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Abstract The understanding and engineering of the plasmon-exciton coupling are necessary to control the innovative optoelectronic device platform. In this study, we investigated the intertwined mechanism of each plasmon-exciton couplings in monolayer molybdenum disulfide (MoS2) and plasmonic hybrid structure. The results of absorption, simulation, electrostatics, and emission spectra show that interaction between photoexcited carrier and exciton modes are successfully coupled by energy transfer and exciton recombination processes. Especially, neutral exciton, trion, and biexciton can be selectively enhanced by designing the plasmonic hybrid platform. All of these results imply that there is another degree of freedom to control the individual enhancement of each exciton mode in the development of nano optoelectronic devices.

The spatial configuration of nanostructure building blocks determines the physical and optical properties of their superstructures. Here, the authors report on complex nanoparticles in which different geometric forms of nanoframes are nested into a single entity by multistep chemical reactions.

Abstract We investigate conducting characteristics of biochar derived from the pyrolysis of a paper at terahertz frequencies. Paper is annealed under temperatures ranging from 600 to 1000 °C to modify structural and electrical properties. We experimentally observe that the terahertz conductivity increases above 102 S/m as the annealing temperature increases up to 800 °C. From structural characterization using energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, we confirm that more graphitic biochars are produced in high annealing temperature, in agreement with the improvement of terahertz conductivity. Our results show that biochar can be a highly promising candidate to be used in paper-based devices operating at terahertz frequencies.

We report on a prototypical study of the detection of microplastic embedded in table salts by using terahertz time-domain spectroscopy. In the experiment, high-density polyethylene (HDPE) of sizes from 150 to 400 μm are used as a representative microplastic and mixed with table salts. Analyzing terahertz transmittance with an effective medium model, we extract various optical properties such as refractive index, absorption coefficient, and real/imaginary parts of the dielectric constant of the mixture. Consequently, the optical properties exhibit volume-ratio-dependence in 0.1–0.5 THz regimes. Especially, the refractive index and the real part of the dielectric constant possess monotonic frequency dependence, meaning that the quantities can be relevant indicators for the detection of the microplastic in terms of practical applications. Our work proves that terahertz time-domain spectroscopy can pave a way to recognize microplastic mixed with salts and be expanded for detecting various micro-sized particles.

Twisted bilayer graphene (tBLG) is two stacked single graphene sheets rotated at a specific angle. The twist angle plays an important role in the physical properties of the tBLG. In this study, we analyzed the interaction distance between two graphene layers in tBLG using Raman spectroscopy and atomic force microscopy. To confirm the interaction of the upper and bottom graphenes in the tBLG, we prepared two tBLGs with twist angles of 5° and 24°. The interlayer distance was controlled by depositing a gold bar between the two graphene layers. We found that the decoupling interlayer distance of the tBLG was different depending on the twist angle (0.74 nm for 5° and 1.66 nm for 24°). This indicates that the interaction between two graphene layers is strongly coupled with small twist angle, as expected.

We report on an electronic structure change of single-walled carbon nanotube (SWNT) on hexagonal boron nitride due to electron doping via high-pressure H2 exposure. The fractional coverage of hydrogenated carbon atom is estimated to be at least θ = 0.163 from the in situ Ids–Vg measurements of the release process. Raman spectroscopy and x-ray photoelectron spectroscopy were carried out to support the in situ electrical measurements. In particular, we used the dissociative Langmuir-type model to yield the desorption coefficient kdes by fitting it to the in situ electrical data. Finally, we applied this hydrogenation method to the SWNT network on the commercial Si/SiO2 substrate to open the possibility of the scalable n-type semiconducting SWNT FETs. [ABSTRACT FROM AUTHOR]

Large prospective studies have demonstrated that good glycemic control in diabetes is associated with reduced development of diabetic complications. However, it is not common to achieve and maintain euglycemia in clinical practice because of the progressive nature of diabetes and misunderstanding of the pathophysiology of the disease. We hypothesized that intensive insulin treatment has long-term beneficial effects in type 2 diabetic patients by compensating the progressive impairment of β-cell function. Continuous subcutaneous insulin infusion (CSII) using insulin pump was used to provide the physiologic insulin requirements delicately. The retrospective clinical records of type 2 diabetic patients with long duration of CSII (n=17, male 47%, age 55.9±8.0, BMI 24.1±3.1, CSII duration 10.2±2.5 years) who admitted to Diabetes Center at Konkuk University Hospital since 1993 were analyzed. At baseline, all the subjects except one had long-standing type 2 diabetes (disease duration 8.5±6.0 years) and had uncontrolled hyperglycemia (HbA[sub 1]c 10.0±2.7%) in spite of full dose of oral hypoglycemic agents and/or intermediate acting insulin. At present, HbA[sub 1]c level has improved (6.5±1.1% vs baseline 10.0±2.7%, p <0.001), diastolic BP has decreased (77.8±6.7 vs baseline 87.6±8.3 mmHg, p <0.05), serum HDL and LDL levels has improved without lipid lowering medication (52.8±9.7 and 129.5±35.6 mg/dL vs baseline 33.5±9.5 and 146±46.7, respectively, p<0.05), and serum creatinine did not increase over 10 years (below <1.3mg/dL, except one). While, no significant change of BMI was observed (p=0.61 vs baseline). In conclusion, ten years of CSII treatment in type 2 diabetic patients had long-term benefits in maintenance of euglycemia and improvement of major cardiovascular risk factors. [ABSTRACT FROM AUTHOR]

Type 2 diabetes mellitus (T2D) is characterized by insulin resistance and progressive impairment of β-cell function. However, a series of reports suggested that the early decline of β-cell function due to high susceptibility of βcell to glucotoxicity may be the dominant mechanism for the pathogenesis of T2D. We experienced a group of patients maintaining substantial period of remission after discontinuation of long-term continuous subcutaneous insulin infusion (CSII), not only in newly-diagnosed but also in long-standing T2D patients. Among the patients admitted to Diabetes Center at Konkuk University Hospital between 1996-2005, eleven representative patients who achieved long-term remission were chosen (male 45%, age 46.4±15.6, BM124.9±4.2, HbA1c 8.6±2.8%, and disease duration 6.9±9.6 yrs at baseline, CSII duration 19.7±17.6 mos, remission duration 16.8±27.9 mos). They have maintained normoglylcemia without any medical interventions since discontinuation of CSII. Fasting (FPG) and postprandial (PP2) plasma glucose, and HbA1c levels are within normal range (6.0±1.1, 7.0±1.2 mM, 5.9±0.7%, respectively) at present regardless of the severity of hyperglycemia (FPG 11.5±5.4 mM) and the substantial daily dose of insulin (18-150 lU/day) at baseline. C-peptide based HOMA-IR [C-peptide (ng/ml) x FPG (mM)] and HOMA-β [C-peptide (ng/ml)/(FPG (mM)-3.5)] have improved (p<0.05 vs baseline) and insulin based HOMA-β at present have been restored to be equivalent to those of normal subjects (122.8±134.3, p>0.05). Duration of CSII required until the remission showed a significant correlation with the duration of the disease (r=0.76, p<0.01). In conclusion, long-term CSII seemed to have achieved remission of T2D both in newly-diagnosed and long-standing patients through the recovery of insulin secretary function of β-cell, suggesting that treating T2D patients with CSII at any stage of the disease may produce considerable clinical benefits. [ABSTRACT FROM AUTHOR]