Electrophysiological properties of cultured neonatal rat dorsal horn neurons containing GABA and met-enkephalin-like immunoreactivity

We have developed a culture of neurons dissociated from the most superficial laminae of the neonatal rat spinal cord dorsal horn (DH). By using the perforated patch-clamp technique, we distinguished four types of neurons based on their firing properties in response to intracellular injection of 900 ms lasting current pulses. Type 1 neurons were characterized by a tonic firing. Type 2 neurons displayed marked spike accommodation and fired brief (<500 ms) bursts of action potentials, whereas type 3 neurons fired a single spike. Type 4 neurons exhibited different types of firing patterns, but all of them possessed a time-dependent inwardly rectifying current activated by membrane hyperpolarization. Met-enkephalin-like immunoreactivity (met-ENK-LI) and glutamic acid decarboxylase-like immunoreactivity (GAD-LI) were colocalized in 42% of the neurons (n = 59), which were previously identified electrophysiologically. Type 1-4 neurons represented respectively 4, 64, 20, and 12% of the population of neurons colocalizing met-ENK-LI and GAD-LI. We conclude that the electrophysiological properties of DH neurons present in our cultures are similar to those described in acute slice or hemisected spinal cord preparations and that met-ENK-LI and GABA-LI are preferentially colocalized in type 2 neurons.     

Process modeling of hybrid machining system consisted of electro discharge machining and end milling

This paper presents a novel hybrid machining process (HMP) that combines cutting action with machining using discharge pulses. Working conditions for a machine tool capable of combining micro-electro discharge machining (EDM) with milling is still an ill-defined problem relying on heuristics because there is insufficient knowledge of the discharge mechanism and the effects of machining parameters. The proposed HMP that combines micro-EDM and milling processes was applied to a steel alloy (AISI 1045) as the workpiece and end mill tungsten carbide as the tool electrode. Test results obtained from a number of experiments showed that the developed HMP yields reasonable machining time and surface roughness. Significant controlling variables for the machining response were identified and ranked using the Taguchi method. Furthermore, the response surface method was used to develop an empirical model based on the correlation between input variables and output responses.     

Lexical control of within-word eye movements.

Eye movements were recorded during the reading of long words, which were presented in isolation at their optimal viewing position. Refixations were found to be preferentially directed toward the region of the word that contained the critical letters for distinguishing it from its competitors. In Experiments 1 and 2, low-frequency stimulus words sharing all letters except the initial ones with a high-frequency stimulus word (critical letters at the beginning of the word) elicited more left refixations than low-frequency stimulus words sharing all letters except the final ones with a high-frequency stimulus word (critical letters at the end of the word). A similar result was found in Experiments 3 and 4, using an orthographic priming paradigm. These results suggest that refixations are linked to the selection stage of lexical access, aimed at isolating a single lexical entry among a set of candidates activated during the first fixation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design and Analysis of New Micromixers Based on Distillation Column Trays

Four passive micromixer designs (G1, G2, G3, and G4) based on distillation columns trays are proposed. The performance of the devices is assessed by numerical simulations. The mixing performance is investigated for different Reynolds numbers and channel heights for oil/ethanol flow. G1 and G4 designs provided a high mixing index. The G1 device achieved superior mixing performance with a moderate pressure drop due to the induced flow recirculation pattern for a relatively high flow rate, highlighting the potential use of such microdevice for scale-up and numbering-up of microdevices in modular chemical plant processing.     

Synthesis and Anticancer Properties of Oxazepines Related to Azaisoerianin and IsoCoQuines

In this article, we report the synthesis and biological properties of a series of novel oxazepines related to isoCA-4 having significant antitumor properties. Among them, three oxazepin-9-ol derivatives display a nanomolar or a sub-nanomolar cytotoxicity level against five human cancer cell lines (HCT116, U87, A549, MCF7, and K562). It was demonstrated that the lead compound in this series inhibits tubulin assembly with an IC₅₀ value of 1 μM and totally arrests the cellular cycle in the G2/M phase at the low concentration of 5 nM in HCT116 and K562 cells. Molecular modeling studies perfectly corroborates these promising results.     

Kinetic study of liquid lipase-catalyzed glycerolysis of olive oil using Lipozyme TL 100L

Monoacylglycerol (MAG) and diacylglycerol (DAG) are two natural components found in most edible oils and fats. Conventional synthesis of MAG and DAG is usually conducted by glycerolysis of triacylglycerol (TAG) at high temperatures (above 200°C) in the presence of an alkaline catalyst. In this work, the synthesis of MAG and DAG using enzymatic glycerolysis of olive oil was investigated using Tween 80 as surfactant, n-butanol as co-surfactant and the novel lipase in free/liquid formulation Lipozyme TL 100L as catalyst. Experimental design was used to evaluate the effect of enzyme load and reaction temperature on the feedstock conversion. Enzyme load and system temperature were significant variables in the statistical design and the best condition was found at 35°C, 7.5 vol% of Lipozyme TL 100L and glycerol to oil volumetric ratio of 2:1 with conversion of TAG at approximately 98% after 2 h of process. A mathematical model based on the Ping-Pong Bi-Bi mechanism was used to describe the reaction kinetics. The model adequately described the behavior of the system and can be a useful tool for the design of reactors in larger scales.     

Structural and Catalytic Studies of a Trimethyltin Vanadate Coordination Polymer

The organotin vanadate [Me₃SnVO₃] (1) has been prepared and characterised in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis, multinuclear magic-angle spinning (MAS) NMR, IR and Raman spectroscopy. The phase purity and structure of microcrystalline 1 were confirmed by carrying out a full Rietveld structural refinement at ambient temperature and from conventional powder XRD. ⁵¹V and ¹¹⁹Sn MAS NMR data for compound 1 were in agreement with the predicted structure, showing two equally-abundant, nonequivalent Me₃Sn groups and two equally-abundant, nonequivalent vanadium atoms. The compound was applied as a catalyst for the liquid-phase epoxidation of olefins at 55 °C using tert-butyl hydroperoxide (tBuOOH) as the oxidant. The reaction rate for the different substrates followed the order cis-cyclooctene > (R)-(+)-limonene ≅ trans-2-octene > cyclododecene > styrene > 1-octene; the corresponding epoxides were the only observed products. Leaching tests indicated that the catalytic epoxidation of cyclooctene was mainly heterogeneous in nature. This paper is dedicated to Professor Ian Manners and his scientific accomplishments.     

Hydrogen production in fluidized bed by chemical-looping cycle

To investigate the feasibility of a chemical-looping hydrogen generation system, we investigated the reduction and water splitting reaction characteristics for three mediators and two reducing gas in a bubbling fluidized bed reactor (0.02 m I.D.). For three oxygen carrier particles (NiO/bentonite, Fe₂O₃/bentonite, (NiO:Fe₂O₃)/bentonite), hydrogen was used as a reduction gas and water was used as an oxidation gas. For (NiO: Fe₂O₃)/bentonite particle, carbon monoxide, which is the main component in the syngas from coal or heavy residue, was used as a reducing gas to check reactivity for the carbon containing fuels and carbon deposition characteristics. Based on the reactivity tests, (NiO: Fe₂O₃)/bentonite particle was selected as the best mediator for the chemical-looping hydrogen generation system to achieve stable continuous operation. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Crystal structure of poly(pentamethylene 2,6-naphthalate)

The crystal structure of poly(pentamethylene 2,6-naphthalate) (PPN) was determined by using X-ray diffraction and molecular modeling. The unit cell of PPN was found to be triclinic ( space group) with dimensions of a=0.457 nm, b=0.635 nm, c=2.916 nm, =121.6°, β=90.4°, γ=87.6°, and the calculated crystal density was 1.311 g cm⁻³. The unit cell contains one polymer chain with two repeating units. In the unit cell, the PPN backbone takes gauche/gauche conformation in the middle part of each pentamethylene unit, and two naphthalene rings are in face-to-face arrangement.