Analysis of Water Transport in the Vicinity of Micro-Porous Layer in PEFC With Freezing Method

2013 ◽  
Author(s):  
Yusuke Aoyama ◽  
Kengo Suzuki ◽  
Yutaka Tabe ◽  
Takemi Chikahisa
Keyword(s):  
Catalyst Layer ◽  
Cathode Side ◽  
Cross Sectional ◽  
Porous Layers ◽  
Freezing Method ◽  
Water Condensation ◽  
Flow Channels ◽  
Condensed Water ◽  
Electronic Microscope

This paper examines the role of micro porous layers (MPLs) in Polymer Electrode Fuel Cells (PEFCs) by observing the cross-sectional distribution of condensed water inside a cathode side MPL In addition, the forms of water condensation in the vicinity of a MPL are also compared between two places, under flow channels and under lands, by observing both inside the MPL and an interface between the MPL and a catalyst layer (CL). The freezing method and a cryo-scanning electronic microscope (cryo-SEM) are used for the observation. The result under the non-flooded condition shows that condensed water does not accumulate inside the MPL. This result indicates that the water produced by PEFC power generation passes through the MPL as vapor state under non-flooded conditions.

Study on Water Transport Phenomena Through Micro-Porous Layers in PEFC

2012 ◽  
Author(s):  
Takemi Chikahisa ◽  
Yutaka Tabe ◽  
Kazumasa Kadowaki
Keyword(s):  
Water Transport ◽  
Water Distribution ◽  
Produced Water ◽  
Catalyst Layer ◽  
Operating Conditions ◽  
Water Flooding ◽  
Cathode Side ◽  
Porous Layers ◽  
Condensed Water ◽  
Vapor Pressure Gradient

Micro-porous layers (MPLs) play an important role in the water management of polymer electrolyte fuel cells (PEFCs), but details of the mechanism that works to suppress water flooding has not been fully understood. In this study, the authors investigated water distribution at the interface between the MPL and the catalyst layer (CL) at the cathode side to clarify the effect of the MPL on the discharge of produced water. A freezing method was applied to observe the distribution of the condensed water, and the ice distribution on the CL surface was quantified by image processing. The effects of operating conditions on the water distribution were examined at normal temperature conditions. The distribution of ice formed on the surface of the CL with and without MPL after −10°C cold start operation was also established. Water transport rate in the vapor phase was analyzed based on temperature and vapor pressure gradient considerations. The experiments and the analysis showed that the MPL functions to prevent accumulation of water on the surface of the CL, resulting in less water flooding.

Liquid Water Transport and Distribution in Fibrous Porous Media and Gas Channels

2008 ◽  
Author(s):  
Dirk Rensink ◽  
Jo¨rg Roth ◽  
Stephan Fell
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Catalyst Layer ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Operating Conditions ◽  
Cathode Side ◽  
Porous Layers ◽  
Micro Channels

In a polymer electrolyte membrane (PEM) fuel cell water is produced by electrochemical reactions in the catalyst layer on the cathode side. The water diffuses through the catalyst layer and a fibrous substrate into gas channels where it is transported away by convection. The fibrous substrate represents the gas diffusion media (GDM). Sometimes the GDM has a thin microporous layer on the side facing the catalyst layer. The same layer structure can be found on the anode side. All layers together are the porous layers of a PEM fuel cell. Under certain operating conditions condensation can occur in the porous layers which might lead to flooding conditions and — if the liquid water forms droplets which grow together in the gas channels — the complete blockage of the channels. Both situations can lead to a local starvation of reactant gases with negative impact on fuel cell performance and durability. The void space of the hydrophobic fibrous substrate in a PEM fuel cell can be interpreted as micro channels in a broader sense, especially if liquid phase transport from the catalyst layer towards the gas channels is in focus. Due to the small dimensions with effective channel diameter in the range of micrometer the flow of liquid water is governed by capillary forces. The same applies for the gas channels at low gas velocities since the Bond and Capillary numbers are well below one. Thus the investigation of liquid water flow and distribution under low gas velocities in the hydrophobic fibrous substrate and the spreading of liquid water along the hydrophilic gas channel walls under capillary action is of special interest for PEM fuel cells and investigated here.

Psychological Resilience Provides No Independent Protection From Suicidal Risk

Crisis ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Danica W. Y. Liu ◽  
A. Kate Fairweather-Schmidt ◽  
Richard Burns ◽  
Rachel M. Roberts ◽  
Kaarin J. Anstey
Keyword(s):  
Risk Factors ◽  
Well Being ◽  
Current Status ◽  
Psychological Resilience ◽  
Cross Sectional ◽  
Life Project ◽  
Resilience Factors ◽  
First Time

Abstract. Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.

Testing the Strain Theory of Suicide – The Moderating Role of Social Support

Crisis ◽  
2020 ◽  
Vol 41 (2) ◽  
pp. 82-88 ◽  
Author(s):  
Bob Lew ◽  
Ksenia Chistopolskaya ◽  
Yanzheng Liu ◽  
Mansor Abu Talib ◽  
Olga Mitina ◽  
...  
Keyword(s):  
Social Support ◽  
Suicidal Behavior ◽  
Online Survey ◽  
Perceived Social Support ◽  
Strain Theory ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Psychological Strains ◽  
Moderating Role

Abstract. Background: According to the strain theory of suicide, strains, resulting from conflicting and competing pressures in an individual's life, are hypothesized to precede suicide. But social support is an important factor that can mitigate strains and lessen their input in suicidal behavior. Aims: This study was designed to assess the moderating role of social support in the relation between strain and suicidality. Methods: A sample of 1,051 employees were recruited in Beijing, the capital of China, through an online survey. Moderation analysis was performed using SPSS PROCESS Macro. Social support was measured with the Multidimensional Scale of Perceived Social Support, and strains were assessed with the Psychological Strains Scale. Results: Psychological strains are a good predictor of suicidality, and social support, a basic need for each human being, moderates and decreases the effects of psychological strains on suicidality. Limitations: The cross-sectional survey limited the extent to which conclusions about causal relationships can be drawn. Furthermore, the results may not be generalized to the whole of China because of its diversity. Conclusion: Social support has a tendency to mitigate the effects of psychological strains on suicidality.

Role of Sildenafil in the Treatment of Persistent Pulmonary Hypertension of Newborn (PPHN) - Should it Be Withdrawn from Market of Bangladesh due to Threat of being Misuses

2020 ◽  
Vol 35 (2) ◽  
pp. 100-104
Author(s):  
Maksudur Rahman ◽  
Mohammad Abdullah Al Mamun ◽  
MAK Azad Chowdhury ◽  
Abu Sayeed Munsi
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Neonatal Intensive Care ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cardiac Intensive Care Unit ◽  
Cross Sectional ◽  
Cardiac Intensive Care ◽  
Hospital Protocol

Background: Recently it has been apprehended that sildenafil, a drug which has been successfully using in the treatment of PPHN and erectile dysfunction in adult, is going to be withdrawn from the market of Bangladesh due to threat of its misuses. Objective: The aim of this study was to see the extent of uses of sildenafil in the treatment of PPHN and importance of availability of this drugs in the market inspite of its probable misuses. Methods: This cross sectional study was conducted in neonatal intensive care unit (NICU), special baby care unit (SCABU) and cardiac intensive care unit (CICU) of Dhaka Shishu (Children) Hospital from June, 2017 to May 2018. Neonates with PPHN were enrolled in the study. All cases were treated with oral sildenefil for PPHN along with others management according to hospital protocol. Data along with other parameters were collected and analyzed. Results: Total 320 patients with suspected PPHN were admitted during the study period. Among them 92 (29%) cases had PPHN. Male were 49(53 %) cases and female were 43(47%) cases. Mean age at hospital admission was 29.7±13.4 hours. Based on echocardiography,13(14%) cases had mild, 38 (41%) cases moderate and 41(45%) cases severe PPHN. Mean duration of sildenafil therapy was 11.9±7.1 days. Improved from PPHN were 83 (90%) cases. Mortality was 10% (9). Conclusion: In this study it was found that the incidence of PPHN is 29% among the suspected newborns. Sildenafil is successfull in improving the oxygenation of PPHN and to decrease the mortality of neonates. DS (Child) H J 2019; 35(2) : 100-104

Role of Fibrinolytic Therapy in Empyema Thoracis – A Hospital Based one year Cross Sectional Study

2012 ◽  
Vol 2 (2) ◽  
pp. 345-350
Author(s):  
Dr. Girish.L Dandagi ◽  
◽  
Venkat kalyana kumar. P ◽  
Dr. Dr.Isaac Mathew ◽  
Dr. Dr.G S Gaude Dr. Dr.G S Gaude
Keyword(s):  
Cross Sectional Study ◽  
Fibrinolytic Therapy ◽  
Empyema Thoracis ◽  
Sectional Study ◽  
Cross Sectional ◽  
One Year

Sleep Reactivity and Psychological Health in Normal Sleepers: the moderating role of stress

2018 ◽  
Author(s):  
Jason G. Ellis ◽  
Sarah Allen ◽  
Michael Perlis ◽  
Michael Grandner ◽  
Maria Gardani ◽  
...  
Keyword(s):  
Life Events ◽  
Psychological Health ◽  
Public Health Campaign ◽  
Health Campaign ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Dysfunctional Cognitions ◽  
The Relationship ◽  
Moderating Role

The aim of the present study was to determine whether normal sleepers with vulnerability to insomnia, via high sleep reactivity, demonstrate more sleep-related dysfunctional cognitions and behaviours and poorer psychological health compared to those who are not vulnerable. Further, the influence of stress on the relationship between sleep reactivity and psychological health was also examined. A cross-sectional survey of 737 young adult ‘normal’ sleepers from the general population was undertaken. Results indicated normal sleepers vulnerable to insomnia demonstrated more sleep-related dysfunctional cognitions and behaviours as well as poorer psychological health compared to those not vulnerable. Furthermore, the relationship between sleep reactivity and psychological health was moderated by perceived stress over the previous month and life events over the previous year. Therefore, identifying and supporting those who are vulnerable to insomnia may be a fruitful avenue for preventative public health campaign to mitigate both insomnia and poor psychological health.

Alcohol use in daily life: Examining the role of trait and state impulsivity facets

2020 ◽  
Author(s):  
Sarah A Griffin ◽  
Timothy J Trull
Keyword(s):  
Alcohol Use ◽  
Sensation Seeking ◽  
Daily Life ◽  
Drinking Behavior ◽  
Cross Sectional ◽  
Trait Level ◽  
Trait Impulsivity ◽  
Drinking Behaviors ◽  
Ecological Momentary

Objectives: Using Ecological Momentary Assessment methods (EMA) we aimed to investigate the influence of trait and state (momentary) impulsivity on alcohol use behaviors in daily life. Facets of the UPPS trait model of impulsivity (Whiteside and Lynam, 2001) have been found to differentially relate to alcohol-related outcomes and behaviors in cross-sectional and longitudinal studies. The present work expands on this by assessing UPPS facets in daily life and examining the contributions of trait and state impulsivity facets to daily life drinking behavior. Methods: 49 participants were prompted at least six times per day for 21 days. A total of 4,548 collected EMA reports were included in analyses. Multi-level models were computed predicting daily life alcohol use behaviors from state and trait impulsivity facets and relevant covariates. Results: Individual facets of momentary impulsivity differentially related to alcohol outcomes, such that (lack of) premeditation and, to a lesser extent, sensation seeking showed unique patterns of association with drinking and drinking quantity. Only trait levels of (lack of) premeditation were related to drinking behavior in daily life; no other trait UPPS scale significantly related to alcohol use. Conclusions: These results highlight state difficulties with premeditation as particularly relevant to drinking behavior in daily life. Our results also support the incremental validity of state impulsivity facets over trait level measures in relation to drinking behavior in daily life. These findings offer important insight into the phenomenology of daily-life alcohol use and highlight possible avenues for intervention and prevention efforts. Public Health Statement: Momentary fluctuations in premeditation predict alcohol use in daily life. Treatments targeting planning or forethought in relation to alcohol use may interrupt this process contributing to daily life drinking behaviors.

SUBLINGUAL VITAMIN D3 DRUG THERAPY IN VITAMIN D DEFICIENCY PATIENTS AT PRAVARA RURAL HOSPITAL

2019 ◽  
pp. 18-20
Author(s):  
Sanjeeva Kumar Goud T ◽  
Rahul Kunkulol
Keyword(s):  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Vitamin D3 ◽  
Serum Vitamin ◽  
Cross Sectional ◽  
Serum Vitamin D ◽  
Significant Difference ◽  
Before And After

The present study was aimed to study the effect of Sublingual Vitamin D3 on Serum Vitamin D level in Vitamin D deficiency patients. This was a cross-sectional and interventional study. All the Vitamin D deficiency patients of age 18-60years and either gender, willing to participate in the study were included. Patients who had greater than 20 ng/ml were excluded from the study. The total number of participants in our study was 200, out of these 111 males and 89 females, the mean age in our study was 51.07 ± 7.39Yrs. All volunteers were given sublingual vitamin D3 (60,000IU) in six doses every fifteen days of follow up for 3 months. The subject’s serum 25(OH)D levels were estimated before and after the treatment of sublingual vitamin D3. There was a statistically significant difference in serum vitamin D3 level before 16.61±6.71 ng/ml and after 35.80±7.80 ng/ml after treatment with Sublingual Vitamin D3. Six doses of 60,000IU of Vitamin D3 sublingual route having improved the role of serum 25(OH)D levels in the treatment of Vitamin D3 deficiency patients.Keywords: Vitamin D3; Sublingual route

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