Heritability of Stroop and flanker performance in 12-year old children

Background  

There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks.     

Designing of dipeptide‐based oligoconjugates as potential carrier for drug delivery. Pyroglutamil‐S‐glutamic acid bisoligo‐3‐hydroxybutyrates

In the present article, we describe the synthesis and characterization of conjugates based on pyroglutamyl‐S‐glutamic acid and bisoligo‐[R,S]‐3‐hydroxybutyrates (PyGlu‐S_‐Glu_bisOHB) using anionic ring opening polymerization of β‐butyrolactone with a dipeptide bearing two carboxylate groups as potassium salt. The results indicated that the above‐mentioned reaction is accompanied of oligomerization of β‐butyrolactone yielding (3‐hydroxybutyrates) oligomers with crotonate and carboxyl end groups. We report also the end group analysis of the synthesized conjugates using electrospray ionization tandem mass spectrometry (ESI‐MS), the latter confirmed the presence of a mixture of dipeptide conjugate with β‐butyrolactone oligomer chain and β‐butyrolactone homopolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4103–4111, 2008     

Synthesis of ionic polyurethanes with pyrene rings: Spectral properties and fluorescence quenching study

Hydrophilic ionic polyurethanes with 4‐chloromethylphenylcarbamoyl‐1‐oxymethylpyrene located on the quaternary ammonium structure from a polymer based on poly(ethylene glycol), isophorone diisocyanate, and N‐methyldiethanolamine were prepared by a quaternization reaction, in which the amount of pyrene covalently attached to the polymeric backbone ranged from 1.14 to 19.82 mmol of fluorophore/100 g of polymer. It was interesting to compare the photoluminescence of the pyrene polyurethane carrying a few mole percent of pyrene moieties with that of a third polymer resulting from its subsequent quaternization with benzyl chloride up to a concentration of ionic groups as in the latter (quaternization degree = 14.15%). The process of excimer formation between the pyrene molecules attached to the ionic polyurethane was investigated in tetrahydrofuran (THF), dimethylformamide, film, and THF/H₂O to illustrate the expected differences in the polymer behavior compared with that of the starting pyrene derivative. The formation of aggregates or core–shell micelles was sustained by the fluorescence data, which indicated the existence of pyrene units in the ground state of the molecule, giving rise thus to an explanation for the high excimer‐to‐monomer intensity ratio. The fluorescence decay of pyrene polyurethanes in the presence of various concentrations of nitrobenzene used as a quencher was analyzed too when the fluorescence quenching in the polymer solution normally followed Stern–Volmer kinetics. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3945–3956, 2005     

Triazene UV-triggered photogeneration of silver/gold nanoparticles in block copolymer templates

Journal of Nanoparticle Research - Synthesis of yttrium oxide nanoparticles in a specially designed radio frequency thermal plasma reactor is reported. Good crystallinity, narrow size distribution,...     

Synthesis and properties of new photosensitive triazene polyacrylates

1‐(Phenyl)‐3‐(2‐acryloyloxyethyl)‐3‐methyl triazene‐1 (M1) and 1‐(p‐nitrophenyl)‐3‐(2‐acryloyloxyethyl)‐3‐methyl triazene‐1 (M2) were synthesized to study the substituent effect of the triazene unit on the copolymerization with methyl methacrylate (MMA). From the ¹H NMR spectra of the resulting copolymers, their compositions were determined to be 1:3.18 M1/MMA and 1:2.45 M2/MMA, respectively. The polymers were examined with respect to their structure, thermal properties, and surface morphology. The influence of the triazene structure on the photosensitive properties of the copolymers exposed to ultraviolet/laser irradiation was also investigated and compared with that of the parent derivatives. The copolymer containing the phenyl triazene chromophore as the photochemically most active group exhibited a low threshold of ablation and a high etching rate for fluences under 400 mJ cm^?2. Scanning electron microscopy images confirm the formation of ablated craters more clearly in the copolymer made with M1, for which the thermal effects of the ablation mechanism were visible only with 2500× magnification. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5271–5282, 2006     

Synthesis and characterization of poly [N-acryloyl-(D/L), (+/−)-phenylalanine-co-(D/L), (−/+)N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)] copolymers

Two monomers of (D/L), (+/?)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea) methacrylate (D/L-MABU) type were prepared and further polymerized through free radical polymerization with optically active monomers containing phenylalanine sequences such as N-acryloyl-(D/L), (?/+)-phenylalanine (A-D/L-Phe). The resulting copolymers, i.e., poly[N-acryloyl-(D/L), (?/+)-phenylalanine-co-(D/L), (+/?)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)], A-D/L-Phe-co-D/L-MABU, were characterized by FT-IR, 1D/2D NMR (¹H and ¹³C), UV-vis, and circular dichroism (CD) spectroscopies, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The copolymers obtained with a molar fraction of 0.76: 0.24 / 0.64: 0.36 monomer units had optical rotation values of ?25° and +15°, respectively. Upon chemical modification of the phenylalanine-based copolymers with fluorescein-isothiocyanate, new fluorescent copolyacrylates (A-D/L-Phe-co-D/L-MABU-F) were synthesized and further studied for pH measurements in DMF solutions using HCl and NaOH 10^?1M. It was found that sterioselectivity of the A-L-Phe-co-L-MABU-F copolymer is higher than of its dextro-form, especially at basic pH.      

Synthesis of block copolymers derived from N-trityl-(S)-serine and pyrene end-labeled poly(methyl methacrylate) or poly(N-isopropylacrylamide) via ATRP

A new monomer bearing N-trityl-l-serine methyl ester in structure, methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine (MTS), was prepared to be further polymerized by atom transfer radical polymerization (ATRP) with pyrene-endcapped poly(methyl methacrylate) (Py–PMMA–Br) or poly(N-isopropylacrylamide) (Py–PNIPA–Br). The resulting block copolymers, poly(methyl methacrylate–block–methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine) (Py–PMMA–b–PMTS) and poly(N-isopropylacrylamide–block–methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine (Py–PNIPA–b–PMTS) were characterized by ¹H (¹³C) NMR, ultraviolet, FTIR and fluorescence spectroscopy, thermal analysis, differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), and gel permeation chromatography (GPC) measurements. The chemical composition in Py–PMMA–b–PMTS was estimated from the ¹H NMR analysis that indicated a ratio of the repeating units of 46:19 (MMA:MTS). For the Py–PNIPA–b–PMTS the composition rate in the copolymer was 61:25 (NIPA:MTS). Quenching of the pyrene species with N,N-diethylaniline, nitrobenzene, nitrophenol, potassium iodide, p-nitrotoluene and tetracyanoquinodimethane (TCNQ) in DMF solution excited at 348 nm was evidenced, more efficiently being nitrophenol and TCNQ. In this case, the monomer emission at 388–409 nm underwent a significant decrease caused of an electron transfer from the electron-reach photoexcited pyrene molecule to the electron-deficient quenchers.     

Copolyacrylates with phenylalanine and anthracene entities prepared by ATRP and microwave irradiation

In this study, two amino acid copolymers containing anthracene incorporated either on the one end, poly(N-acryloyl-l-phenylalanine-co-methyl methacrylate)-1 or as pendant groups, poly-(N-acryloyl-l-phenylalanine-co-methyl methacrylate)-2 were prepared directly from N-acryloyl-l-phenylalanine (APhe) and methyl methacrylate (MMA) through atom transfer radical polymerization (ATRP) and microwave-assisted synthesis. In the first case, 9-(chloromethyl)anthracene was used as an ATRP-initiator to obtain a copolymer that contains amino acid sequences and anthracene end-capped units (0.03 molar fraction). Rapid synthesis of copolymer under microwave irradiation (250 W) in the presence of 1,1′-azobis(cyclohexanecarbonitrile) used as an initiator was followed of a functionalization of the formed copolymer with an anthracene derivative yielding copolyacrylate with pendant anthracene (0.02 molar fraction). The structure of the copolymers was verified by ¹H NMR, UV-Vis and FTIR spectroscopy, gel permeation chromatography (GPC), and fluorescence spectroscopy. The fluorescence quenching process of anthracene which exists in copolymers by FeCl₃, cobalt acetate, nitrobenzene, maleic anhydride, diethylaniline and nitromethane in DMF solutions shows that this involves an electron transfer between the excited state anthracene and the present transitional metal cations, more efficiently being FeCl₃ for poly-(APhe-co-MMA)-1 and cobalt acetate for the latter copolymer.     

Preparation of photocrosslinked sol‐gel composites based on urethane‐acrylic matrix,silsesquioxane sequences,TiO2, and Ag/Au Nanoparticles for use in photocatalytic applications

An acid urethane oligodimethacrylate based on poly(ethylene glycol) was synthesized and used in the preparation of hybrid composites containing silsesquioxane sequences and titania domains formed through sol‐gel reactions along with silver/gold nanoparticles (Ag/Au NPs) in situ photogenerated during the UV‐curing process. The photopolymerization kinetics studied by Fourier transform infrared spectroscopy and photoDSC showed that the photoreactivity of the investigated formulations depends on the amount of titanium butoxide (5–20 wt %) added in the system subjected to UV irradiation. The introduction of 1 wt % AgNO₃/AuBr₃ in formulations slightly improved the degree of conversion but diminished the polymerization rates. The formation of hybrid materials comprising predominantly amorphous TiO₂/SiO₂ NPs, with or without Ag/Au NPs, was confirmed through specific analyses. The evaluation of photocatalytic activity demonstrated that the synthesized hybrid films are suitable for the complete removal of organic pollutants (phenolic compounds) from water under UV irradiation (200–350 min) at low intensity (found in the solar radiation). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1189–1204