and age at commencement of therapy. This model revealed striking differences in predicted response rates between subgroups and provided a strong rationale for early treatment, particularly for those with genotype 1 disease. Our study demonstrates that results comparable with those of RCTs can be achieved in clinical practice, and suggests that prediction of response rates based on probability modelling will provide a valuable adjunct to individual patient management.
Liver transplantation in children with glycogen storage disease: Controversies and evaluation of the risk/benefit of this procedure
Authors: Davis Michael K. , Weinstein David A.
Published: February 2008

Abstract:  GSD‐I, III, and IV are congenital disorders of glycogen metabolism that are commonly associated with severe liver disease. Liver transplantation has been proposed as a therapy for these disorders. While liver transplantation corrects the primary hepatic enzyme defect, the extrahepatic manifestations of GSD often complicate post‐transplantation management. Upon review of the English‐language literature, 42 children <19 yr of age were discovered to have undergone liver transplantation for complications associated with GSD (18 patients with GSD‐Ia, six with GSD‐Ib, one with GSD‐III, 17 with GSD‐IV). An additional two children followed at our institution have undergone liver transplantation for GSD complications (one with GSD‐Ia and one with GSD‐III) and are included in this review. The risks and benefits of liver transplantation should be considered prior to performing liver transplantation in these metabolic disorders, particularly in GSD‐Ia. As liver pathology is not the major source of morbidity in GSD‐Ib and GSD‐IIIa, liver transplantation should only be performed when there is high risk for HCC or evidence of substantial cirrhosis or liver dysfunction. Liver transplantation remains the best option for treatment of GSD‐IV.
Lung transplantation and survival in children with cystic fibrosis: Solid statistics – Flawed interpretation
Authors: Sweet Stuart C. , Aurora Paul , Benden Christian , Wong Jackson Y. , Goldfarb Samuel B. , Elidemir Okan , Woo Marlyn S. , Mallory George B. ,   International Pediatric Lung Transplant Collaborative.
Published: February 2008

Abstract: In their provocative paper, “Lung transplantation and survival in children with cystic fibrosis,” Liou and colleagues state that “Prolongation of life by means of lung transplantation should not be expected in children with cystic fibrosis. A prospective, randomized trial is needed to clarify whether and when patients derive a survival and quality of life benefit from lung transplantation.” Unfortunately, that conclusion is not supportable. Liou’s dataset introduced bias against transplantation by using covariates obtained well before the time of transplant (when predicted survival was good) and having a cohort with lower than expected post‐transplant survival than reported elsewhere. The calculated hazard ratios are based on factors that may have changed between listing and transplant, and do not reflect true benefit on a patient by patient basis. The findings of the study are contrary to other studies using similar methods. Finally, recent changes in US lung transplant allocation policy may have made the study findings moot. In contrast to Liou’s suggestion to perform an ethically and logistically challenging randomized trial to verify the benefit of lung transplantation, a research agenda is recommended for pediatric lung transplantation for cystic fibrosis that focuses on developing strategies to continually reassess and maximize quality of life and survival benefit.
A prospective study of unmet activity of daily living needs in palliative care inpatients
Authors: Jeyasingam Lalitha , Agar Meera , Soares Michael , Plummer John , Currow David
Published: February 2008

Aim:  To define the unmet needs of activities of daily living as defined by patients and caregivers in a palliative care inpatient unit.

Methods:  A cross‐sectional prevalence study of a convenience cohort of a dyad of patient/caregiver. Functional status and unment needs were assessed. Agreement between respondents was analysed.

Results:  Caregivers identified significantly more unmet needs than patients (2.5 vs 2.5; p = 0.03). Areas of unmet need included mobility, leisure and bathing.

Conclusion:  Routine screening for unmet needs in function should be part of all inpatient palliative care assessments.
SEX‐DIFFERENCES IN CIRCADIAN BLOOD PRESSURE VARIATIONS IN RESPONSE TO CHRONIC ANGIOTENSIN II INFUSION IN RATS
Authors: Sampson Amanda K , Widdop Robert E , Denton Kate M
Published: February 2008

The aim of this study was to investigate the effect of chronic angiotensin II (AngII) infusion on the circadian rhythms of arterial blood pressure, heart rate (HR) and locomotor activity (ACT) in male and female rats.

Radiotelemetry probes were implanted into the aorta in male and female rats and allowed 10 days for recovery. Control levels for mean arterial pressure (MAP), HR and ACT were recorded for 3 days, then AngII (400 ng/kg per min s.c via osmotic minipump) or vehicle (saline) was infused for 10 days (n = 6 per group). Further recordings of MAP, HR and ACT were made during days 8, 9 and 10 of the infusion period.

In response to AngII infusion, night and day‐time MAP increased significantly in female (18 ± 2 mmHg; 28 ± 7 mmHg) and male (27 ± 4 mmHg; 30 ± 3 mmHg) rats, respectively. The degree of elevation in MAP in response to AngII was attenuated in the females during the night period (Psex < 0.05) but not the day (Psex = 0.2). Control night–day differences in MAP, HR and ACT averaged 7 ± 1 mmHg, 58 ± 5 b.p.m. and 30 ± 4 units in the female and 6 ± 1 mmHg, 43 ± 3 b.p.m. (Psex < 0.05) and 14 ± 2 units (Psex < 0.05) in male rats, respectively. AngII infusion disrupted MAP circadian rhythm in female (–4 ± 2 mmHg) and male rats (1 ± 2 mmHg; Ptreat < 0.01), but did not affect heart rate or locomotor activity.

In conclusion, sex differences in the circadian rhythm of heart rate and locomotor activity, but not arterial pressure exist under basal conditions. Circulating AngII modulated the circadian rhythm of MAP in female and male rats but not heart rate or locomotor activity. These findings have important implications for our understanding of circadian blood pressure rhythms in states of activation of the renin angiotensin system.