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Over the last 30-years, microchip electrophoresis and its applications have expanded due to the benefits it offers. Nanochip electrophoresis, on the other hand, is viewed as an evolving area of electrophoresis because it offers some unique advantages not associated with microchip electrophoresis. These advantages arise from unique phenomena that occur in the nanometer domain not readily apparent in the microscale domain due to scale-dependent effects. Scale-dependent effects associated with nanochip electrophoresis includes high surface area-to-volume ratio, electrical double layer overlap generating parabolic flow even for electrokinetic pumping, concentration polarization, transverse electromigration, surface charge dominating flow, and surface roughness. Nanochip electrophoresis devices consist of channels with dimensions ranging from 1 to 1000 nm including classical (1–100 nm) and extended (100 nm – 1000 nm) nanoscale devices. In this review, we highlight scale-dependent phenomena associated with nanochip electrophoresis and the utilization of those phenomena to provide unique biomolecular separations that are not possible with microchip electrophoresis. We will also review the range of materials used for nanoscale separations and the implication of material choice for the top-down fabrication and operation of these devices. We will also provide application examples of nanochip electrophoresis for biomolecule separations with an emphasis on nano-electrophoresis (nEP) and nano-electrochromatography (nEC).

The presence of air bubbles boosts the shear resistance and causes pressure fluctuation within fluid-perfused microchannels, resulting in possible cell damage and even malfunction of microfluidic devices. Eliminating air bubbles is especially challenging in microscale where the adhesive surface tension force is often dominant over other forces. Here, we present an air bubble removal strategy from a novel surface engineering perspective. A microfluidic port-to-port interconnect was fabricated by modifying the peripheral of the microfluidic ports superhydrophobic, while maintaining the inner polymer microchannels hydrophilic. Such a sharp wettability contrast enabled a preferential fluidic entrance into the easy-wetting microchannels over the non-wetting boundaries of the microfluidic ports, while simultaneously filtering out any incoming air bubbles owing to the existence of port-to-port gaps. This bubble-eliminating capability was consistently demonstrated at varying flow rates and liquid analytes. Compared to equipment-intensive techniques and porous membrane-venting strategies, our wettability contrast-governed strategy provides a simple yet effective route for eliminating air bubbles and simultaneously sealing microfluidic interconnects.

Currently there is no in vitro diagnostic test for acute ischemic stroke (AIS), yet rapid diagnosis is crucial for effective thrombolytic treatment. We previously demonstrated the utility of CD8(+) T-cells’ mRNA expression for AIS detection; however extracellular vesicles (EVs) were not evaluated as a source of mRNA for AIS testing. We now report a microfluidic device for the rapid and efficient affinity-enrichment of CD8(+) EVs and subsequent EV’s mRNA analysis using droplet digital PCR (ddPCR). The microfluidic device contains a dense array of micropillars modified with anti-CD8α monoclonal antibodies that enriched 158 ± 10 nm sized EVs at 4.3 ± 2.1 × 109 particles/100 µL of plasma. Analysis of mRNA from CD8(+) EVs and their parental T-cells revealed correlation in the expression for AIS-specific genes in both cell lines and healthy donors. In a blinded study, 80% test positivity for AIS patients and controls was revealed with a total analysis time of 3.7 h., Wijerathne et al develop an approach to quantify mRNA amounts in extracellular vesicles (EVs) from plasma using a microfluidics device to enrich EVs. They show this method allows for the correlation of specific mRNAs with acute ischemic stroke pointing towards potential clinical use.

Existing methods for sealing chip-to-chip (or module-to-motherboard) microfluidic interconnects commonly use additional interconnect components (O-rings, gaskets, and tubing), and manual handling expertise for assembly. Novel gasketless superhydrophobic fluidic interconnects (GSFIs) sealed by transparent superhydrophobic surfaces, forming liquid bridges between the fluidic ports for fluidic passages were demonstrated. Two test platforms were designed, fabricated, and evaluated, a multi-port chip system (ten interconnects) and a modules-on-a-motherboard system (four interconnects). System assembly in less than 3 sec was done by embedded magnets and pin-in-V-groove structures. Flow tests with deionized (DI) water, ethanol/water mixture, and plasma confirmed no leakage through the gasketless interconnects up to a maximum flow rate of $100~\mu \text{L}$ /min for the multi-port chip system. The modules-on-a-motherboard system showed no leakage of water at a flow rate of $20~\mu \text{L}$ /min and a pressure drop of 3.71 psi. Characterization of the leakage pressure as a function of the surface tension of the sample liquid in the multi-port chip system revealed that lower surface tension of the liquid led to lower static water contact angles on the superhydrophobic-coated substrate and lower leakage pressures. The high-density, rapidly assembled, gasketless interconnect technology will open up new avenues for chip-to-chip fluid transport in complex microfluidic modular systems. [2020-0168]

An improved, laser-induced fluorescence-based micro-optical biosensor was designed and fabricated, with cyclic olefin copolymer (COC) optical waveguides, a poly(methyl methacrylate) (PMMA) fluidic substrate with an array of microlenses, and a COC coupling prism integrated with the waveguide substrate or cover plate. The double-sided hot embossed fluidic substrate had sampling zone microchannels on the bottom and microlenses on the top. Dissolved COC injected into polydimethylsiloxane (PDMS) lost molds embedded the waveguides in the PMMA cover plate and formed the integrated coupling prism. The embedded COC waveguide was flycut down to $50~\mu \text{m}$ . The cover plate and shallow, 1:20 aspect ratio, microchannels were thermal fusion bonded using a pressure-assisted boiling point control system, without sagging. The large COC prism coupled better to the waveguide. The highest intensity evanescent excitation of the waveguide was obtained near the critical angle. The maximum signal-to-noise ratio (SNR) was 119 and the lowest detection limit was 7.34 $\times 10^{\mathbf {-20}}$ mol at a SNR of 2 for a $100~\mu \text{m}$ wide by $50~\mu \text{m}$ deep waveguide. The microlenses highly focused the fluorescent radiation in the sampling zone. The microfabricated waveguide enables rapid, low-cost detection of fluorescent samples with high SNR, a low detection limit, and high sampling efficiency. [2020-0067]

Background Suicide is a leading cause of death among children, adolescents, and young adults (AYA), and mental health disorders are a major contributing factor. Yet, suicidal behaviors among children and AYA with mental health concerns remain understudied and age-specific risk factors are poorly understood. We examined the risk factors for suicide attempt in children and AYA with mental health disorders across three age groups: pre-adolescent children (aged ≤ 12), adolescents (aged 13-17), and young adults (aged 18-25). Methods A cross-sectional study of children and AYA hospitalized for a mental health disorder (n = 18,018) at a private hospital system with 141 facilities across the United States (year 2014). Results Suicide attempts six months prior to hospitalization were reported in 12.1% (n = 177) pre-adolescent children, 22% (n = 1476) adolescents, and 17.9% (n = 1766) young adults. Evidence of psychological trauma was present in 55.4% of pre-adolescent children, 51.2% of adolescents, and 44.5% of young adults. Predictors for suicide attempt observed across all three age groups included the following: female sex, depressive disorder, and being a victim of bullying. Risk factors for suicide attempt specific to pre-adolescent children included being uninsured and having an unsafe home or school environment. Among AYA, suicide attempt was associated with non-Hispanic white, family history of suicide, emotional traumas, and other traumatic experiences. Alcohol use disorder was also a significant predictor of suicide attempt in young adults. Conclusions Suicide attempts among children and AYA admitted to a hospital with mental health concerns are highly prevalent. Socioeconomic stressors appeared to be an important contributing factor of suicidal behavior in pre-adolescent children but not in older AYA. Effective suicide prevention strategies targeting children and AYA would need to consider age-specific risk factors.

Chip-to-chip and world-to-chip fluidic interconnections are paramount to enable the passage of liquids between component chips and to/from microfluidic systems. Unfortunately, most interconnect designs add additional physical constraints to chips with each additional interconnect leading to over-constrained microfluidic systems. The competing constraints provided by multiple interconnects induce strain in the chips, creating indeterminate dead volumes and misalignment between chips that comprise the microfluidic system. A novel, gasketless superhydrophobic fluidic interconnect (GSFI) that uses capillary forces to form a liquid bridge suspended between concentric through-holes and acting as a fluid passage was investigated. The GSFI decouples the alignment between component chips from the interconnect function and the attachment of the meniscus of the liquid bridge to the edges of the holes produces negligible dead volume. This passive seal was created by patterning parallel superhydrophobic surfaces (water contact angle ≥ 150°) around concentric microfluidic ports separated by a gap. The relative position of the two polymer chips was determined by passive kinematic constraints, three spherical ball bearings seated in v-grooves. A leakage pressure model derived from the Young–Laplace equation was used to estimate the leakage pressure at failure for the liquid bridge. Injection-molded, Cyclic Olefin Copolymer (COC) chip assemblies with assembly gaps from 3 to 240 µm were used to experimentally validate the model. The maximum leakage pressure measured for the GSFI was 21.4 kPa (3.1 psig), which corresponded to a measured mean assembly gap of 3 µm, and decreased to 0.5 kPa (0.073 psig) at a mean assembly gap of 240 µm. The effect of radial misalignment on the efficacy of the gasketless seals was tested and no significant effect was observed. This may be a function of how the liquid bridges are formed during the priming of the chip, but additional research is required to test that hypothesis.

Due to the rapid developmental growth in preschool-aged children, more precise measurement of the effects of burns on child health outcomes is needed. Expanding upon the Shriners Hospitals for Children/American Burn Association Burn Outcome Questionnaire 0 to 5 (BOQ0–5), we developed a conceptual framework describing domains important in assessing recovery from burn injury among preschool-aged children (1–5 years). We developed a working conceptual framework based on the BOQ0–5, the National Research Council and Institute of Medicine’s Model of Child Health, and the World Health Organization’s International Classification of Functioning, Disability, and Health for Children and Youth. We iteratively refined our framework based on a literature review, focus groups, interviews, and expert consensus meetings. Data were qualitatively analyzed using methods informed by grounded theory. We reviewed 95 pediatric assessments, conducted two clinician focus groups and six parent interviews, and consulted with 23 clinician experts. Three child health outcome domains emerged from our analysis: symptoms, functioning, and family. The symptoms domain describes parents’ perceptions of their child’s pain, skin-related discomfort, and fatigue. The functioning domain describes children’s physical functioning (gross and fine motor function), psychological functioning (internalizing, externalizing, and dysregulation behavior; trauma; toileting; resilience), communication and language development (receiving and producing meaning), and social functioning (connecting with family/peers, friendships, and play). The family domain describes family psychological and routine functioning outcomes.

Background The short form, 17-item version of the Pediatric Symptom Checklist-Youth Self-Report (PSC-17-Y) is a validated measure that assesses psychosocial problems overall (OVR) and in 3 major psychopathological domains (internalizing, externalizing, and attention-deficit/hyperactivity disorder), taking 5-10 min to complete. Prior research has established sound psychometric properties of the PSC-17-Y for English speakers. Objective This study extends psychometric evidence for the acceptability of the PSC-17-Y in a large sample of Spanish adolescents, providing proof of its reliability and structure, convergent and discriminant validity, and longitudinal and gender invariance. Methods Data were collected on 5430 adolescents, aged 12-18 years, who filled out the PSC-17-Y twice during 2018-2019 (7-month interval). We calculated the Cronbach alpha and the McDonald omega coefficients to test reliability, the Pearson correlation for convergent (distress) and criterion validity (well-being, quality of life, and socioemotional skills), confirmatory factor analysis (CFA) for structure validity, and multigroup and longitudinal measurement invariance analysis for longitudinal and gender stability. Results Within structural analysis for the PSC-17-Y, CFA supported a correlated 3-factor solution, which was also invariant longitudinally and across gender. All 3 subscales showed evidence of reliability, with coefficients near or above .70. Moreover, scores of PSC-17-Y subscales were positively related with convergent measures and negatively related with criterion measures. Normative data for the PSC-17-Y are presented in the form of percentiles (75th and 90th). Conclusions This work provides the first evidence of the reliability and validity of the Spanish version of the PSC-17-Y administered over the internet to assess mental health problems among adolescents, maintaining the same domains as the long version.

Traditionally, cardiac and vascular surgeons have been treating diseases of the aorta as individual specialists. Neither cardiac nor vascular surgeons have ever considered the aorta as a whole, which can be diseased throughout its length at the same time requiring a more thoughtful and different approach. Aortic dissection and aneurysmal disease may well benefit from a multidisciplinary approach. In the context of this review, we discuss examples of joint operating between cardiac and vascular surgeons that may well become a more routine approach in more units in the future.

Hypothesis Compared to vertical micro-pillars, re-entrant micro-structures exhibited superior omniphobicity for suspending liquids to Cassie-Baxter state. However, the existing re-entrant structures rely on complex multi-step deposition and etching procedures. The conventional, rigid-templated imprinting would instead damage the re-entrant structures. This leads to the question: is it possible to preserve the re-entrant curvatures by a flexible-templated imprinting? Experiments We facilely imprinted the re-entrant structures on a plastic substrate using a flexible nylon-mesh template. The effect of imprinting time (15–35 min), temperature (110–120 °C) and pressure (15–50 Bar) was investigated. To further improve the liquid-repellency and abrasion resistance, the silica nanoparticles (30–650 nm) along with epoxy resin binder (10 mg/mL) were pre-coated. Findings A one-step imprinting is sufficient to fabricate the re-entrant structures by utilizing flexible nylon-mesh template, without damaging the imprinted structures after the demolding process. The pre-coated silica nanoparticles and epoxy resin (1) improved liquid repellency by introducing hierarchical surface structures (e.g. contact angle hysteresis of olive oil reduced > 10°), and (2) acted as a protective layer against mechanical abrasion (omniphobicity maintained after 25 cycles, ~1.6 kPa sand paper abrasion). Additionally, the fluorine-free post-treatment was sufficient for the omniphobicity on the obtained plastic structures.

Antimony(V) carboxylate photoresists incorporating polymerizable olefins have demonstrated high photospeeds. The work of Passarelli et al. reported a sensitivity hypothesis, polymerizable olefin loading (POL), in which an increase in photospeed correlates to an increase in the number of olefins per molecular weight of resist.1 Utilizing this sensitivity trend, a photoresist of higher molecular weight, triphenylantimony(V) bis(4-vinylbenzoate) (JP-30), was developed exhibiting moderate photospeed at the cost of improved pattern fidelity. Herein we report three approaches for improving the lithographic performance of polymerizable olefin antimony carboxylate photoresists. Approach 1 increased the number of olefins per molecule through functionalization of the R-group. Tristyreneantimony(V) dicarboxylate photoresists were lithographically evaluated exhibiting high photospeeds and improved resolution capabilities (Figure 1). Approach 2 examined the benefits of blending two antimony carboxylate photoresists with high and low POL values and observing the changes in photospeed. Approach 3 increased the POL relative to JP-30 through reduction in molecular weight of the R-groups by the synthesis and lithographic evaluation of trimethylantimony(V) bis(4-vinylbenzoate).

Hypothesis The superhydrophobic lotus leaf has dual-scale surface structures, that is, nano-bumps on micro-mountains. Large hydrophilic particles, due to its high surface energy and weight, have high affility to substrates and tend to precipitate at the bottom of coating films. Small hydrophobic particles, due to its low surface energy and weight, tends to sit on the top of coating films and form porous structures. To mimic the lotus leaf surface, it may be possible to develop dual-sized particle films, in which small particles are decorated on large particles. Experiments A one-step spin coating of a mixture of dual-sized silica particles (55/200 nm) was used. Epoxy resin was added to improve the adhesion of particle films. The single-sized and dual-sized particle films were compared. The mechanical robustness of particle films was tested by tape peeling and droplet impact. Findings The novel combination of hydrophobic silica (55 nm) and hydrophilic silica (200 nm) is essential in creating the hierarchical structures. By combining the strong adhesion of hydrophilic silica (bottom of coating film) to polymer substrates and porous structures of hydrophobic silica (top of coating film), we first time report a one-step and versatile approach to create uniform, transparent, robust, and superhydrophobic surface.

Children who exhibit mental health problems are more likely to be targets of peer victimization. However, little is known about how mental health risk interacts with other individual and school-level factors in this relationship. In the current study, we explored the associations between peer victimization and mental health in 10,532 Chilean sixth grade students attending 405 of the lower SES schools in the country. Children were screened for mental health and classroom adaptation problems using standardized parent and teacher rating scales at the beginning of the school year, and completed questionnaires on self-reported peer victimization, classroom climate, and school climate at the end of the year, as part of an ongoing national school mental health program, which includes monitoring for school violence and school climate. Data were analyzed through logistic regression and multilevel analyses, incorporating sex, absenteeism due to physical health, school attendance, and individual SES as covariates. Results showed that the odds of being victimized by peers were five times greater for students who were identified at risk for mental health problems based on parent reports, and one time greater for students identified by teachers with attention and concentration difficulties. However, multilevel analyses showed that the relative contribution of mental health risk to peer victimization significantly diminished when other individual and school-level variables were included. Particularly relevant was the contribution of individual SES, classroom climate, and absenteeism due to physical health; and of school-level SES. These findings suggest the complex nature of the influence of mental health on peer victimization and the relevance of the social context interacting with student’s mental health problems.

A method for the design, construction, and assembly of modular, polymer-based, microfluidic devices using simple micro-assembly technology was demonstrated to build an integrated fluidic system consisting of vertically stacked modules for carrying out multi-step molecular assays. As an example of the utility of the modular system, point mutation detection using the ligase detection reaction (LDR) following amplification by the polymerase chain reaction (PCR) was carried out. Fluid interconnects and standoffs ensured that temperatures in the vertically stacked reactors were within ± 0.2 C° at the center of the temperature zones and ± 1.1 C° overall. The vertical spacing between modules was confirmed using finite element models (ANSYS, Inc., Canonsburg, PA) to simulate the steady-state temperature distribution for the assembly. Passive alignment structures, including a hemispherical pin-in-hole, a hemispherical pin-in-slot, and a plate-plate lap joint, were developed using screw theory to enable accurate exactly constrained assembly of the microfluidic reactors, cover sheets, and fluid interconnects to facilitate the modular approach. The mean mismatch between the centers of adjacent through holes was 64 ± 7.7 μm, significantly reducing the dead volume necessary to accommodate manufacturing variation. The microfluidic components were easily assembled by hand and the assembly of several different configurations of microfluidic modules for executing the assay was evaluated. Temperatures were measured in the desired range in each reactor. The biochemical performance was comparable to that obtained with benchtop instruments, but took less than 45 min to execute, half the time.

One of the long-standing problems for nanoparticle-based liquid-repellent coatings is their poor adhesion to substrates. For polymers with low glass transition temperatures, it is highly desirable to have a low temperature coating strategy to fabricate robust superhydrophobic films. Here, we report a facile method for fabricating robust, transparent, superhydrophobic films on polymer substrates. A mixture of silica particles and silica-based oligomers was spin coated on polymer substrates, followed by oxygen plasma treatment and vapor deposition of 1 H,1 H,2 H,2 H-Perfluorodecyltriethoxysilan (FDTS). The resulting superhydrophobic surface has a static contact angle of 160° and contact angle hysteresis less than 5°. This is a practical solution for improving the adhesion of superhydrophobic films on polymer substrates under ambient conditions.

A multi-scale fluidic motherboard, which can be used in a universal molecular processing system (uMPS) integrated with task-specific processing modules, was designed and fabricated in thermoplastics. The motherboard consists of a coverplate and a substrate. The coverplate included fluidic interconnects and thermal grooves on the top side, and the corresponding interconnects on the bottom side. The substrate was comprised of cell lysis microchannels, micromixers, and flow-connecting microchannels on the top side, and reservoirs for sample inputs and waste output, thermal grooves, and valve seats for flow control on the bottom side. The coverplates and substrates were fabricated with double-sided hot embossing of polycarbonate (PC) using four micromilled brass molds, two for the coverplate and another two for the substrate. Evaluation of the relative front-to-backside alignment for the double-sided hot embossing yielded an accuracy of 25 μm ± 14 μm (average ± standard deviation) for the coverplates and 30 μm ± 20 μm for the substrates. Thermal fusion bonding (TFB) of the coverplate and substrate was done using a spring plunger bonding setup with a range of temperatures and pressures. The motherboard bonded at 154 °C and 12.0 psi for 2 hours in a convection oven produced complete bonding with a little deformation of the valve seats. The complete motherboard will be integrated with the task-specific processing modules in the uMPS for investigating circulating markers from whole blood for precision molecular diagnosis of disease at low cost and with high fidelity.

The EUV photoproducts of antimony carboxylate photoresists [R3Sb(O2CR′)2] are used to evaluate a possible free radical exposure mechanism by studying the change in molecular weight distribution with dose. We demonstrate the redistribution of carboxylate ligands across the metal centers in solution and use this property to create a statistical mono-olefin resist system with blended solutions of olefinic and non-olefinic antimony compounds that limit crosslinking and improve solubility of the photoproducts. Through gel permeation chromatography (GPC) analysis, we demonstrate the formation of high molecular weight oligomers with exposure dose and provide further support for the free-radical polymerization mechanism.

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is used to evaluate the composition of nonvolatile photoproducts created by EUV photolysis of antimony carboxylate photoresists [R3Sb(O2CR′)2]. Dozens of potential photoproduct ions were identified using exact mass and 121Sb/123Sb isotopic ratios. Several oxygen-rich antimony ions were found to increase in abundance with exposure. Two methods were employed to identify photoproducts which create solubility contrast. First, samples were analyzed pre- and post-development to examine the effects of EUV exposure and developer solvent on secondary ion intensity. Secondly, changes in intensity of select ions were compared to dissolution contrast over a range of doses. Through these studies, ion intensities were found to correlate with dissolution contrast for several fragments, indicating their active role in creating negative-tone response.

With sizes larger than molecules but smaller than colloidal particles, nanoparticles exhibit unique transport properties in porous media. They can easily pass through typical pore throats in reservoir formations with micron diameters, but may get retained by physicochemical interaction with the pore walls. Based on detailed analysis of nanoparticle retention data from an extensive series of transport experiments, we examine the limitations of classical models of transport and interaction with a stationary phase. Some features of nanoparticle transport and retention are similar to those of adsorbing/desorbing solutes, while others are similar to those of depositing colloids. But neither solute sorption nor colloid filtration alone can explain all nanoparticle retention features, and of particular importance for subsurface applications, neither model can predict the effect of changing flow conditions on nanoparticle retention. The model that accounts for most observations is an independent two-site model which postulates physically independent sites of fixed capacity: one for reversible attachment and the other for irreversible attachment. We validate the model against five distinctly different groups of experimental data from the literature, through a rigorous approach of obtaining the model parameters from one experiment and blind testing against data from other experiments when experimental conditions vary.

OBJECTIVES Point-of-care ultrasonography (POCUS) is an increasingly integral part of emergency medicine. This study investigated community emergency department physicians' choices regarding ultrasonography as a branch point in clinical decision making. METHODS During shifts covering all days of the week and all time-spans over a 3-month period, emergency department physicians were interviewed whenever POCUS was used. Questions focused on the role of POCUS in clinical management and on tests avoided because of ultrasonography use. Cost savings attributable to POCUS were calculated using Center for Medicare and Medicaid Services and FairHealth data. Anonymization of data precluded follow-up testing to account for misdiagnosis. RESULTS On average, POCUS use eliminated $1134.31 of additional testing for privately insured patients, $2826.31 for out-of-network or uninsured patients, and $181.63 for Center for Medicare and Medicaid Services patients. Differences were significant when the total cost of eliminated additional testing was compared to a baseline of no savings (p

Based on the outcomes from the automated trucking breakout session at the 2017 Automated Vehicles Symposium, this Chapter reviews the current state-of-the-art of automated trucking applications and discusses key factors expected to influence their deployment. It is suggested that a key challenge for the deployment of automation in the trucking domain is that the business models are typically linked to specific and strongly heterogeneous transport operations, each of which associated with a specific set of deployment factors. To handle this complexity, strategic partnerships are expected to be formed between stakeholders, where business models and other deployment factors can be addressed jointly, and in a step-wise fashion, for specific automated trucking operations.

This paper describes the photoreactivity of six organometallic complexes of the type PhnMX2 containing bismuth, antimony and tellurium, where n = 3 for bismuth and antimony and n = 2 for tellurium, and where X = acetate (O2CCH3) or pivalate (O2CC(CH3)3). These compounds were exposed to EUV light to monitor photodecomposition via in situ mass spectral analysis of the primary outgassing products of CO2, benzene and phenol. This paper explores the effect of metal center and carboxylate ligand on the EUV reactivity of these EUV photoresists.

We have investigated the mechanism of photodecomposition of antimony carboxylate complexes of the type Ph3Sb(O2CR′)2 by means of EUV outgassing in combination with isotopic labelling. A series of photoresists were examined to determine the mechanistic pathways by which volatile photoproducts are generated during EUV exposure. A primary volatile photoproduct from triphenylantimony complexes is benzene. However, the source of hydrogen needed to convert the phenyl groups to benzene (Ph-H) is not obvious. We concluded that the primary source of hydrogen to create benzene is external to the film. Additionally, we have prepared isotopically-labelled versions of Ph3Sb(O2CCH(CH3)2)2 in which the hydrogens in the isobutyrate ligand were replaced with 0, 1, 6 and 7 deuteriums, to provide information about the relative reactivity of these protons during EUV exposure as analyzed by mass spectrometry. High reaction selectivity was identified within the carboxylate dictated by hydrogen location relative to the carbonyl for both benzene and phenol generation. Lastly, the results of these studies were used to propose a series of reaction pathways to generate the aforementioned reaction byproducts.

The photo-mechanism of EUV exposures in chemically amplified photoresists are much different than that of previous lithographic wavelengths. Electrons generated during EUV exposure are demonstrated to be a source of acid production through a process referred to as electron trapping. Density functional theory modeling indicates that it is energetically favorable for the PAG molecule to decompose if an electron is trapped. Low-energy electrons unlikely to produce holes and secondary electrons generate acid indicating electron-PAG interactions are capable to induce decomposition. Additionally, a more easily reduced PAG (i.e. higher likelihood of trapping an electron) produces a higher acid yield supporting electron trapping as a process of acid production. An acid indicator, Coumarin 6, was used to determine the number of acids generated per absorbed EUV photon. The results of these measurements indicate that electron-PAG interactions are a source of acid production through electron trapping; thus, increasing the number of electron-hole pairs available to induce chemical reactions would improve sensitivity. It is expected that lower band gap materials produce more electron-hole pairs after an absorption event. Subsequently, these measurements show that lower band gap polymers generate higher acid yields.

Two-photon fluorescence lifetime imaging microscopy (FLIM) is a technique that not only probes the intensity of fluorophores, but also provides the temporal decay trace of said fluorophores on a pixel-by-pixel basis. These traces can then be transformed into the frequency domain for subsequent analysis, resulting in a scatterplot of phasor coordinates where each phasor corresponds to a single image pixel. With this in mind, it follows that individual fluorophores result in distinct clusters in the phasor plot, and a mixture of two fluorophores results in phasors that fall somewhere along a line linking the two clusters depending on the relative fluorophore concentrations. Until now, distinction of fluorescent species has relied mainly on computing the Euclidean distance between a given phasor and the mean coordinates of reference phasor clusters. However, this approach becomes inadequate in cases where one fluorophore has a much wider lifetime distribution than the other. As such, we propose the use of the Mahalanobis distance as an alternative to the Euclidean distance, as this metric additionally factors in the relative spread of each reference phasor cluster. This method has been applied to studying the oxidative response of ex vivo human skin via endogenous NADH fluorescence as it is exposed to chemical sun filters, the active ingredients in sunscreens. Given that both NADH and sun filters are fluorescent under the same excitation and emission conditions, the proposed Mahalanobis distance approach was used to distinguish the source of fluorescence in images of human skin. This allowed for the assessment of oxidative response as well as the tracking and monitoring of the sun filter formulation as it permeated throughout the skin.

Adverse weather poses a significant threat to transportation safety. Road weather information systems (RWIS) are used to mitigate the impact of adverse weather. Because of the lack of detailed, unified guidelines and because of diverse weather conditions across the United States, state and city transportation agencies follow different practices for choosing locations for environmental sensor stations. This paper proposes a comprehensive cell-based methodology that optimizes overall benefits of RWIS based on weather-sensitive crash characterizations and using both normal and adverse weather crash data. The proposed approach is especially suited to optimizing regionwide environmental sensor station locations involving many road segments. A case study concerning RWIS deployment in Austin, Texas, was conducted with data from a crash records information system for 2010 to 2013.

This research evaluated the use of a milling machine to texture pavement surfaces and its effect on skid improvement. Texturing tests with different milling drums, forward speeds and cutting depths were conducted on 31 asphalt pavement sections across Texas. Macrotexture and friction were measured before the milling and 3, 6, 12, and 18 months after the milling. The results show that sections milled with fine drums exhibited a higher skid resistance and macrotexture after milling. The test results also indicate that the forward milling speed is positively associated with both skid resistance and macrotexture. In other words, higher milling speeds tend to produce surfaces with higher skid resistance and macrotexture. The data suggests that milling operations on average provide a service life of about 12 months on seal coats, whereas milling on HMA sections extends the service life beyond 18 months.

Scalable syntheses of two-dimensional topological insulators are critical to material exploration. We demonstrate a controlled assembly of a two-dimensional V–VI group compound, Sb2Te3 nanoplates (NPs), through a vapor–solid growth process. The physical thickness of Sb2Te3 NPs can be rationally controlled in a wide range, from hundreds of nm down to sub-10 nm. Single-quintuple-layer Sb2Te3 NPs were obtained, with a high domain density of ∼2.465 × 108 cm−2 over a large surface area (1 cm × 1 cm) of a SiO2/Si substrate, verifying a scalable synthesis method. Extensive material analyses were conducted to explore the basic properties of Sb2Te3 NPs using SEM and AFM, etc. HRTEM analysis confirms that the NP samples exhibit a highly crystalline structure and XPS analysis confirms the chemical composition and material stoichiometry. The growth of 2D topological insulator nanostructures may open up new opportunities in surface-state studies and potential applications in low-dissipative electronic systems.

Chemical sun filters are commonly used as active ingredients in sunscreens due to their efficient absorption of ultraviolet (UV) radiation. Yet, it is known that these compounds can photochemically react with UV light and generate reactive oxygen species and oxidative stress in vitro, though this has yet to be validated in vivo. One label-free approach to probe oxidative stress is to measure and compare the relative endogenous fluorescence generated by cellular coenzymes nicotinamide adenine dinucleotides and flavin adenine dinucleotides. However, chemical sun filters are fluorescent, with emissive properties that contaminate endogenous fluorescent signals. To accurately distinguish the source of fluorescence in ex vivo skin samples treated with chemical sun filters, fluorescence lifetime imaging microscopy data were processed on a pixel-by-pixel basis using a non-Euclidean separation algorithm based on Mahalanobis distance and validated on simulated data. Applying this method, ex vivo samples exhibited a small oxidative shift when exposed to sun filters alone, though this shift was much smaller than that imparted by UV irradiation. Given the need for investigative tools to further study the clinical impact of chemical sun filters in patients, the reported methodology may be applied to visualize chemical sun filters and measure oxidative stress in patients' skin.

Pure thin-films of unimolecular organometallic photoresists were lithographically evaluated using extreme ultraviolet light (EUV, λ = 13.5 nm) and developed using solutions containing carboxylic acids. Optimization of development solutions used with a cobalt-oxalate EUV resist (NP1, 2) led to a switch in lithographic tone from negative to positive. Additional optimization led to an improvement in top loss (35 to 7%) with development in cyclohexanone and 2-butanone, respectively. We saw a drastic improvement in photo-speed (Emax = 5 mJ/cm2) and contrast of the negative-tone imaging with development in certain acidic solutions. Additionally, carboxylic acid solutions provide excellent development conditions for resists that we, in the past, have been unable to successfully develop.

We have developed a method to study the photomechanism of our antimony carboxylate platform R3Sb(COOR')2. A series of mechanistic studies followed the production of reaction byproducts by mass spectrometer, as they left the film during exposure to EUV photons and 80 eV electrons. We identified several prominent outgassing fragments and their rates of production as a function of ligand structure. The degree of outgassing appears to be well-correlated with the bond dissociation energy of the carboxylate ligand R’ group. Furthermore, a deuterium labeling study was conducted to determine from which ligand hydrogen is abstracted to form benzene and phenol during exposure. Benzene and phenol were found to abstract hydrogen from opposing sites within the film, and with greater than 95% isotopic purity. Using the results of the outgassing studies alongside established mechanisms for electron-induced reactions; a series of reaction pathways were proposed to generate the aforementioned outgassing species and a possible nonvolatile negative-tone photoproduct.

the microelectronics industry. Traditional EUV photoresists have been composed of organic compounds which are moderately transparent to EUV. Resist stochastics and sensitivity can be improved by increasing the number of photons absorbed. Molecular organometallic resists are a type of metal containing resist aimed at improving EUV absorption. This work focuses on studying the role of the metal center (Metal = Co, Fe, Cr) in an oxalate complex by comparing the number of absorbed photons and the photoelectron reactivity in each compound. In the study presented here, the EUV absorption coefficients are determined experimentally by measuring the transmission through a resist coated on a silicon nitride membrane using an Energetiq EQ-10M xenon plasma EUV source. Additionally, the photochemistry is evaluated by monitoring outgassing reaction products. This particular resist platform eliminates oxalate ligands when exposed to electrons or EUV photons resulting in a solubility difference between the exposed and unexposed regions. In the process, carbon dioxide is produced and is monitored using mass spectrometry, where quantitative values are obtained using a calibration technique. For the metal oxalate complexes studied, the absorption of EUV changed minimally due to the low concentrations of metal atoms. However, EUV and electron reactivity greatly changed between the three compounds likely due to the reducibility of the metal center. A correlation is shown between Esize and the reducibility of each photoresist.

Extreme ultraviolet (EUV, ~13.5 nm) lithography is the prospective technology for high volume manufacturing by the microelectronics industry. Significant strides towards achieving adequate EUV source power and availability have been made recently, but a limited rate of improvement in photoresist performance still delays the implementation of EUV. Many fundamental questions remain to be answered about the exposure mechanisms of even the relatively well understood chemically amplified EUV photoresists. Moreover, several groups around the world are developing revolutionary metal-based resists whose EUV exposure mechanisms are even less understood. Here, we describe several evaluation techniques to help elucidate mechanistic details of EUV exposure mechanisms of chemically amplified and metal-based resists. EUV absorption coefficients are determined experimentally by measuring the transmission through a resist coated on a silicon nitride membrane. Photochemistry can be evaluated by monitoring small outgassing reaction products to provide insight into photoacid generator or metal-based resist reactivity. Spectroscopic techniques such as thin-film Fourier transform infrared (FTIR) spectroscopy can measure the chemical state of a photoresist system pre- and post-EUV exposure. Additionally, electrolysis can be used to study the interaction between photoresist components and low energy electrons. Collectively, these techniques improve our current understanding of photomechanisms for several EUV photoresist systems, which is needed to develop new, better performing materials needed for high volume manufacturing.

The research team recognized the value of network-level falling weight deflectometer (FWD) testing to evaluate the structural condition trends of flexible pavements. However, practical limitations due to the cost of testing, traffic control and safety concerns, and the ability to test a large network may discourage some agencies from conducting the network-level FWD testing. For this reason, the surrogate measure of the structural condition index (SCI) is suggested for use. The main purpose of the research presented in this paper is to investigate data-mining strategies and to develop a prediction method of the structural condition trends for network-level applications, which do not require FWD testing. The research team first evaluated the existing and historical pavement condition, distress, ride, traffic, and other data attributes in the Texas Department of Transportation (TxDOT) Pavement Maintenance Information System (PMIS); applied data-mining strategies to the data; discovered useful patter...

Bedside ultrasound is an extremely valuable and rapidly accessible diagnostic and therapeutic modality in potentially life- and limb-threatening situations in the emergency department. In this report, the authors discuss the role of ultrasound in quick assessment of pathologic conditions and its use to aid in diagnostic and therapeutic interventions.

We report on the nature of multiphoton excited fluorescence observed from human erythrocytes (red blood cells RBC's) and their "ghosts" following 800nm sub-15 fs excitation. The detected optical signal is assigned as two-photon excited fluorescence from hemoglobin. Our findings are supported by wavelength-resolved fluorescence lifetime decay measurements using time-correlated single photon counting system from RBC's, their ghosts as well as in vitro samples of various fluorophores including riboflavin, NADH, NAD(P)H, hemoglobin. We find that low-energy and short-duration pulses allow two-photon imaging of RBC’s, but longer more intense pulses lead to their destruction.

The goal of this study was to investigate the degree to which school-based and nonformal education programs that focus on air quality (AQ) achieved measurable AQ improvements, and whether specific instructional methods were associated with those improvements. We completed a standardized telephone interview with representatives of 54 AQ education programs. Quantitative analysis of these interviews generated three key findings: (1) nearly half (46%) of the programs we studied reported evidence that AQ had actually improved over the course of their projects; (2) most (89%) of the programs we studied took some sort of action to improve AQ; and (3) programs reporting more place-based learning qualities and practices such as service-learning and community partnerships were more likely to report improvements in AQ (r = .40, p

Background: This study explored the feasibility and validity of using brief clinician- and parent-rated measures routinely over 6 months in outpatient child psychiatry. Method: All patients under 18 years of age seen for intake in the Child Psychiatry Clinic from 1 August 2007 through 31 July 2010 were eligible for inclusion in the study. Data were collected at intake for 1033 patients and at 3- and 6-month follow-up. Results: ANOVA for repeated measures showed statistically significant improvements in total and subscale scores on all three measures (Brief Psychiatric Rating Scale for Children, Children’s Global Assessment Scale, and Pediatric Symptom Checklist) at both second and third assessments. Conclusion: The fact that both broadband and narrowband scales showed significant improvements over the first 6 months of care establishes the possibility that these measures could be used in experimental designs studying comparative effectiveness.

Objective Aortic annular erosion is a serious complication of aortic valve endocarditis or previous aortic valve replacement without endocarditis, and its surgical management is challenging. We present the early and midterm results of a technique for left ventricular outflow tract and aortic root reconstruction with a polyester tube graft and translocation of the aortic valve and coronary arteries. Methods A polyester tube graft is placed into the left ventricle and sutured to the left ventricular outflow tract below the area of erosion. The graft is then everted and sutured to a composite graft. Interposition polyester grafts from the coronary arteries are attached to the composite graft above the valve. This technique has been used in 12 cases. All but 1 patient had previously undergone aortic root or aortic valve replacement, and 4 had endocarditis of prosthetic (n = 2) or aortic allograft (n = 2) valves. Results There were no in-hospital deaths. There was 1 early death from pulmonary embolism at 1 postoperative month and 2 late deaths at 15 and 64 postoperative months, both resulting from heart failure. The remaining 9 patients are alive at 3 to 132 postoperative months. Actuarial 5-year survival is 75%. Conclusions Left ventricular outflow tract reconstruction with translocation of the aortic valve and coronary arteries for annular erosion is a useful technique that safely excludes the area of annular erosion and eliminates left ventricular outflow tract obstruction. The procedure can be safely performed with satisfactory early outcomes and 5-year survival.

Arrays of nanowires and nanotubes of bismuth–tellurium (Bi–Te) were fabricated by electrodeposition techniques. Scanning electron microscopy was employed to characterize the morphology of the fabricated BiTe nanowires and nanotubes. The fabricated BiTe nanowire and nanotube arrays are shown to be polycrystalline with no preferred orientation. Wavelength dispersive spectroscopy analysis shows that either p-type (Bi rich) or n-type (Te rich) nanowires or nanotubes can be obtained by changing the electrodeposition potentials. The lamellar thickness of the nanowires and nanotube crystallites were determined using the Scherrer equation and found to be ∼17–24 nm. The Seebeck coefficient measurements at room temperature obtained for the nanowires and nanotubes deposited at −400 mV were +11.5 and +17 μV K−1, respectively, whereas those obtained at −65 mV were −48 and −63 μV K−1, respectively. The electrical resistance measurements indicated that the resistance of the nanowires and nanotubes decreased with increasing temperature, suggesting that these nanostructures behave like semiconductors.

This study addresses gas–liquid two-phase flows in polymer (PMMA) micro-channels with non-molecularly smooth and poorly wetting walls (typical contact angle of 65°) unlike previous studies conducted on highly wetting molecularly smooth materials (e.g., glass/silicon). Four fundamentally different topological flow regimes (Capillary Bubbly, Segmented, Annular, Dry) were identified along with two transitory ones (Segmented/Annular, Annular/Dry) and regime boundaries were identified from the two different test chips. The regime transition boundaries were influenced by the geometry of the two-phase injection, the aspect ratio of the test micro-channels, and potentially the chip material as evidenced from comparisons with the results of previous studies. Three principal Segmented flow sub-regimes (1, 2, and 3) were identified on the basis of quantified topological characteristics, each closely correlated with two-phase flow pressure drop trends. Irregularity of the Segmented regimes and related influencing factors were addressed and discussed. The average bubble length associated with the Segmented flows scaled approximately with a power law of the liquid volumetric flow ratio, which depends on aspect ratio, liquid superficial velocity, and the injection system. A simplified semi-empirical geometric model of gas bubble and liquid plug volumes provided good estimates of liquid plug length for most of the segmented regime cases and for all test-channel aspect ratios. The two-phase flow pressure drop was measured for the square test channels. Each Segmented flow sub-regime was associated with different trends in the pressure drop scaled by the viscous scale. These trends were explained in terms of the quantified flow topology (measured gas bubble and liquid plug lengths) and the number of bubble/plug pairs. Significant quantitative differences were found between the two-phase pressure drop in the polymer micro-channels of this study and those obtained from previous glass/silicon micro-channel studies, indicating that the effect of wall surface properties is important. Pressure drop trends on the capillary scale along gas bubbles extracted from the measurements in square micro-channels indicated a linear dependence on the Capillary number and did not agree with those predicted by highly idealized theory primarily because explicit and implicit assumptions in the theory were not relevant to practical conditions in this study.