Physical-mechanical properties of panels produced with corn cob particles and different types and contents of adhesives

The objective of this research was to evaluate the best type and adequate content of adhesive in low density particleboards produced with corn cob, in addition to the chemical analysis of the particles. The adhesives used were urea-formaldehyde (UF) and phenol-formaldehyde (PF) distributed in three levels (6, 9 and 12%) on the dry mass of the particles and the nominal density was 0.60 g.cm-3. Regarding the water absorption and swelling properties, no significant differences were found between treatments. The mean value calculated for the IE 24 h was 37.07%, being above the minimum limit stipulated by the standard. The modulus of rupture (MOR) and modulus of elasticity (MOE), were influenced by the tested factors. All particleboards met the requirements of the standard norm. For internal adhesion there was a significant effect only for the type of adhesive factor, with the particleboards produced with PF showing the highest means. For the compression property there was no effect of the factors tested. In general, the dimensional stability of the particleboards was below the minimum required by the standard, but the mechanical properties met all requirements.

Receptor recognition by meningococcal type IV pili relies on a specific complex N-glycan

Bacterial infections are frequently based on the binding of lectin-like adhesins to specific glycan determinants exposed on host cell receptors. These interactions confer species-specific recognition and tropism for particular host tissues and represent attractive antibacterial targets. However, the wide structural diversity of carbohydrates hampers the characterization of specific glycan determinants. Here, we characterized the receptor recognition of type IV pili (Tfp), a key adhesive factor present in numerous bacterial pathogens, using Neisseria meningitidis as a model organism. We found that meningococcal Tfp specifically recognize a triantennary sialylated poly-N-acetyllactosamine–containing N-glycan exposed on the human receptor CD147/Basigin, while fucosylated derivatives of this N-glycan impaired bacterial adhesion. Corroborating the inhibitory role of fucosylation on receptor recognition, adhesion of the meningococcus on nonhuman cells expressing human CD147 required prior defucosylation. These findings reveal the molecular basis of the selective receptor recognition by meningococcal Tfp and thereby, identify a potential antibacterial target.

Perbedaan Sikap Keberagamaan Antara Masyarakat Islam dan Kristiani di Sumatera Utara dan Frankfurt Am Main Jerman

<p>This article seeks to reveal differences of religious attitudes between Muslim and Christian communities in North Sumatera and Frankfurt Am Main Germany. This article shows that the relation between Muslims and Christians can be understood to have taken place in two categories, positive and negative. Positive relation can be attested through integrating factors between the two religious communities, while negative relation can be attested through separating factors. In North Sumatera there exist local wisdoms which serve as adhesive factors of Muslim-Christian relation, such as the concept of ‘marga” among Batakese society. Meanwhile, pig either as food or as pet is regarded as a dividing factor together with fanaticism and exclusivism. In Germany, as majority group the Christians are tolerant towards Muslims due to the rule of law in the country. This tolerance becomes an adhesive factor, while mutual suspicion among both Muslims and Christians is raeagrded as dividing factor.</p>

Bond Strength of Adhesive Systems with Different Solvents to Dry and Wet Dentin

ABSTRACT Aim This study evaluates bond strength between dentin and composite using adhesives with different solvents to dry and wet dentin. Materials and methods Ninety bovine incisors were used; the vestibular surfaces were worn by the exposure of an area with a diameter of 4 mm of dentin. The specimens were divided into 6 groups, according to the type of adhesive used and hydratation stals: Group SB-wet: Single Bond 2 in wet dentin, Group SBdry: Single Bond 2 in dry dentin, Group SL-wet: Solobond M in wet dentin, Group SL-dry: Solobond M in dentin dry. Group XPwet: XP Bond in wet dentin, Group XP-dry: XP Bond in dentin dry. They were cut to obtain specimens in the shape of stick with 1 × 1 mm and subjected to microtensile test in universal testing machine with a cross speed of 1mm/min. The data were analyzed with ANOVA and Tukey's tests (5%). Results ANOVA showed significant differences for surface treatment and interaction, but no difference was found for adhesive factor. The Tukey's test showed that the samples with wet dentin shown higher values of bond strength. Conclusion The adhesive did not influence in the bond strength. The groups with wet dentin showed higher values of bond strength than groups with dry dentin. How to cite this article Silva MA, Rangel PM, Barcellos DC, Pagani C, Torres CRG. Bond Strength of Adhesive Systems with Different Solvents to Dry and Wet Dentin. J Contemp Dent Pract 2013;14(1):9-13.

Influence of Self-Etching Adhesive Systems on Restorative Material Surfaces

ABSTRACT This study evaluated the microhardness of restorative materials after the use of self-etching and acid-etching adhesives. Specimens were divided into four groups: Group 1 (CR): Composite resin, Group 2 (GIC): Glass ionomer cement chemically activated, Group 3 (EC): Dual resinous cement, Group 4 (E): Dual resinous cement. Each group was divided into three subgroups, according to the type of adhesive system applied on the surface: Subgroup 1 (C): Control subgroup, Subgroup 2 (XE): Xeno III self-etching adhesive, Subgroup 3 (SB): Single bond acid-etching adhesive. Vickers microhardness analysis was performed on the surfaces and the data were submitted to the two-way ANOVA and the Tukey's test. The means for the material factor: GIC: (35.61)a; CR: (43.54)b; E: (44.65)b; EC: (50.13)c. The means for the adhesive factor: SB: (36.35)a; XE: (38.44)a; C: (55.65)b. All materials tested showed a decrease in surface hardness after application of the adhesive systems, irrespective of the system. The lowest microhardness was shown by GIC and the highest by Enforce Core.

Staphylococcus aureus MazF Specifically Cleaves a Pentad Sequence, UACAU, Which Is Unusually Abundant in the mRNA for Pathogenic Adhesive Factor SraP

ABSTRACT Escherichia coli mRNA interferases, such as MazF and ChpBK, are sequence-specific endoribonucleases encoded by toxin-antitoxin (TA) systems present in its genome. A MazF homologue in Staphylococcus aureus (MazFSa) has been shown to inhibit cell growth when induced in E. coli. Here, we determined the cleavage site for MazFSa with the use of phage MS2 RNA as a substrate and CspA, an RNA chaperone, which prevents the formation of secondary structures in the RNA substrate. MazFSa specifically cleaves the RNA at a pentad sequence, U↓ACAU. Bioinformatics analysis revealed that this pentad sequence is significantly abundant in several genes, including the sraP gene in the S. aureus N315 strain. This gene encodes a serine-rich protein, which is known to play an important role in adhesion of the pathogen to human tissues and thus in endovascular infection. We demonstrated that the sraP mRNA became extremely unstable in comparison with the ompA mRNA only when MazFSa was induced in E. coli. Further bioinformatics analysis indicated that the pentad sequence is also significantly abundant in the mRNAs for all the pathogenic factors in S. aureus. This observation suggests a possible regulatory relationship between the MazEFSa TA module and the pathogenicity in S. aureus.

The Beat generation: a multigene family encoding IgSF proteins related to the Beat axon guidance molecule in Drosophila

A previous genetic screen led to the identification of the beaten path (beat Ia) gene in Drosophila. Beat Ia contains two immunoglobulin (Ig) domains and appears to function as an anti-adhesive factor secreted by specific growth cones to promote axon defasciculation. We identify a family of 14 beat-like genes in Drosophila. In contrast to beat Ia, four novel Beat-family genes encode membrane-bound proteins. Moreover, mutations in each gene lead to much more subtle guidance phenotypes than observed in beat Ia. Genetic interactions between beat Ic and beat Ia reveal complementary functions. Our data suggest a model whereby Beat Ic (and perhaps other membrane-bound family members) functions in a pro-adhesive fashion to regulate fasciculation, while Beat Ia (the original secreted Beat) functions in an anti-adhesive fashion to regulate defasciculation.