The thermostated medical jet nebulizer: Aerosol characteristics.

The sudden expansion of gas at the outlet of the jet (pneumatic) nebulizer significantly reduces the temperature of the solution, which may provoke bronchospasm, therefore it is recommended to use modern pneumatic inhalers equipped with a thermostat or a universal thermal attachment that allow to obtain a higher temperature aerosol, i.e. thermo-aerosol. The research was carried out for model Newtonian fluids. The droplet diameters of the aerosol spray were investigated using a Spraytec aerosol particle size measurement system. Analysis of the obtained results showed that the increase in solution viscosity caused a decrease in mean droplet diameters and prolonged nebulization time. The analysis of experimental data made it possible to propose a correlation equation describing the mean diameter of the droplets depending on the properties of the liquid and the flow conditions in the thermostated medical nebulizer. The obtained data contributes to a better understanding of the complex liquid atomisation process and can be helpful in the design of medical nebulizers and pharmaceutical preparations.

The effect of shear and extensional viscosities on atomization of Newtonian and non-Newtonian fluids in ultrasonic inhaler.

The paper contains results of the experimental study on atomization process of aqueous solutions of glycerol and aqueous solutions of glycerol-polyacrylamide (Rokrysol WF1) in an ultrasonic inhaler. In experiments the different concentration aqueous solutions of glycerol and glycerol-polyacrylamide have been tested. The results have been obtained by the use of laser diffraction technique. The differences between characteristics of ultrasonic atomization for test liquids have been observed. The analysis of drop size histograms shows that the different sizes of drops have been formed during atomization process. The present study confirmed the previous reports which suggested that the drops size changes with the increase in viscosity of solution changes in spray characteristics were also observed. It has been shown that the shear and extensional viscosities affect the process of atomization.

Femtosecond fiber lasers with pulse energies above 10 nJ.

A series of experiments aimed at determining the maximum pulse energy that can be produced by a femtosecond fiber laser is reported. Exploiting modes of pulse propagation that avoid wave breaking in a Yb fiber laser allows pulse energies up to 14 nJ to be achieved. The pulses can be dechirped to sub-100-fs duration to produce peak powers that reach 100 kW. The limitations to the maximum pulse energy are discussed.

High-energy femtosecond stretched-pulse fiber laser with a nonlinear optical loop mirror.

A stretched-pulse fiber laser with a nonlinear optical loop mirror (NOLM) that produces 100-fs pulses with 1-nJ energy is demonstrated. These results constitute a 30-fold increase in pulse energy over previously reported femtosecond fiber lasers with a NOLM. Compared with previous stretched-pulse lasers, this laser offers a cleaner spectrum and improved stability, with comparable pulse duration and energy. Implications for the construction of truly environmentally stable lasers are discussed.

Deactivation of the pulmonary surfactant dynamics by toxic aerosols and gases.

Interactions between selected toxic aerosols and gases occurring in the air at the workplace and the pulmonary surfactant (PS) have been studied with two physicochemical techniques in vitro. The Pulsating Bubble Surfactometer (PBS) and the Langmuir-Wilhelmy Balance (LWB) have been used for measurements of dynamic interfacial properties of the PS material after its contact with several gases (sulfur dioxide, nitrogen oxides, ozone, ammonia) and liquids (sulfuric, nitric and hydrochloric acids and ammonium hydroxide), which can be brought into the alveoli with the inhaled air. Surface tension-area relationships for the interface oscillations have been analyzed using qualitative criteria of normalized hysteresis area (HA(N)) and minimum surface tension (sigma(min)). It was demonstrated that, for each analyzed compound, inactivation of the surfactant occurs, but the critical concentrations and doses are compound specific, which suggests the toxic potential of the investigated substances with respect to PS. Possible mechanisms of the interactions between the investigated substances and the surfactant components are discussed. Degradation of the PS dynamical interfacial properties (HA(N) and sigma(min)), important from the physiological viewpoint, observed in our in vitro experiments, suggests a possibility of adverse health effect in the case of a chronic inhalation of toxic gases and aerosols, even at low concentration or after a short exposure to strongly contaminated air. It results in a slowdown of the pulmonary clearance rate and increase of the lung burden for both considered cases.

Application of a fibrous electrostatic filter for treatment of diesel exhaust.

The paper presents results of investigations of a novel method for diesel exhaust filtration in a fibrous filter supplemented by the external electrostatic field (FEF), which may be used to eliminate the occupational hazard near sources of diesel emission. The reported research follows the preliminary basic study of soot removal in such systems (Ciach, Sosnowski, & Podgórski, 1995), and is focused on the construction and testing of a prototype technical-scale FEF device. The results suggest a strong relation between applied voltage and filtration efficiency of the system and demonstrate the influence of aerosol precharging on the efficiency, which can be more than 95%.

Pulse nebulization in pneumatic devices.

Aerosols of a physiological salt solution and aqueous solutions of salbutamol, sodium cromoglicate, and dornase alfa were generated in a pneumatic nebulizer and analyzed in a system with controlled humidity of air as a carrier gas. Mass distribution of aerosol particles and yield of generation for pulse nebulization were measured. Pulsation of generation was realized with an attachment maintained by a computer program. Opening times of the valve were in the range 50-800 ms. The results indicate the possibility of improving aerosol particle delivery to the lung using a pulse generation system.

Assessment of the pulmonary toxicity of inhaled gases and particles with physicochemical methods.

Physicochemical techniques used for evaluating the pulmonary surfactant (PS) quality are discussed as methods useful in assessing toxicity of inhaled gases and particles. Two standard devices, Langmuir-Wilhelmy film balance and pulsating bubble apparatus, are presented in detail, and the measured results of interaction between sulfuric acid and 2 models of PS materials are analyzed. The evident decrease in surface activity of the pulmonary surfactant after its contact with the acid at concentrations approaching 0.001 M may be considered as an indicator of the adverse effect, which can result in several health problems. The presented approach can be used as a method of assessing pulmonary toxicity of any substances present in the breathing air.

[Comparative studies of particle distribution range of aerosol cromolyn sodium generated by MDI systems]. / Badania porównawcze rozkladów wielkosci czastek aerozolowych kromoglikanu dwusodowego generowanych z dozowników MDI.

Particles size distribution of the sodium cromoglycate preparations: CROPOZ PLUS and CROMOGEN EB generated with MDI and for under-pressure releasing methods were measured. Results of measurements indicate a significant repeatability of each sample properties. An average contribution of mass of the respirable fraction for both aerosolized pharmaceuticals is in the range of 40% of the generated dose. CROMOGEN EB with optimizer (spacer) gives a higher contribution of the respirable fraction--up to 50% of dose, with simultaneous lower value of the released mass of aerosol. Particles size distribution of CROPOZ PLUS within a respirable fraction indicates an efficient penetration and deposition of particles in the upper, central and peripheral parts of tracheobronchial tree (TB). High contribution of submicron particles of CROMOGEN EB with optimizer gives efficient penetration and deposition of these particles in the lungs.

Churg-Strauss syndrome leading to small bowel infarction: an unusual case of abdominal pain in a young patient.

A 33-year-old man with a history of severe asthma presented to the emergency department with a week-long history of severe unrelenting abdominal pain, nausea and decreased appetite. He was admitted to hospital, and routine gastrointestinal investigations were performed, which did not elucidate the cause of his abdominal pain. Exploratory laparotomy demonstrated patchy infarction of the entire small bowel, characteristic of Churg-Strauss syndrome. The patient subsequently underwent 12 separate laparotomies to salvage surviving small bowel. The patient is maintained on total parenteral nutrition.

Optical saturation measurements of fluorophores in solution with pulsed femtosecond excitation and two-dimensional CCD camera detection.

We present a new method for the measurement of saturation of the optical transition of fluorescent molecules in solution, which is based on detection with a CCD camera of a two-dimensional projection of the three-dimensional, spatially nonuniform fluorescence intensity distribution as generated in a bulk solution of the fluorophore by excitation with focused femtosecond optical pulses. Essential to the method is (a) a combination of information from a measurement in saturation and one not in saturation and (b) for the measurement in saturation, the simultaneous observation of both saturated and nonsaturated regions of the fluorescence intensity distribution. The experimental setup is straightforward and good agreement is found between the theory and the experimental data.

Production of 30-fs pulses tunable throughout the visible spectral region by a new technique in optical parametric amplification.

A multipass optical parametric amplif ier is pumped by a 250-kHz microjoule-level Ti:sapphire regenerative amplif ier system. Tuning each pass of the amplif ier to provide gain for slightly different spectral regions of a white-light continuum source produces broadband pulses that may be compressed to less than 30 fs.

Patterns of practice in emergency department management of chest pain of suspected cardiac origin: clinical utility of single stat creatine kinase (CK).

The patterns of practice and the clinical utility of a single stat creatine kinase (CK) level in the emergency department management of chest pain of suspected cardiac origin were examined by a prospective observational study using a two-part questionnaire, completed by physicians before and after availability of CK results. The results showed that of the 776 patients in the study, 135 were admitted to hospital with acute myocardial infarction (AMI), 285 were admitted for reasons other than AMI, 343 were discharged, and 13 died or were transferred to another hospital. Although initial and final diagnoses in the emergency department did not differ in 597 patients (77%), initial decisions to admit or discharge were made in only 244 (31%) patients without waiting for CK results, and in 401 (52%) cases, decisions on patient disposition were deferred. Of 218 patients who had elevated CK levels, 193 (89%) were admitted, 121 for AMI. Only five (< 1%) patients who would otherwise have been discharged were admitted because of elevated CK levels. Of the 343 discharges, 245 (71%) occurred after the physicians knew the CK results. It is concluded that emergency department physicians routinely make changes in their diagnostic and management decisions based on current information and as it becomes updated. This study also suggests that there appears to be a heavy reliance on a single CK assay, although the relative importance of this diagnostic test compared to other factors is not known. Further studies are necessary.

Chirped-pulse amplification of 85-fs pulses at 250 kHz with third-order dispersion compensation by use of holographic transmission gratings.

We demonstrate pulse stretching and compression in a high-repetition-rate chirped-pulse Ti:sapphire regenerative amplifier, using high-efficiency holographic transmission gratings. A quantitative dispersion measurement technique is developed to characterize dispersion of the system to the third order. After recompression with third-order dispersion compensation, 3.1-microJ 85-fs, nearly transform-limited pulses are obtained.

Active-passive coping and skin conductance and heart rate changes.

Sixty subjects were administered 33 tasks, selected from the Raven Progressive Matrices, in conditions that differed by type of monetary reinforcement (reward, frustration, and control group). Subjects were tested in pairs. One subject, assigned as the active one, was asked to solve a problem while the other was only a passive observer. Heart rate level and the amplitude of evoked skin conductance responses were measured. Statistical analysis detected a higher heart rate level in active versus passive subjects at the beginning stage of the experiment, as well as a faster heart rate decrease in the former versus the latter group during subsequent blocks of four tasks. Changes in skin conductance response magnitude during the ensuing task phases exhibited a descending trend in passive subjects and an ascending trend in active subjects. The monetary reinforcement manipulation was not effective. The results support a concept put forward by Fowles (1988), who maintained that tonic heart rate and skin conductance response amplitude may serve as indices of the behavioral activation system and behavioral inhibition system, respectively, as postulated by Gray's model of arousal.

Sources of uncertainty and psychophysiological state changes under conditions of noxious stimulus anticipation.

The main aim of the experiment was to compare the effect of the two variables (regarded here as different sources of subjective uncertainty) - probability of stimulus occurrence and ambiguity of the message about this probability - upon changes in heart rate (HR) and skin resistance (SR) during anticipation of a noxious stimulus. Three other independent variables - the type of stimulus (shock vs. sound), repetition of trials (two series of trials), and time-within-trial - were controlled as well. Results indicate that ambiguity as compared to probability has a more pronounced effect upon SR changes. Effects of the two variables upon HR changes are not significant. Moreover, in the shock group, the effect of repetition of trials was found to have a habituation effect for HR changes and a dishabituation effect for SR changes.