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Fetal long-QT syndrome (LQTS) may present with sinus bradycardia, functional 2:1 atrioventricular block (2:1AVB), and ventricular arrhythmias (VT/TdP) and lead to fetal or postnatal death. We performed a systematic review and individual participant data meta-analysis of 83 studies reporting outcomes of 265 fetuses where suspected LQTS was confirmed postnatally and determined risk of adverse peri/postnatal outcomes using logistic, and stepwise logistic regression. A longer fetal QTc was more predictive of death than any other antenatal factor (ROC area under curve (AUC), 0·85 (95% confidence interval (CI) 0·66-1·00)); risk of death was significantly increased with fetal QTc greater than 600ms. Neither fetal heart rate nor heart rate z-score predicted death (ROC AUC 0·51 (95%CI 0·31-0·71) and 0·59 (95%CI 0·37-0·80), respectively). The combination of antenatal VT/TdP or functional 2:1AVB and a lack of family history of LQTS was also highly predictive of death (ROC AUC 0·82(95%CI 0·76 to 0·88). Our data provide clinical screening tools to enable prediction and intervention for fetuses with LQTS at risk of death.

Aims We aim to determine any additional benefit of virtual reality (VR) experience if compared to conventional cross-sectional imaging and standard three-dimensional (3D) modelling when deciding on surgical strategy in patients with complex double outlet right ventricle (DORV). Methods and results We retrospectively selected 10 consecutive patients with DORV and complex interventricular communications, who underwent biventricular repair. An arterial switch operation (ASO) was part of the repair in three of those. Computed tomography (CT) or cardiac magnetic resonance imaging images were used to reconstruct patient-specific 3D anatomies, which were then presented using different visualization modalities: 3D pdf, 3D printed models, and VR models. Two experienced paediatric cardiac surgeons, blinded to repair performed, reviewed each case evaluating the suitability of repair following assessment of each visualization modalities. In addition, they had to identify those who had ASO as part of the procedure. Answers of the two surgeons were compared to the actual operations performed. There was no mortality during the follow-up (mean = 2.5 years). Two patients required reoperations. After review of CT/cardiac magnetic resonance images, the evaluators identified the surgical strategy in accordance with the actual surgical plan in 75% of the cases. When using 3D pdf this reached only 70%. Accordance improved to 85% after revision of 3D printed models and to 95% after VR. Use of 3D printed models and VR facilitated the identification of patients who required ASO. Conclusion Virtual reality can enhance understanding of suitability for biventricular repair in patients with complex DORV if compared to cross-sectional images and other 3D modelling techniques.

Congenital complete heart block (CCHB) is a very rare condition, with high risk of mortality. Prematurity is associated with immaturity of the cardiovascular system. Morbidity related to CCHB and prematurity has never been described. We describe a tertiary perinatal center experience over a 15-year period on CCHB management and complications in preterm infants. This is a single-center observational cohort study. All neonates admitted to neonatal intensive care unit with a diagnosis of isolated CCHB between January 2006 and January 2021 were identified. All preterm neonates (

The use of Melody valves in the mitral position has been introduced in clinical practice. Stent fracture is a recognized complication of Melody valve implantation in the pulmonary position; however, reports in the mitral position are rare. We present the case of an 8-year-old boy in whom complete fracture of the proximal stent struts occurred, causing acute severe mitral stenosis, and in whom urgent hybrid transapical Melody valve implantation in the fractured Melody valve was performed successfully using a novel modified technique. This modification simplified the implantation, led to reduced time of the procedure, and minimized hemodynamic instability.

Purpose Donation after circulatory death (DCD) offers an additional source of cardiac allografts, potentially allowing expansion of the donor pool. In this study, we investigated the efficacy of mitochondrial transplantation to improve myocardial function in DCD hearts. Methods Cardiocirculatory death was induced in Yorkshire pigs (40-50 kg, n=22) by cessation of mechanical ventilation. After 20 minutes of warm ischemia, cardioplegia was administered. The hearts were then reperfused on an ex-situ blood perfusion system for 240 minutes. Following 15 minutes of ex-situ perfusion, mitochondria (5 × 109 in respiration buffer, Mitochondria, n=8) or respiration buffer alone (Vehicle, n=8) were delivered as a single bolus to the coronary arteries. A control group (Sham, n=6) was not subjected to warm ischemia. Hearts were perfused in a resting mode for 120 minutes before converting the system to a continuous isovolumic loading mode. Left ventricular (LV) global function, myocardial oxygen consumption, and arterial lactates were compared by two-way repeated-measures analysis of variance (ANOVA) with Bonferroni adjustment. Results At the end of 240 minutes of reperfusion, LV peak developed pressure (LVdevP) and dP/dt max were significantly higher in the Sham group than in Vehicle (p 0.05), which was significantly lower in Vehicle (p=0.004). No differences were found in arterial lactate levels (Figure D) (p> 0.05). Conclusion Mitochondrial transplantation significantly preserves myocardial function and oxygen consumption in DCD hearts, thus providing an additional possible benefit for expanding heart donor pool.

Multi-system inflammatory syndrome in children (MIS-C) causes widespread inflammation including a pancarditis in the weeks following a COVID infection. As we prepare for further coronavirus surges, understanding the medium-term cardiac impacts of this condition is important for allocating healthcare resources. A retrospective single-center study of 67 consecutive patients with MIS-C was performed evaluating echocardiographic and electrocardiographic (ECG) findings to determine the point of worst cardiac dysfunction during the admission, then at intervals of 6-8 weeks and 6-8 months. Worst cardiac function occurred 6.8 ± 2.4 days after the onset of fever with mean 3D left ventricle (LV) ejection fraction (EF) 50.5 ± 9.8%. A pancarditis was typically present: 46.3% had cardiac impairment; 31.3% had pericardial effusion; 26.8% demonstrated moderate (or worse) valvar regurgitation; and 26.8% had coronary dilatation. Cardiac function normalized in all patients by 6-8 weeks (mean 3D LV EF 61.3 ± 4.4%, p 0.001 compared to presentation). Coronary dilatation resolved in all but one patient who initially developed large aneurysms at presentation, which persisted 6 months later. ECG changes predominantly featured T-wave changes resolving at follow-up. Adverse events included need for ECMO (n = 2), death as an ECMO-related complication (n = 1), LV thrombus formation (n = 1), and subendocardial infarction (n = 1). MIS-C causes a pancarditis. In the majority, discharge from long-term follow-up can be considered as full cardiac recovery is expected by 8 weeks. The exception includes patients with medium sized aneurysms or greater as these may persist and require on-going surveillance.

Surgical navigation systems have demonstrated improvements in alignment accuracy in a number of arthroplasty procedures, but they have not yet been widely adopted for use in total shoulder arthroplasty (TSA). We believe this is due in part to the obtrusiveness of conventional optical tracking systems, as well as the need for additional intraoperative steps such as calibration and registration. The purpose of this study is to evaluate the feasibility of adapting a less-intrusive dental navigation system for use in TSA.We developed a proof-of-concept system based on validated laser-engraved surgical tools recently introduced for use in dental surgery that are calibrated once when manufactured and not recalibrated at time of use. The design also features a notably smaller bone-mounted tracker that can be tracked from a wide range of viewing angles. To assess our system's performance, we modified the dental surgical software to support guidance of a TSA procedure. We then conducted a user study in which three participants with varying surgical experience used the system to drill 30 holes in a glenoid model. Using a coordinate measuring machine, we determined the resulting drilled trajectory and compared this to the pre-planned trajectory. Since we used a model glenoid rather than anatomical specimens, we report on targeting precision rather than overall procedure precision or accuracy.We found targeting precision 1 mm (standard deviation) for locating the entry hole and ~ 1° (SD) for both version and inclination. The latter value was markedly lower than the end-to-end angular precision achieved by previously reported TSA navigation systems (approximately 3°-5° SD).We conclude that variability during the targeting phase represents a small fraction of the overall variability exhibited by existing systems, so a less obtrusive navigation system for TSA based on laser-engraved tooling is likely feasible, which could improve the uptake rates of surgical navigation for TSA, thereby potentially leading to improved overall surgical outcomes.

Hyperlactatemia develops intraoperatively during cardiac surgery and is associated with postoperative mortality. This study aimed to determine the factors that lead to an increase in lactate during cardiopulmonary bypass (CPB) in neonates undergoing cardiac surgery.Retrospective study from July 2015 to December 2018.Academic tertiary children's hospital.The study comprised 376 neonates.No interventions were performed.Lactate measurements at prebypass, upon initiation of CPB and before coming off CPB, last in the operating room, and first in the cardiac intensive care unit were collected. The changes in lactate levels were compared using the nonparametric Wilcoxon signed rank test for paired data. Univariate and multivariate median regression models of the change during CPB were determined. The cohort characteristics were male (60%), median age 5 days (range 1-30), and weight 3.2 kg (range 1.5-4.7). Most patients had a STAT score of 4 (45%) or 5 (23%). Significant increases in lactate were observed from pre-CPB to start of CPB (p0.001) and from start to end of CPB (p0.001). In the multivariate regression analysis, duration of circulatory arrest (coefficient = 1.216; 95% confidence interval [CI] 0.754-1.678; p0.001), duration of mean arterial pressure25 mmHg (coefficient = 0.423; 95% CI 0.196-to- 0.651; p0.001), and duration of mean arterial pressure between 35 and 39 mmHg (coefficient = -0.246; 95% CI -0.397 to -0.095; p = 0.001) were identified as significant independent predictors of the lactate change per 30- minutes duration.These results emphasized the importance of blood pressure management during CPB and the importance of the duration of circulatory arrest.

Introduction: Comparison of two pediatric cases at our institution that utilized bivalirudin for anticoagulation on cardiopulmonary bypass (CPB); a bilateral lung transplant (BLT) and a ventricular assist device (VAD) implantation. Methods: The same bivalirudin protocol was utilized in both cases with an initial bolus of 1 mg/kg administered by the anesthesia team, a 50 mg bolus in the pump prime at the time of the initial patient bolus and an initial infusion rate of 2.5 mg/kg/h, with titration as needed during CPB to maintain kaolin-activated clotting time (K-ACT) values >400 s. Results: The BLT experienced high K-ACT levels (>720 s) for the majority of the case despite decreasing the bivalirudin infusion rate to 0.5 mg/kg/h. The VAD implantation case required the bivalirudin infusion rate to be increased to 5.0 mg/kg/h throughout the case due to low K-ACTs. Conclusion: The literature strongly supports a specific infusion rate1–7 (2.5 mg/kg/h) for bivalirudin anticoagulation during extracorporeal circulation. Clinicians must consider the loss of clotting factors and the administration of blood products while adjusting the bivalirudin infusion during bypass. We have now elected to maintain an infusion rate of ≥0.5 mg/kg/h for bivalirudin anticoagulation at our center, based on institutional experience, though consideration for a higher infusion rate for an added margin of safety should be considered. It is imperative to have a well-developed protocol for the management of these cardiopulmonary bypass patients and we offer our one-page timeline of events to help guide other pediatric centers looking to use bivalirudin anticoagulation.

Background: Malpositioning of the glenoid component in total shoulder arthroplasty (TSA) remains the primary source of loosening. The purpose of this study is firstly, to quantify postoperative glenoid component position in patients having a TSA and secondly, to explore whether glenoid component radiolucency is associated with glenoid position, clinical outcomes and patient-reported measures in the short-term (two year) follow-up period. Methods: This study was a sub-study of a larger clinical trial that included patients who underwent a TSA and who were randomized into two different glenoid types with a minimum two-year follow-up period. Post-operative radiographic assessments (six weeks and two years) were used to measure glenoid component position (version, inclination, offset) and humeral head centering anterior���posterior (AP) and superior���inferior (SI), and to assess glenoid component radiolucent scoring (modified Lazarus). Pre-operative X-rays were used to measure glenoid version, inclination and Walch classification. Patient-reported measures (PROMs) included the EQ-5D health slider and the Western Ontario Osteoarthritis (WOOS) and American Shoulder and Elbow Surgeons (ASES) score and were captured at baseline and two years postoperative. Clinical outcomes including range of motion and complications were also documented. Statistical analysis included t-tests and regression modeling. Results: Ninety-one patients with an average age of 69.9 �� 6.2 years were included in this study. Glenoid component position improved significantly in version (���19.4 �� 8.6�� to ���17.7 �� 8.5��; p < 0.045) and inclination (11.5 �� 7.1�� to 5.9 �� 6.3��; p < 0.00001) from preoperative to six weeks postoperative. Glenoid component offset in SI and humeral head centering in AP remained unchanged throughout the follow-up. Radiolucency (Lazarus classification) was recorded in 21 cases (17.3%) with a Lazarus score of 1 (15 cases) and 2 (6 cases). The EQ-5D health slider, WOOS and ASES, and ROM confirmed continuous improvements from the preoperative scores to the two-year follow-up (p < 0.05). Regression models showed no correlation between glenoid component radiolucency at two years and the postoperative week six glenoid component position; however, female gender was a significant variable. Conclusion: Glenoid component changes from its original native glenoid were observed following TSA. Glenoid inclination was improved more than version from baseline, and the humeral head remained well-centered in AP and SI at two years. Radiolucency of the glenoid at two years is not negatively associated with PROMs or component position; however, female gender was identified as a significant predictor and warrants further investigation. Complications are not associated with glenoid position or radiolucency, but longer-term follow-up is required.

Objective To analyze findings and trends on serial electrocardiograms (ECGs) in multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease taken during the course of illness and at follow-up. Study design We included all children presenting with MIS-C at a single center with 3 or more ECGs taken during the course of their illness. We measured ECG intervals (PR, QRSd, and QTc) and amplitudes (R-, S-, and T-waves) on each ECG and documented any arrhythmias and ST-segment changes. Results A majority of children (n = 42, 67%) showed ECG changes. The most common findings were low QRS amplitudes and transient T-wave inversion. ST changes were uncommon and included ST-segment elevation consistent with pericarditis in 1 child and acute coronary ischemia in 1 child. Arrhythmias were seen in 13 children (21%) but were benign with the exception of 1 child who was compromised by an atrial tachycardia requiring support with extracorporeal membrane oxygenation. No children were found to have high-grade atrioventricular block. Conclusions MIS-C is associated with electrocardiographic changes over the course of the illness, with low amplitude ECGs on presentation, followed by transient T-wave inversion, particularly in the precordial leads. There was a low prevalence of ST-segment changes and tachyarrhythmias.

Aims Patent ductus arteriosus (PDA) is common in preterm infants and can contribute to morbidity and mortality. We aimed to compare results and outcome of transcatheter closure using the Amplatzer Piccolo Occluder versus surgical closure in 2 matched groups of preterm infants weighing Methods and results A total of 147 babies from three tertiary centres were retrospectively analysed. Sixty-four babies undergoing catheter closure were compared with 83 matched surgical cases. Patent ductus arteriosus closure was successful in all cases. During neonatal unit course, mortality was 6.3% (n = 4) after catheterization and 12% (n = 10) after surgery (p = 0.24). Median duration of mechanical ventilation was shorter after catheterisation than after surgery (3 vs 5 days, p = 0.035). Before 4 weeks of age the difference between transcatheter and surgical closure for mechanical ventilation was even more pronounced (3 vs 9 days, p = 0.022). Additionally, when catheterisation was performed before 4 weeks, babies were discharged home earlier as compared to those who underwent closure later in life (39+1 vs. 42+1 weeks, p = 0.021). Such difference was not found in the surgical group. Conclusions Transcatheter closure of patent ductus arteriosus is safe, effective and is associated with shorter mechanical ventilation than after surgery. Hospital stay might be shorter when performed earlier in life.

Visual Abstract, Highlights • Inhaled hydrogen gas has been shown to temper the sequelae of ischemic insults. Its application in cardiopulmonary bypass has not been investigated. • Neonatal swine were cannulated to cardiopulmonary bypass and exposed to prolonged circulatory arrest (75 min at 25°C). Swine were randomized to treatment with or without inhaled 2.4% hydrogen gas mixtures for 24 h during and following ischemic injury. Hydrogen-treated swine exhibited significantly less severe brain injury than controls, as quantified by clinical examination, serology, magnetic resonance-graded volume of injury, and histopathology. Hydrogen treatment also decreased renal injury. • The administration of inhaled 2.4% hydrogen gas mixtures through a standard ventilator and anesthesia machine were safe, even in the setting of electrocautery., Summary This study used a swine model of mildly hypothermic prolonged circulatory arrest and found that the addition of 2.4% inhaled hydrogen gas to inspiratory gases during and after the ischemic insult significantly decreased neurologic and renal injury compared with controls. With proper precautions, inhalational hydrogen may be administered safely through conventional ventilators and may represent a complementary therapy that can be easily incorporated into current workflows. In the future, inhaled hydrogen may diminish the sequelae of ischemia that occurs in congenital heart surgery, cardiac arrest, extracorporeal life-support events, acute myocardial infarction, stroke, and organ transplantation.

We describe a quality improvement project (QIP) designed to reduce unnecessary biochemistry samples requested on a paediatric cardiology ward in Great Ormond Street Hospital. Prior to the intervention biochemistry tests were requested on a daily basis by nursing and junior doctor staff at an annual cost of around £27 000 for the ward. The lead author observed that for the majority the true indication for these biochemistry tests was for the purpose of monitoring renal function and plasma electrolytes. However, during a diagnostic analysis trying to understand the behaviours around ordering tests it appeared that a broader profile and more expensive combined test set was being requested that included unnecessary liver and bone profile analyses. A driver diagram identified three areas to target in order to rationalise blood test requests: (1) a critical understanding of the purpose of the test by those requesting the tests; (2) effective communication between professionals; and (3) improved utilisation of the computer system. An education-based QIP was initiated with the aim of reducing requests of these costly, unnecessary combined biochemical tests by half, by supporting and encouraging staff to switch to a simpler renal function assay. The project was designed to be engaging and fun and invited clinical teams to consider the cost of wasted resources in terms of the financial implications for the hospital, and in terms of the wider environmental impact of wasted resources illustrated in terms of estimated carbon dioxide use. This perhaps unusual approach of encouraging an awareness of both financial and environmental cost led to a sustained reduction in the ordering of expensive combined biochemical tests, saving an estimated £11 338 (or 13.5%) on biochemistry tests and around 17.8 tonnes of carbon dioxide across a 32-month follow-up period.

Photovoltaic (PV) solar energy systems are being deployed at an accelerating rate to supply low-carbon electricity worldwide. However, PV is unlikely to economically supply much more than 10% of the world's electricity unless there is a dramatic reduction in the cost of electricity storage. There is an important scientific and technological opportunity to address the storage challenge by developing inexpensive hybrid solar converters that collect solar heat at temperatures between about 200 and 600 °C and also incorporate PV. Since heat can be stored and converted to electricity at relatively low cost, collection of high exergy content (high temperature) solar heat can provide energy that is dispatchable on demand to meet loads that are not well matched to solar insolation. However, PV cells can collect and convert much of the solar spectrum to electricity more efficiently and inexpensively than solar thermal systems. Advances in spectrum-splitting optics, high-temperature PV cells, thermal management and system design are needed for transformational hybrid converters. We propose that maximizing the exergy output from the solar converters while minimizing the cost of exergy can help propel solar energy toward a higher contribution to carbon-free electricity in the long term than the prevailing paradigm of maximizing the energy output while minimizing the cost of energy.

Objective Oxygenators for cardiopulmonary bypass require water flow for their integral heat exchanger. Heater-cooler units are nearly universally used for this requirement. Heater-cooler units pose the risk of aerosolized infection. The Centers for Disease Control and Prevention recommended discontinuing use of Stockert 3T heater-cooler units (LivaNova PLC, London, United Kingdom) in October 2016 because of this risk. We aimed to reduce the risk of aerosolized infection posed by heater-cooler units by eliminating those devices from our operating rooms. Methods The cardiac surgery division collaborated with in-house specialties to engineer a novel wall water system. The design called for service to 4 operating rooms with the actual water mixing valve in an operating room closet. Remote temperature control was mounted next to the heart-lung machine. Primary safety systems built into the water system include 5 μm filtration, pressure regulating and relief valves, flow quantifiers, limits to the hot and chilled input temperatures, and a novel bridge near the heart-lung machine that allows the perfusionist to test the system before patient use and to quickly disconnect the patient in case of system malfunction. In addition, all water line connections can be made with the tubing drained and never under pressure. Results This novel wall water system has successfully provided heat exchanger water flow on 625 patients undergoing congenital heart surgery requiring cardiopulmonary bypass during its first 9 months of use. Conclusions Wall water systems are an option for oxygenator heat exchangers that allow for improved heat exchange performance while reducing the risk of heater-cooler unit–associated infection during cardiac surgery.

The basal plane of graphene has been known to be less reactive than the edges, but some studies observed vacancies in the basal plane after reaction with oxygen gas. Observation of these vacancies has typically been limited to nanometer-scale resolution using microscopic techniques. This work demonstrates the introduction and observation of subnanometer vacancies in the basal plane of graphene by heat treatment in a flow of oxygen gas at low temperature such as 533 K or lower. High-resolution transmission electron microscopy was used to directly observe vacancy structures, which were compared with image simulations. These proposed structures contain C═O, pyran-like ether, and lactone-like groups.

Background Patent ductus arteriosus (PDA) is very common in extremely low birth weight babies and may contribute to prolonged mechanical ventilation, bronchopulmonary dysplasia, renal failure, periventricular leukomalacia and necrotizing enterocolitis. When PDA closure is indicated with failure of medical therapy (cyclooxygenase inhibitors or paracetamol), surgical ligation is usually performed with excellent results. Transcatheter closure has been recently developed with promising results but comparative studies with surgical ligation are lacking. Objectives To compare results and outcomes after transcatheter closure using the Amplatzer Piccolo device versus surgical closure in 2 matched groups of pre-term infants weighing ≤ 3000 g. Methods One hundred and forty seven babies (3 tertiary centres) were retrospectively analysed. Sixty-four patients who underwent transcatheter closure were compared with 83 matched surgical patients, using Wilcoxon signed-rank tests. Results PDA closure was successful in all surgical and transcatheter cases. During NICU course, mortality was 6.3% (n = 4) after transcatheter closure and 12% (n = 10) after surgery (P = 0.24). Median duration of mechanical ventilation was shorter after transcatheter closure than after surgical ligation (3 vs. 5 days, P = 0.035). In babies undergoing duct closure before 4 weeks of age the difference between transcatheter and surgical closure for mechanical ventilation during the NICU course was even more pronounced (3 vs. 9 days, P = 0.022). When transcatheter closure was performed before 4 weeks, babies were discharged home earlier as compared to those who underwent closure later in life (39 + 1 vs. 41 + 5 weeks, P = 0.021). Such difference was not found in the surgical group. Conclusion Transcatheter PDA closure in low birth weight babies is safe, effective and associated with improved mechanical ventilation as compared to surgery. It may offer shorter hospital stay when performed earlier in life.

Anticorrosion and antioxidation surface treatments such as paint or anodization are a foundational component in nearly all industries. Graphene, a single-atom-thick sheet of carbon with impressive impermeability to gases, seems to hold promise as an effective anticorrosion barrier, and recent work supports this hope. We perform a complete study of the short- and long-term performance of graphene coatings for Cu and Si substrates. Our work reveals that although graphene indeed offers effective short-term oxidation protection, over long time scales it promotes more extensive wet corrosion than that seen for an initially bare, unprotected Cu surface. This surprising result has important implications for future scientific studies and industrial applications. In addition to informing any future work on graphene as a protective coating, the results presented here have implications for graphene's performance in a wide range of applications.

S-layers are two-dimensional protein or glycoprotein lattices that cover the surfaces of many bacteria and archaea. Because they constitute the first interface of interaction between microorganisms and their environment, hosts, and predators, they are of great biological interest. Moreover, owing to their nanoscale, periodic, porous structure and relative ease of manipulation, they have the potential to be useful for both nano-biotechnological and materials applications. However, details of the assembly process are not yet known for any Slayer and high resolution structural information is very limited. Herein, we report a two-dimensional (2D) structural analysis of the expanding boundary of an isolated Lysinibacillus sphaericus S-layer (SbpA) growing on a graphene support. The results reveal previously unknown steps in the conformational transformation that drives the well-documented non-classical pathway of S-layer assembly and show how the fully-folded oligomeric repeating unit is entropically locked into the ordered array. In addition, our results provide the first demonstration that the unique physical properties of graphene offer superior image quality for cryogenic transmission electron microscopy (cryo-TEM) of biological macromolecules. S-layers assemble from a single protein or glycoprotein sequence to form a 2D lattice that covers the entire cell surface of microorganisms, including the cell poles and division sites. They are non-covalently attached to peptidoglycans and related polymers of gram-positive cell walls, linked to the outer membrane of gram-negative bacterial cell walls, and integrated into the cytoplasmic membrane through trans-membrane domains in gram-negative archaea. The primary sequence of the single protein or glycoprotein species contains all the information needed for assembly. Although they are often called “crystalline” cell surface layers, they are better described as “quasi-crystalline” or “paracrystalline”. S-layers also self-assemble in vitro in the presence of Ca ions, either on support films or in bulk solution, into ordered arrays with long-range order, substantially larger than a single cell. Previous studies found that self-assembly of SbpA (1268 residues from Lysinibacillus sphaericus) on lipid bilayers follows a multi-step pathway. It starts with the aggregation of monomers that adsorb onto the lipids in an extended conformation to form amorphous or liquid-like clusters. These clusters subsequently crystallize into the characteristic lattice of homotetrameric units, which grows by addition of new tetramers to the lattice edge sites. The rate of tetramer addition increases linearly with protein concentration, implying that monomers are added one at a time. However, the pathway through which the individual monomeric units become integrated with the correct conformation into the homotetrameric units—arguably the single most important step in S-layer assembly—remains unknown. To gain insight into S-layer assembly at the level of the tetramer subunits in the intact solution state, we obtained cryo-TEM images of single sheets, plunge-frozen while growing on graphene. Because the active self-assembling Slayers are instantly frozen, all the conformational states present at the expanding boundary on the graphene flat support are captured. Image alignment and averaging provide a view of the steps leading to subunit recruitment and maturation in S-layer self-assembly. For this study, we chose the surface layer protein SbpA (1268 residues), from the gram-positive bacterium Lysinibacillus sphaericus, which naturally forms a 2D quasi-crystalline cell envelope. We carried out the reconstitution of SbpA on single graphene sheets supported by TEM grids designed for cryo-TEM. The great potential of graphene for use as a support for biological cryo-TEM samples has recently been discussed. While mechanically strong and elastic, the 0.246 nm lattice constant and one-atom thickness of a single graphene layer, approximately 0.34 nm, make them trans[*] L. R. Comolli Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA 94720 (USA) E-mail: lrcomolli@lbl.gov

Uniaxial materials whose axial and tangential permittivities have opposite signs are referred to as indefinite or hyperbolic media. While hyperbolic responses are normally achieved with metamaterials, hexagonal boron nitride (hBN) naturally possesses this property due to the anisotropic phonons in the mid-infrared. Using scattering-type scanning near-field optical microscopy, we studied polaritonic phenomena in hBN. We performed infrared nano-imaging of highly confined and low-loss hyperbolic phonon polaritons in hBN. The polariton wavelength was shown to be governed by the hBN thickness according to a linear law persisting down to few atomic layers [1]. Additionally, we carried out the modification of hyperbolic response in meta-structures comprised of a mononlayer graphene deposited on hBN [2]. Electrostatic gating of the top graphene layer allows for the modification of wavelength and intensity of hyperbolic phonon polaritons in bulk hBN. The physics of the modification originates from the plasmon-phonon coupling in the hyperbolic medium. Furthermore, we demonstrated the “hyperlens” for subdiffractional focusing and imaging using a slab of hBN [3]. References [1] S. Dai et al., Science, 343, 1125 (2014). [2] S. Dai et al., Nature Nanotechnology, 10, 682 (2015). [3] S. Dai et al., Nature Communications, 6, 6963 (2015).

We demonstrate a process for batch production of large-area (100-3000 μrn2) patterned freestanding graphene membranes on Cu scaffolds using chemical vapor deposition (CVD)-grown graphene. This technique avoids the use of silicon and transfers of graphene. As one application of this technique, we fabricate transmission electron microscopy (TEM) sample supports. TEM characterization of the graphene membranes reveals relatively clean, highly TEM-transparent, single-layer graphene regions (∼50% by area) and, despite the polycrystalline nature of CVD graphene, membrane yields as high as 75-100%. This high yield verifies that the intrinsic strength and integrity of CVD-grown graphene films is sufficient for sub-100 μm width membrane applications. Elemental analysis (electron energy loss spectroscopy (EELS) and X-ray energy-dispersive spectroscopy (EDS)) of the graphene membranes reveals some nanoscaled contamination left over from the etching process, and we suggest several ways to reduce this contamination and improve the quality of the graphene for electronic device applications. This large-scale production of suspended graphene membranes facilitates access to the two-dimensional physics of graphene that are suppressed by substrate interactions and enables the widespread use of graphene-based sample supports for electron and optical microscopy. © 2010 American Chemical Society.

Insects and hummingbirds remain unmatched in their aerodynamic ability to hover in place in addition to other acrobatic feats such as flying backward and sideways by exploiting flapping-wing motion. Although this remarkable ability is key to making small-scale aircraft, flapping-hovering behavior has been difficult to reproduce artificially because of the challenging stability, power, and aeroelastic phenomena involved. Recent interest in small-scale unmanned air vehicles, especially those capable of hovering like insects and hummingbirds, is driven by many potential applications. A number of flapping machines have been developed, but only two are capable of untethered hovering flight. A key challenge is to demonstrate a stable untethered flapping-hovering ability at a weight and power approximating that of insects and birds where flapping-hovering flight is observed in nature. Here we demonstrate, for the first time, a passively stable 24-g machine capable of flapping-hovering flight at a Reynolds number similar to insects (Re = 8 times 103). This architecture, particularly the passive stability, may help in the design of insect-sized hovering vehicles as well as shed light on the aeroelastic dynamic principles underlying insect flight.

Relativistic quantum mechanics predicts that when the charge of a superheavy atomic nucleus surpasses a certain threshold, the resulting strong Coulomb field causes an unusual atomic collapse state; this state exhibits an electron wave function component that falls toward the nucleus, as well as a positron component that escapes to infinity. In graphene, where charge carriers behave as massless relativistic particles, it has been predicted that highly charged impurities should exhibit resonances corresponding to these atomic collapse states. We have observed the formation of such resonances around artificial nuclei (clusters of charged calcium dimers) fabricated on gated graphene devices via atomic manipulation with a scanning tunneling microscope. The energy and spatial dependence of the atomic collapse state measured with scanning tunneling microscopy revealed unexpected behavior when occupied by electrons., 3 figures

Background Aortic atresia or severe aortic stenosis and left ventricular outflow tract obstruction is a frequent component of complex congenital heart disease. Aortic atresia or severe aortic stenosis and left ventricular outflow tract obstruction with two adequate ventricles is sometimes treated by Norwood palliation followed by late biventricular repair. We reviewed our experience with primary biventricular repair in this group of neonates. Methods Retrospective review identified 17 neonates (10 males) with aortic atresia or severe left ventricular outflow tract obstruction with ventricular septal defect and an adequate left ventricle undergoing primary biventricular repair between 1986 and 2002. Mean age was 7.7 ± 2.9 days, weight 3.3 ± 0.7 kg, and body surface area 0.21 ± 0.04 kg/m 2 . Associated anomalies included arch hypoplasia, 7 (41%); aortic atresia, 7 (41%); and coarctation, 5 (29%). Results are reported as mean ± standard deviation. Results Median follow-up was 6 years (range, 1 to 17.7 years). Three of the 17 (18%) died within 30 days. There were no deaths in this series since 1992. Nine patients (38.9%) required one reoperation, 7 of which were for conduit stenosis, 1 for left ventricular outflow tract obstruction, and 1 for residual ventricular septal defect with left ventricle–to–right atrium shunt. Freedom from death at 10 years was 82% by Kaplan–Meier estimate. Conclusions Excellent long-term survival can be achieved by primary biventricular repair as corroborated by our survival rate of 82%. Primary biventricular repair is an effective operation for aortic atresia and severe left ventricular outflow tract obstruction with adequate sized left ventricle that avoids interstage attrition associated with Norwood palliation and is our procedure of choice.

Graphene resonators are fabricated using a polymer-free, direct transfer method onto metal reinforced holey carbon grids. The resonators are distinguished by the absence of organic residues and excellent crystallinity. The normal mode frequencies are measured using a Fabry–Perot technique; resonance curves indicate highly linear behaviour but very little built-in strain, which is consistent with device geometry examined by atomic force microscopy. We conclude that the oscillators' restoring force is due instead to graphene's intrinsic bending rigidity; our measurements indicate a value of approximately 1.0 eV, consistent with previous theoretical and experimental work. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities., United States. Air Force Office of Scientific Research (Grant FA9550-11-1-0225)

Recently discovered production techniques allow the synthesis of carbon nanostructured films with large surface areas. The abundance of carbon and the unique properties of these nanostructures, including high transparency and excellent electrical conductivity, make these materials very interesting for photovoltaic applications, in particular in combination with amorphous silicon. We examine the properties of thin carbon nanotube films (buckypaper) and graphene in junctions with undoped amorphous silicon thin films. The observed open-circuit voltages, 390 mV for the carbon nanotube film and 150 mV for graphene, suggest that solar cells with high efficiency can be produced without expensive processing steps like doping, multilayer film deposition in high vacuum, or transparent conducting oxide deposition. The buckypaper cells are stable in ambient conditions for many weeks, at least.

We present a novel photovoltaic cell architecture based on the electric field effect that controls carrier concentration in semiconductors using screening-engineered nanostructured electrodes. The device operates in inversion mode, with a top gate that forms a depletion layer and a p-n junction, and with nanostructured electrodes that collect the photocurrent across the junction. This architecture does not require any doping process or a heterojunction, opening an alternative path to fabricate cells on hard-to-dope materials such as oxides or phosphides. As a proof of concept, we present a field effect solar cell made of Si. To demonstrate the potential of this configuration for alternative materials, we also present a field-effect solar cell made of cuprous oxide, which has a favorable band gap but that is difficult to dope. We control the behavior of the devices with the gate voltage that forms an inversion layer and hence a rectifying p-n junction.

The effect of charge-carrier screening on the transport properties of a neutral graphene sheet is studied by directly probing its electronic structure. We find that the Fermi velocity, Dirac point velocity, and overall distortion of the Dirac cone are renormalized due to the screening of the electron-electron interaction in an unusual way. We also observe an increase of the electron mean free path due to the screening of charged impurities. These observations help us to understand the basis for the transport properties of graphene, as well as the fundamental physics of these interesting electron-electron interactions at the Dirac point crossing., Comment: Please see the published PRL at http://link.aps.org/doi/10.1103/PhysRevLett.110.146802

Photovoltaics (PV) are a promising source of clean renewable energy, but current technologies face a cost-to-efficiency trade-off that has slowed widespread implementation. We have developed a PV architecture-screening-engineered field-effect photovoltaics (SFPV)-that in principle enables fabrication of low-cost, high efficiency PV from virtually any semiconductor, including the promising but hard-to-dope metal oxides, sulfides, and phosphides. Prototype SFPV devices have been constructed and are found to operate successfully in accord with model predictions.

We present a systematic Raman study of unconventionally-stacked double-layer graphene, and find that the spectrum strongly depends on the relative rotation angle between layers. Rotation-dependent trends in the position, width and intensity of graphene 2D and G peaks are experimentally established and accounted for theoretically. Our theoretical analysis reveals that changes in electronic band structure due to the interlayer interaction, such as rotational-angle dependent Van Hove singularities, are responsible for the observed spectra features. Our combined experimental and theoretical study provides a deeper understanding of the electronic band structure of rotated double-layer graphene, and leads to a practical way to identify and analyze rotation angles of misoriented double-layer graphene., To appear in Phys. Rev. Lett., added extra data, 22 pages with 10 figures (including 6 supplementary figures)

The Fermi velocity is one of the key concepts in the study of a material, as it bears information on a variety of fundamental properties. Upon increasing demand on the device applications, graphene is viewed as a prototypical system for engineering Fermi velocity. Indeed, several efforts have succeeded in modifying Fermi velocity by varying charge carrier concentration. Here we present a powerful but simple new way to engineer Fermi velocity while holding the charge carrier concentration constant. We find that when the environment embedding graphene is modified, the Fermi velocity of graphene is (i) inversely proportional to its dielectric constant, reaching ~2.5$\times10^6$ m/s, the highest value for graphene on any substrate studied so far and (ii) clearly distinguished from an ordinary Fermi liquid. The method demonstrated here provides a new route toward Fermi velocity engineering in a variety of two-dimensional electron systems including topological insulators., Comment: accepted in Scientific Reports

The response of Dirac fermions to a Coulomb potential is predicted to differ significantly from how non-relativistic electrons behave in traditional atomic and impurity systems. Surprisingly, many key theoretical predictions for this ultra-relativistic regime have not been tested. Graphene, a two-dimensional material in which electrons behave like massless Dirac fermions, provides a unique opportunity to test such predictions. Graphene’s response to a Coulomb potential also offers insight into important material characteristics, including graphene’s intrinsic dielectric constant, which is the primary factor determining the strength of electron–electron interactions in graphene. Here we present a direct measurement of the nanoscale response of Dirac fermions to a single Coulomb potential placed on a gated graphene device. Scanning tunnelling microscopy was used to fabricate tunable charge impurities on graphene, and to image electronic screening around them for a Q = +1|e| charge state. Electron-like and hole-like Dirac fermions were observed to respond differently to a Coulomb potential. Comparing the observed electron–hole asymmetry to theoretical simulations has allowed us to test predictions for how Dirac fermions behave near a Coulomb potential, as well as extract graphene’s intrinsic dielectric constant: ε[subscript g] = 3.0±1.0. This small value of ε[subscript g] indicates that electron–electron interactions can contribute significantly to graphene properties., United States. Office of Naval Research. Multidisciplinary University Research Initiative (Award N00014-09-1-1066), United States. Dept. of Energy. Office of Science (Contract DE-AC02-05CH11231), National Science Foundation (U.S.) (Award DMR-0906539)

The understanding of crack formation due to applied stress is key to predicting the ultimate mechanical behavior of many solids. Here we present experimental and theoretical studies on cracks or tears in suspended monolayer graphene membranes. Using transmission electron microscopy, we investigate the crystallographic orientations of tears. Edges from mechanically induced ripping exhibit straight lines and are predominantly aligned in the armchair or zigzag directions of the graphene lattice. Electron-beam induced propagation of tears is also observed. Theoretical simulations account for the observed preferred tear directions, attributing the observed effect to an unusual nonmonotonic dependence of graphene edge energy on edge orientation with respect to the lattice. Furthermore, we study the behavior of tears in the vicinity of graphene grain boundaries, where tears surprisingly do not follow but cross grain boundaries. Our study provides significant insights into breakdown mechanisms of graphene in the presence of defective structures such as cracks and grain boundaries.

We report a new and highly versatile approach to artificial layered materials synthesis which borrows concepts of molecular beam epitaxy, self-assembly, and graphite intercalation compounds. It readily yields stacks of graphene (or other two-dimensional sheets) separated by virtually any kind of “guest” species. The new material can be “sandwich like”, for which the guest species are relatively closely spaced and form a near-continuous inner layer of the sandwich, or “veil like”, where the guest species are widely separated, with each guest individually draped within a close-fitting, protective yet atomically thin graphene net or veil. The veils and sandwiches can be intermixed and used as a two-dimensional platform to control the movements and chemical interactions of guest species.

The use of boron nitride (BN) as a substrate for graphene nanodevices has attracted much interest since the recent report that BN greatly improves the mobility of charge carriers in graphene compared to standard SiO(2) substrates. We have explored the local microscopic properties of graphene on a BN substrate using scanning tunneling microscopy. We find that BN substrates result in extraordinarily flat graphene layers that display microscopic Moiré patterns arising from the relative orientation of the graphene and BN lattices. Gate-dependent dI/dV spectra of graphene on BN exhibit spectroscopic features that are sharper than those obtained for graphene on SiO(2). We observe a significant reduction in local microscopic charge inhomogeneity for graphene on BN compared to graphene on SiO(2).

We report direct mapping of the grains and grain boundaries (GBs) of large-area monolayer polycrystalline graphene sheets, at large (several micrometer) and single-atom length scales. Global grain and GB mapping is performed using electron diffraction in scanning transmission electron microscopy (STEM) or using dark-field imaging in conventional TEM. Additionally, we employ aberration-corrected TEM to extract direct images of the local atomic arrangements of graphene GBs, which reveal the alternating pentagon-heptagon structure along high-angle GBs. Our findings provide a readily adaptable tool for graphene GB studies.

Several authors have described methods to track perfusion and cardiac surgical morbidity and mortality as well as perfusion accidents. There is currently not a standard definition of a perfusion accident nor is there a standard reporting threshold for events which do not directly cause known morbidity. We propose the term non-routine events (NREs) instead of accidents, and provide a working definition and reporting threshold for such. This paper describes the program which we developed to track perfusion NREs within the Cardiovascular Program at Children’s Hospital, Boston. NREs are categorized by type (technique, equipment, or patient-related) and bypass period (pre-cardiopulmonary bypass, bypass, or post-cardiopulmonary). NRE outcomes are also classified by the level of discussion or change in perfusion practice after multidisciplinary review. We have documented during a 44 month interval that 42% (29/69) of reported NREs occur during the bypass period and are equipment related and thus, efforts to improve practice should focus there. We have also seen a generally decreasing incidence of NREs requiring either a change in perfusion practice or a new protocol during this time period. We believe that our regular multidisciplinary meetings to discuss NREs have increased awareness among the entire team about potential problems in the program and that intuitively, it has improved patient safety.

The folding of paper, hide, and woven fabric has been used for millennia to achieve enhanced articulation, curvature, and visual appeal for intrinsically flat, two-dimensional materials. For graphene, an ideal two-dimensional material, folding may transform it to complex shapes with new and distinct properties. Here, we present experimental results that folded structures in graphene, termed grafold, exist, and their formations can be controlled by introducing anisotropic surface curvature during graphene synthesis or transfer processes. Using pseudopotential-density functional theory calculations, we also show that double folding modifies the electronic band structure of graphene. Furthermore, we demonstrate the intercalation of C60 into the grafolds. Intercalation or functionalization of the chemically reactive folds further expands grafold's mechanical, chemical, optical, and electronic diversity., Comment: 29 pages, 10 figures (accepted in Phys. Rev. B)

Solar radiation provokes a lifelong series of destructive changes in the supporting elastic tissues of "exposed" skin. Called actinic elastosis/lysis (or actinic "aging"), the sequence begins in early life as simple elastic hyperplasia, converts in middle life to progressive actinic elastotic degeneration, and, in late life, typically ends with a stage of resorption (elastolysis) and atrophy ("aged" skin). Superficial "exposed" arteries such as the temporal artery participate in the same sequence of degenerative elastotic changes, which, as in the skin, may provoke granulomatous responses in a few of the many subjects affected. In the case of the temporal artery, a contingent outcome may be giant cell (temporal) arteritis and its recognized systemic vascular expression, polymyalgia rheumatica. Actinic commotion at the surface of the body is often massive in degree and extent and may be expected to exert a deleterious autoimmune impact on the essential elastic tissues of the arterial system. For this reason, solar radiation should be recognized as a risk factor for other elastic-related vascular diseases, including atherosclerosis and aneurysms. Man-made radiations may be exacerbating the effects of predominant solar radiation. Of the many radiant bands that make up the actinic (electromagnetic) spectrum, little is known for certain about the identity of those that cause these prevalent disorders of elastic tissue. Until this void is filled, more care should be taken with solar and the other "safe" radiations.