Decane

MgAl-Layered-Double-Hydroxide/Sepiolite Composite Membrane for High-Performance Water Treatment Based on Layer-by-Layer Hierarchical Architectures.[Pubmed:30960508]

Polymers (Basel). 2019 Mar 20;11(3). pii: polym11030525.

One of the major challenges in the removal of organic pollutants is to design a material with high efficiency and high flux that can remove both cationic and anionic dyes, oil-in-water (O/W) emulsion and heavy metal ions. Herein, we constructed novel chemically stabilized MgAl-layered-double-hydroxide/sepiolite (MgAl-LDH/Sep) composite membranes via 3D hierarchical architecture construction methods. These membranes were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD), etc. Benefiting from the presence of hydrophilic functional groups on the surface of the film, the membranes show an enhanced water flux (~1200 L.m(-2) h(-1)), while keeping a high dyes rejection (above 99.8% for anionic and cationic dyes). Moreover, the CA membrane coupled with MgAl-LDH/Sep exhibits a multifunctional characteristic for the efficient removal of mesitylene (99.2%), petroleum ether (99.03%), Decane (99.07%), kerosene (99.4%) and heavy metal ion in water due to the layer-by-layer sieving. This hierarchical architecture is proved to have excellent environmental and chemical stability. Therefore, the membrane has potential in the treatment of sewage wastewater.

Correlating the effect of co-monomer content with responsiveness and interfacial activity of soft particles with stability of corresponding smart emulsions.[Pubmed:30927593]

J Colloid Interface Sci. 2019 Mar 23;546:293-302.

HYPOTHESIS: This study presents the synthesis and characterization of Poly(N-isopropylacrylamide)-co-methacrylic acid (PNIPAM-co-MAA) based multi-responsive soft microgel particles employed as "smart emulsifiers" for controlled stabilization and breakage of the Decane-in-water Pickering emulsions. These soft microgel particles can act as reversible stabilizers, i.e. they can either stay at the oil-water interface by supporting emulsion formation or preventing aggregates; while triggering demulsification can be controlled by varying the temperature, pH or ionic strength of the microgel system. EXPERIMENTS: Dynamic light scattering was applied to observe the variation in hydrodynamic radius of the particles as a function of temperature and pH of the multi-responsive microgel system. Microgel composition was varied in terms of MAA-content and influence of this variation on their thermo-sensitivity and pH responsiveness as well as on the stability of corresponding emulsions was evaluated. FINDINGS: The microgel particles with highest MAA content showed a significant impact on multi-responsive behaviour. Thermal sensitivity is pH dependent under acidic conditions but this dependence is gradually reduced as the pH increases above 7.5. On the other hand, pH-responsiveness is enhanced with the rise in temperature and stable emulsions were formed under highly alkaline conditions even the temperature was far above the volume phase transition temperature (VPTT). Understanding the correlation of stimuli responsiveness at interface with the emulsion stability would help to fabricate and design novel smart Pickering emulsions with better control over desired properties.

Super-resolution microscopy on single particles at fluid interfaces reveals their wetting properties and interfacial deformations.[Pubmed:30896703]

Nanoscale. 2019 Apr 4;11(14):6654-6661.

Solid particles adsorbed at fluid interfaces are crucial for the mechanical stability of Pickering emulsions. The key parameter which determines the kinetic and thermodynamic properties of these colloids is the particle contact angle, theta. Several methods have recently been developed to measure the contact angle of individual particles adsorbed at liquid-liquid interfaces, as morphological and chemical heterogeneities at the particle surface can significantly affect theta. However, none of these techniques enables the simultaneous visualization of the nanoparticles and the reconstruction of the fluid interface to which they are adsorbed, in situ. To tackle this challenge, we utilize a newly developed super-resolution microscopy method, called iPAINT, which exploits non-covalent and continuous labelling of interfaces with photo-activatable fluorescent probes. Herewith, we resolve with nanometer accuracy both the position of individual nanoparticles at a water-octanol interface and the location of the interface itself. First, we determine single particle contact angles for both hydrophobic and hydrophilic spherical colloids. These experiments reveal a non-negligible dependence of theta on particle size, from which we infer an effective line tension, tau. Next, we image elliptical particles at a water-Decane interface, showing that the corresponding interfacial deformations can be clearly captured by iPAINT microscopy.

A miniaturized push-pull-perfusion probe for few-second sampling of neurotransmitters in the mouse brain.[Pubmed:30869670]

Lab Chip. 2019 Apr 9;19(8):1332-1343.

Measuring biomolecule concentrations in the brain of living animals, in real time, is a challenging task, especially when detailed information at high temporal resolution is also required. Traditionally, microdialysis probes are used that generally have sampling areas in the order of about 1 mm2, and provide information on concentrations with a temporal resolution of at least several minutes. In this paper, we present a novel miniaturized push-pull perfusion sampling probe that uses an array of small 3 mum-wide sampling channels to sample neurotransmitters at a typical recovery rate of 61%, with a reduced risk of clogging. The added feature to segment the dialysate inside the probe into small water-in-Decane droplets enables the detection of concentrations with a temporal resolution of a few seconds. Here we used the probe for in vivo recordings of neurotransmitter glutamate released upon electrical stimulation in the brain of a mouse to demonstrate the feasibility of the probe for real-time neurochemical brain analysis.

Equilibrium configurations and capillary interactions of Janus dumbbells and spherocylinders at fluid-fluid interfaces.[Pubmed:30854540]

Soft Matter. 2019 Mar 20;15(12):2638-2647.

We numerically investigate the adsorption of a variety of Janus particles (dumbbells, elongated dumbbells and spherocylinders) at a fluid-fluid interface by using a numerical method that takes into account the interfacial deformations. We first determine the equilibrium configuration of a single adsorbed particle, and we find that the overall shape of the induced deformation field has a strong hexapolar mode while non-Janus particles of the same shape do not induce any interfacial deformation. We then calculate the capillary interactions between two Janus spherocylinders adsorbed at an interface. The hexapolar deformation field induces capillary attractions for laterally aligned Janus spherocylinders and repulsions for laterally anti-aligned ones. We also experimentally synthesize micrometer-sized charged Janus dumbbells and let them adsorb at a water-Decane interface. After several hours we observe the formation of aggregates of dumbbells predominantly induced by interactions that appear to be capillary in nature. Our Janus dumbbells attach laterally and are all aligned, as predicted by our numerical calculations.

Switchable Oil-in-Water Emulsions Stabilized by Like-Charged Surfactants and Particles at Very Low Concentrations.[Pubmed:30807183]

Langmuir. 2019 Mar 19;35(11):4058-4067.

A novel CO2/N2 switchable n-Decane-in-water emulsion was prepared, which is stabilized by a CO2/N2 switchable surfactant [ N'-dodecyl- N, N-dimethylacetamidine (DDMA)] in cationic form in combination with positively charged alumina nanoparticles at concentrations as low as 0.01 mM and 0.001 wt %, respectively. The particles do not adsorb at the oil-water interface but remain dispersed in the aqueous phase between surfactant-coated droplets. A critical zeta potential of the particles of ca. +18 mV is necessary for the stabilization of the novel emulsions, suggesting that the electrical double-layer repulsions between particles and between particles and oil droplets are responsible for their stability. By bubbling N2 into the emulsions, demulsification occurs following transformation of DDMA molecules from the surface-active cationic form to the surface-inactive neutral form and desorption from the oil-water interface. Bubbling CO2 into the demulsified mixtures, cationic DDMA molecules are re-formed, which adsorb to the droplet interfaces, ensuring stable emulsions after homogenization. Compared with Pickering emulsions and traditional emulsions, the amount of switchable surfactant and number of like-charged particles required for stabilization are significantly reduced, which is economically and environmentally benign for practical applications.

Probing electromechanical behaviors by datacube piezoresponse force microscopy in ambient and aqueous environments.[Pubmed:30780144]

Nanotechnology. 2019 Jun 7;30(23):235701.

For assisting the in-depth investigations of widespread electromechanical phenomena in functional materials, piezoresponse force microscopy (PFM) has gradually evolved to realize full information-flow acquisition and fit the conductive liquid working environments. Here, we designed data cube (DCUBE) based PFM to collect the electromechanical effect into a high-dimensional array of piezoresponse by adding ac bias with a wide range of frequencies to the probe. The electromechanical and mechanical spectra can be consecutively extracted at each pixel in the intermittent-contact mode. High-resolution ferroelectric domains of the poled LiNbO3 were mapped, corresponding to the ideal phase contrasts of about 180 degrees in air, Decane, and deionized water. Rich information detection and non-contact mode in DCUBE-PFM bring many merits on the electromechanical characterizations, especially for elastic-inhomogeneous surfaces and soft materials. Moreover, we systematically reveal the Debye screening effect and time-resolved field-oriented ion dynamics, which play crucial roles in the reduction of PFM spatial resolution in electrolytes. These physical discussions provide strategies to further realize high-resolution electromechanical imaging in highly conductive liquid environments.

Synthetic Studies toward Plumisclerin A.[Pubmed:30767543]

Org Lett. 2019 Mar 1;21(5):1384-1387.

A concise approach to synthesize the tetracyclic framework of the marine diterpenoid plumisclerin A is described. Starting from commercially available iridoid genipin, a highly selective intermolecular Diels-Alder reaction was utilized to construct the A/B/C tricycle. Later, a four-step sequence involving stereoselective epoxidation and Dauben oxidative rearrangement was developed to introduce the requisite enone moiety. The unique tricyclo[4,3,1,0(1,5)]Decane motif was successfully forged via a late-stage SmI2-mediated reductive coupling.

Hydrogenated Diglucose Detergents for Membrane-Protein Extraction and Stabilization.[Pubmed:30767533]

Langmuir. 2019 Mar 26;35(12):4287-4295.

We report herein the design and synthesis of a novel series of alkyl glycoside detergents consisting of a nonionic polar headgroup that comprises two glucose moieties in a branched arrangement (DG), onto which octane-, Decane-, and doDecanethiols were grafted leading to ODG, DDG, and DDDG detergents, respectively. Micellization in aqueous solution was studied by isothermal titration calorimetry, (1)H NMR spectroscopy, and surface tensiometry. Critical micellar concentration values were found to decrease by a factor of approximately 10 for each pair of methylene groups added to the alkyl chain, ranging from approximately 0.05 to 9 mM for DDDG and ODG, respectively. Dynamic light scattering and analytical ultracentrifugation sedimentation velocity experiments were used to investigate the size and composition of the micellar aggregates, showing that the aggregation number significantly increased from approximately 40 for ODG to approximately 80 for DDDG. All new compounds were able to solubilize membrane proteins (MPs) from bacterial membranes, insect cells, as well as the Madin-Darby canine kidney cells. In particular, native human adenosine receptor (A2AR) and bacterial transporter (BmrA) were solubilized efficiently. Striking thermostability improvements of +13 and +8 degrees C were observed when ODG and DDG were, respectively, applied to wild-type and full-length A2AR. Taken together, this novel detergent series shows promising detergent potency for solubilization and stabilization of membrane proteins (MPs) and thus makes a valuable addition to the chemical toolbox available for extracting and handling these important but challenging MP targets.

Alstonlarsines A-D, Four Rearranged Indole Alkaloids from Alstonia scholaris.[Pubmed:30758208]

Org Lett. 2019 Mar 1;21(5):1471-1474.

Four indole alkaloids, alstonlarsines A-D (1-4), were isolated from Alstonia scholaris and structurally characterized. Compound 1 possesses a new carbon skeleton with a cage-shaped 9-azatricyclo[4.3.1.0(3,8)]Decane motif, and compounds 2-4 feature a rare carbon skeleton that was found in nature for the first time. Plausible biosynthetic routes for 1-4 are proposed. Compound 1 showed DRAK2 inhibitory activity with an IC50 value of 11.65 +/- 0.63 muMu.

Pulmonary Oxygen Toxicity in Navy Divers: A Crossover Study Using Exhaled Breath Analysis After a One-Hour Air or Oxygen Dive at Nine Meters of Sea Water.[Pubmed:30740057]

Front Physiol. 2019 Jan 25;10:10.

Introduction: Exposure to hyperbaric hyperoxic conditions can lead to pulmonary oxygen toxicity. Although a decrease in vital capacity has long been the gold standard, newer diagnostic modalities may be more accurate. In pulmonary medicine, much research has focussed on volatile organic compounds (VOCs) associated with inflammation in exhaled breath. In previous small studies after hyperbaric hyperoxic exposure several methyl alkanes were identified. This study aims to identify which VOCs mark the development of pulmonary oxygen toxicity. Methods: In this randomized crossover study, 12 divers of the Royal Netherlands Navy made two dives of one hour to 192.5 kPa (comparable to a depth of 9 msw) either with 100% oxygen or compressed air. At 30 min before the dive, and at 30 min and 1, 2, 3, and 4 h post-dive, exhaled breath was collected and followed by pulmonary function tests (PFT). Exhaled breath samples were analyzed using gas chromatography-mass spectrometry (GC-MS). After univariate tests and correlation of retention times, ion fragments could be identified using a standard reference database [National Institute of Standards and Technology (NIST)]. Using these fragments VOCs could be reconstructed, which were then tested longitudinally with analysis of variance. Results: After GC-MS analysis, seven relevant VOCs (generally methyl alkanes) were identified. Decane and decanal showed a significant increase after an oxygen dive (p = 0.020 and p = 0.013, respectively). The combined intensity of all VOCs showed a significant increase after oxygen diving (p = 0.040), which was at its peak (+35%) 3 h post-dive. Diffusion capacity of nitric oxide and alveolar membrane capacity showed a significant reduction after both dives, whereas no other differences in PFT were significant. Discussion: This study is the largest analysis of exhaled breath after in water oxygen dives to date and the first to longitudinally measure VOCs. The longitudinal setup showed an increase and subsequent decrease of exhaled components. The VOCs identified suggest that exposure to a one-hour dive with a partial pressure of oxygen of 192.5 kPa damages the phosphatidylcholine membrane in the alveoli, while the spirometry and diffusion capacity show little change. This suggests that exhaled breath analysis is a more accurate method to measure pulmonary oxygen toxicity.

(+)- and (-)-Preuisolactone A: A Pair of Caged Norsesquiterpenoidal Enantiomers with a Tricyclo[4.4.0(1,6).0(2,8)]decane Carbon Skeleton from the Endophytic Fungus Preussia isomera.[Pubmed:30730149]

Org Lett. 2019 Feb 15;21(4):1078-1081.

A pair of enantiomeric norsesquiterpenoids, (+)- and (-)-preuisolactone A (1) [(+)-1 and (-)-1)] featuring an unprecedented tricyclo[4.4.0(1,6).0(2,8)]Decane carbon scaffold were isolated from Preussia isomera. Their structures were determined by spectroscopic and computed methods and X-ray crystallography. Compounds (+)-1 and (-)-1 are two rare naturally occurring sesquiterpenoidal enantiomers. A plausible biosynthetic pathway for 1 is proposed. Additionally, (+/-)-1 exhibited remarkable antibacterial activity against Micrococcus luteus with an MIC value of 10.2 muM.

High performance liquid chromatography of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) - Comparison of different solvent systems.[Pubmed:30718060]

J Chromatogr A. 2019 Jan 25. pii: S0021-9673(19)30115-3.

A series of ethylene/1-octene copolymers with different chemical composition was separated in six binary mobile phases using solvent gradients and a column packed with porous graphite Hypercarb(). It was found that the elution volumes of the samples were to a larger extent influenced by the choice of desorption promoting solvent (desorli: 1,2-dichlorobenzene vs. 1,2,4-trichlorobenzene) than by the choice of adsorption promoting solvent (2-ethyl-1-hexanol, 1-decanol, n-Decane). Elution volumes increased with decreasing number of chlorine atoms in the desorlis as well as with increasing polarity of the adsorlis. The resolution of HPLC systems depended pronouncedly on the choice of solvent pair: While in the majority of the tested HPLC systems, the chromatograms of the polymer samples indicate a shoulder, in n-Decane-->TCB the samples eluted without indication of a shoulder. In addition to the influence of different solvents on the samples elution behavior, the response of the employed detector, an evaporative light scattering detector (ELSD), was investigated. Its response was found to depend pronouncedly on the nature of the used solvents. Overall, the solvent pair 1-decanol-->TCB appears to be the optimal compromise between the considered parameters and thus the best choice for HPLC of ethylene/1-octene copolymers.

Mechanistic Study of Wettability Changes on Calcite by Molecules Containing a Polar Hydroxyl Functional Group and Nonpolar Benzene Rings.[Pubmed:30681863]

Langmuir. 2019 Feb 19;35(7):2527-2537.

Oil extraction efficiency strongly depends on the wettability status (oil- vs water-wet) of reservoir rocks during oil recovery. Aromatic compounds with polar functional groups in crude oil have a significant influence on binding hydrophobic molecules to mineral surfaces. Most of these compounds are in the asphaltene fraction of crude oil. This study focuses on the hydroxyl functional group, an identified functional group in asphaltenes, to understand how the interactions between hydroxyl groups in asphaltenes and mineral surfaces begin. Phenol and 1-naphthol are used as asphaltene surrogates to model the simplest version of asphaltenes. Adsorption of oil molecules on the calcite {1014} surface is described using static quantum-mechanical density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations. DFT calculations indicate that adsorption of phenol and 1-naphthol occurs preferentially between their hydroxyl group and calcite step edges. 1-Naphthol adsorbs more strongly than phenol, with different adsorption geometries due to the larger hydrophobic part of 1-naphthol. MD simulations show that phenol can behave as an agent to separate oil from the water phase and to bind the oil phase to the calcite surface in the water/oil mixture. In the presence of phenol, partial separation of water/oil with an incomplete lining of phenol at the water/oil boundary is observed after 0.2 ns. After 1 ns, perfect separation of water/oil with a complete lining of phenol at the water/oil boundary is observed, and the calcite surface becomes oil-wet. Phenol molecules enclose Decane molecules at the water-Decane boundary preventing water from repelling Decane molecules from the calcite surface and facilitate further accumulation of hydrocarbons near the surface, rendering the surface oil-wet. This study indicates phenol and 1-naphthol to be good proxies for polar components in oil, and they can be used in designing further experiments to test pH, salinity, and temperature dependence to improve oil recovery.

Septosones A-C, in Vivo Anti-inflammatory Meroterpenoids with Rearranged Carbon Skeletons from the Marine Sponge Dysidea septosa.[Pubmed:30676034]

Org Lett. 2019 Feb 1;21(3):767-770.

Three unusual meroterpenoids, septosones A-C (1-3), were isolated from the marine sponge Dysidea septosa. The structures were determined by analysis of spectroscopic data combined with single-crystal X-ray diffraction and ECD calculations. Septosone A (1) features an unprecedented "septosane" carbon skeleton, whereas septosones B (2) and C (3) share a rare spiro[4.5]Decane motif. Septosone A showed in vivo anti-inflammatory activity in CuSO4-induced transgenic fluorescent zebrafish likely through inactivation of the NF-kappaB signaling pathway.