Search

Our estimates show that ‘proven reserves’ of fossil fuels in 2022, would generate an estimated 4777 Gt of CO2after allowing for non-fuel uses. This quantity already could ‘bust CO2budgets’ for IPCC RCP2.6, RCP4.5, and RCP6.0 and is approaching the range for RCP8.5. Notwithstanding these results, fossil fuel companies are still exploring and bringing new reserves onstream. We discuss the reasons behind this, and propose some policy options for governments as they address this situation.

Hydrogels are attractive materials for tissue engineering, but efforts to date have shown limited ability to produce the microstructural features necessary to promote cellular self-organization into hierarchical three-dimensional (3D) organ models. Here we develop a hydrogel ink containing prefabricated gelatin fibres to print 3D organ-level scaffolds that recapitulate the intra- and intercellular organization of the heart. The addition of prefabricated gelatin fibres to hydrogels enables the tailoring of the ink rheology, allowing for a controlled sol–gel transition to achieve precise printing of free-standing 3D structures without additional supporting materials. Shear-induced alignment of fibres during ink extrusion provides microscale geometric cues that promote the self-organization of cultured human cardiomyocytes into anisotropic muscular tissues in vitro. The resulting 3D-printed ventricle in vitro model exhibited biomimetic anisotropic electrophysiological and contractile properties.

Pediatric heart valve disease affects children worldwide and necessitates valve replacements that remodel and grow with the patient. Current valve manufacturing technologies struggle to create valves that facilitate native tissue remodeling for permanent replacements. Here, we present focused rotary jet spinning (FRJS) for implantable medical devices, such as heart valves, to address this challenge. Combining RJS and a focused air stream, FRJS prints FibraValves, micro- and nanofibrous heart valves, in minutes. The micro- and nanoscale features provide structural cues to orient cells at the biotic-abiotic interface, while the centimeter-scale valve shape regulates cardiac flow. We built valves using poly(L-lactide-co-Ɛ-caprolactone) fiber scaffolds, which supported rapid cellular infiltration and displayed native valve-like mechanical properties. Evaluating clinical translatability, we assessed acute performance in a large animal model using a transcatheter delivery approach. These tests indicate that FRJS is a viable method for manufacturing heart valves and future medical implants.

The majority of people in the world lack basic access to breast diagnostic imaging resulting in delay to diagnosis of breast cancer. In this study, we tested a volume sweep imaging (VSI) ultrasound protocol for evaluation of palpable breast lumps that can be performed by operators after minimal training without prior ultrasound experience as a means to increase accessibility to breast ultrasound. Medical students without prior ultrasound experience were trained for less than 2 hours on the VSI breast ultrasound protocol. Patients presenting with palpable breast lumps for standard of care ultrasound examination were scanned by a trained medical student with the VSI protocol using a Butterfly iQ handheld ultrasound probe. Video clips of the VSI scan imaging were later interpreted by an attending breast imager. Results of VSI scan interpretation were compared to the same‐day standard of care ultrasound examination. Medical students scanned 170 palpable lumps with the VSI protocol. There was 97% sensitivity and 100% specificity for a breast mass on VSI corresponding to 97.6% agreement with standard of care (Cohen's κ= 0.95, P< .0001). There was a detection rate of 100% for all cancer presenting as a sonographic mass. High agreement for mass characteristics between VSI and standard of care was observed, including 87% agreement on Breast Imaging‐Reporting and Data System assessments (Cohen's κ= 0.82, P< .0001). Breast ultrasound VSI for palpable lumps offers a promising means to increase access to diagnostic imaging in underserved areas. This approach could decrease delay to diagnosis for breast cancer, potentially improving morbidity and mortality.

Background: The timing of behavior and habitat use of nocturnal animals can be influenced by the lunar cycle in nature. The prevalence of artificial light at night (ALAN) has been recognized as a source of environmental pollution. The interaction between ALAN and the lunar cycle on bat behavior is important for understanding anthropogenic effects on bats. We utilized a decade (2012–2022) of acoustic monitoring data collected in North Carolina, United States, to investigate the relationship between bat activity, lunar cycle, and light pollution. We examined whether the amount of lunar illumination affected species-specific nightly activity and whether hourly bat activity patterns varied between nights with different moon phases. We further investigated if the relationship between bat activity and the lunar cycle might be altered by light pollution. Results: We found that seven bat species showed activity variation across nights in relation to the amount of moon illumination when ALAN was absent. In general, bats were less active on full moon nights compared to new moon nights. Light pollution interacted with the bat–lunar relationship in five of the seven species, masking the effect of the lunar cycle. We identified delayed bat activity patterns on nights with a full or waxing moon in seven species, and light pollution altered that pattern in four species. Overall, ALAN was associated with decreased bat activity independent of lunar cycle effects. Conclusions: Our study demonstrated that at a broad spatial scale, ALAN negatively affected many North American temperate bat species and altered their lunar chronobiology. As light pollution is spreading to historically dark areas and habitats, ALAN might couple with other threats, such as the white-nose syndrome or climate change, to cause cascading damage in the environment that depends on ecosystem services such as pest control provided by bats. We argue that further research and conservation actions are needed to mitigate the impact of light pollution.

Speckle statistics in ultrasound and optical coherence tomography have been studied using various distributions, including the Rayleigh, the K, and the more recently proposed Burr distribution. In this paper, we expand on the utility of the Burr distribution by first validating its theoretical framework with numerical simulations and then introducing a new local estimator to characterize sample tissues of liver, brain, and skin using optical coherence tomography. The spatially local estimates of the Burr distribution’s power-law or exponent parameter enable a new type of parametric image. The simulation and experimental results confirm the potential for various applications of the Burr distribution in both basic science and clinical realms.

We study the performance of an artificial intelligence (AI) program designed to assist radiologists in the diagnosis of breast cancer, relative to measures obtained from conventional readings by radiologists. A total of 10 radiologists read a curated, anonymized group of 299 breast ultrasound images that contained at least one suspicious lesion and for which a final diagnosis was independently determined. Separately, the AI program was initialized by a lead radiologist and the computed results compared against those of the radiologists. The AI program's diagnoses of breast lesions had concordance with the 10 radiologists' readings across a number of BI‐RADS descriptors. The sensitivity, specificity, and accuracy of the AI program's diagnosis of benign versus malignant was above 0.8, in agreement with the highest performing radiologists and commensurate with recent studies. The trained AI program can contribute to accuracy of breast cancer diagnoses with ultrasound. Access the CME test hereand search by article title.

Gas-phase cationic ternary complexes of group 10 metals of the formula [(phen)M(X)]+, where phen = 1,10-phenanthroline (M = Ni, Pd, or Pt; and X = H or CH3), react with cyclohexane via C–H activation, forming the respective cyclohexyl species [(phen)M(c-C6H11)]+. Upon collisional activation, these species undergo two key competing processes: (i) ring opening followed by “cracking” of the hydrocarbon chain leading to extrusion of propylene and ethylene as major products among other hydrocarbons; and (ii) dehydrogenation of the cyclohexyl ring leading to the loss of one, two, or three hydrogen molecules, with subsequent loss of cyclohexenes or benzene. The relative prevalence of these two pathways strongly depends on the metal ion, with Pt preferring dehydrogenation over ring opening. The multiple catalytic cycles operating within both pathways are described. Density functional theory (DFT) calculations are used to shed light on mechanistic aspects associated with the experimental results.

The speckle statistics of optical coherence tomography images of biological tissue have been studied using several historical probability density functions. Here, we propose a new theoretical framework based on power-law functions, where we hypothesize that an underlying power-law distribution governs scattering from tissues. Thus, multi-scale scattering sites including the fractal branching vasculature will contribute to power-law probability distributions of speckle statistics. Specifically, these are the Burr type XII distribution for speckle amplitude, the Lomax distribution for intensity, and the generalized logistic distribution for log amplitude. Experimentally, these three distributions are fitted to histogram data from nine optical coherence tomography scans of various samples and biological tissues, in vivo and ex vivo. The distributions are also compared with classical models such as the Rayleigh, K, and gamma distributions. The results indicate that across OCT datasets of various tissue types, the proposed power-law distributions are more appropriate models yielding novel parameters for characterizing the physics of scattering from biological tissue. Thus, the overall framework brings to the field new biomarkers from OCT measures of speckle in tissues, grounded in basic biophysics and with wide applications to diagnostic imaging in clinical use.

The ternary Pd complexes [(phen)Pd(H)]+(1-Pd) and [(phen)Pd(CH3)]+(5-Pd) (where phen = 1,10-phenanthroline) both react with hexane in a linear ion trap mass spectrometer, forming the C–H activation product [(phen)Pd(C6H11)]+(3-Pd) and releasing H2and CH4, respectively. Density functional theory (DFT) calculations agree well with the experiments in predicting low barriers for these reactions proceeding via a metathesis mechanism. Species 3-Pdundergoes extensive fragmentation, or “cracking”, of the hydrocarbon chain when sufficient energy is supplied via collision-induced dissociation (CID), resulting in the extrusion of a mixture of alkenes, methane, and hydrogen. DFT calculations show that Pd “chain-walking” from α (terminal carbon) to β and from β to γ positions can proceed with barriers sufficiently below those required for chain “cracking”. The fragmentation reactions can be made catalytic if 1-Pdand 5-Pdproduced by CID of 3-Pdare allowed to react with hexane again. Ni complexes largely mirrored the chemistry observed for Pd. Both 1-Niand 5-Nireacted with hexane, forming 3-Ni, which fragmented under CID conditions in a fashion similar to 3-Pd. In contrast, only 5-Ptreacted with hexane to form 3-Pt, which fragmented predominantly via sequential losses of H2.

Valvular heart disease is a major cause of morbidity and mortality worldwide. Surgical valve repair or replacement has been the standard of care for patients with valvular heart disease for many decades, but transcatheter heart valve therapy has revolutionized the field in the past 15 years. However, despite the tremendous technical evolution of transcatheter heart valves, to date, the clinically available heart valve prostheses for surgical and transcatheter replacement have considerable limitations. The design of next-generation tissue-engineered heart valves (TEHVs) with repair, remodelling and regenerative capacity can address these limitations, and TEHVs could become a promising therapeutic alternative for patients with valvular disease. In this Review, we present a comprehensive overview of current clinically adopted heart valve replacement options, with a focus on transcatheter prostheses. We discuss the various concepts of heart valve tissue engineering underlying the design of next-generation TEHVs, focusing on off-the-shelf technologies. We also summarize the latest preclinical and clinical evidence for the use of these TEHVs and describe the current scientific, regulatory and clinical challenges associated with the safe and broad clinical translation of this technology.

Shape-memory polymeric materials lack long-range molecular order that enables more controlled and efficient actuation mechanisms. Here, we develop a hierarchical structured keratin-based system that has long-range molecular order and shape-memory properties in response to hydration. We explore the metastable reconfiguration of the keratin secondary structure, the transition from a-helix to ß-sheet, as an actuation mechanism to design a high-strength shape-memory material that is biocompatible and processable through fibre spinning and three-dimensional (3D) printing. We extract keratin protofibrils from animal hair and subject them to shear stress to induce their self-organization into a nematic phase, which recapitulates the native hierarchical organization of the protein. This self-assembly process can be tuned to create materials with desired anisotropic structuring and responsiveness. Our combination of bottom-up assembly and top-down manufacturing allows for the scalable fabrication of strong and hierarchically structured shape-memory fibres and 3D-printed scaffolds with potential applications in bioengineering and smart textiles.

Low winter temperatures are a major driver of hibernation and migration in temperate North American bats. Hibernation and migration in turn affect bat mortality via white-nose syndrome and collisions with wind turbines. To describe winter bat acoustic activity across a wide temperature gradient and to understand species-specific responses to low temperatures, we recorded nightly acoustic activity of bats at 15 sites across the state of North Carolina, United States, from December through February 2016 – 2018. Bat acoustic activity was recorded at all sites during both winters. Nightly probability of bat acoustic presence regressed positively on ambient temperature. Nightly probability of presence in Lasionycteris noctivagans(silver-haired bat) and Eptesicus fuscus(big brown bat) regressed negatively on wind speed. The mean probability of presence within the same winter condition was highest for L. noctivagans, followed by E. fuscus, Perimyotis subflavus(tricolored bat), and Lasiurus cinereus(hoary bat). Differences in species’ mean body weight and roosting preference explained part of the variation of the species-specific probability of presence. Our results can be used to predict bat acoustic presence for these species across the southeastern United States in winter, and better understand the potential threats to bats such as white-nose syndrome and wind turbine interactions.

Acceptorless dehydrogenation of ethane was achieved in the gas phase via a two-step catalytic cycle involving ternary cationic metal hydrides, [(phen)M(H)]+, 1, and metal ethides, [(phen)M(CH2CH3)]+, 2, (where M = Ni, Pd, or Pt, and phen = 1,10-phenanthroline). Species 1and 2were generated and their reactivity studied in a quadrupole ion trap mass spectrometer. It was found that 1readily reacted with ethane releasing H2and forming 2, with the relative reactivity being Pt > Ni ≫ Pd. Density functional theory (DFT) calculations for this metathesis reaction agree with the experimental reactivity order. Species 2can in turn be converted into 1and release ethylene when sufficient energy is supplied via collision-induced dissociation. DFT calculations also provided insight into competing side reactions (e.g., dehydrogenation of 2and formation of protonated phen ligand) that become competitive during this endothermic step. The catalytic cycle can be repeated in the mass spectrometer several times. Multiple entry points into the cycle have been identified and discussed.

Personnel operating in extreme environments require equipment that protects against multiple hazards. Currently, protection against both thermal and ballistic threats requires the combination of multiple high-performance materials that increases equipment weight and complexity. Here, we hypothesized we could achieve simultaneous protection by manufacturing a porous network of aligned fibers, combining the mechanical properties of continuous fibers with the thermal properties of porous aerogels. Choosing para-aramid polymers as the building block, we engineered precursor solutions to be fluid-like during fiber spinning and solid-like during fiber formation. This allowed for the fabrication of porous, continuous para-aramid fiber sheets (pAFS) with fiber diameters an order of magnitude lower than that of commercial para-aramid fibers. Although exhibiting moderately reduced single-fiber mechanics, these pAFS had fragment projectile resistance comparable with commercial para-aramids, while providing 20-fols heat-insulation capability. With these synergistic properties, the nanofiber sheets act as a multifunctional material that can provide improved simultaneous protection.

Kevin “Kit” Parker believes there is benefit in soldier-driven innovation on the battlefield and in the general populace. Here, he recounts how his military experience, along with other veterans, can make their way into science and bring their unique expertise into the lab.

The multiscale organization of protein-based fibrillar materials is a hallmark of many organs, but the recapitulation of hierarchal structures down to fibrillar scales, which is a requirement for withstanding physiological loading forces, has been challenging. We present a microfluidic strategy for the continuous, large-scale formation of strong, handleable, free-standing, multicentimeter-wide collagen sheets of unprecedented thinness through the application of hydrodynamic focusing with the simultaneous imposition of strain. Sheets as thin as 1.9 μm displayed tensile strengths of 0.5–2.7 MPa, Young’s moduli of 3–36 MPa, and modulated the diffusion of molecules as a function of collagen nanoscale structure. Smooth muscle cells cultured on engineered sheets oriented in the direction of aligned collagen fibrils and generated coordinated vasomotor responses. The described biofabrication approach enables rapid formation of ultrathin collagen sheets that withstand physiologically relevant loads for applications in tissue engineering and regenerative medicine, as well as in organ-on-chip and biohybrid devices.

After 100 years of theoretical treatment of speckle patterns from coherent illumination, there remain some open questions about the nature of ultrasound speckle from soft vascularized tissues. A recent hypothesis is that the fractal branching vasculature is responsible for the dominant echo pattern from organs such as the liver. In that case, an analysis of cylindrical scattering structures arranged across a power law distribution of sizes is warranted. Using a simple model of echo strength and basic transformation rules from probability, we derive the first order statistics of speckle considering the amplitude, the intensity, and the natural log of amplitude. The results are given by long tailed distributions that have been studied in the statistics literature for other fields. Examples are given from simulations and animal studies, and the theoretical fit to these preliminary data support the overall framework as a plausible model for characterizing ultrasound speckle statistics.

Supplemental Digital Content is available in the text.

Subcellular localization is essential to RNA biogenesis, processing, and function across the gene expression life cycle. However, the specific nucleotide sequence motifs that direct RNA localization are incompletely understood. Fortunately, new sequencing technologies have provided transcriptome-wide atlases of RNA localization, creating an opportunity to leverage computational modeling. Here we present RNA-GPS, a new machine learning model that uses nucleotide-level features to predict RNA localization across eight different subcellular locations—the first to provide such a wide range of predictions. RNA-GPS's design enables high-throughput sequence ablation and feature importance analyses to probe the sequence motifs that drive localization prediction. We find localization informative motifs to be concentrated on 3′-UTRs and scattered along the coding sequence, and motifs related to splicing to be important drivers of predicted localization, even for cytotopic distinctions for membraneless bodies within the nucleus or for organelles within the cytoplasm. Overall, our results suggest transcript splicing is one of many elements influencing RNA subcellular localization.

Recent reports suggest the utility of extracellular matrix (ECM) molecules as raw components in scaffolding of engineered materials. However, rapid and tunable manufacturing of ECM molecules into fibrous structures remains poorly developed. Here we report on an immersion rotary jet-spinning (iRJS) method to show high-throughput manufacturing (up to ∼1 g/min) of hyaluronic acid (HA) and other ECM fiber scaffolds using different spinning conditions and postprocessing modifications. This system allowed control over a variety of scaffold material properties, which enabled the fabrication of highly porous (70–95%) and water-absorbent (swelling ratio ∼2000–6000%) HA scaffolds with soft-tissue mimetic mechanical properties (∼0.5–1.5 kPa). Tuning these scaffolds’ properties enabled the identification of porosity (∼95%) as a key facilitator for rapid and in-depth cellular ingress in vitro. We then demonstrated that porous HA scaffolds accelerated granulation tissue formation, neovascularization, and reepithelialization in vivo, altogether potentiating faster wound closure and tissue repair. Collectively, this scalable and versatile manufacturing approach enabled the fabrication of tunable ECM-mimetic nanofiber scaffolds that may provide an ideal first building block for the design of all-in-one healing materials.

Detailed data on juvenile survival are rare in the literature. Although many studies estimate recruitment, if you cannot distinguish between permanent dispersal and mortality, the management implications for a population may be unclear. We estimated juvenile survival in a reintroduced North Island robin (Petroica longipes) population in a protected sanctuary surrounded by an unprotected landscape where the species is extirpated. The population has had marginal population growth due to poor recruitment so we modeled 3 types of data (resighting of fledglings, radio‐telemetry of independent juveniles, resighting of adults) in an integrated framework to determine the life stages where high mortality was occurring, and to distinguish mortality from dispersal. Approximately 16% of birds that fledged (n= 109) were present at the start of the next breeding season, consistent with recruitment rates from previous years. Low survival in the first 6 weeks after fledging was the primary cause of poor recruitment. Only 50% survived to independence (4 weeks after fledging), and 18% survived to the end of the radio‐tracking period (14 weeks), after which juvenile survival matched adult survival. No dispersal from the sanctuary occurred during the radio‐tracking period. Juveniles moved between adjacent forest fragments within the sanctuary, but did not leave the sanctuary. This information, which demonstrates the importance of distinguishing between natal mortality and dispersal, is important for ongoing management of the site and selection of future reintroduction sites for this species. © 2019 The Wildlife Society. Analysis of survival of movements of juvenile North Island robins at Tāwharanui Regional Park, New Zealand, showed that low recruitment in this reintroduced population was due to high mortality soon after fledging rather than dispersal from the park. These results indicate that recruitment would not be improved by reducing connectivity, and that there is no need to avoid reintroductions to other sites with similar levels of connectivity to the surrounding landscape.

Engineering bioscaffolds for improved cutaneous tissue regeneration remains a healthcare challenge because of the increasing number of patients suffering from acute and chronic wounds. To help address this problem, we propose to utilize alfalfa, an ancient medicinal plant that contains antibacterial/oxygenating chlorophylls and bioactive phytoestrogens, as a building block for regenerative wound dressings. Alfalfa carries genistein, which is a major phytoestrogen known to accelerate skin repair. The scaffolds presented herein were built from composite alfalfa and polycaprolactone (PCL) nanofibers with hydrophilic surface and mechanical stiffness that recapitulate the physiological microenvironments of skin. This composite scaffold was engineered to have aligned nanofibrous architecture to accelerate directional cell migration. As a result, alfalfa-based composite nanofibers were found to enhance the cellular proliferation of dermal fibroblasts and epidermal keratinocytes in vitro. Finally, these nanofibers exhibited reproducible regenerative functionality by promoting re-epithelialization and granulation tissue formation in both mouse and human skin, without requiring additional proteins, growth factors, or cells. Overall, these findings demonstrate the potential of alfalfa-based nanofibers as a regenerative platform toward accelerating cutaneous tissue repair.

Supplemental Digital Content is available in the text.

In dynamic optical coherence elastography (OCE), surface acoustic waves are the predominant perturbations. They constrain the quantification of elastic modulus to the direction of wave propagation only along the surface of tissues, and disregard elasticity gradients along depth. Longitudinal shear waves (LSW), on the other hand, can be generated at the surface of the tissue and propagate through depth with desirable properties for OCE: (1) LSW travel at the shear wave speed and can discriminate elasticity gradients along depth, and (2) the displacement of LSW is longitudinally polarized along the direction of propagation; therefore, it can be measured by a phase-sensitive optical coherence tomography system. In this study, we explore the capabilities of LSW generated by a circular glass plate in contact with a sample using numerical simulations and tissue-mimicking phantom experiments. Results demonstrate the potential of LSW in detecting an elasticity gradient along axial and lateral directions simultaneously. Finally, LSW are used for the elastography of ex vivo mouse brain and demonstrate important implications in in vivo and in situ measurements of local elasticity changes in brain and how they might correlate with the onset and progression of degenerative brain diseases.

Development of biomimetic and instructive materials is emerging as a promising approach for redirecting fibrotic wound healing into a regenerative process. In nature, complete tissue regeneration can transpire in certain organ substructures, during embryogenesis and, remarkably, in some organisms in which whole limbs can regrow. These regenerative phenomena were observed to possess specific extracellular matrices, as well as stem cell niches and regulatory signaling pathways, that likely act as spatiotemporal organizers of these preferred outcomes. Biomimetic materials are now improving on the limitations of existing wound care treatments because they are being designed to stimulate these spatiotemporal cues, thus supporting regeneration within host tissues. A variety of novel materials have already emerged and demonstrated promise both in preclinical studies and in patients. This review discusses the recent advances in understanding these biomimetic and instructive properties and their integration into wound care scaffolds.

H‐scan imaging is a new ultrasound technique used to visualize the relative size of acoustic scatterers. The purpose of this study was to evaluate the use of H‐scan ultrasound imaging for monitoring early tumor response to neoadjuvant treatment using a preclinical breast cancer animal model. Real‐time H‐scan ultrasound imaging was implemented on a programmable ultrasound scanner (Vantage 256; Verasonics Inc., Kirkland, WA) equipped with an L11‐4v transducer. Bioluminescence and H‐scan ultrasound was used to image luciferase‐positive breast cancer–bearing mice at baseline and at 24, 48, and 168 hours after administration of a single dose of neoadjuvant (paclitaxel) or sham treatment. Animals were euthanized at 48 or 168 hours, and tumors underwent histologic processing to identify cancer cell proliferation and apoptosis. Baseline H‐scan ultrasound images of control and therapy group tumors were comparable, but the latter exhibited significant changes over the 7‐day study (P< .05). At termination, there was a marked difference between the H‐scan ultrasound images of control and treated tumors (P< .05). Specifically, H‐scan ultrasound images of treated tumors were more blue in hue than images obtained from control tumors. There was a significant linear correlation between the predominance of the blue hue found in the H‐scan ultrasound images and intratumoral apoptotic activity (R2> 0.40, P< .04). Preliminary preclinical results suggest that H‐scan ultrasound imaging is a new and promising tissue characterization modality. H‐scan ultrasound imaging may provide prognostic value when monitoring early tumor response to neoadjuvant treatment.

Understanding the uptake and transport dynamics of engineered nanomaterials (ENMs) by mammalian cells is an important step in designing next-generation drug delivery systems. However, to track these materials and their cellular interactions, current studies often depend on surface-bound fluorescent labels, which have the potential to alter native cellular recognition events. As a result, there is still a need to develop methods capable of monitoring ENM-cell interactions independent of surface modification. Addressing these concerns, here we show how scatter enhanced phase contrast (SEPC) microscopy can be extended to work as a generalized label-free approach for monitoring nanoparticle uptake and transport dynamics. To determine which materials can be studied using SEPC, we turn to Lorenz–Mie theory, which predicts that individual particles down to ∼35 nm can be observed. We confirm this experimentally, demonstrating that SEPC works for a variety of metal and metal oxides, including Au, Ag, TiO2, CeO2, Al2O3, and Fe2O3nanoparticles. We then demonstrate that SEPC microscopy can be used in a quantitative, time-dependent fashion to discriminate between distinct modes of active cellular transport, including intracellular transport and membrane-assisted transport. Finally, we combine this technique with microcontact printing to normalize transport dynamics across multiple cells, allowing for a careful study of ensemble TiO2nanoparticle uptake. This revealed three distinct regions of particle transport across the cell, indicating that membrane dynamics play an important role in regulating particle flow. By avoiding fluorescent labels, SEPC allows for a rational exploration of the surface properties of nanomaterials in their native state and their role in endocytosis and cellular transport.

Complex deformation of a polymer jet appears in many manufacturing processes, such as 3D printing, electrospinning, blow spinning, and rotary jet spinning. In these applications, a polymer melt or solution is first extruded through an orifice and forms a jet. The polymer jet is then dynamically deformed until the polymer solidifies. The final product is strongly affected by the deformation of the polymer jet. And the deformation is strongly affected by the viscoelasticity of the polymer. Here we develop a beam theory to incorporate both the nonlinear viscoelasticity and the bending/twisting stiffness of a polymer jet. As a demonstration, we study the formation of a polymer fiber under strong centrifugal force, a fiber manufacturing process known as rotary jet spinning.

Across the varieties of waves that have been studied in physics, it is well established that group velocities can be significantly greater than or less than phase velocities measured within comparable frequency bands, depending on the particular mechanisms involved. The distinction between group and phase velocities is important in elastography, because diagnoses are made based on shear wave speed estimations from a variety of techniques. We review the general definitions of group and phase velocity and examine their specific relations within an important general class of rheological models. For the class of tissues and materials exhibiting power law dispersion, group velocity is significantly greater than phase velocity, and simple expressions are shown to interrelate the commonly measured parameters. Examples are given from phantoms and tissues.

T cells create vast amounts of diversity in the genes that encode their T cell receptors (TCRs), which enables individual clones to recognize specific peptide–major histocompatibility complex (MHC) ligands. Here we combined sequencing of the TCR-encoding genes with assay for transposase-accessible chromatin with sequencing (ATAC-seq) analysis at the single-cell level to provide information on the TCR specificity and epigenomic state of individual T cells. By using this approach, termed transcript-indexed ATAC-seq (T-ATAC-seq), we identified epigenomic signatures in immortalized leukemic T cells, primary human T cells from healthy volunteers and primary leukemic T cells from patient samples. In peripheral blood CD4+T cells from healthy individuals, we identified cis and trans regulators of naive and memory T cell states and found substantial heterogeneity in surface-marker-defined T cell populations. In patients with a leukemic form of cutaneous T cell lymphoma, T-ATAC-seq enabled identification of leukemic and nonleukemic regulatory pathways in T cells from the same individual by allowing separation of the signals that arose from the malignant clone from the background T cell noise. Thus, T-ATAC-seq is a new tool that enables analysis of epigenomic landscapes in clonal T cells and should be valuable for studies of T cell malignancy, immunity and immunotherapy.