Ionic liquids for the fractionation of microalgae biomass

Microalgae have emerged as one of the most promising sources of renewable biomass. However, considerable challenges must be addressed in order to improve the commercial outlook for the production of commodity chemicals. The largest challenge remains the energy intensive and consequently costly process of microalgae harvesting and drying. Ionic liquids have found a niche application in this area by allowing the extraction of lipids from wet biomass at low temperatures in less time than traditional lipid extraction methods. A number of recent studies have advanced the study of wet extraction of microalgae using ionic liquids and elucidated some of the limitations of this process. However, the most promising avenue for ionic liquid-based wet extraction lies in the fractionation and recovery of multiple biomass products such as lipids, carbohydrates, and carotenoids, in a single process.     

Hydrogenation of cinnamaldehyde over bimetallic Au-Cu/CeO2 catalyst under a mild condition

Bimetallic Au_xCu_y/CeO₂ (x/y=3/1, 1/1, and 1/3) catalysts were prepared by direct anion exchange (DAE), following impregnation (IMP) methods, and used for selective hydrogenation of cinnamaldehyde. The effects of pretreatments, such as calcination or reduction on the catalytic activities of these catalysts were investigated. XRD and HRTEM showed that for the reduced catalysts, there is the formation of an Au-Cu alloy. HAADF-STEM displayed that reduction pretreatment leads to a very homogenous distribution of Au and Cu on the external catalyst surface. Reaction parameters, such as CAL concentration, the stirring speed, nature of the solvent influence the catalytic activities. Pretreatments lead to a major effect on CAL conversion and HCAL selectivity. Catalysts Au_xCu_y/CeO₂pretreated under reduction display higher CAL conversion and HCAL selectivity than that of under calcination mainly due to the synergistic effect resulting in a formation of Au-Cu alloy.     

Are Clusters Important in Understanding the Mechanisms in Atmospheric Pressure Ionization? Part 1: Reagent Ion Generation and Chemical Control of Ion Populations

It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region.

Native Electrospray Mass Spectrometry of DNA G-Quadruplexes in Potassium Solution

A commonly used electrolyte in electrospray mass spectrometry (ESI-MS) of biomolecules is ammonium acetate (NH₄OAc). Although some nucleic acid structures such as duplexes require only proper physiological ionic strength (whatever the monovalent ions) to be properly folded in ESI-MS conditions, the folding of some other nucleic acid structures such as DNA G-quadruplexes also depends on direct binding of specific cations. Here, we developed ESI-MS compatible conditions that allow one to observe DNA G-quaduplexes with K⁺ ions specifically bound between G-quartets. NH₄OAc was replaced with trimethylammonium acetate (TMAA), at concentrations up to 150 mM to provide physiological ionic strength, and the solution was doped with KCl at concentrations up to 1 mM. The trimethylammonium ion is too large to coordinate between G-quartets, where only K⁺ ions bind. Compared with the equivalent NH₄OAc/KCl mixtures, the TMAA/KCl mixtures provide cleaner spectra by suppressing the nonspecific adducts, and favor the formation of similar stacking arrangements as in 100 mM KCl (physiologically relevant cation) for the polymorphic human telomeric DNA G-quadruplexes. This new sample preparation method can be exploited to determine the number of potassium binding sites in new sequences, to screen ligand binding to the structures favored in potassium, and to transfer potassium-bound G-quadruplexes to the mass spectrometer for gas-phase structural probing, as illustrated herein with ion mobility spectrometry experiments.

A Racemic and Enantiopure Unsymmetric Diiron(III) Complex with a Chiral o‐Carborane‐Based Pyridylalcohol Ligand: Combined Chiroptical,Magnetic, and Nonlinear Optical Properties

The design of molecule‐based systems combining magnetic, chiroptical and second‐order optical nonlinear properties is still very rare. We report an unusually unsymmetric diiron(III) complex 1 , in which three bulky chiral carboranylpyridinealkoxide ligands ( o CB hmp^?) bridge both metal ions and the complex shows the above‐mentioned properties. The introduction of o‐carborane into the 2‐(hydroxymethyl)pyridine (hmpH) architecture significantly alters the coordination of the simple or aryl‐substituted 2‐hmpH. The unusual architecture observed in 1 seems to be triggered by the poor nucleophilicity of our alkoxide ligand ( o CB hmp^?). A very rare case of spontaneous resolution takes place on precipitation or exposure to solvent vapor for the bulk compound, as confirmed by a combination of single‐crystal and powder X‐ray diffraction, second‐harmonic generation, and circular dichroism. The corresponding enantiopure complexes (+) 1 and (?) 1 have also been synthesized and fully characterized. This research provides a new building block with unique geometry and electronics to construct coordination complexes with multifunctional properties.     

The impact behavior of polyethylene: A new vista

Recent advances in the analysis of the fracture behavior of polyethylene have been reviewed specifically to establish the nature and extent of morphological changes. It has been shown that in the case of linear low-density polyethylene (LLDPE), reorganization and orientation of lamellae occur in the shear lips region, the pattern being influenced by differences in molecular structure. Crazes, on the other hand, are characterized by the presence of voiding, with no significant effect on the original morphology.     

Anti-Inflammatory Effects of the Iron Chelator,DIBI, in Experimental Acute Lung Injury

Iron plays a critical role in the immune response to inflammation and infection due to its role in the catalysis of reactive oxygen species (ROS) through the Haber-Weiss and Fenton reactions. However, ROS overproduction can be harmful and damage healthy cells. Therefore, iron chelation represents an innovative pharmacological approach to limit excess ROS formation and the related pro-inflammatory mediator cascades. The present study was designed to investigate the impact of the iron chelator, DIBI, in an experimental model of LPS-induced acute lung injury (ALI). DIBI was administered intraperitoneally in the early and later stages of lung inflammation as determined by histopathological evaluation. We found that lung tissues showed significant injury, as well as increased NF-κB p65 activation and significantly elevated levels of various inflammatory mediators (LIX, CXCL2, CCL5, CXCL10, IL-1𝛽, IL-6) 4 h post ALI induction by LPS. Mice treated with DIBI (80 mg/kg) in the early stages (0 to 2 h) after LPS administration demonstrated a significant reduction of the histopathological damage score, reduced levels of NF-κB p65 activation, and reduced levels of inflammatory mediators. Intravital microscopy of the pulmonary microcirculation also showed a reduced number of adhering leukocytes and improved capillary perfusion with DIBI administration. Our findings support the conclusion that the iron chelator, DIBI, has beneficial anti-inflammatory effects in experimental ALI.