High performance carbon nanotubes thin film transistors by selective ferric chloride doping

Single wall carbon nanotubes (SWNT) have been a significant research topic as active layers for thin film transistors (TFTs) due to their high charge carrier mobility beyond that of crystalline silicon. In this study, we report an effective approach to achieve a very high field-effect mobility and on/off ratio for solution processed semiconducting SWNT TFTs, by selective doping through contact with a thin ferric chloride (FeCl3) dopant layer. The semiconducting layer is formed by a double spin coating of the highly purified (>99%) high pressure carbon mono oxide (HiPCO) SWNT sorted by wrapping of poly (3-dodecylthiophene-2,5-diyl) (P3DDT). In order to achieve effective hole injection from the top Au source electrode without increasing the off-state drain current, less purified (98-99%) SWNTs produced by the plasma discharge process sorted by wrapping of poly (9,9-di-n-dodecylfluorene) (PFDD) are formed on the top of HiPCO film. Significantly improved TFT performance is achieved by the insertion of a few nanometers of a FeCl3 dopant layer at the semiconductor-contact interface. A significant high hole field-effect of 48.35 +/- 3.11 cm(2)V(-1)s(-1) (bare: 6.18 +/- 0.87 cm(2)V(-1)s(-1)) with a reasonable on/off current ratio of 10(5), and low off current of similar to 80 pA, are obtained by controlling the concentration of FeCl3 dopant (thickness = 1.5 nm) at the contact. Mobility is improved further at 2.5 nm thickness of the FeCl3 dopant layer resulting in a hole mobility of 177 +/- 13.2 cm(2) V(-1)s(-1), an on/off ratio of 7.4 x 10(3), and off state current of 1.2 x 10(-9) A

The Flexible PPG sensor using printed photo-devices

1

Dicyanomethylene-quinoid vs. dicyanovinyl-benzenoid organic semiconductors: Understanding structure-property correlations in mesomerism-like forms

Understanding two mesomerism-like forms (quinoid vs. benzenoid structures) over organic semiconductors (OSCs) is essential for achieving high electronic device performance. Herein, we report the synthesis as well as the comparative physicochemical, microstructural, and charge-transporting analysis of dicyanomethylene-quinoid versus dicyanovinyl-benzenoid OSCs based on benzo[1,2-b: 4,5-b'] dithiophene (BDT) units (DCM-Q-BDT and DCV-B-BDT). The electron-deficient nature of the quinoid structure in DCM-Q-BDT can lower the LUMO level and bandgap relative to the benzenoid analogy DCV-B-BDT. Top-gate/bottom-contact (TG/BC) field-effect transistors (OFETs) based on DCM-Q-BDT show not only the maximum electron mobility up to 0.23 cm(2)/V.s without requiring post-annealing treatments, but also demonstrate excellent air stability (half-life times of drain current approximate to 35 h) without any encapsulation. The superior n-channel performance for DCM-Q-BDT is due to the anisotropic orientation, high degree of the crystallinity, and low-lying LUMO induced by the quinoid structure. Our study shows underlying structure-property relationships in quinoid over benzenoid OSCs while demonstrating promise in n-channel OFETs.clos

A new ultrafast 3D gradient echo‐based imaging method using quadratic‐phase encoding

Purpose: To propose a novel 3D ultrafast gradient echo‐based MRI method, dubbed RASE, using quadratic‐phase encoding. Theory and Methods: Several characteristics of RASE, including spin behaviors, spatial resolution, SNR, and reduction of susceptibility‐induced signal loss, were analytically described. A way of compensating for TE variation was suggested in the quadratic phase‐encoding direction. Lemon, in vivo rat and mouse images were demonstrated at 9.4T, including a feasibility study for DCE‐MRI as one of promising applications. Results: RASE was successfully demonstrated by lemon and in vivo rat brain imaging, showing a good robustness to field inhomogeneity. Contribution of the quadratic phase to signal enhancement in a range of magnetic susceptibilities was also evaluated by simulation. Taking a geometric mean of 2 phantom data acquired with opposite gradient polarities effectively compensated for the effect of TE variation. Preliminary DCE‐MRI results were also presented, showing that RASE could more accurately estimate Gd concentration than FLASH. Conclusion: RASE offers a shorter effective TE, having less sensitivity to field inhomogeneity and T2 * effects, much less Nyquist ghosting or chemical‐shift artifacts than gradient echo EPI (GE‐EPI). We highly anticipate that RASE can be an alternative to GE‐EPI in many applications, particularly those requiring high spatial and temporal resolutions in a broad volume coverage.© 2019 International Society for Magnetic Resonance in Medicine

Model-Based Prediction to Evaluate Residence Time of Hyaluronic Acid Based Dermal Fillers

Dermal fillers are gel-type substances for nonsurgical medical-device use to achieve facial rejuvenation. Currently, the most widely used skin fillers are hyaluronic-acid-based dermal fillers. This study aimed to explain the change in the volume of injected dermal fillers by developing a mathematical kinetic model for various dermal fillers. The kinetics of the injected fillers were separated by a biphasic phenomenon. We attributed an increase in filler volume to the hydration of hyaluronic acid molecules and injection-site reaction and a decrease in volume to enzyme-mediated degradation. To explain these in vivo characteristics of dermal fillers, we proposed a two-compartment model, divided into a depot compartment (where the filler was injected) and a subcutaneous compartment (an observation compartment where the fillers swell and degrade), assuming that the swelling and degradation occurred in accordance with the swelling and degradation rate constants, respectively. The model was developed using five hyaluronic-acid-based dermal fillers and NONMEM. We determined that the rate-limiting step for the complete degradation of the dermal fillers in vivo was the swelling phase, as described by the swelling rate constant (Kswell). This study could enable scientists developing novel dermal fillers to predict the in vivo behavior of fillers

Model-Based Prediction to Evaluate Residence Time of Hyaluronic Acid Based Dermal Fillers

Dermal fillers are gel-type substances for nonsurgical medical-device use to achieve facial rejuvenation. Currently, the most widely used skin fillers are hyaluronic-acid-based dermal fillers. This study aimed to explain the change in the volume of injected dermal fillers by developing a mathematical kinetic model for various dermal fillers. The kinetics of the injected fillers were separated by a biphasic phenomenon. We attributed an increase in filler volume to the hydration of hyaluronic acid molecules and injection-site reaction and a decrease in volume to enzyme-mediated degradation. To explain these in vivo characteristics of dermal fillers, we proposed a two-compartment model, divided into a depot compartment (where the filler was injected) and a subcutaneous compartment (an observation compartment where the fillers swell and degrade), assuming that the swelling and degradation occurred in accordance with the swelling and degradation rate constants, respectively. The model was developed using five hyaluronic-acid-based dermal fillers and NONMEM. We determined that the rate-limiting step for the complete degradation of the dermal fillers in vivo was the swelling phase, as described by the swelling rate constant (Kswell). This study could enable scientists developing novel dermal fillers to predict the in vivo behavior of fillers

Cardiac Effects of Thyrotropin Oversuppression with Levothyroxine in Young Women with Differentiated Thyroid Cancer

Background. We investigated the cardiac effects of TSH (thyroid-stimulating hormone) oversuppression in women with thyroidectomized differentiated thyroid cancer (DTC) during levothyroxine suppression therapy. Methods. Fourteen young female patients with DTC were enrolled. The duration of TSH-suppressive therapy was 5 to 9 years. They satisfied the following criteria: (1) a serum level of TSH < 0.1 mU/L in the intermediate-risk or TSH < 0.3 mU/L in the low-recurrence-risk group and (2) having been receiving a fixed dose of LT4 before the study. Controls matched for age, sex, and body mass index (BMI) were compared in terms of the levels of serum free T4, free T3, TSH, plasma N-terminal pro-brain natriuretic peptide (NT-pro-BNP), and cardiac functions and structures. Results. DTC patients and control subjects were well matched in heart rate and blood pressure. There were marked differences in serum TSH (P=0.001) and free T4 (P=0.002). However, there were no differences between the groups in serum free T3 and plasma NT-pro-BNP. Furthermore, there were nonsignificant differences in cardiac functions and structures between the groups. Conclusions. This study shows that TSH suppression therapy in women with DTC may be safe with respect to cardiac functions and structures despite intermittent oversuppression of TSH during long-term suppressive therapy. Trial Registration. This trial is registered with clinicaltrials.gov identifier NCT02645786

On the Origin of Improved Charge Transport in Double-Gate In–Ga–Zn–O Thin-Film Transistors: A Low-Frequency Noise Perspective

International audienceLow-frequency noise (LFN) in double-gate (DG) In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) is studied to investigate the origin of performance improvement. We found that thinning down the IGZO film enhances such improvements. With 7-nm IGZO, the mobility is raised by a factor of 3.77, and the subthreshold slope is reduced to 0.17 V/decade from single-gate to DG mode. Device simulations show that bulk transport inside IGZO film emerges as the two gates field effects get coupled. The LFN results reveal a transport transition from surface to bulk and disclose the superior bulk transport that experiences slight phonon scattering with a small Hooge parameter α H = 4.44 × 10 -3 whereas the surface transport undergoes serious charge trapping with surface trap densities about 2 × 10 11 eV -1 cm -2