Corosolic acid isolated from the fruit of Crataegus pinnatifida var. psilosa is a protein kinase C inhibitor as well as a cytotoxic agent

We report a case of left-sided hydronephrosis and ureteropelvic urinary extravasation due to a large left iliac artery aneurysm. Urinoma was diagnosed preoperatively by contrast-enhanced computed tomography. The patient was successfully treated by percutaneous nephrostomy and ureteral double J stent placement followed by staged operative repair.     

Tissue levels of malondialdehyde after passive smoke exposure of rats for a 24-week period.

The present study was to evaluate the effects of chronic cigarette smoke exposure on lipid peroxidation in various organ tissues. Sprague-Dawley rats were exposed to passive smoking 2 hr per day, 6 days per week (Monday-Saturday), for 24 weeks. Malondialdehyde levels, as an index of lipid peroxidation, were measured by the thiobarbituric acid assay. Levels were significantly higher in tissues of passive-smoke-exposed groups (n=10) compared with normal-bred control groups (n=6), for red blood cells (2.17+/-0.22 vs. 1.80+/-0.39 nmol/mg), lung (1.39+/-0.32 vs. 1.03+/-0.35 nmol/mg), and spleen (1.75+/-0.33 vs. 1.42+/-0.15 nmol/mg); p<.05. No differences in malondialdehyde levels were found in plasma, heart, liver, stomach, and renal tissues. The results suggest that chronic environmental tobacco smoke exposure can increase lipid peroxidation in red blood cells and in lung and spleen tissue. This finding brings further investigative attention to the public health issue of the injurious effects of chronic passive smoke exposure.     

Propylene aromatization on Ga-MFI Zeolites

Propylene aromatization reaction was performed on various MFI type zeolites containing Ga species. The Ga was introduced into the zeolites by substitution (Ga-MFI), ion exchange (GIZ) and physical mixing (GPZ). A com-mercialized zeolite (PQZSM-5) was also used for comparison. The catalysts prepared were characterized by using XRF, XPS, surface area measurement, NH₃-TPD, and H₂-TPR. Through the Ga substitution, the acidity of the modified catalysts was decreased, and dehydrogenation and aromatization reactions occurred more easily. The lattice Ga did not react well with hydrogen contrary to the Ga located at the outside of the lattice. It was also found that Ga-MFI catalysts facilitate alkylation reactions. This paper is dedicated to Professor Wha Young Lee on the occasion of his retirement from Seoul National University     

Effect of pressure on direct synthesis of DME from syngas over metal-pillared ilerites and metal/metal-pillared ilerites

The effect of pressure on the direct synthesis of dimethyl ether (DME) from syngas over metal (Cu, Zn) pillared ilerites and metal (Cu, Zn) impregnated metal-pillared ilerites was explored. The prepared catalysts were characterized by XRD, BET, ICP-AES, SEM and FT-IR. The direct DME synthesis reaction was carried out in a differential fixed bed reactor with the prepared catalysts at various pressures (10, 20, 30 bar), 250°C and H₂/CO ratio of 2. The Cu/Zn-pillared ilerite catalyst showed the highest catalytic activity among the prepared catalysts at 20 bar, in which CO conversion was about 62% and DME selectivity was about 89%. CO conversion increased with pressure, and DME selectivity increased with pressure in the range of 10–20 bar, and above the pressure slightly decreased with pressure. The optimum pressure for this reaction was 20 bar.     

Bundling dynamics regulates the active mechanics and transport in carbon nanotube networks and their nanocomposites

High-density carbon nanotube networks (CNNs) continue to attract interest as active elements in nanoelectronic devices, nanoelectromechanical systems (NEMS) and multifunctional nanocomposites. The interplay between the network nanostructure and its properties is crucial, yet current understanding remains limited to the passive response. Here, we employ a novel superstructure consisting of millimeter-long vertically aligned single walled carbon nanotubes (SWCNTs) sandwiched between polydimethylsiloxane (PDMS) layers to quantify the effect of two classes of mechanical stimuli, film densification and stretching, on the electronic and thermal transport across the network. The network deforms easily with an increase in the electrical and thermal conductivities, suggestive of a floppy yet highly reconfigurable network. Insight from atomistically informed coarse-grained simulations uncover an interplay between the extent of lateral assembly of the bundles, modulated by surface zipping/unzipping, and the elastic energy associated with the bent conformations of the nanotubes/bundles. During densification, the network becomes highly interconnected yet we observe a modest increase in bundling primarily due to the reduced spacing between the SWCNTs. The stretching, on the other hand, is characterized by an initial debundling regime as the strain accommodation occurs via unzipping of the branched interconnects, followed by rapid rebundling as the strain transfers to the increasingly aligned bundles. In both cases, the increase in the electrical and thermal conductivity is primarily due to the increase in bundle size; the changes in network connectivity have a minor effect on the transport. Our results have broad implications for filamentous networks of inorganic nanoassemblies composed of interacting tubes, wires and ribbons/belts.     

Advanced Fatigue Crack Detection Using Nonlinear Self-Sensing Impedance Technique for Automated NDE of Metallic Structures

This article reports the application of a nonlinear impedance technique under a low-frequency vibration to detect contact-type structural defects such as fatigue cracks. If the contact-type damage is developed within the structure due to the low-frequency dynamic load, the vibration can cause a nonlinear fluctuation of the structural impedance because of the contact acoustic nonlinearity (CAN). This nonlinear effect can lead to amplitude modulation and phase modulation of the current flow. The nonlinear characteristics of the structural impedance can be extracted by observing the coupled electromechanical impedance of a piezoelectric active sensor and utilizing nonlinear wave modulation spectroscopy. Experimentally, a low-frequency vibration was applied to a notched coupon at a certain natural frequency by a shaker, so that a nonlinear fatigue crack can be artificially formed at the notch tip. Then, the nonlinear features are extracted based on a self-sensing impedance measurement from a host structure under a low-frequency vibration. The damage metric was established based on the nonlinear fluctuation of the impedance due to the CAN.     

Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CN(x)-multi-wall carbon nanotube hybrid materials

In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.