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Nanotube deposition in a continuous arc reactor for varying arc gap and substrate temperature
Hamdan M. Yusoff,Rahul Shastry,Thomas Querrioux,John Abrahamson 한국물리학회 2006 Current Applied Physics Vol.6 No.3
A new continuous method for producing mounted carbon nanotubes (CNT) has been developed using the arc discharge method, in which a woven carbon substrate is used as a carbon source. In the process, carbon nanotubes grow on the fibres of the carbon substrate during the arc discharge. The method used differs from the conventional arc discharge method in that it deposits on the anode using low current (less than 20 A), with inter-electrode gaps of more than 5 mm and is run at atmospheric pressure, so that the substrate can be continuously fed and recovered. The aim of this work was to study the effect of the physical parameters of the arc on substrate surface temperature and on the CNT growth there. The effects of arc gap and buffer gas flow through the anodic substrate were investigated. An optical pyrometric technique was used to determine the substrate surface temperature. It was found that carbon nanotube growth was favoured over the temperature range 3600–3700 ± 50 K and not favoured at higher temperatures of 3800–4000 ± 50 K. This indicates that CNT growth is unlikely to be due to vaporization/condensation of small molecular carbon species.
Inhibitory Effect of Solid Inhibitors on LPG Combustible Mixtures
Hamdan, M. A.,Yamin, J. A.,Dabbas, R. K. Korean Chemical Society 2010 대한화학회지 Vol.54 No.3
액화석유가스-공기 불꽃에 대한 2가지 열적 금지제(즉, 돌가루, 탄산칼슘)의 억제효과를 연구하였다. 이를 위해 이들 금지제를 가하기 전과 후 가연성 혼합물의 가연성 한도를 측정하여 조사하였다. 그 결과, 탄산칼슘이 돌가루에 비해 억제 효과가 우수하였다. An experimental rig was constructed in order to study the inhibitory effects of two thermal inhibitors namely; stone and calcium carbonate, on Liquefied Petroleum Gas -air flames. This was achieved by measuring the flammability limits of the combustible mixtures before and after the addition of these inhibitors. It was found that calcium carbonate has superior inhibitory effect on the combustible mixture under investigation while, Stone has a lower inhibitory effect than that of calcium carbonate.
Droplets behavior impacting on a hot surface above the Leidenfrost temperature
Hamdan, Khaleel Sami,Kim, Dong-Eok,Moon, Sang-Ki Elsevier 2015 Annals of nuclear energy Vol.80 No.-
<P><B>Abstract</B></P> <P>Experimental studies of droplet behaviors impacting on a hot surface above the Leidenfrost temperature have been performed to provide improvements in the modeling of heat transfer in a ballooned surface characteristic of a loss-of-coolant accident (LOCA). Droplets of known size and velocity were impacted on a hot surface above the Leidenfrost temperature. The spreading of droplets into a liquid film on the surface and the breakup of the droplets were observed using a high-speed camera. For droplets of higher normal Weber number than a threshold value, the higher the normal Weber number of the droplet the smaller the secondary droplets. The conventional correlations showed fairly good agreements with the maximum spreading diameters of the droplets on the hot surface. On the other hand, the size of the secondary droplets resulting from an impact upon the hot surface was not well predicted by the COBRA-TF correlation. A new improved model for the secondary droplet size was developed using the mass conservation with a correction factor. The new model showed good predictions of the secondary droplet size for the present experiment as well as other experiments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The droplet behaviors impacting on a hot surface above the Leidenfrost temperature has been performed. </LI> <LI> The droplet diameters, velocities, and spreading diameters were measured. </LI> <LI> The COBRA-TF correlation over-predicts the breakup size of secondary droplets. </LI> <LI> A new model for the breakup size of secondary droplets was developed. </LI> <LI> The new model predicts the present experiments as well as other experiments. </LI> </UL> </P>
Hamdan Khaldoun Mohammad,Al-Bashaireh Ahmad M.,Al-Dalahmeh Mohammad,Saifan Ahmad Rajeh,Albqoor Maha Alkaid,Shaheen Abeer M. 대한중환자의학회 2023 Acute and Critical Care Vol.38 No.4
Background: There is a growing need for palliative care globally due to the rapid aging of the population and improvement in cancer survival rates. Adequate knowledge and a positive attitude are vital for palliative care nurses. The study’s purpose was to examine nurses’ knowledge and attitudes toward palliative care.Methods: A cross-sectional design with convenience sampling was used. The study included 182 intensive care unit (ICU) nurses from Jordanian hospitals in all sectors. Self-administered questionnaires were used to assess nurses' knowledge and attitudes toward palliative care. Descriptive statistics, analysis of variance, and the Kruskal-Wallis H test were used to analyze the data.Results: We measured nurses’ knowledge using the Palliative Care Quiz for Nursing, and we measured nurses' attitudes using the Frommelt Attitude Toward Care of the Dying scale. The mean total knowledge and attitude scores were 8.88 (standard deviation [SD], 2.52) and 103.14 (SD, 12.31), respectively. The lowest level of knowledge was in psychosocial and spiritual care (mean, 0.51±0.70). The percentage of nurses with unfavorable attitudes was 53.3%. Significant differences in knowledge and attitude levels were observed according to educational level, experience, and hospital type.Conclusions: ICU nurses have insufficient knowledge and inappropriate attitudes toward palliative care. Knowledge of psychological and spiritual aspects of palliative care was particularly lacking as were appropriate attitudes towards communication with dying patients. Improving knowledge and attitudes toward palliative care in nursing schools and hospitals would help overcome this problem.
Intention to Quit Smoking among Intermediate and Secondary School Students in Saudi Arabia
Abdulmohsen Hamdan, Al-Zalabani,Ayat Roushdy, Abdallah,Reem Ibrahim, Alqabshawi Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15
Background: Smoking is one of the most preventable causes of disease and death, including cancer, and quitting at an early age can reduce smoking-related morbidity and mortality. This study aimed to estimate the prevalence and to identify factors affecting the "intention to quit" among intermediate and secondary school current cigarette smoker students in Al Madinah city, Saudi Arabia. Materials and Methods: This study cohort included 307 current smoker students in a school-based survey. The intention to quit and its related determinants were assessed using a self-administered questionnaire. Results: More than half of the participants were ${\geq}17$ years, and of male gender (54.7%, 77.9% respectively). An intention to quit smoking was reported in 71.7% of participants, and was been significantly associated with: male gender (OR=3.25, 95% CI=1.65-6.41): age at 1st trial of smoking. 10-15 years (OR=2.11, 95% CI=1.03-4.32) along with age of ${\geq}15$ years (OR=3.10, 95% CI=1.20-7.88); days of smoking in the past 30 days (days <10 (OR=2.31, 95% CI=1.23-4.35) along with days ranging from 10-19 days (OR= 3.42, 95% CI=1.18-9.91); knowing that smoking is hazardous to health (OR=3.04, 95% CI=1.42-6.47); and finally, supporting smoking bans in public places (OR=1.89, 95% CI=1.11-3.25). Conclusions: A substantial number of participants were willing to quit smoking. Effective interventions focusing on providing information about the hazards of smoking and prohibiting smoking in public places could help initiate the intention to quit among youth smokers.
Employee Voice Mechanisms in The Kingdom of Saudi Arabia
Abdulmonem Hamdan Alzalabani 한국고용노사관계학회 2012 産業關係硏究 Vol.22 No.1
This paper explores employee voice practices and the effectiveness of the new system of employee representation that organisations in Saudi Arabia have started forming to provide a channel for workers to voice their interests inside the workplace. It will examine to what extent workers think the existence of these committees is important in the workplace, after several years of operation, and their effectiveness in achieving their goals. The data will cover many private sector organisations, including firms that already have workers’ committees and those that are expected to follow. Also, it will focus on the viewpoints of employees about employee participation practices in their organisations. The findings show that employee voice is practiced only in large companies in the private sector. However, the majority of employees support the formation of worker’s committees in their workplaces, although, in general, there is a lack of employee awareness of such committee regulations and the existing workers’ committees are evaluated as low effective. The results also identify four predictors of effectiveness of these committees: cooperation of employers, healthy industrial relations climate, employees’ participation and mutual trust between employees and their representatives.