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Scaling is a key issue for resistive switching (RS) memory before commercialization. In this letter, we reveal the impact of electrode diffusion on the device performance as the thickness of RS material scaled. Serious deterioration of on/off ratio and device yield was observed when the material thickness scaled below 3 nm. A new method of two-step electrode deposition accompanied with reoxidization process was employed to overcome this problem. Significant improvements of device performance such as forming free, low RESET current (\sim\!\!\1\ \mu\A), high on/off ratio ( > 100), and 100% device yield were achieved thereafter. [ABSTRACT FROM PUBLISHER]

Objective: The multimode ablation of liver cancer, which uses radio-frequency heating after a pre-freezing process to treat the tumor, has shown significantly improved therapeutic effects and enhanced anti-tumor immune response. Unlike open surgery, the ablated lesions remain in the body after treatment, so it is critical to assess the immediate outcome and to monitor disease status over time. Here we propose a novel tumor progression prediction method for simultaneous postoperative evaluation and prognosis analysis., Methods: We propose to leverage the intraoperative therapeutic information extracted from thermal dose distribution. For tumors with specific sensitivity reflected in medical images, different thermal doses implicitly indicate the degree of instant damage and long-term inhibition excited under specific ablation energy. We further propose a survival analysis framework for the multimode ablation treatment. It extracts carefully designed features from clinical, preoperative, intraoperative, and postoperative data, then uses random survival forest for feature selection and deep neural networks for survival prediction., Results: We evaluated the proposed methods using clinical data. The results show that our method outperforms the state-of-the-art survival analysis methods with a C-index of 0.855±0.090. The thermal dose information contributes significantly to the prediction accuracy by taking up 21.7% of the overall feature importance., Conclusion: The proposed methods have been demonstrated to be a powerful tool in tumor progression prediction of multimode ablation therapy., Significance: This kind of data-driven prognosis analysis may benefit personalized medicine and simplify the follow-up process.

An accurate temperate control is the key during multimode thermal therapy of tumor. However, the tumor tissue temperature is greatly influenced by local blood flow changes of individuals. A simple but effective method is proposed for estimation of the local blood flow and its impact on the ablation boundary temperature. The proposed model is focused on the tumor domain, namely the targeted treatment region. In the natural thawing process post tumor freezing during the therapy, the main energy transferring to the tumor tissue comes from the blood flow of the surrounding normal tissue on the tumor boundary. By fitting the rewarming temperature measured in the tissue, the inversed problem is solved by the model to calculate the boundary convection condition and thus to predict the corresponding blood perfusion rate. The model is validated by the animal experimental data. The calculated blood perfusion rates are within the published range, but differ individually. The results prove that the new model and the estimated personalized convection coefficient can better predict the tissue temperature distribution during the therapy.Clinical Relevance-The model estimates the local blood flows around the tumor of individuals and the influence on heat transfer process. It can be used to better predict and control the temperature on the tumor boundary during the therapy that is critical to the therapeutic effect. The model also greatly cuts down the calculation time which facilitates the possibility of intraoperative real time monitoring.

This study proposed a control strategy of the ablation margin using the temperature of the probe, without causing additional damage. Compared with other methods, the proposed strategy is real time and impedance-ignored, thus has a better performance in practice. A theoretical model was established to obtain the temperature distribution during the treatment. Several functions were obtained by fitting the results of the simulation model, with which a preset central temperature curve corresponding to a desired ablation zone was determined to regulate the temperature of the control point. Considering the various impedances in practice, a voltage adjustment method according to the error between the preset central temperature and the practical central temperature was proposed to minimize the effect of impedances. At last, the strategy was verified with phantom experiments. The results show that all the temperatures of the control points reached to 50°C at a specific time and kept for a while, which demonstrated the strategy had a good performance within the error range allowed.

Numerical simulations provide effective way to acquire detailed temperature field during radiofrequency ablation (RF). Based on the patient's real electrical resistance and RF power, we have designed a theoretical model suitable for clinical treatment planning. The human body is assumed to be two cylinders with the inner cylinder simulating the liver with real liver electrical conductivity, while the electrical conductivity of the out cylinder adjusted to match the real resistance recorded when treated with RFA. The orthogonal-array method has been applied to analyze the impact of the main geometric parameters. Results show that a limited range of model parameters with the same resistance and power condition results in similar prediction of ablation range. In addition, RF heating experiments have been performed in the liver of a live pig to validate this model. The simulated temperature fits well with the real temperature. The comparison of the results predicted using the proposed model and previous models finds that the previous uniform-electrical-conductivity model would significantly underestimates or overestimates the ablation range based on the magnitude of the electrical resistance recorded.

The stabilization of the resistive switching characteristics is important to resistive random access memory (RRAM) device development. In this paper, an alternative approach for improving resistive switching characteristics in ZrO(2)-based resistive memory devices has been investigated. Compared with the Cu/ZrO(2)/Pt structure device, by embedding a thin TiO(x) layer between the ZrO(2) and the Cu top electrode, the Cu/TiO(x)-ZrO(2)/Pt structure device exhibits much better resistive switching characteristics. The improvement of the resistive switching characteristics in the Cu/TiO(x)-ZrO(2)/Pt structure device might be attributed to the modulation of the barrier height at the electrode/oxide interfaces.