scholarly journals Conductive Electrospun Nanofibers for Multifunctional Portable Devices

2021 ◽  
Vol 5 (1) ◽  
pp. 37
Author(s):  
Antonio Fotia ◽  
Patrizia Frontera ◽  
Lucio Bonaccorsi ◽  
Angela Malara
Keyword(s):  
Electrical Properties ◽  
Aqueous Media ◽  
Electrospun Nanofibers ◽  
Single Species ◽  
Electrical Contacts ◽  
Portable Devices ◽  
In Situ Sensing ◽  
Made In

The need to perform in situ sensing measurements lead to the development of innovative and smart field-portable devices. The advantages of such systems are remarkable since they are mainly battery-powered, lightweight and easy to carry and keep. Moreover, field-portable devices are easy to use and are able to give fast sensing responses. In the last few years, many efforts have been made in the development of new performing systems and the advantageous use of nanofibrous materials was assessed. To this purpose, the electrospinning has been recognized as the most powerful and facile technique for generating uniform nanofibers with controlled dimension and morphology. When conductive polymers are electrospun, very interesting electrical properties can be obtained along with the well-known ones that are typical of nanofibers. Among these polymers, polyaniline has been extensively used. In this work, an innovative hybrid material based on polyaniline/polyvinyl acetate/graphene oxide nanofibers was developed and tested as a sensor toward the detection of contaminants in aqueous media. Nanofibers, in the form of a compact mat, were deposited onto a support with suitable electrical contacts. Measurements were performed exploiting the excellent electrical properties of the realized nanofibers in both direct and alternating currents. When a direct current was used, the change in the nanofibers’ resistance value was registered upon exposure to contaminated aqueous solutions and used to determine the presence or absence of contaminants, whereas when tests were performed with an alternating current, the quantitative determination of single species in contaminated solutions was also possible. In this way, by integrating the two different measurement methodologies, an opportunely designed multifunctional portable device will be developed for both qualitative and quantitative contaminants determinations.

Capacitance-voltage characteristics of MIS-structures on the basis of graded-band MBE Hg1−xCdxTe at passivation by epitaxially grown in situ CdTe

2010 ◽  
Vol 18 (3) ◽  
Author(s):  
A.V. Voitsekhovskii ◽  
S.N. Nesmelov ◽  
S.M. Dzyadukh ◽  
V.S. Varavin ◽  
S.A. Dvoretskii ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Molecular Beam ◽  
Surface States ◽  
Electrical Strength ◽  
Mobile Charge ◽  
Protective Layers ◽  
Capacitance Voltage ◽  
Mis Structures

AbstractThe electrical properties of the interface between Hg1−xCdxTe (x = 0.22 and x = 0.32–0.36) and CdTe prepared in situ molecular beam epitaxy were estimated at 77 K. The methods of determination of main parameters of interface semiconductor/insulator and insulator from capacitance-voltage characteristics of MIS-structures based on graded-band Hg1−xCdxTe have been developed. The fixed charge states density, fast surface states density, and density of mobile charge are obtained from capacitance-voltage measurements. For improvement in stable and electrical strength of insulator coating for several samples over CdTe additional protective layers SiO2-Si3N4 are formed for x = 0.22 and ZnTe for x = 0.32–0.36.

scholarly journals Quantification of the least limiting water range in an oxisol using two methodological strategies

2014 ◽  
Vol 38 (6) ◽  
pp. 1772-1783
Author(s):  
Wagner Henrique Moreira ◽  
Cássio Antônio Tormena ◽  
Edner Betioli Junior ◽  
Getulio Coutinho Figueiredo ◽  
Álvaro Pires da Silva ◽  
...  
Keyword(s):  
Soil Water Potential ◽  
Soil Samples ◽  
In Situ Measurements ◽  
Soil Resistance ◽  
Suggested Approach ◽  
Least Limiting Water Range ◽  
Resistance To Penetration ◽  
Made In

The least limiting water range (LLWR) has been used as an indicator of soil physical quality as it represents, in a single parameter, the soil physical properties directly linked to plant growth, with the exception of temperature. The usual procedure for obtaining the LLWR involves determination of the water retention curve (WRC) and the soil resistance to penetration curve (SRC) in soil samples with undisturbed structure in the laboratory. Determination of the WRC and SRC using field measurements (in situ ) is preferable, but requires appropriate instrumentation. The objective of this study was to determine the LLWR from the data collected for determination of WRC and SRC in situ using portable electronic instruments, and to compare those determinations with the ones made in the laboratory. Samples were taken from the 0.0-0.1 m layer of a Latossolo Vermelho distrófico (Oxisol). Two methods were used for quantification of the LLWR: the traditional, with measurements made in soil samples with undisturbed structure; and in situ , with measurements of water content (θ), soil water potential (Ψ), and soil resistance to penetration (SR) through the use of sensors. The in situ measurements of θ, Ψ and SR were taken over a period of four days of soil drying. At the same time, samples with undisturbed structure were collected for determination of bulk density (BD). Due to the limitations of measurement of Ψ by tensiometer, additional determinations of θ were made with a psychrometer (in the laboratory) at the Ψ of -1500 kPa. The results show that it is possible to determine the LLWR by the θ, Ψ and SR measurements using the suggested approach and instrumentation. The quality of fit of the SRC was similar in both strategies. In contrast, the θ and Ψ in situ measurements, associated with those measured with a psychrometer, produced a better WRC description. The estimates of the LLWR were similar in both methodological strategies. The quantification of LLWR in situ can be achieved in 10 % of the time required for the traditional method.

scholarly journals Determination of blood potassium using a fouling-resistant PVDF–HFP-based optode

RSC Advances ◽  
2016 ◽  
Vol 6 (17) ◽  
pp. 14261-14265 ◽  
Author(s):  
Mizuki Tenjimbayashi ◽  
Hirokazu Komatsu ◽  
Masaaki Akamatsu ◽  
Waka Nakanishi ◽  
Koji Suzuki ◽  
...  
Keyword(s):  
Clinical Analysis ◽  
Additional Advantage ◽  
Significant Aspect ◽  
Blood Potassium ◽  
In Situ Sensing

Monitoring potassium levels in blood is a significant aspect of clinical analysis. Here, we report a system for determination of potassium in blood which has the additional advantage of being blood-fouling resistant for safe and easy in situ sensing.

scholarly journals VLBI Observations of Turbulence in the Inner Solar Wind

1996 ◽  
Vol 154 ◽  
pp. 65-75
Author(s):  
Steven R. Spangler
Keyword(s):  
Solar Wind ◽  
Accurate Determination ◽  
The Sun ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Outer Corona ◽  
Very Long Baseline Array ◽  
Made In

AbstractI discuss the use of Very Long Baseline Interferometer (VLBI) phase scintillations to probe the conditions of plasma turbulence in the solar wind. Specific results from 5.0 and 8.4 GHz observations with the Very Long Baseline Array (VLBA) are shown. There are several advantages of phase scintillation measurements. They are sensitive to fluctuations on scales of hundreds to thousands of kilometers, much larger than those probed by IPS intensity scintillations. In addition, with the frequency versatility of the VLBA one can measure turbulence from the outer corona ~ 5 –10 R⊙ to well past the perihelion approach of the Helios spacecraft. This permits tests of the consistency of radio propagation and direct in-situ measurements of turbulence. Such a comparison is made in the present paper. Special attention is dedicated to measuring the dependence of the normalization coefficient of the density power spectrum, on distance from the sun. Our results are consistent with the contention published several years ago by Aaron Roberts, that there is insufficient turbulence close to the sun to account for the heating and acceleration of the solar wind. In addition, an accurate determination of the relationship could aid the detection of transients in the solar wind.

Observation of plant roots in situ

1971 ◽  
Vol 49 (10) ◽  
pp. 1850-1852 ◽  
Author(s):  
J. Waddington
Keyword(s):  
Fiber Optics ◽  
Fiber Bundle ◽  
Small Diameter ◽  
Root Penetration ◽  
Image Transfer ◽  
Transparent Plastic ◽  
Plastic Tube ◽  
Made In

A technique is described which permits the determination of root penetration, distribution, and density with minimal disturbance to the plant. A small diameter tunnel is made in the soil and fitted tightly with a glass or transparent plastic tube. A fiber optics probe is used to observe the arrival of roots at the wall of the tube at various depths and to estimate their distribution and density. The probe consists of a light source and fiber bundle for illumination, a coherent fiber bundle for image transfer to the surface, a right angle viewing attachment at the objective end, and adjustable lenses.

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