Precision excimer laser annealed Ga-doped ZnO electron transport layers for perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) continue to attract considerable attention due to their excellent photovoltaic performance and low cost. In order to realize the fabrication of PSCs on temperature-sensitive substrates, low-temperature processing of all the components in the device is required, however, the majority of the high-performance PSCs rely on the electron transport layers (ETLs) processed at high temperatures. Herein, we apply excimer laser annealing (ELA) to treat ETLs (Ga-doped ZnO, GZO) at room temperature. A synergetic improvement in optical transparency and electrical conductivity is achieved after ELA treatment, which in turn improves light absorption, enhances electron injection, and depresses charge recombination. Devices fabricated with ELA treated GZO ETL acheived a power conversion efficiency (PCE) of 13.68%, higher than that of the PSCs utilizing GZO with conventional high-temperature annealing (12.96%). Thus, ELA is a promising technique for annealing ETLs at room temperature to produce efficient PSCs on both rigid and flexible substrates

Unregulated miR-96 Induces Cell Proliferation in Human Breast Cancer by Downregulating Transcriptional Factor FOXO3a

FOXO transcription factors are key tumor suppressors in mammalian cells. Until now, suppression of FOXOs in cancer cells was thought to be mainly due to activation of multiple onco-kinases by a phosphorylation-ubiquitylation-mediated cascade. Therefore, it was speculated that inhibition of FOXO proteins would naturally occur through a multiple step post-translational process. However, whether cancer cells may downregulate FOXO protein via an alternative regulatory mechanism is unclear. In the current study, we report that expression of miR-96 was markedly upregulated in breast cancer cells and breast cancer tissues compared with normal breast epithelial cells (NBEC) and normal breast tissues. Ectopic expression of miR-96 induced the proliferation and anchorage-independent growth of breast cancer cells, while inhibition of miR-96 reduced this effect. Furthermore, upregulation of miR-96 in breast cancer cells resulted in modulation of their entry into the G1/S transitional phase, which was caused by downregulation of cyclin-dependent kinase (CDK) inhibitors, p27Kip1 and p21Cip1, and upregulation of the cell-cycle regulator cyclin D1. Moreover, we demonstrated that miR-96 downregulated FOXO3a expression by directly targeting the FOXO3a 3′-untranslated region. Taken together, our results suggest that miR-96 may play an important role in promoting proliferation of human breast cancer cells and present a novel mechanism of miRNA-mediated direct suppression of FOXO3a expression in cancer cells

A two degree-of-freedom rotary-linear machine with transverse-flux structure

This paper proposes a two-degree-of-freedom rotary-linear machine with transverse-flux structure. In the proposed machine, the rotary flux and linear flux are naturally decoupled, hence its linear force and rotary torque can be controlled independently. Unlike the conventional rotary-linear machines with 3D-flux pattern, the proposed machine with transverse-flux structure can employ circumferentially laminated steel sheets to provide outstanding electromagnetic performance. The topology and operation principle of the proposed machine are introduced, while the naturally decoupled-flux feature is explained by analytical modelling and 3D finite-element method. A parametric study of pole-pair numbers combination is conducted to obtain the optimal pole-pair numbers in both axial and circumferential directions. The optimal electromagnetic performances are quantitatively compared with other two conventional rotary-linear machines, while an experimental prototype is manufactured to verify the proposed concepts.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThis work was supported by National Research Foundation (NRF) Singapore under its NRF Fellowship Grant NRF-NRFF12-2020-0003, and the Ministry of Education, Singapore, under its Academic Research Fund (AcRF) Tier 1 Program under Grant 2019-T1-002-064

Nanosecond laser ablation tandem inductively coupled plasma mass and optical emission spectrometry for micro-chemical elemental analysis

A novel experimental system was designed for micro-chemical elemental analysis using a laser ablation technique tandem to both mass and optical emission spectrometry. One new excimer gas laser of 193 nanometer wavelength was constructed to replace the COMPexPro 102 laser unit in the RESOlution M50 laser ablation system without changing the ablation cell. The ablated mass (aerosol) was introduced into the inductively coupled plasma mass spectrometer, i.e. Agilent 7500, where optical emission spectrometry was performed simultaneously using an Ocean Optics fiber optic spectrometer. The fiber optic spectrometer consists of six channels, which can detect the optical emission lines from plasma and cover wavelengths from 190 nm to 800 nm. Standard reference materials were measured for demonstrating the elemental analytical method. The constant LA-ICP-MS transient signals, acceptable concentration determinations of MPI DING glass ATHO or T1 samples and negligible differences of elemental fractionation due to replacement of the laser source in RESOlution M-50 suggest that our newly constructed excimer gas laser can satisfy LA-ICP-MS microchemical analysis. Furthermore, the laser ablated particle resultant inductively coupled plasma optical emission lines can be identified, and the quite good linear correlation of signals in various emission lines of the same element analysed suggests that the wavelength resolution necessary for quantitative elemental analysis by LA-ICP-OES can be achievable using a fiber optic spectrometer. Finally, based on sharing the same inductively coupled plasma configuration in our new LA-ICP-MS & OES system, the linear correlation between signals of LA-ICP-MS and LA-ICP-OES for the same elements can be recognized. The calibration curves for optical emission lines of element manganese, and the coefficient ratios around 0.999, suggest that the novel method of LA-ICP-MS & OES might be a feasible option for micro-chemical elemental analysis through synchronously detecting the stoichiometric composition in the laser ablated mass resultant inductively coupled plasma

Effects of spark plasma sintering parameters on mechanical and thermal properties of U3Si2 pellets

BackgroundU3Si2 is regarded as one of the most promising accident-tolerant nuclear fuels for light water reactors and is expected to replace the UO2 nuclear fuel in the future. Currently, spark plasma sintering (SPS) is an advanced technique for preparing U3Si2 pellets; however, the influence of SPS parameters on the performance of the pellets is unclear.PurposeThis study aims to investigate the effects of different sintering parameters (temperature and pressure) on the mechanical and thermal properties of the U3Si2 pellets prepared using SPS technology.MethodsThe thermal diffusivity of U3Si2 pellets was measured using a laser flash apparatus, and the thermal conductivity of the pellets was calculated. The mechanical properties of the pellets, including hardness, Young's modulus, and fracture toughness, were measured using nanoindenter. Thereafter, the influence of different sintering temperatures in the range of 1 000~1 300 ℃ and pressures in the range of 30~90 MPa on the mechanical and thermal properties of U3Si2 pellets were carefully examined.ResultsThe measurement results show that the thermal conductivity of the as-synthesized pellets increases linearly with temperature in the range 27~700 ℃. Moreover, increasing the sintering temperature and pressure improves the thermal conductivity of the U3Si2 pellets. The hardness and Young's modulus of the pellets increase with an increase in sintering temperature. They also exhibit a trend of first increasing and then stabilizing with increasing pressure, and tend to fully stabilize at 60 MPa. Moreover, the fracture toughness of the pellets decreases with the increase of sintering temperature and increases with increasing pressure.ConclusionsBased on the above results, optimized SPS parameters for the U3Si2 pellets are proposed, and this study provides a reference for the preparation of high-performance U3Si2 pellets