Fluids and Electrolytes under Confinement in Single-Digit Nanopores

Confined fluids and electrolyte solutions in nanopores exhibit rich and surprising physics and chemistry that impact the mass transport and energy efficiency in many important natural systems and industrial applications. Existing theories often fail to predict the exotic effects observed in the narrowest of such pores, called single-digit nanopores (SDNs), which have diameters or conduit widths of less than 10 nm, and have only recently become accessible for experimental measurements. What SDNs reveal has been surprising, including a rapidly increasing number of examples such as extraordinarily fast water transport, distorted fluid-phase boundaries, strong ion-correlation and quantum effects, and dielectric anomalies that are not observed in larger pores. Exploiting these effects presents myriad opportunities in both basic and applied research that stand to impact a host of new technologies at the water-energy nexus, from new membranes for precise separations and water purification to new gas permeable materials for water electrolyzers and energy-storage devices. SDNs also present unique opportunities to achieve ultrasensitive and selective chemical sensing at the single-ion and single-molecule limit. In this review article, we summarize the progress on nanofluidics of SDNs, with a focus on the confinement effects that arise in these extremely narrow nanopores. The recent development of precision model systems, transformative experimental tools, and multiscale theories that have played enabling roles in advancing this frontier are reviewed. We also identify new knowledge gaps in our understanding of nanofluidic transport and provide an outlook for the future challenges and opportunities at this rapidly advancing frontier.

Observation and Isochoric Thermodynamic Analysis of Partially Water-Filled 1.32 and 1.45 nm Diameter Carbon Nanotubes

Recent measurements of fluids under extreme confinement, including water within narrow carbon nanotubes, exhibit marked deviations from continuum theoretical descriptions. In this work, we generate precise carbon nanotube replicates that are filled with water, closed from external mass transfer, and studied over a wide temperature range by Raman spectroscopy. We study segments that are empty, partially filled, and completely filled with condensed water from -80 to 120 °C. Partially filled, nanodroplet states contain submicron vapor-like and liquid-like domains and are analyzed using a Clausius-Clapeyron-type model, yielding heats of condensation of water inside closed 1.32 nm diameter carbon nanotubes (3.32 ± 0.10 kJ/mol and 3.72 ± 0.11 kJ/mol) and 1.45 nm diameter carbon nanotubes (3.50 ± 0.07 kJ/mol) that are lower than the bulk enthalpy of vaporization and closer to the bulk enthalpy of fusion. Favored partial filling fractions are calculated, highlighting the effect of subnanometer changes in confining diameter on fluid properties and suggesting the promise of molecular engineering of nanoconfined liquid/vapor interfaces for water treatment or membrane distillation.

Discretized hexagonal boron nitride quantum emitters and their chemical interconversion

Quantum emitters in two-dimensional hexagonal boron nitride (hBN) are of significant interest because of their unique photophysical properties, such as single-photon emission at room temperature, and promising applications in quantum computing and communications. The photoemission from hBN defects covers a wide range of emission energies but identifying and modulating the properties of specific emitters remain challenging due to uncontrolled formation of hBN defects. In this study, more than 2000 spectra are collected consisting of single, isolated zero-phonon lines (ZPLs) between 1.59 and 2.25 eV from diverse sample types. Most of ZPLs are organized into seven discretized emission energies. All emitters exhibit a range of lifetimes from 1 to 6 ns, and phonon sidebands offset by the dominant lattice phonon in hBN near 1370 cm^-1. Two chemical processing schemes are developed based on water and boric acid etching that generate or preferentially interconvert specific emitters, respectively. The identification and chemical interconversion of these discretized emitters should significantly advance the understanding of solid-state chemistry and photophysics of hBN quantum emission.

ODAS: Open embeddeD Audition System

Artificial audition aims at providing hearing capabilities to machines, computers and robots. Existing frameworks in robot audition offer interesting sound source localization, tracking and separation performance, although involve a significant amount of computations that limit their use on robots with embedded computing capabilities. This paper presents ODAS, the Open embeddeD Audition System framework, which includes strategies to reduce the computational load and perform robot audition tasks on low-cost embedded computing systems. It presents key features of ODAS, along with cases illustrating its uses in different robots and artificial audition applications.

Direct Chemical Vapor Deposition Synthesis of Porous Single-Layer Graphene Membranes with High Gas Permeances and Selectivities

Single-layer graphene containing molecular-sized in-plane pores is regarded as a promising membrane material for high-performance gas separations due to its atomic thickness and low gas transport resistance. However, typical etching-based pore generation methods cannot decouple pore nucleation and pore growth, resulting in a trade-off between high areal pore density and high selectivity. In contrast, intrinsic pores in graphene formed during chemical vapor deposition are not created by etching. Therefore, intrinsically porous graphene can exhibit high pore density while maintaining its gas selectivity. In this work, the density of intrinsic graphene pores is systematically controlled for the first time, while appropriate pore sizes for gas sieving are precisely maintained. As a result, single-layer graphene membranes with the highest H₂ /CH₄ separation performances recorded to date (H₂ permeance > 4000 GPU and H₂ /CH₄ selectivity > 2000) are fabricated by manipulating growth temperature, precursor concentration, and non-covalent decoration of the graphene surface. Moreover, it is identified that nanoscale molecular fouling of the graphene surface during gas separation where graphene pores are partially blocked by hydrocarbon contaminants under experimental conditions, controls both selectivity and temperature dependent permeance. Overall, the direct synthesis of porous single-layer graphene exploits its tremendous potential as high-performance gas-sieving membranes.

A virucidal face mask based on the reverse-flow reactor concept for thermal inactivation of SARS-CoV-2

While facial coverings reduce the spread of SARS-CoV-2 by viral filtration, masks capable of viral inactivation by heating can provide a complementary method to limit transmission. Inspired by reverse-flow chemical reactors, we introduce a new virucidal face mask concept driven by the oscillatory flow of human breath. The governing heat and mass transport equations are solved to evaluate virus and CO₂ transport. Given limits imposed by the kinetics of SARS-CoV-2 thermal inactivation, human breath, safety, and comfort, heated masks may inactivate SARS-CoV-2 to medical-grade sterility. We detail one design, with a volume of 300 ml at 90°C that achieves a 3-log reduction in viral load with minimal impedance within the mask mesh, with partition coefficient around 2. This is the first quantitative analysis of virucidal thermal inactivation within a protective face mask, and addresses a pressing need for new approaches for personal protective equipment during a global pandemic.

Diameter Dependence of Water Filling in Lithographically Segmented Isolated Carbon Nanotubes

Although the structure and properties of water under conditions of extreme confinement are fundamentally important for a variety of applications, they remain poorly understood, especially for dimensions less than 2 nm. This problem is confounded by the difficulty in controlling surface roughness and dimensionality in fabricated nanochannels, contributing to a dearth of experimental platforms capable of carrying out the necessary precision measurements. In this work, we utilize an experimental platform based on the interior of lithographically segmented, isolated single-walled carbon nanotubes to study water under extreme nanoscale confinement. This platform generates multiple copies of nanotubes with identical chirality, of diameters from 0.8 to 2.5 nm and lengths spanning 6 to 160 μm, that can be studied individually in real time before and after opening, exposure to water, and subsequent water filling. We demonstrate that, under controlled conditions, the diameter-dependent blue shift of the Raman radial breathing mode (RBM) between 1 and 8 cm^-1 measures an increase in the interior mechanical modulus associated with liquid water filling, with no response from exterior water exposure. The observed RBM shift with filling demonstrates a non-monotonic trend with diameter, supporting the assignment of a minimum of 1.81 ± 0.09 cm^-1 at 0.93 ± 0.08 nm with a nearly linear increase at larger diameters. We find that a simple hard-sphere model of water in the confined nanotube interior describes key features of the diameter-dependent modulus change of the carbon nanotube and supports previous observations in the literature. Longer segments of 160 μm show partial filling from their ends, consistent with pore clogging. These devices provide an opportunity to study fluid behavior under extreme confinement with high precision and repeatability.

Mobility and transformation of CdSe/ZnS quantum dots in soil: Role of the capping ligands and ageing effect

The increasing application of Quantum Dots (QDs) is cause of concern for the potential negative effects for the ecosystem, especially in soils that may act as a sink. In this study, soil leaching experiments were performed in quartz sand packed columns to investigate the behavior of core-shell CdSe/ZnS QDs coated with either small ligands (TGA-QDs) or more complex polymers (POAMA-QDs). Fluorescence emission was compared to mass spectrometric measurements to assess the nanoparticles (NPs) state in both the leachate (transported species) and porous media (deposited amounts). Although both QDs were strongly retained in the column, large differences were observed depending on their capping ligand stability. Specifically, for TGA-QDs elution was negligible and the retained fraction accumulated in the top-columns. Furthermore, 74% of the NPs were degraded and 38% of the Se was found in the leachate in non-NPs state. Conversely, POAMA-QDs were recovered to a larger extent (78.1%), and displayed a higher transport along the soil profile. Further experiments with altered NPs showed that homo-aggregation of the QDs prior injection determined a reduced mobility but no significant changes in their stability. Eventually, ageing of the NPs in the column (15 days) caused the disruption of up to 92% of the original QDs and the immobilization of NPs and metals. These results indicate that QDs will accumulate in top-soils, where transformations phenomena will determine the overall transport, persistency and degradation of these chemicals. Once accumulated, they may act as a source for potentially toxic Cd and Se metal species displaying enhanced mobility.

Combination of Optimization and Metalated-Ligand Exchange: An Effective Approach to Functionalize UiO-66(Zr) MOFs for CO2 Separation

The strategy to functionalize water-stable metal-organic frameworks (MOFs) in order to improve their CO2 uptake capacities for efficient CO2 separation remains limited and challenging. We herein present an effective approach to functionalize a prominent water-stable MOF, UiO-66(Zr), by a combination of optimization and metalated-ligand exchange. In particular, by systematic optimization, we have successfully obtained UiO-66(Zr) of the highest BET surface area reported so far (1730 m(2)  g(-1) ). Moreover, it shows a hybrid Type I/IV N2 isotherm at 77 K and a mesopore size of 3.9 nm for the first time. The UiO-66 MOF underwent a metalated-ligand-exchange (MLE) process to yield a series of new UiO-66-type MOFs, among which UiO-66-(COONa)2 -EX and UiO-66-(COOLi)4 -EX MOFs have both enhanced CO2 working capacity and IAST CO2 /N2 selectivity. Our approach has thus suggested an alternative design to achieve water-stable MOFs with high crystallinity and gas uptake for efficient CO2 separation.

Statistical distance as a measure of physiological dysregulation is largely robust to variation in its biomarker composition

Physiological dysregulation may underlie aging and many chronic diseases, but is challenging to quantify because of the complexity of the underlying systems. Recently, we described a measure of physiological dysregulation, D_M, that uses statistical distance to assess the degree to which an individual’s biomarker profile is normal versus aberrant. However, the sensitivity of D_M to details of the calculation method has not yet been systematically assessed. In particular, the number and choice of biomarkers and the definition of the reference population (RP, the population used to define a “normal” profile) may be important. Here, we address this question by validating the method on 44 common clinical biomarkers from three longitudinal cohort studies and one cross-sectional survey. D_Ms calculated on different biomarker subsets show that while the signal of physiological dysregulation increases with the number of biomarkers included, the value of additional markers diminishes as more are added and inclusion of 10-15 is generally sufficient. As long as enough markers are included, individual markers have little effect on the final metric, and even D_Ms calculated from mutually exclusive groups of markers correlate with each other at r~0.4-0.5. We also used data subsets to generate thousands of combinations of study populations and RPs to address sensitivity to differences in age range, sex, race, data set, sample size, and their interactions. Results were largely consistent (but not identical) regardless of the choice of RP; however, the signal was generally clearer with a younger and healthier RP, and RPs too different from the study population performed poorly. Accordingly, biomarker and RP choice are not particularly important in most cases, but caution should be used across very different populations or for fine-scale analyses. Biologically, the lack of sensitivity to marker choice and better performance of younger, healthier RPs confirm an interpretation of D_M physiological dysregulation and as an emergent property of a complex system.

Family history of anxiety and mood disorders in anorexia nervosa: review of the literature

OBJECTIVE

To provide a critical review of the research on mood and anxiety disorders in relatives of individuals with anorexia nervosa (AN). In the first section, we explore methodological issues with these studies. In the second section, we present results.

METHOD

A Medline search identified studies published on family history of mood and anxiety disorders in AN, and was complemented by a manual search. Only studies from 1980 to 2006 using strict diagnostic criteria for the disorders were included [Feighner and Halmi criteria for AN, Reasearch Diagnostic Criteria (RDC), Diagnostic and Statistical Manual of Mental Disorders - Third Edition - Revised (DSM-III-R) or DSM - Fourth Edition (DSM-IV) for anorexia and other disorders].

RESULTS

A review of the research methods used in the studies revealed a number of methodological problems. Therefore, we provide only a description of the prevalence of mood and anxiety disorders in relatives of individuals with AN.

CONCLUSIONS

In the light of the methodological issues uncovered, the value of the results of these studies and their implications for further study are considered.

[Mood and anxiety disorders in relatives of anorexia nervosa patients: a review]

In the literature, no review concerning the family comorbidity of mood and anxiety disorders of anorexic subjects exists. However, this data can be important for the comprehension of this disorder and for the assumption of responsibility.

OBJECTIVE

We conducted a critical literature review on studies assessing the prevalence of anxiety disorders (AD) and mood disorders in relatives of anorexia nervosa (AN) subjects. In the first part, we discuss methodological issues relevant to these comorbidity studies. In the second part, taking into account the methodological considerations raised, we summarise the findings of these studies.

METHOD

We performed a manual and computerised search (Medline) for all published studies on the frequency of MD and AD in AN relatives and MD or AD, limiting our search to the 1980-2002 period, in order to get sufficiently homogeneous diagnostic criteria for both categories of disorders (most often RDC, DSM III, DSM III-R, or DSM IV criteria).

RESULTS

We review methodological issues regarding population sources, general methodological procedures, diagnostic criteria for AN, MD and AD, diagnostic instruments, age of subjects and course of the eating disorder.

DISCUSSION

We discuss the results taking into account the methodological problems observed. We give implications for reviewing the results of published studies and planning future research.

[On the subject of the cyclic vomiting syndrome]

The cyclic vomiting syndrome is defined by episodes of vomiting lasting from hours to days with free intervals between episodes. Various symptoms can be associated with vomiting: nausea, abdominal pain, photophobia, fever, pallor, dehydratation, excess salivation, social withdrawal. Some factors often precipitate the crisis: infection, psychological stresses, menstruation. Excluding a medical condition, especially a gastro-intestinal or a neurological disease is compulsory for the diagnostic of cyclic vomiting syndrome. The cyclic vomiting syndrome shares many common features with migraine including treatment. Due to negative paraclinical testing, a psychiatric disease is often suspected in these children. Pathophysiology of cyclic vomiting syndrome is unknown. As for migraine, mitochondrial and ionic channels abnormalities are thought to play a role. Overactivation of hypothalamic-pituitary-adrenal axis and autonomic dysfunction seem to be involved too. Three clinical vignets will illustrate these aspects.

Impact of unified procedures as implemented in the Canadian Quality Assurance Program for T lymphocyte subset enumeration. Participating Flow Cytometry Laboratories of the Canadian Clinical Trials Network for HIV/AIDS Therapies

The objective of the Canadian Quality Assurance Program (CQAP) is to provide the most reproducible and accurate T-cell subset enumeration for individuals living with HIV who are enrolled in the Canadian Clinical Trial Network for Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) Therapies (abbreviated as CTN). The Canadian National Laboratory for Analytical Cytology, within the Laboratory Centre for Disease Control, is part of the Health Protection Branch of Health Canada. For the past eight years, the Laboratory for Analytical Cytology has been responsible for delivering a bilingual quality assurance program for CD4 T-cell enumeration. This federal program, which integrates biotechnology transfer with quality assessment, was achieved through the organization of workshops focused on technology transfer and essential skill-building techniques. Two training sessions were conducted for the CTN flow cytometer operators. The first introduced the concept of window of analysis, to demonstrate the practical benefits of unified quantitative fluorescent measurement. As a follow-up to the first workshop, participants performed a series of quantitative assays that monitored the expression of CD69, an early activation marker. This quantitative fluorescence protocol was performed with acceptable inter-laboratory variation using modified commercial kits. The second workshop focused on a absolute count method based on a single platform. Four preserved whole-blood preparations were tested with this approach. The combined effort reduced inter-laboratory variation. The direct impact was monitored as related to the frequency of participation. Over the years, the standard deviation of average accumulated variation decreased dramatically with increased frequency of participation, from 10% to <4%.

Monoclonal idiotypic and anti-idiotypic antibodies to human immunodeficiency virus type 1 envelope glycoprotein

Murine monoclonal antibodies (MAbs) gp41-1 (IgG2a) and gp41-2 (IgG1), directed against the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1), were produced and characterized. These MAbs recognized both gp160 and gp41 and reacted with divergent HIV-1 isolates. Surface binding assays using viable HIV-infected cells indicated that these MAbs were directed against surface-exposed epitopes. Both MAbs caused a reduction in reverse transcriptase activity. Syngeneic monoclonal antiidiotypic antibodies (anti-ids) against gp41-1 were also generated. Six anti-ids (agp41-11 to agp41-16) were selected by ELISA using F(ab')2 fragments of gp41-1; no reaction was observed when fragments from an irrelevant IgG2a MAb were used. Anti-ids were recognized by both gp41-1 and gp41-2 biotinylated MAbs. Competitive ELISA studies suggested that anti-ids were directed against at least three distinct idiotopes on gp41-1. All anti-ids reacted with idiotopes associated with both heavy and light chains and not with separated chains. The binding of MAbs gp41-1 and gp41-2 to HIV-infected cells was inhibited by each anti-id, except for the binding of gp41-2 which was not affected by the presence of agp41-12. Immunization of rabbits with agp41-11 and agp41-13 resulted in an antibody response against recombinant gp160. These studies indicated that these two anti-ids contain a surrogate image of the antigen recognized by gp41-1.

Properties of three monoclonal antibodies that recognize an 80-kDa phytohemagglutinin-binding glycoprotein from porcine lymphocytes

Monoclonal antibodies (mAbs) directed against porcine splenocyte phytohemagglutinin receptor glycoproteins were produced in BALB/c mice. Three antibody-producing, stable hybridomas were cloned and expanded in the peritoneal cavity of BALB/c mice. The mAbs (A7, B1, and H3) were purified and belong to the IgG2 subclass of immunoglobulins (kappa light chain). Each 125I-labeled mAb bound to purified porcine splenocytes with an (apparent) affinity KA congruent to 10(8) M-1 (Scatchard analysis). The number of (apparent) binding sites was 5 x 10(4) sites/cell in the case of B1 and H3, and approximately 15 x 10(4) sites/cell for A7. Immunoprecipitation experiments showed that the three mAbs recognized a single antigenic protein of Mr 80 kilodaltons (gp80). In addition, each mAb recognized a different epitope of gp80, as observed by Western blot analyses. Assessment of the relative ability of anti-gp80 mAbs to stimulate porcine splenocytes as determined by [3H]thymidine incorporation showed weak (A7 and B1) or no (H3) mitogenic activity. Cross-linked anti-gp80 mAbs were not mitogenic, except in the case of B1. In contrast, each anti-gp80 mAb (cross-linked or untreated) showed synergistic mitogenic properties when used in combination with a suboptimal concentration of phytohemagglutinin. The mechanism involved in this synergistic effect is discussed.

Compact, low-loss, fused biconical taper couplers: overcoupled operation and antisymmetric supermode cutoff

The automated manufacture and characterization of compact four-port highly overcoupled fused couplers is reported. During the pulling stage of the manufacturing process, the light power in such devices is observed to cycle back and forth up to 1000 times between the two output ports for elongations smaller than 20 mm. For sufficiently long pulls, antisymmetric supermode cutoff has been observed for the first time to our knowledge, manifested by a sudden cessation of the coupling process. The measured wavelength dependence of the coupling ratio together with the device dimensions are consistent with the observation of cutoff as observed in pull-signature characteristics.