Properties of tetrahedral amorphous carbon prepared by vacuum arc deposition

The structural, optical, electrical and physical properties of amorphous carbon deposited from the filtered plasma stream of a vacuum arc were investigated. The structure was determined by electron diffraction, neutron diffraction and energy loss spectroscopy and the tetrahedral coordination of the material was confirmed. The measurements gave a nearest neighbour distance of 1.53 Å, a bond angle of 110 and a coordination number of four. A model is proposed in which the compressive stress generated in the film by energetic ion impact produces pressure and temperature conditions lying well inside the region of the carbon phase diagram within which diamond is stable. The model is confirmed by measurements of stress and plasmon energy as a function of ion energy. The model also predicts the formation of sp²-rich materials on the surface owing to stress relaxation and this is confirmed by a study of the surface plasmon energy. Some nuclear magnetic resonance, infrared and optical properties are reported and the behaviour of diodes using tetrahedral amorphous carbon is discussed.     

Integrated MR imaging approach to valvular heart disease

With development of cine and velocity encoded magnetic resonance imaging, it is now feasible to detect and quantify aortic and mitral stenosis and regurgitation accurately. In addition, magnetic resonance imaging has the capabilities to assess simultaneously left and right ventricular mass, volumes, and function precisely. The high accuracy and reproducibility of magnetic resonance imaging in quantification of regurgitation and ventricular function has the potential to provide improved monitoring of therapy and optimal timing of surgery in patients with valvular dysfunction. In comparison to echocardiography and angiography, some current limitations of magnetic resonance imaging to an integrated approach of valvular heart disease exist, which may be removed with future refinement of magnetic resonance imaging technology for cardiovascular imaging.     

Polystyrene foams. II. Structure–impact properties relationships

In the first part of this series of articles, the relations between the foaming conditions and the microstructure of expanded polystyrene (EPS) were explored. In this part, the effects of the foaming conditions and the microstructure of EPS on impact properties are discussed. Regression analysis was conducted on the data and expressions were developed to quantify these relationships. Moreover, the importance of the individual structural parameters was determined. Statistical analysis of the data showed that foaming time was the most important factor determining the impact strength, while foaming temperature was the most important factor controlling the specific impact strength. The deformation of cells at the crack tip, as a result of bending and/or buckling of cell walls, can increase the failure strain, which leads to an increase in failure energy. In expanded polymers, the majority of the absorbed energy during impact loading is dissipated as plastic work. The transition of plane stress conditions to plane strain conditions, due to expansion, can be considered as another source of toughening in EPS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1421–1426, 2003     

Long-chain derivatives with a hexahydrothioxotetrazine moiety as potential antimicrobial agents

A series of hexahydrothioxotetrazine-containing compounds I–IV were evaluated for their antimicrobial activity. Fungi (Aspergillus sydowii, A. nidulari, A. terreus, Fusarium solanum, Trichoderma viridae, T. lignorum, Rhizopus arrhitus andCandida albicans) and bacteria (Escherichia coli, Salmonella sp.,Pseudomonas aeruginosa, bacillus sp.,Staphylococcus aureus, Klebsella sp.,Shigella sp. andStreptococcus faecalis) were used for this examination. Compounds I–III showed 90% growth inhibition against a large number of fungi. Two compounds (II and III) have shown significant antibacterial activity. The most striking feature of this study is that compound II, which does not carry an ester function, is the most potent antifungal and antibacterial agent. In general, these promising compounds may be of commercial significance in the future and therefore need developmental studies.     

Panic disorder: effective treatment options

Panic disorder is a distressing and debilitating condition with a familial tendency; it may be associated with situational (agoraphobic) avoidance. The diagnosis of panic disorder requires recurrent, unexpected panic attacks and at least one of the following characteristics: persistent concern about having an additional attack (anticipatory anxiety); worry about the implications of an attack or its consequences (e.g., a catastrophic medical or mental consequence) and making a significant change in behavior as a consequence of the attacks. A variety of pharmacologic interventions is available, as are non-pharmacologic cognitive or cognitive-behavioral therapies that have demonstrated safety and efficacy in the treatment of panic disorder. Early detection and thoughtful selection of appropriate first-line interventions can help these patients, who often have been impaired for years, regain their confidence and ability to function in society.     

Sensitivity and specificity of a short questionnaire for food insecurity surveillance in Iran

BACKGROUND: Food insecurity is frequent in both developed and developing countries, affecting from 5% to 25% of the general population. It has considerable health impacts on the physical, social, and psychological status of individuals in communities suffering from food insecurity. OBJECTIVE: The aim of this study was to document the epidemiologic features of food insecurity in the northwest region of Iran and to evaluate the sensitivity and specificity of a short-form (six items) questionnaire for screening of food insecurity in the region. METHODS: This cross-sectional study was conducted on 300 subjects (132 male and 168 female) selected randomly in the Asadabadi area of the northwest of Iran. Information on food consumption was obtained by a 24-hour food-recall questionnaire for 3 days in a week. This information was compared with the data from the Household Food Security Scale (six-item short questionnaire) to assess the applicability of this short scale for the surveillance of food insecurity. Hunger was defined as inadequate intake of energy. Hidden hunger was defined as adequate intake of energy and inadequate intake of one (or more) of four key nutrients (protein, calcium, vitamin A, and vitamin B2). RESULTS: The prevalence of hunger and hidden hunger in the area according to the 24-hour food-recall questionnaire was 26% and 42%, respectively. Only 32% of the study population was secure in terms of having access to all key nutrients. The sensitivity, specificity, and accuracy of the short questionnaire for screening for hunger in the population were 98.7%, 85.5%, and 89%, respectively; and the corresponding values for hidden hunger were 23.5%, 96.9%, and 56.3%. CONCLUSIONS: Our findings indicate that food insecurity is prevalent in the northwest of Iran. The short questionnaire (six items) may be used as a simple, low-cost, rapid, and useful tool for the screening of food insecurity and energy intake in similar areas.     

Free transverse vibrations of cracked nanobeams with surface effects

The flexural vibrations of cracked micro- and nanobeams in the presence of surface effects are studied. The cracked-beam model is set up by dividing the classical cracked beam element into two segments connected by a rotational spring located at the cracked section. This model promotes a discontinuity in bending slope, which is proportional to the second derivative of the displacements. Numerical examples demonstrate the effects of beam length, and crack position and severity on the calculated values of natural frequencies of an anodic alumina nanowire in the presence of surface effects. Limiting cases are considered and good agreements with the data available in the literature are obtained.     

Single and multilayer metamaterials fabricated by nanoimprint lithography

We demonstrate for the first time a fast and easy nanoimprint lithography (NIL) based stacking process of negative index structures like fishnet and Swiss-cross metamaterials. The process takes a few seconds, is cheap and produces three-dimensional (3D) negative index materials (NIMs) on a large area which is suitable for mass production. It can be performed on all common substrates even on flexible plastic foils. This work is therefore an important step toward novel and breakthrough applications of NIMs such as cloaking devices, perfect lenses and magnification of objects using NIM prisms. The optical properties of the fabricated samples were measured by means of transmission and reflection spectroscopy. From the measured data we retrieved the effective refractive index which is shown to be negative for a wavelength around 1.8 μm for the fishnet metamaterial while the Swiss-cross metamaterial samples show a distinct resonance at wavelength around 1.4 μm.     

A novel approach to develop the control of Telbot using ANFIS for nuclear hotcells

This paper develops an improved controller for Telbot. Telbot is a new 6 DOF tele-robot, with special kinematic design, famous for working in nuclear hotcells. The recent controllers are based on simple and improved PID controllers, with visible tracking error. In this project, an ANFIS controller was designed and trained for controlling this tele-robot. The proposed controller generates an appropriate torque for reaching desired state, without any error. The controller was initialized with if-then rules. The training includes online and offline processes. The offline processes have light loads, and prepaid more than 90% of system desired, but the online processes do the last critical 10%, and remove all the errors. The controller is describing the high degree of nonlinear dynamics behavior of the Telbot. The final simulation shows the error-less tracking.