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Building a modular architecture with superconducting quantum computing chips is one of the means to achieve qubit scalability, allowing the screening, selection, replacement, and integration of individual qubit modules into large quantum systems. However, the nondestructive replacement of modules within a compact architecture remains a challenge. Liquid metals, specifically gallium alloys, can be alternatives to solid-state galvanic interconnects. This is motivated by their self-healing, self-aligning, and other desirable fluidic properties, potentially enabling the nondestructive replacement of modules at room temperatures, even after operating the entire system at millikelvin regimes. In this study, we present coplanar waveguide resonators (CPWRs) interconnected by gallium alloy droplets, achieving high internal quality factors up to nearly one million and demonstrating performance on par with the continuous solid-state CPWRs. Leveraging the desirable fluidic properties of gallium alloys at room temperature and their compact design, we envision a modular quantum system enabled by liquid metals.

We present the coupled oscillator: a new mechanism for signal amplification with widespread application in metrology. We introduce the mechanical theory of this framework, and support it by way of simulations. We present a particular implementation of coupled oscillators: a microelectromechanical system (MEMS) that uses one large (~100mm) N52 magnet coupled magnetically to a small (~0.25mm), oscillating N52 magnet, providing a force resolution of 200zN measured over 1s in a noiseless environment. We show that the same system is able to resolve magnetic gradients of 130aT/cm at a single point (within 500um). This technology therefore has the potential to revolutionize force and magnetic gradient sensing, including high-impact areas such cardiac and brain imaging., Comment: 13 pages, 17 figures

Understanding the structural and functional development of human-induced pluripotent stem-cell-derived cardiomyocytes is essential to engineering cardiac tissue that enables pharmaceutical testing, modeling diseases, and designing therapies. Here we use a method not commonly applied to biological materials, small angle X-ray scattering, to characterize the structural development of human-induced pluripotent stem-cell-derived cardiomyocytes within 3D engineered tissues during their preliminary stages of maturation. An X-ray scattering experimental method enables the reliable characterization of the cardiomyocyte myofilament spacing with maturation time. The myofilament lattice spacing monotonically decreases as the tissue matures from its initial post-seeding state over the span of ten days. Visualization of the spacing at a grid of positions in the tissue provides an approach to characterizing the maturation and organization of cardiomyocyte myofilaments and has the potential to help elucidate mechanisms of pathophysiology, and disease progression, thereby stimulating new biological hypotheses in stem cell engineering.

The chemical activity of ionized hydrogen describes the potency of protons in solution and is used to define the pH with wide-ranging applications in biological and materials sciences. Measuring pH with graphene field-effect transistors (FETs) has been described in the past but has yet to be characterized with a monolayer hexagonal boron nitride (hBN) capping layer. hBN capping is hypothesized to lower the chemical affinity of protons to oxidized defects in the graphene crystal and lower the standard deviation of pH measurement via screening charge density. First, the electronic properties of commercial, monolayer graphene and monolayer hBN/graphene, both on four-inch 90 nm SiO2/p-type Si, were contrasted as a function of solutal pH in 10 mM phosphate buffered solution. The two-dimensional (2D) FETs were fabricated with photoresistless metallization followed by microcentrifuge tube-masking and reactive ion etching to define a quasi-pure 2D sensing mesa for pH sensing. Thereafter, the devices were exposed to phosphate buffer of varying pH and the resistance and liquid-transfer characteristics measured. The hBN/graphene/SiO2 FETs had higher linearity, and both lower standard deviation and range of Dirac voltage shifting than monolayer graphene/SiO2. Then, before microcentrifuge tube-masking, freshly metallized devices were coated with 9 nm of Al2O3 by electron beam deposition. The Al2O3/graphene/SiO2 and Al2O3/hBN/graphene/SiO2 devices showed an altered response to the pH of the phosphate buffered solutions before and after basic etching of the Al2O3 with NaOH (pH = 12). This prompted studying the pH-dependencies of the 2D devices as a function of the thickness of Al2O3 via atomic layer deposition. These results show that modifying the surface of monolayer graphene with nanoscale dielectrics enables tuning of the pH-dependent electronic properties of graphene pH sensors.

Electrical detection of messenger ribonucleic acid (mRNA) is a promising approach to enhancing transcriptomics and disease diagnostics because of its sensitivity, rapidity, and modularity. Reported here is a fast SARS-CoV-2 mRNA biosensor (<1 minute) with a limit of detection of 1 aM, and dynamic range of 4 orders of magnitude and a linear sensitivity of 22 mV per molar decade. These figures of merit were obtained on photoresistlessly patterned monolayer graphene field-effect transistors (FETs) derived from commercial four-inch graphene on 90 nm of silicon dioxide on p-type silicon. Then, to facilitate mRNA hybridization, graphene sensing mesa were coated with an ultrathin sub-percolation threshold gold film for bonding 3'-thiolated single-stranded deoxyribonucleic acid (ssDNA) probes complementary to SARS-CoV-2 nucleocapsid phosphoprotein (N) gene. Sub-percolated gold was used to minimize the distance between the graphene material and surface hybridization events. The liquid-transfer characteristics of the graphene FETs repeatedly shows correlation between the Dirac voltage and the copy number of polynucleotide. Ultrathin percolated gold films on graphene FETs facilitate two-dimensional electron gas (2DEG) mRNA biosensors for transcriptomic profiling., Comment: 15 pages, 6 figures Keywords: transcriptome, virus, monolayer graphene, percolated gold, 2DEG, field-effect transistor

The Casimir Force, a quantum mechanical effect, has been observed in several microelectromechanical systems (MEMS) platforms. Due to its extreme sensitivity to the separation of two objects, the Casimir Force has been proposed as an excellent avenue for quantum metrology. Practical application, however, is challenging due to attractive forces leading to stiction and failure of the device, called Casimir pull-in. In this work, we design and simulate a Casimir-driven metrology platform, where a time-delay based parametric amplification technique is developed to achieve a steady state and avoid pull-in. We apply the design to the detection of weak, low frequency, gradient magnetic fields, similar to those emanating from ionic currents in the heart and brain. Simulation parameters are selected from recent experimental platforms developed for Casimir metrology and magnetic gradiometry, both on MEMS platforms. While MEMS offer many advantages to such an application, the detected signal must typically be at the resonant frequency of the device, with diminished sensitivity in the low frequency regime of biomagnetic fields. Using a Casimir-drive parametric amplifier, we report a 10,000 fold improvement in the best-case resolution of MEMS single-point gradiometers, with a maximum sensitivity of 6 Hz/(pT/cm) at 1 Hz. The development of the proposed design has the potential to revolutionize metrology, and specifically may enable unshielded monitoring of biomagnetic fields in ambient conditions.

We have designed and fabricated a microfluidic-based platform for sensing mechanical forces generated by cardiac microtissues in a highly-controlled microenvironment. Our fabrication approach combines Direct Laser Writing (DLW) lithography with soft lithography. At the center of our platform is a cylindrical volume, divided into two chambers by a cylindrical polydimethylsiloxane (PDMS) shell. Cells are seeded into the inner chamber from a top opening, and the microtissue assembles onto tailor-made attachment sites on the inner walls of the cylindrical shell. The outer chamber is electrically and fluidically isolated from the inner one by the cylindrical shell and is designed for actuation and sensing purposes. Externally applied pressure waves to the outer chamber deform parts of the cylindrical shell and thus allow us to exert time-dependent forces on the microtissue. Oscillatory forces generated by the microtissue similarly deform the cylindrical shell and change the volume of the outer chamber, resulting in measurable electrical conductance changes. We have used this platform to study the response of cardiac microtissues derived from human induced pluripotent stem cells (hiPSC) under prescribed mechanical loading and pacing., Comment: Main article 15 pages, 6 figures, 1 tables; supplementary 11 pages, 7 figures, 1 table, 6 movies

The structural and functional maturation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is essential for application to pharmaceutical testing, disease modeling, and ultimately therapeutic use. Multicellular 3D-tissue platforms have improved functional maturation of hiPSC-CMs, but probing cardiac contractile properties remains challenging in a 3D environment, especially at depth and in live tissues. Using small angle X-ray scattering (SAXS) images, we show that hiPSC-CMs, matured and examined in a 3D environment, exhibit periodic spatial arrangement of the myofilament lattice, which has not been previously detected in hiPSC-CMs. Contractile force is found to correlate with both scattering intensity (R2=0.44) and lattice spacing (R2=0.46). Scattering intensity also correlates with lattice spacing (R2=0.81), suggestive of lower noise in our structural measurement relative to the functional measurement. Notably, we observe decreased myofilament ordering in tissues with a myofilament mutation known to lead to hypertrophic cardiomyopathy (HCM). Our results highlight the progress of human cardiac tissue engineering and enable unprecedented study of structural maturation in hiPSC-CMs., Comment: 12 pages, 6 figures, supplementary material available upon request to the lead author

In this article, we present a nano-electromechanical system (NEMS) designed to detect changes in the Casimir Energy. The Casimir effect is a result of the appearance of quantum fluctuations in the electromagnetic vacuum. Previous experiments have used nano- or micro- scale parallel plate capacitors to detect the Casimir force by measuring the small attractive force these fluctuations exert between the two surfaces. In this new set of experiments, we aim to directly detect shifts in the Casimir $\textit{energy}$ in the vacuum due to the presence of metallic parallel plates, one of which is a superconductor. A change in the Casimir energy of this configuration is predicted to shift the superconducting transition temperature (T$_\textrm{c}$) because of an interaction between it and the superconducting condensation energy. The experiment we discuss consists of taking a superconducting film, carefully measuring its transition temperature, bringing a conducting plate close to the film, creating a Casimir cavity, and then measuring the transition temperature again. The expected shifts will be small, comparable to the normal shifts one sees in cycling superconducting films to cryogenic temperatures and so using a NEMS resonator and doing this in situ is the only practical way to obtain accurate, reproducible data. Using a thin Pb film and opposing Au surface, we observe no shift in T$_\textrm{c}$ greater than 12 $\mu$K down to a minimum spacing of approximately 70 nm.

Magnetic sensing is present in our everyday interactions with consumer electronics, and also demonstrates potential for measurement of extremely weak biomagnetic fields, such as those of the heart and brain. In this work, we leverage the many benefits of the micro-electromechanical systems (MEMS) devices to fabricate a small, low power, inexpensive sensor whose resolution is in the range of weak biomagnetic fields. The sensor works at room temperature, and is suitable for consumer electronics integration. At present, such biomagnetic fields can only be measured by expensive mechanisms such as optical pumping and superconducting quantum interference devices (SQUIDs). Thus, our sensor suggests the opening of a large phase space for medical and consumer applications. The prototype fabrication is achieved by assembling micro-objects, including a permanent micromagnet, onto a post-release commercial MEMS accelerometer. With this system, we demonstrate a room temperature MEMS magnetometer, whose design is only sensitive to gradient magnetic fields and is generally insensitive to the Earth's uniform field. In air, the sensor's response is linear with a resolution of 1.1 nT cm-1 and spans over 3 decades of dynamic range to 4.6 {\mu}T cm-1. In 1 mTorr vacuum with 20 dB magnetic shielding, the sensor achieved 100 pT cm-1 resolution at resonance. The theoretical floor of this design is 110 fT cm-1 Hz-1/2 with a resolution of 13 fT cm-1, thus these devices hold promise for both magnetocardiography (MCG) and magnetoencephalography (MEG) applications.

We present electrothermal microelectromechanical (MEMS) actuators as a practical platform for straining 2D materials. The advantages of the electrothermal actuator is its high output force and displacement for low input voltage, but its drawback is that it is actuated by generating high amounts of heat. It is crucial to mitigate the high temperatures generated during actuation for reliable 2D material strain device implementation. Here, we implement a chevron actuator design that incorporates a thermal isolation stage in order to avoid heating the 2D material from the high temperatures generated during the actuation. By comparing experiment and simulation, we ensure our design does not compromise output displacement, while keeping the 2D material strain device stage cool. We also provide a simple analytical model useful for quickly evaluating different thermal isolation stage designs.

The Casimir Effect is a physical manifestation of quantum fluctuations of the electromagnetic vacuum. When two metal plates are placed closely together, typically much less than a micron, the long wavelength modes between them are frozen out, giving rise to a net attractive force between the plates, scaling as d^-4 (or d^-3 for a spherical-planar geometry) even when they are not electrically charged. In this paper we observe the Casimir Effect in ambient conditions using a modified capacitive MEMS accelerometer. Using a feedback assisted pick-and-place assembly process we are able to attach various micro-structures onto the post-release MEMS, converting it from an inertial force sensor to a direct force measurement platform with pN resolution. With this system we are able to directly measure the Casimir force between a silver-coated microsphere and gold-coated silicon plate. This device is a step towards leveraging the Casimir Effect for cheap, sensitive, room temperature quantum metrology.

Software defined radios (SDR) in the microwave X and K bands offer the promise of low cost, programmable operation with real-time frequency agility. However, the real world in which such radios operate requires them to be able to detect nanowatt signals in the vicinity of 100 kW transmitters. This imposes the need for selective RF filters on the front end of the receiver to block the large, out of band RF signals so that the finite dynamic range of the SDR is not overwhelmed and the desired nanowatt signals can be detected and digitally processed. This is currently typically done with a number of narrow band filters that are switched in and out under program control. What is needed is a small, fast, wide tuning range, high Q, low loss filter that can continuously tune over large regions of the microwave spectrum. In this paper we show how extreme throw MEMS actuators can be used to build such filters operating up to 15 GHz and beyond. The key enabling attribute of our MEMS actuators is that they have large, controllable, out-of-plane actuation ranges of a millimeter or more. In a capacitance-post loaded cavity filter geometry, this gives sufficient precisely controllable motion to produce widely tunable devices in the 4-15 GHz regime., Comment: 12 pages 14 figures 2 tables

We report on a modified transfer technique for atomically thin materials integrated onto microelectromechanical systems (MEMS) for studying strain physics and creating strain-based devices. Our method tolerates the non-planar structures and fragility of MEMS, while still providing precise positioning and crack free transfer of flakes. Further, our method used the transfer polymer to anchor the 2D crystal to the MEMS, which reduces the fabrication time, increases the yield, and allowed us to exploit the strong mechanical coupling between 2D crystal and polymer to strain the atomically thin system. We successfully strained single atomic layers of molybdenum disulfide (MoS$_2$) with MEMS devices for the first time and achieved greater than 1.3\% strain, marking a major milestone for incorporating 2D materials with MEMS We used the established strain response of MoS$_2$ Raman and Photoluminescence spectra to deduce the strain in our crystals and provide a consistency check. We found good comparison between our experiment and literature., Comment: 23 pages (includes supplementary), 7 figures, 6 tables

Breast cancer is the most prevalent cancer type in women, and while its survival rate is generally high the aesthetic outcome is an increasingly important factor when evaluating different treatment alternatives. 3D scanning and reconstruction techniques offer a flexible tool for building detailed and accurate 3D breast models that can be used both pre-operatively for surgical planning and post-operatively for aesthetic evaluation. This paper aims at comparing the accuracy of low-cost 3D scanning technologies with the significantly more expensive state-of-the-art 3D commercial scanners in the context of breast 3D reconstruction. We present results from 28 synthetic and clinical RGBD sequences, including 12 unique patients and an anthropomorphic phantom demonstrating the applicability of low-cost RGBD sensors to real clinical cases. Body deformation and homogeneous skin texture pose challenges to the studied reconstruction systems. Although these should be addressed appropriately if higher model quality is warranted, we observe that low-cost sensors are able to obtain valuable reconstructions comparable to the state-of-the-art within an error margin of 3 mm., Comment: This paper has been accepted to MICCAI2017

SN 2016gkg is a nearby Type IIb supernova discovered shortly after explosion. Like several other Type IIb events with early-time data, SN 2016gkg displays a double-peaked light curve, with the first peak associated with the cooling of a low-mass extended progenitor envelope. We present unprecedented intranight-cadence multi-band photometric coverage of the first light-curve peak of SN 2016gkg obtained from the Las Cumbres Observatory Global Telescope network, the Asteroid Terrestrial-impact Last Alert System, the Swift satellite and various amateur-operated telescopes. Fitting these data to analytical shock-cooling models gives a progenitor radius of ~25-140 solar radii with ~2-30 x 10^-2 solar masses of material in the extended envelope (depending on the model and the assumed host-galaxy extinction). Our radius estimates are broadly consistent with values derived independently (in other works) from HST imaging of the progenitor star. However, the shock-cooling model radii are on the lower end of the values indicated by pre-explosion imaging. Hydrodynamical simulations could refine the progenitor parameters deduced from the shock-cooling emission and test the analytical models., Comment: Accepted by ApJL

Micro/Nano Electro Mechanical Systems (MEMS/NEMS) provide the engineer with a powerful set of solutions to a wide variety of technical challenges. However, because they are mechanical systems, response times can be a limitation. In some situations, advanced engineered drive techniques can improve response times by as much as a thousand, significantly opening up the application space for MEMS/NEMS solutions., Comment: 37 pages, 20 figures

The 'Building Resilience in the Arid and Semi-Arid Lands of Northern Kenya' project was implemented in Turkana County, in Northern Kenya, between July 2012 and April 2015. The project was designed to build the resilience of project participants to a number of shocks and stresses: droughts – which threaten the area annually – floods and outbreaks of human and animal diseases on the one hand, and anthropocentric risks on the other hand, such as fire, livestock theft, and conflicts. The project worked at different levels to try and reduce households’ vulnerability to these risks, through Community-Managed Disaster Risk Reduction (CMDRR) and integration of community-level plans and committees into the work of the county government. This Effectiveness Review used a quasi-experimental evaluation design to assess the impact of the project activities, at the household- and community-level. The results provide evidence that the project had had a positive impact on households’ resilience capacities. This report is part of Oxfam's Effectiveness Review series.

Percolation diffusion into long (11.5 cm) self-assembled, ordered mesoporous microfibres is studied using optical transmission and laser ablation inductive coupled mass spectrometry (LA-ICP-MS). Optical transmission based diffusion studies reveal rapid penetration (< 5 s, D > 80 um2.s-1) of Rhodamine B with very little percolation of larger molecules such as zinc tetraphenylporphyrin (ZnTPP) observed under similar loading conditions. The failure of ZnTPP to enter the microfibre was confirmed, in higher resolution, using LA-ICP-MS. In the latter case, LA-ICP-MS was used to determine the diffusion of zinc acetate dihydrate, D ~ 3 x 10-4 nm2.s-1. The large differences between the molecules are accounted for by proposing ordered solvent and structure assisted accelerated diffusion of the Rhodamine B based on its hydrophilicity relative to the zinc compounds. The broader implications and applications for filtration, molecular sieves and a range of devices and uses are described., Comment: 18 pages, 6 figures, Accepted in Nanomaterials, Special Issue on Mesoporous Materials

We present a micro-electromechanical system (MEMS) based method for the resist free patterning of nano-structures. Using a focused ion beam (FIB) to customize larger MEMS machines, we fabricate apertures as small as 50 nm on plates that can be moved with nanometer precision over an area greater than 20x20 {\mu}m^2. Depositing thermally evaporated gold atoms though the apertures while moving the plate results in the deposition of nanoscale metal patterns. Adding a shutter only microns above the aperture, enables high speed control of not only where but also when atoms are deposited. Using a shutter, different sized apertures can be selectively opened and closed for nano-structure fabrication with features ranging from nano- to micrometers in scale. The ability to evaporate materials with high precision, and thereby fabricate circuits and structures in situ, enables new kinds of experiments based on the interactions of a small number of atoms and eventually even single atoms., Comment: 29 pages, 16 figure

We have inspected all supernova discoveries reported during 2010 and 2011 (538 and 926 events, respectively). We examine the statistics of all discovered objects, as well as those of the subset of spectroscopically-confirmed events. In these two years we see the rise of wide-field non-targeted supernova surveys to prominence, with the largest numbers of events reported by the CRTS and PTF surveys (572 and 393 events in total respectively, contributing together 74% of all reported discoveries in 2011), followed by the integrated contribution of numerous amateurs (184 events). Among spectroscopically-confirmed events the PTF (393 events) leads, followed by CRTS (170 events), and amateur discoveries (144 events). Traditional galaxy-targeted surveys, such as LOSS and CHASE, maintain a strong contribution (86 and 61 events, respectively) with high spectroscopic completeness (~90% per cent). It is interesting to note that the community managed to provide substantial spectroscopic follow-up for relatively brighter amateur discoveries (=16.5 mag), but significant less help for fainter (and much more numerous) events promptly released by the CRTS (=18.6 mag). Inspecting discovery magnitude and redshift distributions we find that PS1 discoveries have similar properties (=21.6 mag, =0.23) to events found in previous seasons by cosmology-oriented projects (e.g., SDSS-II), while PTF (=19.2 mag, =0.095) and CRTS (=18.6 mag, =0.049) populate the relatively unexplored phase space of faint SNe (>19 mag) in nearby galaxies (mainly PTF), and events at 0.05

This evaluation is presented as part of the Effectiveness Review Series 2014/15, selected for review under the resilience thematic area. The report documents the findings of a quasi-experimental evaluation carried out in December 2014 that sought to assess the impact of the climate change adaptation among small scale producers project., The project was carried about by Oxfam in partnership with the Centro para la Promoción, la Investigación y el Desarrollo Rural y Social (CIPRES) in the department of Chinandega between January 2011 and October 2013. This project aimed to improve small producers’ understanding of and ability to adapt to climate change, especially by providing training and inputs to improve seed selection, grain storage and livestock management, and to encourage protection of the local environment. In its later stages, the project also helped direct participants share their learning with other cooperative members and their neighbours., For more information, the data for this effectiveness review is available through the UK Data Service. Read more about the Oxfam Effectiveness Reviews.

This evaluation is presented as part of the Effectiveness Review Series 2013/14, selected for review under the livelihoods thematic area. This report documents the findings of a quasi-experimental evaluation carried out in November 2013 that sought to assess the impact of the activities of the Food Security and Livelihood Programme in Zimbabwe. The project’s overall objective was to contribute to the eradication of extreme poverty and hunger amongst the poor and vulnerable in Midlands and Masvingo provinces. It aimed to do this by enhancing livelihood options for households from selected communities in 15 wards across three districts in these provinces. The project aimed to directly benefit up to 24,500 people across the three target districts through three key interventions: summer agricultural inputs together with conservation agriculture training; small livestock support; and development of communal market garden linkages. The project activities were implemented from 2010 to 2014 by Oxfam in conjunction with two local partner organisations – Batanai HIV & AIDS Service Organisation (BHASO) and Midlands Aids Caring Organisation (MACO). Read more about the Oxfam Effectiveness Reviews.

This evaluation is presented as part of the Effectiveness Review Series 2013/14, selected for review under the resilience thematic area. This report documents the findings of a quasi-experimental evaluation carried out in September 2013 that sought to assess the impact of the activities of the ‘Mainstreaming disaster risk reduction and enhancing response capability’ project in Nepal., The project’s overall objective is to increase resilience and reduce vulnerability in local communities and institutions through support to strategies that enable them to better prepare for, mitigate and respond to natural disasters. The community-level activities carried out included the formation of community disaster-management committees, small-scale disaster mitigation activities, community training on hazards, first-aid and search and rescue, and the establishment of a flood early-warning system. These project activities were implemented in 10 communities, located in Alital and Jogbudha village development committee (VDC) areas in western Nepal. The communities are spread across three river basins – the Rangun, Puntara and Sadani – and are particularly vulnerable to flash flooding. The project was implemented between 2010 and 2013 with Oxfam in partnership with Integrated Development Society (IDeS), a local organisation., For more information, the data for this effectiveness review is available through the UK Data Service. Read more about the Oxfam Effectiveness Reviews.

The ‘Community-Led Disaster Risk Reduction’ project aims to increase resilience to climatic shocks among target groups in Mongu district in the Zambezi floodplain of western Zambia, through: Strengthening capacity of target communities to manage and respond to floods and droughts; and By encouraging livelihood diversification and asset growth., These full and summary reports document the findings of a quasi-experimental impact evaluation carried out in January 2013 in six communities located .