m.h. fathi

In this research, a kind of environmentally-friendly inorganic-organic hybrid nanocomposite coating based on silica containing titania/silica core/shell nanoparticles was synthesized and characterized for conservation of facade tiles in historical buildings. The matrix of the composite was prepared by sol-gel process via two methods of ultrasonic and reflux stirring. Tetraethyl orthosilicate (TEOS) and poly-dimethyl siloxane hydroxy-terminated (PDMS-OH) were used for the formation of silica network and creation of flexibility and hydrophobicity, respectively. Titania nanoparticles were used in the form of titania/silica core/shell as ultraviolet absorber. The synthesized nanocomposite was applied on the microscope slides and tiles by dip coating technique. The properties of nanoparticles and coatings were characterized by Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and water contact angle measurement. The results revealed that formation of titania/silica core/shell structure was successful. The investigation of PDMS content effect on transparency, cohesion and hydrophobicity of the coating confirmed that the optimum content of this siloxane was around 20 wt.%. In general, the results showed that the silica-based hybrid nanocomposite reinforced with TiO2/SiO2 core/shell nanoparticles could produce a transparent and hydrophobic coating for tile and glass protection.

Methane eructated from ruminants is considered to be one of the most important contributors to global warming, imposing an environmental burden that cannot be ignored. Meanwhile, it represents a loss of 2% to 15% of the gross energy intake (Johnson and Johnson 1995). Animal nutritionists have been studying manipulation of the rumen microbial ecosystem to reduce methane emission without the adverse effects on rumen function. There is a need to identify feed additives to modify ruminal fermentation characteristics and increase the efficiency of feed utilization, thereby inhibiting the ruminal methanogenesis. In recent years, essential oils (Benchaar 2007), plant secondary metabolites such as condensed tannins and saponins (Pen et al., 2006; Bhatta etal, 2009) and dietary lipids (Dohme et al., 2001) have arisen as attractive rumen modifiers to improve rumen microbial metabolism as well as inhibit methane production in ruminants. Particularly, Woodward et al. (2006) showed a positive effect of fish oil (FO) on reducing CH4 emissions in a short-term study, whereas no reduction was observed for a longer-term study. The positive effects of tannin-rich plant extracts on methane emission and methanogens population in vitro as well as in vivo have been examined (Patra et al., 2006; Patra and Saxena, 2010; Becker et al., 2014). The objective of this study was to evaluate the effect of pomegranate by-products (pomegranate oil and peel) on the in vitro rumen fermentation with respect to methane emissions. Basic substrate was contained of 600 g/kg forage and 400 g/kg concentrate. Pomegranate oil was administered in doses of 2, 4, and 6% of substrate DM in the first trial and in the second trial powder peel pomegranate was added in doses of 2.5, 5, and 7.5% of substrate DM. Syringes were inoculated with 40 ml of a rumen fluid–buffer mix (10 ml rumen fluid and 30 ml buffer) and were incubated at 39°C. The gas production was measured at different incubation times and total gas production, CO2, hydrogen, and methane production were determined after 24h of incubation. Data were analyzed by GLM procedure of SAS (2001) software. The results of the first experiment showed that the addition of pomegranate oil to substrate did not affect total gas production, digestibility parameters (b and c), metabolizable energy (ME) and organic materails dry (OMD). Methane production was decreased by addition of 6% of pomegranate oil (P< 0.05), but not by lower levels of oil. Lipids significantly decreased CH4 emission in the short-term study (−27%), but this effect was not observed after 11 wk of lipid supplementation. On the other hand, several in vitro trials have shown that FO reduced CH4 methanogenesis (Fievez et al. 2003; Patra and Yu 2013). Saturated medium chain fatty acids, C10-C14, also lead to methane reduction. At ruminal temperature, an increasing chain length of medium chain fatty acids seems to reduce their efficiency in inhibiting methanogens and methane formation due to lower solubility (Bucher et al. 2008; Patra 2012). Beauchemin et al. (2008) reviewed the practical application of lipids to reduce methanogenesis. Oil supplementation to diet decreased methane emission by 80% in vitro (Fievez et al. 2003) and about 25% in vivo (Machmu¨ller et al. 2000). The toxic effects of certain oils on rumen protozoa contributed to reduce methane production (Machmu¨ller et al., 1998). The addition of canola oil at 0%, 3.5% or 7% to the diets of sheep reduced the number of rumen protozoa by 88–97% (Machmu¨ller et al. 1998). The detrimental impact of unsaturated fatty acids has also been reported (Henderson1973). Machmulleur et al. (1998) observed coconut oil as more effective inhibitor followed by rapeseed, sunflower seed, and linseed oil. Coconut oil comprises medium chain fatty acids. Dong et al. (1997) compared canola oil to coconut oil and demonstrated coconut oil as more effective methane inhibitor. Coconut oil controlled rumen methanogens by changing the metabolic activity and composition (Machmu¨ller et al., 2003). The inclusion of sunflower oil to the diet of cattle resulted in 22% decrease of methane emissions (McGinn et al., 2004). In the second experiment, adding of 5 and 7.5% of pomegranate peel to substrate DM reduced (P <0.05) total gas production after 24, 72, and 96 h of incubation. Metabolizable energy, b fraction, and OMD digestibility reduced by pomegranate peel powder. Because these parameters dependent the total gas production. Methane production was reduced by adding pomegranate peel to diet, but no difference was observed between methane produced by diet contained different doses of pomegranate peel. However, a direct effect of condensed tannins on rumen methanogens cannot totally be excluded (Field et al. 1989). Furthermore, tannins decrease the degradation of nutrients in the rumen, which then may be degraded in the hindgut. This could have contributed to a lower methane emission, because hindgut fermentation differs from ruminal fermentation by resulting in a lower methane production per unit of fermented nutrients (Fievez, et al. 1999). A meta-analysis of in vivo experiments with tannins by Jayanegara et al. (2012) reported a relatively close relationship between dietary tannin concentration and CH4 production per unit of digestible OM. According to Goel and Makkar (2012), the antimethanogenic effect of tannins depends on the dietary concentration and is positively related to the number of hydroxyl groups in their structure. These authors concluded that hydrolyzable tannins tend to act by directly inhibiting rumen methanogens, whereas the effect of condensed tannins on CH4 production is more through inhibition of fiber digestion. They also pointed out that more animal research is needed with these compounds to establish their antimethanogenic effect. Hydrolysable tannins are hydrolyzed in the rumen and some could be toxic (Lowry et al., 1996; McSweeney et al. 2003). Addition of pomegranate oil and pomegranate peel powder to base substrate did not have a significant effect on digestibility in in vitro conditions, but reduce the production of methane gas as a harmful greenhouse gas in the atmosphere, that would loss significant portion of the energy of the feed. Therefore, the use of pomegranate oil and pomegranate peel in the present experiment as inexpensive edible compounds not only have no negative effects on feeding ruminants, but also a good alternative to ionophors and other antigens.

This experiment was conducted to investigate the effects of spearmint sativum essence added to starter concentrate of Holstein calves. For this purpose, thirty calves (15 male and 15 female) with the mean of 41.3± 0.73 kg birth weight were used in a completely randomized design. The experiment was done from 3 days age to 3 weeks after weaning. Three levels 0 (control), 0.025 and 0.05% of the essence were added to the calves starter concentrate as dry matter (DM) basis. Plasma samples and ruminal fluid were collected at different times. Weight records, feed consumption, fecal score and weaning age were determined. Results showed that the treatments had no significant effect on DM intake and average daily gain during the different weeks of experiment. However, the 0.05% essence increased (P<0.05) alfalfa intake in entire trial. Also, the high level of essence reduced (P<0.05) claves weaning age. During the preweaning period 0.05% essence increased (P<0.05) fecal score, however this effect was not significant in postweaning and entire periods. Plasma parameters and ruminal metabolites were not affected by the essence. It was concluded that 0.05% spearmint essence added to starter concentrate decreased calves weaning age and increased their forage consumption.

An experiment was conducted to evaluate the effects of different levels of raw and heated grass pea (Lathyrus sativus) seed on growth performance and some blood metabolites of broiler chickens. Fourteen day old broilers (210 chickens) were randomly assigned to 7 treatments, with 3 replicates and 10 birds in each replicate. Broilers were fed the isocaloric and isonitrogenous diets containing 0, 10, 20 and 30 % of raw or heated grass pea seed. Feed intake, weight gain, feed conversion ration (FCR), European efficiency factor (EEF) and carcass characteristics were recorded. Total plasma protein, triglyceride and cholesterol concentration of broilers were measured at 2 stages of growth (28 & 42d). The results showed that diets containing 20 and 30% raw grass pea seed, increased feed intake significantly (P<0.05) and heated at 30% level increased feed intake significantly (P<0.05). Heating the grass pea seed improved weight gain and FCR of broilers in different levels. The birds which received 20% raw or 30% heated grass pea seed had significantly greater (P<0.05) liver weight than the control group. Total plasma protein concentration was affected by treatments at 28d. At 42d, the birds which received 30% raw grass pea seed had significantly (P<0.05) lowest cholesterol concentration. Increasing the levels of raw grass pea seed, decreased cholesterol concentration. It was concluded that heating process have some beneficial effect on grass pea seed used in chicken diets.

Statement of problem: 

Carbamide peroxide bleaching has been implicated to adversely affect the bond strength of composite to enamel.

The purpose of this study was to evaluate the effect of carbamide peroxide bleaching on the shear bond strength of composite to bleached enamel bonded with a three step total etch system; Scotchbond Multipurpose(SBMP), and two simplified all-in-one systems; Prompt L-Pop (PLP) and i bond.

Seventy two human molar teeth were randomly assigned to three control and three experimental groups. The experimental groups were subjected to a %15 carbamide peroxide bleaching system. Twenty four hours later, all the control and experimental groups were bonded with cylinders of composite, using three dental bonding agents. After thermocycling, shear bond strengths were determined by a universal testing machine. The data were evaluated using one way ANOVA and Duncan tests (P<0.05).

The composite bond strengths of SBMP were 19.52±5.21 MPa to the unbleached and 7.95±4.16 MPa to the bleached enamel. For PLP, the unbleached enamel exhibited bond strengths of 9.66±2.89 MPa and, the bleached one showed a bond strength value of 5.39±0.66 MPa. For i-bond the composite bond strengths were 11.46±4.31 MPa to the unbleached and 6.41±2.01 MPa to the bleached enamel. There was a statistically significant difference between the shear bond strength of the control and experimental groups of each dental bonding agent (SBMP, P<0.001, PLP, P<0.001, i bond: P=0.002).

Bleaching with 15% carbamide peroxide used in this study reduced the bond strengths of the composite to the enamel bonded with a three step total etch and two simplified one step all-in-one dental bonding agents.

Regarding the importance of surface roughness of tooth structure and restorative materials on plaque retention, this study was done to evaluate the effect of home and office bleaching agents on surface roughness of microhybrid and nanofilled composite resins. Point 4 (kerr, USA) microhybride composite, Premise (Kerr, USA) and Filtek supreme (3M ESPE, USA) nanofilled composites, Opalescence PF (Ultradent, USA) as the home bleaching agent and Opalescence Quisk (Ultradent, USA) as the office bleaching agent were selected. One hundred and fifty samples were divided into 15 groups (n = 10). For each composite, five groups were defined as: control, two weeks home bleaching, 4 weeks home bleaching, one time office bleaching and two times office bleaching with 2 weeks interval. The composites light cured under clear matrix strip and polished with soflex TM (3M ESPE, USA) polishing disks systems.After bleaching with specific protocol, surface roughness of samples was measured withprofilometer (SM7 Profile Test, Italy). The data were analyzed with two-way ANOVA statistical test. Surface morphology of samples were analyzed with scanning electron microscopy; SEM (XL30, Philips, Netherlands). There was no significant difference in surface roughness among all groups (p value > 0.05). There were no difference between the surface morphology of control and experimental groups of each composite. The bleaching agents used in this study had no effects on surface roughness of two types of nanofilled composites and one type of microhybrid composite.

Investment materials have been used to produce molds for casting of Inlays, Onlays, crowns and bridges. In this study, gypsum and investments routinely used in Iran, were evaluated and characterized, then α hemi hydrate calcium sulfate and a new dental investment with a gypsum-micro silica binder were fabricated. The purpose of this study was to produce and evaluate a new gypsum investment product in Iran. Using this production, it could be not necessary to import this material from other countries.Methods and Materials: Yellow, well-mixed, orthodontic gypsums and casting investments routinely used in Iran, were evaluated and characterized with scanning electron microscopy elemental analysis (SEM) and XRD phase analysis. The morphology of these materials also was evaluated. Gypsum mineral (CaSO4.2H2O) was fired at 3 atmosphere autoclave and dental stone produced, and evaluated. New dental investment was fabricated with fine silica, Alumina, Silicon Carbide, Micro Silica and Polypropylene. Cold crushing strength (CCS) and setting expansion tests were performed. Casting was done at new molds. Phase changing of investments was tested at high temperatures with x- ray diffraction phase analysis. Compressive strength of some samples was tested after firing. Using above techniques showed that yellow and well-mixed gypsum are dental stones, orthodontic gypsum is high strength stone and investments have phosphate bonds. New investment has efficiency at 1000°C, and more. There isnt any decomposition in gypsums at these temperatures. Silicon Carbide and polypropylene increase CCS. Compressive Strength of these new investments increases 7 times after firing. Micro silica is used as a refractory and binder. Micro silica is very fine and has a large specific surface. So it is a good binder and it leads a smooth surface castings. Silicon Carbide increases investment strength and thermal resistance. Poly propylene increases spaces for escaping of gases during casting. New gypsum- micro silica investment can be used at temperatures more than 1000°‍‍‍C. There are other materials which were proposed before to increase thermal resistance of gypsum investments, but they are more expensive than micro silica based products.

Evaluation of bonding in atomic level, by SEM/EDS analysis of Si atoms, is an exact method for determination of bond strength of metal and porcelain. The purpose of this study was to evaluate the bond strength of one noble alloy and two base metal alloys with and without beryllium.Methods and materials: Six specimens of each alloy Begostar, Rexillium III, Wiron 99 (10×10×1mm dimensions) were prepared. All specimens were airabraded with 50 μm aluminium oxide particles. Vita VMK 95 porcelain was fused on the central 6 mm diameter circular area of each specimen with 1 mm thickness. Porcelain was debonded by planar-shear test at a cross- head speed of 0/5 mm/min. Specimens were analyzed by SEM/EDS (Scanning Electron Microscope/Energy Dispresssive Spectroscopy) analysis 3 times throughout the study to determine the Si atomic percentage. Bond strength of porcelain to alloys was characterized by determining the Area Fraction of Adherent Porcelain (AFAP). Results were analyzed by one-way analysis of variance and LSD test. Statistical analysis showed a significant difference in the AFAP values among groups. AFAP value of noble alloy group (0.97±0.07) was significantly higher than other groups. For base metal groups, AFAP value of beryllium group (0.45±0.13) was significantly higher than non-beryllium group (0.17±0.04). Superior AFAP values of noble alloys, confirm better bond strength between noble alloys and porcelain as compared with base metal alloys. Also, in base metal alloys, specimens with beryllium, have a higher AFAP values and higher bond strengths.