Building momentum through networks: Bioimaging across the Americas.

In September 2023, the two largest bioimaging networks in the Americas, Latin America Bioimaging (LABI) and BioImaging North America (BINA), came together during a 1-week meeting in Mexico. This meeting provided opportunities for participants to interact closely with decision-makers from imaging core facilities across the Americas. The meeting was held in a hybrid format and attended in-person by imaging scientists from across the Americas, including Canada, the United States, Mexico, Colombia, Peru, Argentina, Chile, Brazil and Uruguay. The aims of the meeting were to discuss progress achieved over the past year, to foster networking and collaborative efforts among members of both communities, to bring together key members of the international imaging community to promote the exchange of experience and expertise, to engage with industry partners, and to establish future directions within each individual network, as well as common goals. This meeting report summarises the discussions exchanged, the achievements shared, and the goals set during the LABIxBINA2023: Bioimaging across the Americas meeting.

Convergence of the dimensional assessment of personality pathology (DAPP-BQ) and the five-factor personality inventory for the international classification of diseases 11th edition (FFiCD) in the context of the five-factor model and personality disorders.

The current manuscript presents the convergence of the Dimensional Assessment of Personality Pathology (DAPP-BQ), using its short form the DAPP-90, and the Five-Factor Personality Inventory for International Classification of Diseases (ICD-11), the FFiCD, in the context of the five-factor personality model and the categorical approach of personality disorders (PDs). The current manuscript compares the predictive validity of both the FFiCD and the DAPP-90 regarding personality disorder scales and clusters. Results demonstrate a very high and meaningful convergence between the DAPP-90 and the FFiCD personality pathology models and a strong alignment with the FFM. The DAPP-90 and the FFiCD also present an almost identical predictive power of PDs. The DAPP-90 accounts for between 18% and 47%, and the FFiCD between 21% and 47% of PDs adjusted variance. It is concluded that both DAPP-90 and FFiCD questionnaires measure strongly similar pathological personality traits that could be described within the frame of the FFM. Additionally, both questionnaires predict a very similar percentage of the variance of personality disorders.

The Alternative Model of Personality Disorders: Assessment, Convergent and Discriminant Validity, and a Look to the Future.

The Alternative Model of Personality Disorders (AMPD) is a dimensional, empirically based diagnostic system developed to overcome the serious limitations of traditional categories. We review the mounting evidence on its convergent and discriminant validity, with an incursion into the less-studied ICD-11 system. In the literature, the AMPD's Pathological Trait Model (Criterion B) shows excellent convergence with normal personality traits, and it could be useful as an organizing framework for mental disorders. In contrast, Personality Functioning (Criterion A) cannot be distinguished from personality traits, lacks both discriminant and incremental validity, and has a shaky theoretical background. We offer some suggestions with a view to the future. These include removing Criterion A, using the real-life consequences of traits as indicators of severity, delving into the dynamic mechanisms underlying traits, and furthering the integration of currently disengaged psychological paradigms that can shape a sounder clinical science. Expected final online publication date for the Annual Review of Clinical Psychology, Volume 20 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Photocatalytic and Photothermal Antimicrobial Mussel-Inspired Nanocomposites for Biomedical Applications.

Bacterial infection has traditionally been treated with antibiotics, but their overuse is leading to the development of antibiotic resistance. This may be mitigated by alternative approaches to prevent or treat bacterial infections without utilization of antibiotics. Among the alternatives is the use of photo-responsive antimicrobial nanoparticles and/or nanocomposites, which present unique properties activated by light. In this study, we explored the combined use of titanium oxide and polydopamine to create nanoparticles with photocatalytic and photothermal antibacterial properties triggered by visible or near-infrared light. Furthermore, as a proof-of-concept, these photo-responsive nanoparticles were combined with mussel-inspired catechol-modified hyaluronic acid hydrogels to form novel light-driven antibacterial nanocomposites. The materials were challenged with models of Gram-negative and Gram-positive bacteria. For visible light, the average percentage killed (PK) was 94.6 for E. coli and 92.3 for S. aureus. For near-infrared light, PK for E. coli reported 52.8 and 99.2 for S. aureus. These results confirm the exciting potential of these nanocomposites to prevent the development of antibiotic resistance and also to open the door for further studies to optimize their composition in order to increase their bactericidal efficacy for biomedical applications.

Anti-Ro52/TRIM21 antibodies are associated with aberrant inflammatory circuits in patients with systemic autoimmune rheumatic diseases.

INTRODUCTION: Anti-Ro52/TRIM21 antibodies are markers for several systemic autoimmune rheumatic diseases (SARD). OBJECTIVE: To assess whether anti-Ro52/TRIM21 antibodies are related to abnormalities in inflammatory circuits. METHODS: Cross-sectional study of consecutive outpatients with SARD. Anti-Ro52/TRIM21 antibodies and serum amyloid A protein were measured by ELISA; panels for 18 cytokines and nine chemokines were analyzed on a Luminex reading platform, while high-sensitivity C-reactive protein (hs-CRP) and complement were measured by nephelometry. RESULTS: Among 167 included patients, 143 had systemic lupus erythematosus (SLE), 16 had primary Sjögren's syndrome and eight had systemic sclerosis; 41 (24%) were positive for anti-Ro52/TRIM21 antibodies. Patients with anti-Ro52/TRIM21 antibodies had higher serum levels of IL-2, IL-4, IL-6, GM-CSF, IL-21, IL-22, hs-CRP and chemokines CCL4, CXCL8, CXCL10 and CXCL12, but lower levels of complement C4. Anti-Ro52/TRIM21 antibody titers were positively correlated with IL-2, IL-4, IL-6, IL-10, IL-21, IL-22, CXCL10, and hs-CRP, and negatively with complements C3 and C4. When only SLE patients were included, no association was identified between anti-Ro52/TRIM21 antibodies and disease activity or organ-specific involvement. CONCLUSIONS: Anti-Ro52/TRIM21 antibodies are associated with aberrant cytokine circuits and elevated levels of angiogenic molecules and neutrophil and monocyte chemoattractants, which suggests an active role for these antibodies in SARD.

INTRODUCCIÓN: Los anticuerpos anti-Ro52/TRIM21 son marcadores de varias enfermedades reumáticas autoinmunes sistémicas (ERAS). OBJETIVO: Evaluar si los anticuerpos anti-Ro52/TRIM21 están relacionados con anomalías en los circuitos inflamatorios. MÉTODOS: Estudio transversal de pacientes consecutivos y ambulatorios con ERAS. Los anticuerpos anti-Ro52/TRIM21 y la proteína amiloide sérica se midieron mediante ELISA; los paneles para 18 citocinas y nueve quimiocinas se analizaron en una plataforma de lectura Luminex; la proteína C reactiva (hs-CRP) y el complemento se midieron mediante nefelometría. RESULTADOS: Se incluyeron 167 pacientes, 143 con lupus eritematoso sistémico (LES), 16 con síndrome de Sjögren primario y ocho con esclerosis sistémica; 41 fueron positivos para anticuerpos anti-Ro52/TRIM21 (24 %). Los pacientes con anticuerpos anti-Ro52/TRIM21 tuvieron niveles séricos más altos de IL-2, IL-4, IL-6, GM-CSF, IL-21, IL-22, hs-CRP y quimiocinas CCL4, CXCL8, CXCL10 y CXCL12; y más bajos de complemento C4. Los títulos de anticuerpos anti-Ro52/TRIM21 correlacionaron positivamente con IL-2, IL-4, IL-6, IL-10, IL-21, IL-22, CXCL10 y hs-CRP; y negativamente con complemento C3 y C4. Al incluir solo LES, no se identificó asociación entre los anticuerpos anti-Ro52/TRIM21 y la actividad de la enfermedad o la afectación específica de órganos. CONCLUSIONES: Los anticuerpos anti-Ro52/TRIM21 se asocian a circuitos aberrantes de citocinas y niveles elevados de moléculas angiogénicas y quimioatrayentes de neutrófilos y monocitos, lo que sugiere un papel activo de esos anticuerpos en las ERAS.

Paternal inflammatory arthritis is associated with a higher risk of miscarriage: results of a large multicentre study (iFAME-Fertility).

OBJECTIVES: Paternal preconception health is recognized as an important contributor to pregnancy outcomes. Nonetheless, pregnancy outcomes of partners of men with inflammatory arthritis (IA) have never been studied. Our objective was to describe the pregnancy outcomes of partners of men diagnosed with IA. METHODS: We performed a multicentre cross-sectional retrospective study conducted in the Netherlands. Men with IA who were over 40 years old that reported at least one positive pregnancy test were included. To analyse the impact of IA on pregnancy outcomes, pregnancies were classified into two groups: pregnancies conceived after the diagnosis of IA and before the diagnosis of IA. RESULTS: In total, 408 male participants diagnosed with IA reported 897 singleton pregnancies that resulted in 794 live births. Pregnancies conceived after the diagnosis of IA had higher rate of miscarriage (12.27 vs 7.53%, P = <0.05). This increased risk was still present after adjusting for confounders [OR 2.03 (95% CI 1.12, 3.69) P = 0.015]. CONCLUSIONS: This is the largest study to describe the pregnancy outcomes of partners of men diagnosed with IA and the first to demonstrate that paternal IA is associated with a higher risk of miscarriage. Notwithstanding, the overall rate of miscarriage reported in our study could be comparable to previously reported population estimates.

Determinants of sexual function in male patients with systemic lupus erythematosus.

OBJECTIVES: Our study aims to describe the association between SLE and sexual function, analysing demographic variables, comorbidities and other disease-related factors. As an exploratory objective, the impact of asking about sexual function during outpatient consultation was evaluated. METHODS: From 2018 to 2019, we invited sexually active men diagnosed with SLE to complete questionnaires that evaluated their sexual function and quality of life. Additionally, patients were asked if they believed they had sexual dysfunction, whether they would be interested in receiving specialized sexual care, and if they considered SLE to be detrimental to their sexual function. Epidemiological and disease-related data were retrieved from the patients' clinical records. RESULTS: We included 124 men with SLE. Twenty-two (18%) patients answered positively when asked if they believed they had sexual dysfunction. These patients had lower overall erectile function scores and lower physical function scores than those who did not consider they had sexual dysfunction. In the multivariable analysis, factors that were associated with better sexual function were high physical function (B = 0.126, p = .031), lower BMI (B = 0.53, p = .010) and the patient's perception of normal sexual function (B = 13.0, p < .001). Comorbidities associated with worse sexual function were type 2 diabetes (B = -8.1, p = .017) and a history of thrombosis (B = -5.12, p = .019). CONCLUSION: Sexual function of male patients with SLE is impaired, independently of disease activity, chronic disease damage or pharmacological treatment. A simple question about perception of sexual function in the outpatient clinic can be used to help determine which patients could benefit from a multidisciplinary intervention to improve sexual health.

Determination of association equilibrium constant from single molecule fluorescence localization microscopy.

Single molecule fluorescence localization microscopy provides molecular localization with a precision in the tens of nanometer range in the plane perpendicular to the light propagation. This opens the possibility to count molecules and correlate their locations, starting from a map of the actual positions in a single molecule super resolution image. Considering molecular pair correlation as an indication of interaction, and a way to discern them from free molecules, we describe a method to calculate thermodynamic equilibrium constants. In this work, we use as a test system two complementary homo-oligonucleotides, one strand marked with Cyanine 3.5 and the other with Alexa Fluor 647. Hybridization is controlled by the amount of each strand, temperature, and the ionic force, and measured in steady state emission. The same samples are examined in Stochastic Optical Reconstruction Microscopy (STORM) experiments with split-field simultaneous two-colour detection. The effect of multiblinking, labelling-detection efficiency, and determination of the critical distance for association are discussed. We consistently determine values in STORM coincident with those of the bulk experiment.

Exploring the stability of HEXACO-60 structure and the association of gender, age, and social position with personality traits across 18 countries.

OBJECTIVES: The present paper tests the cross-national stability of the HEXACO-60 structure across 18 countries from four continents. Gender and age differences across countries will be examined. Finally, this is the first study to explicitly analyze the relationships between the HEXACO and social position. METHOD: Ten thousand two hundred and ninety eight subjects (5,410 women and 4,888 men) from 18 countries and 13 languages were analyzed. Confirmatory factor analysis techniques were used to test configural, metric and scalar invariance models. Congruence coefficients with the original structure of the HEXACO-60 were computed for every culture. Effect sizes of gender, age, and social position factors across countries were also computed. RESULTS: HEXACO-60 demonstrates configural and metric invariance, but not scalar invariance. Congruence coefficients show a great equivalence in almost all countries and factors. Only Emotionality presents a large gender difference across countries. No relevant effect of age is observed. A profile of high scores on Honesty-Humility, Extraversion, Conscientiousness, and Openness to Experience, and low scores on Emotionality increases the likelihood of achieving a higher social position, although the effect sizes are small. CONCLUSIONS: HEXACO-60 is a useful instrument to conduct personality trait research and practice around the world. Implications of gender, social position, and country differences are discussed.

Systemic lupus erythematosus and COVID-19 during pregnancy.

Background: The ongoing corona virus disease 2019 (COVID-19) pandemic is having a worldwide impact. Valuable information on the clinical characteristics of COVID-19 in pregnant patients with an autoimmune disease, such as systemic lupus erythematosus (SLE), is currently lacking. Methods: Herein, we describe the clinical presentation of 2 pregnant patients with SLE and mild symptomatic COVID-19 infection. Results: In both pregnant SLE patients, a watchful-waiting approach without initiation of treatment for COVID-19 was taken. No adverse outcomes were reported and both pregnancies resulted in healthy neonates born at term. In one patient we observed a flare in SLE disease activity, most likely attributed to discontinuing SLE treatment. Conclusion: Our report highlights the importance of multidisciplinary collaboration between health care professionals as well as individualized treatment decisions during unprecedented periods such as the current COVID-19 pandemic. Discontinuation of immunosuppressive drugs during the acute phase of a COVID-19 infection should be considered on a case-by-case basis. Maternal treatment decisions should be in line with current recommendations for treatment of rheumatic and musculoskeletal diseases during COVID-19 infection and in line with treatment of COVID- 19 during pregnancy.

FREQUENCY OF DEPRESSION AND ANXIETY SYMPTOMS IN MEXICAN PATIENTS WITH RHEUMATIC DISEASES DETERMINED BY SELF-ADMINISTERED QUESTIONNAIRES ADAPTED TO THE SPANISH LANGUAGE.

BACKGROUND: The frequency of depression and anxiety symptoms in Spanish-speaking patients suffering from rheumatic conditions is unknown when using self-administered detection tools. METHODS: A single-center, cross-sectional survey including 413 patients (341 women) with well-defined rheumatic diseases was conducted. The patient health questionnaire-9 (PHQ-9) and generalized anxiety disorder (GAD)-7 questionnaires were used to detect depression and anxiety symptoms, respectively. RESULTS: A total of 193 patients (46.7%) reported depression symptoms, and increased PHQ-9 scores were more frequently observed in women than in men (23% vs. 13%; p = 0.038), particularly in association with osteoarthritis, fibromyalgia, Sjögren's syndrome, and osteoporosis. From 88 patients (21.3%) with PHQ-9 scores ≥ 10 points (moderate-to-severe depression symptoms), 27 (30.6%) were previously diagnosed to have depression and only four were under antidepressant treatment. Anxiety symptoms were observed in 168 patients (40.6%) and classified as moderate-to-severe by elevated GAD-7 scores in 68 subjects (16.4%). Of them, 12 (17.6%) were previously diagnosed with GAD, but only 4 (5.8%) were under therapy. CONCLUSIONS: An unexpected and unusually high frequency of undiagnosed depression and anxiety symptoms was found in rheumatic patients. Self-administered screening tools adapted to the Spanish language are useful and may help clinicians to suspect these conditions.

Visualization of internal in situ cell structure by atomic force microscopy.

Light and electron microscopy have been used to study cell structure for many years, but atomic force microscopy is a more recent technique used to analyze cells, mainly due to the absence of techniques to prepare the samples. Isolated molecules or organelles, whole cells, and to a lesser extent in situ cell structure have been observed by different atomic force microscopy imaging modes. Here, we review efforts intended to analyze in situ the cell structures using approaches involving imaging of the surface of semithin sections of samples embedded in resin and sections prepared with an ultramicrotome. The results of such studies are discussed in relation to their implications to analyze the fine structure of organelles at the nanoscale in situ at enhanced resolution compared to light microscopy.

Web building and silk properties functionally covary among species of wolf spider.

Although phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally covary or just vary across environments that the spiders occupy. As MaSp2-like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non-web building, but a select few species build webs. We accordingly collected MA silk from two web-building and six non-web-building species found in semirural ecosystems in Uruguay to test whether the presence of MaSp2-like proteins (indicated by amino acid composition, silk mechanical properties and silk nanostructures) was associated with web building across the group. The web-building and non-web-building species were from disparate subfamilies so we estimated a genetic phylogeny to perform appropriate comparisons. For all of the properties measured, we found differences between web-building and non-web-building species. A phylogenetic regression model confirmed that web building and not phylogenetic inertia influences silk properties. Our study definitively showed an ecological influence over spider silk properties. We expect that the presence of the MaSp2-like proteins and the subsequent nanostructures improves the mechanical performance of silks within the webs. Our study furthers our understanding of spider web and silk co-evolution and the ecological implications of spider silk properties.

Reconstructing Native American population history.

The peopling of the Americas has been the subject of extensive genetic, archaeological and linguistic research; however, central questions remain unresolved. One contentious issue is whether the settlement occurred by means of a single migration or multiple streams of migration from Siberia. The pattern of dispersals within the Americas is also poorly understood. To address these questions at a higher resolution than was previously possible, we assembled data from 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. Here we show that Native Americans descend from at least three streams of Asian gene flow. Most descend entirely from a single ancestral population that we call 'First American'. However, speakers of Eskimo-Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream. We show that the initial peopling followed a southward expansion facilitated by the coast, with sequential population splits and little gene flow after divergence, especially in South America. A major exception is in Chibchan speakers on both sides of the Panama isthmus, who have ancestry from both North and South America.

Two new species of Phyllonema (Rivulariaceae, Cyanobacteria) with an emendation of the genus.

Two untapered, heterocytous species were observed and collected from the intertidal and supratidal zones of the Mexican coastline of the Pacific Ocean near Oaxaca and from the Gulf of Mexico. These populations were highly similar in morphology to the freshwater taxon Petalonema incrustans in the Scytonemataceae. However, 16S rRNA sequence data and phylogenetic analysis indicated that they were sister taxa to the epiphyllic, Brazilian species Phyllonema aveceniicola in the Rivulariaceae, described from culture material. While genetic identity between the two new species was high, they differed significantly in morphology, 16S rRNA gene sequence identity, and sequence and structure of the 16S-23S ITS region. Their morphology differed markedly from the generitype of the previously monotypic Phyllonema, which has tapered, heteropolar, single-false branched trichomes with very thin or absent sheath. The two new species, Phyllonema ansata and Phyllonema tangolundensis, described from both culture and environmental material, have untapered, isopolar, geminately false branched trichomes with thick, lamellated sheaths, differences so significant that the species would not be placed in Phyllonema without molecular corroboration. The morphological differences are so significant that a formal emendation of the genus is required. These taxa provide a challenge to algal taxonomy because the morphological differences are such that one would logically conclude that they represent different genera, but the phylogenetic evidence for including them all in the same genus is conclusive. This conclusion is counter to the current trend in algal taxonomy in which taxa with minor morphological differences have been repeatedly placed in separate genera based primarily upon DNA sequence evidence.

3D printed multiplexed electrospinning sources for large-scale production of aligned nanofiber mats with small diameter spread.

We report the design, fabrication, and characterization of novel, low-cost, and modular miniaturized nanofiber electrospinning sources for the scalable production of non-woven aligned nanofiber mats with low diameter variation. The devices are monolithic arrays of electrospinning emitters made via stereolithography; the emitters are arranged so each element has an independent line of sight to a rotating collector surface. Linear and zigzag emitter packing were evaluated using a PEO solution with the aim of maximizing the throughput of nanofibers with the smallest diameter and narrowest distribution. Current versus flowrate characterization of the devices showed that for a given flowrate a zigzag array produces more current per emitter than a linear array of the same emitter pitch and array size. In addition, the data demonstrate that larger and denser arrays have a net gain in flow rate per unit of active length. Visual inspection of the devices suggests uniform operation in devices with as many as 17 emitters with 300 µm inner diameter and 1.5 mm emitter gap. Well-aligned nanofiber mats were collected on a rotating drum and characterized; the 17-emitter device produced the same narrow nanofiber distribution (∼81 nm average diameter, ∼17 nm standard deviation) for all tested flow rates, which is strikingly different to the performance shown by 1-emitter sources where the average fiber diameter significantly increased and the statistics notably widened when the flowrate increases. Therefore, the data demonstrate that massively multiplexing the emitters is a viable approach to greatly increase the throughput of non-woven aligned nanofiber mats without sacrificing the statistics of the nanofibers generated. The production of dry nanofibers by the 17-emitter array is estimated at 33.0 mg min-1 (1.38 mg min-1 per mm of active length), which compares favorably with the reported multiplexed electrospinning arrays with emitters distributed along a line.

Estimating Diversity of Black Flies in the Simulium ignescens and Simulium tunja Complexes in Colombia: Chromosomal Rearrangements as the Core of Integrative Taxonomy.

Black flies (Diptera: Simuliidae) are distributed throughout the world, with more than 2200 formally described species. The family is renowned for its high frequency of cryptic species, offering an opportunity for integrative taxonomy, based on morphological, chromosomal, and molecular approaches. The biodiversity within Simulium (Psilopelmia) ignescens and S. (Psilopelmia) tunja in Colombia was estimated from the larval stage; 10 morphoforms were recognized based on 7 structural characters. This remarkable morphological variation was evaluated through 23 markers on the polytene chromosomes. We established 1 new cytoform in each nominal species. The congruence of the morphological and chromosomal assignments was evaluated using the mitochondrial marker Cytochrome Oxidase subunit I (COI) for each morphoform. The molecular data supported the chromosomal recognition of cytoforms (i.e., cryptic species). We also established the suitability of the COI marker for linking the pupal stage with each cytoform. Our results reveal the presence of hidden biodiversity in S. ignescens and S. tunja and demonstrate the power of polytene chromosomes as a tool for evaluating simuliid diversity, while illustrating the importance of integrated analyses in modern taxonomy.

Nucleologenesis in Trypanosoma cruzi.

Nucleolar assembly is a cellular event that requires the synthesis and processing of ribosomal RNA, in addition to the participation of pre-nucleolar bodies (PNBs) at the end of mitosis. In mammals and plants, nucleolar biogenesis has been described in detail, but in unicellular eukaryotes it is a poorly understood process. In this study, we used light and electron microscopy cytochemical techniques to investigate the distribution of nucleolar components in the pathway of nucleolus rebuilding during closed cell division in epimastigotes of Trypanosoma cruzi, the etiologic agent of American trypanosomiasis. Silver impregnation specific for nucleolar organizer regions and an ethylenediaminetetraacetic acid regressive procedure to preferentially stain ribonucleoprotein revealed the conservation and dispersion of nucleolar material throughout the nucleoplasm during cell division. Furthermore, at the end of mitosis, the argyrophilic proteins were concentrated in the nucleolar organizer region. Unexpectedly, accumulation of nucleolar material in the form of PNBs was not visualized. We suggest that formation of the nucleolus in epimastigotes of T. cruzi occurs by a process that does not require the concentration of nucleolar material within intermediate nuclear bodies such as mammalian and plant PNBs.

Electrospray-printed nanostructured graphene oxide gas sensors.

We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors' response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%-60% relative humidity range while consuming <6 µW. Devices with GO layers printed by different deposition recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ∼5 × 10(-4) T) at ∼1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems.

Parallel nanomanufacturing via electrohydrodynamic jetting from microfabricated externally-fed emitter arrays.

We report the design, fabrication, and characterization of planar arrays of externally-fed silicon electrospinning emitters for high-throughput generation of polymer nanofibers. Arrays with as many as 225 emitters and with emitter density as large as 100 emitters cm(-2) were characterized using a solution of dissolved PEO in water and ethanol. Devices with emitter density as high as 25 emitters cm(-2) deposit uniform imprints comprising fibers with diameters on the order of a few hundred nanometers. Mass flux rates as high as 417 g hr(-1) m(-2) were measured, i.e., four times the reported production rate of the leading commercial free-surface electrospinning sources. Throughput increases with increasing array size at constant emitter density, suggesting the design can be scaled up with no loss of productivity. Devices with emitter density equal to 100 emitters cm(-2) fail to generate fibers but uniformly generate electrosprayed droplets. For the arrays tested, the largest measured mass flux resulted from arrays with larger emitter separation operating at larger bias voltages, indicating the strong influence of electrical field enhancement on the performance of the devices. Incorporation of a ground electrode surrounding the array tips helps equalize the emitter field enhancement across the array as well as control the spread of the imprints over larger distances.