Межфазный катализ: синтез гликозильных эфиров N-ацетилглюкозамина

В межфазной системе “твердое тело — органический растворитель” в присутствии каталитических количеств 15-краун-5 перацетат α-D-глюкозаминилхлорида легко образует гликозильные эфиры ряда карбоновых кислот. Полученные 1-0-β-ацилпиранозы идентифицированы с помощью ¹Н ЯМР спектроскопии.У міжфазній системі “тверде тіло — органічний розчинник” у присутності каталітичної кількості 15-краун-5 перацетат α-D-глюкозамінілхлориду легко утворює глікозильні естери ряду карбонових кислот. Отримані 1-O-β-ацилпіранози ідентифіковані за допомогою ¹Н ЯМР-спектроскопії.Peracetate of α-D-glucosaminyl chloride forms easily the N-acetylglucosamine glycosyl esters of the carboxylic acids range in the phase transfer system of “solid-organic solvent” in the presence of catalytic amounts of 15-crown-5. The structure of 1-O-β-acylpyranose synthesized was identified by ¹H NMR spectroscopy

A comprehensive characterization of ice nucleation by three different types of cellulose particles immersed in water

We present the laboratory results of immersion freezing efficiencies of cellulose particles at supercooled temperature (T) conditions. Three types of chemically homogeneous cellulose samples are used as surrogates that represent supermicron and submicron ice-nucleating plant structural polymers. These samples include microcrystalline cellulose (MCC), fibrous cellulose (FC) and nanocrystalline cellulose (NCC). Our immersion freezing dataset includes data from various ice nucleation measurement techniques available at 17 different institutions, including nine dry dispersion and 11 aqueous suspension techniques. With a total of 20 methods, we performed systematic accuracy and precision analysis of measurements from all 20 measurement techniques by evaluating T-binned (1 ∘C) data over a wide T range (−36 ∘C <T<−4 ∘C). Specifically, we intercompared the geometric surface area-based ice nucleation active surface site (INAS) density data derived from our measurements as a function of T, ns,geo(T). Additionally, we also compared the ns,geo(T) values and the freezing spectral slope parameter (Δlog(ns,geo)/ΔT) from our measurements to previous literature results. Results show all three cellulose materials are reasonably ice active. The freezing efficiencies of NCC samples agree reasonably well, whereas the diversity for the other two samples spans ≈ 10 ∘C. Despite given uncertainties within each instrument technique, the overall trend of the ns,geo(T) spectrum traced by the T-binned average of measurements suggests that predominantly supermicron-sized cellulose particles (MCC and FC) generally act as more efficient ice-nucleating particles (INPs) than NCC with about 1 order of magnitude higher ns,geo(T)

Eutrophication and acidification: Do they induce changes in the dissolvedorganic matter dynamics in the coastal Mediterranean Sea?

Original research paperTwo mesocosms experiments were conducted in winter 2010 and summer 2011 to examine how increased pCO2and/or nutrient concentrations potentially perturbate dissolved organic matter dynamics in natural microbialassemblages. Thefluorescence signals of protein- and humic-like compounds were used as a proxy for labileand non-labile material, respectively, while the evolution of bacterial populations, chlorophylla(Chla) anddissolved organic carbon (DOC) concentrations were used as a proxy for biological activity. For both seasons,the presence of elevated pCO2did not cause any significant change in the DOC dynamics (p-valueb0.05). Theconditions that showed the greatest changes in prokaryote abundances and Chlacontent were those amendedwith nutrients, regardless of the change in pH. The temporal evolution offluorophores and optical indices re-vealed that the degree of humification of the organic molecules and their molecular weight changed significantlyin the nutrient-amended treatment. The generation of protein-like compounds was paired to increases in theprokaryote abundance, being higher in the nutrient-amended tanks than in the control. Different patterns inthe magnitude and direction of the generation of humic-like molecules suggested that these changes dependedon initial microbial populations and the availability of extra nutrient inputs. Based on our results, it is expected that in the future projected coastal scenarios the eutrophication processes will favor the transformations of labile and recalcitrant carbon regardless of changes in pCO2.MINECO, European Union, Generalitat de Catalunya, CSICVersión del editor3,25

Fluorescence characteristics of dissolved organic matter in the deep waters of the Okhotsk Sea and the northwestern North Pacific Ocean

Fluorescent dissolved organic matter (DOM), a fraction of chromophoric DOM, has been known to be produced in the deep ocean and has been considered to be bio-refractory. However, the factors controlling fluorescence properties of DOM in the deep ocean are still not well understood. In this study, we determined the fluorescence properties of DOM in the deep waters of the Okhotsk Sea and the northwestern North Pacific Ocean using excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC). One protein-like, two humic-like components, and one uncertain component, that might be derived from a fluorometer artifact, were identified by EEM-PARAFAC. Fluorescence intensity levels of the protein-like component were highest in the surface waters, decreased with depth, but did not change systematically in the bathypelagic layer (1000 m - bottom). Fluorescence characteristics of the two humic-like components were similar to those traditionally defined as marine and terrestrial humic-like fluorophores, respectively. The fluorescence intensity levels of the two humic-like components were lowest in the surface waters, increased with depth in the mesopelagic layer (200 - 1000 m), and then slightly decreased with depth in the bathypelagic layer. The ratio of the two humic-like components remained in a relatively narrow range in the bathypelagic layer compared to that in the surface layer, suggesting a similar composition of humic-like fluorophores in this layer. In addition, the fluorescence intensities of the two humic-like components were linearly correlated to apparent oxygen utilization (AOU) in the bathypelagic layer, suggesting that both humic-like components are produced in situ as organic matter is oxidized biologically. These findings imply that optical characteristics of humic-like fluorophores once formed might not be altered further biologically or geochemically in the deep ocean. On the other hand, relationships of fluorescence intensities with AOU and Fe(III) solubility were different between the two humic-like components in the mesopelagic layer, suggesting different environmental dynamics and biogeochemical roles for the two humic-like components

Application of excitation emission matrix fluorescence monitoring in the assessment of spatial and seasonal drivers of dissolved organic matter composition: Sources and physical disturbance controls

The environmental dynamics of dissolved organic matter (DOM) were characterized for a shallow, subtropical, seagrass-dominated estuarine bay, namely Florida Bay, USA. Large spatial and seasonal variations in DOM quantity and quality were assessed using dissolved organic C (DOC) measurements and spectrophotometric properties including excitation emission matrix (EEM) fluorescence with parallel factor analysis (PARAFAC). Surface water samples were collected monthly for 2 years across the bay. DOM characteristics were statistically different across the bay, and the bay was spatially characterized into four basins based on chemical characteristics of DOM as determined by EEM-PARAFAC. Differences between zones were explained based on hydrology, geomorphology, and primary productivity of the local seagrass community. In addition, potential disturbance effects from a very active hurricane season were identified. Although the overall seasonal patterns of DOM variations were not significantly affected on a bay-wide scale by this disturbance, enhanced freshwater delivery and associated P and DOM inputs (both quantity and quality) were suggested as potential drivers for the appearance of algal blooms in high impact areas. The application of EEM-PARAFAC proved to be ideally suited for studies requiring high sample throughput methods to assess spatial and temporal ecological drivers and to determine disturbance-induced impacts in aquatic ecosystems

Pulmonary magnetic resonance imaging biomarkers of lung structure and function in adult survivors of bronchopulmonary dysplasia with COPD

Bronchopulmonary dysplasia (BPD) is an emerging risk factor for chronic obstructive pulmonary disease. For BPD survivors, there are no guidelines for the management of lung disease that is often misdiagnosed as asthma. Pulmonary magnetic resonsance imaging (MRI) provides clinically-relevant lung biomarkers of ventilation abnormalities and emphysema. Here our objective was to quantify lung MRI biomarkers in adults with BPD to understand the underlying pathophysiologies responsible for their symptoms and abnormal pulmonary-function. We hypothesized that MRI measurements would be abnormal and reflect emphysema, not airways disease. Patients aged 20–29 year and born ≤32 weeks gestational age were included and those with MRI contraindications were excluded. A 25-year-old female never-smoker born <28 weeks gestation (S1) and a 27-year-old male ex-smoker born ~30 weeks gestation (S2) provided written-informed-consent and underwent pulmonary-function-tests and MRI. Lung abnormalities were quantified using ventilation defect percent (VDP), apparent diffusion coefficients (ADC) and mean linear intercept (Lm). Forced expiratory volume-in 1 sec (S1 = 46%pred/S2 = 33%pred), residual-volume (S1 = 192%pred/S2 = 267%pred) and diffusing-capacity-of-the-lung-for-carbon-monoxide (S1 = 73%pred/S2 = 72%pred) were abnormal. Chest–X-ray and computed tomography (CT) revealed mild structural abnormalities, while MRI VDP (S1 = 6%/S2 = 10%), ADC (S1 = 0.36 cm2/s/S2 = 0.37 cm2/s) and Lm (S1 = 400 μm/S2 = 430 μm) were markedly abnormal with ventilation defects spatially concordant with regions of low MRI signal-intensity and greater Lm, reflecting emphysema and/or gas-trapping. In BPD survivors, MRI biomarkers have the potential to serve as intermediate endpoints and help evaluate therapy

Killing of Pseudomonas aeruginosa by chicken cathelicidin-2 is immunogenically silent, preventing lung inflammation in vivo

The development of antibiotic resistance by Pseudomonas aeruginosa is a major concern in the treatment of bacterial pneumonia. In the search of novel anti-infective therapies, the chicken-derived peptide cathelicidin-2 (CATH-2) has emerged as a potential candidate, with strong broad-spectrum antimicrobial activity and the ability to limit inflammation by inhibiting TLR2 and TLR4 activation. However, as it is unknown how CATH-2 affects inflammation in vivo, we investigated how CATH-2-mediated killing of P. aeruginosa affects lung inflammation in a murine model.First, murine macrophages were used to determine whether CATH-2-mediated killing of P. aeruginosa reduced pro-inflammatory cytokine production in vitro Next, a murine lung model was used to analyze how CATH-2-mediated killing of P. aeruginosa affects neutrophil and macrophage recruitment as well as cytokine/chemokine production in the lung.Our results show that CATH-2 kills P. aeruginosa in an immunogenically silent manner both in vitro and in vivo Treatment with CATH-2-killed P. aeruginosa showed reduced neutrophil recruitment to the lung as well as inhibition of cytokine and chemokine production, compared to treatment with heat- or gentamicin-killed bacteria.Together, these results show the potential for CATH-2 as a dual-activity antibiotic in bacterial pneumonia, which can both kill P. aeruginosa and prevent excessive inflammation