The Electrochemical Behaviour of Quaternary Amine-Based Room-Temperature Ionic Liquid N4111(TFSI)

In this study, we used the in situ X-ray photoelectron spectroscopy (XPS), in situ mass spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy methods, for the first time, in a detailed exploration of the electrochemical behaviour of a quaternary amine cation-based room-temperature ionic liquid, butyl-trimethyl-ammonium bis(trifluoromethylsulfonyl)imide (N4111(TFSI)), at the negatively and positively polarised molybdenum carbide-derived micro-mesoporous carbon (mmp-C(Mo2C)) electrodes that can be used as high surface area supporting material for electrocatalysts. The shapes of the C 1s, N 1s, O 1s, F 1s and S 2p XPS spectra were stable for N4111(TFSI) within a very wide potential range. The XPS data indicated the non-specific adsorption character of the cations and anions in the potential range from −2.00 V to 0.00 V. Thus, this region can be used for the detailed analysis of catalytic reaction mechanisms. We observed strong adsorption from 0.00 V to 1.80 V, and at E > 1.80 V, very strong adsorption of the N4111(TFSI) at the mmp-C(Mo2C) took place. At more negative potentials than −2.00 V, the formation of a surface layer containing both N4111+ cations and TFSI− anions was established with the formation of various gaseous compounds. Collected data indicated the electrochemical instability of the N4111+ cation at E < −2.00 V.

The Plasma Proteome

INTODUCTIONThere is an urgent need for a simple and sensitive method to elucidate the human plasma proteome to find markers of disease, or therapeutic factors. Human plasma proteome may be obtained from tryptic peptides that results from native digestion using commonly available, sensitive and robust analytical instruments such as linear quadrupole, tandem mass spectrometers. METHODSThe human plasma proteome was elucidated from three independent human EDTA plasma populations analyzed by precipitation with acetonitrile (ACN) for quaternary amine (QA) micro-chromatography prior to native tryptic digestion for nano liquid chromatography, electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS). The LC-ESI-MS/MS results from authentic plasma and blank injection MS/MS noise controls were parsed into SQL Server along with the fit of the MS/MS spectra from the rigorous X!TANDEM for analysis with the R statistical system. A total of 13,408 gene symbols from tryptic (TRYP) and/or phosphor/tryptic (STYP) peptides showed ≥ 10 peptides with an FDR q ≤ 0.01 from fit of MS/MS spectra by X!TANDEM and were resolved from the null distribution of background noise showed a Chi Square value of χ2 ≥ 9 (p ≤ 0.005). RESULTSNative digestion of human EDTA plasma permitted the identification and quantification of ~ 13,408 protein gene symbols in plasma that showed low FDR (q≤0.01) from the fit of peptide MS/MS spectra and where observation frequency was resolved from the null distribution of random MS/MS spectra of source noise from recordings of blank injections. There was good agreement between the orbital ion trap (OIT) and the sensitive linear ion trap (LIT) as well as the tryptic versus phospho/tryptic peptides. A distinct subset of human cellular proteins showed a variety of specific interaction domains that formed a highly interconnected network in the plasma. DISCUSIONThe agreement between the fit of the peptide MS/MS spectra by the rigorous X!TANDEM algorithm versus random MS/MS spectra controls from blank noise injections demonstrated the reliability of the experimental approach. The highly interconnected network in the plasma confirmed that digestion of plasma under native conditions permitted the identification and quantification of the proteins in a population of human plasma samples. CONCLUSIONIt was feasible to identify more than ten thousand proteins from human plasma with high confidence using a simple linear ion trap after precipitation, quaternary amine chromatography, native digestion and nano spray analysis with a linear quadrupole ion trap.

Enhanced Performance of Zn/Br Flow Battery Using N-Methyl-N-Propylmorpholinium Bromide as Complexing Agent

Redox flow batteries (RFB) are one of the most interesting technologies in the field of energy storage, since they allow the decoupling of power and capacity. Zinc–bromine flow batteries (ZBFB) are a type of hybrid RFB, as the capacity depends on the effective area of the negative electrode (anode), on which metallic zinc is deposited during the charging process. Gaseous bromine is generated at the positive electrode (cathode) during the charging process, so the use of bromine complexing agents (BCA) is very important. These BCAs are quaternary amines capable of complexation with bromine and generating an organic phase, immiscible with the aqueous electrolyte. One of the most commonly used BCAs in RFB technology is 4-methylethylmorpholinium bromide (MEM-Br). In this work, an alternative quaternary amine 4-methylpropylmorpholinium bromide (MPM-Br) was studied. MPM-Br was integrated into the electrolyte, and 200 charge–discharge cycles were performed on the resulting ZBFBs. The obtained results were compared with those when MEM-Br was used, and it was observed that the electrolyte with MPM-Br displays a higher resistance in voltage and higher energy efficiency, making it a promising alternative to MEM-Br.

Identification of Bioactive Compounds from Marine Natural Products and Exploration of Structure-Activity Relationships (SAR)

Marine natural products (MNPs) have been an important and rich source for antimicrobial drug discovery and an effective alternative to control drug resistant infections. Herein, we report bioassay guided fractionation of marine extracts from sponges Lendenfeldia, Ircinia and Dysidea that led us to identify novel compounds with antimicrobial properties. Tertiary amines or quaternary amine salts: aniline 1, benzylamine 2, tertiary amine 3 and 4, and quaternary amine salt 5, along with three known compounds (6–8) were isolated from a crude extract and MeOH eluent marine extracts. The antibiotic activities of the compounds, and their isolation as natural products have not been reported before. Using tandem mass spectrometry (MS) analysis, potential structures of the bioactive fractions were assigned, leading to the hit validation of potential compounds through synthesis, and commercially available compounds. This method is a novel strategy to overcome insufficient quantities of pure material (NPs) for drug discovery and development which is a big challenge for pharmaceutical companies. The antibacterial screening of the marine extracts has shown several of the compounds exhibited potent in-vitro antibacterial activity, especially against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values between 15.6 to 62.5 microg mL−1. Herein, we also report structure activity relationships of a diverse range of commercial structurally similar compounds. The structure-activity relationships (SAR) results demonstrate that modification of the amines through linear chain length, and inclusion of aromatic rings, modifies the observed antimicrobial activity. Several commercially available compounds, which are structurally related to the discovered molecules, showed broad-spectrum antimicrobial activity against different test pathogens with a MIC range of 50 to 0.01 µM. The results of cross-referencing antimicrobial activity and cytotoxicity establish that these compounds are promising potential molecules, with a favourable therapeutic index for antimicrobial drug development. Additionally, the SAR studies show that simplified analogues of the isolated compounds have increased bioactivity.

Phosphonate/zwitterionic/cationic terpolymer as high-efficiency bactericidal and antifouling coating for metallic substrates

Bacteria associated infection is a critical challenge for metallic implants & devices in biomedical applications. Here, we report the phosphonate/zwitterionic/quaternary amine block polymers as a new type of antifouling and...

Identification bioactive compounds from marine microorganism and exploration of structure–activity relationships (SARs)

ABSTRACTMarine natural products (MNPs) have become new strong leads for antimicrobial drug discovery and an effective alternative to control drug resistant infections. Herein we report the bioassay guided fractionation of marine extracts from sponges Lendenfeldia, Ircinia and Dysidea that led us to identify novel compounds with antimicrobial properties. Tertiary amines or quaternary amine salts: anilines 1, benzylamines 2, tertiary amines 3 and 4, and quaternary amine salt 5, along with three known compounds (6-8) were isolated from a crude extract and MeOH eluent marine extracts. The absolute configurations of the new compounds were assigned based on tandem mass spectrometry (MS) analysis. Several of the compounds exhibited potent in-vitro antibacterial activity, especially against Methicillin-resistant Staphylococcus aureus (MRSA) (MICs from 15.6 to 62.5 micro g/mL). Herein, we also, report structure activity relationships of a diverse range of commercial structurally similar compounds. The structure activity relationships (SARs) results clearly demonstrate that modification of the amines through linear chain length, and inclusion of aromatic rings, modifies the observed antimicrobial activity towards different biological activity. Several commercially available compounds, which are structurally related to the molecules we discovered showed broad spectrum antimicrobial activity against different test pathogens with an MIC50 range of 50 to 0.01 microM. The results of cross-referencing antimicrobial activity and cytotoxicity establish that these compounds are promising potential lead molecules, with a favourable therapeutic index for antimicrobial drug development. Additionally, the SAR studies show that simplified analogues of the isolated compounds with increased bioactivity

Development of Nanofluids for the Inhibition of Formation Damage Caused by Fines Migration: Effect of the Interaction of Quaternary Amine (CTAB) and MgO Nanoparticles

Fines migration is a common problem in the oil and gas industry that causes a decrease in productivity. In this sense, the main objective of this study is to develop nanocomposites based on the interaction of quaternary amine (hexadecyltrimethylammonium bromide—CTAB) and MgO to enhance the capacity of retention of fine particles in the porous medium. MgO nanoparticles were synthesized by the sol–gel method using Mg(NO3)2·6H2O as a precursor. Nanoparticles were characterized by dynamic light scattering (DLS), the point of zero charge (pHpzc), thermogravimetric analysis, and Fourier transform infrared spectroscopy (FT-IR). Different nanoparticle sizes of 11.4, 42.8, and 86.2 nm were obtained, which were used for preparing two system nanofluids. These systems were evaluated in the inhibition of fines migration: in the system I MgO nanoparticles were dispersed in a CTAB-containing aqueous solution, and system II consists of a nanocomposite of CTAB adsorbed onto MgO nanoparticles. The fines retention tests were performed using Ottawa sand 20/40 packed beds and fine particles suspensions at concentrations of 0.2% in a mass fraction in deionized water. Individual and combined effects of nanoparticles and CTAB were evaluated in different treatment dosages. The analysis of the interactions between the CTAB and the MgO nanoparticles was carried out through batch-mode adsorption and desorption tests. The best treatment in the system I was selected according to the fines retention capacity and optimized through a simplex-centroid mixture design for mass fractions from 0.0% to 2.0% of both CTAB and MgO nanoparticles. This statistical analysis shows that the optimal concentration of these components is reached for a mass fraction of 0.73% of MgO nanoparticles and 0.74% in mass fraction of CTAB, where the retention capacity of the porous medium increases from 0.02 to 0.39 mg·L−1. Based on the experimental results, the nanofluids combining both components showed higher retention of fines than the systems treated only with CTAB or with MgO nanoparticles, with efficiencies up to 400% higher in the system I and higher up to 600% in the system II. To evaluate the best performance treatment under reservoir conditions, there were developed core flooding tests at fixed overburden pressure of 34.5 MPa, pore pressure at 6.9 MPa and system temperature at 93 °C. Obtaining critical rate increases in 142.8%, and 144.4% for water and oil flow in the presence of the nanofluid. In this sense, this work offers a new alternative for the injection of nanocomposites as a treatment for the problem of fines migration to optimize the productivity of oil and gas wells.