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IntroductionLateral lymph node (LLN) metastasis in rectal cancer significantly affects patient treatment and prognosis. This study aimed to comprehensively compare the performance of various predictive models in predicting LLN metastasis.MethodsIn this retrospective study, data from 152 rectal cancer patients who underwent lateral lymph node (LLN) dissection were collected. The cohort was divided into a training set (n=86) from Tianjin Union Medical Center (TUMC), and two testing cohorts: testing cohort (TUMC) (n=37) and testing cohort from Gansu Provincial Hospital (GSPH) (n=29). A clinical model was established using clinical data; deep transfer learning models and radiomics models were developed using MRI images of the primary tumor (PT) and largest short-axis LLN (LLLN), visible LLN (VLLN) areas, along with a fusion model that integrates features from both deep transfer learning and radiomics. The diagnostic value of these models for LLN metastasis was analyzed based on postoperative LLN pathology.ResultsModels based on LLLN image information generally outperformed those based on PT image information. Rradiomics models based on LLLN demonstrated improved robustness on external testing cohorts compared to those based on VLLN. Specifically, the radiomics model based on LLLN imaging achieved an AUC of 0.741 in the testing cohort (TUMC) and 0.713 in the testing cohort (GSPH) with the extra trees algorithm.ConclusionData from LLLN is a more reliable basis for predicting LLN metastasis in rectal cancer patients with suspicious LLN metastasis than data from PT. Among models performing adequately on the internal test set, all showed declines on the external test set, with LLLN_Rad_Models being less affected by scanning parameters and data sources.

Objective. This study aimed to explore the genes regulating lymph node metastasis in colorectal cancer (CRC) and to clarify their relationship with tumor immune cell infiltration and patient prognoses. Methods. The data sets of CRC patients were collected through the Cancer Gene Atlas database; the differentially expressed genes (DEGs) associated with CRC lymph node metastasis were screened; a protein–protein interaction (PPI) network was constructed; the top 20 hub genes were selected; the Gene Ontology functions and the Kyoto Encyclopedia of Genes and Genomes pathways were enriched and analyzed. The Least Absolute Shrinkage and Selection Operator (LASSO) regression method was employed to further screen the characteristic genes associated with CRC lymph node metastasis in 20 hub genes, exploring the correlation between the characteristic genes and immune cell infiltration, conducting a univariate COX analysis on the characteristic genes, obtaining survival-related genes, constructing a risk score formula, conducting a Kaplan–Meier analysis based on the risk score formula, and performing a multivariate COX regression analysis on the clinical factors and risk scores. Results. A total of 62 DEGs associated with CRC lymph node metastasis were obtained. Among the 20 hub genes identified via PPI, only calcium-activated chloride channel regulator 1 (CLCA1) expression was down-regulated in lymph node metastasis, and the rest were up-regulated. A total of nine characteristic genes associated with CRC lymph node metastasis (KIF1A, TMEM59L, CLCA1, COL9A3, GDF5, TUBB2B, STMN2, FOXN1, and SCN5A) were screened using the LASSO regression method. The nine characteristic genes were significantly related to different kinds of immune cell infiltration, from which three survival-related genes (TMEM59L, CLCA1, and TUBB2B) were screened. A multi-factor COX regression showed that the risk scores obtained from TMEM59L, CLCA1, and TUBB2B were independent prognostic factors. Immunohistochemical validation was performed in tissue samples from patients with rectal and colon cancer. Conclusion. TMEM59L, CLCA1, and TUBB2B were independent prognostic factors associated with lymphatic metastasis of CRC.

The memory retention for a ferroelectric field-effect transistor is limited by the depolarization effects and carrier charge trapping. Here, the authors fabricate a long-retention memory cell with a metal-ferroelectric-metal-insulator-semiconductor architecture built from all van der Waals single crystals.

In this paper, an ultra-wideband and polarization-insensitive frequency-selective surface absorber is presented with oblique incident stable behavior. Different from conventional absorbers, the absorption behavior is much less deteriorated with the increase in the incidence angle. Two hybrid resonators, which are realized by symmetrical graphene patterns, are employed to obtain the desired broadband and polarization-insensitive absorption performance. The optimal impedance-matching behavior is designed at the oblique incidence of electromagnetic waves, and an equivalent circuit model is used to analyze and facilitate the mechanism of the proposed absorber. The results indicate that the absorber can maintain a stable absorption performance with a fractional bandwidth (FWB) of 136.4% up to 40°. With these performances, the proposed UWB absorber could be more competitive in aerospace applications.

In this paper, a high-accurate technique with non-uniform grids is introduced into a system-combined alternative-direction-implicit finite-difference time-domain (SC-ADI-FDTD) algorithm, and then successfully used to analyze electromagnetic propagations. To our knowledge, the conventional FDTD with non-uniform grids can be effectively deal with some edges of the three-dimensional cubes and complicated structures of the tiny objects by modulating the local grid scales, which to the extent improves its reliability and accuracy. However, due to existing the finer grids in the local computational region and the inevitable Courant-Friedrichs-Lewy (CFL) limit in the conventional FDTD, the temporal interval must be determined by the minimum fine spatial grid, resulting in much larger temporal sampling density required during the whole computation process. As the advantage of circumventing the repeated variables, the non-uniform SC-ADI-FDTD (NUSC-ADI-FDTD) cannot only break through the CFL limit to implement the high-efficient computation, but also further save more CPU time in the local microstructure cases. Furthermore, the empirical formula between the spatial sampling density and the CFL factors can be obtained from the numerical fitting method after errors analysis. The numerical simulations of the electromagnetic scattering have been executed to illustrate feasibility and validity of our proposed method.

Abstract Purpose The aim of this study is to examine the pattern of lymph node metastasis (lateral vs. mesenteric lymph nodes) in low rectal cancer. Methods This retrospective analysis included all patients undergoing laparoscopic total mesorectal excision plus lateral lymph node dissection for advanced low rectal cancer (up to 8 cm from the anal verge) during a period from July 1, 2017, to August 31, 2019, at the Department of Colorectal Surgery, Tianjin Union Medical Center. The decision to conduct lateral lymph node dissection was based on positive findings in preoperative imaging assessments. Results A total of 42 patients were included in data analysis. Surgery was successfully completed as planned, without conversion to open surgery in any case. A minimum of 10 mesenteric lymph nodes and 1 lateral lymph node on each side were dissected in all patients. Pathologic examination of resected specimens showed no metastasis to either mesenteric or lateral lymph nodes in 7 (16.7%) case, metastasis to both mesenteric and lateral lymph nodes in 26 (61.9%) cases, metastasis to mesenteric but not lateral lymph nodes in 4 (9.5%) cases, and metastasis to lateral but not mesenteric lymph nodes in 5 (11.9%) cases (n = 2 in the obturator region; n = 3 in the iliac artery region). Conclusion A clinically significant proportion of low rectal cancer patients have metastasis to lateral lymph nodes without involvement of mesenteric lymph nodes. More carefully planned prospective studies are needed to verify this preliminary finding.

Two-dimensional magnets with intrinsic ferromagnetic/antiferromagnetic ordering are highly desirable for future spintronic devices. Here, the authors demonstrate a chemical vapor deposition approach to controllably grow ultrathin FeTe crystals with antiferromagnetic tetragonal and ferromagnetic hexagonal phase, showing a thickness-dependent magnetic transition.

Abstract In recent years, two‐dimensional (2D) ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space. However, as for the precise synthesis of 2D ternary materials, great challenges still lie ahead that hinder their further development. In this work, we demonstrated a simple and reliable approach to synthesize 2D ternary‐layered BiOCl crystals through a microwave‐assisted space‐confined process in a short time (

Controlled growth of heterostructures within 10 nm scale is crucial for potential applications of transition metal dichalcogenides. Here, the authors report strain-driven synthesis of ultra-long MoS2 nano-channels having several micrometers length and 2–30 nm width embedded within MoSe2 monolayer.

Incorporating a truncation of the complex-frequency-shifted perfectly matched layer (CFS-PML), the direct-splitting- based Crank-Nicolson finite-difference time-domain (CNDS-FDTD) is developed and applied to the infrared two-dimensional layered material (2DLM) black phosphorous (BP) metasurface implementations on the all-dielectric nanostructure. To improve extremely low efficiencies in solving infrared terahertz (THz) problems with the few-atomic-layer thickness of 2DLMs, the CFS-CNDS-FDTD is proposed in demand due to the fact that it possesses capabilities of implicit FDTD method and unsplit-field CFS-PML truncation, respectively, in completely conquering the Courant-Friedrich-Levy condition (CFL) limit and holding good performance. The temporal incremental in the CFS-CNDS-FDTD can reach 1000 times larger than that in the regular FDTD for infrared nanoscale problems centered at the 2.5 THz and then keep accurate. Three-dimensional (3D) numerical cases have been carried out to corroborate the proposed method. The CFS-CNDS- FDTD can not only achieve high accuracies and then saves several dozen times of CPU time as compared to the regular FDTD, but also pave the way for designing all-dielectric nanostructures with other 2DLM metasurfaces.

Abstract Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~1012 cm−2. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: −25 mV and Tafel slope: 54 mV dec−1), thus indicating an intrinsically high activation of the TMD GBs.

A circularly polarized (CP) broadside antenna array with a continuously adjustable beam is proposed and implemented. First, a reflection phase shifter with varactor diodes loaded on two output terminals of a branch directional coupler is realized. By controlling the voltage across both ends of the varactor diodes in the terminal load circuit, the reactance of the load is changed, allowing control of port phase shift. Following that, the microstrip patch antenna array is combined with the reflection phase shifter to achieve the pattern reconstruction for the array. For verification, a prototype of the designed pattern reconfigurable antenna (PRA) is fabricated and measured. The measurement results indicate that the beam direction of the antenna can be continuously adjusted with a change in the voltage across the varactor diodes. The maximum beam direction of the antenna reaches ±21° when the biggest DC bias voltage across the varactor diode is chosen as 15 V. Besides, the antenna shows good CP performance in different beam directions.

Room temperature Na-ion batteries (SIBs) show great potential for use as renewable energy storage systems. However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan (G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets (NSs), as well as being a buffer material to adapt to changes in volume during the cycle. Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability (527.3 mAh g−1 at 100 mA g−1 after 200 cycles), excellent rate capability, and a long cycle life (439.1 mAh g−1 at 1A g−1 after 200 cycles). Keywords: Na-ion batteries, Carbon-based materials, MoS2, Long cycle life

Abstract Graphene, an innovated 2D material with atomic thickness, is a very promising candidate and has drawn great attentions in various applications. Graphene metasurface enables dynamic control of various wavefronts, achieving distinguished functionalities. The flexibility of graphene metasurface makes it possible to implement multifunctional devices with ease. In this work, a novel design of multifunctional graphene metasurface, which can combine the functionalities of generating and steering vortex waves, has been proposed. The multifunctional graphene metasurface consists of a large array of graphene reflective unit cells. Each unit cell is controlled independently by its size and external static gate voltage. By scrutinizing the reflective property of the graphene cell, the graphene metasurface is designed to realize multi-functionalities. Simulation results show that vortex wave can be generated and steered. This work can establish a methodology to design multifunctional graphene metasurfaces, and the tunability of graphene opens the gate to the design and fabrication of reconfigurable graphene devices.

In this response letter, we focus on addressing Yu Hang Yang’s comments so that the correctness and validity of the proposed auxiliary-differential-equation-based (ADE) Crank-Nicolson finite-difference time-domain method with direct-splitting technique (CNDS-FDTD) are demonstrated. Moreover, related applications in modeling 2D material nanostructure problems are shown.

The adaptation to atomically thin 2D semiconductors and van der Waals layered ferroelectrics can enable negative capacitance transistors with superior performance and bendability. Here, the authors report flexible negative capacitance transistors based on MoS2 and a ferroelectric dielectric CIPS with a minimum sub-threshold slope of 28 mV/dec and high gain logic invertors.

Several configurations of multi-beam reconfigurable THz antennas based on graphene have been investigated. Two modulation mechanisms of graphene-based THz antenna are introduced, one is the reflector-transmission window model, and the other is the reflector-director model (Yagi-Uda antenna). The main parameters, such as main beam direction, resonance frequency, peak gain, and the front-to-back ratio of the proposed antenna can be controlled by adjusting the chemical potentials of the graphene in the antenna. Moreover, this paper provides an easy way to obtain complex graphene-based multi-beam antennas, showing strong potential in the design of other complex graphene-based systems, enabling nanoscale wireless communications and sensing devices for different applications.

This contribution presents a novel 3-D circular conformal MIMO antenna system composed of three magneto-electric dipoles (MED) antennas. The single MED element was delicately designed to include one main (lower-band) dipole and two auxiliaries (upper-band) dipoles in order to achieve the dual-band radiation. The proposed MED owns a low-profile conformal geometry but features a wide H-plane beamwidth (minimum 103°). By embedding the metamaterial of the broadside-coupled E-shaped unit cells into the magnetic dipole, the height of MED can be dramatically reduced by 37.2% as compared with the conventional ones. Meanwhile, the two U-shaped notches together with a rectangular notch were included onto the E-dipole to create a band-notch, which offers the anti-interference capability to the ubiquitous 2.4-GHz signal of the wireless local area network. According to the measurement results, the MED element exhibits an impedance bandwidth of 54.2% (1.68-2.93 GHz) with a stable gain of 6.05± 1.15 dBi in the lower band and 9.2% (3.32-3.64 GHz) with 5.71 ± 0.7 dBi in the upper band, respectively. Moreover, the three-element MIMO system provides quasi-omnidirectional coverage in the H-plane from 1.68 to 3.64 GHz. The outstanding performance metrics validate the proposed ME dipole antenna that is well suited for the future sub-6-GHz fifth-generation MIMO mobile base stations.

The mid-infrared technologies are essential to various applications but suffer from limited materials with suitable bandgap. Here the authors demonstrate that two-dimensional atomically thin PtSe2 with variable bandgaps in the mid-infrared via layer and defect engineering is highly promising for mid-infrared optoelectronics.

This paper presents a design method of wideband Fabry-Perot resonator antennas (FPRAs) with two layers of electrically thin dielectric superstrates. The bandwidth enhancement mainly benefits from the superstrate structure with reflection phase increasing with frequency, which is used as a partially reflective surface. The proposed method is validated by a design example in X-band. Experimental results of the FPRA prototype demonstrate that the 3-dB gain bandwidth ranges from 8.5 to 11.2 GHz (relatively 28%) with a peak gain of 14 dBi and coincides with the impedance band for S11 ≤ -10 dB. Compared with the existing methods of gain bandwidth enhancement, the one presented in this paper does not need dielectric substrates with a large or fixed electrical thickness, improving cost performance and design flexibility.

This paper describes a beam-switching antenna with high gain and flexible control of beam numbers based on frequency selective surfaces (FSSs). The proposed antenna is composed of an omnidirectional monopole antenna, a hexagon FSS screen, and six metallic sheets that surround the monopole antenna. The hexagon FSS screen contains six columns, each is made up of two FSS unit-cells. The beam-switching antenna is divided into six equal portions by six metallic sheets, which are employed here to improve the gain of the antenna. The proposed FSS unit-cell consists of the two metallic crosses connected by a pin-diode. The transmission characteristics of the FSS unit-cell are investigated for different pin-diode states. Therefore, by changing the states of the pin-diodes in the hexagon FSS screen, the proposed antenna can sweep six directions with gain enhancement in the azimuth plane. Moreover, it can also flexibly operate at multiple beams modes, including two-beam mode and three-beam mode with low power. This proposed antenna is fabricated and measured, showing good performances at 5.2 GHz. The maximum enhancement of the antenna gain is up to 7 dB, which is achieved by using the metallic sheets and verified with simulated and measured results, which show good agreement.

This paper presents a frequency-selective rasorber whose transmission window locates at the higher frequency of absorption band. The accomplished rasorber is composed of dipole-like and slot arrays, and has realized the transmissive/absorptive performance. In every unit cell, each pair of dipole-like elements connected by vias is printed on the two sides of the substrate, and the coupling between long and short dipoles is suppressed by this structure. A guiding circuit is studied based on the analysis of the current path, and the insertion loss of transmission window is significantly reduced by the surface current at the pass-band that is hindered to pass through lossy elements. The presented rasorber acts as an absorber at the low frequencies, while providing a high transmittance window at 5.6 GHz. This design is elaborately optimized to achieve low reflection and angle-insensitive performance. Finally, the presented structure is validated by numerical simulations and experimental measurements. This rasorber could be used for secrecy communications among stealth facilities while providing stable broad-band absorptive properties.

A novel linearly dual-polarized antenna array with triple elements is proposed for beamwidth reconfigurable base-station communications. By cutting off the arc-shaped corners on the radiated patches, the single dual-polarized antenna unit can obtain a wide bandwidth of 78.4% for SWR ≤ 2, ranging from 1.63 to 3.73 GHz for 2G/3G/LTE and 3.5-GHz C-band (3.4-3.6 GHz) applications. In addition, with the box-shaped reflector and the inherent characteristic of the ME dipole antenna, the average gain of the dual-polarized antenna element is about 11.5 dBi. Finally, by employing a two-stage circuit with several power dividers, a three-element antenna array with a widely adjustable beamwidth in both the E-plane and H-plane is investigated, which could meet the demand of the future smart applications.

A low-profile metamaterial loaded antenna array with anti-interference and polarization reconfigurable features is proposed for base-station communication. Owing to the dual notches etched on the radiating electric dipoles, an impedance bandwidth of 75.6% ranging from 1.68 to 3.72 GHz with a notch band from 2.38 to 2.55 GHz can be achieved. By employing the metamaterial loadings that are arranged in the center of the magnetic dipole, the thickness of the proposed antenna can be decreased from 28 to 20 mm. Furthermore, a serial feeding network that consists of several Wilkinson power dividers and phase shifters is introduced to attain the conversion between dual-linear polarization and triple-circular polarization. Hence, the antenna could meet the demand of the future 5G intelligent application.

A substrate integrated magneto-electric (ME) dipole antenna with metasurface is proposed for the 5G/WiMAX/WLAN/X-band MIMO applications. In order to provide a low profile, the radiated electric dipoles integrated with shorted wall are used in the multi-layer substrates at different heights. Owing to the coordination of the metasurface and the ME dipole, dual wideband and high gain have been obtained. As a result of the 3-D hexagonal structure, good envelope correlation coefficient and mean effective gain performance can be achieved by the MIMO antenna system. The antenna element can provide an impedance bandwidth of 66.7% (3.1 - 6.2 GHz) with a stable gain of 7.6 ± 1.5 dBi and an impedance bandwidth of 20.3% (7.1 - 8.7 GHz) with a gain of 7.4 ± 1.8 dBi for the lower and upper bands, respectively. The overall size of the element is 60 × 60 × 7.92 mm3. Hence, it is well-suited for the future 5G/WiMAX/WLAN/X-band MIMO communications.

Two-dimensional superconductors will likely have applications not only in devices, but also in the study of fundamental physics. Here, Wang et al. demonstrate the CVD growth of superconducting NbSe2 on a variety of substrates, making these novel materials increasingly accessible.

To simulate complex subsurface sensing and imaging problems with both propagating and evanescent waves by the finite-difference time-domain (FDTD) method, the highly-accurate second-order perfectly matched layer (SO-PML) formulations based on the direct Z-transform (DZT) and the matrix exponential (ME) techniques are compactly and efficiently proposed for modeling open-domain problems. During mathematical deductions, several manipulations, for example, convolution computations, formulation reorganizations, or variable substitutions, can be circumvented due to the fact that the ME-based method shows a compact first-order differential matrix form. Besides, any material attributes can be completely circumvented because of using electric and magnetic flux densities, consequently, the proposed DZT-SO-PML could be applied without needing any alteration. Moreover, the DZT-SO-PML method can not only preserve better absorption accuracies, but also attain palpable improvements in computational efficiencies, even if the distance between the DSP-SO-PML truncation and the target becomes closer for modeling 3D open-domain subsurface sensing and imaging problems. Finally, numerical examples have been carried out to illustrate and validate these proposed formulations.

A wideband slot antenna with frequency- and pattern-reconfigurable characteristics for TD-LTE (3.4–3.8 GHz) and C-band (3.7–4.2 GHz) applications is proposed. The antenna consists of two symmetric slots that are fed by a fork-shaped microstrip line. Two PIN diodes are loaded in the slots to produce two different frequency bands. Meanwhile, two additional PIN diodes are inserted in the feed line to achieve the pattern reconfigurability. The wideband operation is realized by using the symmetric slots and fork-shaped feed line. Simulated and measured results show that the antenna provides 25° and 20° beam-steering in 3.4–3.8 and 3.7–4.2 GHz bands, respectively. Also, an impedance bandwidth of at least 12.8% is obtained in the operating bands.