The Application of Nanoparticles of Waste Tires in Remediating Boron from Desalinated Water

A waste tire rubber (WTR) collected from the remains discarded tires has exhibited a noteworthy capacity to adsorb Boron. In the current study, the boron adsorption remediation from water at selected pH values, initial boron concentration, contact time, adsorbent dosage and particle size were examined using the WTR, the chemically modified WTR, and nano-WTR. The adsorption isotherms were best fitted to the Freundlich model with a high correlation coefficient (R2 :0.89-0.99), while the adsorption kinetics were satisfactorily described by the pseudo second order kinetic equation with correlation coefficient (R2: 1).The boron remediation using the WTR, the chemically modified-WTR and nano-WTR at low boron concentration (≤ 17.7 mg/L) were comparable with other adsorbents. The highest adsorption capacities for WTR, chemically modified-WTR and nano-WTR at initial concentration of 17.5 mg/L were 16.7 ± 1.3 mg/g, 13.8 ± 1.9 mg/g and 12.7 ± 1.8mg/g, respectively.This publication was made possible by UREP # (19-171-1-031) from the Qatar National Research Fund (a member of Qatar Foundation)

Examination of Glycan Profiles from IgG-Depleted Human Immunoglobulins Facilitated by Microscale Affinity Chromatography

Among the most important proteins involved in disease and healing processes are the immunoglobulins (Igs). Although many of the Igs have been studied through proteomics, aside from IgG, immunoglobulin carbohydrates have not been extensively characterized in different states of health. It seems valuable to develop techniques that permit an understanding of changes in the structures and abundances of Ig glycans in the context of disease onset and progression. We have devised a strategy for characterization of the glycans for the Ig classes other than IgG (i.e., A, D, E, and M) that contain kappa light chains that requires only a few microliters of biological material. First, we designed a microcolumn containing recombinant Protein L that was immobilized on macroporous silica particles. A similarly designed Protein G microcolumn was utilized to first perform an online depletion of the IgG from the sample, human blood serum, and thereby facilitate enrichment of the other Igs. Even though only 3 μL of serum was used in these analyses, we were able to recover a significantly enriched fraction of non-IgG immunoglobulins. The enrichment properties of the Protein L column were characterized using a highly sensitive label-free quantitative proteomics LC-MS/MS approach, and the glycomic profiles of enriched immunoglobulins were measured by MALDI-TOF MS. As a proof of principle, a comparative study was conducted using blood serum from a small group of lung cancer patients and a group of age-matched cancer-free individuals to demonstrate that the method is suitable for investigation of glycosylation changes in disease. The results were in agreement with a glycomic investigation of whole blood serum from a much larger lung cancer cohort

Isolation and Purification of Glycoconjugates from Complex Biological Sources by Recycling High-Performance Liquid Chromatography

Among of the most urgent needs of the glycobiology community is to generate libraries of pure carbohydrate standards. While many oligosaccharides have recently been synthesized, some glycans of biomedical importance are still missing in existing collections or are available in only limited amounts. To address this need, we demonstrate the use of the relatively unexplored technique of recycling high-performance liquid chromatography (R-HPLC) to isolate and purify glycoconjugates from several natural sources. We were able to routinely achieve purities greater than 98%. In several cases, we were able to obtain isomerically pure substances, particularly for glycans with different positional isomerism. These purified substances can then be used in different analytical applications, for example, as standards for mass spectrometry (MS) and capillary-based separations. Moreover, using a bifunctional aromatic amine, the same derivatization agent can be used to enable UV detection of oligosaccharides during their purification and link the isolated molecules to functionalized surfaces and potentially create glycan arrays

Oxidation of Dissolved Elemental Mercury by Thiol Compounds under Anoxic Conditions

Mercuric ion, Hg²⁺, forms strong complexes with thiolate compounds that commonly dominate Hg­(II) speciation in natural freshwater. However, reactions between dissolved aqueous elemental mercury (Hg(0)_aq) and organic ligands in general, and thiol compounds in particular, are not well studied although these reactions likely affect Hg speciation and cycling in the environment. In this study, we compared the reaction rates between Hg(0)_aq and a number of selected organic ligands with varying molecular structures and sulfur (S) oxidation states in dark, anoxic conditions to assess the role of these ligands in Hg(0)_aq oxidation. Significant Hg(0)_aq oxidation was observed with all thiols but not with ligands containing no S. Compounds with oxidized S (e.g., disulfide) exhibited little or no reactivity toward Hg(0)_aq either at pH 7. The rate and extent of Hg(0)_aq oxidation varied greatly depending on the chemical and structural properties of thiols, thiol/Hg ratios, and the presence or absence of electron acceptors. Smaller aliphatic thiols and higher thiol/Hg ratios resulted in higher Hg(0)_aq oxidation rates than larger aromatic thiols at lower thiol/Hg ratios. The addition of electron acceptors (e.g., humic acid) also led to substantially increased Hg(0)_aq oxidation. Our results suggest that thiol-induced oxidation of Hg(0)_aq is important under anoxic conditions and can affect Hg redox transformation and bioavailability for microbial methylation

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg–DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10^–4. Heteroatomic molecules, especially those containing multiple S and N atoms, were found to be among the most important in forming strong complexes with Hg. Major Hg–DOM complexes of C₁₀H₂₁N₂S₄Hg⁺ and C₈H₁₇N₂S₄Hg⁺ were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. These findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg–DOM complexes that affect biological uptake and transformation of Hg in the environment

Global Proteome Response to Deletion of Genes Related to Mercury Methylation and Dissimilatory Metal Reduction Reveals Changes in Respiratory Metabolism in <i>Geobacter sulfurreducens</i> PCA

<i>Geobacter sulfurreducens</i> PCA can reduce, sorb, and methylate mercury (Hg); however, the underlying biochemical mechanisms of these processes and interdependent metabolic pathways remain unknown. In this study, shotgun proteomics was used to compare global proteome profiles between wild-type <i>G. sulfurreducens</i> PCA and two mutant strains: a Δ<i>hgcAB</i> mutant, which is deficient in two genes known to be essential for Hg methylation and a Δ<i>omcBESTZ</i> mutant, which is deficient in five outer membrane <i>c</i>-type cytochromes and thus impaired in its ability for dissimilatory metal ion reduction. We were able to delineate the global response of <i>G. sulfurreducens</i> PCA in both mutants and identify cellular networks and metabolic pathways that were affected by the loss of these genes. Deletion of <i>hgcAB</i> increased the relative abundances of proteins implicated in extracellular electron transfer, including most of the <i>c</i>-type cytochromes, PilA-C, and OmpB, and is consistent with a previously observed increase in Hg reduction in the Δ<i>hgcAB</i> mutant. Deletion of <i>omcBESTZ</i> was found to significantly increase relative abundances of various methyltransferases, suggesting that a loss of dissimilatory reduction capacity results in elevated activity among one-carbon (C1) metabolic pathways and thus increased methylation. We show that <i>G. sulfurreducens</i> PCA encodes only the folate branch of the acetyl-CoA pathway, and proteins associated with the folate branch were found at lower abundance in the Δ<i>hgcAB</i> mutant strain than the wild type. This observation supports the hypothesis that the function of HgcA and HgcB is linked to C1 metabolism through the folate branch of the acetyl-CoA pathway by providing methyl groups required for Hg methylation

Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry

<div><p>Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between –1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.</p></div

Heatmaps for CHO index as a function of molecular mass of extracted SOM compounds before and after the soil warming experiment.

<p>The color bar represents the relative abundance of compounds identified in each of the SOM extract: <b>(a)</b> WSF0, <b>(b)</b> WSF40, <b>(c)</b> BSF0, and <b>(d)</b> BSF40. A positive correlation between CHO index and mass can be observed for mass > 600 Da.</p

Molecular distribution of extracted SOM compounds from a 40-day soil warming incubation experiment.

<p>(a) Box-and-whisker plots of the mass distribution of SOM compounds, including the base-soluble fraction (BSF) at day 0 (BSF0) and day 40 (BSF40) and the water-soluble fraction (WSF) at day 0 (WSF0) and day 40 (WSF40). <b>(b and c)</b> van Krevelen diagram along with CHO index showing the molecular distribution of WSF SOM compounds before (b) and after (c) incubation. <b>(d)</b> Percentages of molecular formulae identified with CHO index values between -2 and 2 before and after soil incubation and are normalized to the total number of formulae displayed in (b) and (c). Compound classes are labeled above colored bars as follows: (A) lipids, (B) unsaturated hydrocarbons, (C) peptides, (D) aminosugars, (E) carbohydrates, (F) lignin, (G) condensed hydrocarbons, (H) tannins.</p

Heatmaps for CHO index as a function of the number of N atoms in extracted SOM compounds identified in (a) WSF0, (b) WSF40, (c) BSF0, and (d) BSF40.

<p>The color bar represents the relative abundance of compounds identified in each of the extract. Note the “island” formations observed for even numbers of N atoms in the BSF samples.</p