Thermionic emission properties and the work function determination of arrays of conical carbon nanotubes

2013 ◽  
Vol 34 ◽  
pp. 1-8 ◽  
Author(s):  
Andriy Sherehiy ◽  
Santoshrupa Dumpala ◽  
Abdelilah Safir ◽  
David Mudd ◽  
Ivan Arnold ◽  
...  
Author(s):  
Chris Evans ◽  
Brian Landi ◽  
Ryne Raffaelle ◽  
Isay Krainsky ◽  
Sheila Bailey ◽  
...  

2015 ◽  
Vol 161 ◽  
pp. 534-537 ◽  
Author(s):  
Nadim A. Davletkildeev ◽  
Denis V. Stetsko ◽  
Valery V. Bolotov ◽  
Yury A. Stenkin ◽  
Petr M. Korusenko ◽  
...  

2020 ◽  
Vol 20 (10) ◽  
pp. 6463-6468 ◽  
Author(s):  
Mohammad M. H. Raza ◽  
Sunny Khan ◽  
Mohd Sadiq ◽  
Mohammad Zulfequar ◽  
Mushahid Husain ◽  
...  

In the present report, the properties of the field emission devices of carbon nanotubes (CNTs) were remarkably improved by decorating their surface with magnesium oxide nanoparticles (MgO NPs). The MgO NPs were attached effectively on the surface of CNTs via thermal evaporation. The Raman spectra confirm the graphitic order of as-grown pristine CNTs with RBM (radial breathing mode), D band and G band peaks at the 282 cm−1, 1347 cm−1 and 1594 cm−1 respectively. The peak at 471 cm−1 indicates successful attachment of MgO NPs to the CNTs. The enhanced field emission properties of CNTs were mainly attributed to the MgO NPs which increased the field enhancement factor and the density of emission sites. The decreased work function and increased field enhancement factor were responsible for the improved FE properties of the CNTs. Our results indicate that the MgO decorated CNTs can be used as an effective field emitter for various electron emission devices. The turn-on field decrease from 1.6 V/μm to 1.3 V/μm and the maximum current density increases from 1.581 to 3.678 mA/cm2 after the decoration of CNTs with MgO NPs. The value of field enhancement factor (β) also increases from 2.814×103 to 9.823×103.


2019 ◽  
Vol 20 (5) ◽  
pp. 390-400 ◽  
Author(s):  
Nabil N. AL-Hashimi ◽  
Amjad H. El-Sheikh ◽  
Rania F. Qawariq ◽  
Majed H. Shtaiwi ◽  
Rowan AlEjielat

Background: The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies. Methods: In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC–DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution. Results: The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods. Conclusion: The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.


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