Large-area multilayer graphene was synthesised on Cu foil by DC plasma-enhanced chemical vapour deposition (DC PECVD) at a relatively low temperature. We discuss the growth mechanism of graphene in the plasma environment by the PECVD method based on the results of X-ray photoelectron spectroscopy, scanning electron microscopy and Raman scattering. Also, the I–V characteristics of graphene synthesised at different plasma powers was studied with a Keithley 2361 system. Due to the advantages of plasma growth, graphene synthesised under DC plasma exhibits better crystallinity, higher growth rate and large grain size at relatively low temperatures. At a plasma power of 100 W, the grain size of graphene (~5 μm) can be increased by a factor of 5. Raman spectroscopy showed D, G and 2D bound in our graphene samples while we find that the intensity of the D peak decreases by increasing the plasma power in growth conditions, which means that the defect density is reduced by the use of the plasma. The XPS results from the sample with maximum plasma power confirm the existence of sp 2 carbon atoms (C=C), which indicates the successful formation of graphene onto Cu foil by PECVD. In addition the increase of plasma power is attributed to larger grain sizes, thus leading to the increase of mobility and current change. This investigation shows that DC PECVD is a simple and effective technique to synthesise large-area multilayer graphene, which has potential for application as electronic devices.
The problem of drugs is one of the most important and serious issues which has attracted attention from different economic, social, political and psychological perspectives at international level. Statistics also indicate that the rate of drug abuse has increased among different communities, especially adolescents and the youth in recent decades (Malekyvar et al, 2007). According to the UN Office for Prevention of Drug Abuse and Crime in 2005, Iran has the largest number of drug addicts in proportion to the population in the world and there is a high rate of prevalence of drug abuse ( 8/2%) in Iran (Ziaie, 2009). According to Iran Drug Control Headquarters, the number of addicts has been 1.2 million in 2007, including 1,137,600 men and 62,400 women. (The annual book of Drug Control Headquarters, 2009: 8). In addition, in 2009, 231,908 individuals were arrested in connection with drug-related offenses of whom a total of 10,378 individuals come from Mazandaran province (Ibid. 51). Also, studies have shown that there is a correlation between behavior and attitude. In other words, attitudes are considered to be antecedents of behavior. Positive attitude towards drugs reduces the negative aspect of drug abuse and normalizes its use and distribution. Since negative effects of anything are usually more visible than its positive effects, it seems that we are experiencing a wide range of cultural chaos in our universities (Serajzadeh Javahery, 2033; Serajzadeh and Babaei, 2009). In such a context, study of attitude towards drugs among students (male and female) would be an important issue and deserves serious attention. In addition, a relatively neglected area of research related to students’ deviant behavior is theories of social interaction and the role that stigmatizing views play in shaping deviant behavior and favorable attitudes of students towards these behaviors. Labeling approach has mainly focused on reaction of social observers towards individuals and their behavior and consequences of this reaction and has paid less attention to the deviant behavior itself. In addition, labeling theorists claim that the way of dealing with offenders is more related to the way that significant others regard their actions rather than the behavior themselves. In this study we try to find an answer for this question: how does informal labeling, conducted by parents, friends and teachers, may lead to favorable attitudes towards drugs among students? In addition to measuring the attitudes of students towards drugs, this research examines labeling theory and its explanatory power to realize students’ attitudes towards drugs.
539 ABSTRACT: Disordered T-shaped graphene nanodevice (TGN) was designed and studied in this paper. We demonstrated the intrinsic transport properties of the TGN by using Landauer approach. Knowing the transmission probability of an electron the current through the system is obtained using Landauer-Buttiker formalism. The effects of single disorder on conductance, current and on the transport length scales are studied using tight-binding model. It is demonstrated that the transport property of the TGN depends sensitively on the disorder positions. However, the current slightly depends on the disorder sites, but strongly depends on the geometry of TGN under small bias voltage. The mean free path in the system is reduced when the strength of disorder is sufficiently high and the mean free path patterns are found to strongly depend on the disorder position. Also observe that the current basically decreases with the stem height increase. We have found that zigzag graphene nanoribbons can be used as metal leads when we build graphene nanodevice based electronic devices.
Abstract Different properties of nanostructured materials such as physical, chemical and catalytic properties based on metal nanoparticles for various applications have been studied extensively on account of their attraction these days. Nanocrystalline tungsten oxide (WO 2 ) can chemically break down adsorbed organic contaminants in sunlight. In this research work, a novel photocatalyst of WO 2 /glass mat nanocomposite has been prepared by hot filament chemical vapor deposition (HFCVD) method, which is used for the degradation of dyestuff from dyes wastewater. Morphology of treated mat was observed using a scanning electron microscope (SEM). The amounts of tungsten oxide on glass mat were examined using the energy dispersive X-ray (EDX) method. Electrical surface resistivity was also measured. It is concluded that oxidant sedimentation has been done physically without any structural changes and increasing of reaction time led to an increase in deposition of tungsten oxide and finally led to a decrease in the electrical resistance of glass mat. The photocatalytic activities of tungsten-oxide-deposited glass mat were assessed by analyzing the decrease in concentration of the methylene blue (MB) as a colorant after exposure to ultraviolet (UV) irradiation. The MB concentration decreases continuously, concomitant with the UV irradiation time up to 240 min. The results show that the WO 2 /glass mat nanocomposite exhibits high photocatalytic activity and provides a good way in the degradation field of dyes wastewater.
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