История развития математических знаний

Isosorbide is a platform chemical of considerable importance for the future replacement of fossil resource-based products. Applications as monomers and building blocks for new polymers and functional materials, new organic solvents, for medical and pharmaceutical applications, and even as fuels or fuel additives are conceivable. The conversion of isosorbide to valuable derivatives by functionalization or substitution of the hydroxyl groups is difficult because of the different configurations of the 2- and 5-positions and the resulting different reactivity and steric hindrance of the two hydroxyl groups. Although a substantial amount of work has been published using exclusively the endo or exo derivatives isomannide and isoidide, respectively, as starting material, a considerable effort is still necessary to transfer and adapt these methods for the efficient conversion of isosorbide. This Minireview deals with all aspects of isosorbide chemistry, which includes its production by catalytic processes, special properties, and chemical transformations for its utilization in biogenic polymers and other applications of interest

A comparative photocatalytic study of TiO2 loaded on three natural clays with different morphologies

[EN] In this work, a sol-gel method was used to load TiO2 nanoparticles on three clays (kaolinite, halloysite and palygorskite) with different morphologies (plates, tubes, and rods with micro tunnels), and then the photocatalytic performance of obtained clay-TiO2 composites for degradation of methyl orange was comparatively investigated. The results surprisingly show that the trend of photocatalytic performance of composites is opposite to that of special surface area of corresponding clays. By concentrated analysis of the loading status of TiO2, the lowest photocatalytic efficiency of palygorskite-TiO2 composite is mainly ascribed to (1) the aggregation of TiO2 nanoparticles on Pal surface, not the amount of TiO2 and (2) the relatively weak adsorption of Pal to methyl orange. The additional adsorption of hydroxyl surface of Kaol to methyl orange and little TiO2 in the lumen of Hal tube leads to the better photocatalytic performance of kaolinite-TiO2 composite than halloysite-TiO2 composite. Finally, kaolinite is proved to be an excellent carrier to support nano TiO2 resulting in a good photocatalytic performance and cycle stability, and the study can provide a direct guidance to select appropriate clay-photocatalyst composites for different practical applications.This work is supported by the National Natural Science Foundation of China (41502032) and the Fundamental Research Funds for the Central Universities (2019XKQYMS76).Wu, A.; Wang, D.; Wei, C.; Zhang, X.; Liu, Z.; Feng, P.; Ou, X.... (2019). A comparative photocatalytic study of TiO2 loaded on three natural clays with different morphologies. Applied Clay Science. 183:1-12. https://doi.org/10.1016/j.clay.2019.105352S11218

Pd–Ce/ZIF-8 Nanocomposite for Catalytic Extraction of Sinomenine from Sinomenium acutum

Sinomenine is a naturally occurring alkaloid and commonly used as one of the bioactive drug components in rheumatoid arthritis (RA) treatment in the clinic. Varying supported palladium-based catalysts have been synthesized and examined as heterogeneous catalysts for catalytic extraction of sinomenine from Sinomenium acutum. Among various examined supported catalysts, Pd–Ce/ZIF-8 (zeolitic imidazolate framework-8) demonstrates promising catalytic activity in the extraction reaction with an improved yield of 2.15% under optimized conditions. The catalyst composite can be recovered by centrifuging, and reused. A total of three catalyst recycling processes were performed with constant activity. The catalyst Pd–Ce/ZIF-8 has a particle size range of 2–12 nm and a total Pd–Ce loading amount of 5.1 wt% (ZIF-8)

Study on the second personalized chair ⁃ side education to change the knowledge, attitude, and practice of patients with periodontitis

Objective To explore the application effect of secondary personalized chairside education on changing the knowledge and behavior of patients with oral periodontal disease. Methods A total of 124 patients experiencing initial periodontal disease were selected. Sixty⁃two patients were observed in the observation group, and 62 patients were observed in the control group. After the doctor checked and determined the periodontal condition of the patients, the nurse conducted a targeted, personalized secondary one⁃on⁃one chairside mission for the observation group; in the control group, the nurses provided routine one⁃to⁃one health education to the patients before treatment. Statistical analysis was conducted to assess periodontal knowledge mastery, self ⁃ care behaviors, rate of return for periodontal treatment and patient satisfaction after 3 months. The plaque index and scale index were statistically analyzed before and 3 months after treatment. Results No statistical difference was found in the general data between the two groups of patients (P > 0.05); however, the degree of mastery of periodontal knowledge in the observation group was higher than that in the control group. The degrees of mastery of the clinical manifestations, hazards and treatment methods were 96.7% , 93.5% , and 91.9% in the observation group and 72.5% , 48.3% , and 69.3% in the control group, respectively; the difference was statistically significant (P < 0.05). The patients in the observation group were more likely than those in the control group to brush more than 2 times daily, use dental floss and use an interdental brush; 100%, 96.7%, and 77.4% of patients in the observation group and 80.6%, 56.4%, and 40.3% of patients in the control group participated in these oral health care behaviors, respectively. The difference was statistically significant (P < 0.05). The rate of recovery and patient satisfaction were higher in the observation group than in control group at 3 months; the rate of recovery and patient satisfaction were 80.6% and 96%, in the observation group and 41.9% and 88.7% in the control group, respectively. The difference was statistically significant (P < 0.05). After 3 months, the plaque index in the observation group was lower than that in the control group (1.71 ± 1.12, 2.35 ± 0.78), and the difference was statistically significant (P < 0.05). Conclusion Secondary personalized chairside education can significantly improve the patient s cognition of the disease, allow the formation of accurate oral health awareness, and change the patients bad oral hygiene habits and medical behavior. Thus, this method is an effective oral health education method and can change the knowledge and beliefs of patients with oral periodontitis

Production of Terephthalic Acid from Lignin-Based Phenolic Acids by a Cascade Fixed-Bed Process

Vanillic acid and syringic acid were converted to terephthalic acid via a two-step process using a fixed-bed reactor. The cascade route includes hydrogenation demethoxylation and carboxylation reactions. Activated carbon (AC)-supported MoWBO_<i>x</i> and PdNiO_<i>x</i> were determined to be suitable catalyst precursors for the process. An intermediate of <i>p</i>-hydroxybenzoic acid (HBA) was produced from the demethoxylation in 71.6% selectivity, and the terephthalic acid was obtained in 58.7% yield with 66.4% HBA conversion