A polarization-sensitive, high on/off ratio and self-powered photodetector based on Nb2CTxand Nd2CTx@MoS2.

MXene two-dimensional materials have been widely used in energy storage, catalysis, sensing and other fields, Nb2C as a typical two-dimensional MXene material, its exploration in the field of optoelectronics is still in its infancy, especially Nb2C-based photodetectors are still to be developed. This paper demonstrates that two-dimensional films based on few-layer Nb2C have a photoelectric response in the wavelength range from visible to near-infrared. We have found that the light response performance can be easily adjusted by controlling the thickness of the spin-coated film, and that Nb2C photodetectors show great advantages in terms of wide bandwidth, polarization response, high switching ratio, etc. By adjusting the material concentration and sample thickness, the photocurrent can reach up to 330 nA, the switching ratio can reach 410, and the responsivity can reach 8.3 × 10-4A W-1. In the polarization characteristic test, an extinction ratio of 7.6 can be obtained. By adjusting the content of that doped MoS2quantum dot, the dark current can reach 7.6 × 10-13A, and the switching ratio can reach 3 × 105, which can be increased by 700 times. The above results show that the few-layer Nb2C nanosheets can be used as optoelectronic detectors in the visible to near-infrared bands, which further broadens the application prospects of two-dimensional MXene.

A TiSe monolayer as a superior anode for applications of Li/Na/K-ion batteries.

Using density functional theory (DFT), we investigated the energy-storage capabilities of a two-dimensional TiSe monolayer for applications of the anode material of Li/Na/K-ion batteries. The TiSe monolayer showed high thermodynamic stability at 800 K according to ab initio molecular dynamics (AIMD) simulation. The ion-diffusion barrier was estimated to be 0.29/0.36/0.33 eV for Li/Na/K, respectively, indicating the high-rate capacity of this material. The theoretical specific capacity was 422.63 mA h g-1 for Li/Na/K, with an energy density of 1000.19, 802.30, and 802.41 mW h g-1, respectively. Fully charged TiSe was mechanically stable according to the calculated elastic constants. Our results show that the TiSe monolayer could be used as an excellent anode material for Li/Na/K-ion batteries.

Harnessing heterogeneity in space with statistically guided meta-learning.

Spatial data are ubiquitous, massively collected, and widely used to support critical decision-making in many societal domains, including public health (e.g., COVID-19 pandemic control), agricultural crop monitoring, transportation, etc. While recent advances in machine learning and deep learning offer new promising ways to mine such rich datasets (e.g., satellite imagery, COVID statistics), spatial heterogeneity-an intrinsic characteristic embedded in spatial data-poses a major challenge as data distributions or generative processes often vary across space at different scales, with their spatial extents unknown. Recent studies (e.g., SVANN, spatial ensemble) targeting this difficult problem either require a known space-partitioning as the input, or can only support very limited number of partitions or classes (e.g., two) due to the decrease in training data size and the complexity of analysis. To address these limitations, we propose a model-agnostic framework to automatically transform a deep learning model into a spatial-heterogeneity-aware architecture, where the learning of arbitrary space partitionings is guided by a learning-engaged generalization of multivariate scan statistic and parameters are shared based on spatial relationships. Moreover, we propose a spatial moderator to generalize learned space partitionings to new test regions. Finally, we extend the framework by integrating meta-learning-based training strategies into both spatial transformation and moderation to enhance knowledge sharing and adaptation among different processes. Experiment results on real-world datasets show that the framework can effectively capture flexibly shaped heterogeneous footprints and substantially improve prediction performances.

Oncological results in women with wound complications following mastectomy and immediate breast reconstruction: A meta-analysis.

We performed a meta-analysis to evaluate the oncological results in women with wound complications following mastectomy and immediate breast reconstruction. A systematic literature search up to August 2022 was performed and 1618 subjects with mastectomy and immediate breast reconstruction at the baseline of the studies; 443 of them were with wound complications, and 1175 were with no wound complications as a control. Odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were calculated to assess the oncological results in women with wound complications following mastectomy and immediate breast reconstruction using dichotomous or contentious methods with a random or fixed-effect model. The wound complications had a significantly longer length of time to adjuvant therapy (MD, 9.44; 95% CI, 4.07-14.82, P < .001) compared with no wound complications in subjects with mastectomy and immediate breast reconstruction. However, no significant difference was found between wound complications and no wound complications in subjects with mastectomy and immediate breast reconstruction in breast cancer recurrence (OR, 1.96; 95% CI, 0.95-4.06, P = .07), death rates (OR, 1.95; 95% CI, 0.89-4.27, P = .09), and kind of immediate breast reconstruction (OR, 1.01; 95% CI, 0.53-1.92, P = .98). The wound complications had a significantly longer length of time to adjuvant, however, no significant difference was found in breast cancer recurrence, death rates, and kind of immediate breast reconstruction. The analysis of outcomes should be done with caution even though no low sample size was found in the meta-analysis but a low number of studies was found in certain comparisons.

Non-equilibrium spin-transport properties of Co/phosphorene/Co MTJ with non-collinear electrodes under mechanical bending.

Monolayer phosphorene has outstanding mechanical flexibility, making it rather attractive in flexible spintronics that are based on 2D materials. Here, we report a first-principles study on non-equilibrium electronic-transport properties of the Co/phosphorene/Co magnetic tunnel junction (MTJ) with two α-Co electrodes. The magnetic moments of the two electrodes are considered in the parallel configuration (PC) and the anti-parallel configuration (APC). The tunneling current through the MTJ is investigated at a small bias from 0 to 40 mV when mechanical bending is applied on the MTJ with different central angle (θ) values. For both the PC and APC, the tunneling current increases evidently and monotonously with increasing mechanical bending for 25° < θ < 40°, as compared to that without bending, which is mainly due to the reduced tunnel barrier. In the PC, the spin-injection efficiency (SIE) of the current is largely increased at a small bias from 0 to 40 mV for 25° ≤ θ ≤ 30° with a maximum of 90%, while the SIE is overall increased under all mechanical bending angles for the APC. The tunnel magnetoresistance is decreased with an increasing bias voltage, which can be largely enhanced for θ ≥ 25°, especially at small bias. Our results indicate that the Co/phosphorene/Co MTJ has promising applications in flexible low-power spintronic devices.

Development and validation of an extended Cox prognostic model for patients with ER/PR+ and HER2- breast cancer: a retrospective cohort study.

BACKGROUND: The purpose of this study was to explore a new estrogen receptor (ER) and/or progesterone receptor (PR)+ and human epidermal growth factor receptor 2 (HER2)- breast cancer prognostic model, called the extended Cox prognostic model, for determining the cutoff values for multiple continuous prognostic factors and their interaction via the new model concept and variable selection method. METHODS: A total of 335 patients with ER/PR+ and HER2- breast cancer were enrolled for the final analysis. The primary endpoint was breast cancer-specific mortality (BCSM). Prognostic factors (histological grade, histological type, stage, T, N, lymphovascular invasion (LVI), P53, Ki67, ER, PR, and age) were included in this study. The four continuous variables (Ki67, ER, PR, and age) were partitioned into a series of binary variables that were fitted in the multivariate Cox analysis. A smoothly clipped absolute deviation (SCAD) variable selection method was used. Model performance was expressed in discrimination and calibration. RESULTS: We developed an extended Cox model with a time threshold of 164-week (more than 3 years) postoperation and developed a user-friendly nomogram based on our extended Cox model to facilitate clinical application. We found that the cutoff values for PR, Ki67, and age were 20%, 60%, and 41-55 years, respectively. There was an interaction between age and PR for patients aged ≥ 41 years and PR ≥ 20% at 164-week postoperation: the older the patients with ER/PR+, HER2-, and PR ≥ 20% were, the lower the survival and more likely to recur and metastasize exceeding 164 weeks (more than 3 years) after surgery. CONCLUSIONS: Our study offers guidance on the prognosis of patients with ER/PR+ and HER2- breast cancer in China. The new concept can inform modeling and the determination of cutoff values of prognostic factors in the future.

Outstanding spin-transport properties of a flexible phosphorene photodetector driven by the photogalvanic effect under mechanical strains.

Monolayer phosphorene has outstanding spintronic properties including a nanosecond spin lifetime, and micrometer spin relaxation length, combined with excellent mechanical flexibility, making it rather attractive in low-dimensional flexible spintronic devices. However, knowledge on the spin-transport properties of phosphorene under mechanical strain is currently very limited. Here, we study the transport properties of the spin-polarized photocurrent in the flexible Ni-phosphorene-Ni photodetector, which is driven by the photogalvanic effect (PGE) under mechanical tension stress and bending. Broadband PGE photocurrent is generated at zero bias under the illumination of linearly polarized light due to the broken inversion symmetry of the photodetector. Remarkable spin-transport performances including the fully spin-polarized photocurrent, perfect spin-valve effect, and enhanced pure spin current are generated in a broad visible range by applying appropriate mechanical tension stress or bending. Our results indicate that the PGE-driven phosphorene-based photodetector has promising applications in flexible and low-power spintronic devices.

The strain effect on the electronic properties of the MoSSe/WSSe van der Waals heterostructure: a first-principles study.

The structural, mechanical and electronic properties of the MoSSe/WSSe van der Waals (vdW) heterostructure under various degrees of horizontal and vertical strain are systematically investigated based on first-principles methods. It is found that the MoSSe/WSSe vdW heterostructure of the most stable AB stacking is a direct band gap semiconductor and exhibits a type-II band alignment, which demonstrates an effective separation of photogenerated electron-hole pairs and increases their lifetime accordingly. The high angle-dependent Young's modulus and normal Poisson's ratios show the mechanical stability and anisotropy. It is found that the band gap of the heterostructure can be modulated effectively by applying strain, exhibiting a decreasing trend with increasing strain, and even lead to an intriguing semiconductor-metal transition under a certain large tensile strain. In particular, a negative correlation between the band gap and structure pressure provides a theoretical basis for experimentally regulating the electronic properties. Moreover, different strains can induce two different conditions of direct-indirect transition or can maintain the characteristics of the direct-band-gap. All these interesting results provide a detailed understanding of the MoSSe/WSSe vdW heterostructure under strain and indicate that it is a good candidate for low-dimensional electronic, nano-electronic and optoelectronic devices.

A self-powered phosphorene photodetector with excellent spin-filtering and spin-valve effects.

Spin-filtering and spin-valve effects are fundamental issues of spintronics in two-dimensional materials, where a self-powered nanotechnology is also highly desired for low-power consumption. Herein, we report a self-powered nickel-phosphorene-nickel photodetector driven by photogalvanic effects (PGEs), based on quantum transport simulations. Persistent photocurrent is generated at zero bias due to PGEs induced by vertical illumination with linearly and elliptically polarized light. Moreover, fully spin-polarized photocurrent and large magnetoresistance can be obtained by tunneling the photon energy and light polarization, which indicates both excellent spin-filtering and spin-valve effects. These results suggest a promising application of PGE-driven phosphorene photodetectors in low energy-consumption spintronic devices.

Remarkable negative differential resistance and perfect spin-filtering effects of the indium triphosphide (InP3) monolayer tuned by electric and optical ways.

Fully spin-polarized current and negative differential resistance (NDR) are two important electronic transport properties for spintronic nanodevices based on two-dimensional materials. Here, we describe both the electric and optical tuning of the spin-polarized electronic transport properties of the indium triphosphide (InP3) monolayer, which is doped with Ge atoms, by using quantum transport calculations. The spin degeneration of the InP3 monolayer is lifted due to the doping of Ge atoms. By applying a small bias voltage, a fully spin-polarized current can be obtained along both the armchair and zigzag directions. Moreover, a remarkable NDR is observed for the current along the zigzag direction, which shows a huge peak-to-valley ratio of 3.1 × 103, while in the armchair direction, a lower peak-to-valley ratio of 5.5 is obtained. Alternatively, a fully spin-polarized photocurrent can also be generated under the illumination of linearly-polarized light by tuning either the photon energy or the polarization angle.

Nonequilibrium spin injection in monolayer black phosphorus.

Monolayer black phosphorus (MBP) is an interesting emerging electronic material with a direct band gap and relatively high carrier mobility. In this work we report a theoretical investigation of nonequilibrium spin injection and spin-polarized quantum transport in MBP from ferromagnetic Ni contacts, in two-dimensional magnetic tunneling structures. We investigate physical properties such as the spin injection efficiency, the tunnel magnetoresistance ratio, spin-polarized currents, charge currents and transmission coefficients as a function of external bias voltage, for two different device contact structures where MBP is contacted by Ni(111) and by Ni(100). While both structures are predicted to give respectable spin-polarized quantum transport, the Ni(100)/MBP/Ni(100) trilayer has the superior properties where the spin injection and magnetoresistance ratio maintains almost a constant value against the bias voltage. The nonequilibrium quantum transport phenomenon is understood by analyzing the transmission spectrum at nonequilibrium.

Photogalvanic effect in monolayer black phosphorus.

We report a first-principles theoretical approach for analyzing linear and circular photogalvanic effects (PGEs) based on density functional theory within the nonequilibrium Green's function formalism. Using this approach we investigate the PGE phenomena in monolayer black phosphorus (MBP) doped with sulfur atoms. The impurity doping breaks the space inversion symmetry of pristine MBP, leading to a C s symmetry with a mirror reflection plane normal to the zigzag direction of the MBP lattice. Governed by this symmetry, a linear PGE is induced in both zigzag and armchair directions, and a circular PGE is induced along the zigzag direction. A robust broadband photoresponse is found from the near-infrared to the visible range for the MBP device. There is a strong anisotropy in PGE: photoresponse in the zigzag direction can be larger by an order of magnitude than that in the armchair direction. We identify the origin of the observed PGE as the inter-band transitions from the impurity and valence bands to the conduction bands, which involves a transfer of angular momentum from photons to electrons.

Melting of icosahedral nickel clusters under hydrostatic pressure.

The thermal stabilities and melting behavior of icosahedral nickel clusters under hydrostatic pressure have been studied by constant-pressure molecular dynamics simulation. The potential energy and Lindemann index are calculated. The overall melting temperature exhibits a strong dependence on pressure. The Lindemann index of solid structure before melting varies slowly and is almost independent of pressure. However, after the clusters melt completely, the Lindemann index at the overall melting point strongly depends on pressure. The overall melting temperature is found to be increasing nonlinearly with increasing pressure, while the volume change during melting decreases linearly with increasing pressure. Under a high pressure and temperature environment, similar angular distributions were found between liquid and solid structures, indicating the existence of a converging local structure.

[Effect of Aß1-42 injection on hippocampus cells in rats and protective role of polygona-polysaccharose for Alzheimer's disease].

OBJECTIVE: To determine the effect of polygona-polysaccharose (PP) on learning and memory ability in rats with Alzheimer's disease (AD). METHODS: Forty five Sprague-Dawley rats were assigned into 3 groups. Rats in the sham-operated group were injected with normal saline. Rats in the Aß group were injected with Aß1-42. Rats in the PP group were injected with 16% PP solution for 45 days consecutively. The Morris water maze was used to investigate the ability of learning and memory in the rats. The effect of Aß and PP on the hippocampus cells was observed by HE and Congo red staining of methanol. RESULTS: Rats in the sham-operated group had no obvious morphological change; and morphology of rats in the PP group was basicaly normal. The layer of pyramidal cells in the Aß group was decreased. The cells appeared sparse and irregular and became smaller. Karyopyknosis and vacuolar degeneration cells were also found. More positive staining materials aggradated in the Aß group compared with the PP group by Congo red staining (P<0.05). CONCLUSION: Aß infusion into the hippocampus results in the impairment of the neuronal degeneration in the rats, which shows similar characterizations of AD. PP can reduce the deposition of Aß in the hippocampus.

Ankle brachial index is a valuable index of the severity of atherosclerotic renal artery stenosis.

OBJECTIVE: The objective of this study was to investigate the relationship between the ankle brachial index (ABI) and the severity of atherosclerotic renal artery stenosis (ARAS). MATERIAL AND METHODS: In total, 138 patients with a complete clinical record were enrolled in this study. The severity of ARAS was judged by renal artery angiography and the ABI was measured according to the method recommended by the American Heart Association. RESULTS: Hypertension, coronary artery disease, chronic renal dysfunction and hyperlipidaemia were significantly increased in the ARAS group (p < 0.05 or 0.01), and the ARAS patients were significantly older than the non-ARAS patients (p < 0.05). There were 31 cases of mild renal artery stenosis, 26 of midrange stenosis, 14 of severe stenosis and 16 of bilateral stenosis. In total, 104 cases had a normal ABI, while 34 cases had an abnormal ABI (≤0.9). Abnormal ABI values were not significantly correlated with mild ARAS, but the abnormal ABI value in patients with midrange and severe ARAS was approximately four times the normal ABI in these patients. CONCLUSION: ABI is a valuable predictive index of midrange to severe ARAS.

[Plasma copeptin levels in elderly victims of massive cerebral infarction and its relationship to early death].

OBJECTIVE: To investigate copeptin levels in elderly patients who have suffered massive cerebral infarction, and to establish its correlation with early death. METHODS: Forty-nine elderly patients with acute massive cerebral infarction and an age-matched control group of thirty normal people were established. Plasma copeptin levels of patient group were measured by ELISA at 24 h, 36 h, 5 d, and 14 d after onset of infarction. Glasgow-Pittsburgh coma scale (GPCS) were recorded within 24 h after onset, and both results were graded. Based on the 14-day mortality, the patient was divided into a death group and a survival group, and the correlations between graded copeptin level and GPCS to mortality were analyzed, as well as the consistency and accuracy of prognosis. RESULTS: Plasma copeptin levels in the patient group were no differences between the 24 h, 36 h and 5 d point, and that of the 14 d was lower than that of the other points. Copeptin levels were significantly higher than in the control group at each test point (P< 0.01 or P< 0.05). The copeptin level at 24 h among those dead by 14 days was higher than in those of the survival group (P<0.01). There were significant associations of early death (within 14 d) with copeptin levels and with GPCS grade(r=0.58, P<0.001, r=0.46, P<0.001, respectively). Copeptin level of the third-grade (>25.0 pmol/L) showed better consistency and coincidence rate than GPCS score (< 20) in predicting early death. CONCLUSION: Plasma copeptin level was increased in early phases of acute massive cerebral infarction in elderly patients; it may have predictive value for early death.

TGF-beta1-800G>A polymorphism and cerebral infarction in Chinese Han population.

OBJECTIVE: To investigate the association between transforming growth factor beta1(TGF-beta1)-800G>A polymorphism and cerebral infarction (CI). METHODS: The genotypes of 247 patients with atherosclerotic cerebral infarction and 167 sex- and age-matched healthy controls were detected by PCR-RFLP, and the frequency distribution of alleles calculated. RESULTS: TGF-beta1-800G>A polymorphism was found in Han population in Hunan Province, China. The distribution of -800G>A genotypes was consistent with Hardy-Weinberg balance in the CI and healthy control group. There was no significant difference between genotypes and allele frequency of TGF-beta1-800G>A in the CI and control group (P>0.05). Logistic regression analysis suggested that no genotypes could increase or reduce the risk of CI onset (P>0.05). CONCLUSION: TGF-beta1-800G>A polymorphism is not associated with CI in Han population in Hunan Province.

High intrinsic ZT in InP3 monolayer at room temperature.

Two-dimensional thermoelectric (TE) materials which have the figure of merit ZT that is greater than 1.5 at room temperature would be highly desirable in energy conversion since the efficiency is competitive to conventional energy conversion techniques. Here, we report that the indium triphosphide (InP3) monolayer shows a large ZT of 1.92 at 300 K, based on the quantum calculations within the ballistic thermal transport region. A remarkably low and isotropic phononic thermal conductivity is found due to the flat lattice vibration modes, which takes a major responsibility for the impressively high ZT at room temperature. Moreover, a large ZT of 1.67 can still be achieved even under a 1% mechanical tension on the lattice. These results suggest that the InP3 monolayer is a promising candidate for low dimensional TE applications.

Self-powered photogalvanic phosphorene photodetectors with high polarization sensitivity and suppressed dark current.

High polarization sensitivity, suppressed dark current and low energy consumption are all desirable device properties for photodetectors. In this work, we propose phosphorene-based photodetectors that are driven using photogalvanic effects (PGEs). The inversion symmetry of pristine phosphorene is broken using either application of an out-of-plane gate voltage or a heterostructure that is composed of the original phosphorene and blue phosphorene. The potential asymmetry enables PGEs under illumination by polarized light. Quantum transport calculations show that robust photocurrents are indeed generated by PGEs under a zero external bias voltage because of the broken inversion symmetry. These results indicate that the proposed photodetector is self-powered. In addition, the zero bias voltage eliminates the dark currents that are caused by application of an external bias voltage to traditional photodetectors. High polarization sensitivity to both linearly and circularly polarized light can also be realized, with extinction ratios ranging up to 102. The photoresponse of the proposed phosphorene/blue phosphorene heterostructure can be greatly enhanced by gating and is several orders of magnitude higher than that in gated phosphorene.

Effect of molybdenum disulfide nanoribbon on quantum transport of graphene.

Based on the density functional theory method in combination with the nonequilibrium green's function formalism, the quantum transport properties in graphene-[Formula: see text] vertical heterojunction were investigated in this work. The leads are boron doped graphene and seamlessly connect to the graphene nanoribbon in central scattering region. Although there is a weak graphene-[Formula: see text] interaction, molybdenum disulfide can smooth the electrostatic potential and enlarge the transport properties of the whole device. However, another competitive factor is that of the edge states of the [Formula: see text] nanoribbon. When the transport is along the zigzag direction of graphene, the armchair [Formula: see text] nanoribbon simply enlarges the transmission coefficient. Nevertheless, in the armchair transport system, there is an asymmetric electrostatic potential induced by the different atomic potentials of S and Mo atoms at both edges in the zigzag [Formula: see text] nanoribbon, whose potential can lead to obvious scattering from graphene to [Formula: see text] and suppress the transmission probability. Therefore, it also suppresses the influence of zigzag [Formula: see text] nanoribbon on the transmission coefficient. Our first principles simulations provide useful predictions for the application of graphene based emerging electronics, which may stimulate further experimental exploration.