Search

Human exhalation flow is a potential source of pathogens that can constitute a cross-infection risk to people in indoor environments. Thus, it is important to investigate the characteristics of this flow, its development, area of influence, and the diffusion of the exhaled contaminants. This paper uses phase-averaged particle image velocimetry together with a tracer gas ( CO2) to study two different exhalation flows over time: the exhalation of an average male (test M) and an average female (test F), using a life-sized thermal manikin in a supine position. The exhalation jets generated for both tests are similar in terms of symmetrical geometry, vorticity values, jet opening angles, and velocity and concentration decays. However, there is a difference in the penetration length of the two flows throughout the whole exhalation process. There is also a time difference in reaching maximum velocity between the two tests. It is also possible to see that the tracer gas dispersion depends on the momentum of the jet so the test with the highest velocity decay shows the lowest concentration decay. All these results are of interest to better understand cross-infection risk. [ABSTRACT FROM AUTHOR]

Downward flow ventilation systems are one of the most recommended ventilation strategies when contaminants in rooms must be removed and people must be protected from the risk of airborne cross-infection. This study is based on experimental tests carried out in a room with downward flow ventilation. Two breathing thermal manikins are placed in a room face to face. One manikin's breathing is considered to be the contaminated source to simulate a risky situation with airborne cross-infection. The position of the manikins in relation to the diffuser and the location of diffuser in the room as well as the distance between the manikins are being changed to observe the influence of these factors on the personal exposure of the target manikin. The results show that the DWF in different situations often is unable to penetrate the microenvironment generated by the manikins. The downward ventilation system can give an unexpected high level of contaminant exposure of the target manikin, when the distance between the manikins is reduced. Practical Implications Several guidelines recommend the downward ventilation system to reduce the risk of cross-infection between people in hospital rooms. This study shows that this recommendation should be taken into careful consideration. It is important to be aware of people position, position to other thermal loads in the room, and especially be aware of the distance between people if the exposure to the exhaled contaminants wants to be reduced. [ABSTRACT FROM AUTHOR]

The level of exposure to human exhaled contaminants in a room depends not only on the air distribution system but also on people's different positions, the distance between them, people's activity level and height, direction of exhalation, and the surrounding temperature and temperature gradient. Human exhalation is studied in detail for different distribution systems: displacement and mixing ventilation as well as a system without mechanical ventilation. Two thermal manikins breathing through the mouth are used to simulate the exposure to human exhaled contaminants. The position and distance between the manikins are changed to study the influence on the level of exposure. The results show that the air exhaled by a manikin flows a longer distance with a higher concentration in case of displacement ventilation than in the other two cases, indicating a significant exposure to the contaminants for one person positioned in front of another. However, in all three cases, the exhalation flow of the source penetrates the thermal plume, causing an increase in the concentration of contaminants in front of the target person. The results are significantly dependent on the distance and position between the two manikins in all three cases. Practical Implications Indoor environments are susceptible to contaminant exposure, as contaminants can easily spread in the air. Human breathing is one of the most important biological contaminant sources, as the exhaled air can contain different pathogens such as viruses and bacteria. This paper addresses the human exhalation flow and its behavior in connection with different ventilation strategies, as well as the interaction between two people in a room. This is a key factor for studying the airborne infection risk when the room is occupied by several persons. The paper only takes into account the airborne part of the infection risk. [ABSTRACT FROM AUTHOR]

Abstract: Containerised cogeneration sets, CCSs, are an efficient answer for remote developing regions which do not have alternative energy sources and for those applications requiring mobility and the quick installation of energy plants. Nevertheless, CCSs can present over-heating problems as a result of inefficient ventilation. The heat dissipated by each of the 28 elements under consideration in the engine compartment was assessed, together with the mass flow rate of air supplied to the cab and the air temperature at the inlet and outlet. A Computational Fluid Dynamics (CFD) model has been developed that allows for simulation of the parameters of velocity, temperature and pressure and for calculating the heat flows in a CCS with a reciprocating diesel engine, with an alternator power of 903kW. Predictions from this model have been contrasted with the experimental data obtained in a series of measurements. The CFD model has been used to analyse possible alternatives for improving the ventilation system. Besides the use of insulation to reduce the heat dissipated, other alternatives have been studied: e.g., improving the airflow by fitting a metal sheet as a deflector, or using a third fan. Of the three alternatives analysed, the company has decided to incorporate the simplest and cheapest, consisting in fitting a metal sheet around the alternator. [Copyright &y& Elsevier]

This study aims to optimise the water vapour adsorption capacity of polylactic acid (PLA) and wood composite materials for application in dehumidification systems through material extrusion additive manufacturing. By analysing key process parameters, including nozzle diameter, layer height, and temperature, the research evaluates their impact on the porosity and adsorption performance of the composite. Additionally, the influence of different infill densities on moisture absorption is investigated. The results show that increasing wood content significantly enhances water vapour adsorption, with nozzle diameter and layer height identified as the most critical factors. These findings confirm that composite materials, especially those with higher wood content and optimised printing parameters, offer promising solutions for improving dehumidification efficiency. Potential applications include heating, ventilation, and air conditioning systems or environmental control. This work introduces an innovative approach to using composite materials in desiccant-based dehumidification and provides a solid foundation for future research. Further studies could focus on optimising material formulations and scaling this approach for broader industrial applications.

Energy needs in the buildings sector accounts for 40 % of global energy demand. Therefore, the implementation of several renewable energy sources is necessary to reduce this demand. The design stage of a decentralized generation project requires quantifying the power to be installed and the energy forecast for each source throughout the useful life of the building. This study develops a novel optimization algorithm for a long-term economic function based on mixed-integer disciplined convex programming (MIDCP) which guarantees the sustainability of the building and its energy systems. The robust algorithm integrates risk management of intermittent sources, technical and economic parameters of selected technologies, and life cycle analysis (LCA) of different energy systems, including storage. Furthermore, the penetration of green hydrogen into the distributed generation mix is evaluated as an important contribution. Meteorological and energy demand variables of two antagonistic scenarios were also used as inputs to the algorithm. As a result, the optimal energy supply sizing for tertiary buildings in the two defined locations was obtained. The results of the simulations have achieved an optimal convergence of 100 % in the proposed scenarios, with a resolution time of 14 s and using a memory of about 183 MB. The simulations suggest a higher penetration of green hydrogen in scenarios where supply and investment costs decrease to gray hydrogen supply levels, reaching up to 81 % coverage of the thermal demand of the building. Hybrid energy systems under favorable conditions show a penetration of about 92 % within the distributed generation mix. The developed tool could enable decision-makers to optimally plan distributed generation projects in buildings based on economic, policy, and geographic conditions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Aims: Residual beta cell function in type 1 diabetes (T1D) is associated with lower risk of complications. Autoantigen therapy with GAD-alum (Diamyd) given in 3 intralymphatic injections with oral vitamin D has shown promising results in persons with T1D carrying the human leukocyte antigen (HLA) DR3-DQ2 haplotype in the phase 2b trial DIAGNODE-2. We aimed to explore the efficacy of intralymphatic GAD-alum on blood glucose recorded by continuous glucose monitoring (CGM)., Methods: DIAGNODE-2 (NCT03345004) was a multicenter, randomized, placebo-controlled, double-blind trial of 109 recent-onset T1D patients aged 12 to 24 years with GAD65 antibodies and fasting C-peptide > 0.12 nmol/L, which randomized patients to 3 intralymphatic injections of 4 μg GAD-alum and oral vitamin D, or placebo. We report results for exploratory endpoints assessed by 14-day CGM at months 0, 6, and 15. Treatment arms were compared by mixed-effects models for repeated measures adjusting for baseline values., Results: We included 98 patients with CGM recordings of sufficient quality (DR3-DQ2-positive patients: 27 GAD-alum-treated and 15 placebo-treated). In DR3-DQ2-positive patients, percent of time in range (TIR, 3.9-10 mmol/L) declined less between baseline and month 15 in GAD-alum-treated compared with placebo-treated patients (-5.1% and -16.7%, respectively; P = 0.0075), with reduced time > 13.9 mmol/L (P = 0.0036), and significant benefits on the glucose management indicator (P = 0.0025). No differences were detected for hypoglycemia. GAD-alum compared to placebo lowered the increase in glycemic variability (standard deviation) observed in both groups (P = 0.0219). Change in C-peptide was correlated with the change in TIR., Conclusions: Intralymphatic GAD-alum improves glycemic control in recently diagnosed T1D patients carrying HLA DR3-DQ2., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: To evaluate the efficacy of aluminum-formulated intralymphatic glutamic acid decarboxylase (GAD-alum) therapy combined with vitamin D supplementation in preserving endogenous insulin secretion in all patients with type 1 diabetes (T1D) or in a genetically prespecified subgroup., Research Design and Methods: In a multicenter, randomized, placebo-controlled, double-blind trial, 109 patients aged 12-24 years (mean ± SD 16.4 ± 4.1) with a diabetes duration of 7-193 days (88.8 ± 51.4), elevated serum GAD65 autoantibodies, and a fasting serum C-peptide >0.12 nmol/L were recruited. Participants were randomized to receive either three intralymphatic injections (1 month apart) with 4 μg GAD-alum and oral vitamin D (2,000 IE daily for 120 days) or placebo. The primary outcome was the change in stimulated serum C-peptide (mean area under the curve [AUC] after a mixed-meal tolerance test) between baseline and 15 months., Results: Primary end point was not met in the full analysis set (treatment effect ratio 1.091 [CI 0.845-1.408]; P = 0.5009). However, GAD-alum-treated patients carrying HLA DR3-DQ2 ( n = 29; defined as DRB1*03, DQB1*02:01) showed greater preservation of C-peptide AUC (treatment effect ratio 1.557 [CI 1.126-2.153]; P = 0.0078) after 15 months compared with individuals receiving placebo with the same genotype ( n = 17). Several secondary end points showed supporting trends, and a positive effect was seen in partial remission (insulin dose-adjusted HbA 1c ≤9; P = 0.0310). Minor transient injection site reactions were reported., Conclusion: Intralymphatic administration of GAD-alum is a simple, well-tolerated treatment that together with vitamin D supplementation seems to preserve C-peptide in patients with recent-onset T1D carrying HLA DR3-DQ2. This constitutes a disease-modifying treatment for T1D with a precision medicine approach., (© 2021 by the American Diabetes Association.)

A hospital room is simulated using two breathing thermal manikins representing a health worker (HW) and a patient in repose (PR). The PR exhales R134a simulating small exhaled particles (<5 μm) and the contaminant concentration around and in the inhalation of HW is measured during a period of 2 hours per experiment. The room is climatized to maintain constant air temperature values of 25 °C using two wall mounted grilles and two exhausts. The air change per hour (ACH) used varies from 6 to 12 in order to evaluate its influence on the dispersion of exhaled contaminants. An external heat gain is simulated by a radiant wall (RW) that is active or inactive during the experiments. When RW is active the external heat gain simulated is 39.7 W/m 2 , which corresponds to a solar external radiation typical in many countries worldwide. The contaminant concentration is measured at different locations around HW and in the inhalation tube. The temperature gradient in the room is also measured along a vertical pole. The discussion of the results of the 16 experimental cases can be found in Ref. [1].

Efficient ventilation in hospital airborne isolation rooms is important vis-à-vis decreasing the risk of cross infection and reducing energy consumption. This paper analyses the suitability of using a displacement ventilation strategy in airborne infection isolation rooms, focusing on health care worker exposure to pathogens exhaled by infected patients. The analysis is mainly based on numerical simulation results obtained with the support of a 3-D transient numerical model validated using experimental data. A thermal breathing manikin lying on a bed represents the source patient and another thermal breathing manikin represents the exposed individual standing beside the bed and facing the patient. A radiant wall represents an external wall exposed to solar radiation. The air change efficiency index and contaminant removal effectiveness indices and inhalation by the health care worker of contaminants exhaled by the patient are considered in a typical airborne infection isolation room set up with three air renewal rates (6 h-1, 9 h-1 and 12 h-1), two exhaust opening positions and two health care worker positions. Results show that the radiant wall significantly affects the air flow pattern and contaminant dispersion. The lockup phenomenon occurs at the inhalation height of the standing manikin. Displacement ventilation renews the air of the airborne isolation room and eliminates the exhaled pollutants efficiently, but is at a disadvantage compared to other ventilation strategies when the risk of exposure is taken into account., Competing Interests: The authors have declared that no competing interests exist.