Real-Time Monitoring and Quantitative Evaluation of Resin In-Filtrant Repairing Enamel White Spot Lesions Based on Optical Coherence Tomography.

The aim of the present study was to explore the feasibility of real-time monitoring and quantitative guiding the repair of enamel white spot lesions (WSLs) with resin infiltration by optical coherence tomography (OCT). Seven New Zealand rabbits were treated with 37% phosphoric acid etchant for 15 min to establish the model of enamel demineralization chalk spots of upper incisors, which were repaired by Icon resin infiltrant. OCT, stereo microscope (SM) imaging, scanning electron microscope (SEM) imaging and hematoxylin eosin (HE) staining were used to image each operation step. The changes of WSLs of enamel before and in the process of restoration with resin infiltrant showed specific performance in OCT images, which were consistent with the corresponding results of stereomicroscope and SEM. OCT can non-invasively and accurately image the whole process of repairing enamel demineralization layer with resin infiltration real-time, which can effectively guide the clinical use of resin infiltrant to repair enamel WSLs and be used as an imaging tool to evaluate the process and effect of restoration with resin infiltrant at the same time.

Weak Bonds Joint Effects Catalyze the Cleavage of Strong C-C Bond of Lignin-Inspired Compounds and Lignin in Air by Ionic Liquids.

Oxidation of lignin to value-added aromatics through selective C-C bond cleavage via metal-free and mild strategies is promising but challenging. It was discovered that the cations of ionic liquids (ILs) could effectively catalyze this kind of strong bond cleavage by forming multiple weak hydrogen bonds, enabling the reaction conducted in air at temperature lower than 373 K without metal-containing catalysts. The cation [CPMim]+ (1-propylronitrile-3-methylimidazolium) afforded the highest efficiency in C-C bond cleavage, in which high yields (>90 %) of oxidative products were achieved. [CPMim]+ could form three ipsilateral hydrogen bonds with the oxygen atom of C=O and ether bonds at both sides of the C-C bond. The weak bonds joint effects could promote adjacent C-H bond cleave to form free radicals and thereby catalyze the fragmentation of the strong C-C. This work opens up an eco-friendly and energy-efficient route for direct valorization of lignin by enhancing IL properties via tuning the cation.

Highly Efficient Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid with Heteropoly Acids and Ionic Liquids.

2,5-Furandicarboxylic acid (FDCA) is regarded as an important bioderived substitute for petrochemically derived terephthalic acid (PTA), which is widely applied in the polymer industry. This work delineates the base-free oxidation of 5-hydroxymethylfurfural (HMF) to FDCA in an ionic liquid/heteropoly acid (IL-HPA) catalytic system. HPAs displayed high activity for selective oxidation; their active center (Mo/V) was activated by O2 and transformed from oxygen single and double bonds to epoxy groups, resulting in an FDCA yield of 89 % for HPMV6 (HPM=H3 PMo12 O40 ) in the presence of [Bmim]Cl (1-butyl-3-methylimidazolium chloride) under optimized reaction conditions. The high solubility of imidazole ILs for FDCA improved the affinity of HMF and the active centers of the catalyst and protected the furan ring from oxidative cleavage. Furthermore, multiple hydrogen bonds simultaneously formed between the electronegative anions and hydroxy protons of HMF, as well as the hydrogen atoms of the imidazole rings and hydroxy groups, promoting the transformation to aldehyde groups. Various starting materials were studied, and a moderate FDCA yield was obtained from glucose. This work provides an interesting IL-HPA catalytic system for the base-free synthesis of FDCA from accessible monosaccharides and illustrates the great potential of FDCA production from renewable carbohydrates.

A Simple and Mild Approach for the Synthesis of p-Xylene from Bio-Based 2,5-Dimethyfuran by Using Metal Triflates.

The production of aromatic platform chemicals from biomass-derived feedstocks is of considerable importance in biomass conversion. However, the development of effective routes with simple steps and under mild conditions is still challenging. In this work, we report an original route for the direct synthesis of p-xylene from 2,5-dimethylfuran and acrylic acid catalyzed by scandium(III) triflate (Sc(OTf)3 ) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim]NTf2 ) under mild conditions. An overall 63 % selectivity towards p-xylene and 78 % selectivity towards aromatics were obtained at 90 % conversion of 2,5-dimethylfuran by enhancing the dehydration and introducing an extra one-pot decarboxylation step. Furthermore, various dienes and dienophiles were employed as reactants to extend the substrate scope. The aromatic compounds were obtained in moderate yields, which proved the potential of the method to be a generic approach for the conversion of bio-based furanics into renewable aromatics.

Preparation of nanoscale Ni-B amorphous alloys and their application in the selective hydrogenation of cinnamic acid.

A series of metal modified nanoscale Ni-B amorphous alloys was prepared by chemical reduction and tested in the selective hydrogenation of cinnamic acid. A Co modified Ni-B amorphous alloy (Ni-Co-B) exhibited excellent catalytic performance in this reaction with both 100.0% conversion of cinnamic acid and 100.0% selectivity for hydrocinnamic acid under the optimized reaction conditions. X-ray diffraction (XRD) results indicated that the addition of Co had not changed the amorphous structure of Ni-B; whereas, its addition was believed not only to favor decreased agglomeration of the active Ni species, as proven by transmission electron microscopy (TEM), but also to contribute to adsorption of hydrogen itself. Thus, Ni-Co-B showed a larger BET surface area, smaller particle size, and greater number of active species resulting in optimum H2-chemisorption compared to Ni-B and accounting for its excellent catalytic performance in cinnamic acid hydrogenation.

[Study on the method for rapid detection of Mycobacterium tuberculosis by phage amplified biologically assay].

OBJECTIVE: To set up a method for rapid detection of Mycobacterium tuberculosis (MTB) by phage amplified biologically (PhaB) assay and to investigate the optimal test condition. METHODS: Various test conditions were compared in order to observe the influence on detective results after MTB was infected by Mycobacteriophage. The test condition established was used for detection of sputum samples, and the results were compared with BIOTEC Lab test. RESULTS: The bacterial concentration of MTB in 200 - 500/ml was detected by PhaB assay at 1 x 10(9) plaque forming unite (PFU)/ml of Mycobacteriophage, 37 degrees C for 60 min. The optimal concentration of virucidal for inactivation of Mycobacteriophage was 100 mmol/ml for 5 min at room temperature. The bacteriolytic plaque was clear at the concentration of 1 x 10(8)/ml indicator cells. Bacterium inactivated by heat can not be infected by Mycobacteriophage. Positive result was observed for control strains of H(37)Rv, H(37)Ra and M. bovis while negative result was obtained for 7 strains of non-Mycobacterium and 16 control strains of non-Tuberculosis Mycobacteria (NTM). The 4 strains of NTM (M. fortuitum, M. intrcellulare, M. aurum, M. phlei) showed positive reaction at higher concentrations (> 1 x 10(5)/ml). The repetition test showed that the differentiation coefficient in batch and inner was all under 15%. There was a significantly difference (P < 0.01) in positive rate between two digestion-decontamination procedure with N-acetyl-cysteine-NaOH liquefacient (94%) and NaOH liquefacient (62%). The positive rate of the samples cultured one day (65%) was significantly higher than that of the samples without preculture (40%). The results for detection of clinical samples by two reagents, ours and BIOTEC Lab, were nearly the same. CONCLUSION: Because its rapidity, simplicity, and sensitivity, PhaB assay can be used for rapid detection of MTB, but the condition of test is very important.