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Much progress has been made in the nanoscale analysis of nanostructures, while the mapping of key charge transport properties such as a carrier mobility remains a challenge, especially for one-dimensional systems. Here, we report the nanoscale mapping of carrier mobilities in carbon nanotube (CNT) networks and show that charge transport behaviors varied depending on network structures. In this work, the spatial distribution of localized charge transport properties such as mobilities and charge trap densities in CNT networks were mapped via a scanning noise microscopy. The mobility map was obtained from the conductivity maps measured at different back-gate biases, showing up to two orders of mobility variations depending on localized network structures. Furthermore, from the maps, correlations between mobility/conductivity and charge trap density were analyzed to determine charge transport mechanisms. In metallic CNT networks, the regions with rather

We developed a reusable surface-amplified nanobiosensor for monitoring airborne viruses with a sub-PFU/mL level detection limit. Here, sandwich structures consisted of magnetic particles functionalized with antibodies, target viruses, and alkaline phosphatases (ALPs) were formed, and they were magnetically concentrated on Ni patterns near an electrochemical sensor transducer. Then, the electrical signals from electrochemical markers generated by ALPs were measured with the sensor transducer, enabling highly-sensitive virus detection. The sandwich structures in the used sensor chip could be removed by applying an external magnetic field, and we could reuse the sensor transducer chip. As a proof of concepts, the repeated detection of airborne influenza virus using a single sensor chip was demonstrated with a detection limit down to a sub-PFU/mL level. Using a single reusable sensor transducer chip, the hemagglutinin (HA) of influenza A (H1N1) virus with different concentrations were measured down to 10 aM level. Importantly, our sensor chip exhibited reliable sensing signals even after more than 18 times of the repeated HA sensing measurements. Furthermore, airborne influenza viruses collected from the air could be measured down to 0.01 PFU/mL level. Interestingly, the detailed quantitative analysis of the measurement results revealed the degradation of HA proteins on the viruses after the air exposure. Considering the ultrasensitivity and reusability of our sensors, it can provide a powerful tool to help preventing epidemics by airborne pathogens in the future.

We report the mapping of the nanoscale effects of charge trap activities in the grain structures of an oxygen plasma-treated indium tin oxide (ITO) thin film. Here, a conducting Pt probe made direct contact with the surface of an ITO thin film and scanned the surface while measuring the maps of electrical currents and noises. The measured data were analyzed to obtain the maps of sheet conductance (Gs) and charge trap density (Neff) in the grain structures of the ITO thin film. The results showed that grain boundaries exhibited a lower sheet conductance and a higher charge trap density than those of the regions inside grains. Interestingly, the scaling behavior of Gs ∝ Neff−0.5 was observed in both grain and boundary regions, indicating diffusive charge transport. Furthermore, the sheet conductance increased by two times, and the density of charge traps decreased by ∼70% after an oxygen plasma treatment, presumably due to the enhanced crystallinity of the ITO film. Interestingly, in some boundary regions, the sheet conductance and the charge trap density exhibited the scaling behavior of Gs ∝ Neff0.5, which was attributed to the hopping conduction caused by the enhanced crystallinity and increased localized states in the boundary regions. Since our method provides valuable insights into charge transport and charge trap activities in transparent conducting thin films, it can be a powerful tool for basic research and practical optoelectronic device applications based on ITO thin films., Mapping of noise source density dependence on oxygen plasma treatment in the grains of an ITO thin film.

Homomorphic authenticated encryption allows implicit computation on plaintexts using corresponding ciphertexts without losing privacy, and provides authenticity of the computation and the resultant plaintext of the computation when performing a decryption. However, due to its special functionality, the security notions of the homomorphic authenticated encryption is somewhat complicated and the construction of fully homomorphic authenticated encryption has never been given. In this work, we propose a new security notion and the first construction of fully homomorphic authenticated encryption. Our new security notion is a unified definition for data privacy and authenticity of homomorphic authenticated encryption. Moreover, our security notion is simpler and stronger than the previous ones. To realize our new security notion, we also suggest a construction of fully homomorphic authenticated encryption via generic construction. We combine a fully homomorphic encryption and two homomorphic authenticators, one fully homomorphic and one OR-homomorphic, to construct a fully homomorphic authenticated encryption that satisfies our security notion. Our construction requires its fully homomorphic encryption to be indistinguishable under chosen plaintext attacks and its homomorphic authenticators to be unforgeable under selectively chosen plaintext queries. Our construction also supports multiple datasets and amortized efficiency. For efficiency, we also construct a multi-dataset fully homomorphic authenticator scheme, which is a variant of the first fully homomorphic signature scheme. Our multi-dataset fully homomorphic authenticator scheme satisfies the security requirement of our generic construction above and supports amortized efficiency.

We developed a reusable surface-amplified nanobiosensor for monitoring airborne viruses with a sub-PFU/mL level detection limit. Here, sandwich structures consisted of magnetic particles functionalized with antibodies, target viruses, and alkaline phosphatases (ALPs) were formed, and they were magnetically concentrated on Ni patterns near an electrochemical sensor transducer. Then, the electrical signals from electrochemical markers generated by ALPs were measured with the sensor transducer, enabling highly-sensitive virus detection. The sandwich structures in the used sensor chip could be removed by applying an external magnetic field, and we could reuse the sensor transducer chip. As a proof of concepts, the repeated detection of airborne influenza virus using a single sensor chip was demonstrated with a detection limit down to a sub-PFU/mL level. Using a single reusable sensor transducer chip, the hemagglutinin (HA) of influenza A (H1N1) virus with different concentrations were measured down to 10 aM level. Importantly, our sensor chip exhibited reliable sensing signals even after more than 18 times of the repeated HA sensing measurements. Furthermore, airborne influenza viruses collected from the air could be measured down to 0.01 PFU/mL level. Interestingly, the detailed quantitative analysis of the measurement results revealed the degradation of HA proteins on the viruses after the air exposure. Considering the ultrasensitivity and reusability of our sensors, it can provide a powerful tool to help preventing epidemics by airborne pathogens in the future.

We mapped the nanoscale reduction of resistivity and noise source activities induced by metallic single walled carbon nanotubes (m-SWCNTs) embedded in gold thin films. In this method, current and noise maps of m-SWCNTs/gold hybrid thin films were recorded using a conducting probe in contact with the surface, and the maps were utilized to estimate the nanoscale variation of resistivity (ρ) and the density distribution of noise sources (Neff) generating electrical noises in the hybrid thin film. The m-SWCNTs/gold hybrid thin films with a 5 nm thick gold layer exhibited 300% improved conductivity compared to that of pristine gold thin films. Additionally, the regions with embedded m-SWCNTs showed significantly reduced noise source densities compared with pristine gold film regions. These results clearly show that embedded m-SWCNTs improve the conductivity and reduce electrical noises of metallic electrodes. Interestingly, we observed that the ρ and the Neff on both m-SWCNTs/gold hybrid and pristine gold regions exhibited a scaling behavior of ρ ∝ Neff0.5, implying the hopping charge conduction and noise characteristics of m-SWCNTs/gold hybrid films. Our works can be a useful guideline for the development of high performance electrodes based on CNTs.

Objectives The aim of this study was to evaluate the effect of ticagrelor versus clopidogrel on left ventricular (LV) remodeling after reperfusion of ST-segment elevation myocardial infarction (STEMI) in humans. Background Animal studies have demonstrated that ticagrelor compared with clopidogrel better protects myocardium against reperfusion injury and improves remodeling after myocardial infarction. Methods In this investigator-initiated, randomized, open-label, assessor-blinded trial performed at 10 centers in Korea, patients were enrolled if they had naive STEMI successfully treated with primary percutaneous coronary intervention (PCI) and at least 6-month planned duration of dual-antiplatelet treatment. The coprimary endpoints were LV remodeling index (LVRI) (a relative change of LV end-diastolic volume) measured on 3-dimensional echocardiography and N-terminal pro–B-type natriuretic peptide level at 6 months. Results Among initially enrolled patients with STEMI (n = 336), 139 in each group completed the study. LVRI at 6 months was numerically lower with ticagrelor versus clopidogrel (0.6 ± 18.6% vs. 4.5 ± 16.5%; p = 0.095). Ticagrelor significantly reduced the 6-month level of N-terminal pro–B-type natriuretic peptide (173 ± 141 pg/ml vs. 289 ± 585 pg/ml; p = 0.028). These differences were prominent in patients with pre-PCI TIMI (Thrombolysis In Myocardial Infarction) flow grade 0. By multivariate analysis, ticagrelor versus clopidogrel reduced the risk for positive LV remodeling (LVRI >0%) (odds ratio: 0.56; 95% confidence interval: 0.33 to 0.95; p = 0.030). The LV end-diastolic volume index remained unchanged during ticagrelor treatment (from 54.7 ± 12.2 to 54.2 ± 12.2 ml/m2; p = 0.629), but this value increased over time during clopidogrel treatment (from 54.6 ± 11.3 to 56.4 ± 13.9 ml/m2; p = 0.056) (difference −2.3 ml/m2; 95% confidence interval: −4.8 to 0.2 ml/m2; p = 0.073). Ticagrelor reduced LV end-systolic volume index (from 27.0 ± 8.5 to 24.7 ± 8.4 ml/m2; p Conclusions Ticagrelor was superior to clopidogrel for LV remodeling after reperfusion of STEMI with primary PCI. (High Platelet Inhibition With Ticagrelor to Improve Left Ventricular Remodeling in Patients With ST Segment Elevation Myocardial Infarction [HEALING-AMI]; NCT02224534 )

A method is developed to directly map nanoscale "noise-source switching" phenomena during the optoelectronic switching of phase-separated polymer nanocomposites of tetrathiafulvalene (TTF) and phenyl-C61 -butyric acid methyl ester (PCBM) molecules dispersed in a polystyrene (PS) matrix. In the method, electrical current and noise maps of the nanocomposite film are recorded using a conducting nanoprobe, enabling the mapping of a conductivity and a noise-source density. The results provide evidence for a repeated modulation in noise sources, a "noise-source switching," in each stage of a switching cycle. Interestingly, when the nanocomposite is "set" by a high bias, insulating PS-rich phases shows a drastic decrease in a noise-source density which becomes lower than that of conducting TTF-PCBM-rich phases. This can be attributed to a trap filling by charge carriers generated from a TTF (donor)-PCBM (acceptor) complex. In addition, when the film is exposed to UV, an optical switching occurs due to chemical reactions which lead to irreversible changes on the noise-source density and conductivity. The method provides a new insight on noise-source activities during the optoelectronic switching of polymer nanocomposites and thus can be a powerful tool for basic noise research and applications in organic memory devices.

Cadaverine (CV), a death-associated odor, is an important target molecule for various sensor applications, including the evaluation of food spoilage. In this study, we developed an oriented nanodisc (ND)-functionalized bioelectronic nose (ONBN), based on carbon nanotube transistors and nanodiscs embedded with an olfactory receptor produced in Escherichia coli (E. coli) for detection of CV. To fabricate ONBN devices, a trace-amine-associated receptor 13c (TAAR13c) binding to CV was produced in E. coli, purified, reconstituted into NDs, and assembled, in the desired orientation, onto a carbon- nanotube-based field-effect transistor with floating electrodes. The ONBN showed high performance in terms of sensitivity and selectivity. Moreover, the ONBN was used to measure CV in diverse real-food samples for the determination of food freshness. These results indicate ONBN devices can be utilized to evaluate the quality of food samples quantitatively, which should enable versatile practical applications such as food safety and preservative development. Moreover, the ONBN could provide a useful tool for detection of corpses, which could be practically used in disaster responses.

An electrical noise is one of the key parameters determining the performance of modern electronic devices. However, it has been extremely difficult, if not impossible, to image localized noise sources or their activities in such devices. We report a “noise spectral imaging” strategy to map the activities of localized noise sources in graphene domains. Using this method, we could quantitatively estimate sheet resistances and noise source densities inside graphene domains, on domain boundaries and on the edge of graphene. The results show high activities of noise sources and large sheet resistance values at the domain boundary and edge of graphene. Additionally, we showed that the top layer in double-layer graphene had lower noises than single-layer graphene. This work provides valuable insights about the electrical noises of graphene. Furthermore, the capability to directly map noise sources in electronic channels can be a major breakthrough in electrical noise research in general.

We report a successful development of a floating electrode-based DNA sensor with controllable responses. Here, metallic floating electrodes were fabricated to form Schottky barriers between carbon nanotubes and the floating electrodes. We showed that the sensor response could be enhanced by increasing the number of floating electrodes. We also analyzed the response of the sensors based on the Langmuir isotherm theory.

The aim of this study was to explore the effect of one stenosis in a daughter artery on the fractional flow reserve (FFR) of another stenosis parallels in side branch.The impact of one stenosis on the FFR of another parallel stenosis has not been evaluated.The proximal segments of the left anterior descending (LAD) and left circumflex (LCX) arteries were exposed and encircled with a Teflon pledget complex in seven swine (55-70 kg). Five degrees of stenosis (to approximate angiographic diameter stenoses of 0%, 25%, 50%, 75%, and 100%) were made by tightening the pledgets. FFR was evaluated simultaneously in the LAD and the LCX with two pressure wires in each coronary artery. A mixed-effects linear model was used to evaluate the association between the FFR values.A total of 115 paired FFR values were obtained. The FFR of the LAD and LCX were not significantly associated with each other (F = 0.237 and P = 0.627 for the LCX FFR to predict the LAD FFR; F = 0.541 and P = 0.463 for the LAD FFR to predict the LCX FFR).The individual FFR values of each parallel stenosis in the LAD and the LCX were not significantly influenced by each other. This relationship was independent of the mean aortic pressure and heart rate. © 2016 Wiley Periodicals, Inc.

We report the large-scale fabrication of high-performance field effect transistors (FETs) based on pristine semiconducting single-walled carbon nanotube (s-SWCNT) networks without bundles or organic impurities, thus exhibiting its intrinsic characteristics. Here, the solution of pristine s-SWCNTs without bundles or organic impurities was prepared in nonpolar solvent via filtration and centrifugation processes, and the s-SWCNTs in the solution were selectively assembled onto specific regions on the solid substrates via a directed assembly strategy. The fabricated FET devices based on such pristine s-SWCNT networks could exhibit a rather large on–off ratio up to over ∼106 and a subthreshold swing as small as ∼490 mV/dec, which are comparable to those of a single s-SWCNT-based device with the same device structure. Importantly, the s-SWCNT devices exhibited anomalous gating behaviors such as an on-current saturation at a large gate bias and unconventional scaling behaviors, which are quite different from tho...

In the present study, nanoscale wavelength-selective photovoltaic activities in H- and J-aggregates of azo dye-based solar cell films were mapped by wavelength-dependent photoconductive noise microscopy. In this strategy, the local conductivities and charge traps in dye films were mapped by a conducting probe scanning the surface while illuminating the lights with selected wavelengths. We observed the formation of localized domains exhibiting wavelength-dependent photoconductivities. The individual domains could be identified as H- and J-aggregates, which showed dominant photoexcitations at wavelengths of 600 and 450 nm, respectively. Notably, the short-circuit currents Isc and photoconductivities ΔσPC of the film showed power-law dependencies with trap densities under illuminated conditions (NT_L) and the trap density change by the illumination (ΔNT), respectively, like ΔσPC ∝ |ΔNT|1/2 and Isc ∝ NT_L−3/4 for each wavelength illumination. These results revealed the carrier recombination process in cooperation with the traps which could be a major factor determining the performance of solar cells. Significantly, the J-aggregates showed lower trap densities than those of the H-aggregates, resulting in superior solar cell characteristics of the J-aggregates, such as a higher Isc and larger open circuit voltages. Since our method allows mapping the nanoscale photovoltaic activities of solar cell film aggregates, it can be a powerful tool for both basic research and in the application of photoelectronic devices.

We report a colorimetric dye-functionalized sol-gel matrix on carbon nanotubes for use as a refreshable and flexible gas sensor with humidity calibration. Here, we fabricated gas sensors by functionalizing dye molecules on the top of carbon nanotube networks via a sol-gel method. Using hybrid gas sensors with different dye molecules, we could selectively detect various hazardous gases, such as NH3, Cl2 and SO2 gases, via optical and electrical signals. The sensors exhibited rather large conductance changes of more than 50% following exposure to gas species with concentrations even under the permissible exposure limit. Significantly, we could refresh used gas sensors by simply exposing them to fresh N2 gas without any heat treatment. Additionally, our sensors can be bent to form versatile practical sensor devices, such as tube-shape sensors for ventilation tubes. This work shows a simple but powerful method for building refreshable and selective gas sensors for versatile industrial and academic applications.

International audience; Semiconducting single-walled carbon nanotube-Au (sSWCNT-Au) hybrid films are prepared to build a thermistor device with an adjustable temperature coefficient and show that the embedded sSWCNTs reduce the resistivity and noise source activities in the nanoscale regions of the film. The temperature coefficient of the hybrid films can be adjusted from negative to positive values simply by increasing the deposited Au thickness. Moreover, scanning noise microscopy is utilized to map the nanoscale variation of the resistivity and noise source density on the sSWCNT-Au hybrid films. Interestingly, the map shows that the regions with both sSWCNT and Au exhibit three times lower resistivity and 18 times smaller noise source activities than pristine Au regions, indicating that sSWCNTs embedded in metallic films can significantly reduce the resistivity and electrical noise source activities in the film.