Use of twitch mouth pressure to assess diaphragm strength in patients with chronic obstructive pulmonary disease.

This study was undertaken to determine whether twitch mouth pressure (TwPmo) can reliably assess diaphragm strength in patients with chronic obstructive pulmonary disease (COPD) using fully automatic trigger techniques. Fifteen patients with COPD were recruited. TwPmo, twitch oesophageal pressure (TwPes) and twitch transdiaphragmtic pressure (TwPdi) were generated by phrenic nerve stimulation and were measured using an inspiratory flow trigger (40 ml/s, Experiment 1) using an inspiratory pressure trigger (-5 cmH2O, Experiment 2) and using no trigger at functional residual capacity (Experiment 3). The correlation between TwPmo and TwPes was as follows: r=0.832; P<0.0001 (Experiment 1), r=0.900; P<0.0001 (Experiment 2); there was no significant correlation in Experiment 3. A Bland-Altman plot of the difference between TwPmo and TwPes showed the limits of agreement in Experiment (1) bias (range) 0.18 cmH2O (-2.05 to 2.41) and Experiment (2) bias (range) 0.32 cmH2O (-1.69 to 2.32). Measuring TwPmo using a fully automatic technique is a simple and convenient method for assessing diaphragm strength.

Surface modification of nanometer size TiO2 with salicylic acid for photocatalytic degradation of 4-nitrophenol.

The efficiency of photocatalytic reactions was limited by the wide band-gap of TiO(2) and the high degree of electron-hole recombination inherent in photocatalytic process, as well as by the limited adsorption capability of photocatalysts. In order to increase the overall efficiency, the surface of nanometer size TiO(2) was simply and fast modified by chemical adsorption in saturated solution of salicylic acid. A stable, light yellow surface complex was formed quickly, which has obvious absorption in the region from 320 to 420 nm. Through surface modification, the adsorption efficiency of 4-nitrophenol by TiO(2) was enhanced from 42 to 84%. The photocatalytic efficiency was tested on the degradation of 4-nitrophenol. The influences of catalyst and its dosage, pH value, and 4-nitrophenol concentration on the degradation were investigated. Under such photodegradation conditions as initial pH 4.0, 4-nitrophenol 5 mg l(-1), catalyst 100 mg, and irradiation time 160 min with 160 W high-pressure mercury lamp, the degradation efficiency of 4-nitrophenol by TiO(2) was increased from 39.5 to 79.3% after surface modification, and furthermore, the degradation efficiency could be enhanced to 91.1% if the concentration of 4-nitrophenol was not more than 1 mg l(-1). Compared with the pure TiO(2), surface modification led not only to improve the surface coverage of 4-nitrophenol, but also to increase the light utilization. Both of these factors were crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of aromatic pollutants.