The measurement of volatile fatty acids (VFAs) is of great importance in the fields of food and agriculture. There are various methods to measure VFAs, but most methods require specific equipment, making on-site measurements difficult. In this work, we demonstrate the measurements of VFAs in a model sample, silage, through its vapor using an array of nanomechanical sensors—Membrane-type Surface stress Sensors (MSS). Focusing on relatively slow desorption behaviors of VFAs predicted with the sorption kinetics of nanomechanical sensing and the dissociation nature of VFAs, the VFAs can be efficiently measured by using features extracted from the decay curves of the sensing response, resulting in sufficient discrimination of the silage samples. Since the present sensing system does not require expensive, bulky setup and pre-treatment of samples, it has a great potential for practical applications including on-site measurements.
Carbon nanotubes were synthesized by arc discharge in a CF4 gas atmosphere
involving fluorine atoms, which are able to terminate carbon bonding, while no fullerenes
were synthesized in a CF4 gas atmosphere. The morphology of these nanotubes was
investigated by scanning electron microscopy (SEM) and transmission electron
microscopy (TEM). Based on these results, the synthesized conditions in CF4 gas were
compared with those in other gases, i.e., in CH4, H2, He and Ar gases. In addition,
electron spin resonance (ESR) measurements were performed in order to obtain
information about the electronic properties of these nanotubes.
Introduction. Although boron-doped (B-doped) carbon nanotubes and boroncarbonnitrogen (B±C±N) nanotubes have been synthesized [1,2], there are not known investigations of the electronic properties of these nanotubes. In this brief report, we investigate the electronic properties of B-doped carbon nanotubes using electron spin resonance (ESR) and conductance measurements. The morphology of synthesized nanotubes is also investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
From a practical point of view, some measures to reduce the thickness effect backed by a reasonable criterion are required for fabricating structures with heavy section plates. In this study, the thickness effect was investigated by systematic experiments on welded steel joints with thicknesses ranging from 10 to 80 mm. Cruciform joints and T-joints with improved weld by overall profiling or toe-grinding were tested under pulsating tension and under pulsating bending, respectively. These experimental results were analyzed together with the previous results of as-welded joints. As a result, it was concluded that the thickness effect exponents for various conditions may be classified into three categories according to the combination of joint type and loading mode. As-welded joints under bending stress have the steepest thickness effect exponent of −1/3, while as-welded joints under tension with an exponent of −1/5 is milder in thickness effect than that specified in the existing codes. If the weld profile is improved by grinding, the thickness effect becomes much milder to an exponent of −1/10. The as-weld joints with constant-sized attachments also have an exponent of −1/10. Furthermore, thickness effect dependence on fatigue life and thickness effect under random stress were investigated. Based on these results, this study proposes a new evaluation criterion for design purposes.
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