Manipulation of ferroic order parameters, namely (anti‐)ferromagnetic, ferroelectric, and ferroelastic, by light at room temperature is a fascinating topic in modern solid‐state physics due to ...potential cross‐fertilization in research fields that are largely decoupled. Here, full optical control, that is, reversible switching, of the ferroelectric/ferroelastic domains in BiFeO3 thin films at room temperature by the mediation of the tip‐enhanced photovoltaic effect is demonstrated. The enhanced short‐circuit photocurrent density at the tip contact area generates a local electric field well exceeding the coercive field, enabling ferroelectric polarization switching. Interestingly, by tailoring the photocurrent direction, via either tuning the illumination geometry or simply rotating the light polarization, full control of the ferroelectric polarization is achieved. The finding offers a new insight into the interactions between light and ferroic orders, enabling fully optical control of all the ferroic orders at room temperature and providing guidance to design novel optoferroic devices for data storage and sensing.
Full optical control of ferroelectric order parameters at room temperature is demonstrated by a combination of the bulk photovoltaic effect and the tip of an atomic force microscope. The ferroelectric polarization of a BiFeO3 thin film can be reversibly switched solely by light via changing illumination areas or simply rotating the light polarization angles.
Described herein is an organocatalytic enantioselective desymmetrizing cycloisomerization of arylsulfonyl‐protected ynamide cyclohexanones, representing the first metal‐free asymmetric Conia‐ene‐type ...carbocyclization. This method allows the highly efficient and atom‐economical construction of a range of valuable morphans with wide substrate scope and excellent enantioselectivity (up to 97 % ee). In addition, such a cycloisomerization of alkylsulfonyl‐protected ynamide cyclohexanones can lead to the divergent synthesis of normorphans as the main products with high enantioselectivity (up to 90 % ee). Moreover, theoretical calculations are employed to elucidate the origins of regioselectivity and enantioselectivity.
An organocatalytic enantioselective desymmetrizing cycloisomerization of arylsulfonyl‐protected ynamide cyclohexanones is disclosed for practical and atom‐economical assembly of morphans with excellent enantioselectivities. It represents the first metal‐free asymmetric Conia‐ene‐type carbocyclization. In addition, cycloisomerization of the alkylsulfonyl‐protected ynamide cyclohexanones leads to normorphans with high enantioselectivities.
Object tracking has been one of the most important and active research areas in the field of computer vision. A large number of tracking algorithms have been proposed in recent years with ...demonstrated success. However, the set of sequences used for evaluation is often not sufficient or is sometimes biased for certain types of algorithms. Many datasets do not have common ground-truth object positions or extents, and this makes comparisons among the reported quantitative results difficult. In addition, the initial conditions or parameters of the evaluated tracking algorithms are not the same, and thus, the quantitative results reported in literature are incomparable or sometimes contradictory. To address these issues, we carry out an extensive evaluation of the state-of-the-art online object-tracking algorithms with various evaluation criteria to understand how these methods perform within the same framework. In this work, we first construct a large dataset with ground-truth object positions and extents for tracking and introduce the sequence attributes for the performance analysis. Second, we integrate most of the publicly available trackers into one code library with uniform input and output formats to facilitate large-scale performance evaluation. Third, we extensively evaluate the performance of 31 algorithms on 100 sequences with different initialization settings. By analyzing the quantitative results, we identify effective approaches for robust tracking and provide potential future research directions in this field.
Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide because of metastasis. Epithelial‐mesenchymal transition (EMT) is widely considered to be crucial to the invasion‐metastasis ...cascade during cancer progression. Actin‐like 6A (ACTL6A) is initially verified important for cell proliferation, differentiation, and migration. In this study, we find that ACTL6A plays an essential role in metastasis and EMT of HCC. ACTL6A expression is up‐regulated in HCC cells and tissues. A high level of ACTL6A in HCCs is correlated with aggressive clinicopathological features and is an independent poor prognostic factor for overall and disease‐free survival of HCC patients. Ectopic expression of ACTL6A markedly promotes HCC cells migration, invasion, as well as EMT in vitro and promotes tumor growth and metastasis in the mouse xenograft model. Opposite results are observed when ACTL6A is knocked down. Mechanistically, ACTL6A promotes metastasis and EMT through activating Notch signaling. ACTL6A knockdown has the equal blockage effect as the Notch signaling inhibitor, N‐N‐(3,5‐difluorophenacetyl)‐L‐alanyl‐S‐phenylglycine t‐butylester, in HCC cells. Further studies indicate that ACTL6A might manipulate SRY (sex determining region Y)‐box 2 (SOX2) expression and then activate Notch1 signaling. Conclusions: ACTL6A promotes metastasis and EMT by SOX2/Notch1 signaling, indicating a prognostic biomarker candidate and a potential therapeutic target for HCC. (Hepatology 2016;63:1256–1271)
Abstract
Presently, liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays are two dominant flat panel display technologies. Recently, inorganic mini-LEDs (mLEDs) and ...micro-LEDs (μLEDs) have emerged by significantly enhancing the dynamic range of LCDs or as sunlight readable emissive displays. “mLED, OLED, or μLED: who wins?” is a heated debatable question. In this review, we conduct a comprehensive analysis on the material properties, device structures, and performance of mLED/μLED/OLED emissive displays and mLED backlit LCDs. We evaluate the power consumption and ambient contrast ratio of each display in depth and systematically compare the motion picture response time, dynamic range, and adaptability to flexible/transparent displays. The pros and cons of mLED, OLED, and μLED displays are analysed, and their future perspectives are discussed.
Rearrangement reactions have attracted considerable interest over the past decades due to their high bond-forming efficiency and atom economy in the construction of complex organic architectures. In ...contrast to the well-established 3,3-rearrangement, 1,3 O-to-C rearrangement has been far less vigorously investigated, and stereospecific 1,3-rearrangement is extremely rare. Here, we report a metal-free intramolecular hydroalkoxylation/1,3-rearrangement, leading to the practical and atom-economical assembly of various valuable medium-sized lactams with wide substrate scope and excellent diastereoselectivity. Moreover, such an asymmetric cascade cyclization has also been realized by chiral Brønsted acid-catalyzed kinetic resolution. In addition, biological tests reveal that some of these medium-sized lactams displayed their bioactivity as antitumor agents against melanoma cells, esophageal cancer cells and breast cancer cells. A mechanistic rationale for the reaction is further supported by control experiments and theoretical calculations.
Deblurring Images via Dark Channel Prior Pan, Jinshan; Sun, Deqing; Pfister, Hanspeter ...
IEEE transactions on pattern analysis and machine intelligence,
10/2018, Letnik:
40, Številka:
10
Journal Article
Recenzirano
Odprti dostop
We present an effective blind image deblurring algorithm based on the dark channel prior. The motivation of this work is an interesting observation that the dark channel of blurred images is less ...sparse. While most patches in a clean image contain some dark pixels, this is not the case when they are averaged with neighboring ones by motion blur. This change in sparsity of the dark channel pixels is an inherent property of the motion blur process, which we prove mathematically and validate using image data. Enforcing sparsity of the dark channel thus helps blind deblurring in various scenarios such as natural, face, text, and low-illumination images. However, imposing sparsity of the dark channel introduces a non-convex non-linear optimization problem. In this work, we introduce a linear approximation to address this issue. Extensive experiments demonstrate that the proposed deblurring algorithm achieves the state-of-the-art results on natural images and performs favorably against methods designed for specific scenarios. In addition, we show that the proposed method can be applied to image dehazing.
It is highly desirable to discover photovoltaic mechanisms that enable enhanced efficiency of solar cells. Here we report that the bulk photovoltaic effect, which is free from the thermodynamic ...Shockley-Queisser limit but usually manifested only in noncentrosymmetric (piezoelectric or ferroelectric) materials, can be realized in any semiconductor, including silicon, by mediation of flexoelectric effect. We used either an atomic force microscope or a micrometer-scale indentation system to introduce strain gradients, thus creating very large photovoltaic currents from centrosymmetric single crystals of strontium titanate, titanium dioxide, and silicon. This strain gradient-induced bulk photovoltaic effect, which we call the flexo-photovoltaic effect, functions in the absence of a p-n junction. This finding may extend present solar cell technologies by boosting the solar energy conversion efficiency from a wide pool of established semiconductors.
Positron emission tomography (PET) imaging is an effective tool used in determining disease stage and lesion malignancy; however, radiation exposure to patients and technicians during PET scans ...continues to draw concern. One way to minimize radiation exposure is to reduce the dose of radioactive tracer administered in order to obtain the scan. Yet, low-dose images are inherently noisy and have poor image quality making them difficult to read. This paper proposes the use of a deep learning model that takes specific image features into account in the loss function to denoise low-dose PET image slices and estimate their full-dose image quality equivalent. Testing on low-dose image slices indicates a significant improvement in image quality that is comparable to the ground truth full–dose image slices. Additionally, this approach can lower the cost of conducting a PET scan since less radioactive material is required per scan, which may promote the usage of PET scans for medical diagnosis.
Electroreduction of carbon dioxide (CO2) into high‐value and readily collectable liquid products is vital but remains a substantial challenge due to the lack of highly efficient and robust ...electrocatalysts. Herein, Bi‐based metal‐organic framework (CAU‐17) derived leafy bismuth nanosheets with a hybrid Bi/BiO interface (Bi NSs) is developed, which enables CO2 reduction to formic acid (HCOOH) with high activity, selectivity, and stability. Specially, the flow cell configuration is employed to eliminate the diffusion effect of CO2 molecules and simultaneously achieve considerable current density (200 mA cm−2) for industrial application. The faradaic efficiency for transforming CO2 to HCOOH can achieve over 85 or 90% in 1 m KHCO3 or KOH for at least 10 h despite a current density that exceeds 200 mA cm−2, outperforming most of the reported CO2 electroreduction catalysts. The hybrid Bi/BiO surface of leafy bismuth nanosheets boosts the adsorption of CO2 and protects the surface structure of the as‐prepared leafy bismuth nanosheets, which benefits its activity and stability for CO2 electroreduction. This work shows that modifying electrocatalysts by surface oxygen groups is a promising pathway to regulate the activity and stability for selective CO2 reduction to HCOOH.
Herein, leafy bismuth nanosheets are shown to achieve CO2 electroreduction to HCOOH with high activity (>200 mA cm−2), selectivity (>90%) and stability (>10 h) by employing in gas diffusion cell configuration. According to the in‐depth characterizations, the large electrochemically accessible surface area and the superficial BiO species for Bi nanosheets are the key factors that enable the high catalytic activity.
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