1,355,146 research outputs found
Liquefying Fuel Combustion in a Lab-scale Vortex Flow Pancake Hybrid Rocket Engine
No full textThe combustion behavior of paraffin-based blends is investigated by a lab-scale vortex flow pancake motor (VFP). A complete pre-burning characterization for different paraffin-based fuel formulations is performed. The tested compositions are based on a micro-crystalline paraffin wax (W1), possibly blended with a styrene-based reinforcing polymer (SEBS-MA). Liquid paraffin (LP) is considered as an additional fuel ingredient for mechanical properties tailoring. The pre-burning characterization of the fuels includes thermal behavior investigation, rheological, tensile and compression analyses. In this preliminary investigation, 12 combustion tests are performed with quasisteady operating conditions. The main observable of interest is the solid fuel regression rate. Effects of the vortex flow combustion on the combustion efficiency are assessed by the characteristic velocity efficiency of the lab-scale system. The pre-burning characterization proves that SEBS-MA is a good candidate for improving the mechanical and thermal characteristics for the blends. LP had a significant impact on decreasing the viscosity of the blends
Hashish smoking and T-lymphocytes
No full textTo investigate the effect of long term hashish use on T-lymphocytes we have measured the incorporation of14C-thymidine by peripheral blood lymphocytes, unstimulated and stimulated by phytohemagglutinin, as well as the proportion and number of E-rosettes in 12 healthy male chronic users of the drug before and after a smoking session, and in 15 control subjects. The results show that hashish smoking does not impair the response of lymphocytes to PHA, at least at the concentration of PHA used. Furthermore there is a possibility that among chronic users a hashish smoking session may have a slight stimulatory effect. © 1978 Springer-Verlag
Effects of Vortex Flow Pancake Hybrid Rocket Engine Operating Parameters on Liquefying Fuel Combustion
No full textExperimental results from the vortex flow pancake hybrid rocket engine implemented at the Space Propulsion Laboratory of Politecnico di Milano are presented. Paraffin-based fuels are tested under quasi-steady and forced transient operating conditions. This preliminary investigation shows a database of more than 30 firings with quasi-steady operating conditions, and 4 runs with oxidizer mass flow rate throttling. The three main engine operating parameters varied in the current research are: (i) the oxidizer mass flow rate, (ii) the combustion chamber height, and (iii) the oxidizer injection velocity. The latter parameter is altered by changing the number of injectors for the oxidizer inlet flow. Throttling is performed on selected fuel formulations. Under the investigated conditions, the quasi-steady tests showed a regression rate decrease for increasing reinforcing polymer mass fraction in the paraffin-based blends. Such a result is due to the augmented viscosity of the melt layer of the formulations as the reinforcing polymer mass fraction increases. At the same time, the regression rate showed no direct dependence on the initial combustion chamber height, while oxidizer injection velocity dependence was identified. Forced transient tests showed an immediate response to throttling for the two investigated fuels
Effect of Hashish on Vigilance Performance
No full text A group of 11 hashish users were compared with 11 controls on a visual sustained attention (vigilance) task. Analysis indicated that hashish use affected subjects' sensitivity. Subjects who used hashish responded in an indiscriminate manner, making more false alarms (8.7) than controls (2.6). The importance of vigilance in the assessment of adverse effects of hashish is discussed. </jats:p
Hashish Addiction at Higher Education Institutions: Factors and Remedies
No full textHashish is considered to be the most widely and commonly used drug (UNODC, 2013, p-31). Hashish looks to be in usage of university students as well. A significant number of students have been reported with the usage of hashish regularly during their studies at universities. The usage of hashish is badly affecting the psychological and physical health of the students. The addict students have been found in street crimes as well. Therefore, this paper identifies the parental and societal factors of hashish addiction in universities students. To provide the remedies to overcome the usage of hashish in students, unstructured interviews were used as a tool of research. Purposive sampling was used in the selection of participants. The study is an empirical addition in the knowledge for the comprehension of hashish addiction in the students. The findings revealed a need for school wide consistency to address the usage of hashish in the students. It was concluded that students learned the usage of hashish from their parents as well. Parental illiteracy and poverty were found major factors of hashish addiction in the students. Students adopted the usage of hashish from senior students at university climate. The study can assist the school administration to evaluate their current efforts to overcome usage of hashish in students. The recommendations of the study are supportive in launching prevention programs for the hashish addiction in the students
Changes induced by hashish constituents on human erythrocyte phospholipids
No full textThe possible effect of Δ9-THC on human erythrocyte phospholipids of chronic hashish users was studied. Changes in individual phospholipids concentrations were observed in heavy hashish users after smoking the drug. Results are discussed in relation to the possible alterations of enzymatic mechanisms which require the presence of essential for their activation phospholipids. © 1979
Cellular Structures for Solid Fuel Grain Reinforcement: Mechanical and Combustion Performance in Conventional and Non-Conventional Hybrid Rocket Engines
No full textHashish Revival in Morocco
No full textInternational audienceBackground: In less than a decade, Morocco reportedly saw cannabis cultivation decrease by 65 %, and hashish production is widely believed to have followed the same trend. Yet large anomalies exist between the alleged fall of hashish production in Morocco and international seizure data. While no explanation for such a discrepancy existed, the main hypothesis was that cannabis cultivation and hashish production had not declined to the extent suggested by the available information. Methods: Based on existing data, on interviews with various actors, from European police sources to Moroccan cannabis cultivators, and on field research in Morocco, this article reviews contradictory available data and confronts it with observations made in the field. Results: In the past decade cannabis cultivation underwent radical changes that could explain the discrepancy between official Moroccan cultivation and production data on the one hand, and international seizures on the other hand. The "traditional" kif cannabis variety is being rapidly replaced by hybrids with much larger resin yields and much higher potency. This unnoticed phenomenon, which slowly started in the early 2000s, explains how a two-third decline in cannabis cultivation was at least partially compensated for by three to fivefold yield increases. Conclusion: The fact that the massive ongoing switch to hybrid cultivation is largely unknown or unaccounted for is actually a serious issue, for it directly questions the economic strategies that are being implemented in part to reduce and suppress cannabis cultivation in the Rif
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