Effect of repair resin type and surface treatment on the repair strength of polyamide denture base resin.

The purpose of the present study was to evaluate the effects of different repair resins and surface treatments on the repair strength of a polyamide denture base material. Polyamide resin specimens were prepared and divided into nine groups according to the surface treatments and repair materials. The flexural strengths were measured with a 3-point bending test. Data were analyzed with a 2-way analysis of variance, and the post-hoc Tukey test (α=0.05). The effects of the surface treatments on the surface of the polyamide resin were examined using scanning electron microscopy. The repair resins and surface treatments significantly affected the repair strength of the polyamide denture base material (p<0.05); however, no significant differences were observed interaction between the factors (p>0.05). The flexural strength of the specimens repaired with the polyamide resin was significantly higher than that of those repaired with the heat-polymerized and autopolymerizing acrylic resins.

[Investigation on the process of sapindus saponin purified with macroporous adsorption resin and screening of its bacteriostasis].

OBJECTIVE: To study the technological parameters of the purification process of saponins with macroporous adsorption resin. METHODS: The adsorptive characteristics and elutive parameters of the process were studied by taking the elutive and purified ratio of saponins as markers. Bacteriostasis activity of each parts eluted was evaluated by the mean of cup-plate method. RESULTS: 13.6 mL of the extraction of sapindus saponin (crude drugs 0.01 g/mL) was purified with a column of macroporous adsorption resin (phi15 mm x H90 mm, dry weight 2.5 g) and washed with 3BV of distilled water, then eluted with 3BV of 30% ethanol and 3BV of 70% ethanol, most of saponins were collected in the 70% ethanol. CONCLUSION: With macroporous adsorption resin adsorbing and purifying, the elutive ratio of saponins was 93.8% and the purity reached 250.1%. So this process of applying macroporous adsorption resin to adsorb and purify saponins is feasible, and supplies reference to the purification of other types of saponin.

[Purification process of proanthrocyanidin from rapeseed with macroporous resins].

The characteristics of absoption and desorption of four classes (five kinds) of macroporous resins in the solution of rapeseed proanthrocyanidin were compared. The results indicated that the weak polar macroporous resins AB-8 and HPD450 were better than the other three macroporous resins in some characteristics of absorption and desorption. In this experiment, the purity of rapeseed proanthrocyanidin prepared only by AB-8 macroporous resin column was higher than only by HPD450 column. However,the yield was lower. Using two steps of purification (first HPD450 column and second AB-8 column) obtained better results. The yield and purity were 62. 5% and 84% ,respectively. After using mixed resin column (50% HPD450 and 50% AB-8), the yield and purity were 75.2% and 80.3%, respectively. The last results might be used in industry.

Preparation and infrared/raman classification of 630 spectroscopically encoded styrene copolymers.

The barcoded resins (BCRs) were introduced recently as a platform for encoded combinatorial chemistry. One of the main challenges yet to be overcome is the demonstration that a large number of BCRs could be generated and classified with high confidence. Here, we describe the synthesis and classification of 630 polystyrene-based copolymers prepared from the combinatorial association of 15 spectroscopically active styrene monomers. Each of the 630 copolymers displayed a unique vibrational fingerprint (infrared and Raman), which was converted into a spectral vector. To each of the 630 copolymers, a vector of the known (reference) composition was assigned. Unknown (prediction) vectors were decoded using multivariate data analysis. From the inner product of the reference and prediction vectors, a correlation map comparing 396 900 copolymer pairs (630 x 630) was generated. In 100% of the cases, the highest correlation was obtained for polymer pairs in which the reference and prediction vectors correspond to copolymers prepared from identical styrene monomers, thus demonstrating the high reliability of this encoding strategy. We have also established that the spectroscopic barcodes generated from the Raman and infrared spectra are independent of the copolymers' morphology (beaded versus bulk polymers). Besides the demonstration of the generality of the polymer barcoding strategy, the analytical methods developed here could in principle be extended to the investigation of the composition and purity of any other synthetic polymer and biopolymer library, or even scaffold-based combinatorial libraries.

Maximising tubing functionality, Part I: Proper selection of resins.

Making an incorrect selection of polymeric materials, formulations and compounding can result in a compromised design and impaired functionality of the end product. Part I of this article provides guidance on how to simplify and expedite materials selection.

A novel peptide synthesis using fluorous chemistry.

Three new fluorous supports for peptide synthesis, i.e., the trialkoxybenzhydryl-type (6), the Wang-type (7) and the tert-butyl-type support (8), were prepared. A bioactive peptide TRH was easily synthesized by an Fmoc strategy using the benzhydryl-type fluorous support with fluorous chemistry.

The clinical performance of adhesives.

OBJECTIVES: Traditional mechanical methods of retaining restorative materials have been replaced to a large extent by tooth conserving adhesive restorative techniques. Because adhesives have been evolving so rapidly for the last few years, the timing is right for evaluating the clinical status of present day adhesives. DATA SOURCES: Current literature with regard to the clinical performance of adhesives has been reviewed. An overview of currently available adhesive systems is provided and a categorization of these adhesives according to their clinical application procedure and their intended mechanism of adhesion is proposed. Parameters of direct relevance to the clinical effectiveness of adhesives are discussed in relation to the clinical effectiveness of today's adhesives. CONCLUSIONS: The clinical performance of present day adhesives has significantly improved, allowing adhesive restorations to be placed with a high predictable level of clinical success. Most modern adhesive systems are superior to their predecessors, especially in terms of retention that is no longer the main cause of premature clinical failure. Recent adhesives also appear less sensitive to substrate and other clinical co-variables. As the remaining major shortcoming of modern adhesives, none of these modern systems however appears yet to be able to guarantee hermetically sealed restorations with margins free of discoloration for a long time.

DOT-ELISA-IgM in saliva for the diagnosis of human leptospirosis using polyester fabric-resin as support: preliminary report

Com a finalidade de melhorar o diagnostico da leptospirose humana, padronizou-se o teste dot-ELISA para a pesquisa de anticorpos especificos da classe IgM na saliva. Empregaram-se amostras de saliva e soro coletadas simultaneamente de 20 pacientes com a forma icterohemorragica da doenca, de 10 pacientes com outras patologias e 5 controles negativos. Culturas de Leptospira em meio EMJH, dos sorovares: icterohaemorrhagiae, canicola, hebdomadis, brasiliensis e cynopteri, foram utilizadas como antigeno, na concentracao proteica individual de 0,2 ug/ul, misturadas em volumes iguais. Na fase solida do teste empregou-se tecido de poliester impregnado com resina de N-metilol-acrilamida....