Tuning the electronic properties of boron nitride nanotube by mechanical uni-axial deformation: a DFT study

The effect of uni-axial strain on the electronic properties of (8,0) zigzag and (5,5) armchair boron nitride nanotubes (BNNT) is addressed by density functional theory calculation. The stress-strain profiles indicate that these two BNNTS of differing types display very similar mechanical properties, but there are variations in HOMO-LUMO gaps at different strains, indicating that the electronic properties of BNNTs not only depend on uni-axial strain, but on BNNT type. The variations in nanotube geometries, partial density of states of B and N atoms, B and N charges are also discussed for (8,0) and (5,5) BNNTs at different strains

Applications of multi-walled carbon nanotube in electronic packaging

Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work

How French general practitioners manage and prevent recurrent respiratory tract infections in children: the SOURIRRE survey

Bruno Chicoulaa,1 Hervé Haas,2 Jérôme Viala,3 Maryline Salvetat,4 Jean-Pierre Olives,5 1Faculty of Medicine, Toulouse Rangueil, Toulouse, 2Paediatric Emergency and Infectious Disease Departments, Lenval University Hospital, Nice, 3Gastroenterology Department, Robert-Debré Hospital, Paris, 4Sports and General Medicine Practice, Labruguière, 5Gastroenterology and Nutrition Department, Children’s Hospital, University Hospital, Toulouse, France Background: Recurrent respiratory tract infections (RRTIs) are the most common reason for children’s visits to primary care physicians in France; however, little is known about general practitioners’ (GPs) opinions and expectations concerning the management and prevention of these common and recurrent pathologies. Purpose: To describe French GPs’ daily practice in the management of respiratory infections and the prevention of their recurrence in children. Methods: A sample group of French GPs answered a structured questionnaire on risk factors, RRTI management, antibiotic use and prevention measures. Results: A total of 358 GPs participated in the survey. Rhinopharyngitis, the most frequent respiratory infection, was considered to be recurrent if six or more episodes occurred in a year. Four risk factors were acknowledged as substantial: living in communities, passive smoking, pollution and allergies. Around 63% of GPs said that RRTIs are too often treated with antibiotics. More than 85% thought that prevention of RRTIs is possible. Smoking cessation, vaccination, allergen avoidance and hygiene were identified as the main preventive measures. A large majority of GPs (84%) prescribed products for prevention and ~90% would prescribe a product stimulating immunity if the efficacy and tolerability of these agents was proven and confirmed in their daily practice. Conclusions: French GPs are well aware of the health and socioeconomic burdens resulting from RRTIs, as well as the risk of antibiotic overuse. They have a prevention-oriented approach, implement preventive measures when possible and prescribe products for prevention. Keywords: disease management, epidemiology, general practice, immunity, therapeutic

Crossovers in the out-of-plane resistivity of superconducting Tl2Ba2CaCu2O8 single crystals

We report the in-plane (rho (ab)) and out-of-plane (rho (c)) resistivities in the 4-800 K range on single crystals of Tl2Ba2CaCu2O8 high-T-c cuprate with T-c = 111 K (rho (c)/rho (ab) approximate to 1000). rho (ab)(T) exhibits "usual" linear behavior and rho (c)(T) follows generally metallic-like, positive slope in the 150-400 K temperature range. There is a clear crossover to semiconductor-like behavior close to T-c. However, for the first time in a chainless high-T-c cuprate we observe a crossover above 500 K due to hopping conduction. Under high pressures ((c) strongly decreases, yet the rho (c)(T) slope does riot change. This suggests that the out-of-plane charge transport is governed by the interplane tunneling rate