The increased CO2 adsorption performance of chitosan-derived activated carbons with nitrogen-doping.

Highly porous nitrogen-doped activated carbons (NACs) were prepared by the chemical activation of chitosan using alkali carbonates. The NACs exhibited extremely high CO2 capacities of 1.6 mmol g(-1) (15 kPa) and 4.9 mmol g(-1) (100 kPa) at 25 °C. Nitrogen atoms doped into carbon frameworks clearly enhanced CO2 adsorption at low partial pressures.

Electrodynamic trapping of spinless neutral atoms with an atom chip.

Three-dimensional electrodynamic trapping of neutral atoms has been demonstrated. By applying time-varying inhomogeneous electric fields with micron-sized electrodes, nearly 10(2) strontium atoms in the 1S0 state have been trapped with a lifetime of 80 ms. In order to design the electrodes, we numerically analyzed the electric field and simulated atomic trajectories in the trap, which showed reasonable agreement with the experiment.

Permeabilities of alkyl p-aminobenzoates through living skin equivalent and cadaver skin.

The in vitro permeabilities of alkyl p-aminobenzoates through living skin equivalent (LSE) and cadaver skin were compared. Methyl, ethyl, and butyl p-aminobenzoates were used as model compounds. The permeabilities of these compounds through LSE and cadaver skin from an aqueous drug suspension were determined with a flow-through diffusion cell. The permeability coefficients of these esters in LSE were an order of magnitude higher than in cadaver skin. This was primarily because of low resistances offered by the outermost layer (i.e., stratum corneum) of LSE. In the case of cadaver skin, the permeability coefficient increased as the carbon chain length increased, whereas no appreciable change in the permeability coefficients of these esters in LSE was observed. These results clearly suggest that the LSE membrane offered very little resistance as opposed to cadaver skin. Therefore, the LSE membrane may not quantitatively represent a good human skin model for evaluating skin permeation of a drug from topical or transdermal formulations.

Effect of receiver fluid pH on in vitro skin flux of weakly ionizable drugs.

In in vitro skin permeation experiments, the pH of viable epidermis is readily conditioned by the receiver fluid. For weakly ionizable compounds, the flux determined experimentally thus depends on the receiver fluid pH. The purpose of the present work is to characterize this pH effect, since nonphysiological conditions have often been used in the receiver fluid to enhance the solubility of the subject compounds. A transport model was developed to analyze the above-mentioned pH effect of the receiver fluid on the steady state flux of weakly ionizable drugs. The results showed that the skin flux had a strong dependence on pH for those compounds with high intrinsic partition coefficients. Experimentally, this pH effect was observed with a model acid and a model base. The skin flux was found to have a profound dependence on the receiver fluid pH. This dependence also correlates with the octanol/water partition coefficient of the molecule. It was concluded that the use of a physiological receiver fluid would be crucial for a realistic estimation of transdermal potential. The results also suggested that, for weakly ionizable compounds with high partition coefficients, the viable epidermis could be a significant transport barrier for systemic absorption.

Reconstruction of neglected Achilles tendon rupture with Marlex mesh.

Reconstruction of the neglected Achilles tendon rupture was performed with marlex mesh on six patients. Marlex mesh was folded into three layers and sandwiched between both ruptured ends that were divided horizontally into two layers in moderate tension. All of the patients showed satisfactory function with a mean follow-up period of 3 years (range, 2.4-3.7 years). The operative procedure is simple because there is no need to harvest healthy tendon or fascia as the donor and there is less adhesion with neighboring tissues and minimal signs of foreign-body reactions.