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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - From Nanostructured Piezoelectric Materials to Broadband Transducers for High Resolution Ultrasonic Imaging
摘要： One-dimensional (1D) piezoelectric nanotubes have been fabricated and integrated for producing high frequency nanotube array ultrasonic transducers for high resolution ultrasonic imaging. We find that the nanotube structural feature and the unique nanoconfinement-induced crystal and polarization orientation lead to outstanding piezoelectric material properties and the resulting superior transducer performance. The nanotube array ultrasonic transducers show a broad bandwidth of 126 % (-6 dB) at 108 MHz, with significantly improved sensitivity in comparison with conventional thin film transducers despite the size shrinkage. We further demonstrate high resolution scanning ultrasonic imaging and photoacoustic imaging using the obtained nanotube array transducers, exhibiting great application values.
关键词： piezoelectric nanotubes,high resolution imaging,ultrasonic transducers,photoacoustic imaging
更新于2025-09-04 15:30:14
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Synthesis and Characterization of Carbon Nanotubes by Modified Flame Fragments Deposition Method
摘要： This study focuses on the synthesis of carbon nanotubes from Iraqi natural gas via a modified flame fragments deposition method in presence and absence of the catalyst. Four types of catalysts were used for the growth of carbon nanotubes. These types are iron doped on magnesium oxide (Fe/MgO), iron-cobalt doped on calcium carbonate (Fe-Co/CaCO3) and iron(III) oxide. All these four types were prepared in one batch by a home made instrument.The implemented technique ensures the same experimental conditions such as type of carbon source, type of carrier gas, flow rate of gases, growth temperature and synthesis time of growth for all synthesized samples. Various experimental techniques viz., X-ray diffraction, Raman spectroscopy, scanning electron microscopy and thermogravimetric analysis were used for characterization of the synthesized carbon nanotubes.
关键词： Flame fragments deposition,Natural gas,Carbon nanotubes
更新于2025-09-04 15:30:14
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Quartz Tuning‐Fork Based Carbon Nanotube Transfer into Quantum Device Geometries
摘要： With the objective of integrating single clean, as-grown carbon nanotubes into complex circuits, we have developed a technique to grow nanotubes directly on commercially available quartz tuning forks using a high-temperature chemical vapor deposition process. Multiple straight and aligned nanotubes bridge the >100 mm gap between the two tips. The nanotubes are then lowered onto contact electrodes, electronically characterized in situ, and subsequently cut loose from the tuning fork using a high current. First quantum transport measurements of the resulting devices at cryogenic temperatures display Coulomb blockade characteristics.
关键词： carbon nanotubes,transfer,device fabrication
更新于2025-09-04 15:30:14
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UV light-induced photocatalytic, antimicrobial, and antibiofilm performance of anodic TiO2 nanotube layers prepared on titanium mesh and Ti sputtered on silicon
摘要： The potential use of TiO2 nanotube layers as a self-sterilizing and self-cleaning material for environmental application is presented. Antimicrobial, antibiofilm and photocatalytic performance of anodic TiO2 nanotube layers under UV irradiation was investigated on titanium mesh and on Ti sputtered on silicon substrates. The nanotubes were prepared in fluoride containing ethylene glycol-based electrolyte to obtain ~ 4 μm thick nanotube layers, which were subsequently annealed at 450 °C. Structural and morphological properties of prepared TiO2 layers were characterized using X-ray diffraction, scanning electron microscopy and atomic force microscopy. In addition, their surface wettability, before and after UV irradiation, was investigated. Their photoactivity was compared to TiO2 sol–gel films of similar thickness. The highest efficiency in photocatalytic degradation of organic dye and removal of free-floating bacteria of Gram-positive Staphylococcus epidermidis was observed for TiO2 nanotube layers on titanium mesh. The highest antibiofilm performance in impairments of biofilms was reached using the TiO2 nanotubes on silicon. The obtained results on silicon substrate are promising for the development of medical devices covered by TiO2 nanotubes that would decrease the risk of infection. On the other hand, the mesh substrate covered by TiO2 nanotubes could find environmental applications such as filters in flowing photocatalytic reactors.
关键词： Nanotubes,TiO2,Antibiofilm,Photocatalytic,Antimicrobial
更新于2025-09-04 15:30:14
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Influence of Water Molecules on the Detection of Volatile Organic Compounds (VOC) Cancer Biomarkers by Nanocomposite Quantum Resistive Vapor Sensors vQRS
摘要： The anticipated diagnosis of various fatal diseases from the analysis of volatile organic compounds (VOC) biomarkers of the volatolome is the object of very dynamic research. Nanocomposite-based quantum resistive vapor sensors (vQRS) exhibit strong advantages in the detection of biomarkers, as they can operate at room temperature with low consumption and sub ppm (part per million) sensitivity. However, to meet this application they need to detect some ppm or less amounts of biomarkers in patients' breath, skin, or urine in complex blends of numerous VOC, most of the time hindered by a huge amount of water molecules. Therefore, it is crucial to analyze the effects of moisture on the chemo-resistive sensing behavior of carbon nanotubes based vQRS. We show that in the presence of water molecules, the sensors cannot detect the right amount of VOC molecules present in their environment. These perturbations of the detection mechanism are found to depend on the chemical interactions between water and other VOC molecules, but also on their competitive absorption on sensors receptive sites, located at the nanojunctions of the conductive architecture. This complex phenomenon studied with down to 12.5 ppm of acetone, ethanol, butanone, toluene, and cyclohexane mixed with 100 ppm of water was worth to investigate in the prospect of future developments of devices analysing real breath samples in which water can reach a concentration of 6%.
关键词： conductive polymer nanocomposites,anticipated diagnosis,effects of humidity,VOC,quantum resistive vapor sensors,functionalized carbon nanotubes,biomarkers detection
更新于2025-09-04 15:30:14
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Bipolar Thermoelectric Effects in Semiconducting Carbon Nanotubes: Description in Terms of One-Dimensional Dirac Electrons
摘要： The thermoelectric effects in semiconducting single-walled carbon nanotubes (SWCNTs) are investigated based on the linear response theory combined with the thermal Green’s function method. It is shown that the electronic states near the lowest conduction band minimum and the highest valence band maximum can be effectively described in terms of one-dimensional (1D) Dirac electrons to which a theoretical scheme is developed to describe the thermoelectric responses making it possible to study the effects of inter-band impurity scattering and in-gap states. Using the proposed scheme, the bipolar thermoelectric effects (i.e., the sign inversion of the Seebeck coefficient) in semiconducting SWCNTs observed in recent experiments are explained. Moreover, the temperature dependence of the Seebeck coefficient of semiconducting SWCNTs at low temperature is clarified.
关键词： thermal Green’s function method,Seebeck coefficient,linear response theory,Dirac electrons,semiconducting single-walled carbon nanotubes,thermoelectric effects
更新于2025-09-04 15:30:14
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Photodegradtion of Methyl Orange in the Water on Undoped and Fe-doped TiO2 Nanotubes
摘要： Undoped and Fe-doped TiO2 nanotubes were fabricated by hydrothermally treating the sol-gel-derived undoped and Fe-doped TiO2 nanoparticles in a KOH aqueous solution. The light absorption edge the nanotubes extended to visible light region of ~449 nm at a maximal Fe molar content (3.86 %). Correspondingly, the optical bandgap narrowed to ~2.76 eV. The sunlight-excited degradation rate of methyl orange aqueous solution on the nanotubes increased as increasing Fe-doping content and initial solution pH. The photodegradation followed pseudo-first order reaction kinetics. The pseudo-kinetic rate constant increased from 0.133 to 0.513 h(cid:2)1 as the increase of Fe content and initial pH. A maximal value was achieved at Fe molar content of 3.86 % and initial solution pH=9. The measurement of oxidation-reduction potential revealed a dominant reductive photocatalytic behavior of the nanotubes. The mechanism of enhancing photocatalysis of TiO2 nanotubes by Fe-doping was proposed.
关键词： nanotubes,enviromant decontaimnant,Advanced oxidation,TiO2,photodegradation
更新于2025-09-04 15:30:14
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Highly efficient multifunctional Ag/TiO2 nanotubes/Ti plate coated with MIL-88B(Fe) as a photocatalyst, adsorbent, and disinfectant in water treatment
摘要： Multifunctional MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates were prepared via dip-coating process. Pollutant removals from aqueous solutions were investigated using three different reactions: (1) adsorption of heavy metal ion (Pb2+ and Cd2+), (2) photocatalytic degradation of methyl orange dye (MO), and (3) antibacterial effect for Escherichia coli (E. coli) degradation. Photocatalytic results for dye degradation under UV light irradiation proved the highest activity of the MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates. The degradation rate constant of MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates was approximately four times as that of pure TiO2 nanotubes/Ti under UV irradiation. In addition, this plate showed the effective removal of heavy metal ions by sorption process. The adsorption of Pb2+ and Cd2+on the MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates reached a maximum capacity of 113 and 138 mg/g, and this value was approximately 1.6 times as that of pure TiO2 nanotubes/Ti. In addition, the multifunctional composite plates demonstrated great antibacterial activities towards E. coli. All bacteria colonies killed after 60 min photocatalytic treatment on MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates. The results show the importance of a cooperative effect between the MIL-88B(Fe) metal organic framework (MOF) and Ag/TiO2 nanotubes/Ti plates. The simultaneous removals of these pollutants with the high efficiency showed an facile approach for the polluted water treatment via the newly fabricated MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plate with multiple functions.
关键词： Photocatalyst,Ag/TiO2 nanotubes/Ti,MIL-88B(Fe),Water treatment,Disinfectant,Adsorbent
更新于2025-09-04 15:30:14
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WS2 nanodots-modified TiO2 nanotubes to enhance visible-light photocatalytic activity
摘要： WS2 nanodots-modified TiO2 nanotubes (TNT/WND) composites were fabricated via one-pot hydrothermal method for the first time. The physical and photophysical properties of the as-prepared photocatalysts were characterized by XRD, TEM, HRTEM, BET, UV-vis, and PL. The results demonstrated that WS2 nanodots have been successfully anchored on the inner wall of TiO2 nanotubes. TNT/WND composites showed excellent photocatalytic activity toward photodegradation of rhodamine B (RhB) under visible-light, which mainly attributed to the synergistic effect from relative low recombination rate of the photogenerated electron-hole pairs and high specific surface area.
关键词： Semiconductors,Photocatalysis,WS2 nanodots,Structural,TiO2 nanotubes,Nanocomposites
更新于2025-09-04 15:30:14
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BODIPY with Tuned Amphiphilicity as Fluorogenic Plasma Membrane Probe
摘要： Staining of the plasma membrane (PM) is essential in bio-imaging as it delimits the cell surface and provides various information regarding the cell morphology and status. Herein, the lipophilicity of a green-emitting BODIPY fluorophore was tuned by gradual functionalization with anchors composed of zwitterionic and aliphatic groups, thus yielding three different amphiphilic dyes. We found that BODIPY bearing one or three anchors failed in efficiently staining the PM: derivative with one anchor showed low affinity to PM and exhibited strong fluorescence in water due to high solubility, whereas BODIPY with three anchors aggregated strongly in media and precipitated before binding to PM. In sharp contrast, the BODIPY bearing two anchors (B-2AZ, MemBright-488) formed virtually non-fluorescent soluble aggregates in aqueous medium that quickly de-aggregated in the presence of PM leading to bright soluble molecular form (quantum yield of 0.92). This fluorogenic response allowed for efficient probing of the PM at low concentration (20 nM) with high signal to background ratio images in mono- as well as two-photon excitation microscopy. B-2AZ proved to selectively stain the PM in a more homogeneous manner than the commercially available fluorescently labelled lectin WGA. Finally, it was successfully used in 3D-imaging to reveal fine intercellular tunneling nanotubes in KB cells and to stain the PM in glioblastoma cells in spheroids.
关键词： tunneling nanotubes,two-photon imaging,spheroids,Plasma membrane probe,fluorogenic probe
更新于2025-09-04 15:30:14