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The key of the root canal therapy is to eliminate the micro-organism infection, fill the root canal tightly and reduce the stimulation to the periapical tissues. However, it is quite difficult to meet all the conditions due to the defect of the material. Here we develop a novel root canal sealer (MZOE), in which zinc oxide eugenol (ZOE) were fabricated with polyhexamethylene guanidine (PHMG), and the PHMG's concentration is 0.8, 1.0, 1.2 and 1.4%. Our investigation tested its physical properties, antibacterial effect to E. faecalis, C. albicans, E. coli, S. aureus and cytotoxicity to human periodontal ligament fibroblasts (HPDLFs). The physical properties of the MZOE conformed to the ISO 6876:2001, and its antibacterial effect was stronger than ZOE (p

Nitrated polycyclic aromatic hydrocarbons are more mutagenic and carcinogenic than parent PAHs. The formation mechanism of dinitro-pyrenes initiated by OH from mononitro-pyrenes was conducted by quantum chemical calculations. The products are 1,2-, 1,7-, 2,4-, 2,5- and 2,7- dinitropyrenes. Water molecules can decrease the Gibbs activation barriers of water loss step of NO2-OH-nitropyrene. By canonical variational transition state theory with small curvature tunneling correction, the calculated overall rate constants for 1-, 2- and 4-nitropyrene are 8.13 × 10−13 cm3 molecule−1 s−1, 8.90 × 10−13 cm3 molecule−1 s−1 and 1.50 × 10−12 cm3 molecule−1 s−1 at 298 K and 1 atm, respectively.

Furanaldehydes have raised environmental attention due to their large emission and high potential to generate secondary organic aerosol. In this study, the removal process of 2-furanaldehyde initiated by NO3 in gas phase was investigated by quantum chemical calculations. The overall rate constant for trans-2-furanaldehyde initiated by NO3 is 1.04 × 10−12 cm3 molecule−1 s−1 at 298 K and 1 atm. The atmospheric lifetime of 2-furanaldehyde with NO3 is estimated to be 0.53 h. This study indicates that the night-time reactions of 2-furanaldehyde with NO3 could contribute to the oxidative capacity of the atmosphere, secondary organic aerosol formation and new particle formation.

Amides, a class of nitrogen-containing organic pollutants in the atmosphere, may affect the formation of atmospheric aerosols by the interactions with sulfuric acid. Here, the molecular interactions of sulfuric acid with formamide, methylformamide, dimethylformamide, acetamide, methylacetamide and dimethylacetamide was investigated by density functional theory. Geometry optimization and Gibbs free energy calculation were carried out at M06-2X/6-311++G(3df,3pd) level. The results indicate that the addition of amides to H2SO4 might have a promoting effect on atmospheric new particle formation at 298.15 K and 1 atm. In the initial stage of new particle formation, the binding capacity of amides and sulfuric acid is stronger than ammonia, but weaker than methylamine. It is worth noting that the trans-methylacetamide could have similar capabilities of stabilizing sulfuric acid as dimethylamine. In the presence of water, amides are found to only have a weak enhancement capability on new particle formation. In addition, we can infer from evaporation rate that the small molecule clusters of formamide and sulfuric acid may be more energetically favorable than macromolecule clusters.

In recent years, Criegee chemistry has become an important research focus due to its relevance in regulating concentrations of tropospheric OH radicals, hydroperoxides, sulfates, nitrates, and aerosols. However, to date, its interface behavior remains poorly understood. Thus, in this study, we used the Born-Oppenheimer molecular dynamics (BOMD) simulation method to explore the reaction mechanisms between Criegee intermediates (CIs) and methylsulfonic acid (MSA) at the air-water interface, then compared the observed behaviors with those in the gas phase. The addition of Criegee intermediates to MSA is nearly a barrierless reaction and follows a loop-structure mechanism in the gas phase. The high rate constants indicate that the Criegee intermediates and MSA reactions are the main acid removal channels. At the water's surface, the interaction of Criegee intermediates with MSA includes three main channels: 1) direct addition reaction, 2) H2O-mediated hydroperoxide formation, and 3) MSA-mediated Criegee hydration. These reaction channels follow a loop-structure or a stepwise mechanism and proceed at the picosecond time-scale. The results of this work broaden our understanding of Criegee atmospheric behaviors in polluted urban and marine areas, which in turn will aid in developing more effective pollution control measures.

Oral squamous cell carcinoma (OSCC) is the most prevalent form of malignant tumour in the oral cavity and its early detection is critical for improving the prognosis of affected patients. The present study aimed to isolate and confirm exosomes derived from the supernatant of the OSCC cell line CAL-27 and human oral epithelial cells (HOECs), analyze long non-coding RNA (lncRNA) expression profiles and determine the diagnostic value based on bioinformatics analyses. The results indicated that the particles isolated from the supernatant of CAL-27 and HOECs were either round or oval, had a size range of 30-150 nm and were enriched with ALG-2 interacting protein X (ALIX) and tumour susceptibility 101 proteins (TSG101). These characteristics confirmed that these particles were exosomes. Three lncRNAs (NR-026892.1, NR-126435.1 and NR-036586.1) were selected as potential diagnostic biomarkers for OSCC. The expression levels of the selected lncRNAs were significantly different in CAL-27-exo vs. HOEC-exo, as well as in whole cells (CAL-27 vs. HOECs) (P

The aims of this study were to generate periodontal ligament (PDL) cells that have adenovirus- or lentivirus-mediated overexpression of human telomerase reverse transcriptase (hTERT) and to compare the osteogenic and proliferative abilities of the two cell lines to establish an efficient and stable cell model that will be more suitable for studies of PDL regeneration. After construction of the recombinant adenovirus plasmid pAd-pshuttle-cmv-hTERT, human PDL cells were infected by packaged adenovirus and lentivirus particles to establish two PDL cell lines. The expression levels of hTERT and mRNA for alkaline phosphatase, osteopontin, osteocalcin, bone sialoprotein, core-binding factor (runt-related transcription factor 2), and type I collagen were assessed for each cell line. After culture in osteoinductive culture medium for 14 days, the PDL cells were stained with alizarin red to observe formation of mineralized nodules, and proliferation activity was measured with a CCK-8 kit. A quantitative polymerase chain reaction assay indicated that the two transduced cell lines expressed hTERT levels that were significantly higher than that seen for normal PDL cells. Expression of all osteogenic genes tested, with the exception of osteopontin, was higher for both the adenovirus- and lentivirus-transduced cells relative to normal PDL cells. The expression of bone sialoprotein, osteocalcin, and runt-related transcription factor 2 in adenovirus-transduced cells was significantly higher than that for lentivirus-transduced cells. Alizarin red staining showed that the adenovirus-transduced cell line produced more mineralized nodules than the lentivirus-transduced cell line, whereas a CCK-8 test showed that the adenovirus-transduced cell line had higher proliferation activity than lentivirus-transduced cells. In conclusion, a PDL cell line established by adenovirus transduction had superior osteogenic differentiation and proliferative activity compared to the cell line produced by lentivirus transduction. The results indicate that PDL cells having adenovirus-mediated expression of hTERT would be a more suitable model for studies of PDL regeneration.

Nitrated polycyclic aromatic hydrocarbons have received an increasing number of considerations because of their higher mutagens than parent PAHs. In this paper, the formation of dinitro-naphthalene was investigated mechanistically using 1- and 2-nitronaphthalene as precursors with the aid of high-accuracy quantum chemistry calculation. The geometrical parameters, as well as vibrational frequencies, were calculated at the BB1K/6-31+G(d,p) level. Water molecule plays an important role in the formation of dinitro-naphthalene. The rate constants were deduced by canonical variational transition-state theory with small curvature tunneling contribution over the temperature range of 273-333 K. Meanwhile, the Arrhenius formulas were fitted for the OH addition of both 1- and 2-nitronaphthalene. The calculated overall rate constants for 1-nitronaphthalene and 2-nitronaphthalene at 298 K and 1 atm are 7.43 × 10(-13) and 7.48 × 10(-13) cm(3) molecule(-1) s(-1), respectively. The rate constants of NO3 addition to 1-nitronaphthalene and 2-nitronaphthalene by RRKM method at 298 K and 1 atm are 3.55 × 10(-15) and 3.47 × 10(-15) cm(3) molecule(-1) s(-1), respectively. This study provides a comprehensive investigation of the formation process of dinitro-naphthalenes, initiated by OH and NO3 radicals and should facilitate to illuminate its atmospheric source. Oxygen may probably be competitive with the second NO2 addition step when the concentration of NO2 is at low level.

Exosomes, secreted by both normal cells and tumor cells, are small membrane vesicle bodies that presented in saliva, blood, urine and other body fluids. The proteins, lipids, non-coding RNA and other components in exosomes functioned profoundly in cell communication and signal transduction, and tumor-derived exosomes can activate various signaling pathways and influence tumor microenvironment to participate in the tumor proliferation and migration. Non-coding RNAs play a crucial role in regulating gene expression, such as cell physiology, tumor development and tumor immunity. At present, researchs focused on exosome non-coding RNA, especially miRNA and lnRNA. In this review, we will review the tumor-derived exosome miRNA and lnRNA in tumorigenesis and development.

A series of transition metal-free tandem reactions for the synthesis of indolizines and 6,7-dihydroindolizin-8(5H)-ones by 4-bromobut-2-enoate ramifications reacted with 2-acetyl pyrrole derivatives are described. As the α-carbon changed from CH3, CH2Cl, CHCl2, to CCl3, different kinds of tandem reactions were observed. These tandem reactions could be used to synthesize fused indolizine and indolizidine scaffolds under mild and green conditions.

An interesting dimmer (excimer)-induced-AIE characteristic of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one was observed. By using a ring-opening reaction, we developed a novel fluorescent probe based on sub-micron particles of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one in water.

Different tandem reactions take place when the α-substituents in the pyrrole substrates are changed (-Me, CH2Cl, -CHCl2, -CCl3).

A transition metal-free methodology for the synthesis of pyridazinopyrido[3,2-f][1,4]thiazepine-diones was studied. The construction of this tricyclic system went through a one-pot coupling/Smiles rearrangement/cyclization process. The high yields of pure products were obtained through simple recrystallization.

A transition metal-free methodology for the synthesis of pyridazinopyrido[3,2-f][1,4]thiazepine-diones was studied. The construction of this tricyclic system went through a one-pot coupling/Smiles rearrangement/cyclization process. The high yields of pure products were obtained through simple recrystallization.