Mechanism of highly efficient oil removal from spent hydrodesulfurization catalysts by ultrasound-assisted surfactant cleaning methods.

The removal of crude oil from spent hydrodesulfurization catalysts constitutes the preliminary stage in the recovery process of valuable metals. However, the traditional roasting method for the removal exhibits massive limitations. In view of this, the present study used an ultrasound-assisted surfactant cleaning method to remove crude oil from spent hydrodesulfurization catalysts, which demonstrated effectiveness. Furthermore, the study investigated the mechanism governing the process with calculation and experiments, so as to provide a comprehensive understanding of the cleaning method's efficacy. The surfactant selection was predicated on the performance in the IFT test, with SDBS and TX-100 finally being chosen. Subsequent calculations and analysis were then conducted to elucidate their frontier molecular orbitals, electrostatic potential, and polarity. It has been found that both SDBS and TX-100 possess the smallest LUMO-HOMO energy gap (ΔE), registering at 4.91 eV and 4.80 eV, respectively, and presenting the highest interfacial reactivity. The hydrophilic structure in the surfactant regulates the wettability of the oil-water interface, and the long-chain alkanes have excellent non-polar properties that promote the dissolution of crude oil. The ultrasonic-assisted process further improves the interface properties and enhances the oil removal effect. Surprisingly, the crude oil residue was reduced to 0.25% under optimal conditions. The final phase entailed the techno-economic evaluation of the entire process, revealing that, in comparison to the roasting method, this process saves $0.38 per kilogram of spent HDS catalyst, with the advantages of operational simplicity and emission-free. Generally, this study shed new light on the realization of efficient oil removal, with the salience of green, sustainable, and economical.

Fluorine removal from sodium tungstate ion exchange effluent by precipitation with addition of lanthanum chloride.

The waste water generated from the sodium tungstate ion exchange process of scheelite hydrometallurgical extraction contains a certain concentration of fluorine ion, which caused environmental pollution and harmed human health. In this study, a new method for removing fluorine from the wastewater by precipitation with addition of lanthanum chloride was proposed. In the process, fluorine was removed by from the solution as insoluble lanthanum fluoride precipitates. To explore the favourable conditions for the formation of lanthanum fluoride, thermodynamic analysis of the La-F-H2O system was conducted. Results show that lanthanum fluoride is stable when the solution pH value is between 1.0 and 10.0, and the lanthanum fluoride is gradually converted into lanthana hydroxide when the pH value is more than 10.0 at 298K. The effects of various parameters on the fluorine removal were studied, and the optimum process parameters were determined. More than 92% of the fluorine can be removed when the concentration of fluorine in the solution ranged from 60 to 400 mg/L, the dosage of lanthanum chloride was 1.3 times of the theoretical amount, the pH value was 8.0 at 60°C for 30 min. After removing fluorine from the solution, the resiual fluorine concentrtion was lower than 10 mg/L, which could meet the requirement of national wastewater discharge.

Natural progression of periodontal diseases in Chinese villagers based on the 2018 classification.

BACKGROUND: Based on the 2018 classification, we aimed to determine the prevalence, distribution, and progression of periodontitis in the rural Chinese population without access to dental care. METHODS: In all, 404 subjects (28.7 ± 8.9 years, M:F = 182:222) were randomly enrolled in 1992 and re-called in 1996. With the new classification, the prevalence and distribution of stage, grade, and extent were characterized. Stage progression was compared with the progression of clinical attachment loss (CAL) and radiographic bone loss (RBL). RESULTS: At baseline, 94.1% villagers suffered from periodontitis, of whom 53.7% were in Stage III/IV. The prevalence of Stage III/IV increased from 18.2% in the age group of 15 to 24 years to 60.9% in 25 to 34-year-old group and 88.7% in the 35 to 44-year-old group. Significantly more Stage III/IV, generalized, and Grade C periodontitis were found in male villagers than female villagers. In 1996, the prevalence rate of periodontitis increased to 98.5%, with 80.0% in Stage III/IV. Further, 84.2% villagers presented with Grade C periodontitis based on longitudinal ΔCAL. The rate of progression (≥1 site with ΔCAL ≥3 mm) was 63.7%. Stage progression correlated significantly with CAL and RBL progression in Stage I/II, but this association was not found in Stage III/IV. Among subjects with disease progression in Stage III/IV, 90.4% shifted from localized to generalized cases. Furthermore, ceiling effects were observed in Stage III/IV. CONCLUSIONS: In villagers without access to dental care, 94.1% suffered from periodontitis, with more than half having Stage III/IV disease based on the 2018 classification. The majority cases presented with rapid periodontal progression. Although stage progression correlated significantly with CAL and RBL progression in Stage I/II, ceiling effects existed in Stage III/IV.

Natural 4-year periodontal progression of mandibular first molars in Chinese villagers based on radiographic records.

BACKGROUND: To report 4-year natural periodontal progression of mandibular first molars based on radiographic records in 15 to 44-year-old Chinese villagers. METHODS: In 1992 (N = 486) and 1996 (N = 413), panoramic radiographs were recorded. Tooth loss of mandibular first molars was calculated. Relative bone height (RBH), intrabony defect (IBD) depth, and furcation involvement (FI) were measured on 918 and 755 mandibular first molars in 1992 and 1996, respectively. The progression of the three parameters and their relationship with widened periodontal ligament space (WPDL) were analyzed. RESULTS: In 1992, of 31 lost mandibular first molars, 29 belonged to the 35- to 44-year age group. At 4-year follow-up, five of eight lost teeth belonged to the 35- to 44-year age group. RBH decreased from 83% in 1992 to 77% in 1996. RBH progression was significantly faster in the 25- to 34- and 35- to 44-year age groups than in the 15- to 24-year age group. The mean IBD depth was 2.81 ± 0.55 mm (n = 32) in 1992 and 3.70 ± 0.73 mm (n = 33) in 1996. Prevalence of FI increased from 20.8% to 27.4%. Teeth with WPDL showed greater RBH and IBD progression than those without WPDL (RBH: 12% ± 1% versus 6% ± 0.01%, P < 0.001; IBD depth: 0.31 ± 0.08 versus 0.01 ± 0.00 mm, P <0.001). FI-area progression in teeth with WPDL showed a trend of greater expansion than in those without WPDL (0.92 ± 0.18 versus 0.56 ± 0.11 mm2 , P = 0.051). CONCLUSIONS: Tooth loss mainly occurred in the 35- to 44-year age group. RBH progression was faster in the 25- to 44-year age group. WPDL was associated with progression of RBH, IBDs, and FI.

A 4-year prospective study of the progression of periodontal disease in a rural Chinese population.

OBJECTIVES: The natural progression of periodontitis in the Chinese population is not well researched. We investigated the progression of periodontal disease over 4 years in 15-44-year-old Chinese villagers with no access to regular dental care. METHODS: In 1992, 486 villagers were enrolled, and in 1996, 413 villagers were re-examined. Probing depth (PD) and clinical attachment level (CAL) were examined at six sites per tooth. Sites with ΔCAL ≥3 mm were defined as active sites. Cross-sectional and longitudinal analyses were performed using means and percentile plots. RESULTS: The mean CAL increased by 0.26 mm over 4 years. The incidence of periodontitis (at least one site with CAL ≥3 mm) was 8%. The incidence of periodontitis among those with no periodontal disease at baseline was 44.9%. Seventy-eight percent of the subjects had at least one active site. In the 15-24-year group, 244 of 401 active sites had gingival recession, while only 51 active sites had both gingival recession and deeper pockets. In the 25-34-year and 35-44-year groups, almost one-third of the active sites (329/1087) and more than one-third of the active sites (580/1312) respectively had a combination of gingival recession and deeper pockets. CONCLUSIONS: In this study, we demonstrated that in Chinese population without regular dental care, both the initiation of periodontitis and progression of previously existed periodontitis contributed to the natural progression of periodontitis and periodontal pocketing played a greater role with age increasing. CLINICAL SIGNIFICANCE: This rare study reports the natural progression of periodontal disease in a group of Chinese villagers (15-44 years) with virtually no access to regular dental care.

Effect of glycine powder air-polishing as an adjunct in the treatment of peri-implant mucositis: a pilot clinical trial.

BACKGROUND: Glycine powder air-polishing (GPAP) has the potential to effectively erase biofilms and may improve the treatment efficacy of peri-implant mucositis. This pilot clinical trial evaluated the effect of GPAP as an adjunct in treating peri-implant mucositis. MATERIALS AND METHODS: Twenty-four subjects having at least one implant with peri-implant mucositis were randomly assigned to test (12 subjects with 17 implants) and control (12 subjects with 16 implants) groups. Following baseline assessment, all subjects received oral hygiene instruction and non-surgical debridement. In the test group, the sites with probing depth (PD) ≥4 mm were additionally treated by GPAP for 5 sec. Clinical parameters were measured at 1-week, 1-month, and 3-month recall visits. RESULTS: At the 3-month visit, the mean reductions in PD at site level were 0.93 ± 0.93 mm and 0.91 ± 0.98 mm in the test and control groups, respectively (P < 0.05), and no significant difference existed between two groups. Mean bleeding score was also significantly reduced in both groups after the intervention. No complications or discomfort were reported during the study. CONCLUSIONS: This pilot clinical trial suggests that non-surgical mechanical debridement may effectively control peri-implant mucositis, and adjunctive GPAP treatment seems to have a limited beneficial effect as compared with mechanical debridement alone. However, further clinical trials with a large sample size are needed to confirm this preliminary observation.

[Longitudinal genetic effect on incisor position in cephalograms of female twins from six to twelve years old].

PURPOSE: A better understanding of the relative effect of genes and environment on craniofacial parameters should improve the possibilities and limitations of the orthodontic treatment and treatment planning. This is especially important for early treatment started in the mixed dentitions that is performed to enhance the dental and skeletal development before the eruption of the permanent dentition. METHODS: The sample used in this study consisted of lateral cephalograms of eighty-nine pairs of female twins in Beijing. With a mixed longitudinal method, the effective twins were 183 pairs (MZ 110, DZ 73). With the statistical methods of twins, the genetic and environmental effects were analyzed on the position of incisors in female twins from six to twelve years old. SPSS13.0 software package was used for independent-sample t test. RESULTS: Statistical comparisons revealed significant environmental effects on 6 positions of incisors (P<0.05), whilst family genetic effects on angle LI-MP were significant (P<0.05). CONCLUSION: Although the relatively low inherited proportions of dental variations could be found, genetic effects on incisor position should be carefully treated. Supported in part by a Grants-in-Aid for Scientific Research (International Scientific Exchange, 1994-1996) from the Japanese Ministry of Education, Culture, Science & Technology.

[Evaluation of the in vitro quantitative measurement of II degree furcation involvements in mandibular molars by cone-beam computed tomography].

OBJECTIVE: To evaluate the accuracy of measurement of II degree furcation involvements in molars of dry mandibles by cone-beam computed tomography (CBCT). METHODS: Twenty molars with II degree furcation involvements in dry mandibles were examined directly and measured by CBCT. Eight parameters were selected to describe the exact appearance of each II degree furcation involvements, including vertical defect dimensions, horizontal defect dimensions and furcation entrance dimensions. The results were compared with the corresponding data obtained by probing and periapical radiograph. RESULTS: All furcation involvements could be correctly classified by CBCT. For 5 of 8 parameters, no significant difference was found between the data obtained by CBCT and probing measurements (P>0.05). The distances from furcation entrance to alveolar crest, to bottom of bone pocket, and to the deepest site of horizontal bone defect measured by CBCT were less than those probed directly (P<0.05), but the differences were less than 0.5 mm (0.21, 0.24, 0.35 mm, respectively). The localization of furcation entrance may cause the differences. Two out of 20 furcation involvements could not be detected on periapical radiographs, and only 2 of 8 parameters could be measured on periapical radiographs. CONCLUSION: CBCT could provide precise and detailed 3D images of II degree furcation involvements in vitro.

[Association of Fc gamma receptors IIIA gene polymorphisms with the susceptibility to periodontitis in Chinese patients].

OBJECTIVE: Fc gamma receptors IIIA (Fc gamma RIIIA) mediates phagocytosis by macrophages, and cytokine production by NK cells and lymphocytes. The Fc gamma R IIIA-158V/F polymorphism may play a role in the pathogenesis of periodontitis. This study was to detect Fc gamma R IIIA-158V/F genotypes in Chinese patients with different forms of periodontitis. METHODS: Thirty aggressive periodontitis (AgP) patients (aged from 9 to 40, 13 males and 17 females), 131 chronic periodontitis (CP) patients (aged from 22 to 63, 76 males and 55 females), and 47 healthy subjects (H) (aged from 22 to 75, 21 males and 26 females) consented to participate in this study. Swabs were taken from each subject by ten strokes on the buccal mucosa. DNA was isolated from each swab by Chelex-100 methods. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)was performed to determine the Fc gamma R IIIA-158 genotypes in each groups of subject. RESULTS: The allele frequency was in Hardy-Weinberg equilibrium in our cohort for the V-158F polymorphism in Fc gamma R IIIA gene (P>0.05). The detected frequency of 158F/F in AgP patients was significantly higher than that in CP patients (16.7% vs 0.8%, P<0.05), and also higher than that in H subjects (16.7% vs 4.3%) but was not statistically significant. No significant difference in distribution of the Fc gamma R IIIA-158V/F genotype was found between CP and H groups (P>0.05). CONCLUSION: The distribution of Fc gamma R IIIA-158F/F genotype might have effects on the phenotypes of periodontitis.

Nifedipine intake increases the risk for periodontal destruction in subjects with type 2 diabetes mellitus.

BACKGROUND: This study investigated the possible association of nifedipine (NIF) intake and diabetes mellitus (DM) with periodontal destruction. METHODS: A group of Chinese subjects (N = 1,083, age: 63 +/- 8.7 years) were screened. Three hundred fifty-eight non-smokers with hypertension were selected for the study and were grouped based on DM status as non-DM and DM groups, DM(-) and DM(+) respectively. NIF(+) and NIF(-) indicated NIF intake or not. The groups were further divided: NIF(-)/DM(-) (n = 135); NIF(+)/DM(-) (n = 108); NIF(-)/DM(+) (n = 64); and NIF(+)/DM(+) (n = 51). The periodontal conditions in anterior teeth were assessed using plaque index, sulcus bleeding index, clinical attachment loss (AL), probing depth (PD), and the number of missing teeth. RESULTS: Using analysis of covariance, NIF intake was associated with mean PD and extent of PD > or =4 mm in the non-DM and DM groups. The subjects in the NIF(+)/DM(+) subgroup showed greater mean AL and percentage of sites with AL > or =5 mm and AL > or =7 mm than those in NIF(-)/DM(+) subgroup, whereas no significant difference existed between subjects in NIF(-)/DM(-) and NIF(+)/DM(-) subgroups. The NIF(+)/DM(+) subgroup exhibited a greater percentage of sites with AL > or =5 mm (35.5%) compared to the other three subgroups (24.7% for NIF[-]/DM[-], P = 0.004; 25.0% for NIF[+]/DM[-], P = 0.007; and 25.2% for NIF[-]/DM[+], P = 0.016). Logistic regression analysis showed that the NIF(+)/DM(+) subgroup had a significantly higher risk for having >10% of sites with AL > or =5 mm compared to the NIF(-)/DM(-) subgroup (odds ratio [OR] = 2.9; 95% confidence interval [CI]: 1.2 to 7.4; P = 0.022), the NIF(+)/DM(-) subgroup (OR = 3.1; 95% CI: 1.2 to 8.1; P = 0.020), and the NIF(-)/DM(+) subgroup (OR = 5.1; CI: 1.8 to 14.3; P = 0.002). CONCLUSION: NIF intake may increase the risk for periodontal destruction in patients with type 2 DM.

[The effect of different concentrations of platelet-rich plasma on human periodontal ligament cells in vitro].

PURPOSE: To assess the effect of different concentrations of platelet-rich plasma (PRP) on cell proliferation and alkaline phosphatase (ALP) activity of human periodontal ligament cells (hPDLCs) in vitro. METHODS: PRP was obtained from volunteer donors using two-step centrifugation. TGF-beta1 and PDGF-AB levels in activated PRP, PRP and plasma were evaluated by enzyme-linked immunosorbent assay. hPDLCs were exposed to various concentrations of PRP (2%,5%,10% and 20%) and DMEM (negative control), respectively. After 24 and 72 hours, cell proliferation was evaluated using Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) activity of hPDLCs was evaluated by a p-nitrophenyl phosphate disodium assay. Statistical analysis was performed using one-way ANOVA and Student's t test in SPSS10.0. RESULTS: TGF-beta1 and PDGF-AB levels were highest in activated PRP. The effect of various concentrations of PRP on cell proliferation and ALP activity was significantly greater than that of negative control (P<0.001). The effect of PRP was significantly greater at 72-hour compared with that at 24-hour (P<0.01), with significantly difference among various PRP concentrations (P<0.001). Cell proliferation and ALP activity increased when the concentration of PRP increased from 2% to 10%. The maximum effect on cell proliferation was achieved with 10% PRP; 20% PRP resulted in a reduced cell proliferation. However, ALP activity was greatest with 20% PRP. CONCLUSION: PRP preparations exert a dose-dependent effect on hPDLCs proliferation and ALP activity in a certain extent in vitro at 24-hour and 72-hour. Supported by the Capital Medical Development Fund (Grant No. 2005-2007).

[Construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds and dog periodontal ligament cells].

OBJECTIVE: To investigate the construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds (beta-TCP/col) and dog periodontal ligament cells (PDLCs). METHODS: Dog PDLCs were isolated, cultured and identified. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of beta-TCP/col on the proliferation of PDLCs. The cells were seeded onto porous beta-TCP/col scaffolds. The cellular capability of adhesion and growth on porous beta-TCP/col surface was investigated visually by scanning electron microscopy (SEM). RESULTS: The cytotoxicity assay indicated that there was no significant difference between beta-TCP/col and the control during the 7 days (P>0.05). SEM showed cells successfully adhered to porous beta-TCP/col scaffolds and spread extensively. Matrix secretions were found on the cell surface. CONCLUSION: Porous beta-tricalcium phosphate/collagen scaffolds were of good biocompatibility to the dog periodontal ligament cells, and were potential ideal candidates for periodontal tissue engineering.

[Effect of verapamil on the proliferation of normal gingival fibroblast].

OBJECTIVE: To evaluate the effect of verapamil on the proliferation of normal gingival fibroblast (NGF) in vitro. METHODS: NGF was isolated and cultured. The 5th passage of NGF was incubated with 0, 0.1, 1, 10, 100 micromol/L verapamil respectively. Methyl thiazolyl tetrazolium (MTT) assay and flow cytometry were used to detect cell proliferation and cell cycles. RESULTS: Incubated with 100 micromol/L verapamil for 66 h, the A value of normal gingival fibroblast was significantly lower than those without verapamil groups (P < 0.01). Incubated with 100 micromol/L verapamil for 18 h, 69% of cells were at the G(0) - G(1) phase, 27% were at the S phase. For control group (without verapamil) 41% of cells were at G(0) - G(1) phase and 49% cells were at S phase. There was significant difference between the two groups (P < 0.001). CONCLUSIONS: 100 micromol/L verapamil inhibited proliferation of normal gingival fibroblast by a cell-cycle arrest.

Correlation between single nucleotide polymorphisms in a calprotectin subunit gene and risk of periodontitis in a Chinese population.

S100A8, the light subunit of calprotectin, has been known to be associated with periodontal inflammation. The present study looked to detect whether three polymorphisms in the upstream region of the S100A8 gene are correlated with periodontitis. Three hundred and twenty one subjects, including chronic periodontitis (CP) patients, aggressive periodontitis (AgP) patients and periodontally healthy controls, were recruited. The SNPs rs3795391, rs3806232 and rs3885688 were analyzed by PCR-RFLP analysis. No person carried the rs3885688 polymorphism in this cohort. For the other two polymorphisms, the combined effects of genotype/allele and gender were shown to be associated with the risk of periodontitis using multivariate logistic regression analysis. The G+ genotype/G allele may be considered to exert a significant protective effect in males against AgP (Genotype: rs3795391: P= 0.032, rs3806232: P= 0.017; Allele: rs3795391: P= 0.024, rs3806232: P= 0.013). Although the combined effects of genotype and gender on CP susceptibility were not observed for these two polymorphisms, there does seem to be increased risk of CP in males with allele A compared to females with allele A (rs3795391: P= 0.008; rs3806232: P= 0.009). Hence we found an important association between polymorphisms in the S100A8 gene and periodontitis in a Chinese population.

[Novel mutations of cathepsin C gene in two Chinese patients with Papillon-Lefèvre syndrome].

OBJECTIVE: To investigate the mutational characteristics of cathepsin C (CTSC) gene in two Chinese patients with Papillon-Lefèvre syndrome (PLS), and provide molecular basis for research of the pathogenesis of PLS. METHODS: Peripheral blood samples were obtained from patients and their parents respectively. Genomic DNA were extracted after consents. Polymerase chain reaction, direct DNA sequencing and restriction enzyme reaction were performed to screen mutations of CTSC gene. RESULTS: Compound heterozygous mutations of CTSC gene were identified in the two patients. Patient I carried the G139R and S260P mutations, patient II had the R250X and C258W mutations. The parents were heterozygous carriers without the clinical feature of PLS. None of the mutations were detected in normal controls. Furthermore, the S260P and C258W changes were novel mutations of CTSC gene, which had not been reported previously. CONCLUSIONS: Mutations of CTSC gene are responsible for the phenotype of Papillon-Lefèvre syndrome in two Chinese patients. The results extend the mutation spectrum of CTSC gene and also provide basis for gene diagnosis of PLS in China.

[Effects of enamel matrix protein on the growth of human periodontal ligament cells on root cementum surfaces].

OBJECTIVE: To evaluate the effect of enamel matrix protein (EMP) on the attachment and proliferation of periodontal ligament cells (PDLC) on diseased cementum surfaces in vitro. METHODS: Cementum chips were obtained from diseased roots exposed to periodontal pocket. Thirteen diseased root cementum chips were conditioned with EMP. Meanwhile, 13 diseased and 13 healthy cementum chips were treated with physiological saline as control. The growth and morphology of PDLC on the root surface were observed after 24 hours incubation by scanning electron microscope (SEM). PDLC attachment and proliferation were quantified using MTT assay at 16 or 72 hours. RESULTS: The cells on EMP treated roots under SEM were growing robust like the cells on healthy roots. By contrast, the diseased cementum surface without conditioned with EMP was only partly covered with spindle-shaped cells, with filopodia appearing short and thin. MTT assay indicated that the number of adhered and proliferated cells on diseased cementum chips treated with EMP was significantly greater than that on diseased chips treated with saline (adhesion: 0.45 +/- 0.03 vs. 0.37 +/- 0.05, P < 0.05; proliferation: 0.71 +/- 0.02 vs. 0.55 +/- 0.08, P < 0.01), but less than that on healthy chips (adhesion: 0.45 +/- 0.03 vs. 0.67 +/- 0.08, P < 0.05; proliferation: 0.71 +/- 0.02 vs. 1.05 +/- 0.09, P < 0.05). CONCLUSIONS: It was suggested that EMP could promote the growth of PDLC on the diseased root cementum surface.