SATURATION DIVING WITH HELIOX TO 350 METERS OBSERVATION ON HEARING THRESHOLD, BRAINSTEM EVOKED RESPONSE AND ACOUSTIC IMPEDANCE

Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of bearing, earache daring compression. Examination showed that the threshold of tower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test

Clinical experiment of exercise induced asthma and respiratory impedance assessed with impulse oscillometry to measure exercise response of asthmatics

Abstract Objective In order to investigate pathophysiology of exercise induced asthma (EIA), the impedance of the respiratory system was studied using impulse oscillometry (IOS). EIA is a temporary increase in airway resistance, which occurs after several minutes of strenuous exercise. Most asthmatics experience EIA. Patients and methods Respiratory impedance was measured with IOS (MasterScreen, Jaeger, Germany) in 14 healthy volunteers and 14 asthmatics as baseline value at first. The procedure of exercise challenge with an ergometer (Corival 300 Gould Co.) increased heart rate to 90% of predicted maximum values in 3-4 min and maintained for 6 min. After challenge, measurements with IOS were made immediately at 5 min intervals for 5 times. Results The maximal increase of respiratory impedance occurred at 5-10 min after exercise and the increment magnitude of peripheral resistance (99.6%) was more than that of central resistance (13.5%) in asthmatics. After challenge, R5Hz, R5Hz-R20Hz, Zrespir (total impedance), resonance frequency (Fres) and X5Hz from patients changed significantly. The increment value of R5Hz-R20Hz from asthmatics was≥0.032kpa/l·s -1 and the change ratio of X5Hz from 71.4% of asthmatics was ≥41% (2SD beyond the mean response of nonashmatics). Air trapping loop was expressed in V T Zrespir graph in 57.1% patients. All subjects underwent IOS measurement. Conclusion Exercise test can diagnose asthma and evaluate efficacy of treatment for bronchial asthma. Because the patients usually have shortness of breath after exercise challenge, the measurement with spirometry (FEV 1) may not be accurate. IOS is based on measurement of the relationship between an external pressure pulse applied to the respiratory system and the resulting respiratory airflow. The spectral ratio of the amplitude of the pressure wave signal to the resulting flow signal constitutes the impedance of the respiratory system, from which the resistance (R) and the reactance (X, including elastance and inertance) of respiratory system in the frequency range 5Hz to 35Hz can be calculated. Our data showed that the increment value of R5Hz-R20Hz was more sensitive than other indices for detecting exercise induced asthma. The bronchoconstriction took place in peripheral airway mainly after exercise. Because obstruction of small bronchi during expiration and impedance increased abruptly, air trapping loops were expressed in V T Zrespir graph after challenge in asthmatics. Fres is the frequency point where the absolute value of elastance equals to that of inertance. X5Hz reflects the condition of compliance of lungs. Fres shifted right and change ratio of X5Hz increased after exercise were relative to the compliance decrease of lungs. The airway response of exercise challenge may be assessed more accurately and more conveniently with IOS that did not require a maximal inspiration and forced expiration.

Novel,tadpole-shaped,polyhedral oligomeric silsesquioxane containing sulfonated block copolymer for humidity sensing

Due to the"trade-off"effect between the high water adsorption and low stability under high Relative Humidity of polymer matrix,fabrication of resistive-type polymer-based humidity sensors with a wide impedance response and excellent stability in high relative humidity remains a great challenge.Aim at solving that,a novel polymeric humidity sensing matrix,specifically a tadpole-shaped,polyhedral oligomeric silsesquioxane(POSS)containing block copolymers(BCPs)of POSS-poly(methyl methacrylate)-poly styrene(POSS-PMMA-SPS)were proposed.This novel BCP was synthesized using atom transfer radical polymerization(ATRP)employing a two-step approach,and following post sulfonation,a series of sulfonated BCPs(POSS-PMMA-SPS)with different sulfonation degree was obtained.The subject humidity sensors were produced using different sulfonated BCPs employing a dip-coating technique,and three wide-impedance response humidity sensors were produced.Each of these sensors exhibited an excellent humidity-sensing response of mo re than 104 within the humidity range from 11%to 95%RH.In particular,the humidity sensor S-6 that had a proper degree of sulfonation presented a relatively fast response(t90%of 11 s and 80 s in both the water adsorption and desorption processes),and superior repeatability for more than 30 days.