In vitro and in vivo assessments of an optimal polyblend composition of polycaprolactone/gelatin nanofibrous scaffolds for Achilles tendon tissue engineering

In this study, we manufactured various ratios of polycaprolactone (PCL)/gelatin (GE) highly aligned electrospun nanofibrous scaffolds (ENs) to investigate the effects of polymer ratio on tenogenic differentiation activity. For biological assessments, the cell proliferation rate was optimal in the PCL/GE (9:1) group. Interestingly, however, the tenogenic differentiation rate was best for the PCL/GE (7:3) group. From our outcomes, we established that a poly-blending mix of PCL/GE (7:3) is a promising ratio for tenogenic differentiation. Thus, our findings may provide for an effective mesh to promote tenogenic differentiation of ENs in future tendon tissue engineering applications.This work was supported by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) & funded by the Korean government (MSIP&MOHW) (No. 2017M3A9E4048170)

Sensation of draft at uncovered ankles for women exposed to displacement ventilation and underfloor air distribution systems

Draft is defined as unwanted local convective cooling. Existing draft risk models, developed in the 1970s, focus on air movement at the neck. The purpose of the present study is to experimentally evaluate ankle draft risk for women with uncovered ankles because of current widespread use of displacement ventilation and underfloor air distribution systems and changes in dress customs. Thirty female university students participated in nine double-blind randomized tests. The subjects wore sandals with lower legs, ankles and feet uncovered. Exposures occurred in an environmental chamber resembling an office environment. The operative temperature at 1.1 m above the floor was maintained at 24.1 °C. The measured air speeds at the ankle varied between 0.16 and 0.59 m/s and the air temperature at the ankle varied between 18.0 and 21.7 °C. Subjective responses were obtained to assess these parameters: thermal acceptability, comfort, preference and sensation, air movement acceptability and preference, local thermal sensation and comfort, and perceived air quality. Subjects were more sensitive to ankle draft than expected. For all the tested conditions, between 20 and 37% of the subjects found the overall thermal environment not acceptable, while between 23 and 57% of the subjects found air movement at the ankle unacceptable. These dissatisfaction percentages are higher than those of international, American and European standards, indicating the need to develop a draft risk model for displacement ventilation and underfloor air distribution systems

Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering

This publication is the Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering from July 6-8, 2022. The EG-ICE International Workshop on Intelligent Computing in Engineering brings together international experts working on the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolution of challenges such as supporting multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways. &nbsp

Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering

This publication is the Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering from July 6-8, 2022. The EG-ICE International Workshop on Intelligent Computing in Engineering brings together international experts working on the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolution of challenges such as supporting multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways. &nbsp

Mass Accretion and Ozone Reactivity of Idealized Indoor Surfaces in Mechanically or Naturally Ventilated Indoor Environments

In indoor environments, accretion of mass to materials may provide sites for surface chemistry that differ from those of the original material. Since indoor surfaces are a major sink of oxidant gases, surface mass accretion may impact indoor O3 chemistry. In this study, the effect of surface mass accretion on O3 surface deposition was tested by deploying cleaned borosilicate glass plates in two types of indoor environments: a mechanically ventilated ( MV ) office and a naturally ventilated ( NV ) residence located in Singapore. In each environment, seven replicate glass plates and one field blank were deployed for between 7 - 56 days and examined in a laboratory chamber for O3 deposition rate and surface reaction probability. Average mass accretion to plates, deployed in a horizontal position and including deposited particles, was 10.6 mg/ ( m2 d ) in the MV office vs. 18.5 mg/ ( m2 d) in the NV residence and the comparison is at the threshold of statistical significance ( p = 0.054 ) . Ozone reactivity to the plates increased in magnitude and persistence with longer plate deployment. Ozone reaction probabilities to cleaned plates prior to deployment ranged [ 0.06–0.74 ] × 10-6 for two hours of observable removal whereas plates deployed for 56 days ranged [ 0.15–1.2 ] × 10-6 for four hours of observable removal. Regressions of cumulative O3 removed during chamber tests vs. mass accreted show removal of 4.3 nmol O3 / mg for the NV residence and 2.4 nmol O3 / mg for the MV office. These results imply that accretion of mass to surfaces may alter indoor O3 transformation pathways

Evaluation of human exposure to indoor airborne pollutants : transport and fate of particulate and gaseous pollutants

textBuilding environmental conditions such as ventilation and contaminant concentrations are important factors that influence occupant health and comfort. The objective of the present work is to investigate how personal exposure to gaseous and particulate pollutants depends on indoor airflow, source characteristics, and occupant activity in commercial and residential environments. The study examines airflow and pollutant transport using experimental measurements in conjunction with computational fluid dynamics (CFD). The results demonstrate that breathing has a measurable influence on the airflow in an occupant breathing zone, but it has very small impacts on the occupant thermal plume. The results also show that breathing can significantly affect inhaled particle concentrations, even though the influence varies with source position and particle size. Also, localized hand motions of a sitting manikin do not significantly disrupt the upward thermal plume. In typical US residences, forced convection driven mixing airflow or buoyancy driven stratified airflow occurs depending on the HVAC fan operation (fan on or fan off, respectively). The measured transition period between mixing flow (fan on) and stratified flow (fan off) is approximately one minute, implying that most airflow in the residence is either dominated by mixing or stratification. A high level of exposure to short-term pollutant sources, such as resuspension of particles from floor surfaces due to human activity, more likely occurs with stratified flow than with highly mixed airflow. This is due to the strong influence of the occupant thermal plume that transports the pollutants into the breathing zone. Furthermore, by transporting air containing ozone across the reactive occupant surface, the occupant thermal plume has a large effect on exposure to ozone reaction products. Due to the reaction of ozone with the skin oils and clothing surfaces, the occupant surface boundary layer becomes depleted of ozone and conversely enriched with ozone reaction products. The parameter ventilation effectiveness quantifies the effectiveness of airflow distribution and can be used for assessment of exposure to gaseous pollutants. Based on the study results, the usefulness of ventilation effectiveness as an indicator of exposure to particulate pollutants depends on the particle size. For small particles (~1 [mu]m), an increase of ventilation effectives caused a decrease in occupant exposure, while for large particles (~7 [mu]m), source location and airflow around the pollutant source are significant factors for the exposure, and the ventilation effectiveness has very little to no effect.Civil, Architectural, and Environmental Engineerin

Ozone Reaction With Interior Building Materials: Influence of Diurnal Ozone Variation, Temperature and Humidity

Elevated tropospheric ozone concentrations are associated with increased morbidity and mortality. Indoor ozone chemistry affects human exposure to ozone and reaction products that also may adversely affect health and comfort. Reactive uptake of ozone has been characterized for many building materials; however, scant information is available on how diurnal variation of ambient ozone influences ozone reaction with indoor surfaces. The primary objective of this study is to investigate ozone-surface reactions in response to a diurnally varying ozone exposure for three common building materials: ceiling tile, painted drywall, and carpet tile. A secondary objective is to examine the effects of air temperature and humidity. A third goal is to explore how conditioning of materials in an occupied office building might influence subsequent ozone-surface reactions. Experiments were performed at bench-scale with inlet ozone concentrations varied to simulate daytime (ozone elevated) and nighttime (ozone-free in these experiments) periods. To simulate office conditions, experiments were conducted at two temperatures (22 °C and 28 °C) and three relative humidity values (25%, 50%, 75%). Effects of indoor surface exposures were examined by placing material samples in an occupied office and repeating bench-scale characterization after exposure periods of 1 and 2 months. Deposition velocities were observed to be highest during the initial hour of ozone exposure with slow decrease in the subsequent hours of simulated daytime conditions. Daily-average ozone reaction probabilities for fresh materials are in the respective ranges of (1.7–2.7) × 10−5, (2.8–4.7) × 10−5, and (3.0–4.5) × 10−5 for ceiling tile, painted drywall, and carpet tile. The reaction probability decreases by 7%–47% across the three test materials after two 8-h periods of ozone exposure. Measurements with the samples from an occupied office reveal that deposition velocity can decrease or increase with time. Influence of temperature and humidity on ozone-surface reactivity was not strong

Energy and Cost Associated with Ventilating Office Buildings in a Tropical Climate

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This studyevaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the followingfactors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor airtemperature and humidity, air conditioning system coefficient of performance (COP), andcost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore’s tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment.Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore’s. This result implies that the benefits ofincreasing outdoor air ventilation rate up to 25 L/s per person—which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave—can be much larger than the incremental cost of ventilation

Ozone Reaction with Human Surfaces: Influences of Surface Reaction Probability and Indoor Air Flow Condition

It is well-established that indoor surfaces, such as building materials, act as a sink for indoor ozone. However, comparatively little research has been done regarding ozone reactions with human surfaces such as skin and clothing. Reaction characteristics of human surfaces and airflow around the human body may affect ozone removal and reaction byproduct formation. The objective of this study is to investigate effects of the reactivity of human surfaces, modeled for a range of reaction probabilities (γ), on ozone deposition and reaction byproduct formation. Computational fluid dynamics models are verified and validated with previously published studies, and used to analyze ozone reaction dynamics due to human surfaces under varying indoor air flow conditions. The results show that for indoor environments with air exchange rateh−1, ozone deposition velocity is in the range of 8–10 m/h for human skin oil while it is 2–3 m/h for clean clothing. Surface reactivity of the human body has a larger influence on the ozone deposition velocity than do the air exchange rates or indoor airflow patterns. Modeled emission rates of major reaction byproducts from ozone chemistry with human surfaces included acetone (0.3 mg/h/person), decanal (0.2 mg/h/person), nonanal (0.1 mg/h/person) and 6-MHO (0.1 mg/h/person) for a transport-limited scenario with 90 ppb bulk ozone concentration. These results imply that exposures to indoor ozone and reaction byproducts can be meaningfully modulated by an interaction of building airflow and chemistry occurring on and around individuals, and should be considered in models of human exposure