Evaluation of a novel primer containing isocyanate group on dentin bonding durability.

OBJECTIVES: To evaluate the benefits of a novel dentin-bonding primer, namely, isocyanate-terminated urethane methacrylate precursor (UMP), which can form covalent bonds with demineralized dentin collagen. METHODS: The synthesized and purified UMP monomer was characterized and tested its effects on the degree of conversion (DC) and wettability of an acetone-based dental adhesive. Then UMP primers of different concentrations were formulated and used to prepare adhesive specimens, which were compared with solvent-treated groups. Primer-treated specimens with and without aging were also compared. To evaluate the bonding interface, microtensile strength tests, nano-indentation tests and nanoleakage- eavaluation were performed using a field-emission scanning electron microscope and nano-indenter. Data were analyzed using SPSS 20.0 software with significance set at α = 0.05 using one-way analysis of variance (ANOVA) and two-way ANOVA to characterize the effects of the primer. RESULTS: Treatment with the UMP primer promoted the DC and wettability of the adhesive on the demineralized dentin surface (P < 0.05); it also increased the bond strength of the aged dentin bonding interface (P < 0.05). Nanoleakage was reduced; the bonding interface became more stable, and the continuity and strength of the hybrid layer improved (P < 0.05) following UMP treatment. The application of 5 mM UMP as a primer for dentin bonding could lead to a stable bonding interface and long-lasting bonding effects. SIGNIFICANCE: The use of 5 mM UMP primer developed in this study could improve dentin bonding durability and has excellent clinical application prospects.

Cryopreservation of mango (Mangifera indica L.) embryogenic cultures.

Three techniques were compared for cryopreserving embryogenic masses (EMs) sampled from mango (Mangifera indica L.) cv. Zihua embryogenic cultures: (i) encapsulation/dehydration; (ii) pregrowth/dehydration; and (iii) vitrification. In all experiments, EMs were sampled from embryogenic cultures during their exponential growth phase and pretreated for 24 h on solid medium containing 0.5 M sucrose before freezing. No recovery was achieved after cryopreservation using the encapsulation/dehydration technique, whatever the moisture content (fresh weight basis) of EMs, which ranged from 78.3% without dehydration to 40.8% after 6 h dehydration. With the pregrowth plus dehydration technique, limited recovery (8.3%) was achieved after desiccation of EMs for 1 h, to 58.5% MC. Using the vitrification technique, recovery ranged from 94.3% after treatment of EMs with the PVS3 vitrification solution for 20 min (EM moisture content of 34.7%) to 10.9% after a 120 min treatment with the vitrification solution (EM moisture content of 26.0%).

[Genetic diversity and differentiation of Fagopyrum tataricum and its related species in China].

Genetic diversity and differentiation among 50 populations of total 8 species and 1 variety of Fagopyrum tataricum and its related species from 27 counties of Sichuan and Yunnan provinces, Southwest China were investigated using allozyme electrophoresis. Seven enzymesat 12 loci were assessed. The result shows that among 8 species and 1 variety, inbreeding coefficient is -0.54(-)-0.80, which means hterozogote excess. Higher genetic diversity was found in the wild related species of F. tataricum than in F. tataricum. F. dibotrys has the highest Fst value, which means that more genetic variations exist among its populations. The lowest Fst value shows that less genetic variations exist among population of F. gracilipes whic is close to panmictic There is almost no genetic differentiation between populations of F. statice. Genetic similarity is 55.3%-65.2% between species of F. tataricum and its related species, which is close to the average level among species in seed plants. According to the cluster analysis of genetic similarity, F. gracillipes is most close to F. tataricum and F. esculentum. Jinsha River region is the distributional and original center of F. tataricum and its related species.