Low-temperature heat capacities of 1-alkyl-3-methylimidazolium bis(oxalato)borate ionic liquids and the influence of anion structural characteristics on thermodynamic properties.

Two chelated orthoborate ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(oxalato)borate ([Bmim][BOB]) and 1-hexyl-3-methylimidazolium bis(oxalato)borate ([Hmim][BOB]), were prepared and characterized. Their thermodynamic properties were studied using adiabatic calorimetry and differential scanning calorimetry (DSC). The thermodynamic properties of the two ILs were evaluated and compared with each other, and then with those of other [Bmim] type ILs. The results clearly indicate that for a given cation (or anion) and at a certain temperature, the more atoms in the anion (or cation), the higher the heat capacity; the higher glass-transition temperatures of [BOB] type ILs than others are mainly caused by the higher symmetry of the orthoborate anion structure. It is suggested that a high content of strong electronegative atoms and C(n) or C(nv) (n = 1,2,3,…,∞) point group symmetry in the anion are favorable for the design and synthesis of room temperature ILs with a wide liquid range.

[The influence of different alkaline pH conditions on Enterococcus faecalis in planktonic and biofilm mode].

PURPOSE: To study the influence of different pH conditions on Enterococcus faecalis(E. faecalis) in planktonic and biofilm mode. METHODS: E. faecalis were prepared in planktonic and biofilm mode and cultured in TSB mediums 2 hours at pH 7,8,9,10,11 and 12. MTT assays were applied to evaluate the survival rate of bacterial cells in different pH value. SAS 6.12 software package was used for statistical analysis. RESULTS: Mild alkaline mediums (pH7-9) had no effect on cell vitality of E. faecalis and high alkaline condition (pH>10) led to significant declines of survival rate of cells. The biofilm cells of E. faecalis were more alkaline tolerant than corresponding planktonic cells. CONCLUSION: Biofilm formation is an important step in the development of alkaline tolerance of E. faecalis.

[Quantitative evaluation of residual endodontic microorganisms after mechanical root canal preparation different chemical preparations by real-time PCR].

PURPOSE: To establish a quick, sensitive method for quantifying root canal flora and investigate the effects of different root canal preparations on the pathogenic bacteria at RNA level. METHODS: A total of 24 single-rooted teeth with chronic apical periodontitis were selected and prepared using 3% H2O2 combined with 1% NaClO, EDTA combined with 3% H(2)O(2),1% NaClO, respectively,the samples were taken before and after root canal preparation. After isolation of total RNA from the root canal samples, cDNA was synthesized by reverse transcription, and detected by real-time PCR. The data were analyzed with SAS 6.12 software package. RESULTS: The number of bacteria in the root canal reduced dramatically after mechanical preparation and irrigated using 3% H(2)O(2) and 1% NaClO(P<0.01). Further combined with EDTA, its effect was better than that of simply irrigated using 3% H(2)O(2) and 1% NaClO(P<0.05). CONCLUSIONS: Real-time PCR can be employed in the identification of bacteria flora in the root canal, both methods of root canal preparation can effectively reduce the number of bacteria flora.

[Quantitive study of interleukin 1beta in periapical exudates of chronic periapical periodontitis in the course of root canal therapy].

PURPOSE: To evaluate the relationship between IL-1beta and clinical findings of chronic apical periodontitis and to explore the function of IL-1beta during the endodontic interappointment flare-ups. METHODS: Periapical exudates samples were obtained from 19 teeth suffering from endodontic flare-ups after root canal preparation and 20 teeth without any symptoms and signs at the second visit after root canal preparation. The levels of IL-1beta were determined by ELISA and the data was analyzed by SAS6.12 software package. RESULTS: Significantly higher levels of IL-1beta were found in periapical exudates from teeth suffering from endodontic flare-ups than that before canal preparation(P<0.001). The mean IL-1beta levels significantly decreased following the endodontic therapy if there were no symptom at the second visit (P<0.001). CONCLUSION: The level of IL-1beta in the exudates of root canals were related with the exist of infection which might take an active part in the occurrence of endodontic interappointment flare-up.