Comparison of fabric skins for the simulation of sweating on thermal manikins.

Sweating is an important thermoregulatory process helping to dissipate heat and, thus, to prevent overheating of the human body. Simulations of human thermo-physiological responses in hot conditions or during exercising are helpful for assessing heat stress; however, realistic sweating simulation and evaporative cooling is needed. To this end, thermal manikins dressed with a tight fabric skin can be used, and the properties of this skin should help human-like sweat evaporation simulation. Four fabrics, i.e., cotton with elastane, polyester, polyamide with elastane, and a skin provided by a manikin manufacturer (Thermetrics) were compared in this study. The moisture management properties of the fabrics have been investigated in basic tests with regard to all phases of sweating relevant for simulating human thermo-physiological responses, namely, onset of sweating, fully developed sweating, and drying. The suitability of the fabrics for standard tests, such as clothing evaporative resistance measurements, was evaluated based on tests corresponding to the middle phase of sweating. Simulations with a head manikin coupled to a thermo-physiological model were performed to evaluate the overall performance of the skins. The results of the study showed that three out of four evaluated fabrics have adequate moisture management properties with regard to the simulation of sweating, which was confirmed in the coupled simulation with the head manikin. The presented tests are helpful for comparing the efficiency of different fabrics to simulate sweat-induced evaporative cooling on thermal manikins.

Opportunities and constraints of presently used thermal manikins for thermo-physiological simulation of the human body.

Combining the strengths of an advanced mathematical model of human physiology and a thermal manikin is a new paradigm for simulating thermal behaviour of humans. However, the forerunners of such adaptive manikins showed some substantial limitations. This project aimed to determine the opportunities and constraints of the existing thermal manikins when dynamically controlled by a mathematical model of human thermal physiology. Four thermal manikins were selected and evaluated for their heat flux measurement uncertainty including lateral heat flows between manikin body parts and the response of each sector to the frequent change of the set-point temperature typical when using a physiological model for control. In general, all evaluated manikins are suitable for coupling with a physiological model with some recommendations for further improvement of manikin dynamic performance. The proposed methodology is useful to improve the performance of the adaptive manikins and help to provide a reliable and versatile tool for the broad research and development domain of clothing, automotive and building engineering.

Development studies on determination of preservatives decomposition products.

Preservatives are chemical substances whose role is to protect medicinal products against harmful changes caused by microorganisms. They are added to sterile medicinal products, such as eye drops and multidose solutions for injections, as well as to non-sterile products, such as water oral solutions, creams, gels, suppositories and capsules with liquid content. The most commonly used preservatives include: benzyl alcohol, butyl, ethyl, methyl and propyl p-hydroxybenzoates and their sodium salts. In medicinal products benzyl alcohol slowly oxidizes to benzaldehyde and benzoic acid while esters of p-hydroxybenzoic acid hydrolyze to p-hydroxybenzoic acid. HPLC methods were elaborated for identification and quantitative determination of the parabens, benzyl alcohol, active substances as well as their impurities in pharmaceuticals: oral solutions Amertil and Efforil (contain cetirizine hydrochloride or etilefrine hydrochloride and parabens), eye drops Difadol (contains diclofenac sodium and benzyl alcohol) and cream Tenasil (contains terbinafine hydrochloride and benzyl alcohol). The HPLC systems consisted of columns: Supelcosil LC-DP, Inertsil ODS-3 or Discovery HS F5 and three mobile phases mixtures of acetonitrile with buffers of various pH (3, 5 and 7) in proportions 45 : 55 (v/v). These systems have been characterized with appropriate selectivity (all the Rs values > 2) and sensitivity (LOD approx. 0.01 microg/mL). They also demonstrated satisfactory precision and a linear dependence between the analyte content and the peak area.

Thermal sensations of surgeons during work in surgical gowns.

Standards for surgical procedures and medical clothing, designed for use in the operating theatre, have been gradually developed with the progress in science and technology. Standard No. EN 13795:2011, determining the requirements concerning materials for production of surgical gowns, was introduced in 2003. It concerns, e.g., resistance to microbial penetration. Little attention is given to thermal comfort, even though it is well known that thermal discomfort can have an adverse effect on the quality and efficiency of work. During a real-life test and laboratory tests, 2 male surgeons and 8 male volunteers were asked to describe their subjective sensations before and after work. The results of the real-life test and the laboratory tests are comparable. They show a clear lack of thermal comfort when medical clothing designed for the operating theatre is used.

Psychomotor Performance after 30 h of Sleep Deprivation Combined with Exercise.

Sleep deprivation (SD) usually impairs psychomotor performance, but most experiments are usually focused on sedentary conditions. The purpose of this study was to evaluate the influence of 30 h of complete SD combined with prolonged, moderate exercise (SDE) on human psychomotor performance. Eleven endurance-trained men accustomed to overnight exertion were tested twice: in well-slept and non-fatigued conditions (Control) and immediately after 30 h of SDE. They performed a multiple-choice reaction time test (MCRT) at rest and during each workload of the graded exercise test to volitional exhaustion. At rest, the MCRT was shorter after SDE than in the Control (300 ± 13 ms vs. 339 ± 11 ms, respectively, p < 0.05). During graded exercise, there were no significant differences in MCRT between groups, but the fastest reaction was observed at lower workloads after SDE (158 ± 7 W vs. 187 ± 11 W in Control, p < 0.05). The total number of missed reactions tended to be higher after SDE (8.4 ± 0.7 vs. 6.3 ± 0.8 in Control, p = 0.06). In conclusion, SDE is different from SD alone; however, well-trained men, accustomed to overnight exertion can maintain psychomotor abilities independently of the extent of central fatigue. Exercise can be used to enhance psychomotor performance in sleep-deprived subjects in whom special caution is required in order to avoid overload.

Methods of estimating the effect of integral motorcycle helmets on physiological and psychological performance.

This article proposes a method for a comprehensive assessment of the effect of integral motorcycle helmets on physiological and cognitive responses of motorcyclists. To verify the reliability of commonly used tests, we conducted experiments with 5 motorcyclists. We recorded changes in physiological parameters (heart rate, local skin temperature, core temperature, air temperature, relative humidity in the space between the helmet and the surface of the head, and the concentration of O(2) and CO(2) under the helmet) and in psychological parameters (motorcyclists' reflexes, fatigue, perceptiveness and mood). We also studied changes in the motorcyclists' subjective sensation of thermal comfort. The results made it possible to identify reliable parameters for assessing the effect of integral helmets on performance, i.e., physiological factors (head skin temperature, internal temperature and concentration of O(2) and CO(2) under the helmet) and on psychomotor factors (reaction time, attention and vigilance, work performance, concentration and a subjective feeling of mood and fatigue).

Prevalence of chronic venous disorders among employees working in prolonged sitting and standing postures.

Research was conducted to determine the prevalence and severity of chronic venous disorders (CVD) among people working in prolonged sitting or static standing postures. Clinical examination and duplex Doppler sonography were performed on 126 employees working in a sitting (96 individuals) or a standing posture (30 individuals). Evidence of CVD was found in 59.4% of individuals working in a sitting posture and in 83.4% of those working in a standing posture, and was significantly higher in employees working in a standing posture (p = .015). Incompetent perforating veins and vena saphena magna valves, and bilateral changes were the more frequent signs of CVD. The investigation showed that prolonged standing and sitting at work increases risk of developing CVD. Further, people working in a standing posture are at a significantly greater risk for CVD than those working in a prolonged sitting posture. They should thus be the subject of specific prophylaxis interventions.