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Intercalation-induced phase transformations in Li-ion battery electrode materials give rise to multi-phase coexistence regimes within individual particles, generating significant lattice coherency strain across dynamically evolving interfaces. We demonstrate here that the lattice coherency strain can be alleviated by leveraging the coupling of electrochemistry, mechanics, and particle geometry to achieve controllable nucleation and deterministic ion transport. Here, we contrast singular kinks and continuous curvature as a means of enabling homogeneous lithiation without developing large stresses within a model cathode material, V2O5. The singular kink confirms that local curvature facilitates lithiation but also exacerbates lithiation inhomogeneities and elastic misfit strain. In contrast, the incorporation of continuous curvature enables homogeneous single-phase lithiation, mitigating lattice coherency strain. The studies provide a direct view of the coupling of mechanics and electrochemistry within crystalline electrodes and suggest that mesoscale architectures can help resolve key failure mechanisms limiting the performance of energy-storage systems without sacrificing charge/discharge kinetics.

Transformations between different atomic configurations of a material oftentimes bring about dramatic changes in functional properties as a result of the simultaneous alteration of both atomistic and electronic structure. Transformation barriers between polytypes can be tuned through compositional modification, generally in an immutable manner. Continuous, stimulus-driven modulation of phase stabilities remains a significant challenge. Utilizing the metal–insulator transition of VO2, we exemplify that mobile dopants weakly coupled to the crystal lattice provide a means of imbuing a reversible and dynamical modulation of the phase transformation. Remarkably, we observe a time- and temperature-dependent evolution of the relative phase stabilities of the M1and R phases of VO2in an “hourglass” fashion through the relaxation of interstitial boron species, corresponding to a 50 °C modulation of the transition temperature achieved within the same compound. The material functions as both a chronometer and a thermometer and is “reset” by the phase transition. Materials possessing memory of thermal history hold promise for applications such as neuromorphic computing, atomic clocks, thermometry, and sensing.

Molybdenum disulfide (MoS2) is a semiconducting transition metal dichalcogenide that is known to be a catalyst for both the hydrogen evolution reaction (HER) as well as for hydro-desulfurization (HDS) of sulfur-rich hydrocarbon fuels. Specifically, the edges of MoS2nanostructures are known to be far more catalytically active as compared to unmodified basal planes. However, in the absence of the precise details of the geometric and electronic structure of the active catalytic sites, a rational means of modulating edge reactivity remain to be developed. Here we demonstrate using first-principles calculations, X-ray absorption spectroscopy, as well as scanning transmission X-ray microscopy (STXM) imaging that edge corrugations yield distinctive spectroscopic signatures corresponding to increased localization of hybrid Mo 4d states. Independent spectroscopic signatures of such edge states are identified at both the S L2,3and S K-edges with distinctive spatial localization of such states observed in S L2,3-edge STXM imaging. The presence of such low-energy hybrid states at the edge of the conduction band is seen to correlate with substantially enhanced electrocatalytic activity in terms of a lower Tafel slope and higher exchange current density. These results elucidate the nature of the edge electronic structure and provide a clear framework for its rational manipulation to enhance catalytic activity.

Increasing intercalation of Li-ions brings about distortive structural transformations in several canonical intercalation hosts. Such phase transformations require the energy dissipative creation and motion of dislocations at the interface between the parent lattice and the nucleated Li-rich phase. Phase inhomogeneities within particles and across electrodes give rise to pronounced stress gradients, which can result in capacity fading. How such transformations alter Li-ion diffusivities remains much less explored. In this article, we use layered V2O5as an intercalation host and examine the structural origins of the evolution of Li-ion diffusivities with phase progression upon electrochemical lithiation. Galvanostatic intermittent titration measurements show a greater than 4 orders of magnitude alteration of Li-ion diffusivity in V2O5as a function of the extent of lithiation. Pronounced dips in Li-ion diffusivities are correlated with the presence of phase mixtures as determined by Raman spectroscopy and X-ray diffraction, whereas monophasic regimes correspond to the highest Li-ion diffusivity values measured within this range. First-principles density functional theory calculations confirm that the variations in Li-ion diffusivity do not stem from intrinsic differences in diffusion pathways across the different lithiated V2O5phases, which despite differences in the local coordination environments of Li-ions show comparable migration barriers. Scanning transmission X-ray microscopy measurements indicate the stabilization of distinct domains reflecting the phase coexistence of multiple lithiated phases within individual actively intercalating particles. The results thus provide fundamental insight into the considerable ion transport penalties incurred as a result of phase boundaries formed within actively intercalating particles. The combination of electrochemical studies with ensemble structural characterization and single-particle X-ray imaging of phase boundaries demonstrates the profound impact of interfacial phenomena on macroscopic electrode properties.

In this work, we report the effects of incorporation of variable amounts (1–20 wt %) of sodium montmorillonite (MMT) into a siloxane–poly(ethylene oxide) hybrid hydrogel prepared by the sol–gel route. The aim was to control the nanostructural features of the nanocomposite, improve the release profile of the sodium diclofenac (SDCF) drug, and optimize the swelling behavior of the hydrophilic matrix. The nanoscopic characteristics of the siloxane-cross-linked poly(ethylene oxide) network, the semicrystallinity of the hybrid, and the intercalated or exfoliated structure of the clay were investigated by X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. The correlation between the nanoscopic features of nanocomposites containing different amounts of MMT and the swelling behavior revealed the key role of exfoliated silicate in controlling the water uptake by means of a flow barrier effect. The release of the drug from the nanocomposite displayed a stepped pattern kinetically controlled by the diffusion of SDCF molecules through the mass transport barrier created by the exfoliated silicate. The sustained SDCF release provided by the hybrid hydrogel nanocomposite could be useful for the prolonged treatment of painful conditions, such as arthritis, sprains and strains, gout, migraine, and pain after surgical procedures.

Understanding the diffusion mechanisms of Li ions through host materials and the resulting phase evolution of intercalated phases is of paramount importance for designing electrode materials of rechargeable batteries. The formation of lithiation gradients and discrete domains during intercalation leads to the development of strain within the host material and is responsible for the observed capacities of most cathode materials being well below theoretically predicted values. Such mesoscale heterogeneity has also been implicated in the loss of capacity upon cycling. Due to their inherent complexity, the analysis of such heterogeneity is rather complex and precise understanding of the evolution of metal sites remains underexplored. In this work, we use phase-pure, single-crystalline V2O5nanowires with dimensions of 183 ± 50 nm and lengths spanning tens of microns as a model cathode material and demonstrate that V K-edge X-ray absorption near-edge structure can be used as an effective probe of the local valence and geometry of vanadium sites upon lithiation. We demonstrate that a highly lithiated phase is nucleated and grows at the expense of a homogeneous low-lithium-content α-phase without mediation of a solid-solution with intermediate lithium content. Density functional theory calculations allow for assignment of the pre-edge feature to dipolar transitions that are particularly sensitive to the V 3d–O 2p hybridization of the vanadyl bond and the local geometry of the distorted [VO5] square pyramid. The quantitative analysis of multiple vanadium sites and their evolution as a function of Li-ion content provides insight into the mechanism of phase evolution and the nature of lithiation gradients. The phase coexistence and segregation is further observed in scanning transmission X-ray microscopy images of individual lithiated V2O5nanowires. The mechanisms and the dynamics of nucleation and growth unraveled here are of great importance for the design and discovery of Li-ion cathode materials.

Transition metal oxides are usually used as catalysts in the air cathode of lithium–air (Li–air) batteries. This study elucidates the mechanistic origin of the oxygen reduction reaction catalyzed by δ-MnO2monolayers and maps the conditions for Li2O2growth using a combination of first-principles calculations and mesoscale modeling. The MnO2monolayer, in the absence of an applied potential, preferentially reacts with a Li atom instead of an O2molecule to initiate the formation of LiO2. The oxygen reduction products (LiO2, Li2O2, and Li2O molecules) strongly interact with the MnO2monolayer via the stabilization of Li–O chemical bonds with lattice oxygen atoms. As compared to the disproportionation reaction, direct lithiation reactions are the primary contributors to the stabilization of Li2O2on the MnO2monolayer. The energy profiles of (Li2O2)2and (Li2O)2nucleation on δ-MnO2monolayer during the discharge process demonstrate that Li2O2is the predominant discharge product and that further reduction to Li2O is inhibited by the high overpotential of 1.21 V. Interface structures have been examined to study the interaction between the Li2O2and MnO2layers. This study demonstrates that a Li2O2film can be homogeneously deposited onto δ-MnO2and that the Li2O2/MnO2interface acts as an electrical conductor. A mesoscale model, developed based on findings from the first-principles calculations, further shows that Li2O2is the primary product of electrochemical reactions when the applied potential is smaller than 2.4 V.

The origins of performance degradation in batteries can be traced to atomistic phenomena, accumulated at mesoscale dimensions, and compounded up to the level of electrode architectures. Hyperspectral X-ray spectromicroscopy techniques allow for the mapping of compositional variations, and phase separation across length scales with high spatial and energy resolution. We demonstrate the design of workflows combining singular value decomposition, principal-component analysis, k-means clustering, and linear combination fitting, in conjunction with a curated spectral database, to develop high-accuracy quantitative compositional maps of the effective depth of discharge across individual positive electrode particles and ensembles of particles. Using curated reference spectra, accurate and quantitative mapping of inter- and intraparticle compositional heterogeneities, phase separation, and stress gradients is achieved for a canonical phase-transforming positive electrode material, α-V2O5. Phase maps from single-particle measurements are used to reconstruct directional stress profiles showcasing the distinctive insights accessible from a standards-informed application of high-dimensional chemical imaging.

Often typified as cunning social predators, psychopathic offenders show a persistent pattern of impulsive and reckless behavior, the pathophysiology of which has been related to dysfunction in the dorsolateral prefrontal cortex (DLPFC). That is, the DLPFC is important for the regulatory control of impulses and emotion as well as working memory and psychopathic offenders show impairments in all three dimensions. In the present study, we used combined transcranial magnetic stimulation and electroencephalography to compare the physiology of the DLPFC in 13 psychopathic offenders and 15 healthy subjects vis à vis excitability and inhibition. In addition, working memory performance was measured through the letter–number sequencing test. Results showed that compared to healthy subjects, psychopathic offenders had inhibition not excitability deficits in the DLPFC that was accompanied by deficits in working memory performance. In healthy controls and psychopathic offenders working memory performance correlated with the extent of inhibition over the DLPFC. Taken together, these findings suggest that psychopathic offenders suffer from dysfunctional inhibitory neurotransmission in the DLPFC and impaired working memory which may account for the behavioral impairments associated with this disorder.

Increased plasma concentrations of the endogenous nitric oxide synthase inhibitor, asymmetric dimethylarginine, decreased arginine bioavailability, and mitochondrial dysfunction have been reported in adult sepsis. We studied whether asymmetric dimethylarginine, arginine, and carnitine metabolism (a measure of mitochondrial dysfunction) are altered in pediatric sepsis and whether these are clinically useful biomarkers.

AbstractThe essential oil from leaves of Bauhinia acuruanaMoric was obtained by hydrodistillation and analyzed by gas chromatography (GC-FID) and gas chromatography/mass spectrometry (GC/MS). In total, thirty compounds comprising 91.4% of the total peak area were identified. The main constituents of the essential oil were the sesquiterpenes spathulenol (23.4 ± 0.08%), epi-α-cadinol (20.7 ± 0.12%) and caryophyllene oxide (16.4 ± 0.04%). The essential oil was tested against Aedes aegyptilarvae and showed LC50value of 56.2 ± 0.4 μg/mL.

Cervical cancer (CC) is still the second in prevalence and mortality among women. In spite of previously observed higher incidence of cervical dysplasia among systemic lupus erythematosus (SLE) patients, few studies have considered the influence of classic risk factors and the use of immunosuppressors (IM).

ABSTRACTHuman infection with Leishmania braziliensiscan lead to cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML). We hypothesize that the intense tissue destruction observed in ML is a consequence of an uncontrolled exacerbated inflammatory immune response, with cytotoxic activity. For the first time, this work identifies the cellular sources of inflammatory and antiinflammatory cytokines, the expression of effector molecules, and the expression of interleukin-10 (IL-10) receptor in ML and CL lesions by using confocal microscopy. ML lesions displayed a higher number of gamma interferon (IFN-γ)-producing cells than did CL lesions. In both ML and CL, CD4+cells represented the majority of IFN-γ-producing cells, followed by CD8+cells and CD4−CD8−cells. The numbers of tumor necrosis factor alpha-positive cells, as well as those of IL-10-producing cells, were similar in ML and CL lesions. The effector molecule granzyme A showed greater expression in ML than in CL lesions, while inducible nitric oxide synthase did not. Finally, the expression of IL-10 receptor was lower in ML than in CL lesions. Thus, our data identified distinct cytokine and cell population profiles for CL versus ML patients and provide a possible mechanism for the development of ML disease through the demonstration that low expression of IL-10 receptor is present in conjunction with a cytotoxic and inflammatory profile in ML.

Background: Helminthic infections decrease skin reactivity to indoor allergens, but data on whether they influence asthma severity are lacking. Objective: This study evaluated the course of asthma in patients with and without Schistosoma mansoniinfection. Methods: Asthmatic subjects were enrolled from 3 low-socioeconomic areas: a rural area endemic for schistosomiasis (group 1) in addition to a rural area (group 2) and a slum area (group 3), both of which were not endemic for schistosomiasis. A questionnaire on the basis of the International Study of Asthma and Allergies in Childhood study was applied in these 3 areas, and from each area, 21 age- and sex-matched asthmatic subjects were selected for a prospective 1-year study. Pulmonary function tests, skin prick tests with indoor allergens, stool examinations, and serum evaluations were performed in these subjects. Every 3 months, the subjects were evaluated for asthma exacerbation through physical examination, and a questionnaire regarding asthma symptoms and use of antiasthma medicine was administered. Results: The prevalence of S mansoniinfection was greater in group 1 compared with in groups 2 and 3 (P< .0001), whereas the frequency of other helminth and protozoa infections was similar among the 3 groups. The frequency of positive skin test responses to indoor allergens was less (19.0%) in group 1 subjects relative to those in group 2 (76.2%) and group 3 (57.1%; P< .001). The frequencies of symptoms, use of antiasthma drugs, and pulmonary abnormal findings at physical examination were less in group 1 subjects than in group 2 and 3 subjects (P= .0001). Conclusion: Our results suggest that S mansoniinfection is associated with a milder course of asthma.

Background:Recurrent vaginal candidiasis (RVC) is an important health problem with unknown pathogenesis. Although impairment of the T-cell response is associated with persistent or recurrent candidiasis, data on immunologic responses in patients with RVC are controversial. Objectives:To evaluate the T-cell response in patients with RVC and the ability of cytokines and cytokine antagonists to modulate IFN-γ production in cultures stimulated with Candida albicansantigens. Methods:Participants in the study included 13 patients with RVC and 7 control women with sporadic candidiasis. Cytokines were determined by ELISA in supernatants of mononuclear cells with C albicans, purified protein derivative, or tetanus toxoid antigen. Results:IFN-γ production was absent or low in 11 of 13 women (84.6%) with RVC. Absent or low IFN-γ production was specific to C albicansantigens (189 ± 389 pg/mL), because high IFN-γ levels were found in cultures stimulated with purified protein derivative (739 ± 774 pg/mL) or tetanus toxoid antigens (1085 ± 546 pg/mL). Monoclonal antibody anti-IL-10 enhanced IFN-γ levels (750 ± 753 pg/mL), and IL-10 suppressed this cytokine production in patients with sporadic candidiasis. Conclusions:Mononuclear cells from patients with RVC stimulated with C albicansantigen have low or absent IFN-γ production. IL-10 plays an important role in downregulation of the T-cell response in these patients. (J Allergy Clin Immunol 2002;109:102-5.)

We have explored the biological function of a surface glycoprotein (GP72) of Trypanosoma cruzi by studying a null mutant parasite, generated by targeted gene deletion. GP72 deletion affected parasite morphology in several stages of the life cycle. Insect midgut (epimastigote) forms had a detached flagellum (apomastigote) in the null mutant. The abnormal flagellar phenotype persisted during development of the infective (metacyclic) forms but there was no impairment in the acquisition of complement resistance, sialidase expression or cell infectivity. The GP72 null mutant could efficiently infect and proliferate in mouse macrophages and non-phagocytic L6E9 cells. The mammalian stages of the life cycle also showed major morphological abnormalities. During early subcultures in L6E9 cells, few extracellular fully flagellated forms, expressing markers characteristic of trypomastigotes, were seen. The extracellular population consisted almost exclusively of rounded forms with short flagella (micromastigote), which expressed an amastigote-specific surface marker and no sialidase. The propagation of the parasite was not affected, despite the apparent lack of the trypomastigote forms, which are thought to be primarily responsible for cell invasion. After some subcultures, the extracellular population changed to about equal numbers of micromastigotes and a range of flagellated forms that still did not include true trypomastigotes. Instead, the kinetoplast remained close to the nucleus and the flagellum emerged from the middle of the cell (mesomastigote). Half of the flagellum adhered to the cell body and the remainder was free at the anterior end. In Triatoma infestans, the survival of the mutant was dramatically reduced, suggesting that either GP72 itself, or the altered properties of the flagellum, were critical for establishment in the insect vector.