Bioactive C15 acetogenins from the red alga Laurencia obtusa

The petroleum ether extract of the red alga Laurencia obtusa afforded three new C(15) acetogenins (cyclic ether enyne): (12Z)-cis-maneonene-D (1), (12E)-cis-maneonene-E (2), and (12Z)-trans-maneonene-C (3), along with one known cis-maneonene-A (4). Blood neutrophils were prepared, cultured, and incubated for 24, 48, and 72 h in medium with and without isolated compounds. Blood neutrophils were prepared, cultured, and incubated for 24, 48 and 72 h in medium with and without the isolated compounds. Both morphology and DNA fragmentation methods assessed the percentage of neutrophils apoptosis in each culture. In the present study, several observations have been made concerning the apoptosis-inducing or inhibiting effect of 1 and 2. Both compounds had no inhibition of apoptosis but apoptosis was enhanced significantly by aging. However, 1 stimulated apoptosis of normal only at the initial 24 h. After that there was no significant difference in apoptosis with or without compound 1, while 2 stimulated apoptosis at all the times. The apoptosis induced by these two compounds was demonstrated by DNA fragmentation assay and microscopic observation. These observations suggest that compounds 1 and 2 may be involved in regulation of programmed death in the initiation and propagation of inflammatory responses.     

Hydrogen bonded supramolecular polymers in moderately polar solvents

Hydrogen bonded assemblies are usually decomposed by polar organic solvents. However, we have succeeded in preparing a strongly associated supramolecular polymer which forms viscous solutions in competitive solvents such as tetrahydrofuran.     

Diversity-oriented synthesis of a library of substituted tetrahydropyrones using oxidative carbon-hydrogen bond activation and click chemistry

Eighteen (2RS,6RS)-2-(4-methoxyphenyl)-6-(substituted ethyl)dihydro-2H-pyran-4(3H)ones were synthesized via a DDQ-mediated oxidative carbon-hydrogen bond activation reaction. Fourteen of these tetrahydropyrans were substituted with triazoles readily assembled via azide-alkyne click-chemistry reactions. Examples of a linked benzotriazole and pyrazole motif were also prepared. To complement the structural diversity, the alcohol substrates were obtained from stereoselective reductions of the tetrahydropyrone. This library provides rapid access to structurally diverse non-natural compounds to be screened against a variety of biological targets.     

Novel photoconductive Ag/nanostructure ruthenium oxide/p-type silicon Schottky barrier diode by sol–gel method

A new Schottky photodiode of Ag/RuO₂/p-Si/Al was successfully fabricated using spin-coating technique. The ruthenium oxide (RuO₂) nanoparticles with an average size of 8 nm were synthesized using a sol–gel method. The crystal structure and morphology of the synthesized RuO₂ were analyzed by means of X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and selective area electron diffraction. The rectification ratio of the diode was found to be 112 at ±2 V. The ideality factor and barrier height values of the Ag/RuO₂/p-Si/Al diode were obtained to be 1.47 and 0.55 eV, respectively. The Cheung–Cheung and Norde’s models were used to determine the diode parameters. The photoresponse behavior of the fabricated Ag/RuO₂/p-Si/Al diode was studied under various illumination intensities. The transient photocurrent results indicate that photocurrent under illumination is higher than the dark current and this indicates that the fabricated diode behaves as a photodiode. The capacitance–voltage–frequency measurements indicate that the capacitance of the diode depends on voltage and frequency. The obtained results suggest that the new Ag/RuO₂/p-Si/Al diode can be used an optical switching device for optical sensor applications and are also expected to be generated in the future study.     

Optical model analysis of p+6He scattering over a wide range of energy

Optical-model analysis of proton elastic scattering from ⁶He has been carried out for eight sets of elastic scattering data at energies, 24.5, 25.0, 36.2, 38.3, 40.9, 41.6, 71.0 and 82.3 MeV/n respectively. The vector analyzing power and differential cross section for the elastic scattering of ⁶He nucleus from polarized protons at 71 MeV have been analyzed in the framework of the optical model potentials. The data are, first, analyzed in term of phenomenological potentials using the Woods-Saxon form for the real and imaginary parts supplemented by a spin-orbit potential of Thomas form. The analysis has been also performed using microscopic complex potentials.     

绿色可磁性分离二氧化硅包裹镍铁尖晶石负载硫酸氢铁纳米粒子催化剂用于合成1,8-二氧十氢吖啶合成(英文)

A new magnetically separable catalyst consisting of ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles was prepared.The synthesized catalyst was characterized using vibrating sample magnetometry,X-ray diffraction,transmission electron microscopy,scanning electron microscopy,and Fourier transform infrared spectroscopy.This new magnetic catalyst was shown to be an efficient heterogeneous catalyst for the synthesis of 1,8- dioxodecahydroacridines under solvent-free conditions.The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.     

Novel bulk synthesis of magnesium oxide nanobelts networks by microwave hydrothermal route

Novel magnesium oxide (MgO) nanobelt structures were successfully synthesized on a large scale, low cost and catalyst free by a microwave hydrothermal route using the magnesium metal and potassium hydroxide precursors at 200 °C for 10 min. The synthesized MgO nanobelts were systemically characterized by power X-ray diffraction (XRD), scanning electron microscopy, energy dispersion spectroscopy and transmission-high resolution electron microscopy. The XRD results indicate that the MgO nanobelts have the well-crystalline cubic phase. The detailed morphological studies revealed that the synthesized products were nanobelts and were grown in large quantity. The optical energy gap of MgO nanobelts was found to be 3.1 eV. The photoluminescence spectra of the MgO nanobelts show a strong and broad green emission band, a weak ultraviolet emission band, and a weak red emission band. This novel method will open new dimensions for synthesized 1-D metal oxide and can be easily extended to the synthesis and assembly of other inorganic nanocrystals.     

Total Lipid Extraction of Food Using d-Limonene as an Alternative to n-Hexane

A useful and green method for the extraction of fats and oils with a new procedure combining Soxhlet extraction and Clevenger distillation using d-limonene (bio-solvent) as a substitute for n-hexane (petroleum solvent) is reported. This method using green solvent is a laboratory exercise which easily teaches fundamental green analytical chemical lessons and successfully incorporates green “analytical chemistry” into the teaching and the research laboratory to both developed and developing nations.     

Microwave hydrodiffusion and gravity, a new technique for extraction of essential oils

A new process design and operation for the extraction of essential oils was developed. Microwave hydrodiffusion and gravity (MHG) is a combination of microwaves for hydrodiffusion of essential oils from the inside to the exterior of biological material and earth gravity to collect and separate. MHG is performed at atmospheric pressure without adding any solvent or water. MHG has been compared with a conventional technique, hydrodistillation (HD), for the extraction of essential oil from two aromatic herbs: spearmint (Mentha spicata L.) and pennyroyal (Mentha pulegium L.) belonging to the Labiatae family. The essential oils extracted by MHG for 15 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional hydrodistillation for 90 min. MHG also prevents pollution through potential 90% of energy saved which can lead to greenhouse gas emission benefits.     

Convergence of Inverse Power Method for First Eigenvalue of p-Laplace Operator

In this article, convergence of an iterative scheme to approximate the first eigenfunction and related eigenvalue for p-Laplace operator is shown. Moreover, numerical examples are presented that show the e?ciency and accuracy of the algorithm.