Diethyl 1‐(4‐fluoro­phenyl)‐3‐(2‐furyl)‐5‐oxopyrrolidine‐2,2‐di­carboxyl­ate and diethyl 1‐(3,4‐di­chloro­phenyl)‐3‐(2‐furyl)‐5‐oxopyrrolidine‐2,2‐di­carboxyl­ate

The title compounds, C₂₀H₂₀FNO₆ and C₂₀H₁₉Cl₂NO₆, respectively, may exhibit bioactivity. In these compounds, the pyrrolidine ring adopts a conformation intermediate between envelope and half‐chair. Only one of the two ethoxy­carbonyl side chains is nearly planar. Centrosymmetric pairs are formed, and the crystal structure is stabilized by weak C—H⋯O hydrogen bonds and van der Waals interactions.     

Natural Compounds Isolated from Stachybotrys chartarum Are Potent Inhibitors of Human Protein Kinase CK2

A large number of secondary metabolites have been isolated from the filamentous fungus Stachybotrys chartarum and have been described before. Fourteen of these natural compounds were evaluated in vitro in the present study for their inhibitory activity towards the cancer target CK2. Among these compounds, stachybotrychromene C, stachybotrydial acetate and acetoxystachybotrydial acetate turned out to be potent inhibitors with IC₅₀ values of 0.32 µM, 0.69 µM and 1.86 µM, respectively. The effects of these three compounds on cell proliferation, growth and viability of MCF7 cells, representing human breast adenocarcinoma as well as A427 (human lung carcinoma) and A431 (human epidermoid carcinoma) cells, were tested using EdU assay, IncuCyte^® live-cell imaging and MTT assay. The most active compound in inhibiting MCF7 cell proliferation was acetoxystachybotrydial acetate with an EC₅₀ value of 0.39 µM. In addition, acetoxystachybotrydial acetate turned out to inhibit the growth of all three cell lines completely at a concentration of 1 µM. In contrast, cell viability was impaired only moderately, to 37%, 14% and 23% in MCF7, A427 and A431 cells, respectively.     

1/fα fractal noise generation from Grünwald–Letnikov formula

This communication presents a recursive algorithm for generating streams of 1/f^α fractal noise, by means of fractional integration/differentiation of a white noise signal. The quality of correlated and anticorrelated noise obtained by this approach is evaluated by applying detrended fluctuation analysis.     

Effect of Reaction Temperature on the Gel Content of Acrylic Latexes

The effect of reaction temperature on the kinetics and the microstructure properties of polyacrylates produced by seeded semicontinuous emulsion homopolymerization of two acrylate monomers (butyl acrylate and 2‐ethylhexyl acrylate) initiated by a thermal initiator was investigated. Contrary to what has been reported at higher temperatures (75–95 °C), increasing reaction temperature (from 60 to 80 °C) led to a decrease of the amount of gel content produced in the semicontinuous polymerizations. These results were analyzed by means of a Monte‐Carlo model of the process.

     

Optimization of clean-up procedure for patulin determination in apple juice and apple purees by liquid chromatography

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by several fungal species that can be carried into industrial apple juice by-products during factory processing. An analytical method for determination of PAT in apple juice and another one for determination of this compound in apple purees and apple compotes by liquid chromatography are proposed in the present paper. These methods have better precision and sensitivity than previously reported methods and focus mainly on extraction and clean-up. To accomplish analytical methods with higher accuracy, lower limits of detection and simpler procedures for application in quality control of the goods, different extraction and clean-up procedures for PAT were comparatively studied. PAT recoveries in apple juice spiked with 1.0 mg PAT/kg varied between 52.3% and 81.0%. The highest PAT recovery in apple puree spiked with 0.1 mg PAT/kg was 82.9%. Addition of NaH₂PO₄ during the extraction phase here reported for the first time has the advantage of keeping the pH slightly acidic, thus avoiding PAT degradation.     

Multidimensional chromatography in food analysis

In this work, the main developments and applications of multidimensional chromatographic techniques in food analysis are reviewed. Different aspects related to the existing couplings involving chromatographic techniques are examined. These couplings include multidimensional GC, multidimensional LC, multidimensional SFC as well as all their possible combinations. Main advantages and drawbacks of each coupling are critically discussed and their key applications in food analysis described.     

Adsorption of cadmium and lead onto oxidized nitrogen-doped multiwall carbon nanotubes in aqueous solution: equilibrium and kinetics

Nitrogen-doped multiwall carbon nanotubes (CNx) were chemically oxidized and tested to adsorb cadmium and lead from aqueous solution. Physicochemical characterization of carbon nanotubes included morphological analysis, textural properties, and chemical composition. In addition, the cadmium adsorption capacity of oxidized-CNx was compared with commercially available activated carbon and single wall carbon nanotubes. Carboxylic and nitro groups on the surface of oxidized CNx shifted the point of zero charge from 6.6 to 3.1, enhancing their adsorption capacity for cadmium and lead to 0.083 and 0.139 mmol/g, respectively, at pH 5 and 25 °C. Moreover, oxidized-CNx had higher selectivity for lead when both metal ions were in solution. Kinetic experiments for adsorption of cadmium showed that the equilibrium was reached at about 4 min. Finally, the small size, geometry, and surface chemical composition of oxidized-CNx are the key factors for their higher adsorption capacity than activated carbon.     

Multiplexed Immunosensing Platform Coupled to Hybridization Chain Reaction for Electrochemical Determination of MicroRNAs in Clinical Samples

There is an urgent need for development of rapid and inexpensive techniques for detection of microRNAs (miRNAs), which are potential biomarkers of various types of cancer. In this paper, we describe a multiplexed electrochemical platform for determination of three cancer‐relevant miRNAs: miR‐21, let‐7a and miR‐31. The strategy combines the use of magnetic beads (MBs) modified with a commercial antibody for the efficient capture of the heteroduplexes formed by hybridization of the target miRNA with DNA probe. Free non‐hybridized region of the DNA probe was thereafter hybridized with two biotin‐labeled auxiliary DNA probes in a process of hybridization chain reaction (HCR), resulting in a long hybrid bearing a large number of biotin molecules. Labeling of these multiple biotin units with streptavidin‐peroxidase conjugates allowed an amplification of the amperometric signal measured after capturing the modified MBs at a screen‐printed carbon electrode array of eight electrodes. The combined strategy demonstrated in a similar assay time significantly higher sensitivity than those previously described using modified MBs with the same capture antibody (without amplification by HCR) or a HCR strategy implemented on the surface of MBs, respectively. The methodology exhibits a good selectivity for discriminating single mismatches and was applied to the determination of the three target miRNAs in total RNA (RNA_t) extracted from various cancer cell lines and from cervical precancerous lesions.     

Real‐Time Interrogation of Aspirin Reactivity,Biochemistry, and Biodistribution by Hyperpolarized Magnetic Resonance Spectroscopy

Hyperpolarized magnetic resonance spectroscopy enables quantitative, non‐radioactive, real‐time measurement of imaging probe biodistribution and metabolism in vivo. Here, we investigate and report on the development and characterization of hyperpolarized acetylsalicylic acid (aspirin) and its use as a nuclear magnetic resonance (NMR) probe. Aspirin derivatives were synthesized with single‐ and double‐¹³C labels and hyperpolarized by dynamic nuclear polarization with 4.7 % and 3 % polarization, respectively. The longitudinal relaxation constants (T₁) for the labeled acetyl and carboxyl carbonyls were approximately 30 seconds, supporting in vivo imaging and spectroscopy applications. In vitro hydrolysis, transacetylation, and albumin binding of hyperpolarized aspirin were readily monitored in real time by ¹³C‐NMR spectroscopy. Hyperpolarized, double‐labeled aspirin was well tolerated in mice and could be observed by both ¹³C‐MR imaging and ¹³C‐NMR spectroscopy in vivo.