Optimization and Validation of a UV–HPLC Method for Vitamin C Determination in Strawberries (<Emphasis Type="Italic">Fragaria ananassa</Emphasis> Duch.), Using Experimental Designs

Vitamin C or total ascorbic acid (TAA) in fruits can be assumed as ascorbic acid (AA) plus dehydroascorbic acid (DHA) content. The aim of this work was to optimize and validate, using experimental designs, a new high-performance liquid chromatographic method for vitamin C determination in strawberries. The mobile phase (MP) consisted of a 0.03 M sodium acetate/acetic acid buffer, 5% methanol. For optimization, a Box–Behnken design was used (three factors at three levels: (a) pH of MP, 3.8–5.8; (b) wavelength, 240–270 nm; and (c) flow rate, 0.5–1.2 ml min⁻¹). Responses were: AA and TAA areas, peak widths, and retention times. A global optimization was performed using the Derringer desirability function, and a value of 0.84 was reached for the combination of design factors: A = 5.8, B = 251 nm, and C = 1.15 ml min⁻¹. Method validation, using AA standard solutions, included: linearity study, limits of detection and quantification, and calibration and analytical sensitivity quantifications. Precision and accuracy were studied in strawberry extracts. The coefficients of variation (percent) were: AA, 1.5%; TAA, 1.8%, and DHA, 4.9%. Accuracy was evaluated with AA standard spiked in 30–150% range of the expected amount of analyte in real samples. The joint confidence elliptical region test and t test were employed for the study of the difference between recoveries (percent) and the ideal 100%. The robustness was analyzed using a fractional factorial design (3⁴⁻²), and an AA recovery study after slight changes in operative variables was performed. The results indicate that the optimized method was linear, sensible, precise, accurate, and robust.     

The influence of nitrogen incorporation on the optical properties of anodic Ta2O5

Anodic oxides were grown on sputter-deposited Ta in different aqueous solutions. A photoelectrochemical investigation was performed in order to estimate the band gap of the films as a function of the anodizing bath composition and formation voltage, i.e. thickness. Photoelectrochemical results provided evidence of sub-band gap photocurrent for films formed in a bath containing ammonium ions at pH 9. Elemental depth profiles obtained by glow discharge optical emission spectroscopy revealed the presence of nitrogen species in the outer part of the anodic films, which is bonded to Ta according to XPS analysis. A mechanism of nitrogen incorporation is proposed in order to account for the pH dependence of film composition.     

Novel Tacrine‐Grafted Ugi Adducts as Multipotent Anti‐Alzheimer Drugs: A Synthetic Renewal in Tacrine–Ferulic Acid Hybrids

Herein we describe the design, multicomponent synthesis, and biological, molecular modeling and ADMET studies, as well as in vitro PAMPA‐blood–brain barrier (BBB) analysis of new tacrine–ferulic acid hybrids (TFAHs). We identified (E)‐3‐(hydroxy‐3‐methoxyphenyl)‐N‐{8[(7‐methoxy‐1,2,3,4‐tetrahydroacridin‐9‐yl)amino]octyl}‐N‐[2‐(naphthalen‐2‐ylamino)2‐oxoethyl]acrylamide (TFAH 10 n ) as a particularly interesting multipotent compound that shows moderate and completely selective inhibition of human butyrylcholinesterase (IC₅₀=68.2 nM ), strong antioxidant activity (4.29 equiv trolox in an oxygen radical absorbance capacity (ORAC) assay), and good β‐amyloid (Aβ) anti‐aggregation properties (65.6 % at 1:1 ratio); moreover, it is able to permeate central nervous system (CNS) tissues, as determined by PAMPA‐BBB assay. Notably, even when tested at very high concentrations, TFAH 10 n easily surpasses the other TFAHs in hepatotoxicity profiling (59.4 % cell viability at 1000 μM ), affording good neuroprotection against toxic insults such as Aβ_1–40, Aβ_1–42, H₂O₂, and oligomycin A/rotenone on SH‐SY5Y cells, at 1 μM . The results reported herein support the development of new multipotent TFAH derivatives as potential drugs for the treatment of Alzheimer′s disease.     

Potent,Metabolically Stable 2‐Alkyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐adenines as Adenosine A2A Receptor Ligands

Inhibition of adenosine A_2A receptors has been shown to elicit a therapeutic response in preclinical animal models of Parkinson’s disease (PD). We previously identified the triazolo‐9H‐purine, ST1535, as a potent A_2AR antagonist. Studies revealed that ST1535 is extensively hydroxylated at the ω‐1 position of the butyl side chain. Here, we describe the synthesis and evaluation of derivatives in which the ω‐1 position has been substituted (F, Me, OH) in order to block metabolism. The stability of the compounds was evaluated in human liver microsomes (HLM), and the affinity for A_2AR was determined. Two compounds, (2‐(3,3‐dimethylbutyl)‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐6‐amine ( 3 b ) and 4‐(6‐amino‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐2‐yl)‐2‐methylbutan‐2‐ol ( 3 c ), exhibited good affinity against A_2AR (K_i=0.4 nM and 2 nM , respectively) and high in vitro metabolic stability (89.5 % and 95.3 % recovery, respectively, after incubation with HLM for two hours).     

Microscopic diagnosis of the leaf and stem of Piper solmsianum C.DC

Piper solmsianum C.DC., which is popularly known as pariparoba, is a shrub that measures 1–3 m in height and it inhabits areas with wet tropical soils. The objective of this study was to analyze the leaf and stem anatomy using light microscopy, scanning electron micrographs, and energy‐dispersive X‐ray spectroscopy in order to provide information for species identification. The anatomical profile showed the following main microscopic markers: hypostomatic leaf; hypodermis layer on both sides; pearl glands; biconvex midrib shape; five collateral vascular bundles in open arc with the central bundle larger than the others; circular stem shape; collateral vascular bundles arranged in two rings; sinuous sclerenchymatic sheath in the pith; secretory idioblasts; and starch grains in the mesophyll, in the ground parenchyma of the midrib, petiole, and in the stem; and six morphotypes of calcium oxalate crystals (styloids, cuneiform, tabular crystal rosettes, cuneiform crystal rosettes, elongated square dipyramids, as well as very elongated square dipyramids).     

Neutronic characterization of the MEGAPIE target

The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of about 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). This project is an important step in the roadmap towards the demonstration of the accelerator driven system (ADS) concept and high power liquid metal targets in general. Following the design phase, an experimental program was defined to provide a complete characterization of the facility by performing a “mapping” of the neutron flux at different points, from the center of the target to the beam lines. The neutronic performance of the target was studied using different experimental techniques with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid lead targets used before and after the MEGAPIE experiment.     

Studies on the Susceptibility of Granular Cassava and Corn Starches to Enzymatic Attack. Part 2: Study of the Granular Structure of Starch

The starch granules remaining after enzymatic hydrolysis were analyzed. Enzymatic corrosion efficiency was related to granule diameter. The intrinsic viscosity of enzymatically treated cassava and corn starches was gradually lowered by hydrolysis. X-ray analysis and observation under a polarizing microscope suggested that enzymatic corrosion must occur in amorphous areas of the granules. Scanning electron microscopy showed that, for cassava granules, enzymatic corrosion occured mainly at the surface. Corn starch granules displayed considerable surface corrosion, as well as deep radial corrosion channels.     

Influence of pressure-assisted polymerization on the microstructure and strength of polymer-infiltrated ceramics

A method of manufacturing polymer-infiltrated ceramics (PICs) is to pre-infiltrate a porous ceramic with a liquid monomer and subsequently polymerize the organic component inside the ceramic structure. The volume reduction during polymerization leads to the formation of pores (defects), which has a detrimental effect on the mechanical properties of PICs. To avoid the generation of defects, a new polymerization method that uses pressure during polymerization was developed. To investigate the influences of pressure and heating rate on strength and microstructure, both parameters were varied. The influences of both parameters on the strength of PICs were studied using a biaxial test. The influence on the microstructure was investigated through microscopy. Fracture toughness and R-curve behavior of the manufactured PICs were determined with the SEVNB method. The process parameters have a strong influence on strength and microstructure of PICs. Defect-free PICs with improved strength could be manufactured using elevated pressure during polymerization. As expected, a distinct R-curve behavior and enhanced fracture toughness relative to composites manufactured using conventional methods was found. The developed manufacturing method leads to defectless PICs with increased mechanic behaviors.