Bevel-edge epitaxy of ferroelectric rhombohedral boron nitride single crystal.

Within the family of two-dimensional dielectrics, rhombohedral boron nitride (rBN) is considerably promising owing to having not only the superior properties of hexagonal boron nitride1-4-including low permittivity and dissipation, strong electrical insulation, good chemical stability, high thermal conductivity and atomic flatness without dangling bonds-but also useful optical nonlinearity and interfacial ferroelectricity originating from the broken in-plane and out-of-plane centrosymmetry5-23. However, the preparation of large-sized single-crystal rBN layers remains a challenge24-26, owing to the requisite unprecedented growth controls to coordinate the lattice orientation of each layer and the sliding vector of every interface. Here we report a facile methodology using bevel-edge epitaxy to prepare centimetre-sized single-crystal rBN layers with exact interlayer ABC stacking on a vicinal nickel surface. We realized successful accurate fabrication over a single-crystal nickel substrate with bunched step edges of the terrace facet (100) at the bevel facet (110), which simultaneously guided the consistent boron-nitrogen bond orientation in each BN layer and the rhombohedral stacking of BN layers via nucleation near each bevel facet. The pure rhombohedral phase of the as-grown BN layers was verified, and consequently showed robust, homogeneous and switchable ferroelectricity with a high Curie temperature. Our work provides an effective route for accurate stacking-controlled growth of single-crystal two-dimensional layers and presents a foundation for applicable multifunctional devices based on stacked two-dimensional materials.

Sliding ferroelectricity in 2D van der Waals materials: Related physics and future opportunities.

Near the 100th anniversary of the discovery of ferroelectricity, so-called sliding ferroelectricity has been proposed and confirmed recently in a series of experiments that have stimulated remarkable interest. Such ferroelectricity exists widely and exists only in two-dimensional (2D) van der Waals stacked layers, where the vertical electric polarization is switched by in-plane interlayer sliding. Reciprocally, interlayer sliding and the "ripplocation" domain wall can be driven by an external vertical electric field. The unique combination of intralayer stiffness and interlayer slipperiness of 2D van der Waals layers greatly facilitates such switching while still maintaining environmental and mechanical robustness at ambient conditions. In this perspective, we discuss the progress and future opportunities in this behavior. The origin of such ferroelectricity as well as a general rule for judging its existence are summarized, where the vertical stacking sequence is crucial for its formation. This discovery broadens 2D ferroelectrics from very few material candidates to most of the known 2D materials. Their low switching barriers enable high-speed data writing with low energy cost. Related physics like Moiré ferroelectricity, the ferroelectric nonlinear anomalous Hall effect, and multiferroic coupling are discussed. For 2D valleytronics, nontrivial band topology and superconductivity, their possible couplings with sliding ferroelectricity via certain stacking or Moiré ferroelectricity also deserve interest. We provide critical reviews on the current challenges in this emerging area.

Letter to the editor.

We review the study by Xu et al. (J Clin Monit Comput 37(4):985-992, 2023. https://doi.org/10.1007/s10877-022-00968-1 ) on ultrasound-guided regional blocks in clavicle surgery, assessing the effects on anaesthesia and postoperative outcomes. However, there are concerns. The defined population of the study differs from the registered title (Xu et al. J Clin Monit Comput 37(4):985-992, 2023. https://doi.org/10.1007/s10877-022-00968-1 ). In particular, the authors did not specify fracture types (Xu et al. J Clin Monit Comput 37(4):985-992, 2023. https://doi.org/10.1007/s10877-022-00968-1 ). In addition, the method of measuring the diaphragm is not clear (Xu et al. J Clin Monit Comput 37(4):985-992, 2023. https://doi.org/10.1007/s10877-022-00968-1 ). This affects the accurate interpretation of their results.

Atypical Sliding and Moiré Ferroelectricity in Pure Multilayer Graphene.

Most nonferroelectric two-dimensional materials can be endowed with so-called sliding ferroelectricity via nonequivalent homobilayer stacking, which is not applicable to monoelement systems like pure graphene bilayer with inversion symmetry at any sliding vector. Herein, we show first-principles evidence that multilayer graphene with N>3 can all be ferroelectric, where the polarizations of polar states stem from the symmetry breaking in stacking configurations of across layer instead of adjacent layer, which are electrically switchable via interlayer sliding. The nonpolar states can also be electrically driven to polar states via sliding, and more diverse states with distinct polarizations will emerge in more layers. In contrast to the ferroelectric moiré domains with opposite polarization directions in twisted bilayers reported previously, the moiré pattern in some multilayer graphene systems (e.g., twisted monolayer-trilayer graphene) possess nonzero net polarizations with domains of the same direction separated by nonpolar regions, which can be electrically reversed upon interlayer sliding. The distinct moiré bands of two polar states should facilitate electrical detection of such sliding moiré ferroelectricity during switching.

Optimal prophylactic para-aortic radiotherapy in locally advanced cervical cancer: anatomy-based versus margin-based delineation.

OBJECTIVE: Precise delineation of the para-aortic nodal region is critical for the optimal therapeutic ratio of prophylactic para-aortic radiotherapy. We aimed to evaluate the para-aortic control and patient-reported gastrointestinal toxicity in patients with locally advanced cervical cancer who received anatomy-based or margin-based prophylactic para-aortic radiotherapy. METHODS: We analyzed 160 patients with locally advanced cervical cancer who received prophylactic extended-field radiotherapy between January 2014 and November 2019 at two tertiary centers. Para-aortic nodal regions were delineated based on the anatomic principle-based atlas or marginal expansion from the aorta and inferior vena cava. The Patient-Reported Outcome version of the Common Terminology Criteria for Adverse Events was used to assess acute gastrointestinal toxicity, and a score of ≥3 was defined as severe gastrointestinal toxicity. RESULTS: Seventy-six (47.5%) and 84 (52.5%) patients received anatomy-based and margin-based prophylactic para-aortic radiotherapy, respectively. The median follow-up was 40.1 months (IQR 25.5-58.9). Para-aortic nodal failures occurred in one (1.3%) patient in the anatomy-based para-aortic radiotherapy group and in one (1.2%) patient in the margin-based para-aortic radiotherapy group (p=1.00). There was no in-field or marginal para-aortic nodal failure. The 3-year para-aortic recurrence-free survival for anatomy-based and margin-based para-aortic radiotherapy was 98.6% and 98.8%, respectively (p=0.94). Patients who received anatomy-based para-aortic radiotherapy reported less severe acute gastrointestinal toxicity than those who received margin-based para-aortic radiotherapy (13.2% vs 29.8%, p=0.01). A comparison of gastrointestinal toxicities showed that patients who received anatomy-based para-aortic radiotherapy reported significantly less severe gastrointestinal toxicity than those who received margin-based para-aortic radiotherapy in terms of frequency of diarrhea (7.9% vs 20.2%, p=0.03), severity of abdominal pain (3.9% vs 14.3%, p=0.03), and interference of abdominal pain (2.6% vs 11.9%, p=0.03). CONCLUSION: Anatomy-based prophylactic para-aortic radiotherapy achieved excellent para-aortic control and a lower incidence of severe patient-reported gastrointestinal toxicity. These findings suggest that anatomy-based delineation optimizes clinical outcomes of prophylactic para-aortic radiotherapy in locally advanced cervical cancer.

Association of bowel radiation dose-volume with skeletal muscle loss during pelvic intensity-modulated radiotherapy in cervical cancer.

BACKGROUND: Radiation-induced bowel damage may compromise nutrient absorption and digestion and affect body composition during pelvic radiotherapy in patients with locally advanced cervical cancer (LACC). This study aimed to evaluate the relationship between bowel radiation dose-volume and body composition changes during pelvic radiotherapy. METHODS: Data of 301 LACC patients treated with chemoradiotherapy were analyzed. Changes in skeletal muscle index (SMI) and density (SMD), and total adipose tissue index (TATI) were measured from computed tomography images at the L3 vertebral level. A reduction in SMI, SMD, or TATI of ≥10% was classified as "loss." Bowel V45 indicates the bowel volume (mL) receiving a radiation dose of ≥45 Gy. The relationship between body composition and bowel V45 was analyzed using logistic regression models. RESULTS: After treatment, 61 (20.3%), 81 (26.9%), and 97 (32.2%) patients experienced SMI, SMD, and TATI loss, respectively. Increased bowel V45 was independently associated with increased odds of SMI loss (odds ratio [OR]: 1.012; 95% confidence interval [CI]: 1.007-1.018; p<0.001) and TATI loss (OR: 1.006; 95% CI: 1.001-1.010; p=0.01), but not with SMD loss (OR: 1.005; 95% CI: 1.000-1.009; p=0.054). The cut-off value with the highest accuracy for predicting SMI loss was V45 ≥222 mL; a higher rate of SMI loss was noted in 40.0% of patients with V45 ≥222 mL than in 13.7% of patients with V45 <222 mL (p<0.001). CONCLUSIONS: Higher bowel dose-volume was significantly associated with muscle loss during pelvic radiotherapy. Bowel dose-volume consideration is required in individualized nutritional counseling and supportive care in clinical practice.

0D/1D organic ferroelectrics/multiferroics for ultrahigh density integration: Helical hydrogen-bonded chains, multi-mode switching, and proton synaptic transistors.

In recent years, room-temperature ferroelectricity has been experimentally confirmed in a series of two-dimensional (2D) materials. Theoretically, for isolated ferroelectricity in even lower dimensions such as 1D or 0D, the switching barriers may still ensure the room-temperature robustness for ultrahigh-density non-volatile memories, which has yet been scarcely explored. Here, we show ab initio designs of 0D/1D ferroelectrics/multiferroics based on functionalized transition-metal molecular sandwich nanowires (SNWs) with intriguing properties. Some functional groups such as -COOH will spontaneously form into robust threefold helical hydrogen-bonded chains around SNWs with considerable polarizations. Two modes of ferroelectric switching are revealed: when the ends of SNWs are not hydrogen-bonded, the polarizations can be reversed via ligand reorientation that will reform the hydrogen-bonded chains and alter their helicity; when both ends are hydrogen-bonded, the polarizations can be reversed via proton transfer without changing the helicity of chains. The combination of those two modes makes the system the smallest proton conductor with a moderate migration barrier, which is lower compared with many prevalent proton-conductors for higher mobility while still ensuring the robustness at ambient conditions. This desirable feature can be utilized for constructing nanoscale artificial ionic synapses that may enable neuromorphic computing. In such a design of synaptic transistors, the migration of protons through those chains can be controlled and continuously change the conductance of MXene-based post-neuron for nonvolatile multilevel resistance. The success of mimicking synaptic functions will make such designs promising in future high-density artificial neutral systems.

Fullerene-based 0D ferroelectrics/multiferroics for ultrahigh-density and ultrafast nonvolatile memories.

Recently, the existence of room-temperature ferroelectricity has been experimentally confirmed in a number of two-dimensional (2D) materials. With a switching barrier large enough to be stable against thermal fluctuation, ferroelectricity in even lower dimensions like 1D or 0D may be explored for data storage of higher density, which has been scarcely reported. Here, we show the first-principles design of 0D ferroelectrics/multiferroics based on polar functionalized fullerene. It turns out that the ferroelectric polarization of endohedral metallofullerenes can be reversed with the diffusion of metal ions inside when the fullerene is fixed on a substrate. If its bonding with the substrate is relatively weak, the rotation of fullerene will be more favorable in energy for ferroelectric switching. The switching barriers of both modes, for the candidates with considerable magnetic moments and dipole moments, are all in the ideal range for working under ambient conditions. Moreover, compared with conventional ferroelectrics for data storage, they may be endowed with a high areal density (∼105 Gbit per in2) and high writing speed (∼102 GHz) that are respectively more than 2 and 3 orders of magnitude higher.

In-Field Calibration of Triaxial Accelerometer Basedon Beetle Swarm Antenna Search Algorithm.

Traditional calibration method is usually performed with expensive equipments suchas three-axis turntable in a laboratory environment. However in practice, in order to ensure theaccuracy and stability of the inertial navigation system (INS), it is usually necessary to recalibratethe inertial measurement unit (IMU) without external equipment in the field. In this paper, anew in-field recalibration method for triaxial accelerometer based on beetle swarm antenna search(BSAS) algorithm is proposed. Firstly, as a new intelligent optimization algorithm, BSAS algorithmand its improvements based on basic beetle antennae search (BAS) algorithm are introduced indetail. Secondly, the nonlinear mathematical model of triaxial accelerometer is established forhigher calibration accuracy, and then 24 optimal measurement positions are designed by theoreticalanalysis. In addition, the calibration procedures are improved according to the characteristics of BSASalgorithm, then 15 calibration parameters in the nonlinear method are optimized by BSAS algorithm.Besides, the results of BSAS algorithm and basic BAS algorithm are compared by simulation, whichshows the priority of BSAS algorithm in calibration field. Finally, two experiments demonstrate thatthe proposed method can achieve high precision in-field calibration without any external equipment,and meet the accuracy requirements of the INS.

A Denoising Method for Fiber Optic Gyroscope Based on Variational Mode Decomposition and Beetle Swarm Antenna Search Algorithm.

Fiber optic gyroscope (FOG) is one of the important components of Inertial Navigation Systems (INS). In order to improve the accuracy of the INS, it is necessary to suppress the random error of the FOG signal. In this paper, a variational mode decomposition (VMD) denoising method based on beetle swarm antenna search (BSAS) algorithm is proposed to reduce the noise in FOG signal. Firstly, the BSAS algorithm is introduced in detail. Then, the permutation entropy of the band-limited intrinsic mode functions (BLIMFs) is taken as the optimization index, and two key parameters of VMD algorithm, including decomposition mode number K and quadratic penalty factor α , are optimized by using the BSAS algorithm. Next, a new method based on Hausdorff distance (HD) between the probability density function (PDF) of all BLIMFs and that of the original signal is proposed in this paper to determine the relevant modes. Finally, the selected BLIMF components are reconstructed to get the denoised signal. In addition, the simulation results show that the proposed scheme is better than the existing schemes in terms of noise reduction performance. Two experiments further demonstrate the priority of the proposed scheme in the FOG noise reduction compared with other schemes.

Vanadium dioxide based broadband THz metamaterial absorbers with high tunability: simulation study.

With their unprecedented flexibility in manipulating electromagnetic waves, metamaterials provide a pathway to structural materials that can fill the so-called "THz gap". It has been reported that vanadium dioxide (VO2) experiences a three orders of magnitude increase in THz electrical conductivity when it undergoes an insulator-to-metal transition. Here, we propose a VO2 based THz metamaterial absorber exhibiting broadband absorptivity that arises from the multiple resonances supported by a delicately balanced doubly periodic array of VO2 structures and numerically demonstrate that the corresponding absorption behavior is highly dependent on the VO2's THz electrical properties. Considering the phase transition induced dramatic change in VO2's material property, the proposed metamaterial absorbers have the potential for strong modulation and switching of broadband THz radiation.

Sodium bismuth dichalcogenides: candidates for ferroelectric high-mobility semiconductors for multifunctional applications.

The combination of ferroelectricity with narrow-gap high-mobility semiconductors may not only entail both functions of nonvolatile memory and efficient manipulation of signals, but may also facilitate efficient ferroelectric photovoltaics and thermoelectrics. However, these applications are hindered by the wide gap and poor mobility of current ferroelectrics. A recent study (J. Am. Chem. Soc., 2018, 140, 3736) reported a facile, general, low-temperature, and size tunable solution phase synthesis of NaBiS2 and NaBiSe2 that are made of relatively abundant or biocompatible elements, which enables their large-scale practical applications. Herein we show first-principles evidence of their ferroelectricity with a large polarization (∼33 µC cm-2), a moderate bandgap (∼1.6 eV) and a high electron-mobility (∼104 cm2 V-1 s-1). Although they have a relatively small switching barrier, their ferroelectricity can be robust under ambient conditions with enhanced polarization upon either application of a small tensile strain or ion doping, where distortion can be increased and multiferroics may also be obtained, despite reduced mobility. Considering previous reports on photovoltaics and thermoelectrics of similar compounds, sodium bismuth dichalcogenides might be tuned for higher performance with the coexistence of these desirable properties.

The Actor-Dueling-Critic Method for Reinforcement Learning.

Model-free reinforcement learning is a powerful and efficient machine-learning paradigm which has been generally used in the robotic control domain. In the reinforcement learning setting, the value function method learns policies by maximizing the state-action value (Q value), but it suffers from inaccurate Q estimation and results in poor performance in a stochastic environment. To mitigate this issue, we present an approach based on the actor-critic framework, and in the critic branch we modify the manner of estimating Q-value by introducing the advantage function, such as dueling network, which can estimate the action-advantage value. The action-advantage value is independent of state and environment noise, we use it as a fine-tuning factor to the estimated Q value. We refer to this approach as the actor-dueling-critic (ADC) network since the frame is inspired by the dueling network. Furthermore, we redesign the dueling network part in the critic branch to make it adapt to the continuous action space. The method was tested on gym classic control environments and an obstacle avoidance environment, and we design a noise environment to test the training stability. The results indicate the ADC approach is more stable and converges faster than the DDPG method in noise environments.

Type-II Multiferroic Hf2VC2F2 MXene Monolayer with High Transition Temperature.

Achieving multiferroic two-dimensional (2D) materials should enable numerous functionalities in nanoscale devices. Until now, however, predicted 2D multiferroics are very few and with coexisting yet only loosely coupled (type-I) ferroelectricity and magnetism. Here, a type-II multiferroic MXene Hf2VC2F2 monolayer is identified, where ferroelectricity originates directly from its magnetism. The noncollinear 120° Y-type spin order generates a polarization perpendicular to the spin helical plane. Remarkably, the multiferroic transition is estimated to occur above room temperature. Our investigation should open the door to a new branch of 2D materials in the pursuit of intrinsically strong magnetoelectricity.

Impact of para-aortic recurrence risk-guided intensity-modulated radiotherapy in locally advanced cervical cancer with positive pelvic lymph nodes.

OBJECTIVES: A previous study has suggested the benefit of sub-renal vein radiotherapy (SRVRT) for pelvic lymph node (PLN)-positive cervical cancer. In order to better select patients for SRVRT, this study aimed to evaluate the value of a risk-based radiation field based on PLN location and number in PLN-positive cervical cancer. METHODS: We reviewed 198 patients with FIGO stage IB2-IVA cervical cancer, positive PLNs, and negative para-aortic lymph nodes (PALNs) from 2004 to 2015 at two tertiary centers. All patients underwent pelvic radiotherapy (PRT) or SRVRT with IMRT. The SRVRT extended the PRT field cranially to the level of the left renal vein. The prescribed doses were 45-50.4Gy in 1.8Gy per fraction. RESULTS: Overall, 118 and 80 patients underwent PRT and SRVRT, respectively. The SRVRT group had more advanced disease based on FIGO stage, common iliac PLNs, and number of PLNs. The median follow-up was 63months (range: 7-151months). PALN failure was experienced by 28 patients (23.7%) in the PRT group and 1 patient (1.3%) in the SRVRT group (p<0.001). Compared with PRT, SRVRT significantly improved 5-year PALN recurrence-free survival (56.8% vs. 100%, p<0.001) and cancer-specific survival (56.5% vs. 93.9%, p<0.001) among patients with common iliac PLNs or ≥3 PLNs. No significant differences were observed in these outcomes among patients with PLNs below the common iliac bifurcation and 1-2 PLNs. The SRVRT did not increase severe toxicities. CONCLUSIONS: Risk-based radiation field based on PLN location and number could optimize outcomes for PLN-positive cervical cancer.

Transition-metal-doped group-IV monochalcogenides: a combination of two-dimensional triferroics and diluted magnetic semiconductors.

We report the first-principles evidence of a series of two-dimensional triferroics (ferromagnetic + ferroelectric + ferroelastic), which can be obtained by doping transition-metal ions in group-IV monochalcogenide (SnS, SnSe, GeS, GeSe) monolayers, noting that a ferromagnetic Fe-doped SnS2 monolayer has recently been realized (Li B et al 2017 Nat. Commun. 8 1958). The ferroelectricity, ferroelasticity and ferromagnetism can be coupled and the magnetization direction may be switched upon ferroelectric/ferroelastic switching, rendering electrical writing + magnetic reading possible. They can be also two-dimensional half-metals or diluted magnetic semiconductors, where p/n channels or even multiferroic tunneling junctions can be designed by variation in doping and incorporated into a monolayer wafer.

The Effect of Body Mass Index and Weight Change on Late Gastrointestinal Toxicity in Locally Advanced Cervical Cancer Treated With Intensity-modulated Radiotherapy.

OBJECTIVE: To evaluate the effects of body mass index (BMI) and weight change during radiotherapy on the development of toxicity in patients with locally advanced cervical cancer (LACC) treated with intensity-modulated radiotherapy (IMRT). METHODS: A total of 245 patients were analyzed after undergoing definitive IMRT treatment between 2004 and 2015 for stage IB2 to stage IVA LACC. The patients were divided into 3 groups: underweight (BMI <18.5 kg/m), normal weight (BMI 18.5-24.9 kg/m), and overweight (BMI ≥25.0 kg/m). The relationships between toxicity, clinical factors, and the bowel dose-volume histogram were analyzed. V45 indicated the bowel volume that received a radiation dose of 45 Gy. RESULTS: The median follow-up period was 63 months. The V45 was similar among the 3 groups. The 5-year rates of grade 3 or higher late gastrointestinal toxicities were 18.6%, 4.0%, and 4.2% for the underweight, normal weight, and overweight groups, respectively (P = 0.002). In the multivariable analysis, underweight (hazard ratio, 13.99; 95% confidence interval, 3.22-60.82; P < 0.001) and weight loss (> -5%) (hazard ratio, 5.91; 95% confidence interval, 1.75-19.98; P = 0.004) were significant predictors of grade 3 or higher-grade late gastrointestinal toxicities. CONCLUSION: A BMI of less than 18.5 kg/m and weight loss (> -5%) were associated with a higher risk of grade ≥3 or higher late gastrointestinal toxicity in patients with LACC treated with definitive IMRT. Future research on the development of a standardized and structured approach to improve the therapeutic ratio for the supportive care of patients with LACC is needed.

Bismuth Oxychalcogenides: A New Class of Ferroelectric/Ferroelastic Materials with Ultra High Mobility.

Atomically thin Bi2O2Se has been recently synthesized, and it possesses ultrahigh mobility (Nat. Nanotechnol. 2017, 12, 530; Nano Lett. 2017, 17, 3021). Herein, we show first-principles evidence that Bi2O2Se and a related class of bismuth oxychalcogenides, such as Bi2O2S and Bi2O2Te, not only are novel semiconductors with ultrahigh mobility but also possess previously unreported ferroelectricity/ferroelasticity. Such a unique combination of semiconducting with ferroelectric/ferroelastic properties enables bismuth oxychalcogenides to potentially meet a great challenge, that is, integration of room-temperature functional nonvolatile memories into future nanocircuits. Specifically, we predict that bulk Bi2O2S is both ferroelastic and antiferroelectric and that a thin film with odd number of layers can even be multiferroic with nonzero in-plane polarization, and this polarization can be switchable via ferroelasticity. Moreover, Bi2O2Te possesses intrinsic out-of-plane ferroelectricity, while Bi2O2Se possesses piezoelectricity and ferroelectricity upon an in-plane strain. The in-plane strain on Bi2O2Se can induce giant polarizations (56.1 µC/cm2 upon 4.1% strain) with the piezoelectric coefficient being about 35 times higher than that of MoS2 monolayer. The in-plane strain can also enhance the bandgap or even convert indirect to direct bandgap beyond a critical value. The good match among the lattice constants of bismuth oxychalcogenides is also desirable, rendering the epitaxial growth of heterostructure devices free of fabrication issues related to lattice mismatch, thereby allowing high-quality bismuth oxychalcogenide heterostructures tailored by design for a variety of applications.

Chemically Functionalized Phosphorene: Two-Dimensional Multiferroics with Vertical Polarization and Mobile Magnetism.

In future nanocircuits based on two-dimensional (2D) materials, the ideal nonvolatile memories (NVMs) would be based on 2D multiferroic materials that can combine both efficient ferroelectric writing and ferromagnetic reading, which remain hitherto unreported. Here we show first-principles evidence that a halogen-intercalated phosphorene bilayer can be multiferroic with most long-sought advantages: its "mobile" magnetism can be controlled by ferroelectric switching upon application of an external electric field, exhibiting either an "on" state with spin-selective and highly p-doped channels, or an "off" state, insulating against both spin and electron transport, which renders efficient electrical writing and magnetic reading. Vertical polarization can be maintained against a depolarizing field, rendering high-density data storage possible. Moreover, all those functions in the halogenated regions can be directly integrated into a 2D phosphorene wafer, similar to n/p channels formed by doping in a silicon wafer. Such formation of multiferroics with vertical polarization robust against a depolarizing field can be attributed to the unique properties of covalently bonded ferroelectrics, distinct from ionic-bonded ferroelectrics, which may be extended to other van der Waals bilayers for the design of NVM in future 2D wafers. Every intercalated adatom can be used to store one bit of data: "0" when binding to the upper layer and "1" when binding to the down layer, giving rise to a possible approach of realizing single atom memory for high-density data storage.

Prophylactic lower para-aortic irradiation using intensity-modulated radiotherapy mitigates the risk of para-aortic recurrence in locally advanced cervical cancer: A 10-year institutional experience.

OBJECTIVE: To evaluate the effects of prophylactic sub-renal vein radiotherapy (SRVRT) using intensity-modulated radiotherapy (IMRT) for cervical cancer. METHODS: A total of 206 patients with FIGO stage IB2-IVA cervical cancer and negative para-aortic lymph nodes (PALNs) who underwent pelvic IMRT (PRT) or SRVRT between 2004 and 2013 at our institution were reviewed. SRVRT cranially extended the PRT field for PALNs up to the left renal vein level. The prescribed dose was consistent 50.4Gy in 28 fractions. RESULTS: Overall, 110 and 96 patients underwent PRT and SRVRT, respectively. The SRVRT group had more advanced disease based on FIGO stage and positive pelvic lymph nodes (PLNs). The median follow-up time was 60months (range, 7-143). For the total study population, the 5-year PALN recurrence-free survival (PARFS) and overall survival (OS) for PRT vs. SRVRT were 87.6% vs. 97.9% (p=0.03) and 74.5% vs. 87.8% (p=0.04), respectively. In patients with FIGO III-IVA or positive PLNs, the 5-year PARFS and OS for PRT vs. SRVRT were 80.1% vs. 96.4% (p=0.02) and 58.1% vs. 83.5% (p=0.012), respectively. However, there were no significant differences in these outcomes for patients with FIGO IB-IIB and negative PLNs. In a multivariate analysis, only SRVRT was associated with better PARFS (HR, 0.21; 95% CI, 0.06-0.78; p=0.02). The SRVRT did not significantly increase severe late toxicities. CONCLUSION: Prophylactic SRVRT using IMRT reduced PALN recurrence with tolerable toxicities, supporting the application of risk-based radiation fields for cervical cancer.