Influence of some phospholipase A2 and cytochrome P450 inhibitors on rat arterial smooth muscle K+ currents.

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Laparoscopic evaluation shows deficiencies in memory ring deployment during small ventral hernia repair

Abstract: Background With the introduction of a self-expanding, memory-containing, circular hernia patch, surgeons have been enthusiastic about its use to repair ventral hernias smaller than 3 cm in diameter. The aim of this study was to evaluate the efficiency, reliability, and safety of the device laparoscopically with respect to adequate deployment of the patch. Methods During 1 year all patients with small ventral hernias were treated with this memory-containing patch and were inspected by laparoscopy. Just prior to insertion of the patch, remaining adhesions on top of the peritoneum were analyzed, as was the interference of the umbilical ligament. The final position of the patch was monitored, identifying the cupping phenomenon, exposure of the polypropylene to the viscera, and the amount of tension on the straps. All patients were followed for 2 years and postoperative complications and recurrence rate were monitored. Results Twenty-eight patients were operated on for repair of a small ventral hernia with laparoscopic control. Adhesions, not digitally palpable, that interfered with adequate patch deployment were observed in more than 80% of the cases. After a median follow-up of 25 months a 14.8% recurrence rate was observed. Conclusions The patch, consisting of both polypropylene and ePTFE, leads to unacceptable morbidity and a high rate of recurrences. By laparoscopic evaluation, these recurrences are probably based on a combination of material characteristics and unavoidable technical errors

Selective Conversion of Lignin-Derivable 4-Alkylguaiacols to 4-Alkylcyclohexanols over Noble and Non-Noble-Metal Catalysts

© 2016 American Chemical Society. Recent lignin-first catalytic lignocellulosic biorefineries produce large quantities of two potential platform chemicals, 4-n-propylguaiacol (PG) and 4-n-propylsyringol. Because conversion into 4-n-propylcyclohexanol (PCol), a precursor for novel polymer building blocks, presents a promising valorization route, reductive demethoxylation of PG was examined here in the liquid-phase over three commercial hydrogenation catalysts, viz. 5 wt % Ru/C, 5 wt % Pd/C and 65 wt % Ni/SiO2-Al2O3, at elevated temperatures ranging from 200 to 300 °C under hydrogen atmosphere. Kinetic profiles suggest two parallel conversion pathways: Pathway I involves PG hydrogenation to 4-n-propyl-2-methoxycyclohexanol (PMCol), followed by its demethoxylation to PCol, whereas Pathway II constitutes PG hydrodemethoxylation to 4-n-propylphenol (PPh), followed by its hydrogenation into PCol. The slowest step in the catalytic formation of PCol is the reductive methoxy removal from PMCol. Moreover, under the applied reaction conditions, PCol may react further into hydrocarbons. The following criteria are therefore essential to reach a high PCol yield: (i) catalytic pathway II is preferred as this route does not involve stable intermediates; (ii) reactivity of PMCol should be higher than that of PCol, and (iii) the overall carbon balance should be high. Both the catalyst type and the reaction conditions have a substantial impact on the PCol yield. Only the commercial Ni catalyst meets the three criteria, provided the reaction is performed at 250 °C in hexadecane. Additional advantages of this solvent choice are a high boiling point (low operational pressure in closed reactor systems), high solubility of PG and derived products, high thermal, reductive stability, and easy derivability from fatty biomass feedstock. This Ni catalyst also showed an excellent stability in recycling runs and is capable of converting highly concentrated (up to 20 wt %) PG in hexadecane. Ru and Pd on carbon showed a low PCol yield, as they are not conform the three criteria. Low hydrogen pressure favors Pathway II, resulting in a very high PCol yield of 85% at 10 bar. Catalytic conversion of guaiacol, 4-methyl- and 4-ethylguaiacol in comparable circumstances showed similarly high yields of the corresponding cyclohexanols.status: publishe

A single switch boost converter with a high conversion ratio

To supply a high voltage load directly from a low voltage battery pack, often a converter is required with a high conversion ratio. Converters with coupled inductors have emerged displaying a high efficiency, a low overall component count, a simple topology, and the need for only a single low-voltage active switch. However, if the different possible positions for the capacitors in the topology are considered, several variants of this topology can be distinguished. After a review of the principles of operation of the basic converter, the properties of the different topological variations are studied. Finally, a topological choice is made based on the proposed criteria for a 200 V supply, converting 200 W from a 24 V battery. The theoretical results are compared to the results retrieved from a prototype converter