Bi2O2Se-based CBRAM integrated artificial synapse.

Integrating two-dimensional (2D) semiconducting materials into memristor structures has paved the way for emerging 2D materials to be employed in a vast field of memory applications. Bismuth oxyselenide (Bi2O2Se), a 2D material with high electron mobility, has attracted significant research interest owing to its great potential in various fields of advanced applications. Here, we explore the out-of-plane intrinsic switching behavior of few-layered Bi2O2Se via a cross point device for application in conductive bridge random access memory (CBRAM) and artificial synapses for neuromorphic computing. Via state-of-the-art methods, CVD-grown Bi2O2Se nanoplate is applied as a switching material (SM) in an Al/Cu/Bi2O2Se/Pd CBRAM structure. The device exhibits ∼90 consecutive DC cycles with a tight distribution of the SET/RESET voltages under a compliance current (CC) of 1 mA, a retention of over 10 ks, and multilevel switching characteristics showing four distinct states at Vread values of 0.1, 0.2, 0.25, and 0.3 V. Moreover, an artificial synapse is realized with potentiation and depression by modulating the conductance. The switching mechanism is explained via Cu migration through Bi2O2Se based on HRTEM analysis. The present structure shows potential for future integrated memory applications.

Bi2O2Se-Based Bimode Noise Generator for the Application of Generative Adversarial Networks.

In the emerging technology, the generative aversive networks (GANs), randomness, and unpredictability of inputting noises are the keys to the uniqueness, diversity, robustness, and security of the generated images. Compared with deterministic software-based noise generation, hardware-based noise generation introduces physical entropy sources, such as electronic and photonic noises, to add unpredictability. In this study, bimode Bi2O2Se-based noise generators have been demonstrated for the application of GANs. Harnessing its ultrahigh carrier mobility, excellent air stability, marvelous optoelectronic performance, as well as the unique surface resistive switching effect and defect locations in the energy diagram, Bi2O2Se provides a good material platform to easily integrate with multiple device architectures for generating noises in different physical sources. The noise of the black current mode in a photodetector architecture and the random telegraph noise in a memristor mode were measured, characterized, compared, and analyzed. A method of Markov chain equipped with K-means clustering was carried out to calculate the discrete noise states and the transition probability matrix between them. To evaluate the generated properties of the GANs based on the hardware noise source, the inception score and Fréchet inception distance were evaluated.

Bi2O2Se-based integrated multifunctional optoelectronics.

The prominent light-matter interaction in 2D materials has become a pivotal research area that involves either an archetypal study of inherent mechanisms to explore such interactions or specific applications to assess the efficacy of such novel phenomena. With scientifically controlled light-matter interactions, various applications have been developed. Here, we report four diverse applications on a single structure utilizing the efficient photoresponse of Bi2O2Se with precisely tuned multiple optical wavelengths. First, the Bi2O2Se-based device performs the function of optoelectronic memory using UV (λ = 365 nm, 1.1 mW cm-2) for the write-in process with SiO2 as the charge trapping medium followed by a +1 V bias for read-out. Second, associative learning is mimicked with wavelengths of 525 nm and 635 nm. Third, using similar optical inputs, functions of logic gates "AND", "OR", "NAND", and "NOR" are realized with response current and resistance as outputs. Fourth is the demonstration of a 4 bit binary to the decimal converter using wavelengths of 740 nm (LSB), 595 nm, 490 nm, and 385 nm (MSB) as binary inputs and output response current regarded as equivalent decimal output. Our demonstration is a paradigm for Bi2O2Se-based devices to be an integral part of future advanced multifunctional electronic systems.

Bi2O2Se-Based True Random Number Generator for Security Applications.

The fast development of the Internet of things (IoT) promises to deliver convenience to human life. However, a huge amount of the data is constantly generated, transmitted, processed, and stored, posing significant security challenges. The currently available security protocols and encryption techniques are mostly based on software algorithms and pseudorandom number generators that are vulnerable to attacks. A true random number generator (TRNG) based on devices using stochastically physical phenomena has been proposed for auditory data encryption and trusted communication. In the current study, a Bi2O2Se-based memristive TRNG is demonstrated for security applications. Compared with traditional metal-insulator-metal based memristors, or other two-dimensional material-based memristors, the Bi2O2Se layer as electrode with non-van der Waals interface, high carrier mobility, air stability, extreme low thermal conductivity, as well as vertical surface resistive switching shows intrinsic stochasticity and complexity in a memristive true analogue/digital random number generation. Moreover, those analogue/digital random number generation processes are proved to be resilient for machine learning prediction.

Bi2O2Se-Based Memristor-Aided Logic.

The implementation of two-dimensional materials into memristor architectures has recently been a new research focus by taking advantage of their atomic thickness, unique lattice, and physical and electronic properties. Among the van der Waals family, Bi2O2Se is an emerging ternary two-dimensional layered material with ambient stability, suitable band structure, and high conductivity that exhibits high potential for use in electronic applications. In this work, we propose and experimentally demonstrate a Bi2O2Se-based memristor-aided logic. By carefully tuning the electric field polarity of Bi2O2Se through a Pd contact, a reconfigurable NAND gate with zero static power consumption is realized. To provide more knowledge on NAND operation, a kinetic Monte Carlo simulation is carried out. Because the NAND gate is a universal logic gate, cascading additional NAND gates can exhibit versatile logic functions. Therefore, the proposed Bi2O2Se-based MAGIC can be a promising building block for developing next-generation in-memory logic computers with multiple functions.

Dye-free wire-guided cannulation of the biliary tree during ERCP is associated with high success and low complication rates: outcomes in a single operator experience of 822 cases.

BACKGROUND: Deep biliary cannulation (DBC) is a prerequisite to most endoscopic retrograde cholangiopancreatographies (ERCPs). Numerous techniques have been described to maximize success and minimize ERCP-related complications, most notably post-ERCP pancreatitis. Dye-free cannulation by using guidewires with hydrophilic tips has been proposed as a technique with a high rate of success and a low rate of complications. We report the outcomes 822 consecutive ERCP procedures by using dye-free guidewire cannulation techniques. OBJECTIVE: To evaluate the success rate for DBC and rates of complications by using dye-free guidewire cannulation techniques. DESIGN: Retrospective. Consecutive ERCP procedures with intent to achieve DBC exclusively by using dye-free guidewire technique were included. Complication data on post-ERCP pancreatitis, bleeding, perforation, and cholangitis were extracted. SETTING: University. PATIENTS: Patients undergoing biliary ERCP. INTERVENTIONS: ERCP. MAIN OUTCOME MEASUREMENTS: Success, complication rates. RESULTS: Eight hundred and twenty-two ERCPs were performed on 744 patients. Five hundred and fifty-nine (68%) procedures were performed on inpatients, 263 (32%) on outpatients. DBC was successful in 801 of 822 (97%) ERCPs. In 795 of 801 (99%) ERCPs with successful DBC procedures, DBC was achieved in a dye-free fashion. Eleven patients (1.3%) developed post-ERCP pancreatitis-all cases were mild. Guidewire perforations occurred 11 times (1.3%), none required surgery. Ten of 11 patients with known or suspected (91%) guidewire perforation achieved successful DBC on repeat ERCP by the same endoscopist by using dye-free techniques. LIMITATIONS: Retrospective. CONCLUSIONS: In this large retrospective case series, a high success rate of DBC was achieved by using dye-free guidewire techniques. This technique has associated lower rates of complications in comparison to those reported earlier.

Prediction of which patients with an abnormal intraoperative cholangiogram will have a confirmed stone at ERCP.

BACKGROUND: Abnormal intraoperative cholangiogram (IOC) findings are commonly evaluated using postoperative endoscopic retrograde cholangiopancreatography (ERCP). However, abnormal IOC studies are associated with high false-positive rates. This study aimed to identify a subset of patients with abnormal IOC who would benefit from a postoperative ERCP. METHODS: This retrospective study investigated 68 patients with abnormal IOC at laparoscopic cholecystectomy (LC) who underwent postoperative ERCP at two tertiary referral centers over a 4-year period. Univariate and multivariate logistic regression analyses were performed to determine predictors of common bile duct (CBD) stones at postoperative ERCP. These predictors included: indication for LC, abnormal liver function tests, white blood cell count (WBC), amylase and lipase, abdominal ultrasound findings, and IOC findings [(1) non-passage of contrast into the duodenum, (2) single stone, (3) multiple stones, (4) dilated CBD, (5) non-visualization of the distal CBD, and (6) palpable CBD stones]. RESULTS: For all 68 patients, ERCP was successful. ERCP showed CBD stones in 36 cases (52.9%), and normal results in 32 cases (47%). On univariate and multivariate analysis, none of the variables included in this study significantly predicted stones at postoperative ERCP. CONCLUSIONS: Approximately one-half of patients with an abnormal IOC have a normal postoperative ERCP. None of the parameters evaluated in this retrospective study helped identify patients who merit further evaluation by ERCP. The argument could be made that in patients with an abnormal IOC, less invasive methods such as endoscopic ultrasound or magnetic resonance cholangiopancreatography could be used postoperatively if symptoms arise to assess for possible retained stone.

Histopathologic correlation of endoscopic ultrasound findings of chronic pancreatitis in human autopsies.

OBJECTIVES: To provide histologic correlation of endoscopic ultrasound (EUS) findings believed to represent chronic pancreatitis (CP). METHODS: Eighteen postmortem pancreatic specimens in patients dying of all causes were examined in vitro by EUS for features of CP: (1) echogenic foci, (2) hypoechoic foci, (3) echogenic main pancreatic duct (MPD), (4) accentuated lobular pattern, (5) cysts, (6) irregular MPD, (7) dilated MPD, (8) side branch dilation, and (9) calculi. The pancreata were then examined by 2 pathologists (blinded to the EUS/clinical findings) for histopathologic features of CP. RESULTS: Six specimens were autolyzed, and in 1 specimen, MPD could not be seen by EUS. In the other 11 patients, 10 had evidence of CP by EUS (> or =3 features) and by histopathologic examination (> or =2 features). One patient did not have CP by both EUS and histologic examination. CONCLUSIONS: Endoscopic ultrasound accurately detected CP, when compared with histopathologic examination. The presence of 3 or more features of CP correlates with the histologic diagnosis of CP, however, up to 3 features are frequently present in elderly patients dying of all causes. Future studies should address the clinical relevance and the specificity of EUS findings of CP in the older population.

Pure versus mixed electrosurgical current for endoscopic biliary sphincterotomy: a meta-analysis of adverse outcomes.

BACKGROUND: Endoscopic biliary sphincterotomy (ES) can cause bleeding, pancreatitis, and perforation. This has, in part, been attributed to the type of electrosurgical current used for ES. No consensus exists on the optimal type of electrosurgical current for ES to maximize safety. OBJECTIVE: To compare the rates of complications in patients undergoing ES via pure current versus mixed current. DESIGN: A systematic review of published, prospective, randomized trials that compared pure current with mixed current for ES. PATIENTS: Patients undergoing ES, with random assignment to either current group. INTERVENTIONS: Data were standardized for pancreatitis and postsphincterotomy bleeding. There were insufficient data to analyze perforation risk. A random-effects model was used. MAIN OUTCOME MEASUREMENTS: Bleeding, pancreatitis, and perforation. RESULTS: A total of 804 patients from 4 trials that compared pure current to mixed current were analyzed. The aggregated rate of pancreatitis was 3.8%, 95% confidence interval (CI) 1.0%-6.6%, for the pure-current group versus 7.9%, 95% CI 3.1%-12.7%, for the mixed-current group; the difference was not statistically significant. The rate of bleeding (all severity groups) for the pure-current group was 37.3% (95% CI 27.3%, 47.3%), which was significantly higher than that of the mixed-current group (12.2% [95% CI 4.1%, 20.3%]). Mild bleeding was significantly more frequent with pure current (28.9% [95% CI 16.3, 41.4]) compared with mixed current (9.4% [95% CI 2.1%, 16.8%]). LIMITATIONS: Variables, including endoscopist skill and cannulation difficulty, were difficult to measure. CONCLUSIONS: The rate of pancreatitis in patients who underwent ES when using pure current was not significantly different from those when using mixed current. Pure current was associated with more episodes of bleeding, primarily mild bleeding. Data were insufficient to analyze the perforation risk.

Establishing a true assessment of endoscopic competence in ERCP during training and beyond: a single-operator learning curve for deep biliary cannulation in patients with native papillary anatomy.

BACKGROUND: Deep cannulation of the common bile duct (CBD) in patients with native papillary anatomy can be used as a marker of competence at ERCP. OBJECTIVE: The primary aim of this study was to analyze a single-operator learning curve for supervised ERCPs in patients with native papillary anatomy and to assess the development of endoscopic competence, defined as the ability to deeply cannulate the CBD in the setting > or =80% of the time. Posttraining outcomes were evaluated as proof of training. DESIGN: A retrospective review: 1097 ERCP procedures were analyzed, 697 were performed during ERCP training (July 2002-July 2003), 400 were performed after training as an independent operator, 499 and 303 procedures for training and posttraining periods, respectively, were performed with the intent of deep cannulation of CBD in patients with native papillary anatomy. Procedures were chronologically grouped into subsets. Success rates were plotted against time. SETTING: Single center. MAIN OUTCOME MEASUREMENTS: Rate of successful deep biliary cannulation. RESULTS: The successful cannulation rate increased from 43% at the beginning of training to > or =80% after 350 to 400 supervised procedures. The success rate continued to improve posttraining with an aggregated success rate of >96% for the next 300 procedures performed as an independent operator. LIMITATIONS: Single operator. CONCLUSIONS: Achievement of a satisfactory success rate for deep biliary cannulation in patients with native papillary anatomy should be tracked by ERCP trainers and trainees. The consistent achievement of > or =80% success at deep biliary cannulation in such patients should become a standard for ERCP training programs to produce skilled and competent therapeutic biliary endoscopists.

Adenocarcinoma of the small bowel: a 60-yr perspective derived from M. D. Anderson Cancer Center Tumor Registry.

OBJECTIVES: To analyze subsite distribution of small bowel adenocarcinoma (SBA) over a 60-yr interval and to determine the impact of age, gender, and ethnicity on SBA cross-referenced for selected variables including anatomic distribution. METHODS: Data from 1944 to 2003 were extracted from the M. D. Anderson Cancer Center Tumor Registry (MDACCTR) and analyzed by age, gender, ethnicity, anatomic site, and time intervals. RESULTS: A total of 523 confirmed cases with 460 specified for subsite were identified. Peak incidence occurred in the sixth decade with male predominance (58%). Relative distribution for subsites was stable over the period of study; however, site-specific incidence differed significantly with age. Although jejunal SBA comprised only 21% of site-specific total (SST), 49% occurred in 0-49 age group rendering duodenal SBA (59% of SST) more common with increasing age (p < 0.001). A higher percentage of women presented at younger age; however, the difference was not significant (p = 0.061). Subsite distribution was similar for both genders, but varied significantly among ethnicities (p = 0.048) with Hispanics and African Americans having a higher percentage of duodenal SBA. The age and gender distribution among ethnicities varied significantly. African Americans having SBA presented at a younger age (p < 0.001), and comprised a higher percentage of women (p = 0.026). CONCLUSION: Differences exist for SBA subsite distribution within age and ethnic groups but not gender. Unlike colon cancer, SBA subsite distribution has been stable during the last six decades. Different risk factors for SBA appear to affect different subsites. Site- and age-related distribution impacts on diagnostic evaluation for SBA.

EUS vs MRCP for detection of choledocholithiasis.

BACKGROUND: Numerous published studies have shown the high diagnostic performance of both EUS and MRCP compared with ERCP for the detection of choledocholithiasis. DESIGN: We undertook a systematic review of all published randomized, prospective trials that compared EUS with MRCP with the primary aim being to compare the overall diagnostic accuracy for the detection of choledocholithiasis in patients with suspected biliary disease. METHODS: A MEDLINE review was performed. We identified 5 randomized, prospective, blinded trials comparing MRCP and EUS for the detection of choledocholithiasis, with subsequent ERCP or intraoperative cholangiography as a criterion standard. The study-specific variables for EUS and MRCP for choledocholithiasis were calculated from the data, and analyses were performed by using aggregated variables (sensitivity, specificity, positive and negative predictive values, and likelihood ratios). RESULTS: The pooled data set consisted of 301 patients. The aggregated sensitivities of EUS and MRCP for the detection of choledocholithiasis were 0.93 and 0.85, respectively, whereas their specificities were 0.96 and 0.93, respectively. The aggregated positive predictive values for EUS and MRCP were 0.93 and 0.87, respectively, with the corresponding negative predictive values of 0.96 and 0.92, respectively. Positive likelihood ratios were >10 for both tests, and corresponding negative likelihood ratios approached 0.10 for both tests. No statistically significant differences between EUS and MRCP were found in our analysis. CONCLUSIONS: EUS and MRCP have high diagnostic performance overall. Our analysis showed no statistically significant difference between the modalities. We recommend taking into consideration other factors, such as resource availability, experience, and cost considerations in deciding between these 2 tests.

Can U.S. GI fellowship programs meet American Society for Gastrointestinal Endoscopy recommendations for training in EUS? A survey of U.S. GI fellowship program directors.

BACKGROUND: American Society for Gastrointestinal Endoscopy (ASGE) EUS training and credentialing guidelines exist, but the capability of U.S. GI fellowships to meet these guidelines has not been assessed. OBJECTIVE: To ascertain the capability of U.S. GI fellowship programs to meet ASGE guidelines for EUS training in the context of 3-year and advanced GI fellowships. METHODS: U.S. GI fellowship programs were surveyed for the presence or the absence, type, and extent of EUS training. Demographics regarding the programs and the program directors were obtained. MAIN OUTCOME MEASUREMENTS: Data on the annual total EUS volume and data on EUS performed by 3-year and/or advanced-year fellows were collected and analyzed. RESULTS: Ninety-one of 142 contactable GI programs responded (64%); 72% of programs performed >200 EUS/y and thus could train >or=1 EUS trainee/y. For 3-year GI fellows, 55% received less than 3 months of training, with 43% not receiving actual "hands-on" EUS experience, and 61% not learning EUS-guided FNA. The median EUS performed by 3-year fellows was 50 (0-350). Programs that offer advanced endoscopy fellowship had a median advanced-trainee EUS volume of 200 procedures (range, 50-1100 procedures). Of advanced fellows, 20% failed to receive "hands-on" training and 52% performed <200 procedures. We observed a significant difference in the median EUS volume performed by 3-year versus advanced-year fellows (P<.001). Program director variables did not correlate with training EUS volumes. CONCLUSIONS: The majority of U.S. GI fellowship programs have established the EUS volume to train at least 1 EUS fellow, per ASGE guidelines; however, most 3-year and many advanced fellows are currently receiving insufficient EUS training.