Sorption of hydrophobic organic contaminants on functionalized biochar: Protagonist role of Π-Π electron-donor-acceptor interactions and hydrogen bonds

© 2018 Elsevier B.V. The sorption of five potent endocrine disruptors as representative hydrophobic organic contaminants (HOCs) namely estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2) and bisphenol A (BPA) on functionalized biochar (fBC) was systematically examined, with a particular focus on the importance of π-electron-donor (phenanthrene: PHEN) and π-electron-acceptors (1,3-dinitrobenzene: DNB, p-amino benzoic acid: PABA) on sorption. Experimental results suggested that hydrogen-bond formation and π-π-electron-donor-acceptor (EDA) interactions were the dominant sorption mechanisms. The sorption of HOCs decreased as E1 > E2 > EE2 > E3 > BPA based on the Freundlich and Polanyi-Mane-models. The comparison of adsorption coefficient (Kd) normalized against hexadecane-water partition coefficient (KHW) between HOCs and PHEN indicated strong π-π-EDA interactions. π-π interactions among DNB, PHEN and HOCs were verified by the observed upfield frequency (Hz) shifts using proton nuclear magnetic resonance (1H NMR) which identified the specific direction of π-π interactions. UV–vis spectra showed charge-transfer bands for π-donors (PHEN and HOCs) with the model π-acceptor (DNB) also demonstrating the role of π-π EDA interactions. The role of π-electron-donor and π-electron-acceptor domains in fBC was identified at different solution pH

Initial growth of the Northern Lhasaplano, Tibetan Plateau in the early Late Cretaceous (ca. 92 Ma)

Constraining the growth of the Tibetan Plateau in time and space is critical for testing geodynamic models and climatic changes at the regional and global scale. The Lhasa block is a key region for unraveling the early history of the Tibetan Plateau. Distinct from the underlying shallow-marine limestones, the Jingzhushan and Daxiong formations consist of conglomerate and sandstone deposited in alluvial-fan and braided-river systems. Both units were deposited at ca. 92 Ma, as constrained by interbedded tuff layers, detrital zircons, and micropaleontological data. Provenance and paleocurrent analyses indicate that both units were derived from the same elevated source area located in the central-northern Lhasa block. These two parallel belts of coeval conglomerates record a major change in paleogeography of the source region from a shallow seaway to a continental highland, implying initial topographic growth of an area over 160,000 km2, named here the Northern Lhasaplano. The early Late Cretaceous topographic growth of the Northern Lhasaplano was associated with the demise of Tethyan seaways, thrust-belt development, and crustal thickening. The same paleogeographic and paleotectonic changes were recorded earlier in the Northern Lhasaplano than in the Southern Lhasaplano, indicating progressive topographic growth from north to south across the Bangong-Nujiang suture and Lhasa block during the Cretaceous. Similar to the Central Andean Plateau, the Northern Lhasaplano developed by plate convergence above the oceanic Neo-Tethyan subduction zone before the onset of the India-Asia collision

Sorptive removal of dissolved organic matter in biologically-treated effluent by functionalized biochar and carbon nanotubes: Importance of sorbent functionality

© 2018 Elsevier Ltd The sorptive removal of dissolved organic matter (DOM) in biologically-treated effluent was studied by using multi-walled carbon nanotube (MWCNT), carboxylic functionalised MWCNT (MWCNT-COOH), hydroxyl functionalized MWCNT (MWCNT-OH) and functionalized biochar (fBC). DOM was dominated by hydrophilic fraction (79.6%) with a significantly lower hydrophobic fraction (20.4%). The sorption of hydrophobic DOM was not significantly affected by the sorbent functionality (∼10.4% variation) and sorption capacity followed the order of MWCNT > MWCNT-COOH > MWCNT-OH > fBC. In comparison, the sorption of hydrophilic fraction of DOM changed significantly (∼37.35% variation) with the change of sorbent functionality with adsorption capacity decreasing as MWCNT-OH > MWCNT-COOH > MWCNT > fBC. Furthermore, the affinity of adsorbents toward a hydrophilic compound (dinitrobenzene), a hydrophobic compound (pyrene) and humic acid was also evaluated to validate the proposed mechanisms. The results provided important insights on the type of sorbents which are most effective to remove different DOM fractions

The Benefit of Enhanced Contractility in the Infarct Borderzone: A Virtual Experiment

Objectives: Contractile function in the normally perfused infarct borderzone (BZ) is depressed. However, the impact of reduced BZ contractility on left ventricular (LV) pump function is unknown. As a consequence, there have been no therapies specifically designed to improve BZ contractility. We tested the hypothesis that an improvement in borderzone contractility will improve LV pump function. Methods: From a previously reported study, magnetic resonance imaging (MRI) images with non-invasive tags were used to calculate 3D myocardial strain in five sheep 16 weeks after anteroapical myocardial infarction. Animal-specific finite element (FE) models were created using MRI data and LV pressure obtained at early diastolic filling. Analysis of borderzone function using those FE models has been previously reported. Chamber stiffness, pump function (Starling’s law) and stress in the fiber, cross fiber, and circumferential directions were calculated. Animal-specific FE models were performed for three cases: (a) impaired BZ contractility (INJURED); (b) BZ-contractility fully restored (100% BZ IMPROVEMENT); or (c) BZ-contractility partially restored (50% BZ IMPROVEMENT). Results: 100% BZ IMPROVEMENT and 50% BZ IMPROVEMENT both caused an upward shift in the Starling relationship, resulting in a large (36 and 26%) increase in stroke volume at LVPED = 20 mmHg (8.0 ml, p < 0.001). Moreover, there were a leftward shift in the end-systolic pressure volume relationship, resulting in a 7 and 5% increase in LVPES at 110 mmHg (7.7 ml, p < 0.005). It showed that even 50% BZ IMPROVEMENT was sufficient to drive much of the calculated increase in function. Conclusion: Improved borderzone contractility has a beneficial effect on LV pump function. Partial improvement of borderzone contractility was sufficient to drive much of the calculated increase in function. Therapies specifically designed to improve borderzone contractility should be developed

the fire assay reloaded

The fire assay process is still the most accurate and precise method for measuring the gold content in gold alloys. Scanning electron microscopy and transmission electron microscopy have been applied to observe the change in microstructure of the samples undergoing the fire assay process. The performed observations reveal that the microstructure of the specimen is more complex than expected. Before the parting stage, the specimen is not a perfect gold–silver binary alloy but contains also copper–silver oxides and other residual compounds. The parting stage appears to be a dealloying process leading to a nanoporous gold nanostructure. What observed after partition explains the evolution of the shape and colour of the specimen and may allow for a better comprehension of the procedure and an improvement in the method

Colossal magnetocapacitance and scale-invariant dielectric response in phase-separated manganites

Thin films of strongly-correlated electron materials (SCEM) are often grown epitaxially on planar substrates and typically have anisotropic properties that are usually not captured by edge-mounted four-terminal electrical measurements, which are primarily sensitive to in-plane conduction paths. Accordingly, the correlated interactions in the out-of-plane (perpendicular) direction cannot be measured but only inferred. We address this shortcoming and show here an experimental technique in which the SCEM under study, in our case a 600 Angstrom-thick (La1-yPry)0.67Ca0.33MnO3 (LPCMO) film, serves as the base electrode in a metal-insulator-metal (MIM) trilayer capacitor structure. This unconventional arrangement allows for simultaneous determination of colossal magnetoresistance (CMR) associated with dc transport parallel to the film substrate and colossal magnetocapacitance (CMC) associated with ac transport in the perpendicular direction. We distinguish two distinct strain-related direction-dependent insulator-metal (IM) transitions and use Cole-Cole plots to establish a heretofore unobserved collapse of the dielectric response onto a universal scale-invariant power-law dependence over a large range of frequency, temperature and magnetic field.Comment: 32 pages, 4 figures, Supplementary section included, Submitted to Nature Physic

Intergenic regions of Borrelia plasmids contain phylogenetically conserved RNA secondary structure motifs

<p>Abstract</p> <p>Background</p> <p><it>Borrelia </it>species are unusual in that they contain a large number of linear and circular plasmids. Many of these plasmids have long intergenic regions. These regions have many fragmented genes, repeated sequences and appear to be in a state of flux, but they may serve as reservoirs for evolutionary change and/or maintain stable motifs such as small RNA genes.</p> <p>Results</p> <p>In an in silico study, intergenic regions of <it>Borrelia </it>plasmids were scanned for phylogenetically conserved stem loop structures that may represent functional units at the RNA level. Five repeat sequences were found that could fold into stable RNA-type stem loop structures, three of which are closely linked to protein genes, one of which is a member of the <it>Borrelia </it>lipoprotein_1 super family genes and another is the complement regulator-acquiring surface protein_1 (CRASP-1) family. Modeled secondary structures of repeat sequences display numerous base-pair compensatory changes in stem regions, including C-G→A-U transversions when orthologous sequences are compared. Base-pair compensatory changes constitute strong evidence for phylogenetic conservation of secondary structure.</p> <p>Conclusion</p> <p>Intergenic regions of <it>Borrelia </it>species carry evolutionarily stable RNA secondary structure motifs. Of major interest is that some motifs are associated with protein genes that show large sequence variability. The cell may conserve these RNA motifs whereas allow a large flux in amino acid sequence, possibly to create new virulence factors but with associated RNA motifs intact.</p

Diagnosis, treatment and follow-up of 25 patients with melamine-induced kidney stones complicated by acute obstructive renal failure in Beijing Children’s Hospital

A total of 25 Chinese patients aged 6 to 36 months hospitalised at Beijing Children’s Hospital due to melamine-induced kidney stones complicated by acute obstructive renal failure in 2008 were included in a study in order to diagnose and treat these special cases more effectively. Feeding history, clinical presentation, ultrasound findings, treatments and effects were summarised. Twelve to seventeen months follow-up was reported also. Ultrasound examination showed that calculi were located at the kidney and ureters. Stones were composed of both uric acid and melamine in a molar ratio of 1.2:1 to 2.1:1. Treatments providing liquid plus alkalisation of urine proved to be effective in helping the patients pass the stones. Surgical intervention was needed in severe cases. Renal function returned to normal in all 25 patients after various durations of therapy. Sixty-eight percent of the patients expelled all of the calculi within 3 months, 90% in 6 months and 95% in 9 months, without sequelae till now. Melamine-contaminated milk formula can cause kidney stones in infants, which should be diagnosed by feeding history, clinical symptoms and ultrasound examination. Composition of the stones was not only of melamine but also uric acid. Providing liquid orally or intravenously plus alkalisation of urine proved to promote the removal of the stones. Follow-up of 12 to 17 months after discharge showed no sequelae

Effects of dairy intake on weight maintenance

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Molecular Valves for Controlling Gas Phase Transport Made from Discrete Angstrom-Sized Pores in Graphene

An ability to precisely regulate the quantity and location of molecular flux is of value in applications such as nanoscale 3D printing, catalysis, and sensor design. Barrier materials containing pores with molecular dimensions have previously been used to manipulate molecular compositions in the gas phase, but have so far been unable to offer controlled gas transport through individual pores. Here, we show that gas flux through discrete angstrom-sized pores in monolayer graphene can be detected and then controlled using nanometer-sized gold clusters, which are formed on the surface of the graphene and can migrate and partially block a pore. In samples without gold clusters, we observe stochastic switching of the magnitude of the gas permeance, which we attribute to molecular rearrangements of the pore. Our molecular valves could be used, for example, to develop unique approaches to molecular synthesis that are based on the controllable switching of a molecular gas flux, reminiscent of ion channels in biological cell membranes and solid state nanopores.Comment: to appear in Nature Nanotechnolog