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Introduction: Historically, coronary angiography and percutaneous coronary intervention involved accessing the femoral artery via palpation. However, recently there has been a trend towards using a transradial approach and ultrasound guidance for arterial access. Studies have shown that these techniques respectively improve major bleeding rates and access outcomes. There have been no studies conducted that assess the time it takes to train operators to attain proficiency. This sub-analysis of the Standard versus Ultrasound-guided Radial and Femoral access in coronary angiography and intervention (SURF) trial aims to assess the number of procedures required to attain proficiency in ultrasound-guided transradial and transfemoral access. Methods: The SURF trial randomised 1,388 patients undergoing coronary angiography and/or percutaneous coronary intervention into standard or ultrasound-guidance and radial or femoral access in a 2×2 factorial design. Operators who participated in this trial were required to have performed at least 50 standard and 10 ultrasound-guided punctures for each of transradial and transfemoral access. Cases were then chronologically ordered and stratified into groups of five, from which the primary endpoint measured was a progression in mean access time and first-pass success rates. Results: Across all operators, there was a reduction in mean access time between procedures one to five and six to 10 with ultrasound-guided femoral punctures (60.5 secs–51.5 secs, p=0.029) and between procedures 11 to 15 and 16 to 20 ultrasound-guided radial punctures (74s to 62.5 secs, p=0.082). This trend was more obvious in trainees, with significant reductions in mean access time between procedures one to five and six to 10 from 73.5 to 53.5 seconds (p<0.001) for ultrasound-guided femoral access and from 99.5 seconds to 60 seconds (p=0.024) for ultrasound-guided radial access. There were no trends with standard transradial access. Conclusion: The numbers require

The digital age drives change in many sectors of life. In this age, correspondence between two continents happens immediately, and knowledge is exchanged and expended rapidly. Teachers as a focal figure in the realm of instruction are required to redress and even decipher these progressions as a methods for facilitating students to secure the 21st century capabilities. In any case, actually, a large number of teachers are hesitant to connect with these changes, particularly those related with the utilization of innovation in instruction and learning. In some developing countries, for example, Indonesia, a great deal of teachers are frustrated with the digital gap, less expertise in applying technology, limited supporting infrastructure, and students’ age variation. This article investigates the impact of short training on digital technology use in education to 29 primary teachers in Jakarta, Indonesia. The training course includes the introduction of the materials on digital learning, followed by assignment of looking for learning resources on the web, and an essay writing as the assessment to finish of the program. The observations and interviews with 7 respondents showed that the activity of the training improved the teachers’ digital literacy, especially in the utilization of technology in education. Era digital menyebabkan perubahan yang signifikan disetiap lini kehidupan. Pada masa ini komunikasi antar dua benua terjadi seketika, realitas dimodifikasi dan dikonsumsi secara cepat. Guru sebagai sosok sentral dalam dunia pendidikan dituntut untuk mengimbangi bahkan menerjemahkan perubahan tersebut sebagai sarana menghasilkan peserta didik yang memiliki kompetensi abad 21. Namun pada kenyataanya banyak guru yang segan bersinggungan dengan perubahan ini, khususnya yang berkaitan dengan pemanfaatan teknologi dalam pembelajaran. Di beberapa Negara berkembang seperti Indonesia banyak guru yang frustasi karena adanya jurang digital yakni kurang terampil dalam mangaplika

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

his paper presents detailed study of biogas reforming. Model biogas with different levels of H2S is subjected to reforming reaction over supported Ni catalyst in a fixed bed reactor at 700 °C and 800 °C. In order to understand the poisoning effects of H2S the reactions have been initially carried out without H2S in the feed stream. Three different H2S concentrations (20, 50 and 100 ppm) have been considered in the study. The H2O to CH4 ratio is maintained in such as way that CO2 also participates in the reforming reaction. After performing the poisoning studies, regeneration of the catalyst has been studied using three different techniques i) removal of H2S from the feed stream ii) temperature enhancement and iii) steam treatment. Poisoning at low temperature is not recoverable just by removal of H 2S from the feed stream. However, poisoning at high temperature is easily reversed just by removal of H2S from the feed stream. Unlike some previous reports by Li et al. (2010) and Rostrup-nielsen (1971) [1,2], catalyst regeneration is achieved in shorter time frames for all the regeneration techniques attempted

This paper deals with the development and validation of a detailed kinetic model for steam reforming of biogas with and without H2S. The model has 68 reactions among 8 gasphase species and 18 surface adsorbed species including the catalytic surface. The activation energies for various reactions are calculated based on unity bond index-quadratic exponential potential (UBI-QEP) method. The whole mechanism is made thermodynamically consistent by using a previously published algorithm. Sensitivity analysis is carried out to understand the influence of reaction parameters on surface coverage of sulfur. The parameters describing sticking and desorption reactions of H2S are the most sensitive ones for the formation of adsorbed sulfur. The mechanism is validated in the temperature range of 873-1200 K for biogas free from H 2S and 973-1173 K for biogas containing 20-108 ppm H2S. The model predicts that during the initial stages of poisoning sulfur coverages are high near the reactor inlet; however, as the reaction proceeds further sulfur coverages increase towards the reactor exit. In the absence of sulfur, CO and elemental hydrogen are the dominant surface adsorbed species. High temperature operation can significantly mitigate sulfur adsorption and hence the saturation sulfur coverages are lower compared to low temperature operation. Low temperature operation can lead to full deactivation of the catalyst. The model predicts saturation coverages that are comparable to experimental observation

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

This paper deals with the development and validation of a detailed kinetic model for steam reforming of biogas with and without H2S. The model has 68 reactions among 8 gasphase species and 18 surface adsorbed species including the catalytic surface. The activation energies for various reactions are calculated based on unity bond index-quadratic exponential potential (UBI-QEP) method. The whole mechanism is made thermodynamically consistent by using a previously published algorithm. Sensitivity analysis is carried out to understand the influence of reaction parameters on surface coverage of sulfur. The parameters describing sticking and desorption reactions of H2S are the most sensitive ones for the formation of adsorbed sulfur. The mechanism is validated in the temperature range of 873-1200 K for biogas free from H 2S and 973-1173 K for biogas containing 20-108 ppm H2S. The model predicts that during the initial stages of poisoning sulfur coverages are high near the reactor inlet; however, as the reaction proceeds further sulfur coverages increase towards the reactor exit. In the absence of sulfur, CO and elemental hydrogen are the dominant surface adsorbed species. High temperature operation can significantly mitigate sulfur adsorption and hence the saturation sulfur coverages are lower compared to low temperature operation. Low temperature operation can lead to full deactivation of the catalyst. The model predicts saturation coverages that are comparable to experimental observation

This paper deals with the development and validation of a detailed kinetic model for steam reforming of biogas with and without H2S. The model has 68 reactions among 8 gasphase species and 18 surface adsorbed species including the catalytic surface. The activation energies for various reactions are calculated based on unity bond index-quadratic exponential potential (UBI-QEP) method. The whole mechanism is made thermodynamically consistent by using a previously published algorithm. Sensitivity analysis is carried out to understand the influence of reaction parameters on surface coverage of sulfur. The parameters describing sticking and desorption reactions of H2S are the most sensitive ones for the formation of adsorbed sulfur. The mechanism is validated in the temperature range of 873-1200 K for biogas free from H 2S and 973-1173 K for biogas containing 20-108 ppm H2S. The model predicts that during the initial stages of poisoning sulfur coverages are high near the reactor inlet; however, as the reaction proceeds further sulfur coverages increase towards the reactor exit. In the absence of sulfur, CO and elemental hydrogen are the dominant surface adsorbed species. High temperature operation can significantly mitigate sulfur adsorption and hence the saturation sulfur coverages are lower compared to low temperature operation. Low temperature operation can lead to full deactivation of the catalyst. The model predicts saturation coverages that are comparable to experimental observation

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

Maintaining optimal temperature of the stack is critical for efficient operation of high temperature polymer electrolyte membrane fuel cells. While a number of possibilities of thermal management exist for small stacks, the problem becomes more complicated for larger stacks. In the present study, the thermal management of stacks in the power range of 1-10 kWe is considered through computational fluid dynamics simulations. It is shown that large stacks need to have dedicated cooling plates through which a coolant is circulated. Further, stacks of the size of 10 kWe can have reasonably low cell temperature variations (similar to 20 K) only by passing pre-heated liquid coolant through the coolant plates. Estimates show that the concomitant increase in the coolant flow rate induces large pressure drops, of the order of 30 bar, if a four-parallel serpentine is used on an active cell area of 30 cm x 30 cm. It is therefore necessary to use parallel channel flow fields with carefully designed feeder manifolds to maintain optimal cell temperatures and reasonably low coolant pressure drops in large stacks.

This paper deals with the development and validation of a detailed kinetic model for steam reforming of biogas with and without H2S. The model has 68 reactions among 8 gasphase species and 18 surface adsorbed species including the catalytic surface. The activation energies for various reactions are calculated based on unity bond index-quadratic exponential potential (UBI-QEP) method. The whole mechanism is made thermodynamically consistent by using a previously published algorithm. Sensitivity analysis is carried out to understand the influence of reaction parameters on surface coverage of sulfur. The parameters describing sticking and desorption reactions of H2S are the most sensitive ones for the formation of adsorbed sulfur. The mechanism is validated in the temperature range of 873-1200 K for biogas free from H 2S and 973-1173 K for biogas containing 20-108 ppm H2S. The model predicts that during the initial stages of poisoning sulfur coverages are high near the reactor inlet; however, as the reaction proceeds further sulfur coverages increase towards the reactor exit. In the absence of sulfur, CO and elemental hydrogen are the dominant surface adsorbed species. High temperature operation can significantly mitigate sulfur adsorption and hence the saturation sulfur coverages are lower compared to low temperature operation. Low temperature operation can lead to full deactivation of the catalyst. The model predicts saturation coverages that are comparable to experimental observation

his paper presents detailed study of biogas reforming. Model biogas with different levels of H2S is subjected to reforming reaction over supported Ni catalyst in a fixed bed reactor at 700 °C and 800 °C. In order to understand the poisoning effects of H2S the reactions have been initially carried out without H2S in the feed stream. Three different H2S concentrations (20, 50 and 100 ppm) have been considered in the study. The H2O to CH4 ratio is maintained in such as way that CO2 also participates in the reforming reaction. After performing the poisoning studies, regeneration of the catalyst has been studied using three different techniques i) removal of H2S from the feed stream ii) temperature enhancement and iii) steam treatment. Poisoning at low temperature is not recoverable just by removal of H 2S from the feed stream. However, poisoning at high temperature is easily reversed just by removal of H2S from the feed stream. Unlike some previous reports by Li et al. (2010) and Rostrup-nielsen (1971) [1,2], catalyst regeneration is achieved in shorter time frames for all the regeneration techniques attempted

Considerable heat is generated in a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) at high current densities which poses a challenge in the cooling of stack, especially in automobile applications which require high power densities. In the present study, we investigate the effectiveness of an external coolant system using a multiscale, stack heat transfer model on a commercially available computational fluid dynamics (CFD) computer code which takes account of the convective and conductive heat transfer occurring through various layers of the cell and stack elements of an HT-PEMFC operating at 473 K (200 °C). The model accounts for the coupling between the local cell temperature, the local current density and the local overpotential through an empirical polarization curve appropriate for the cell. Results from the simulations show that temperature variations within the stack can be kept to within 10 K by an optimal choice of the number of coolant plates, the coolant flow rate and the temperature at which it enters the stack. Specific power densities of up to 690 W kg−1 (based on the active volume of the fuel cell) have been obtained for a 1 kWe stack with graphite cooling plates located one for four cells.

Considerable heat is generated in a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) at high current densities which poses a challenge in the cooling of stack, especially in automobile applications which require high power densities. In the present study, we investigate the effectiveness of an external coolant system using a multiscale, stack heat transfer model on a commercially available computational fluid dynamics (CFD) computer code which takes account of the convective and conductive heat transfer occurring through various layers of the cell and stack elements of an HT-PEMFC operating at 473 K (200 °C). The model accounts for the coupling between the local cell temperature, the local current density and the local overpotential through an empirical polarization curve appropriate for the cell. Results from the simulations show that temperature variations within the stack can be kept to within 10 K by an optimal choice of the number of coolant plates, the coolant flow rate and the temperature at which it enters the stack. Specific power densities of up to 690 W kg−1 (based on the active volume of the fuel cell) have been obtained for a 1 kWe stack with graphite cooling plates located one for four cells.

Considerable heat is generated in a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) at high current densities which poses a challenge in the cooling of stack, especially in automobile applications which require high power densities. In the present study, we investigate the effectiveness of an external coolant system using a multiscale, stack heat transfer model on a commercially available computational fluid dynamics (CFD) computer code which takes account of the convective and conductive heat transfer occurring through various layers of the cell and stack elements of an HT-PEMFC operating at 473 K (200 °C). The model accounts for the coupling between the local cell temperature, the local current density and the local overpotential through an empirical polarization curve appropriate for the cell. Results from the simulations show that temperature variations within the stack can be kept to within 10 K by an optimal choice of the number of coolant plates, the coolant flow rate and the temperature at which it enters the stack. Specific power densities of up to 690 W kg−1 (based on the active volume of the fuel cell) have been obtained for a 1 kWe stack with graphite cooling plates located one for four cells.

Considerable heat is generated in a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) at high current densities which poses a challenge in the cooling of stack, especially in automobile applications which require high power densities. In the present study, we investigate the effectiveness of an external coolant system using a multiscale, stack heat transfer model on a commercially available computational fluid dynamics (CFD) computer code which takes account of the convective and conductive heat transfer occurring through various layers of the cell and stack elements of an HT-PEMFC operating at 473 K (200 °C). The model accounts for the coupling between the local cell temperature, the local current density and the local overpotential through an empirical polarization curve appropriate for the cell. Results from the simulations show that temperature variations within the stack can be kept to within 10 K by an optimal choice of the number of coolant plates, the coolant flow rate and the temperature at which it enters the stack. Specific power densities of up to 690 W kg−1 (based on the active volume of the fuel cell) have been obtained for a 1 kWe stack with graphite cooling plates located one for four cells.

This paper presents a detailed surface reaction mechanism for the decomposition of NH3 to H2 and N2 on a Ni surface. The mechanism is validated for temperatures ranging from 700 to 1500K and pressures from 5.3Pa to 100kPa. The activation energies for various elementary steps are calculated using the unity bond index-quadratic exponential potential (UBI-QEP) method. Sensitivity analysis is carried out to study the influence of various kinetic parameters on reaction rates. The NH3 decomposition mechanism is used to simulate SOFC button cell operating on NH3 fuel.

This paper presents a detailed surface reaction mechanism for the decomposition of NH3 to H2 and N2 on a Ni surface. The mechanism is validated for temperatures ranging from 700 to 1500K and pressures from 5.3Pa to 100kPa. The activation energies for various elementary steps are calculated using the unity bond index-quadratic exponential potential (UBI-QEP) method. Sensitivity analysis is carried out to study the influence of various kinetic parameters on reaction rates. The NH3 decomposition mechanism is used to simulate SOFC button cell operating on NH3 fuel.

This paper presents a detailed surface reaction mechanism for the decomposition of NH3 to H2 and N2 on a Ni surface. The mechanism is validated for temperatures ranging from 700 to 1500K and pressures from 5.3Pa to 100kPa. The activation energies for various elementary steps are calculated using the unity bond index-quadratic exponential potential (UBI-QEP) method. Sensitivity analysis is carried out to study the influence of various kinetic parameters on reaction rates. The NH3 decomposition mechanism is used to simulate SOFC button cell operating on NH3 fuel.

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds.

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds.

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds.

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds.

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds.

Risk Assessment is an activity that analyze a risk by determining the likelihood/ probability and severity ofconsequence / Consequences of a risk. This study is aimed to describe and assess the risk level in terms ofworker characteristics, equipment, materials, work processes and working environment of stone breakersworkers and making recommendations on hazard control efforts of workers.This was a descriptive qualitative research by conducting interviews on the workers and make observations onthe environment and work processes, and measuring the work environment. The study population was allworkers in the village of stone breaker Rowosari, Tembalang, Semarang with a sample of 41 people taken bysimple random sampling. Qualitative data analysis with content analysis using the form Hazard Identificationand Risk Assessment (HIRA).Results from this study is the level of risk of accidents at stone-breaking workers of each variable: thecharacteristics of workers with medium category, such as basket work tools, hammers, ganco and chairs with themedium category, with categories of stone material from the medium, such as the work process collecting,splitting, collecting and collating the stone with the medium category, and work environment with the mediumcategory. Workers are expected to wear the working tools such as carts and wearing personal protectiveequipment such as masks and gloves in order to reduce the risk of hazards during work.

Risk Assessment is an activity that analyze a risk by determining the likelihood/ probability and severity ofconsequence / Consequences of a risk. This study is aimed to describe and assess the risk level in terms ofworker characteristics, equipment, materials, work processes and working environment of stone breakersworkers and making recommendations on hazard control efforts of workers.This was a descriptive qualitative research by conducting interviews on the workers and make observations onthe environment and work processes, and measuring the work environment. The study population was allworkers in the village of stone breaker Rowosari, Tembalang, Semarang with a sample of 41 people taken bysimple random sampling. Qualitative data analysis with content analysis using the form Hazard Identificationand Risk Assessment (HIRA).Results from this study is the level of risk of accidents at stone-breaking workers of each variable: thecharacteristics of workers with medium category, such as basket work tools, hammers, ganco and chairs with themedium category, with categories of stone material from the medium, such as the work process collecting,splitting, collecting and collating the stone with the medium category, and work environment with the mediumcategory. Workers are expected to wear the working tools such as carts and wearing personal protectiveequipment such as masks and gloves in order to reduce the risk of hazards during work.