The general position number and the iteration time in the P3 convexity

In this paper, we investigate two graph convexity parameters: the iteration time and the general position number. Harary and Nieminem introduced in 1981 the iteration time in the geodesic convexity, but its computational complexity was still open. Manuel and Klav\v{z}ar introduced in 2018 the general position number of the geodesic convexity and proved that it is NP-hard to compute. In this paper, we extend these parameters to the P3 convexity and prove that it is NP-hard to compute them. With this, we also prove that the iteration number is NP-hard on the geodesic convexity even in graphs with diameter two. These results are the last three missing NP-hardness results regarding the ten most studied graph convexity parameters in the geodesic and P3 convexities

Fluoride intake from drinking water and dentifrice by children living in a tropical area of Brazil

OBJECTIVE: To assess fluoride (F-) intake from water and toothpaste by children aged 18 to 36 months and to monitor the F- concentrations in the drinking water system in a tropical city of Brazil. METHODS: Children (n=58) aged 18-36 months, all lifetime residents of Penedo, state of Alagoas, Brazil, participated in this study. Water F- analyses were carried out in 7 different occasions at least a week apart. For 2 days all the water drunk by each child was accounted for. Fluoride intake from water for each child was estimated using the mean F- concentration of water in 7 different occasions. Fluoride intake from toothpaste was estimated by subtracting the recovered post-brushing F- from the original amount placed in the toothbrush. The F- intake from water and toothpaste was estimated by dividing the total amount of F- ingested by the weight of each child. RESULTS: The mean F- concentration in the drinking water was 0.94 ppm (mean range 0.78-1.1 ppm), which is above the 0.7 ppm recommended for this area of Brazil. Mean total F- intake from water and toothpaste was 0.128 mg F-/Kg Body Weight/day. The daily means of F- intake from water and toothpaste were 0.021 and 0.107 mg F-/Kg Body Weight, respectively. Ninety six percent of children showed F- intake above 0.07 mg F-/Kg Body Weight/day. CONCLUSIONS: Children in Penedo are at risk for developing dental fluorosis due to high F- intake from fluoridated toothpastes. Water fluoridation showed low contribution to the total F- intake. However, high water F- concentrations in the water indicate the need of surveillance of the artificial water fluoridation system.OBJETIVOS: determinar a ingestão de flúor (F-) pela água e creme dental em crianças de 18 a 36 meses de idade que moram em uma cidade de clima tropical no Brasil e monitorar as concentrações de F- no sistema de água potável. MATERIAIS MÉTODOS: participaram deste estudo crianças (n=58), 18-36 meses, todas residentes vitalícias de Penedo (Alagoas), Brasil. As análises de F- em amostras de água foram realizadas em 7 ocasiões diferentes em semanas separadas. Durante 2 dias toda a água bebida por cada criança foi considerada. A ingestão de fluoreto para cada criança foi calculada pela média de flúor na água nas 7 ocasiões diferentes. A ingestão de F- pelo creme dental foi calculada subtraindo a saliva recuperada do expectorado pela quantidade de F- colocada na escova dental. A ingestão de F- de água e pasta de dentes foi calculada dividindo a quantia de F ingerida pelo peso de cada criança. RESULTADOS: A concentração média de F- em água potável foi de 0,94 ppm (variando de 0.78-1.12 ppm) estando acima do recomendado para esta área do Brasil que é de 0,7 ppm. A ingestão de F- total (água + creme dental) foi de 0,128 mg de F/Kg peso/dia. As médias diárias de ingestão de F- pela água e creme dental foram de 0,021 e 0,107 mg F-/Kg de peso corporal dia, respectivamente. Noventa que seis por cento das crianças demonstraram ingestão de F- superior a 0,07 mg de F-/Kg peso/dia. CONCLUSÕES: crianças em Penedo estão sob risco de desenvolver fluorose dental devido a elevada ingestão de F- pelo creme dental fluoretado. Adição de flúor à água de água mostrou baixa contribuição ao flúor total ingerido. Porém, altas concentrações de F- na água indicam a necessidade de vigilância do sistema de fluoretação artificial das águas

Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology

The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as β-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the β-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L−1 oNP min−1 g−1 was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industr

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity