Flexible Omnidirectional Self-Powered Photodetectors Enabled by Solution-Processed Two-Dimensional Layered PbI2 Nanoplates.

Realizing omnidirectional self-powered photodetectors is central to advancing next-generation portable and smart photodetector systems. However, the traditional omnidirectional photodetector is typically achieved by integrating complex hemispherical microlens on multiple photodetectors, which makes the detection system cumbersome and restricts its application in the portable field. Here, facile and high-performance flexible omnidirectional self-powered photodetectors are achieved by solution-processed two-dimensional (2D) layered PbI2 nanoplates on transparent conducting substrates. Characterization of PbI2 nanoplates microstructural/compositional and their photodetection properties have been systematically characterized. Under the irradiation of a 405 nm laser, the photodetectors exhibit an impressively low dark current of 10-13 A, a high light on/off ratio up to 106, and a fast rise/decay response time of 2/3 ms. Importantly, when light irradiates the photodetector at 5°, it can still maintain high photodetection properties, realizing almost 360° omnidirectional self-powered photodetection. What is more, these self-powered photodetectors exhibit robust omnidirectional photoresponse stability of flexibility even after bending for 1200 cycles. Thus, this work broadens the applicability of 2D layered nanoplates for further extending its applications in advanced optoelectronic devices.

Schottky-Contacted High-Performance GaSb Nanowires Photodetectors Enabled by Lead-Free All-Inorganic Perovskites Decoration.

The surface Fermi level pinning effect promotes the formation of metal-independent Ohmic contacts for the high-speed GaSb nanowires (NWs) electronic devices, however, it limits next-generation optoelectronic devices. In this work, lead-free all-inorganic perovskites with broad bandgaps and low work functions are adopted to decorate the surfaces of GaSb NWs, demonstrating the success in the construction of Schottky-contacts by surface engineering. Benefiting from the expected Schottky barrier, the dark current is reduced to 2 pA, the Ilight /Idark ratio is improved to 103 and the response time is reduced by more than 15 times. Furthermore, a Schottky-contacted parallel array GaSb NWs photodetector is also fabricated by the contact printing technology, showing a higher photocurrent and a low dark current of 15 pA, along with the good infrared photodetection ability for a concealed target. All results guide the construction of Schottky-contacts by surface decorations for next-generation high-performance III-V NWs optoelectronics devices.

Polarization enlargement of FOV in Super Multi-view display based on near-eye timing-apertures.

With strip-type timing-apertures attached to each eye of a viewer, more than one perspective views can be guided to either eye sequentially through different timing-apertures, thus implementing VAC-free (vergence-accommodation conflict-free) SMV (Super Multi-view) 3D (three-dimensional) display. To overcome the FOV (field of view) limitation problem due to small size of the timing-apertures along their arrangement direction, novel polarization architectures are designed to the timing-apertures in this paper. Correspondingly, the display screen of the proposed SMV display system is divided into M > 1 sub-screens along the arrangement direction of the timing-apertures, with adjacent sub-screens emitting light of mutually orthogonal polarization. At a time-point of each time period, a group of M timing-apertures, which correspond to the M sub-screens in a one-by-one manner along the arrangement direction, are turned on for creating an M-fold FOV, with each polarized timing-aperture of the group allowing light from the corresponding sub-screen passing through and blocking light from sub-screen(s) adjacent to the corresponding sub-screen. At 2T > 1 time-points of each time period, 2T groups of timing-apertures are turned on sequentially for presenting more than one two-dimensional images of the displayed scene to each eye, to implement SMV display based on persistence of vision. M stands for the FOV magnification number and T stands for the two-dimensional image number for each eye. As proof, a 3-fold FOV of 41° gets implemented experimentally with a currently available timing-aperture array of M = 3, accompanied by an effective noise-free region (ENFR) of 8.34 mm. Furthermore, the promising of freeing FOV from timing-aperture constraint fundamentally by larger M is described, out-of-screen blur along strip direction of the timing-apertures and the problem of limited ENFR are discussed.

Toward Unusual-High Hole Mobility of p-Channel Field-Effect-Transistors.

The relative low hole mobility of p-channel building block device challenges the continued miniaturization of modern electronic chips. Metal-semiconductor junction is always an efficient strategy to control the carrier concentration of channel semiconductor, benefiting the carrier mobility regulation of building block device. In this work, complementary metal oxide semiconductor (CMOS)-compatible metals are selected to deposit on the surface of the important p-channel building block of GaSb nanowire field-effect-transistors (NWFETs), demonstrating the efficient strategy of hole mobility enhancement by metal-semiconductor junction. When deposited with lower work function metal of Al, the peak hole mobility of GaSb NWFET can be enhanced to as high as ≈3372 cm2 V-1 s-1 , showing three times than the un-deposited one. The as-studied metal-semiconductor junction is also efficient for the hole mobility enhancement of other p-channel devices, such as GaAs NWFET, GaAs film FET, and WSe2 FET. With the enhanced mobility, the as-constructed CMOS inverter shows good invert characteristics, showing a relatively high gain of ≈18.1. All results may be regarded as important advances to the next-generation electronics.

Lung Cancer and Granuloma Identification Using a Deep Learning Model to Extract 3-Dimensional Radiomics Features in CT Imaging.

BACKGROUND: We aimed to evaluate a deep learning (DL) model combining perinodular and intranodular radiomics features and clinical features for preoperative differentiation of solitary granuloma nodules (GNs) from solid lung cancer nodules in patients with spiculation, lobulation, or pleural indentation on CT. PATIENTS AND METHODS: We retrospectively recruited 915 patients with solitary solid pulmonary nodules and suspicious signs of malignancy. Data including clinical characteristics and subjective CT findings were obtained. A 3-dimensional U-Net-based DL model was used for tumor segmentation and extraction of 3-dimensional radiomics features. We used the Maximum Relevance and Minimum Redundancy (mRMR) algorithm and the eXtreme Gradient Boosting (XGBoost) algorithm to select the intranodular, perinodular, and gross nodular radiomics features. We propose a medical image DL (IDL) model, a clinical image DL (CIDL) model, a radiomics DL (RDL) model, and a clinical image radiomics DL (CIRDL) model to preoperatively differentiate GNs from solid lung cancer. Five-fold cross-validation was used to select and evaluate the models. The prediction performance of the models was evaluated using receiver operating characteristic and calibration curves. RESULTS: The CIRDL model achieved the best performance in differentiating between GNs and solid lung cancer (area under the curve [AUC] = 0.9069), which was significantly higher compared with the IDL (AUC = 0.8322), CIDL (AUC = 0.8652), intra-RDL (AUC = 0.8583), peri-RDL (AUC = 0.8259), and gross-RDL (AUC = 0.8705) models. CONCLUSION: The proposed CIRDL model is a noninvasive diagnostic tool to differentiate between granuloma nodules and solid lung cancer nodules and reduce the need for invasive diagnostic and surgical procedures.

Ambipolar transport in Ni-catalyzed InGaAs nanowire field-effect transistors for near-infrared photodetection.

Weak n-type characteristics or poor p-type characteristics are limiting the applications of binary semiconductors based on ambipolar field-effect transistors (FETs). In this work, a ternary alloy of In0.2Ga0.8As nanowires (NWs) is successfully prepared using a Ni catalyst during a typical solid-source chemical-vapor-deposition process to balance the weak n-type conduction behavior in ambipolar GaAs NWFETs and the poor p-type conduction behavior in ambipolar InAs NWFETs. The presence of ambipolar transport, contributed by a native oxide shell and the body defects of the prepared In0.2Ga0.8As NWs, is confirmed by the constructed back-gated NWFETs. As demonstrated by photoluminescence, the bandgap of the prepared In0.2Ga0.8As NWs is 1.28 eV, offering the promise of application in near-infrared (NIR) photodetection. Under 850 nm laser illumination, the fabricated ambipolar NWFETs show extremely low dark currents of 50 pA and 0.5 pA when positive and negative gate voltages are applied, respectively. All the results demonstrate that with careful design of the surface oxide layer and the body defects, NWs are suitable for use in next-generation optoelectronic devices.

Deep Convolutional Neural Networks-Based Automatic Breast Segmentation and Mass Detection in DCE-MRI.

Breast segmentation and mass detection in medical images are important for diagnosis and treatment follow-up. Automation of these challenging tasks can assist radiologists by reducing the high manual workload of breast cancer analysis. In this paper, deep convolutional neural networks (DCNN) were employed for breast segmentation and mass detection in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). First, the region of the breasts was segmented from the remaining body parts by building a fully convolutional neural network based on U-Net++. Using the method of deep learning to extract the target area can help to reduce the interference external to the breast. Second, a faster region with convolutional neural network (Faster RCNN) was used for mass detection on segmented breast images. The dataset of DCE-MRI used in this study was obtained from 75 patients, and a 5-fold cross validation method was adopted. The statistical analysis of breast region segmentation was carried out by computing the Dice similarity coefficient (DSC), Jaccard coefficient, and segmentation sensitivity. For validation of breast mass detection, the sensitivity with the number of false positives per case was computed and analyzed. The Dice and Jaccard coefficients and the segmentation sensitivity value for breast region segmentation were 0.951, 0.908, and 0.948, respectively, which were better than those of the original U-Net algorithm, and the average sensitivity for mass detection achieved 0.874 with 3.4 false positives per case.

Retraction of "Solid-to-Solid Crystallization of Organic Thin Films: Classical and Nonclassical Pathways".

[This retracts the article DOI: 10.1021/acsomega.8b00153.].

Trait-Based Climate Change Predictions of Vegetation Sensitivity and Distribution in China.

Dynamic global vegetation models (DGVMs) suffer insufficiencies in tracking biochemical cycles and ecosystem fluxes. One important reason for these insufficiencies is that DGVMs use fixed parameters (mostly traits) to distinguish attributes and functions of plant functional types (PFTs); however, these traits vary under different climatic conditions. Therefore, it is urgent to quantify trait covariations, including those among specific leaf area (SLA), area-based leaf nitrogen (N area), and leaf area index (LAI) (in 580 species across 218 sites in this study), and explore new classification methods that can be applied to model vegetation dynamics under future climate change scenarios. We use a redundancy analysis (RDA) to derive trait-climate relationships and employ a Gaussian mixture model (GMM) to project vegetation distributions under different climate scenarios. The results show that (1) the three climatic variables, mean annual temperature (MAT), mean annual precipitation (MAP), and monthly photosynthetically active radiation (mPAR) could capture 65% of the covariations of three functional traits; (2) tropical, subtropical and temperate forest complexes expand while boreal forest, temperate steppe, temperate scrub and tundra shrink under future climate change scenarios; and (3) the GMM classification based on trait covariations should be a powerful candidate for building new generation of DGVM, especially predicting the response of vegetation to future climate changes. This study provides a promising route toward developing reliable, robust and realistic vegetation models and can address a series of limitations in current models.

Solid-to-Solid Crystallization of Organic Thin Films: Classical and Nonclassical Pathways.

The solid-to-solid crystallization processes of organic molecules have been poorly understood in view of the complexity and the instability of organic crystals. Here, we studied the crystallization of a π-conjugated small molecular semiconductor, bis-(8-hydroxyquinoline) copper (CuQ2), by annealing the thin films at different temperatures. We observed a classical film-to-nanorods crystallization at 80 °C, a coexistence of classical and nonclassical nucleation and particle growth at 120 °C, and a nonclassical crystal growth at 150 °C. We found that the growth of the crystals followed the following processes: particle nucleation, particle growth, particle migration, nondirectional particle attachment, and structure reconstruction. We notice that the growth of CuQ2 particles follows an outside-to-inside process. More interestingly, our experiments suggest that the submicron CuQ2 particles are able to migrate dozens of micrometers at 150 °C.

Angiopep-2-conjugated poly(ethylene glycol)-co- poly(ε-caprolactone) polymersomes for dual-targeting drug delivery to glioma in rats.

The blood-brain barrier is a formidable obstacle for glioma chemotherapy due to its compact structure and drug efflux ability. In this study, a dual-targeting drug delivery system involving Angiopep-2-conjugated biodegradable polymersomes loaded with doxorubicin (Ang-PS-DOX) was developed to exploit transport by the low-density lipoprotein receptor-related protein 1 (LRP1), which is overexpressed in both blood-brain barrier and glioma cells. The polymersomes (PS) were prepared using a thin-film hydration method. The PS were loaded with doxorubicin using the pH gradient method (Ang-PS-DOX). The resulting PS were uniformly spherical, with diameters of ~135 nm and with ~159.9 Angiopep-2 molecules on the surface of each PS. The drug-loading capacity and the encapsulation efficiency for doxorubicin were 7.94%±0.17% and 95.0%±1.6%, respectively. Permeability tests demonstrated that the proton diffusion coefficient across the PS membrane was far slower than that across the liposome membrane, and the common logarithm value was linearly dependent on the dioxane content in the external phase. Compared with PS-DOX, Ang-PS-DOX demonstrated significantly higher cellular uptake and stronger cytotoxicity in C6 cells. In vivo pharmacokinetics and brain distribution experiments revealed that Ang-PS-DOX achieved a more extensive distribution and more abundant accumulation in glioma cells than PS-DOX. Moreover, the survival time of glioma-bearing rats treated with Ang-PS-DOX was significantly prolonged compared with those treated with PS-DOX or a solution of free doxorubicin. These results suggested that Ang-PS-DOX can target glioma cells and enhance chemotherapeutic efficacy.

Super multi-view three-dimensional display technique for portable devices.

Portable display devices, such as intelligent telephones and panel PCs, have become parts of modern people's daily life. Their mainstream display interfaces are based on two-dimensional (2D) images. Although some three-dimensional (3D) technologies have been proposed for portable devices, comfortable visual effects are untouched until now. A super multi-view (SMV) system with comfortable 3D effects, constructed by a group of OLED microdisplay/projecting lens pairs, is proposed in this paper. Through gating different segments of each projecting lens sequentially and refreshing the virtual image of the corresponding microdisplay synchronously, the proposed SMV system greatly decreases the demand on the number of employed microdisplays and at the same time takes a thin optical structure, endowing great potential for portable devices.

Robust Eye Center Localization through Face Alignment and Invariant Isocentric Patterns.

The localization of eye centers is a very useful cue for numerous applications like face recognition, facial expression recognition, and the early screening of neurological pathologies. Several methods relying on available light for accurate eye-center localization have been exploited. However, despite the considerable improvements that eye-center localization systems have undergone in recent years, only few of these developments deal with the challenges posed by the profile (non-frontal face). In this paper, we first use the explicit shape regression method to obtain the rough location of the eye centers. Because this method extracts global information from the human face, it is robust against any changes in the eye region. We exploit this robustness and utilize it as a constraint. To locate the eye centers accurately, we employ isophote curvature features, the accuracy of which has been demonstrated in a previous study. By applying these features, we obtain a series of eye-center locations which are candidates for the actual position of the eye-center. Among these locations, the estimated locations which minimize the reconstruction error between the two methods mentioned above are taken as the closest approximation for the eye centers locations. Therefore, we combine explicit shape regression and isophote curvature feature analysis to achieve robustness and accuracy, respectively. In practical experiments, we use BioID and FERET datasets to test our approach to obtaining an accurate eye-center location while retaining robustness against changes in scale and pose. In addition, we apply our method to non-frontal faces to test its robustness and accuracy, which are essential in gaze estimation but have seldom been mentioned in previous works. Through extensive experimentation, we show that the proposed method can achieve a significant improvement in accuracy and robustness over state-of-the-art techniques, with our method ranking second in terms of accuracy. According to our implementation on a PC with a Xeon 2.5Ghz CPU, the frame rate of the eye tracking process can achieve 38 Hz.

Improved spatiotemporal-multiplexing super-multiview display based on planar aligned OLED microdisplays.

Through gating spectrum plane of multiple planar aligned OLED microdisplays by a timely sequential manner, a super-multiview (SMV) three-dimensional (3D) display based on spatiotemporal-multiplexing was developed in our previous paper. But an upper limit of the allowable sub-viewing-zones (SVZs) for an OLED microdisplay did exist in the previous system, even if microdisplays with very high frame rates could be commercially available. In this manuscript, an improved spatiotemporal-multiplexing SMV displays system is developed, which removes the above limitation through controllable fusing of light beams from adjacent OLED microdisplays. The employment of a liquid-crystal panel as the gating-aperture array allows the improved system to accommodate multiple rows of OLED microdisplays for denser SVZs. Experimentally, a prototype system is demonstrated by 24 OLED microdisplays, resulting in 120 SVZs with an interval small to 1.07mm.

A computer-aided diagnosis system for dynamic contrast-enhanced MR images based on level set segmentation and ReliefF feature selection.

This study established a fully automated computer-aided diagnosis (CAD) system for the classification of malignant and benign masses via breast magnetic resonance imaging (BMRI). A breast segmentation method consisting of a preprocessing step to identify the air-breast interfacing boundary and curve fitting for chest wall line (CWL) segmentation was included in the proposed CAD system. The Chan-Vese (CV) model level set (LS) segmentation method was adopted to segment breast mass and demonstrated sufficiently good segmentation performance. The support vector machine (SVM) classifier with ReliefF feature selection was used to merge the extracted morphological and texture features into a classification score. The accuracy, sensitivity, and specificity measurements for the leave-half-case-out resampling method were 92.3%, 98.2%, and 76.2%, respectively. For the leave-one-case-out resampling method, the measurements were 90.0%, 98.7%, and 73.8%, respectively.

Phase-sensitive Bloch surface wave sensor based on variable angle spectroscopic ellipsometry.

In this paper, we propose a phase-sensitive Bloch surface wave sensor based on the variable angle spectroscopic ellipsometry and numerically simulate the phase behavior of the sensor. The simulation results show that the dependence of resonant phase is step-like when BSWs are excited. In contrast to the reflectance behavior, even though losses of the dielectric layers are very small, the resonance dip in the reflectivity will be shallow while the step-like change of the reflection phase of the BSW still be remarkable. This means that phase detection is an alternative to reflectivity intensity detection for the sensing applications of the BSWs in this case. Our experimental results indicate that phase detection for the BSW sensors has the potential to achieve the higher sensitivity and the lower limit of detection.

Effects of hepatitis B immunization on prevention of mother-to-infant transmission of hepatitis B virus and on the immune response of infants towards hepatitis B vaccine.

BACKGROUND: Combined immunization with hepatitis B immunoglobulin (HBIG) plus hepatitis B vaccine (HB vaccine) can effectively prevent perinatal transmission of hepatitis B virus (HBV). With the universal administration of HB vaccine, anti-HBs conferred by HB vaccine can be found increasingly in pregnant women, and maternal anti-HBs can be passed through the placenta. This study was designed to evaluate the effect of hepatitis B immunization on preventing mother-to-infant transmission of HBV and on the immune response of infants towards HB vaccine. METHOD: From 2008 to 2013, a prospective study was conducted in 15 centers in China. HBsAg-positive pregnant women and their infants aged 8-12 months who completed immunoprophylaxis were enrolled in the study and tested for HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc). Antepartum administration of HBIG to HBsAg-positive women was based on individual preference. HBsAg-negative pregnant women and their infants of 7-24 months old who received HB vaccines series were enrolled and tests of their HBV markers were performed. RESULTS: 1202 HBsAg-positive mothers and their infants aged 8-12 months were studied and 40 infants were found to be HBsAg positive with the immunoprophylaxis failure rate of 3.3%. Infants with immunoprophylaxis failure were all born to HBeAg-positive mothers of HBV-DNA ≥6 log10copies/ml. Among infants of HBeAg-positive mothers, immunoprophylaxis failure rate in vaccine plus HBIG group, 7.9% (29/367), was significantly lower than the vaccine-only group, 16.9% (11/65), p=0.021; there was no significant difference in the immunoprophylaxis failure rate whether or not antepartum HBIG was given to the pregnant woman, 10.3% (10/97) vs 9.0% (30/335), p=0.685. Anti-HBs positive rate was 56.3% (3883/6899) among HBsAg-negative pregnant women and anti-HBs positive rate was 94.2% in cord blood of anti-HBs-positive mothers. After completing the HB vaccine series, anti-HBs positive rate among infants with maternal anti-HBs titers of <10 IU/L, 10-500 IU/L and ≥500 IU/L was 90.3% (168/186), 90.5% (219/242) and 80.2% (89/111) respectively, p=0.011. Median titers of anti-HBs (IU/L) among infants in the three groups was 344.2, 231.9 and 161.1 respectively, p=0.020. CONCLUSIONS: HBIG plus HB vaccine can effectively prevent mother-to-infant transmission of HBV, but no HBV breakthrough infection was observed in infants born to HBeAg-negative mothers who received HB vaccine with or without HBIG after birth. Antepartum injection of HBIG has no effect on preventing HBV mother-to-infant transmission. High maternal titer of anti-HBs can transplacentally impair immune response of infants towards HB vaccine.

Spatiotemporal multiplexing for holographic display with multiple planar aligned spatial-light-modulators.

A holographic display system combining the spatial- and time-multiplexing together in one system is proposed. The system is constructed by multiple planar aligned spatial-light-modulators (SLMs). A shiftable cylindrical lens is introduced in to build up an "equivalent SLM" by seamlessly linked horizontal images of the SLMs, which are tiled in a time-sequential manner. The proposed system can realize wide horizontal-viewing-angle holographic three-dimensional (3D) display through the "equivalent SLM", but bear with low requirements on the number and frame rate of SLMs, and the numerical aperture of the optical system. In the proposed system, only one parallel incident beam is needed, leading to a simplified optical structure. Using two 60Hz phase SLMs, a 3D display with a horizontal viewing angle (VA) of 27.5° is implemented experimentally.

Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.