Hygroscopic Expansion of Aesthetic Restorative Materials: One-Year Report

Objective: To measure the long-term linear hygroscopic expansion (LHE) of several materials using bulked and layered techniques.Materials and Methods: Seven materials were used; Fuji Cap II, Fuji II LC, Photac-Fil Aplicap, Vitremer, Dyract, Tetric and Z100. Ten specimens (6×4 mm) were made for each material using layered and bulked techniques (each group comprises five specimens). The specimens were stored in distilled water at 37°C. The length of each specimen was measured immediately after preparation, 24 hours, one week, one month, three months, six months, nine months and one year. This was used to calculate the percentage change in the length of materials. The mean LHE and standard deviation were calculated. Repeated measure analysis and paired sample t-test were used.Results: The type of material and time had a significant effect on LHE. Fuji Cap II and Fuji II LC exhibited no significant changes after one-year and one month, respectively.However, layered specimens of Photac-Fil Aplicap and Tetric showed constant expansionuntil six month, whereas bulked specimens reached the constant length at three months.Constant expansion was obtained for layered and bulked specimens of Dyract and Z100 at six month. Layered specimens of Vitremer showed no significant differences except between 24 hours and one year measurements. But in bulked specimens, the results at ninemonths and one year were significantly different from those obtained at three months and before.Conclusion: Fuji II showed no significant LHE and resin-modified glass ionomer cements (RMGICs) exhibited the highest LHE. Dyract maintained an intermediate LHE in comparison with RMGIC and composite resin

International Benchmarking of the Individual Tree Detection Methods for Modeling 3-D Canopy Structure for Silviculture and Forest Ecology Using Airborne Laser Scanning

Canopy structure plays an essential role in biophysical activities in forest environments. However, quantitative descriptions of a 3-D canopy structure are extremely difficult because of the complexity and heterogeneity of forest systems. Airborne laser scanning (ALS) provides an opportunity to automatically measure a 3-D canopy structure in large areas. Compared with other point cloud technologies such as the image-based Structure from Motion, the power of ALS lies in its ability to penetrate canopies and depict subordinate trees. However, such capabilities have been poorly explored so far. In this paper, the potential of ALS-based approaches in depicting a 3-D canopy structure is explored in detail through an international benchmarking of five recently developed ALS-based individual tree detection (ITD) methods. For the first time, the results of the ITD methods are evaluated for each of four crown classes, i.e., dominant, codominant, intermediate, and suppressed trees, which provides insight toward understanding the current status of depicting a 3-D canopy structure using ITD methods, particularly with respect to their performances, potential, and challenges. This benchmarking study revealed that the canopy structure plays a considerable role in the detection accuracy of ITD methods, and its influence is even greater than that of the tree species as well as the species composition in a stand. The study also reveals the importance of utilizing the point cloud data for the detection of intermediate and suppressed trees. Different from what has been reported in previous studies, point density was found to be a highly influential factor in the performance of the methods that use point cloud data. Greater efforts should be invested in the point-based or hybrid ITD approaches to model the 3-D canopy structure and to further explore the potential of high-density and multiwavelengths ALS data

Laboratory and clinical investigations into resin-modified glass-ionomer cements and related materials

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN010213 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Investigation into the Translucency of Tooth-Colored Restorative Materials

Objective: The aim of this study was to investigate the translucency of resin-modified glass-ionomer cements (RMGIC) and polyacid-modified composite resin (PCMR) over a period of one year.Materials and Methods: The study was done on three RMGIC (Fuji II LC, Photac-Fil Aplicap and Vitremer) and one PCMR (Dyract). A conventional GIC (Fuji Cap II) and two composite resins (Tetric and Z 100) were used for comparison. Five discs approximately 5 mm in diameter and 1.5 mm thick were made from each material using a Perspex mould. The specimens were kept in distilled water at 37°C during the test period. The optical density/mm (inverse of translucency) of each material was measured using a special photometric set up after preparation and after one week, six months, and one year.Means and standard deviations were calculated and subjected to Two-way ANOVA, Oneway ANOVA and Scheffe tests.Results: The results indicated that all of the materials, except Dyract, showed an increase of translucency over the test period. After one year, the conventional GIC was the least translucent material.Conclusion: The translucency of the resin-modified GICs and Dyract was equivalent to that of the composite resins Tetric and Z 100

Effect of multiple adhesive coating on the microshear bond strength and surface microhardness of bonded dentin after using four adhesives

"nBackground and Aims: In this in-vitro study, the effect of multiple adhesive coating on the microshear bond strength of composite to dentin and surface microhardness of dentin after treatment with four adhesives (One Step Plus, One Step, Single Bond, Single Bond 2) were evaluated. "nMaterials and Methods: One hundred intact human molars were cut to obtain disks of dentin having 2 mm thickness. For the microshear bond test, sixty disks were randomly divided into four groups. In each group one type of adhesive was used. In one half of a disk two layers and in another half six layers of adhesive were applied. Cylinders with 1mm height was filled with a composite and light cured. The cross-head speed was 0.5 mm/min. Vickers microhardness was tested on forty dentin disks which divided into four groups and prepared in the same manner used for microshear bond test. Data were analyzed by Two-way ANOVA and Tukey tests. "nResults: The highest and lowest bond strength were recorded as 29.49 ± 5.74 MPa (One Step Plus; 6 layers), and 21.23 ± 4.83 MPa (One Step Plus; 2 layers), respectively. The results indicated that One Step Plus bond strength in 6 Layers was significantly higher than 2 layers. The highest and lowest dentin hardness values were"n39.08 ± 8.34VHN (Single Bond; 2 layers) and 28.53 ± 5.98 VHN (One Step Plus; 6 layers). None of the adhesives exhibited significant difference in hardness with regards to the layers applied (P>0.05). Presence of filler in adhesives had no significant effect on bond strength (P=0.05) whereas caused significant decrease in the dentin microhardness (P<0.05). In addition, type of solvent had significant effect on the bond strength and bond strength was significantly higher in acetone-base adhesives (P<0.05). However, dentin microhardness was significantly higher in the ethanol-base adhesives (P<0.05). "nConclusion: Multiple adhesive coating had no influence on the microshear bond strength of composite to dentin and dentin surface microhardness. It was dependent on the type of adhesive used

The Relationship between Level of Vitamin C in Follicular Fluid and ‎Maturation of Oocytes and Embryo Quality in Patients Undergoing In-vitro ‎Fertilization

BACKGROUND AND OBJECTIVE: Oxidative stress and its adverse effects in vitro or on the body can reduce the number of reproductive cells and embryo quality. Given the fact that vitamin C is a natural antioxidant with a protective role, in this study we aimed to evaluate the relationship between the level of vitamin C in follicular fluid (FF) and maturation of oocytes and embryo quality of patients undergoing in vitro fertilization (IVF). METHODS: This cross-sectional study was performed on the eggs and embryos of 50 patients admitted to IVF unit of Al Zahra Hospital, Rasht, Iran. Patients underwent the same mediations used to induce ovulation, and then they were injected 10000 units of human chorionic gonadotropin. Finally, they underwent 36 hours of follicle suction. Vitamin C level in FF was measured by biochemical methods. Maturation of oocytes and embryo quality were examined with inverted light microscope. FINDINGS: After examining 583 eggs and 275 embryos the following results were obtained: the percentage of metaphase II oocytes in vitamin C level of less than one was 81.3% (412), but when compared to vitamin C level of one or more, it was 71.1% (54), which were significantly different (p=0.038). In the sub-classification, vitamin C level (0.5-1 mg/dl), MII oocyte frequency and the two pronuclei embryos were higher but the difference was not statistically significant. CONCLUSION: The results showed that the quality of oocyte maturation and embryos in lower levels of vitamin C levels had improved, as compared to higher levels

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE ULTRAFINE-GRAINED COPPER TUBE PRODUCED BY SEVERE PLASTIC DEFORMATION

In this paper, cyclic flaring and sinking (CFS) as a new severe plastic deformation (SPD) method was employed to produce the ultrafine grain (UFG) copper tubes. The extra friction has eliminated in the CFS method that provided the possibility for production of longer UFG tubes compared to the other SPD methods. This process was done periodically to apply more strain and consequently finer grain size and better mechanical properties. The CFS was performed successfully on pure copper tubes up to eleven cycles. Mechanical properties of the initial and processed tubes were extracted from tensile tests in the different cycles. The remarkable increase in strength and decrease in ductility take placed in the CFS-ed tubes. The material flow behavior during CFS processing was analyzed by optical microscopy (OM), and a model was presented for grain refinement mechanism of pure copper based on multiplication and migration of dislocations (MMD). This mechanism caused that the initial grains converts to elongated dislocation cells (subgrains) and then to equiaxed ultrafine grains in the higher cycles. The CFS method refined the microstructure to fine grains with the mean grain size of 1200nm from initial coarse grain size of 40µ

High-speed quantitative optical imaging of absolute metabolism in the rat cortex.

Significance: Quantitative measures of blood flow and metabolism are essential for improved assessment of brain health and response to ischemic injury. Aim: We demonstrate a multimodal technique for measuring the cerebral metabolic rate of oxygen ( CMRO2 ) in the rodent brain on an absolute scale ( μM O2/min ). Approach: We use laser speckle imaging at 809 nm and spatial frequency domain imaging at 655, 730, and 850 nm to obtain spatiotemporal maps of cerebral blood flow, tissue absorption ( μa ), and tissue scattering ( μs' ). Knowledge of these three values enables calculation of a characteristic blood flow speed, which in turn is input to a mathematical model with a "zero-flow" boundary condition to calculate absolute CMRO2 . We apply this method to a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation. With this model, the zero-flow condition occurs during entry into CA. Results: The CMRO2 values calculated with our method are in good agreement with those measured with magnetic resonance and positron emission tomography by other groups. Conclusions: Our technique provides a quantitative metric of absolute cerebral metabolism that can potentially be used for comparison between animals and longitudinal monitoring of a single animal over multiple days. Though this report focuses on metabolism in a model of ischemia and reperfusion, this technique can potentially be applied to far broader types of acute brain injury and whole-body pathological occurrences

High-speed spatial frequency domain imaging of rat cortex detects dynamic optical and physiological properties following cardiac arrest and resuscitation.

Quantifying rapidly varying perturbations in cerebral tissue absorption and scattering can potentially help to characterize changes in brain function caused by ischemic trauma. We have developed a platform for rapid intrinsic signal brain optical imaging using macroscopically structured light. The device performs fast, multispectral, spatial frequency domain imaging (SFDI), detecting backscattered light from three-phase binary square-wave projected patterns, which have a much higher refresh rate than sinusoidal patterns used in conventional SFDI. Although not as fast as "single-snapshot" spatial frequency methods that do not require three-phase projection, square-wave patterns allow accurate image demodulation in applications such as small animal imaging where the limited field of view does not allow single-phase demodulation. By using 655, 730, and 850 nm light-emitting diodes, two spatial frequencies ([Formula: see text] and [Formula: see text]), three spatial phases (120 deg, 240 deg, and 360 deg), and an overall camera acquisition rate of 167 Hz, we map changes in tissue absorption and reduced scattering parameters ([Formula: see text] and [Formula: see text]) and oxy- and deoxyhemoglobin concentration at [Formula: see text]. We apply this method to a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) to quantify hemodynamics and scattering on temporal scales ([Formula: see text]) ranging from tens of milliseconds to minutes. We observe rapid concurrent spatiotemporal changes in tissue oxygenation and scattering during CA and following CPR, even when the cerebral electrical signal is absent. We conclude that square-wave SFDI provides an effective technical strategy for assessing cortical optical and physiological properties by balancing competing performance demands for fast signal acquisition, small fields of view, and quantitative information content