Miniaturized power limiter metasurface based on Fano-type resonance and Babinet principle.

In this work, we present a miniaturize power limiter, a device with size smaller than that required by the working frequency, made of coupled self-complementary electric inductive-capacitive (CELC) resonator and original electric inductive-capacitive (ELC) structure. We also make use of Babinet principle to ensure both CELC and ELC are resonating at the same frequency. The CELC structure is loaded with a Schottky diode to achieve the effect of a nonlinear power limiter. The constructive interference of CELC and ELC structure produces a new Fano-type resonance peak at a lower frequency. The Fano peak is sharp and able to concentrate electric field at a region between the inner and outer metallic patch of the metastructure, hence enhancing the nonlinear properties of the loaded diode. The Fano peak enhances the maximum isolation of the power limiter due to the local field enhancement at where the diode is loaded. Numerical simulation and experiment are conducted in the S-band frequency to verify the power limiting effect of the device designed and to discuss the formation of Fano peak. The power limiter designed has a maximum isolation of 8.4 dB and a 3-dB isolation bandwidth of 6%.

Metal nanocluster light-emitting devices with suppressed parasitic emission and improved efficiency: exploring the impact of photophysical properties.

Here we investigate the photophysical properties of Au(0)@Au(i)-thiolate nanoclusters by controlling the degree of aggregation, and measure electrochemical energy levels to design a metal nanocluster-based thin film LED (MNC-LED) structure. These efforts allow us to implement MNC-LEDs with luminance exceeding 40 cd m(-2) and external quantum efficiency exceeding 0.1% with clearly visible orange emission. It is also demonstrated that by varying the sizes of nanoclusters, the electroluminescence spectrum of the device can be tuned to the infrared emission, indicating the possibility of exploiting metal nanocluster emitters for use over a wide spectral range.

A novel Osmium-based compound targets the mitochondria and triggers ROS-dependent apoptosis in colon carcinoma.

Engagement of the mitochondrial-death amplification pathway is an essential component in chemotherapeutic execution of cancer cells. Therefore, identification of mitochondria-targeting agents has become an attractive avenue for novel drug discovery. Here, we report the anticancer activity of a novel Osmium-based organometallic compound (hereafter named Os) on different colorectal carcinoma cell lines. HCT116 cell line was highly sensitive to Os and displayed characteristic features of autophagy and apoptosis; however, inhibition of autophagy did not rescue cell death unlike the pan-caspase inhibitor z-VAD-fmk. Furthermore, Os significantly altered mitochondrial morphology, disrupted electron transport flux, decreased mitochondrial transmembrane potential and ATP levels, and triggered a significant increase in reactive oxygen species (ROS) production. Interestingly, the sensitivity of cell lines to Os was linked to its ability to induce mitochondrial ROS production (HCT116 and RKO) as HT29 and SW620 cell lines that failed to show an increase in ROS were resistant to the death-inducing activity of Os. Finally, intra-peritoneal injections of Os significantly inhibited tumor formation in a murine model of HCT116 carcinogenesis, and pretreatment with Os significantly enhanced tumor cell sensitivity to cisplatin and doxorubicin. These data highlight the mitochondria-targeting activity of this novel compound with potent anticancer effect in vitro and in vivo, which could have potential implications for strategic therapeutic drug design.

Dynamic character of charge transport parameters in disordered organic semiconductor field-effect transistors.

In this perspective article, we discuss the dynamic instability of charge carrier transport in a range of popular organic semiconductors. We observe that in many cases field-effect mobility, an important parameter used to characterize the performance of organic field-effect transistors (OFETs), strongly depends on the rate of the gate voltage sweep during the measurement. Some molecular systems are so dynamic that their nominal mobility can vary by more than one order of magnitude, depending on how fast the measurements are performed, making an assignment of a single mobility value to devices meaningless. It appears that dispersive transport in OFETs based on disordered semiconductors, those with a high density of localized trap states distributed over a wide energy range, is responsible for the gate voltage sweep rate dependence of nominal mobility. We compare such rate dependence in different materials and across different device architectures, including pristine and trap-dominated single-crystal OFETs, as well as solution-processed polycrystalline thin-film OFETs. The paramount significance given to a single mobility value in the organic electronics community and the practical importance of OFETs for applications thus suggest that such an issue, previously either overlooked or ignored, is in fact a very important point to consider when engaging in fundamental studies of charge carrier mobility in organic semiconductors or designing applied circuits with organic semiconductors.

Impact of a fall prevention programme in acute hospital settings in Singapore.

INTRODUCTION: This study aimed to develop a multifaceted strategy using tailored interventions to implement a fall prevention programme, and to achieve a change in fall prevention practices and a reduction in fall incidence at an acute care hospital in Singapore. METHODS: A comparative study was conducted at two acute care hospitals (intervention and control) in Singapore. Pre-intervention, post-intervention and six-month follow-up knowledge assessments of 641 nursing staff, and audits of fall rates and fall prevention practices were performed to determine the effectiveness of a multifaceted strategy with targeted interventions in supporting the implementation of a fall prevention programme. RESULTS: The mean post-knowledge test scores at six months were statistically significantly higher (t[516] is -3.3, p-value is less than 0.01) at the intervention hospital (10.3 +/- 2.3) compared to the scores at the control hospital (9.8 +/- 1.8). Increased compliance with the use of fall risk assessment tools was evident in 99.4 percent and 99.3 percent of all patient records at the control and intervention hospitals, respectively. Following the implementation strategy for a fall prevention programme, there was a non-significant reduction in fall rates from 1.44 to 1.09 per 1,000 patient days at the intervention hospital. No reduction in the fall rate was observed at the control hospital. CONCLUSION: A multifaceted strategy for the implementation of a fall prevention programme was effective in increasing nurses' knowledge and the use of the fall risk assessment, but did not have a statistically significant impact on a reduction in the fall rate. The increase in nurses' knowledge and change in nursing practice were important markers of success in terms of fall prevention at the acute hospitals.