Natural carbohydrate-based thermosensitive chitosan/pectin adsorbent for removal of Pb(II) from aqueous solutions.

Biodegradable and eco-friendly adsorbents composed of natural carbohydrates have been used to replace carbon-based materials. This study presents a natural carbohydrate-based chitosan/pectin (CS/Pec) hydrogel adsorbent to remove Pb(II) from aqueous solutions. The physical CS/Pec hydrogel was prepared by blending aqueous CS and Pec solutions at 65 °C, preventing the use of toxic chemistries (crosslinking agents). The thermosensitive CS/Pec hydrogel was quickly created by cooling CS/Pec blend at room temperature. The used strategy created stable CS/Pec hydrogel against disintegration and water dissolution. The as-prepared hydrogel was characterized by infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The adsorbent had 1.688 mmol -COO- for each gram. These ionized sites bind Pb(II) ions, promoting their adsorption. The adsorption kinetic and equilibrium studies indicated that the Elovich and pseudo-second-order models adjusted well to the experimental data, respectively. The maximum removal capacities (qm) predicted by the Langmuir and Sips isotherms achieved 108.2 and 97.55 mg/g at 0.83 g/L adsorbent dosage (pH 4.0). The hydrogel/Pb(II) pair was characterized by scanning electron microscopy (SEM), X-ray dispersive energy (EDS), and differential scanning calorimetry (DSC). The chemisorption seems to play an essential role in the Pb(II) adsorption. Therefore, the adsorbent was not recovered, showing low potential for reusability.

The impact of crown fracture in the permanent dentition on children's quality of life.

BACKGROUND/AIM: Among the diseases related to oral health, traumatic dental injuries (TDI) can lead to pain, loss of function and aesthetic problems, with physical, emotional and social consequences for children and their families. The aim of this study was to investigate the relationship between enamel fracture and enamel-dentin fracture with oral health-related quality of life (OHRQoL). MATERIAL AND METHODS: This cross-sectional study had a representative sample of 1589 children between 8-10 years of age from public schools. The OHRQoL was obtained through the Child Perceptions Questionnaire (CPQ8-10 ), which is a questionnaire validated for Brazilian children. Clinical data were collected by 4 calibrated examiners (Kappa > 0.7) using the Decay, Missing, Filled Teeth (DMFT) Index, Dental Aesthetic Index (DAI) and TDI. A socio-economic questionnaire was sent to the caregivers to be answered at home. Descriptive statistics and Poisson regression with prevalence ratio (PR) and 95% confidence interval (CI) were used for statistical analysis. RESULTS: The prevalence of TDI was 10.6%, and among these 10.3% who had an impact on the OHRQoL, it was due to enamel-dentin fracture. Children with enamel-dentin fracture had (PR 1.35; 95% CI 1.07-1.70) higher prevalence of impact on the OHRQoL. Children with enamel fracture had no impact on the OHRQoL (P = .254). CONCLUSION: Enamel fracture had no significant impact on children's quality of life, while enamel-dentin fracture did have an impact on quality of life.

Untreated Dental Caries Is Associated with Reports of Verbal Bullying in Children 8-10 Years Old.

The objective of this research was to verify the association between verbal bullying and untreated dental caries. The present cross-sectional study had a representative sample of 1,589 children, aged 8-10 years, from public schools. Information on verbal bullying related to the oral condition was obtained through a questionnaire directed to the students. Clinical data were collected by 4 calibrated examiners (kappa > 0.70) using the DMFT/dmft and PUFA/pufa indexes for caries. Socioeconomic issues were answered by those responsible. The prevalence of verbal bullying related to the oral condition was 27%. The results of the Poisson regression, in an adjusted multiple model, showed a significant association between bullying and untreated caries lesions (prevalence ratio, PR: 1.27; 95% CI: 1.07-1.52), PUFA/pufa index (PR: 1.34; 95% CI: 1.11-1.61), pulp involvement (PR: 1.35; 95% CI: 1.09-1.67), and abscess (PR: 1.74; 95% CI: 1.18-2.56). It was concluded that children with untreated dental caries had a higher prevalence of verbal bullying when compared to caries-free or disease-treated children.

Immobilized humic substances and immobilized aggregates of humic substances as sorbent for solid phase extraction.

In this work, humic substances (HS) immobilized, as a thin layer or as aggregates, on silica gel were tested as material for solid phase extraction. Some triazines (simazine, atrazine, therbutylazine, atrazine-desethyl-desisopropyl-2-hydroxy, ametryn and terbutryn), have been selected as test analytes due to their environmental importance and to span a large range of solubility and octanol/water partition coefficient (logP). The sorbent was obtained immobilizing a thin layer of HS via physisorption on a pre-coated silica gel with a cationic polymer (polybrene). While the sorbent could be used as it is, it was demonstrated that additional HS could be immobilized, via weak interactions, to form stable humic aggregates. However, while a higher quantity of HS could be immobilized, no significant differences were observed in the sorption parameters. This sorbent have been tested for solid phase extraction to concentrate triazines from aqueous matrixes. The sorbent demonstrated performances equivalent to commercial alternatives as a concentration factor between 50 and 200, depending on the type of triazines, was obtained. Moreover the low cost and the high flow rate of sample through the column allowed using high quantity of sorbent. The analytical procedure was tested with different matrixes including tap water, river water and estuarine water.

Dynamically formed admicelle layer to control the amplitude of cathodic electroosmotic flow.

In this manuscript, a method to precisely adjust the amplitude of a cathodic electroosmotic flow is described. The method uses a capillary pre-coated with a cationic polymer (polybrene), in presence of an anionic surfactant such as sodium dodecyl sulfate. At low concentration of surfactant, molecules will self-assemble to form an immobilized hemimicelle layer with the anionic "head" in contact with the cationic coating and the hydrophobic tail reaching into the background electrolyte. At higher concentration, surfactant molecules in solution will then interact, via hydrophobic interactions, to form an admicelle layer. It has been demonstrated that the admicelle layer can be constructed with either pure anionic surfactant (SDS), or a mixture of anionic and neutral surfactants. Admicelle coatings can be used to control the electroosmotic flow (EOF). While at low surfactant concentration the amplitude of the EOF depends on the concentration of the surfactants concentration, when this concentration reaches the critical admicelle concentration the EOF becomes near constant. The amplitude of the EOF can also be adjusted via the relative proportion of neutral and ionic surfactant in solution. Using this approach, the EOF was varied from 0.450 to 3.848 × 10(-8)m(2)V(-1)s(-1) with a precision below 0.050 × 10(-8)m(2)V(-1)s(-1) (standard deviation measured with three replicates). The coating has been tested using a mix of triazines (atrazine, simazine and terbuthylazine) and a beer sample. With the beer sample an average relative standard deviation of 1.5% for the migration time and of 2.2% for the corrected peak area was obtained.