[Contamination Characteristics and Source Apportionment of Potentially Toxic Elements in Soil around the Coal-fired Power Plant Using APCS-MLR and PMF Models].

To investigate the characteristics and sources of potentially toxic elemental contamination in soils around the coal-fired power plant, we selected the soil around the Jingyuan power plant as the object of investigation. Thirty-six and 27 soil samples collected from the urban and farmland areas were analyzed for PTEs (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn), respectively. We employed the geoaccumulation index, single-factor pollution index, and improved Nemerow integrated pollution index to evaluate the contamination characteristics of PTEs, and combined correlation analysis with absolute principal component scores-multiple linear regression (APCS-MLR) and positive matrix factorization (PMF) receptor models were used to quantitatively analyze the pollution sources of PTEs. The results revealed that all the average concentrations of other soil metals around Jingyuan power plant exceeded their corresponding background values of Gansu Province, except for As, in agricultural soil, and Hg exhibited significant spatial non-homogeneity, and thus it was visibly affected by anthropogenic activities. The values of the single-factor pollution and geoaccumulation indices indicated that the soils of both sites were mainly contaminated with Cd, Cr, Ni, and Pb, and Hg contamination was reflected in wide areas for both sites. Additionally, the results of the improved Nemerow index demonstrated that the investigated soil was between moderately contaminated and heavily contaminated. Further, the comprehensive pollution degree of urban soil was higher than that of agricultural soil. Moreover, source apportionment revealed that PTEs in urban soil were derived from mixed sources of traffic activities and coal combustion, mixed sources of traffic activities and industrial and mining activities, and atmospheric deposition from industrial activities, with contribution rates of APCS-MLR of 35.2%, 25.1%, and 23.4%, respectively. The PMF contribution rates were 40.2%, 12.4%, and 47.7%, respectively. PTEs in agricultural soil were from one mixture source of industrial, mining, agricultural, and traffic sources, and the other mixed source was of traffic activities and coal combustion, with a APCS-MLR contribution rate of 40.3% and 35.9% and a contribution rate of PMF of 36.2% and 18.0%, respectively. In addition, another mixed source of agricultural activities and coal combustion was obtained using the PMF model, with a contribution rate of 48.5%.

[Spatial Distribution Characteristics and Source Analysis of Heavy Metals in Urban River Surface Sediments from the Lanzhou Reach of the Yellow River].

In order to investigate the contamination characteristics and potential sources of heavy metals from the urban river surface sediments in the Yellow River Basin, we selected the Lanzhou reach of the Yellow River as the object of investigation. A total of 46 surface sediment samples were collected along the Lanzhou reach of the Yellow River, and the contents of eight heavy metals, Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb, were determined by using inductively coupled plasma mass spectrometry and an atomic fluorescence spectrometer. Contamination indexes including single factor pollution index (Pi) and geo-accumulation index (Igeo), together with the sediment pollution index (SPI), were used to assess heavy metal pollution characteristics and ecological risk levels in the urban river surface sediments of the Lanzhou reach of the Yellow River. Pearson's correlation analysis (CA), positive matrix factorization (PMF), and principal component analysis/absolute principal component score (PCA/APCS) were jointly employed to quantitatively analyze pollution sources of heavy metals. The results showed that the mean concentrations of the majority of heavy metals exceeded their corresponding background values of Gansu Province and Lanzhou City with the exception of As, and the spatial distribution of high concentrations of heavy metals was mainly concentrated in the corner of the river. Based on the single factor pollution and geo-accumulation indexes of the eight heavy metals, in the Lanzhou reach of the Yellow River, Cr was the dominant pollution element in the urban river surface sediments, followed by Cd and Ni. Additionally, the SPI values for the eight heavy metals in the surface sediments ranged from 0.48 to 8.56, presenting natural to low ecological risk level. Furthermore, source apportionment revealed that a mixture source of industrial and agricultural activities (77.6%) was the largest contributor of Cr, Ni, Zn, As, Cd, and Pb in the urban river surface sediments, followed by natural sources (11.4%) and a mixed source of industrial and traffic activities (11%).

[Evaluation on application of 3D printing digital positioning guide in root canal retreatment].

PURPOSE: To explore the application of 3D printing digital positioning guide in root canal retreatment. METHODS: Eighty-two isolated teeth collected in Chifeng College Affiliated Hospital from January 2018 to December 2021 were selected, and divided into experimental group and control group by random number table method, with 41 teeth in each group. Both groups were given root canal retreatment. The control group underwent traditional pulpotomy, while the experimental group underwent precise pulpotomy under 3D printing digital positioning guide. The damage of the coronal prosthesis caused by pulpotomy was compared between the two groups, the time of pulpotomy was recorded, removal of root canal fillings in the two groups was counted, fracture resistance of the tooth tissue in the two groups was compared, and the incidence of complications in the two groups was recorded. SPSS 18.0 software package was used for statistical analysis of the data. RESULTS: The ratio of pulp opening area to total dental and maxillofacial area in the experimental group was significantly lower than that in the control group (P＜0.05). The pulp opening time in the experimental group was lower than that in the control group(P＜0.05), and the root canal preparation time in the experimental group was significantly higher than that in the control group(P＜0.05). There was no significant difference in the total time between pulp opening and root canal preparation between the two groups(P＞0.05). The removal rate of root canal filling in the experimental group was higher than that in the control group (P＜0.05). The failure load value of the experimental group was significantly higher than that of the control group (P＜0.05). There was no significant difference in the incidence of total complications between the two groups (P＞0.05). CONCLUSIONS: Application of 3D-printed digital positioning guides in root canal retreatment can achieve precise and minimally invasive pulp opening, reduce damage to coronal restorations, preserve more dental tissue, and improve the removal efficiency of root canal fillings and the fracture resistance of dental tissue, as well as performance, safety and reliability.

[Effect of individualized healing abutment on patients with posterior implant prosthesis and improvement of food impaction symptoms].

PURPOSE: To observe the effect of individualized healing abutment on patients with posterior dental implant prosthesis and its influence on implant stability and food impaction. METHODS: Eighty patients who received posterior dental implants in Jiangsu Stomatological Hospital from June 2013 to June 2018 were selected as the study subjects. According to the different healing abutment, they were divided into traditional operation group (40 cases) and experimental group (40 cases). Patients in the experimental group used personalized healing abutment on the basis of traditional dental implants. Differences in dental implant stability, food impaction score, masticatory efficiency and incidence of complications between the two groups after implant restoration were compared. SPSS 13.0 software package was used to analyze the data. RESULTS: At 1, 3 and 6 months after operation, the stability of implants in the experimental group was significantly higher than that in the control group (P<0.01); One, 3 and 6 months after operation, the food impaction score in the experimental group was significantly lower than that in the traditional operation group(P<0.01); There was no significant difference in masticatory ability between the two groups before operation; After treatment, the occlusive force and masticatory efficiency in the experimental group were significantly higher than those in the traditional operation group (P<0.05). The incidence of complications such as tooth loosening and periodontitis in the experimental group was significantly lower than in the traditional operation group (P<0.05). CONCLUSIONS: Individualized healing abutment has a good therapeutic effect on patients with posterior implant prosthesis, and can significantly improve the incidence of food impaction and complications with a good application value.

In Vitro and in Vivo Antitumor Effects of Plant-Derived Miliusanes and Their Induction of Cellular Senescence.

Our earliest phytochemical separation of Miliusa sinensis aided us in the isolation of a class of unique miliusanes, which were demonstrated as anticancer lead molecules. In the present study, we isolated 19 miliusanes (1-19), including 11 novel ones (5 and 10-19) from another Miliusa plant ( M. balansae), and synthesized additional derivatives to elucidate the structure-activity relationship of miliusanes. When extrapolated to various carcinoma xenograft mouse models, miliusol (1) and its derivatives 20, 26, and 27 (7.5-40 mg/kg) were demonstrated with tumor inhibitory efficacy comparable or even superior to the mainstay chemotherapeutics paclitaxel or fluorouracil. To gain a molecular insight into their anticancer mechanism, 1-3 (GI50 0.03-4.79) were administered to a wide spectrum of human cancer cell lines, including those with specific drug resistance. We further revealed that the antiproliferative properties of miliusanes in carcinoma cells were highly associated with the p21-dependent induction of cellular senescence.

Antimalarial Activity of Plant Metabolites.

Malaria, as a major global health problem, continues to affect a large number of people each year, especially those in developing countries. Effective drug discovery is still one of the main efforts to control malaria. As natural products are still considered as a key source for discovery and development of therapeutic agents, we have evaluated more than 2000 plant extracts against Plasmodium falciparum. As a result, we discovered dozens of plant leads that displayed antimalarial activity. Our phytochemical study of some of these plant extracts led to the identification of several potent antimalarial compounds. The prior comprehensive review article entitled “Antimalarial activity of plant metabolites” by Schwikkard and Van Heerden (2002) reported structures of plant-derived compounds with antiplasmodial activity and covered literature up to the year 2000. As a continuation of this effort, the present review covers the antimalarial compounds isolated from plants, including marine plants, reported in the literature from 2001 to the end of 2017. During the span of the last 17 years, 175 antiplasmodial compounds were discovered from plants. These active compounds are organized in our review article according to their plant families. In addition, we also include ethnobotanical information of the antimalarial plants discussed.

Design, synthesis and evaluation of novel dihydrostilbene derivatives as potential anti-melanogenic skin-protecting agents.

The stems of Dendrobium orchids (Orchidaceae), also known as Shi Hu, have been used for medicinal purposes for centuries in oriental countries. In fact, the health benefits of Shi Hu have been evidenced by its modern pharmacological actions on conquering oxidative stress in pathological conditions. From the extracts of two commonly used Dendrobium species, we obtained discernible amounts of stilbenoids, explicitly trans-resveratrol (1) and dihydro-resveratrol (2), which are prototypical antioxidants. When applied to cultured melanocytes, these stilbenoids, dihydro-resveratrol (2) in particular, significantly reduced melanin formation via inhibiting tyrosinase activity and expression of tyrosinase-related proteins. By utilizing dihydro-resveratrol (2) as the basic structural unit, we synthesized 11 novel dihydrostilbene derivatives (3-13) in good yields and purity, with manipulative steps. In addition to their anti-melanogenic activity, some of the novel derivatives are indeed potential antioxidants as they quenched intracellular oxidative radicals in a manner more efficient than Trolox, a water-soluble analogue of vitamin E, and thus premeditated beneficial to skin protection.