Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications. Simple solution processing of the 2D ...perovskite provides opportunities for manufacturing devices at drastically lower cost compared to current commercial technologies. A key to high device performance is to align the 2D perovskite layers, during the solution processing, vertical to the electrodes to achieve efficient charge transport. However, it is yet to be understood how the counter-intuitive vertical orientations of 2D perovskite layers on substrates can be obtained. Here we report a formation mechanism of such vertically orientated 2D perovskite in which the nucleation and growth arise from the liquid-air interface. As a consequence, choice of substrates can be liberal from polymers to metal oxides depending on targeted application. We also demonstrate control over the degree of preferential orientation of the 2D perovskite layers and its drastic impact on device performance.
In this article, we have demonstrated solar cell performance of the inkjet-printed PEDOT:PSS layer and the roles of additives in device efficiency. The newly proposed PEDOT:PSS inks with additives of ...glycerol and surfactant show the improved surface morphology and high conductivity resulting in the enhanced photovoltaic performance. Using the optimized ink formulation of PEDOT:PSS, we have demonstrated a 3.16% efficient solar cell with an inkjet printing.
It has frequently been reported that exposure to artificial light at night (ALAN) may cause negative health effects, such as breast cancer, circadian phase disruption and sleep disorders. Here, we ...reviewed the literature assessing the effects of human exposure to ALAN in order to list the health effects of various aspects of ALAN. Several electronic databases were searched for articles, published through August 2014, related to assessing the effects of exposure to ALAN on human health; these also included the details of experiments on such exposure. A total of 85 articles were included in the review. Several observational studies showed that outdoor ALAN levels are a risk factor for breast cancer and reported that indoor light intensity and individual lighting habits were relevant to this risk. Exposure to artificial bright light during the nighttime suppresses melatonin secretion, increases sleep onset latency (SOL) and increases alertness. Circadian misalignment caused by chronic ALAN exposure may have negative effects on the psychological, cardiovascular and/or metabolic functions. ALAN also causes circadian phase disruption, which increases with longer duration of exposure and with exposure later in the evening. It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright. This literature review may be helpful to understand the health effects of ALAN exposure and suggests that it is necessary to consider various characteristics of artificial light, beyond mere intensity.
Objectives
We aimed to develop a novel wire‐ and adenosine‐free microcirculatory resistive index from functional angiography (angio‐IMR) to estimate coronary microcirculatory resistance, and to ...investigate how this method can improve clinical interpretation of physiological stenosis assessment with quantitative flow ratio (QFR).
Background
Hyperemic index of coronary microcirculatory resistance (IMR) is a widely used tool to assess microcirculatory dysfunction. However, the need of dedicated intracoronary wire and hyperemia limits its adoption in clinical practice.
Methods
We performed our study in two separate stages: (1) development of a formula (angio‐IMR) to estimate IMR from resting angiograms and aortic pressure (Pa), and (2) validation of the method in a clinical population using invasively measured IMR as reference. Additionally, QFR diagnostic performance was assessed considering angio‐IMR values.
Results
We developed the formula: angio‐IMR = (Pa–0.1*Pa)*QFR*e‐Tmn (where e‐Tmn is an estimation of hyperaemic mean transit time) and validated it in 115 vessels (104 patients). Angio‐IMR correlated well with IMR (Spearman's rho = 0.70, p < 0.001). Sensitivity, specificity, positive and negative predictive value, accuracy and area under the curve of angio‐IMR to predict IMR were 87.5% (73.2–95.8), 85.3% (75.3–92.4), 76.1% (64.5–84.8), 92.8% (84.9–96.7), 85% and 0.90 (0.83–0.95), respectively. False positive QFR measurements decreased from 19.5% to 8.5% when angio‐IMR was incorporated into the QFR interpretation workflow.
Conclusions
Estimation of IMR without physiology wire and adenosine is feasible. Coronary microcirculatory dysfunction causing high IMR can be ruled‐out with high confidence in vessels with low angio‐IMR. Awareness of angio‐IMR contributes to a better clinical interpretation of functional stenosis assessment with QFR.
Coffea arabica and Coffea canephora (Robusta coffee) are the most commonly consumed coffee varieties globally. In this contribution, NMR was used to confirm the coffee authenticity and LC-ESI-MSn ...technique was employed to profile and quantify the most abundant chlorogenic acid in 54 different samples of the two coffee varieties from diverse origins. Significant variations were observed for feruloyl quinic acids, dicaffeoyl quinic acids and 5-sinapoylquinic acid while the mono-caffeoyl quinic acids showed no variation when the two coffee varieties were compared. Additionally isomer ratios were explored as a potential marker for coffee authenticity along with a thorough statistical evaluation of rather extensive data set. Robusta 5-CQA when compared with 3,4-DiCQA Robusta shows high positive correlation, similar high correlation coefficient was observed in 5-pCoQA Robusta when compared with 3-pCoQA as against the Arabica.
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•Chlorogenic acids (CGAs) in 54 green coffee samples were quantified.•CGA levels in green Robusta and Arabica beans were compared using statistical methods.•Key CGAs were identified as biomarkers allowing distinction between bean types.•Using key markers a LDA model was established for 100% differentiation.
The transmission of loads across the soil-structure mobilizes direction-dependent shear resistance, which can be selectively used to design geo-structures. A previous study confirmed the frictional ...anisotropy induced by the interface between the soil and snakeskin-inspired surfaces. However, it is necessary to estimate the interface friction angle quantitatively. In this study, a conventional direct shear apparatus is modified, and 45 cases are performed in two-way shearing directions between bio-inspired surfaces and Jumunjin standard sand under three vertical stresses (50, 100, and 200 kPa). The results show that: (1) shearing against the scales (cranial shearing) mobilizes larger shear resistance and produces a dilative response than shearing along the scales (caudal shearing) and (2) higher scale height or shorter scale length exhibits dilative tendency and produces higher interface friction angle. Further analysis is conducted to capture the frictional anisotropy as a function of the scale geometry ratio, which reveals that the interface anisotropy response is more pronounced during cranial shearing in all the cases, and the difference in the interface friction angle for the caudal → cranial test is higher than that for the cranial → caudal test at the given scale ratio.
Some microscopic flying insects have evolved bristled wings. In the low-Reynolds-number regime they reside in, these porous wings perform like membranous wings because the virtual fluid barriers ...formed by strong viscous diffusion effectively block the gaps between bristles. In this study, the unsteady aerodynamic responses of a two-dimensional bristled wing to a single intermittent head-on gust are investigated numerically for a wide range of the Reynolds number, gust profile and gap width between the bristles. A comparison of a bristled wing with a corresponding flat wing shows that the gap flow alleviates the undesired aerodynamic loading induced by gusts. The Womersley number, which represents the ratio of the gap width to the length scale of unsteady viscous diffusion, is introduced to better characterize the unsteady drag and lift acting on the bristled wing. Under various model conditions, unsteady drag asymptotically converges beyond a specific value of the Womersley number, and unsteady lift exhibits peak values in a limited range of the Womersley number. Because of the linear property of the low-Reynolds-number flow, the unsteady force induced by the intermittent gusty flow is independent of the steady force produced by the basic steady and uniform free stream. For a large Womersley number, the aerodynamic interaction between the bristles is weak under a gusty flow, and thus the unsteady drag and lift forces can be analytically predicted, using the linear superposition approach of the velocity vector perturbed by a single isolated bristle.
CRISPR effectors, which comprise a CRISPR-Cas protein and a guide (g)RNA derived from the bacterial immune system, are widely used for target-specific genome editing. When the gRNA recognizes genomic ...loci with sequences that are similar to the target, deleterious mutations can occur. Off-target mutations with a frequency below 0.5% remain mostly undetected by current genome-wide off-target detection techniques. Here we report a method to effectively detect extremely small amounts of mutated DNA based on predicted off-target-specific amplification. In this study, we used various genome editors to induce intracellular genome mutations, and the CRISPR amplification method detected off-target mutations at a significantly higher rate (1.6~984 fold increase) than an existing targeted amplicon sequencing method. In the near future, CRISPR amplification in combination with genome-wide off-target detection methods will allow detection of genome editor-induced off-target mutations with high sensitivity and in a non-biased manner.
Understanding direction-dependent friction anisotropy is necessary to optimize interface shear resistance across soil-structure. Previous studies estimated interface frictional anisotropy ...quantitatively using contractive sands. However, no studies have explored how sand with a high dilative tendency around the structural surface affects the interface shear response. In this study, a series of interface direct shear tests are conducted with selected French standard sand and snakeskin-inspired surfaces under three vertical stresses (50, 100, and 200 kPa) and two shearing directions (cranial → caudal or caudal → cranial). First, the sand-sand test observes a higher dilative response, and a significant difference between the peak and residual friction angles (ϕ
- ϕ
= 8°) is obtained at even a lower initial relative density D
= 40%. In addition, the interface test results show that (1) shearing against the scales (cranial shearing) mobilizes a larger shear resistance and produces a dilative response than shearing along the scales (caudal shearing), (2) a higher scale height or shorter scale length exhibits a higher dilative tendency and produces a higher interface friction angle, and (3) the interface anisotropy response is more pronounced during cranial shearing in all cases. Further analysis reveals that the interface friction angle and dilation angle are decreased with the scale geometry ratio (L/H). For L/H values between 16.67 and 60, the interface dilation angle varies between 9° and 4° for cranial first shearing and 3.9°-2.6° for caudal first shearing. However, the difference in dilation angle within the same shearing direction is less than 1°.
Metal halide perovskites have demonstrated strong potential for optoelectronic applications. Particularly, two-dimensional (2D) perovskites have emerged to be promising materials due to their tunable ...properties and superior stability compared to their three-dimensional counterparts. For high device performance, 2D perovskites need a vertical crystallographic orientation with respect to the electrodes to achieve efficient charge transport. However, the vertical orientation is difficult to achieve with various compositions due to a lack of understanding of the thin film nucleation and growth processes. Here we report a general crystallization mechanism for 2D perovskites, where solvent evaporation and crystal growth compete to influence the level of supersaturation and a low supersaturation is necessary to crystallize vertically oriented thin films starting from nucleation at the liquid–air interface. Factors influencing the supersaturation and crystallization dynamics, such as choices of organic spacers, solvents, and solvent drying rate, have a strong influence on the degree of crystallographic orientation. With this understanding of crystallization mechanism, we demonstrate direct crystallization of thin films with strong vertical orientation using three different organic spacers without any additives, and the vertically oriented 2D perovskites result in efficient and stable solar cell operation.
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