Luminaolide, a novel metamorphosis-enhancing macrodiolide for scleractinian coral larvae from crustose coralline algae

A new metamorphosis-enhancing macrodiolide, luminaolide (1), was isolated from the crustose coralline algae (CCA) Hydrolithonreinboldii. Its structure was determined by spectroscopic analysis. A fraction (1.30 μg/mL) eluted with 80% aqueous MeOH by ODS gel column chromatography of the same CCA extract induced larval metamorphosis (25.9 ± 7.4%) against Leptastrea purpurea, and its metamorphosis-inducing activity was further enhanced to 92.6 ± 2.9% with the addition of 1 (25.6 ng/mL).     

Capacitance response of double-walled carbon nanotubes depending on surface modification

The capacitive behaviors of high-purity double-walled carbon nanotubes (DWNTs) were investigated before and after oxidation using nitric acid (HNO₃). The electrodes prepared from the HNO₃-oxidized DWNTs have exhibited higher capacitances than the pristine nanotube electrode in both aqueous and non-aqueous systems, despite the deterioration of their specific surface area after HNO₃ oxidation. The superiority of the HNO₃-oxidized DWNTs in capacitance properties is caused by the variations of surface wettability and the interstitial pore structure of nanotube bundles, which result from the introduction of polar oxygen functional groups onto the nanotube surface by HNO₃ oxidation.     

Superhydrophobic effects of self-assembled monolayers on micropatterned surfaces: 3-D arrays mimicking the lotus leaf

The contact angle of water has been measured on a series of self-assembled monolayers (SAM) on thermally evaporated and sputter coated silver surfaces. It is found that micropatterning the surface using nanosphere lithography leads to large increases in the contact angle and generates superhydrophobic surfaces with contact angles >150 degrees. The type of functional groups on the SAMs, the metal island size, and the metal island thickness all contribute to the measured contact angle. The maximum contact angle found was 161 degrees for a fluorinated alkanethiol on 80 nm thick silver islands.     

Improved ruthenium catalysts for Z-selective olefin metathesis

Several new C-H-activated ruthenium catalysts for Z-selective olefin metathesis have been synthesized. Both the carboxylate ligand and the aryl group of the N-heterocyclic carbene have been altered and the resulting catalysts evaluated using a range of metathesis reactions. Substitution of bidentate with monodentate X-type ligands led to a severe attenuation of metathesis activity and selectivity, while minor differences were observed between bidentate ligands within the same family (e.g., carboxylates). The use of nitrato-type ligands in place of carboxylates afforded a significant improvement in metathesis activity and selectivity. With these catalysts, turnover numbers approaching 1000 were possible for a variety of cross-metathesis reactions, including the synthesis of industrially relevant products.     

Monitoring the brain metabolites of children with acute encephalopathy caused by the H1N1 virus responsible for the 2009 influenza pandemic: a quantitative in vivo H MR spectroscopy study

Background and Purpose

Influenza viral infection, which results in central nervous system dysfunction, is a major cause of acute encephalopathy (AE). The purpose of this study was to investigate the changes in the concentrations of brain metabolites in children with AE using single-voxel magnetic resonance spectroscopy (MRS) and to provide diagnostic information about the relationship between the symptoms of AE and metabolite concentrations.

Materials and Methods

The subjects were 10 children (mean age: 6.2 years; range: 1–13) with AE caused by the novel influenza A virus responsible for the 2009 influenza pandemic. The serial MRS data (TE/TR=30/5000 ms, 3 T) acquired from the basal ganglia (BG) and centrum semiovale (CS) of each patient were categorized into three periods: (1) initial neurological symptom presentation and the start of treatment (n= 10), (2) short-term follow-up (n= 9) and (3) long-term follow-up (n= 3). As controls, the magnetic resonance (MR) spectra of eight age-matched children were also investigated.

Results

In both regions, the concentrations of the major metabolites (N-acetylaspartate, creatine, choline, myo-inositol, glutamate/glutamine complex and glutamate) only showed minor fluctuations between the three periods. On the other hand, higher levels of taurine (Tau) were observed in the BG during the second period (P=.005), and increased levels of glucose were observed in the CS during the first (P=.005) and second (P=.036) periods.

Conclusions

Serial monitoring of brain metabolite changes was carried out with a clinical MR system. The concentrations of major metabolites only displayed very minor fluctuations in response to mild H1N1-related AE. However, a higher Tau concentration was found to be associated with neurological symptoms. Further studies are required to improve our understanding of the detailed activity of Tau in AE.     

Magnetic properties of Mn-rich Rh2Mn1+xSn1−x Heusler alloys

X-ray powder diffraction and magnetization measurements have been carried out on Rh₂Mn_1+xSn_1−x (0≤x≤0.3) alloys. The alloys, which crystallize in the L2₁ structure, were found to exhibit ferromagnetic behavior. The lattice constant a at room temperature decreases with increasing x, whereas the Curie temperature T_C decreases linearly. At 5 K the magnetic moment per formula unit first increases with increasing x and then saturates for x≥0.2. The experimental results are discussed in terms of the influence of the Mn-Mn exchange interactions between the Mn atoms on the Sn and Mn sites.     

Kinetic investigation on carbamate formation from the reaction of carbon dioxide with amino acids in homogeneous aqueous solution

The kinetics of carbamate formation from the reaction of carbon dioxide with α‐amino acids in D₂O was first investigated by means of nuclear magnetic resonance spectroscopy. Potassium carbonate was used as the CO₂ source. For each amino acid, the maximum carbamate yield, the apparent rate constant for the carbamate formation k_app, and the rate constants for the formation k₁ and the breakdown k_?1 of the carbamate were estimated. Plots of log k₁ or log k_?1 versus pK_a of amino acids indicated that the formation rate k₁ increased with the basicity (pK_a) of amino acid, while the decomposition rate k_?1 decreased. A Br?nsted β value of 0.39 was obtained from the former plot, being in good agreement with the previously reported ones (0.26–0.43). The observed negative pK_a dependence of log k_?1 (Br?nsted α = 0.34) is reasonable, because the carbamate decomposition is acid‐catalyzed and the steady‐state concentration of H⁺ should be higher for weaker basic amines. The charge (σ) and the lone‐pair energy (E_N) at the nitrogen atom of the amino group were calculated. Although log k₁ correlated with σ and E_N, log k_?1 was unrelated with both of these parameters. Considering that the carbamate formation (k₁) is not only base‐catalyzed but should also be promoted by the nucleophilicity of the amino nitrogen, its correlation with σ and E_N in addition to pK_a is rational. The irrelevance of log k_?1 to σ and E_N is not surprising, because σ and E_N are not a direct measure of [H⁺] of the solution. Copyright © 2011 John Wiley & Sons, Ltd.     

Indication of reactor ν(e) disappearance in the Double Chooz experiment

The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio of events of 0.944±0.016(stat)±0.040(syst) was obtained in 101 days of running at the Chooz nuclear power plant in France, with two 4.25 GW(th) reactors. The results were obtained from a single 10 m(3) fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 flux measurement after correction for differences in core composition. The deficit can be interpreted as an indication of a nonzero value of the still unmeasured neutrino mixing parameter sin(2)2θ(13). Analyzing both the rate of the prompt positrons and their energy spectrum, we find sin(2)2θ(13)=0.086±0.041(stat)±0.030(syst), or, at 90% C.L., 0.017相似文献   

Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition

Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2+2+2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2+2+2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured.