Effect Of Daily Use Of An Enzymatic Denture Cleanser On Candida Albicans Biofilms Formed On Polyamide And Poly(methyl Methacrylate) Resins: An In Vitro Study.

Candida biofilms on denture surfaces are substantially reduced after a single immersion in denture cleanser. However, whether this effect is maintained when dentures are immersed in cleanser daily is unclear. The purpose of this study was to evaluate the effect of the daily use of enzymatic cleanser on Candida albicans biofilms on denture base materials. The surfaces of polyamide and poly(methyl methacrylate) resin specimens (n=54) were standardized and divided into 12 groups (n=9 per group), according to study factors (material type, treatment type, and periods of treatment). Candida albicans biofilms were allowed to form over 72 hours, after which the specimens were treated with enzymatic cleanser once daily for 1, 4, or 7 days. Thereafter, residual biofilm was ultrasonically removed and analyzed for viable cells (colony forming units/mm(2)) and enzymatic activity (phospholipase, aspartyl-protease, and hemolysin). Factors that interfered with the response variables were analyzed by 3-way ANOVA with the Holm-Sidak multiple comparison method (α=.05). Polyamide resin presented more viable cells of Candida albicans (P<.001) for both the evaluated treatment types and periods. Although enzymatic cleansing significantly (P<.001) reduced viable cells, daily use did not maintain this reduction (P<.001). Phospholipase activity significantly increased with time (P<.001) for both materials and treatments. However, poly(methyl methacrylate) based resin (P<.001) and enzymatic cleansing treatment (P<.001) contributed to lower phospholipase activity. Aspartyl-protease and hemolysin activities were not influenced by study factors (P>.05). Although daily use of an enzymatic cleanser reduced the number of viable cells and phospholipase activity, this treatment was not effective against residual biofilm over time.

The Effect Of Poly(methyl Methacrylate) Surface Treatments On The Adhesion Of Silicone-based Resilient Denture Liners.

Different surface treatment protocols of poly(methyl methacrylate) have been proposed to improve the adhesion of silicone-based resilient denture liners to poly(methyl methacrylate) surfaces. The purpose of this study was to evaluate the effect of different poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners. Poly(methyl methacrylate) specimens were prepared and divided into 4 treatment groups: no treatment (control), methyl methacrylate for 180 seconds, acetone for 30 seconds, and ethyl acetate for 60 seconds. Poly(methyl methacrylate) disks (30.0 × 5.0 mm; n = 10) were evaluated regarding surface roughness and surface free energy. To evaluate tensile bond strength, the resilient material was applied between 2 treated poly(methyl methacrylate) bars (60.0 × 5.0 × 5.0 mm; n = 20 for each group) to form a 2-mm-thick layer. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α = .05). A Pearson correlation test verified the influence of surface properties on tensile bond strength. Failure type was assessed, and the poly(methyl methacrylate) surface treatment modifications were visualized with scanning electron microscopy. The surface roughness was increased (P < .05) by methyl methacrylate treatment. For the acetone and ethyl acetate groups, the surface free energy decreased (P < .05). The tensile bond strength was higher for the methyl methacrylate and ethyl acetate groups (P < .05). No correlation was found regarding surface properties and tensile bond strength. Specimens treated with acetone and methyl methacrylate presented a cleaner surface, whereas the ethyl acetate treatment produced a porous topography. The methyl methacrylate and ethyl acetate surface treatment protocols improved the adhesion of a silicone-based resilient denture liner to poly(methyl methacrylate).

Hydrolysis of methyl benzoate from Piper arboreum by Naupactus bipes beetle

A new natural product was isolated from Piper arboreum (Piperaceae) leaves, the methyl 3-geranyl-4-hydroxybenzoate (1). The metabolism of P. arboreum leaves by Naupactus bipes beetle (Germar, 1824 - Coleoptera: Curculionidae) led to the hydrolysis of 1 to 3-geranyl-4-hydroxybenzoic acid (2). The structures of both compounds were determined based on spectroscopic analysis (¹H and 13C NMR, MS, and IR).

Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticles

Methyl esters were prepared by the clean, one-step catalytic esterification of primary alcohols using molecular oxygen as a green oxidant and a newly developed SiO(2)-supported gold nanoparticle catalyst. The catalyst was highly active and selective in a broad range of pressure and temperature. At 3 atm O(2) and 130 degrees C benzyl alcohol was converted to methyl benzoate with 100% conversion and 100% selectivity in 4 h of reaction. This catalytic process is much ""greener"" than the conventional reaction routes because it avoids the use of stoichiometric environmentally unfriendly oxidants, usually required for alcohol oxidation, and the use of strong acids or excess of reactants or constant removal of products required to shift the equilibrium to the desired esterification product.

1-Furoyl-3-methyl-3-phenylthiourea

The title compound, C13H12N2O2S, crystallizes with two independent molecules in the asymmetric unit. The two molecules differ in the conformation of the thiocarbonyl and carbonyl groups, and show the typical geometric parameters of substituted thiourea derivatives. The crystal structure is mainly stabilized by intermolecular N-H center dot center dot center dot O hydrogen bonding.

3-Nitrobenzoic acid-3-methyl-4-nitropyridine 1-oxide (1/1)

The title adduct, C(7)H(5)NO(4)center dot C(6)H(6)N(2)O(3), forms part of an ongoing study of the design of non-centrosymmetric systems based on 3-methy-4-nitropyridine 1-oxide. The components of the adduct are linked by intermolecular O-H center dot center dot center dot O hydrogen bonds. The rings of the two components are nearly planar, with a dihedral angle of 11.9 (2)degrees between the planes. The supramolecular structure shows that molecules of the title complex are linked into sheets by a combination of strong O-H center dot center dot center dot O and weak C-H center dot center dot center dot O hydrogen bonds.

5-Methyl-2,4-bis(methylsulfanyl)tricyclo[6.2.1.0(2,7)]undeca-4,9-diene-3,6-dione

The structure analysis of the title compound, C(14)H(16)O(2)S(2), shows the SMe and H atoms of the bond linking the six-membered rings to be syn and also to be syn to the bridgehead -CH(2)- group. Each of the five-membered rings adopts an envelope conformation at the bridgehead -CH(2)- group. The dione-substituted ring adopts a folded conformation about the 1,4-C center dot center dot center dot C vector, with the ketone groups lying to one side. The cyclohexene ring adopts a boat conformation.

4-Methyl-3-(2-phenoxyacetyl)-5-phenyl-1,3,4-oxadiazinan-2-one

The 1,3,4-oxadiazinane ring in the title compound, C(18)H(18)N(2)O(4), is in a twisted boat conformation. The two carbonyl groups are orientated towards the same side of the molecule. The dihedral angle between the planes of the benzene rings is 76.6 (3)degrees. Molecules are sustained in the three-dimensional structure by a combination of C-H center dot center dot center dot O, C-H center dot center dot center dot pi and pi-pi [shortest centroid-centroid distance = 3.672 (6) angstrom] interactions.

(5R)-3-(2-Chloroacetyl)-4-methyl-5phenyl-1,3,4-oxadiazinan-2-one

The 1,3,4-oxadiazinan-2-one ring in the title compound, C(12)H(13)ClN(2)O(3), is in a distorted half-chair conformation. The phenyl and chloroacetyl groups occupy axial and equatorial positions, respectively, and lie to the opposite side of the molecule to the N-bound methyl substituent. Molecules are consolidated in the crystal structure by C-H center dot center dot center dot O interactions.

1-Methyl-3-phenylsulfonyl-2-piperidone

The piperidone ring in the title compound, C12H15NO3S, has a slightly distorted half-chair conformation with the methyl, carbonyl and phenylsulfonyl ring substituents occupying equatorial, equatorial and axial positions, respectively. Molecules are connected into centrosymmetric dimers via C-H center dot center dot center dot O interactions and these associate into layers via C-H center dot center dot center dot O-S contacts. Further C-H center dot center dot center dot O interactions involving both the carbonyl and sulfonyl O atoms consolidate the crystal packing by providing connections between the layers.

2-Bromo-2-methyl-N-p-tolylpropanamide

In the title molecule, C(11)H(14)BrNO, there is twist between the mean plane of the amide group and the benzene ring [C(=O)-N-C...;C torsion angle = -31.2 (5)degrees]. In the crystal, intermolecular N-H...O and weak C-H...O hydrogen bonds link molecules into chains along [100]. The methyl group H atoms are disordered over two sets of sites with equal occupancy.

2-Bromo-2-methyl-N-(4-nitrophenyl)propanamide

The title compound, C(10)H(11)BrN(2)O(3), exhibits a small twist between the amide residue and benzene ring [the C-N-C-C torsion angle = 12.7 (4)degrees]. The crystal structure is stabilized by weak N-H center dot center dot center dot O, C-H center dot center dot center dot Br and C-H center dot center dot center dot O interactions. These lead to supramolecular layers in the bc plane.

Effect of cerium (IV) ions on the anticorrosion properties of siloxane-poly(methyl methacrylate) based film applied on tin coated steel

This work investigates the influence of the addition of cerium (IV) ions on the anticorrosion properties of organic-inorganic hybrid coatings applied to passivated tin coated steel. In order to evaluate the specific effect of cerium (IV) addition on nanostructural features of the organic and inorganic phases of the hybrid coating, the hydrolytic polycondensation of silicon alkoxide and the radical polymerization of the methyl methacrylate (MMA) function were induced separately. The corrosion resistance of the coatings was evaluated by means of linear polarization, Tafel type curves and electrochemical impedance measurements. The impedance results obtained for the hybrid coatings were discussed based on an electrical equivalent circuit used to fit the experimental data. The electrochemical results clearly showed the improvement of the protective properties of the organic-inorganic hybrid coating mainly when the cerium (IV) was added to the organic phase solution precursor, which seemed to be due to the formation of a more uniform and densely reticulated siloxane-PMMA film. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of acibenzolar-S-methyl and Saccharomyces cerevisiae on the activation of Eucalyptus defences against rust

Tree defence mechanisms against the fungus Puccinia psidii were examined by comparing the activities of defence-related enzymes (chitinase, peroxidase and phenylalanine ammonia-lyase) of two Eucalyptus grandis x E. urophylla (urograndis) hybrids, previously classified as either susceptible to rust (VR hybrid) or moderately resistant to rust (C0 hybrid). Furthermore, the potential of disease control by artificial activation of host defences using either acibenzolar-S-methyl (ASM) or Saccharomyces cerevisiae extract was also investigated. Greenhouse inoculation trials revealed that the C0 hybrid had lower disease severity than the VR hybrid but following foliar applications of either ASM or S. cerevisiae extract treatment, disease severity (evaluated at 15 days after inoculation) was reduced in both hybrids. This enhanced resistance was associated with the induction of a hypersensitive reaction which appeared to be effective in controlling rust in both clones. The activity of all enzymes differed between clones and inducer treatment. The role of the defence-related enzymes in imparting resistance to eucalypt hybrids against rust is discussed.

A Survey for Diclofop-Methyl Resistance in Italian Ryegrass from Tennessee and How To Manage Resistance in Wheat

Italian ryegrass resistance to diclofop has been documented in several countries, including the United States. The purpose of this research was to screen selected putative resistant populations of Italian ryegrass for resistance to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides diclofop and pinoxaden and the acetolactate synthase (ALS)-inhibiting herbicides imazamox, pyroxsulam, and mesosulfuron in the greenhouse and to use field experiments to develop herbicide programs for Italian ryegrass control. Resistance to diclofop was confirmed in eight populations from Tennessee. These eight populations did not show cross-resistance to pinoxaden. One additional population (R1) from Union County, North Carolina, was found to be resistant to both diclofop and pinoxaden. The level of resistance to pinoxaden of the R1 population was 15 times that of the susceptible population. No resistance was confirmed to any of the ALS-inhibiting herbicides examined in this research. Field experiments demonstrated PRE Italian ryegrass control with chlorsulfuron (71 to 94%) and flufenacet + metribuzin (84 to 96%). Italian ryegrass control with pendimethalin applied PRE or delayed preemergence (DPRE) was variable (0 to 85%). POST control of Italian ryegrass was acceptable with pinoxaden, mesosulfuron, flufenacet + metribuzin, and chlorsulfuron + flucarbazone (> 80%). Application timing and herbicide treatment had no effect on wheat yield, except for diclofop and pendimethalin treatments, in which uncontrolled Italian ryegrass reduced wheat yield.