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Gas sensors

Zhouping Yin, Xiaomei Wang, Fazhe Sun, Xiaohu Tong, Chen Zhu, Qiying Lv, Dong Ye, Shuai Wang, Wei Luo, YongAn Huang
Gas sensing performance can be improved significantly by the increase in both the effective gas exposure area and the surface reactivitiy of ZnO nanorods. Here, we propose aligned hierarchical Ag/ZnO nano-heterostructure arrays (h-Ag/ZnO-NAs) via electrohydrodynamic nanowire template, together with a subsequent hydrothermal synthesis and photoreduction reaction. The h-Ag/ZnO-NAs scatter at top for higher specific surface areas with the air, simultaneously contact at root for the electrical conduction. Besides, the ZnO nanorods are uniformly coated with dispersed Ag nanoparticles, resulting in a tremendous enhancement of the surface reactivity...
September 22, 2017: Scientific Reports
A S Ilin, M I Ikim, P A Forsh, T V Belysheva, M N Martyshov, P K Kashkarov, L I Trakhtenberg
The possibility of reducing the operating temperature of H2 gas sensor based on ZnO-In2O3 down to room temperature under green illumination is shown. It is found that sensitivity of ZnO-In2O3 composite to H2 nonmonotonically depends on the oxides' content. The optimal ratio between the components is chosen. The new mechanism of nanocrystalline ZnO-In2O3 sensor sensitivity to H2 under illumination by green light is proposed. The mechanism considers the illumination turns the composite into nonequilibrium state and the photoconductivity change in the H2 atmosphere is linked with alteration of nonequilibrium charge carriers recombination rate...
September 22, 2017: Scientific Reports
Samuel M Yimenu, J Y Kim, B S Kim
The aim of the present study was to investigate the potential of a fast gas chromatography (GC) e-nose for freshness discrimination and for prediction of storage time as well as sensory and internal quality changes during storage of hen eggs. All samples were obtained from the same egg production farm and stored at 20 °C for 20 d. Egg sampling was conducted every 0, 3, 6, 9, 12, 16, and 20 d. During each sampling time, 4 egg cartons (each containing 10 eggs) were randomly selected: one carton for Haugh units, one carton for sensory evaluation and 2 cartons for the e-nose experiment...
October 1, 2017: Poultry Science
Yan Wang, Jianliang Cao, Cong Qin, Bo Zhang, Guang Sun, Zhanying Zhang
Flower-like SnO₂/g-C₃N₄ nanocomposites were synthesized via a facile hydrothermal method by using SnCl₄·5H₂O and urea as the precursor. The structure and morphology of the as-synthesized samples were characterized by using the X-ray powder diffraction (XRD), electron microscopy (FESEM and TEM), and Fourier transform infrared spectrometer (FT-IR) techniques. SnO₂ displays the unique 3D flower-like microstructure assembled with many uniform nanorods with the lengths and diameters of about 400-600 nm and 50-100 nm, respectively...
September 22, 2017: Nanomaterials
Qian Rong, Yumin Zhang, Chao Wang, Zhongqi Zhu, Jin Zhang, Qingju Liu
Ag-LaFeO3 molecularly imprinted polymers (ALMIPs) were fabricated, which provided special recognition sites to methanol. Then ALMIPs fiber 1, fiber 2 and fiber 3 were prepared using filter paper, silk and carbon fibers template, respectively. Based on the observation of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Nitrogen adsorption surface area analyzer (BET), the structure, morphology and surface area of the fibers were characterized. The ALMIPs fibers (fiber 1, fiber 2 and fiber 3) show excellent selectivity and good response to methanol...
September 21, 2017: Scientific Reports
Tatsuya Iwata, Kyosuke Matsuda, Kazuhiro Takahashi, Kazuaki Sawada
Demand for the detection of carbon dioxide (CO 2 ) is increasing in various fields, including air-quality monitoring, healthcare, and agriculture. On the other hand, smart gas sensors, in which micromachined gas sensors are integrated with driving circuits, are desirable toward the development of the society of the internet of things. In this study, micromachined hotplate-based CO 2 sensors were fabricated and their characteristics were investigated. The sensors have La 2 O 3 /SnO 2 stacked layers as a sensing material and Pt interdigitated electrodes...
September 20, 2017: Sensors
Chuanxing Jiang, Dongzhi Zhang, Nailiang Yin, Yao Yao, Talgar Shaymurat, Xiaoyan Zhou
This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag-SnO₂/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag-SnO₂/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag-SnO₂/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO₂ and SnO₂/rGO film sensors...
September 18, 2017: Nanomaterials
Camilla Baratto, Raj Kumar, Elisabetta Comini, Matteo Ferroni, Marco Campanini
We present here heterostructured ZnO-NiO nanowires, constituted by a core of single crystalline ZnO nanowires, covered by poly-crystalline NiO nanorods. The bottle-brush shape was investigated by SEM and TEM, confirming that a columnar growth of NiO occurred over the ZnO core, with a preferred orientation of NiO over ZnO nanowires. The heterostructured devices are proposed for gas sensing application. Bare ZnO nanowires and heterostructured sensors with two different thicknesses of NiO poly-crystalline nanorods were analysed for acetone, ethanol, NO2 and H2 detection...
September 18, 2017: Nanotechnology
Mahdi Ghasemi-Varnamkhasti, Zahra Safari Amiri, Mojtaba Tohidi, Majid Dowlati, Seyed Saeid Mohtasebi, Adenilton C Silva, David D S Fernandes, Mário C U Araujo
Cumin is a plant of the Apiaceae family (umbelliferae) which has been used since ancient times as a medicinal plant and as a spice. The difference in the percentage of aromatic compounds in cumin obtained from different locations has led to differentiation of some species of cumin from other species. The quality and price of cumin vary according to the specie and may be an incentive for the adulteration of high value samples with low quality cultivars. An electronic nose simulates the human olfactory sense by using an array of sensors to distinguish complex smells...
January 1, 2018: Talanta
Aimin Chen, Rui Liu, Xiao Peng, Qiaofen Chen, Jianmin Wu
In order to distinguish NO2 and SO2 gas with one sensor, we designed a paper chip assembled with 2D g-C3N4/rGO stacking hybrid fabricated via layer by layer self-assembled approach. The g-C3N4/rGO hybrid exhibited remarkable photoelectricity property due to the construction of van der Waals heterostructure. For the first time, we have been able to selectively detect NO2 and SO2 gas using "light on and off" strategy. Under "light off" condition, the g-C3N4/rGO sensor exhibited a p-type semiconducting behavior with low detection limit of 100 ppb NO2, but no response towards SO2...
September 14, 2017: ACS Applied Materials & Interfaces
Mohammad Mizanur Rahman, Chalie Charoenlarpnopparut, Prapun Suksompong, Pisanu Toochinda, Attaphongse Taparugssanagorn
Electronic noses (E-Noses) are becoming popular for food and fruit quality assessment due to their robustness and repeated usability without fatigue, unlike human experts. An E-Nose equipped with classification algorithms and having open ended classification boundaries such as the k-nearest neighbor (k-NN), support vector machine (SVM), and multilayer perceptron neural network (MLPNN), are found to suffer from false classification errors of irrelevant odor data. To reduce false classification and misclassification errors, and to improve correct rejection performance; algorithms with a hyperspheric boundary, such as a radial basis function neural network (RBFNN) and generalized regression neural network (GRNN) with a Gaussian activation function in the hidden layer should be used...
September 12, 2017: Sensors
Bian Wu, Xingfei Zhang, Beiju Huang, Yutong Zhao, Chuantong Cheng, Hongda Chen
Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration...
September 9, 2017: Sensors
Dong Liu, Leimiao Lin, Qiaofen Chen, Hongzhi Zhou, Jianmin Wu
Silicon nanowires/TiO2 (SiNWs/TiO2) array with core-shell nanostructure was created by sol-gel and drop-casting methods. The hybrid material displayed excellent sensing performance for CH4 detection at room temperature. The chemiresistor sensor has a linear response towards CH4 gas in 30 ~ 120 ppm range with a detection limit of 20 ppm, which is well below most of CH4 sensors reported before. The enhanced gas sensing performance at room temperature was attributed to the creation of heterojunctions that form a depletion layer at the interface of SiNWs and TiO2 layer...
September 11, 2017: ACS Sensors
Yifeng Wang, Jing Zhou, Xuecheng Guo, Qian Hu, Chaoran Qin, Hui Liu, Meng Dong, Yanjun Chen
In this work, a layer-by-layer (LbL) assembled biopolymer microcapsule with separate layer cavities is generated by a novel and convenient gas-liquid microfluidic approach. This approach exhibits combined advantages of microfluidic approach and LbL assembly method, and it can straightforwardly build LbL-assembled capsules in mild aqueous environments at room temperature. In particular, using this approach we can build the polyelectrolyte multilayer capsule with favorable cavities in each layer, and without the need for organic solvent, emulsifying agent, or sacrificial template...
December 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Jong-Woo Kim, Yoann Porte, Kyung Yong Ko, Hyungjun Kim, Jae-Min Myoung
Micropatternable double-faced (DF) zinc oxide (ZnO) nanoflowers (NFs) for flexible gas sensors have been successfully fabricated on a polyimide (PI) substrate with single-walled carbon nanotubes (SWCNTs) as electrode. The fabricated sensor comprises ZnO nanoshells laid out on a PI substrate at regular intervals, on which ZnO nanorods (NRs) were grown in- and outside the shells to maximize the surface area and form a connected network. This three-dimensional network structure possesses multiple gas diffusion channels and the micropatterned island structure allows the stability of the flexible devices to be enhanced by dispersing the strain into the empty spaces of the substrate...
September 15, 2017: ACS Applied Materials & Interfaces
Tim L Ullrich, Christoph Czernik, Christoph Bührer, Gerd Schmalisch, Hendrik S Fischer
OBJECTIVE: Nasal high-frequency oscillatory ventilation (nHFOV) is a novel mode of non-invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high-frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions. METHODS: NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth...
September 7, 2017: Pediatric Pulmonology
Eric Singh, M Meyyappan, Hari S Nalwa
Wearable electronics is expected to be one of the most active research areas in the next decade, therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, light-weight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons...
September 6, 2017: ACS Applied Materials & Interfaces
Datong Wu, Pengfei Cai, Xiaoyong Zhao, Yong Kong, Yuanjiang Pan
Ionic liquids have been functionalized for modern applications. The functional ionic liquids are also called task-specific ionic liquids. Various task-specific ionic liquids with certain groups have been constructed and exploited widely in the field of separation. To take advantage of their properties in separation science, task-specific ionic liquids are generally used in techniques such as liquid-liquid extraction, solid-phase extraction, gas chromatography, high-performance liquid chromatography and capillary electrophoresis...
September 6, 2017: Journal of Separation Science
Arnoldo Santos, Eva Gomez-Peñalver, M Ignacio Monge-Garcia, Jaime Retamal, João Batista Borges, Gerardo Tusman, Goran Hedenstierna, Anders Larsson, Fernando Suarez-Sipmann
OBJECTIVES: To compare the effects of two lung-protective ventilation strategies on pulmonary vascular mechanics in early acute respiratory distress syndrome. DESIGN: Experimental study. SETTING: University animal research laboratory. SUBJECTS: Twelve pigs (30.8 ± 2.5 kg). INTERVENTIONS: Acute respiratory distress syndrome was induced by repeated lung lavages and injurious mechanical ventilation...
September 1, 2017: Critical Care Medicine
Peter Keil, Gregor Liebsch, Ljudmilla Borisjuk, Hardy Rolletschek
The high-throughput analysis of respiratory activity has become an important component of many biological investigations. Here, a technological platform, denoted the "MultiSense tool," is described. The tool enables the parallel monitoring of respiration in 100 samples over an extended time period, by dynamically tracking the concentrations of oxygen (O2) and/or carbon dioxide (CO2) and/or pH within an airtight vial. Its flexible design supports the quantification of respiration based on either oxygen consumption or carbon dioxide release, thereby allowing for the determination of the physiologically significant respiratory quotient (the ratio between the quantities of CO2 released and the O2 consumed)...
2017: Methods in Molecular Biology
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