Analytical Investigation of Replica-Molding-Enabled Nanopatterned Tribocharging Process on Soft-Material Surfaces.

Nanopatterned tribocharge can be generated on the surface of elastomers through their replica molding with nanotextured molds. Despite its vast application potential, the physical conditions enabling the phenomenon have not been clarified in the framework of analytical mechanics. Here, we explain the final tribocharge pattern by separately applying two models, namely cohesive zone failure and cumulative fracture energy, as a function of the mold nanotexture's aspect ratio. These models deepen our understanding of the triboelectrification phenomenon.

Pursuit of hidden rules behind the irregularity of nano capillary lithography by hybrid intelligence.

Nature finds a way to leverage nanotextures to achieve desired functions. Recent advances in nanotechnologies endow fascinating multi-functionalities to nanotextures by modulating the nanopixel's height. But nanoscale height control is a daunting task involving chemical and/or physical processes. As a facile, cost-effective, and potentially scalable remedy, the nanoscale capillary force lithography (CFL) receives notable attention. The key enabler is optical pre-modification of photopolymer's characteristics via ultraviolet (UV) exposure. Still, the underlying physics of the nanoscale CFL is not well understood, and unexplained phenomena such as the "forbidden gap" in the nano capillary rise (unreachable height) abound. Due to the lack of large data, small length scales, and the absence of first principles, direct adoptions of machine learning or analytical approaches have been difficult. This paper proposes a hybrid intelligence approach in which both artificial and human intelligence coherently work together to unravel the hidden rules with small data. Our results show promising performance in identifying transparent, physics-retained rules of air diffusivity, dynamic viscosity, and surface tension, which collectively appear to explain the forbidden gap in the nanoscale CFL. This paper promotes synergistic collaborations of humans and AI for advancing nanotechnology and beyond.

Curvature-Adjustable Polymeric Nanolens Fabrication Using UV-Controlled Nanoimprint Lithography.

Nanolenses are gaining importance in nanotechnology, but their challenging fabrication is thwarting their wider adoption. Of particular challenge is facile control of the lens' curvature. In this work, we demonstrate a new nanoimprinting technique capable of realizing polymeric nanolenses in which the nanolens' curvature is optically controlled by the ultraviolet (UV) dose at the pre-curing step. Our results reveal a regime in which the nanolens' height changes linearly with the UV dose. Computational modeling further uncovers that the polymer undergoes highly nonlinear dynamics during the UV-controlled nanoimprinting process. Both the technique and the process model will greatly advance nanoscale science and manufacturing technology.

CLAIRE-Parallelized Diffeomorphic Image Registration for Large-Scale Biomedical Imaging Applications.

We study the performance of CLAIRE-a diffeomorphic multi-node, multi-GPU image-registration algorithm and software-in large-scale biomedical imaging applications with billions of voxels. At such resolutions, most existing software packages for diffeomorphic image registration are prohibitively expensive. As a result, practitioners first significantly downsample the original images and then register them using existing tools. Our main contribution is an extensive analysis of the impact of downsampling on registration performance. We study this impact by comparing full-resolution registrations obtained with CLAIRE to lower resolution registrations for synthetic and real-world imaging datasets. Our results suggest that registration at full resolution can yield a superior registration quality-but not always. For example, downsampling a synthetic image from 10243 to 2563 decreases the Dice coefficient from 92% to 79%. However, the differences are less pronounced for noisy or low contrast high resolution images. CLAIRE allows us not only to register images of clinically relevant size in a few seconds but also to register images at unprecedented resolution in reasonable time. The highest resolution considered are CLARITY images of size 2816×3016×1162. To the best of our knowledge, this is the first study on image registration quality at such resolutions.

Significance of D-Dimer in Acute Ischemic Stroke Patients With Large Vessel Occlusion Accompanied by Active Cancer.

Background: This study aimed to investigate clinical outcome predictors of acute stroke patients with large vessel occlusion and active cancer and validate the significance of D-dimer levels for endovascular thrombectomy decisions. Methods: We analyzed a prospectively collected hospital-based stroke registry to determine clinical EVT outcomes of acute stroke patients within 24 h with following criteria: age ≥18 years, NIHSS ≥6, and internal carotid artery or middle cerebral artery lesion. All patients were classified into EVT and non-EVT groups. Patients were divided into two groups by initial D-dimer level. We explored variables potentially associated with successful recanalization as well as 3-month functional outcomes and mortality rates. Results: Among 68 patients, 36 were treated with EVT, with successful recanalization in 55.6%. The low D-dimer group showed a higher rate of successful recanalization and favorable outcome than the high D-dimer group. The mortality rate was higher in the high D-dimer group. No EVT and high D-dimer level were independent predictors of mortality, whereas lesion volume and low D-dimer level were independently associated with favorable outcomes. Conclusions: D-dimer level is a prognostic factor in acute LVO stroke patients with active cancer, and its high value for EVT decisions provisionally supports its testing in this patient population.

Aggresome assembly at the centrosome is driven by CP110-CEP97-CEP290 and centriolar satellites.

Protein degradation is critical to maintaining cellular homeostasis, and perturbation of the ubiquitin proteasome system leads to the accumulation of protein aggregates. These aggregates are either directed towards autophagy for destruction or sequestered into an inclusion, termed the aggresome, at the centrosome. Utilizing high-resolution quantitative analysis, here, we define aggresome assembly at the centrosome in human cells. Centriolar satellites are proteinaceous granules implicated in the trafficking of proteins to the centrosome. During aggresome assembly, satellites were required for the growth of the aggresomal structure from an initial ring of phosphorylated HSP27 deposited around the centrioles. The seeding of this phosphorylated HSP27 ring depended on the centrosomal proteins CP110, CEP97 and CEP290. Owing to limiting amounts of CP110, senescent cells, which are characterized by the accumulation of protein aggregates, were defective in aggresome formation. Furthermore, satellites and CP110-CEP97-CEP290 were required for the aggregation of mutant huntingtin. Together, these data reveal roles for CP110-CEP97-CEP290 and satellites in the control of cellular proteostasis and the aggregation of disease-relevant proteins.

Correlation between bispectral index and patient state index in children under sevoflurane anesthesia.

BACKGROUND: Because the unanticipated arousal or hemodynamic instability during anesthesia may adversely affect the physical and emotional welfare of children, adequate management of the anesthesia depth is required. We aimed to compare Bispectral Index (BIS) and Patient State Index (PSI) in children during sevoflurane anesthesia and evaluate PSI as depth of anesthesia monitor in children aged 6 months-12 years. METHODS: In this prospective observational study, children aged 6 months-12 years old scheduled for elective surgery under sevoflurane anesthesia were enrolled from November 2018 to June 2019. We monitored BIS and PSI at different sevoflurane concentrations. The primary outcome was the correlation between BIS and PSI. The correlation between BIS and PSI at different sevoflurane concentrations (at 1, 1.5, and 2 MACs) and at different age groups (6 months-2 years, 2-7 years, and 8-12 years) was also investigated. RESULTS: Bispectral index and PSI showed a fair correlation (r = .430; 95% confidence interval [CI], 0.297-0.546; p < .001). Two values were fairly correlated at 1, 1.5, and 2 MAC (r = .544; 95% CI, 0.314-0.716; p < .001, r = .509; 95% CI, 0.283-0.699; p < .001, and r = .315; 95% CI, 0.047-0.522; p = 0.007). BIS and PSI values showed a fair correlation in 6 months - 2 year and 8-12 year groups (r = .696; 95% CI, 0.519-0.813; p < .001 and r = .297; 95% CI, -0.017 to 0.543; p < .021), but there was not significant correlation in 2-7 years group (r = .190; 95% CI, -0.015 to 0.374; p = .052). CONCLUSIONS: There was a fair correlation between BIS and PSI in children under sevoflurane anesthesia. The use of BIS and PSI as an indicator for anesthesia depth by sevoflurane is not reliable in pediatric patients.

Mechano-Triboelectric Analysis of Surface Charge Generation on Replica-Molded Elastomeric Nanodomes.

Replica molding-based triboelectrification has emerged as a new and facile technique to generate nanopatterned tribocharge on elastomer surfaces. The "mechano-triboelectric charging model" has been developed to explain the mechanism of the charge formation and patterning process. However, this model has not been validated to cover the full variety of nanotexture shapes. Moreover, the experimental estimation of the tribocharge's surface density is still challenging due to the thick and insulating nature of the elastomeric substrate. In this work, we perform experiments in combination with numerical analysis to complete the mechano-triboelectrification charging model. By utilizing Kelvin probe force microscopy (KPFM) and finite element analysis, we reveal that the mechano-triboelectric charging model works for replica molding of both recessed and protruding nanotextures. In addition, by combining KPFM with numerical electrostatic modeling, we improve the accuracy of the surface charge density estimation and cross-calibrate the result against that of electrostatic force microscopy. Overall, the regions which underwent strong interfacial friction during the replica molding exhibited high surface potential and charge density, while those suffering from weak interfacial friction exhibited low values on both. These multi-physical approaches provide useful and important tools for comprehensive analysis of triboelectrification and generation of nanopatterned tribocharge. The results will widen our fundamental understanding of nanoscale triboelectricity and advance the nanopatterned charge generation process for future applications.

A multiplexed, next generation sequencing platform for high-throughput detection of SARS-CoV-2.

Population scale sweeps of viral pathogens, such as SARS-CoV-2, require high intensity testing for effective management. Here, we describe "Systematic Parallel Analysis of RNA coupled to Sequencing for Covid-19 screening" (C19-SPAR-Seq), a multiplexed, scalable, readily automated platform for SARS-CoV-2 detection that is capable of analyzing tens of thousands of patient samples in a single run. To address strict requirements for control of assay parameters and output demanded by clinical diagnostics, we employ a control-based Precision-Recall and Receiver Operator Characteristics (coPR) analysis to assign run-specific quality control metrics. C19-SPAR-Seq coupled to coPR on a trial cohort of several hundred patients performs with a specificity of 100% and sensitivity of 91% on samples with low viral loads, and a sensitivity of >95% on high viral loads associated with disease onset and peak transmissibility. This study establishes the feasibility of employing C19-SPAR-Seq for the large-scale monitoring of SARS-CoV-2 and other pathogens.

Grayscale Nanopixel Printing at Sub-10-nanometer Vertical Resolution via Light-Controlled Nanocapillarity.

Nanotextures play increasingly important roles in nanotechnology. Recent studies revealed that their functionalities can be further enhanced by spatially modulating the height of their nanoscale pixels. Realizing the concept, however, is very challenging as it requires "grayscale" printing of the nanopixels in which their height is controlled within a few nanometers as a micrometric function of position. This work demonstrates such a high vertical and lateral resolution grayscale printing of polymeric nanopixels. We realize the height modulation by exploiting the discovery that the capillary rise of certain photopolymers can be optically controlled to stop at a predetermined height with sub-10-nm accuracy. Microscale spatial patterning of the control light directly extends the height modulation into a two-dimensionally patterned, grayscale nanopixel printing. Its utility is verified through readily reconfigurable, maskless printing of grayscale nanopixel arrays in dielectric and metallo-dielectric forms. This work also reveals the highly nonlinear and unstable nature of the polymeric nanocapillary effect, expanding its understanding and application scope.

Direct interaction between CEP85 and STIL mediates PLK4-driven directed cell migration.

PLK4 has emerged as a prime target for cancer therapeutics, and its overexpression is frequently observed in various types of human cancer. Recent studies have further revealed an unexpected oncogenic activity of PLK4 in regulating cancer cell migration and invasion. However, the molecular basis behind the role of PLK4 in these processes still remains only partly understood. Our previous work has demonstrated that an intact CEP85-STIL binding interface is necessary for robust PLK4 activation and centriole duplication. Here, we show that CEP85 and STIL are also required for directional cancer cell migration. Mutational and functional analyses reveal that the interactions between CEP85, STIL and PLK4 are essential for effective directional cell motility. Mechanistically, we show that PLK4 can drive the recruitment of CEP85 and STIL to the leading edge of cells to promote protrusive activity, and that downregulation of CEP85 and STIL leads to a reduction in ARP2 (also known as ACTR2) phosphorylation and reorganization of the actin cytoskeleton, which in turn impairs cell migration. Collectively, our studies provide molecular insight into the important role of the CEP85-STIL complex in modulating PLK4-driven cancer cell migration.This article has an associated First Person interview with the first author of the paper.

Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio.

Tissue expansion techniques physically expand swellable gel-embedded biological specimens to overcome the resolution limit of light microscopy. As the benefits of expansion come at the expense of signal concentration, imaging volume and time, and mechanical integrity of the sample, the optimal expansion ratio may widely differ depending on the experiment. However, existing expansion methods offer only fixed expansion ratios that cannot be easily adjusted to balance the gain and loss associated with expansion. Here, a hydrogel conversion-based expansion method is presented, that enables easy adjustment of the expansion ratio for individual needs, simply by changing the duration of a heating step. This method, termed ZOOM, isotropically expands samples up to eightfold in a single expansion process. ZOOM preserves biomolecules for post-processing labelings and supports multi-round expansion for the imaging of a single sample at multiple zoom factors. ZOOM can be flexibly and scalably applied to nanoscale imaging of diverse samples, ranging from cultured cells to thick tissues, as well as bacteria, exoskeletal Caenorhabditis elegans, and human brain samples.

Rapid Design and Analysis of Microtube Pneumatic Actuators Using Line-Segment and Multi-Segment Euler-Bernoulli Beam Models.

Soft material-based pneumatic microtube actuators are attracting intense interest, since their bending motion is potentially useful for the safe manipulation of delicate biological objects. To increase their utility in biomedicine, researchers have begun to apply shape-engineering to the microtubes to diversify their bending patterns. However, design and analysis of such microtube actuators are challenging in general, due to their continuum natures and small dimensions. In this paper, we establish two methods for rapid design, analysis, and optimization of such complex, shape-engineered microtube actuators that are based on the line-segment model and the multi-segment Euler-Bernoulli's beam model, respectively, and are less computation-intensive than the more conventional method based on finite element analysis. To validate the models, we first realized multi-segment microtube actuators physically, then compared their experimentally observed motions against those obtained from the models. We obtained good agreements between the three sets of results with their maximum bending-angle errors falling within ±11%. In terms of computational efficiency, our models decreased the simulation time significantly, down to a few seconds, in contrast with the finite element analysis that sometimes can take hours. The models reported in this paper exhibit great potential for rapid and facile design and optimization of shape-engineered soft actuators.

Perioperative myocardial injury in revascularized coronary patients who undergo noncardiac surgery.

BACKGROUND: Whether high-sensitivity cardiac troponin elevation during the perioperative period is associated with poor clinical outcome in revascularized coronary patients who undergo noncardiac surgery remains unclear. We investigated the effects of perioperative troponin elevation on the long-term clinical outcomes of patients with a history of coronary revascularization. METHODS: We analyzed patients whose pre- or postoperative high-sensitivity cardiac troponin I (hs-cTnI) assay results were available. Patients were divided into two groups according to hs-cTnI levels. The patient groups were analyzed separately according to whether hs-cTnI was assessed preoperatively or postoperatively. The primary outcome was all-cause death during the follow-up period. RESULTS: Median follow-up duration was 25 months (interquartile range 11-50). In the propensity-matched analysis, the risk of all-cause death during follow-up was higher in the group with elevated hs-cTnI group than in the normal group (12.7% vs 6.3%; hazard ratio [HR], 2.67; 95% confidential interval [CI], 1.04-6.82; p = 0.04). In the propensity-matched analysis of preoperative hs-cTnI levels, we found no significant difference between the groups in the rate of all-cause death (12.9% vs. 11.9%; HR, 1.06; 95% CI, 0.45-2.50; p = 0.89). In the postoperative propensity-matched analysis, all-cause death was higher in patients with elevated hs-cTnI than in those with normal levels (14.9% vs. 5.9%; HR, 2.80; 95% CI, 1.01-7.77; p = 0.048). CONCLUSION: In revascularized coronary patients who underwent noncardiac surgery, postoperative (but not preoperative) hs-cTnI elevation was associated with all-cause death during follow-up. Larger datasets are needed to support this finding.

PCNT is critical for the association and conversion of centrioles to centrosomes during mitosis.

A centrosome consists of a pair of centrioles and pericentriolar material (PCM). We manipulated expression of PCNT, a key PCM protein, and investigated roles of PCM in centriole behavior during mitosis. Deletion of PCNT had little effect on interphase centrosomes. However, centrioles in PCNT-deleted mitotic cells prematurely separated and frequently amplified, revealing that centrioles are limited within the spindle poles by PCNT during mitosis. It is known that specific cleavage of PCNT is necessary for centriole separation during mitotic exit. We observed delayed centriole separation in the G0 phase when a non-cleavable mutant form of PCNT was removed or when PCNT was artificially cleaved by TEV protease. Furthermore, a daughter centriole converts to a mother centriole only after experiencing both mitotic exit and specific PCNT cleavage. Based on these results, we propose that a centriole pair disengages upon entering mitosis but remains associated with the surrounding PCM proteins throughout mitosis. During mitotic exit, specific cleavage of PCNT induces PCM disintegration. As a result, a daughter centriole separates from the mother centriole and converts to a young mother centriole.

Nanoscale Modulation of Friction and Triboelectrification via Surface Nanotexturing.

Nanoscale contact electrification (CE) of elastomer surfaces and the resulting tribocharge formation are important in many branches of nanotechnology but their mechanism is not fully clarified. In this Letter, we investigate the mechanism using the recently discovered phenomenon of replica molding-induced nanoscale CE. By generating tribocharge distributions patterned in close correlation with the interfacial nanotextures, the phenomenon provides well-defined targets for the investigation. By applying a variety of scanning probe microscopy techniques (AFM/KPFM/EFM) and finite element modeling (FEM) to the tribocharge distributions, we extract a process model that can explain how their patterns are formed and affected by the interfacial nanotexture's morphology. It turns out that the cumulative distance of the elastomer's tangential sliding during the interfacial separation plays the key role in shaping the tribocharge's distribution pattern. The model proves remarkably universal, staying valid to nanotextures all the way down in the sub-10 nm regime. This replica molding-induced CE also turns out to be an effective tool for sculpting nanoscale tribocharge distributions into unconventional forms, such as rings, partial eclipses, and dumbbells. Both the model and the technique will prove useful in many areas of nanotechnology.

Replica molding-based nanopatterning of tribocharge on elastomer with application to electrohydrodynamic nanolithography.

Replica molding often induces tribocharge on elastomers. To date, this phenomenon has been studied only on untextured elastomer surfaces even though replica molding is an effective method for their nanotexturing. Here we show that on elastomer surfaces nanotextured through replica molding the induced tribocharge also becomes patterned at nanoscale in close correlation with the nanotexture. By applying Kelvin probe microscopy, electrohydrodynamic lithography, and electrostatic analysis to our model nanostructure, poly(dimethylsiloxane) nanocup arrays replicated from a polycarbonate nanocone array, we reveal that the induced tribocharge is highly localized within the nanocup, especially around its rim. Through finite element analysis, we also find that the rim sustains the strongest friction during the demolding process. From these findings, we identify the demolding-induced friction as the main factor governing the tribocharge's nanoscale distribution pattern. By incorporating the resulting annular tribocharge into electrohydrodynamic lithography, we also accomplish facile realization of nanovolcanos with 10 nm-scale craters.

Microdroplet-based On-Demand Drawing of High Aspect-Ratio Elastomeric Micropillar and Its Contact Sensing Application.

High aspect-ratio elastomeric micropillars play important roles as the platform for microscale sensing and actuation. Many soft-lithographic techniques have been developed for their facile realization but most of the techniques are limited to build the micropillars only on totally flat, widely accessible substrate areas with the micropillar's structural characteristics completely predetermined, leaving little room for in situ control. Here we demonstrate a new technique which overcomes these limitations by directly drawing micropillars from pipette-dispensed PDMS microdroplets using vacuum-chucked microspheres. The combined utilization of PDMS microdroplets and microspheres not only enables the realization of microsphere-tipped PDMS micropillars on non-flat, highly space-constrained substrate areas at in situ controllable heights but also allows arraying of micropillars with dissimilar heights at a close proximity. To validate the new technique's utility and versatility, we realize PDMS micropillars on various unconventional substrate areas in various configurations. We also convert one of them, the optical fiber/micropillar hybrid, into a soft optical contact sensor. Both the fabrication technique and the resulting sensing scheme will be useful for future biomedical microsystems.

The DNA replication protein Cdc6 inhibits the microtubule-organizing activity of the centrosome.

The centrosome serves as a major microtubule-organizing center (MTOC). The Cdc6 protein is a component of the pre-replicative complex and a licensing factor for the initiation of chromosome replication and localizes to centrosomes during the S and G2 phases of the cfell cycle of human cells. This cell cycle-dependent localization of Cdc6 to the centrosome motivated us to investigate whether Cdc6 negatively regulates MTOC activity and to determine the integral proteins that comprise the pericentriolar material (PCM). Time-lapse live-cell imaging of microtubule regrowth revealed that Cdc6 depletion increased microtubule nucleation at the centrosomes and that expression of Cdc6 in Cdc6-depleted cells reversed this effect. This increase and decrease in microtubule nucleation correlated with the centrosomal intensities of PCM proteins such as γ-tubulin, pericentrin, CDK5 regulatory subunit-associated protein 2 (CDK5RAP2), and centrosomal protein 192 (Cep192). The regulation of microtubule nucleation and the recruitment of PCM proteins to the centrosome required Cdc6 ATPase activity, as well as a centrosomal localization of Cdc6. These results suggest a novel function for Cdc6 in coordinating centrosome assembly and function.