Groovy chiral gold particles
Although plasmonic optical activity can arise from chiral assemblies of gold and silver nanoparticles, there are few examples of gold nanoparticles with intrinsic ...chirality and high optical activity. González-Rubio
et al.
show that morphological chirality can be induced during the seeded growth of gold nanoparticles, particularly for highly anisotropic nanorods. Chiral additives as cosurfactants formed helical micelles that directed the seeded growth to create grooves that maintained a chiral morphology. The resulting particles displayed high-intensity circular dichroism with anisotropy factors near 0.2 at near-infrared wavelengths.
Science
, this issue p.
1472
Seeded growth with gold nanorods and chiral micelle cosurfactants created nanoparticles with high chiroplasmonic activity.
Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20). Through variation of the dimensions of chiral wrinkles, the chiroptical properties can be tuned within the visible and near-infrared electromagnetic spectrum. The micelle-directed mechanism allows extension to other systems, such as the seeded growth of chiral platinum shells on gold nanorods. This approach provides a reproducible, simple, and scalable method toward the fabrication of NPs with high chiral optical activity.
Comprehensive studies that examine the transfer of metals across soil-river bed sediment systems at the basin scale are scarce. An understanding of the distribution of metals among various fractions ...of soils and sediments within a basin is fundamental to understand their environmental behavior and, thus, to define watershed management plans. This study aims to determine the distribution of metals (Fe, Mn, Cu, and Zn) in topsoils under different land uses (cultivation, pastures, and forests) and river surface sediments in the upper Mero River basin (NW Spain) and to assess these metals' mobility and bioavailability in both environmental compartments to detect potential threats to crops and the water quality. Sequential extraction is used to fractionate the four metals into six fractions: soluble/exchangeable/specifically adsorbed, metals that are bound to Mn oxides, amorphous compounds, metals that are bound to organic matter, crystalline Al and Fe oxides, and residual metals (metals within the crystal lattices of minerals). The fractionation results for both soils and sediment indicate an abundance of metals in the residual fraction (except for Mn in soils) followed by relatively high percentages of oxide-bound fractions (mostly crystalline Fe oxides for both Fe and Zn, amorphous for Cu, and Mn oxides for Mn). On average, the Mn residual fraction in soils (30.2%) is only slightly exceeded by the Mn oxide fraction (34.7%). The land uses do not affect the sequence of metal-binding phases in soils, except for Mn, which is only slightly altered. The results also suggest that Fe, Mn, Cu and Zn in both soils and sediments are not readily mobile under current environmental condition and hence pose no threat to crops or the water quality. In overall terms, the mobility and bioavailability of the four metals (considering the sum of the three least mobile fractions, namely, organic matter, crystalline Al and Fe oxides, and residual) in the soils decrease in the following order: Mn>Cu>Fe>Zn. The same sequence occurs in the sediments, but the order between Fe and Zn is reversed. The soils and sediments that are studied cannot be considered polluted in terms of these metals because of their low levels and prevalence in the residual fraction, which is typical of contributions from natural sources and indicates the pedogenic/lithologic origin of these metals.
•We assess metal fractionation (Cu, Zn, Fe, Mn) in soils and river bed sediments.•Land uses did not affect the sequence of metal-binding phases in soils, except Mn.•The examined metals are not readily mobile under current environmental conditions.•Mn is potentially more bioavailable than the other metals that are examined.•The soils and sediments cannot be considered polluted in terms of Cu, Zn, Mn and Fe.
Abstract
Background
The role of vitamin D status in COVID-19 patients is a matter of debate.
Objectives
To assess serum 25-hydroxyvitamin D (25OHD) levels in hospitalized patients with COVID-19 and ...to analyze the possible influence of vitamin D status on disease severity.
Methods
Retrospective case–control study of 216 COVID-19 patients and 197 population-based controls. Serum 25OHD levels were measured in both groups. The association of serum 25OHD levels with COVID-19 severity (admission to the intensive care unit, requirements for mechanical ventilation, or mortality) was also evaluated.
Results
Of the 216 patients, 19 were on vitamin D supplements and were analyzed separately. In COVID-19 patients, mean ± standard deviation 25OHD levels were 13.8 ± 7.2 ng/mL, compared with 20.9 ± 7.4 ng/mL in controls (P < .0001). 25OHD values were lower in men than in women. Vitamin D deficiency was found in 82.2% of COVID-19 cases and 47.2% of population-based controls (P < .0001). 25OHD inversely correlates with serum ferritin (P = .013) and D-dimer levels (P = .027). Vitamin D-deficient COVID-19 patients had a greater prevalence of hypertension and cardiovascular diseases, raised serum ferritin and troponin levels, as well as a longer length of hospital stay than those with serum 25OHD levels ≥20 ng/mL. No causal relationship was found between vitamin D deficiency and COVID-19 severity as a combined endpoint or as its separate components.
Conclusions
25OHD levels are lower in hospitalized COVID-19 patients than in population-based controls and these patients had a higher prevalence of deficiency. We did not find any relationship between vitamin D concentrations or vitamin deficiency and the severity of the disease.
Chiral plasmonics is a rapidly developing field where breakthroughs and unsolved problems coexist. We have recently reported binary surfactant-assisted seeded growth of chiral gold nanorods (Au NRs) ...with high chiroptical activity. Such a seeded-growth process involves the use of a chiral cosurfactant that induces micellar helicity, in turn driving the transition from achiral to chiral Au NRs, from both the morphological and the optical points of view. We report herein a detailed study on both transitions, which reveals intermediate states that were hidden so far. The correlation between structure and optical response is carefully analyzed, including the (linear and CD) spectral evolution over time, electron tomography, the impact of NR dimensions on their optical response, the variation of the absorption-to-scattering ratio during the evolution from achiral to chiral Au NRs, and the near-field enhancement related to chiral plasmon modes. Our findings provide further understanding of the growth process of chiral Au NRs and the associated optical changes, which will facilitate further study and applications of chiral nanomaterials.
Surface-enhanced Raman scattering (SERS) has become a widely used spectroscopic technique for chemical identification, providing unbeaten sensitivity down to the single-molecule level. The ...amplification of the optical near field produced by collective electron excitations plasmons in nanostructured metal surfaces gives rise to a dramatic increase by many orders of magnitude in the Raman scattering intensities from neighboring molecules. This effect strongly depends on the detailed geometry and composition of the plasmon-supporting metallic structures. However, the search for optimized SERS substrates has largely relied on empirical data, due in part to the complexity of the structures, whose simulation becomes prohibitively demanding. In this work, we use state-of-the-art electromagnetic computation techniques to produce predictive simulations for a wide range of nanoparticle-based SERS substrates, including realistic configurations consisting of random arrangements of hundreds of nanoparticles with various morphologies. This allows us to derive rules of thumb for the influence of particle anisotropy and substrate coverage on the obtained SERS enhancement and optimum spectral ranges of operation. Our results provide a solid background to understand and design optimized SERS substrates.
Small headwater catchments deliver large quantities of suspended sediment (SS) to the ocean. However, there are relatively few studies focused on the study of patterns and dynamics of suspended ...sediment in headwater catchments over the long-term (10 year or more). In this study, the dynamics of suspended sediment transport were examined at different time scales in a small headwater catchment in NW Spain, based on a 12-year dataset from high-resolution monitoring. The results revealed that, similar to other humid catchments, the hydrological response was highly dependent on initial conditions, especially in autumn and summer. However, in winter and spring the hydrology was more influenced by rainfall amount. The annual suspended sediment was 117 Mg, which equates to a suspended sediment yield of 10 Mg km−2 y−1. The SS yield in the Corbeira catchment is related to runoff generation and flooding, which play a key role in sediment yield from the catchment. About 80% of the annual SS was transported over 12% of the study period. Rainfall and discharge at the beginning of the events were the most important factors in explaining the hydrological response at event scale. Suspended sediment transport in this catchment is determined by event magnitude, while the SS is mainly influenced by variables related to runoff erosivity.
Display omitted
•The SS transport dynamic was assessed in a small headwater area in NW Spain.•The high SS variability underlines the importance of long-term records.•SS transport is mainly influenced by streamflow; SS availability is also important.•Multivariate analysis identified the factors controlling the runoff and SS response.
Toward Ultimate Nanoplasmonics Modeling Solís, Diego M; Taboada, José M; Obelleiro, Fernando ...
ACS nano,
08/2014, Letnik:
8, Številka:
8
Journal Article
Recenzirano
Advances in the field of nanoplasmonics are hindered by the limited capabilities of simulation tools in dealing with realistic systems comprising regions that extend over many light wavelengths. We ...show that the optical response of unprecedentedly large systems can be accurately calculated by using a combination of surface integral equation (SIE) method of moments (MoM) formulation and an expansion of the electromagnetic fields in a suitable set of spatial wave functions via fast multipole methods. We start with a critical review of volume versus surface integral methods, followed by a short tutorial on the key features that render plasmons useful for sensing (field enhancement and confinement). We then use the SIE-MoM to examine the plasmonic and sensing capabilities of various systems with increasing degrees of complexity, including both individual and interacting gold nanorods and nanostars, as well as large random and periodic arrangements of ∼1000 gold nanorods. We believe that the present results and methodology raise the standard of numerical electromagnetic simulations in the field of nanoplasmonics to a new level, which can be beneficial for the design of advanced nanophotonic devices and optical sensing structures.
To compare the effectiveness of rituximab versus an alternative tumour necrosis factor (TNF) inhibitor (TNFi) in patients with rheumatoid arthritis (RA) with an inadequate response to one previous ...TNFi.
SWITCH-RA was a prospective, global, observational, real-life study. Patients non-responsive or intolerant to a single TNFi were enrolled ≤4 weeks after starting rituximab or a second TNFi. Primary end point: change in Disease Activity Score in 28 joints excluding patient's global health component (DAS28-3)-erythrocyte sedimentation rate (ESR) over 6 months.
604 patients received rituximab, and 507 an alternative TNFi as second biological therapy. Reasons for discontinuing the first TNFi were inefficacy (n=827), intolerance (n=263) and other (n=21). A total of 728 patients were available for primary end point analysis (rituximab n=405; TNFi n=323). Baseline mean (SD) DAS28-3-ESR was higher in the rituximab than the TNFi group: 5.2 (1.2) vs 4.8 (1.3); p<0.0001. Least squares mean (SE) change in DAS28-3-ESR at 6 months was significantly greater in rituximab than TNFi patients: -1.5 (0.2) vs -1.1 (0.2); p=0.007. The difference remained significant among patients discontinuing the initial TNFi because of inefficacy (-1.7 vs -1.3; p=0.017) but not intolerance (-0.7 vs -0.7; p=0.894). Seropositive patients showed significantly greater improvements in DAS28-3-ESR with rituximab than with TNFi (-1.6 (0.3) vs -1.2 (0.3); p=0.011), particularly those switching because of inefficacy (-1.9 (0.3) vs -1.5 (0.4); p=0.021). The overall incidence of adverse events was similar between the rituximab and TNFi groups.
These real-life data indicate that, after discontinuation of an initial TNFi, switching to rituximab is associated with significantly improved clinical effectiveness compared with switching to a second TNFi. This difference was particularly evident in seropositive patients and in those switched because of inefficacy.
The hydrological response of a small agroforestry catchment in northwest Spain (Corbeira catchment, 16 km
2
) is analysed, with particular focus on rainfall events. Fifty-four rainfall-runoff events, ...from December 2004 to September 2007, were used to analyse the principal hydrological patterns and show which factors best explain the hydrological response. The nonlinearity between rainfall and runoff showed that the variability in the hydrological response of the catchment was linked to the seasonal dynamics of the rainfall and, to a lesser extent, to evapotranspiration. The runoff coefficient, estimated as the ratio between direct runoff and rainfall volume, on an event basis, was analysed as a function of rainfall characteristics (amount and intensity) and the initial catchment state conditions prior to an event, such as pre-event baseflow and antecedent rainfall index. The results revealed that the hydrological response depends both on the soil humidity conditions at the start of the event and on rainfall amount, whereas rainfall intensity presented only a significant correlation with discharge increment. The antecedent conditions seem to be a key point in runoff production, and they explain much of the response. The hydrographs are characterized by a steep rising limb, a relatively narrow peak discharge and slow recession limb. These data and the observations suggest that the subsurface flow is the dominant runoff process.
Editor Z.W. Kundzewicz; Associate editor T. Wagener
Citation Rodríguez-Blanco, M.L., Taboada-Castro, M.M. and Taboada-Castro, M.T., 2012. Rainfall-runoff response and event-based runoff coefficients in a humid area (northwest Spain). Hydrological Sciences Journal, 57 (3), 445-459.
Open label studies have suggested that tumour necrosis factor (TNF) antagonists led to sustained improvement and corticosteroid sparing effect in patients with giant cell arteritis (GCA). To confirm ...these observations, we conducted a randomised, double-blind, placebo controlled trial with etanercept in patients with biopsy-proven GCA with side effects secondary to corticosteroids.
We randomly assigned patients with GCA to receive etanercept (n = 8) or placebo (n = 9) over 1 year together with corticosteroids that were reduced according to a predefined schedule. The primary outcome was the ability to withdraw the corticosteroid therapy and control the disease activity at 12 months.
Baseline characteristics were similar in the two groups, although patients in the etanercept group showed higher levels of basal glycaemia (p = 0.02) and a higher erythrocyte sedimentation rate (ESR) (p = 0.01). After 12 months, 50% of the patients in the etanercept group and 22.2% in the placebo group were able to control the disease without corticosteroid therapy (p value not significant). Patients in the etanercept group had a significant lower dose of accumulated prednisone during the first year of treatment (p = 0.03). There were no differences in the number and type of adverse events.
The limited number of patients included in this study does not allow us to draw definitive conclusions. Etanercept therapy was well tolerated in this aged population. The therapeutic role of etanercept in patients with GCA should be evaluated in studies with a larger number of patients.
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