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Soon after diagnosis with type 1 diabetes (T1D), many patients experience a period of partial remission. A longer partial remission is associated with a better response to treatment, but the mechanism is not known. The frequency of CD4+CD25+CD127hi (127-hi) cells, a cell subset with an anti-inflammatory Th2 bias, correlates positively with length of partial remission. The purpose of this study was to further characterize the nature of the Th2 bias in 127-hi cells. Single cell RNA sequencing paired with TCR sequencing of sorted 127-hi memory cells identifies clonally expanded Th2 clusters in 127-hi cells from T1D, but not from healthy donors. The Th2 clusters express GATA3, GATA3-AS1, PTGDR2, IL17RB, IL4R and IL9R. The existence of 127-hi Th2 cell clonal expansion in T1D suggests that disease factors may induce clonal expansion of 127-hi Th2 cells that prolong partial remission and delay disease progression.
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Diabetes Mellitus Tipo 1 , Células Th2 , Humanos , Diabetes Mellitus Tipo 1/genéticaRESUMO
A library of 34 lipophilic sulfonamides based upon the memantine core has been synthesized to identify potential drug candidates to cross the blood-brain barrier and target glioblastoma. The library was screened for inâ vitro activity against 4 mammalian cell lines, including U-87 (glioblastoma). Additional synthetic variation of the active compounds has validated the importance of specific regions of the pharmacophore, with the sulfonamide functionality and S-aryl unit displaying the most significant impact. In silico investigations suggest the active compounds might target DDR1 or RET proteins. The investigation has resulted in several compounds that warrant further development for lead optimization.
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Antineoplásicos , Glioblastoma , Animais , Humanos , Glioblastoma/tratamento farmacológico , Memantina/farmacologia , Memantina/uso terapêutico , Sulfonamidas , Barreira Hematoencefálica , Transporte Biológico , Relação Estrutura-Atividade , MamíferosRESUMO
Alzheimer's disease (AD) is the most common form of age-associated dementia. Several studies have predicted that AD is caused by the production and deposition of the ß-amyloid peptide (Aß) in the brain, which is one of pathologic hallmarks of AD. In particular, Aß oligomers are reportedly the most toxic and pathogenic of other peptide forms. We previously developed Multimer Detection System-Oligomeric Amyloid-ß (MDS-OAß), a technique for measuring Aß oligomerization in plasma to diagnose AD. Here, we clarified the molecular sizes of oligomers that can be detected by the MDS and investigated differences in plasma spiking with a synthetic Aß peptide in the plasma of AD patients and individuals with non-AD neurological conditions. To determine Aß oligomer sizes detectable by MDS, size exclusion chromatography (SEC) was first performed on incubated samples of synthetic Aß42 peptides. As a result, no MDS signals were observed for the Aß42 monomer fractions, but strong signals were found for oligomers of 7-35-mers long. Also, an amplified luminescent proximity homogeneous assay-linked immunoassay (AlphaLISA) was used to confirm that synthetic Aß peptides not only recruited endogenous Aß in plasma but also induced significantly stronger seeding in AD plasma than in healthy control plasma. In addition, the absence of the MDS signals in Aß-depleted plasma confirmed that the increased oligomerization tendency in AD plasma is dependent on the presence of endogenous Aß in plasma. Therefore, the MDS-OAß measurement of oligomerization differences in plasma after incubation with spiked synthetic Aß peptides has significant potential in AD diagnosis.
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Doença de Alzheimer/sangue , Peptídeos beta-Amiloides/sangue , Multimerização Proteica , Idoso , Peptídeos beta-Amiloides/química , Biomarcadores/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Quantum confinements, especially quantum in narrow wells, have been investigated because of their controllability over electrical parameters. For example, quantum dots can emit a variety of photon wavelengths even for the same material depending on their particle size. More recently, the research into two-dimensional (2D) materials has shown the availability of several quantum mechanical phenomenon confined within a sheet of materials. Starting with the gapless semimetal properties of graphene, current research has begun into the excitons and their properties within 2D materials. Even for simple 2D systems, experimental results often offer surprising results, unexpected from traditional studies. We investigated a coupled quantum well system using 2D hexagonal boron nitride (hBN) barrier as well as 2D tungsten disulfide (WS2) semiconductor arranged in stacked structures to study the various 2D to 2D interactions. We determined that for hexagonal boron nitride-tungsten disulfide (hBN/WS2) quantum well stacks, the interaction between successive wells resulted in decreasing bandgap, and the effect was pronounced even over a large distance of up to four stacks. Additionally, we observed that a single layer of isolating hBN barriers significantly reduces interlayer interaction between WS2 layers, while still preserving the interwell interactions in the alternative hBN/WS2 structure. The methods we used for the study of coupled quantum wells here show a method for determining the respective exciton energy levels and trion energy levels within 2D materials and 2D materials-based structures. Renormalization energy levels are the key in understanding conductive and photonic properties of stacked 2D materials.
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OBJECTIVES: Cardiovascular disease (CVD) continues to disproportionately affect disadvantaged populations, leading to calls to address social determinants of health (SDOH) as a preventive strategy. Our aim is to create a weighed SDOH score and to test the impact of each SDOH factor on the Framingham risk score (FRS) and on individual traditional CVD risk factors. STUDY DESIGN: We conducted a retrospective cohort study. METHODS: We included patients seen at a primary care clinic at UHealth/University of Miami Health System who answered a SDOH survey between September 16, 2016, and September 10, 2017. The survey included SDOH domains recommended by the American Heart Association position statement and by the National Academy of Medicine. We selected the FRS as well as all traditional CVD risk factors as our outcome metrics. RESULTS: We included 2876 patients. The mean (SD) age of our cohort was 53.8 (15.8) years, 61% were female, 9% were Black, 38% were Hispanic, and 87% reported speaking English. The statistically significant ß coefficients in the FRS model corresponded to being born outside of the United States, being a racial minority, living alone, having a high social isolation score, and having a low geocoded median household income (P < .01). Increasing quartile of SDOH score was significantly associated with higher systolic blood pressure, FRS, glycated hemoglobin, and smoking pack-years (P < .05). It was also associated with fewer minutes spent exercising weekly (P < .01). CONCLUSIONS: The addition of self-reported SDOH data has a dose effect on CVD risk factors. Future studies should address how to intervene to address social factors.
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Doenças Cardiovasculares , Determinantes Sociais da Saúde , Doenças Cardiovasculares/epidemiologia , Feminino , Fatores de Risco de Doenças Cardíacas , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Estados Unidos/epidemiologiaRESUMO
OBJECTIVE: We present a holistic perioperative optimization approach led by a CI team with the goal to optimize the workflow within our EHR, improve operative room metrics and user satisfaction. SUMMARY OF BACKGROUND DATA: The EHR has become integral to perioperative care. Many approaches are utilized to improve performance including systems-based approaches, process redesign, lean methodology, checklists, root cause analysis, and parallel processing. Although most reports describe strategies improving day or surgery productivity, few include perioperative interventions to improve efficiencies. METHODS: An interdisciplinary CI team consisting of clinicians, informatics specialists, and analysts spent 6 weeks assessing users and optimizing all perioperative areas (scheduling, day of surgery, postop discharge/admission). Elbow-to-elbow retraining and simultaneous content development was performed utilizing an Agile workflow process optimization with the Scrum framework. This iterative approach averaged 1 week from build to change implementation. Pre/post optimization surveys were sent. RESULTS: Two hundred forty-two perioperative enhancements were completed. While most impacted documentation, all areas were enhanced including billing, reporting, registration, device integration, scheduling, central supply, and so on. FCOTS improved from <70% to >85% and total delay was halved. These parameters were consistently sustained for over 1 year after the 6-week optimization. While only 5% of pre-optimization users agreed to proficiency in the EHR system, this improved to 70% post-optimization. Furthermore, EHR confidence and acceptance improved from 40% to 90%. CONCLUSIONS: To improve workflow efficiency, all who contribute to the perioperative process must be assessed. This IT driven initiative resulted in improved FCOTS, perioperative workflows, and user satisfaction.
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Registros Eletrônicos de Saúde , Informática Médica , Equipe de Assistência ao Paciente , Assistência Perioperatória/métodos , Assistência Perioperatória/normas , Melhoria de Qualidade , HumanosRESUMO
The increasing prevalence of Alzheimer's disease (AD) has become a global phenomenon presenting serious social and health challenges. For detecting early molecular changes in the disease, several techniques to measure varied species of amyloid beta in the peripheral blood have been recently developed, but the efforts to associate them with cognitive assessments have yet to produce sufficient data. We prospectively collected participants from the consecutive population who visited our center for brain health screening. In total, 97 participants (F:M = 58:39) aged 69.4 ± 7.52 were assessed. Participants performed the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K), the clinical dementia rating (CDR), plasma oligomeric amyloid-ß (OAß) level tests, routine blood tests, ApoE genotype, and brain MRI. Among total population, 55.7% had a CDR of 0, and 40.2% had a CDR of 0.5. The results showed that word memory and word recall, and the total scores of the CERAD-K were negatively correlated with the plasma OAß level. With a cut-off value of 0.78 ng/mL for the OAß level and a -1.5 standard deviation of age/sex/education adjusted norms for the CERAD-K; naming, word memory, word recall, word recognition, and total score were significantly correlated with the OAß level. No correlation between the OAß level and mini-mental status examination was found. Our results demonstrate that the level of plasma OAß was well correlated with the measure of cognitive function through the CERAD-K in the field data collected from consecutive populations. Studies on longitudinal comparisons with large cohorts will further validate the diagnostic value of plasma OAß as a useful biomarker for screening AD and predicting progression.
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Previous studies have looked at differences in predisposing factors, symptomology, treatment options, and outcomes in patients with SSCD experiencing audiologic and vestibular symptoms, however this study utilizes data from the largest series of SSCD patients by a single pair of neurosurgeon and head and neck surgeon to date. The objective was to determine what pre-operative factors, if any, contribute to post-operative outcomes in SSCD patients. A retrospective chart review collected patient demographics, preoperative symptoms, and postoperative symptoms. Nonparametric tests were run using IBM® SPSS® Statistics. Fisher's Exact Tests, Spearman's rho, and McNemar's test for paired comparison of binary measures were performed, with a significance level of Pâ¯<â¯0.05. A total of 156 SSCD surgeries were performed within a cohort of 119 patients. The majority of patients were female (nâ¯=â¯75, 63.0%). The median age was 55â¯years (±12.7â¯years) and median follow-up length was 0.46â¯months (range: 0.03-59.5â¯months). Increased postoperative dizziness and hearing loss was significantly correlated with females (Pâ¯=â¯.048, Pâ¯=â¯.041). Additionally, males reported significantly improved postoperative hearing (Pâ¯=â¯.044) with confirmatory audiometry. Serum ionized calcium levels inversely correlated with age using spearman's coefficient (rsâ¯=â¯-.260 Pâ¯=â¯.037). Postsurgical autophony was significantly associated with bilateral SSCD (Pâ¯=â¯.01). In conclusion, differences in outcomes between patients may have to do with bilateralism of SSCD or gender effects. Proposed theories concerning a "two hit" hypothesis and about calcium feedback regulation in SSCD may play a role in these findings. Understanding differences between symptomology will help facilitate discussions with future patients.
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Doenças do Labirinto/patologia , Doenças do Labirinto/cirurgia , Procedimentos Cirúrgicos Otorrinolaringológicos/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Adulto , Idoso , Cálcio/sangue , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Recém-Nascido , Doenças do Labirinto/sangue , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/sangue , Estudos Retrospectivos , Fatores de Risco , Canais Semicirculares/patologia , Canais Semicirculares/cirurgia , Fatores SexuaisRESUMO
OBJECTIVE: The authors compared postoperative symptoms between patients with sealed and those with plugged semicircular canal dehiscence repairs. METHODS: In total, 136 ears from 118 patients who underwent surgical repair for semicircular canal dehiscence were identified via chart review. Data from postoperative MRI scans showing preservation or loss of semicircular canal fluid signal and postoperative reports of autophony, amplification, aural fullness, tinnitus, hyperacusis, hearing loss, vertigo, dizziness, disequilibrium, oscillopsia, and headache were amalgamated and analyzed. RESULTS: Patients with preservation of fluid signal were far less likely to have dizziness postoperatively (p = 0.007, OR 0.158, 95% CI 0.041-0.611). In addition, these patients were more likely to have tinnitus postoperatively (p = 0.028, OR 3.515, 95% CI 1.145-10.787). CONCLUSIONS: The authors found that superior semicircular canal dehiscence patients who undergo sealing without plugging have improved balance outcomes but show more tinnitus postoperatively than patients who undergo plugging.
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Transition metal oxide-based memristors have widely been proposed for applications toward artificial synapses. In general, memristors have two or more electrically switchable stable resistance states that device researchers see as an analogue to the ion channels found in biological synapses. The mechanism behind resistive switching in metal oxides has been divided into electrochemical metallization models and valence change models. The stability of the resistance states in the memristor vary widely depending on: oxide material, electrode material, deposition conditions, film thickness, and programming conditions. So far, it has been extremely challenging to obtain reliable memristors with more than two stable multivalued states along with endurances greater than â¼1000 cycles for each of those states. Using an oxygen plasma-assisted sputter deposition method of noble metal electrodes, we found that the metal-oxide interface could be deposited with substantially lower interface roughness observable at the nanometer scale. This markedly improved device reliability and function, allowing for a demonstration of memristors with four completely distinct levels from â¼6 × 10-6 to â¼4 × 10-8 S that were tested up to 104 cycles per level. Furthermore through a unique in situ transmission electron microscopy study, we were able to verify a redox reaction-type model to be dominant in our samples, leading to the higher degree of electrical state controllability. For solid-state synapse applications, the improvements to electrical properties will lead to simple device structures, with an overall power and area reduction of at least 1000 times when compared to SRAM.
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Social determinants of health (SDH) impact health outcomes. Medical centers have begun to collect SDH data, urged by government and scientific entities. Provider perspectives on collecting SDH are unknown. The aim is to understand differences in views and preferences according to provider characteristics. A cross-sectional survey of University of Miami clinical faculty was conducted in late 2016. The survey contained 11 questions: 8 demographic and departmental responsibilities questions and 3 Likert scale questions to capture collection and use of SDH perspectives. The main outcome was whether providers thought the benefit of collecting SDH outweighs the burden and risks. In all, 240 faculty members were included. The majority were men (64%), with a mean age of 51 years. Among participants, 53.5% were non-Hispanic white, 32% were Hispanic, 5% were Black/African American, and 5% were Asian. The majority agreed that SDH are important predictors of health outcomes and quality of care (83%). When comparing minority to nonminority faculty, 25% believed that SDH should only be available to PCPs, compared to 8% of nonminorities (P < 0.01). In a multivariate model, belonging to a racial ethnic minority was the only characteristic associated with believing that benefits of collecting SDH outweigh the risks (odds ratio 1.87, 95% confidence interval 1.02- 3.5) after adjusting for age, sex, minority status, health care provider type, type of responsibilities, and department. This study reveals that although most providers of a health system believe social risks impact health outcomes and quality metrics, the buy-in to collect SDH varies according to the racial/ethnic composition of the faculty.
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Atitude do Pessoal de Saúde , Coleta de Dados , Médicos/estatística & dados numéricos , Determinantes Sociais da Saúde , Estudos Transversais , Registros Eletrônicos de Saúde , Feminino , Humanos , Masculino , Inquéritos e Questionários , Resultado do TratamentoRESUMO
BACKGROUND: Coronary collateral circulation protects cardiac tissues from myocardial infarction damage and decreases sudden cardiac death. So far, it is unclear how coronary collateralization varies by race-ethnicity groups and by sex. METHODS: We assessed 868 patients with obstructive CAD. Patients were assessed for collateral grades based on Rentrop grading system, as well as other covariates. DNA samples were genotyped using the Affymetrix 6.0 genotyping array. To evaluate genetic contributions to collaterals, we performed admixture mapping using logistic regression with estimated local and global ancestry. RESULTS: Overall, 53% of participants had collaterals. We found difference between sex and racial-ethnic groups. Men had higher rates of collaterals than women (P-value = 0.000175). White Hispanics/Latinos showed overall higher rates of collaterals than African Americans and non-Hispanic Whites (59%, 50% and 48%, respectively, P-value = 0.017), and especially higher rates in grade 1 and grade 3 collateralization than the other two populations (P-value = 0.0257). Admixture mapping showed Native American ancestry was associated with the presence of collaterals at a region on chromosome 17 (chr17:35,243,142-41,251,931, ß = 0.55, P-value = 0.000127). African ancestry also showed association with collaterals at a different region on chromosome 17 (chr17: 32,266,966-34,463,323, ß = 0.38, P-value = 0.00072). CONCLUSIONS: In our study, collateralization showed sex and racial-ethnic differences in obstructive CAD patients. We identified two regions on chromosome 17 that were likely to harbor genetic variations that influenced collateralization.
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Aterosclerose/genética , Circulação Colateral/genética , Circulação Coronária/genética , Infarto do Miocárdio/genética , Adulto , Negro ou Afro-Americano/genética , Idoso , Artérias/fisiopatologia , Aterosclerose/epidemiologia , Aterosclerose/fisiopatologia , Circulação Coronária/fisiologia , Etnicidade , Feminino , Genótipo , Hispânico ou Latino/genética , Humanos , Indígenas Norte-Americanos/genética , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/epidemiologia , Infarto do Miocárdio/fisiopatologia , Fatores de Risco , Caracteres Sexuais , População Branca/genéticaRESUMO
BACKGROUND: Teratomas of the cranial vault are divided into histopathological subtypes and grouped by prognoses: mature (good prognosis), mixed/malignant and immature teratomas (intermediate prognosis). This schema also includes non-teratomatous tumors. The authors of this study sought to elucidate histologically dependent predictors of survival and further clarify the classification system of intracranial teratomas. METHODS: We performed a systematic analysis of the published literature to identify studies describing patients with intracranial teratomas diagnosed with magnetic resonance imaging (MRI) and presenting definite information on histologies, therapies, and outcomes at a minimum follow-up of 2 years. Disease-free (DFS) and overall survival (OS) were evaluated. RESULTS: A total of 18 articles comprised of 134 patients were included. On univariate analysis, male sex and gross-total resection (GTR) were associated with high mean DFS (p = 0.0362 and p < 0.0001, respectively). On multivariate analysis, mature teratomas located in the pineal, and those having undergone subtotal resection (STR) demonstrated high mean OS (p = 0.0023 and p = 0.0044, respectively). Mature and mixed/malignant suprasellar teratomas had equally higher mean OS versus immature suprasellar teratomas (p < 0.0001). Mature and immature teratomas treated with adjuvant therapy had significantly higher mean OS compared to those managed with surgery alone (p = 0.0421 and p = 0.0423, respectively). Males with immature teratomas had the highest mean OS (p < 0.0001). Immature teratomas managed with surgery alone had higher mean DFS, but lower mean OS, compared to those treated with adjuvant therapy (p = 0.0176 and p = 0.0423, respectively). CONCLUSIONS: Our data highlight the divergent nature of the different histopathological subtypes of teratomas, and suggest that survival outcomes are multifactorial. Specifically, male sex, pineal, suprasellar, GTR, and STR were dependent predictors of OS, while histopathology was an independent predictor of OS.
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Neoplasias Encefálicas , Teratoma , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Feminino , Humanos , Masculino , Teratoma/mortalidade , Teratoma/patologia , Teratoma/terapiaRESUMO
Central neurocytoma (CN) is a rare, benign brain tumor often located in the lateral ventricles. CN may cause obstructive hydrocephalus and manifest as signs of increased intracranial pressure. The goal of treatment for CN is a gross total resection (GTR), which often yields excellent prognosis with a very high rate of tumor control and survival. Adjuvant radiosurgery and radiotherapy may be considered to improve tumor control when GTR cannot be achieved. Chemotherapy is also not considered a primary treatment, but has been used as a salvage therapy. The radiological features of CN are indistinguishable from those of other brain tumors; therefore, many histological markers, such as synaptophysin, can be very useful for diagnosing CNs. Furthermore, the MIB-1 Labeling Index seems to be correlated with the prognosis of CN. We also discuss oncogenes associated with these elusive tumors. Further studies may improve our ability to accurately diagnose CNs and to design the optimal treatment regimens for patients with CNs.
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Resistive random access memory (ReRAM) devices have been extensively investigated resulting in significant enhancement of switching properties. However fluctuations in switching parameters are still critical weak points which cause serious failures during 'reading' and 'writing' operations of ReRAM devices. It is believed that such fluctuations may be originated by random creation and rupture of conducting filaments inside ReRAM oxides. Here, we introduce defective monolayer graphene between an oxide film and an electrode to induce confined current path distribution inside the oxide film, and thus control the creation and rupture of conducting filaments. The ReRAM device with an atomically thin interlayer of defective monolayer graphene reveals much reduced fluctuations in switching parameters compared to a conventional one. Our results demonstrate that defective monolayer graphene paves the way to reliable ReRAM devices operating under confined current path distribution.
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BACKGROUND: The mechanisms through which exercise reduces cardiovascular disease are not fully understood. We used echocardiograms, cardiac biomarkers and gene expression to investigate cardiovascular effects associated with exercise training. METHODS: Nineteen sedentary men (22-37 years) completed a 17-week half-marathon training program. Serial measurements of resting heart rate, blood pressure, maximum oxygen consumption, lipids, C-reactive protein, cardiac troponin T, echocardiograms and blood for gene expression were obtained from baseline to peak training. Controls included 22 sedentary men who did not exercise. RESULTS: Among the training group, VO2 max increased from 37.1 to 42.0 ml/kg/min (p < 0.001). Significant changes were seen in left ventricular wall thickness and mass, stroke volume, resting heart rate and blood pressure (p < 0.001). The control group demonstrated no significant changes. Expression profiling in the training group identified 10 significantly over-expressed and 53 significantly under-expressed loci involved in inflammatory pathways. Dividing the training group into high and low responders based on percent change in VO2 max identified loci that differentiated these two groups at baseline and after training. CONCLUSION: Intensive exercise training leads to significant increase in cardiac and hemodynamic performance, and significant changes in expression of genes involved in immune and inflammatory response.
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OBJECTIVES: To assess the impact of the Centers for Medicare and Medicaid Services (CMS) national coverage determination (NCD) on access for patients with aortic stenosis (AS) with transcatheter aortic valve replacement (TAVR) in a tertiary care center. BACKGROUND: TAVR has given hope to patients with AS who are deemed inoperable. The effects of the NCD on access to patients with AS has not been evaluated. MATERIALS AND METHODS: A total of 94 inoperable AS patients were evaluated and treated from December 2011 through June of 2012 with TAVR. Patients who underwent transfemoral (TF) vs. non-TF access were compared. The CMS NCD was released on May 1, 2012 and on July 1, 2012, the nontransfemoral access program was put on hold due to lack of reimbursement. RESULTS: Patients in the TF (n = 33) and non-TF access (n = 61) groups were similar in age (85.2 ± 6.3 vs. 84.8 ± 6.6 P = 0.74) and STS mortality (9.38 ± 5.33 vs. 7.91 ± 3.69, P = 0.074). The iliofemoral arteries were larger diameter in the TF group (7.72 ± 1.49 vs. 6.21 ± 1.78, P < 0.001) and males (7.39 ± 1.81 vs. 6.1 ± 1.61 P < 0.001). More women underwent valve implantation via non-TF access (73 vs. 23%, P = 0.03). After the NCD, 21 patients who previously qualified for non-TF TAVR would not be reimbursed by CMS. Four died soon after. CONCLUSIONS: After the NCD, the proportion of inoperable patients with severe AS that can be treated with TAVR was greatly reduced due the lack of reimbursement for TAVR via non-TF access. This effect is particularly pronounced in women. © 2014 Wiley Periodicals, Inc.
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Estenose da Valva Aórtica/cirurgia , Centers for Medicare and Medicaid Services, U.S./estatística & dados numéricos , Substituição da Valva Aórtica Transcateter/métodos , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/diagnóstico , Estenose da Valva Aórtica/mortalidade , Cateterismo Cardíaco , Feminino , Seguimentos , Humanos , Masculino , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida/tendências , Substituição da Valva Aórtica Transcateter/economia , Resultado do Tratamento , Estados Unidos/epidemiologiaRESUMO
Stackable select devices such as the oxide p-n junction diode and the Schottky diode (one-way switch) have been proposed for non-volatile unipolar resistive switching devices; however, bidirectional select devices (or two-way switch) need to be developed for bipolar resistive switching devices. Here we report on a fully stackable switching device that solves several problems including current density, temperature stability, cycling endurance and cycle distribution. We demonstrate that the threshold switching device based on As-Ge-Te-Si material significantly improves cycling endurance performance by reactive nitrogen deposition and nitrogen plasma hardening. Formation of the thin Si3N4 glass layer by the plasma treatment retards tellurium diffusion during cycling. Scalability of threshold switching devices is measured down to 30 nm scale with extremely fast switching speed of ~2 ns.
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The rectifying Schottky characteristics of the metal-semiconductor junction with high contact resistance have been a serious issue in modern electronic devices. Herein, we demonstrated the conversion of the Schottky nature of the Ni-Si junction, one of the most commonly used metal-semiconductor junctions, into an Ohmic contact with low contact resistance by inserting a single layer of graphene. The contact resistance achieved from the junction incorporating graphene was about 10(-8) ~ 10(-9) Ω cm(2) at a Si doping concentration of 10(17) cm(-3).