Influence of soil organic matter (SOM) on the adsorption, desorption and transport of polycyclic aromatic hydrocarbons (PAHs) has already been given full investigation in soils. In this paper, confocal laser scanning microscope (CLSM) was used to elucidate aqueous leaching of PAHs in different types of soil with soil columns, which enhanced understanding on transport of PAHs appreciably. Four typical soils in China including fluvo-aquic soil (FAS), aquic brown soil (ABS), red soil (RS) and black soil (BS) were selected in the experiment. Target pollutants of phenanthrene and pyrene were extracted from the leachate by solid phase extraction (SPE) and then determined by high performance liquid chromatography (HPLC). The experimental results showed that the retardation ability of pollutants to the four selected types of soil increased in the order: FAS H” ABS < RS < BS. To better expatiate the dissimilar ability of the PAHs transported in the four typical soils, the retardation factor (R), distribution constant (Kd) and partition coefficient (Koc) were evaluated based on the observed breakthrough curves (BTCs). Furthermore, CLSM was used to visualize the effects of SOM on the transport ability of PAHs in different types of soil. All the results provided vivid understanding with mathematical and especially optical measures that SOM was considered the single most important factor limiting the availability and mobility of PAHs in soil over the duration of the experiment.

Objective: Confocal laser scanning microscopy (CLSM) is relatively a new light microscopical imaging technique with a wide range of applications in biological sciences. The primary value of CLSM for the biologist is its ability to provide optical sections from a three-dimensional specimen. The present study was designed to assess the thickness and content of in vivo accumulated dental plaque using CLSM and scanning electron microscopy (SEM).Materials and Methods: Acroflat lower arch splints (acrylic appliance) were worn by five participants for three days without any disturbance. The formed plaques were assessed using CLSM combined with vital fluorescence technique and SEM.Results: In this study accumulated dental plaque revealed varied plaque microflora vitality and thickness according to participant’s oral hygiene. The thickness of plaque smears ranged from 40.32 to 140.72 mm and 65.00 to 128.88 mm for live (vital) and dead accumulated microorganisms, respectively. Meanwhile, the thickness of plaque on the appliance ranged from 101 mm to 653 mm. CLSM revealed both dead and vital bacteria on the surface of the dental plaque. In addition, SEM revealed layers of various bacterial aggregations in all dental plaques.Conclusion: This study offers a potent non-invasive tool to evaluate and assess the dental plaque biofilm, which is a very important factor in the development of dental caries.

Introduction: This study aimed to evaluate the effectiveness of N-acetylcysteine (NAC), photodynamic therapy (PDT) and NAC with supplemental PDT in optimizing the removal of bacteria from infected dentinal tubules of root canals infected with Enterococcus (E. ) faecalis biofilm. Methods and Materials: Eighty human teeth were randomly divided into 5 groups (n=16) according to the intracanal medication used: saline solution (control); calcium hydroxide (CH); NAC; PDT; NAC+PDT. Ten samples from each group were prepared for microbiological culture analysis (CFU/mL) and were inoculated with E. faecalis suspension for 21 days for biofilm development; the other six samples from each group were prepared for scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) and submitted to a 5-days contamination protocol including eight centrifugation cycles on every other day for dentinal tubules infection. For antimicrobial activity analysis by microbiological culture, the root canals were contaminated with E. faecalis biofilm, instrumented and then medicated according to the experimental groups. Three samples were collected from the root canals: after 21-days of contamination, immediately after the instrumentation and 14-days after the medication according to the experimental groups. The morphology of E. faecalis biofilm on the root canal walls and bacterial cells viability were assessed by means of SEM and CLSM, respectively. One-way ANOVA and Repeated Measures ANOVA tests were used to analyze the obtained data statistically. Results: CFU/mL analysis showed that CH, NAC and NAC+PDT promoted greater antibacterial activity with statistically significant difference compared to saline solution and PDT (P<0. 0001). However, saline solution and PDT were statistically similar. Illustrative images by SEM confirmed partially the CFU/mL results. CLSM showed that all groups were effective eliminating E. faecalis except for the saline solution group. Conclusions: Based on this in vitro study NAC was bactericidal against E. faecalis biofilms regardless PDT stimulation, presenting similar antimicrobial activity to CH.