Trauma-Induced Coagulopathy: Prevalence and Association with Mortality Persist Twenty Years Later.

INTRODUCTION: A 2003 landmark study identified the prevalence of eTIC at 28% with a strong association with mortality of 8.9%. Over the last 20 years there have been significant advances in both the fundamental understanding of eTIC and therapeutic interventions. METHODS: A retrospective cohort study was performed from 2018-2022 on patients ≥18 using prospectively collected data from two level 1 trauma centers and compared to data from 2003. Demographics, laboratory data and clinical outcomes were obtained. RESULTS: There were 20,107 patients meeting criteria: 65% male, 85% blunt, mean age 54 ± 21 years, median injury severity score (ISS) 10 [10, 18]), 8% of patients were hypotensive on arrival, with an all-cause mortality 6.0%. The prevalence of eTIC remained high at 32% in patients with an abnormal PT and 10% with an abnormal PTT, for an overall combined prevalence of 33.4%. Coagulopathy had a major impact on mortality over all injury severity ranges, with the greatest impact with lower ISS. In a hybrid logistic regression/Classification and Regression Trees analysis, coagulopathy was independently associated with a 2.1-fold increased risk of mortality (95% CI 1.5-2.9); the predictive quality of the model was excellent (AUROC 0.932). CONCLUSION: The presence of eTIC conferred a higher risk of death across all disease severities and was independently associated with a greater risk of death. Biomarkers of coagulopathy associated with eTIC remain strongly predictive of poor outcome despite advances in trauma care.

Deciphering heterogeneous enzymatic surface reactions on xylan using surface plasmon resonance spectroscopy.

Xylans' unique properties make it attractive for a variety of industries, including paper, food, and biochemical production. While for some applications the preservation of its natural structure is crucial, for others the degradation into monosaccharides is essential. For the complete breakdown, the use of several enzymes is required, due to its structural complexity. In fact, the specificity of enzymatically-catalyzed reactions is guided by the surface, limiting or regulating accessibility and serving structurally encoded input guiding the actions of the enzymes. Here, we investigate enzymes at surfaces rich in xylan using surface plasmon resonance spectroscopy. The influence of diffusion and changes in substrate morphology is studied via enzyme surface kinetics simulations, yielding reaction rates and constants. We propose kinetic models, which can be applied to the degradation of multilayer biopolymer films. The most advanced model was verified by its successful application to the degradation of a thin film of polyhydroxybutyrate treated with a polyhydroxybutyrate-depolymerase. The herein derived models can be employed to quantify the degradation kinetics of various enzymes on biopolymers in heterogeneous environments, often prevalent in industrial processes. The identification of key factors influencing reaction rates such as inhibition will contribute to the quantification of intricate dynamics in complex systems.

Atmospheric reduced nitrogen: Sources, transformations, effects, and management.

Human activities have increased atmospheric emissions and deposition of oxidized and reduced forms of nitrogen, but emission control programs have largely focused on oxidized nitrogen. As a result, in many regions of the world emissions of oxidized nitrogen are decreasing while emissions of reduced nitrogen are increasing. Emissions of reduced nitrogen largely originate from livestock waste and fertilizer application, with contributions from transportation sources in urban areas. Observations suggest a discrepancy between trends in emissions and deposition of reduced nitrogen in the U.S., likely due to an underestimate in emissions. In the atmosphere, ammonia reacts with oxides of sulfur and nitrogen to form fine particulate matter that impairs health and visibility and affects climate forcings. Recent reductions in emissions of sulfur and nitrogen oxides have limited partitioning with ammonia, decreasing long-range transport. Continuing research is needed to improve understanding of how shifting emissions alter formation of secondary particulates and patterns of transport and deposition of reactive nitrogen. Satellite remote sensing has potential for monitoring atmospheric concentrations and emissions of ammonia, but there remains a need to maintain and strengthen ground-based measurements and continue development of chemical transport models. Elevated nitrogen deposition has decreased plant and soil microbial biodiversity and altered the biogeochemical function of terrestrial, freshwater, and coastal ecosystems. Further study is needed on differential effects of oxidized versus reduced nitrogen and pathways and timescales of ecosystem recovery from elevated nitrogen deposition. Decreases in deposition of reduced nitrogen could alleviate exceedances of critical loads for terrestrial and freshwater indicators in many U.S. areas. The U.S. Environmental Protection Agency should consider using critical loads as a basis for setting standards to protect public welfare and ecosystems. The U.S. and other countries might look to European experience for approaches to control emissions of reduced nitrogen from agricultural and transportation sectors.Implications: In this Critical Review we synthesize research on effects, air emissions, environmental transformations, and management of reduced forms of nitrogen. Emissions of reduced nitrogen affect human health, the structure and function of ecosystems, and climatic forcings. While emissions of oxidized forms of nitrogen are regulated in the U.S., controls on reduced forms are largely absent. Decreases in emissions of sulfur and nitrogen oxides coupled with increases in ammonia are shifting the gas-particle partitioning of ammonia and decreasing long-range atmospheric transport of reduced nitrogen. Effort is needed to understand, monitor, and manage emissions of reduced nitrogen in a changing environment.

How Resilient is Wood Xylan to Enzymatic Degradation in a Matrix with Kraft Lignin?

Despite the potential of lignocellulose in manufacturing value-added chemicals and biofuels, its efficient biotechnological conversion by enzymatic hydrolysis still poses major challenges. The complex interplay between xylan, cellulose, and lignin in fibrous materials makes it difficult to assess underlying physico- and biochemical mechanisms. Here, we reduce the complexity of the system by creating matrices of cellulose, xylan, and lignin, which consists of a cellulose base layer and xylan/lignin domains. We follow enzymatic degradation using an endoxylanase by high-speed atomic force microscopy and surface plasmon resonance spectroscopy to obtain morphological and kinetic data. Fastest reaction kinetics were observed at low lignin contents, which were related to the different swelling capacities of xylan. We demonstrate that the complex processes taking place at the interfaces of lignin and xylan in the presence of enzymes can be monitored in real time, providing a future platform for observing phenomena relevant to fiber-based systems.

Engineering Saccharomyces cerevisiae for targeted hydrolysis and fermentation of glucuronoxylan through CRISPR/Cas9 genome editing.

BACKGROUND: The abundance of glucuronoxylan (GX) in agricultural and forestry residual side streams positions it as a promising feedstock for microbial conversion into valuable compounds. By engineering strains of the widely employed cell factory Saccharomyces cerevisiae with the ability to directly hydrolyze and ferment GX polymers, we can avoid the need for harsh chemical pretreatments and costly enzymatic hydrolysis steps prior to fermentation. However, for an economically viable bioproduction process, the engineered strains must efficiently express and secrete enzymes that act in synergy to hydrolyze the targeted polymers. RESULTS: The aim of this study was to equip the xylose-fermenting S. cerevisiae strain CEN.PK XXX with xylanolytic enzymes targeting beechwood GX. Using a targeted enzyme approach, we matched hydrolytic enzyme activities to the chemical features of the GX substrate and determined that besides endo-1,4-ß-xylanase and ß-xylosidase activities, α-methyl-glucuronidase activity was of great importance for GX hydrolysis and yeast growth. We also created a library of strains expressing different combinations of enzymes, and screened for yeast strains that could express and secrete the enzymes and metabolize the GX hydrolysis products efficiently. While strains engineered with BmXyn11A xylanase and XylA ß-xylosidase could grow relatively well in beechwood GX, strains further engineered with Agu115 α-methyl-glucuronidase did not display an additional growth benefit, likely due to inefficient expression and secretion of this enzyme. Co-cultures of strains expressing complementary enzymes as well as external enzyme supplementation boosted yeast growth and ethanol fermentation of GX, and ethanol titers reached a maximum of 1.33 g L- 1 after 48 h under oxygen limited condition in bioreactor fermentations. CONCLUSION: This work underscored the importance of identifying an optimal enzyme combination for successful engineering of S. cerevisiae strains that can hydrolyze and assimilate GX. The enzymes must exhibit high and balanced activities, be compatible with the yeast's expression and secretion system, and the nature of the hydrolysis products must be such that they can be taken up and metabolized by the yeast. The engineered strains, particularly when co-cultivated, display robust growth and fermentation of GX, and represent a significant step forward towards a sustainable and cost-effective bioprocessing of GX-rich biomass. They also provide valuable insights for future strain and process development targets.

Short peptides based on the conserved regions of MIEN1 protein exhibit anticancer activity by targeting the MIEN1 signaling pathway.

Migration and invasion enhancer 1 (MIEN1) overexpression characterizes several cancers and facilitates cancer cell migration and invasion. Leveraging conserved immunoreceptor tyrosine-based activation motif and prenylation motifs within MIEN1, we identified potent anticancer peptides. Among them, bioactive peptides LA3IK and RP-7 induced pronounced transcriptomic and protein expression changes at sub-IC50 concentrations. The peptides effectively inhibited genes and proteins driving cancer cell migration, invasion, and epithelial-mesenchymal transition pathways, concurrently suppressing epidermal growth factor-induced nuclear factor kappa B nuclear translocation in metastatic breast cancer cells. Specifically, peptides targeted the same signal transduction pathway initiated by MIEN1. Molecular docking and CD spectra indicated the formation of MIEN1-peptide complexes. The third-positioned isoleucine in LA3IK and CVIL motif in RP-7 were crucial for inhibiting breast cancer cell migration. This is evident from the limited migration inhibition observed when MDA-MB-231 cells were treated with scrambled peptides LA3IK SCR and RP-7 SCR. Additionally, LA3IK and RP-7 effectively suppressed tumor growth in an orthotopic breast cancer model. Notably, mice tolerated high intraperitoneal (ip) peptide doses of 90 mg/Kg well, surpassing significantly lower doses of 5 mg/Kg intravenously (iv) and 30 mg/Kg intraperitoneally (ip) used in both in vivo pharmacokinetic studies and orthotopic mouse model assays. D-isomers of LA3IK and RP-7 showed enhanced anticancer activity compared to their L-isomers. D-LA3IK remained stable in mouse plasma for 24 h with 75% remaining, exhibiting superior pharmacokinetic properties over D/L-RP-7. In summary, our findings mark the first report of short peptides based on MIEN1 protein sequence capable of inhibiting cancer signaling pathways, effectively impeding cancer progression both in vitro and in vivo.

Insights into soft short circuit-based degradation of lithium metal batteries.

The demand for electric vehicles with extended ranges has created a renaissance of interest in replacing the common metal-ion with higher energy-density metal-anode batteries. However, the potential battery safety issues associated with lithium metal must be addressed to enable lithium metal battery chemistries. A considerable performance gap between lithium (Li) symmetric cells and practical Li batteries motivated us to explore the correlation between the shape of voltage traces and degradation. We coupled impedance spectroscopy and operando NMR and used the new approach to show that transient (i.e., soft) shorts form in realistic conditions for battery applications; however, they are typically overlooked, as their electrochemical signatures are often not distinct. The typical rectangular-shaped voltage trace, widely considered ideal, was proven, under the conditions studied here, to be a result of soft shorts. Recoverable soft-shorted cells were demonstrated during a symmetric cell polarisation experiment, defining a new type of critical current density: the current density at which the soft shorts are not reversible. Moreover, we demonstrated that soft shorts, detected via electrochemical impedance spectroscopy (EIS) and validated via operando NMR, are predictive towards the formation of hard shorts, showing the potential use of EIS as a relatively low-cost and non-destructive method for early detection of catastrophic shorts and battery failure while demonstrating the strength of operando NMR as a research tool for metal plating in lithium batteries.

Spiers Memorial Lecture: Lithium air batteries - tracking function and failure.

The lithium-air battery (LAB) is arguably the battery with the highest energy density, but also a battery with significant challenges to be overcome before it can be used commercially in practical devices. Here, we discuss experimental approaches developed by some of the authors to understand the function and failure of lithium-oxygen batteries. For example, experiments in which nuclear magnetic resonance (NMR) spectroscopy was used to quantify dissolved oxygen concentrations and diffusivity are described. 17O magic angle spinning (MAS) NMR spectra of electrodes extracted from batteries at different states of charge (SOC) allowed the electrolyte decomposition products at each stage to be determined. For instance, the formation of Li2CO3 and LiOH in a dimethoxyethane (DME) solvent and their subsequent removal on charging was followed. Redox mediators have been used to chemically reduce oxygen or to chemically oxidise Li2O2 in order to prevent electrode clogging by insulating compounds, which leads to lower capacities and rapid degradation; the studies of these mediators represent an area where NMR and electron paramagnetic resonance (EPR) studies could play a role in unravelling reaction mechanisms. Finally, recently developed coupled in situ NMR and electrochemical impedance spectroscopy (EIS) are used to characterise the charge transport mechanism in lithium symmetric cells and to distinguish between electronic and ionic transport, demonstrating the formation of transient (soft) shorts in common lithium-oxygen electrolytes. More stable solid electrolyte interphases are formed under an oxygen atmosphere, which helps stabilise the lithium anode on cycling.

Political Person-Culture Match and Longevity: The Partisanship-Mortality Link Depends on the Cultural Context.

Recent studies demonstrate that Republicans live longer than Democrats. We examined whether these longevity benefits are universal or culturally varying. Following a person-culture match perspective, we hypothesized that Republicans' longevity benefits occur in Republican, but not in Democratic, states. To test this argument, we conducted two studies among U.S. adults. In preregistered Study 1, we used large survey data (extended U.S. General Social Survey; N = 42,855). In confirmatory Study 2, we analyzed obituaries/biographies of deceased U.S. political partisans (novel data web-scraped from an online cemetery; N = 9,177). Both studies supported the person-culture match perspective with substantial effect sizes. In Republican contexts, up to 50.1% of all Republicans but only 36.3% of all Democrats reached an age of 80 years. In Democratic contexts, there was no such longevity gap. Robustness tests showed that this effect generalizes to political ideology and holds across spatial levels but is limited to persons with strong political convictions.

Correction: Academic global surgical competencies: A modified Delphi consensus study.

[This corrects the article DOI: 10.1371/journal.pgph.0002102.].

Substrate microtopographies induce cellular alignment and affect nuclear force transduction.

Cellular physiology has been mainly studied by using two-dimensional cell culture substrates which lack in vivo-mimicking extracellular environment and interactions. Thus, there is a growing need for more complex model systems in life sciences. Micro-engineered scaffolds have been proven to be a promising tool in understanding the role of physical cues in the co-regulation of cellular functions. These tools allow, for example, probing cell morphology and migration in response to changes in chemo-physical properties of their microenvironment. In order to understand how microtopographical features, what cells encounter in vivo, affect cytoskeletal organization and nuclear mechanics, we used direct laser writing via two-photon polymerization (TPP) to fabricate substrates which contain different surface microtopographies. By combining with advanced high-resolution spectral imaging, we describe how the constructed grid and vertical line microtopographies influence cellular alignment, nuclear morphology and mechanics. Specifically, we found that growing cells on grids larger than 10 × 20 µm2 and on vertical lines increased 3D actin cytoskeleton orientation along the walls of microtopographies and abolished basal actin stress fibers. In concert, the nuclei of these cells were also more aligned, elongated, deformed and less flattened, indicating changes in nuclear force transduction. Importantly, by using fluorescence lifetime imaging microscopy for measuring Förster resonance energy transfer for a genetically encoded nesprin-2 molecular tension sensor, we show that growing cells on these microtopographic substrates induce lower mechanical tension at the nuclear envelope. To conclude, here used substrate microtopographies modulated the cellular mechanics, and affected actin organization and nuclear force transduction.

Academic global surgical competencies: A modified Delphi consensus study.

Academic global surgery is a rapidly growing field that aims to improve access to safe surgical care worldwide. However, no universally accepted competencies exist to inform this developing field. A consensus-based approach, with input from a diverse group of experts, is needed to identify essential competencies that will lead to standardization in this field. A task force was set up using snowball sampling to recruit a broad group of content and context experts in global surgical and perioperative care. A draft set of competencies was revised through the modified Delphi process with two rounds of anonymous input. A threshold of 80% consensus was used to determine whether a competency or sub-competency learning objective was relevant to the skillset needed within academic global surgery and perioperative care. A diverse task force recruited experts from 22 countries to participate in both rounds of the Delphi process. Of the n = 59 respondents completing both rounds of iterative polling, 63% were from low- or middle-income countries. After two rounds of anonymous feedback, participants reached consensus on nine core competencies and 31 sub-competency objectives. The greatest consensus pertained to competency in ethics and professionalism in global surgery (100%) with emphasis on justice, equity, and decolonization across multiple competencies. This Delphi process, with input from experts worldwide, identified nine competencies which can be used to develop standardized academic global surgery and perioperative care curricula worldwide. Further work needs to be done to validate these competencies and establish assessments to ensure that they are taught effectively.

Design of experiments as a tool to guide the preparation of tailor-made activated carbons.

Activated carbon produced from biomass exhibits a high specific surface area due to the natural hierarchical porous structure of the precursor material. To reduce production costs of activated carbon, bio-waste materials receive more and more attention, which has led to a steep increase in the number of publications over the past decade. However, the characteristics of activated carbon are highly dependent on the properties of the precursor material used, making it difficult to draw assumptions about activation conditions for new precursor materials based on published work. Here, we introduce a Design of Experiment methodology with a Central Composite Design to better predict the properties of activated carbons from biomass. As a model precursor, we employ well-defined regenerated cellulose-based fibers which contain 25 wt.% chitosan as intrinsic dehydration catalyst and nitrogen donor. The use of the DoE methodology opens up the possibility to better identify the crucial dependencies between activation temperature and impregnation ratio on the yield, surface morphology, porosity and chemical composition of the activated carbon, independent of the used biomass. The use of DoE yields contour plots, which allows for more facile analysis on correlations between activation conditions and activated carbon properties, thus enabling its tailor-made manufacturing.

Cabazitaxel-Loaded Nanoparticles Reduce the Invasiveness in Metastatic Prostate Cancer Cells: Beyond the Classical Taxane Function.

Bone-metastatic prostate cancer symbolizes the beginning of the later stages of the disease. We designed a cabazitaxel-loaded, poly (lactic-co-glycolic acid) (PLGA) nanoparticle using an emulsion-diffusion-evaporation technique. Bis (sulfosuccinimidyl) suberate (BS3) was non-covalently inserted into the nanoparticle as a linker for the conjugation of a bone-targeting moiety to the outside of the nanoparticle. We hypothesized that the nanoparticles would have the ability to inhibit the epithelial-to-mesenchymal transition (EMT), invasion, and migration in prostate cancer cells. Targeted, cabazitaxel-loaded nanoparticles attenuated the EMT marker, Vimentin, and led to an increased E-cadherin expression. These changes impart epithelial characteristics and inhibit invasive properties in cancer progression. Consequently, progression to distant sites is also mitigated. We observed the reduction of phosphorylated Src at tyrosine 416, along with increased expression of phosphorylated cofilin at serine 3. These changes could affect migration and invasion pathways in cancer cells. Both increased p-120 catenin and inhibition in IL-8 expression were seen in targeted, cabazitaxel-loaded nanoparticles. Overall, our data show that the targeted, cabazitaxel-loaded nanoparticles can act as a promising treatment for metastatic prostate cancer by inhibiting EMT, invasion, and migration, in prostate cancer cells.

Testing three coping strategies for time pressure in categorizations and similarity judgments.

This article compares three psychological mechanisms to make multi-attribute inferences under time pressure in the domains of categorization and similarity judgments. Specifically, we test if people under time pressure attend to fewer object features (attention focus), if they respond less precisely (lower choice sensitivity), or if they simplify a psychological similarity function (simplified similarity). The simpler psychological similarity considers the number of matching features but ignores the actual feature value differences. We conducted three experiments (two of them preregistered) in which we manipulated time pressure: one was a categorization task, which was designed based on optimal experimental design principles, and the other two involved a similarity judgment task. Computational cognitive modeling following an exemplar-similarity framework showed that the behavior of most participants under time pressure is in line with a lower choice sensitivity, this means less precise response selection, especially when people make similarity judgments. We find that the variability of participants' behavior increases with time pressure, to a point where participants are unlikely to make inferences anymore but instead start choosing readily available response options repeatedly. These findings are consistent with related research in other cognitive domains, such as risky choices, and add to growing evidence that time pressure and other forms of cognitive load do not necessarily alter core cognitive processes themselves but rather affect the precision of response selection.

Absorbance-Transmittance Excitation Emission Matrix Method for Quantification of Major Cannabinoids and Corresponding Acids: A Rapid Alternative to Chromatography for Rapid Chemotype Discrimination of Cannabis sativa Varieties.

Background: Phytocannabinoids naturally occur in the cannabis plant (Cannabis sativa), and Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) predominate. There is a need for rapid inexpensive methods to quantify total THC (for statutory definition) and THC-CBD ratio (for classification into three chemotypes). This study explores the capabilities of a spectroscopic technique that combines ultraviolet-visible and fluorescence, absorbance-transmittance excitation emission matrix (A-TEEM). Methods: The A-TEEM technique classifies 49 dry flower extracts into three C. sativa chemotypes, and quantifies the total THC-CBD ratio, using validated gas chromatography (GC)-flame ionization (FID) and High-Performance Liquid Chromatography (HPLC) methods for reference. Multivariate methods used are principal components analysis for a chemotype classification, extreme gradient boost (XGB) discriminant analysis (DA) to classify unknown samples by chemotype, and XGB regression to quantify total THC and CBD content using GC-FID and HPLC data on the same samples. Results: The A-TEEM technique provides robust classification of C. sativa samples, predicting chemotype classification, defined by THC-CBD content, of unknown samples with 100% accuracy. In addition, A-TEEM can quantify total THC and CBD levels relevant to statutory determination, with limit of quantifications (LOQs) of 0.061% (THC) and 0.059% (CBD), and high cross-validation (>0.99) and prediction (>0.99), using a GC-FID method for reference data; and LOQs of 0.026% (THC) and 0.080% (CBD) with high cross-validation (>0.98) and prediction (>0.98), using an HPLC method for reference data. A-TEEM is highly predictive in separately quantifying acid and neutral forms of THC and CBD with HPLC reference data. Conclusions: The A-TEEM technique provides a sensitive method for the qualitative and quantitative characterization of the major cannabinoids in solution, with LOQs comparable with GC-FID and HPLC, and high values of cross-validation and prediction. As a spectroscopic technique, it is rapid, with data acquisition <45 sec per measurement; sample preparation is simple, requiring only solvent extraction. A-TEEM has the sensitivity to resolve and quantify cannabinoids in solution based on their unique spectral characteristics. Discrimination of legal and illegal chemotypes can be rapidly verified using XGB DA, and quantitation of statutory levels of total THC and total CBD comparable with GC-FID and HPLC can be obtained using XBD regression.

The role of the Neuropsychologist across the stages of recovery from acquired brain injury: a summary from the pediatric rehabilitation Neuropsychology collaborative.

Neuropsychologists working in a pediatric neurorehabilitation setting provide care for children and adolescents with acquired brain injuries (ABI) and play a vital role on the interdisciplinary treatment team. This role draws on influences from the field of clinical neuropsychology and its pediatric subspecialty, as well as rehabilitation psychology. This combination of specialties is uniquely suited for working with ABI across the continuum of recovery. ABI recovery often involves a changing picture that spans across stages of recovery (e.g., disorders of consciousness, confusional state, acute cognitive impairment), where each stage presents with distinctive characteristics that warrant a specific evidence-based approach. Assessment and intervention are used reciprocally to inform diagnostics, treatment, and academic planning, and to support patient and family adjustment. Neuropsychologists work with the interdisciplinary teams to collect and integrate data related to brain injury recovery and use this data for treatment planning and clinical decision making. These approaches must often be adapted and adjusted in real time as patients recover, demanding a dynamic expertise that is currently not supported through formal training curriculum or practice guidelines. This paper outlines the roles and responsibilities of pediatric rehabilitation neuropsychologists across the stages of ABI recovery with the goal of increasing awareness in order to continue to develop and formalize this role.

Surface Passivation of III-V GaAs Nanopillars by Low-Frequency Plasma Deposition of Silicon Nitride for Active Nanophotonic Devices.

Numerous efforts have been devoted to improve the electronic and optical properties of III-V compound materials via reduction of their nonradiative states, aiming at highly efficient III-V sub-micrometer active devices and circuits. Despite many advances, the poor reproducibility and short-term passivation effect of chemical treatments, such as sulfidation and nitridation, requires the use of protective encapsulation methods, not only to protect the surface, but also to provide electrical isolation for device manufacturing. There is still a controversial debate on which combination of chemical treatment and capping dielectric layer can best reproducibly protect the crystal surface of III-V materials while being compatible with readily available semiconductor-foundry plasma deposition methods. This work reports on a systematic experimental study on the role of sulfide ammonium chemical treatment followed by dielectric coating (either silicon oxide or nitride) in the passivation effect of GaAs/AlGaAs nanopillars. Our results conclusively show that, under ambient conditions, the best surface passivation is achieved using ammonium sulfide followed by encapsulation with a thin layer of silicon nitride by low-frequency plasma-enhanced chemical deposition. Here, the sulfurized GaAs surfaces, high level of hydrogen ions, and low-frequency (380 kHz) excitation plasma that enable intense bombardment of hydrogen, all seem to provide a combined active role in the passivation mechanism of the pillars by reducing the surface states. As a result, we observe up to a 29-fold increase of the photoluminescence (PL) integrated intensity for the best samples as compared to untreated nanopillars. X-ray photoelectron spectroscopy analysis confirms the best treatments show remarkable removal of gallium and arsenic native oxides. Time-resolved micro-PL measurements display nanosecond lifetimes resulting in a record-low surface recombination velocity of ∼1.1 × 104 cm s-1 for dry-etched GaAs nanopillars. We achieve robust, stable, and long-term passivated nanopillar surfaces, which creates expectations for remarkable high internal quantum efficiency (IQE > 0.5) in nanoscale light-emitting diodes. The enhanced performance paves the way to many other nanostructures and devices such as miniature resonators, lasers, photodetectors, and solar cells, opening remarkable prospects for GaAs active nanophotonic devices.

3D Polymer Architectures for the Identification of Optimal Dimensions for Cellular Growth of 3D Cellular Models.

Organ-on-chips and scaffolds for tissue engineering are vital assay tools for pre-clinical testing and prediction of human response to drugs and toxins, while providing an ethical sound replacement for animal testing. A success criterion for these models is the ability to have structural parameters for optimized performance. Here we show that two-photon polymerization fabrication can create 3D test platforms, where scaffold parameters can be directly analyzed by their effects on cell growth and movement. We design and fabricate a 3D grid structure, consisting of wall structures with niches of various dimensions for probing cell attachment and movement, while providing easy access for fluorescence imaging. The 3D structures are fabricated from bio-compatible polymer SZ2080 and subsequently seeded with A549 lung epithelia cells. The seeded structures are imaged with confocal microscopy, where spectral imaging with linear unmixing is used to separate auto-fluorescence scaffold contribution from the cell fluorescence. The volume of cellular material present in different sections of the structures is analyzed, to study the influence of structural parameters on cell distribution. Furthermore, time-lapse studies are performed to map the relation between scaffold parameters and cell movement. In the future, this kind of differentiated 3D growth platform, could be applied for optimized culture growth, cell differentiation, and advanced cell therapies.

Spectral imaging and nucleic acid mimics fluorescence in situ hybridization (SI-NAM-FISH) for multiplex detection of clinical pathogens.

The application of nucleic acid mimics (NAMs), such as locked nucleic acid (LNA) and 2'-O-methyl-RNA (2'OMe), has improved the performance of fluorescence in situ hybridization (FISH) methods for the detection/location of clinical pathogens since they provide design versatility and thermodynamic control. However, an important limitation of FISH techniques is the low number of distinguishable targets. The use of filters in fluorescence image acquisition limits the number of fluorochromes that can be simultaneously differentiated. Recent advances in fluorescence spectral image acquisition have allowed the unambiguous identification of several microorganisms in a single sample. In this work, we aimed to combine NAM-FISH and spectral image analysis to develop and validate a new FISH variant, the spectral imaging-NAM-FISH (SI-NAM-FISH), that allows a multiplexed, robust and rapid detection of clinical pathogens. In the first stage, to implement/validate the method, we have selected seven fluorochromes with distinct spectral properties and seven bacterial species (Pseudomonas aeruginosa, Citrobacter freundii, Staphylococcus aureus, Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, and Acinetobacter calcoaceticus). As a strong variation in fluorescence intensities is found between species and between fluorochromes, seven versions of a EUB LNA/2'OMe probe, each conjugated to one of seven fluorochromes, were used to rank species/fluorochromes by FISH and then optimize species/fluorochrome pairing. Then, final validation tests were performed using mixed populations to evaluate the potential of the technique for separating/quantifying the different targets. Overall, validation tests with different proportions of bacteria labeled with the respective fluorochrome have shown the ability of the method to correctly distinguish the species.