These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

21 CFR 172.165 - Quaternary ammonium chloride combination.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 true Quaternary ammonium chloride combination. 172.165 ...Preservatives § 172.165 Quaternary ammonium chloride combination. The food additive, quaternary ammonium chloride combination, may be...

2010-04-01

2

40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides...Substances § 721.10154 Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides...chemical substance identified as quaternary ammonium compounds, dicoco...

2010-07-01

3

40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides... § 721.10154 Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides...substance identified as quaternary ammonium compounds, dicoco alkyldimethyl,...

2011-07-01

4

Algicidal Activity of a Surface-Bonded Organosilicon Quaternary Ammonium Chloride  

PubMed Central

The hydrolysis product of a quaternary amine-containing organosilicon salt, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was found to exhibit algicidal activity while chemically bonded to a variety of substrates. Six representative species of Chlorophyta, Cyanophyta, and Chrysophyta were used to evaluate the algicidal activity. Substrate-bonded 14C-labeled organosilicon quaternary ammonium salt when attached to nonwoven fibers was durable to repeated washings, and algicidal activity could not be attributed to slow release of the chemical. Images PMID:4632852

Walters, P. A.; Abbott, E. A.; Isquith, A. J.

1973-01-01

5

Surface-Bonded Antimicrobial Activity of an Organosilicon Quaternary Ammonium Chloride  

PubMed Central

The hydrolysis product of 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride exhibited antimicrobial activity against a broad range of microorganisms while chemically bonded to a variety of surfaces. The chemical was not removed from surfaces by repeated washing with water, and its antimicrobial activity could not be attributed to a slow release of the chemical, but rather to the surface-bonded chemical. Images PMID:4650597

Isquith, A. J.; Abbott, E. A.; Walters, P. A.

1972-01-01

6

Determination of the quaternary ammonium compounds dequalinium and cetylpyridinium chlorides in candy-based lozenges by high-performance liquid chromatography.  

PubMed

The retention behavior of the quaternary ammonium compounds benzalkonium chloride, cetylpyridinium chloride and dequalinium chloride on a 100 x 4.6 mm id cyanopropyl stationary phase column is reported as a function of organic modifier and ionic hydrophobic mobile phase additive concentrations. Optimum liquid chromatographic mobile phases using different mobile phase additives are reported which are suitable for the determination of cetylpyridinium chloride and dequalinium chloride in a variety of candy-based lozenge formulations. The quantitative aspects of assays based on the separation of active ingredients and formulation excipients were established. The generality of application of the assay methods was evaluated by determining the quaternary ammonium content of different lozenges and comparing the values obtained with the stated dose. PMID:9374026

Taylor, R B; Toasaksiri, S; Reid, R G; Wood, D

1997-09-01

7

The toxicity of the quaternary ammonium compound benzalkonium chloride alone and in mixtures with other anionic compounds to bacteria in test systems with Vibrio fischeri and Pseudomonas putida.  

PubMed

Mixtures of chemicals are present in the aquatic environment but standard testing methods assess only single compounds. One aspect of this question is the importance of the formation of ionic pairs, for example from quaternary ammonium compounds with organic anions, and the significance of the ionic pairs for bacterial toxicity in the aquatic environment. The aim of the present study was to investigate the toxicity of the cationic quaternary ammonium compound benzalkonium chloride (BAC) against aquatic bacteria in the presence of substances commonly found in wastewater, such as the anionic surfactant linear alkylbenzene sulfonate (LAS), naphthalene sulfonic acid (NSA), sodium dodecylsulfonate (SDS), and benzene sulfonic acid (BSA). The growth inhibition test with Pseudomonas putida and the Vibrio fischeri luminescent inhibition test were used to determine the toxicity of single compounds and compound mixtures. The results found in this study indicate that ion pair formation is of minor significance under the test conditions applied here. PMID:18272223

Sütterlin, H; Alexy, R; Kümmerer, K

2008-10-01

8

Formation of a bioconjugate composed of hemin, smectite, and quaternary ammonium chloride that is soluble and active in hydrophobic media.  

PubMed

Hemin (Fe(3+)) was adsorbed onto synthetic smectite (clay mineral) intercalated with a quaternary alkenylammonium compound, dioleyldimethylammonium chloride (DOA), to form a hemin-smectite-DOA conjugate. The hemin-smectite-DOA conjugate was soluble in organic solvents such as benzene and toluene to form a transparent colloidal solution with a light yellow color. Its absorption spectrum in benzene showed two bands, 600 and 568 nm, in the visible region and a sharp Soret band at 400 nm with the molar extinction coefficient of 7.5 x 10(4) M(-1) cm(-1). The formation of the conjugate of smectite and DOA was confirmed by X-ray diffraction analysis: the basal spacing, d(001), of hemin-smectite-DOA conjugate was 19 A which is an expansion of the interlayer space by 5 A based upon the basal spacing of smectite of 14 A. Hemin-smectite-DOA conjugate catalyzed the peroxidase-like reaction in organic solvents using benzoyl peroxide as the hydrogen acceptor and leucocrystal violet as the hydrogen donor. The temperature-dependent peroxidase-like activity of the conjugate was compared with peroxidase activity of horseradish peroxidase. The hemin-smectite-DOA conjugate exhibited higher activity as the temperature was increased from 30 to 70 degrees C, while horseradish peroxidase activity was reduced as the temperature was increased. PMID:11906251

Kurosawa, Masaru; Itoh, Tetsuji; Kodera, Yoh; Matsushima, Ayako; Hiroto, Misao; Nishimura, Hiroyuki; Inada, Yuji

2002-01-01

9

40 CFR 721.4095 - Quaternary ammonium alkyltherpropyl trialkylamine halides.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Quaternary ammonium alkyltherpropyl trialkylamine halides...Substances § 721.4095 Quaternary ammonium alkyltherpropyl trialkylamine halides...substances identified generically as quaternary ammonium alkyltherpropyl trialkylamine...

2010-07-01

10

40 CFR 721.4467 - Quaternary ammonium hydroxide.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Quaternary ammonium hydroxide. 721.4467 Section 721...Substances § 721.4467 Quaternary ammonium hydroxide. (a) Chemical substance...identified generically as a quaternary ammonium hydroxide (PMN P-95-1806)...

2010-07-01

11

40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.  

Code of Federal Regulations, 2010 CFR

... false Ethoxylated alkyl quaternary ammonium compound. 721.655 Section 721...655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical substance...generically as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is...

2010-07-01

12

40 CFR 721.10511 - Quaternary ammonium salts (generic).  

...2014-07-01 false Quaternary ammonium salts (generic). 721.10511 Section 721...Substances § 721.10511 Quaternary ammonium salts (generic). (a) Chemical substance...identified generically as quaternary ammonium salts (PMNs P-07-320,...

2014-07-01

13

40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.  

Code of Federal Regulations, 2011 CFR

...Ethoxylated alkyl quaternary ammonium compound. 721.655 Section 721.655 ...Ethoxylated alkyl quaternary ammonium compound. (a) Chemical substance and significant...ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject...

2011-07-01

14

Bacterial adhesion inhibition of the quaternary ammonium functionalized silica nanoparticles.  

PubMed

Quaternary ammonium compounds have been considered as excellent antibacterial agents due to their effective biocidal activity, long term durability and environmentally friendly performance. In this work, 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride as a quaternary ammonium silane was applied for the surface modification of silica nanoparticles. The quaternary ammonium silane provided silica surface with hydrophobicity and antibacterial properties. In addition, the glass surface which was coated with the surface modified silica nanoparticles presented bacterial growth inhibition activity. For comparison of bacterial growth resistance, hydrophobic silane (alkyl functionalized silane) modified silica nanoparticles and pristine silica nanoparticles were prepared. As a result of bacterial adhesion test, the quaternary ammonium functionalized silica nanoparticles exhibited the enhanced inhibition performance against growth of Gram-negative Escherichia coli (96.6%), Gram-positive Staphylococcus aureus (98.5%) and Deinococcus geothermalis (99.6%) compared to pristine silica nanoparticles. These bacteria resistances also were stronger than that of hydrophobically modified silica nanoparticles. It could be explained that the improved bacteria inhibition performance originated from the synergistic effect of hydrophobicity and antibacterial property of quaternary ammonium silane. Additionally, the antimicrobial efficacy of the fabricated nanoparticles increased with decreasing size of the nanoparticles. PMID:21115282

Song, Jooyoung; Kong, Hyeyoung; Jang, Jyongsik

2011-02-01

15

Quaternary Ammonium Compounds as Water Channel Blockers  

E-print Network

, West Mains Road, EH9 3JJ Scotland, United Kingdom Excessive water uptake through Aquaporins (AQP) canQuaternary Ammonium Compounds as Water Channel Blockers SPECIFICITY, POTENCY, AND SITE OF ACTION, potency, and binding site of tetraethyl- ammonium (TEA) to block Aquaporin water permeability. Using

de Groot, Bert

16

[Resistance of Staphylococcus aureus strains to quaternary ammonium compounds and chlorhexidine].  

PubMed

The level of susceptibility of 90 different Staphylococcus aureus strains to chosen quaternary ammonium compounds: cetyltrimethyl ammonium bromide, benzalkonium chloride and benzethonium chloride as well as to chlorhexidine digluconate were examined. The examined strains consist of three groups: hospital originated MRSA, hospital originated MSSA and non-hospital MSSA. The significant differences between these groups were observed in they susceptibility to the investigated disinfectants. The obtained MIC values showed that the most resistant were hospital MRSA strains, where 55% was estimated as resistant to cetyltrimethyl ammonium bromide, 72% were resistant to benzalkonium chloride and benzethonium chloride and 7% were resistant to chlorhexidine digluconate. Among hospital originated MSSA 3% of strains were resistant to cetyltrimethyl ammonium bromide and 6% were resistant to benzalkonium chloride and benzethonium chloride. 14% non-hospital S. aureus strains were resistant to benzalkonium chloride and benzethonium chloride. None were resistant to chlorhexidine digluconate or cetyltrimethyl ammonium bromide. PMID:12632654

Stefa?ska, Joanna; M?ynarczyk, Grazyna; M?ynarczyk, Andrzej; Staro?ciak, Bohdan; ?uczak, Miros?aw

2002-01-01

17

Exposure to common quaternary ammonium disinfectants decreases fertility in mice.  

PubMed

Quaternary ammonium compounds (QACs) are antimicrobial disinfectants commonly used in commercial and household settings. Extensive use of QACs results in ubiquitous human exposure, yet reproductive toxicity has not been evaluated. Decreased reproductive performance in laboratory mice coincided with the introduction of a disinfectant containing both alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC). QACs were detected in caging material over a period of several months following cessation of disinfectant use. Breeding pairs exposed for six months to a QAC disinfectant exhibited decreases in fertility and fecundity: increased time to first litter, longer pregnancy intervals, fewer pups per litter and fewer pregnancies. Significant morbidity in near term dams was also observed. In summary, exposure to a common QAC disinfectant mixture significantly impaired reproductive health in mice. This study illustrates the importance of assessing mixture toxicity of commonly used products whose components have only been evaluated individually. PMID:25483128

Melin, Vanessa E; Potineni, Haritha; Hunt, Patricia; Griswold, Jodi; Siems, Bill; Werre, Stephen R; Hrubec, Terry C

2014-12-01

18

The Importance of Molecular Parameters of Quaternary Ammonium Salts in Their Antigibberellin (Retardant) Activity  

Microsoft Academic Search

The importance of six theoretically calculated molecular parameters in the antigibberellin (retardant) activity of quaternary ammonium salts is studied using a regression analysis. A bioassay system based on cell culture of fungus Gibberella fujikuroi is used to determine the activity. In the case of N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium chloride (choline) and N,N,N-triethyl-N-(2-hydroxyethyl)ammonium chloride (N,N,N-triethylcholine) derivatives with linear structure, the polarizability, proton acceptor activity,

R. G. Gafurov; V. Yu. Grigor'ev; A. N. Proshin; V. G. Chistyakov; I. V. Martynov; N. S. Zefirov

2004-01-01

19

Microtitration of various anions with quaternary ammonium halides using solid-state electrodes  

Microsoft Academic Search

Many solid-state electrodes were found to respond as endpoint detectors in the potentiometric titration of large inorganic and organic anions with quaternary ammonium halides. The best response was obtained with the iodide and cyanide electrodes although practically any electrode can function as endpoint sensor. The titrants were hexadecylpyridinium chloride and hexadecyltrimethylammonium chloride; hexadecyltrimethylammonium bromide and Hyamine 1622 may also be

W SELIG

1980-01-01

20

40 CFR 721.9075 - Quaternary ammonium salt of fluorinated alkylaryl amide.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Quaternary ammonium salt of fluorinated alkylaryl amide. 721...Substances § 721.9075 Quaternary ammonium salt of fluorinated alkylaryl amide. ...identified generically as quaternary ammonium salt of fluorinated alkylaryl amide...

2010-07-01

21

40 CFR 721.9075 - Quaternary ammonium salt of fluorinated alkylaryl amide.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Quaternary ammonium salt of fluorinated alkylaryl amide. 721...Substances § 721.9075 Quaternary ammonium salt of fluorinated alkylaryl amide. ...identified generically as quaternary ammonium salt of fluorinated alkylaryl amide...

2011-07-01

22

Surface Micellization Patterns of Quaternary Ammonium Surfactants on Mica  

E-print Network

Surface Micellization Patterns of Quaternary Ammonium Surfactants on Mica Heather N. Patrick equilibrium structures of adsorbed films of quaternary ammonium surfactants on mica have been investigated never been reported on graphite. Mica is a model hydrophilic surface and has been previously used

Aksay, Ilhan A.

23

21 CFR 173.400 - Dimethyldialkylammonium chloride.  

Code of Federal Regulations, 2011 CFR

...2-ethyl-hexyl)-hexa-decyl-ammonium chloride. (b...Free Amine Value of Fatty Quaternary Ammonium Chlorides,” 2d...entitled “Colorimetric Determination of Residual Quaternary Ammonium Compounds (Arquad...

2011-04-01

24

21 CFR 173.400 - Dimethyldialkylammonium chloride.  

Code of Federal Regulations, 2010 CFR

...2-ethyl-hexyl)-hexa-decyl-ammonium chloride. (b...Free Amine Value of Fatty Quaternary Ammonium Chlorides,” 2d...entitled “Colorimetric Determination of Residual Quaternary Ammonium Compounds (Arquad...

2010-04-01

25

40 CFR 415.240 - Applicability; description of the ammonium chloride production subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the ammonium chloride production subcategory. 415...MANUFACTURING POINT SOURCE CATEGORY Ammonium Chloride Production Subcategory § 415.240 Applicability; description of the ammonium chloride production subcategory....

2010-07-01

26

Quaternary ammonium salts and their antimicrobial potential: targets or nonspecific interactions?  

PubMed

For more than 50 years dequalinium chloride has been used successfully as an antiseptic drug and disinfectant, particularly for clinical purposes. Given the success of dequalinium chloride, several series of mono- and bisquaternary ammonium compounds have been designed and reported to have improved antimicrobial activity. Furthermore, many of them exhibit high activity against mycobacteria and protozoa, especially against plasmodia. This review discusses the structure-activity relationships and the modes of action of the various series of (bis)quaternary ammonium compounds. PMID:22113995

Tischer, Maximilian; Pradel, Gabriele; Ohlsen, Knut; Holzgrabe, Ulrike

2012-01-01

27

Polycationic antimicrobial dendrimers: a comparison of alkyl pyridinium,quaternary ammonium, quaternary phosphonium and tertiary sulfonium salts  

NASA Astrophysics Data System (ADS)

Polycationic biocides usually kill bacteria through the interactions of the positively charged head groups with negatively charged bacteria and the interactions of the hydrophobic segments with phospholipid cell membranes, which implies that high local charge densities and a large number of hydrophobic groups would lead to enhanced biocidal potency. The advent of dendrimers offers us the first-ever opportunity to achieve the desired high local density. We have demonstrated that dimethyl dodecyl ammonium chloride functionalized polypropylene imine dendrimers are over 100 times more potent than their small molecule ounterparts. In this study, quaternary ammonium, quaternary phosphonium, alkyl pyridinium and tertiary sulfonium salts based on polypropylene imine dendrimers have been synthesized and characterized. Their antimicrobial properties have been quantified with a novel bioluminescence method. The structure-activity relationship of these polycationic dendrimers has also been investigated to elucidate the molecular mechanism for the enhanced antimicrobial effects.

Chen, Chris; Cooper, Stuart

2000-03-01

28

Microtitration of various anions with quaternary ammonium halides using solid-state electrodes  

SciTech Connect

Many solid-state electrodes were found to respond as endpoint detectors in the potentiometric titration of large inorganic and organic anions with quaternary ammonium halides. The best response was obtained with the iodide and cyanide electrodes although practically any electrode can function as endpoint sensor. The titrants were hexadecylpyridinium chloride and hexadecyltrimethylammonium chloride; hexadecyltrimethylammonium bromide and Hyamine 1622 may also be used. Some inorganic anions thus titratable are perrhenate, persulfate, ferricyanide, hexafluorophosphate, and hexachloroplatinate. Examples of organic anions titratable are nitroform, tetraphenylborate, cyanotriphenylborate, picrate, long-chain sulfates and sulfonates, and some soaps. The reverse titration of quaternary ammonium halides vs dodecylsulfate is also feasible. Some titrations are feasible in a partially nonaqueous medium.

Selig, W.

1980-01-01

29

Determination of antibacterial quaternary ammonium compounds in lozenges by capillary electrophoresis.  

PubMed

A method for the specific determination of three quaternary ammonium compounds, benzalkonium chloride, cetylpyridinium chloride and dequalinium chloride, used as antibacterial agents in candy-based lozenges, is described based on capillary zone electrophoresis. It is shown that, following optimisation of buffer composition with respect to organic modifier concentration. pH and buffer concentration together with the inclusion of sodium dodecylsulphate as an ion-pairing agent in the case of dequalinium chloride, these analytes migrate in less than 5 min. The resultant electrophoretic peaks are sharp and readily quantified. The individual alkyl components of benzalkonium chloride can be resolved as can related impurities in dequalinium chloride lozenges. The quantitative characteristics of the assay method, based on peak areas normalised with respect to migration times, are reported and the method is compared with a previously published method based on liquid chromatography. PMID:9542144

Taylor, R B; Toasaksiri, S; Reid, R G

1998-03-01

30

Resistance to quaternary ammonium compounds in food-related bacteria.  

PubMed

Microbial resistance to antimicrobial agents continues to be a major problem. The frequent use and misuse of disinfectants based on quaternary ammonium compounds (QACs) in food-processing industries have imposed a selective pressure and may contribute to the emergence of disinfectant-resistant microorganisms. A total number of 1,325 Gram-negative isolates (Escherichia coli, other coliforms Vibrio spp., and Aeromonas spp.) and 500 Enterococcus spp. from food and food-processing industries and fish farming were screened for natural resistance to the QAC-based disinfectant benzalkonium chloride (BC). Of the 1,825 isolates, 16 strains, mainly from meat retail shops, showed low-level resistance to BC. None of the Enterococcus spp. from broiler, cattle, and pigs, the antibiotic-resistant E. coli from pig intestine and fish pathogens Vibrio spp. and Aeromonas spp. from the Norwegian fish farming industry were resistant to BC. The BC-resistant strains were examined for susceptibility to 15 different antibiotics, disinfectants, and dyes. No systematic cross-resistance between BC and any of the other antimicrobial agents tested was detected. Stable enhanced resistance in Enterobacter cloacae isolates was demonstrated by step-wise adaptation in increasing concentrations of BC. In conclusion, BC resistance among food-associated Gram-negative bacteria and Enterococcus spp. is not frequent, but resistance may develop to user concentrations after exposure to sublethal concentrations of BC. PMID:12523638

Sidhu, Maan Singh; Sørum, Henning; Holck, Askild

2002-01-01

31

Studies of corrosion inhibitors for zinc–manganese batteries: quinoline quaternary ammonium phenolates  

Microsoft Academic Search

Three compounds, hydroxyethyl quinoline quaternary ammonium phenolate, hydroxyethyl quinoline quaternary ammonium para-methyl phenolate and hydroxyethyl quinoline quaternary ammonium para-nitro phenolate were synthesized and tested as corrosion inhibitors for zinc–manganese batteries. Such quaternary ammonium salts derived from heterocylic molecule containing N atoms possess a higher density electron cloud around the functional groups and provide a larger projective area. From the analysis

Dongshe Zhang; Lidong Li; Lixin Cao; Neifen Yang; Chubao Huang

2001-01-01

32

21 CFR 520.310 - Caramiphen ethanedisulfonate and ammonium chloride tablets.  

Code of Federal Regulations, 2010 CFR

...false Caramiphen ethanedisulfonate and ammonium chloride tablets. 520.310 Section...310 Caramiphen ethanedisulfonate and ammonium chloride tablets. (a) Specifications...ethanedisulfonate and 80 milligrams of ammonium chloride.1 1 These...

2010-04-01

33

Composite aromatic boxes for enzymatic transformations of quaternary ammonium substrates.  

PubMed

Cation-? interactions to cognate ligands in enzymes have key roles in ligand binding and enzymatic catalysis. We have deciphered the key functional role of both charged and aromatic residues within the choline binding subsite of CTP:phosphocholine cytidylyltransferase and choline kinase from Plasmodium falciparum. Comparison of quaternary ammonium binding site structures revealed a general composite aromatic box pattern of enzyme recognition sites, well distinguished from the aromatic box recognition site of receptors. PMID:25283789

Nagy, Gergely N; Marton, Lívia; Contet, Alicia; Ozohanics, Olivér; Ardelean, Laura-Mihaela; Révész, Agnes; Vékey, Károly; Irimie, Florin Dan; Vial, Henri; Cerdan, Rachel; Vértessy, Beáta G

2014-12-01

34

Antibacterial effects of three experimental quaternary ammonium salt (QAS) monomers on bacteria associated with oral infections.  

PubMed

The aim of this study was to test the antibacterial effects of three experimental quaternary ammonium salt monomers in order to evaluate their potential applications as dental materials. In vitro susceptibility testing of the monomers was performed by the broth dilution method on bacteria associated with oral infections: Streptococcus mutans ATCC 25175, Actinomyces viscosus ATCC 15987, Staphylococcus aureus ATCC 29213 and Lactobacillus casei ATCC 393. The time-kill kinetics of the monomer with relatively higher antibacterial activity against S. mutans were also investigated. It was found that all the tested bacteria strains were susceptible to the three monomers, among which methacryloxylethyl cetyl ammonium chloride (DMAE-CB) exhibited the lowest minimal inhibitory concentrations, ranging from 1.2 to 4.8 microg/ml. The time-kill curve showed that DMAE-CB achieved 99.44% killing at 19.2 microg/ml (4 times the minimal bactericidal concentration) against S. mutans after 1 min and 100% killing within 10 min of contact. This result indicates that the quaternary ammonium salt monomer DMAE-CB may be a candidate antibacterial agent for incorporation into dental restorative materials. PMID:18818469

Xiao, Yu-Hong; Chen, Ji-Hua; Fang, Ming; Xing, Xiao-Dong; Wang, Hui; Wang, Ying-Jie; Li, Fang

2008-09-01

35

A Novel Route to Recognizing Quaternary Ammonium Cations Using Electrospray Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Characterizing and elucidating structures is a commonplace and necessary activity in the pharmaceutical industry with mass spectrometry and NMR being the primary tools for analysis. Although many functional groups are readily identifiable, quaternary ammonium cations have proven to be difficult to unequivocally identify using these techniques. Due to the lack of an N-H bond, quaternary ammonium groups can only be detected in the 1H NMR spectra by weak signals generated from long-range 14N-H coupling, which by themselves are inconclusive evidence of a quaternary ammonium functional group. Due to their low intensity, these signals are frequently not detected. Additionally, ions cannot be differentiated in a mass spectrum as an M+ or [M + H]+ ion without prior knowledge of the compound's structure. In order to utilize mass spectrometry as a tool for determining this functionality, ion cluster formation of quaternary ammonium cations and non-quaternary amines was studied using electrospray ionization. Several mobile phase modifiers were compared; however, the addition of small amounts of trifluoroacetic acid proved superior in producing characteristic and intense [M +2TFA]- clusters for compounds containing quaternary ammonium cations when using negative electrospray. By fragmenting this characteristic ion using CID, nearly all compounds studied could be unambiguously identified as containing a quaternary ammonium cation or a non-quaternary amine attributable to the presence (non-quaternary amine) or absence (quaternary ammonium cation) of the resulting [2TFA + H]- ion in the product spectra. This method of analysis provides a rapid, novel, and reliable technique for indicating the presence of quaternary ammonium cations in order to aid in structural elucidation.

Shackman, Holly M.; Ding, Wei; Bolgar, Mark S.

2015-01-01

36

Flocculation of Escherichia coli using a quaternary ammonium salt grafted carboxymethyl chitosan flocculant.  

PubMed

Only few studies are available on bacteria removal efficiencies and antibacterial properties of flocculants, which is one of the important requirements in water treatment work. Escherichia coli (E. coli) was selected as an example of a Gram-negative bacteria for testing the flocculating properties of a quaternary ammonium salt grafted chitosan (carboxymethyl chitosan-graft-poly[(2-methacryloyloxyethyl) trimethylammonium chloride] copolymer; i.e., CMC-g-PDMC). The effect of various flocculation parameters, including flocculant dosage, initial bacterial density, nutrient medium content, and pH were successively investigated. The experimental results indicated that, besides flocculation effects, CMC-g-PDMC also exhibited a bactericidal effect (not requiring additional treatment facilities). Moreover, the flocculation mechanisms were investigated via zeta potential measurements, floc observation, and three-dimensional excitation-emission matrix spectra analysis. Apart from its flocculating and settling effect, this chitosan-based material has bactericidal action through the breaking of bacterial cell walls by grafted quaternary ammonium salt. PMID:24871697

Yang, Zhen; Degorce-Dumas, Jean-Regis; Yang, Hu; Guibal, Eric; Li, Aimin; Cheng, Rongshi

2014-06-17

37

Resistance to phenicol compounds following adaptation to quaternary ammonium compounds in Escherichia coli.  

PubMed

Bacterial adaptation to quaternary ammonium compounds (QACs) is mainly documented for benzalkonium chloride (BC) and few data are available for other QACs. The aim of this study was to assess the effects of repeated exposure to different quaternary ammonium compounds (QACs) on the susceptibility and/or resistance of bacteria to other QACs and antibiotics. Escherichia coli strains (n=10) were adapted by daily exposure to increasingly sub-inhibitory concentrations of a QAC for 7 days. Three QACs were studied. Following adaptation, we found similar levels of reduction in susceptibility to QACs with a mean 3-fold increase in the minimum inhibitory concentration (MIC) compared to initial MIC values, whatever the QAC used during adaptation. No significant differences in antibiotic susceptibility were observed between the tested QACs. Antibiotic susceptibility was reduced from 3.5- to 7.5-fold for phenicol compounds, ? lactams, and quinolones. Increased MIC was associated with a shift in phenotype from susceptible to resistant for phenicol compounds (florfenicol and chloramphenicol) in 90% of E. coli strains. Regardless of the QAC used for adaptation, exposure to gradually increasing concentrations of this type of disinfectant results in reduced susceptibility to QACs and antibiotics as well as cross-resistance to phenicol compounds in E. coli strains. Extensive use of QACs at sub-inhibitory concentrations may lead to the emergence of antibiotic-resistant bacteria and may represent a public health risk. PMID:22397929

Soumet, C; Fourreau, E; Legrandois, P; Maris, P

2012-07-01

38

Aqueous ammonia and ammonium chloride hydrates: Principal infrared spectra  

NASA Astrophysics Data System (ADS)

The infrared (IR) spectra of aqueous ammonia (NH3) and aqueous ammonium chloride (NH4Cl) were recorded by attenuated total reflectance to obtain their molecular organizations. Factor analysis (FA) of the spectra revealed two hydrates for each species: (NH3)2?H2O and NH3?3H2O; NH·HO; and (NH4+,Cl)·3HO, respectively. The hydrate spectra and species abundances were obtained as a function of total concentrations. From this the equilibrium equation between the two ammonia hydrates was determined: 2[(NH)2·HO]+5(HO)2?4[NH·3HO] with its equilibrium constant K? = (2.3 ± 0.6) × 10-5 L3 mol-3. Similarly, for the two ammonium chloride hydrates the equation is 2[(NHCl)2·HO]+5(HO)2?4[NHCl·3HO] with its equilibrium constant: K? = (4 ± 1) × 10-7 L3 mol-3. Band simulations of the hydrate spectra were compared to that of pure liquid water and parent molecules. For aqueous ammonium chloride solutions the water and all ammonium hydrate bands are slightly displaced from that of pure water and pure ammonium chloride, respectively. However, for ammonia hydrates the situation is different: compared to the gas situation the hydrate water bands have similar displacements as that of pure liquid water; the ammonia deformation bands are also little displaced but the stretching bands are strongly red shifted. These shifts, which are even greater than that in pure liquid water, are attributed to strong hydrogen bonding situations: water-H with N-ammonia and ammonia-H with O-water. This explains the high solubility of ammonia in water. The comparison between the spectra of aqueous ammonium chloride and ammonia hydrates indicates that ammonium ion is not present in aqueous ammonia from 11.3 M down to at least our detection limit of 3 mM NH3.

Max, Jean-Joseph; Chapados, Camille

2013-08-01

39

[Synthesis and biological evaluation of tetrahydrocoptisine quaternary ammonium compounds].  

PubMed

The goal of treatment of metabolic syndrome is the prevention of diabetes and cardiovascular events. A series of novel tetrahydrocoptisine quaternary ammonium compounds were prepared to evaluate their action of hypoglycemia and hypolipidemia for finding the therapeutic agents of metabolic syndrome. Starting from the coptisine hydrochloride (2), fifteen target compounds were synthesized by reduction and substitution of the 7-N position. All of the target compounds were characterized by 1H NMR and HR-MS. Their hypoglycemic activities were evaluated in HepG2 cell and hypolipidemic activities of compounds with better hypoglycemic activity were tested further in vivo. Results indicated that compounds 5, 7, 8 and 9 exhibited better hypoglycemic activities in vitro and compounds 5 and 8 exhibited good hypolipidemic activities in high-fat-diet (HFD) induced hyperlipidemia mice and (or) hamsters. However, the activity is not as good as simvastatin. PMID:23460970

Wang, Dong-Mei; Wei, Jin-Zhao; Fan, Bao-Yan; Liu, Quan; Zhu, Hai-Bo; Shen, Zhu-Fang; Wu, Song

2012-12-01

40

[The synergistic action of quaternary ammonium derivatives and inhibitors of nitrate reduction in respect to Pseudomonas aeruginosa].  

PubMed

It was revealed that ability of zink chloride, copper sulphate, aluminium nitrate and sodium chloride to inhibit the nitrate reduction of Pseudomonas correlated with their potentiating influence on the antimicrobial activity of decamethoxin, a quaternary ammonium derivative. So, doses of zink chloride (0.01-0.04%), copper sulphate (0.04%), aluminium nitrate (0.04%), sodium fluoride (0.05-0.1%) able to inhibit effectively the reduction of anions of nitric acid decreased the minimal inhibitory concentration of decamethoxin against Pseudomonas strain ATCC 27853 to 0.15-10 mg/ml and minimal bactericidal concentration to 0.20-10 mg/ml in comparison with 15.6 and 60.4 mg/ml in the control without potentiators. Providing the use of respiration chain's inhibiting doses of sodium fluoride (0.1%) and zink chloride (0.01%), it became possible to decrease the resistance of 54 clinical samples of Pseudomonas aeruginosa to decamethoxin. PMID:9181976

Vievski?, A N

1994-01-01

41

Synergistic effect of heartwood extractives and quaternary ammonium compounds on termite resistance of treated wood.  

PubMed

This study evaluates the synergistic effect of wood extractives and quaternary ammonium compounds (QACs) on the resistance to termites of several treated wood species. Wood specimens from different natural durability classes were extracted with either hot water alone or hot water + ethanol/benzene. The extracted and unextracted wood specimens were treated with either didecyldimethylammonium tetrafluoroborate (DBF) or commercial didecyldimethylammonium chloride (DDAC) solutions and then exposed to subterranean termites, Coptotermes formosanus Shiraki, for 3 weeks under laboratory conditions. The results showed that extractives of the heartwood portions of the wood species contributed to increased resistance against termite attack in the presence of either DBF or DDAC wood preservatives. The synergistic effect of wood extractives and DBF was much clearer with Pseudotsuga menziesii (Mirbel) Franco and Tsuga heterophylla Sarg wood samples. Further studies are needed for a better understanding of the synergism between wood extractives and either DBF or DDAC using both the sapwood and heartwood portions of the same wood species. PMID:17054087

Hwang, Won-Joung; Kartal, S Nami; Yoshimura, Tsuyoshi; Imamura, Yuji

2007-01-01

42

Determination of antibacterial quaternary ammonium compound in lozenges and human serum by resonance light scattering technique.  

PubMed

A method for the specific determination of an antibacterial quaternary ammonium compound Dequalinium chloride (DQC) was described in this paper. At pH 0.5, the resonance light scattering (RLS) intensity of sodium dodecyl benzene sulfonate (SDBS) remarkably was enhanced by adding DQC. A RLS peak at 392.0 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DQC in the range of 0.096-2.88 microg/mL. The detection limit was 2.98 ng/mL and the correlation coefficient was r=0.9988 (n=9). The method was applied to the analysis of DQC in lozenges and human serum. The results indicated that the method was sensitive, simple, practical and useful in the clinical assay. PMID:18585882

Chen, Zhanguang; Peng, Yurui; Chen, Junhui; Zhu, Li

2008-11-01

43

Regulation of nitrogenase activity by ammonium chloride in Azospirillum spp.  

PubMed Central

Ammonium chloride (greater than or equal to 0.05 mM) effectively and reversibly inhibited the nitrogenase activity of Azospirillum brasilense, Azospirillum lipoferum and Azospirillum amazonense. The glutamine synthetase inhibitor L-methionine-DL- sulfoximine abolished this "switch-off" in A. lipoferum and A. brasilense, but not in A. amazonense. Azaserine, an inhibitor of glutamate synthase, inhibited nitrogenase activity itself. This provides further evidence for glutamine as a metabolite of regulatory importance in the NH4+ switch-off phenomenon. In A. brasilense and A. lipoferum, a transition period before the complete inhibition of nitrogenase activity after the addition of 1 mM ammonium chloride was observed. The in vitro nitrogenase activity also was decreased after treatment with ammonium. During sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a second dinitrogenase reductase (Fe protein) subunit appeared, which migrated in coincidence with the modified subunit of the inactive Fe protein of the nitrogenase of Rhodospirillum rubrum. After the addition of ammonium 32P was incorporated into this subunit of the Fe protein of A. brasilense. In A. amazonense, the inhibition of nitrogenase activity by ammonium was only partial, and no transition period could be observed. The in vitro nitrogenase activity of ammonium-treated cells was not decreased, and no evidence for a modified Fe protein subunit was found. Nitrogenase extracts of A. amazonense were active and had an Fe protein that migrated as a close double band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Images PMID:3081492

Hartmann, A; Fu, H; Burris, R H

1986-01-01

44

Antibacterial properties of poly(quaternary ammonium) modified gold and titanium dioxide nanoparticles.  

PubMed

We report excellent antibacterial effect induced by amine-functionalized gold and titanium dioxide nanoparticles without external excitations. The idea originates from the excellent antibacterial property of quaternary ammonium salts. The effects of poly(quaternary ammonium) and polyacrylate sodium functional groups as nanoparticle surfactants are compared to show that poly(quaternary ammonium) functional groups are the main cause of the induced antibacterial effect. 99.999% of E. coli can be destructed in 10 minutes by simply mixing bacteria with nanoparticle dispersions. The effect of nanoparticle concentrations on the antibacterial property is evaluated. Time required to significantly suppress bacteria growth is studied. The result indicates that the excellent antibacterial property can be introduced to any nanomaterials by using poly(quaternary ammonium) functional groups as surfactants. The engineered nanoparticles can find enormous applications such as self-cleaning surfaces, waste water treatment, Lab-on-a-Chip devices and many more. PMID:22905506

Wan, Weijie; Yeow, John T W

2012-06-01

45

Interaction of ochratoxin A with quaternary ammonium beta-cyclodextrin.  

PubMed

Ochratoxin A (OTA) is a widely spread nephrotoxic food contaminant mycotoxin. Unfortunately, attenuation or prevention of the toxic effects of OTA is still an unresolved problem. Molecular inclusion of OTA by cyclodextrins (CDs) results in complexes with low stability. In the human organism, OTA exists mostly in the dianionic state (OTA(2-)). Therefore, our major goal was to develop a chemically modified cyclodextrin which gives a more stable complex with OTA than the previously published derivatives and which shows stronger preference towards OTA(2-). In our fluorescence spectroscopic study we demonstrate that quaternary ammonium beta-cyclodextrin (QABCD) fulfils both of these requirements. The calculated stability constant of the QABCD-OTA(2-) complex was 28,840 M(-1) (about 200-fold higher than that of the ?-CD-OTA(2-) complex). We hypothesize, that QABCD may be a suitable tool for the decontamination of different OTA-contaminated drinks; furthermore, for alleviation of the toxic effects of OTA, such complex formation may reduce its absorption from the intestine. PMID:25442535

Poór, Miklós; Kunsági-Máté, Sándor; Szente, Lajos; Matisz, Gergely; Secenji, Györgyi; Czibulya, Zsuzsanna; K?szegi, Tamás

2015-04-01

46

Quaternary ammonium sulfanilamide: a membrane-impermeant carbonic anhydrase inhibitor  

SciTech Connect

A novel carbonic anhydrase (CA) inhibitor, quaternary ammonium sulfanilamide (QAS), was tested for potency as a CA inhibitor and for its ability to be excluded from permeating biological membranes. Inhibitor titration plots of QAS vs. pure bovine CA II and CA from the gills of the blue crab, Callinectes sapidus, yielded K/sub i/ values of approx. 15 ..mu..M; thus QAS is a relatively weak but effective CA inhibitor. Permeability of the QAS was directly tested by two independent methods. The inhibitor was excluded from human erythrocytes incubated in 5 mM QAS for 24 h as determined using an /sup 18/O-labeled mass spectrometer CA assay for intact cells. Also QAS injected into the hemolymph of C. sapidus (1 or 10 mM) did not cross the basal membrane of the gill. The compound was cleared from the hemolymph by 96 h after injection, and at no time during that period could the QAS be detected in homogenates of gill tissue. Total branchial CA activity was only slightly reduced following the QAS injection. These data indicate that QAS is a CA inhibitor to which biological membranes are impermeable and that can be used in vivo and in vitro in the study of membrane-associated CA.

Henry, R.P.

1987-05-01

47

Synthesis and structure-activity study of quaternary ammonium functionalized beta-cyclodextrin-carboxymethylcellulose polymers.  

PubMed

Carboxymethylcellulose (CMC) and beta-cyclodextrin (beta-CD)-based polymers functionalized with two types of quaternary ammonium compounds (QACs), the alkaquat DMB-451 (N-alkyl (50% C14, 40% C12, 10% C10) dimethylbenzylammonium chloride) (DMD-451) named polymer DMB-451, and FMB 1210-8 (a blend of 32 w% N-alkyl (50% C14, 40% C12, 10% C10) dimethylbenzylammonium chloride and 48 w% of didecyldimethylammonium chloride) named polymer FMB 1210-8, were synthethized and characterized by Fourier transform infrared spectroscopy. The antimicrobial activities of these polymers against Eschericia coli were also evaluated at 25 degrees C in wastewater. The results have indicated that the polymer FMB 1210-8 possesses a high-affinity binding with bacterial cells that induces a rapid disinfection process. Moreover, in the same experimental conditions of disinfection (mixture of 1.0 g of polymer and 100 mL of wastewater), the polymer FMB 1210-8 has a higher antimicrobial efficiency (99.90%) than polymer DMB-451 (92.8%). This phenomenon might be associated to a stronger interaction with bacterial cells due to stronger binding affinity for E. coli cells and greater killing efficiency of the C10 alkyl chains QAC of polymer FMB 1210-8 to disrupt the bacterial cell membrane as compared to N-alkyl (50% C14, 40% C12, 10% C10) dimethylbenzylammonium chloride. Together, these results suggest that the polymer FMB 1210-8 could constitute a good disinfectant against Escherichia coli, which could be advantageously used in wastewater treatments due to the low toxicity of beta-CD and CMC, and moderated toxicity of FMB 1210-8 to human and environment. PMID:22049706

Bonenfant, Danielle; Bourgeois, François-René; Mimeault, Murielle; Monette, Frédéric; Niquette, Patrick; Hausler, Robert

2011-01-01

48

Copper and quaternary ammonium cations exert synergistic bactericidal and antibiofilm activity against Pseudomonas aeruginosa.  

PubMed

Biofilms are slimy aggregates of microbes that are likely responsible for many chronic infections as well as for contamination of clinical and industrial environments. Pseudomonas aeruginosa is a prevalent hospital pathogen that is well known for its ability to form biofilms that are recalcitrant to many different antimicrobial treatments. We have devised a high-throughput method for testing combinations of antimicrobials for synergistic activity against biofilms, including those formed by P. aeruginosa. This approach was used to look for changes in biofilm susceptibility to various biocides when these agents were combined with metal ions. This process identified that Cu(2+) works synergistically with quaternary ammonium compounds (QACs; specifically benzalkonium chloride, cetalkonium chloride, cetylpyridinium chloride, myristalkonium chloride, and Polycide) to kill P. aeruginosa biofilms. In some cases, adding Cu(2+) to QACs resulted in a 128-fold decrease in the biofilm minimum bactericidal concentration compared to that for single-agent treatments. In combination, these agents retained broad-spectrum antimicrobial activity that also eradicated biofilms of Escherichia coli, Staphylococcus aureus, Salmonella enterica serovar Cholerasuis, and Pseudomonas fluorescens. To investigate the mechanism of action, isothermal titration calorimetry was used to show that Cu(2+) and QACs do not interact in aqueous solutions, suggesting that each agent exerts microbiological toxicity through independent biochemical routes. Additionally, Cu(2+) and QACs, both alone and in combination, reduced the activity of nitrate reductases, which are enzymes that are important for normal biofilm growth. Collectively, the results of this study indicate that Cu(2+) and QACs are effective combinations of antimicrobials that may be used to kill bacterial biofilms. PMID:18519726

Harrison, Joe J; Turner, Raymond J; Joo, Daniel A; Stan, Michelle A; Chan, Catherine S; Allan, Nick D; Vrionis, Helen A; Olson, Merle E; Ceri, Howard

2008-08-01

49

[The action of quaternary ammonium derivatives on respiration and nitrate reduction in Pseudomonas aeruginosa].  

PubMed

It was revealed that the same dosages of quaternary ammonium derivatives, such as decamethoxin and cetyltrimethylammonium bromide, inhibited the respiratory chains and caused destruction of Pseudomonas aeruginosa under aerobic conditions more effectively than under anaerobic ones when anions of nitric acid were the terminal acceptors of electrons. It was also registered that Pseudomonas were able to dissimilatory nitrate reduction in the media under the polysaccharide layer that was produced by these bacteria: this fact possibly proves the possibility of survival of denitrifying bacteria in solutions with high concentrations of quaternary ammonium salts. The data obtained permit supposing that inhibitors of respiratory chains and oxidizers may be used as potentiators of the antimicrobial action of quaternary ammonium derivatives. PMID:7952225

Bievski?, A N

1994-01-01

50

Synthesis and analgesic activity of hydrochlorides and quaternary ammoniums of epibatidine incorporated with amino acid ester.  

PubMed

Hydrochloride derivatives 5a-c and quaternary ammonium derivatives 6a-c of epibatidine incorporated with amino acid ester were synthesized and evaluated for their in vivo analgesic activity and toxicity. Among all tested compounds, compound 6c has the most potent analgesic activity. The quaternary ammonium salts 6a and 6c showed better analgesic activity than the corresponding hydrochlorides 5a and 5c. Both 5a-c and 6a-c showed significantly lower toxicity than epibatidine itself. PMID:14643319

Dong, Jing-Chao; Wang, Xin; Li, Run-Tao; Zhang, Hong-Mei; Cheng, Tie-Ming; Li, Chang-Ling

2003-12-15

51

Synthesis, surface and antimicrobial properties of some quaternary ammonium homochiral camphor sulfonamides.  

PubMed

A group of homochiral quaternary ammonium sulfonamides bearing hydrophobic camphor derived moieties were synthesized and characterized. The described synthetic procedure is quick and efficient. The novel quaternary ammonium bromides were tested as antimicrobial and antifungal agents. They exhibited strong antimicrobial and also antifungal activity, especially N-{2-[((1S, 4R)-7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methylsulfonamido] ethyl}-N,N-dimethyltetradecan-1-aminium bromide 1c. The surface properties of prepared compounds were evaluated by surface tension measurements and critical micelle concentration (CMC) with surface tension at CMC (?CMC) was calculated. PMID:25218991

Mikláš, R; Miklášová, N; Bukovský, M; Horváth, B; Kubincová, J; Devínsky, F

2014-12-18

52

Capillary electrophoresis and liquid chromatography in the analysis of some quaternary ammonium salts used in lozenges as antibacterial agents.  

PubMed

A comparison is made of the relative merits of high-performance liquid chromatography and capillary electrophoresis, both using direct UV detection, for the determination of three quaternary ammonium compounds used as the active antibacterial ingredient in lozenge formulations. While both techniques are capable of separating the compounds cetylpyridinium chloride, dequalinium chloride, and benzalkonium chlorides, the liquid chromatographic method involving ion pairing and using a 5-micron cyanopropyl stationary phase, was unable to resolve the benzalkonium chlorides from the lozenge excipients and quantitation was not possible. The capillary electrophoresis method using a 205-mm 50-micron-i.d. capillary with a running buffer of 50% vol/vol 50 mM phosphate buffer at pH 3 provided superior resolution of the three antibacterials in all lozenge formulations. This system was also capable of resolving impurities in the dequalinium chloride both in the standard and in lozenges containing this compound. On the basis of quantitative results previously published, both methods have adequate validation parameters since the relative insensitivity of capillary electrophoresis compared with liquid chromatography is not important at the concentration required to be determined following a single simple sample pretreatment. PMID:10327369

Taylor, R B; Toasaksiri, S; Reid, R G

1998-01-01

53

Synthesis and characterization of antibacterial polyurethane coatings from quaternary ammonium salts functionalized soybean oil based polyols.  

PubMed

In this study, a simple and versatile synthetic approach was developed to prepare bactericidal polyurethane coatings. For this purpose, introduction of both quaternary ammonium salts (QASs), with well-known antibacterial activity, and reactive hydroxyl groups on to the backbone of soybean oil was considered. Epoxidized soybean oil was reacted with diethylamine and the intermediate tertiary amine containing polyol was reacted with two different alkylating agents, methyl iodide and benzyl chloride, to produce MQAP and BQAP, respectively. These functional polyols were reacted with different diisocyanate monomers to prepare polyurethane coatings. Depending on the structure of monomers used for the preparation of polyurethane coatings, initial modulus, tensile strength and elongation at break of samples were in the ranges of 122-339MPa, 4.6-12.4MPa and 8.4-46%, respectively. Polyurethane coatings based on isophorone diisocyanate showed proper mechanical properties and adhesion strength (0.41MPa) for coating application. Study of fibroblast cells interaction with prepared polyurethanes showed promising cells viability in the range of 78-108%. Meanwhile, MQAP based samples with higher concentration of QASs showed better adhesion strength, surface hydrophilicity and antibacterial activity (about 95% bacterial reduction). Therefore, these materials can find applications as bactericidal coating for biomedical devices and implants. PMID:25428057

Bakhshi, Hadi; Yeganeh, Hamid; Mehdipour-Ataei, Shahram; Shokrgozar, Mohammad Ali; Yari, Abbas; Saeedi-Eslami, Seyyed Nasirodin

2013-01-01

54

Dual action antimicrobials: nitric oxide release from quaternary ammonium-functionalized silica nanoparticles.  

PubMed

The synthesis of quaternary ammonium (QA)-functionalized silica nanoparticles with and without nitric oxide (NO) release capabilities is described. Glycidyltrialkylammonium chlorides of varied alkyl chain lengths (i.e., methyl, butyl, octyl, and dodecyl) were tethered to the surface of amine-containing silica nanoparticles via a ring-opening reaction. Secondary amines throughout the particle were then functionalized with N-diazeniumdiolate NO donors to yield dual functional nanomaterials with surface QAs and total NO payloads of 0.3 ?mol/mg. The bactericidal activities of singly (i.e., only NO-releasing or only QA-functionalized) and dual (i.e., NO-releasing and QA-functionalized) functional nanoparticles were tested against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa . Particles with only NO release capabilities alone were found to be more effective against P. aeruginosa , while particles with only QA-functionalities exhibited greater toxicity toward S. aureus . The minimum bactericidal concentrations (MBC) of QA-functionalized particles decreased with increasing alkyl chain length against both microbes tested. Combining NO release and QA-functionalities on the same particle resulted in an increase in bactericidal efficacy against S. aureus ; however, no change in activity against P. aeruginosa was observed compared to NO-releasing particles alone. PMID:22998760

Carpenter, Alexis W; Worley, Brittany V; Slomberg, Danielle L; Schoenfisch, Mark H

2012-10-01

55

Factors contributing to the survival of poultry associated Pseudomonas spp. exposed to a quaternary ammonium compound.  

PubMed

Resistance to benzalkonium chloride (BC) among Pseudomonas spp. isolated from poultry carcasses was determined and strategies for elimination of resistant strains evaluated. This investigation showed that resistance was quite common, about 30% of the isolates being able to grow in 200 micrograms ml-1 BC. Pseudomonas fluorescens strains were generally less susceptible than strains of Ps. lundensis and Ps. fragi. An overnight incubation in medium containing 200 micrograms ml-1 BC was sufficient to reduce the susceptibility of two Pseudomonas strains to the lethal effect of BC significantly. Adding EDTA enhanced the lethal effect of BC, but the effect was reduced after growing cells in medium containing BC and EDTA. Growth in medium with a quaternary ammonium compound (QAC) rendered the cells more susceptible to chlorine, phenolics, and alkylaminoacetate. These results indicate that alternating use of QACs with these compounds can be used to avoid build-up of resistant strains. In addition, increased temperatures improved the lethal effect of BC and should be considered when planning disinfection routines. PMID:9202437

Langsrud, S; Sundheim, G

1997-06-01

56

Effects of quaternary ammonium silane coatings on mixed fungal and bacterial biofilms on tracheoesophageal shunt prostheses.  

PubMed

Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem. PMID:16672516

Oosterhof, Janine J H; Buijssen, Kevin J D A; Busscher, Henk J; van der Laan, Bernard F A M; van der Mei, Henny C

2006-05-01

57

The role of the qacA gene in mediating resistance to quaternary ammonium compounds.  

PubMed

Conditions facilitating resistance to quaternary ammonium compounds (QACs) were investigated in Staphylococcus aureus SK982 exposed to benzalkonium chloride (BAC; a member of QACs) under various circumstances. S. aureus SK982 carrying the qacA gene encoding for resistance to QACs was grown in the presence of stable or gradually increasing concentrations of BAC, or it was exposed to this antiseptic in the exponential phase of growth. Bacteria cultivated in the highest BAC concentrations that did not retard their growth comparing to the untreated control were subjected to real-time quantitative polymerase chain reaction analysis for relative expression of the efflux genes qacA and norA. Under such conditions, S. aureus SK982 tolerated a relatively low stable concentration of BAC (1.22?mg/L) when compared with a gradually increasing antiseptic concentration (tolerance of 4.88?mg/L). However, in both cases, qacA expression was not significant. The culture exposed in the exponential phase of growth tolerated the highest concentration of BAC (9.76?mg/L) as also accompanied by significant overexpression of qacA. Expression of norA was relatively low regardless of the conditions tested. It seems that under the short-term conditions, the phase of bacterial growth is more important for the expression of BAC resistance than the capability to adapt to this antiseptic. This study provides a deeper insight into the relevance of the qac genes in conferring resistance to QACs. PMID:23256651

Cervinkova, Dana; Babak, Vladimir; Marosevic, Durdica; Kubikova, Iva; Jaglic, Zoran

2013-06-01

58

Incidence of Class 1 Integrons in a Quaternary Ammonium Compound-Polluted Environment  

PubMed Central

Samples of effluent and soil were collected from a reed bed system used to remediate liquid waste from a wool finishing mill with a high use of quaternary ammonium compounds (QACs) and were compared with samples of agricultural soils. Resistance quotients of aerobic gram-negative and gram-positive bacteria to ditallowdimethylammomium chloride (DTDMAC) and cetyltrimethylammonium bromide (CTAB) were established by plating onto nutrient agar containing 5 ?g/ml or 50 ?g/ml DTDMAC or CTAB. Approximately 500 isolates were obtained and screened for the presence of the intI1 (class 1 integrase), qacE (multidrug efflux), and qacE?1 (attenuated qacE) genes. QAC resistance was higher in isolates from reed bed samples, and class 1 integron incidence was significantly higher for populations that were preexposed to QACs. This is the first study to demonstrate that QAC selection in the natural environment has the potential to coselect for antibiotic resistance, as class 1 integrons are well-established vectors for cassette genes encoding antibiotic resistance. PMID:15855499

Gaze, W. H.; Abdouslam, N.; Hawkey, P. M.; Wellington, E. M. H.

2005-01-01

59

The inhibitive effect of some quaternary ammonium salts towards corrosion of aluminium in hydrochloric acid solution  

Microsoft Academic Search

The inhibitive action of some quaternary ammonium salts towards the corrosion of aluminium in hydrochloric acid was tested by thermometric, mass loss and polarization measurements. Parallelism between the different methods was established. It is suggested that the tested compounds act as cathodic inhibitors. The inhibitors appear to function through adsorption, following the Temkin adsorption isotherm. The values of free energy

A.-M. K. Mohamed; A. Al-Nadjm; A.-A. S. Fouda

1998-01-01

60

Synthesis of hierarchical zeolites using an inexpensive mono-quaternary ammonium surfactant as mesoporogen.  

PubMed

A simple amphiphilic surfactant containing a mono-quaternary ammonium head group (N-methylpiperidine) is effective in imparting substantial mesoporosity during synthesis of SSZ-13 and ZSM-5 zeolites. Highly mesoporous SSZ-13 prepared in this manner shows greatly improved catalytic performance in the methanol-to-olefins reaction compared to bulk SSZ-13. PMID:25316609

Zhu, Xiaochun; Rohling, Roderigh; Filonenko, Georgy; Mezari, Brahim; Hofmann, Jan P; Asahina, Shunsuke; Hensen, Emiel J M

2014-12-01

61

Corrosion inhibition of benzyl triethanol ammonium chloride and its ethoxylate on steel in sulphuric acid solution  

Microsoft Academic Search

The inhibitive effect of benzyl triethanol ammonium chloride (BTAC) and ethoxylated benzyl triethanol ammonium chloride (EBTAC) on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The adsorption of these compounds (surfactants) leads to the formation of a monolayer on the metal surface. The relationships between the concentrations of these inhibitors and their

M. M Osman; A. M. A Omar; A. M Al-Sabagh

1997-01-01

62

Hibiscus sabdariffa Affects Ammonium Chloride-Induced Hyperammonemic Rats  

PubMed Central

Hibiscus sabdariffa (HS) is an edible medicinal plant, indigenous to India, China and Thailand and is used in Ayurveda and traditional medicine. Alcoholic extract of HS leaves (HSEt) was studied for its anti-hyperammonemic and antioxidant effects in brain tissues of ammonium chloride-induced hyperammonemic rats. Oral administration of HSEt (250 mg kg?1 body weight) significantly normalizes the levels of ammonia, urea, uric acid, creatinine and non-protein nitrogen in the blood. HSEt significantly reduced brain levels of lipid peroxidation products such as thiobarbituric acid and reactive substances (TBARS) and hydroperoxides (HP). However, the administered extract significantly increased the levels of antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) in brain tissues of hyperammonemic rats. This investigation demonstrates significant anti-hyperammonemic and antioxidant activity of HS. PMID:17965762

Essa, M. Mohamed

2007-01-01

63

Liquid-liquid phase separation in particles containing organics mixed with ammonium sulfate, ammonium bisulfate, ammonium nitrate or sodium chloride  

NASA Astrophysics Data System (ADS)

As the relative humidity varies from high to low values in the atmosphere, particles containing organic species and inorganic salts may undergo liquid-liquid phase separation. The majority of the laboratory work on this subject has used ammonium sulfate as the inorganic salt. In the following we studied liquid-liquid phase separation in particles containing organics mixed with the following salts: ammonium sulfate, ammonium bisulfate, ammonium nitrate and sodium chloride. In each experiment one organic was mixed with one inorganic salt and the liquid-liquid phase separation relative humidity (SRH) was determined. Since we studied 23 different organics mixed with four different salts, a total of 92 different particle types were investigated. Out of the 92 types, 49 underwent liquid-liquid phase separation. For all the inorganic salts, liquid-liquid phase separation was never observed when the oxygen-to-carbon elemental ratio (O : C) ≥ 0.8 and was always observed for O : C < 0.5. For 0.5 ≤ O : C < 0.8, the results depended on the salt type. Out of the 23 organic species investigated, the SRH of 20 organics followed the trend: (NH4)2SO4 ≥ NH4HSO4 ≥ NaCl ≥ NH4NO3. This trend is consistent with previous salting out studies and the Hofmeister series. Based on the range of O : C values found in the atmosphere and the current results, liquid-liquid phase separation is likely a frequent occurrence in both marine and non-marine environments.

You, Y.; Renbaum-Wolff, L.; Bertram, A. K.

2013-12-01

64

Selective removal and inactivation of bacteria by nanoparticle composites prepared by surface modification of montmorillonite with quaternary ammonium compounds.  

PubMed

The purpose of the present study was to prepare new nanocomposites with antibacterial activities by surface modification of montmorillonite using quaternary ammonium compounds that are widely applied as disinfectants and antiseptics in food-processing environments. The intercalation of four quaternary ammonium compounds namely benzalkonium chloride, cetylpyridinium chloride monohydrate, hexadecyltrimethylammonium bromide, tetraethylammonium chloride hydrate into montmorillonite layers was confirmed by X-ray diffraction. The antibacterial influences of the modified clay variants against important foodborne pathogens differed based on modifiers quantities, microbial cell densities, and length of contact. Elution experiments through 0.1 g of the studied montmorillonite variants indicated that Staphylococcus aureus, Pseudomonas aeroginosa, and Listeria monocytogenes were the most sensitive strains. 1 g of hexadecyltrimethylammonium bromide intercalated montmorillonites demonstrated maximum inactivation of L. monocytogenes populations, with 4.5 log c.f.u./ml units of reduction. In adsorption experiments, 0.1 g of tetraethylammonium chloride hydrate montmorillonite variants significantly reduced the growth of Escherichia coli O157:H7, L. monocytogenes, and S. aureus populations by 5.77, 6.33, and 7.38 log units respectively. Growth of wide variety of microorganisms was strongly inhibited to undetectable levels (chloride montmorillonite variants. This investigation highlights that reduction in counts of microbial populations adsorbed to the new nanocomposites was substantially different from that in elution experiments, where interactions of nanocomposites with bacteria were specific and more complex than simple ability to inactivate. Treatment columns packed with modified variants maintained their inactivation capacity to the growth of Salmonella Tennessee and S. aureus populations after 48 h of incubation at room temperature with maximum reductions of 6.3 and 5.0 log units respectively. New nanocomposites presented in this research may have potential applications in industrial scale for the control of foodborne pathogens by their incorporation into high-performance filters in food processing plant environments where selectivity in removal and/or inactivation of species in fluid flow streams is desirable. Nevertheless, extensive in vitro and in vivo studies of these new nanocomposites is essential to outpace the understanding of their potential impacts and consequences on human health and the environment if they will make an appearance in commercialized food packaging and containment food materials in the future. PMID:23709187

Khalil, Rowaida K S

2013-10-01

65

Morphology Control of Zn-SiO2 Composite Films Electrodeposited from Aqueous Solution Containing Quaternary Ammonium Cations  

NASA Astrophysics Data System (ADS)

Zn-SiO2 alloys were electrodeposited from acidic aqueous solution containing cationic surfactants such as diallyl-dimethyl-ammonium chloride, trimethyl-tetradecyl-ammonium chloride, trimethyl-stearyl-ammonium chloride and dimethyl-distearyl-ammonium chloride. Zn-SiO2 alloy thin films were obtained at the wide current density range from 5 A/dm2 to 100 A/dm2. SiO2 content in deposits was ca. 10 % at the maximum using the solution containing a surfactant with molecular weight range of 200 to 300.

Ohgai, T.; Ogushi, K.; Takao, K.

2013-03-01

66

Headgroup effect on drag reduction and rheological properties of micellar solutions of quaternary ammonium surfactants  

Microsoft Academic Search

Two sets of cationic surfactants each with essentially the same alkyl chains but different headgroup structures were studied to investigate the effects of surfactant headgroup structure on micelle microstructures, drag reduction (DR) and rheological properties at certain counterion and surfactant concentrations. Cetyldimethylethylammonium bromide (CDMEAB) was compared with alkyltrimethyl ammonium bromide (CnTAB) and benzyldimethyl(hydrogenated tallow)ammonium chloride (DMHTB) was compared with alkyltrimethylammonium

Ying Zhang; Yunying Qi; Jacques L. Zakin

2005-01-01

67

Dietary ammonium chloride and the urinary excretion of chlortetracycline and oxytetracycline  

E-print Network

- tonseed meal was reduced from 10 to 7 percent of the total ration and a comb1nation of ammonium chloride, ammonium sulfate and Poly-N (a commercial preparation of ammoniated phosphoric acid) at the level of 0. 5, 1. 0 and 1. 5 percent of the total diet... percent ammonium chloride, 1. 0 percent ammonium sulfate and 1. 5 percent Poly-N reduced gain and feed consumption markedly but resulted in only a small decrease 1n feed efficiency when compared to the basal ration plus diethylstilbestrol. Apparently...

Roberts, Ronald Curtis

1967-01-01

68

bis-Azaaromatic quaternary ammonium salts as ligands for the blood-brain barrier choline transporter  

PubMed Central

A series of bis-azaaromatic quaternary ammonium compounds containing flexible polymethylenic linkers as well as conformationally restricted linkers were evaluated for their affinity for the blood-brain barrier choline transporter (BBB-ChT). The preliminary structure-activity relationships obtained from this study suggest that incorporating a linear, conformationally restricted linker into the molecule improves affinity for the BBB-ChT. PMID:20462759

Zheng, Guangrong; Zhang, Zhenfa; Lockman, Paul R.; Geldenhuys, Werner J.; Allen, David D.; Dwoskin, Linda P.; Crooks, Peter A.

2013-01-01

69

Synthesis of Quaternary Ammonium Salts of Tricyclic Cationic Drugs: A One-Pot Synthesis for the Bioorganic Chemistry Laboratory  

ERIC Educational Resources Information Center

A one-pot conversion of tricyclic cationic drugs to their quaternary ammonium forms is described for a widely used bioactive drug: chlorpromazine, a phenothiazine-based antipsychotic. After conversion to its free base, the parent drug was methylated using substoichiometric amounts of methyl iodide dissolved in ether; the charged quaternary

Brunauer, Linda S.; Mogannam, Abid C.; Hwee, Won B.; Chen, James Y.

2007-01-01

70

Peptides derivatized with bicyclic quaternary ammonium ionization tags. Sequencing via tandem mass spectrometry.  

PubMed

Improving the sensitivity of detection and fragmentation of peptides to provide reliable sequencing of peptides is an important goal of mass spectrometric analysis. Peptides derivatized by bicyclic quaternary ammonium ionization tags: 1-azabicyclo[2.2.2]octane (ABCO) or 1,4-diazabicyclo[2.2.2]octane (DABCO), are characterized by an increased detection sensitivity in electrospray ionization mass spectrometry (ESI-MS) and longer retention times on the reverse-phase (RP) chromatography columns. The improvement of the detection limit was observed even for peptides dissolved in 10?mM NaCl. Collision-induced dissociation tandem mass spectrometry of quaternary ammonium salts derivatives of peptides showed dominant a- and b-type ions, allowing facile sequencing of peptides. The bicyclic ionization tags are stable in collision-induced dissociation experiments, and the resulted fragmentation pattern is not significantly influenced by either acidic or basic amino acid residues in the peptide sequence. Obtained results indicate the general usefulness of the bicyclic quaternary ammonium ionization tags for ESI-MS/MS sequencing of peptides. PMID:25303389

Setner, Bartosz; Rudowska, Magdalena; Klem, Ewelina; Cebrat, Marek; Szewczuk, Zbigniew

2014-10-01

71

77 FR 47291 - Residues of Didecyl Dimethyl Ammonium Chloride; Exemption From the Requirement of a Tolerance  

Federal Register 2010, 2011, 2012, 2013

...in evaporative humidifiers. Evaporative humidifiers, unlike other types of humidifiers, do not generate and expel treated droplets or mist. The Didecyl dimethyl ammonium chloride will volatilize in, at most, negligible amounts from treated water in...

2012-08-08

72

Immobilization of quaternary ammonium salts on grafting particle polystyrene/SiO 2 and preliminary study of application performance  

NASA Astrophysics Data System (ADS)

Polystyrene (PSt) was grafted on the surface of silica gel particles in the manner of "grafting from" in a solution polymerization system, and grafting particles PSt/SiO 2 was obtained. The chloromethylation reaction of the grafted polystyrene was performed using a novel chloromethylation reagent, 1,4-bis(chloromethyoxy)butane which is un-carcinogenic, and grafting particles CMPS/SiO 2 was gained. Subsequently, grafted CMPS was quaternized (denoted as QPS) using tertiary amine, and finally functional composite-type particles QPS/SiO 2, on which quaternary ammonium groups were immobilized, were prepared. The catalysis activity of the particle QPS/SiO 2 as a triphase catalyst in phase-transfer catalysis systems and its antibacterial activity as a water-insoluble antibacterial material were studied preliminarily. The experimental results show that the particle QPS/SiO 2 exhibits higher catalysis activity as a triphase catalyst for the reaction between benzyl chloride in organic phase and sodium acetate in aqueous phase to form benzyl acetate, and under a mild condition of 60 °C for 7 h of reaction time a conversion of 66% for benzyl chloride can be obtained. The particle QPS/SiO 2 has high antibacterial activity as a water-insoluble antibacterial material against Escherichia coli ( E. coli).

Gao, Baojiao; Qi, Changsheng; Liu, Qing

2008-04-01

73

Quaternary ammonium salts intercalated ?-ZrP compounds for adsorption of phenolic compounds  

NASA Astrophysics Data System (ADS)

By using methylamine as the colloidization agent to weaken the interactions of ?-ZrP laminate, the quaternary ammonium salts of DTAB, TTAB, CTAB and STAB were successfully intercalated into the methylamine pre-pillared ?-ZrP, denoted as DTAB-ZrP, TTAB-ZrP, CTAB-ZrP and STAB-ZrP, respectively. XRD, FTIR, TEM and N2 sorption were used to characterize the intercalated compounds, and the arrangements of intercalated quaternary ammonium salts within ZrP were supposed according to the results. It was shown that the interlayer distances were increased from 0.76 nm to 2.10-3.50 nm and the intercalated quaternary amine salt cationic bonded with Psbnd O- anion through electrostatic interaction. The phenolic compounds adsorption results have demonstrated that all the four intercalated compounds have good adsorption performance, and CTAB-ZrP show the highest maximum adsorption amounts of 0.90, 1.25 and 1.34 mmol g-1, for phenol, 2-chlorophenol and 2,4-dichlorophenolare, respectively. The adsorption isotherms of phenolic compounds are linear with the C0 of 2.0-6.0 mmol L-1 and fit well to both the Linear and the Freundlich models, which indicated that the adsorption mechanism is mainly partition effects of organic phase within ZrP interlayer.

Wang, Hongning; Liu, Wenjin; Yao, Wei; Zhang, Ke; Zhong, Jing; Chen, Ruoyu

2013-03-01

74

Evaluation of three-dimensional biofilms on antibacterial bonding agents containing novel quaternary ammonium methacrylates  

PubMed Central

Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alkyl chain length effects on three-dimensional biofilms adherent on adhesives for the first time. Six quaternary ammonium methacrylates with chain lengths of 3, 6, 9, 12, 16 and 18 were synthesized and incorporated into Scotchbond Multi-Purpose. Streptococcus mutans bacteria were cultured on resin to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live/dead volumes and live-bacteria percentage vs. distance from resin surface. Biofilm thickness was the greatest for Scotchbond control; it decreased with increasing chain length, reaching a minimum at chain length 16. Live-biofilm volume had a similar trend. Dead-biofilm volume increased with increasing chain length. The adhesive with chain length 9 had 37% live bacteria near resin surface, but close to 100% live bacteria in the biofilm top section. For chain length 16, there were nearly 0% live bacteria throughout the three-dimensional biofilm. In conclusion, strong antibacterial activity was achieved by adding quaternary ammonium into adhesive, with biofilm thickness and live-biofilm volume decreasing as chain length was increased from 3 to 16. Antibacterial adhesives typically only inhibited bacteria close to its surface; however, adhesive with chain length 16 had mostly dead bacteria in the entire three-dimensional biofilm. Antibacterial adhesive with chain length 16 is promising to inhibit biofilms at the margins and combat secondary caries. PMID:24722581

Zhou, Han; Weir, Michael D; Antonucci, Joseph M; Schumacher, Gary E; Zhou, Xue-Dong; Xu, Hockin HK

2014-01-01

75

Syntheses and Applications of (Thio)Urea-Containing Chiral Quaternary Ammonium Salt Catalysts  

PubMed Central

We herein report our efforts to obtain a new class of systematically modified bifunctional (thio)urea-containing quaternary ammonium salts based on easily obtainable chiral backbones. Among the different classes of catalysts that were successfully synthesized, those based on trans-1,2-cyclohexane diamine were found to be the most powerful for the asymmetric ?-fluorination of ?-keto esters. Selectivities up to 93:7 could be obtained by using only 2 mol-% of the optimized catalyst. The importance of the bifunctional nature of these catalysts was demonstrated by control experiments using simplified monofunctional catalyst analogues, which gave almost racemic product only. PMID:25339849

Novacek, Johanna; Waser, Mario

2014-01-01

76

Reversible phase transformation-type layer shape electrolyte based on POM and quaternary ammonium salt  

NASA Astrophysics Data System (ADS)

A novel kind of organic-inorganic layer shape material, polyoxymetalates (POM)-type ionic liquid (IL) with Keggin structure and simple quaternary ammonium salt, (TOAMe)4PW11VO40 (trioctylmethylammonium = TOAMe,…) is synthesized and characterized by IR, UV, X-ray diffraction (XRD), TG-DTA. Its electrochemical property was investigated by cyclic voltammgram. Research results released the vanadium and the POM structure in the compound can process reduction in DMSO, which is unlikely in water solution as a simple hydrated ion because water will protonize substrate.

Wu, Xuefei; Li, Yunyan; Wu, Qingyin; Ding, Hong; Yan, Wenfu

2014-02-01

77

Syntheses and Applications of (Thio)Urea-Containing Chiral Quaternary Ammonium Salt Catalysts.  

PubMed

We herein report our efforts to obtain a new class of systematically modified bifunctional (thio)urea-containing quaternary ammonium salts based on easily obtainable chiral backbones. Among the different classes of catalysts that were successfully synthesized, those based on trans-1,2-cyclohexane diamine were found to be the most powerful for the asymmetric ?-fluorination of ?-keto esters. Selectivities up to 93:7 could be obtained by using only 2 mol-% of the optimized catalyst. The importance of the bifunctional nature of these catalysts was demonstrated by control experiments using simplified monofunctional catalyst analogues, which gave almost racemic product only. PMID:25339849

Novacek, Johanna; Waser, Mario

2014-02-01

78

A gemini quaternary ammonium poly (ether ether ketone) anion-exchange membrane for alkaline fuel cell: design, synthesis, and properties.  

PubMed

To reconcile the tradeoff between conductivity and dimensional stability in AEMs, a novel Gemini quaternary ammonium poly (ether ether ketone) (GQ-PEEK) membrane was designed and successfully synthesized by a green three-step procedure that included polycondensation, bromination, and quaternization. Gemini quaternary ammonium cation groups attached to the anti-swelling PEEK backbone improved the ionic conductivity of the membranes while undergoing only moderate swelling. The grafting degree (GD) of the GQ-PEEK significantly affected the properties of the membranes, including their ion-exchange capacity, water uptake, swelling, and ionic conductivity. Our GQ-PEEK membranes exhibited less swelling (? 40?% at 25-70?°C, GD 67?%) and greater ionic conductivity (44.8?mS?cm(-1) at 75?°C, GD 67?%) compared with single quaternary ammonium poly (ether ether ketone). Enhanced fuel cell performance was achieved when the GQ-PEEK membranes were incorporated into H2 /O2 single cells. PMID:25346412

Si, Jiangju; Lu, Shanfu; Xu, Xin; Peng, Sikan; Xiu, Ruijie; Xiang, Yan

2014-12-01

79

Pongamia pinnata modulates the oxidant-antioxidant imbalance in ammonium chloride-induced hyperammonemic rats.  

PubMed

The effect of Pongamia pinnata (an indigenous plant used in Ayurvedic Medicine in India) leaf extract (PPEt) on circulatory lipid peroxidation and antioxidant status was evaluated in ammonium chloride-induced hyperammonemic rats. Enhanced lipid peroxidation in the circulation of ammonium chloride-treated rats was accompanied by a significant decrease in the levels of vitamin A, vitamin C, vitamin E, reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT). PPEt-administered rats experienced a significant reduction in lipid peroxidation with a simultaneous elevation in antioxidant levels. Our results indicate that PPEt modulates these changes by reversing the oxidant-antioxidant imbalance during ammonium chloride-induced hyperammonemia and this could be due to its (i) antihyperammonemic effect by means of detoxifying excess ammonia, urea and creatinine and (ii) antioxidant property. The exact mechanism has to be still investigated and isolation of active constituents is required. PMID:16671965

Essa, M Mohamed; Subramanian, P

2006-06-01

80

The Listeria monocytogenes transposon Tn6188 provides increased tolerance to various quaternary ammonium compounds and ethidium bromide.  

PubMed

Tolerance of the foodborne pathogen Listeria monocytogenes to sublethal concentrations of disinfectants has been frequently reported. Particularly, quaternary ammonium compounds (QACs) such as benzalkonium chloride (BC) are often used in disinfectants and also as antiseptics in food industry and hospitals. Recently, we described Tn6188, a novel transposon in L. monocytogenes harbouring the transporter QacH, a molecular mechanism leading to increased tolerance to BC. In this study, we investigated the presence of Tn6188 within the genus Listeria spp. Our screening indicates that the distribution of Tn6188 may be limited to L. monocytogenes. We confirm that QacH is responsible for the observed increase in tolerance by complementation of a qacH deletion mutant and introducing qacH in a Tn6188 negative strain. We investigated the transporter's substrate spectrum by determining minimal inhibitory concentrations (MICs) and showed that QacH also confers higher tolerance towards other QACs and ethidium bromide (EtBr). This result was supported by increased expression of qacH in the presence of the various substrates as determined by quantitative reverse transcriptase PCR (qRT-PCR). In addition, we detected expression of a Tn6188 transposase gene and circular forms of Tn6188, suggesting activity and possible transfer of this transposon. PMID:25312720

Müller, Anneliese; Rychli, Kathrin; Zaiser, Andreas; Wieser, Cornelia; Wagner, Martin; Schmitz-Esser, Stephan

2014-12-01

81

Palladium-catalyzed amination of aryl chlorides and bromides with ammonium salts.  

PubMed

We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the primary arylamine over the diarylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes. PMID:25133675

Green, Rebecca A; Hartwig, John F

2014-09-01

82

Reporter-free potentiometric sensing of boronic acids and their reactions by using quaternary ammonium salt-functionalized polymeric liquid membranes.  

PubMed

The tremendous applications of boronic acids (BAs) in chemical sensing, medical chemistry, molecular assembly, and organic synthesis lead to an urgent demand for developing effective sensing methods for BAs. This paper reports a facile and sensitive potentiometric sensor scheme for heterogeneous detection of BAs based on their unexpected potential responses on quaternary ammonium salt-doped polymeric liquid membranes. (11)B NMR data reveal that a quaternary ammonium chloride can trigger the hydrolysis of an electrically neutral BA in an aprotic solvent. Using the quaternary ammonium salt as the receptor, the BA molecules can be extracted from the sample solution into the polymeric membrane phase and undergo the concomitant hydrolysis. Such salt-triggered hydrolysis generates H(+) ions, which can be coejected into the aqueous phase with the counterions (e.g., Cl(-)) owing to their high hydrophilicities. The perturbation on the ionic partition at the sample-membrane interface changes the phase boundary potential and thus enables the potentiometric sensing of BAs. In contrast to other transduction methods for BAs, for which labeled or separate reporters are exclusively required, the present heterogeneous sensing scheme allows the direct detection of BAs without using any reporter molecules. This technique shows superior detection limits for BAs (e.g., 1.0 × 10(-6) M for phenylboronic acid) as compared to previously reported methods based on colorimetry, fluorimetry, and mass spectrometry. The proposed sensing strategy has also been successfully applied to potentiometric indication of the BA reactions with hydrogen peroxide and saccharides, which allows indirect and sensitive detection of these important species. PMID:24484387

Wang, Xuewei; Yue, Dengfeng; Lv, Enguang; Wu, Lei; Qin, Wei

2014-02-18

83

Correlation between resistance of Pseudomonas aeruginosa to quaternary ammonium compounds and expression of outer membrane protein OprR.  

PubMed

The adaptation mechanism of Pseudomonas aeruginosa ATCC 10145 to quaternary ammonium compounds (QACs) was investigated. A P. aeruginosa strain with adapted resistance to QACs was developed by a standard broth dilution method. It was revealed that P. aeruginosa exhibited remarkable resistance to N-dodecylpyridinium iodide (P-12), whose structure is similar to that of a common disinfectant, cetylpyridinium chloride. Adapted resistance to benzalkonium chloride (BAC), which is commonly used as a disinfectant, was also observed in P. aeruginosa. Moreover, the P-12-resistant strain exhibited cross-resistance to BAC. Analysis of the outer membrane protein of the P-12-resistant strain by two-dimensional polyacrylamide gel electrophoresis showed a significant increase in the level of expression of a protein (named OprR) whose molecular mass was approximately 26 kDa. The actual function of OprR is not yet clear; however, OprR was expected to be an outer membrane-associated protein with homology to lipoproteins of other bacterial species, according to a search of the National Center for Biotechnology Information website with the BLAST program by use of the N-terminal sequence of OprR. A correlation between the level of expression of OprR and the level of resistance of P. aeruginosa to QACs was observed by using a PA2800 gene knockout mutant derived from the P-12-resistant strain. The knockout mutant recovered susceptibility not only to P-12 but also to BAC. These results suggested that OprR significantly participated in the adaptation of P. aeruginosa to QACs, such as P-12 and BAC. PMID:12821452

Tabata, Atsushi; Nagamune, Hideaki; Maeda, Takuya; Murakami, Keiji; Miyake, Yoichiro; Kourai, Hiroki

2003-07-01

84

Solution-processed white organic light-emitting diodes with enhanced efficiency by using quaternary ammonium salt doped conjugated polyelectrolyte.  

PubMed

Solution-processed white organic light emitting diodes (WOLEDs) with quaternary ammonium salt doped water/alcohol soluble conjugated polyelectrolyte, poly[(9,9-bis(3'-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluoren)] dibromide (PFNBr), as electron transport material has been fabricated. Compared with the undoped devices, the performances of such devices with a doped electron transport layer have been dramatically improved to be nearly twice high in luminous efficiency and nearly one-third in response time when the weight ratio of PFNBr to tetraethylammonium bromide (TEAB) was 10:3. Four kinds of quaternary ammonium salts have been investigated to be dopants in the conjugated polyelectrolyte electron transport layer. It has been shown that both the anions and the cations of quaternary ammonium salts can influence the device performance. The dopant who has both a smaller anion and a smaller cation size can exhibit a better device performance. In addition, ultraviolet photoelectron spectroscopy measurement and single-carrier device testing have been employed to investigate the reason why such quaternary ammonium salt dopants can make an obvious improvement in the device performance of WOLEDs. These findings will be beneficial to the progress in design and fabrication of solution-processed WOLEDs suitable for lighting. PMID:24786821

Tian, Yuan; Xu, Xinjun; Wang, Jinshan; Yao, Chuang; Li, Lidong

2014-06-11

85

Quaternary ammonium silane-functionalized, methacrylate resin composition with antimicrobial activities and self-repair potential  

PubMed Central

Design of antimicrobial polymers for enhancing healthcare issues and minimizing environmental problems is an important endeavor with both fundamental and practical implications. Quaternary ammonium silane-functionalized methacrylate (QAMS) represents an example of antimicrobial macromonomers synthesized by a sol-gel chemical route; these compounds possess flexible Si-O-Si bonds. In present work, a partially-hydrolyzed QAMS copolymerized with bis-GMA is introduced. This methacrylate resin was shown to possess desirable mechanical properties with both a high degree of conversion and minimal polymerization shrinkage. Kill-on-contact microbiocidal activities of this resin were demonstrated using single-species biofilms of Streptococcus mutans (ATCC 36558), Actinomyces naeslundii (ATCC 12104) and Candida albicans (ATCC 90028). Improved mechanical properties after hydration provided the proof-of-concept that QAMS-incorporated resin exhibits self-repair potential via water-induced condensation of organic modified silicate (ormosil) phases within the polymerized resin matrix. PMID:22659173

Gong, Shi-qiang; Niu, Li-na; Kemp, Lisa K.; Yiu, Cynthia K.Y.; Ryou, Heonjune; Qi, Yi-pin; Blizzard, John D.; Nikonov, Sergey; Brackett, Martha G.; Messer, Regina L.W.; Wu, Christine D.; Mao, Jing; Brister, L. Bryan; Rueggeberg, Frederick A.; Arola, Dwayne D.; Pashley, David H.; Tay, Franklin R.

2012-01-01

86

Critical review on the environmental fate of quaternary ammonium herbicides in soils devoted to vineyards.  

PubMed

Quaternary Ammonium Herbicides (QUATs) are nonselective contact herbicides, widely used at weed emergence to protect a wide range of crops. The benefits achieved by the use of these herbicides are indisputable. In soils devoted to vineyards, their uses increase the yield and the quality of the grapes for winemaking. However, several environmental dangers have emerged from the overuse of these compounds. Therefore, there has been a great interest in the presence of these compounds in soils, water, and food. Once in the soil, the mobility of these agrochemicals plays an important role in their fate and transport in the environment. This is why we mainly focused our review on (a) their physical and chemical properties and their activity, (b) the factors affecting their mobility in soils, (c) the quality of surrounding waters, and (d) the measures to reduce their contamination, especially in the case of agricultural soils devoted to vineyards. PMID:23614668

Pateiro-Moure, Mirian; Arias-Estévez, Manuel; Simal-Gándara, Jesús

2013-05-21

87

Altered sensitivity to a quaternary ammonium sanitizer in stressed Listeria innocua.  

PubMed

Chemical sanitizers are commonly used to inactivate Listeria monocytogenes and other Listeria species that persist in food-processing environments after cleaning. In this study, Listeria innocua cultures were exposed to acid, heat, cold, and starvation stress and then assessed for sensitivity to the quaternary ammonium compound cetrimide. Unstressed and stressed cultures were exposed to cetrimide for 3 min, neutralized, and plated on tryptic soy agar with yeast extract to determine the percentage of survivors. Relative to controls, L. innocua exposed to acid and starvation conditions was less sensitive to cetrimide, whereas heat and cold stress increased cetrimide sensitivity (P < 0.05). The diminished sensitivity of acid- and starvation-stressed L. innocua to cetrimide suggests that these stressors might increase the persistence of this organism within food-manufacturing facilities. In contrast, enhanced L. innocua sensitivity to cetrimide following heat and cold stress suggests that these interventions might increase sanitation efficacy. PMID:21132975

Moorman, M; Nettleton, W; Ryser, E; Linz, J; Pestka, J

2005-08-01

88

Perfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents  

SciTech Connect

Perfluorinated quaternary ammonium cations, [CF{sub 3}(CF{sub 2}){sub 7}(CH{sub 2}){sub 3}]{sub 3}CH{sub 3}N{sup +} (RFN{sup +}), were synthesized and used as counter cations for the [WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW{sub 9}O{sub 34}){sub 2}]{sup 12-} (M = Mn(II), Zn(II)), polyoxometalate. The (RFN{sup +}){sub 12}[WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW9O{sub 34}){sub 2}] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected both by the hydrophobicity of the solvent and the substrate.

Maayan, Galia; Fish, Richard H.; Neumann, Ronny

2003-05-28

89

Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids.  

PubMed

The alkaline stability of 26 different quaternary ammonium groups (QA) is investigated for temperatures up to 160?°C and NaOH concentrations up to 10?mol?L(-1) with the aim to provide a basis for the selection of functional groups for hydroxide exchange membranes in alkaline fuel cells and of ionic-liquid cations stable in basic conditions. Most QAs exhibit unexpectedly high alkaline stability with the exception of aromatic cations. ?-Protons are found to be far less susceptible to nucleophilic attack than previously suggested, whereas the presence of benzyl groups, nearby hetero-atoms, or other electron-withdrawing species promote degradation reactions significantly. Cyclic QAs proved to be exceptionally stable, with the piperidine-based 6-azonia-spiro[5.5]undecane featuring the highest half-life at the chosen conditions. Absolute and relative stabilities presented herein stand in contrast to literature data, the differences being ascribed to solvent effects on degradation. PMID:25431246

Marino, M G; Kreuer, K D

2015-02-01

90

Biofilm-eradicating properties of quaternary ammonium amphiphiles: simple mimics of antimicrobial peptides.  

PubMed

Bacterial biofilms are difficult to eradicate because of reduced antibiotic sensitivity and altered metabolic processes; thus, the development of new approaches to biofilm eradication is urgently needed. Antimicrobial peptides (AMPs) and quaternary ammonium cations (QACs) are distinct, yet well-known, classes of antibacterial compounds. By mapping the general regions of charge and hydrophobicity of QACs onto AMP structures, we designed a small library of QACs to serve as simple AMP mimics. In order to explore the role that cationic charge plays in biofilm eradication, structures were varied with respect to cationic character, distribution of charge, and alkyl side chain. The reported compounds possess minimum biofilm eradication concentrations (MBEC) as low as 25 ?M against Gram-positive biofilms, making them the most active anti-biofilm structures reported to date. These potent AMP mimics were synthesized in 1-2 steps and hint at the minimal structural requirements for biofilm destruction. PMID:25147134

Jennings, Megan C; Ator, Laura E; Paniak, Thomas J; Minbiole, Kevin P C; Wuest, William M

2014-10-13

91

Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties  

SciTech Connect

A new borate [C{sub 6}H{sub 16}N][B{sub 5}O{sub 6}(OH){sub 4}] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, ?=66.508(2)°, ?=74.751(2)°, ?=81.893(2)°. The [B{sub 5}O{sub 6}(OH){sub 4}]{sup ?} anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH{sub 3}){sub 3}(i-C{sub 3}H{sub 7}) N{sup +} cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K to 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents. - Graphical abstract: The new quaternary ammonium borate [C{sub 6}H{sub 17}N][B{sub 5}O{sub 6}(OH){sub 4}] contains a 3D supramolecular network formed by hydrogen bond linked [B{sub 5}O{sub 6}(OH){sub 4}]{sup ?} anions and shows tunable luminescent properties with temperature, excitation light, and solvents. Highlights: ? A novel quaternary ammonium borate was synthesized. ? It possesses a supramolecular network fomed by H-bonded [B{sub 5}O{sub 6}(OH){sub 4}]{sup ?} anions. ? This borate shows tunable luminescent properties with temperature, heating treatment, excitation light, and solvents.

Liang, Jie; Wang, Yong-gang [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Wang, Ying-xia, E-mail: wangyx@pku.edu.cn [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Liao, Fu-hui [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Lin, Jian-hua, E-mail: jhlin@pku.edu.cn [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2013-04-15

92

Synthesis and characterization of dimethacrylates containing quaternary ammonium functionalities for dental applications  

PubMed Central

Objectives The widespread incidence of recurrent caries highlights the need for improved dental restorative materials. The objective of this study was to synthesize low viscosity ionic dimethacrylate monomers (IDMAs) that contain quaternary ammoniums groups (antimicrobial functionalities) and are compatible with existing dental dimethacrylate-based monomers. Such monomers have the potential to copolymerize with other methacrylate monomers and produce antibacterial polymers. Methods Two monomers (IDMA-1 and IDMA-2) were synthesized using the Menschutkin reaction and incorporated at 0% to 30% (by mass) into a 1:1 (by mass) bisphenol A glycerolate dimethacrylate (BisGMA):triethylene glycol dimethacrylate (TEGDMA) resin. Resin viscosity was quantified using rheology, and polymer degree of conversion (DC) and surface charge density were measured using Fourier transform infrared spectroscopy (FTIR) and fluorescein binding, respectively. Effects of IDMA-1 on initial attachment of Streptococcus mutans and on viability and enzymatic activity (formazan reduction) of RAW 264.7 macrophage-like cells were quantified. Results IDMA-1 and IDMA-2 were prepared and characterized. IDMA-1 was miscible with BisGMA:TEGDMA and slightly increased the resin viscosity and DC. As expected, polymeric surface charge density increased with increasing IDMA-1. Incorporation of 10% IDMA-1 into BisGMA:TEGDMA reduced bacterial colonization without affecting viability or enzymatic activity of mammalian cells. Increasing IDMA-1 up to 30% had no additional effect on bacterial coverage, but ? 20% IDMA-1 significantly reduced macrophage density, viability, and enzymatic activity. Leachables from polymers containing IDMA-1 were not cytotoxic. Significance The Menschutkin reaction provides a facile, convenient means to synthesize new monomers with quaternary ammonium groups for dental and medical applications. PMID:22035983

Antonucci, Joseph M.; Zeiger, Diana N.; Tang, Kathy; Lin-Gibson, Sheng; Fowler, Bruce O.; Lin, Nancy J.

2011-01-01

93

Effect of ten quaternary ammonium cations on tetrachloromethane sorption to clay from water  

USGS Publications Warehouse

The mineral surface of Wyoming bentonite (clay) was modified by replacing inorganic ions by each of 10 quaternary ammonium compounds, and tetrachloromethane sorption to the modified sorbents from water was studied. Tetrachloromethane sorption from solution to clay modified with tetramethyl-, tetraethyl-, benzyltrimethyl-, or benzyltriethylammonium cations generally is characterized by relatively high solute uptake, isotherm nonlinearity, and competitive sorption (with trichloroethene as the competing sorbate). For these sorbents, the ethyl functional groups yield reduced sorptive capacity relative to methyl groups, whereas the benzyl group appears to have a similar effect on sorbent capacity as the methyl group. Sorption of tetrachloromethane to clay modified with dodecyldimethyl(2-phenoxyethyl)-, dodecyltrimethyl-, tetradecyltrimethyl-, hexadecyltrimethyl-, or benzyldimethylhexadecylammonium bromide is characterized by relatively low solute uptake, isotherm linearity, and noncompetitive sorption. For these sorbents, an increase in the size of the nonpolar functional group(s) causes an increase in the organic carbon normalized sorption coefficient (Koc). No measurable uptake of tetrachloromethane sorption by the unmodified clay or clay modified by ammonium bromide was observed. ?? 1990 American Chemical Society.

Smith, J.A.

1990-01-01

94

Separation of the isomers of benzene poly(carboxylic acid)s by quaternary ammonium salt via formation of deep eutectic solvents.  

PubMed

Because of similar properties and very low volatility, isomers of benzene poly(carboxylic acid)s (BPCAs) are very difficult to separate. In this work, we found that isomers of BPCAs could be separated efficiently by quaternary ammonium salts (QASs) via formation of deep eutectic solvents (DESs). Three kinds of QASs were used to separate the isomers of BPCAs, including the isomers of benzene tricarboxylic acids (trimellitic acid, trimesic acid, and hemimellitic acid) and the isomers of benzene dicarboxylic acids (phthalic acid and isophthalic acid). Among the QASs, tetraethylammonium chloride was found to have the best performance, which could completely separate BPCA isomers in methyl ethyl ketone solutions. It was found that the hydrogen bond forming between QAS and BPCA results in the selective separation of BPCA isomers. QAS in DES was regenerated effectively by the antisolvent method, and the regenerated QAS was reused four times with the same high efficiency. PMID:25351281

Hou, Yucui; Li, Jian; Ren, Shuhang; Niu, Muge; Wu, Weize

2014-11-26

95

Surface structures of PDMS incorporated with quaternary ammonium salts designed for antibiofouling and fouling release applications.  

PubMed

Poly(dimethylsiloxane) (PDMS) materials have been extensively shown to function as excellent fouling-release (FR) coatings in the marine environment. The incorporation of biocide moieties, such as quaternary ammonium salts (QAS), can impart additional antibiofouling properties to PDMS-based FR coating systems. In this study, the molecular surface structures of two different types of QAS-incorporated PDMS systems were investigated in different chemical environments using sum frequency generation vibrational spectroscopy (SFG). Specifically, a series of PDMS coatings containing either a QAS with a single ammonium salt group per molecule or a quaternary ammonium-functionalized polyhedral oligomeric silsesquioxane (Q-POSS) were measured with SFG in air, water, and artificial seawater (ASW) to investigate the relationships between the interfacial surface structures of these materials and their antifouling properties. Although previous studies have shown that the above-mentioned materials are promising contact-active antifouling coatings, slight variations of the QAS structure can lead to substantial differences in the antifouling performance. Indeed, the SFG results presented here indicated that the surface structures of these materials depend on several factors, such as the extent of quaternization, the molecular weight of the PDMS component, and the functional groups of the QAS used for incorporation into the PDMS matrix. It was concluded that in aqueous environments a lower extent of Q-POSS quaternization and the use of ethoxy (instead of methoxy) functional groups for QAS incorporation facilitated the extension of the alkyl chains away from the nitrogen atom of the QAS on the surface. The SFG results correlated well with the antifouling activity studies that indicated that the coatings exhibiting a lower concentration of longer alkyl chains protruding out of the surface can neutralize microorganisms more effectively, ultimately leading to better antifouling performance. Furthermore, the results of this study provide additional evidence that incorporated QAS exert their antimicrobial activity through a two-step interaction. The first step is the adsorption of the bacteria on the surface as a result of the electrostatic attraction between the negatively charged microorganisms and the positively charged QAS nitrogen atoms on the surface. The second step is the disruption of the cell membranes by the penetration of the QAS long, extended alkyl chains. PMID:23394402

Liu, Yuwei; Leng, Chuan; Chisholm, Bret; Stafslien, Shane; Majumdar, Partha; Chen, Zhan

2013-03-01

96

Effect of Quaternary Ammonium Carboxymethylchitosan on Release Rate In-vitro of Aspirin Sustained-release Matrix Tablets  

PubMed Central

The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with 10.27% of the maximum grafting degree was obtained. To assess the preliminary safety of this biopolymer, cell toxicity assay was employed. In order to further investigate quaternary ammonium carboxymethylchitosan application as pharmaceutical excipient, aspirin was chosen as model drug. The effect of quaternary ammonium CMCTS on aspirin release rate from sustained-release matrix tablets was examined by in-vitro dissolution experiments. The results showed that this biopolymer had a great potential in increasing the dissolution of poorly soluble drug. With the addition of CMCTS-CEDA, the final cumulative release rate of drug rose up to 90%. After 12 h, at the grade of 10, 20 and 50 cps, the drug release rate increased from 58.1 to 90.7%, from 64.1 to 93.9%, from 69.3 to 96.1%, respectively. At the same time, aspirin release rate from sustainedrelease model was found to be related to the amount of quaternary ammonium CMCTS employed. With the increase of CMCTS-CEDA content, the accumulated release rate increased from 69.1% to 86.7%. The mechanism of aspirin release from sustained-release matrix tablets was also preliminary studied to be Fick diffusion. These data demonstrated that the chitosan derivative has positive effect on drug release from sustained-release matrix tablets. PMID:24250627

Meng, Lingbin; Teng, Zhongqiu; Zheng, Nannan; Meng, Weiwei; Dai, Rongji; Deng, Yulin

2013-01-01

97

Selectivity Control in Synergistic Liquid-Liquid Anion Exchange of Univalent Anions via Structure-Specific Cooperativity between Quaternary Ammonium Cations and Anion Receptors  

SciTech Connect

Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence upon the structure of the alkylammonium cation. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). C4P has the unique ability in its cone anion-binding conformation to accept an appropriately sized electropositive species in the resulting cup formed by its four electron-rich pyrrole groups, while BTU is not expected to be predisposed for a specific host-guest interaction with the quaternary ammonium cations. It was therefore hypothesized that synergism between C4P and methyltri(C8,10)alkylammonium chloride (Aliquat 336) would be uniquely pronounced owing to insertion of the methyl group of the Aliquat cation into the C4P cup, and we present herein data supporting this expectation. While synergism is comparatively weak for both exchangers with the BTU receptor, synergism between C4P and Aliquat 336 is indeed so strong that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, unraveling the observed selectivity behavior and resulting in the estimation of binding constants for C4P with the ion pairs of A336+ with Cl , Br , OAcF3 , NO3 , and I . The uniquely strong positive cooperativity between A336 and C4P underscores the advantage of a supramolecular approach in the design of synergistic anion exchange systems.

Borman, Christopher J [ORNL; Bonnesen, Peter V [ORNL; Moyer, Bruce A [ORNL

2012-01-01

98

The effect of the ionic size of small quaternary ammonium BF? salts on electrochemical double layer capacitors.  

PubMed

By varying the cation size of quaternary ammonium salts, approximately 10% higher capacitance was achieved with trimethylethylammonium BF4 and trimethylpropylammonium BF4 relative to tetraethylammonium BF4 using microporous activated carbon (AC) electrodes. The ions carried solvation shells in the bulk electrolytes, but became desolvated within the narrow AC pores when the electrochemical double-layer capacitor was charged to a high potential. The capacitance depended on the size of the cation rather than that of the BF4 anion because the anion is smaller than the quaternary ammonium ions. The capacitance was found to be proportional to the reciprocal radii of the neat cations. The effective radius of the asymmetric trimethylpropylammonium ion was estimated to be 0.314 nm based on the present results. PMID:24935222

Koh, Ah Reum; Hwang, Byunghyun; Roh, Kwang Chul; Kim, Ketack

2014-08-01

99

Comparison of Theoretical and Experimental Values for the Effective Heat of Ablation of Ammonium Chloride  

NASA Technical Reports Server (NTRS)

Thermodynamic properties of ammonium chloride have been obtained and applied to a theoretical analysis of the shielding mechanism which reduces the rate of heat transfer to a body when ablation takes place at the surface. The analysis has considered the mechanism as one in which the material sublimes directly from the solid to the vapor phase. The results of the computation are compared with the experimental results obtained from the Langley 700-kilowatt arc jet.

Welker, Jean E.

1960-01-01

100

The inhibitive effect of some quaternary ammonium salts towards corrosion of aluminium in hydrochloric acid solution  

NASA Astrophysics Data System (ADS)

The inhibitive action of some quaternary ammonium salts towards the corrosion of aluminium in hydrochloric acid was tested by thermometric, mass loss and polarization measurements. Parallelism between the different methods was established. It is suggested that the tested compounds act as cathodic inhibitors. The inhibitors appear to function through adsorption, following the Temkin adsorption isotherm. The values of free energy of adsorption have been calculated and discussed. The inhibitor character of the additives depends upon the concentration as well as the composition of the inhibitor. Within the given homolegous series the contribution of the functional group to adsorption increases with the length of the chain. The aim of this article is to throw some light on the mechanism of inhibition of these bulky molecules on the corrosion of aluminium in hydrochloric acid. L'action inhibitrice de certains sels d'ammonium quaternaires vis-à-vis de la corrosion de l'aluminium dans l'acide chlorhydrique en solution a été testée par des mesures thermiques de perte de matière et de polarisation. Il est suggéré que les composés testés agissent comme des inhibiteurs cathodiques, fonctionnant par adsorption suivant l'isotherme de Temkin. Les énergies libres d'adsorption ont été calculées et discutées. Le caractère inhibiteur des additifs dépend aussi bien de leur concentration que de leur composition. Pour une série d'inhibiteurs homologues, la contribution à l'adsorption du groupe fonctionnel augmente avec la longueur de la chaîne. Le but de cet article est de mieux comprendre le mécanisme d'inhibition de ces grosses molécules sur la corrosion de l'aluminium dans l'acide chlorhydrique.

Mohamed, A.-M. K.; Al-Nadjm, A.; Fouda, A.-A. S.

1998-10-01

101

Discovery of novel quaternary ammonium derivatives of (3R)-quinuclidinyl carbamates as potent and long acting muscarinic antagonists.  

PubMed

Novel quaternary ammonium derivatives of N,N-disubstituted (3R)-quinuclidinyl carbamates have been identified as potent M(3) muscarinic antagonists with long duration of action in an in vivo model of bronchoconstriction. These compounds have also presented a high level of metabolic transformation (human liver microsomes). The synthesis, structure-activity relationships and biological evaluation of these compounds are reported. PMID:21524581

Prat, Maria; Buil, María Antonia; Fernández, Maria Dolors; Castro, Jordi; Monleón, Juan Manuel; Tort, Laia; Casals, Gaspar; Ferrer, Manuel; Huerta, Josep Maria; Espinosa, Sònia; López, Manuel; Segarra, Victor; Gavaldà, Amadeu; Miralpeix, Montserrat; Ramos, Israel; Vilella, Dolors; González, Marisa; Córdoba, Mònica; Cárdenas, Alvaro; Antón, Francisca; Beleta, Jorge; Ryder, Hamish

2011-06-01

102

Mucoadhesivity and release properties of quaternary ammonium-chitosan conjugates and their nanoparticulate supramolecular aggregates: an NMR investigation.  

PubMed

Selective relaxation rate measurements effectively proved the affinity of dexamethasone 21-phosphate disodium salt for quaternary ammonium-chitosan conjugates, their thiolated derivatives and the corresponding nanostructured aggregates. Affinity was also probed by dynamic dialysis. The release profile of dexamethasone loaded nanoparticles was defined by quantitative NMR and interrupted dialysis experiments, and mucoadhesivity of empty nanoparticles was effectively probed by selective relaxation rate measurements. PMID:24368100

Uccello-Barretta, Gloria; Balzano, Federica; Aiello, Federica; Senatore, Alessandro; Fabiano, Angela; Zambito, Ylenia

2014-01-30

103

Sensitive determination of quaternary ammonium salts by extraction-spectrophotometry of ion associates with bromophenol blue anion and coextraction  

Microsoft Academic Search

The chloroform extraction behaviour of the ion-associates of a Bromophenol Blue anion (BPB2? :blue) with quaternary ammonium cations (Q+) was examined. During extraction using Q+ with a small number of carbon atoms (Nc) or using Q+ with a large Nc and high concentrations of BPB2?, the addition of a proton to BPB2? gives HBPB? (yellow), which can be extracted as

Koichi Yamamoto

1995-01-01

104

Erythrocyte lysis in isotonic solution of ammonium chloride: theoretical modeling and experimental verification.  

PubMed

A mathematical model of erythrocyte lysis in isotonic solution of ammonium chloride is presented in frames of a statistical approach. The model is used to evaluate several parameters of mature erythrocytes (volume, surface area, hemoglobin concentration, number of anionic exchangers on membrane, elasticity and critical tension of membrane) through their sphering and lysis measured by a scanning flow cytometer (SFC). SFC allows measuring the light-scattering pattern (indicatrix) of an individual cell over the angular range from 10 degrees to 60 degrees . Comparison of the experimentally measured and theoretically calculated light scattering patterns allows discrimination of spherical from non-spherical erythrocytes and evaluation of volume and hemoglobin concentration for individual spherical cells. Three different processes were applied for erythrocytes sphering: (1) colloid osmotic lysis in isotonic solution of ammonium chloride, (2) isovolumetric sphering in the presence of sodium dodecyl sulphate and albumin in neutrally buffered isotonic saline, and (3) osmotic fragility test in hypotonic media. For the hemolysis in ammonium chloride, the evolution of distributions of sphered erythrocytes on volume and hemoglobin content was monitored in real-time experiments. The analysis of experimental data was performed in the context of a statistical approach, taking into account that parameters of erythrocytes vary from cell to cell. PMID:18083194

Chernyshev, Andrey V; Tarasov, Peter A; Semianov, Konstantin A; Nekrasov, Vyacheslav M; Hoekstra, Alfons G; Maltsev, Valeri P

2008-03-01

105

Urinary acidification assessed by simultaneous furosemide and fludrocortisone treatment: an alternative to ammonium chloride.  

PubMed

Distal renal tubular acidosis (RTA) can lead to rickets in children or osteomalacia in adults if undetected. This disorder is normally diagnosed by means of an oral ammonium chloride-loading test; however, the procedure often leads to vomiting and abandonment of the test. In this study, we assess an alternative, more palatable approach to test urinary acidification. This was achieved by the simultaneous oral administration of the diuretic furosemide and the mineralocorticoid fludrocortisone to increase distal tubular sodium delivery, principal cell sodium reabsorption, and alpha-intercalated cell proton secretion. We evaluated 11 control subjects and 10 patients with known distal RTA by giving oral ammonium chloride or furosemide/fludrocortisone in random order on separate days. One control and two patients were unable to complete the study owing to vomiting after NH4Cl; however, there were no adverse effects with the furosemide/fludrocortisone treatment. The urine pH decreased to less than 5.3 in the controls with both tests, whereas none of the patients was able to lower the urine pH below 5.3 with either test. We conclude that the simultaneous administration of furosemide and fludrocortisone provides an easy, effective, and well-tolerated alternative to the standard ammonium chloride urinary acidification test for the diagnosis of distal RTA. PMID:17410104

Walsh, S B; Shirley, D G; Wrong, O M; Unwin, R J

2007-06-01

106

21 CFR 878.4015 - Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC) additive.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4015 Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC)...

2014-04-01

107

21 CFR 878.4015 - Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC) additive.  

Code of Federal Regulations, 2012 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4015 Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC)...

2012-04-01

108

21 CFR 878.4015 - Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC) additive.  

Code of Federal Regulations, 2010 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4015 Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC)...

2010-04-01

109

21 CFR 878.4015 - Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC) additive.  

Code of Federal Regulations, 2011 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4015 Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC)...

2011-04-01

110

21 CFR 878.4015 - Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC) additive.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4015 Wound dressing with poly (diallyl dimethyl ammonium chloride) (pDADMAC)...

2013-04-01

111

Degradation of imidazolium- and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone) anion exchange membranes.  

PubMed

Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by ¹H NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 °C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 °C but much lower stability at 80 °C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed. PMID:23067022

Chen, Dongyang; Hickner, Michael A

2012-11-01

112

Quatsomes: vesicles formed by self-assembly of sterols and quaternary ammonium surfactants.  

PubMed

Thermodynamically stable nanovesicle structures are of high interest for academia and industry in a wide variety of application fields, ranging from preparation of nanomaterials to nanomedicine. Here, we show the ability of quaternary ammonium surfactants and sterols to self-assemble, forming stable amphiphilic bimolecular building-blocks with the appropriate structural characteristics to form in aqueous phases, closed bilayers, named quatsomes, with outstanding stability, with time and temperature. The molecular self-assembling of cholesterol and surfactant cetyltrimethylammonium bromide (CTAB) was studied by quasi-elastic light scattering, cryogenic transmission electron microscopy, turbidity (optical density) measurements, and molecular dynamic simulations with atomistic detail, upon varying the cholesterol-to-surfactant molar ratio. As pure species, CTAB forms micelles and insoluble cholesterol forms crystals in water. However, our molecular dynamic simulations reveal that the synergy between CTAB and cholesterol molecules makes them self-assemble into bimolecular amphiphiles and then into bilayers in the presence of water. These bilayers have the same structure of those formed by double-tailed unimolecular amphiphiles. PMID:23647396

Ferrer-Tasies, Lidia; Moreno-Calvo, Evelyn; Cano-Sarabia, Mary; Aguilella-Arzo, Marcel; Angelova, Angelina; Lesieur, Sylviane; Ricart, Susagna; Faraudo, Jordi; Ventosa, Nora; Veciana, Jaume

2013-06-01

113

Mitochondrial Dysfunction Is the Focus of Quaternary Ammonium Surfactant Toxicity to Mammalian Epithelial Cells  

PubMed Central

Surfactants have long been known to have microbicidal action and have been extensively used as antiseptics and disinfectants for a variety of general hygiene and clinical purposes. Among surfactants, quaternary ammonium compounds (QAC) are known to be the most useful antiseptics and disinfectants. However, our previous toxicological studies showed that QAC are also the most toxic surfactants for mammalian cells. An understanding of the mechanisms that underlie QAC toxicity is a crucial first step in their rational use and in the design and development of more effective and safer molecules. We show that QAC-induced toxicity is mediated primarily through mitochondrial dysfunction in mammalian columnar epithelial cell cultures in vitro. Toxic effects begin at sublethal concentrations and are characterized by mitochondrial fragmentation accompanied by decreased cellular energy charge. At very low concentrations, several QAC act on mitochondrial bioenergetics through a common mechanism of action, primarily by inhibiting mitochondrial respiration initiated at complex I and, to a lesser extent, by slowing down coupled ADP phosphorylation. The result is a reduction of cellular energy charge which, when reduced below 50% of its original value, induces apoptosis. The lethal effects are shown to be primarily a result of this process. At higher doses (closer to the critical micellar concentration), QAC induce the complete breakdown of cellular energy charge and necrotic cell death. PMID:23529737

Inácio, Ângela S.; Costa, Gabriel N.; Domingues, Neuza S.; Santos, Maria S.; Moreno, António J. M.; Vaz, Winchil L. C.

2013-01-01

114

Properties of new low melting point quaternary ammonium salts with bis(trifluoromethanesulfonyl)imide anion  

NASA Astrophysics Data System (ADS)

Eight new monocationic quaternary ammonium (QA) salts with the bis(trifluoromethanesulfonyl)imide (TFSI) anion were prepared by metathesis using our previously reported QA halides as precursors. New salts were characterized both in liquid and solid state using 1H and 13C NMR techniques, mass spectroscopy and elemental analysis together with X-ray diffraction and thermoanalytical methods. In addition, residual water content, viscosity and conductivity measurements were made for three of the room-temperature ionic liquids (RTILs). The crystal structures of three compounds were determined by X-ray single crystal diffraction. Powder diffraction was used to study the crystallinity of the solid salts and to compare structural similarities between the single crystals and the microcrystalline bulk powders. Three of the salts are liquid below room temperature, having broad liquid ranges (˜300 °C), and in total five out of eight salts melt below 100 °C. Moreover, powder diffraction data of the two RTILs were able to be measured at sub-ambient temperatures using in situ low-temperature powder X-ray diffraction revealing high crystallinity on both RTILs below their freezing point. The RTILs presented relatively high conductivities (˜0.1-0.2 S m -1) and moderate to relatively low viscosities. The determined physicochemical properties of the reported ILs suggest their applicability on various applications such as heat transfer fluids, high temperature synthesis and lubricants.

Kärnä, Minna; Lahtinen, Manu; Kujala, Anna; Hakkarainen, Pirkko-Leena; Valkonen, Jussi

2010-11-01

115

Determination of quaternary ammonium herbicides in soils. Comparison of digestion, shaking and microwave-assisted extractions.  

PubMed

Very challenging analytical problems arise from the continuous introduction in agriculture of chemical pesticides. Particularly, diquat (DQ), paraquat (PQ) and difenzoquat (DF) are a difficult group of quaternary ammonium herbicides to analyze. This article reviews and addresses the most relevant analytical methods for determining the selected herbicides in soil. We discuss and critically evaluate procedures, such as digestion-based methods, shaking extraction and microwave-assisted extraction (MAE). Clean-up of extracts was performed by solid-phase extraction (SPE) using silica cartridges. Detection of these herbicides was carried out by liquid chromatography (LC) coupled to UV detection and mass spectrometry (MS) as confirmatory technique. Recoveries ranged from 98% to 100% by digestion, from no recovered to 61% by shaking, and from 102% to 109% by MAE with estimated quantification limits between 1.0 microg/kg and 2.0 microg/kg by digestion and 5.0 mug/kg and 7.5 microg/kg by MAE using LC/MS-MS as detection technique. The recoveries obtained under the optimum conditions are compared and discussed with those obtained from digestion extraction and MAE. PMID:18423476

Pateiro-Moure, Miriam; Martínez-Carballo, Elena; Arias-Estévez, Manuel; Simal-Gándara, Jesús

2008-07-01

116

CO2 capture from simulated fuel gas mixtures using semiclathrate hydrates formed by quaternary ammonium salts.  

PubMed

In order to investigate the feasibility of semiclathrate hydrate-based precombustion CO2 capture, thermodynamic, kinetic, and spectroscopic studies were undertaken on the semiclathrate hydrates formed from a fuel gas mixture of H2 (60%) + CO2 (40%) in the presence of quaternary ammonium salts (QASs) such as tetra-n-butylammonium bromide (TBAB) and fluoride (TBAF). The inclusion of QASs demonstrated significantly stabilized hydrate dissociation conditions. This effect was greater for TBAF than TBAB. However, due to the presence of dodecahedral cages that are partially filled with water molecules, TBAF showed a relatively lower gas uptake than TBAB. From the stability condition measurements and compositional analyses, it was found that with only one step of semiclathrate hydrate formation with the fuel gas mixture from the IGCC plants, 95% CO2 can be enriched in the semiclathrate hydrate phase at room temperature. The enclathration of both CO2 and H2 in the cages of the QAS semiclathrate hydrates and the structural transition that results from the inclusion of QASs were confirmed through Raman and (1)H NMR measurements. The experimental results obtained in this study provide the physicochemical background required for understanding selective partitioning and distributions of guest gases in the QAS semiclathrate hydrates and for investigating the feasibility of a semiclathrate hydrate-based precombustion CO2 capture process. PMID:23718261

Park, Sungwon; Lee, Seungmin; Lee, Youngjun; Seo, Yongwon

2013-07-01

117

Identification and composition of emerging quaternary ammonium compounds in municipal sewage sludge in China.  

PubMed

Quaternary ammonium compounds (QACs) have raised considerable attention due to their wide commercial applications and recent discovery of unknown persistent analogues in aqueous environment. In this work, the occurrence and distribution of alkyltrimethylammonium (ATMAC), benzylakyldimethylethylammonium (BAC) and dialkyldimethylammonium (DADMAC) homologues were investigated in fifty-two municipal sewage sludge samples. ATMAC C10-18, BAC C8-18 and paired DADMAC C8:8-C18:18 as well as emerging homologues such as ATMAC-20, 22 and mixed DADMAC-16:18 and 14:16 were present. Furthermore, paired DADMAC-20:20 and mixed DADMAC-14:18, 18:20 were identified for the first time by nontarget qualitative strategies. A triple quadruple mass spectrometer quantification method was also initially verified with the aid of laboratory synthesized standards for the analysis of the mixed DADMACs with no certificated commercial standards currently available. The total concentrations of ATMACs, BACs and DADMACs were in the range of 0.38-293, 0.09-191 and 0.64-344 ?g/g dry weight, respectively, and particularly, mixed DADMACs constituted 39 ± 7% of total DADMAC concentrations. The concentrations and profiles of individual homologues further suggested different QAC applications and fate in China. Significant correlations were also found among the concentrations of various QAC homologues as well as wastewater treatment plant (WWTP) characteristics (total organic carbon contents and daily treatment volumes). PMID:24654682

Ruan, Ting; Song, Shanjun; Wang, Thanh; Liu, Runzeng; Lin, Yongfeng; Jiang, Guibin

2014-04-15

118

Quaternary ammonium silane-functionalized, methacrylate resin composition with antimicrobial activities and self-repair potential.  

PubMed

The design of antimicrobial polymers to address healthcare issues and minimize environmental problems is an important endeavor with both fundamental and practical implications. Quaternary ammonium silane-functionalized methacrylate (QAMS) represents an example of antimicrobial macromonomers synthesized by a sol-gel chemical route; these compounds possess flexible Si-O-Si bonds. In present work, a partially hydrolyzed QAMS co-polymerized with 2,2-[4(2-hydroxy 3-methacryloxypropoxy)-phenyl]propane is introduced. This methacrylate resin was shown to possess desirable mechanical properties with both a high degree of conversion and minimal polymerization shrinkage. The kill-on-contact microbiocidal activities of this resin were demonstrated using single-species biofilms of Streptococcus mutans (ATCC 36558), Actinomyces naeslundii (ATCC 12104) and Candida albicans (ATCC 90028). Improved mechanical properties after hydration provided the proof-of-concept that QAMS-incorporated resin exhibits self-repair potential via water-induced condensation of organic modified silicate (ormosil) phases within the polymerized resin matrix. PMID:22659173

Gong, Shi-qiang; Niu, Li-Na; Kemp, Lisa K; Yiu, Cynthia K Y; Ryou, Heonjune; Qi, Yi-Pin; Blizzard, John D; Nikonov, Sergey; Brackett, Martha G; Messer, Regina L W; Wu, Christine D; Mao, Jing; Bryan Brister, L; Rueggeberg, Frederick A; Arola, Dwayne D; Pashley, David H; Tay, Franklin R

2012-09-01

119

The inhibitory effects of quaternary ammonium methacrylates on soluble and matrix-bound MMPs.  

PubMed

Matrix metalloproteinases (MMPs) bound to dentin contribute to the progressive degradation of collagen fibrils in hybrid layers created by dentin adhesives. This study evaluated the MMP-inhibiting potential of quaternary ammonium methacrylates (QAMs), with soluble rhMMP-9 and a matrix-bound endogenous MMP model. Six different QAMs were initially screened by a rhMMP-9 colorimetric assay. For the matrix-bound endogenous MMPs, we aged demineralized dentin beams for 30 days in calcium- and zinc-containing media (CM; control), chlorhexidine, or QAMs in CM to determine the changes in dry mass loss and solubilization of collagen peptides against baseline levels. The inhibitory effects of QAMs on soluble rhMMP-9 varied between 34 and 100%. Beams incubated in CM showed a 29% decrease in dry mass (p < 0.05), whereas beams incubated with QAMs showed only 0.2%-6% loss of dry mass. Significantly more solubilized collagen was detected from beams incubated in CM (p < 0.05). It is concluded that QAMs exhibited dentin MMP inhibition comparable with that of chlorhexidine, but required higher concentrations. PMID:21212315

Tezvergil-Mutluay, A; Agee, K A; Uchiyama, T; Imazato, S; Mutluay, M M; Cadenaro, M; Breschi, L; Nishitani, Y; Tay, F R; Pashley, D H

2011-04-01

120

Controlling wettability and hydrophobicity of organoclays modified with quaternary ammonium surfactants.  

PubMed

The montmorillonite clays were modified with quaternary ammonium salts (QASs) having different alkyl chain lengths and a benzyl substitute group. The modified organoclays were characterized by different analytical techniques. The wettability and hydrophilicity/hydrophobicity of the modified clays was evaluated using water or oil penetration (adsorption) and contact angle measurements. The loading of QASs was in the range of 0.60-0.75 mmol/g per clay, irrespective of the type of QAS used for the modification of the clay. From the analytical investigations, it was elucidated that the modification of clay with QAS affected the structural, textural, and surface properties. Moreover, it should be noted that the modification with QAS having benzyl substitute group resulted in water-non-wettable and superhydrophobic surface, whereas clays modified with QAS without benzyl substitute group became more water-wettable and hydrophilic than the pristine clay. The presence of benzyl groups on the clay prevents water from penetration into the inter-clay or interlayer spacing, which yields the hydrophobic surface. These behaviors can arise from molecular arrangement of QAS on clay but not be attributable to the amount of QASs, and the surface area, size, and zeta potential of particles. PMID:23830282

Shah, Kinjal J; Mishra, Manish Kumar; Shukla, Atindra D; Imae, Toyoko; Shah, Dinesh O

2013-10-01

121

Structural and conformational properties of the quaternary ammonium ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium iodide  

NASA Astrophysics Data System (ADS)

We have used single-crystal X-ray structural analysis and Raman spectroscopy to study the crystalline structure and conformational properties of a quaternary ammonium ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium iodide ([DEME][I]). At 296 K the crystal structure of [DEME][I] was determined to be monoclinic (P21/a, Z = 8) with a = 13.216 (5), b = 12.842 (3), c = 14.417 (6), ? = 104.10 (3)°, and V = 2373.1 (15) Å3. With results from X-ray diffraction measurements and density functional theory calculations, we have identified two folded forms: Gauche--Gauche--gauche--gauche--trans and Gauche+-Gauche+-gauche+-gauche+-trans conformers, having intramolecular attractive N+⋯O- interactions of [DEME]+ in the single-crystal state. In the liquid state, [DEME]+ exists in equilibrium between folded and (non-interacting) extended forms.

Tsuge, Shu; Uno, Kenjiro; Hanasaki, Tomonori; Takekiyo, Takahiro; Abe, Hiroshi; Yoshimura, Yukihiro

2014-02-01

122

Mixtures of quaternary ammonium compounds and anionic organic compounds in the aquatic environment: Elimination and biodegradability in the closed bottle test monitored by LC-MS/MS.  

PubMed

Quaternary ammonium compounds (QACs) are widely used as disinfectants, detergents and fabric softeners. Anionic detergents are one of the most widely used chemical substances. QACs and anionic surfactants can form ionic pairs. In the present study we investigated the biodegradability of QACs in the presence of different anionic surfactants. The biodegradability of three QACs, namely benzalkonium chloride (BAC), didecyldimethylammonium chloride (DDMAC) and ethacridine lactate (EL), when applied as single substances and in combination with anionic surfactants such as benzene sulfonic acid (BSA), LAS, naphthalene sulfonic acid (NSA) and sodium dodecylsulfonate (SDS) was studied applying the closed bottle test (CBT) [OECD 301D, 1992. Guidelines for Testing of Chemicals. Closed bottle test. Organisation of Economic Cooperation and Development, Paris] at a ratio of 1:1 (mol:mol). Biodegradation was monitored by measuring oxygen concentration in the test vessels with an oxygen electrode in accordance with international standard methods [ISO 5414, 1990. Water quality - determination of dissolved oxygen. In: German Standard Methods for the Examination of Water, Wastewater and Sludge. VCH Verlagsgesellschaft, Weinheim, New York, Basel Cambridge]. Primary elimination of the QACs and of LAS was monitored by LC-MS/MS. There was little biodegradability of the QACs as either single compounds or in the presence of organic counter ions. The biodegradability of the organic counter ions was lower in the presence of QACs as compared to the single substances. Primary elimination of the QACs by sorption took place. PMID:18439651

Sütterlin, H; Alexy, R; Coker, A; Kümmerer, K

2008-06-01

123

Effect of higher minimum inhibitory concentrations of quaternary ammonium compounds in clinical E. coli isolates on antibiotic susceptibilities and clinical outcomes.  

PubMed

Quaternary ammonium compounds (QACs) are cationic surfactants used as preservatives and environmental disinfectants. Limited data are available regarding the effect of QACs in the clinical setting. We performed a prospective cohort study in 153 patients with Escherichia coli bacteraemia from February to September 2008 at University Hospital in Rennes. The minimum inhibitory concentrations (MICs) of antibiotics and QACs alkyldimethylbenzylammonium chloride (ADBAC) and didecyldimethylammonium chloride (DDAC) were determined by the agar dilution method. The capacity of biofilm production was assayed using the Crystal Violet method, and mutation frequencies by measuring the capacity of strains to generate resistance to rifampicin. Logistic regression analysis showed that one of the significant factors related to low MICs for ADBAC (?16 mg/L) and DDAC (?8 mg/L), was cotrimoxazole susceptibility (odds ratio: 3.72; 95% confidence interval: 1.22-11.24; P=0.02 and OR: 3.61; 95% CI: 1.56-7.56; P<0.01, respectively). Antibiotic susceptibility to cotrimoxazole was strongly associated with susceptibility to amoxicillin and nalidixic acid (P<0.01). Community-acquired or healthcare-associated bacteraemia, severity of bacteraemia, and patient outcome were independent of the MICs of ADBAC and DDAC. Our findings demonstrate an epidemiological relationship between higher MIC values of QACs in clinical E. coli isolates and antibiotic resistance. PMID:21807440

Buffet-Bataillon, S; Branger, B; Cormier, M; Bonnaure-Mallet, M; Jolivet-Gougeon, A

2011-10-01

124

Identification of quaternary ammonium compounds as potent inhibitors of hERG potassium channels  

SciTech Connect

The human ether-a-go-go-related gene (hERG) channel, a member of a family of voltage-gated potassium (K{sup +}) channels, plays a critical role in the repolarization of the cardiac action potential. The reduction of hERG channel activity as a result of adverse drug effects or genetic mutations may cause QT interval prolongation and potentially leads to acquired long QT syndrome. Thus, screening for hERG channel activity is important in drug development. Cardiotoxicity associated with the inhibition of hERG channels by environmental chemicals is also a public health concern. To assess the inhibitory effects of environmental chemicals on hERG channel function, we screened the National Toxicology Program (NTP) collection of 1408 compounds by measuring thallium influx into cells through hERG channels. Seventeen compounds with hERG channel inhibition were identified with IC{sub 50} potencies ranging from 0.26 to 22 {mu}M. Twelve of these compounds were confirmed as hERG channel blockers in an automated whole cell patch clamp experiment. In addition, we investigated the structure-activity relationship of seven compounds belonging to the quaternary ammonium compound (QAC) series on hERG channel inhibition. Among four active QAC compounds, tetra-n-octylammonium bromide was the most potent with an IC{sub 50} value of 260 nM in the thallium influx assay and 80 nM in the patch clamp assay. The potency of this class of hERG channel inhibitors appears to depend on the number and length of their aliphatic side-chains surrounding the charged nitrogen. Profiling environmental compound libraries for hERG channel inhibition provides information useful in prioritizing these compounds for cardiotoxicity assessment in vivo.

Xia Menghang, E-mail: mxia@mail.nih.gov [NIH Chemical Genomics Center, National Institutes of Health, Bethesda, MD (United States); Shahane, Sampada A.; Huang, Ruili; Titus, Steven A. [NIH Chemical Genomics Center, National Institutes of Health, Bethesda, MD (United States); Shum, Enoch; Zhao Yong [Cerep, Inc., Redmond, WA (United States); Southall, Noel; Zheng, Wei [NIH Chemical Genomics Center, National Institutes of Health, Bethesda, MD (United States); Witt, Kristine L.; Tice, Raymond R. [National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States); Austin, Christopher P. [NIH Chemical Genomics Center, National Institutes of Health, Bethesda, MD (United States)

2011-05-01

125

Superposition model study of Cr3+ doped tetra methyl ammonium cadmium chloride  

NASA Astrophysics Data System (ADS)

The zero field splitting parameter D of Cr3+ doped in tetra methyl ammonium cadmium chloride (TMCC) is calculated with perturbation formula using microscopic spin Hamiltonian theory and crystal field parameters from superposition model. The theoretically calculated ZFS parameter for Cr3+ in TMCC single crystal is compared with the experimental value obtained by electron paramagnetic resonance (EPR). The local structure distortion is considered to obtain the crystal field parameters. The theoretical study gives the ZFS parameter D similar to that from experiment. However, calculation considering small distortion in local structure around Cr3+ gives better agreement with the experimental value of ZFS parameter.

Kripal, Ram; Yadav, Awadhesh Kumar

2015-02-01

126

Aerogels from quaternary ammonium-functionalized cellulose nanofibers for rapid removal of Cr(VI) from water.  

PubMed

An efficient heavy metal adsorbent from quaternary ammonium-functionalized cellulose nanofiber aerogels was successfully developed. The highly porous aerogel could well retain its large specific surface area, which allowed rapid and effective removal of Cr(VI) from contaminated water. The aerogel adsorbent became mechanically robust after chemical crosslinking. It could be easily separated from water after adsorption without complicated centrifugation or filtration process. With only 1g of aerogel, more than 99% of Cr(VI) in 1L of 1mg/L solution could be removed in 50 min. Besides, the aerogel also exhibited excellent reusability. PMID:25037403

He, Xu; Cheng, Long; Wang, Yaru; Zhao, Jiangqi; Zhang, Wei; Lu, Canhui

2014-10-13

127

Comparative studies of the biological activities of lysosomotropic aminoesters and quaternary ammonium salts on the yeast Saccharomyces cerevisiae.  

PubMed

The biological activity of lysosomotropic n-alkyl N,N-dimethylglycinates (DMG-n) was compared with that of a quaternary ammonium salt IM (methochloride of DMG-12). The activity of the glycinates appeared to be carbon chain length dependent and was similar at pH 6 and pH 8. Nutritional auxotrophy and respiratory deficiencies have no influence on DMG-n sensitivity. Both IM and DMG-n inhibit plasma membrane H+-ATPase activity while mitochondrial ATPase is relatively non-sensitive to glycinates. No cross-resistance to IM and DMG-n was observed. PMID:11753434

Ob?ak, E; Lachowicz, T M; Luczy?ski, J; Witek, S

2001-01-01

128

Determination of quaternary ammonium compounds in oranges and cucumbers using QuEChERS extraction and ultra-performance liquid chromatography/tandem mass spectrometry.  

PubMed

A simple and fast method has been developed for determining relevant quaternary ammonium compounds in cucumber and orange samples. The target compounds were benzoalkonium chloride (BAC-10, BAC-12, BAC-14, and BAC-16), didecyldimethylammonium chloride, and benzethonium chloride, all frequently used biocides in the agrifood industry. An extraction based on the buffered Quick, Easy, Cheap, Effective, Rugged, and Safe method and determination by ultra-performance LC/MS/MS that eluted the biocides in less than 5 min were used. The method was fully validated and implemented in a UNE-EN-ISO/IEC 17025 accredited laboratory for its application to the analysis of real samples. Performance characteristics of the method are reported, including an estimation of measurement uncertainty. Calibration curves were set between 0.01 and 0.150 mg/kg, LOD values were always between 0.4 and 1.0 microg/kg, LOQ values were in the range 1-4 microg/kg, recovery was between 81 and 115%, intraday and interday precision were always lower than 17% (expressed as RSD), and expanded uncertainty was always lower than 40%. The validation was accomplished for the two studied matrixes at spiking concentrations of 0.011 and 0.050 mg/kg. The method has been applied to the analysis of 30 cucumber and orange samples that were found to contain concentrations of BAC-12 that ranged between 0.015 and 0.210 mg/kg and of BAC-14 between 0.018 and 0.081 mg/kg. PMID:25145132

Arrebola-Liébanas, Francisco Javier; Abdo, María Angeles Herrera; Moreno, José Luis Fernandez; Martínez-Vidal, José L; Frenich, Antonia Garrido

2014-01-01

129

Improvement of the adsorption of quaternary ammonium on polypropylene affinity membrane through the control of its surface properties.  

PubMed

Polypropylene fiber meshes were plasma-treated in order to attach new chemical functions corresponding to acidic or basic groups without altering the roughness of such thin material. An almost complete wettability of these plasma-treated materials is obtained. Because of the plasma-grafting of acid or amino moieties, such surface treatment allows increasing the adsorption rate of quaternary ammonium molecule like Aliquat 336. This increase was explained by specific interactions of ammonium head of the Aliquat 336 and hydrophilic group of plasma-treated PP, followed by the adsorption of a further layer of Aliquat 336 through hydrophobic interactions of its hydrocarbon chain. These interactions between the carrier and the polymeric surface were characterized leading to physisorption mechanism. Such new material could be applied to the extraction process since no evidence of aging was given. PMID:24411392

Hachache, Naima; Bal, Youcef; Debarnot, Dominique; Poncin-Epaillard, Fabienne

2014-02-01

130

Antioxidant Potential of Momordica Charantia in Ammonium Chloride-Induced Hyperammonemic Rats  

PubMed Central

The present study was aimed to investigate the antioxidant potential of Momordica charantia fruit extract (MCE) in ammonium chloride-induced (AC) hyperammonemic rats. Experimental hyperammonemia was induced in adult male Wistar rats (180–200?g) by intraperitoneal injections of ammonium chloride (100?mg?kg?1 body weight) thrice a week. The effect of oral administration (thrice a week for 8 consecutive weeks) of MCE (300?mg?kg?1 body weight) on blood ammonia, plasma urea, serum liver marker enzymes and oxidative stress biomarkers in normal and experimental animals was analyzed. Hyperammonemic rats showed a significant increase in the activities of thiobarbituric acid reactive substances, hydroperoxides and liver markers (alanine transaminase, aspartate transaminase and alkaline phosphatase), and the levels of glutathione peroxidase, superoxide dismutase, catalase and reduced glutathione were decreased in the liver and brain tissues. Treatment with MCE normalized the above-mentioned changes in hyperammonemic rats by reversing the oxidant-antioxidant imbalance during AC-induced hyperammonemia, and offered protection against hyperammonemia. Our results indicate that MCE exerting the antioxidant potentials and maintaining the cellular integrity of the liver tissue could offer protection against AC-induced hyperammonemia. However, the exact underlying mechanism is yet to be investigated, and examination of the efficacy of the active constituents of the M. charantia on hyperammonemia is desirable. PMID:20047891

Thenmozhi, A. Justin; Subramanian, P.

2011-01-01

131

Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors  

NASA Technical Reports Server (NTRS)

Double-layer capacitors are unique energy storage devices, capable of supporting large current pulses as well as a very high number of charging and discharging cycles. The performance of doublelayer capacitors is highly dependent on the nature of the electrolyte system used. Many applications, including for electric and fuel cell vehicles, back-up diesel generators, wind generator pitch control back-up power systems, environmental and structural distributed sensors, and spacecraft avionics, can potentially benefit from the use of double-layer capacitors with lower equivalent series resistances (ESRs) over wider temperature limits. Higher ESRs result in decreased power output, which is a particular problem at lower temperatures. Commercially available cells are typically rated for operation down to only 40 C. Previous briefs [for example, Low Temperature Supercapacitors (NPO-44386), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), p. 32, and Supercapacitor Electrolyte Solvents With Liquid Range Below 80 C (NPO-44855), NASA Tech Briefs, Vol. 34, No. 1 (January 2010), p. 44] discussed the use of electrolytes that employed low-melting-point co-solvents to depress the freezing point of traditional acetonitrile-based electrolytes. Using these modified electrolyte formulations can extend the low-temperature operational limit of double-layer capacitors beyond that of commercially available cells. This previous work has shown that although the measured capacitance is relatively insensitive to temperature, the ESR can rise rapidly at low temperatures, due to decreased electrolyte conductance within the pores of the high surface- area carbon electrodes. Most of these advanced electrolyte systems featured tetraethylammonium tetrafluoroborate (TEATFB) as the salt. More recent work at JPL indicates the use of the asymmetric quaternary ammonium salt triethylmethylammonium tetrafluoroborate (TEMATFB) or spiro-(l,l')-bipyrrolidium tetrafluoroborate (SBPBF4) in a 1:1 by volume solvent mixture of acetonitrile (AN) and methyl formate (MF) enables double-layer capacitor cells to operate well below -40 C with a relatively low ESR. Typically, a less than twofold increase in ESR is observed at -65 C relative to room-temperature values, when these modified electrolyte blends are used in prototype cells. Double-layer capacitor coin cells filled with these electrolytes have displayed the lowest measured ESR for an organic electrolyte to date at low temperature (based on a wide range of electrolyte screening studies at JPL). The cells featured high-surface-area (approximately equal to 2,500 m/g) carbon electrodes that were 0.50 mm thick and 1.6 cm in diameter, and coated with a thin layer of platinum to reduce cell resistance. A polyethylene separator was used to electrically isolate the electrodes.

Brandon, Erik J.; Smart, Marshall C.; West, William C.

2011-01-01

132

Interactions of bovine serum albumin with cationic imidazolium and quaternary ammonium gemini surfactants: effects of surfactant architecture.  

PubMed

The interactions of BSA with a series of cationic imidazolium gemini surfactants ([C(n)-s-C(n)im]Br(2), n=10, 12, 14, s=2, 4, 6), quaternary ammonium surfactants (C(12)C(2)C(12)), and their corresponding monomers ([C(12)mim]Br and DTAB) are investigated by fluorescence using pyrene as a molecular probe, synchronous fluorescence, circular dichroism (CD), and UV-visible absorption spectra. These surfactants are used to elucidate the effects of surfactant hydrophilic head group, spacer length, and hydrophobic chain length on the conformation of BSA. The results of fluorescence spectra and CD show that the imidazolium gemini surfactants with shorter spacers or with longer hydrophobic chains have a larger effect on BSA unfolding, and the imidazolium gemini surfactant interacts with BSA more strongly than its corresponding monomer and the quaternary ammonium gemini surfactant. These conclusions have been confirmed by the binding constants (K(a)) and binding sites (n) for the BSA/surfactant system. Stern-Volmer quenching constants K(SV) of cationic surfactants binding to BSA are obtained, indicating that the probable quenching mechanism is initiated by ground-state complex formation rather than by dynamic collision. Moreover, the synchronous fluorescence spectra show that the surfactants mainly interact with tryptophan residues of BSA. PMID:23044272

Zhou, Ting; Ao, Mingqi; Xu, Guiying; Liu, Teng; Zhang, Juan

2013-01-01

133

Synthesis, degradation, and cytotoxicity of multiblock poly(epsilon-caprolactone urethane)s containing gemini quaternary ammonium cationic groups.  

PubMed

Novel cationic biodegradable multiblock poly(epsilon-caprolactone urethane)s that contain gemini quaternary ammonium side groups on the hard segments were developed. To obtain these polyurethanes, a new L-lysine-derivatized diamine containing gemini quaternary ammonium side groups (GA8) was first synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectra (NMR), mass spectrometry (MS), and high-resolution mass spectra (HRMS). Then a series of gemini poly(epsilon-caprolactone urethane)s were designed and prepared using L-lysine ethyl ester diisocyanate (LDI), poly(epsilon-caprolactone) (PCL) diols, 1,4-butandiol (BDO), and GA8 and were terminated by methoxyl-poly(ethylene glycol) (m-PEG). The obtained polyurethanes were fully characterized by (1)H NMR, gel permeation chromatograph (GPC), differential scanning calorimetry (DSC), FTIR, and water contact angle (WCA) measurement. The gemini polyurethane shows a rapid rate of hydrolytic and enzymatic degradation, as demonstrated by weight loss and polarizing light microscopy (PLM) observations. In vitro cytotoxicity analysis suggests that both the polyurethanes and their degradation products do not show significant inhibition effect against fibroblasts. Our work provides a new way to synthesize nontoxic and amphiphilic multiblock polyurethanes with rapid degradation rate, and these new materials could be good candidates as biodegradable carriers for drug and gene delivery. PMID:19817491

Ding, Mingming; Li, Jiehua; Fu, Xiaoting; Zhou, Jian; Tan, Hong; Gu, Qun; Fu, Qiang

2009-10-12

134

A Systematic Investigation of Quaternary Ammonium Ions as Asymmetric Phase Transfer Catalysts. Synthesis of Catalyst Libraries and Evaluation of Catalyst Activity  

PubMed Central

Despite over three decades of research into asymmetric phase transfer catalysis (APTC), a fundamental understanding of the factors that affect the rate and stereoselectivity of this important process are still obscure. This paper describes the initial stages of a long-term program aimed at elucidating the physical organic foundations of APTC employing a chemoinformatic analysis of the alkylation of a protected glycine imine with a libraries of enantiomerically enriched quaternary ammonium ions. The synthesis of the quaternary ammonium ions follows a diversity oriented approach wherein the tandem inter[4+2]/intra[3+2] cycloaddition of nitroalkenes serves as the key transformation. A two part synthetic strategy comprised of: (1) preparation of enantioenriched scaffolds and (2) development of parallel synthesis procedures is described. The strategy allows for the facile introduction of four variable groups in the vicinity of a stereogenic quaternary ammonium ion. The quaternary ammonium ions exhibited a wide range of activity and to a lesser degree enantioselectivity. Catalyst activity and selectivity are rationalized in a qualitative way based on the effective positive potential of the ammonium ion. PMID:21446721

Denmark, Scott E.; Gould, Nathan D.; Wolf, Larry M.

2011-01-01

135

Poly-benzylic ammonium chloride resins as solid catalysts for fructose dehydration.  

PubMed

5-hydroxymethylfurfural (HMF) is one of the most promising platform molecules, and can be converted into a variety of interesting chemicals. The production of HMF is essentially targeted at bulk chemicals downstream, such as chemicals for the fuels and plastics industries. One critical challenge in HMF production processes is the link to further value-adding reactions in a simple and efficient way (e.g., fewer isolation and purification steps). Herein, a novel poly-benzyl ammonium chloride (PBnNH3 Cl) resin is developed as a highly efficient and stable catalyst for dehydration of carbohydrates into HMF. In the isopropanol system, PBnNH3 Cl produces high purity HMF that is suitable as feedstock for oxidation to 2,5-furandicarboxylic acid (FDCA). The excellent catalytic properties together with its easy synthesis, low cost, and nontoxic nature make this poly-ammonium resin a promising catalyst for the development of new and efficient processes for biomass-based chemicals. PMID:24903397

Teong, Siew Ping; Yi, Guangshun; Cao, Xueqin; Zhang, Yugen

2014-08-01

136

Interactive effect of monocrotophos and ammonium chloride on the freshwater fish Oreochromis mossambicus with reference to lactate\\/pyruvate ratio  

Microsoft Academic Search

Sublethal effect of monocrotophos (pesticide) and ammonium chloride (fertilizer) was studied in the freshwater fish Oreochromis mossambicus, with reference to carbohydrate metabolism for a period of 96h. The glycogen content was analysed in liver and muscle, while the lactate and pyruvate were assessed in blood along with liver and muscle. The results revealed that the glycogen content was found to

K. Vijayavel; E. F. Rani; C. Anbuselvam; M. P. Balasubramanian

2006-01-01

137

Predictions of size-resolved aerosol concentrations of ammonium, chloride and nitrate at a bayside site using EQUISOLV II  

NASA Astrophysics Data System (ADS)

Measured ambient air concentrations of ammonium, chloride and nitrate were compared with concentrations produced by EQUISOLV II, an aerosol thermodynamic equilibrium model. The monitoring equipment was located ˜50 m from Old Tampa Bay at the eastern end of the Gandy Bridge in Tampa, FL. Size-segregated ion concentrations of ammonium, sodium, potassium, calcium, magnesium, fluoride, chloride, nitrite, nitrate, sulfate and phosphate were determined from 6- and 1-day integrated cascade impactor samples obtained in May and August 2001, respectively. EQUISOLV II was initialized with these ion concentrations by size bin, and by gas phase concentrations of the volatile species, acquired with a collocated annular denuder system. The model redistributed the ions between the size bins until gas and particle concentrations reached equilibrium. The model calculated predominantly fine particle ammonium and coarse particle chloride and nitrate. For the May sampling period, when the average relative humidity was below 65%, the model predicted the formation of seven solids KNO 3, K 2SO 4, (NH 4) 2SO 4, Na 2SO 4, NaCl, NaNO 3, and CaSO 4·2H 2O. The amounts of ammonium in the fine fraction and of nitrate and chloride in the coarse fraction were predicted within the combined measurement and modeling uncertainty in the majority of cases.

Campbell, Scott W.; Evans, Melissa C.; Poor, Noreen D.

138

Silica Gel and Cellulose Loaded with Bis-Quaternary Ammonium Salts as Sensitive Reagents for Iron, Bismuth and Anionic Surfactants Determination in Water  

Microsoft Academic Search

Sorption of some high molecular weight bis-quaternary ammonium salts (QAS) on silica gel and cellulose was investigated. It was shown that QAS were not washed practically from the sorbents surface at pH = 1 – 9. Sorption of bismuth tetraiodide and iron (III) thiocyanate complexes and anionic dye — picric acid (Picr) onto silica gel modified with QAS was studied.

Olga A. Zaporozhets; Oksana Yu. Nadzhafova; Valentina V. Verba; Nataliya M. Zinchenko; Vasiliy V. Sukhan

1999-01-01

139

Selective Production of Electrostatically-Bound Adducts of Alkyl Cations/Polyoxoanions by the Collision-Induced Fragmentations of Their Quaternary Ammonium Counterparts  

NASA Astrophysics Data System (ADS)

Solutions of the quaternary ammonium salts of a set of classic polyoxometalates (POMs) (Keggin [XM12O40]n-, Dawson [P2W18O62]6-, and Lindqvist [M6O19]2- (X = P, Si; M = W, Mo) were characterized by electrospray mass spectrometry. The gas-phase fragmentations of a series of quaternary ammonium-associated clusters were investigated by their collision-induced dissociations to elucidate their fragmentation mechanisms. It was found that the quaternary ammonium-associated clusters had distinctive dissociation characteristics. Moreover, the mono-quaternary ammonium-associated clusters, {NR4[POMs]}(n-1)-, shared a common fragmentation feature, that is, they decomposed exclusively into their respective alkyl cation-bound clusters irrespective of the different cation sizes and the different natures of the polyoxoanions. The optimized geometries and the binding energies of the mono cation-bound Lindqvist POM-based clusters were obtained by calculations. To the best of our knowledge, this is the first investigation of the gas-phase fragmentations of these noncovalent complexes between organic amines and inorganic POM anions by a combination of theory and mass spectrometry.

Cao, Jie; Xu, Chong; Fan, YanXuan; Fan, LinYuan; Zhang, XiuHui; Hu, ChangWen

2013-06-01

140

A divalent quaternary alkyl ammonium salt as the electrolyte for high-energy electric double-layer capacitors  

NASA Astrophysics Data System (ADS)

A divalent electrolyte salt based on 1,1,4,4-tetramethyl piperazine has been synthesized and applied in electric double-layer capacitors (EDLCs). Traits of the divalent salts have been accessed as well as monovalent quaternary alkyl ammonium salts by the means of galvanostatic charge-discharge tests and ionic conductivity measurements. Compared with monovalent salts, the divalent salts do enlarge the charge storage ability of EDLCs remarkably. However, highly concentrated charge density on the divalent cation has a strong interaction with the organic solvent of propylene carbonate. The adverse effect of this heavy solvation on the performance of EDLCs has been investigated. Moreover, the influence of pore size distribution on the storage ability of these cations at the porous carbon electrode has been addressed.

Zheng, Cheng; Yoshio, Masaki; Qi, Li; Wang, Hongyu

2012-12-01

141

Quaternary ammonium-functionalized silica sorbents for the solid-phase extraction of aromatic amines under normal phase conditions.  

PubMed

Quaternary ammonium-functionalized silica materials were synthesized and applied for solid-phase extraction (SPE) of aromatic amines, which are classified as priority pollutants by US Environmental Protection Agency. Hexamethylenetetramine used for silica surface modification for the first time was employed as SPE sorbent under normal phase conditions. Hexaminium-functionalized silica demonstrated excellent extraction efficiencies for o-toluidine, 4-ethylaniline and quinoline (recoveries 101-107%), while for N,N-dimethylaniline and N-isopropylaniline recoveries were from low to moderate (14-46%). In addition, the suitability of 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica as SPE sorbent was tested under normal phase conditions. The recoveries achieved for the five aromatic amines ranged from 89 to 99%. The stability of the sorbent was evaluated during and after 150 extractions. Coefficients of variation between 4.5 and 10.2% proved a high stability of the synthesized sorbent. Elution was carried out using acetonitrile in the case of hexaminium-functionalized silica and water for 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent. After the extraction the analytes were separated and detected by liquid chromatography ultraviolet detection (LC-UV). The retention mechanism of the materials was primarily based on polar hydrogen bonding and ?-? interactions. Comparison made with activated silica proved the quaternary ammonium-functionalized materials to offer different selectivity and better extraction efficiencies for aromatic amines. Finally, 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent was successfully tested for the extraction of wastewater and soil samples. PMID:23473515

Vidal, Lorena; Robin, Orlane; Parshintsev, Jevgeni; Mikkola, Jyri-Pekka; Riekkola, Marja-Liisa

2013-04-12

142

The electrochemical behaviour of ferrocene in deep eutectic solvents based on quaternary ammonium and phosphonium salts  

Microsoft Academic Search

The electrochemical behaviour of ferrocene (Fc) is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between selected ammonium and phosphonium salts with glycerol and ethylene glycol. Combinations of cyclic voltammetry and chronoamperometry are employed to characterise the DESs. The reductive and oxidative potential limits are reported versus the Fc\\/Fc+ couple. The diffusion coefficient, D,

L. Bahadori; N. S. Abdul Manan; M. H. Chakrabarti; M. A. Hashim; F. S. Mjalli; I. M. Alnashef; M. A. Hussain; C. T. J. Low

2013-01-01

143

Palladium extraction from nitrate solutions by tertiary amines and quaternary ammonium salts  

Microsoft Academic Search

The mechanism of palladium extraction by trilaurylamine and trilaurylmethylammonium nitrate from nitric acid solutions was studied. The composition of the extracted compounds was determined by the Job method as well as by organic phase saturation. Both reagents were found to extract palladium as Am2Pd\\/NO3\\/4 \\/Am=ammonium cation\\/.

P. Tarap?ík; V. Mikulaj

1986-01-01

144

Ammonium chloride inhibits autophagy of hepatocellular carcinoma cells through SMAD2 signaling.  

PubMed

Autophagy is a cellular degradation process for the clearance of damaged or superfluous proteins and organelles, the recycling of which serves as an alternative energy source during periods of metabolic stress to maintain cell homeostasis and viability. The anti-necrotic function of autophagy is critical for tumorigenesis of many tumor cells, including hepatocellular carcinoma (HCC). However, the underlying mechanism is not clarified yet. Ammonium chloride (NH4Cl) is a well-known autophagy inhibitor, whereas its interaction with SMAD2 signaling pathway has not been reported previously. Here, we show that NH4Cl significantly inhibited rapamycin-induced autophagy in HCC cells through decreasing the levels of Beclin-1, autophagy-related protein 7 (ATG7), p62, and autophagosome marker LC3 and significantly decreased the level of phosphorylated SMAD2 in rapamycin-treated HCC cells. In order to find out whether NH4Cl may inhibit the autophagy in rapamycin-treated HCC cells through inhibition of SMAD2 signaling, we used transforming growth factor ?1 (TGF?1) to induce phosphorylation of SMAD2 in HCC cells. We found that induction of SMAD2 in HCC cells completely abolished the inhibitory effect of NH4Cl on rapamycin-induced autophagy in HCC cells, suggesting that NH4Cl inhibits autophagy of HCC cells through inhibiting SMAD2 signaling. PMID:25342595

Sun, Ranran; Luo, Yonggang; Li, Juan; Wang, Qiongye; Li, Jingjing; Chen, Xiaolong; Guan, Kelei; Yu, Zujiang

2014-10-24

145

Adsorption kinetics of 3-alkoxy-2-hydroxypropyl trimethyl ammonium chloride at oil-water interface  

NASA Astrophysics Data System (ADS)

Dynamic interfacial tension (DIT) between aqueous solution of 3-alkoxy-2-hydroxypropyl trimethyl ammonium chloride (RnHTAC) and n-octane was measured using spinning drop method. The effects of RnHTAC concentration (the concentration below the CMC) and temperature on DIT have been investigated. The cause of the change of DIT with time has been discussed. The effective diffusion coefficient, Da, and the adsorption barrier, ?a, have been obtained with extended Word-Tordai equation. The results show that the higher the concentration of the surfactant is, the smaller the DIT will be and the lower the curve of the DIT, and the aqueous RnHTAC solutions follow a mixed diffusion-activation adsorption mechanism. With increase of RnHTAC concentration in the bulk solution, Da decreases and ?a increases. Da of aqueous R14HTAC solution decreases from 0.090 × 10-13 m2 s-1 to 0.081 × 10-13 m2 s-1 and ?a increases from 10.12 kJ mol-1 to 11.89 kJ mol-1, with the temperature increasing from 30 °C to 50 °C. This phenomenon indicates that the diffusion tendency becomes weak with the strengthening of the interaction between the surfactant molecules and that the thermo-motion of molecules benefits interface adsorption.

Wei, Xi-lian; Wang, Xiu-hong; Liu, Jie; Sun, De-zhi; Yin, Bao-lin; Wang, Xiu-jie

2012-11-01

146

Effects of freezing, drying, ultraviolet irradiation, chlorine, and quaternary ammonium treatments on the infectivity of myxospores of Myxobolus cerebralis for Tubifex tubifex.  

PubMed

The effects of freezing, drying, ultraviolet irradiation (UV), chlorine, and a quaternary ammonium compound on the infectivity of the myxospore stage of Myxobolus cerebralis (the causative agent of whirling disease) for Tubifex tubifex were examined in a series of laboratory trials. Freezing at either -20 degrees C or -80 degrees C for a period of 7 d or 2 months eliminated infectivity as assessed by the absence of production of the actinospore stage (triactinomyxons [TAMs]) from T. tubifex cultures inoculated with treated myxospores over a 4-5-month period. Myxospores retained infectivity when held in well water at 5 degrees C or 22 degrees C for 7 d and when held at 4 degrees C or 10 degrees C d for 2 months. In contrast, no TAMs were produced from T. tubifex cultures inoculated with myxospores held at 20 degrees C for 2 months. Drying of myxospores eliminated any evidence of infectivity for T. tubifex. Doses of UV from 40 to 480 mJ/cm2 were all effective for inactivating myxospores of M. cerebralis, although a few TAMs were detected in one replicate T. tubifex culture at 240 mJ/cm2 and in one replicate culture at 480 mJ/cm2. Treatments of myxospores with chlorine bleach at active concentrations of at least 500 mg/L for 15 min largely inactivated myxospore infectivity for T. tubifex. Likewise, there was no evidence of TAMs produced by T. tubifex inoculated with myxospores treated with alkyl dimethyl benzyl ammonium chloride (ADBAC) at 1,500 mg/L for 10 min. Treatments of myxospores with 1,000-mg/L ADBAC for 10 min reduced TAM production in T. tubifex cultures sevenfold relative to that in cultures inoculated with an equal number of untreated myxospores. These results indicate that myxospores of M. cerebralis demonstrate a selective rather than broad resistance to selected physical and chemical treatments, and this selective resistance is consistent with conditions that myxospores are likely to experience in nature. PMID:18783133

Hedrick, Ronald P; McDowell, Terry S; Mukkatira, Kaveramma; MacConnell, Elizabeth; Petri, Brian

2008-06-01

147

Relationship between the resistance genes to quaternary ammonium compounds and antibiotic resistance in staphylococci isolated from surgical site infections  

PubMed Central

Background We aimed to investigate the prevalence of disinfectant resistance genes (qacA/qacB,qacC) and the aminoglycosides resistance genes [(aac(6?)aph(2?),aph(3?)-IIIa,ant(4?)-Ia)] in both S. aureus and coagulase-negative staphylococcal strains (CoNS) isolated from surgical site infections. Material/Methods Totally, 130 staphylococcal strains isolated from surgical site infections between January 2012 and February 2013 were included in the study. The PCR technique was employed to verify any presence of methicillin resistance gene (mecA), aminoglycoside resistance genes [(aac(6?)/aph (2?), aph(3)-III a ant (4?)-1a)], and disinfectant resistance genes (qacA/qacB,qacC) in staphylococci. Results MecA gene was determined in 58 (44.6%) of 130 staphylococcal isolates. A total of 28 (73.7%) of 38 S. aureus isolates were found to be positive for the mecA gene, and 4 (12.9%) of 31 isolates sensitive to amikacin were sensitive to methicillin. Eighteen (47.4%) of 38 amikacin-resistant S. aureus isolates were found to be positive for qacA/qacB genes and 11 (8.9%) of them were positive for qacC gene. Both mecA and qacA/qacB genes were found to be positive at the same time in 19 amikacin-resistant S. aureus strains. Seven (18.4%) S. aureus isolates were determined to be positive for qacA/qacB and qacC genes. Frequency of qacA/B genes was found to be 47.4% among amikacin-resistant S. aureus strains, while qacC gene was found to be 28.9% (p<0.05). The ratio of qacA/B and qacC genes in CoNS was found to be 37.9% and 20.7%, respectively (p<0.05). Conclusions Quaternary ammonium resistance genes were found to be positive at a remarkable ratio in the staphylococcal isolates from surgical wounds. Especially, the high rates of aminoglycosides and methicillin-resistance gene was remarkable in S. aureus isolates. Quaternary ammonium resistance genes were found to be positive. PMID:24691183

Temiz, Muhyittin; Duran, Nizami; Duran, Gülay Gülbol; Ery?lmaz, Naciye; Jenedi, Kemal

2014-01-01

148

Binding of acetylcholine and other quaternary ammonium cations by sulfonated calixarenes. Crystal structure of a [choline-tetrasulfonated calix[4]arene] complex  

Microsoft Academic Search

The water-soluble tetra- and hexasulfonated calix[4] and calix[6]arenes bind very strongly the neurotransmitter acetylcholine and other quaternary ammonium cations with association constants Ks up to 4×10 M for NEt4 . The high affinities for choline and acetylcholine (Ks=5×10 to 8×10 M) are comparable to those of the biological recognition sites. The crystal structure of the [choline-tetrasulfonated calix[4]arene] complex was determined.

Jean-Marie Lehn; Robert Meric; Jean-Pierre Vigneron; Michele Cesario; Jean Guilhem; Claudine Pascard; Zouhair Asfari; Jacques Vicens

1995-01-01

149

Insights into the transport of aqueous quaternary ammonium cations: a combined experimental and computational study.  

PubMed

This study focuses on understanding the relative effects of ammonium substituent groups (we primarily consider tetramethylammonium, benzyltrimethylammonium, and tetraethylammonium cations) and anion species (OH(-), HCO3(-), CO3(2-), Cl(-), and F(-)) on ion transport by combining experimental and computational approaches. We characterize transport experimentally using ionic conductivity and self-diffusion coefficients measured from NMR. These experimental results are interpreted using simulation methods to describe the transport of these cations and anions considering the effects of the counterion. It is particularly noteworthy that we directly probe cation and anion diffusion with pulsed gradient stimulated echo NMR and molecular dynamics simulations, corroborating these methods and providing a direct link between atomic-resolution simulations and macroscale experiments. By pairing diffusion measurements and simulations with residence times, we were able to understand the interplay between short-time and long-time dynamics with ionic conductivity. With experiment, we determined that solutions of benzyltrimethylammonium hydroxide have the highest ionic conductivity (0.26 S/cm at 65 °C), which appears to be due to differences for the ions in long-time diffusion and short-time water caging. We also examined the effect of CO2 on ionic conductivity in ammonium hydroxide solutions. CO2 readily reacts with OH(-) to form HCO(-)3 and is found to lower the solution ionic conductivity by almost 50%. PMID:24437699

Sarode, Himanshu N; Lindberg, Gerrick E; Yang, Yuan; Felberg, Lisa E; Voth, Gregory A; Herring, Andrew M

2014-02-01

150

Extraction of benzene and naphthalene carboxylic acids using quaternary ammonium salts as a model study for the separation of coal oxidation products  

SciTech Connect

The ion-pair solvent extraction of benzene- and naphthalene-carboxylic acids has been investigated as a model study for the separation of coal oxidation products, which are formed by treatment with alkaline solutions at high temperatures. It was possible that benzene- and naphthalene-dicarboxylic acids are extracted into several types of organic solvents with quaternary ammonium ions. The extraction equilibrium constants (K{sub ex}) for benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1-naphthoic acid, 2-naphthoic acid, 2,3-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid into chloroform were determined at 20{sup o}C. The difference of K{sub ex} among the aromatic acids was sufficiently large for designing a separation method for these aromatic acids. It was unexpected that the extraction of dicarboxylic acids was slower than that of monocarboxylic acids, although the ion-pair formation of aromatic carboxylate ion with quaternary ammonium ion is normally considered as a diffusion control reaction in aqueous phase. Thus, this fact suggests that the phase transfer of the ion-pair from aqueous to organic phase is the rate-determining step. Liner-free-energy relationship was observed for the monocarboxylic acids using different quaternary ammonium salts while that was ambiguous for the dicarboxylic acids. This is due to the steric influence of the counter ions for the magnitude of K{sub ex}.

Kawamura, K.; Nagano, H.; Okuwaki, A. [Tohoku University, Miyagi (Japan). Graduate School of Environmental Studies

2005-07-01

151

The synergistic effect of organic silicone quaternary ammonium salt and 5-fluorouracil on hepatocellular carcinoma in vitro and in vivo.  

PubMed

Hepatocellular carcinoma (HCC) is the third most common type of cancer worldwide, causing over 370,000 deaths per year, with approximately half of them in China. Chemotherapy is the optimal treatment for patients with advanced HCC, although chemoresistance has become a significant obstacle to successful liver cancer surgery. In this paper, we have assessed the characteristics of drugs to explore the effects of individual and combined action of organic silicone quaternary ammonium salt (Jieyoushen) and 5-fluorouracil (5-FU). The results of MTT assays showed that single and combined action of Jieyoushen and 5-FU can inhibit the proliferation of liver carcinoma cell lines in a dose-dependent and time-dependent manner, respectively. Electron microscopy and Hoechst 33342 staining showed characteristic apoptotic bodies in apoptotic cells treated with Jieyoushen and 5-FU. Flow cytometry results indicated that the percentage of cells at G0/G1 phase gradually increased, whereas it gradually decreased during the S phase after treatment. Taken together, these results suggest that the combination of Jieyoushen with 5-FU exerts a synergistic anticancer effect on HCC growth and that targeted therapeutic strategies may improve HCC sensitivity to chemotherapy. PMID:25072280

Wang, Juan-Xia; Zhang, Ling-Yi; Zhang, Jun; Ding, Hui; Wang, Dong-Min; Wang, Zhi-Ping

2014-09-01

152

Quaternary ammonium salt containing soybean oil: An efficient nanosize gene delivery carrier for halophile green microalgal transformation.  

PubMed

Dunaliella salina, a halophile green microalga, is considered a robust photobioreactor and a remarkable cost beneficial system for the production of therapeutic recombinant proteins. In this study, with low overall cost, a proper cationic lipid was synthesized from renewable soybean oil as an efficient gene delivery carrier for D. salina cells to create appropriate protein-producing transformed cell lines. To obtain an effective carrier, quaternary ammonium salt containing soybean oil (QASSO) was synthesized through the ring opening reaction of the epoxy groups of epoxidized soybean oil with diethylamine. QASSO was characterized using nuclear magnetic resonance and Fourier-transform infrared instruments. QASSO was used to prepare nanolipoplex construct using plasmid DNA molecules containing green fluorescent protein (GFP) as reporter gene. These nanolipoplexes (QASSO-pGFP, N/P=3) and QASSO had diameter of 63.62 and 110.63nm, and zeta potential of -68.89 and 48.25mV at pH 7.0, respectively. Results indicated the GFP gene expression and cytoplasmic accumulation of GFP protein in the transformants after incubation under desirable conditions for 48h and 1week. The transformation efficiency was quantitatively assayed by flow cytometry, which yielded transformations of 58.87% and 48.34% for QASSO and 38.32% and a negligible percentage for Polyfect® after 48h and 1week incubation, respectively. PMID:25451567

Akbari, Fariba; Yari Khosroushahi, Ahmad; Yeganeh, Hamid

2015-01-01

153

Integrating Conjugative Elements as Vectors of Antibiotic, Mercury, and Quaternary Ammonium Compound Resistance in Marine Aquaculture Environments  

PubMed Central

The presence of SXT/R391-related integrating conjugative elements (ICEs) in bacterial strains isolated from fish obtained from marine aquaculture environments in 2001 to 2010 in the northwestern Iberian Peninsula was studied. ICEs were detected in 12 strains taxonomically related to Vibrio scophthalmi (3 strains), Vibrio splendidus (5 strains), Vibrio alginolyticus (1 strain), Shewanella haliotis (1 strain), and Enterovibrio nigricans (2 strains), broadening the known host range able to harbor SXT/R391-like ICEs. Variable DNA regions, which confer element-specific properties to ICEs of this family, were characterized. One of the ICEs encoded antibiotic resistance functions in variable region III, consisting of a tetracycline resistance locus. Interestingly, hot spot 4 included genes providing resistance to rifampin (ICEVspPor2 and ICEValPor1) and quaternary ammonium compounds (QACs) (ICEEniSpa1), and variable region IV included a mercury resistance operon (ICEVspSpa1 and ICEEniSpa1). The S exclusion group was more represented than the R exclusion group, accounting for two-thirds of the total ICEs. Mating experiments allowed ICE mobilization to Escherichia coli strains, showing the corresponding transconjugants' rifampin, mercury, and QAC resistance. These results show the first evidence of ICEs providing rifampin and QAC resistances, suggesting that these mobile genetic elements contribute to the dissemination of antimicrobial, heavy metal, and QAC resistance determinants in aquaculture environments. PMID:22314526

Rodríguez-Blanco, Arturo; Lemos, Manuel L.

2012-01-01

154

Preparative separation of quaternary ammonium alkaloids from Coptis chinensis Franch by pH-zone-refining counter-current chromatography  

PubMed Central

pH-Zone-refining counter-current chromatography was successfully applied to the preparative separation of five quaternary ammonium alkaloids from the crude extract of Coptis chinensis Franch. The separation was performed with a two-phase solvent system composed of chloroform–methanol–water (4:3:3, v/v), where the upper aqueous stationary phase was added with 60 mM of hydrochloric acid and the lower organic mobile phase with 5 mM of triethylamine. From 1.0 g of crude extract, 5.4 mg of columbamine at 96.6% purity, 6.1 mg of jateorhizine at 98.8% purity, 58.3 mg of coptisine at 99.5% purity, 25.6 mg of palmatine at98.4% purity and 503.9 mg of berberine at 99.5% purity were obtained. The purities of the isolated alkaloids were analyzed by HPLC and the chemical structures were identified by electrospray ionization-mass spectrometry and 1H-NMR. PMID:21268250

Sun, Changlei; Li, Jia; Wang, Xiao; Duan, Wenjuan; Zhang, Tianyou; Ito, Yoichiro

2014-01-01

155

Nitric oxide-releasing quaternary ammonium-modified poly(amidoamine) dendrimers as dual action antibacterial agents.  

PubMed

Herein we describe the synthesis of nitric oxide (NO)-releasing quaternary ammonium (QA)-functionalized generation 1 (G1) and generation 4 (G4) poly(amidoamine) (PAMAM) dendrimers. Dendrimers were modified with QA moieties of different alkyl chain lengths (i.e., methyl, butyl, octyl, dodecyl) via a ring-opening reaction. The resultant secondary amines were then modified with N-diazeniumdiolate NO donors to yield NO-releasing QA-modified PAMAM dendrimers capable of spontaneous NO release (payloads of ~0.75 ?mol/mg over 4 h). The bactericidal efficacy of individual (i.e., non-NO-releasing) and dual action (i.e., NO-releasing) QA-modified PAMAM dendrimers was evaluated against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa bacteria. Bactericidal activity was found to be dependent on dendrimer generation, QA alkyl chain length, and bacterial Gram class for both systems. Shorter alkyl chains (i.e., methylQA, butylQA) demonstrated increased bactericidal activity against P. aeruginosa versus S. aureus for both generations, with NO release markedly enhancing overall killing. PMID:24797526

Worley, Brittany V; Slomberg, Danielle L; Schoenfisch, Mark H

2014-05-21

156

Structures of KcsA in complex with symmetrical quaternary ammonium compounds reveal a hydrophobic binding site.  

PubMed

Potassium channels allow for the passive movement of potassium ions across the cell membrane and are instrumental in controlling the membrane potential in all cell types. Quaternary ammonium (QA) compounds block potassium channels and have long been used to study the functional and structural properties of these channels. Here we describe the interaction between three symmetrical hydrophobic QAs and the prokaryotic potassium channel KcsA. The structures demonstrate the presence of a hydrophobic pocket between the inner helices of KcsA and provide insight into the binding site and blocking mechanism of hydrophobic QAs. The structures also reveal a structurally hidden pathway between the central cavity and the outside membrane environment reminiscent of the lateral fenestration observed in sodium channels that can be accessed through small conformational changes in the pore wall. We propose that the hydrophobic binding pocket stabilizes the alkyl chains of long-chain QA molecules and may play a key role in hydrophobic drug binding in general. PMID:25093676

Lenaeus, Michael J; Burdette, Dylan; Wagner, Tobias; Focia, Pamela J; Gross, Adrian

2014-08-19

157

bis-Azaaromatic quaternary ammonium analogues: ligands for alpha4beta2* and alpha7* subtypes of neuronal nicotinic receptors.  

PubMed

A series of bis-nicotinium, bis-pyridinium, bis-picolinium, bis-quinolinium and bis-isoquinolinium compounds was evaluated for their binding affinity at nicotinic acetylcholine receptors (nAChRs) using rat brain membranes. N,N'-Decane-1,12-diyl-bis-nicotinium diiodide (bNDI) exhibited the highest affinity for [(3)H]nicotine binding sites (K(i)=330 nM), but did not inhibit [(3)H]methyllycaconitine binding (K(i) >100 microM), indicative of an interaction with alpha4beta2*, but not alpha7* receptor subtypes, respectively. Also, bNDI inhibited (IC(50)=3.76 microM) nicotine-evoked (86)Rb(+) efflux from rat thalamic synaptosomes, indicating antagonist activity at alpha4beta2* nAChRs. N,N'-Dodecane-1,12-diyl-bis-quinolinium dibromide (bQDDB) exhibited highest affinity for [(3)H]methyllycaconitine binding sites (K(i)=1.61 microM), but did not inhibit [(3)H]nicotine binding (K(i)>100 microM), demonstrating an interaction with alpha7*, but not alpha4beta2* nAChRs. Thus, variation of N-n-alkyl chain length together with structural modification of the azaaromatic quaternary ammonium moiety afforded selective antagonists for the alpha4beta2* nAChR subtype, as well as ligands with selectivity at alpha7* nAChRs. PMID:12372503

Ayers, Joshua T; Dwoskin, Linda P; Deaciuc, A Gabriela; Grinevich, Vladimir P; Zhu, Jun; Crooks, Peter A

2002-11-01

158

The electrochemical behaviour of ferrocene in deep eutectic solvents based on quaternary ammonium and phosphonium salts.  

PubMed

The electrochemical behaviour of ferrocene (Fc) is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between selected ammonium and phosphonium salts with glycerol and ethylene glycol. Combinations of cyclic voltammetry and chronoamperometry are employed to characterise the DESs. The reductive and oxidative potential limits are reported versus the Fc/Fc(+) couple. The diffusion coefficient, D, of ferrocene in all studied DESs is found to lie between 8.49 × 10(-10) and 4.22 × 10(-8) cm(2) s(-1) (these do not change significantly with concentration). The standard rate constant for heterogeneous electron transfer across the electrode/DES interface is determined to be between 1.68 × 10(-4) and 5.44 × 10(-4) cm s(-1) using cyclic voltammetry. These results are of the same order of magnitude as those reported for other ionic liquids in the literature. PMID:23247115

Bahadori, Laleh; Manan, Ninie Suhana Abdul; Chakrabarti, Mohammed Harun; Hashim, Mohd Ali; Mjalli, Farouq Sabri; AlNashef, Inas Muen; Hussain, Mohd Azlan; Low, Chee Tong John

2013-02-01

159

A novel group of quaternary ammonium salts as ionic liquids and deep eutectic solvents  

NASA Astrophysics Data System (ADS)

A growing number of non-toxic and biodegradable deep eutectic solvents (DES) have been discovered in recent years. This group encompasses the solidified crystalline material 3-(2-aminopyrimidin-1-yl)propanoate (3-2AP), a primary ammonium cation that is a construct of a typical DES. Synthesis of 3-(2-aminopyrimidin-1-yl)propanoate by quarternerization of the amine in the aromatic ring creates a novel deep eutectic solvent. An additional alteration to the DES construct is observed with the formation of a zwitterion between the positively charged quartenary amine group and the negatively charged carboxylate counter ion. The molecular arrangement, or construct, of a deep eutectic solvent will determine both its structure and application in industry. This report describes the synthesis and characterization of an 80:20 urea/3-2AP eutectic mixture with a melting point of 50°C, nearly 120°C lower than the melting temperature of 3-2AP (172.5°C). A cytotoxicity profile for 3-2AP exposed to A549 bronchoaveolar carcinoma cells revealed an LD50 of 337.65 mug/ml.

Sparrow, Christopher R.

2011-12-01

160

New lipophilic polyelectrolyte gels containing quaternary ammonium salt with superabsorbent capacity for organic solvents.  

PubMed

Water and soil pollution by organic pollutants from petrochemical plants has become one of the major environmental problems in recent years. Lipophilic polyelectrolyte gels with ionic groups dissociable in nonpolar organic solvents show an enhanced swelling ability in a corresponding media attributed to the electrostatic repulsion and osmotic pressure provided by dissociated ionic groups. Here, we synthesized new lipophilic polyelectrolyte gels based on an easily available electrolyte monomer, methacryloxyethyl dimethyloctane ammonium trifluoromethanesulfonimide (MODAT), and a lipophilic neutral monomer, dodecyl acrylate by radiation-induced polymerization and cross-linking. The resultant lipophilic polyelectrolyte gels could absorb plenty of organic solvents with dielectric constants lower than 20 and exhibited a high absorbing ability at a wide range of temperatures (0-40 °C). The maximum swelling degree could reach as high as 200 g/g in some media, such as 1,2-dichloroethane (199.4 g/g) and dichloromethane (204 g/g), which was much higher than that of the nonionic gel without the addition of MODAT. Moreover, the resultant lipophilic polyelectrolyte gels could release most of the absorbed solvents within several hours and then be reused. It is expected that this new type of lipophilic polyelectrolyte gels may be a suitable candidate as organic pollutant absorbents. PMID:25134413

Chen, Jian; Wang, Shuojue; Peng, Jing; Li, Jiuqiang; Zhai, Maolin

2014-09-10

161

Retention behavior of long chain quaternary ammonium homologues and related nitroso-alkymethylamines  

USGS Publications Warehouse

Several chromatographic methods have been utilized to study the retentionbehavior of a homologous series of n-alkylbenzyldimethylammonium chlorides (ABDAC) and the corresponding nitroso-n-alkylmethylamines (NAMA). Linear correlation of the logarithmic capacity factor (k') with the number of carbons in the alkyl chain provides useful information on both gas chromatographic (GC) and high-performance liquid chromatographich (HPLC) retention parameters of unknown components. Under all conditions empolyed, GC methodology has proved effective in achieving complete resolution of the homologous mixture of NMA despite its obvious inadequacy in the separation of E-Z configurational isomers. Conversely, normal-phase HPLC on silica demonstrates that the selectivity (a) value for an E-Z pair is much higher than that for an adjacent homologous pair. In the reversed-phase HPLC study, three different silica-based column systems were examined under various mobile phase conditions. The extent of variation in k' was found to be a function of the organic modifier, counter-ion concentration, eluent pH, nature of counter-ion, and the polarity and type of stationary phase. The k'—[NaClO4] profiles showed similar trends between the ABDAC and the NAMA series, supporting the dipolar electronic structures of the latter compounds. Mobile phase and stationary phase effects on component separation are described. The methodology presented establishes the utility of HPLC separation techniques as versatile analytical tools for practical application.

Abidi, S.L.

1985-01-01

162

[Influence of quaternary ammonium salt on liberation of drug with antiseptic effect].  

PubMed

The paper evaluates the influence of three surfactants (carbetopendecinium halogenides) on the liberation of the drug chlorhexidine dihydrochloride (CHX) in 0.1% (w/w) from the dosage form-gel and also the flow properties of gels. The following tensides were evaluated: carbetopendecinium bromide (SB), carbetopendecinium chloride (SC), and carbetopendecinium iodide (SI). The tenside concentration was set under the critical micelle concentration. The biopolymer - chitosan (CHIT) in 2.5% (w/w) concentration was used as a gel creating substance. Based on the flow properties of the studied gels, it was found that the employed tensides exhibited no influence on the character of the system. The gels exhibited the character of plastic systems with time-independent flow. The drug liberation was evaluated at the temperatures of 20, 30 and 40 °C. Between the types of the tensides, the statistically significant differences (P < 0.05) were found as to the amount of the liberated CHX, which was reflected by the increased amount of the liberated drug. Based on the obtained results, it can be concluded that the most suitable was the SI tenside. From the gel with this tenside the greatest amount of CHX was liberated, which had the highest value of the liberation rate constant. PMID:24393113

Vitková, Zuzana; Herdová, Petra; Oremusová, Jarmila; Cižmárik, Jozef; Tóthová, Katarína

2013-12-01

163

Novel cationic polyaspartamide with covalently linked carboxypropyl-trimethyl ammonium chloride as a candidate vector for gene delivery  

Microsoft Academic Search

The non-viral gene vector properties of a protein-like polymer, the ?,?-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) were investigated after its derivatization with 3-(carboxypropyl)trimethyl-ammonium chloride (CPTA) as molecule bearing cationic groups, in order to obtain stable polycations able to condense DNA. PHEA was firstly functionalized with hydrazide pendant groups by reaction with hydrazine monohydrate (HYD), obtaining the polyhydrazide ?,?-poly(N-2-hydroxyethyl\\/carbazate)-d,l-aspartamide (PHEA–HYD). In this paper we reported

Mariano Licciardi; Monica Campisi; Gennara Cavallaro; Bianca Carlisi; Gaetano Giammona

2006-01-01

164

Highly fluorescent C-dots obtained by pyrolysis of quaternary ammonium ions trapped in all-silica ITQ-29 zeolite.  

PubMed

C-dots obtained in the homogeneous phase may exhibit a broad particle size distribution. The formation of C-dots within nanometric reaction cavities could be a methodology to gain control on their size distribution. Among the various possibilities, in the present work, the cavities of small pore size zeolites have been used to confine C-dots generated by the pyrolysis of the organic structure directing agent present in the synthesis of these crystalline aluminosilicates. To explore this methodology, ITQ-29 zeolite having a Linde type A (LTA) structure was prepared as pure silica with 4-methyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3.2.1-ij]quinolinium as the organic structure directing agent. Pyrolysis under an inert atmosphere at 550 °C of a pure-silica ITQ-29 sample (cubic particles of 4 ?m edge) renders a highly fluorescent zeolite containing about 15 wt% of the carbonised residue. While another small pore zeolite, ITQ-12 (ITW), also renders photoluminescent C-dots under similar conditions, medium or large pore zeolites, such as silicalite (MFI) or pure silica Beta (BEA), failed to produce fluorescent powders under analogous thermal treatment and only decomposition and complete removal of the corresponding quaternary ammonium ion templates was observed for these zeolites. The dissolution of the pyrolysed ITQ-29 zeolite framework and the extraction of the carbon residue with ethyl acetate have allowed the characterisation of C-dots with particle sizes between 5 and 12 nm and a photoluminescence quantum yield of 0.4 upon excitation at 350 nm that is among the highest reported for non-surface functionalized C-dots. Photoluminescence varies with the excitation wavelength and is quenched by oxygen. Pyrolysed ITQ-29 powders can act as fluorescent oxygen sensors. PMID:25516465

Baldovi, Herme G; Valencia, Susana; Alvaro, Mercedes; Asiri, Abdullah M; Garcia, Hermenegildo

2015-01-22

165

Highly fluorescent C-dots obtained by pyrolysis of quaternary ammonium ions trapped in all-silica ITQ-29 zeolite  

NASA Astrophysics Data System (ADS)

C-dots obtained in the homogeneous phase may exhibit a broad particle size distribution. The formation of C-dots within nanometric reaction cavities could be a methodology to gain control on their size distribution. Among the various possibilities, in the present work, the cavities of small pore size zeolites have been used to confine C-dots generated by the pyrolysis of the organic structure directing agent present in the synthesis of these crystalline aluminosilicates. To explore this methodology, ITQ-29 zeolite having a Linde type A (LTA) structure was prepared as pure silica with 4-methyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3.2.1-ij]quinolinium as the organic structure directing agent. Pyrolysis under an inert atmosphere at 550 °C of a pure-silica ITQ-29 sample (cubic particles of 4 ?m edge) renders a highly fluorescent zeolite containing about 15 wt% of the carbonised residue. While another small pore zeolite, ITQ-12 (ITW), also renders photoluminescent C-dots under similar conditions, medium or large pore zeolites, such as silicalite (MFI) or pure silica Beta (BEA), failed to produce fluorescent powders under analogous thermal treatment and only decomposition and complete removal of the corresponding quaternary ammonium ion templates was observed for these zeolites. The dissolution of the pyrolysed ITQ-29 zeolite framework and the extraction of the carbon residue with ethyl acetate have allowed the characterisation of C-dots with particle sizes between 5 and 12 nm and a photoluminescence quantum yield of 0.4 upon excitation at 350 nm that is among the highest reported for non-surface functionalized C-dots. Photoluminescence varies with the excitation wavelength and is quenched by oxygen. Pyrolysed ITQ-29 powders can act as fluorescent oxygen sensors.

Baldovi, Herme G.; Valencia, Susana; Alvaro, Mercedes; Asiri, Abdullah M.; Garcia, Hermenegildo

2015-01-01

166

Synergistic antimicrobial activity based on the combined use of a gemini-quaternary ammonium compound and ultraviolet-A light.  

PubMed

This study examined the utility of synergistic disinfection employing a gemini-quaternary ammonium salt (a gemini-QUAT, namely 3,3'-(2,7-dioxaoctane)bis(1-decylpyridinium bromide)), as an organic biocide in combination with irradiation by an ultraviolet-A (UV-A) light-emitting diode (LED) with a peak wavelength of 365nm. The combined system represents a novel disinfection method utilizing facilitated in situ oxidation depending on overproduction of reactive oxygen species (ROS) triggered by the initial action of the gemini-QUAT on the bacterial membrane. We demonstrate that this combination decreased the viability of pathogenic bacteria in a significant and rapid manner, and depended on doses of the gemini-QUAT and the fluence: the viability of Escherichia coli was reduced by greater than 5.0-logs by the combination procedure, but the decrease in viability was only 2.3-logs for exposure to UV at the same fluence dose in the absence of the gemini-QUAT. Adding catalase as a radical scavenger decreased bacterial inactivation by the combined disinfection procedure. Flow cytometric analysis indicated superoxide and hydrogen peroxide overproduction within cells treated with the combined disinfection procedure. The excessive superoxide, detected only in the combined system, appeared to be generated by the action of the gemini-QUAT at the bacterial membrane, leading to excessive and rapid generation of ROS in the system. Our data strongly suggested that this ROS promoted bacterial membrane peroxidation during initial treatment by the combination method, resulting in increased oxidative modification of DNA. These oxidative reactions may play an important role in the efficacy of this disinfection procedure. PMID:24362318

Shirai, Akihiro; Aihara, Mutsumi; Takahashi, Akira; Maseda, Hideaki; Omasa, Takeshi

2014-01-01

167

Assessment of bactericidal effects of quaternary ammonium-based antibacterial monomers in combination with colloidal platinum nanoparticles.  

PubMed

Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives. PMID:22277619

Ma, Sai; Izutani, Naomi; Imazato, Satoshi; Chen, Ji-Hua; Kiba, Wakako; Yoshikawa, Ranna; Takeda, Kahoru; Kitagawa, Haruaki; Ebisu, Shigeyuki

2012-02-01

168

tetrakis-Azaaromatic quaternary ammonium salts: Novel subtype-selective antagonists at neuronal nicotinic receptors that mediate nicotine-evoked dopamine release  

PubMed Central

A series of tetrakis-azaaromatic quaternary ammonium salts was synthesized in order to identify compounds with higher affinity and selectivity as antagonists at neuronal nicotinic receptor subtypes that mediate nicotine-evoked DA release. A high hit rate was achieved in identifying potent analogues that inhibit these nAChRs. Three tetrakis analogues, 11j, 11f and 11g, were identified as potent (IC50 = 3, 28 and 56 nM, respectively) antagonists at these receptors. These compounds represent a novel structural class of nicotinic receptor antagonists. PMID:18851914

Zhang, Zhenfa; Zheng, Guangrong; Pivavarchyk, Marharyta; Deaciuc, A. Gabriela; Dwoskin, Linda P.; Crooks, Peter A.

2008-01-01

169

Effect of a novel quaternary ammonium methacrylate polymer (QAMP) on adhesion and antibacterial properties of dental adhesives.  

PubMed

This study investigated the resin-dentin bond strength (?TBS), degree of conversion (DC), and antibacterial potential of an innovative adhesive system containing a quaternary ammonium methacrylate polymer (QAMP) using in situ and in vitro assays. Forty-two human third molars were flattened until the dentin was exposed and were randomly distributed into three groups of self-etching adhesive systems: Clearfil™ SE Bond containing 5% QAMP (experimental group), Clearfil™ Protect Bond (positive control) and Clearfil™ SE Bond (negative control). After light curing, three 1 mm-increments of composite resin were bonded to each dentin surface. A total of thirty of these bonded teeth (10 teeth per group) was sectioned to obtain stick-shaped specimens and tested under tensile stress immediately, and after 6 and 12 months of storage in distilled water. Twelve bonded teeth (4 teeth per group) were longitudinally sectioned in a mesio-to-distal direction to obtain resin-bonded dentin slabs. In situ DC was evaluated by micro-Raman spectroscopy. In vitro DC of thin films of each adhesive system was measured using Fourier transform infrared spectroscopy. In vitro susceptibility tests of these three adhesive systems were performed by the minimum inhibitory/minimum bactericidal concentration (MIC/MBC) assays against Streptococcus mutans, Lactobacillus casei, and Actinomyces naeslundii. No statistically significant difference in ?TBS was observed between Clearfil™ SE Bond containing 5% QAMP and Clearfil™ SE Bond (p>0.05) immediately, and after 6 and 12 months of water storage. However Clearfil™ Protect Bond showed a significant reduction of ?TBS after 12 months of storage (p=0.039). In addition, QAMP provided no significant change in DC after incorporating into Clearfil™ SE Bond (p>0.05). Clearfil™ SE Bond containing 5% QAMP demonstrated MIC/MBC values similar to the positive control against L. casei and A. naeslundii and higher than the negative control for all evaluated bacterial strains. The use of QAMP in an adhesive system demonstrated effective bond strength, a suitable degree of conversion, and adequate antibacterial effects against oral bacteria, and may be useful as a new approach to provide long-lasting results for dental adhesives. PMID:24853131

Pupo, Yasmine M; Farago, Paulo Vitor; Nadal, Jessica M; Simão, Luzia C; Esmerino, Luís Antônio; Gomes, Osnara M M; Gomes, João Carlos

2014-01-01

170

Functionalized ionic liquids based on quaternary ammonium cations with two ether groups as new electrolytes for Li/LiFePO4 secondary battery  

NASA Astrophysics Data System (ADS)

New functionalized ILs based on quaternary ammonium cations with two ether groups and bis(trifluoromethanesulfonyl)imide (TFSA-) anion are synthesized and characterized. Physical and electrochemical properties, including melting point, thermal stability, viscosity, conductivity and electrochemical stability are investigated for these ILs. All these ILs are liquids at room temperature except N,N-diethyl-N,N-bis(2-ethoxyethyl)ammonium TFSA (N22(2o2)(2o2)-TFSA, Tm = 29.7 °C), and the viscosities of N-methyl-N-ethyl-N-(2-methoxyethyl)-N-(2-ethoxyethyl)ammonium TFSA (N12(2o1)(2o2)-TFSA) and N-methyl-N-ethyl-N,N-bis(2-ethoxyethyl)ammonium TFSA (N12(2o2)(2o2)-TFSA) are 68.0 cP and 63.0 cP at 25 °C, respectively. N-Methyl-N,N-diethyl-N-(2-methoxyethyl)ammonium TFSA (DEME-TFSA) and five ILs with lower viscosity are chosen to dissolve 0.6 mol kg-1 of LiTFSA as IL electrolytes without additive for lithium battery. Lithium plating and striping on Ni electrode can be observed in these IL electrolytes, and cycle performances of lithium symmetrical cells are also investigated for these IL electrolytes. Li/LiFePO4 cells using these IL electrolytes without additives have good cycle property at the current rate of 0.1 C, and the N-methyl-N-ethyl-N,N-bis(2-methoxyethyl)ammonium TFSA (N12(2o1)(2o1)-TFSA) and N12(2o2)(2o2)-TFSA electrolytes own better rate property than DEME-TFSA electrolyte.

Jin, Yide; Zhang, Jianhao; Song, Jianzhi; Zhang, Zhengxi; Fang, Shaohua; Yang, Li; Hirano, Shin-ichi

2014-05-01

171

Selective Detection of Carbohydrates and Their Peptide Conjugates by ESI-MS Using Synthetic Quaternary Ammonium Salt Derivatives of Phenylboronic Acids  

NASA Astrophysics Data System (ADS)

We present new tags based on the derivatives of phenylboronic acid and apply them for the selective detection of sugars and peptide-sugar conjugates in mass spectrometry. We investigated the binding of phenylboronic acid and its quaternary ammonium salt (QAS) derivatives to carbohydrates and peptide-derived Amadori products by HR-MS and MS/MS experiments. The formation of complexes between sugar or sugar-peptide conjugates and synthetic tags was confirmed on the basis of the unique isotopic distribution resulting from the presence of boron atom. Moreover, incorporation of a quaternary ammonium salt dramatically improved the efficiency of ionization in mass spectrometry. It was found that the formation of a complex with phenylboronic acid stabilizes the sugar moiety in glycated peptides, resulting in simplification of the fragmentation pattern of peptide-derived Amadori products. The obtained results suggest that derivatization of phenylboronic acid as QAS is a promising method for sensitive ESI-MS detection of carbohydrates and their conjugates formed by non-enzymatic glycation or glycosylation.

Kijewska, Monika; Kuc, Adam; Kluczyk, Alicja; Waliczek, Mateusz; Man-Kupisinska, Aleksandra; Lukasiewicz, Jolanta; Stefanowicz, Piotr; Szewczuk, Zbigniew

2014-06-01

172

Preparative separation of quaternary ammonium alkaloids from Corydalis yanhusuo W. T. Wang by pH-zone-refining counter-current chromatography.  

PubMed

The optimal extraction condition for extracting quaternary ammonium alkaloid dehydrocorydaline from Corydalis yanhusuo W. T. Wang was investigated using orthogonal experimental design. pH-zone-refining counter-current chromatography (CCC) with normal phase elution was successfully applied to preparative separation of alkaloids from the crude extract of Corydalis yanhusuo. The separation was performed with a biphasic solvent system composed of chloroform (CHCl(3))-methanol (MeOH)-water (2:1:1, v/v), in which the lower organic phase containing 10?mM of triethylamine was used as the mobile phase, while the upper aqueous phase containing 10?mM of hydrochloric acid was used as the stationary phase. The separation mechanism of quaternary ammonium alkaloids using pH-zone-refining CCC was discussed in comparison with standard high-speed CCC. In the present study, the separation of 1.200?g of crude sample yielded 129?mg of dehydrocorydaline and 12?mg of palmatine at a high purity of 94 and 92%, respectively. Recovery for dehydrocorydaline and palmatine was 85 and 86%, respectively. PMID:21268250

Yu, Qing; Tong, Shengqiang; Yan, Jizhong; Hong, Chaoqun; Zhai, Wenfeng; Li, Yaqin

2011-02-01

173

(tert-But­yl)(2-hy­droxy­eth­yl)ammonium chloride  

PubMed Central

In the cation of the title mol­ecular salt, C6H16NO+·Cl?, the N—C—C—O torsion angle is 176.5?(2)°. In the crystal, the cations and chloride ions are linked by N—H?O and O—H?O hydrogen bonds, generating a two-dimensional network parallel to (100). PMID:25161569

Valerio-Cárdenas, Cintya; Hernández-Ortega, Simón; Morales-Morales, David

2014-01-01

174

Catalytic dehydrochlorination of polyvinyl chloride in two-phase systems  

SciTech Connect

The catalytic activity of quaternary ammonium salts (QAS), whose cation and anion structures are different, and the mechanism of catalytic two-phase dehydrochlorination of polyvinyl chloride (PVC) are studied. Under phase-transfer conditions, dehydrochlorination of PVC is shown to proceed at the interface via an ionic mechanism in the presence of quaternary ammonium salts. The catalytic activity of QAS is governed by both the cation lipophilicity and the anion nature and increases as alcohols are introduced into the reaction mixture. The alcohol nature does not influence the extent of the reaction completion, but it does effect the supermolecular structure of the polyacetylene synthesized.

Leplyanin, G.V.; Salimgareeva, V.N.; Sannikova, N.S. [Institute of Organic Chemistry, Ufa (Russian Federation)

1994-11-01

175

The optical constants of several atmospheric aerosol species - Ammonium sulfate, aluminum oxide, and sodium chloride  

NASA Technical Reports Server (NTRS)

An investigation is conducted of problems which are related to a use of measured optical constants in the simulation of the optical constants of real atmospheric aerosols. The techniques of measuring optical constants are discussed, taking into account transmission measurements through homogeneous and inhomogeneous materials, the immersion of a material in a liquid of a known refractive index, the consideration of the minimum deviation angle of prism measurement, the interference of multiply reflected light, reflectivity measurements, and aspects of mathematical analysis. Graphs show the real and the imaginary part of the refractive index as a function of wavelength for aluminum oxide, NaCl, and ammonium sulfate. Tables are provided for the dispersion parameters and the optical constants.

Toon, O. B.; Pollack, J. B.; Khare, B. N.

1976-01-01

176

AGING EFFECTS ON THE PROPERTIES OF IMIDAZOLIUM, QUATERNARY AMMONIUM, PYRIDINIUM AND PYRROLIDINIUM-BASED IONIC LIQUIDS USED IN FUEL AND ENERGY PRODUCTION  

SciTech Connect

Ionic liquids are often cited for their excellent thermal stability, a key property for their use as solvents and in the chemical processing of biofuels. However, there has been little supporting data on the long term aging effect of temperature on these materials. Imizadolium, quaternary ammonium, pyridinium, and pyrrolidnium-based ionic liquids with the bis(trifluoromethylsulfonyl)imide and bis(perfluoroethylsulfonyl)imide anions were aged for 2520 hours (15 weeks) at 200?C in air to determine the effects of an oxidizing environment on their chemical structure and thermal stability over time. It was found that the minor changes in the cation chemistry could greatly affect the properties of the ILs over time.

Fox, E.

2013-08-13

177

Optimizing the concentration of quaternary ammonium dimethacrylate monomer in bis-GMA/TEGDMA dental resin system for antibacterial activity and mechanical properties.  

PubMed

Four novel quaternary ammonium dimethacrylate monomers named IMQ (side alkyl chain length from 12 to 18) were synthesized with the aim to synthesize dental resin with antibacterial activity. All of IMQs were added into bis-GMA/TEGDMA dental resin system with a series of mass ratio (5, 10, and 20 wt%), double bond conversion (DC), flexural strength (FS), modulus of elasticity (FM) and biofilm formation inhibitory effect were studied. According to the results of DC, FS, FM, and the biofilm inhibitory effect, IMQ-16 containing polymer had the best comprehensive properties, and the optimal concentration of IMQ-16 in bis-GMA/TEGDMA dental resin would be in the range of 5-10 wt%. PMID:24449028

Liang, Xiaoxu; Söderling, Eva; Liu, Fang; He, Jingwei; Lassila, Lippo V J; Vallittu, Pekka K

2014-05-01

178

Highly sensitive, colorimetric detection of mercury(II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature.  

PubMed

We provide a highly sensitive and selective assay to detect Hg(2+) in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by Hg(2+) that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of Hg(2+) in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 × 10(-8)-1 × 10(-2) M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for Hg(2+). PMID:21069969

Liu, Dingbin; Qu, Weisi; Chen, Wenwen; Zhang, Wei; Wang, Zhuo; Jiang, Xingyu

2010-12-01

179

CO2/ethylene oxide copolymerization and ligand variation for a highly active salen-cobalt(III) complex tethering 4 quaternary ammonium salts.  

PubMed

A cobalt(III) complex (1) of a salcy-type ligand tethering 4 quaternary ammonium salts, which is thought to act as a highly active catalyst for CO2/propylene oxide (PO) copolymerization, also shows high activity (TOF, 25,900 h(-1); TON, 518,000; 2.72 kg polymer per g cat) and selectivity (>98%) for CO2/ethylene oxide (EO) copolymerization that results in high-molecular-weight polymers (M(n), 200,000-300,000) that have strictly alternating repeating units. The related cobalt(III) complexes 11-14 were prepared through variations of the ligand framework of 1 by replacing the trans-1,2-diaminocyclohexane unit with 2,2-dimethyl-1,3-propanediamine, trans-1,2-diaminocyclopentane, or 1,1'-binaphthyl-2,2'-diamine or by replacing the aldimine bond with ketimine. These ligand frameworks are thought to favour the formation of the cis-? configuration in complexation, and the formation of the cis-? configuration in 11-14 was confirmed through NMR studies or X-ray crystallographic studies of model complexes not bearing the quaternary ammonium salts. Complexes 11, 13, and 14, which adopt the cis-? configuration even in DMSO did not show any activity for CO2/PO copolymerization. Complex 12, which was constructed with trans-1,2-diaminocyclopentane and fluctuated in DMSO between the coordination and de-coordination of the acetate ligand as observed for 1, showed fairly high activity (TOF, 12,400 h(-1)). This fluctuating behaviour may play a role in polymerization. However, complex 12 did not compete with 1 in terms of activity, selectivity, and the catalyst cost. PMID:23104466

Jeon, Jong Yeob; Lee, Jung Jae; Varghese, Jobi Kodiyan; Na, Sung Jae; Sujith, S; Go, Min Jeong; Lee, Junseong; Ok, Myung-Ahn; Lee, Bun Yeoul

2013-07-01

180

Synthesis, in vitro and in vivo evaluation of new norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives as polymer therapeutics.  

PubMed

New norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives (NCTD-HACCs) were synthesized and characterized by (1)H NMR, Fourier-transform infrared spectroscopy (FT-IR), and wide-angle X-ray diffraction (WAXD). Two NCTD-HACCs with different degrees of substitution (DS) (12.2% and 24.8%) were obtained, which had good water solubility. NCTD was released from the NCTD-HACCs via hydrolysis, faster in pH 5.0 than pH 7.4 and presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. Fluorescence microscope and flow cytometry analysis demonstrated that the NCTD-HACC was endocytosized into MGC80-3 cells and the uptaken amount increased as incubation time. Compared with free NCTD, the NCTD-HACCs showed lower in vitro anti-tumor activity against human gastric cancer MGC80-3 cells, but higher in vivo tumor growth inhibition in S180 tumor-bearing mice. The in vivo near-infrared (NIR) fluorescence real-time imaging result showed the fluorescence intensity in tumor was much higher than that in heart, liver, spleen and lung (except kidney) after i.v. injection of the FITC-labeled NCTD-HACC2, indicating specific accumulation of the NCTD-HACC in tumor. PMID:23742972

Xu, Xiaofen; Li, Yanggong; Wang, Feihu; Lv, Li; Liu, Jieying; Li, Mingna; Guo, Aijie; Jiang, Jinjun; Shen, Yuanyuan; Guo, Shengrong

2013-09-10

181

Protective role of pongamia pinnata leaf extract on tissue antioxidant status and lipid peroxidation in ammonium chloride-induced hyperammonemic rats.  

PubMed

The present investigation was designed to study the protective role of Pongamia pinnata (an indigenous plant used in Ayurvedic medicine in India) leaf extract on oxidative stress during ammonium chloride-induced hyperammonemia by measuring the extent of oxidative damage as well as antioxidant status. Ethanolic extract of Pongamia pinnata (PPEt) leaves was administered orally (300 mg/kg body weight) and the effects of PPEt on the levels of thiobarbituric acid reactive substances (TBARS), hydroperoxides (HP), conjugated diene (CD), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) were studied in liver and kidney of ammonium chloride-induced hyperammonemic rats. On treatment with PPEt, a significant reduction in the levels of TBARS, HP, and CD and a significant increase in the levels of SOD, CAT, GPx, and GSH in liver and kidney of ammonium chloride-induced hyperammonemic rats were observed, which clearly shows the antioxidant property of PPEt. The study of induction of the antioxidant status is considered to be a reliable marker for evaluating the antiperoxidative effect of the medicinal plant. Our present findings show the protective role of PPEt against lipid peroxidation and suggest that PPEt possesses antioxidant potential that may be used for therapeutic purposes. The exact mechanism has to be still investigated and the isolation of active constituents is required. PMID:20020989

Essa, M Mohamed; Subramanian, P

2006-01-01

182

Degradation of benzyldimethyl hexadecylammonium chloride by Bacillus niabensis and Thalassospira sp. isolated from marine sediments  

Microsoft Academic Search

Following enrichment in its presence, two strains of bacteria, isolated from marine sediments, were shown to degrade the quaternary ammonium surfactant benzyldimethyl hexadecylammonium chloride (BDHAC) in a minimal salts medium. The bacteria identified by 16S ribosomal deoxyribonucleic acid sequencing were shown to belong to several genera and determined to be Bacillus niabensis and Thalassospira sp. Initial investigations demonstrated that the

D. E. Bassey; S. J. W. Grigson

2011-01-01

183

The effect of ammonium chloride and urea application on soil bacterial communities closely related to the reductive transformation of pentachlorophenol.  

PubMed

Pentachlorophenol (PCP) is widely distributed in the soil, and nitrogen fertilizer is extensively used in agricultural production. However, studies on the fate of organic contaminants as affected by nitrogen fertilizer application have been rare and superficial. The present study aimed to examine the effect of ammonium chloride (NH4Cl) and urea (CO(NH2)2) application on the reductive transformation of PCP in a paddy soil. The study showed that the addition of low concentrations of NH4Cl/CO(NH2)2 enhanced the transformation of PCP, while the addition of high concentrations of NH4Cl/CO(NH2)2 had the opposite effect. The variations in the abundance of soil microbes in response to NH4Cl/CO(NH2)2 addition showed that both NH4Cl and CO(NH2)2 had inhibitory effects on the growth of dissimilatory iron-reducing bacteria (DIRB) of the genus Comamonas. In contrast, for the genus Shewanella, low concentrations of NH4Cl inhibited growth, and high concentrations of NH4Cl enhanced growth, whereas all concentrations of CO(NH2)2 showed enhancement effects. In addition, consistent patterns of variation were found between the abundances of dechlorinating bacteria in the genus Dehalobacter and PCP transformation rates under NH4Cl/CO(NH2)2 addition. In conclusion, nitrogen application produced variations in the structure of the soil microbial community, especially in the abundance of dissimilatory iron-reducing bacteria and dechlorinating bacteria, which, in turn, affected PCP dechlorination. PMID:24662270

Yu, Huan-Yun; Wang, Yong-kui; Chen, Peng-cheng; Li, Fang-bai; Chen, Man-jia; Hu, Min

2014-05-15

184

In Vitro Antibacterial Activity of a Novel Resin-Based Pulp Capping Material Containing the Quaternary Ammonium Salt MAE-DB and Portland Cement  

PubMed Central

Background Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. Methods The experimental material was prepared from a 2?1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4?3?1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. Results S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. Conclusion The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows promise as a pulp capping material for vital pulp preservation in the treatment of deep caries. PMID:25389975

Zhang, Hongchen; Zhou, Wei; Ban, Jinghao; Wei, Jingjing; Liu, Yan; Gao, Jing; Chen, Jihua

2014-01-01

185

Encapsulation of alkyl and aryl derivatives of quaternary ammonium cations within cucurbit[n]uril (n?=?6,7) and their inverted diastereomers: density functional investigations.  

PubMed

Electronic structure, vibrational frequencies, and ¹H chemical shifts of inclusion complexes between CB[n] (n?=?6,7) or their inverted iCB[n] diastereomer hosts and quaternary diammonium viz., 1,6-hexyldiammonium (HDA) or p-xylyldiammonium (XYL) cationic guests are obtained from the density functional calculations. The interaction of CB[n] or iCB[n] with HDA (guest) conduce inclusion complexes in which the guest attains gauche conformation within the host cavity. The lowest energy XYL complexes of CB[6] or iCB[6] are comprised of one ammonium group orienting parallel to aromatic ring. The CB[7] or iCB[7] complexes of XYL on the other hand, reveal ammonium group(s) perpendicular to aromatic ring of the guest. The ureido C=O and N--H stretching vibrations on complexation engender frequency down-shift in the calculated spectra. This can be attributed to C--H-- --O and N--H-- --O interactions in the complex. The inverting of glycouril unit in iCB[n] renders a frequency shift (12 cm?¹) for the C=O stretching in the opposite direction. Molecular electron density topography and natural bond orbital analyses have been used to explain the direction of frequency shifts. Calculated ¹H NMR reveal that guest protons within the host cavity not participating in hydrogen bonding interactions, exhibit shielded signals compared to isolated XYL or HDA. Likewise the inverted protons in the iCB[6]-XYL complex led to up-field signals in calculated ¹H NMR as a result of C-H-- -? interactions. PMID:24567156

Raja, Ishita A; Gobre, Vivekanand V; Pinjari, Rahul V; Gejji, Shridhar P

2014-03-01

186

Study of the activity of quaternary ammonium compounds in the mitigation of biofouling in heat exchangers-condensers cooled by seawater.  

PubMed

The effectiveness of two quaternary ammonium compounds (QACs) (non-oxidising biocides) to reduce the growth of biofilm adhering to the tubes of a heat exchanger-condenser cooled by seawater was evaluated. Their effectiveness was compared to that of a conventional oxidising biocide (sodium hypochlorite [NaOCl]) under the same testing conditions. Each biocide was applied intermittently (6?h on, 6?h off) in a first shock stage (1.5?ppm over 8?days) and a second stabilising stage (0.5?ppm over 20?days). The results showed that the antifouling effectiveness of the first of the QACs (fifth generation) was comparable to that shown by the oxidising power of NaOCl. Although the reaction time was longer than that of NaOCl, both the compounds removed the biofilm, and the tube was practically restored to its clean condition. Treatment with the second of the QACs (fourth generation) allowed for the stabilisation of biofilm growth, but not for its removal. Ecotoxicology studies classified the QACs as environmentally harmless under the testing conditions. PMID:24067104

Trueba, Alfredo; Otero, Félix M; González, José A; Vega, Luis M; García, Sergio

2013-01-01

187

Evaluation of aqueous and alcohol-based quaternary ammonium sanitizers for inactivating Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes on peanut and pistachio shells.  

PubMed

This study evaluated the efficacy of aqueous (aQUAT) and isopropyl alcohol-based quaternary ammonium (ipQUAT) sanitizers for reducing Salmonella spp., Escherichia coli O157:H7, or Listeria monocytogenes populations on peanut and pistachio shell pieces. Inoculated nutshells were mixed with QUAT sanitizers, water, or 70% ethanol and enumerated immediately or after incubation at 30 °C for 48 h. None of the treatments had any immediate effect on Salmonella or E. coli O157:H7 populations on the peanut or pistachio shells. L. monocytogenes populations declined immediately on the peanut and pistachio shells treated with aQUAT or ipQUAT. After incubation, Salmonella and E. coli O157:H7 populations increased significantly on the water- or aQUAT-treated peanut and pistachio shells. L. monocytogenes populations also increased significantly on the water- or aQUAT-treated peanut shells, but levels did not change on the water-treated pistachio shells and levels were just above the limit of detection on the aQUAT-treated pistachio shells. After treatment with ipQUAT and 48-h incubation, Salmonella and E. coli O157:H7 populations decreased to or below the limit of detection on both shell types; L. monocytogenes populations remained at or below the limit of detection on both shell types. PMID:25583342

McEgan, Rachel; Danyluk, Michelle D

2015-05-01

188

Ion distribution in quaternary-ammonium-functionalized aromatic polymers: effects on the ionic clustering and conductivity of anion-exchange membranes.  

PubMed

A series of copoly(arylene ether sulfone)s that have precisely two, three, or four quaternary ammonium (QA) groups clustered directly on single phenylene rings along the backbone are studied as anion-exchange membranes. The copolymers are synthesized by condensation polymerizations that involve either di-, tri-, or tetramethylhydroquinone followed by virtually complete benzylic bromination using N-bromosuccinimide and quaternization with trimethylamine. This synthetic strategy allows excellent control and systematic variation of the local density and distribution of QA groups along the backbone. Small-angle X-ray scattering of these copolymers shows extensive ionic clustering, promoted by an increasing density of QA on the single phenylene rings. At an ion-exchange capacity (IEC) of 2.1?meq?g(-1), the water uptake decreases with the increasing local density of QA groups. Moreover, at moderate IECs at 20?°C, the Br(-) conductivity of the densely functionalized copolymers is higher than a corresponding randomly functionalized polymer, despite the significantly higher water uptake of the latter. Thus, the location of multiple cations on single aromatic rings in the polymers facilitates the formation of a distinct percolating hydrophilic phase domain with a high ionic concentration to promote efficient anion transport, despite probable limitations by reduced ion dissociation. These findings imply a viable strategy to improve the performance of alkaline membrane fuel cells. PMID:25044778

Weiber, E Annika; Jannasch, Patric

2014-09-01

189

Improvement of separation efficiencies of anion-exchange chromatography using monolithic silica capillary columns modified with polyacrylates and polymethacrylates containing tertiary amino or quaternary ammonium groups.  

PubMed

Anion-exchange (AEX) columns were prepared by on-column polymerization of acrylates and methacrylates containing tertiary amino or quaternary ammonium groups on monolithic silica in a fused silica capillary modified with anchor groups. The columns provided a plate height (H) of less than 10 microm at optimum linear velocity (u) with keeping their high permeability (K=9-12 x 10(-14) m2). Among seven kinds of AEX columns, a monolithic silica column modified with poly(2-hydroxy-3-(4-methylpiperazin-1-yl)propyl methacrylates) (HMPMA) showed larger retentions and better selectivities for nucleotides and inorganic anions than the others. The HMPMA column of 410 mm length produced 42,000-55,000 theoretical plates (N) at a linear velocity of 0.97 mm/s with a backpressure of 3.8 MPa. The same column could be employed for a fast separation of inorganic anions in 1.8 min at a linear velocity of 5.3 mm/s with a backpressure of 20 MPa. In terms of van Deemter plot and separation impedance, the HMPMA column showed higher performance than a conventional particle-packed AEX column. The HMPMA column showed good recovery of a protein, trypsin inhibitor, and it was applied to the separation of proteins and tryptic digest of bovine serum albumin (BSA) in a gradient elution, to provide better separation compared to a conventional particle-packed AEX column. PMID:19683243

Watanabe, Yuta; Ikegami, Tohru; Horie, Kanta; Hara, Takeshi; Jaafar, Jafariah; Tanaka, Nobuo

2009-10-30

190

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts  

PubMed Central

Summary The (salen)Co(III) complex 1 tethering four quaternary ammonium salts, which is a highly active catalyst in CO2/epoxide copolymerizations, shows high activity for propylene oxide/phthalic anhydride (PO/PA) copolymerizations and PO/CO2/PA terpolymerizations. In the PO/PA copolymerizations, full conversion of PA was achieved within 5 h, and strictly alternating copolymers of poly(1,2-propylene phthalate)s were afforded without any formation of ether linkages. In the PO/CO2/PA terpolymerizations, full conversion of PA was also achieved within 4 h. The resulting polymers were gradient poly(1,2-propylene carbonate-co-phthalate)s because of the drift in the PA concentration during the terpolymerization. Both polymerizations showed immortal polymerization character; therefore, the molecular weights were determined by the activity (g/mol-1) and the number of chain-growing sites per 1 [anions in 1 (5) + water (present as impurity) + ethanol (deliberately fed)], and the molecular weight distributions were narrow (M w/M n, 1.05–1.5). Because of the extremely high activity of 1, high-molecular-weight polymers were generated (M n up to 170,000 and 350,000 for the PO/PA copolymerization and PO/CO2/PA terpolymerization, respectively). The terpolymers bearing a substantial number of PA units (f PA, 0.23) showed a higher glass-transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C). PMID:25161738

Jeon, Jong Yeob; Eo, Seong Chan; Varghese, Jobi Kodiyan

2014-01-01

191

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts.  

PubMed

The (salen)Co(III) complex 1 tethering four quaternary ammonium salts, which is a highly active catalyst in CO2/epoxide copolymerizations, shows high activity for propylene oxide/phthalic anhydride (PO/PA) copolymerizations and PO/CO2/PA terpolymerizations. In the PO/PA copolymerizations, full conversion of PA was achieved within 5 h, and strictly alternating copolymers of poly(1,2-propylene phthalate)s were afforded without any formation of ether linkages. In the PO/CO2/PA terpolymerizations, full conversion of PA was also achieved within 4 h. The resulting polymers were gradient poly(1,2-propylene carbonate-co-phthalate)s because of the drift in the PA concentration during the terpolymerization. Both polymerizations showed immortal polymerization character; therefore, the molecular weights were determined by the activity (g/mol-1) and the number of chain-growing sites per 1 [anions in 1 (5) + water (present as impurity) + ethanol (deliberately fed)], and the molecular weight distributions were narrow (M w/M n, 1.05-1.5). Because of the extremely high activity of 1, high-molecular-weight polymers were generated (M n up to 170,000 and 350,000 for the PO/PA copolymerization and PO/CO2/PA terpolymerization, respectively). The terpolymers bearing a substantial number of PA units (f PA, 0.23) showed a higher glass-transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C). PMID:25161738

Jeon, Jong Yeob; Eo, Seong Chan; Varghese, Jobi Kodiyan; Lee, Bun Yeoul

2014-01-01

192

Structural characterization of zinc(II) chloride in aqueous solution and in the protic ionic liquid ethyl ammonium nitrate by x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the species and structures existing in a series of ZnCl2-H2O-NaCl solutions with different chloride/zinc ratios and in a solution of ZnCl2 in the protic ionic liquid ethyl ammonium nitrate (EAN). The average coordination numbers and distances of zinc species were determined from the analysis of the EXAFS data. In aqueous solution the number of chloride ions tightly bounded to Zn2+ is significantly related to the chloride/zinc ratio, and no inner complex formation between Zn2+ and Cl- ions has been detected for low ZnCl2 concentration (0.1 and 0.2 M). Conversely, in the same concentration range (0.13 M) the ZnCl2 species do not dissociate in EAN and the Zn2+ first coordination shell has two chloride ions and is completed by two oxygen atoms of the nitrate anion. The results of this investigation show that notwithstanding the existence of similar characteristics between EAN and water, the solvation properties of the two solvents are markedly different.

D'Angelo, Paola; Zitolo, Andrea; Ceccacci, Francesca; Caminiti, Ruggero; Aquilanti, Giuliana

2011-10-01

193

Combinatorial materials research applied to the development of new surface coatings XV: an investigation of polysiloxane anti-fouling/fouling-release coatings containing tethered quaternary ammonium salt groups.  

PubMed

As part of ongoing efforts aimed at the development of extensive structure?property relationships for moisture-curable polysiloxane coatings containing tethered quaternary ammonium salt (QAS) moieties for potential application as environmental friendly coatings to combat marine biofouling, a combinatorial/high-throughput (C/HT) study was conducted that was focused on four different compositional variables. The coatings that were investigated were derived from solution blends of a silanol-terminated polydimethylsiloxane (HO-PDMS-OH), QAS-functional alkoxysilane, and methyltriacetoxysilane. The compositional variables investigated were alkoxysilane functionality of the QAS-functional silane, chain length of the monovalent alkyl group attached to the QAS nitrogen atom, concentration of the QAS-functional alkoxysilane, and molecular weight of the HO-PDMS-OH. Of these variables, the composition of the alkoxysilane functionality of the QAS-functional silane was a unique variable that had not been previously investigated. The antifouling (AF) and fouling-release (FR) characteristics of the 24 unique coating compositions were characterized using HT assays based on three different marine microorganisms, namely, the two bacteria, Cellulophaga lytica and Halomonas pacifica, and the diatom, Navicula incerta. Coatings surfaces were characterized by surface energy, water contact angle hysteresis, and atomic force microscopy (AFM). A wide variety of responses were obtained over the compositional space investigated. ANOVA analysis showed that the compositional variables and their interactions significantly influenced AF/FR behaviors toward individual marine microorganisms. It was also found that utilization of the ethoxysilane-functional QASs provided enhanced AF character compared to coatings based on methoxysilane-functional analogues. This was attributed to enhanced surface segregation of QAS groups at the coating-air interface and confirmed by phase images using AFM. PMID:21480666

Majumdar, Partha; Crowley, Elizabeth; Htet, Maung; Stafslien, Shane J; Daniels, Justin; VanderWal, Lyndsi; Chisholm, Bret J

2011-05-01

194

Combinatorial materials research applied to the development of new surface coatings IX: an investigation of novel antifouling/fouling-release coatings containing quaternary ammonium salt groups.  

PubMed

Polysiloxane coatings containing chemically-bound ("tethered") quaternary ammonium salt (QAS) moieties were investigated for potential application as environmental-friendly coatings to control marine biofouling. A combinatorial/high-throughput approach was applied to the investigation to enable multiple variables to be probed simultaneously and efficiently. The variables investigated for the moisture-curable coatings included QAS composition, ie alkyl chain length, and concentration as well as silanol-terminated polysiloxane molecular weight. A total of 75 compositionally unique coatings were prepared and characterized using surface characterization techniques and biological assays. Biological assays were based on two different marine microorganisms, a bacterium, Cellulophaga lytica and a diatom, Navicula incerta, as well as a macrofouling alga, Ulva. The results of the study showed that all three variables influenced coating surface properties as well as antifouling (AF) and fouling-release (FR) characteristics. The incorporation of QAS moieties into a polysiloxane matrix generally resulted in an increase in coating surface hydrophobicity. Characterization of coating surface morphology revealed a heterogeneous, two-phase morphology for many of the coatings investigated. A correlation was found between water contact angle and coating surface roughness, with the contact angle increasing with increasing surface roughness. Coatings based on the QAS moiety containing the longest alkyl chain (18 carbons) displayed the highest micro-roughness and, thus, the most hydrophobic surfaces. With regard to AF and FR properties, coatings based on the 18 carbon QAS moieties were very effective at inhibiting C. lytica biofilm formation and enabling easy removal of Ulva sporelings (young plants) while coatings based on the 14 carbon QAS moities were very effective at inhibiting biofilm growth of N. incerta. PMID:18368587

Majumdar, Partha; Lee, Elizabeth; Patel, Nehal; Ward, Kaley; Stafslien, Shane J; Daniels, Justin; Chisholm, Bret J; Boudjouk, Philip; Callow, Maureen E; Callow, James A; Thompson, Stephanie E M

2008-01-01

195

Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for Cr(VI) and P(V) removal.  

PubMed

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties (QM-chitosan) was prepared and employed to remove chromium(VI) and phosphorus(V) (Cr(VI) and P(V)) from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), energy dispersive X-ray (SEM-EDX) and zeta potential. Batch experiments show that QM-chitosan can effectively remove Cr(VI) and P(V), and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr(VI) and P(V) removal. The adsorption isotherms of both Cr(VI) and P(V) on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P(V) (2.783mmol/g) was found to be higher than that of Cr(VI) (2.323mmol/g), resulting from the size of the H2PO4(-) ions being smaller than that of the HCrO4(-) ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr(VI) than P(V). The adsorption-desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated. PMID:25499485

Yao, Wei; Rao, Pinhua; Lo, Irene M C; Zhang, Wenqi; Zheng, Wenrui

2014-12-01

196

Functionalization of cotton fabrics by radiation induced grafting of quaternary salt to impart antibacterial property  

Microsoft Academic Search

High energy gamma radiation has been used to covalently link polymer chains of a quaternary ammonium salt containing monomer, viz. [2-(Acryloyloxyethyl)]trimethylammonium chloride (AETC) to cotton fabric by mutual radiation grafting using 2-hydroxyethyl methacrylate (2-HEMA) monomer as the grafting facilitator. Grafting yield was found to increase with the radiation dose and monomer concentration. The grafted samples have been characterized for water

N. K. Goel; Virendra Kumar; M. S. Rao; Y. K. Bhardwaj; S. Sabharwal

2011-01-01

197

Synthesis of Quaternary Heterocyclic Salts  

PubMed Central

The microwave synthesis of twenty quaternary ammonium salts is described. The syntheses feature comparable yields to conventional synthetic methods reported in the current literature with reduced reaction times and the absence of solvent or minimal solvent. PMID:24256924

Winstead, Angela J.; Nyambura, Grace; Matthews, Rachael; Toney, Deveine; Oyaghire, Stanley

2014-01-01

198

A second polymorph of bis-(triphenyl-?(5)-phosphanyl-idene)ammonium chloride-boric acid adduct.  

PubMed

The title crystal structure is a new triclinic polymorph of [(Ph3P)2N]Cl·(B(OH)3) or C36H30NP2 (+)·Cl(-)·BH3O3. The crystal structure of the ortho-rhom-bic polymorph was reported by [Andrews et al. (1983 ?). Acta Cryst. C39, 880-882]. In the crystal, the [(Ph3P)2N](+) cations have no significant contacts to the chloride ions nor to the boric acid mol-ecules. This is indicated by the P-N-P angle of 137.28?(8)°, which is in the expected range for a free [(Ph3P)2N](+) cation. The boric acid mol-ecules form inversion dimers via pairs of O-H?O hydrogen bonds, and each boric acid mol-ecule forms two additional O-H?Cl hydrogen bonds to one chloride anion. These entities fill channels, created by the [(Ph3P)2N](+) cations, along the c-axis direction. PMID:24427065

Correia Bicho, Bruno A; Bolli, Christoph; Jenne, Carsten; Seeger, Helene

2013-01-01

199

A second polymorph of bis­(triphenyl-?5-phosphanyl­idene)ammonium chloride–boric acid adduct  

PubMed Central

The title crystal structure is a new triclinic polymorph of [(Ph3P)2N]Cl·(B(OH)3) or C36H30NP2 +·Cl?·BH3O3. The crystal structure of the ortho­rhom­bic polymorph was reported by [Andrews et al. (1983 ?). Acta Cryst. C39, 880–882]. In the crystal, the [(Ph3P)2N]+ cations have no significant contacts to the chloride ions nor to the boric acid mol­ecules. This is indicated by the P—N—P angle of 137.28?(8)°, which is in the expected range for a free [(Ph3P)2N]+ cation. The boric acid mol­ecules form inversion dimers via pairs of O—H?O hydrogen bonds, and each boric acid mol­ecule forms two additional O—H?Cl hydrogen bonds to one chloride anion. These entities fill channels, created by the [(Ph3P)2N]+ cations, along the c-axis direction. PMID:24427065

Correia Bicho, Bruno A.; Bolli, Christoph; Jenne, Carsten; Seeger, Helene

2013-01-01

200

5-Acetyl-4-(3-hy­droxy­phen­yl)-6-methyl-1,2,3,4-tetra­hydro­pyrimidin-2-one–tris­(hy­droxy­meth­yl)ammonium chloride (2/1)  

PubMed Central

The asymmetric unit of the title compound, 2C13H14N2O3·C3H10NO3 +·Cl?, contains two independent mol­ecules (A and B) of the title pyrimidine derivative and one ion-pair of tris­(hy­droxy­meth­yl)ammonium chloride. The pyrimidine ring in each pyrimidine derivative has a half-chair conformation. Its mean plane is inclined to the benzene ring by 87.2?(3)° in mol­ecule A and 85.7?(2)° in mol­ecule B. In the crystal, the pyrimidine derivatives are connected to each other by N—H?O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked via O—H—Cl hydrogen bonds, forming corrugated sheets lying parallel to the bc plane. The sheets are linked via C—H?O hydrogen bonds, forming a three-dimensional framework. The tris­(hy­droxy­meth­yl)ammonium chloride mol­ecules are located in the cages of the framework. There are also further C—H?O hydrogen bonds and C—H?? inter­actions present in the three-dimensional framework structure. Both the cation and chloride anion of the tris­(hy­droxy­meth­yl)ammonium chloride ion pair are disordered over two positions, with a refined occupancy ratio of 0.418?(8):0.582?(8) for the cation and 0.71?(4):0.29?(4) for the anion. PMID:24454216

Huq, C. A. M. A.; Fouzia, S.; NizamMohideen, M.

2013-01-01

201

5-Acetyl-4-(3-hy-droxy-phen-yl)-6-methyl-1,2,3,4-tetra-hydro-pyrimidin-2-one-tris-(hy-droxy-meth-yl)ammonium chloride (2/1).  

PubMed

The asymmetric unit of the title compound, 2C13H14N2O3·C3H10NO3 (+)·Cl(-), contains two independent mol-ecules (A and B) of the title pyrimidine derivative and one ion-pair of tris-(hy-droxy-meth-yl)ammonium chloride. The pyrimidine ring in each pyrimidine derivative has a half-chair conformation. Its mean plane is inclined to the benzene ring by 87.2?(3)° in mol-ecule A and 85.7?(2)° in mol-ecule B. In the crystal, the pyrimidine derivatives are connected to each other by N-H?O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked via O-H-Cl hydrogen bonds, forming corrugated sheets lying parallel to the bc plane. The sheets are linked via C-H?O hydrogen bonds, forming a three-dimensional framework. The tris-(hy-droxy-meth-yl)ammonium chloride mol-ecules are located in the cages of the framework. There are also further C-H?O hydrogen bonds and C-H?? inter-actions present in the three-dimensional framework structure. Both the cation and chloride anion of the tris-(hy-droxy-meth-yl)ammonium chloride ion pair are disordered over two positions, with a refined occupancy ratio of 0.418?(8):0.582?(8) for the cation and 0.71?(4):0.29?(4) for the anion. PMID:24454216

Huq, C A M A; Fouzia, S; Nizammohideen, M

2013-11-13

202

Standard molar enthalpy of combustion and formation of quaternary ammonium tetrachlorozincate [n-CnH2n+1 N(CH3)3]2 ZnCl4.  

PubMed

The standard molar enthalpy of combustion (?c H (o) m) and formation (?f H (o) m) of quaternary ammonium tetrachlorozincate [n-CnH2n+1N(CH3)3]2ZnCl4 have been determined for the hydrocarbon chain length from even number 8 to 18 of carbon atoms (n) by an oxygen-bomb combustion calorimeter. The results indicated that the values of ?c H (o) m increased and ?f H (o) m decreased with increasing chain length and showed a linear dependence on the number of carbon atoms, which were caused by that the order and rigidity of the hydrocarbon chain decreased with increasing the carbon atoms. The linear regression equations are -?c H (o) m =1440.50n +3730.67 and -?f H (o) m = -85.32n + 1688.22. PMID:23519475

Ren, Biyan; Zhang, Shuying; Ruan, Bei; Wu, Kezhong; Zhang, Jianjun

2013-12-01

203

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)  

PubMed Central

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 ? cm2 and 0.83, respectively. PMID:24958543

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2012-01-01

204

Infrared band intensities in ammonium hydroxide and ammonium salts  

NASA Technical Reports Server (NTRS)

We have applied Kramers-Kronig analysis to reflection spectra to determine the optical constants of ammonium hydroxide and of aqueous solutions of ammonium chloride and bromide. From considerations of the absorption indices k(nu) we conclude that ammonium hydroxide consists of a solution of NH3 in water, in which NH3 molecules are hydrogen bonded to neighboring water molecules. The spectrum of ammonium hydroxide differs from the spectra of ammonium salts, in which bands characteristic of NH4(+) ions are prominent. The existence of ammonium hydroxide as an aerosol in planetary atmospheres is briefly discussed

Sethna, P. P.; Downing, H. D.; Pinkley, L. W.; Williams, D.

1978-01-01

205

Benzalkonium chloride. Health hazard evaluation report  

SciTech Connect

Health hazards associated with the use of benzalkonium chlorides (BAC) are reviewed. Benzalkonium chloride is extensively used as a cationic disinfectant. It is found in a great many over-the-counter and prescription eye products, disinfectants, shampoos, and deodorants, and is used in concentrations that range from 0.001 to 0.01% in eyedrops, up to 2.5% in concentrated liquid disinfectants. Solutions of 0.03 to 0.04% BAC may cause temporary eye irritation in humans but are unlikely to cause any skin response except in persons allergic to quaternary ammonium compounds. Inhalation of a vaporized 10% solution of BAC produced a bronchospasmodic reaction in a previously sensitized individual. At present no other human health effects from BAC have been documented or inferred from exposure to such dilute concentrations.

Bernholc, N.M.

1984-01-01

206

[Antimicrobial action of ammonium salts of fused heterocycles containing ortho-nitrogen].  

PubMed

By alkylation of hexamethylenetetramine with halogenated derivatives of ketones, ethers, esters or amides of acids, alkyl- and aralkyl halides the corresponding N-monoalkylated compounds of hexamethylenetetramine were obtained. The quaternization of pyridine nitrogen in 5,6-benzoquinoline, 8-hydroxyquinoline, quinoline, 1,10-phenanthroline molecules with alkyl- or aralkylhalides was carried out. The susceptibility of Gram-positive (Streptococcus agalactiae and Staphylococcus aureus) and Gram-negative (E. coli, Salmonella cholerae suis, Salmonella enteridis Gartneri) microorganisms to synthesized quaternary ammonium salts by disc difussion method has been detected. The bacteriostatic action of 0.5-1% solutions of all compounds was assessed in comparison with benzalkonium chloride. It was shown, that the most effectiveness against all strains is possessed by quaternary hexamethylenetetramine ammonium salts, and especially salts, containing 1-propynyl- or hydroxycarbamoylmethyl radicals. The action of these two compounds against Salmonella and Streptococcus was stronger than the action of benzalkonium chloride. Susceptibility of Pseudomonas aeruginosa to these compounds were detected. It was shown, that 1% solutions of chlorides of N-(1-propynyl) hexamethylenetetramonium and N-(hydroxycarbamoylmethyl) hexamethylenetetrammonium demonstrate the same bacteriostatic action against P. aeruginosa as well as benzalkonium chloride. PMID:14617863

Stankeviciene, Laimute; Grigonis, Aidas; Matusevicius, Algimantas; Janusiene, Laima; Stankevicius, Antanas

2003-01-01

207

The cytotoxicity of methacryloxylethyl cetyl ammonium chloride, a cationic antibacterial monomer, is related to oxidative stress and the intrinsic mitochondrial apoptotic pathway.  

PubMed

Antibacterial monomers incorporated in dentin bonding systems may have toxic effects on the pulp. Thus, the cytotoxicity of antibacterial monomers and its underlying mechanisms must be elucidated to improve the safety of antibacterial monomer application. The influence of an antibacterial monomer, methacryloxylethyl cetyl ammonium chloride (DMAE-CB), on the vitality of L929 mouse fibroblasts was tested using MTT assay. Cell cycle progression was studied using flow cytometry. Production of intracellular reactive oxygen species (ROS) after DMAE-CB treatment was measured using 2,7-dichlorodihydrofluorescein diacetate staining and flow cytometry analysis. Loss of mitochondrial membrane potential, disturbance of Bcl-2 and Bax expression, as well as release of cytochrome C were also measured using flow cytometry analysis or Western blot to explore the possible involvement of the mitochondrial-related apoptotic pathway. DMAE-CB elicited cell death in a dose-dependent manner and more than 50% of cells were killed after treatment with 30 µM of the monomer. Both necrosis and apoptosis were observed. DMAE-CB also induced G1- and G2-phase arrest. Increased levels of intracellular ROS were observed after 1 h and this overproduction was further enhanced by 6-h treatment with the monomer. DMAE-CB may cause apoptosis by disturbing the expression of Bcl-2 and Bax, reducing the mitochondrial potential and inducing release of cytochrome C. Taken together, these findings suggest that the toxicity of the antibacterial monomer DMAE-CB is associated with ROS production, mitochondrial dysfunction, cell cycle disturbance, and cell apoptosis/necrosis. PMID:22002093

Ma, Sai; Shan, Le-qun; Xiao, Yu-hong; Li, Fang; Huang, Li; Shen, Lijuan; Chen, Ji-hua

2011-11-01

208

Occupational allergic contact dermatitis from 2,3-epoxypropyl trimethyl ammonium chloride (EPTMAC) and Kathon LX in a starch modification factory.  

PubMed

2,3-epoxypropyl trimethyl ammonium chloride (EPTMAC) is used in the production of cationic starch (CS) for the paper industry. It has been shown to be a sensitizer in guinea pigs, but cases of human sensitization are few. 4 workers were previously sensitized to the substance in a Finnish plant. This report describes 3 process men from another plant examined because of recurring dermatitis. 18 workers were involved in production, and had free access to all work sites. 3 process men, whose work involved drying the CS, had dermatitis, although they had only occasional contact with the cationizing chemical. 2 were already verified to be allergic to EPTMAC and had had variable dermatitis for 8-12 years. One had had dermatitis on his face for 1 year. Patch testing with a dilution series (1%, 0.5%, 0.2%, 0.1% pet.) confirmed their allergy to the cationizing chemical containing EPTMAC, but tests with CS were negative. In addition, 2 had contact allergy to Cl+ Me-isothiazolinone from contact with Kathon LX used as a slimicide in the process. In long-standing (years) recurrent dermatitis, re-examination of patients with verified exposure history and skin test is necessary. In line with our previous study, sampling the process materials, maintenance work and contamination of work sites and gloves caused sensitization. The results also confirm that EPTMAC is a strong human contact sensitizer. 0.2%-0.5% pure EPTMAC in pet. seems to be the optimal patch test concentration. PMID:9165201

Estlander, T; Jolanki, R; Kanerva, L

1997-04-01

209

Adsorption properties of biologically active derivatives of quaternary ammonium surfactants and their mixtures at aqueous/air interface. I. Equilibrium surface tension, surfactant aggregation and wettability.  

PubMed

The adsorption properties of surfactant mixtures containing two types of quaternary derivatives of lysosomotropic substances: alkyl N,N-dimethylalaninates methobromides and alkyl N,N-dimethylglycinates methobromides were studied. Quantitative and qualitative description of the adsorption process was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. The results indicated that most of the systems studied revealed synergistic effect both in adsorption and wetting properties. In vitro studies on human cancer cells were undertaken and the data obtained showed that the mixtures suppressed the cancer cells' proliferation more effectively than individual components. Results of preliminary research on the interaction of catanionic mixtures with phospholipids suggested a possibility of a strong penetration of cell membranes by the mixtures investigated. PMID:23751418

Rojewska, Monika; Biadasz, Andrzej; Kotkowiak, Micha?; Olejnik, Anna; Rychlik, Joanna; Dudkowiak, Alina; Prochaska, Krystyna

2013-10-01

210

Methyl chloride via oxhydrochlorination of methane  

SciTech Connect

Dow Corning is developing a route from methane to methyl chloride via oxyhydrochlorination (OHC) chemistry with joint support from the Gas Research Institute and the Department of Energy Federal Energy Technology Center. Dow Corning is the world`s largest producer of methyl chloride and uses it as an intermediate in the production of silicone materials. Other uses include production of higher hydrocarbons, methyl cellulose, quaternary ammonium salts and herbicides. The objective of this project is to demonstrate and develop a route to methyl chloride with reduced variable cost by using methane instead of methanol raw materials. Methyl chloride is currently produced from methanol, but U.S. demand is typically higher than available domestic supply, resulting in fluctuating prices. OHC technology utilizes domestic natural gas as a feedstock, which allows a lower-cost source of methyl chloride which is independent of methanol. In addition to other uses of methyl chloride, OHC could be a key step in a gas-to-liquid fuels process. These uses could divert significant methanol demand to methane. A stable and selective catalyst has been developed in the laboratory and evaluated in a purpose-built demonstration unit. Materials of construction issues have been resolved and the unit has been run under a range of conditions to evaluate catalyst performance and stability. Many technological advances have been made, especially in the areas of catalyst development, online FTIR analysis of the product stream, and recovery of methyl chloride product via an absorber/stripper system. Significant technological hurdles still remain including heat transfer, catalysts scaleup, orthogonality in modeling, and scaleable absorption data. Economics of the oxyhydrochlorination process have been evaluated an found to be unfavorable due to high capital and utility costs. Future efforts will focus on improved methane conversion at high methyl chloride selectivity.

Jarvis, R.F. Jr.

1997-12-31

211

Analysis of quaternary ammonium compounds in estuarine sediments by LC-ToF-MS: very high positive mass defects of alkylamine ions provide powerful diagnostic tools for identification and structural elucidation  

PubMed Central

A sensitive and robust method of analysis for quaternary ammonium compounds (QACs) in marine sediments is presented. Methods for extraction, sample purification, and HPLC-Time-of-Flight-MS analysis were optimized, providing solutions to problems associated with analysis of QACs, such as dialkyldimethylammonium (DADMAC) and benzalkonium (BAC) compounds experienced previously. Recognized in this study are the exceptionally high positive mass defects characteristic of alkylammonium or protonated alkylamine ions. No alternative and chemically-viable elemental formulas exist within 25.2 mDa when the number of double bond equivalents is low, effectively allowing facile discrimination of this compound class in complex mixtures. Accurate mass measurements of diagnostic collision induced dissociation fragment ions and heavy isotope peaks were obtained and also seen to be uniquely heavy compared to other elemental formulae. In the case of BACs, the ability to resolve masses of alkylamine fragment ions is greater than it is for molecular ions, opening up a wide range of potential applications. The power of utilizing a combination of approaches is illustrated with the identification of non-targeted DADMAC C8:C8 and C8:C10, two widely used biocides previously unreported in environmental samples. Concentrations of QACs in sewage-impacted estuarine sediments (up to 74 ?g/g) were higher than concentrations of other organic contaminants measured in the same or nearby samples, suggesting further study is needed. PMID:19739657

Li, Xiaolin; Brownawell, Bruce J.

2009-01-01

212

The preparation of quaternary ammonium-based ionic liquid containing a cyano group and its properties in a lithium battery electrolyte  

NASA Astrophysics Data System (ADS)

A room temperature ionic liquid consisting of N, N, N, N-cyanomethyl trimethyl ammonium (CTMA) cation and bis(trifluoromethane sulfone)imide (TFSI) anion was newly synthesized, and its electrochemical properties were investigated. This ionic liquid has a melting point of 35 °C and an order of conductivity of 10 -4 S cm -1. Lithium deposition/dissolution tests in 0.2 mol dm -3 LiTFSI/CTMATFSI electrolytes showed an improved cycle behavior compared with that of a Li electrolyte based on a tetraalkylammonium ionic liquid without a cyano group. It is suggested that such an improvement may be associated with the formation of a protective film on the lithium surface. Introducing a proper functional group is suggested to be effective to improve the interfacial properties of ionic liquid.

Egashira, Minato; Okada, Shigeto; Yamaki, Jun-ichi; Dri, Diego Alejandro; Bonadies, Francesco; Scrosati, Bruno

213

Functionalization of cotton fabrics by radiation induced grafting of quaternary salt to impart antibacterial property  

NASA Astrophysics Data System (ADS)

High energy gamma radiation has been used to covalently link polymer chains of a quaternary ammonium salt containing monomer, viz. [2-(Acryloyloxyethyl)]trimethylammonium chloride (AETC) to cotton fabric by mutual radiation grafting using 2-hydroxyethyl methacrylate (2-HEMA) monomer as the grafting facilitator. Grafting yield was found to increase with the radiation dose and monomer concentration. The grafted samples have been characterized for water uptake, surface morphology and thermal stability and for their antibacterial efficacy against various bacteria and were found to possess significant antibacterial activity particularly against gram-positive bacteria.

Goel, N. K.; Kumar, Virendra; Rao, M. S.; Bhardwaj, Y. K.; Sabharwal, S.

2011-11-01

214

Adsorption properties of biologically active derivatives of quaternary ammonium surfactants and their mixtures at aqueous/air interface II. Dynamics of adsorption, micelles dissociation and cytotoxicity of QDLS.  

PubMed

The main aim of our study was analysis of adsorption dynamics of mixtures containing quaternary derivatives of lysosomotropic substance (QDLS). Two types of equimolar mixtures were considered: the ones containing two derivatives of lysosomotropic substances (DMALM-12 and DMGM-12) as well as the catanionic mixtures i.e. the systems containing QDLS and DBSNa. Dynamic surface tension measurements of surfactant mixtures were made. The results suggested that the diffusivity of the mixed system could be treated as the average value of rates of diffusion of individual components, micelles and ion pairs, which are present in the mixtures studied. Moreover, an attempt was made to explain the influence of the presence of micelles in the mixtures on their adsorption dynamics. The compounds examined show interesting biological properties which can be useful, especially for drug delivery in medical treatment. In vitro cytotoxic activities of the mixtures studied towards human cancer cells were evaluated. Most of the mixtures showed a high antiproliferative potential, especially the ones containing DMALM-12. Each cancer cell line used demonstrated different sensitivity to the same dose of the mixtures tested. PMID:24768517

Rojewska, Monika; Prochaska, Krystyna; Olejnik, Anna; Rychlik, Joanna

2014-07-01

215

Mutational upregulation of a resistance-nodulation-cell division-type multidrug efflux pump, SdeAB, upon exposure to a biocide, cetylpyridinium chloride, and antibiotic resistance in Serratia marcescens.  

PubMed

Serratia marcescens is an important opportunistic pathogen in hospitals, where quaternary ammonium compounds are often used for disinfection. The aim of this study is to elucidate the effect of a biocide on the emergence of biocide- and antibiotic-resistant mutants and to characterize the molecular mechanism of biocide resistance in Serratia marcescens. A quaternary ammonium compound-resistant strain, CRes01, was selected by exposing a wild-type strain of S. marcescens to cetylpyridinium chloride. The CRes01 cells exhibited 2- to 16-fold more resistance than the wild-type cells to biocides and antibiotics, including cetylpyridinium chloride, benzalkonium chloride, chlorhexidine gluconate, fluoroquinolones, tetracycline, and chloramphenicol, and showed increased susceptibilities to beta-lactam antibiotics and N-dodecylpyridinium iodide. Mutant cells accumulated lower levels of norfloxacin than the parent cells in an energized state but not in a de-energized state, suggesting that the strain produced a multidrug efflux pump(s). To verify this assumption, we knocked out a putative efflux pump gene, sdeAB, in CRes01 and found that the knockout restored susceptibility to most quaternary ammonium compounds and antibiotics, to which the CRes01 strain showed resistance. On the basis of these and other results, we concluded that S. marcescens gains resistance to both biocides and antibiotics by expressing the SdeAB efflux pump upon exposure to cetylpyridinium chloride. PMID:19752278

Maseda, Hideaki; Hashida, Yumiko; Konaka, Rumi; Shirai, Akihiro; Kourai, Hiroki

2009-12-01

216

Evaluation of Reduced Susceptibility to Quaternary Ammonium Compounds and Bisbiguanides in Clinical Isolates and Laboratory-Generated Mutants of Staphylococcus aureus  

PubMed Central

The MICs and minimum bactericidal concentrations (MBCs) for the biocides benzalkonium chloride and chlorhexidine were determined against 1,602 clinical isolates of Staphylococcus aureus. Both compounds showed unimodal MIC and MBC distributions (2 and 4 or 8 mg/liter, respectively) with no apparent subpopulation with reduced susceptibility. To investigate further, all isolates were screened for qac genes, and 39 of these also had the promoter region of the NorA multidrug-resistant (MDR) efflux pump sequenced. The presence of qacA, qacB, qacC, and qacG genes increased the mode MIC, but not MBC, to benzalkonium chloride, while only qacA and qacB increased the chlorhexidine mode MIC. Isolates with a wild-type norA promoter or mutations in the norA promoter had similar biocide MIC distributions; notably, not all clinical isolates with norA mutations were resistant to fluoroquinolones. In vitro efflux mutants could be readily selected with ethidium bromide and acriflavine. Multiple passages were necessary to select mutants with biocides, but these mutants showed phenotypes comparable to those of mutants selected by dyes. All mutants showed changes in the promoter region of norA, but these were distinct from this region of the clinical isolates. Still, none of the in vitro mutants displayed fitness defects in a killing assay in Galleria mellonella larvae. In conclusion, our data provide an in-depth comparative overview on efflux in S. aureus mutants and clinical isolates, showing also that plasmid-encoded efflux pumps did not affect bactericidal activity of biocides. In addition, current in vitro tests appear not to be suitable for predicting levels of resistance that are clinically relevant. PMID:23669380

Furi, Leonardo; Ciusa, Maria Laura; Knight, Daniel; Di Lorenzo, Valeria; Tocci, Nadia; Cirasola, Daniela; Aragones, Lluis; Coelho, Joana Rosado; Freitas, Ana Teresa; Marchi, Emmanuela; Moce, Laura; Visa, Pilar; Northwood, John Blackman; Viti, Carlo; Borghi, Elisa; Orefici, Graziella

2013-01-01

217

Evaluation of reduced susceptibility to quaternary ammonium compounds and bisbiguanides in clinical isolates and laboratory-generated mutants of Staphylococcus aureus.  

PubMed

The MICs and minimum bactericidal concentrations (MBCs) for the biocides benzalkonium chloride and chlorhexidine were determined against 1,602 clinical isolates of Staphylococcus aureus. Both compounds showed unimodal MIC and MBC distributions (2 and 4 or 8 mg/liter, respectively) with no apparent subpopulation with reduced susceptibility. To investigate further, all isolates were screened for qac genes, and 39 of these also had the promoter region of the NorA multidrug-resistant (MDR) efflux pump sequenced. The presence of qacA, qacB, qacC, and qacG genes increased the mode MIC, but not MBC, to benzalkonium chloride, while only qacA and qacB increased the chlorhexidine mode MIC. Isolates with a wild-type norA promoter or mutations in the norA promoter had similar biocide MIC distributions; notably, not all clinical isolates with norA mutations were resistant to fluoroquinolones. In vitro efflux mutants could be readily selected with ethidium bromide and acriflavine. Multiple passages were necessary to select mutants with biocides, but these mutants showed phenotypes comparable to those of mutants selected by dyes. All mutants showed changes in the promoter region of norA, but these were distinct from this region of the clinical isolates. Still, none of the in vitro mutants displayed fitness defects in a killing assay in Galleria mellonella larvae. In conclusion, our data provide an in-depth comparative overview on efflux in S. aureus mutants and clinical isolates, showing also that plasmid-encoded efflux pumps did not affect bactericidal activity of biocides. In addition, current in vitro tests appear not to be suitable for predicting levels of resistance that are clinically relevant. PMID:23669380

Furi, Leonardo; Ciusa, Maria Laura; Knight, Daniel; Di Lorenzo, Valeria; Tocci, Nadia; Cirasola, Daniela; Aragones, Lluis; Coelho, Joana Rosado; Freitas, Ana Teresa; Marchi, Emmanuela; Moce, Laura; Visa, Pilar; Northwood, John Blackman; Viti, Carlo; Borghi, Elisa; Orefici, Graziella; Morrissey, Ian; Oggioni, Marco Rinaldo

2013-08-01

218

Quaternary ammonium room-temperature ionic liquid including an oxygen atom in side chain/lithium salt binary electrolytes: ab initio molecular orbital calculations of interactions between ions.  

PubMed

Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids. PMID:18636771

Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime

2008-08-14

219

A study on the ability of quaternary ammonium groups attached to a polyurethane foam wound dressing, to inhibit bacterial attachment and biofilm formation.  

PubMed

Bacterial infection of acute and chronic wounds impedes wound healing significantly. Part of this impediment is the ability of bacterial pathogens to grow in wound dressings. In this study, we examined the effectiveness of a polyurethane foam wound dressings coated with poly diallyl-dimethylammonium chloride (pDADMAC-PU) to inhibit the growth and biofilm development by three main wound pathogens: Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii, within the wound dressing. pDADMAC-PU inhibited the growth of all three pathogens. Time-kill curves were conducted both with and without serum to determine the killing kinetic of pDADMAC-PU. pDADMAC-PU killed S. aureus, A. baumannii, and P. aeruginosa. The effect of pDADMAC-PU on biofilm development was analyzed quantitatively and qualitatively. Quantitative analysis, (CFU) assay, revealed that pDADMAC-PU dressing produced more than 8 log reduction in biofilm formation by each pathogen. Visualization of the biofilms by either confocal laser scanning microscopy or scanning electron microscopy confirmed these findings. In addition, it was found that the pDADMAC-PU treated foam totally inhibited migration of bacteria through the foam for all three bacterial strains. These results suggest that pDADMAC-PU is an effective wound dressing that inhibits the growth of wound pathogens both within the wound and in the wound dressing. PMID:25469865

Tran, Phat L; Hamood, Abdul N; de Souza, Anselm; Schultz, Gregory; Liesenfeld, Bernd; Mehta, Dilip; Reid, Ted W

2014-12-01

220

Vinylbenzyl quaternary ammonium-based polymeric monolith with hydrophilic interaction/strong anion exchange mixed-mode for pressurized capillary electrochromatography.  

PubMed

A novel polymeric monolith with hydrophilic interaction and strong anion-exchange mixed-mode has been fabricated for pressurized capillary electrochromatography by an in situ copolymerization of vinylbenzyl trimethylammonium chloride (VBTA) and bisphenol A glycerolate dimethacrylate (BisGMA). The optimization of the polymerization mixture composition has been investigated, and column characteristics in terms of mechanical stability, permeability and reproducibility have been studied in detail. Linear responses between back pressure and flow rate have been achieved in different solvents. The absolute value of swelling propensity (SP) factor for poly(VBTA-co-BisGMA) monolith is 0.41, and the degree of permeability drop from pure ACN to water is about 45%. An acceptable mechanical stability of the column is obtained. The suitable reproducibility is also measured with the RSD for day-to-day (n=3) of retention time and column efficiency less than 3.3%, and the RSD for batch-to-batch (n=3) less than 5.3%, respectively. Under the optimum conditions, the mixed-mode of hydrophilic interaction and strong anion-exchange has been carried out, and efficient electrochromatography profiling of various polar compounds including neutral phenols, negatively charged benzoic acids and positively charged nucleic acid bases and nucleosides are achieved, respectively. PMID:24125728

Lin, Xucong; Feng, Shuhui; Jia, Wenchao; Ding, Kang; Xie, Zenghong

2013-11-01

221

Substoichiometric isotope dilution mass spectrometry of boron by the ion-pair extraction with halogenated salicyl alcohol derivatives and a quaternary ammonium salt.  

PubMed

Novel salicyl alcohol derivatives (H(2)X(n)sal), 5-bromo-, 3,5-dibromo-, and 3,5-diiodosalicyl alcohol which were abbreviated to H(2)Brsal, H(2)Br(2)sal, and H(2)I(2)sal, respectively, were synthesized and used for the selective extraction of boric acid. Boric acid was extracted with each H(2)X(n)sal into chlorobenzene containing trioctylmethylammonium chloride (TOMACl) as an ion-pair complex, TOMA·B(X(n)sal)(2), at a different pH range. The extraction constant (K(ex)) of boric acid was determined by the equilibrium analyses including the formation of hydrogen-bonded complex of each H(2)X(n)sal with TOMACl in the organic phase. The K(ex) values obtained by salicyl alcohol (H(2)sal) and its derivatives were decreased in the order of H(2)I(2)sal ? H(2)Br(2)sal > H(2)Brsal > H(2)sal. The most powerful extractant, H(2)I(2)sal, was employed for the substoichiometric extraction of boric acid, which was extracted at pH 5 - 9 with a substoichiometric amount of TOMACl in the presence of an excess of H(2)I(2)sal. The present substoichiometric separation method combined with the stable isotope dilution analysis using inductively coupled plasma mass spectrometry (ICP-MS) could be successfully applied to the determination of boron in a reference material of high-analysis compound fertilizer (FAMIC-A-08) without any correction as to the isotopic abundance. PMID:22451364

Morita, Keisuke; Imura, Hisanori

2012-01-01

222

[Formulation of benzethonium chloride into gels].  

PubMed

This study is focused on the preparation of gels with antimicrobial effects. A quaternary ammonium salt, benzethonium chloride, in a concentration of 0.01-0.5% (w/w) was employed as the drug. The humectant employed was propylene glycol in concentrations of 5% and 10% (w/w). Two types of polymers, chitosan and hydroxyethyl cellulose, in the same concentrations of 2.5% (w/w), were used for gel preparation. Finally the flow properties, rheological parameters and pH values of the gels were evaluated. Based on the obtained results, the samples of the gels prepared on the basis of chitosan and hydroxyethyl cellulose, which have the following optimum composition shown below, were found: 2,5% (w/w) CHIT + 0,5% (w/w) BZCl + 10% (w/w) PG; 2,5% (w/w) HEC + 0,5% (w/w) BZCl + 5% (w/w) PG. PMID:25115665

Cižmárik, Jozef; Vitková, Zuzana; Herdová, Petra; Kodadová, Alexandra; Vími, Daniel

2014-06-01

223

High performance ammonium nitrate propellant  

NASA Technical Reports Server (NTRS)

A high performance propellant having greatly reduced hydrogen chloride emission is presented. It is comprised of: (1) a minor amount of hydrocarbon binder (10-15%), (2) at least 85% solids including ammonium nitrate as the primary oxidizer (about 40% to 70%), (3) a significant amount (5-25%) powdered metal fuel, such as aluminum, (4) a small amount (5-25%) of ammonium perchlorate as a supplementary oxidizer, and (5) optionally a small amount (0-20%) of a nitramine.

Anderson, F. A. (inventor)

1979-01-01

224

Quaternary Studies  

NSDL National Science Digital Library

First, the Irish Quaternary Association (IQUA) website publicizes its aim "to promote Quaternary studies in Ireland through its publications, and the organization of field meetings and conferences" (1). Visitors can learn about the importance of quaternary studies as well as find out the latest news and upcoming meetings. At the second website, the University of Wisconsin-Madison describes the current and recent studies dealing with "basic and applied problems in glacial geology, surficial geology, palynology, sedimentology, geologic mapping, hydrogeology, soils, and environmental geology "(2). The website offers abstracts of publications of members of the Department of Geology and Geophysics and the Wisconsin Geological and Natural History Survey along with descriptions of the lab, a shaded relief map of the Wisconsin area, and amusing glacial songs. Next, the Godwin Institute of Quaternary Research (GIQR) presents the University of Cambridge's history in quaternary research and the seven current research groups and four recent research projects (3 ). The website furnishes news from the research groups, a gallery of historical images of the East Anglia excursion, and summaries of the Institute's reference collections. Fourth, the International Union for Quaternary Research (INQUA) discusses quaternary scientists' investigations "to interpret the changing world of the glacial ages and their impact on our planet's surface environments" (4). Researchers can find out about INQUA-funded projects, meetings, and scientific commissions. Next, the Quaternary Research Association explains that it "exists to promote understanding of the Quaternary Period by publishing field guides, technical guides, and an international journal as well as holding field meetings and speaker meetings" (5). Students and researchers can discover employment, research, grant, meetings, and educational opportunities. Sixth, the University of Wales presents its investigations in the Remote Sensing Laboratory, Palaeoecology Laboratory, and the Luminescence Laboratory (6 ). Users can find concise descriptions of individual researchers' successes, abstracts of published papers, and links to conference information. The seventh website illustrates the Alaska Quaternary Center's commitment "to the promotion of interdisciplinary research and the enhancement of interdisciplinary instruction in Quaternary sciences" (7). Users can view images of the field work and learn how to obtain quaternary data from the Geographic Information Network of Alaska (GINA). Lastly, Rutgers University promotes its Graduate Certificate in Quaternary Studies where students take part in geology, geography, meteorology, and other disciplines interested in the last couple of million years of Earth's history (8). Students and educators can find information on the researchers involved with the program and the necessary course work.

225

Synthesis, self-aggregation and biological properties of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride.  

PubMed

A series of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride have been synthesized. Their physicochemical properties were also investigated. The critical micelle concentration (cmc), the surface tension value at the cmc (?cmc), and the surface area at the surface saturation per head group (Acmc) were determined by means of surface tension measurements. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines and alkylphosphohomocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds in general. However, quaternary ammonium compounds exhibit significantly higher activity against human tumor cells and pathogenic free-living amoebae Acanthamoeba lugdunensis and Acanthamoeba quina compared to alkylphosphocholines. The relationship between structure, physicochemical properties and biological activity of the tested compounds is discussed. PMID:23792315

Luká?, Miloš; Mrva, Martin; Garajová, Mária; Mojžišová, Gabriela; Varinská, Lenka; Mojžiš, Ján; Sabol, Marián; Kubincová, Janka; Haragová, Hana; Ondriska, František; Devínsky, Ferdinand

2013-08-01

226

Synthesis, micellisation and interaction of novel quaternary ammonium compounds derived from l-Phenylalanine with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine as model membrane in relation to their antibacterial activity, and their selectivity over human red blood cells.  

PubMed

A series of quaternary ammonium compounds (QUATS) derived from l-Phenylalanine have been synthesized and their antibacterial efficiencies were determined against various strains of Gram-positive and Gram-negative bacteria. The antibacterial activity increased with increasing chain length, exhibiting a cut-off effect at C14 for Gram-positive and C12 for Gram-negative bacteria. The l-Phenylalanine QUATS displayed enhanced antibacterial properties with a higher cut-off point compared to their corresponding l-Phenylalanine ester hydrochlorides. The CMC was correlated with the MIC, inferring that micellar activity contributes to the cut-off effect in antibacterial activity. The hemolytic activities (HC50) of the QUATS against human red blood cells were also determined to illustrate the selectivity of these QUATS for bacterial over mammalian cells. In general, the MIC was lower than the HC50, and assessment of the micellar contribution to the antibacterial and hemolytic evaluation in TBS as a common medium confirmed that these QUATS can act as antibacterial, yet non-toxic molecules at their monomer concentrations. The interaction of the QUATS with the phospholipid vesicles (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) in the presence of 1-anilino-8-naphthalene sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probes showed that the presence of the quaternary ammonium moiety causes an increase in hydrophobic interactions, thus causing an increase in antibacterial activity. PMID:25618736

Joondan, Nausheen; Caumul, Prakashanand; Akerman, Matthew; Jhaumeer-Laulloo, Sabina

2015-02-01

227

Reactions of 2-aminobenzothiazoles with ethylene chlorohydrin. molecular and crystal structure of bis[(3- ? -hydroxyethyl)benzo-thiazolyl-2-indene]ammonium chloride  

Microsoft Academic Search

Hydroxyethylation of 2-aminobenzothiazoles by ethylene chlorohydrin unexpectedly led to preferential formation of 3-ß-chloroethylbenzothiazolin-2-one. In the case of unsubstituted 2-aminobenzothiazole, we also isolated the target 2-indno-3-ß-hydroxyethylbenzothiazoline and bis((3-\\/3-hydroxyethyl)benzothiazolyl-2-indenelamnionium chloride. As a result of reaction of 2-aminobenzothiazole with 3-ß-chloroethylbenzothiazolin-2-one, we obtained 2-(benzothiazolyl-2-imino)-3-(ß-(2-oxobenzothiazolin-3-yl)ethyllbenzothiazoline. The structure ofthesynthesized compounds was established based on x-ray diffraction, PMR, IR, UV, and mass spectra.

M. K. Makhmudov; R. F. Ambartsumova; B. Tashkhodzhaev

1996-01-01

228

Ammonium and urea removal by Spirulina platensis  

Microsoft Academic Search

Different concentrations either of ammonium chloride or urea were used in batch and fed-batch cultivations of Spirulina platensis to evaluate the possibility of substituting nitrate by cheaper reduced nitrogen sources in wastewaters biotreatment. The\\u000a maximum nitrogen concentration able to sustain the batch growth of this microalga without inhibition was 1.7 mM in both cases.\\u000a Ammonium chloride was limiting for the growth

A. Converti; S. Scapazzoni; A. Lodi; J. C. M. Carvalho

2006-01-01

229

Biodegradation of rocket propellant waste, ammonium perchlorate  

NASA Technical Reports Server (NTRS)

The short term effects of ammonium perchlorate on selected organisms were studied. A long term experiment was also designed to assess the changes incurred by ammonium perchlorate on the nitrogen and chloride contents of soil within a period of 3 years. In addition, an attempt was made to produce methane gas from anaerobic fermentation of the aquatic weed, Alternanthera philoxeroides.

Naqvi, S. M. Z.; Latif, A.

1975-01-01

230

Biologically active bisquaternary ammonium chlorides: physico-chemical properties of long chain amphiphiles and their evaluation as non-viral vectors for gene delivery.  

PubMed

The biological properties of bisquaternary ammonium salts, which are derivatives of N,N-bisdimethyl-1,2-ethanediamine (bis-C(n)BEC), of general formula /C(n)H(2n+1)OOCCH2(CH3)2N(+)CH2CH2N(+)(CH3)2CH2COOC(n)H(2n+1)/2Cl-, were investigated (n=10, 12, 14). The interaction with model membrane was studied by differential scanning calorimetry experiments, and the apparent adiabatic molar compressibility of their solution as a function of concentration was obtained by sound velocity measurements. Their biological activities were assayed by Electrophoresis Mobility Shift, MTT proliferation, and transient transfection. All the investigated compounds interact with the DNA and are able to transfect DNA, when they are co-formulated with DOPE, with an efficiency significantly greater than that of a standard commercial transfection reagent. Bis-C(14)BEC is the only molecule able to deliver DNA inside the cells without a helper lipid, as shown by EGFP expression, albeit with a low efficiency in comparison with a standard commercial transfection reagent. This may be due to a slightly different interaction of bis-C14BEC from bis-C10BEC and bis-C12BEC with phospholipid bilayers. Bis-C10BEC and bis-C12BEC show a slight fluidizing effect, while bis-C14BEC increases stability of both the gel and the rippled gel phases. PMID:15725392

Fisicaro, Emilia; Compari, Carlotta; Duce, Elenia; Donofrio, Gaetano; Rózycka-Roszak, Bozenna; Wo?niak, Edyta

2005-03-11

231

Liquid chromatography of hydrocarbonaeous quaternary amines on cyclodextrin bonded silica  

USGS Publications Warehouse

Mixtures of n-alkylbenzyldimethylammonium chloride (ABDAC) were resolved into homologous components by high-performance liquid chromatography (HPLC) with a cyclodextrin-bonded silica stationary phase. With a few exceptions, results from this study are similar to those obtained from traditional reversed-phase HPLC. It was found that the presence of electrolytes in aqueous mobile phases is not a critical factor in determining the success of HPLC separation. Under normal HPLC conditions, a mobile phase consisting of either methanol–water (50:50) or acetonitrile–water (30:70) was employed for obtaining adequate resolution of the quaternary ammonium mixtures. Although the percent organic modifier–water profiles were similar to those in previous studies with these compounds, resolution (R) and selectivity (?) parameters were found to be quite susceptible to changes in the mobile phase solvent composition. The retention behavior of the cationic analytes in the homologous series is consistent with the hydrophobic-interaction concept proposed for the retention mechanism via dominant inclusion complex formation. Several electrolytes were chosen for a study of the counter ion effect on the chromatographic characteristics of ABDAC components. Among the electrolytes examined, the perchlorate ion was found most likely to act as an ion-pairing counter ion for ammonium cations in the HPLC system studied. A correlation study established linear relationships between the chain length of ABDAC and the logarithmic capacity factor (k2). The analytical utility of the HPLC method was demonstrated by the analysis of various unknown mixtures.

Abidi, S.L.

1986-01-01

232

Enrichment of Polychlorinated Biphenyls from Aqueous Solutions Using Fe3O4 Grafted Multiwalled Carbon Nanotubes with Poly Dimethyl Diallyl Ammonium Chloride  

PubMed Central

In this paper, Fe3O4 nanoparticles (Fe3O4 NPs) grafted carboxyl groups of multiwalled carbon nanotubes with cationic polyelectrolyte poly (dimethyldiallylammonium chloride) (PDDA) (MWCNTs-COO?/PDDA@Fe3O4), are successfully synthesized and used for the extraction of six kinds of major toxic polychorinated biphenyls (PCBs) from a large volume of water solution. The hydrophilicity of the PDDA cage can enhance the dispersibility of sorbents in water samples, and the superparamagnetism of the Fe3O4 NPs facilitate magnetic separation which directly led to the simplification of the extraction procedure. With the magnetic solid-phase extraction (MSPE) technique based on the MWCNTs-COO?/PDDA@Fe3O4 sorbents, it requires only 30 min to extract trace levels of PCBs from 500 mL water samples. When the eluate condensed to 1.0 mL, concentration factors for PCBs became over 500. The spiked recoveries of several real water samples for PCBs were in the range of 73.3–98.9% with relative standard deviations varying from 3.8% to 9.4%, reflecting good accuracy of the method. Therefore, preconcentration of trace level of PCBs by using this MWCNTs-COO?/PDDA@Fe3O4 sorbent, which are stable for multiple reuses, from water solution can be performed. PMID:22754371

Zeng, Shaolin; Cao, Yuting; Sang, Weiguo; Li, Tianhua; Gan, Ning; Zheng, Lei

2012-01-01

233

Discovery of novel quaternary ammonium derivatives of (3R)-quinuclidinol esters as potent and long-acting muscarinic antagonists with potential for minimal systemic exposure after inhaled administration: identification of (3R)-3-{[hydroxy(di-2-thienyl)acetyl]oxy}-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane bromide (aclidinium bromide).  

PubMed

The objective of this work was to discover a novel, long-acting muscarinic M(3) antagonist for the inhaled treatment of chronic obstructive pulmonary disease (COPD), with a potentially improved risk-benefit profile compared with current antimuscarinic agents. A series of novel quaternary ammonium derivatives of (3R)-quinuclidinol esters were synthesized and evaluated. On the basis of its overall profile, (3R)-3-{[hydroxy(di-2-thienyl)acetyl]oxy}-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane bromide (aclidinium bromide) emerged as a candidate for once-daily maintenance treatment of COPD. This compound is a potent muscarinic antagonist, with long duration of action in vivo, and was found to have a rapid hydrolysis in human plasma, minimizing the potential to induce class-related systemic side effects. Aclidinium bromide is currently in phase III development for maintenance treatment of patients with COPD. PMID:19653626

Prat, María; Fernández, Dolors; Buil, M Antonia; Crespo, María I; Casals, Gaspar; Ferrer, Manuel; Tort, Laia; Castro, Jordi; Monleón, Juan M; Gavaldà, Amadeu; Miralpeix, Montserrat; Ramos, Israel; Doménech, Teresa; Vilella, Dolors; Antón, Francisca; Huerta, Josep M; Espinosa, Sonia; López, Manuel; Sentellas, Sonia; González, Marisa; Albertí, Joan; Segarra, Victor; Cárdenas, Alvaro; Beleta, Jorge; Ryder, Hamish

2009-08-27

234

75 FR 760 - Choline chloride; Exemption from the Requirement of a Tolerance  

Federal Register 2010, 2011, 2012, 2013

...positively charged quaternary hydroxyl alkylammonium ion and a negatively charged chloride ion. Choline is an essential component of the human...of view, there were no concerns for the chloride ion. It was considered to be...

2010-01-06

235

Irish Quaternary Association (IQUA)  

NSDL National Science Digital Library

The Irish Quaternary Association (IQUA) website publicizes its aim "to promote Quaternary studies in Ireland through its publications, and the organization of field meetings and conferences." Visitors can learn about the importance of quaternary studies, find out the latest news and upcoming meetings, and find links to Quaternary studies journals.

1969-12-31

236

The Alaska Quaternary Center  

NSDL National Science Digital Library

This website illustrates the Alaska Quaternary Center's (at the University of Alaska, Fairbanks) commitment "to the promotion of interdisciplinary research and the enhancement of interdisciplinary instruction in Quaternary sciences." Users can view images of the field work and learn how to obtain quaternary data from the AQC Quaternary Research Geodatabase.

1969-12-31

237

Quaternary and Geomorphology.  

ERIC Educational Resources Information Center

Highlights conferences and meetings of organizations involved with quaternary geology and geomorphology, including International Union of Quaternary Research Conference held in Moscow. The impetus of a revision of "The Quaternary of the United States" resulted from this conference. Includes activities/aims of "Friends of the Pleistocene"…

Andrews, J. T.; Graf, W. L.

1983-01-01

238

DICHLORO (5,10,15,20-TETRAPHENYLPORPHYRIN) PHOSPHORUS(V) CHLORIDE AS A NEW CATALYST FOR CONVERSION OF 1,2-EPOXYETHANES TO 2-HYDROXYETHYL THIOCYANATES WITH AMMONIUM THIOCYANATE  

Microsoft Academic Search

A convenient and efficient procedure for the cleavage of the oxirane rings with ammonium thiocyanate in the presence of phosphorus(V)tetraphenylporphyrin is described. The ring-opening of 1,2- epoxyethanes is found to proceed regioselectively under mild reaction conditions. Thus, several 2-hydroxyethyl thiocyanates, useful intermediates toward biologically active molecules, are easily obtained in very good yields.

Hashem Sharghi; Alireza Hassani Nejad

2004-01-01

239

Chloride Test  

MedlinePLUS

... is an electrolyte. It is a negatively charged ion that works with other electrolytes, such as potassium , ... which is made up of sodium and chloride ions. Most of the chloride is absorbed by the ...

240

Ammonium metabolism in humans.  

PubMed

Free ammonium ions are produced and consumed during cell metabolism. Glutamine synthetase utilizes free ammonium ions to produce glutamine in the cytosol whereas glutaminase and glutamate dehydrogenase generate free ammonium ions in the mitochondria from glutamine and glutamate, respectively. Ammonia and bicarbonate are condensed in the liver mitochondria to yield carbamoylphosphate initiating the urea cycle, the major mechanism of ammonium removal in humans. Healthy kidney produces ammonium which may be released into the systemic circulation or excreted into the urine depending predominantly on acid-base status, so that metabolic acidosis increases urinary ammonium excretion while metabolic alkalosis induces the opposite effect. Brain and skeletal muscle neither remove nor produce ammonium in normal conditions, but they are able to seize ammonium during hyperammonemia, releasing glutamine. Ammonia in gas phase has been detected in exhaled breath and skin, denoting that these organs may participate in nitrogen elimination. Ammonium homeostasis is profoundly altered in liver failure resulting in hyperammonemia due to the deficient ammonium clearance by the diseased liver and to the development of portal collateral circulation that diverts portal blood with high ammonium content to the systemic blood stream. Although blood ammonium concentration is usually elevated in liver disease, a substantial role of ammonium causing hepatic encephalopathy has not been demonstrated in human clinical studies. Hyperammonemia is also produced in urea cycle disorders and other situations leading to either defective ammonium removal or overproduction of ammonium that overcomes liver clearance capacity. Most diseases resulting in hyperammonemia and cerebral edema are preceded by hyperventilation and respiratory alkalosis of unclear origin that may be caused by the intracellular acidosis occurring in these conditions. PMID:22921946

Adeva, Maria M; Souto, Gema; Blanco, Natalia; Donapetry, Cristóbal

2012-11-01

241

Quaternary Research Association  

NSDL National Science Digital Library

The Quaternary Research Association explains that it "exists to promote understanding of the Quaternary Period by publishing field guides, technical guides, and an international journal as well as holding field meetings and speaker meetings." Students and researchers can discover employment, research, grant, meetings, and educational opportunities.

242

Listeria monocytogenes strains selected on ciprofloxacin or the disinfectant benzalkonium chloride exhibit reduced susceptibility to ciprofloxacin, gentamicin, benzalkonium chloride, and other toxic compounds.  

PubMed

Listeria monocytogenes is a leading agent for severe food-borne illness and death in the United States and other nations. Even though drug resistance has not yet threatened therapeutic interventions for listeriosis, selective pressure associated with exposure to antibiotics and disinfectants may result in reduced susceptibility to these agents. In this study, selection of several L. monocytogenes strains on either ciprofloxacin (2 ?g/ml) or the quaternary ammonium disinfectant benzalkonium chloride (BC; 10 ?g/ml) led to derivatives with increased MICs not only to these agents but also to several other toxic compounds, including gentamicin, the dye ethidium bromide, and the chemotherapeutic drug tetraphenylphosphonium chloride. The spectrum of compounds to which these derivatives exhibited reduced susceptibility was the same regardless of whether they were selected on ciprofloxacin or on BC. Inclusion of strains harboring the large plasmid pLM80 revealed that MICs to ciprofloxacin and gentamicin did not differ between the parental and plasmid-cured strains. However, ciprofloxacin-selected derivatives of pLM80-harboring strains had higher MICs than those derived from the plasmid-cured strains. Susceptibility to the antimicrobials was partially restored in the presence of the potent efflux inhibitor reserpine. Taken together, these data suggest that mutations in efflux systems are responsible for the multidrug resistance phenotype of strains selected on ciprofloxacin or BC. PMID:22003016

Rakic-Martinez, Mira; Drevets, Douglas A; Dutta, Vikrant; Katic, Vera; Kathariou, Sophia

2011-12-01

243

DEMONSTRATION OF TWO STABLE POTENTIAL STATES IN THE SQUID GIANT AXON UNDER TETRAETHYLAMMONIUM CHLORIDE  

Microsoft Academic Search

During the course of experiments designed to investigate the effects of various chemicals injected into squid giant axons (2), it was found that quater- nary ammonium ions are capable of prolonging the duration of the action potential without affecting the properties of the resting membrane appreciably. A similar effect of quaternary ammonium ions upon the action potential of other excitable

ICHIJI TASAKI; SUSUMU HAGIWARA

1957-01-01

244

International Union for Quaternary Research  

NSDL National Science Digital Library

The International Union for Quaternary Research (INQUA) discusses quaternary scientists' investigations "to interpret the changing world of the glacial ages and their impact on our planet's surface environments.". Researchers can find out about INQUA-funded projects, meetings, scientific commissions, and INQUA's two publicaions, Quaternary International, and Quaternary Perspectives.

1969-12-31

245

Quaternary Ammonium Polysaccharides for Gene Delivery Ira Yudovin-Farber,  

E-print Network

using cell electroporation, microinjection of DNA, and incorporation of the gene by viruses (2) and synthetic vectors (3). Viral vectors includ- ing retroviruses, adenoviruses, and adeno-associated viruses

Linial, Michal

246

Measuring quaternary ammonium cleaning agents with ion selective electrodes  

Microsoft Academic Search

Data for coated-wire, ion selective electrodes (ISEs) are presented for cationic surfactant ions found in common cleaners including benzyldimethyltetradecylammonium, benzyldimethyldodecylammonium, and benzyldimethylhexadecylammonium. The ion exchangers dinonylnaphthalene sulfonic acid, tetraphenyborate, and tetrakis(4-chlorophenyl)borate are examined, showing dinonylnaphthalene sulfonic acid to be the favored species. The ISEs exhibit approximately Nernstian behavior down to the 10?6M limit of detection with lifetimes in excess of

Michael A. Plesha; Bernard J. Van Wie; James M. Mullin; David A. Kidwell

2006-01-01

247

Cesium Chloride  

MedlinePLUS

... effect on tumors. A few people have had life-threatening problems with heart rhythm, seizures, loss of consciousness, and electrolyte (blood chemistry) imbalances after taking cesium chloride. How is it ...

248

Does metallic ammonium exist  

NASA Technical Reports Server (NTRS)

A description is given of calculations which demonstrate that metallic ammonium, at least in the form envisaged by Ramsey (1951), is unstable at all pressures. On the basis of the computational results it is concluded that monovalent metallic ammonium is never the thermodynamically favored phase for an NH3-1/2H2 mixture.

Stevenson, D. J.

1975-01-01

249

Competition between counterions and active protein sites to bind bisquaternary ammonium groups. A combined mass spectrometry and quantum chemistry model study  

NASA Astrophysics Data System (ADS)

A model study of the interaction between biologically active bisquaternary ammonium salts and their molecular targets in living systems is urgently needed to elucidate the molecular mechanisms involved in the interactions between these compounds. To address this need a combined experimental-computational study of the interaction of two tetramethylammonium cations (modeling two quaternary groups) with the chlorine anion and with the deprotonated 2,5-dihydroxybenzoic acid (modeling a carboxylic group and an aromatic ring of side radicals of proteins) has been performed. Fast atom bombardment mass spectrometry method and DFT/B3LYP/6-31++G** and MP2/6-31++G** calculations have been employed in the study. Stable noncovalent complexes with different ratios of the tetramethylammonium cations and chlorine anions or deprotonated 2,5-dihydroxybenzoic acid anions were registered in the mass spectra of tetramethylammonium chloride and 2,5-dihydroxybenzoic acid mixture. This finding shows that the organic and inorganic anions compete to bind tetramethylammonium in the studied system. The theoretically determined stabilities of the noncovalent complexes were compared with the relative stabilities evaluated from the mass spectrometric measurements. The results of the study allow us to elucidate the competing interactions that exist between quaternary groups with inorganic counterions or with active groups of molecular protein targets.

Pashynska, V.; Boryak, O.; Kosevich, M. V.; Stepanian, S.; Adamowicz, L.

2010-06-01

250

Ammonium and sulfate ion release of histamine from lung fragments.  

PubMed

In vitro studies with guinea pig lung fragments incubated with 10- to 200-mM concentrations of ammonium ion demonstrated the release of substanial quantities of histamine. Of the anions tested with ammonium ion, sulfate was the most potent, while nitrate and acetate ions were of intermediate potency and chloride was less potent. An osmotic effect is unlikely since equal concentrations of sodium chloride failed to release histamine. Isoproterenol, known to decrease anaphylactic histamine release, and acetycholine, known to increase histamine release, had no effect on the ammonium sulfate-mediated release of histamine. N-6 2'-O-Dibutyryladenosine 3',5' monophosphate (dibutyryl c-AMP) was also ineffective. These studies suggest that the inhalation irritation associated with certain sulfate and other salts, may be a function of their ability to release histamine in the presence of amonium ion. PMID:49176

Charles, J M; Menzel, D B

1975-06-01

251

Noncovalent Complexation of Monoamine Neurotransmitters and Related Ammonium Ions by Tetramethoxy Tetraglucosylcalix[4]arene  

NASA Astrophysics Data System (ADS)

The noncovalent complexation of monoamine neurotransmitters and related ammonium and quaternary ammonium ions by a conformationally flexible tetramethoxy glucosylcalix[4]arene was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The glucosylcalixarene exhibited highest binding affinity towards serotonin, norepinephrine, epinephrine, and dopamine. Structural properties of the guests, such as the number, location, and type of hydrogen bonding groups, length of the alkyl spacer between the ammonium head-group and the aromatic ring structure, and the degree of nitrogen substitution affected the complexation. Competition experiments and guest-exchange reactions indicated that the hydroxyl groups of guests participate in intermolecular hydrogen bonding with the glucocalixarene.

Torvinen, Mika; Kalenius, Elina; Sansone, Francesco; Casnati, Alessandro; Jänis, Janne

2012-02-01

252

Interaction of supercritical CO 2 with alkyl-ammonium organoclays: Changes in morphology  

Microsoft Academic Search

This paper investigates the influence of supercritical carbon dioxide on the morphology and surface chemistry of three organic modified montmorillonite species. Alkyl based quaternary ammonium surfactants with differing numbers of chains attached, were chosen to vary the degree of CO2-philicity exhibited by the organoclay. In a high pressure batch vessel, the different organoclays were suspended in the supercritical solvent at

M. R. Thompson; J. Liu; H. Krump; L. K. Kostanski; P. D. Fasulo; W. R. Rodgers

2008-01-01

253

Ammonium sulfide organosolv pulping  

Microsoft Academic Search

The use of ammonium sulfide in aqueous ethanol and methanol was investigated for pulping of wood. Hemlock chips required 21% ammonium sulfide (equivalent to 19% Na2O) at 180°C to become delignified to the kappa range 35–50. The yields exceeded those of conventional kraft pulps by 14% on dry wood basis. Over 75% of the original glucomannan was recovered in the

V. L. Chiang; K. V. Sarkanen

1983-01-01

254

Molecular Structure of Ammonium ion  

NSDL National Science Digital Library

The first widespread production of ammonium compounds occurred during the 1890s when ammonium sulfate was produced as a by-product from coke oven gas. Ammonium ion is produced as a product of the reaction of water and ammonia. Often, ammonium salts are isomorphous. They have a similar solubility to potassium and rubidium salts, whose ions are similar in size to ammonium. The ion is most stable in the presence of a large compound with a single negative charge.

2002-09-10

255

Quaternary Faunal Environments  

NSDL National Science Digital Library

Students collect information the environments associated with a list of presently living mammals. Students use FAUNMAP to explore the spatial patterns associated with these living mammals during the late Quaternary. They compare these distributions for living mammals to the distribution patterns for a set of extinct mammals. Students answer a set of questions that provide a basis for a summary report.

Christopher Hill

256

Effect of Intra-articular 4-(S)-amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2H-4-pyranylcarbonyl} piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride (MEN16132), a kinin B2 receptor antagonist, on nociceptive response in monosodium iodoacetate-induced experimental osteoarthritis in rats.  

PubMed

The present study was designed to investigate the role of bradykinin (BK) in the knee joint osteoarthritis induced by intra-articular (i.ar.) administration of monosodium iodoacetate (MIA) in the rat, and to determine the efficacy of the kinin B(2) receptor antagonists, 4-(S)-amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2H-4-pyranylcarbonyl} piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride (MEN16132) and icatibant, in reducing pain. Rats received MIA (1 mg/25 microl i.ar.) in the right knee. MEN16132, icatibant (1, 3, and 10 microg/25 microl i.ar.), or saline were administered 7 days after MIA treatment, and their antinociceptive effect was observed for 2 weeks. MEN16132 induced a marked and sustained reduction of incapacitation produced by MIA, approximately 56% inhibition of pain at 3 microg/knee. MEN16132 analgesia was more potent and longer lasting, up to 10 days, than icatibant. MEN16132 (3 microg/knee), at different time points from MIA treatment in separate groups of animals, produced comparable maximal antinociceptive effects, whereas the pain response induced by MIA was unaffected if MEN16132 (10 microg/knee) was administered in the contralateral knee. Indomethacin at high doses (100-625 microg/knee) inhibited by approximately 40% but with a short duration the MIA-induced pain. MIA treatment produced a significant increase of BK and prostaglandin E(2) (PGE(2)) metabolite levels in synovial fluid up to 21 days, and PGE(2) metabolite levels were reduced almost to basal values by MEN16132. In conclusion the potent and long-lasting analgesic effect of MEN16132 in MIA-induced osteoarthritis indicates an important role for BK in osteoarthritic pain, and suggests that MEN16132 can be a candidate for the treatment of this chronic disease. PMID:19745108

Cialdai, Cecilia; Giuliani, Sandro; Valenti, Claudio; Tramontana, Manuela; Maggi, Carlo Alberto

2009-12-01

257

70. INTERIOR VIEW OF AMMONIUM NITRATE HOUSE, LOOKING AT AMMONIUM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

70. INTERIOR VIEW OF AMMONIUM NITRATE HOUSE, LOOKING AT AMMONIUM NITRATE IN STORAGE. APRIL 18, 1919. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

258

The toxicity of ammonia/ammonium to the vermifiltration wastewater treatment process.  

PubMed

This study was undertaken to assess the toxicity of ammonia/ammonium to key species within the vermifiltration process. The key species, the earthworm Eisenia fetida, was subjected to a series of tests in solid phase mesocosms and full-scale units. The solid phase tests showed a relatively low toxicity to ammonium with ammonium chloride having an LC50 for ammonium of 1.49 g/kg. Ammonium sulfate did not show an effect on mortality at 2 g/kg ammonium. The full-scale units showed that ammonia hydroxide can change the pH and concentration of ammonia in wastewater and while it caused some mortality to the worms its overall affect on system functioning was minimal with no significant difference in terms of worm survival found between treatments. The affect on nitrifying bacteria was also minimal with no linear trend shown with ammonia concentration. PMID:18845859

Hughes, R J; Nair, J; Ho, G

2008-01-01

259

Contamination of Ammonium-Based Nutrient Solutions by Nitrifying Organisms and the Conversion of Ammonium to Nitrate.  

PubMed

Conversion of ammonium to nitrate and contamination by nitrifying organisms are often assumed not to be significant in ammonium-based nutrient solutions. To assess this assumption, maize (Zea mays) and pea (Pisum sativum) were grown under greenhouse conditions in aeroponic, hydroponic, and sand-culture systems containing 2 mM ammonium chloride as the sole nitrogen source and evaluated for the activity of contaminating nitrifying organisms. In all three culture systems, root colonization by nitrifying organisms was detected within 5 d, and nitrate was detected in the nutrient solution within 10 d after seedling transfer. In sand culture, solution nitrate concentration reached 0.35 mM by the end of the 17-d experiment. Consistent with the microbial ammonium oxidation sequence, nitrite was detected earlier than nitrate and remained at lower levels throughout the experiment. Nitrate was found in significant quantities in root and shoot tissues from seedlings grown in ammonium-based nutrient solutions in all of the solution culture systems. Maize seedlings grown in an ammonium-based hydroponic system contained nitrate concentrations at 40% of that found in plants grown in nitrate-based solution. Determination of nitrate (or nitrite) levels in the nutrient solution was the weakest indicator of the activity of nitrifying organisms. A bioassay for the presence of nitrifying organisms in combination with tissue analysis for nitrate was a better indicator of microbial conversion of ammonium to nitrate in nutrient solution culture. The results have implications for the use of ammonium-based nutrient solutions to obtain plants suitable for research on induction of nitrate uptake and reduction or for research using solution culture to compare ammonium versus nitrate fertilization. PMID:12231673

Padgett, P. E.; Leonard, R. T.

1993-01-01

260

Effect of benzalkonium chloride on percutaneous absoption of antisense phosphorothioate oligonucleotides  

Microsoft Academic Search

The effect of benzalkonium chloride on skin permeability of partially modified antisense phosphorothioate oligonucleotides\\u000a (PS-ODN), which are designed as scar formation inhibitor, was investigated using Franz Diffusion Cell. When the concentration\\u000a ratio of PS-ODN-quarternary ammonium salt complex is more than 1?100, the apparent partition coefficient (APC) of each complex\\u000a was increased in the following order; tetraphenyl phosphonium chloride (TPP)ammonium

Young Mi Lee; Sung Hee Lee; Geon Il Ko; Jae Baek Kim; Dong Hwan Sohn

1996-01-01

261

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2014-10-01

262

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2011 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2011-10-01

263

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2013 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2013-10-01

264

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2012 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2012-10-01

265

Experimental study of directional solidification of aqueous ammonium chloride solution  

NASA Technical Reports Server (NTRS)

Directional solidification experiments have been carried out using the analog casting system of NH4Cl-H2O solution by cooling it from below with a constant-temperature surface ranging from -31.5 C to +11.9 C. The NH4Cl concentration was 26 percent in all solutions, with a liquidus temperature of 15 C. It was found that finger convection occurred in the fluid region just above the mushy layer in all experiments. Plume convection with associated chimneys in the mush occurred in experiments with bottom temperatures as high as +11.0 C. However, when the bottom temperature was raised to +11.9 C, no plume convection was observed, although finger convection continued as usual. A method has been devised to determine the porosity of the mush by computed tomography. Using the mean value of the porosity across the mush layer and the permeability calculated by the Kozeny-Carman relationship, the critical solute Rayleigh number across the mush layer for onset of plume convection was estimated to be between 200 and 250.

Chen, C. F.; Chen, Falin

1991-01-01

266

Steady-state solidification of aqueous ammonium chloride  

NASA Astrophysics Data System (ADS)

We report on a series of experiments in which a Hele-Shaw cell containing aqueous solutions of NH4Cl was translated at prescribed rates through a steady temperature gradient. The salt formed the primary solid phase of a mushy layer as the solution solidified, with the salt-depleted residual fluid driving buoyancy-driven convection and the development of chimneys in the mushy layer. Depending on the operating conditions, several morphological transitions occurred. A regime diagram is presented quantifying these transitions as a function of freezing rate and the initial concentration of the solution. In general, for a given concentration, increasing the freezing rate caused the steady-state system to change from a convecting mushy layer with chimneys to a non-convecting mushy layer below a relatively quiescent liquid, and then to a much thinner mushy layer separated from the liquid by a region of active secondary nucleation. At higher initial concentrations the second of these states did not occur. At lower concentrations, but still above the eutectic, the mushy layer disappeared. A simple mathematical model of the system is developed which compares well with the experimental measurements of the intermediate, non-convecting state and serves as a benchmark against which to understand some of the effects of convection. Movies are available with the online version of the paper.

Peppin, S. S. L.; Huppert, Herbert E.; Worster, M. Grae

267

The shape of ammonium chloride dendrite tips at small supersaturation  

NASA Astrophysics Data System (ADS)

We report detailed measurements of the tip shapes of three-dimensional NH_4Cl dendrites grown from aqueous solution at small supersaturation.[1] We compare three different models for determining the tip position and shape: parabolic, parabolic with a fourth-order correction, and power law[2]. We also consider an intensity centroid method[3] useful for locating tip positions even when the tip is too small to image accurately. None of these methods is ideal, but the fourth-order fit appears to provide the most robust description of both the tip shape and position for the crystals grown in this work. Since all models considered include data a finite distance back from the tip, the question of whether incipient sidebranches contaminate the computed tip position and shape will be considered when looking for possible tip oscillations. 1. More details and references are available at http://www.lafayette.edu/%7Edoughera/talks/aps2003/index.html 2. U. Bisang and J. H. Bilgram, Phys. Rev. E 54, 5309 (1996). 3. J. C. LaCombe et al., Phys. Rev. E 65, 031604 (2002).

Dougherty, Andrew; Lahiri, Mayank

2003-03-01

268

Sidebranching in the Dendritic Crystal Growth of Ammonium Chloride  

NASA Astrophysics Data System (ADS)

We report new measurements of the dendritic crystal growth of NH4Cl from supersaturated aqueous solution. We report the first measurement of the capillary length d0 to be approximately 2 x10-4 ?m. For growth at small dimensionless supersaturations ? on the order of 0.005, we have estimated the stability constant &*circ; to be approximately 0.008. The origin of the sidebranches in dendritic growth is not fully understood, but one model is that they result from the selective amplification of microscopic noise. We will compare measurements of the sidebranch envelope with predictions of the noise-induced sidebranching model of Gonz'alez-Cinca, Ram'irez-Piscina, Casademunt, and Hern'andez-Machado [Phys Rev. E, 63, 051602 (2001)]. A second model is that sidebranches result from small oscillations of the tip. We have observed no such oscillations, but very small ones can not be ruled out. Given the finite experimental resolution, no measurement of the tip region can be completely free of contamination from early sidebranches. We will discuss this and other experimental challenges that need to be overcome before we can understand the origin of sidebranches.

Dougherty, Andrew; Stinner, Franklin

2010-03-01

269

Sidebranching in the Dendritic Crystal Growth of Ammonium Chloride  

NASA Astrophysics Data System (ADS)

We report measurements of the dendritic crystal growth of NH4Cl from supersaturated aqueous solution at small supersaturations. Sidebranch growth in this regime is challenging to model well, and the origin of the sidebranches is not fully understood. The early detection of sidebranches requires measurements of small deviations from the smooth steady state shape, but that shape is not well known at the intermediate distances relevant for sidebranch measurements. One model is that sidebranches result from the selective amplification of microscopic noise. We compare measurements of the sidebranch envelope with predictions of the noise-induced sidebranching model of Gonz'alez-Cinca, Ram'irez-Piscina, Casademunt, and Hern'andez-Machado [Phys Rev. E, 63, 051602 (2001)]. We find that the measured amplitude is somewhat larger than predicted, and the shape of the sidebranch envelope is also different. A second model is that sidebranches result from small oscillations of the tip. We have observed no such oscillations, but very small ones can not be ruled out. No measurement of the tip region can be completely free of contamination from early sidebranches, so it can be challenging to distinguish between an oscillating tip and a smooth tip with sidebranches starting nearby.

Dougherty, Andrew

2012-02-01

270

Ammonium Homeostasis and Human Rhesus Glycoproteins  

Microsoft Academic Search

The brain ammonium production is detoxified by astrocytes, the gut ammonium production is detoxified by hepatic cells, and the renal ammonium production plays a major role in renal acid excretion. As a result of ammonium handling in these organs, the ammonium and pH values are strictly regulated in plasma. Up until recently, it was accepted that mammalian cell transmembrane ammonium

Gabrielle Planelles

2007-01-01

271

Quaternary Research Association Educational Resources  

NSDL National Science Digital Library

The Quaternary Research Association (QRA) is an organization comprising archaeologists, botanists, civil engineers, geographers, geologists, soil scientists, zoologists and others interested in research into the problems of the Quaternary. This site describes their activities and organization. This direct link to the educational teaching resources provides access to glacier and glaciation resources.

272

Topic in Depth - Quaternary Studies  

NSDL National Science Digital Library

Quaternary Studies examines the geologic period of the Quaternary, the last two million years up to the present day. Glaciers formed and receded; animals evolved and went extinct. Here, visitors can learn all about current research and education initiatives in this field of stratigraphic geology.

2010-09-14

273

Solubility of sodium salts in ammonium-based deep eutectic solvents  

Microsoft Academic Search

The solubility of sodium chloride (NaCl), sodium bromide (NaBr), and sodium carbonate (Na2CO3) was measured in nine ammonium-based deep eutectic solvents (DESs). The aim of the study is to assess the potential use of these DESs as solvents and electrolytes for the separation of sodium metal from its salts. The studied DESs were prepared by combining ammonium salts with various

F. S. Ghareh Bagh; F. S. Mjalli; M. A. Hashim; M. K. O. Hadj-Kali; I. M. Alnashef

2013-01-01

274

Exploring factors controlling the thermal behavior of ammonium perchlorate and ammonium nitrate energetic systems.  

E-print Network

??This research project characterizes ammonium nitrate (AN) and ammonium perchlorate (AP) to assist in the parameter optimization of ammonium-salt propellants. Throughout these studies, the effective… (more)

Lang, Anthony J.

2009-01-01

275

Quaternary GIS Laboratory  

NSDL National Science Digital Library

This is the home page of the Quaternary Geographic Information System (GIS) Laboratory at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado. The laboratory supports quantitative spatial analysis of glacier, climate, coastal, and other environmental relationships at high latitudes. Users can access a collection of climate animations for the State of Alaska which show seasonal variation in monthly temperature and precipitation. There is also a set of high-resolution imagery and terrain models for Barrow, Alaska, an animation of the land bridge between Asia and North America, an atlas of paleoglaciation for the state, and links to a variety of other projects involving climatology, paleoclimatology, and glacial geomorphology in the Sate of Alaska.

276

Paleosols in central Illinois as potential sources of ammonium in groundwater  

USGS Publications Warehouse

Glacially buried paleosols of pre-Holocene age were evaluated as potential sources for anomalously large concentrations of ammonium in groundwater in East Central Illinois. Ammonium has been detected at concentrations that are problematic to water treatment facilities (greater than 2.0 mg/L) in this region. Paleosols characterized for this study were of Quaternary age, specifically Robein Silt samples. Paleosol samples displayed significant capacity to both store and release ammonium through experiments measuring processes of sorption, ion exchange, and weathering. Bacteria and fungi within paleosols may significantly facilitate the leaching of ammonium into groundwater by the processes of assimilation and mineralization. Bacterial genetic material (DNA) was successfully extracted from the Robein Silt, purified, and amplified by polymerase chain reaction to produce 16S rRNA terminal restriction fragment length polymorphism (TRFLP) community analyses. The Robein Silt was found to have established diverse and viable bacterial communities. 16S rRNA TRFLP comparisons to well-known bacterial species yielded possible matches with facultative chemolithotrophs, cellulose consumers, nitrate reducers, and actinomycetes. It was concluded that the Robein Silt is both a source and reservoir for groundwater ammonium. Therefore, the occurrence of relatively large concentrations of ammonium in groundwater monitoring data may not necessarily be an indication of only anthropogenic contamination. The results of this study, however, need to be placed in a hydrological context to better understand whether paleosols can be a significant source of ammonium to drinking water supplies. ?? 2009 National Ground Water Association.

Glessner, J.J.G.; Roy, W.R.

2009-01-01

277

49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410...Materials § 176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a)...

2013-10-01

278

Quantitative determination of benzalkonium chloride in treated wood by solid-phase extraction followed by liquid chromatography with ultraviolet detection.  

PubMed

Ammoniacal copper quat (ACQ) compound wood preservative is comprised of copper and quaternary ammonium compounds with benzalkonium chloride (BAC) as the active ingredient. Solid-phase extraction (SPE) followed by liquid chromatography with ultraviolet detection (LC-UV) was developed for quantitative determination of BAC in treated wood. Five species of wood were used, Japanese cedar (Cryptomeria japonica), Japanese larch (Larix leptolepis), Yezo spruce (Picea jezoensis), Sakhalin fir (Abies sachalinensis), and western hemlock (Tsuga heterophylla). BAC used in the present study was composed of 66% C12, 33% C14 and less than 1% C16. BAC was added to each wood species (500 mg) then extracted with HCl-ethanol (20 ml) and quantitatively determined with LC-UV (262 nm). Wood extractives from the heartwood of each species, except western hemlock, interfered with quantitative determination of BAC, but SPE with an Oasis MCX cartridge was effective in preventing this. Using the present methods, BAC homologue peaks were clearly confirmed without interference. Recoveries from wood ranged from 92 to 101% and the limit of quantitation was approximately 240 microg/g wood for the C12 and C14 homologues. PMID:16275285

Miyauchi, Teruhisa; Mori, Mitsunori; Ito, Katsuhiko

2005-11-18

279

Long-term exposure to benzalkonium chloride disinfectants results in change of microbial community structure and increased antimicrobial resistance.  

PubMed

The effect of benzalkonium chlorides (BACs), a widely used class of quaternary ammonium disinfectants, on microbial community structure and antimicrobial resistance was investigated using three aerobic microbial communities: BACs-unexposed (DP, fed a mixture of dextrin/peptone), BACs-exposed (DPB, fed a mixture of dextrin/peptone and BACs), and BACs-enriched (B, fed only BACs). Long-term exposure to BACs reduced community diversity and resulted in the enrichment of BAC-resistant species, predominantly Pseudomonas species. Exposure of the two microbial communities to BACs significantly decreased their susceptibility to BACs as well as three clinically relevant antibiotics (penicillin G, tetracycline, ciprofloxacin). Increased resistance to BACs and penicillin G of the two BACs-exposed communities is predominantly attributed to degradation or transformation of these compounds, whereas resistance to tetracycline and ciprofloxacin is largely due to the activity of efflux pumps. Quantification of several key multidrug resistance genes showed a much higher number of copies of these genes in the DPB and B microbial communities compared to the DP community. Collectively, our findings indicate that exposure of a microbial community to BACs results in increased antibiotic resistance, which has important implications for both human and environmental health. PMID:23924280

Tandukar, Madan; Oh, Seungdae; Tezel, Ulas; Konstantinidis, Konstantinos T; Pavlostathis, Spyros G

2013-09-01

280

Prolonged exposure of mixed aerobic cultures to low temperature and benzalkonium chloride affect the rate and extent of nitrification.  

PubMed

The combined effect of benzalkonium chloride (BAC) and prolonged exposure to low temperature on nitrification was investigated. Ammonia oxidation at 22-24°C by an enriched nitrifying culture was inhibited at increasing BAC concentrations and ceased at 15mg BAC/L. The non-competitive inhibition coefficient was 1.5±0.9mg BAC/L. Nitrification tests were conducted without and with BAC at 5mg/L using an aerobic, mixed heterotrophic/nitrifying culture maintained at a temperature range of 24-10°C. Maintaining this culture at 10°C for over one month in the absence of BAC, resulted in slower nitrification kinetics compared to those measured when the culture was first exposed to 10°C. BAC was degraded by the heterotrophic population, but its degradation rate decreased significantly as the culture temperature decreased to 10°C. These results confirm the negative impact of quaternary ammonium compounds on the nitrification process, which is further exacerbated by prolonged, low temperature conditions. PMID:25544497

Yang, Jeongwoo; Tezel, Ulas; Li, Kexun; Pavlostathis, Spyros G

2015-03-01

281

21 CFR 582.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Ammonium carbonate. 582.1137 Section 582.1137...General Purpose Food Additives § 582.1137 Ammonium carbonate. (a) Product. Ammonium carbonate. (b) Conditions of use....

2010-04-01

282

21 CFR 582.1139 - Ammonium hydroxide.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Ammonium hydroxide. 582.1139 Section 582.1139...General Purpose Food Additives § 582.1139 Ammonium hydroxide. (a) Product. Ammonium hydroxide. (b) Conditions of use....

2010-04-01

283

21 CFR 556.375 - Maduramicin ammonium.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Maduramicin ammonium. 556.375 Section 556.375 ...Animal Drugs § 556.375 Maduramicin ammonium. A tolerance is established for residues of maduramicin ammonium in chickens as follows: (a) A...

2010-04-01

284

76 FR 47238 - Ammonium Nitrate From Russia  

Federal Register 2010, 2011, 2012, 2013

...731-TA-856; Second Review] Ammonium Nitrate From Russia Determination On...the antidumping duty order on ammonium nitrate from Russia would be likely...4249 (August 2011), entitled Ammonium Nitrate from Russia:...

2011-08-04

285

76 FR 11273 - Ammonium Nitrate From Russia  

Federal Register 2010, 2011, 2012, 2013

...731-TA-856 (Second Review)] Ammonium Nitrate From Russia AGENCY: United...the suspended investigation on ammonium nitrate from Russia...the suspended investigation on ammonium nitrate from Russia would be...

2011-03-01

286

76 FR 70366 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013

...NPRM for the Ammonium Nitrate Security Program. The agenda for the public...Department's Ammonium Nitrate Security Program Web site, at http://www.dhs...programs/ammonium-nitrate-security-program.shtm. This...

2011-11-14

287

76 FR 62311 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013

...NPRM) for the Ammonium Nitrate Security Program. The agenda for the public...Department's Ammonium Nitrate Security Program Web site in mid-October at http...programs/ammonium-nitrate-security-program.shtm. Each...

2011-10-07

288

Microwave Decomposition of Solid Crystalline Ammonium Paratungstate and Ammonium Metatungstate  

NASA Astrophysics Data System (ADS)

The potential for microwave decomposition of solid crystalline ammonium paratungstate (APT) and ammonium metatungstate (AMT) was investigated. It was observed that APT and AMT interact with 2.45-GHz microwave radiation. Samples of ammonium paratungstate (20-50 g) were successfully converted into WO 3- x (0 ? x ? 0.2). A wide variety of morphological parameters were found. The interaction of AMT with the 2.45-GHz microwave radiation resulted in the partial loss of crystalline water and the partial dissolution of the sample in the released water.

Pfeifer, J.; Badaljan, E. G.; Tekula-Buxbaum, P.; Vadasdi, K.

1993-08-01

289

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

290

A novel poly(2,6-dimethyl-1,4-phenylene oxide) with trifunctional ammonium moieties for alkaline anion exchange membranes.  

PubMed

2,4,6-Tri(dimethylaminomethyl)-phenol was synthesized as a trifunctional moiety and incorporated onto poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) to obtain a novel quaternary ammonium functionalized PPO (PPO-TQA). Membranes of the polymer were fabricated and exhibited high conductivity, a low swelling ratio and water uptake. PMID:24487653

Li, Qing; Liu, Lei; Miao, Qingqing; Jin, Bangkun; Bai, Ruke

2014-03-14

291

A novel ammonium based eutectic solvent for the treatment of free fatty acid and synthesis of biodiesel fuel  

Microsoft Academic Search

In this work, low grade crude palm oil (LGCPO) with high free fatty acids (FFA) content is introduced as a possible biodiesel production feedstock alternative. The pre-treatment of LGCPO was conducted using ammonium-based deep eutectic solvent which consisted of hydrogen bond donor (i.e. p-toluenesulfonic acid monohydrate) (PTSA) and salt (i.e. N,N-diethylenethanol ammonium chloride) as a novel recyclable catalyst (DEAC-DES). The

A. Hayyan; M. A. Hashim; M. Hayyan; F. S. Mjalli; I. M. AlNashef

2013-01-01

292

High Affinity Ammonium Transporters: Molecular Mechanism of Action  

PubMed Central

The importance of the family of high affinity ammonium transporters is demonstrated by the presence of these proteins in all domains of life, including bacteria, archaea, fungi, plants, and humans. The majority of the proteins that have been studied from this family show high affinity and selectivity for ammonium, are impermeable to alkaline cations, saturate rapidly at low millimolar concentrations and most of them, are also permeable to methylammonium. Crystallization of homologue proteins from bacteria and archaea has demonstrated that the functional entity corresponds to a trimer, with each monomer maintaining a conductive pore. Through molecular modeling, it has been demonstrated that even though the identity of the proteins between bacteria/archaea with those from plants is below 25%, the latter seem to maintain similar tertiary and quaternary structures, an observation that has helped to address the functionality of conserved residues by means of mutational analysis. Results have shown that changes in the extracellular binding site of some plant transporters may result in their inhibition or reduction in transport activity, while in Escherichia coli, dissimilar replacements like Phe/Ala or Ser/Leu that eliminate possible ?-interactions or H-bonds with ammonium, respectively, lead to more active transporters. Active mutants with changes in the pair of conserved His in the center of the transporter suggest these residues are dispensable. Additional mutations have identified other important amino acids, both in the entrance of the pore and in cytoplasmic loops. Regulation of this family of transporters can be achieved by interactions of the C-terminal with cytoplasmic loops within the same monomer, or with a neighbor in the trimer. Depending on the interacting residues, these contacts may lead to the activation or inhibition of the protein. The aim of this review is to critically evaluate the newest findings on the role of the proposed amino acids that structure the ammonium pathway, as well as highlight the importance of additional residues that have been identified through mutational analyses. PMID:22645581

Pantoja, Omar

2012-01-01

293

Treatment of ammonium-rich swine waste in modified porphyritic andesite fixed-bed anaerobic bioreactor.  

PubMed

In this study, a modified porphyritic andesite (WRS) was developed as ammonium adsorbent and bed material for the anaerobic digestion of ammonium-rich swine waste. The performance in bioreactors with modified WRS, natural WRS, calcium chloride and no additives was investigated. The bioreactor with modified WRS exhibited the best performance, with start-up time on the 7th day, methane yield of 359.71 ml/g-VS, and COD removal of 67.99% during all 44 days of the experiment at 35°C. The effective ammonium adsorption and essential ions dissociation for microorganisms by modified WRS, as well as the immobilization of microbial on the surface of the modified WRS play a great role on the high efficiency anaerobic digestion of ammonium-rich swine waste. PMID:22366608

Wang, Qinghong; Yang, Yingnan; Li, Dawei; Feng, Chuanping; Zhang, Zhenya

2012-05-01

294

Pollution vulnerability of the Quaternary aquifer near Cairo, Egypt, as indicated by isotopes and hydrochemistry  

Microsoft Academic Search

.   The present study was conducted to delineate the pollution vulnerability of the Quaternary aquifer in two areas, Imbaba and\\u000a Shobra El-Khima, near Cairo, Egypt. Environmental isotopes combined with hydrochemistry were used for this purpose. The groundwater\\u000a in the Imbaba area (average total dissolved solids about 900 mg\\/L; sodium\\/chloride, sulfate, and bicarbonate water types)\\u000a is more mineralized than groundwater in the

M. A. Sadek; Abd S. El-Samie

2001-01-01

295

Ammonium transport in the kidney.  

PubMed

Ammonium excretion into the urine is the main mechanism of renal acid excretion. Ammonium is produced by epithelial cells of the proximal tubule and then secreted into the luminal fluid. However, before its final excretion into urine, ammonium ion is reabsorbed by the thick ascending limb (TAL), and accumulated in the interstitium to build up a corticopapillary gradient of ammonium which is necessary for the final diffusion of the gas NH3 in parallel to active proton secretion. Recent evidence has been provided by the study of several mouse models of renal acidosis. Particularly, it has been shown that the Na+/H+ exchanger NHE4 is a critical step of ammonium absorption by the TAL, and also that NH3 diffusion across the membrane of collecting duct cells requires the presence of the recently identified gas channel Rhcg. This review is an update on the different mechanisms of ammonium transport along the nephron, with a particular emphasis on these new molecules. PMID:21170885

Eladari, Dominique; Chambrey, Régine

2010-01-01

296

Quaternary uplift of southern Italy  

Microsoft Academic Search

Dramatic coastline changes demonstrate rapid Quaternary uplift of Calabria in southern Italy. Because most of the west (Tyrrhenian Sea) coast is normal fault bounded, previous work has asserted that its uplift is local footwall uplift related to extension. However, the east (Ionian Sea) coast is also uplifting but is not normal fault bounded. This reanalysis, based on original field work

Rob Westaway

1993-01-01

297

Quaternary faults of west Texas  

Microsoft Academic Search

North- and northwest-striking intermontane basins and associated normal faults in West Texas and adjacent Chihuahua, Mexico, formed in response to Basin and Range tectonism that began about 24 Ma ago. Data on the precise ages of faulted and unfaulted Quaternary deposits are sparse. However, age estimates made on the basis of field stratigraphic relationships and the degree of calcic soil

E. W. Collins; J. A. Raney

1993-01-01

298

Quaternary Studies: An Interdisciplinary Program  

NSDL National Science Digital Library

Rutgers University promotes its Graduate Certificate in Quaternary Studies where students take part in geology, geography, meteorology, and other disciplines interested in the last couple of million years of Earth's history. Students and educators can find information on the researchers involved with the program and the necessary course work.

2014-09-02

299

Preparation and characterization of ammonium-functionalized silica nanoparticle as a new adsorbent to remove methyl orange from aqueous solution  

NASA Astrophysics Data System (ADS)

Quaternary ammonium polyethylenimine (PEI) was successfully modified to silica nanoparticle (QPEI/SiO2) as a new adsorbent to remove methyl orange from aqueous solution. The isotherm and kinetics of dye adsorption were studied, which showed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity of QPEI/SiO2 for methyl orange is 105.4 mg/g. The equilibrium time for methyl orange adsorption onto QPEI/SiO2 was as short as 10 min, indicating that the adsorbent has a strong affinity for methyl orange. The adsorption capacities of the methyl orange are slightly influenced by the pH in the range of 3.2-9.6. The QPEI/SiO2 adsorbent can be used in the wide pH range, which is different from other adsorbent. This may attribute to the quaternary ammonium carrying positive charges in acidic and basic solution.

Liu, Jinshui; Ma, Shi; Zang, Lingjie

2013-01-01

300

Anaerobic ammonium oxidation for treatment of ammonium-rich wastewaters*  

PubMed Central

The concept of anaerobic ammonium oxidation (ANAMMOX) is presently of great interest. The functional bacteria belonging to the Planctomycete phylum and their metabolism are investigated by microbiologists. Meanwhile, the ANAMMOX is equally valuable in treatment of ammonium-rich wastewaters. Related processes including partial nitritation-ANAMMOX and completely autotrophic nitrogen removal over nitrite (CANON) have been developed, and lab-scale experiments proved that both processes were quite feasible in engineering with appropriate control. Successful full-scale practice in the Netherlands will accelerate application of the process in future. This review introduces the microbiology and more focuses on application of the ANAMMOX process. PMID:18500782

Zhang, Lei; Zheng, Ping; Tang, Chong-jian; Jin, Ren-cun

2008-01-01

301

Antimicrobial and inhibitory enzyme activity of N-(benzyl) and quaternary N-(benzyl) chitosan derivatives on plant pathogens.  

PubMed

Chemical modification of a biopolymer chitosan by introducing quaternary ammonium moieties into the polymer backbone enhances its antimicrobial activity. In the present study, a series of quaternary N-(benzyl) chitosan derivatives were synthesized and characterized by (1)H-NMR, FT-IR and UV spectroscopic techniques. The antimicrobial activity against crop-threatening bacteria Agrobacterium tumefaciens and Erwinia carotovora and fungi Botrytis cinerea, Botryodiplodia theobromae, Fusarium oxysporum and Phytophthora infestans were evaluated. The results proved that the grafting of benzyl moiety or quaternization of the derivatives onto chitosan molecule was successful in inhibiting the microbial growth. Moreover, increase water-solubility of the compounds by quaternization significantly increased the activity against bacteria and fungi. Exocellular enzymes including polygalacturonase (PGase), pectin-lyase (PLase), polyphenol oxidase (PPOase) and cellulase were also affected at 1000 mg/L. These compounds especially quaternary-based chitosan derivatives that have good inhibitory effect should be potentially used as antimicrobial agents in crop protection. PMID:25037402

Badawy, Mohamed E I; Rabea, Entsar I; Taktak, Nehad E M

2014-10-13

302

Enhanced growth rate for ammonothermal gallium nitride crystal growth using ammonium iodide mineralizer  

NASA Astrophysics Data System (ADS)

High-temperature gallium nitride (GaN) crystal growth using the acidic ammonothermal method with ammonium iodide (NH4I) as a mineralizer was investigated. The growth rate reached 105 ?m/day, which was much higher than that previously achieved using acidic ammonothermal methods, and exceeded 100 ?m/day, which is the minimum growth rate required for industrial applications. When NH4I was used as a mineralizer, high-speed crystal growth was achieved at a relatively low pressure compared to the case of using an ammonium chloride (NH4Cl) as a mineralizer.

Tomida, D.; Kagamitani, Y.; Bao, Q.; Hazu, K.; Sawayama, H.; Chichibu, S. F.; Yokoyama, C.; Fukuda, T.; Ishiguro, T.

2012-08-01

303

Mucoadhesive nanoparticles made of thiolated quaternary chitosan crosslinked with hyaluronan.  

PubMed

Mucoadhesive polymeric nanoparticles intended for drug transport across the gastrointestinal mucosa were prepared from quaternary ammonium-chitosan conjugates synthesised from reduced-MW chitosan (32 kDa). Conjugates contained pendant moieties of 2-4 adjacent diethyl-dimethylene-ammonium groups substituted on repeating units (26-55%). Conjugates were thiolated via amide bonds with thioglycolic acid to yield products with thiol content in the 35-87 ?mol/g range. Nanoparticles with mean size in the 270-370 nm range and positive zeta-potential (+3.7 to +12.5 mV) resulted from ionotropic gelation of the thiolated conjugates with de-polymerised hyaluronic acid (470 kDa). The nanoparticles were fairly stable in size and thiol content and showed a significant mucoadhesivity, matching and even exceeding that of the constituent polymers. Nanoparticles were internalised by endothelial progenitor cells in direct relation to their surface charge intensity. Nanoparticle uptake significantly improved cell viability and resistance to oxidation. The lyophilised nanoparticles were re-dispersible and could make a manageable formulation for oral use. PMID:23218262

Zambito, Ylenia; Felice, Francesca; Fabiano, Angela; Di Stefano, Rossella; Di Colo, Giacomo

2013-01-30

304

Quaternary ecology: A paleoecological perspective  

SciTech Connect

This book considers issues and problems in ecology which may be illuminated, if not solved, by considering paleoecology. The five central chapters include a discussion of application of Quaternary ecology to future global climate change, including global warming. Other areas presented include: population dispersal, invasions, expansions, and migrations; plant successions; ecotones; factors in community structure; ecosystem patterns and processes. Published case studies are numerous. The role played by continuing climatic change in vegetation change is acknowledged but not stressed.

Delcourt, H.R.; Delcourt, P.A.

1991-01-01

305

Cyclo­hexyl­ammonium nitrate  

PubMed Central

In the title salt, C6H14N+·NO3 ?, the cyclo­hexyl ring adopts a chair conformation. The ammonium group occupies an equatorial position and the crystal struture is stabilized by inter­molecular N—H?O hydrogen-bonding inter­actions, resulting in a three-dimensional network. PMID:24764971

Bagabas, Abdulaziz A.; Aboud, Mohamed F. A.; Shemsi, Ahsan M.; Addurihem, Emad S.; Al-Othman, Zeid A.; Chidan Kumar, C. S.; Fun, Hoong-Kun

2014-01-01

306

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2011 CFR

...NH4 )2 CO3 , CAS Reg. No. 8000-73-5) is a mixture of ammonium bicarbonate (NH4 HCO3 ) and ammonium carbamate (NH2 COONH4 ). It is prepared by the sublimation of a mixture of ammonium sulfate and calcium carbonate and...

2011-04-01

307

Extraction of urea and ammonium ion  

NASA Technical Reports Server (NTRS)

Water purification system keeps urea and ammonium ion concentration below toxic limits in recirculated water of closed loop aquatic habitat. Urea is first converted to ammonium ions and carbon dioxide by enzygmatic action. Ammonium ions are removed by ion exchange. Bioburden is controlled by filtration through 0.45 micron millipore filters.

Anselmi, R. T.; Husted, R. R.; Schulz, J. R.

1977-01-01

308

Influence of Heterogeneous Ammonium Availability on Bacterial  

E-print Network

primarily focused on nitrification by ammonium-oxidizing bacteria, the role of nitrate as an electronInfluence of Heterogeneous Ammonium Availability on Bacterial Community Structure and the Expression of Nitrogen Fixation and Ammonium Transporter Genes during in Situ Bioremediation of Uranium

Lovley, Derek

309

Polyurethane-based polymer surface modifiers with alkyl ammonium copolyoxetane soft segments: Reaction engineering, surface morphology and antimicrobial behavior  

NASA Astrophysics Data System (ADS)

Concentrating quaternary (positive) charge at polymer surfaces is important for applications including layer-by-layer polyelectrolyte deposition and antimicrobial coatings. Prior techniques to introduce quaternary charge to the surface involve grafting of quaternary ammonium moieties to a substrate or using polyurethanes with modified hard segments however there are impracticalities involved with these techniques. In the case of the materials discussed, the quaternary charge is introduced via polyurethane based polymer surface modifiers (PSMs) with quaternized soft segments. The particular advantage to this method is that it utilizes the intrinsic phase separation between the hard and soft segments of polyurethanes. This phase separation results in the surface concentration of the soft segments. Another advantage is that unlike grafting, where modification has to take place after device fabrication, these PSMs can be incorporated with the matrix material during device fabrication. The soft segments of these quaternized polyurethanes are produced via ring opening co-polymerization of oxetane monomers which possess either a trifluoroethoxy (3FOx) side chains or a quaternary ammonium side chain (C12). These soft segments are subsequently reacted with 4,4'-(methylene bis (p-cyclohexyl isocyanate)), HMDI and butanediol (BD) to form the PSM. It was initially intended to increase the concentration of quaternary ammonium charge by increasing PSM soft segment molecular weight. Unexpectedly, produced blends with surface microscale phase separation. This observation prompted further investigation of the effect of PSM soft segment molecular weight on phase separation in PSM-base polyurethane blends and the subsequent effects of this phase separation on the biocidal activity. Analysis of the surface morphology via tapping mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) revealed varying complexities in surface morphology as a function of the PSM soft segment molecular weight and initial annealing temperature. Many of these features include what are described as nanodots (100-300 nm), micropits (0.5-2 mum) and micropeaks (1-10 mum). It was also observed that surface morphology continued to coarsen with time and that the larger features were typically observed in blends containing PSMs with low molecular weight soft segments. This appearance of surface morphological feature correlates with decreased biocidal activity of the PSM blends, that is, the PSM blends exhibit little to no activity upon development of phase separated features. A model has been developed for phase separation and concomitant reduction of surface quaternary charge. This model points the way to future work that will stabilize surface charge and provide durability of surface modification.

Brunson, Kennard Marcellus, Jr.

310

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT OF CENTER WITH TOP OF SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

311

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.  

Code of Federal Regulations, 2012 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2012-10-01

312

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.  

Code of Federal Regulations, 2010 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2010-10-01

313

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.  

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2014-10-01

314

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.  

Code of Federal Regulations, 2013 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2013-10-01

315

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.  

Code of Federal Regulations, 2011 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2011-10-01

316

Late Quaternary history of the Atacama Desert  

E-print Network

#12;#12;#12;#12;#12;73 Late Quaternary history of the Atacama Desert Claudio Latorre, Julio L and Kate Rylander Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been

Vuille, Mathias

317

Determinants of quaternary association in legume lectins  

Microsoft Academic Search

It is well known that the sequence of amino acids in proteins code for its tertiary structure. It is also known that there exists a relationship between sequence and the quaternary structure of proteins. The question addressed here is whether the nature of quaternary association can be predicted from the sequence, similar to the three-dimensional structure prediction from the sequence.

K. V. Brinda; Nivedita Mitra; Avadhesha Surolia; Saraswathi Vishveshwara

2004-01-01

318

Stereoselective Synthesis of Quaternary Proline Analogues  

PubMed Central

This review describes available methods for the diastereoselective and asymmetric synthesis of quaternary prolines. The focus is on the preparation of ?-functionalized prolines with the pyrrolidine moiety not embedded in a polycyclic frame. The diverse synthetic approaches are classified according to the bond which is formed to complete the quaternary skeleton. PMID:19655047

Calaza, M. Isabel

2009-01-01

319

[Congenital chloride diarrhea].  

PubMed

Congenital chloride diarrhea (CCD) is a rare hereditary disease, with a prenatal onset, secondary to a deficit in the intestinal chloride transport. In the present study, we describe the clinical characteristics of three patients with congenital watery diarrhea, two of them females, aged between 9 and 14 months at the first visit. All patients presented perinatal antecedents of polyhydramnios and prematurity, watery stools since birth and growth failure. Metabolic alkalosis, hypokalemia and hypochloremia were found. Stool ionogram with elevated doses of chloride, exceeding both sodium and potassium, confirmed the diagnosis of CCD. Substitute treatment with sodium and potassium chloride was started with good results. CCD should be considered as a differential diagnosis to congenital watery diarrhea, since early diagnosis and appropriate treatment are mandatory for the normal development of the child, avoiding severe complications such as neurological sequelae and even death. PMID:16127986

Contreras, Mónica; Rocca, Ana; Benedetti, Laura; Kakisu, Hisae; Delgado, Sabrina; Ruiz, José Antonio

2005-01-01

320

Triethyl­ammonium hydrogen chloranilate  

PubMed Central

In the crystal structure of the title compound (systematic name: triethyl­ammonium 2,5-dichloro-4-hy­droxy-3,6-dioxo­cyclo­hexa-1,4-dien-1-olate), C6H16N+·C6HCl2O4 ?, two hydrogen chloranilate anions are connected by a pair of bifurcated O—H?O hydrogen bonds into a dimeric unit. The triethyl­ammonium cations are linked on both sides of the dimer via bifurcated N—H?O hydrogen bonds into a centrosymmetric 2:2 aggregate. The 2:2 aggregates are further linked by inter­molecular C—H?O hydrogen bonds. PMID:21589539

Gotoh, Kazuma; Maruyama, Shinpei; Ishida, Hiroyuki

2010-01-01

321

Cyclic voltammetry of metallic acetylacetonate salts in quaternary ammonium and phosphonium based deep eutectic solvents  

Microsoft Academic Search

Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 mol·L-1 for the most soluble salts, some were found to display

M. H. Chakrabarti; N. P. Brandon; F. S. Mjalli; L. Bahadori; I. M. Al Nashef; M. A. Hashim; M. A. Hussain; C. T. J. Low; V. Yufit

2013-01-01

322

75 FR 40729 - Residues of Quaternary Ammonium Compounds, N-Alkyl (C12-14  

Federal Register 2010, 2011, 2012, 2013

...product (4% ai.)) mg/kg/day (333 ug/ guinea pigs MRID cm2)b 41105801 UFA = 3x...Formulated-based dermal endpoint = (20 mg/kg guinea pig x 0.43 kg guinea pig x 1,000 ug/mg)/25.8cm2 area of guinea...

2010-07-14

323

Mixtures of Quaternary Ammonium Compounds and Long-chain Fatty Acids as Antifungal Agents  

PubMed Central

The influence of undecylenic acid on the fungistatic effect of phenoxyethyldimethyldodecylammonium bromide (Domiphen bromide) against Trichophyton mentagrophytes was investigated. The unsaturated fatty acid was found to enhance the fungistatic activity of Domiphen bromide against this organism. The ratio of concentrations of these agents has a marked influence on the results of in vitro tests for antifungal action resulting in a completely different effect than heretofore noted in combination experiments against bacteria. The enhancing phenomenon is not particular to T. mentagrophytes, it was observed also with Candida albicans. PMID:14460466

Kull, F. C.; Eisman, P. C.; Sylwestrowicz, H. D.; Mayer, R. L.

1961-01-01

324

40 CFR 721.10666 - Quaternary ammonium compounds, bis(fattyalkyl) dimethyl, salts with tannins (generic).  

Code of Federal Regulations, 2013 CFR

...bis(fattyalkyl) dimethyl, salts with tannins (generic). 721.10666 Section...bis(fattyalkyl) dimethyl, salts with tannins (generic). (a) Chemical substance...bis(fattyalkyl) dimethyl, salts with tannins (PMN P-12-437) is subject to...

2013-07-01

325

40 CFR 721.10666 - Quaternary ammonium compounds, bis(fattyalkyl) dimethyl, salts with tannins (generic).  

...bis(fattyalkyl) dimethyl, salts with tannins (generic). 721.10666 Section...bis(fattyalkyl) dimethyl, salts with tannins (generic). (a) Chemical substance...bis(fattyalkyl) dimethyl, salts with tannins (PMN P-12-437) is subject to...

2014-07-01

326

Interaction between Quaternary Ammonium Ions in the Pore of Potassium Channels  

PubMed Central

We have examined the interaction between internal and external ions in the pore of potassium channels. We found that external tetraethylammonium was able to antagonize block of Shaker channels by internal TEA when the external and internal solutions contained K+ ions. This antagonism was absent in solutions with Rb+ as the only permeant ion. An externally applied trivalent TEA analogue, gallamine, was less effective than the monovalent TEA in inhibiting block by internal TEA. In addition, block by external TEA was little affected by changes in the concentration of internal K+ ions, but was increased by the presence of internal Na+ ions in the pore. These results demonstrate that external and internal TEA ions, likely located at opposite ends of the pore selectivity filter, do not experience a mutual electrostatic repulsion. We found that these results can be simulated by a simple 4-barrier-3-site permeation model in which ions compete for available binding sites without long-range electrostatic interactions. PMID:10828250

Thompson, Jill; Begenisich, Ted

2000-01-01

327

THE SALTING OUT OF GELATIN INTO TWO LIQUID LAYERS WITH SODIUM CHLORIDE AND OTHER SALTS.  

PubMed

1. Conditions under which gelatin may be salted out into two liquid layers at 35 degrees were studied. 2. The equilibria governing the amounts and composition of the layers salted out with sodium chloride are found to accord with the requirements of the phase rule for the quaternary system gelatin-sodium chloride-hydrogen ion-water. 3. So far, soaps and gelatin are found to be surprisingly similar in their behaviour and definite indications are given as to where further similarities may be sought. 4. It is evident from this work that the term "coagulation" as ordinarily applied to the salting out of proteins is definitely a misnomer. PMID:19872438

McBain, J W; Kellogg, F

1928-09-20

328

THE SALTING OUT OF GELATIN INTO TWO LIQUID LAYERS WITH SODIUM CHLORIDE AND OTHER SALTS  

PubMed Central

1. Conditions under which gelatin may be salted out into two liquid layers at 35° were studied. 2. The equilibria governing the amounts and composition of the layers salted out with sodium chloride are found to accord with the requirements of the phase rule for the quaternary system gelatin-sodium chloride-hydrogen ion-water. 3. So far, soaps and gelatin are found to be surprisingly similar in their behaviour and definite indications are given as to where further similarities may be sought. 4. It is evident from this work that the term "coagulation" as ordinarily applied to the salting out of proteins is definitely a misnomer. PMID:19872438

McBain, James W.; Kellogg, Frederick

1928-01-01

329

Formation of light absorbing organo-nitrogen species from evaporation of droplets containing glyoxal and ammonium sulfate  

NASA Astrophysics Data System (ADS)

Formation of particle-phase organo-nitrogen compounds has been recently proposed via aqueous chemistry of glyoxal and ammonium sulfate in both dark and illuminated conditions. In the atmosphere, glyoxal can partition into aqueous droplets containing significant levels of different inorganic salts but their molecular interactions are still not well understood. Upon droplet evaporation, both the organics and inorganic ions become highly concentrated, accelerating reactions between them. To demonstrate this process, we investigated the formation of organo-nitrogen and light absorbing materials in evaporating droplets containing glyoxal and different ammonium salts including ammonium sulfate, ammonium nitrate and ammonium chloride. Our results demonstrate that evaporating glyoxal-ammonium sulfate droplets produce light absorbing species on a time scale of seconds, which is orders of magnitude faster than observed in bulk solutions. Using aerosol mass spectrometry, we show that particle-phase organics with high N:C ratios were formed when ammonium salts were used, and that the presence of sulfate ions promoted this chemistry. Since sulfate can also significantly enhance the Henry's law partitioning of glyoxal, our results highlight the atmospheric importance of such inorganic-organic interactions in aqueous phase aerosol chemistry.

Lee, A.; Zhao, R.; Richard, L.; Liggio, G.; Li, S.; Abbatt, J.

2013-12-01

330

Comparative effects of ammonium and nitrate compounds on Pacific treefrog and African clawed frog embryos.  

PubMed

The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific treefrog (Pseudacris regilla) and African clawed frog (Xenopus laevis) embryos were determined in static-renewal tests. The 10-day LC50s for the three ammonium compounds for P. regilla ranged from 25.0-32. 4 mg/L NH4 -N. The 10-day sodium nitrate LC50 for P. regilla was 578. 0 mg/L NO3-N. LC50s for X. laevis exposed for 4 or 5 days to the three ammonium compounds ranged from 27.5-60.2 mg/L NH4-N. The sodium nitrate LC50 for X. laevis ranged from 438.4-871.6 mg/L NO3-N. The lowest LOAEL based on length or weight was 6.1 mg/L NH4-N for the two species. The lowest LOAELs for NO3-N were 111.1 mg/L for P. regilla and 56.7 mg/L for X. laevis. Calculated unionized NH3 comprised 0.5-1.8% of measured NH4-N concentrations. Potential harm to amphibian populations could occur if NH4-N and NO3-N in agricultural runoff or drainage impacts sensitive life stages for a sufficiently long period. PMID:9888966

Schuytema, G S; Nebeker, A V

1999-02-01

331

An Electronic Tongue Designed to Detect Ammonium Nitrate in Aqueous Solutions  

PubMed Central

An electronic tongue has been developed to monitor the presence of ammonium nitrate in water. It is based on pulse voltammetry and consists of an array of eight working electrodes (Au; Pt; Rh; Ir; Cu; Co; Ag and Ni) encapsulated in a stainless steel cylinder. In a first step the electrochemical response of the different electrodes was studied in the presence of ammonium nitrate in water in order to further design the wave form used in the voltammetric tongue. The response of the electronic tongue was then tested in the presence of a set of 15 common inorganic salts; i.e.; NH4NO3; MgSO4; NH4Cl; NaCl; Na2CO3; (NH4)2SO4; MgCl2; Na3PO4; K2SO4; K2CO3; CaCl2; NaH2PO4; KCl; NaNO3; K2HPO4. A PCA plot showed a fairly good discrimination between ammonium nitrate and the remaining salts studied. In addition Fuzzy Art map analyses determined that the best classification was obtained using the Pt; Co; Cu and Ni electrodes. Moreover; PLS regression allowed the creation of a model to correlate the voltammetric response of the electrodes with concentrations of ammonium nitrate in the presence of potential interferents such as ammonium chloride and sodium nitrate. PMID:24145916

Campos, Inmaculada; Pascual, Lluis; Soto, Juan; Gil-Sánchez, Luis; Martínez-Máñez, Ramón

2013-01-01

332

Physiological aspects of ammonium and nitrate fertilization  

Microsoft Academic Search

Various physiological effects of ammonium, nitrate and mixed ammonium?nitrate nutrition of plants have been studied in this laboratory during the last years. Some of the characteristic distinctions observed between plants growing on these nitrogen sources are described and discussed. Biomass production of ammonium?grown plants increased with K concentration in the nutrient medium between 0.1 to 3 mM , while nitrate?fed

S. H. Lips; E. O. Leidi; M. Silberbush; M. I. M. Soares; O. E. M. Lewis

1990-01-01

333

Molecular Structure of Barium Chloride  

NSDL National Science Digital Library

Barium Chloride was the byproduct of the discovery of radium by Madame Curie. When refining radium, the final separation resulted in barium chloride and radium chloride. Electrophoresis of barium chloride produces small-scale amounts of barium atom. This can be used for obtaining barium for commercial uses. Applications of barium chloride include stimulating the heart and other muscles for medicinal purposes, and also for softening water. Other uses of barium chloride include the manufacturing of barium salts, as pesticide, pigments, boiler detergent, in purifying sugar, as mordant in dyeing and printing textiles, and in the manufacture of caustic soda, polymers, and stabilizers.

2002-08-15

334

Chloride removal from vitrification offgas  

SciTech Connect

This study identified and investigated techniques of selectively purging chlorides from the low-level waste (LLW) vitrification process with the purge stream acceptable for burial on the Hanford Site. Chlorides will be present in high concentration in several individual feeds to the LLW Vitrification Plant. The chlorides are highly volatile in combustion type melters and are readily absorbed by wet scrubbing of the melter offgas. The Tank Waste Remediation System (TWRS) process flow sheets show that the resulting chloride rich scrub solution is recycled back to the melter. The chlorides must be purged from the recycle loop to prevent the buildup of excessively high chloride concentrations.

Slaathaug, E.J. [Westinghouse Hanford Co., Richland, WA (United States)

1995-06-01

335

75 FR 55991 - Ammonium Formate; Exemption from the Requirement of a Tolerance  

Federal Register 2010, 2011, 2012, 2013

...Ammonium formate breaks down into ammonium and formate ions. Ammonium ions are a toxic waste product of the metabolism in animals...Ammonium formate breaks down into ammonium and formate ions. Ammonium ions are ubiquitous in the natural...

2010-09-15

336

Comparative toxicity of ammonium and nitrate compounds to Pacific treefrog and African clawed frog tadpoles  

SciTech Connect

The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific treefrog (Pseudacris regilla [Baird and Girard]) and African clawed frog (Xenopus laevis [Daudin]) tadpoles were determined in static-renewal tests. The 10-d ammonium nitrate and ammonium sulfate LC50s for P. regilla were 55.2 and 89.7 mg/L NH{sub 4}-N, respectively. The 10-d LC50s for X. laevis for the three ammonium compounds ranged from 45 to 64 mg/L NH{sub 4}-N. The 10-d sodium nitrate LC50s were 266.2 mg/L NO{sub 3}-N for P. regilla and 1,236.2 mg/L NO{sub 3}-N for X. laevis. The lowest observed adverse effect level (LOAEL) of ammonium compound based on reduced length or weight was 24.6 mg/L NH{sub 4}-N for P. regilla and 99.5 mg/L NH{sub 4}-N for X. laevis. The lowest sodium nitrate LOAELs based on reduced length or weight were {lt}30.1 mg/L NO{sub 3}-N for P. regilla and 126.3 mg/L NO{sub 3}-N for X. laevis. Calculated un-ionized NH{sub 3} comprised 0.3 to 1.0% of measured NH{sub 4}-N concentrations. Potential harm to amphibians could occur if sensitive life stages were impacted by NH{sub 4}-N and NO{sub 3}-N in agricultural runoff or drainage for a sufficiently long period.

Schuytema, G.S.; Nebeker, A.V.

1999-10-01

337

Effect of ammonium sulfate, ammonium chloride and root-zone acidity on inorganic ion content of tobacco  

NASA Technical Reports Server (NTRS)

Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH4)2SO4 or NH4Cl at root-zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH4+ source or root-zone pH. Plants supplied with NH4Cl accumulated up to 1.2 mM Cl g DW-1, but accumulated 37% less inorganic H2PO4- and 47% less SO4(2-) than plants supplied with (NH4)2SO4. The large Cl- accumulation resulted in NH4Cl- supplied plants having a 31% higher inorganic anion (NO3-, H2, PO4-, SO4(2-), and Cl-) charge. This higher inorganic anion charge in the NH4Cl-supplied plants was balanced by a similar increase in K+ charge. Plants supplied with NH4Cl accumulated greater concentrations of Cl- in leaves (up to 5.1% of DW) than plants supplied with (NH4)2SO4 (less than -% DW). Despite the high Cl- concentration of leaves in NH4Cl supplied plants, these plants showed no symptoms of Cl- toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl- concentration in tissue and NH4+ nutrition. The increase in root-zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.

Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

1990-01-01

338

Ammonium assmilation in spruce ectomycorrhizas  

SciTech Connect

Assimilation of labelled NH{sub 4}{sup +} into amino acids has been followed in ectomycorrhizal roots of spruce. Over an 18 h period of NH{sub 4}{sup +} feeding, Gln, Glu and Ala became the most abundant amino acids. Gln was also the most highly labelled amino acid during the experiment, followed by Glu and Ala. This result indicates that Gln synthesis is an important ammonium utilization reaction in spruce mycorrhizas. Addition of MSX to NH{sub 4}{sup +} fed mycorrhizas caused an inhibition of Gln accumulation with a corresponding increase in Glu, Ala and Asn levels. The supply of MSX induced a sharp diminution of {sup 15}N enrichment in both amino and amido groups of glutamine. In contrast, the {sup 15}N incorporation into Glu and derivatives (Ala and Asp) remained very high. This study demonstrates that the fungal glutamate dehydrogenase is quite operative in spruce ectomycorrhizas since it is able to sustain ammonium assimilation when glutamine synthetase is inhibited.

Chalot, M.; Brun, A.; Botton, B. (Univ. of nancy, Vandoeuvre-les-Nancy (France)); Stewart, G. (University College, London (England))

1990-05-01

339

Structural study of ammonium metatungstate  

SciTech Connect

Several techniques have been used to study the structure of the Keggin-type polyoxometalate salt ammonium metatungstate (AMT)-(NH{sub 4}){sub 6}[H{sub 2}W{sub 12}O{sub 40}]*nH{sub 2}O, a potential fuel cell catalyst. The dehydrated salt is comprised of a mixture of crystallites of different unit cells in a centered eutactic cubic configuration, with an average unit cell of a{approx_equal}12.295. Varied orientations of the Keggin ions in the cubic arrangement create the differences, and orientational variation within each unit cell size represents an energy well. Progressive hydration of each crystallite leads to expansion of the lattice, with the degree of expansion depending on the locations of the water added in relation to the Keggin ion, which is influenced by cation location and hydrogen bonding. The structural hypothesis is supported by electron diffraction of single and multicrystal samples, by powder density measurements, X-ray powder diffraction studies, synchrotron powder X-ray diffraction, and a priori structural modeling studies. Based on the structure, projected active site densities are compared with nanostructured platinum catalysts for fuel cell application. - Graphical abstract: The structure of ammonium metatungstate powders are highly dependent on hydration and POM molecule rotation, with cation and hydrogen bonding forces directing a mixture of structures that have been studied with bulk and single-crystal methods. The illustration shows Monte Carlo simulated anion structural disorder for the fully dehydrated form of the title compound.

Christian, Joel B. [OSRAM SYLVANIA Global Tungsten and Powders, Towanda, PA 18848 (United States); SUNY at Binghamton, Materials Science Program, Binghamton, NY 13902 (United States)], E-mail: joel.christian@sylvania.com; Whittingham, M. Stanley [SUNY at Binghamton, Materials Science Program, Binghamton, NY 13902 (United States)

2008-08-15

340

Molecular Structure of Thionyl chloride  

NSDL National Science Digital Library

Thionyl chloride is a slightly yellowish liquid with an intense odor and low viscosity. It reacts with lithium to produce lithium chloride and is a good solvent for most organic compounds. Other uses of thionyl chloride include as an intermediate for the production of pharmaceutically active ingredients, as an electrolyte in lithium batteries, and in crop protection.

2002-10-01

341

Chloride Channels of Intracellular Membranes  

PubMed Central

Proteins implicated as intracellular chloride channels include the intracellular ClC proteins, the bestrophins, the cystic fibrosis transmembrane conductance regulator, the CLICs, and the recently described Golgi pH regulator. This paper examines current hypotheses regarding roles of intracellular chloride channels and reviews the evidence supporting a role in intracellular chloride transport for each of these proteins. PMID:20100480

Edwards, John C.; Kahl, Christina R.

2010-01-01

342

Sodium Chloride (Catheter Flush) Injection  

MedlinePLUS

... use a sodium chloride flush several times a day. Your health care provider will determine the number of sodium chloride flushes you will need a day. ... health care provider probably will give you several days supply of sodium chloride. You will be told ...

343

Supercritical water oxidation of ammonium picrate  

Microsoft Academic Search

This study demonstrates the feasibility of using supercritical water oxidation to destroy ammonium picrate. Analyses of reactor effluent composition at various temperatures, residence times, and oxidant concentrations were used to design an improved reactor configuration for achieving destruction with minimum corrosion. The engineering evaluation reactor, a room-sized laboratory scale reactor, was reconfigured to incorporate this design change. Destruction of ammonium

C. A. LaJeunesse; B. E. Mills; B. G. Brown

1994-01-01

344

21 CFR 558.340 - Maduramicin ammonium.  

Code of Federal Regulations, 2010 CFR

... 6 2010-04-01 2010-04-01 false Maduramicin ammonium. 558.340 Section 558.340 Food and Drugs FOOD...Animal Drugs for Use in Animal Feeds § 558.340 Maduramicin ammonium. (a) Approvals. Type A medicated articles:...

2010-04-01

345

Ammonium nonanoate broadcast application over onions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ammonium nonanoate occurs in nature and is primarily formed from biodegradation of higher fatty acids. Racer (40% ammonium nonaoate) is a potential contact herbicide for weed control in organic crop production. Field research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determin...

346

Winter Wheat Fertilization: Post Ammonium Nitrate  

Microsoft Academic Search

Summary The potential for overwinter losses of nitrogen by denitrification and leaching have led to the recommendation that nitrogen fertilization of winter wheat be done using ammonium nitrate broadcast in the spring. However, spring broadcast application of urea can result in significant loss of nitrogen by volatilization and immobilization by surface residues. Since prilled ammonium nitrate is not available for

R. Byron Irvine; Guy Lafond; Randy Kutcher

347

Ligand-enabled multiple absolute stereocontrol in metal-catalysed cycloaddition for construction of contiguous all-carbon quaternary stereocentres  

NASA Astrophysics Data System (ADS)

The development of a general catalytic method for the direct and stereoselective construction of contiguous all-carbon quaternary stereocentres remains a formidable challenge in chemical synthesis. Here, we report a highly enantio- and diastereoselective [3+2] annulation reaction of 5-vinyloxazolidinones and activated trisubstituted alkenes catalysed by a palladium complex bearing a newly devised phosphine ligand with a chiral ammonium salt component, which enables the single-step construction of three contiguous stereocentres, including vicinal all-carbon quaternary stereocentres, in a five-membered heterocyclic framework. This stereoselective cycloaddition protocol relies on the remarkable ability of the chiral ligand to rigorously control the absolute stereochemistry of each chiral centre associated with the multiple bond-forming events, and provides a reliable catalytic process for the asymmetric synthesis of densely functionalized pyrrolidines.

Ohmatsu, Kohsuke; Imagawa, Naomichi; Ooi, Takashi

2014-01-01

348

Ligand-enabled multiple absolute stereocontrol in metal-catalysed cycloaddition for construction of contiguous all-carbon quaternary stereocentres.  

PubMed

The development of a general catalytic method for the direct and stereoselective construction of contiguous all-carbon quaternary stereocentres remains a formidable challenge in chemical synthesis. Here, we report a highly enantio- and diastereoselective [3+2] annulation reaction of 5-vinyloxazolidinones and activated trisubstituted alkenes catalysed by a palladium complex bearing a newly devised phosphine ligand with a chiral ammonium salt component, which enables the single-step construction of three contiguous stereocentres, including vicinal all-carbon quaternary stereocentres, in a five-membered heterocyclic framework. This stereoselective cycloaddition protocol relies on the remarkable ability of the chiral ligand to rigorously control the absolute stereochemistry of each chiral centre associated with the multiple bond-forming events, and provides a reliable catalytic process for the asymmetric synthesis of densely functionalized pyrrolidines. PMID:24345946

Ohmatsu, Kohsuke; Imagawa, Naomichi; Ooi, Takashi

2014-01-01

349

Effect of ammonium nitrate on precipitation of Ammonium Di-Uranate (ADU) and its characteristics  

NASA Astrophysics Data System (ADS)

Effect of ammonium nitrate on precipitation of Ammonium Di-Uranate (ADU) from nitric acid medium via gaseous ammonia route had been investigated. Studies on effect of ammonium nitrate on precipitation time, particle size, shape, surface morphology, flowability, oxygen/uranium (O/U) ratio and tap density of calcined ADU were carried out at various ammonium nitrate concentrations. It was observed that, the presence of excess ammonium nitrate influences the precipitation time, particle size distribution and surface morphology of the ADU. ADU and uranium oxide were characterized with Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). Presence of ammonium nitrate during precipitation leads to the formation of bigger, porous and uniform particles as compared to the ADU prepared without ammonium nitrate additions.

Paik, Shrishma; Biswas, S.; Bhattacharya, S.; Roy, S. B.

2013-09-01

350

21 CFR 582.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2012-04-01

351

21 CFR 582.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2013-04-01

352

21 CFR 582.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2011-04-01

353

21 CFR 582.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2010-04-01

354

21 CFR 182.1127 - Aluminum ammonium sulfate.  

...2014-04-01 2014-04-01 false Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2014-04-01

355

21 CFR 182.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2012-04-01

356

21 CFR 182.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2009-04-01 true Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2010-04-01

357

21 CFR 182.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2011-04-01

358

21 CFR 582.1127 - Aluminum ammonium sulfate.  

...2014-04-01 2014-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2014-04-01

359

21 CFR 182.1127 - Aluminum ammonium sulfate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

2013-04-01

360

40 CFR 721.10099 - Dialkyl dimethyl ammonium carbonate (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dialkyl dimethyl ammonium carbonate (generic). 721.10099...Substances § 721.10099 Dialkyl dimethyl ammonium carbonate (generic). (a) Chemical...identified generically as dialkyl dimethyl ammonium carbonate (1:1) (PMN...

2010-07-01

361

40 CFR 721.10302 - Zinc ammonium phosphate (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Zinc ammonium phosphate (generic). 721...Specific Chemical Substances § 721.10302 Zinc ammonium phosphate (generic). ...chemical substance identified generically as zinc ammonium phosphate (PMN...

2012-07-01

362

40 CFR 721.10302 - Zinc ammonium phosphate (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Zinc ammonium phosphate (generic). 721...Specific Chemical Substances § 721.10302 Zinc ammonium phosphate (generic). ...chemical substance identified generically as zinc ammonium phosphate (PMN...

2013-07-01

363

40 CFR 721.10302 - Zinc ammonium phosphate (generic).  

...2014-07-01 2014-07-01 false Zinc ammonium phosphate (generic). 721...Specific Chemical Substances § 721.10302 Zinc ammonium phosphate (generic). ...chemical substance identified generically as zinc ammonium phosphate (PMN...

2014-07-01

364

78 FR 32690 - Certain Ammonium Nitrate From Ukraine  

Federal Register 2010, 2011, 2012, 2013

...731-TA-894 (Review)] Certain Ammonium Nitrate From Ukraine Determination On...antidumping duty order on certain ammonium nitrate from Ukraine would be likely...May 2013), entitled Certain Ammonium Nitrate from Ukraine:...

2013-05-31

365

Tn6188 - A Novel Transposon in Listeria monocytogenes Responsible for Tolerance to Benzalkonium Chloride  

PubMed Central

Controlling the food-borne pathogen Listeria (L.) monocytogenes is of great importance from a food safety perspective, and thus for human health. The consequences of failures in this regard have been exemplified by recent large listeriosis outbreaks in the USA and Europe. It is thus particularly notable that tolerance to quaternary ammonium compounds such as benzalkonium chloride (BC) has been observed in many L. monocytogenes strains. However, the molecular determinants and mechanisms of BC tolerance of L. monocytogenes are still largely unknown. Here we describe Tn6188, a novel transposon in L. monocytogenes conferring tolerance to BC. Tn6188 is related to Tn554 from Staphylococcus (S.) aureus and other Tn554-like transposons such as Tn558, Tn559 and Tn5406 found in various Firmicutes. Tn6188 comprises 5117 bp, is integrated chromosomally within the radC gene and consists of three transposase genes (tnpABC) as well as genes encoding a putative transcriptional regulator and QacH, a small multidrug resistance protein family (SMR) transporter putatively associated with export of BC that shows high amino acid identity to Smr/QacC from S. aureus and to EmrE from Escherichia coli. We screened 91 L. monocytogenes strains for the presence of Tn6188 by PCR and found Tn6188 in 10 of the analyzed strains. These isolates were from food and food processing environments and predominantly from serovar 1/2a. L. monocytogenes strains harboring Tn6188 had significantly higher BC minimum inhibitory concentrations (MICs) (28.5 ± 4.7 mg/l) than strains without Tn6188 (14 ± 3.2 mg/l). Using quantitative reverse transcriptase PCR we could show a significant increase in qacH expression in the presence of BC. QacH deletion mutants were generated in two L. monocytogenes strains and growth analysis revealed that ?qacH strains had lower BC MICs than wildtype strains. In conclusion, our results provide evidence that Tn6188 is responsible for BC tolerance in various L. monocytogenes strains. PMID:24098567

Muhterem-Uyar, Meryem; Zaiser, Andreas; Stessl, Beatrix; Guinane, Caitriona M.; Cotter, Paul D.; Wagner, Martin; Schmitz-Esser, Stephan

2013-01-01

366

MembFac -Scoring Sheet 1. 12% MPD, 0.1 M Na Acetate pH 4.6, 0.1 M Sodium Chloride  

E-print Network

Acetate pH 4.6 8. 18% PEG 400, 0.1 M Na Acetate pH 4.6, 0.1 M Magnesium Chloride 9. 1.0 M Ammonium Sodium Chloride 11. 12% PEG 6000, 0.1 M Na Acetate pH 4.6, 0.1 M Magnesium Chloride 12. 18% PEG 400, 0 pH 5.6, 0.1 M Sodium Chloride 16. 1.0 M Magnesium Sulfate, 0.1 M Na Citrate pH 5.6 17. 12% PEG 4000

Hill, Chris

367

Chloride and Salinity  

NSDL National Science Digital Library

This learning activity from the Advanced Technology Environmental and Energy Center (ATEEC) will provide a good introduction for students studying chloride and salinity. A list of required materials is included as well as the step by step procedure for conducting the experiment. Student worksheets are also included. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

2011-07-15

368

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

...glufosinate ammonium, butanoic acid, 2-amino-4-(hydroxymethylphosphinyl...hydroxymethylphosphinyl)propanoic acid, expressed as 2-amino-4-(hydroxymethylphosphinyl...glufosinate ammonium, butanoic acid,...

2014-07-01

369

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...glufosinate ammonium, butanoic acid, 2-amino-4-(hydroxymethylphosphinyl...hydroxymethylphosphinyl)propanoic acid, expressed as 2-amino-4-(hydroxymethylphosphinyl...glufosinate ammonium, butanoic acid,...

2013-07-01

370

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...glufosinate-ammonium (butanoic acid, 2-amino-4-(hydroxymethylphosphinyl...3-methylphosphinico-propionic acid, expressed as 2-amino-4-(hydroxymethylphosphinyl...glufosinate ammonium, butanoic acid,...

2010-07-01

371

Identification and Functional Analysis of an Ammonium Transporter in Streptococcus mutans  

PubMed Central

Streptococcus mutans, a Gram-positive bacterium, is considered to be a major etiologic agent of human dental caries and reported to form biofilms known as dental plaque on tooth surfaces. This organism is also known to possess a large number of transport proteins in the cell membrane for export and import of molecules. Nitrogen is an essential nutrient for Gram-positive bacteria, though alternative sources such as ammonium can also be utilized. In order to obtain nitrogen for macromolecular synthesis, nitrogen-containing compounds must be transported into the cell. However, the ammonium transporter in S. mutans remains to be characterized. The present study focused on characterizing the ammonium transporter gene of S. mutans and its operon, while related regulatory genes were also analyzed. The SMU.1658 gene corresponding to nrgA in S. mutans is homologous to the ammonium transporter gene in Bacillus subtilis and SMU.1657, located upstream of the nrgA gene and predicted to be glnB, is a member of the PII protein family. Using a nrgA-deficient mutant strain (NRGD), we examined bacterial growth in the presence of ammonium, calcium chloride, and manganese sulfate. Fluorescent efflux assays were also performed to reveal export molecules associated with the ammonium transporter. The growth rate of NRGD was lower, while its fluorescent intensity was much higher as compared to the parental strain. In addition, confocal laser scanning microscopy revealed that the structure of biofilms formed by NRGD was drastically different than that of the parental strain. Furthermore, transcriptional analysis showed that the nrgA gene was co-transcribed with the glnB gene. These results suggest that the nrgA gene in S. mutans is essential for export of molecules and biofilm formation. PMID:25229891

Ardin, Arifah Chieko; Fujita, Kazuyo; Nagayama, Kayoko; Takashima, Yukiko; Nomura, Ryota; Nakano, Kazuhiko; Ooshima, Takashi; Matsumoto-Nakano, Michiyo

2014-01-01

372

Effect of Application of Ammonium Chloride and Calcium Chloride on Alfalfa Cation-Anion Content and Yield1  

Microsoft Academic Search

A major factor predisposing the cow to periparturient hypocalcemia, or milk fever, is being fed a prepartum ration with a high dietary cation-anion difference (DCAD). The DCAD can be favorably altered to prevent milk fever by decreasing K and Na or increasing Cl and S in forages for cows in late gestation. The objective of this study was to test

J. P. Goff; E. C. Brummer; S. J. Henning; R. K. Doorenbos; R. L. Horst

2007-01-01

373

Influence of ammonium and nitrate nitrogen on nitrogenase activity of pea plants as affected by light intensity and sugar addition  

Microsoft Academic Search

Summary Addition of ammonium chloride or potassium nitrate to nodulated pea plants resulted in a decrease in acetylene-reducing activity. Both nodule growth and specific activity of the nodules were diminished. Acetylene-reducing activity of isolated bacteroids, treated with EDTA-toluene and supplied with ATP and dithionite, had not decreased after a 3-day treatment of the plants with NH4Cl or KNO3. The effect

F. Houwaard

1980-01-01

374

Iodide, bromide, and ammonium in hydraulic fracturing and oil and gas wastewaters: environmental implications.  

PubMed

The expansion of unconventional shale gas and hydraulic fracturing has increased the volume of the oil and gas wastewater (OGW) generated in the U.S. Here we demonstrate that OGW from Marcellus and Fayetteville hydraulic fracturing flowback fluids and Appalachian conventional produced waters is characterized by high chloride, bromide, iodide (up to 56 mg/L), and ammonium (up to 420 mg/L). Br/Cl ratios were consistent for all Appalachian brines, which reflect an origin from a common parent brine, while the I/Cl and NH4/Cl ratios varied among brines from different geological formations, reflecting geogenic processes. There were no differences in halides and ammonium concentrations between OGW originating from hydraulic fracturing and conventional oil and gas operations. Analysis of discharged effluents from three brine treatment sites in Pennsylvania and a spill site in West Virginia show elevated levels of halides (iodide up to 28 mg/L) and ammonium (12 to 106 mg/L) that mimic the composition of OGW and mix conservatively in downstream surface waters. Bromide, iodide, and ammonium in surface waters can impact stream ecosystems and promote the formation of toxic brominated-, iodinated-, and nitrogen disinfection byproducts during chlorination at downstream drinking water treatment plants. Our findings indicate that discharge and accidental spills of OGW to waterways pose risks to both human health and the environment. PMID:25587644

Harkness, Jennifer S; Dwyer, Gary S; Warner, Nathaniel R; Parker, Kimberly M; Mitch, William A; Vengosh, Avner

2015-02-01

375

Phase diagram of ammonium nitrate  

SciTech Connect

Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ?} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

Dunuwille, Mihindra; Yoo, Choong-Shik, E-mail: csyoo@wsu.edu [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)] [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)

2013-12-07

376

Substrate specificity of Rhbg: ammonium and methyl ammonium transport.  

PubMed

Rhbg is a nonerythroid membrane glycoprotein belonging to the Rh antigen family. In the kidney, Rhbg is expressed at the basolateral membrane of intercalated cells of the distal nephron and is involved in NH4+ transport. We investigated the substrate specificity of Rhbg by comparing transport of NH3/NH4+ with that of methyl amine (hydrochloride) (MA/MA+), often used to replace NH3/NH4+, in oocytes expressing Rhbg. Methyl amine (HCl) in solution exists as neutral methyl amine (MA) in equilibrium with the protonated methyl ammonium (MA+). To assess transport, we used ion-selective microelectrodes and voltage-clamp experiments to measure NH3/NH4+- and MA/MA+-induced intracellular pH (pH(i)) changes and whole cell currents. Our data showed that in Rhbg oocytes, NH3/NH4+ caused an inward current and decrease in pH(i) consistent with electrogenic NH4+ transport. These changes were significantly larger than in H2O-injected oocytes. The NH3/NH4+-induced current was not inhibited in the presence of barium or in the absence of Na+. In Rhbg oocytes, MA/MA+ caused an inward current but an increase (rather than a decrease) in pH(i). MA/MA+ did not cause any changes in H2O-injected oocytes. The MA/MA+-induced current and pH(i) increase were saturated at higher concentrations of MA/MA+. Amiloride inhibited MA/MA+-induced current and the increase in pH(i) in oocytes expressing Rhbg but had no effect on control oocytes. These results indicate that MA/MA+ is transported by Rhbg but differently than NH3/NH4+. The protonated MA+ is likely a direct substrate whose transport resembles that of NH4+. Transport of electroneutral MA is also enhanced by expression of Rhbg. PMID:20592240

Nakhoul, Nazih L; Abdulnour-Nakhoul, Solange M; Boulpaep, Emile L; Rabon, Edd; Schmidt, Eric; Hamm, L Lee

2010-09-01

377

Synthesis, spectroscopic and thermal studies of the copper(II) aspartame chloride complex  

NASA Astrophysics Data System (ADS)

Aspartame adduct of copper(II) chloride Cu(Asp) 2Cl 2·2H 2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions.

Çak?r, S.; Co?kun, E.; Naumov, P.; Biçer, E.; Bulut, ?.; ?çbudak, H.; Çak?r, O.

2002-08-01

378

40 CFR 721.10569 - Tricyclic quaternary amine salt (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Tricyclic quaternary amine salt (generic). 721.10569 Section 721...721.10569 Tricyclic quaternary amine salt (generic). (a) Chemical substance...generically as tricyclic quaternary amine salt (PMN P-08-471) is subject to...

2013-07-01

379

Catalytic enantioselective synthesis of quaternary carbon stereocentres  

NASA Astrophysics Data System (ADS)

Quaternary carbon stereocentres--carbon atoms to which four distinct carbon substituents are attached--are common features of molecules found in nature. However, before recent advances in chemical catalysis, there were few methods of constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for the synthesis of single stereoisomers of such organic molecules. This progress now makes it possible to incorporate quaternary stereocentres selectively in many organic molecules that are useful in medicine, agriculture and potentially other areas such as flavouring, fragrances and materials.

Quasdorf, Kyle W.; Overman, Larry E.

2014-12-01

380

Catalytic enantioselective synthesis of quaternary carbon stereocentres.  

PubMed

Quaternary carbon stereocentres-carbon atoms to which four distinct carbon substituents are attached-are common features of molecules found in nature. However, before recent advances in chemical catalysis, there were few methods of constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for the synthesis of single stereoisomers of such organic molecules. This progress now makes it possible to incorporate quaternary stereocentres selectively in many organic molecules that are useful in medicine, agriculture and potentially other areas such as flavouring, fragrances and materials. PMID:25503231

Quasdorf, Kyle W; Overman, Larry E

2014-12-11

381

Biodegradation of rocket propellent waste, ammonium perchlorate  

NASA Technical Reports Server (NTRS)

The impact of the biodegradation rate of ammonium perchlorate on the environment was studied in terms of growth, metabolic rate, and total biomass of selected animal and plant species. Brief methodology and detailed results are presented.

Naqui, S. M. Z.

1975-01-01

382

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2010 CFR

... ). It is prepared by the sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard, white or translucent mass. (b) The ingredient meets the specifications of the Food Chemicals...

2010-04-01

383

Electrochemically and bioelectrochemically induced ammonium recovery.  

PubMed

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ammonium from an ammonium-rich stream is demonstrated using an electrochemical and a bioelectrochemical system. Both systems are controlled by a potentiostat to either fix the current (for the electrochemical cell) or fix the potential of the working electrode (for the bioelectrochemical cell). In the bioelectrochemical cell, electroactive bacteria catalyze the anodic reaction, whereas in the electrochemical cell the potentiostat applies a higher voltage to produce a current. The current and consequent restoration of the charge balance across the cell allow the transport of cations, such as ammonium, across a cation exchange membrane from the anolyte to the catholyte. The high pH of the catholyte leads to formation of ammonia, which can be stripped from the medium and captured in an acid solution, thus enabling the recovery of a valuable nutrient. The flux of ammonium across the membrane is characterized at different anolyte ammonium concentrations and currents for both the abiotic and biotic reactor systems. Both systems are compared based on current and removal efficiencies for ammonium, as well as the energy input required to drive ammonium transfer across the cation exchange membrane. Finally, a comparative analysis considering key aspects such as reliability, electrode cost, and rate is made. This video article and protocol provide the necessary information to conduct electrochemical and bioelectrochemical ammonia recovery experiments. The reactor setup for the two cases is explained, as well as the reactor operation. We elaborate on data analysis for both reactor types and on the advantages and disadvantages of bioelectrochemical and electrochemical systems. PMID:25651406

Gildemyn, Sylvia; Luther, Amanda K; Andersen, Stephen J; Desloover, Joachim; Rabaey, Korneel

2015-01-01

384

Influence of buffer solution composition on drug release from pellets coated with neutral and quaternary acrylic polymers and on swelling of free polymer films  

Microsoft Academic Search

Aqueous dispersions of the acrylic resins poly(ethylacrylate-methylmethacrylate-trimethylammonioethyl methacrylate chloride) (quaternary PMMA, Eudragit RS30D) and poly(ethylacrylate-methylmethacrylate) (neutral PMMA, Eudragit NE30D) were used to cast free films and to coat theophylline pellets. The release of theophylline from pellets coated with Eudragit RS showed a great dependence on the composition of the buffer solution. The highest release rates were observed in formate buffers;

Klaus Knop

1996-01-01

385

The influence of ammonium on nitrate reduction in wheat seedlings  

Microsoft Academic Search

Ammonium markedly inhibited nitrate absorption by nitrogenstarved wheat seedlings but did not decrease the proportion of absorbed nitrate that was reduced. Seedlings high in nitrate (absorbed prior to the experimental periods) reduced similar amounts of this nitrate regardless of whether or not ammonium was present and being absorbed during the period of measurement. Ammonium or products of ammonium assimilation did

P. L. Minotti; Doris Craig Williams; W. A. Jackson

1969-01-01

386

Human Rhesus B and Rhesus C glycoproteins: properties of facilitated ammonium transport in recombinant kidney cells  

PubMed Central

The mammalian Rh (Rhesus) protein family belongs to the Amt/Mep (ammonia transporter/methylammonium permease)/Rh superfamily of ammonium transporters. Whereas RhCE, RhD and RhAG are erythroid specific, RhBG and RhCG are expressed in key organs associated with ammonium transport and metabolism. We have investigated the ammonium transport function of human RhBG and RhCG by comparing intracellular pH variation in wild-type and transfected HEK-293 (human embryonic kidney) cells and MDCK (Madin–Darby canine kidney) cells in the presence of ammonium (NH4+/NH3) gradients. Stopped-flow spectrofluorimetry analysis, using BCECF [2?,7?-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein] as a pH-sensitive probe, revealed that all cells submitted to inwardly or outwardly directed ammonium gradients exhibited rapid alkalinization or acidification phases respectively, which account for ammonium movements in transfected and native cells. However, as compared with wild-type cells known to have high NH3 lipid permeability, RhBG- and RhCG-expressing cells exhibited ammonium transport characterized by: (i) a five to six times greater kinetic rate-constant; (ii) a weak temperature-dependence; and (iii) reversible inhibition by mercuric chloride (IC50: 52 ?M). Similarly, when subjected to a methylammonium gradient, RhBG- and RhCG-expressing cells exhibited kinetic rate constants greater than those of native cells. However, these constants were five times higher for RhBG as compared with RhCG, suggesting a difference in substrate accessibility. These results, indicating that RhBG and RhCG facilitate rapid and low-energy-dependent bi-directional ammonium movement across the plasma membrane, favour the hypothesis that these Rh glycoproteins, together with their erythroid homologue RhAG [Ripoche, Bertrand, Gane, Birkenmeier, Colin and Cartron (2005) Proc. Natl. Acad. Sci. U.S.A. 101, 17222–17227] constitute a family of NH3 channels in mammalian cells. PMID:15929723

Zidi-Yahiaoui, Nedjma; Mouro-Chanteloup, Isabelle; D'Ambrosio, Anne-Marie; Lopez, Claude; Gane, Pierre; Le Van Kim, Caroline; Cartron, Jean-Pierre; Colin, Yves; Ripoche, Pierre

2005-01-01

387

Ionic liquid-based routes to conversion or reuse of recycled ammonium perchlorate.  

PubMed

New, potentially green, and efficient synthetic routes for the remediation and/or re-use of perchlorate-based energetic materials have been developed. Four simple organic imidazolium- and phosphonium-based perchlorate salts/ionic liquids have been synthesized by simple, inexpensive, and nonhazardous methods, using ammonium perchlorate as the perchlorate source. By appropriate choice of the cation, perchlorate can be incorporated into an ionic liquid which serves as its own electrolyte for the electrochemical reduction of the perchlorate anion, allowing for the regeneration of the chloride-based parent ionic liquid. The electrochemical degradation of the hazardous perchlorate ion and its conversion to harmless chloride during electrolysis was studied using IR and (35)Cl NMR spectroscopies. PMID:19902435

Cordes, David B; Smiglak, Marcin; Hines, C Corey; Bridges, Nicholas J; Dilip, Meghna; Srinivasan, Geetha; Metlen, Andreas; Rogers, Robin D

2009-12-14

388

BEETLE RECORDS Late Tertiary and Early Quaternary  

E-print Network

B BEETLE RECORDS Contents Overview Late Tertiary and Early Quaternary Middle Pleistocene of Europe of London, Surrey, UK ª 2007 Elsevier B.V. All rights reserved. The study of fossil beetles (Coleoptera of the world, most recently to Australia, New Zealand, and Japan. Fossil beetle research has led to many

Sheldon, Nathan D.

389

Enantioselective Construction of Cyclic Quaternary Centers: (-)-Mesembrine  

E-print Network

Enantioselective Construction of Cyclic Quaternary Centers: (-)-Mesembrine Douglass F. Taber next needed a dehydration method that would give predominantly the (E)-R, -unsaturated ester from) Gericke, N. P.; Van Wyk, B. E. World Patent 9746234, 1997. (2) For leading references to previous

Taber, Douglass

390

Antibacterial and Hemolytic Activities of Quaternary Pyridinium  

E-print Network

bacteria but not mammalian cells.[2­4] Polymers have been used as antimicrobial agents due commonly used as biocidal agents.[6­15] A number of polymeric disinfectants based on quaternary pyridinium bacteria. Recently, Gao and coworkers synthesized random copolymers of acrylamide and vinyl pyridine

391

Benzyl­tris­[2-(di­benzyl­amino)­eth­yl]ammonium iodide  

PubMed Central

In the title quaternary ammonium salt, C55H61N4 +·I?, all three N,N-di­benzyl­ethanamine, –(CH2)2N(CH2C6H5)2, groups have different conformations. The N—C—C—N torsion angles are significantly different [89.86?(13), 162.61?(10) and 175.70?(10)°] and the dihedral angles between the phenyl rings in these groups are different as well [58.21?(4), 43.73?(4) and 76.72?(5)°]. In the crystal, the I? anions fill empty spaces between the bulky cations. The cations and anions are linked by weak C—H?I inter­actions, forming a chain along [110]. PMID:24526992

Bello, Mollie J.; Brady, Sarah E.; Zakharov, Lev N.; Tyler, David R.

2014-01-01

392

Renal ammonium excretion after an acute acid load: blunted response in uric acid stone formers but not in patients with type 2 diabetes  

PubMed Central

Idiopathic uric acid nephrolithiasis is characterized by elevated urinary net acid excretion and insufficient buffering by ammonium, resulting in excessively acidic urine and titration of the relatively soluble urate anion to insoluble uric acid. Patients with type 2 diabetes have similar changes in urinary pH, net acid excretion, and ammonium in 24-h urine collections at baseline, even after controlling for dietary factors, and are at increased risk for uric acid nephrolithiasis. However, not all patients with type 2 diabetes develop kidney stones, suggesting that uric acid stone formers may have additional urinary defects, perhaps not apparent at baseline. We performed a metabolic study of 14 patients with idiopathic uric acid nephrolithiasis, 13 patients with type 2 diabetes, and 8 healthy control subjects of similar body mass index. After equilibration on a fixed diet for 5 days, subjects were given a single oral acid load (50 meq ammonium chloride), and urine was collected hourly for 4 h. Uric acid stone formers had a lower ammonium excretory response to acute acid loading compared with diabetic and nondiabetic nonstone formers, suggesting that an ammonium excretory defect unique to uric acid stone formers was unmasked by the acid challenge. The Zucker diabetic fatty rat also did not show impaired urinary ammonium excretion in response to acute acid challenge. A blunted renal ammonium excretory response to dietary acid loads may contribute to the pathogenesis of idiopathic uric acid nephrolithiasis. PMID:24026180

Bobulescu, I. Alexandru; Maalouf, Naim M.; Capolongo, Giovanna; Adams-Huet, Beverley; Rosenthal, Tara R.; Moe, Orson W.

2013-01-01

393

Chloride removal from ferrous substrates  

SciTech Connect

Chlorides will be summarized with respect to occurrence, electrolytic confinement of chlorides on pitted steel, action at the steel/paint interface, and removal. Processes which will be discussed for removal are (1) blast cleaning, (2) blast cleaning enhanced with electrode reversal and nocturnal humidity, (3) water spray and water jetting procedures.

Johnson, B. [KTA-Tator, Inc., Pittsburgh, PA (United States)

1998-12-31

394

Molecular Structure of Picryl chloride  

NSDL National Science Digital Library

Picryl chloride is ranked as one of the 100 most commonly found explosive and shock sensitive materials. It is made by reacting 2,4,6 trinitrophenol with thionyl chloride. This highly reactive compound is known to be hazardous and toxic, and to cause liver injury in mice. It is often used as a sensitization agent in mice when their cells undergo hypersensitivity studies.

2002-09-20

395

Synthesis and class III antiarrhythmic activity of (phenylbut-2-enyl)ammonium salts. Effect of conformation on activity.  

PubMed

The syntheses of seven 4-(substituted phenyl)but-2-en(or yn)yl quaternary ammonium salts and four related tertiary amines are described. The Meerwein arylation reaction was the preferred synthetic method for the required intermediate 1-aryl-4-halo-2-butenes (15a-c, 18). In the case of 18, the trans stereochemistry of the Meerwein adduct of 2,3-dimethylbutadiene was established unambiguously by 2D NMR and X-ray studies. The title compounds represent conformationally restricted analogues of the class III antiarrhythmic agent clofilium (1) and exhibit comparable potency and efficacy in the in vitro evaluation using isolated canine Purkinje fibers. These results suggest that the alkylene chain in 1 is extended in the active conformation. Computer-aided conformational analysis (MM2) supports this conclusion. Selective catalytic hydrogen conditions were developed for the conversion of the unsaturated analogue 2 to clofilium (1) with minimal hydrogenolysis of the allylic quaternary ammonium moiety, thus completing a novel and efficient synthesis of this substance. PMID:3735308

Morgan, T K; Wohl, R A; Lumma, W C; Wan, C N; Davey, D D; Gomez, R P; Marisca, A J; Briggs, M; Sullivan, M E; Wong, S S

1986-08-01

396

Crystallization characteristics of ammonium uranyl carbonate (AUC) in ammonium carbonate solutions  

NASA Astrophysics Data System (ADS)

Ammonium carbonate solutions with an excessive amount of NH 3 were produced in a commercial AUC (ammonium uranyl carbonate) conversion plant. In this study the AUC crystals, precipitated with uranyl nitrate and ammonium carbonate solutions prepared in the laboratory, were characterized to determine the feasibility of recycling ammonium carbonate solution. The AUC crystals were easily agglomerated with the increasing concentration of CO 32- and mole ratio of {NH 4+}/{CO 32-} in ammonium carbonate solution. Effects of a mixing system for the solution in the AUC crystallizer and the feed location of the solution on the agglomeration of AUC crystals were also studied along with the effects of agglomerated AUC powders on UO 2 powders. Finally, the feasibility of manufacturing UO 2 fuel with a sintered pellet density of 10.52 g/cm 3, using the AUC powders generated in this experiment, was demonstrated.

Tae-Joon, Kim; Kyung-Chai, Jeong; Jin-Ho, Park; In-Soon, Chang; Cheong-Song, Choi

1994-05-01

397

75 FR 33824 - Barium Chloride From China  

Federal Register 2010, 2011, 2012, 2013

...No. 731-TA-149 (Third Review)] Barium Chloride From China Determination On the...revocation of the antidumping duty order on barium chloride from China would be likely to...Publication 4157 (June 2010), entitled Barium Chloride from China: Investigation...

2010-06-15

398

75 FR 19657 - Barium Chloride From China  

Federal Register 2010, 2011, 2012, 2013

...No. 731-TA-149 (Third Review)] Barium Chloride From China AGENCY: United States...concerning the antidumping duty order on barium chloride from China...revocation of the antidumping duty order on barium chloride from China would be likely...

2010-04-15

399

7 CFR 58.434 - Calcium chloride.  

Code of Federal Regulations, 2011 CFR

...Agriculture 3 2011-01-01 2011-01-01 false Calcium chloride. 58.434 Section 58.434 Agriculture...Quality Specifications for Raw Material § 58.434 Calcium chloride. Calcium chloride, when used, shall meet the...

2011-01-01

400

7 CFR 58.434 - Calcium chloride.  

Code of Federal Regulations, 2010 CFR

...Agriculture 3 2010-01-01 2010-01-01 false Calcium chloride. 58.434 Section 58.434 Agriculture...Quality Specifications for Raw Material § 58.434 Calcium chloride. Calcium chloride, when used, shall meet the...

2010-01-01

401

7 CFR 58.434 - Calcium chloride.  

...Agriculture 3 2014-01-01 2014-01-01 false Calcium chloride. 58.434 Section 58.434 Agriculture...Quality Specifications for Raw Material § 58.434 Calcium chloride. Calcium chloride, when used, shall meet the...

2014-01-01

402

7 CFR 58.434 - Calcium chloride.  

Code of Federal Regulations, 2012 CFR

...Agriculture 3 2012-01-01 2012-01-01 false Calcium chloride. 58.434 Section 58.434 Agriculture...Quality Specifications for Raw Material § 58.434 Calcium chloride. Calcium chloride, when used, shall meet the...

2012-01-01

403

7 CFR 58.434 - Calcium chloride.  

Code of Federal Regulations, 2013 CFR

...Agriculture 3 2013-01-01 2013-01-01 false Calcium chloride. 58.434 Section 58.434 Agriculture...Quality Specifications for Raw Material § 58.434 Calcium chloride. Calcium chloride, when used, shall meet the...

2013-01-01

404

21 CFR 582.6193 - Calcium chloride.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Calcium chloride. 582.6193 Section 582.6193...GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6193 Calcium chloride. (a) Product. Calcium chloride. (b) Conditions of use....

2010-04-01

405

Calcium sulphate in ammonium sulphate solution  

USGS Publications Warehouse

Calcium sulphate, at 25?? C., is two-thirds as soluble in dilute (o.i mol per liter) and twice as soluble in concentrated (3 mois per liter) ammonium sulphate solution as in water. The specific electric conductivity of concentrated ammonium sulphate solutions is lessened by saturating with calcium sulphate. Assuming that dissociation of ammonium sulphate takes place into 2NH4?? and SO4" and of calcium sulphate into Ca and SO4" only, and that the conductivity is a measure of such dissociation, the solubility of calcium sulphate in dilute ammonium sulphate solutions is greater than required by the mass-law. The conductivity of the dilute mixtures may be accurately calculated by means of Arrhenius' principle of isohydric solutions. In the data obtained in these calculations, the concentration of non-dissociated calcium sulphate decreases with increasing ammonium sulphate. The work as a whole is additional evidence of the fact that we are not yet in possession of all the factors necessary for reconciling the mass-law to the behavior of electrolytes. The measurements above described were made in the chemical laboratory of the University of Michigan.

Sullivan, E.C.

1905-01-01

406

Mechanism by which ammonium bicarbonate and ammonium sulfate inhibit mycotoxigenic fungi.  

PubMed Central

In this study we examined the mechanism by which ammonium bicarbonate inhibits mycotoxigenic fungi. Elevated extracellular pH, alone, was not responsible for the antifungal activity. Although conidia of Penicillium griseofulvum and Fusarium graminearum had internal pH (pHi) values as high as 8.0 in buffer at an external pH (pHo) of 9.5, their viability was not markedly affected. The pHi values from conidia equilibrated in glycine-NaOH-buffered treatments without ammonium bicarbonate or ammonium sulfate were similar to values obtained from buffered treatments containing the ammonium salts. Thus, inhibition did not appear to be directly related to increased pHi. Ammonium sulfate in buffered media at pH greater than or equal to 8.7 was as inhibitory as ammonium bicarbonate, but was completely ineffective at pH less than or equal to 7.8. The hypothesis that free ammonia caused the fungal inhibition was tested by using ammonium sulfate as a model for ammonium bicarbonate. Viability, expressed as log CFU/ml, and percent germination of P. griseofulvum and F. graminearum decreased dramatically as the free ammonia concentration increased. Germination rate ratios (the germination rate in buffered ammonium sulfate divided by the germination rate in buffer alone) decreased linearly as the free ammonia concentration increased, further establishing NH3 as the toxic agent. Ammonium bicarbonate inhibits fungi because the bicarbonate anion supplies the alkalinity necessary to establish an antifungal concentration of free ammonia. PMID:2082821

DePasquale, D A; Montville, T J

1990-01-01

407

Benchmark binding energies of ammonium and alkyl-ammonium ions interacting with water. Are ammonium-water hydrogen bonds strong?  

NASA Astrophysics Data System (ADS)

Alkyl-ammonium ion/water interactions are investigated using high level quantum computations, yielding thermodynamics data in good agreement with gas-phase experiments. Alkylation and hydration lead to weaken the NHsbnd O hydrogen bonds. Upon complete hydration by four water molecules, their main features are close to those of the OHsbnd O bond in the isolated water dimer. Energy decomposition analyses indicate that hydration of alkyl-ammonium ions are mainly due to electrostatic/polarization effects, as for hard monoatomic cations, but with a larger effect of dispersion.

Vallet, Valérie; Masella, Michel

2015-01-01

408

Tetra­methyl­ammonium hydrogen terephthalate  

PubMed Central

The asymmetric unit of the title salt, C4H12N+·C8H5O4 ?, contains one half of a tetra­methyl­ammonium cation and one half of a hydrogen terephthalate monoanion. The N atom of the ammonium cation lies on a twofold rotation axis and the centre of mass of the terephthalate anion is on a centre of inversion. In the crystal, the centrosymmetric terephthalate ions are linked by a very short symmetric O—H?O hydrogen bond [O?O = 2.4610?(19)?Å] into a one-dimensional polymeric chain along [1-12]. The tetra­methyl­ammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C—H?O hydrogen bonds, generating a three-dimensional supra­molecular network. The carboxyl­ate groups at both ends of the terephthalate anion are charge-shared with an equal probability of 0.5. PMID:23125785

Dolatyari, Leila; Shoghpour Bayraq, Samad; Sharifi, Sara; Ramazani, Ali; Morsali, Ali; Amiri Rudbari, Hadi

2012-01-01

409

The Optical Constants of Several Atmospheric Aerosol Species: Ammonium Sulfate, Aluminum Oxide, and Sodium Chloride  

Microsoft Academic Search

The optical constants of substances composing atmospheric aerosols are required to evaluate properly the effects of aerosols on the earth's radiation balance. We briefly review techniques for determining optical constants and also discuss pitfalls in using measured optical constants to simulate the optical constants of the real particles found in the atmosphere. We then compile the optical constants of (NH4hSO4,

Owen B. Toon; James B. Pollack; Bishun N. Khare

1976-01-01

410

Surface tension measurements of aqueous ammonium chloride (NH4Cl) in air  

NASA Technical Reports Server (NTRS)

Aqueous NH4Cl's solidification is often used to model metal alloy solidification processes. The present determinations of the magnitude of the variation of aqueous NH4Cl's surface tension as a function of both temperature and solutal concentration were conducted at 3, 24, and 40 C over the 72-100 wt pct water solutal range. In general, the surface tension increases 0.31 dyn/cm per percent decrease in wt pct of water, and decreases 0.13 dyn/cm for each increase in deg C. Attention is given to the experimental apparatus employed.

Lowry, S. A.; Mccay, M. H.; Mccay, T. D.; Gray, P. A.

1989-01-01

411

Absence of power-law scaling in the dendritic crystal growth of ammonium chloride  

NASA Astrophysics Data System (ADS)

We report measurements of the dendritic crystal growth of NH4Cl from supersaturated aqueous solution at small supersaturations, with a goal of understanding the origin of the sidebranching structure. The early detection of sidebranches requires measurements of small deviations from the smooth steady state shape, but that underlying shape is not precisely known at the intermediate distances relevant for sidebranch measurements. We find that no simple power law describes the average crystal shape, the average sidebranch amplitude, or the average sidebranch envelope. Instead, the effective power law exponents appear to increase steadily as a function of distance from the dendritic tip. Comparisons of the amplitude of sidebranches with that predicted by models of noise-driven sidebranching require careful measurements of materials parameters such as the capillary length. Previous published estimates for this material varied by over a factor of 20. We report new measurements of the capillary length and find d0= 0.224 ±0.005;nm. Based on those new measurements, we find that the amplitude of the sidebranches in this system is larger than expected from numerical models.

Dougherty, Andrew

2013-03-01

412

Glutamine synthesis from glucose and ammonium chloride by guinea-pig kidney tubules.  

PubMed Central

1. At a physiological concentration (5 mM), glucose was found to be metabolized by isolated kidney cortex tubules prepared from fed guinea pigs. 2. The release of 14CO2 from [U-14C]glucose indicated that oxidation of the glucose carbon skeleton represented about 50% of the glucose removed; significant amounts of lactate and glutamine also accumulated. 3. Addition of 0.1-10 mM NH4Cl led to a dose-dependent stimulation of glucose metabolism which was accompanied by a large increase in lactate and glutamine accumulation and, to a lesser extent, in glucose oxidation. 4. Comparison of the release of 14CO2 from [1-14C]- and [6-14C]glucose indicates that, in both the absence and the presence of NH4Cl, the pentose phosphate shunt was only a minor pathway of glucose metabolism. 5. The central role of pyruvate carboxylase in the conversion of glucose carbon into glutamine carbon was demonstrated by using a bicarbonate-free medium and measuring the fixation of 14CO2 from [14C]bicarbonate, which was recovered mostly at C-1 of glutamine plus glutamate. 6. The NH4Cl-induced stimulation of glucose removal was secondary not only to increased glutamine synthesis, as shown by the effect of methionine sulphoximine, an inhibitor of glutamine synthetase, but also to the stimulation of phosphofructokinase activity by NH4Cl. 7. Renal arterio-venous difference measurements revealed that, in vivo, the guinea-pig kidney removed glucose from the circulating blood, which suggests that glucose carbon may contribute to the carbon skeleton of the glutamine released by this organ. PMID:8280112

Michoudet, C; Chauvin, M F; Baverel, G

1994-01-01

413

Late-Quaternary recharge determined from chloride in shallow groundwater in the central Great Plains  

USGS Publications Warehouse

An extensive suite of isotopic and geochemical tracers in groundwater has been used to provide hydrologic assessments of the hierarchy of flow systems in aquifers underlying the central Great Plains (southeastern Colorado and western Kansas) of the United States and to determine the late Pleistocene and Holocene paleotemperature and paleorecharge record. Hydrogeologic and geochemical tracer data permit classification of the samples into late Holocene, late Pleistocene-early Holocene, and much older Pleistocene groups. Paleorecharge rates calculated from the Cl concentration in the samples show that recharge rates were at least twice the late Holocene rate during late Pleistocene-early Holocene time, which is consistent with their relative depletion in 16O and D. Noble gas (Ne, Ar, Kr, Xe) temperature calculations confirm that these older samples represent a recharge environment approximately 5??C cooler than late Holocene values. These results are consistent with the global climate models that show a trend toward a warmer, more arid climate during the Holocene. (C) 2000 University of Washington.

Macfarlane, P.A.; Clark, J.F.; Davisson, M.L.; Hudson, G.B.; Whittemore, D.O.

2000-01-01

414

Late-Quaternary Recharge Determined from Chloride in Shallow Groundwater in the Central Great Plains  

NASA Astrophysics Data System (ADS)

An extensive suite of isotopic and geochemical tracers in groundwater has been used to provide hydrologic assessments of the hierarchy of flow systems in aquifers underlying the central Great Plains (southeastern Colorado and western Kansas) of the United States and to determine the late Pleistocene and Holocene paleotemperature and paleorecharge record. Hydrogeologic and geochemical tracer data permit classification of the samples into late Holocene, late Pleistocene-early Holocene, and much older Pleistocene groups. Paleorecharge rates calculated from the Cl concentration in the samples show that recharge rates were at least twice the late Holocene rate during late Pleistocene-early Holocene time, which is consistent with their relative depletion in 16O and D. Noble gas (Ne, Ar, Kr, Xe) temperature calculations confirm that these older samples represent a recharge environment approximately 5°C cooler than late Holocene values. These results are consistent with the global climate models that show a trend toward a warmer, more arid climate during the Holocene.

Macfarlane, P. Allen; Clark, Jordan F.; Davisson, M. Lee; Hudson, G. Bryant; Whittemore, Donald O.

2000-03-01

415

Supercritical water oxidation of ammonium picrate  

SciTech Connect

This study demonstrates the feasibility of using supercritical water oxidation to destroy ammonium picrate. Analyses of reactor effluent composition at various temperatures, residence times, and oxidant concentrations were used to design an improved reactor configuration for achieving destruction with minimum corrosion. The engineering evaluation reactor, a room-sized laboratory scale reactor, was reconfigured to incorporate this design change. Destruction of ammonium picrate with minimized corrosion was demonstrated on this reconfigured reactor. Factors that must be considered in scaling up to pilot plant size are discussed.

LaJeunesse, C.A.; Mills, B.E.; Brown, B.G.

1994-11-01

416

Eutectic composite explosives containing ammonium nitrate  

SciTech Connect

The eutectic of ammonium nitrate (AN), the ammonium salt of 3,5-dinitro-1,2,4-triazole was prepared and its sensitivity and performance were studied. It was found that this AN formulation was unusual in that it performed ideally at small diameter, which indicated that it was a monomolecular explosive. Sensitivity tests included type 12 impact, Henkin thermal and wedge tests, and performance tests included rate stick/plate dent, cylinder, and aquarium tests. Results were compared with calculations, standard explosives, and another eutectic, ethylendiamine dinitrate (EDD)/AN.

Stinecipher, M.M.

1981-01-01

417

On the evaporation of ammonium sulfate solution  

SciTech Connect

Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

2009-07-16

418

On the evaporation of ammonium sulfate solution  

PubMed Central

Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 ± 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor–liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly. PMID:19861551

Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

2009-01-01

419

Index HT -Scoring Sheet A1. 0.1 M Citric Acid pH 3.5, 2.0 M Ammonium Sulfate  

E-print Network

Sodium Chloride B1. 0.1 M Bis-Tris pH 5.5, 0.3 M Magnesium Formate B2. 0.1 M Bis-Tris pH 6.5, 0.5 M.5, 2.0 M Ammonium Sulfate A7. 0.1 M Citric Acid pH 3.5, 3.0 M Sodium Chloride A8. 0.1 M Na Acetate pH 4.5, 3.0 M Sodium Chloride A9. 0.1 M Bis-Tris pH 5.5, 3.0 M Sodium Chloride A10. 0.1 M Bis-Tris pH 6.5, 3

Hill, Chris

420

21 CFR 180.37 - Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin.  

...false Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. 180...37 Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. ...additives saccharin, ammonium saccharin, calcium saccharin, and sodium...

2014-04-01

421

21 CFR 180.37 - Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin.  

Code of Federal Regulations, 2013 CFR

...false Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. 180...37 Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. ...additives saccharin, ammonium saccharin, calcium saccharin, and sodium...

2013-04-01

422

21 CFR 180.37 - Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin.  

Code of Federal Regulations, 2012 CFR

...false Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. 180...37 Saccharin, ammonium saccharin, calcium saccharin, and sodium saccharin. ...additives saccharin, ammonium saccharin, calcium saccharin, and sodium...

2012-04-01

423

Quaternary phylogeography: the roots of hybrid zones  

Microsoft Academic Search

The older history of hybrid zones is explored through consideration of recent advances in climatology, paleontology and phylogeography\\u000a in the Late Cenozoic, particularly the Quaternary Period with its major climatic cycles. The fossil record shows that these\\u000a ice ages and their nested millennial oscillations caused substantial changes in species distributions and with genetic evidence\\u000a allows deduction of refugia and colonization

Godfrey M. Hewitt

2011-01-01

424

Disinfectants - The Rate Matters  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lethal dose curves were calculated for six disinfestants (chlorazene hydrosol, hydrogen dioxide, hydrogen peroxide, iodine, quaternary ammonium chloride, sodium hypochlorite) when applied on seven substrates (galvanized metal, stainless steel, polyethylene ground fabric, polyethylene pot plastic, pr...

425

Near infrared detection of ammonium minerals.  

USGS Publications Warehouse

Diagnostic near-infrared spectral features have been identified for minerals with ammonium (NH4+) bound in the crystal structure. Near-infrared detection of NH4-bearing minerals may provide useful information for prospecting for certain ore deposits and may provide a better understanding of the nitrogen cycle within geologic environments.-from Authors

Krohn, M.D.; Altaner, S.P.

1987-01-01

426

Diamond Head Revisited with Ammonium Dichromate.  

ERIC Educational Resources Information Center

The classroom demonstration using ammonium dichromate to simulate a volcanic eruption can be modified into a more dramatic and accurate representation of the geologic processes involved in the formation of a volcanic crater. The materials, demonstration setup, safety procedures, and applications to instruction are presented. (Author/WB)

Arrigoni, Edward

1981-01-01

427

Mixed Crystals of Ice and Ammonium Fluoride  

Microsoft Academic Search

THE ``inability of forming solid solutions with any compound'' was attributed to water two years ago by Mironov and Bergman1, who refuted previous reports by Giguere and Maass2 and by Kubaschewski and Weber3 of the solubility of hydrogen peroxide in ice. Yet Kathleen Lonsdale4 directed attention to the fact that ice and ammonium fluoride are not only isomorphous but also

R. Brill; S. Zaromb

1954-01-01

428

MECHANISM BY WHICH AMMONIUM FERTILIZERS KILL LARKSPUR  

Technology Transfer Automated Retrieval System (TEKTRAN)

Environmental concerns of using pesticides on public lands have greatly reduced the use of herbicides to control tall larkspur (Delphinium barbeyi). Alternative methods of control have used ammonium sulfate placed in the crown of individual plants to kill larkspur. The objective of this study was ...

429

76 FR 46907 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013

...CBSNews.com, Fertilizer Used in Terror Bombs (Apr. 14, 2004), http...ammonium nitrate can be effectively used in bomb-making. By proposing to include a mixture...under this rule mixtures that terrorist bomb-makers would be most interested in...

2011-08-03

430

Ceric ammonium nitrate promoted oxidation of oxazoles.  

PubMed

The ceric ammonium nitrate promoted oxidations of 4,5-diphenyloxazoles and oxazoles with various substitution patterns have been investigated. This transformation results in the formation of the corresponding imide in good yield and tolerates a wide variety of functional groups and substituents on the oxazole moiety. [reaction: see text]. PMID:17107099

Evans, David A; Nagorny, Pavel; Xu, Risheng

2006-11-23

431

Quaternary Geologic Map of Connecticut and Long Island Sound Basin  

USGS Publications Warehouse

The Quaternary geologic map (sheet 1) and explanatory figures and cross sections (sheet 2) portray the geologic features formed in Connecticut during the Quaternary Period, which includes the Pleistocene (glacial) and Holocene (postglacial) Epochs. The Quaternary Period has been a time of development of many details of the landscape and of all the surficial deposits. At least twice in the late Pleistocene, continental ice sheets swept across Connecticut. Their effects are of pervasive importance to the present occupants of the land. The Quaternary geologic map illustrates the geologic history and the distribution of depositional environments during the emplacement of glacial and postglacial surficial deposits and the landforms resulting from those events.

Stone, Janet Radway; Schafer, John P.; London, Elizabeth Haley; DiGiacomo-Cohen, Mary L.; Lewis, Ralph S.; Thompson, Woodrow B.

2005-01-01

432

An XAFS study of nickel chloride in the ionic liquid 1-ethyl-3-methyl imidazolium chloride/ aluminum chloride  

SciTech Connect

Nickel chloride was studied with cyclic voltammetry and X-ray absorption spectroscopy in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Acidic melts display metal stripping peaks which are not observed in the basic melt. EXAFS analysis shows that the nickel is tetrahedrally coordinated with chloride ions in the basic solution. In the acidic solution the nickel is coordinated by six chloride ions that are also associated with aluminum ions.

D Roeper; G Cheek; K Pandya; W OGrady

2011-12-31

433

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2011 CFR

...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

2011-04-01

434

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2012 CFR

...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

2012-04-01

435

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

2014-04-01

436

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2013 CFR

...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

2013-04-01

437

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2010 CFR

...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

2010-04-01

438

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...glufosinate ammonium, 2-amino-4-(hydroxymethylphosphinyl)butanoic acid monoammonium salt...equivalent of 2-amino-4-(hydroxymethylphosphinyl)butanoic acid, in or on the commodity...glufosinate ammonium, 2-amino-4-(hydroxymethylphosphinyl)butanoic acid monoammonium...

2011-07-01

439

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...glufosinate ammonium, 2-amino-4-(hydroxymethylphosphinyl)butanoic acid monoammonium salt...equivalent of 2-amino-4-(hydroxymethylphosphinyl)butanoic acid, in or on the commodity...glufosinate ammonium, 2-amino-4-(hydroxymethylphosphinyl)butanoic acid monoammonium...

2012-07-01

440

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2012 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2012-10-01

441

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2011 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2011-10-01

442

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2014-10-01

443

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2013 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2013-10-01

444

PREFERENTIAL AMMONIUM UPTAKE DURING GROWTH CYCLE AND IDENTIFICATION OF AMMONIUM TRANSPORTER GENES IN YOUNG PEAR TREES  

Microsoft Academic Search

Five sequences showing homology with gene coding for ammonium (NH 4) transporters of the subfamily AMT1 (AMT1 genes) involved in the nitrogen (N) uptake process were identified in 2-year-old ‘Rocha’ pear\\/BA29 through reverse transcription polymerase chain reaction (RT-PCR) analysis. Multiple AMT1 genes were expressed in each phase of the growth cycle and results suggest that ammonium uptake is conducted by

Mariana Mota; Cláudia B. Neto; António A. Monteiro; Cristina M. Oliveira

2011-01-01

445

Extraction of Rare Earth Metals Using Liquid Surfactant Membranes Prepared by a Synthesized Surfactant  

Microsoft Academic Search

Three surfactants, l-glutamic acid dioleyl ester ribitol (nonionic, 2C18? GE), l-glutamic acid dioleyl ester quaternary ammonium chloride (cationic, 2C18? GEC2QA), and dioleyl dimethyl quaternary ammonium chloride (cationic, 2C18? QA) were synthesized for potential use in liquid membrane operations. These surfactants have strongly hydrophobic, twin oleyl chains as the hydrophobic moiety. Using the synthesized surfactants, extraction of rare earth metals was

Kazuya Uezu; Masahiro Goto; Shinji Irie; Kiyoshi Ikemizu; Fumiyuki Nakashio

1995-01-01

446

40 CFR 721.10430 - Tetra alkyl ammonium salt (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Tetra alkyl ammonium salt (generic). 721.10430 Section 721... § 721.10430 Tetra alkyl ammonium salt (generic). (a) Chemical substance...identified generically as tetra alkyl ammonium salt (PMN P-97-823) is subject to...

2013-07-01

447

21 CFR 172.430 - Iron ammonium citrate.  

...Drugs 3 2014-04-01 2014-04-01 false Iron ammonium citrate. 172.430 Section 172.430...HUMAN CONSUMPTION Anticaking Agents § 172.430 Iron ammonium citrate. Iron ammonium citrate may be safely used in food in...

2014-04-01

448

21 CFR 573.560 - Iron ammonium citrate.  

Code of Federal Regulations, 2012 CFR

...Drugs 6 2012-04-01 2012-04-01 false Iron ammonium citrate. 573.560 Section 573.560...OF ANIMALS Food Additive Listing § 573.560 Iron ammonium citrate. Iron ammonium citrate may be safely used in animal...

2012-04-01

449

21 CFR 172.430 - Iron ammonium citrate.  

Code of Federal Regulations, 2012 CFR

...Drugs 3 2012-04-01 2012-04-01 false Iron ammonium citrate. 172.430 Section 172.430...HUMAN CONSUMPTION Anticaking Agents § 172.430 Iron ammonium citrate. Iron ammonium citrate may be safely used in food in...

2012-04-01

450

21 CFR 573.560 - Iron ammonium citrate.  

Code of Federal Regulations, 2013 CFR

...Drugs 6 2013-04-01 2013-04-01 false Iron ammonium citrate. 573.560 Section 573.560...OF ANIMALS Food Additive Listing § 573.560 Iron ammonium citrate. Iron ammonium citrate may be safely used in animal...

2013-04-01

451

21 CFR 172.430 - Iron ammonium citrate.  

Code of Federal Regulations, 2010 CFR

...Drugs 3 2010-04-01 2009-04-01 true Iron ammonium citrate. 172.430 Section 172.430...HUMAN CONSUMPTION Anticaking Agents § 172.430 Iron ammonium citrate. Iron ammonium citrate may be safely used in food in...

2010-04-01

452

21 CFR 573.560 - Iron ammonium citrate.  

...Drugs 6 2014-04-01 2014-04-01 false Iron ammonium citrate. 573.560 Section 573.560...OF ANIMALS Food Additive Listing § 573.560 Iron ammonium citrate. Iron ammonium citrate may be safely used in animal...

2014-04-01

453

21 CFR 172.430 - Iron ammonium citrate.  

Code of Federal Regulations, 2013 CFR

...Drugs 3 2013-04-01 2013-04-01 false Iron ammonium citrate. 172.430 Section 172.430...HUMAN CONSUMPTION Anticaking Agents § 172.430 Iron ammonium citrate. Iron ammonium citrate may be safely used in food in...

2013-04-01

454

21 CFR 172.430 - Iron ammonium citrate.  

Code of Federal Regulations, 2011 CFR

...Drugs 3 2011-04-01 2011-04-01 false Iron ammonium citrate. 172.430 Section 172.430...HUMAN CONSUMPTION Anticaking Agents § 172.430 Iron ammonium citrate. Iron ammonium citrate may be safely used in food in...

2011-04-01

455

21 CFR 573.560 - Iron ammonium citrate.  

Code of Federal Regulations, 2011 CFR

...Drugs 6 2011-04-01 2011-04-01 false Iron ammonium citrate. 573.560 Section 573.560...OF ANIMALS Food Additive Listing § 573.560 Iron ammonium citrate. Iron ammonium citrate may be safely used in animal...

2011-04-01

456

21 CFR 573.560 - Iron ammonium citrate.  

Code of Federal Regulations, 2010 CFR

...Drugs 6 2010-04-01 2010-04-01 false Iron ammonium citrate. 573.560 Section 573.560...OF ANIMALS Food Additive Listing § 573.560 Iron ammonium citrate. Iron ammonium citrate may be safely used in animal...

2010-04-01

457

40 CFR 721.6070 - Alkyl phosphonate ammonium salts.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Alkyl phosphonate ammonium salts. 721.6070 Section 721.6070 ...721.6070 Alkyl phosphonate ammonium salts. (a) Chemical substances and significant...generically as alkyl phosphonate ammonium salts (PMNs P-93-725 and...

2012-07-01

458

40 CFR 721.6070 - Alkyl phosphonate ammonium salts.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Alkyl phosphonate ammonium salts. 721.6070 Section 721.6070 ...721.6070 Alkyl phosphonate ammonium salts. (a) Chemical substances and significant...generically as alkyl phosphonate ammonium salts (PMNs P-93-725 and...

2010-07-01

459

75 FR 14082 - Ammonium Salts of Fatty Acids (C8  

Federal Register 2010, 2011, 2012, 2013

...EPA-HQ-OPP-2008-0652; FRL-8809-6] Ammonium Salts of Fatty Acids (C 8 -C 18 Saturated...of a tolerance for residues of ammonium salts of fatty acids (C 8 -C 18 saturated...permissible level for residues of ammonium salts of fatty acids (C 8 -C...

2010-03-24

460

STUDIES ON THE EFFECT OF AMMONIUM SULFATE ON CARCINOGENESIS  

EPA Science Inventory

The project was designed to evaluate the health effects of ammonium sulfate (Nh4)2 SO4 inhalation using experimental animals. The questions studied were: (1) Is inhaled ammonium sulfate co-carcinogenic. (2) What are the deposition and clearance patterns of inhaled ammonium sulfat...

461

Thermal Dissociation Kinetics of Solid and Liquid Ammonium Nitrate  

E-print Network

Thermal Dissociation Kinetics of Solid and Liquid Ammonium Nitrate Sergey Vyazovkin,* Jacalyn S and liquid ammonium nitrate. Model-fitting and model-free kinetic methods have been applied to the sets/vaporization. Introduction Ammonium nitrate (AN) finds a widespread applica- tion as both fertilizer and energetic material

Utah, University of

462

Original article Ionic adsorption of ammonium and nitrate on some  

E-print Network

Original article Ionic adsorption of ammonium and nitrate on some animal litters and their role -- Two experiments were carried out to determine the adsorption of ammonium and nitrate on litters (Exp added to the tubes which were incubated for 24 h. Ammonium and nitrate concentrations, and pH, were

Paris-Sud XI, Université de

463

Conversion of Fogwater and Aerosol Organic Nitrogen to Ammonium,  

E-print Network

Conversion of Fogwater and Aerosol Organic Nitrogen to Ammonium, Nitrate, and NOx during Exposure in a slow net loss. Ammonium and nitrate were formed at initial rates on the order of a few micromolar per. Although the formation rates of ammonium and nitrate were relatively small as compared to their initial

Zhang, Qi

464

Novel Microwave-Assisted Synthesis of the Immunomodulator Organotellurium Compound Ammonium Trichloro(dioxoethylene-O,O?)tellurate (AS101)  

PubMed Central

Ammonium trichloro[1,2-ethanediolato-O,O?]-tellurate (AS101) is the most important synthetic Te compound from the standpoint of its biological activity. It is a potent immunomodulator with a variety of potential therapeutic applications and antitumoral action in several preclinical and clinical studies. An experimental design has been used to develop and optimize a novel microwave-assisted synthesis (MAOS) of the AS101. In comparison to the results observed in the literature, refluxing Te(IV) chloride and ethylene glycol in acetonitrile (Method A), or by refluxing Te(IV) chloride and ammonium chloride in ethylene glycol (Method B), it was found that the developed methods in the present work are an effective alternative, because although performance slightly decreases compared to conventional procedures (75% vs. 79% by Method A, and 45% vs. 51% by Method B), reaction times decreased from 4 h to 30 min and from 4 h to 10 min, by Methods A and B respectively. MAOS is proving to be of value in the rapid synthesis of compounds with new and improved biological activities, specially based on the benefit of its shorter reaction times. PMID:24566150

Vázquez-Tato, M. Pilar; Mena-Menéndez, Alberto; Feás, Xesús; Seijas, Julio A.

2014-01-01

465

Proton- and ammonium-sensing by histaminergic neurons controlling wakefulness  

PubMed Central

The histaminergic neurons in the tuberomamillary nucleus (TMN) of the posterior hypothalamus are involved in the control of arousal. These neurons are sensitive to hypercapnia as has been shown in experiments examining c-Fos expression, a marker for increased neuronal activity. We investigated the mechanisms through which TMN neurons respond to changes in extracellular levels of acid/CO2. Recordings in rat brain slices revealed that acidification within the physiological range (pH from 7.4 to 7.0), as well as ammonium chloride (5 mM), excite histaminergic neurons. This excitation is significantly reduced by antagonists of type I metabotropic glutamate receptors and abolished by benzamil, an antagonist of acid-sensing ion channels (ASICs) and Na+/Ca2+ exchanger, or by ouabain which blocks Na+/K+ ATPase. We detected variable combinations of 4 known types of ASICs in single TMN neurons, and observed activation of ASICs in single dissociated TMN neurons only at pH lower than 7.0. Thus, glutamate, which is known to be released by glial cells and orexinergic neurons, amplifies the acid/CO2-induced activation of TMN neurons. This amplification demands the coordinated function of metabotropic glutamate receptors, Na+/Ca2+ exchanger and Na+/K+ ATPase. We also developed a novel HDC-Cre transgenic reporter mouse line in which histaminergic TMN neurons can be visualized. In contrast to the rat, the mouse histaminergic neurons lacked the pH 7.0-induced excitation and displayed only a minimal response to the mGluR I agonist DHPG (0.5 ?M). On the other hand, ammonium-induced excitation was similar in mouse and rat. These results are relevant for the understanding of the neuronal mechanisms controlling acid/CO2-induced arousal in hepatic encephalopathy and obstructive sleep apnoea. Moreover, the new HDC-Cre mouse model will be a useful tool for studying the physiological and pathophysiological roles of the histaminergic system. PMID:22509157

Yanovsky, Yevgenij; Zigman, Jeffrey M.; Kernder, Anna; Bein, Alisa; Sakata, Ichiro; Osborne-Lawrence, Sherri; Haas, Helmut L.; Sergeeva, Olga A.

2012-01-01

466

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed

The objective of this study was to determine if plasticized polyvinyl chloride film would support the growth of any of nine species of fungi. The film was suspended in distilled water with no nutrients or with glucose or ammonium sulfate. Spores of each of the test species were inoculated into the suspension medium, and the mixture was incubated at 30 degrees C for up to 18 weeks. Most species were found to be capable of utilizing the film for carbon or nitrogen when the other nutrient was supplied. Only two species, Aspergillus fischeri and Paecilomyces sp., were found to be capable of utilizing components of the film without added nutrients. Components of the polyvinyl chloride film were then incorporated into mineral salts medium to determine if these components could serve as carbon sources in the presence of ammonium nitrate. The only component found to be utilized by all the fungi as a carbon source was epoxidized oil, a plasticizer-stabilizer. Calcium-zinc stearate was an available carbon source for all except the Penicillium and Verticillium strains. The only other component utilized was a stearamide, which was metabolized solely by the Aspergillus sp. Only the stearamide contained enough nitrogen to serve as a primary source in the film. The compound, however, did not support growth of fungi in the presence of glucose. It was theorized that either the nitrogen of the stearamide was more readily available to the fungi in the whole film due to the presence of trace nutrients or the nitrogen was supplied by exogenous sources. PMID:3707118

Roberts, W T; Davidson, P M

1986-04-01

467

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed Central

The objective of this study was to determine if plasticized