aThis paper reports on a new ozone gas sensor based on a-Ag 2 WO 4 nanorod-like structures. Electrical resistance measurements proved the efficiency of a-Ag 2 WO 4 nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 C, demonstrating great potential for a variety of applications.Metal semiconducting oxides have drawn the interest of many researchers due to their wide range of applications, especially as gas sensing materials. 1-5 Among them, one-dimensional (1-D) semiconductor nanostructures have been proposed as very interesting materials, especially as gas sensor devices.6-12 It is well known that several technological applications of nanostructured materials are directly related to the morphology, particle size, crystalline phase and activity of specic crystalline planes strictly dependent on synthesis methods. 4,[13][14][15] In particular, the relationship between morphology and gas sensing properties has been well established. 4,16,17Tungsten-based oxides are an important class of materials that display wide potential functional properties, 18-20 speci-cally the silver tungstate (Ag 2 WO 4 ) compound, which can exhibit three different structures: a-orthorhombic, b-hexagonal, and g-cubic.21-25 Recently, our research group reported a detailed study of the synthesis, structural and optical properties of hexagonal nanorod-like elongated a-Ag 2 WO 4 nanocrystals obtained by different methods. 26-28Ozone (O 3 ) is an oxidizing gas used in many technological applications in different areas, such as the food industry, drinking-water treatment, medicine, microelectronic cleaning processes, and others.29,34-39 For example, ozone has been employed as a powerful drinking-water disinfectant and oxidant. 34,35,40 On the other hand, when the ozone level in an atmosphere exceeds a certain threshold value, the exposure to this gas becomes hazardous to human health and can cause serious health problems (e.g. headache, burning eyes, respiratory irritation and lung damage).34,41 The European Guidelines (2002/3/EG) recommend avoiding exposure to ozone levels above 120 ppb.41 Such arguments support the requirement for the determination and continuous monitoring of ozone levels. 3,29,41Gas sensing properties are evaluated in terms of operating temperature, sensitivity, response time, recovery time and stability.29-33 SnO 2 , In 2 O 3 and WO 3 compounds have been considered the most promising ozone gas sensors. 29-33To the best of our knowledge, to date the gas sensing properties of a-Ag 2 WO 4 nanocrystals have never been evaluated.Here, we report the sensing properties of 1-D a-Ag 2 WO 4 nanorod-like structures obtained by the microwave-assisted hydrothermal (MAH) method.42-46 Because of such properties, nanorods are potential candidates for practical applications as ozone gas sensors.The crystalline phase of the as-obtained a-Ag 2 WO 4 sample was analyzed by X-ray diffraction measurement and all reec-tions were indexed to an orthorhombic struc...

Repeated injections of acidic saline into the gastrocnemius muscle induced both muscle and cutaneous hypersensitivity. We have previously shown that microinjection of local anesthetic into either the rostral ventromedial medulla (RVM) or the nucleus reticularis gigantocellularis (NGC) reverses this muscle and cutaneous hypersensitivity. Although prior studies show that NMDA receptors in the RVM play a clear role in mediating visceral and inflammatory hypersensitivity, the role of NMDA receptors in the NGC, or in non-inflammatory muscle pain is unclear. Therefore, the present study evaluated involvement of the NMDA receptors in the RVM and NGC in muscle and cutaneous hypersensitivity induced by repeated intramuscular injections of acidic saline. Repeated intramuscular injections of acidic saline, 5 days apart, resulted in a bilateral decrease in the withdrawal thresholds of the paw and muscle in all groups 24 h after the second injection. Microinjection of NMDA receptor antagonists into the RVM reversed both the muscle and cutaneous hypersensitivity. However, microinjection of NMDA receptor antagonists into the NGC only reversed cutaneous, but not muscle hypersensitivity. These results suggest that NMDA receptors in the RVM mediate both muscle and cutaneous hypersensitivity, but those in the NGC mediated only cutaneous hypersensitivity after muscle insult.

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The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 m yolk-shelled ZnCo 2 O 4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo 2 O 4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH 3 and NO 2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo 2 O 4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo 2 O 4 microspheres can be further used in other environment monitoring devices.

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