Asymmetric Organocatalytic One-Pot, Two-Step Sequential Process to Synthesize Chiral Acetal-Containing Polycyclic Derivatives from Cyclic Hemiacetals and Enones

We have developed an efficient one-pot, two-step sequential process to synthesize biologically and synthetically important chiral acetal-containing polycyclic derivatives. This novel protocol had been proved to proceed via Michael-lactolization-oxocarbenium ion ring-closing sequence, which was initiated by a key reactive enamine intermediate and interrupted the previously established reaction pathway of two different enones used in this work, and generated the corresponding cycloadducts with excellent stereoselectivity bearing up to seven continuous stereocenters. Both chiral and racemic starting cyclic hemiacetals worked well in this strategy. The synthetic applications of the obtained polycyclic products have also been demonstrated

Heterogenization of a macrocyclic cobalt complex for photocatalytic CO₂ reduction

<p>Heterogenization could potentially improve the stability and recyclability of molecular catalysts. In this study, a Co(III) cyclam complex, where cyclam is 1,4,8,11-tetraazacyclotetradecane, was grafted on a mesoporous silica surface via two different covalent linkages. The resulting heterogenized catalysts were characterized with a variety of techniques and tested in photocatalytic CO₂ reduction in the presence of <i>p</i>-terphenyl as a molecular photosensitizer. Linking strategies were shown to be important for the preparation of highly active surface Co(III) sites. In particular, derivatizing one of the amines on the cyclam ligand resulted in a detrimental effect on the activity of the molecular Co(III) catalyst. Improved activity was achieved by reacting the Co(III) catalyst with surface silanol groups, forming Si–O–Co linkages. A catalyst loading effect was observed, where the best catalytic activity was achieved when the surface Co(III) sites likely formed a monolayer in silica mesopores. Our results also indicate that the cyclam ligand was essential for the observed activity using the heterogenized Co(III) catalysts.</p

Patients with familial chylomicronemia syndrome (FCS) have disproportional FC and CE levels in plasma.

<p>TG levels (A), cholesterol levels (B) and the FC/CE ratio (C) in plasma of healthy subjects (Ctrl), in FCS patients’ whole plasma (FCS-W), and in chylomicron-depleted FCS plasma (FCS-CD). (D) A linear regression analysis of the FC/CE ratio and plasma TG levels (n = 4 in control group and n = 5 in FCS-W and FCS-CD groups). (E) LCAT activity in healthy subjects’ and FCS-CD plasma (n = 5 in control group and n = 6 in FCS-CD group). Results are mean±s.e.m.; *P<0.05, **P<0.01 and ***P<0.001 (Student’s t-test).</p

Synthesis of (4-Hexyloxybenzoyl)butylsaure Methyl Amide/Poly(3-hexylthiophene) Heterojunction Nanowire Arrays

Large-area P–N heterojunction organic semiconductor nanowire combined (4-hexyloxybenzoyl)­butylsaure methyl amide (H-<i>t</i>-B) and Poly (3-hexylthiophene) (P3HT) were fabricated and the morphology and photoelectric properties were investigated by the growth of composition. The performance of light on/off switching of the H-<i>t</i>-B/P3HT heterojunction nanowire arrays was measured by the light irradiation on and off, the current in the devices showed two distinct states, the current was only 0.34 μA in the dark, while the current can reach 1.37 μA under the illumination of 45 mW/cm². The on/off switching ratio for the device of the heterojunction nanowire arrays is about 4.03

Media 2: Optical switch based on tunable aperture

Originally published in Optics Letters on 15 August 2012 (ol-37-16-3306

Reducing hypertriglyceridemia does not correct the FC/CE ratio.

<p>Plasma TG levels (A), cholesterol levels (B) and the FC/CE ratio (C) in WT, <i>apoc2</i> mutants and the <i>apoc2</i> mutants fed a low fat diet (LFD). Results are mean±s.e.m.; n = 3 in each group; *P<0.05, ***P<0.001 (Student’s t-test).</p

Expression of <i>lcat</i>, but not <i>cetp</i>, is significantly decreased in <i>apoc2</i> mutant zebrafish.

<p>In situ hybridization (A) and qPCR (B) results showing <i>lcat</i> and <i>cetp</i> mRNA expression in 5.3 dpf zebrafish embryos. mRNA expression of <i>apoc2</i>, <i>lcat</i> and <i>cetp</i> (C) and <i>apoa1</i>, <i>apoe</i>, <i>apob</i> and <i>mtp</i> (D) in adult zebrafish liver. Results are mean±s.e.m.; numbers of biological replicates are indicated on the graphs; *P<0.05, **P<0.01 and ***P<0.001 (Student’s t-test).</p

Media 1: Optical switch based on tunable aperture

Originally published in Optics Letters on 15 August 2012 (ol-37-16-3306

The development of violinism in the Slovene lands until the beginning of the Second World War

Composite polyelectrolyte multilayers of chitosan and low molecular weight poly­(acrylic acid) (PAA) have been assembled by sequential adsorption as a first step toward building a surface anchored chitosan gel. Silane chemistry was used to graft the first chitosan layer to prevent film detachment and decomposition. The assembly process is characterized by nonlinear growth behavior, with different adsorption kinetics for chitosan and PAA. In situ analysis of the multilayer by means of surface sensitive total internal reflection Raman (TIRR) spectroscopy, combined with target factor analysis of the spectra, provided information regarding composition, including water content, and ionization state of weak acidic and basic groups present in the thin composite film. Low molecular weight PAA, mainly in its protonated form, diffuses into and out of the composite film during adsorption and rinsing steps. The higher molecular weight chitosan shows a similar behavior, although to a much lower extent. Our data demonstrate that the charged monomeric units of chitosan are mainly compensated by carboxylate ions from PAA. Furthermore, the morphology and mechanical properties of the multilayers were investigated in situ using atomic force microscopy operating in PeakForce tapping mode. The multilayer consists of islands that grow in lateral dimension and height during the build-up process, leading to close to exponentially increasing roughness with deposition number. Both diffusion in and out of at least one of the two components (PAA) and the island-like morphology contribute to the nonlinear growth of chitosan/PAA multilayers

Enhanced Bromate Formation during Chlorination of Bromide-Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid

Bromate (BrO₃^–) in drinking water is traditionally seen as an ozonation byproduct from the oxidation of bromide (Br^–), and its formation during chlorination is usually not significant. This study shows enhanced bromate formation during chlorination of bromide-containing waters in the presence of cupric oxide (CuO). CuO was effective to catalyze hypochlorous acid (HOCl) or hypobromous acid (HOBr) decay (e.g., at least 10⁴ times enhancement for HOBr at pH 8.6 by 0.2 g L^–1 CuO). Significant halate concentrations were formed from a CuO-catalyzed hypohalite disproportionation pathway. For example, the chlorate concentration was 2.7 ± 0.2 μM (225.5 ± 16.7 μg L^–1) after 90 min for HOCl (<i>C</i>_o = 37 μM, 2.6 mg L^–1 Cl₂) in the presence of 0.2 g L^–1 CuO at pH 7.6, and the bromate concentration was 6.6 ± 0.5 μM (844.8 ± 64 μg L^–1) after 180 min for HOBr (<i>C</i>_o = 35 μM) in the presence of 0.2 g L^–1 CuO at pH 8.6. The maximum halate formation was at pHs 7.6 and 8.6 for HOCl or HOBr, respectively, which are close to their corresponding p<i>K</i>_a values. In a HOCl–Br^––CuO system, BrO₃^– formation increases with increasing CuO doses and initial HOCl and Br^– concentrations. A molar conversion (Br^– to BrO₃^–) of up to (90 ± 1)% could be achieved in the HOCl–Br^––CuO system because of recycling of Br^– to HOBr by HOCl, whereas the maximum BrO₃^– yield in HOBr–CuO is only 26%. Bromate formation is initiated by the formation of a complex between CuO and HOBr/OBr^–, which then reacts with HOBr to generate bromite. Bromite is further oxidized to BrO₃^– by a second CuO-catalyzed process. These novel findings may have implications for bromate formation during chlorination of bromide-containing drinking waters in copper pipes