Performance of the Quadripolar CRT-D system: 5-Year Results from the Quadripolar Pacing Post Approval Study.

BACKGROUND: Cardiac resynchronization therapy (CRT) is associated with challenges such as elevated capture thresholds, diaphragmatic stimulation, and lead instability. OBJECTIVE: Assess the chronic safety and efficacy of the quadripolar CRT-D device system with the Quartet 1458Q Left Ventricular (LV) lead in a CRT-indicated population followed for 5 years and evaluate all-cause mortality and impact of baseline characteristics on survival through 5 years. METHODS: Patients indicated for a CRT-D system were followed every 6 months post-implant for 5 years and assessed device performance and adverse events at each visit. The three primary endpoints were freedom from quadripolar CRT-D system-related complications through 5 years, freedom from Quartet 1458Q LV lead-related complications through 5 years, and the mean programmed pacing capture threshold at 5 years. RESULTS: The study enrolled 1,970 subjects at 71 sites. The quadripolar CRT-D system was successfully implanted in 97.2% of subjects. Freedom from quadripolar CRT-D device system-related complications through 5 years was 89.7% and freedom from Quartet 1458Q LV lead-related complications through 5 years was 95.7%. 3.49 % of subjects had LV lead-related complications and an overall LV lead complication rate was 0.0122 events per subject-year. A mean LV pacing capture threshold was 1.52 ± 1.01 V at 5 years. The 5-year survival rate was 67.4%. CONCLUSION: The quadripolar CRT-D system with the Quartet 1458Q LV lead exhibited low rates of complications and stable electrical performance through 5 years of follow-up and suggested a higher 5-year survival rate compared to traditional CRT systems.

Technical-tactical behavior analysis of general duty police officers during non-compliant suspect apprehensions: A novel approach to establish minimum force requirements.

BACKGROUND: While effective apprehensions of non-compliant suspects are central to public safety, the minimal force needed to transition a suspect from standing to the ground, vital for apprehension success, has not been established. OBJECTIVE: To examine the technical-tactical behaviors of general duty police officers during simulated apprehensions and quantify the minimum force required to destabilize non-compliant suspects. METHODS: Task simulations conducted with 91 officers were analyzed to identify common grappling movements, strikes, control tactics, and changes in body posture. A separate assessment of 55 male officers aimed to determine the minimum force required for destabilization in five body regions (wrist, forearm, shoulder, mid-chest, and mid-back). Data are presented as mean±standard deviation. RESULTS: On average, apprehensions took 7.3±3.2 seconds. While all officers used grappling movements (100%) and the majority employed control tactics (75%), strikes were seldom used (4%). Apprehensions typically began with a two-handed pull (97%; Contact Phase), 55% then attempted an arm bar takedown, followed by a two-handed cross-body pull (68%; Transition/Control Phase), and a two-handed push to the ground (19%; Ground Phase). All officers began in the upright posture, with most shifting to squat (75%), kneel (58%), or bent (45%) postures to complete the apprehension. The minimum force required to disrupt balance differed across body regions (wrist: 54±12 kg; forearm: 49±12 kg; shoulder: 42±10 kg; mid-chest: 44±11 kg; mid-back: 30±7 kg, all P < 0.05), except between the shoulder and chest (P = 0.19). CONCLUSION: These findings provide insights that can enhance the design and accuracy of future apprehension evaluations and inform the optimization of law enforcement physical employment standards.

Gas-phase microactuation using kinetically controlled surface states of ultrathin catalytic sheets.

Biological systems convert chemical energy into mechanical work by using protein catalysts that assume kinetically controlled conformational states. Synthetic chemomechanical systems using chemical catalysis have been reported, but they are slow, require high temperatures to operate, or indirectly perform work by harnessing reaction products in liquids (e.g., heat or protons). Here, we introduce a bioinspired chemical strategy for gas-phase chemomechanical transduction that sequences the elementary steps of catalytic reactions on ultrathin (<10 nm) platinum sheets to generate surface stresses that directly drive microactuation (bending radii of 700 nm) at ambient conditions (T = 20 °C; Ptotal = 1 atm). When fueled by hydrogen gas and either oxygen or ozone gas, we show how kinetically controlled surface states of the catalyst can be exploited to achieve fast actuation (600 ms/cycle) at 20 °C. We also show that the approach can integrate photochemically controlled reactions and can be used to drive the reconfiguration of microhinges and complex origami- and kirigami-based microstructures.

Automatic parameter selection for electron ptychography via Bayesian optimization.

Electron ptychography provides new opportunities to resolve atomic structures with deep sub-angstrom spatial resolution and to study electron-beam sensitive materials with high dose efficiency. In practice, obtaining accurate ptychography images requires simultaneously optimizing multiple parameters that are often selected based on trial-and-error, resulting in low-throughput experiments and preventing wider adoption. Here, we develop an automatic parameter selection framework to circumvent this problem using Bayesian optimization with Gaussian processes. With minimal prior knowledge, the workflow efficiently produces ptychographic reconstructions that are superior to those processed by experienced experts. The method also facilitates better experimental designs by exploring optimized experimental parameters from simulated data.

Binocular Viewing Facilitates Size Constancy for Grasping and Manual Estimation.

A prerequisite for efficient prehension is the ability to estimate an object's distance and size. While most studies demonstrate that binocular viewing is associated with a more efficient grasp programming and execution compared to monocular viewing, the factors contributing to this advantage are not fully understood. Here, we examined how binocular vision facilitates grasp scaling using two tasks: prehension and manual size estimation. Participants (n = 30) were asked to either reach and grasp an object or to provide an estimate of an object's size using their thumb and index finger. The objects were cylinders with a diameter of 0.5, 1.0, or 1.5 cm placed at three distances along the midline (40, 42, or 44 cm). Results from a linear regression analysis relating grip aperture to object size revealed that grip scaling during monocular viewing was reduced similarly for both grasping and estimation tasks. Additional analysis revealed that participants adopted a larger safety margin for grasping during monocular compared to binocular viewing, suggesting that monocular depth cues do not provide sufficient information about an object's properties, which consequently leads to a less efficient grasp execution.

Cilia metasurfaces for electronically programmable microfluidic manipulation.

Cilial pumping is a powerful strategy used by biological organisms to control and manipulate fluids at the microscale. However, despite numerous recent advances in optically, magnetically and electrically driven actuation, development of an engineered cilial platform with the potential for applications has remained difficult to realize1-6. Here we report on active metasurfaces of electronically actuated artificial cilia that can create arbitrary flow patterns in liquids near a surface. We first create voltage-actuated cilia that generate non-reciprocal motions to drive surface flows at tens of microns per second at actuation voltages of 1 volt. We then show that a cilia unit cell can locally create a range of elemental flow geometries. By combining these unit cells, we create an active cilia metasurface that can generate and switch between any desired surface flow pattern. Finally, we integrate the cilia with a light-powered complementary metal-oxide-semiconductor (CMOS) clock circuit to demonstrate wireless operation. As a proof of concept, we use this circuit to output voltage pulses with various phase delays to demonstrate improved pumping efficiency using metachronal waves. These powerful results, demonstrated experimentally and confirmed using theoretical computations, illustrate a pathway towards fine-scale microfluidic manipulation, with applications from microfluidic pumping to microrobotic locomotion.

Micrometer-sized electrically programmable shape-memory actuators for low-power microrobotics.

Shape-memory actuators allow machines ranging from robots to medical implants to hold their form without continuous power, a feature especially advantageous for situations where these devices are untethered and power is limited. Although previous work has demonstrated shape-memory actuators using polymers, alloys, and ceramics, the need for micrometer-scale electro-shape-memory actuators remains largely unmet, especially ones that can be driven by standard electronics (~1 volt). Here, we report on a new class of fast, high-curvature, low-voltage, reconfigurable, micrometer-scale shape-memory actuators. They function by the electrochemical oxidation/reduction of a platinum surface, creating a strain in the oxidized layer that causes bending. They bend to the smallest radius of curvature of any electrically controlled microactuator (~500 nanometers), are fast (<100-millisecond operation), and operate inside the electrochemical window of water, avoiding bubble generation associated with oxygen evolution. We demonstrate that these shape-memory actuators can be used to create basic electrically reconfigurable microscale robot elements including actuating surfaces, origami-based three-dimensional shapes, morphing metamaterials, and mechanical memory elements. Our shape-memory actuators have the potential to enable the realization of adaptive microscale structures, bio-implantable devices, and microscopic robots.

Small decreases in biventricular pacing percentages are associated with multiple metrics of worsening heart failure as measured from a cardiac resynchronization therapy defibrillator.

BACKGROUND: Lower BiVentricular (BiV) pacing percentages have been associated with significantly worse survival in patients with chronic heart failure (HF). However, the pathophysiology behind this observation has not been further delineated. This analysis evaluated whether small incremental decreases in BiV pacing percentages were associated with worse measures, related to HF physiology using individual sensor trends and the HeartLogic composite index. METHODS: Sensor data was obtained from 900 ambulatory HF patients with implanted CRT devices. The percent of cardiac cycles with BiV pacing was assessed for periods (median = 7.3 days) between data downloads (median = 55 periods/patient). RESULTS: The third heart sound (S3), respiration rate, RSBI, and night-time heart rate were significantly elevated with sub-optimal pacing (<98%), while the first heart sound (S1), thoracic impedance, and activity were significantly lower. All sensor changes were in the direction associated with worsening HF. While IN the HeartLogic alert state (threshold above an Index of 16) the odds of optimal BiV pacing (≥98%) were less than when OUT of the HeartLogic alert state for a given subject (OR: 0.655; 95% CI: 0.626-0.686; p < 0.0001). The percent BiV pacing was reduced and the HeartLogic Index was increased in the periods surrounding HFhospitalizations. CONCLUSION: Lower BiV pacing percent is associated with multiple sensor changes indicative of worsening HF, and patients in HeartLogic alert are more likely to have suboptimal BiV pacing. Collectively, these data provide strong evidence that even small decreases in BiV percent pacing can lead to worsening HF.

Crystal orientation dictated epitaxy of ultrawide-bandgap 5.4- to 8.6-eV α-(AlGa)2O3 on m-plane sapphire.

Ultrawide-bandgap semiconductors are ushering in the next generation of high-power electronics. The correct crystal orientation can make or break successful epitaxy of such semiconductors. Here, it is found that single-crystalline layers of α-(AlGa)2O3 alloys spanning bandgaps of 5.4 to 8.6 eV can be grown by molecular beam epitaxy. The key step is found to be the use of m-plane sapphire crystal. The phase transition of the epitaxial layers from the α- to the narrower bandgap ß-phase is catalyzed by the c-plane of the crystal. Because the c-plane is orthogonal to the growth front of the m-plane surface of the crystal, the narrower bandgap pathways are eliminated, revealing a route to much wider bandgap materials with structural purity. The resulting energy bandgaps of the epitaxial layers span a broad range, heralding the successful epitaxial stabilization of the largest bandgap materials family to date.

Probing the binding modes and dynamics of histidine on fumed silica surfaces by solid-state NMR.

Silica nanoparticles can be designed to exhibit a diverse range of morphologies (e.g. non-porous, mesoporous), physical properties (e.g. hydrophobic, hydrophilic) and a wide range of chemical and biomolecular surface functionalizations. In the present work, the adsorption complex of histidine (His) and fumed silica nanoparticles (FSN) is probed using thermal analysis (TGA/DTG) and a battery of solid-state (SS) NMR methods supported by DFT chemical shift calculations. Multinuclear (1H/13C/15N) one- and two-dimensional magic angle spinning (MAS) SSNMR experiments were applied to determine site-specific interactions between His and FSN surfaces as a function of adsorption solution concentration, pH and hydration state. By directly comparing SSNMR observables (linewidth, chemical shift and relaxation parameters) for His-FSN adsorption complexes to various crystalline, amorphous and aqueous His forms, the His structural and dynamic environment on FSN surfaces could be determined at an atomic level. The observed 13C and 15N MAS NMR chemical shifts, linewidths and relaxation parameters show that the His surface layer on FSN has a significant dependence on pH and hydration state. His is highly dynamic on FSN surfaces under acidic conditions (pH 4) as evidenced by sharp resonances with near isotropic chemical shifts regardless of hydration level indicating a non-specific binding arrangement while, a considerably more rigid His environment with defined protonation states is observed at near neutral pH with subtle variations between hydrated and anhydrous complexes. At near neutral pH, less charge repulsion occurs on the FSN surface and His is more tightly bound as evidenced by considerable line broadening likely due to chemical shift heterogeneity and a distribution in hydrogen-bonding strengths on the FSN surface. Multiple His sites exchange with a tightly bound water layer in hydrated samples while, direct interaction with the FSN surface and significant chemical shift perturbations for imidazole ring nitrogen sites and some carbon resonances are observed after drying. The SSNMR data was used to propose an interfacial molecular binding model between His and FSN surfaces under varying conditions setting the stage for future multinuclear, multidimensional SSNMR studies of His-containing peptides on silica nanoparticles and other nanomaterials of interest.

Electronically integrated, mass-manufactured, microscopic robots.

Fifty years of Moore's law scaling in microelectronics have brought remarkable opportunities for the rapidly evolving field of microscopic robotics1-5. Electronic, magnetic and optical systems now offer an unprecedented combination of complexity, small size and low cost6,7, and could be readily appropriated for robots that are smaller than the resolution limit of human vision (less than a hundred micrometres)8-11. However, a major roadblock exists: there is no micrometre-scale actuator system that seamlessly integrates with semiconductor processing and responds to standard electronic control signals. Here we overcome this barrier by developing a new class of voltage-controllable electrochemical actuators that operate at low voltages (200 microvolts), low power (10 nanowatts) and are completely compatible with silicon processing. To demonstrate their potential, we develop lithographic fabrication-and-release protocols to prototype sub-hundred-micrometre walking robots. Every step in this process is performed in parallel, allowing us to produce over one million robots per four-inch wafer. These results are an important advance towards mass-manufactured, silicon-based, functional robots that are too small to be resolved by the naked eye.

Imaging Polarity in Two Dimensional Materials by Breaking Friedel's Law.

Friedel's law guarantees an inversion-symmetric diffraction pattern for thin, light materials where a kinematic approximation or a single-scattering model holds. Typically, breaking Friedel symmetry is ascribed to multiple scattering events within thick, non-centrosymmetric crystals. However, two-dimensional (2D) materials such as a single monolayer of MoS2 can also violate Friedel's law, with unexpected contrast between conjugate Bragg peaks. We show analytically that retaining higher order terms in the power series expansion of the scattered wavefunction can describe the anomalous contrast between hkl and hkl¯peaks that occurs in 2D crystals with broken in-plane inversion symmetry. These higher-order terms describe multiple scattering paths starting from the same atom in an atomically thin material. Furthermore, 2D materials containing heavy elements, such as WS2, always act as strong phase objects, violating Friedel's law no matter how high the energy of the incident electron beam. Experimentally, this understanding can enhance diffraction-based techniques to provide rapid imaging of polarity, twin domains, in-plane rotations, or other polar textures in 2D materials.

Bidirectional Self-Folding with Atomic Layer Deposition Nanofilms for Microscale Origami.

Origami design principles are scale invariant and enable direct miniaturization of origami structures provided the sheets used for folding have equal thickness to length ratios. Recently, seminal steps have been taken to fabricate microscale origami using unidirectionally actuated sheets with nanoscale thickness. Here, we extend the full power of origami-inspired fabrication to nanoscale sheets by engineering bidirectional folding with 4 nm thick atomic layer deposition (ALD) SiNx-SiO2 bilayer films. Strain differentials within these bilayers result in bending, producing microscopic radii of curvature. We lithographically pattern these bilayers and localize the bending using rigid panels to fabricate a variety of complex micro-origami devices. Upon release, these devices self-fold according to prescribed patterns. Our approach combines planar semiconductor microfabrication methods with computerized origami design, making it easy to fabricate and deploy such microstructures en masse. These devices represent an important step forward in the fabrication and assembly of deployable micromechanical systems that can interact with and manipulate micro- and nanoscale environments.

Tuning Electrical Conductance of MoS2 Monolayers through Substitutional Doping.

Tuning electrical conductivity of semiconducting materials through substitutional doping is crucial for fabricating functional devices. This, however, has not been fully realized in two-dimensional (2D) materials due to the difficulty of homogeneously controlling the dopant concentrations and the lack of systematic study of the net impact of substitutional dopants separate from that of the unintentional doping from the device fabrication processes. Here, we grow wafer-scale, continuous MoS2 monolayers with tunable concentrations of Nb and Re and fabricate devices using a polymer-free approach to study the direct electrical impact of substitutional dopants in MoS2 monolayers. In particular, the electrical conductivity of Nb doped MoS2 in the absence of electrostatic gating is reproducibly tuned over 7 orders of magnitude by controlling the Nb concentration. Our study further indicates that the dopant carriers do not fully ionize in the 2D limit, unlike in their three-dimensional analogues, which is explained by weaker charge screening and impurity band conduction. Moreover, we show that the dopants are stable, which enables the doped films to be processed as independent building blocks that can be used as electrodes for functional circuitry.

Ambulatory Monitoring of Heart Sounds via an Implanted Device Is Superior to Auscultation for Prediction of Heart Failure Events.

BACKGROUND: We compared the relationship between the third heart sound (S3) measured by an implantable cardiac device (devS3) and auscultation (ausS3) and evaluated their prognostic powers for predicting heart failure events (HFEs). METHODS AND RESULTS: In the MultiSENSE study, devS3 was measured daily with continuous values, whereas ausS3 was assessed at study visits with discrete grades. They were compared among patients with and without HFEs at baseline and against each other directly. Cox proportional hazard models were developed between follow-up visits and over the whole study. Simulations were performed on devS3 to match the limitations of auscultation. We studied 900 patients, of whom 106 patients experienced 192 HFEs. Two S3 sensing modalities correlated with each other, but at baseline, only devS3 differentiated patients with or without HFEs (P < 0.0001). The prognostic power of devS3 was superior to that of ausS3 both between follow-up visits (HR = 5.7, P < 0.0001, and 1.7, P = 0.047, respectively) and over the whole study (HR = 2.9, P < 0.0001, and 1.4, P = 0.216, respectively). Simulation results suggested this superiority may be attributed to continuous monitoring and to subaudible measuring capability. CONCLUSIONS: S3 measured by implantable cardiac devices has stronger prognostic power to predict episodes of future HFEs than that of auscultation.

Nano-folded Gold Catalysts for Electroreduction of Carbon Dioxide.

The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Selectivity is often critical for the practical realization of reactions such as the electroreduction of carbon dioxide (CO2). Previously developed strategies to manipulate the structure and geometry of catalysts for electroreduction of CO2 involve complex processes or fail to efficiently alter the selectivity. Here, using a prestrained polymer, we uniaxially and biaxially compress a 60 nm gold film to form a nano-folded electrocatalyst for CO2 reduction. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of prestrain in the polymer. We characterize the nano-folded catalysts using X-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. We measure an enhancement of Faradaic efficiency for carbon monoxide formation with the biaxially compressed nano-folded catalyst by a factor of about nine as compared to the flat catalyst (up to 87.4%). We rationalize this observation by noting that an increase of the local pH in the tight folds of the catalyst outweighs the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic performance.

A database of predictor test sex bias for development of military physical employment standards.

BACKGROUND: Hesitation to employ females for physically demanding jobs is often due to sex related physical abilities. A physical employment standard (PES) identifies individuals who are physically capable for work. OBJECTIVE: A database containing 300 + sources of physical performance tests (PFTs) will inform potential sex bias for PES development. METHODS: Weighted means and probability density curves illustrate the percentage overlap between male and female performance on PFT data from the armed forces of 11 countries and the open literature. Where female training data were available, the change in percentage overlap illustrates the potential for reduction in sex-related differences. RESULTS: PFTs demonstrating the extremes of sex disparity were bench press (11 sources) and sit-ups (14 sources) with 9% and 93% overlap in performance, respectively. Training for bench press; pull ups; VO2max; and upright pull improved female performance by 12%, 22%, 35%, and 23% respectively. This translated into narrowing the gap between male and female mean performance by 1%, 4%, 5%, and 10% respectively. CONCLUSIONS: The ability of PFT to predict performance is essential; however, PFTs with more overlap will facilitate development of PES with reduced sex bias. PFTs with the greatest potential for improvement in females are identified here.

HeartLogic Multisensor Algorithm Identifies Patients During Periods of Significantly Increased Risk of Heart Failure Events: Results From the MultiSENSE Study.

BACKGROUND: Care of heart failure (HF) patients results in a high burden on healthcare resources, and estimating prognosis is becoming increasingly important to triage resources wisely. Natriuretic peptides are recommended prognosticators in chronic HF. Our objective was to evaluate whether a multisensor HF index and alert algorithm (HeartLogic) replaces or augments current HF risk stratification. METHODS AND RESULTS: MultiSENSE (Multisensor Chronic Evaluation in Ambulatory Heart Failure Patients) enrolled 900 patients with cardiac resynchronization therapy defibrillators enabled for collection of heart sounds, respiration, thoracic impedance, heart rate, and activity data. The HeartLogic algorithm automatically calculated a daily HF index and identified periods IN or OUT of an active alert state relative to a configurable threshold. Patients experienced 192 independently adjudicated HF events (average rate, 0.20/patient-year [pt-yr]) during 1 year of follow-up. HF event rates while IN alert was 10-fold higher than OUT of alert (0.80 versus 0.08 events/pt-yr). Combined with NT-proBNP (N-terminal pro-B-type natriuretic peptide) at enrollment (relative to 1000 pg/mL threshold, event rate was 0.42 [HIGH] versus 0.07 [LOW] events/pt-yr), substratification found the lowest risk group (LOW NT-proBNP and OUT of alert) experienced 0.02 events/pt-yr, whereas the highest risk group (HIGH NT-proBNP and IN alert) was associated with a 50-fold increased risk of an HF event (1.00 events/pt-yr) relative to the lowest risk group. CONCLUSIONS: Dynamic assessment using implantable device sensors within HeartLogic by itself or in conjunction with NT-proBNP measurements can identify time-intervals when patients are at significantly increased risk of worsening HF and potentially better triage resources to this vulnerable patient population. CLINICAL TRIAL REGISTRATION: https://www.clinicaltrials.gov. Unique identifier: NCT01128166.

Strain Mapping of Two-Dimensional Heterostructures with Subpicometer Precision.

Next-generation, atomically thin devices require in-plane, one-dimensional heterojunctions to electrically connect different two-dimensional (2D) materials. However, the lattice mismatch between most 2D materials leads to unavoidable strain, dislocations, or ripples, which can strongly affect their mechanical, optical, and electronic properties. We have developed an approach to map 2D heterojunction lattice and strain profiles with subpicometer precision and the ability to identify dislocations and out-of-plane ripples. We collected diffraction patterns from a focused electron beam for each real-space scan position with a high-speed, high dynamic range, momentum-resolved detector-the electron microscope pixel array detector (EMPAD). The resulting four-dimensional (4D) phase space data sets contain the full spatially resolved lattice information on the sample. By using this technique on tungsten disulfide (WS2) and tungsten diselenide (WSe2) lateral heterostructures, we have mapped lattice distortions with 0.3 pm precision across multimicron fields of view and simultaneously observed the dislocations and ripples responsible for strain relaxation in 2D laterally epitaxial structures.