Strongly Correlated Charge Transport in Silicon Metal-Oxide-Semiconductor Field-Effect Transistor Quantum Dots

Quantum shot noise probes the dynamics of charge transfers through a quantum conductor, reflecting whether quasiparticles flow across the conductor in a steady stream, or in syncopated bursts. We have performed high-sensitivity shot noise measurements in a quantum dot obtained in a silicon metal-oxide-semiconductor field-effect transistor. The quality of our device allows us to precisely associate the different transport regimes and their statistics with the internal state of the quantum dot. In particular, we report on large current fluctuations in the inelastic cotunneling regime, corresponding to different highly correlated, non-Markovian charge transfer processes. We have also observed unusually large current fluctuations at low energy in the elastic cotunneling regime, the origin of which remains to be fully investigated.

Acute anti-obesity effects of intracerebroventricular 11β-HSD1 inhibitor administration in diet-induced obese mice

The hypothalamus is the regulatory centre of both appetite and energy balance and endoplasmic reticulum (ER) stress in the hypothalamus is involved in the pathogenesis of obesity. Recently, inhibition of 11 β hydroxysteroid dehydrogenase type1 (11β-HSD1) was reported to have an anti-obesity effect by reducing fat mass. However, the link between the role of 11β-HSD1 in the hypothalamus and obesity has yet to be determined. In the present study, embryonal primary hypothalamic neurones and high-fat diet (HFD) fed mice were used to investigate the anorexigenic effects of 11β-HSD1 inhibitors both in vitro and in vivo. In hypothalamic neurones, carbenoxolone (a non selecitve 11β-HSD inhibitor) alleviated ER stress and ER stress-induced neuropeptide alterations. In HFD mice, i.c.v. administration of carbenoxolone or KR67500 (nonselective and selective 11β-HSD1 inhibitors, respectively) was associated with less weight gain compared to control mice for 24 hours after treatment, presumably by reducing food intake. Furthermore, glucose regulated protein (Grp78), spliced X-box binding protein (Xbp-1s), c/EBP homologous protein (chop) and ER DnaJ homologue protein (Erdj4) expression was decreased in the hypothalami of mice administrated 11β-HSD1 inhibitors compared to controls. Conversely, the phosphorylation of protein kinase B (PKB/Akt), signal transducer and activator of transcription 3 (Stat3), mitogen-activated protein kinase (MAPK/ERK) and S6 kinase1 (S6K1) in the hypothalamus was induced more in mice treated using the same regimes. In conclusion, acute 11β-HSD1 inhibition in the hypothalamus could reduce food intake by decreasing ER stress and increasing insulin, leptin, and mammalian target of rapamycin complex 1 (mTORC1) signalling.

First-principles study of a MXene terahertz detector

2D transition metal carbides, nitrides, and carbonitrides called MXenes have attracted increasing attention due to their outstanding properties in many fields. By performing systematic density functional theory calculations, here we show that MXenes can serve as excellent terahertz detecting materials. Giant optical absorption and extinction coefficients are observed in the terahertz range in the most popular MXene, namely, Ti₃C₂, which is regardless of the stacking degree. Various other optical properties have been investigated as well in the terahertz range for in-depth understanding of its optical response. We find that the thermoelectric figure of merit (ZT) of stacked Ti₃C₂ flakes is comparable to that of carbon nanotube films. Based on excellent terahertz absorption and decent thermoelectric efficiency in MXenes, we finally suggest the promise of MXenes in terahertz detection applications, which includes terahertz bolometers and photothermoelectric detectors. Possible ZT improvements are discussed in large-scale MXene flake films and/or MXene-polymer composite films.

Comparison of 3D and 2D shear-wave elastography for differentiating benign and malignant breast masses: focus on the diagnostic performance

AIM

To evaluate the diagnostic performance of three-dimensional (3D) image shear-wave elastography (SWE) for differentiating benign from malignant breast masses compared to two-dimensional (2D) SWE and B-mode ultrasound (US).

MATERIALS AND METHODS

This study consisted of 205 breast lesions from 199 patients who underwent B-mode US and SWE before biopsy from January 2014 to March 2016. Quantitative elasticity values (maximum and mean elasticity, Emax and Emean) obtained from 2D and 3D SWE (axial, sagittal, and coronal images) were reviewed retrospectively, in addition to the histopathological findings including immunohistochemistry profiles (luminal A, luminal B, human epidermal growth factor receptor 2 (HER2)-enriched, and triple-negative breast cancer) in cases of malignancy. Histopathological findings were regarded as the reference standard. The diagnostic performance of each data set was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC) analysis to compare sensitivity and specificity.

RESULTS

Among 205 lesions, 105 (51.22%) were malignant and 100 (48.78%) were benign. Compared to benign masses, malignant masses had higher values of Emax and Emean on both 2D and 3D SWE, the differences of which were statistically significant (p<0.001). The AUCs of 2D, 3D axial, and sagittal SWE were significantly higher than that of 3D coronal SWE (p<0.05). In addition, the sensitivities of axial, sagittal, and coronal 3D SWE were all higher than that of 2D SWE for Emean (81.9%, 87.6%, and 89.5% versus 70.5%, respectively, p<0.05). Conversely, the specificity of 2D and 3D axial SWE was higher than that of 3D sagittal and coronal SWE (Emax, 84%, 83% versus 76%, 73%; Emean, 85%, 81% versus 68%, 50%, respectively, p<0.05). We also assessed changes in Breast Imaging-Reporting and Data System (BI-RADS) category 3 and category 4a lesions by adding each of the parameters for 2D and 3D SWE in B-mode US. The specificity, PPV, and accuracy of combined 2D or combined 3D SWE with B-mode US was statistically higher than that of B-mode US alone for differentiating benign and malignant lesions (p<0.05).

CONCLUSIONS

Among SWE images, 2D SWE, and 3D SWE axial and sagittal images exhibited superior diagnostic performance compared to 3D coronal images. Addition of 3D SWE images to B-mode US improved the diagnostic performance for distinguishing benign from malignant masses.