1,097 research outputs found
Crystal growth on enamel in relation to acid etching
Crystal formation may occur during etching of enamel surfaces with phosphoric acid. In this in vitro study we observed, from a morphological standpoint, some crystals left after etching, on the surfaces, using the scanning electron microscope. More often, after water-spraying, a thin generalized precipitate remains on the surface. This precipitate may be harmful for the retention of composite resins. On few specimens we obtained needle-shaped or petal-like crystals. Crystal deposits were spread evenly, on the surface, or nucleated from different points. We tempted to identify these crystal formations by X-ray diffraction and microprobe analysis. Chemical identification seems very important because calcium phosphates solubility varies. Crystal dissolution in saliva can lead to marginal leakage and impairs the quality of esthetic restorations. On the contrary insoluble crystals may ensure microscopic retentions and crystal growth is now considered as an alternative for enamel pretreatment in bracket bonding. Crystal formation, in these first experiments, is too scarse to be used for crystal bonding. But it appears that two factors may enhance the crystal number: a preliminary topical application of fluoride and adsorption of an acidic protein, on the surface, before etching. However, further investigations are still necessary.On peut observer la formation de cristaux, Ă la surface de lâĂ©mail, aprĂšs un mordançage Ă lâacide phosphorique.Dans cette Ă©tude, effectuĂ©e in vitro, nous avons observĂ©, en M.E.B., dâun point de vue strictement morphologique un certain nombre de cristallisations dĂ©posĂ©es, Ă la surface de lâĂ©mail, aprĂšs mordançage.Le plus souvent, aprĂšs rinçage, persiste en surface un fin prĂ©cipitĂ©; celui-ci est gĂ©nĂ©ralement considĂ©rĂ© comme nĂ©faste pour la bonne tenue des rĂ©sines composites. Sur quelques Ă©chantillons nous avons obtenu des cristaux en forme dâaiguilles ou de larges pĂ©tales. Ces cristaux peuvent ĂȘtre disposĂ©s au hasard ou regroupĂ©s autour dâun centre de nuclĂ©ation. Nous avons essayĂ© dâidentifier certains de ces cristaux en pratiquant une analyse en microsonde et une diffraction aux rayons X. Il paraĂźt trĂšs important de connaĂźtre la nature chimique de ces cristaux car les diffĂ©rents sels phospho-calciques ont des taux de solubilitĂ© variables. A long terme, la dissolution de ces cristaux, dans la salive peut conduire Ă la formation dâun hiatus qui risque de compromettre la qualitĂ© esthĂ©tique des restaurations. Au contraire, de telles cristallisations, si elles sâavĂ©raient insolubles pourraient constituer des microrĂ©tentions. La croissance dâune phase cristalline, Ă la surface de lâĂ©mail, Ă©tant dĂ©jĂ considĂ©rĂ©e comme une alternative valable au mordançage, en orthopĂ©die dento-faciale pour le collage des verrous. DâaprĂšs les rĂ©sultats de cette Ă©tude prĂ©liminaire il semble que la formation de cristaux soit encore trop alĂ©atoire pour favoriser la rĂ©tention des rĂ©sines. Deux facteurs semblent favoriser cette formation de cristaux: lâapplication topique prĂ©alable, sur lâĂ©mail, dâun fluorure et lâadsorption dâune protĂ©ine acide (ici, lâalbumine) avant mordançage. Il semble toutefois que ces observations doivent ĂȘtre confirmĂ©es
Comprehensive analysis of fibroblast growth factor receptor expression patterns during chick forelimb development
Specific interactions between fibroblast growth factors (Fgf1-22) and their tyrosine kinase receptors (FgfR1-4) activate different signalling pathways that are responsible for the biological processes in which Fgf signalling is implicated during embryonic development. In the chick, several Fgf ligands (Fgf2, 4,8, 9, 10, 12, 13 and 18) and the four FgfRs (FgfR 1, 2, 3 and 4) have been reported to be expressed in the developing limb. The precise spatial and temporal expression of these transcripts is important to guide the limb bud to develop into a wing/leg. In this paper, we present a detailed and systematic analysis of the expression patterns of FgfR1, 2, 3 and 4 throughout chick wing development, by in situ hybridisation on whole mounts and sections. Moreover, we characterize for the first time the different isoforms of FGFR1-3 by analysing their differential expression in limb ectoderm and mesodermal tissues, using RT-PCR and in situ hybridisation on sections. Finally, isoform-specific sequences for FgfR1IIIb, FgfR1IIIc, FgfR3IIIb and FgfR3IIIc were determined and deposited in GenBank with the following accession numbers: GU053725, GU065444, GU053726, GU065445, respectively.Fundacao para a Ciencia e Tecnologia [SFRH/BD/33176/2007]; Portuguese Government; Fundacao para a Ciencia e Tecnologia, Portugal [OBD/099758/2008]; EU; IBB/CBM
PO-0638: Adaptive dose painting by numbers for head and neck cancer: interim analysis of a randomised trial
International audience1. Recherches sur le Fayuan zayuan yuanshi ji de Sengyou (445-518), premiĂšre anthologie de rites bouddhiques (suite : le contenu des juan 4 et 5) Notre travail de reconstruction du Fayuan zayuan yuanshi ji æłèéç·Łćć§é (Anthologie [pour comprendre] le commencement et lâorigine de diverses [pratiques] dans le jardin des devoirs ; ci-aprĂšs Fayuan) de Sengyou ć§ç„ (445-518) nous a amenĂ©s cette annĂ©e Ă nous pencher sur les 22 premiers titres de la section sur le saáčgha (Sengbao ć§ćŻ¶, « Le joyau de la Loi ..
Noninvasive measurements of arterial stiffness: Repeatability and interrelationships with endothelial function and arterial morphology measures
Corey J Huck1, Ulf G Bronas1, Eric B Williamson1, Christopher C Draheim1, Daniel A Duprez2, Donald R Dengel1,31School of Kinesiology, University of Minnesota, Minneapolis, MN, USA; 2Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, MN; 3Research Service, Minneapolis Veterans Affairs Medical Center, Minneapolis, MN, USABackground: Many noninvasive arterial assessment techniques have been developed, measuring different parameters of arterial stiffness and endothelial function. However, there is little data available comparing different devices within the same subject. Therefore, the purpose of this study was to examine the repeatability and interrelationships between 3 different techniques to measure arterial stiffness and to compare this with forearm-mediated dilation.Methods: Carotid-radial pulse wave velocity was measured by the Sphygmocor (SPWV) and Complior (CPWV) devices, cardio-ankle vascular index (CAVI) was measured by the VaSera device, vascular structure and function was assessed using ultrasonography and evaluated for reliability and compared in 20 apparently healthy, college-aged men and women.Results: The intraclass correlation coefficient and standard error of the mean for the Sphygmocor (R = 0.56, SEM = 0.69), Complior (R = 0.62, SEM = 0.69), and VaSera (R = 0.60, SEM = 0.56), indicated moderate repeatability. Bland-Altman plots indicated a mean difference of 0.11 ± 0.84 for SPWV, 0.13 ± 1.15 for CPWV, and –0.43 ± 0.90 for CAVI. No significant interrelationships were found among the ultrasound measures and SPWV, CPWV, and CAVI.Conclusions: The three noninvasive modalities to study arterial stiffness reliably measures arterial stiffness however, they do not correlate with ultrasound measures of vascular function and structure in young and apparently healthy subjects.Keywords: Pulse wave velocity, intima-media thickness, flow-mediated dilatio
Analyse au microscope Ă©lectronique Ă balayage et au rugosimĂštre dâimpacts laser CO2 sur la dentine
The aim of the study was to compare the morphology of craters produced on the dentinal surface by CO2 laser beams (LASERSATtmCO2) before and after the removal of the carbonized layer, besides with different seetings of the power and duration of the laser beam.Thirty-three recently extracted non carious young third molar teeth were sectionned from vestibular and lingual surfaces, exposing a planed dentinal surface. Twenty impacts were made on each of dentinal surface producing 20 individual craters. The duration and the power of each laser beam were different on each tooth. The duration varied from 0.1 to 0.4 second (0.1 - 0.2 - 0.3 - 0.4 s). The power varied from 1 to 5 watts (1, 2, 3, 4, 5 w).Specimens obtained for a power of 3 and 4 watts and a duration of 0.1 and 0.2 second were examined with a JEOL 35CF (25 KV, magnification: x 30, x 110, x 200), before and after the removal of the carbonized layer. The carbonized layer of the craters was removed with an air polisher (HEATCO).Craters obtained for ail duration values as well as for ail power values were analyzed with a profilometer. The chosen profilometer was: TALISURF 10; horizontal amplification Vh = 20; vertical amplification Vv = 200.Samples were observed by a SEM and the craters depth and diameter were measured with a profilometer. Then, the carbonized layer of the craters was removed with an airpolisher and the cleaned dentinal surface was observed again with the SEM and the profilometer. Measurements were entered in a computer (using the SIPHAR programm) in order to calculate the mean values of the depth, the diameter and the area, for ail test conditions.It appears that the carbonized layer is not adherent to the dentine and can be easily removed. From the mean values, we can conclude that the diameter is about four times larger than the depth for the nocleaned craters and is about five to six times larger than the depth for the cleaned craters. The profils of the craters cannot be used for retention pins in the composite adhesion but the adhesion area is increased after a laser beam.Cette Ă©tude a pour but dâobserver et de quantifier les cratĂšres produits par un tir focalisĂ© discontinu au laser CO2 (Lasersattm), avant et aprĂšs Ă©limination de la couche carbonisĂ©e par un aĂ©ropolisseur. Trentetrois molaires, extraites et indemnes de caries, sont coupĂ©es en deux dans le sens mĂ©sio-distal et leurs faces vestibulaires et linguales sont sectionnĂ©es pour donner une surface dentinaire plane. Vingt cratĂšres sont rĂ©alisĂ©s par un tir focalisĂ© discontinu sur chaque surface dentinaire. Les temps dâapplication et les puissances du rayonnement utilisĂ©s sont respectivement: 0.1, 0.2, 0.3, 0.4 seconde et 1, 2, 3, 4, 5 watts. Ces cratĂšres sont analysĂ©s au microscope Ă©lectronique Ă balayage et au rugosimĂštre, avant et aprĂšs Ă©limination de la couche carbonisĂ©e. Les rĂ©sultats obtenus sont traitĂ©s Ă lâaide du logiciel SIPHAR sur PC; nous obtenons un profil moyen du cratĂšre pour chaque puissance et temps dâapplication utilisĂ©s. Les rĂ©sultats sont les suivants: le diamĂštre est environ quatre fois plus grand que la profondeur avant Ă©limination de la couche carbonisĂ©e et est cinq Ă six fois plus important aprĂšs Ă©limination de cette couche. Le diamĂštre et la profondeur des cratĂšres sont plus importants aprĂšs Ă©limination de la couche carbonisĂ©e. La couche carbonisĂ©e a une Ă©paisseur rĂ©guliĂšre sauf au fond du cratĂšre oĂč elle est plus faible que sur les parois. Avant Ă©limination de la couche carbonisĂ©e le profil du cratĂšre est un cĂŽne, aprĂšs Ă©limination de la couche, le profil est un cĂŽne tronquĂ©. En conclusion, les cratĂšres obtenus ne peuvent ĂȘtre considĂ©rĂ©s comme des ancrages efficaces pour dâĂ©ventuels collages dentinaires avec des composites; toutefois la surface dâadhĂ©sion sâen trouve considĂ©rablement accrue
Pulmonary function is associated with distal aortic calcium, not proximal aortic distensibility. MESA lung study
Forced expiratory volume in one second strongly predicts mortality from cardiovascular disease. FEV1 has been associated with aortic stiffness a strong independent predictor of cardiovascular mortality. However, the anatomical site and possible mechanisms linking aortic stiffness and lung function are unknown. We therefore examined if FEV1 and CT percent emphysema were associated with calcification of the abdominal aorta or reduced distensibility of the proximal thoracic aorta.The Multi-Ethnic Study of Atherosclerosis (MESA) measured aortic calcification on cardiac and abdominal CT scans and proximal aortic distensibility using magnetic resonance among participants aged 45â84 years without clinical cardiovascular disease. Spirometry was measured following ATS/ERS guidelines and percent emphysema was measured in the lung fields of cardiac CT scans. Multivariate analyses adjusted for age, sex, race/ethnicity and cardiovascular risk factors. Of 1,917 participants with aortic distensibility measures, 13% were current and 38% were former smokers. Eighteen percent had airflow limitation without asthma. FEV1 was associated with the extent of distal aortic calcification (0.76; 95%CI 0.60â0.97, p = 0.02) but not proximal aortic calcification or proximal aortic distensibility (â0.04 mmHgâ1; 95%CI â0.16â0.09 mmHgâ1, p = 0.60). Percent emphysema was associated with neither measure. FEV1 was associated with severity of distal aortic calcification where it was present independently of smoking and other cardiovascular risk factors but not with distensibility or calcification of the proximal aorta
The development and psychometric validation of the self-efficacy and performance in self-management support (SEPSS) Instrument
__Aim:__ To develop and psychometrically test the self-efficacy and performance in self-management support (SEPSS) instrument.
__Background:__ Facilitating persons with a chronic condition to take an active role in the management of their condition, implicates that nurses acquire new competencies. An instrument that can validly and reliably measure nurses' performance and their perceived capacity to perform self-management support is needed to evaluate current practice and training in self-management support.
__Design:__ Instrument development and psychometric testing of the content and construct validity, factor structure and reliability.
__Methods:__ A literature review and expert consultation (N = 17) identified the content. The items were structured according to the Five-A's model and an overarching category of 'overall' competencies. The initial instrument was tested in a sample of 472 nurses and 51 nursing students from Belgium and the Netherlands, between June 2014-January 2015.
__Results:__ Confirmatory factor analyses revealed satisfactory fit indices for the six-factor structure. Discriminating power was demonstrated for subgroups. The overall internal consistency (Cronbach's alpha) was high both for the self-efficacy and the performance items. The test-retest intra-class correlation coefficients were good.
__Conclusion:__ The SEPSS instrument is a 36-item, Likert-scaled self-reporting instrument with good content and construct validity, and good internal consistency reliability and good test-retest reliability. Therefore, it is a promising instrument to measure self-efficacy and performance with regard to self-management support
Effects of High Flavanol Dark Chocolate on Cardiovascular Function and Platelet Aggregation.
Regular consumption of chocolate and cocoa products has been linked to reduced cardiovascular mortality. This study compared the effects of high flavanol dark chocolate (HFDC; 1064mg flavanols/day for 6 weeks) and low flavanol dark chocolate (LFDC; 88mg flavanols/day for 6 weeks) on blood pressure, heart rate, vascular function and platelet aggregation in men with pre-hypertension or mild hypertension. Vascular function was assessed by pulse wave analysis using radial artery applanation tonometry in combination with inhaled salbutamol (0.4 mg) to assess changes due to endothelium-dependent vasodilatation. HFDC did not significantly reduce blood pressure compared to baseline or LFDC. Heart rate was increased by LFDC compared to baseline, but not by HFDC. Vascular responses to salbutamol tended to be greater after HFDC. Platelet aggregation induced by collagen or the thromboxane analogue U46619 was unchanged after LFDC or HFDC, whereas both chocolates reduced responses to ADP and the thrombin receptor activator peptide, SFLLRNamide (TRAP6), relative to baseline. Pre-incubation of platelets with theobromine also attenuated platelet aggregation induced by ADP or TRAP6. We conclude that consumption of HFDC confers modest improvements in cardiovascular function. Platelet aggregation is modulated by a flavanol-independent mechanism that is likely due to theobromine.This study was supported by a grant (to R. Corder) from Barry Callebaut Belgium N
Spectroscopy of a single-carrier bilayer graphene quantum dot from time-resolved charge detection
We measured the spectrum of a single-carrier bilayer graphene quantum dot as
a function of both parallel and perpendicular magnetic fields, using a
time-resolved charge detection technique that gives access to individual tunnel
events. Thanks to our unprecedented energy resolution of 4eV, we could
distinguish all four levels of the dot's first orbital, in particular in the
range of magnetic fields where the first and second excited states cross
(mT). We thereby experimentally establish, the hitherto
extrapolated, single-charge carrier spectrum picture and provide a new upper
bound for the inter-valley mixing, equal to our energy resolution
- âŠ