Topological Flat Bands in Graphene Super-Moiré Lattices.

Moiré-pattern-based potential engineering has become an important way to explore exotic physics in a variety of two-dimensional condensed matter systems. While these potentials have induced correlated phenomena in almost all commonly studied 2D materials, monolayer graphene has remained an exception. We demonstrate theoretically that a single layer of graphene, when placed between two bulk boron nitride crystal substrates with the appropriate twist angles, can support a robust topological ultraflat band emerging as the second hole band. This is one of the simplest platforms to design and exploit topological flat bands.

Updates in the management of atrial fibrillation: Emerging therapies and treatment.

OBJECTIVE: The most common and clinically important cardiac arrhythmia is atrial fibrillation (AF), which has a large negative impact on public health due to higher fatalities, morbidity, and healthcare expenditure rates. This study aims to provide valuable insights into the effectiveness and outcomes of various treatment approaches and interventions for AF. STUDY DESIGN: Systematic review. METHOD: The most pertinent published research (original papers and reviews) in the scientific literature were searched for and critically assessed using the online, internationally indexed databases PubMed, Medline, and Cochrane Reviews. These studies are summarised in this review. Keywords like "Atrial Fibrillation", "emerging therapies", "treatment", "catheter ablation", and "atrial appendage" were used to search the papers. The papers were researched and examined to be relevant to the topic. CONCLUSION: A lot of work has gone into enhancing AF management to deal with this expanding public health concern. Significant developments and advances in the treatment of AF during the past few years have aided clinicians in giving AF patients better care. The most recent treatments for AF include medication, catheter ablation, cryo-balloon ablation, and left atrial appendage closure.

Tunable Spin-Polarized States in Graphene on a Ferrimagnetic Oxide Insulator.

Spin-polarized two-dimensional (2D) materials with large and tunable spin-splitting energy promise the field of 2D spintronics. While graphene has been a canonical 2D material, its spin properties and tunability are limited. Here, this work demonstrates the emergence of robust spin-polarization in graphene with large and tunable spin-splitting energy of up to 132 meV at zero applied magnetic fields. The spin polarization is induced through a magnetic exchange interaction between graphene and the underlying ferrimagnetic oxide insulating layer, Tm3 Fe5 O12 , as confirmed by its X-ray magnetic circular dichroism (XMCD). The spin-splitting energies are directly measured and visualized by the shift in their Landau-fan diagram mapped by analyzing the measured Shubnikov-de-Haas (SdH) oscillations as a function of applied electric fields, showing consistent fit with the first-principles and machine learning calculations. Further, the observed spin-splitting energies can be tuned over a broad range between 98 and 166 meV by field cooling. The methods and results are applicable to other 2D (magnetic) materials and heterostructures, and offer great potential for developing next-generation spin logic and memory devices.

Controlled alignment of supermoiré lattice in double-aligned graphene heterostructures.

The supermoiré lattice, built by stacking two moiré patterns, provides a platform for creating flat mini-bands and studying electron correlations. An ultimate challenge in assembling a graphene supermoiré lattice is in the deterministic control of its rotational alignment, which is made highly aleatory due to the random nature of the edge chirality and crystal symmetry. Employing the so-called "golden rule of three", here we present an experimental strategy to overcome this challenge and realize the controlled alignment of double-aligned hBN/graphene/hBN supermoiré lattice, where the twist angles between graphene and top/bottom hBN are both close to zero. Remarkably, we find that the crystallographic edge of neighboring graphite can be used to better guide the stacking alignment, as demonstrated by the controlled production of 20 moiré samples with an accuracy better than ~ 0.2°. Finally, we extend our technique to low-angle twisted bilayer graphene and ABC-stacked trilayer graphene, providing a strategy for flat-band engineering in these moiré materials.

Baseline blood count levels increase odds of cytopenia among CML patients in Kenya: a case control study.

BACKGROUND: Imatinib is the gold standard for the treatment of all phases of Philadelphia positive Chronic Myeloid Leukemia (CML). During treatment, patients may develop cytopenia. We aimed to study the baseline characteristics and factors associated with cytopenia at a Nairobi Hospital. METHODS: This was a retrospective case-control study of patients aged ≥18 years on follow-up at the Glivec International Patient Access Program (GIPAP) clinic from 2007 to 2015. The cases consisted of CML patients on imatinib who developed cytopenia. The controls were CML patients on imatinib who did not develop cytopenia. Baseline socio - demographic, clinical, hematologic, and molecular data were retrieved from patients' files. Chi square or fishers' exact tests were used to analyze for differences between cytopenia and no cytopenia. Binary logistic regressions were employed to identify relationships. Univariate and multivariate analyses were done to identify independent predictors of cytopenia. Odds ratios (OR) were presented including the 95% confidence intervals and respective p values. RESULTS: A total of 201 patients were studied consisting of ninety-four (94) patients with cytopenia and 107 with no cytopenia. Among the entire population, males were 52, and 42% were aged 36-50 years. Sex, age, marital status, occupation and education level were similar between the cytopenia and no cytopenia groups. Among the 201 patients, 70% had symptoms for > 12 months before diagnosis, 78.6% had B symptoms at baseline, 80% had a moderate splenomegaly at baseline. Among patients with cytopenia, 40 and 37.4% developed cytopenia within 3 months and 3-6 months respectively after imatinib initiation. Baseline neutrophilia, neutropenia, anaemia, thrombocytosis, thrombocytopenia was found in 68, 11, 11, 23.5 and 11% respectively. Baseline hemoglobin, neutrophil and platelet level were significantly different between the cytopenia and the no cytopenia group. On univariable analysis, baseline anemia with hb < 7.9 g/dL (p = 0.002), neutropenia (p = 0.001), neutrophilia > 100,000/mm3 (p = 0.002) and thrombocytopenia (p = 0.001) increased the odds of developing cytopenia. On multivariable analysis, baseline anaemia (p value < 0.002), neutropenia (p value < 0.001), thrombocytopenia (p value, < 0.001) and thrombocytosis (p value, 0.033) increased the odds of developing cytopenia. CONCLUSION: Odds of cytopenia were higher in presence of baseline cytopenia and thrombocytosis. Clinicians should have a high index of suspicion for these patients.

Impact of COVID-19 on Cancer Care Delivery in Africa: A Cross-Sectional Survey of Oncology Providers in Africa.

PURPOSE: The COVID-19 pandemic has disrupted cancer care globally. There are limited data of its impact in Africa. This study aims to characterize COVID-19 response strategies and impact of COVID-19 on cancer care and explore misconceptions in Africa. METHODS: We conducted a web-based cross-sectional survey of oncology providers in Africa between June and August 2020. Descriptive statistics and comparative analysis by income groups were performed. RESULTS: One hundred twenty-two participants initiated the survey, of which 79 respondents from 18 African countries contributed data. Ninety-four percent (66 of 70) reported country mitigation and suppression strategies, similar across income groups. Unique strategies included courier service and drones for delivery of cancer medications (9 of 70 and 6 of 70, respectively). Most cancer centers remained open, but > 75% providers reported a decrease in patient volume. Not previously reported is the fear of infectivity leading to staff shortages and decrease in patient volumes. Approximately one third reported modifications of all cancer treatment modalities, resulting in treatment delays. A majority of participants reported ≤ 25 confirmed cases (44 of 68, 64%) and ≤ 5 deaths because of COVID-19 (26 of 45, 58%) among patients with cancer. Common misconceptions were that Africans were less susceptible to the virus (53 of 70, 75.7%) and decreased transmission of the virus in the African heat (44 of 70, 62.9%). CONCLUSION: Few COVID-19 cases and deaths were reported among patients with cancer. However, disruptions and delays in cancer care because of the pandemic were noted. The pandemic has inspired tailored innovative solutions in clinical care delivery for patients with cancer, which may serve as a blueprint for expanding care and preparing for future pandemics. Ongoing public education should address COVID-19 misconceptions. The results may not be generalizable to the entire African continent because of the small sample size.

Tunable Optical Properties of Thin Films Controlled by the Interface Twist Angle.

Control of materials properties has been the driving force of modern technologies. So far, materials properties have been modulated by their composition, structure, and size. Here, by using cathodoluminescence in a scanning transmission electron microscope, we show that the optical properties of stacked, >100 nm thick hexagonal boron nitride (hBN) films can be continuously tuned by their relative twist angles. Due to the formation of a moiré superlattice between the two interface layers of the twisted films, a new moiré sub-band gap is formed with continuously decreasing magnitude as a function of the twist angle, resulting in tunable luminescence wavelength and intensity increase of >40×. Our results demonstrate that moiré phenomena extend beyond monolayer-based systems and can be preserved in a technologically relevant, bulklike material at room temperature, dominating optical properties of hBN films for applications in medicine, environmental, or information technologies.

Cytopenia among CML Patients on Imatinib in Kenya: Types, Grades, and Time Course.

BACKGROUND: Imatinib mesylate is the gold standard for the treatment of all phases of Philadelphia-positive chronic myeloid leukemia. Patients on imatinib treatment may develop cytopenia due to drug toxicity. This study aimed to determine the types, grades, and time course of cytopenia in CML patients on imatinib at a Nairobi hospital. METHODS: This was a cross-sectional descriptive study of adult patients aged ≥18 years followed up at the Glivec International Patient Access Program (GIPAP) clinic from 2007 to 2015. Patients who developed cytopenia within 12 months of initiating imatinib were eligible. Clinical and hematologic data were retrieved from the patients' charts and entered into a study proforma. Measures of central tendency such as mean, median, mode, standard deviation, and variance were used for analysis. RESULTS: Sixty three percent (63.6%) of the 94 patients developed a monocytopenia, with anemia seen in 34%, neutropenia in 27.6%, and thrombocytopenia in 8% of the 94 patients. Anemia plus neutropenia was the most common bicytopenia at 12.7%. Pancytopenia was seen in only 5 of the 94 patients. Most of the cytopenia was grades 2 and 3. Anemia was present at baseline while neutropenia and thrombocytopenia developed within 12 months of imatinib initiation. Anemia resolved during the first 12 months of therapy while neutropenia and thrombocytopenia resolved within 24-36 months of treatment. CONCLUSION: Monocytopenia, especially anemia, was the most common type of cytopenia. The cytopenia was predominantly grade 2, developed in majority of the patients within 6 months after imatinib initiation, and had resolved by 24-36 months after imatinib initiation.

Prevalence and Predictors of Cisplatin-Induced Peripheral Neuropathy at the Kenyatta National Hospital.

PURPOSE: To determine the prevalence, predictors, and/or risk factors of chemotherapy-induced peripheral neuropathy in patients undergoing chemotherapy with cisplatin at Kenyatta National Hospital, Nairobi, Kenya. METHODS: This was a cross-sectional analysis of patients who underwent chemotherapy with cisplatin for at least 2 months at Kenyatta National Hospital oncology units. Peripheral neuropathy was determined by history and physical examination per the protocol. Data are presented in tables. Descriptive inferential statistics such as means, medians, and proportions were determined where applicable. RESULTS: We recruited 67 patients who were undergoing chemotherapy with cisplatin. Fifty-six patients (83.6%) had peripheral neuropathy. Forty-five patients (81%) had mild-grade (grades 1 and 2) peripheral neuropathy. Only two patients (3.1%) had grade 4 neuropathy. Almost all patients who were overweight or obese developed peripheral neuropathy. CONCLUSION: Peripheral neuropathy among patients receiving cisplatin is quite prevalent at Kenyatta National Hospital (83.6% prevalence rate). However, most of the patients had a mild grade of neuropathy, which is largely consistent with literature elsewhere.

Changes in Blood Pressure Levels and Antihypertensive Medication Use before and after Renal Transplantation among Patients in Nairobi, Kenya: A Comparative Cross-Sectional Study.

Objectives. To determine the changes in blood pressure levels and antihypertensive medication use in the postrenal transplantation period compared to pretransplantation one. Methods. A comparative cross-sectional study was carried out on renal transplant recipients at the Kenyatta National Hospital, a national referral hospital in Kenya. Sociodemographic details, blood pressure levels, and antihypertensive medication use before and after renal transplantation were noted. Changes in mean blood pressure levels and mean number of antihypertensive medications after renal transplantation were determined using paired t-test. Results. 85 subjects were evaluated. Mean age was 42.4 (SD ± 12.2) years, with a male : female ratio of 1.9 : 1. Compared to the pretransplant period, significantly lower mean systolic and diastolic blood pressure levels after transplantation were noted (mean SBP 144.5 mmHg versus 131.8 mmHg; mean DBP 103.6 mmHg versus 83.5 mmHg in the pre- and posttransplant periods, respectively, p < 0.001). Mean number of antihypertensive medications also reduced significantly after transplantation, with an average of 3.3 (±1.6) versus 2.1 (±0.9) in the pre- and posttransplant periods, respectively (p < 0.001). Conclusion. There is a significant reduction in blood pressure levels and number of antihypertensive medications used after renal transplantation. The positive impact of renal transplantation on blood pressure control should be confirmed using prospective cohort studies of patients with end stage renal disease who then undergo renal transplantation.