Perception Threshold for Pressure by a Soft Textile Actuator.

Electroactive textile (EAT) has the potential to apply pressure stimuli to the skin, e.g. in the form of a squeeze on the arm. To present a perceivable haptic sensation we need to know the perception threshold for such stimuli. We designed a set-up based on motorized ribbons around the arm with five different widths (range 3 - 49 mm) for psychophysical studies. We investigated the perception threshold of force pressure and ribbon reduction in two studies, using two methods (PSI and 1up/3down staircase), comparing sex, the left and right arm, the lower and upper arm, and stimulated surface area with a total of 57 participants. We found that larger stimulation surfaces require less pressure to reach the perception threshold (0.151 N per cm 2 for 3 mm width, 0.00972 N per cm 2 for 49 mm width on the lower arm). This indicates a spatial summation effect for these pressure stimuli. We did not find significant differences in perception threshold for the left and right arm and, the upper and lower arm. Between male and female participants we found significant differences for two conditions (10 mm and 25 mm) in Experiment 1, but we could not reproduce this in Experiment 2.

Highly Stretchable Multifunctional Wearable Devices Based on Conductive Cotton and Wool Fabrics.

The demand for stretchable, flexible, and wearable multifunctional devices based on conductive nanomaterials is rapidly increasing considering their interesting applications including human motion detection, robotics, and human-machine interface. There still exists a great challenge to manufacture stretchable, flexible, and wearable devices through a scalable and cost-effective fabrication method. Herein, we report a simple method for the mass production of electrically conductive textiles, made of cotton and wool, by hybridization of graphene nanoplatelets and carbon black particles. Conductive textiles incorporated into a highly elastic elastomer are utilized as highly stretchable and wearable strain sensors and heaters. The electromechanical characterizations of our multifunctional devices establish their excellent performance as wearable strain sensors to monitor various human motions, such as finger, wrist, and knee joint movements, and to recognize sound with high durability. Furthermore, the electrothermal behavior of our devices shows their potential application as stretchable and wearable heaters working at a maximum temperature of 103 °C powered with 20 V.

Personality, Driving Behavior and Mental Disorders Factors as Predictors of Road Traffic Accidents Based on Logistic Regression.

BACKGROUND: The aim of this study was to evaluate the effect of variables such as personality traits, driving behavior and mental illness on road traffic accidents among the drivers with accidents and those without road crash. METHODS: In this cohort study, 800 bus and truck drivers were recruited. Participants were selected among drivers who referred to Imam Sajjad Hospital (Tehran, Iran) during 2013-2015. The Manchester driving behavior questionnaire (MDBQ), big five personality test (NEO personality inventory) and semi-structured interview (schizophrenia and affective disorders scale) were used. After two years, we surveyed all accidents due to human factors that involved the recruited drivers. The data were analyzed using the SPSS software by performing the descriptive statistics, t-test, and multiple logistic regression analysis methods. P values less than 0.05 were considered statistically significant. RESULTS: In terms of controlling the effective and demographic variables, the findings revealed significant differences between the two groups of drivers that were and were not involved in road accidents. In addition, it was found that depression and anxiety could increase the odds ratio (OR) of road accidents by 2.4- and 2.7-folds, respectively (P=0.04, P=0.004). It is noteworthy to mention that neuroticism alone can increase the odds of road accidents by 1.1-fold (P=0.009), but other personality factors did not have a significant effect on the equation. CONCLUSION: The results revealed that some mental disorders affect the incidence of road collisions. Considering the importance and sensitivity of driving behavior, it is necessary to evaluate multiple psychological factors influencing drivers before and after receiving or renewing their driver's license.

Exploring a new method for the biological monitoring of plastic workers exposed to the vinyl chloride monomer.

Vinyl chloride monomer (VCM) is widely used in the production of polyvinyl chloride (PVC) plastics. VCM is recognized as a confirmed human and animal carcinogenic compound. Recent studies have reported poor health of plastic workers, even having exposure at concentrations below the permissible limit to VCM. There has not been any study regarding exposed workers to VCM in Iran. Similarly, no information exists as to the biological monitoring of such workers. The main purpose of this study was to conduct a thorough occupational and biological monitoring of Iranian plastic workers exposed to VCM.A total of 100 workers from two plastic manufacturing plants (A and B) in Tehran along with 25 unexposed workers as controls were studied. The personal monitoring of all nonsmoking workers exposed to VCM at two plastic manufacturing plants (A and B) was performed in the morning shift (8 a.m. to 4 p.m.) according to the National Institute For Occupational Safety And Health method no. 1007.Biological monitoring of workers was carried out through collection of exhaled breath of all exposed and control workers in Tedlar bags and with a subsequent analysis using gas chromatography-flame ionization detector.Not only the mean occupational exposure of workers to VCM at plant A was higher than the respective threshold limit value but also the statistical significance was higher than workers at plant B. Similarly, VCM concentration in exhaled breath of workers at plant A was also statistically significantly higher than at plant B. Correlation of occupational exposure of all workers to vinyl chloride with its concentration in exhaled breath was statistically significant.This is the first study on biological monitoring for exposed plastic workers to VCM using exhaled breath. On the basis of the results in this study, a novel method of biological monitoring of plastic workers was proposed.

Improved Method for Analysis of Airborne Asbestos Fibers Using Phase Contrast Microscopy and FTIR Spectrometry.

BACKGROUND: In recent years, some studies have tried to improve Phase Contrast Microscopy (PCM) for counting asbestos fibers. Due to the lack of a universally accepted alternative method, this study aimed to improve PCM for better counting of asbestos fibers. MATERIALS AND METHODS: Confirmed asbestos standards were applied using a dust generator for sampling. Sampling from the dust generator was carried out according to the Occupational Safety and Health Administration (OSHA) ID-160 method and 95 samples with diverse densities were prepared to be counted using conventional and modern PCM. All samples were counted single blindly by a co-author of this study and the obtained data were analyzed by paired t-test, correlation coefficient and Bland-Altman analysis. Duplicate samples were prepared for qualitative analysis by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X ray. RESULTS: Asbestos densities on filters were in the range of less than 100 to 600 fibers/mm(2). Statistically, significant differences were observed for the count density of the 95 samples counted by the two phase contrast microscopes (P<0.001). Nikon microscope demonstrated higher counts compared to conventional microscope and had a lower coefficient of variation. Samples were analyzed qualitatively using FT-IR and SEM, and the presence of asbestos fibers was confirmed. CONCLUSION: The improved PCM and FT-IR methods presented in this study demonstrated more precise and accurate determination of personal exposure to airborne asbestos fibers and subsequent risk assessment.

Outcomes of penetrating keratoplasty in keratoconus.

PURPOSE: Keratoconus (KCN) is one of the most common indications of corneal transplantation in Iran. This study was conducted to determine the outcomes of penetrating keratoplasty (PK) for KCN in patients operated in a private practice setting from 1994 to 2001. METHODS: This longitudinal retrospective study included 164 eyes of 164 patients. Variables included preoperative keratometry, trephination and suturing techniques, donor-recipient disparity, surgical complications, immunologic rejection, graft clarity, postoperative spherical and cylindrical refractive error, keratometry, uncorrected and best spectacle-corrected visual acuity, suture management, and the results of keratorefractive procedures. RESULTS: Patients were followed for a mean period of 33.5 months. Mean postoperative best spectacle-corrected visual acuity (BSCVA) at last follow-up was 0.14 +/- 0.11 LogMAR (20/25); mean spherical error and mean corneal astigmatism were -0.61 +/- 2.6 and 3.4 +/- 1.8 D, respectively. Final visual outcomes were not significantly correlated with trephination and suturing techniques or severity of the ectasia. Although donor-recipient disparity did not affect final astigmatism, more myopic shift was observed with greater disparity, but this finding was not of statistical significance. Overall, 26.8% of the patients required keratorefractive surgery, which resulted in 2.9 D reduction in corneal astigmatism. Immunologic graft rejection occurred in 28% of cases; however, all episodes responded to medical management, and none resulted in graft failure. CONCLUSION: Penetrating keratoplasty is a safe and effective procedure with remarkable optical and visual outcomes for patients with keratoconus who are contact lens intolerant or have unacceptable corrected visual acuity. Neither severity of the disorder nor trephination and suturing techniques significantly affects final visual outcomes. Less graft-recipient disparity (0.25 versus 0.50 mm) seems to induce less myopic shift.