Upfront Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy in Elderly Patients with Brain Metastases from Non-small cell lung cancer: A Retrospective Analysis of a 10-Year Bi-Institutional Experience.

Purpose: Stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) are increasingly used as initial therapies for brain metastases (BM). We aimed to assess the outcomes of SRS/FSRT in patients aged ≥65 years who had 1-10 BM from non-small cell lung cancer (NSCLC). Materials and Methods: We retrospectively reviewed 91 elderly NSCLC patients with 222 BM who were treated with SRS/FSRT at two institutions between 2010 and 2020. The primary endpoint was overall survival (OS) after SRS/FSRT. In addition, in-field local control (IFLC) within the treated field was evaluated. Statistical analysis was performed to identify the prognostic factors affecting OS and IFLC. Results: During a median follow-up of 18 months, the median OS was 32 months. The 1- and 2-year survival rates were 69.8 and 56.1%, respectively. In multivariate analysis, the NSCLC-specific graded prognostic assessment (GPA) score (p=0.007) and administration of systemic therapy (p=0.039) were defined as prognosticators affecting OS. The median IFLC period was 31 months, and the 1- and 2-year IFLC rates were 75.9 and 57.6%, respectively. The total BM volume (p=0.042) significantly affected IFLC. No severe adverse events were reported after SRS/FSRT. Conclusion: SRS/FSRT is an effective upfront treatment option for BM arising from NSCLC in elderly patients, with a good OS without severe side effects. Higher GPA score and active systemic treatment were associated with improved OS, indicating that elderly patients are significant candidates for SRS/FSRT.

Correction: Sung et al. Linear Tumor Regression of Rectal Cancer in Daily MRI during Preoperative Chemoradiotherapy: An Insight of Tumor Regression Velocity for Personalized Cancer Therapy. Cancers 2022, 14, 3749.

In the original publication [...].

Ceramic Aneurysm Clip with Titanium Spring.

OBJECTIVE: To design and evaluate ceramic aneurysm clips with integrated titanium springs, focusing on ergonomic application and precision in neurosurgical procedures. METHODS: The clip design was executed with precision using Creo Parametric 3D CAD software. It comprises a zirconia body and a titanium spring for durability and consistent tension and features a four-coil hairpin titanium spring for enhanced closing force and a ball-type head for versatile maneuverability during surgery. To assess durability, closing forces were rigorously measured using a force gauge system, comparing the ceramic clip with the standard Mizuho permanent clip over 30 open-close cycles. For the assessment of magnetic resonance (MR) artifacts, both the ceramic and Yasargil clips were evaluated using a 3 Tesla (T) MRI scanner, employing specific imaging sequences. RESULTS: The straight type ceramic clip's initial closing force was 1.70 N, dropping to 1.22 N after 30 cycles, indicating a retention of 72% of its initial force. In MRI, the ceramic clip displayed significantly lower measurement discrepancies compared to the titanium alloy Yasargil clip, particularly in high-resolution T1-weighted images. The lowest variance was at measurement point L2, where the ceramic clip showed a 3% discrepancy. Furthermore, the ceramic clip yielded clearer images than the titanium alloy clip, particularly at the clip's end. CONCLUSIONS: Ceramic clips with titanium springs demonstrated satisfactory closing force and superior MRI compatibility, promising enhancements in surgical application and postoperative assessment.

Multiple telescopic stenting versus single flow diverter for the treatment of vertebral artery dissecting aneurysm.

Objective: Reconstruction methods, including stent-assisted coiling, multiple telescopic stents, and flow diverters, are preferred modalities for the treatment of unruptured vertebral artery dissecting aneurysms (VADAs). We aimed to compare the clinical outcomes between two reconstructive flow diversion techniques: single flow diverter (FD) device and multiple telescopic stenting (TS). Methods: We retrospectively reviewed the clinical data of 39 patients with unruptured VADAs. Of these, 17 patients were treated with multiple TS and 22 with a single FD device. Aneurysm characteristics and clinical outcomes were compared between the two groups. Results: All aneurysms included in this study successfully achieved flow diversion, regardless of the treatment modality and duration. However, the mean procedure duration to complete the diversion was shorter in the FD group. Subgroup analysis in TS group showed that there were no significant clinical differences between the low-profile visualized intraluminal support and Enterprise stents, except for the mean procedure duration. Conclusions: Both the single FD and multiple TS methods showed excellent angiographic and clinical outcomes in the treatment of unruptured VADAs. However, single FD required a shorter procedure duration and was associated with faster achievement of complete flow diversion.

Anterior Choroidal Artery Aneurysm Clipping: Angiographic Diagnostics and Surgical Tactics Focused on Visualizing the Anterior Choroidal Artery Behind the Aneurysm.

OBJECTIVE: This study describes our experiences with anterior choroidal artery (AChA) aneurysm clipping with a focus on visualizing the AChA just behind the aneurysm to identify the risk factors for adhesion of the AChA or its branches to the posterior wall of the AChA aneurysm. METHODS: The initial segment of the AChA just behind the aneurysm was evaluated preoperatively using three-dimensional (3D) rotational angiography, and its course was designated as posteromedial, posterior, or posterolateral. The posterior aspect of the AChA aneurysm was inspected intraoperatively using an endoscope or micromirror. RESULTS: Based on 3D rotational angiography, the main trunk of the AChA showed a posteromedial (n = 47, 57.3%), posterior (n = 18, 22.0%), or posterolateral (n = 17, 20.7%) course just behind the aneurysm. Intraoperatively, 14.6% (12 of 82) of the clipped AChA aneurysms revealed an AChA branch adhered to the posterior wall of the aneurysm. A multivariate analysis revealed that the posterior or posterolateral course of the initial segment of the AChA was a statistically significant risk factor for adhesion of an AChA branch to the posterior wall of the aneurysm (odds ratio [OR] 21.083, 95% confidence interval [CI] 2.567-173.166, P = 0.005). CONCLUSIONS: The initial course of the AChA just behind an AChA aneurysm can be evaluated using 3D rotational angiography. In contrast to a posteromedial course, a posterior or posterolateral course of the AChA just behind an AChA aneurysm can be a significant risk factor for adhesion of an AChA branch to the posterior wall of an AChA aneurysm.

Alterations in Plasma Lipid Profile before and after Surgical Removal of Soft Tissue Sarcoma.

Soft tissue sarcoma (STS) is a relatively rare malignancy, accounting for about 1% of all adult cancers. It is known to have more than 70 subtypes. Its rarity, coupled with its various subtypes, makes early diagnosis challenging. The current standard treatment for STS is surgical removal. To identify the prognosis and pathophysiology of STS, we conducted untargeted metabolic profiling on pre-operative and post-operative plasma samples from 24 STS patients who underwent surgical tumor removal. Profiling was conducted using ultra-high-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry. Thirty-nine putative metabolites, including phospholipids and acyl-carnitines were identified, indicating changes in lipid metabolism. Phospholipids exhibited an increase in the post-operative samples, while acyl-carnitines showed a decrease. Notably, the levels of pre-operative lysophosphatidylcholine (LPC) O-18:0 and LPC O-16:2 were significantly lower in patients who experienced recurrence after surgery compared to those who did not. Metabolic profiling may identify aggressive tumors that are susceptible to lipid synthase inhibitors. We believe that these findings could contribute to the elucidation of the pathophysiology of STS and the development of further metabolic studies in this rare malignancy.

Successive Development and Rupture of Blister-Like Anterior Communicating Artery Aneurysms at Mirror Locations.

This is the first report of the successive development and rupture of blister-like anterior communicating artery (ACoA) aneurysms at mirror locations with a short interval. A 49-year-old man presented with an angiogram-negative subarachnoid hemorrhage with significant basal frontal interhemispheric blood. Surgical exploration revealed a blister-like aneurysm on the left side of the superior wall of the ACoA, which was treated using a microsuturing technique. On the 18th day after the initial subarachnoid hemorrhage, the second operation due to another angiogram-negative hemorrhage revealed a de novo blister-like aneurysm with a small blood clot on the posterosuperior wall of the ACoA close to the right A1/A2 junction. The rupture point and ACoA on the right side were occluded using an aneurysm clip. Follow-up digital subtraction angiogram (DSA) at 4 years and computed tomography angiogram (CTA) at 14 years after the surgery showed no recurrence or associated abnormality.

Preservation of the middle meningeal artery during unruptured aneurysm surgery: an independent risk factor for postoperative chronic subdural hematoma.

Background: Although microsurgical clipping for unruptured aneurysms has become safer and more efficient with modern neurosurgical advances, postoperative chronic subdural hematoma (CSDH) persists as an underrecognized complication. This study investigated the association between preservation of the anterior branch of the middle meningeal artery (MMA) during surgery and CSDH development. Methods: We retrospectively reviewed 120 patients who underwent clipping for unruptured aneurysms at Kyungpook National University Chilgok Hospital between May 2020 and July 2023. We evaluated the patients on the basis of surgical approach-lateral supraorbital (LSO) or standard pterional craniotomy-and the status of the MMA postoperatively. We employed pre-and post-operative MR angiography to assess MMA preservation and used follow-up computed tomography scans to monitor CSDH development. Results: Of the 120 patients, 22 (18.3%) developed CSDH. Univariate analysis revealed that male sex, advanced age, and MMA preservation are risk factors for postoperative CSDH. Multivariate analysis supported these findings, indicating a significant association with the development of CSDH. MMA preservation was reported in 65 patients, of whom 60 and 5 underwent LSO and pterional craniotomy, respectively. Conclusion: Preservation of the anterior branch of the MMA during unruptured aneurysm surgery is a risk factor for postoperative CSDH development. Advanced age and male sex also contribute to the increased risk. These findings highlight the need for further investigation into surgical techniques that could mitigate postoperative CSDH development.

The impact of boost radiation therapy after hysterectomy on cervical cancer patients with close or positive resection margins

Purpose We investigated the effect of boost radiation therapy (RT) in addition to whole pelvis RT (WPRT) on treatment outcome and safety of cervical cancer patients following hysterectomy with close/positive resection margins (RM). Methods We retrospectively analyzed 51 patients with cervical cancer who received WPRT with or without boost-RT as adjuvant treatment between July 2006 and June 2022. Twenty patients (39.2%) were treated with WPRT-alone, and 31 (60.8%) received boost-RT after WPRT using brachytherapy or intensity-modulated RT. Results The median follow-up period was 41 months. According to RT modality, the 4-year local control (LC) and locoregional control (LRC) rates of patients treated with WPRT-alone were 61% and 61%, respectively, whereas those in LC and LRC rates in patients who underwent WPRT with boost-RT were 93.2% and 75.3%, with p-values equal to 0.005 and 0.090, respectively. Seven patients (35.0%) had local recurrence in the WPRT-treated group compared to only two out of the 31 patients (6.5%) in the WPRT with boost-RT-treated counterparts (p = 0.025). Boost-RT was a significantly good prognostic factor for LC (p = 0.013) and LRC (p = 0.013). Boost-RT did not result in statistically-significant improvements in progression-free survival or overall survival. The acute and late toxicity rates were not significantly different between groups. Conclusion Boost RT following WPRT is a safe and effective treatment strategy to improve LC without increasing toxicity in patients with cervical cancer with close/positive RM after hysterectomy (AU)

Volatile and Nonvolatile Resistive Switching Coexistence in Conductive Point Hexagonal Boron Nitride Monolayer.

Recently, we demonstrated the nonvolatile resistive switching effects of metal-insulator-metal (MIM) atomristor structures based on two-dimensional (2D) monolayers. However, there are many remaining combinations between 2D monolayers and metal electrodes; hence, there is a need to further explore 2D resistance switching devices from material selections to future perspectives. This study investigated the volatile and nonvolatile switching coexistence of monolayer hexagonal boron nitride (h-BN) atomristors using top and bottom silver (Ag) metal electrodes. Utilizing an h-BN monolayer and Ag electrodes, we found that the transition between volatile and nonvolatile switching is attributed to the thickness/stiffness of chain-like conductive bridges between h-BN and Ag surfaces based on the current compliance and atomristor area. Computations indicate a "weak" bridge is responsible for volatile switching, while a "strong" bridge is formed for nonvolatile switching. The current compliance determines the number of Ag atoms that undergo dissociation at the electrode, while the atomristor area determines the degree of electric field localization that forms more stable conductive bridges. The findings of this study suggest that the h-BN atomristor using Ag electrodes shows promise as a potential solution to integrate both volatile neurons and nonvolatile synapses in a single neuromorphic crossbar array structure through electrical and dimensional designs.

The impact of boost radiation therapy after hysterectomy on cervical cancer patients with close or positive resection margins.

PURPOSE: We investigated the effect of boost radiation therapy (RT) in addition to whole pelvis RT (WPRT) on treatment outcome and safety of cervical cancer patients following hysterectomy with close/positive resection margins (RM). METHODS: We retrospectively analyzed 51 patients with cervical cancer who received WPRT with or without boost-RT as adjuvant treatment between July 2006 and June 2022. Twenty patients (39.2%) were treated with WPRT-alone, and 31 (60.8%) received boost-RT after WPRT using brachytherapy or intensity-modulated RT. RESULTS: The median follow-up period was 41 months. According to RT modality, the 4-year local control (LC) and locoregional control (LRC) rates of patients treated with WPRT-alone were 61% and 61%, respectively, whereas those in LC and LRC rates in patients who underwent WPRT with boost-RT were 93.2% and 75.3%, with p-values equal to 0.005 and 0.090, respectively. Seven patients (35.0%) had local recurrence in the WPRT-treated group compared to only two out of the 31 patients (6.5%) in the WPRT with boost-RT-treated counterparts (p = 0.025). Boost-RT was a significantly good prognostic factor for LC (p = 0.013) and LRC (p = 0.013). Boost-RT did not result in statistically-significant improvements in progression-free survival or overall survival. The acute and late toxicity rates were not significantly different between groups. CONCLUSION: Boost RT following WPRT is a safe and effective treatment strategy to improve LC without increasing toxicity in patients with cervical cancer with close/positive RM after hysterectomy.

Assessment of deep learning-based auto-contouring on interobserver consistency in target volume and organs-at-risk delineation for breast cancer: Implications for RTQA program in a multi-institutional study.

PURPOSE: To quantify interobserver variation (IOV) in target volume and organs-at-risk (OAR) contouring across 31 institutions in breast cancer cases and to explore the clinical utility of deep learning (DL)-based auto-contouring in reducing potential IOV. METHODS AND MATERIALS: In phase 1, two breast cancer cases were randomly selected and distributed to multiple institutions for contouring six clinical target volumes (CTVs) and eight OAR. In Phase 2, auto-contour sets were generated using a previously published DL Breast segmentation model and were made available for all participants. The difference in IOV of submitted contours in phases 1 and 2 was investigated quantitatively using the Dice similarity coefficient (DSC) and Hausdorff distance (HD). The qualitative analysis involved using contour heat maps to visualize the extent and location of these variations and the required modification. RESULTS: Over 800 pairwise comparisons were analysed for each structure in each case. Quantitative phase 2 metrics showed significant improvement in the mean DSC (from 0.69 to 0.77) and HD (from 34.9 to 17.9 mm). Quantitative analysis showed increased interobserver agreement in phase 2, specifically for CTV structures (5-19 %), leading to fewer manual adjustments. Underlying IOV differences causes were reported using a questionnaire and hierarchical clustering analysis based on the volume of CTVs. CONCLUSION: DL-based auto-contours improved the contour agreement for OARs and CTVs significantly, both qualitatively and quantitatively, suggesting its potential role in minimizing radiation therapy protocol deviation.

A Real-World Comparative Analysis of Atezolizumab Plus Bevacizumab and Transarterial Chemoembolization Plus Radiotherapy in Hepatocellular Carcinoma Patients with Portal Vein Tumor Thrombosis.

This study aimed to compare the treatment outcomes of atezolizumab-plus-bevacizumab (Ate/Bev) therapy with those of transarterial chemoembolization plus radiotherapy (TACE + RT) in hepatocellular carcinoma (HCC) patients with portal vein tumor thrombosis (PVTT) and without metastasis. Between June 2016 and October 2022, we consecutively enrolled 855 HCC patients with PVTT. After excluding 758 patients, 97 patients (n = 37 in the Ate/Bev group; n = 60 in the TACE + RT group) were analyzed. The two groups showed no significant differences in baseline characteristics and had similar objective response and disease control rates. However, the Ate/Bev group showed a significantly higher one-year survival rate (p = 0.041) compared to the TACE + RT group, which was constantly displayed in patients with extensive HCC burden. Meanwhile, the clinical outcomes were comparable between the two groups in patients with unilobar intrahepatic HCC. In Cox-regression analysis, Ate/Bev treatment emerged as a significant factor for better one-year survival (p = 0.049). Finally, in propensity-score matching, the Ate/Bev group demonstrated a better one-year survival (p = 0.02) and PFS (p = 0.01) than the TACE + RT group. In conclusion, Ate/Bev treatment demonstrated superior clinical outcomes compared to TACE + RT treatment in HCC patients with PVTT. Meanwhile, in patients with unilobar intrahepatic HCC, TACE + RT could also be considered as an alternative treatment option alongside Ate/Bev therapy.

Unexpected shunt-dependent hydrocephalus after unruptured aneurysm surgery-a case report.

A chronic hydrocephalus after unruptured aneurysm surgery is an extremely rare condition. Its etiology and pathophysiology are also unclear. We report a case of chronic hydrocephalus in a patient who underwent permanent shunt placement after unruptured aneurysm clipping surgery. A 65-year-old man developed chronic hydrocephalus requiring shunt placement after clipping surgery of left anterior cerebral artery aneurysm and right middle cerebral artery aneurysm. This case shows that chronic hydrocephalus is a possible complication of unruptured aneurysm surgery, which can be resolved with an appropriate shunt operation.

Reduced volume intensity-modulated radiotherapy with simultaneous integrated boost for patients with high-grade glioma: A retrospective observational study.

Radiotherapy (RT) is an essential treatment for patients with high-grade gliomas. however, a consensus on the target area of RT has not yet been achieved. In this study, we aimed to analyze progression-free survival (PFS), recurrence patterns, and toxicity in patients who received reduced volume intensity-modulated radiotherapy with simultaneous integrated boost (rvSIB-IMRT). In addition, we attempted to identify prognostic factors for recurrence. Twenty patients with high-grade gliomas who received rvSIB-IMRT between July 2011 and December 2021 were retrospectively analyzed. For rvSIB-IMRT, clinical target volume 1/2 was set at a 5 to 10 mm margin on each gross tumor volume (GTV) 1 (resection cavity and enhanced lesion) and GTV2 (high-signal lesion of T2/fluid-attenuated inversion recovery). RT doses were prescribed to 60 Gy/30 fractions (fxs) for planning target volume (PTV)1 and 51 to 54 Gy/30 fxs for PTV2. The median PFS and overall survival of the total cohorts were 10.6 and 13.6 months, respectively. Among the 12 relapsed patients, central, in-field, and marginal recurrences were identified in 8 (66.7%), 2 (16.7%), and 1 patient (8.3%), respectively. Distant recurrence was identified in 3 patients. Gross total resection (GTR) and high Ki-67 index (>27.4%), and subventricular involvement (SVI) were identified as significant factors for PFS in the multivariate analysis. During the follow up, 4 patients showed pseudoprogression and 1 patient showed radiation necrosis. The rvSIB-IMRT for high-grade gliomas resulted in comparable PFS and tolerable toxicity. Most recurrences were central/in-field (10 cases of 12, 83.4%). GTR, high Ki-67 index (>27.4%), and SVI were significant factors for recurrence.

Efficacy of Liver-Directed Combined Radiotherapy in Locally Advanced Hepatocellular Carcinoma with Portal Vein Tumor Thrombosis.

PURPOSE: Although systemic treatment is the mainstay for advanced hepatocellular carcinoma (HCC), numerous studies have highlighted the added value of local treatment. This study aimed to investigate the clinical efficacy of liver-directed combined radiotherapy (LD combined RT) compared with that of sorafenib, a recommended treatment until recently for locally advanced HCC presenting portal vein tumor thrombosis (PVTT), using a multinational patient cohort. MATERIALS AND METHODS: We identified patients with HCC presenting PVTT treated with either sorafenib or LD combined RT in 10 tertiary hospitals in Asia from 2005 to 2014. Propensity score matching (PSM) was performed to minimize the imbalance between the two groups. The primary endpoint was overall survival (OS), and the secondary endpoints were progression-free survival (PFS) and treatment-related toxicity. RESULTS: A total of 1035 patients (675 in the LD combined RT group and 360 in the sorafenib group) were included in this study. After PSM, 305 patients from each group were included in the analysis. At a median follow-up of 22.5 months, the median OS was 10.6 and 4.2 months for the LD combined RT and sorafenib groups, respectively (p < 0.001). The conversion rate to curative surgery was significantly higher (8.5% vs. 1.0%, p < 0.001), while grade ≥ 3 toxicity was fewer (9.2% vs. 16.1%, p < 0.001) in the LD combined RT group. CONCLUSIONS: LD combined RT improved survival outcomes with a higher conversion rate to curative surgery in patients with locally advanced HCC presenting PVTT. Although further prospective studies are warranted, active multimodal local treatment involving radiotherapy is suggested for locally advanced HCC presenting PVTT.

Re-Irradiation with Intensity-Modulated Radiation Therapy for the Treatment of Recurrent Cervical Cancer in the Pelvis: An Analysis of Outcomes and Toxicity.

Background and Objectives: Treatment options for most patients with recurrent cervical cancer within the previously irradiated field are limited. This study aimed to investigate the feasibility and safety of re-irradiation using intensity-modulated radiation therapy (IMRT) for patients with cervical cancer who experienced intrapelvic recurrence. Materials and Methods: We retrospectively analyzed 22 patients with recurrent cervical cancer who were treated with re-irradiation for intrapelvic recurrence using IMRT between July 2006 and July 2020. The irradiation dose and volume were determined based on the range considered safe for the tumor size, location, and previous irradiation dose. Results: The median follow-up period was 15 months (range: 3-120) and the overall response rate was 63.6%. Of the symptomatic patients, 90% experienced symptom relief after treatment. The 1- and 2-year local progression-free survival (LPFS) rates were 36.8% and 30.7%, respectively, whereas the 1- and 2-year overall survival (OS) rates were 68.2% and 25.0%, respectively. Multivariate analysis revealed that the interval between irradiations and gross tumor volume (GTV) were significant prognostic factors for LPFS. The response to re-irradiation showed borderline statistical significance for LPFS. The GTV and response to re-irradiation were also independent prognostic factors for OS. Grade 3 late toxicities were observed in 4 (18.2%) of the 22 patients. Recto- or vesico-vaginal fistula occurred in four patients. The irradiation dose was associated with fistula formation with borderline significance. Conclusions: Re-irradiation using IMRT is a safe and effective treatment strategy for patients with recurrent cervical cancer who previously received RT. Interval between irradiations, tumor size, response to re-irradiation, and radiation dose were the main factors affecting efficacy and safety.

Non-endometrioid endometrial cancer: analysis of recurrence pattern and identification of prognostic and treatment factors affecting recurrence and survival.

PURPOSE: We investigated the characteristics of recurrence pattern and survival of patients with non-endometrioid endometrial cancer (NEEC) and attempted to identify prognostic and treatment factors affecting disease-free survival (DFS) and overall survival (OS) of these patients. METHODS: Fifty-seven patients with histologically confirmed International Federation of Gynecology and Obstetrics (FIGO) stage IA-IVA NEEC from February 2003 to December 2021 were retrospectively analyzed. RESULTS: The 5­year DFS and OS rates of the total cohort were 50.6% and 56.1%, respectively. Recurrence occurred in 28 patients (49.1%) during follow-up, and the most common recurrence pattern was distant metastasis (DM; 78.6% of total recurrences). The occurrence of relapse significantly reduced 5­year OS (recurrence group vs. non-recurrence group: 12.5% vs. 100%; p < 0.001). In univariate analysis, adjuvant radiotherapy (RT) group showed significantly higher 5­year DFS (56.7% vs. 37.9%; p = 0.04), local recurrence-free survival (91.6% vs. 50.5%; p = 0.01), and regional recurrence-free survival (88.2% vs. 56.5%; p < 0.01) than the non-RT group. In multivariate analysis, advanced FIGO stage was identified as a negative prognostic factor for DFS and OS. Lymphovascular space invasion (LVSI) and adjuvant RT were independent prognostic factors for DFS. CONCLUSION: The most common recurrence pattern observed in patients with NEEC was DM. FIGO stage and LVSI were identified as prognostic factors for survival, and RT was identified as a therapeutic modality that could increase DFS. To improve the OS of patients with NEEC, the addition of effective chemotherapy that can reduce DM may be important.

Reconfigurable Low-Voltage Hexagonal Boron Nitride Nonvolatile Switches for Millimeter-Wave Wireless Communications.

Recently, nonvolatile resistive switching memory effects have been actively studied in two-dimensional (2D) transition metal dichalcogenides and boron nitrides to advance future memory and neuromorphic computing applications. Here, we report on radiofrequency (RF) switches utilizing hexagonal boron nitride (h-BN) memristors that afford operation in the millimeter-wave (mmWave) range. Notably, silver (Ag) electrodes to h-BN offer outstanding nonvolatile bipolar resistive switching characteristics with a high ON/OFF switching ratio of 1011 and low switching voltage below 0.34 V. In addition, the switch exhibits a low insertion loss of 0.50 dB and high isolation of 23 dB across the D-band spectrum (110 to 170 GHz). Furthermore, the S21 insertion loss can be tuned through five orders of current compliance magnitude, which increases the application prospects for atomic switches. These results can enable the switch to become a key component for future reconfigurable wireless and 6G communication systems.