Experimental design and multiple response optimization. Using the desirability function in analytical methods development

Effects of sediment geochemical properties on heavy metal bioavailability.

Traditional supplements of selenium generally have a low degree of absorption and increased toxicity. Therefore, it is imperative to develop innovative systems as transporters of selenium compounds, which would raise the bioavailability of this element and allow its controlled release in the organism. Nanoscale selenium has attracted a great interest as a food additive especially in individuals with selenium deficiency, but also as a therapeutic agent without significant side effects in medicine. This review is focused on the incorporation of nanotechnological applications, in particular exploring the possibilities of a more effective way of administration, especially in selenium-deficient organisms. In addition, this review summarizes the survey of knowledge on selenium nanoparticles, their biological effects in the organism, advantages, absorption mechanisms, and nanotechnological applications for peroral administration.

/pdf/nano-selenium-and-its-nanomedicine-applications-a-critical-4o0hfo1u3k.pdf

Nano-selenium and its nanomedicine applications: a critical review.

Nanoemulsion as pharmaceutical carrier for dermal and transdermal drug delivery: Formulation development, stability issues, basic considerations and applications.

Enhanced extraction of bioactive natural products using tailor-made deep eutectic solvents: application to flavonoid extraction from Flos sophorae

Response surface methodology (RSM) as a tool for optimization in analytical chemistry

A sediment core from Guanabara Bay (Brazil) was analyzed for 210Pb dating, grain size, total organic carbon (TOC) and total nitrogen, carbon stable isotope ratio (δ13C), nitrogen stable isotope ratio (δ15N) and the metals Fe, Mn, Ni, Co, Cu, Pb, V and Zn, to assess the influence of land use changes on the aquatic system in a region for which large industrial and urban development is expected in the next few decades. To obtain baseline data for improving the monitoring of the expected increase in anthropogenic impacts from surrounding drainage basins, a multivariate analysis of data from different sediment layers was carried out to evaluate the dated sediment record. The geochemical data suggested three different sedimentary phases along the last 200 years. Before the 1880s, the highest clay and TOC contents were observed, where the C/N ratios and the δ13C values suggested a mixture of algal and terrestrial organic matter and the lowest concentrations of Co, Cu, Pb, V and Zn, for which background levels were estimated (4.6, 2.7, 14.9, 24.3 and 70.2 mg kg−1, respectively). From the 1880s to the 1950s, the metal concentrations and sand particles increased, but no change in organic matter quality was observed, reflecting a period of land use change, still without significant sewage input. After the 1950s, the sedimentation rate increased from 0.42 to 0.77 cm year−1 and increasing urban sewage input was evidenced by lower C/N ratios, higher δ15N, decrease of Fe and Mn concentrations and increased fluxes of metals and TOC, which showed a good relationship with population growth data.

Sedimentary geochemical record of historical anthropogenic activities affecting Guanabara Bay (Brazil) environmental quality

Purpose
The role of acid-volatile sulfide (AVS) as a factor affecting (or reflecting the environmental conditions influencing) the behavior of metals has been evidenced in anoxic sediments. However, sediment quality studies tend not to consider any potential AVS role when sum of simultaneously extracted metal (ΣSEM) concentrations exceed AVS concentrations, restricting the application of the AVS model to predict toxicity, rather than coupling this model (when applicable) with other possible interpretations of metal–AVS relations.

Leonardo S. Villar

Papers

Response surface methodology (RSM) as a tool for optimization in analytical chemistry

Sedimentary geochemical record of historical anthropogenic activities affecting Guanabara Bay (Brazil) environmental quality

Relation of acid-volatile sulfides (AVS) with metals in sediments from eutrophicated estuaries: Is it limited by metal-to-AVS ratios?