435 research outputs found
Components for PEM fuel cells: An overview
Fuel cells, as devices for direct conversion of the chemical energy of a fuel into
electricity by electrochemical reactions, are among the key enabling technologies for the transition
to a hydrogen-based economy. Among the various types of fuel cells, polymer electrolyte
membrane fuel cells (PEMFCs) are considered to be at the forefront for commercialization for
portable and transportation applications because of their high energy conversion efficiency and low
pollutant emission. Cost and durability of PEMFCs are the two major challenges that need to be
addressed to facilitate their commercialization. The properties of the membrane electrode assembly
(MEA) have a direct impact on both cost and durability of a PEMFC.
An overview is presented on the key components of the PEMFC MEA. The success of the MEA
and thereby PEMFC technology is believed to depend largely on two key materials: the membrane
and the electro-catalyst. These two key materials are directly linked to the major challenges faced in
PEMFC, namely, the performance, and cost. Concerted efforts are conducted globally for the past
couple of decades to address these challenges. This chapter aims to provide the reader an overview
of the major research findings to date on the key components of a PEMFC MEA
Cooperative Perception for Connected and Automated Vehicles: Evaluation and Impact of Congestion Control
Automated vehicles make use of multiple sensors to detect their surroundings. Sensors have significantly improved over the years but still face challenges due to the presence of obstacles or adverse weather conditions, among others. Cooperative or collective perception has been proposed to help mitigate these challenges through the exchange of sensor data among vehicles using V2X (Vehicle-to-Everything) communications. Recent studies have shown that cooperative perception can complement on-board sensors and increase the vehicle's awareness beyond its sensors field of view. However, cooperative perception significantly increases the amount of information exchanged by vehicles which can degrade the V2X communication performance and ultimately the effectiveness of cooperative perception. In this context, this study conducts first a dimensioning analysis to evaluate the impact of the sensors' characteristics and the market penetration rate on the operation and performance of cooperative perception. The study then investigates the impact of congestion control on cooperative perception using the Decentralized Congestion Control (DCC) framework defined by ETSI. The study demonstrates that congestion control can negatively impact the perception and latency of cooperative perception if not adequately configured. In this context, this study demonstrates for the first time that the combination of congestion control functions at the Access and Facilities layers can improve the perception achieved with cooperative perception and ensure a timely transmission of the information. The results obtained demonstrate the importance of an adequate configuration of DCC for the development of connected and automated vehicles
Multinomial Logistic Regression Model for the Inferential Risk Age Groups for Infection Caused by \u3cem\u3eVibrio cholerae\u3c/em\u3e in Kolkata, India
Multinomial Logistic Regression (MLR) modeling is an effective approach for categorical outcomes, as compared with discriminant function analysis and log-linear models for profiling individual category of dependent variable. To explore the yearly change of inferential age groups of acute diarrhoeal patients infected with Vibrio cholerae during 1996-2000 by MLR, systematic sampling data were generated from an active surveillance study. Among 1330 V.cholerae infected cases, the predominant age category was up to 5 years accounting for 478 (30.5%) cases. The independent variables V.cholerae O1 (p\u3c0.001) and non-O1 and non-O139 (p \u3c 0.001) were significantly associated with children under 5 years age group. V.cholerae O139 inferential age group was \u3e 40 years. The infection mediated by V.cholerae O1 had significantly decreasing trend Exp(B) year wise from 1996 to 2000 (p \u3c 0.001, p \u3c 0.001, p \u3c 0.001, p \u3c 0.001 and p \u3c 0.001, respectively). MLR model showed that up to 5 year’s age children are more vulnerable to infection caused by V.cholerae O1
Generation of Cooperative Perception Messages for Connected and Automated Vehicles
Connected and Automated Vehicles (CAVs) utilize a variety of onboard sensors
to sense their surrounding environment. CAVs can improve their perception
capabilities if vehicles exchange information about what they sense using V2X
communications. This is known as cooperative or collective perception (or
sensing). A frequent transmission of collective perception messages could
improve the perception capabilities of CAVs. However, this improvement can be
compromised if vehicles generate too many messages and saturate the
communications channel. An important aspect is then when vehicles should
generate the perception messages. ETSI has proposed the first set of message
generation rules for collective perception. These rules define when vehicles
should generate collective perception messages and what should be their
content. We show that the current rules generate a high number of collective
perception messages with information about a small number of detected objects.
This results in an inefficient use of the communication channel that reduces
the effectiveness of collective perception. We address this challenge and
propose an improved algorithm that modifies the generation of collective
perception messages. We demonstrate that the proposed solution improves the
reliability of V2X communication and the perception of CAVs
Effect of dimethyl sulfoxide on mouse embryo fibroblasts: inhibition of plasminogen activator inhibitor deposition and interference with early events of serum-stimulated growth
Quiescent and serum-stimulated cultures of Swiss mouse embryo fibroblasts (MEF) showed alterations in cell morphology including an enlargement in size upon treatment with 2% dimethyl sulfoxide (DMSO). Treatment of MEF and monkey kidney epithelial cells (MK2) with 2% DMSO at the early periods of serum-stimulated growth inhibited RNA, protein and DNA synthesis. DMSO treatment of cells at late stages of serum-stimulated growth (MEF after 1 hr and MK2 cells after 3 hr of stimulation) had little effect on DNA and protein synthesis although cell enlargement occurred in these cells. When the [35S]methionine labelled proteins of the control and the DMSO treated cells were analysed by high resolution polyacrylamide gel electrophoresis, no apparent difference was observed in the pattern of intracellular proteins of these cells. In contrast, the extracellular levels of two serum-induced secreted proteins of MEF (Mr 48,000 and 26,000) were dramatically reduced by DMSO treatment. The DMSO sensitive 48 kDa protein was found to be the major component of the extracellular matrix, while the 26 kDa protein was not. The 48 kDa protein was identified as plasminogen activator inhibitor (PAI-1). Densitometric quantitation showed a gradual accumulation of this protein in the matrix of serum-stimulated cells. The deposition of this protein in the matrix was inhibited by DMSO. Flow-cytometric quantitation of indirect immunofluorescence indicated higher intracellular levels of the 48 kDa protein in fetal calf serum (FCS) + DMSO treated cells, suggesting that the low level of this protein in the medium of DMSO treated cells is probably due to lack of transport of this protein from the cells into the medium
Log-linear Model to Assess Socioeconomic and Environmental Factors with Childhood Diarrhea Using Hospital Based Surveillance
Categorical outcomes with environment factors analyzed by log linear model are frequent in the environmental epidemiological literature. Epidemiological and socio-economical factors were obtained on 1,119 children below the age of 5 from Infectious Diseases Hospital (IDH) at the Kolkata, India. Significant associations of diarrhea were observed in the rural areas with family income, father’s occupation as a daily labor, literacy of parents, non-cemented floor and wall constructed of mud, and type of storage (wide mouthed earthen pot). The results of the study with specific Log linear model confirm environmental factors were important implications for childhood diarrhea in the rural community. To reduce the diseases burden, the intervention strategies such as education, improvement of economic status and living environment are recommended
Schisandrin B, a Lignan from Schisandra chinensis Prevents Cerebral Oxidative Damage and Memory Decline Through Its Antioxidant Property
The Role of Calcium-activated Potassium Channel in Mitochondria-Associated ER Membrane and Its Functional Link to Cell Survival and Death
The process of apoptosis is not only regulated by molecular gens but it is also regulated by cellular ionic homeostasis especially K+ homeostasis in the cell. In the past decade, molecular mechanisms of ionic regulation of apoptosis have been extensively investigated. The ionic mechanism of apoptosis are involves Ca2+ influx and accumulation of intracellular Ca2+ is convincing evidence to excessive K+ efflux resulting in early steps in apoptosis. The BK channels play a critical role in mediating the K+ efflux linked with apoptotic cell shrinkage. Mitochondria-associated ER membranes (MAMs) control Ca2+ influx between ER and mitochondria. The BKα subunits are localized in the inner mitochondrial and ER membrane and directly interact with other BK channel associated proteins (BKAPs) like, IP3R-1, calreticulin at the ER face of the MAMs, and the molecular chaperone grp78, which bridges the IP3R-1 with voltage-dependent anion channel (VDAC-1) of the outer mitochondrial membrane (OMM). The present chapter clearly depicts that how BK channels are associated with BKAPs and how they are involved in apoptosis through regulation of K+ efflux
Context-based Broadcast Acknowledgement for Enhanced Reliability of Cooperative V2X Messages
Most V2X applications/services are supported by
the continuous exchange of broadcast messages. One of the main
challenges is to increase the reliability of broadcast transmissions
that lack of mechanisms to assure the correct delivery of the
messages. To address this issue, one option is the use of
acknowledgments. However, this option has scalability issues
when applied to broadcast transmissions because multiple
vehicles can transmit acknowledgments simultaneously. To
control scalability while addressing reliability of broadcast
messages, this paper proposes and evaluates a context-based
broadcast acknowledgement mechanism where the transmitting
vehicles selectively request the acknowledgment of
specific/critical broadcast messages, and performs
retransmissions if they are not correctly received. In addition, the
V2X applications/services identify the situations/conditions that
trigger the execution of the broadcast acknowledgment
mechanism, and the receiver(s) that should acknowledge the
broadcast messages. The paper evaluates the performance of the
context-based broadcast acknowledgment mechanism for a
Collective Perception Service. The obtained results show the
proposed mechanism can contribute to improve the awareness of
crossing pedestrians at intersections by increasing the reliability
in the exchange of CPM messages between vehicles approaching
the intersection. This solution is being discussed under IEEE
802.11bd, and thus can be relevant for the standardization
process.10.13039/501100000780-European Commission;10.13039/501100007170-Ministry of Econom
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