Liquid-Metal Synthesized Ultrathin SnS Layers for High-Performance Broadband Photodetectors

Atomically thin materials face an ongoing challenge of scalability, hampering practical deployment despite their fascinating properties. Tin monosulfide (SnS), a low-cost, naturally abundant layered material with a tunable bandgap, displays properties of superior carrier mobility and large absorption coefficient at atomic thicknesses, making it attractive for electronics and optoelectronics. However, the lack of successful synthesis techniques to prepare large-area and stoichiometric atomically thin SnS layers (mainly due to the strong interlayer interactions) has prevented exploration of these properties for versatile applications. Here, SnS layers are printed with thicknesses varying from a single unit cell (0.8 nm) to multiple stacked unit cells (approximate to 1.8 nm) synthesized from metallic liquid tin, with lateral dimensions on the millimeter scale. It is reveal that these large-area SnS layers exhibit a broadband spectral response ranging from deep-ultraviolet (UV) to near-infrared (NIR) wavelengths (i.e., 280-850 nm) with fast photodetection capabilities. For single-unit-cell-thick layered SnS, the photodetectors show upto three orders of magnitude higher responsivity (927 A W-1) than commercial photodetectors at a room-temperature operating wavelength of 660 nm. This study opens a new pathway to synthesize reproduceable nanosheets of large lateral sizes for broadband, high-performance photodetectors. It also provides important technological implications for scalable applications in integrated optoelectronic circuits, sensing, and biomedical imaging

Changes in insider trading legislation in Singapore : the effect on corporate insiders on Singapore exchange (sgx).

The study discusses the implication of changes in insider trading legislation in 2000 on corporate insiders' trading behavior. It examines transactions done by corporate insiders of companies listed in the Singapore Exchange and attempts to find out whether the enhancement of Singapore insider trading laws in 2000 has an impact on the trading behavior of corporate insiders

A cross-cultural study : the impact of individualism-collectivism on consumer behavior towards online coupons.

Cultural differences are known to effect consumer behavior and attitude. Past researches have studied their effect on the acceptance of traditional coupons and internet shopping. However, little empirical research exists on the effectiveness of online coupons. Online coupons are not only digital versions of traditional coupons; these coupons utilize group-buying in order to increase discount rates up to 80%. This study examines the effects of cultural differences on consumer behavior in the purchase of online coupons. In particular, one of Hofstede’s cultural dimensions, individualism-collectivism, is used to investigate these effects. Respondents were chosen and subjected to an internet-administered survey, which included questions about their purchase intention of a manipulated online coupon, their perception of online coupons in general, and other behavior involved in the purchase of online coupons. The findings of this study indicate that consumers are differentially influenced by (1) product scarcity induced by urgency from time left and (2) product popularity indicated by the number of people who brought the coupon. Compared to collectivists, individualists are more likely to purchase online coupons if lesser people had bought the deal beforehand and if a shorter time remains to buy the deal. This study also reveals the differences on how consumers value group-buying deals. Collectivists’ purchase intentions are influenced by discount percentage and information search, whereas, individualists are influenced by their perception of the value of the deal.BUSINES

Black Phosphorus-Diketopyrrolopyrrole Polymer Semiconductor Hybrid for Enhanced Charge Transfer and Photodetection

Black phosphorus (BP) has emerged as an exciting 2D material for optics, photonics, and electronics. However, there are few studies on BP in terms of modulation and enhancement of their electronic and optical properties and their concurrent reactivity and hence reduction after exposure to the ambient environment. To resolve such challenges, creating inorganic–organic hybrid materials is a suitable approach that offers significant opportunities to enhance the utility of BP by combining them with an organic material which has a complementary set of properties. Herein, a hybrid-layered BP material coupled with a low bandgap donor–acceptor organic semiconducting polymer, selenophene-flanked diketopyrrolopyrrole with thienyl-vinylene-thienyl (PDPPSe–TVT) is reported, to broaden the optical absorption and tune the ambipolar field effect transistor characteristics. A highly sensitive, nongated broadband photodetection capability of the hybrid device with a detection range from UV–vis to near-IR (280–1050 nm) and responsivities of up to 4.22 × 103 A W−1 in ambient conditions. In addition to improved photodetection, simultaneous enhancement in both hole (71%) and electron (91%) mobilities is achieved while protecting the sensitive BP material from rapid environmental degradation. The findings therefore report a breakthrough in enhancing the utility of BP as a light-active material for versatile photonics and electronics applications without operating in an inert environment. </p

The Acoustophotoelectric Effect: Efficient Phonon–Photon–Electron Coupling in Zero-Voltage-Biased 2D SnS₂ for Broad-Band Photodetection

Two-dimensional (2D) layered metal dichalcogenides constitute a promising class of materials for photodetector applications due to their excellent optoelectronic properties. The most common photodetectors, which work on the principle of photoconductive or photovoltaic effects, however, require either the application of external voltage biases or built-in electric fields, which makes it challenging to simultaneously achieve high responsivities across broad-band wavelength excitationespecially beyond the material’s nominal band gapwhile producing low dark currents. In this work, we report the discovery of an intricate phonon–photon–electron couplingwhich we term the acoustophotoelectric effectin SnS2 that facilitates efficient photodetection through the application of 100 MHz order propagating surface acoustic waves (SAWs). This effect not only reduces the band gap of SnS2 but also provides the requisite momentum for indirect band gap transition of the photoexcited charge carriers, to enable broad-band photodetection beyond the visible light range, while maintaining pA-order dark currents without the need for any external voltage bias. More specifically, we show in the infrared excitation range that it is possible to achieve up to 8 orders of magnitude improvement in the material’s photoresponsivity compared to that previously reported for SnS2-based photodetectors, in addition to exhibiting superior performance compared to most other 2D materials reported to date for photodetection

Clinical relevance of screening checklists for detecting cancer predisposition syndromes in Asian childhood tumours

Assessment of cancer predisposition syndromes (CPS) in childhood tumours is challenging to paediatric oncologists due to inconsistent recognizable clinical phenotypes and family histories, especially in cohorts with unknown prevalence of germline mutations. Screening checklists were developed to facilitate CPS detection in paediatric patients; however, their clinical value have yet been validated. Our study aims to assess the utility of clinical screening checklists validated by genetic sequencing in an Asian cohort of childhood tumours. We evaluated 102 patients under age 18 years recruited over a period of 31 months. Patient records were reviewed against two published checklists and germline mutations in 100 cancer-associated genes were profiled through a combination of whole-exome sequencing and multiplex ligation-dependent probe amplification on blood-derived genomic DNA. Pathogenic germline mutations were identified in ten (10%) patients across six known cancer predisposition genes: TP53, DICER1, NF1, FH, SDHD and VHL. Fifty-four (53%) patients screened positive on both checklists, including all ten pathogenic germline carriers. TP53 was most frequently mutated, affecting five children with adrenocortical carcinoma, sarcomas and diffuse astrocytoma. Disparity in prevalence of germline mutations across tumour types suggested variable genetic susceptibility and implied potential contribution of novel susceptibility genes. Only five (50%) children with pathogenic germline mutations had a family history of cancer. We conclude that CPS screening checklists are adequately sensitive to detect at-risk children and are relevant for clinical application. In addition, our study showed that 10% of Asian paediatric solid tumours have a heritable component, consistent with other populations.NMRC (Natl Medical Research Council, S’pore)Published versio

Management of coronary disease in patients with advanced kidney disease

BACKGROUND Clinical trials that have assessed the effect of revascularization in patients with stable coronary disease have routinely excluded those with advanced chronic kidney disease. METHODS We randomly assigned 777 patients with advanced kidney disease and moderate or severe ischemia on stress testing to be treated with an initial invasive strategy consisting of coronary angiography and revascularization (if appropriate) added to medical therapy or an initial conservative strategy consisting of medical therapy alone and angiography reserved for those in whom medical therapy had failed. The primary outcome was a composite of death or nonfatal myocardial infarction. A key secondary outcome was a composite of death, nonfatal myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. RESULTS At a median follow-up of 2.2 years, a primary outcome event had occurred in 123 patients in the invasive-strategy group and in 129 patients in the conservative-strategy group (estimated 3-year event rate, 36.4% vs. 36.7%; adjusted hazard ratio, 1.01; 95% confidence interval [CI], 0.79 to 1.29; P=0.95). Results for the key secondary outcome were similar (38.5% vs. 39.7%; hazard ratio, 1.01; 95% CI, 0.79 to 1.29). The invasive strategy was associated with a higher incidence of stroke than the conservative strategy (hazard ratio, 3.76; 95% CI, 1.52 to 9.32; P=0.004) and with a higher incidence of death or initiation of dialysis (hazard ratio, 1.48; 95% CI, 1.04 to 2.11; P=0.03). CONCLUSIONS Among patients with stable coronary disease, advanced chronic kidney disease, and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of death or nonfatal myocardial infarction