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

Permeation of Chromium(VI) and Rhenium(VII) Oxyanions through Liquid Organic Membranes Facilitated by Quaternary Ammonium Chlorides  

Microsoft Academic Search

An experimental investigation is presented on the facilitated transport of Cr(VI) and Re(VII) oxyanions from aqueous solution into and through organic solutions of quaternary ammonium chlorides as mobile carriers of anions. Trimethyl tallow ammonium chloride (Aliquat 26), dimethyl dicoco ammonium chloride (Aliquat 221), and methyl tricapryl ammonium chloride (Aliquat 336) from General Mills Chemicals have been investigated. Effects of both

Jerzy Strzelbicki; Witold A. Charewicz; Alina Mackiewicz

1984-01-01

2

Ion-pair hollow-fiber liquid-phase microextraction of the quaternary ammonium surfactant dicocodimethylammonium chloride.  

PubMed

A two-phase hollow-fiber (HF) liquid-phase microextraction (LPME) method was developed for determination of a quaternary ammonium compound surfactant, dicocodimethylammonium chloride, in aqueous samples. The porous HF was fixed on a metal rod support and was impregnated with approximately 6.6 microL of organic extractant, which was immobilized in the HF pores. Surfactant extraction was facilitated by addition of carboxylic acid to the sample forming neutral ion pairs with the quaternary ammonium compound. After extraction, the analyte was transferred from the organic extractant in the fiber pores by dissolving the 1-octanol into 100 microL methanol. The methanol extract was analyzed by liquid chromatography-mass spectrometry. The method was optimized (with optimized parameters in brackets) with regard to type of organic extractant (1-octanol), fiber length (2 cm), choice and concentration of anionic carrier (600 microg L(-1) octanoate), procedure of transfer to methanol (15-min sonication), sample volume (250 mL), extraction time (17 h), pH (10), and ionic strength (50 mM carbonate). Aspects influencing repeatability in LPME of (quaternary ammonium) surfactants are discussed. The enrichment factor achieved in 250-mL carbonate buffer was around 400. Due to matrix effects, the enrichment factors achieved when industrial process water was analyzed were 120 or about 30% of that in carbonate buffer. Detection limits of 0.3 microg L(-1) in carbonate buffer and 0.9 microg L(-1) in industrial process water were obtained. If the studied compound is seen as a model substance representing quaternary dialkylated dimethylated ammonium surfactants in general, the developed method may be applied to other quaternary ammonium surfactants. PMID:19050857

Hultgren, Sofie; Larsson, Niklas; Nilsson, Bo F; Jönsson, Jan Ake

2009-02-01

3

Antibacterial activity of gemini quaternary ammonium salts.  

PubMed

A series of gemini quaternary ammonium salts (chlorides and bromides), with various hydrocarbon chain and spacer lengths, were tested. These compounds exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria and were not mutagenic. The strongest antibacterial effect was observed for TMPG-10 Cl (against Pseudomonas aeruginosa ATCC 27853) and TMPG-12 Br (against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 11229 and clinical ESBL(+) isolate 434) surfactants. These compounds inhibited the adhesion of Staphylococcus epidermidis ATCC 35984 to a polystyrene surface and eradicated biofilm formed by P. aeruginosa PAO1. The activity of studied compounds was dependent on hydrocarbon chain length. PMID:24236547

Ob??k, Ewa; Piecuch, Agata; Guz-Regner, Katarzyna; Dworniczek, Ewa

2014-01-01

4

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

5

Antifungal activity of gemini quaternary ammonium salts.  

PubMed

A series of gemini quaternary ammonium chlorides and bromides with various alkyl chain and spacer lengths was synthesized. The most active compounds against fungi were chlorides with 10 carbon atoms within the hydrophobic chain. Among these compounds were few with no hemolytic activity at minimal inhibitory concentrations. None of the tested compounds were cytotoxic and mutagenic. Cationic gemini surfactants poorly reduced the adhesion of microorganisms to the polystyrene plate, but inhibited the filamentation of Candida albicans. One of the tested compounds eradicated C. albicans and Rodotorula mucilaginosa biofilm, what could be important in overcoming catheter-associated infections. It was also shown that gemini surfactants enhanced the sensitivity of C. albicans to azoles and polyenes, thus they might be potentially used in combined therapy against fungi. PMID:23827647

Ob??k, Ewa; Piecuch, Agata; Krasowska, Anna; Luczy?ski, Jacek

2013-12-14

6

21 CFR 184.1138 - Ammonium chloride.  

...sodium chloride and an ammonium salt in solution. The less soluble sodium salt...Ammonium chloride is crystallized from the solution. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981),...

2014-04-01

7

Effect of alkyl quaternary ammonium on processing discoloration of melt-intercalated PVC-montmorillonite composites  

Microsoft Academic Search

The effects of alkyl quaternary ammonium on the processing thermal stability of poly (vinyl chloride)\\/alkyl quaternary ammonium modified montmorillonite (PVC\\/OMMT) composites were investigated. PVC\\/sodium montmorillonite (MMT) composites were prepared for comparison. The intercalated PVC\\/OMMT composites exhibited a non-terminal rheological behavior, and showed better mechanical properties and higher thermal degradation stability than the PVC\\/MMT composites. However, under identical melt processing conditions,

Chaoying Wan; Yong Zhang; Yinxi Zhang

2004-01-01

8

Tri-benzyl-ammonium chloride.  

PubMed

Single crystals of the title salt, C21H21NH(+)·Cl(-), were isolated as a side product from the reaction involving [(C6H5CH2)3NH]2[HPO4] and Sn(CH3)3Cl in ethanol. Both the cation and the anion are situated on a threefold rotation axis. The central N atom in the cation has a slightly distorted tetra-hedral environment, with angles ranging from 107.7 to 111.16?(10)°. In the crystal, the tri-benzyl-ammonium cations and chloride anions are linked through N-H?Cl and C-H?Cl hydrogen bonds, leading to the formation of infinite chains along [001]. The crystal studied was a merohedral twin. PMID:24860409

Diallo, Waly; Diop, Libasse; Plasseraud, Laurent; Cattey, Hélène

2014-05-01

9

Tri-benzyl-ammonium chloride  

PubMed Central

Single crystals of the title salt, C21H21NH+·Cl?, were isolated as a side product from the reaction involving [(C6H5CH2)3NH]2[HPO4] and Sn(CH3)3Cl in ethanol. Both the cation and the anion are situated on a threefold rotation axis. The central N atom in the cation has a slightly distorted tetra­hedral environment, with angles ranging from 107.7 to 111.16?(10)°. In the crystal, the tri­benzyl­ammonium cations and chloride anions are linked through N—H?Cl and C—H?Cl hydrogen bonds, leading to the formation of infinite chains along [001]. The crystal studied was a merohedral twin. PMID:24860409

Diallo, Waly; Diop, Libasse; Plasseraud, Laurent; Cattey, Helene

2014-01-01

10

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

Code of Federal Regulations, 2012 CFR

... false Quaternary ammonium salt of fluorinated alkylaryl amide...9075 Quaternary ammonium salt of fluorinated alkylaryl amide...generically as quaternary ammonium salt of fluorinated alkylaryl...f). (ii) Release to water. Requirements as...

2012-07-01

11

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

Code of Federal Regulations, 2013 CFR

... false Quaternary ammonium salt of fluorinated alkylaryl amide...9075 Quaternary ammonium salt of fluorinated alkylaryl amide...generically as quaternary ammonium salt of fluorinated alkylaryl...f). (ii) Release to water. Requirements as...

2013-07-01

12

Occupational dermatitis to 2,3-epoxypropyl trimethyl ammonium chloride.  

PubMed

4 workers developed hand dermatitis in an automated starch modification process plant. 2,3-epoxypropyl trimethyl ammonium chloride (EPTMAC), a quaternary ammonium compound used as a cationizing chemical, produced allergic reactions in all 4 patients. They had only been in contact with EPTMAC for a short time before developing dermatitis, which indicates that EPTMAC is a strong sensitizer. Immunohistochemistry and electron microscopy showed the features of an allergic patch test. An industrial hygiene project was initiated at the factory to prevent new cases. It revealed many risks of skin contact with the process chemicals. Thus an automated process does not guarantee protection. PMID:2936558

Estlander, T; Jolanki, R; Kanerva, L

1986-01-01

13

Synthesis of biodegradable lauric acid ester quaternary ammonium salt cationic surfactant and its utilization as calico softener  

Microsoft Academic Search

Esterquat cationic surfactant was considered as a new type of biodegradable material utilized as a textile softening agent. In this work, cationic lauric ester quaternary ammonium salt (N-(2-hydroxyl-3-lauryloyloxypropyl) dimethyldodecylammonium chloride (HDAC)) was obtained via reaction between lauric acid and N-(2,3-epoxypropyl) dodecyldimethyl ammonium chloride (DCSA) synthesized from dodecyl dimethylammonium (DTA) and epichlorohydrin (EPIC). The optimum synthesis conditions for DCSA were found

Zongcheng Miao; Jianzhou Yang; Lei Wang; Yong Liu; Long Zhang; Xuelei Li; Lei Peng

2008-01-01

14

Third Order Elastic Constants of Ammonium Chloride  

Microsoft Academic Search

Sound velocities along several directions in ammonium chloride crystals have been measured under hydrostatic and uniaxial pressures by means of an ultrasonic method. Second order elastic constants and their pressure derivatives were evaluated in the vicinity of the phase transition point in disordered phase, and third order elastic constants were calculated from the data. It was found that the absolute

Haruyasu Yamashita; Itaru Tatsuzaki

1984-01-01

15

Quantitation and Purification of Quaternary Ammonium Compounds From Halophyte Tissue  

PubMed Central

A simple and sensitive spectrophotometric assay for quaternary ammonium compounds (QACs) based on Dragendorff's reagent is described. Although not specific for a particular QAC, the assay allows for rapid survey of tissue for QAC content. A separation method for QACs in halophyte tissue containing high levels of cations was developed using ion exchange resins and ninhydrin to remove the amino acid fraction. PMID:16663593

Stumpf, David K.

1984-01-01

16

Quaternary ammonium N,N-dichloroamines as topical, antimicrobial agents.  

PubMed

A series of backbone modified and sulfonic acid replacement analogs of our topical, clinical candidate (iii) were synthesized. Their antimicrobial activities and aqueous stabilities at pH 4 and pH 7 were determined, and has led us to identify quaternary ammonium N,N-dichloroamines as a new class of topical antimicrobial agents. PMID:19362467

Francavilla, Charles; Low, Eddy; Nair, Satheesh; Kim, Bum; Shiau, Timothy P; Debabov, Dmitri; Celeri, Chris; Alvarez, Nichole; Houchin, Ashley; Xu, Ping; Najafi, Ron; Jain, Rakesh

2009-05-15

17

Novel immobilization of a quaternary ammonium moiety on keratin fibers for medical applications.  

PubMed

This paper introduces a new approach for immobilizing a quaternary ammonium moiety on a keratinous substrate for enhanced medical applications. The method involves the generation of thiols by controlled reduction of cystine disulfide bonds in the keratin, followed by reaction with [2-(acryloyloxy)ethyl]trimethylammonium chloride through thiol-ene click chemistry. The modified substrate was characterized with Raman and infrared spectroscopy, and assessed for its antibacterial efficacy and other performance changes. The results have demonstrated that the quaternary ammonium moiety has been effectively attached onto the keratin structure, and the resultant keratin substrate exhibits a multifunctional effect including antibacterial and antistatic properties, improved liquid moisture management property, improved dyeability and a non-leaching characteristic of the treated substrate. PMID:24971553

Yu, Dan; Cai, Jackie Y; Liu, Xin; Church, Jeffrey S; Wang, Lijing

2014-09-01

18

Determination of quaternary ammonium compounds in seawater samples by solid-phase extraction and liquid chromatography–mass spectrometry  

Microsoft Academic Search

A method for the simultaneous determination of two biocidal quaternary ammonium compounds; didecyldimethylammonium chloride (didecyldimethyl quat) and dodecylbenzyldimethylammonium chloride (benzyl quat), in seawater by solid phase extraction (SPE) followed by liquid chromatography–mass spectrometry (LC–MS) was developed. The optimised procedure utilised off-line extraction of the analytes from seawater using polymeric (Strata-X) SPE cartridges. Recoveries ranged from 80 to 105%, with detection

P. Bassarab; D. Williams; J. R. Dean; E. Ludkin; J. J. Perry

2011-01-01

19

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

20

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Modified polymer of vinyl acetate and quaternary ammonium...Chemical Substances § 721.8658 Modified polymer of vinyl acetate and quaternary ammonium...substance identified generically as modified polymer of vinyl acetate and quaternary...

2011-07-01

21

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Modified polymer of vinyl acetate and quaternary ammonium...Chemical Substances § 721.8658 Modified polymer of vinyl acetate and quaternary ammonium...substance identified generically as modified polymer of vinyl acetate and quaternary...

2010-07-01

22

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  

Microsoft Academic Search

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

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

2008-01-01

23

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

24

[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

25

Antibacterial nanocomposite with calcium phosphate and quaternary ammonium.  

PubMed

Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO(4) release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

Cheng, L; Weir, M D; Zhang, K; Xu, S M; Chen, Q; Zhou, X; Xu, H H K

2012-05-01

26

Effects of Quaternary Ammonium Chain Length on Antibacterial Bonding Agents  

PubMed Central

The objectives of this study were to synthesize new quaternary ammonium methacrylates (QAMs) with systematically varied alkyl chain lengths (CL) and to investigate, for the first time, the CL effects on antibacterial efficacy, cytotoxicity, and dentin bond strength of bonding agents. QAMs were synthesized with CL of 3 to 18 and incorporated into Scotchbond Multi-Purpose (SBMP) bonding agent. The cured resins were inoculated with Streptococcus mutans. Bacterial early attachment was investigated at 4 hrs. Biofilm colony-forming units (CFU) were measured after 2 days. With CL increasing from 3 to 16, the minimum inhibitory concentration and minimum bactericidal concentration were decreased by 5 orders of magnitude. Incorporating QAMs into SBMP reduced bacterial early attachment, with the least colonization at CL = 16. Biofilm CFU for CL = 16 was 4 log lower than SBMP control (p < .05). All groups had similar dentin bond strengths (p > .1). The new antibacterial materials had fibroblast/odontoblast viability similar to that of commercial controls. In conclusion, increasing the chain length of new QAMs in bonding agents greatly increased the antibacterial efficacy. A reduction in Streptococcus mutans biofilm CFU by 4 log could be achieved, without compromising bond strength and cytotoxicity. New QAM-containing bonding agents are promising for a wide range of restorations to inhibit biofilms. PMID:23958761

Li, F.; Weir, M.D.; Xu, H.H.K.

2013-01-01

27

Antibacterial Nanocomposite with Calcium Phosphate and Quaternary Ammonium  

PubMed Central

Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO4 release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

Cheng, L.; Weir, M.D.; Zhang, K.; Xu, S.M.; Chen, Q.; Zhou, X.; Xu, H.H.K.

2012-01-01

28

Effects of quaternary ammonium chain length on antibacterial bonding agents.  

PubMed

The objectives of this study were to synthesize new quaternary ammonium methacrylates (QAMs) with systematically varied alkyl chain lengths (CL) and to investigate, for the first time, the CL effects on antibacterial efficacy, cytotoxicity, and dentin bond strength of bonding agents. QAMs were synthesized with CL of 3 to 18 and incorporated into Scotchbond Multi-Purpose (SBMP) bonding agent. The cured resins were inoculated with Streptococcus mutans. Bacterial early attachment was investigated at 4 hrs. Biofilm colony-forming units (CFU) were measured after 2 days. With CL increasing from 3 to 16, the minimum inhibitory concentration and minimum bactericidal concentration were decreased by 5 orders of magnitude. Incorporating QAMs into SBMP reduced bacterial early attachment, with the least colonization at CL = 16. Biofilm CFU for CL = 16 was 4 log lower than SBMP control (p < .05). All groups had similar dentin bond strengths (p > .1). The new antibacterial materials had fibroblast/odontoblast viability similar to that of commercial controls. In conclusion, increasing the chain length of new QAMs in bonding agents greatly increased the antibacterial efficacy. A reduction in Streptococcus mutans biofilm CFU by 4 log could be achieved, without compromising bond strength and cytotoxicity. New QAM-containing bonding agents are promising for a wide range of restorations to inhibit biofilms. PMID:23958761

Li, F; Weir, M D; Xu, H H K

2013-10-01

29

Catalytic performance of quaternary ammonium salts in the reaction of butyl glycidyl ether and carbon dioxide  

Microsoft Academic Search

The synthesis of cyclic carbonate from butyl glycidyl ether (BGE) and carbon dioxide was performed in the presence of quaternary ammonium salt catalysts. Quaternary ammonium salts of different alkyl group (C3, C4, C6 and C8) and anions (Cl?, Br? and I?) were used for this reaction carried out in a batch autoclave reactor at 60–120°C. The catalytic activity increased with

Hye-Young Ju; Mamparambath-Dharman Manju; Kyung-Hoon Kim; Sang-Wook Park; Dae-Won Park

2008-01-01

30

Electrorefining zinc dross in ammoniacal ammonium chloride system  

Microsoft Academic Search

A zinc dross was cast into anodes and electrorefined in an ammoniacal ammonium chloride electrolyte (NH3–NH4Cl) to produce high purity zinc. The influence of several factors, such as zinc concentration, current density and temperature, on cathodic current efficiency and power consumption were investigated. The results indicated that increasing Zn concentration increased the current efficiency, but, very high Zn concentrations affected

Zheng Huajun; Gu Zhenghai; Zheng Yunpeng

2008-01-01

31

Copper and Quaternary Ammonium Cations Exert Synergistic Bactericidal and Antibiofilm Activity against Pseudomonas aeruginosa?  

PubMed Central

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 Cu2+ 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 Cu2+ 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 Cu2+ and QACs do not interact in aqueous solutions, suggesting that each agent exerts microbiological toxicity through independent biochemical routes. Additionally, Cu2+ 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 Cu2+ 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

2008-01-01

32

Alkyl dimethyl benzyl ammonium chloride adsorption mechanism on wood  

Microsoft Academic Search

The adsorption of alkyl dimethyl benzyl ammonium chloride (ADBAC) on wood was investigated. The changes in zeta potential\\u000a curves of wood and ADBAC adsorption with increasing ADBAC concentration were highly correlated and showed two different mechanisms\\u000a for ADBAC adsorption on wood: ion exchange reaction at low concentration and additional aggregation form of adsorption by\\u000a hydrophobic interaction at high concentration. ADBAC

Myung Jae Lee; Paul Cooper

2010-01-01

33

Effects of Quaternary Ammonium Silane Coatings on Mixed Fungal and Bacterial Biofilms on Tracheoesophageal Shunt Prostheses  

PubMed Central

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.

2006-01-01

34

Dual Action Antimicrobials: Nitric Oxide Release from Quaternary Ammonium-Functionalized Silica Nanoparticles  

PubMed Central

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-diazeniumdiolates NO donors to yield dual functional nanomaterials with surface QAs and total NO payloads of ca. 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 Grampositive 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.

2012-01-01

35

Synthesis and immobilization of quaternary ammonium cations in acidic zeolites  

Microsoft Academic Search

A general method for the synthesis of quaternary ammo- nium cations in acidic zeolites by a direct reaction of tertiary amines and alcohols is described. Zeolites and zeolite-related porous solids are ideal inorganic hosts for accommodating a large variety of guest species. 1 Bulky carbon-centered ionic intermediates, such as triar- ylmethyl cations, can be encapsulated within zeolite supercages via a

Wei Wang; Andreas Buchholz; Irina I. Ivanova; Jens Weitkampa; Michael Hunger

2003-01-01

36

Phase Behavior of Bis(Quaternary Ammonium Bromide)\\/Sodium Cholate\\/H2O System  

Microsoft Academic Search

Interactions in an oppositely charged surfactant mixture composed of a gemini surfactant (bis(quaternary ammonium bromide)) and a bile salt (sodium cholate) in water were studied at 30°C. A combination of techniques was used including surface tension, conductometry, light scattering, light microscopy, and microelectrophoretic measurements. A strong dependence of the phase behavior on the molar ratio and actual concentration of surfactants

M. Jendric; M. Vincekovi?; M. Bujan; I. Primoži?

2005-01-01

37

Utility of quercetin for determination of some tertiary amine and quaternary ammonium salts  

Microsoft Academic Search

A simple and sensitive spectrophotometric method for the assay of eight drugs containing quaternary ammonium or tertiary amine moieties is described. The method is based on the interaction of these drugs with quercetin after its oxidation with N-bromosuccinimide (as counter ion) to give highly colored ion-pairing complexes extractable with organic solvents. The absorbances of the colored complexes are measured in

Fardous A. Mohamed; Abdel-Maaboud I. Mohamed; Horria A. Mohamed; Samiha A. Hussein

1996-01-01

38

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

2014-10-28

39

Different Virucidal Activities of Hyperbranched Quaternary Ammonium Coatings on Poliovirus and Influenza Virus  

PubMed Central

Virucidal activity of immobilized quaternary ammonium compounds (IQACs) coated onto glass and plastic surfaces was tested against enveloped influenza A (H1N1) virus and nonenveloped poliovirus Sabin1. The IQACs tested were virucidal against the influenza virus within 2 min, but no virucidal effect against poliovirus was found in 6 h. PMID:22287007

Tuladhar, Era; de Koning, Martijn C.; Fundeanu, Irina; Beumer, Rijkelt

2012-01-01

40

ELECTROSPINNING OF LOW SURFACE ENERGY QUATERNARY AMMONIUM SALT CONTAINING POLYMERS AND THEIR ANTIBACTERIAL ACTIVITY  

Microsoft Academic Search

Antibacterial agent (quaternary ammonium salt) containing perfluorinated polymers had been synthesized at different agent concentrations. The polymers were dissolved in solvent mixture and electrospun, to increase effective surface area, at 12 kV which had resulted nanofibers with diameters as low as 40 nanometers and fluffy structures. The resultant electrospun webs' biocidal activities relative to the solution cast film samples and

Kazim Acatay; Mert Akel

41

Quaternary Ammonium Salts From Hydrolysed Fatty Oil Based on Novel Tertiary Amines Used as Corrosion Inhibitors for Pipelines Carbon Steel at Acid Job in Petroleum Industry  

Microsoft Academic Search

Ten new quaternary ammonium salts were designed and synthesized from hydrolyzed fatty oils; the hydrolysed oils were used as a source of alkyl halides to prepare the quaternary ammonium salts by refluxing the fatty alkyl halide with ethoxylated amines as untraditional 3° amines in acetone. The structure of the prepared quaternary ammonium salts were characterized by FTIR and H NMR

A. M. Al-Sabagh; N. G. Kandile; Nahed Amer; Omaima Ramadan; E. A. Khamis

2011-01-01

42

Quaternary Ammonium Polysaccharides for Gene Delivery Ira Yudovin-Farber,  

E-print Network

and tested for gene transfection. Polycations of dextran grafted with MQ ammonium oligoamines of two to four protein and -Gal encoding for -galactosidase protein transfection on EPC and HEK-293 cell lines, which may result in a higher transfection yield. However, the transfection yields were much lower

Linial, Michal

43

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

44

Adsorption of cholic acid on surface of organosilicas containing chemically bound quaternary ammonium groups  

Microsoft Academic Search

It was found that silica modified with quaternary ammonium groups exhibits higher adsorption properties than cholesteramine,\\u000a a sequestering adsorbent used in medicine for regulating the level of cholic acids in the organism. The constants of ion-exchange,\\u000a aggregation, and stability, as well as the distribution coefficients, for synthesized organosilicas were calculated. It was\\u000a shown that adsorption of cholic acid depends on

N. V. Roik; L. A. Belyakova

2006-01-01

45

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25303389

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

2014-10-01

46

Effects of particle size and chain length on flotation of quaternary ammonium salts onto kaolinite  

NASA Astrophysics Data System (ADS)

Effects of particle size and chain length on flotation of quaternary ammonium salts (QAS) onto kaolinite have been investigated by flotation tests. Dodecyltrimethylammonium chloride (DTAC) and cetyltrimethylammonium chloride (CTAC) were used as collectors for kaolinite in different particle size fractions (0.075 ~ 0.01 mm, 0.045 ~ 0.075 mm, 0 ~ 0.045 mm). The anomalous flotation behavior of kaolinite have been further explained based on crystal structure considerations by adsorption tests and molecular dynamics (MD) simulation. The results show that the flotation recovery of kaolinite in all different particle size fractions decreases with an increase in pH. As the concentration of collectors increases, the flotation recovery increases. The longer the carbon chain of QAS is, the higher the recoveries of coarse kaolinite (0.075 ~ 0.01 mm and 0.045 ~ 0.075 mm) are. But the flotation recovery of the finest kaolinite (0 ~ 0.045 mm) decreases with chain lengths of QAS collectors increasing, which is consistent with the flotation results of unscreened kaolinite (0 ~ 0.075 mm). It is explained by the froth stability related to the residual concentration of QAS collector in mineral pulp. In lower residual concentration, the froth stability becomes worse. Within the range of flotation collector concentration, it's easy of CTAC to be completely adsorbed by kaolinite in the particle size fraction (0-0.045 mm), which led to lower flotation recovery. Moreover, it is interesting that the coarser particle size of kaolinite is, the higher flotation recovery is. The anomalous flotation behavior of kaolinite is rationalized based on crystal structure considerations. The results of MD simulations show that the (001) kaolinite surface has the strongest interaction with DTAC, compared with the (001) face, (010) and (110) edges. On the other hand, when particle size of kaolinite is altered, the number of basal planes and edge planes is changed. It is observed that the finer kaolinite particles size become, the greater relative surface area of edges and the more the number of edges are. It means that fine kaolinite particles have more edges to adsorb fewer cationic colletors than that of coarse kaolinite particles, which is responsible for the poorer floatability of fine kaolinite.

Longhua, Xu; Yuehua, Hu; Faqin, Dong; Hao, Jiang; Houqin, Wu; Zhen, Wang; Ruohua, Liu

2014-05-01

47

Fluoroponytailed crown ethers and quaternary ammonium salts as solid-liquid phase transfer catalysts in organic synthesis.  

PubMed

Fluorous derivatives of dibenzo-18-crown-6 ether were prepared, and then successfully applied in representative solid-liquid phase transfer catalysis reactions, which were performed in standard organic solvents, such as chlorobenzene and toluene, as well as in fluorous solvents, such as perfluoro-1,3-dimethylcyclohexane. It was clearly shown that properly designed fluoroponytailed crown ethers could promote the disintegration of the crystal lattice of alkali salts, and transfer anions from the solid surface into an apolar, non-coordinating perfluorocarbon phase, for phase transfer catalysis reactions in organic synthesis. Furthermore, 3,5-bis(perfluorooctyl)benzyl bromide and triethylamine were reacted under mild conditions to provide an analogue of the versatile phase transfer catalyst, benzyltriethylammonium chloride, containing two fluoroponytails. This fluoroponytailed quaternary ammonium salt was also successfully employed as a catalyst in a variety of organic reactions conducted under solid-liquid phase transfer catalysis conditions, without a perfluorocarbon phase. Thus, being both hydrophobic and lipophobic, fluorous crown ethers and ammonium salts, could be rapidly recovered in quantitative yields, and reused without loss of activity, over several reaction cycles. PMID:21928010

Pozzi, Gianluca; Fish, Richard H

2012-01-01

48

Sonic agglomeration of ammonium chloride aerosols in intense sound fields  

NASA Astrophysics Data System (ADS)

Acoustic coagulations were studied under traveling-wave conditions with the sonic intensity levels ranging from 145 to 1556 dB and frequencies from 600 to 3000 Hz. The aerosols used ammonium chloride with mass concentrations of 2-20 gm/cm/and sizes from 0.06 to 35 micrometers. Experimental results show a bimodal mass distribution for the acoustically agglomerated particles. The agglomeration increases with the sonic frequency, the intensity, the particle size and the mass loading. The acoustic kernels were numerically evaluated scheme was developed, tested, and used to calculate the mass distribution of the acoustically agglomerated particles. A comparison of the experiment with theory shows that the orthokinetic interaction is the dominant mechanism under all the experimental conditions in this study. When the total number of coarse particles (collectors) is small, the measured mass distributions of the agglomerated particles are in good agreement with the numerical calculation. Once the number of collectors becomes large, the experimental data is lower than that as calculated by the theory.

Cheng, M. T.

49

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

PubMed

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 H K

2014-06-01

50

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

51

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

52

Dietary ammonium chloride and the urinary excretion of chlortetracycline and oxytetracycline  

E-print Network

DIETARY AMMONIUM CHLORIDE AND THE URINARY EXCRETION OF CHLORTETRACYCLINE AND OXYTETRACYCLINE A Thesis by Ronald C. Roberts Submitted to the Graduate College of the Texas ARM University iq partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1967 Ma)or Sub)cot; Animal Nutrition DIETARY AMMONIUM CHLORIDE AND THE URINARY EXCRETION OF CHLORTETRACYCLINE AND OXYTETRACYCLINE A Thesis by Ronald C. Roberts Approved as to style and content by: airma o ommi tee ea o...

Roberts, Ronald Curtis

2012-06-07

53

Quaternary ammonium-type gemini surfactants synthesized from oleic acid: aqueous solution properties and adsorption characteristics.  

PubMed

Cationic gemini surfactants having a quaternary ammonium headgroup have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an amide bond, while the quaternary ammonium headgroup is introduced onto the cis double bond of oleic acid. The Krafft temperature of these surfactants drops below room temperature (ca. 25°C) when the counterion is exchanged from Br? to Cl?. The aqueous solution properties of the Cl series of surfactants have been assessed by means of pyrene fluorescence, dynamic light scattering (DLS), and static surface tension measurements. An increased hydrocarbon chain length results in a lower critical micelle concentration (cmc) and a higher adsorption efficiency at the air/aqueous solution interface. Surface tension measurements suggest the formation of premicelles at concentrations below cmc, whereas, above cmc, DLS indicates the formation of micellar aggregates whose diameter ranges from 5 to 10 nm. We, furthermore, characterized the adsorption of these surfactants to the silica/aqueous solution interface and observed their spontaneous adsorption to the solid surface by electrostatic and intermolecular hydrophobic interactions. The combination of soft-contact imaging atomic force microscopy (AFM) and force-curve data suggests bilayer formation above cmc, which is reflective of the large packing parameter of the gemini surfactants. Interestingly, we found the repulsive interaction observed during compression of the adsorbed layer to be relatively weak, as a result of the low adsorption density and/or the loose molecular packing arrangement, which arises from the asymmetric structure. PMID:23823915

Sakai, Kenichi; Saito, Yuki; Uka, Akihito; Matsuda, Wataru; Takamatsu, Yuichiro; Kitiyanan, Boonyarach; Endo, Takeshi; Sakai, Hideki; Abe, Masahiko

2013-01-01

54

Quaternary ammonium promoted ultra selective and sensitive fluorescence detection of fluoride ion in water and living cells.  

PubMed

Highly selective and sensitive fluorescent probes with a quaternary ammonium moiety have been rationally designed and developed for fast and sensitive fluorescence detection of fluoride ion (F(-) from NaF, not TBAF) in aqueous solution and living cells. With the sequestration effect of quaternary ammonium, the detection time was less than 2 min and the detection limit of fluoride ion was as low as 0.57 ppm that is among the lowest detection limits in aqueous solutions of many fluoride fluorescence probes in the literature. PMID:25279810

Li, Long; Ji, Yuzhuo; Tang, Xinjing

2014-10-21

55

Air-ozonolysis to generate contact active antimicrobial surfaces: Activation of polyethylene and polystyrene followed by covalent graft of quaternary ammonium salts.  

PubMed

Air-ozonolysis was revealed as an accessible and effective approach for surface activation and further functionalization of hydrocarbon polymers. Antimicrobial contact active polyethylene (PE) and polystyrene (PS) were designed by generation on their surfaces OH-functional groups and covalent graft of dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (C18-TSA) quaternary ammonium salt. The shortened analog, trimethyl [3-(trimethoxysilyl) propyl] ammonium chloride (C1-TSA), was also covalently attached to the activated PE and PS surfaces. X-ray photoelectron spectroscopy (XPS) and FTIR confirmed the surface modifications. Scanning electron (SEM) and confocal microscopy were utilized to monitor surface morphology and bacteria interactions. The antimicrobial effect of the C18-TSA grafted polymer surfaces was demonstrated on Gram-negative and Gram-positive bacteria species including human pathogen, Salmonella enterica. The shorter C1-TSA grafted polymers did not demonstrate bactericidal activity, suggesting the critical role of the alkyl chain length. The described strategy may establish a new general and safe platform for future development and application of contact active antimicrobial polymers. PMID:25064479

Fadida, Tania; Kroupitski, Yulia; Peiper, Uri M; Bendikov, Tatyana; Sela Saldinger, Shlomo; Poverenov, Elena

2014-10-01

56

Design, synthesis, and application of tartaric acid derived N-spiro quaternary ammonium salts as chiral phase-transfer catalysts†‡  

PubMed Central

A novel class of tartaric acid-derived N-spiro quaternary ammonium salts was synthesised starting from known TADDOLs. These compounds were found to catalyse the asymmetric ?-alkylation of glycine Schiff bases with high enantioselectivities and in good yields. PMID:22038391

Waser, Mario; Gratzer, Katharina; Herchl, Richard; Muller, Norbert

2014-01-01

57

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

58

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

59

Dental primer and adhesive containing a new antibacterial quaternary ammonium monomer dimethylaminododecyl methacrylate  

PubMed Central

Objectives The main reason for restoration failure is secondary caries caused by biofilm acids. Replacing the failed restorations accounts for 50–70% of all operative work. The objectives of this study were to incorporate a new quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) and nanoparticles of silver (NAg) into a primer and an adhesive, and to investigate their effects on antibacterial and dentin bonding properties. Methods Scotchbond Multi-Purpose (SBMP) served as control. DMADDM was synthesized and incorporated with NAg into primer/adhesive. A dental plaque microcosm biofilm model with human saliva was used to investigate metabolic activity, colony-forming units (CFU), and lactic acid. Dentin shear bond strengths were measured. Results Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the new DMADDM were orders of magnitude lower than those of a previous quaternary ammonium dimethacrylate (QADM). Uncured primer with DMADDM had much larger inhibition zones than QADM (p<0.05). Cured primer/adhesive with DMADDM-NAg greatly reduced biofilm metabolic activity (p<0.05). Combining DMADDM with NAg in primer/adhesive resulted in less CFU than DMADDM alone (p<0.05). Lactic acid production by biofilms was reduced by 20-fold via DMADDM-NAg, compared to control. Incorporation of DMADDM and NAg into primer/adhesive did not adversely affect dentin bond strength. Conclusions A new antibacterial monomer DMADDM was synthesized and incorporated into primer/adhesive for the first time. The bonding agents are promising to combat residual bacteria in tooth cavity and invading bacteria at tooth-restoration margins to inhibit caries. DMADDM and NAg are promising for use into a wide range of dental adhesive systems and restoratives. PMID:23353068

Cheng, Lei; Weir, Michael D.; Zhang, Ke; Arola, Dwayne D.; Zhou, Xuedong; Xu, Hockin H. K.

2013-01-01

60

Calcium chloride and ammonium thiosulfate as ammonia volatilization inhibitors for urea fertilizers  

Microsoft Academic Search

Surface?applied urea fertilizers are susceptible to hydrolysis and loss of nitrogen (N) through ammonium (NH3) volatilization when conditions favorable for these processes exist. Calcium chloride (CaCl2) and ammonium thiosulfate (ATS) may inhibit urease activity and reduce NH3 volatilization when mixed with urea fertilizers. The objective of this study was to evaluate the effectiveness of CaCl2 and ATS as urea?N loss

J. J. Sloan; W. B. Anderson

1995-01-01

61

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

62

Synthesis and characterization of chitosan quaternary ammonium salt and its application as drug carrier for ribavirin.  

PubMed

Abstract N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is hydro-soluble chitosan (CS) derivative, which can be obtained by the reaction between epoxypropyl trimethyl ammonium chloride (ETA) and CS. The preparation parameters for the synthesis of HTCC were optimized by orthogonal experimental design. ETA was successfully grafted into the free amino group of CS. Grafting of ETA with CS had great effect on the crystal structure of HTCC, which was confirmed by the XRD results. HTCC displayed higher capability to form nanoparticles by crosslinking with negatively charged sodium tripolyphosphate (TPP). Ribavrin- (RIV-) loaded HTCC nanoparticles were positively charged and were spherical in shape with average particle size of 200?nm. More efficient drug encapsulation efficiency and loading capacity were obtained for HTCC in comparison with CS, however, HTCC nanoparticles displayed faster release rate due to its hydro-soluble properties. The results suggest that HTCC is a promising CS derivative for the encapsulation of hydrophilic drugs in obtaining sustained release of drugs. PMID:24215307

Li, Si-Dong; Li, Pu-Wang; Yang, Zi-Ming; Peng, Zheng; Quan, Wei-Yan; Yang, Xi-Hong; Yang, Lei; Dong, Jing-Jing

2014-11-01

63

Ammonium Chloride and Ammonium Sulfate for Prevention of Parturient Paresis in Dairy Cows1  

Microsoft Academic Search

Forty-eight Holstein cows with two or more previous lactations and no history of parturient paresis were randomly assigned to one of four prepartum diets in a 2 x 2 factorial design to determine the effect of dietary supplementation with ammonium salts and Ca intake on serum Ca concentrations at calving. Four diets provided either 53 g total dietary Ca\\/d or

G. R. Oetzel; J. D. Olson; C. R. Curtis; M. J. Fettman

1988-01-01

64

Isolation and characterization of heterotrophic bacteria able to grow aerobically with quaternary ammonium alcohols as sole source of carbon and nitrogen  

Microsoft Academic Search

The quaternary ammonium alcohols (QAAs) 2,3-dihydroxypropyl-trimethyl-ammonium (TM), dimethyl-diethanol-ammonium (DM) and methyl-triethanol-ammonium (MM) are hydrolysis products of their parent esterquat surfactants, which are widely used as softeners in fabric care. We isolated several bacteria growing with QAAs as the sole source of carbon and nitrogen. The strains were compared with a previously isolated TM-degrading bacterium, which was identified as a representative

Andres Kaech; Nathalie Vallotton; Thomas Egli

2005-01-01

65

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

66

Asymmetric Michael reactions catalyzed by a highly efficient and recyclable quaternary ammonium ionic liquid-supported organocatalyst in aqueous media.  

PubMed

A novel ionic liquid-support organocatalyst, which contains the quaternary ammonium ion moiety, was recently developed and successfully applied to the asymmetric Michael reaction in the presence of a newly developed ionic liquid-supported (ILS) benzoic acid as co-catalyst. For the reactions studied, in which various aldehydes and nitroolefins were examined, excellent diastereo- and enantioselectivities were obtained with low catalyst loading. Also, the catalyst could be recycled for ten times without significant loss of enantioselectivity. PMID:23381599

Ghosh, Subrata K; Qiao, Yupu; Ni, Bukuo; Headley, Allan D

2013-03-21

67

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

68

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

Inacio, Angela S.; Costa, Gabriel N.; Domingues, Neuza S.; Santos, Maria S.; Moreno, Antonio J. M.; Vaz, Winchil L. C.

2013-01-01

69

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

70

Asymmetric phase-transfer catalysis with homo- and heterochiral quaternary ammonium salts: a theoretical study.  

PubMed

A thorough theoretical study of phase-transfer quaternary ammonium catalysts designed by the Maruoka group has been performed in an attempt to gain better understanding of the properties and catalytic behavior of the homo- and heterochiral forms of these systems. The conformationally flexible analogue is found to easily undergo interconversion from the homo- to the heterochiral form driven by the higher thermodynamic stability of the heterochiral isomer and resulting in alternation in catalytic behavior. Theoretical calculations of (1)H NMR spectra of the two isomers for different model systems are in good agreement with the experimental data, allowing us to conclude that the upfield shift of signals for the benzylic protons in the heterochiral form could be explained by an increase in the shielding effect of the aromatic parts of the system around these protons due to the conformational changes. By applying the automated transition state (TS) search procedure for the alkylation of glycine derivatives catalyzed by the homo-/heterochiral form of a conformationally rigid analogue, we were able to locate more than 40 configurations of the TS structures. In brief, the homochiral form was theoretically confirmed to catalyze the formation of the predominant R-product, while for the heterochiral form the catalytic activity is found to depend on two factors: (i) formation of a tight ion pair between the catalyst and the glycine derivative, which results in a decrease in the reaction rate, in agreement with the experimental data, and formation of only the R-product, and (ii) the possibility that the reaction occurs without the initial formation of the ion pair or after its dissociation, in which case the formation of an S-product is predominant. The combined effects of both factors would explain the lower reaction rate and the poor enantioselectivity observed experimentally for the heterochiral form. PMID:24720781

Petrova, Galina P; Li, Hai-Bei; Maruoka, Keiji; Morokuma, Keiji

2014-05-15

71

Synthesis of new antibacterial quaternary ammonium monomer for incorporation into CaP nanocomposite  

PubMed Central

Objectives Composites are the principal material for tooth cavity restorations due to their esthetics and direct-filling capabilities. However, composites accumulate biofilms in vivo, and secondary caries due to biofilm acids is the main cause of restoration failure. The objectives of this study were to: (1) synthesize new antibacterial monomers; and (2) develop nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and antibacterial monomer. Methods Two new antibacterial monomers were synthesized: dimethylaminohexane methacrylate (DMAHM) with a carbon chain length of 6, and dimethylaminododecyl methacrylate (DMADDM) with a chain length of 12. A spray-drying technique was used to make NACP. DMADDM was incorporated into NACP nanocomposite at mass fractions of 0%, 0.75%, 1.5%, 2.25% and 3%. A flexural test was used to measure composite strength and elastic modulus. A dental plaque microcosm biofilm model with human saliva as inoculum was used to measure viability, metabolic activity, and lactic acid production of biofilms on composites. Results The new DMAHM was more potent than a previous quaternary ammonium dimethacrylate (QADM). DMADDM was much more strongly antibacterial than DMAHM. The new DMADDM-NACP nanocomposite had strength similar to that of composite control (p > 0.1). At 3% DMADDM in the composite, the metabolic activity of adherent biofilms was reduced to 5% of that on composite control. Lactic acid production by biofilms on composite containing 3% DMADDM was reduced to only 1% of that on composite control. Biofilm colony-forming unit (CFU) counts on composite with 3% DMADDM were reduced by 2-3 orders of magnitude. Significance New antibacterial monomers were synthesized, and the carbon chain length had a strong effect on antibacterial efficacy. The new DMADDM-NACP nanocomposite possessed potent anti-biofilm activity without compromising load-bearing properties, and is promising for antibacterial and remineralizing dental restorations to inhibit secondary caries. PMID:23768794

Zhou, Chenchen; Weir, Michael D.; Zhang, Ke; Deng, Dongmei; Cheng, Lei; Xu, Hockin H. K.

2013-01-01

72

Inactivation of the alamethicin-induced conductance caused by quaternary ammonium ions and local anesthetics  

PubMed Central

Long alkyl chain quaternary ammonium ions (QA), the local anesthetics (LA) tetracaine and lidocaine, imipramine, and pancuronium cause inactivation of the alamethicin-induced conductance in lipid bilayer membranes. The alamethicin-induced conductance undergoes inactivation only when these amphipathic compounds are added to the side containing alamethicin. The concentration of QA required to cause a given amount of inactivation depends on the length of the hydrocarbon chain and follows the sequence C9 greater than C10 greater than C12 greater than C16. LA and imipramine, in contrast to QA or pancuronium, are able to promote appreciable inactivation only if the pH of the alamethicin-free side is equal to or lower than the pK of these compounds. The membrane permeability to QA, LA, or imipramine is directly proportional to the alamethicin-induced conductance and is larger than the one for potassium. The observed steady state and time-course of the inactivation are well described by a model similar to that proposed by Heyer et al. (1976. J. Gen. Physiol. 67:703--729) and extended for any value of the diffuse double layer potential and for LA and imipramine. In this model QA, LA, or imipramine are able to permeate through the membrane only when the alamethicin-induced conductance is turned on. The amphipathic compounds then bind to the other membrane surface, changing the transmembrane potential and turning the conductance off. For a given concentration of QA, LA, or imipramine the extent of inactivation depends on two factors: first, the binding characteristics of these compounds to the membrane surface and second, their ability to permeate through the membrane when the alamethicin-induced conductance is turned on. The several possible mechanisms of permeation of the amphipathic molecules tested are discussed. PMID:448326

1979-01-01

73

Influence of calcium chloride and ammonium thiosulfate on bermudagrass uptake of urea nitrogen  

Microsoft Academic Search

Calcium chloride (CaCl2) and ammonium thiosulfate (ATS) have demonstrated an ability to inhibit urea hydrolysis and NH3 volatilization. The objective of this experiment was to determine the effect of rainfall and soil drying on the ability of CaCl2 and ATS to increase bermudagrass nitrogen (N) uptake from surface?applied urea. Urea fertilizer, labeled with N and amended with CaCl2 or ATS,

J. J. Sloan; W. B. Anderson

1998-01-01

74

Bermudagrass response to surface-applied urea amended with calcium chloride or ammonium thiosulfate  

Microsoft Academic Search

Surface-applied urea fertilizers are susceptible to hydrolysis and loss of nitrogen (N) through NH3 volatilization when conditions favorable for these processes exist. Calcium chloride (CaCl2) and ammonium thiosulfate (ATS) have been proposed as possible urease and NH3 volatilization inhibitors. The main objective of this research was to compare the efficacy of various N fertilizer sources on bermudagrass yield and fertilizer

John J. Sloan; Warren B. Anderson

2001-01-01

75

Kinetic Study of Polyaniline Film Formation Using Ferric Chloride\\/Ammonium Persulfate as Composite Oxidant  

Microsoft Academic Search

Polyaniline (PANI) was synthesized by in situ emulsion polymerization. The kinetics of the PANI film formation was investigated by the quartz crystal microbalance technique (QCM). PANI film doped with dodecylbenzenesulfonic acid (DBSA) was synthesized by emulsion polymerization using ferric chloride\\/ammonium persulfate (FeCl3\\/APS) as composite oxidant in the presence of a constant (0.4 T) magnetic field (MF). The results showed that the

Wen-Yi Su; Feng-Yan Liang; Li Ma

2012-01-01

76

Solubility of hydrogen sulfide in aqueous solutions of the single salts sodium sulfate, ammonium sulfate, sodium chloride, and ammonium chloride at temperatures from 313 to 393 K and total pressures up to 10 MPa  

SciTech Connect

New experimental results for the solubility of hydrogen sulfide in aqueous solutions of the single salts sodium sulfate, ammonium sulfate, sodium chloride, and ammonium chloride at temperatures from 313 to 393 K and total pressures up to 10 MPa are reported. As in the salt-free system, a second-hydrogen sulfide-rich--liquid phase is observed at high hydrogen sulfide concentrations. A model to describe the phase equilibrium is presented. Calculations are compared to the new experimental data.

Xia, J.; Kamps, A.P.S.; Rumpf, B.; Maurer, G.

2000-04-01

77

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)...

2011-04-01

78

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)...

2013-04-01

79

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)...

2014-04-01

80

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)...

2012-04-01

81

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

82

The Effect of Continuous and Pulse Dose Ammonium Chloride Regimens on the Urine pH of Goats  

E-print Network

i THE EFFECT OF CONTINUOUS AND PULSE DOSE AMMONIUM CHLORIDE REGIMENS ON THE URINE PH OF GOATS A Thesis by PHILIPPA MAY SPRAKE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 2012 Major Subject: Biomedical Sciences ii The effect of continuous and pulse dose ammonium chloride regimens on the urine pH of goats. Copyright...

Sprake, Philippa May

2012-10-19

83

Reversible Swelling of Chitosan and Quaternary Ammonium Modified Chitosan Brush Layers: Effect of pH and Counter Anion Size and Functionality  

PubMed Central

This study investigates the swelling of grafted polycationic brushes as a function of pH and anion type. The brushes are chitosan (CH) and chitosans with 27% and 51% degree of substitution (DS) of quaternary ammonium salt, denoted as CH-Q25 and CH-Q50, respectively. The water content and swelling behaviors are monitored using in situ quartz-crystal microbalance with dissipation (QCM-D). The pH varies from ~3.5 to 8.5, and the counter anion types include chloride, acetate, and citrate. At fixed pH, the water content and brush swelling increase as the DS increases. Whereas the CH-Q50 brush layer shows symmetric swelling with a minimum near pH = 4.5, the swelling of CH and CH-Q25 is relatively constant as pH decreases from 8.2 to 5.5, and then begins to increase near pH 4. These studies indicate that the symmetric swelling of CH-Q50 is likely attributed to increasing protonation of primary amines for pH values below pH 6.5 and the quaternary ammonium salts above pH 6.5. At pH 4, the swelling of the CH brush increases upon exchanging the smaller chloridewith a bulkier acetate anion, which is less effective at screening intra/inter molecular repulsion. In contrast, upon exchanging the acetate with trifunctional citrate, CH and CH-Q25 brushes collapse by 53 and 42%, respectively, because the citrate forms ionic cross-links. To test antibacterial properties, silicon oxide, CH and CH-Q50 brush layers are exposed to 107–108 cfu/ml of S. aureus for two days at 37 °C and exposed to stepped shear stresses in 2 min intervals. Whereas an S. aureus biofilm adheres strongly to silicon oxide and CH for stresses up to 12 dyne/cm2, biofilms on CH-Q50 detach at a relatively low shear stress, 1.5 dyne/cm2. Due to their high degree of swelling that can be tuned via pH, counterion size and type, chitosan and quaternary modified chitosans have potential as responsive coatings for applications including MEMS/NEMS devices and drug eluting implants. PMID:23209343

Lee, Hyun-Su; Yee, Michael Q.; Eckmann, Yonaton Y.; Hickok, Noreen J.; Eckmann, David M.; Composto, Russell J.

2012-01-01

84

Hygroscopicity and evaporation of ammonium chloride and ammonium nitrate: Relative humidity and size effects on the growth factor  

NASA Astrophysics Data System (ADS)

The hygroscopicity and evaporation of ammonium chloride and ammonium nitrate in the size range of 40-200 nm are investigated from 20% to 86% RH using a self-assembled hygroscopic tandem differential mobility analyzer (H-TDMA) system. The hygroscopicity of 100 nm (NH 4) 2SO 4 is also measured for comparison. The measured hygroscopic growth factors (GFs) of (NH 4) 2SO 4 agree well with the theoretical Köhler curve. Great discrepancies between the measured GFs and the theoretical values are observed for NH 4Cl and NH 4NO 3 due to their volatile properties. The evaporation of NH 4Cl below the deliquescence RH (DRH) is significantly promoted while RH increases. Similar trend is also observed for NH 4NO 3 particle less than 50 nm. The proposed mechanism suggests that the increase of RH alters the chemical equilibrium among NH 4X (s) (X represents Cl - or NO 3-), NH 3(g) and HX (g), i.e., NHX?NH+HX, by converting NH 3(g) and HX (g) into NH 3·nH 2O and HX·nH 2O, which accelerates the evaporation of NH 4X (s). When RH is higher than the DRH, the GFs of NH 4X increase with initial particle size ( D0) throughout the investigated size range. In this study, the iso-GF curves are also drawn to illustrate the effects of D0 and RH on the GFs. Different from (NH 4) 2SO 4, NaCl, Na 2SO 4 and NaNO 3, the GFs of NH 4X are more sensitive to D0 than RH due to the unique volatility of NH 4Cl and NH 4NO 3 particles.

Hu, Dawei; Chen, Jianmin; Ye, Xingnan; Li, Ling; Yang, Xin

2011-05-01

85

Metabolites and dead-end products from the microbial oxidation of quaternary ammonium alcohols  

Microsoft Academic Search

Methyl-triethanol-ammonium originates from the hydrolysis of the parent esterquat surfactant, which is used as softener in fabric care. The initial steps of the catabolism were investigated in cell-free extracts of the bacterial strain MM 1 able to grow with methyl-triethanol-ammonium as sole source of carbon, energy and nitrogen. The initial degradation of methyl-triethanol-ammonium is an enzymatically catalyzed reaction, located in

Andres Kaech; Martina Hofer; Daniel Rentsch; Christian Schnider; Thomas Egli

2005-01-01

86

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

87

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

88

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

89

Detection of singly- and doubly-charged quaternary ammonium drugs in equine urine by liquid chromatography/tandem mass spectrometry.  

PubMed

Quaternary ammonium drugs (QADs) are anticholinergic agents some of which are known to have been abused or misused in equine sports. A recent review of literature shows that the screening methods reported thus far for QADs mainly cover singly-charged QADs. Doubly-charged QADs are extremely polar substances which are difficult to be extracted and poorly retained on reversed-phase columns. It would be ideal if a comprehensive method can be developed which can detect both singly- and doubly-charged QADs. This paper describes an efficient liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous detection and confirmation of 38 singly- and doubly-charged QADs at sub-parts-per-billion (ppb) to low-ppb levels in equine urine after solid-phase extraction. Quaternary ammonium drugs were extracted from equine urine by solid-phase extraction (SPE) using an ISOLUTE(®) CBA SPE column and analysed by LC/MS/MS in the positive electrospray ionisation mode. Separation of the 38 QADs was achieved on a polar group embedded C18 LC column with a mixture of aqueous ammonium formate (pH 3.0, 10 mM) and acetonitrile as the mobile phase. Detection and confirmation of the 38 QADs at sub-ppb to low-ppb levels in equine urine could be achieved within 16 min using selected reaction monitoring (SRM). Matrix interference of the target transitions at the expected retention times was not observed. Other method validation data, including precision and recovery, were acceptable. The method was successfully applied to the analyses of drug-administration samples. PMID:22123117

Ho, Emmie N M; Kwok, W H; Wong, April S Y; Wan, Terence S M

2012-01-13

90

Antioxidant Potential of Momordica charantia in Ammonium Chloride-induced Hyperammonemic Rats.  

PubMed

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

2010-01-01

91

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

92

Cotton gauze bearing non-diffusible quaternary ammonium salts and featuring anti-microbial activity: An example of single-use articles tailored to self-sterilize  

E-print Network

Cotton gauze bearing non-diffusible quaternary ammonium salts and featuring anti-microbial activity envisaged in which single-use cotton gauze could be chemically tailored to display anti-microbial activity as AEM 5700, into the cotton matrix and polymerizing the monomers about the fibers. In a second approach

Taralp, Alpay

93

Quaternary Ammonium Salts from Hydrolyzed Fatty Oil Based on Novel Tertiary Amines Used as Corrosion Inhibitors for Pipelines Carbon Steel at Acid Job in Petroleum Industry  

Microsoft Academic Search

Ten new quaternary ammonium salts (QASs) were designed and synthesized from hydrolyzed fatty oils; the hydrolyzed oils were used as a source of alkyl halides to prepare the QASs by refluxing the fatty alkyl halide with ethoxylated amines as untraditional 3° amines in acetone. The structure of the prepared QASs were characterized by FTIR and H NMR spectroscopy. The prepared

A. M. Al-Sabagh; N. G. Kandile; Nahed Amer; Omaima Ramadan; E. A. Khamis

2012-01-01

94

Effects of Freezing, Drying, Ultraviolet Irradiation, Chlorine, and Quaternary Ammonium Treatments on the Infectivity of Myxospores of Myxobolus cerebralis for Tubifex tubifex  

Microsoft Academic Search

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°C or ?80°C for a period of 7 d or 2 months eliminated infectivity as assessed

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

2008-01-01

95

Quantitative structure-activity relationship (QSAR) study of toxicity of quaternary ammonium compounds on Chlorella pyrenoidosa and Scenedesmus quadricauda.  

PubMed

The acute toxicity of 13 quaternary ammonium compounds (QACs) to Chlorella pyrenoidosa and Scenedesmus quadricauda was investigated in the present study. Significant inhibition on algae biomass was observed and 96 h EC(50)-value of 13 QACs was tested. Sixteen physicochemical and quantum chemical parameters of the QACs were calculated using the semi-empirical MOPAC AMI method. The multiple linear regression (MLR) was employed to derive the quantitative structure-activity relationship (QSAR) models, by which the calculated parameters were correlated to the toxicity of QACs on the two green algaes. Results showed that the alkyl chain lengths (CL) and total connectivity (T(Con)) were the main descriptors in governing the log (1/EC(50)) values of the QACs in the two QSAR models. The two models had high predictive ability and stability, and two parameters were proved to have the general applicability in QSAR study of QACs congeners. PMID:22014469

Jing, Guohua; Zhou, Zuoming; Zhuo, Jing

2012-01-01

96

Micelle assisted thin-film solid phase microextraction: a new approach for determination of quaternary ammonium compounds in environmental samples.  

PubMed

Determination of quaternary ammonium compounds (QACs) often is considered to be a challenging undertaking owing to secondary interactions of the analytes' permanently charged quaternary ammonium head or hydrophobic tail with the utilized labware. Here, for the first time, a micelle assisted thin-film solid phase microextraction (TF-SPME) using a zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) as a matrix modifier is introduced as a novel approach for in-laboratory sample preparation of the challenging compounds. The proposed micelle assisted TF-SPME method offers suppression/enhancement free electrospray ionization of analytes in mass spectrometric detection, minimal interaction of the micelles with the TF-SPME coating, and chromatographic stationary phase and analysis free of secondary interactions. Moreover, it was found that the matrix modifier has multiple functions; when its concentration is found below the critical micelle concentration (CMC), the matrix modifier primarily acts as a surface deactivator; above its CMC, it acts as a stabilizer for QACs. Additionally, shorter equilibrium extraction times in the presence of the modifier demonstrated that micelles also assist in the transfer of analytes from the bulk of the sample to the surface of the coating. The developed micelle assisted TF-SPME protocol using the 96-blade system requires only 30 min of extraction and 15 min of desorption. Together with a conditioning step (15 min), the entire method is 60 min; considering the advantage of using the 96-blade system, if all the blades in the brush are used, the sample preparation time per sample is 0.63 min. Moreover, the recoveries for all analytes with the developed method were found to range within 80.2-97.3%; as such, this method can be considered an open bed solid phase extraction. The proposed method was successfully validated using real samples. PMID:25148600

Boyac?, Ezel; Pawliszyn, Janusz

2014-09-16

97

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

98

Conditions for defect-free solidification of aqueous ammonium chloride in a quasi two-dimensional directional solidification facility  

Microsoft Academic Search

Experimental and theoretical approaches to the problem of the solidification of a binary melt are presented. We describe a series of experiments in which aqueous solutions of ammonium chloride of above eutectic composition are cooled from below in a Hele–Shaw cell that is translated downwards at a constant rate. A mushy layer of solid dendrites bathed in a salt-depleted interstitial

S. H. Whiteoak; Herbert E. Huppert; M. Grae Worster

2008-01-01

99

New quaternary ammonium camphor derivatives and their antiviral activity, genotoxic effects and cytotoxicity.  

PubMed

The synthesis and biological evaluation of a novel series of dimeric camphor derivatives are described. The resulting compounds were studied for their antiviral activity, cyto- and genotoxicity. Compounds 3a and 3d in which the quaternary nitrogen atoms are separated by the C5H10 and ?9H18 aliphatic chain, exhibited the highest efficiency as an agent inhibiting the reproduction of the influenza virus A(H1N1)pdm09. The cytotoxicity data of compounds 3 and 4 revealed their moderate activity against malignant cell lines; compound 3f had the highest activity for the CEM-13 cells. These results show close agreement with the data of independent studies on toxicity of these compounds, in particular that the toxicity of compounds strongly depends on spacer length. PMID:23993669

Sokolova, Anastasiya S; Yarovaya, Capital O Cyrilliclga I; Shernyukov, Capital A Cyrillicndrey V; Pokrovsky, Capital Em Cyrillicichail A; Pokrovsky, Capital A Cyrillicndrey G; Lavrinenko, Valentina A; Zarubaev, Vladimir V; Tretiak, Tatiana S; Anfimov, Pavel M; Kiselev, Oleg I; Beklemishev, Anatoly B; Salakhutdinov, Nariman F

2013-11-01

100

Preparation and characterisation of anion exchangers with dihydroxy-containing alkyl substitutes in the quaternary ammonium functional groups.  

PubMed

Novel poly(styrene-divinylbenzene) (PS-DVB) based anion exchangers having one and two (2,3-dihydroxypropyl) substitutes in the quaternary ammonium functional groups are prepared and characterised by ion chromatography (IC). The introduction of bulky and hydrophilic substitutes to the anion-exchange groups allows the elimination of non-ionic interactions between the polarisable anions and the aromatic rings from the matrix and the improvement of separation selectivity as compared with the traditional trimethylammonium (TMA) functionalised ion exchangers. The synthesis of the ion exchangers includes acylation of PS-DVB particles with acetic anhydride followed by reductive amination either with methylamine hydrochloride or dimethylamine and further alkylation with oxiranes under varied conditions. The ion exchange selectivity and separation efficiency of nine adsorbents having different structure of bonded groups, ion exchange capacity (9-98?equiv.g(-1)) or particle size is studied for model mixture of inorganic anions (F(-), Cl(-), NO2(-), Br(-), NO3(-), HPO4(2-) and SO4(2-)) using carbonate and hydroxide eluents. The adsorbents with more hydrophilic substitutes provided superior columns efficiencies and better peak symmetry as compared with analogues having hydrophobic functional groups. The calculated values of column efficiencies for polarisable NO3(-) and HPO4(2-) are 18,500 and 29,000N/m, respectively, for anion-exchanger, having N-methyl-N',N?-di-(2,3-dihydroxypropyl)ammonium groups which is significantly higher than 1800 and 12,000N/m obtained for these anions with anion exchanger bearing TMA functional groups. PMID:24309716

Zatirakha, A V; Smolenkov, A D; Pirogov, A V; Nesterenko, P N; Shpigun, O A

2014-01-01

101

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

102

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  

Microsoft Academic Search

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

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

2008-01-01

103

Effect of the steric accessibility of the exchange site in long-chain quaternary ammonium salts on the anion-exchange extraction of divalent ions  

Microsoft Academic Search

The constants of anion-exchange extraction of divalent ions by quaternary ammonium salts of various structures were determined.\\u000a The exchange constants depend significantly on steric accessibility of the exchange site. For the exchange of small-size anions,\\u000a the affinity of the ion exchanger for divalent ions is higher than for monovalent ions. For large divalent anions, the exchange\\u000a constant may increase or

V. V. Egorov; E. M. Rakhman’ko; E. V. Pomelenok; E. B. Okaev

2006-01-01

104

Investigation of double bond conversion, mechanical properties, and antibacterial activity of dental resins with different alkyl chain length quaternary ammonium methacrylate monomers (QAM)  

Microsoft Academic Search

In order to endow dental resin with antibacterial activity, a series of antibacterial quaternary ammonium methacrylate monomers (QAM) with different substituted alkyl chain length (from 10 to 18) were incorporated into commonly used 2,2-bis[4-(2?-hydroxy-3?-methacryloyloxy-propoxy)-phenyl]propane (Bis-GMA)\\/triethyleneglycol dimethacrylate (TEGDMA) (50?wt\\/50?wt) dental resin as immobilized antibacterial agents. Double bond conversion (DC), flexural strength (FS) and modulus (FM), and young and mature biofilms inhibition

Jingwei He; Eva Söderling; Pekka K. Vallittu; Lippo V. J. Lassila

2012-01-01

105

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

Rodriguez-Blanco, Arturo; Lemos, Manuel L.

2012-01-01

106

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

107

Synthesis, characterization and thermal properties of small R2R?2N+X--type quaternary ammonium halides  

NASA Astrophysics Data System (ADS)

Twenty-one R2R'2N +X- -type ( R=methyl or ethyl, R'=alkyl, X=Br or I) quaternary ammonium (QA) halides have been prepared by using a novel one-pot synthetic route in which a formamide (dimethyl-, diethylformamide, etc.) is treated with alkyl halide in the presence of sodium or potassium carbonate. The formation of QA halides was verified with 1H-NMR, 13C-NMR, MS and elemental analysis. The crystal structures of four QA halides (two bromide and two iodide) were determined using X-ray single crystal diffraction, and the powder diffraction method was used to study the structural similarities between the single crystal and microcrystalline bulk material. The thermal properties of all compounds were studied using TG/DTA and DSC methods. The smallest compounds decomposed during or before melting. The decreasing trend of melting points was observed when the alkyl chain length was increased. The liquid ranges of 120-180 °C were observed for compounds with 5-6 carbon atoms in the alkyl chain. The low melting points and wide liquid ranges suggest potential applicability of these compounds for example as ionic liquids precursors.

Busi, Sara; Lahtinen, Manu; Mansikkamäki, Heidi; Valkonen, Jussi; Rissanen, Kari

2005-06-01

108

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

109

Quaternary ammonium compounds in urban estuarine sediment environments--a class of contaminants in need of increased attention?  

PubMed

The distributions of wastewater-derived quaternary ammonium compounds (QACs) were determined in surficial sediments (n = 47) collected from the urbanized lower Hudson River basin. The most abundant class of QACs were dialkyldimethylammonium compounds (DADMACs, with C8 to C18 carbon chain lengths; median ?DADMAC = 26 ?g/g), followed by benzylalkyldimethylammonium compounds (BAC, C12-C18; 1.5 ?g/g), and alkyltrimethylammonium compounds (ATMAC, primarily C16 and C18; 0.52 ?g/g). The concentrations of total QACs are higher than those of other conventional organic contaminants determined on the same samples (e.g., median ?PAH level of 2.1 ?g/g). Comparatively high concentrations, correlations with sewage derived contaminants, and the relatively constant compositions of QACs observed over large areas suggest that many sediment-sorbed QACs can be relatively persistent in receiving waters. Unusually large concentration-dependent sorption is considered as a mechanism that likely affects persistence of these intrinsically biodegradable chemicals under field conditions. There has been comparatively little field-based research on these classes of cationic surfactants; given the levels of QACs observed here, it is suggested that further investigation is warranted. PMID:20804121

Li, Xiaolin; Brownawell, Bruce J

2010-10-01

110

Effects of ionization mode on charge-site-remote and related fragmentation reactions of long-chain quaternary ammonium ions.  

PubMed

Comparison of collisionally activated fragment spectra of long-chain quaternary ammonium ions, formed by liquid-assisted secondary ion mass spectrometry (LSIMS) and electrospray ionization (ESI), shows the latter are dominated by radical cations while the former yield mainly even-electron charge-site-remote (CSR) fragments, similar to the report for different precursors by Cheng et al., J. Am. Soc. Mass Spectrom. 1998, 9, 840. Here, mixed-site fragmentation products (formal loss of a radical directly bonded to the nitrogen plus a radical derived from the long chain) are of comparable importance for both ionization techniques. These observations are difficult to understand if the CSR ions are formed by a concerted rearrangement-elimination reaction, since precollision internal energies of the ESI ions are much lower than those of the ions from LSIMS. Alternatively, if one discards the concerted mechanism for high-energy CA, and assumes that the even-electron fragments are predominantly formed via homolytic bond cleavage, the colder radical cations from ESI survive to the detector while the more energized counterparts from LSIMS preferentially lose a hydrogen atom to yield the CSR ions, as proposed by Wysocki and Ross (Int. J. Mass Spectrom. Ion Processes 1991, 104, 179). The present work also attempts to reconcile discrepancies involving critical energies and known structures for neutral fragments. PMID:11349955

Seto, C; Grossert, J S; Waddell, D S; Curtis, J M; Boyd, R K

2001-05-01

111

Integrating conjugative elements as vectors of antibiotic, mercury, and quaternary ammonium compound resistance in marine aquaculture environments.  

PubMed

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; Osorio, Carlos R

2012-05-01

112

Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.  

PubMed

A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. PMID:24642395

Sutherland, K; del Río, J C

2014-04-18

113

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

114

Surface chemical study on the covalent attachment of hydroxypropyltrimethyl ammonium chloride chitosan to titanium surfaces  

NASA Astrophysics Data System (ADS)

An anti-microbial and bioactive coating could not only reduce the probability of infection related to titanium implants but also support the growth of surrounding osteogenic cells. Our previous study has showed that hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with a DS (degrees of substitution) of 18% had improved solubility and significantly higher antibacterial activities against three bacteria which were usually associated with infections in orthopaedics. In the current study, HACC with a DS of 18% coating was bonded to titanium surface by a three-step process. The titanium surface after each individual reaction step was analyzed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection (ATR) of Fourier-transformed infrared (FT-IR) spectroscopy. The XPS results demonstrated that there were great changes in the atomic ratios of C/Ti, O/Ti, and N/Ti after each reaction step. The XPS high resolution and corresponding devolution spectra of carbon, oxygen, nitrogen, and titanium were also in good coordination with the anticipated reaction steps. Additionally, the absorption bands around 3365 cm -1 (-OH vibration), 1664 cm -1 (Amide I), 1165 cm -1 ( ?as, C-O-C bridge), and the broad absorption bands between 958 cm -1 and 1155 cm -1 (skeletal vibrations involving the C-O stretching of saccharide structure of HACC) verified that HACC was successfully attached to titanium surface.

Xu, Xiaofen; Wang, Ling; Guo, Shengrong; Lei, Lei; Tang, Tingting

2011-10-01

115

Kinetics of emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride and acrylamide with gamma rays  

NASA Astrophysics Data System (ADS)

Inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride with acrylamide has been studied with gamma ray dilatometrically. Aqueous monomer solutions were emulsified in kerosene with a blend of two surfactants (Span80 and OP10). The gel effect is evident from the increase of the molecular weight with conversion and also from the percentage conversion versus time curves. Monomer reactivity ratios have been derived as rAM = 0.23 and rDMC = 1.40 at pH 6.8. Initial emulsions and final inverse latexes displayed the same broad size distribution. The effects of dose rate, concentration and composition of the monomer, emulsifier concentration, etc. on polymerization rate and intrinsic viscosity of polymer have been examined. The rate of polymerization ( Rp) can be represented by Rp ? D0.87[M] 1.37[E] 0.53. The overall activation activation energy for the rate of polymerization is 16.9 kJ/mol (32-55°C). Based on these experimental results, some aspects of the polymerization mechanism are discussed.

Ge, Xuewu; Ye, Qiang; Xu, Xiangling; Zhang, Zhicheng; Sun, Qian

116

Kinetics of emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride and acrylamide with gamma rays  

NASA Astrophysics Data System (ADS)

Inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride with acrylamide has been studied with gamma ray dilatometrically. Aqueous monomer solutions were emulsified in kerosene with a blend of two surfactants (Span80 and OP10). The gel effect is evident from the increase of the molecular weight with conversion and also from the percentage conversion versus time curves. Monomer reactivity ratios have been derived as ram = 0.23 and rdmc = 1.40 at pH 6.8. Initial emulsions and final inverse latexes displayed the same broad size distribution. The effects of dose rate, concentration and composition of the monomer, emulsifier concentration, etc. on polymerization rate and intrinsic viscosity of polymer have been examined. The rate of polymerization (Rp) can be represented by Rp ? D0.87[M]1.37[E]0.53. The overall activation energy for the rate of polymerization is 16.9 kJ/mol (32-55°C). Based on these experimental results, some aspects of the polymerization mechanism are discussed.

Xuewu, Ge; Qiang, Ye; Xiangling, Xu; Zhicheng, Zhang; Qian, Sun

1997-09-01

117

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

118

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

119

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.

120

Combined measurement of translational and rotational diffusion in quaternary acyclic ammonium and cyclic pyrrolidinium ionic liquids.  

PubMed

The translational self-diffusion coefficients (D(T)) for a series of tetra-alkyl acyclic ammonium and cyclic pyrrolidinium ionic liquids (ILs) were measured using (1)H pulse field gradient (PFG) NMR spectroscopy over various temperatures. These NMR diffusion results were combined with previously measured rotational diffusion coefficients (D(R)) obtained from (14)N NMR relaxation measurements for the same ILs (Alam, T. M.; et al. J. Phys. Chem. A 2011, 115, 4307- 4316). The D(T)/D(R) ratio was then used to estimate the effective hydrodynamic radius and corresponding volumes without the need to directly measure the viscosities of the ILs. The generality, validity, and performance of using this D(T)/D(R) ratio is discussed and compared to the effective hydrodynamic volumes obtained using classic D(T)/viscosity and D(R)/viscosity relationships. The temperature variation observed for the molecular volumes obtained using the D(T)/D(R) ratio is argued to be a signature for the breakdown or decoupling of the Stokes-Einstein and Stoke-Einstein-Debye relationships in these neat IL systems, consistent with recent molecular dynamic simulations. PMID:23327476

Alam, Todd M; Dreyer, Daniel R; Bielawski, Christopher W; Ruoff, Rodney S

2013-02-14

121

Recognition of N-alkyl and N-aryl acetamides by N-alkyl ammonium resorcinarene chlorides.  

PubMed

N-Alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra- and intermolecular hydrogen bonds that leads to cavitand-like structures. Depending on the upper-rim substituents, self-inclusion was observed in solution and in the solid state. The self-inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self-included dimers spontaneously reorganize to 1:1 host-guest complexes. These host compounds show an interesting ability to bind a series of N-alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C?O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl(-) ) and ammonium (NH2 (+) ) cations of the hosts, and also through CH???? interactions between the hosts and guests. The self-included and host-guest complexes were studied by single-crystal X-ray diffraction, NMR titration, and mass spectrometry. PMID:25257765

Beyeh, N Kodiah; Ala-Korpi, Altti; Cetina, Mario; Valkonen, Arto; Rissanen, Kari

2014-11-10

122

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

123

Assay of 1-ammonium-3,5-dinitro-1,2,4-triazole and its determination in mixtures with ammonium nitrate. [Titrant - cetylpyridinium chloride  

SciTech Connect

Work is in progress at this Laboratory on the detonation calorimetry of ammonium dinitrotriazole (ADNT) and mixtures of ADNT and ammonium nitrate (AN). Our analytical requirements were therefore, twofold: (1) the assay of ADNT, and (2) the determination of ADNT in admixture with AN. The first requirement was straightforward and was accomplished by nonaqueous titration of ADNT, either as an acid or as a base. The second requirement, however, proved more difficult. It was accomplished by using cetypyridinium chloride (CPC), a new titrant recently introduced at this Laboratory to determine the ADNT in the mixture. Various liquid-membrane electrodes such as the fluoroborate, perchlorate, and nitrate ion-selective electrodes (ISE's) may be used as endpoint sensors. We have found that the solid-state cyanide (or iodide) ISE also senses the endpoint of this titration, although considerably smaller endpoint breaks are obtained. Nevertheless, the mean values obtained using the fluoroborate and cyanide ISE's differed by only 0.09%. The method can also be used for the assay of some ammonium salts of other nitroheterocycles. It cannot differentiate, however, between the various compounds.

Selig, W.

1981-07-01

124

Environmental assessment of an alkyl dimethyl benyzl ammonium chloride (ADBAC) based mollusicide using laboratory tests  

SciTech Connect

A series of acute and chronic toxicity tests were conducted to estimate the potential environmental impact of n-alkyl dimethyl benzyl ammonium chloride (ADBAC) when used to control zebra mussels and other types of macrofouling organism in industrial cooling systems. The ADBAC-based molluscicide was tested as pure product and often detoxification with bentonite clay. Six flow-through acute tests were conducted to estimate the toxicity of ADBAC. In addition three chronic toxicity tests using Pimephales promelas, Daphnia magna and Selenastrum capricornutum were carried out to evaluate the efficacy of complexing the ADBAC-based molluscicide with a bentonite clay as a detoxification strategy. A 29-day CO{sub 2} Production test was also conducted to evaluate the biodegradability of the molluscicide. Of the six species tested in acute flow-through experiments, D. magna (LC{sub 50} = 0.02 mg ADBAC/L) was the most sensitive species followed by Mysidopsis bahia (LC{sub 50} = 0.08 mg ADBAC/L), Menidia beryllina (LC{sub 50} = 0.88 mg ADBAC/L), P. promelas (LC{sub 50} = 0.36 mg ADBAC/L), Cyprinodon variegatus (LC{sub 50} = 0.88 mg ADBAC/L), and Oncorhynchus mykiss (LC{sub 50} = 1.01 mg ADBAC/L). In the detoxification studies the three test species were exposed to treatment levels of: 0:0, 2.5:0, 2.5:25, 2.5:37.5, 2.5:50, 2.5:75, and 0:75 as mg/L ADBAC:clay. Bentonite clay was found to be an effective detoxification agent for this molluscicide at all treatment levels, except for the 2.5:25 treatment. In addition, a biodegradation study showed that the ADBAC-based molluscicide was readily biodegradable by unacclimated activated sludge microorganisms releasing 65.9% of the theoretical possible CO{sub 2} after 29 days.

Dobbs, M.G.; Cherry, D.S.; Scott, J.C. [Virginia Tech, Blacksburg, VA (United States); Petrille, J.C. [Betz Water Management Center, Trevose, PA (United States)

1995-06-01

125

Effects of antibacterial primers with quaternary ammonium and nano-silver on S. mutans impregnated in human dentin blocks  

PubMed Central

Objectives Recent studies developed antibacterial bonding agents and composites containing a quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg). The objectives of this study were to investigate: (1) the effect of antibacterial primers containing QADM and NAg on the inhibition of Streptococcus mutans (S. mutans) impregnated into dentin blocks for the first time, and (2) the effect of QADM or NAg alone or in combination, and the effect of NAg mass fraction, on S. mutans viability in dentin. Methods Scotchbond Multi-Purpose (SBMP) bonding agent was used. QADM and NAg were incorporated into SBMP primer. Six primers were tested: SBMP primer control, control + 10% QADM (mass %), control + 0.05% NAg, control + 10% QADM + 0.05% NAg, control + 0.1% NAg, and control + 10% QADM + 0.1% NAg. S. mutans were impregnated into dentin blocks, then a primer was applied. The viable colony-forming units (CFU) were then measured by harvesting the bacteria in dentin using a sonication method. Results Control + 10% QADM + 0.1% NAg had bacteria inhibition zone 8-fold that of control (p < 0.05). The sonication method successfully harvested bacteria from dentin blocks. Control + 10% QADM + 0.1% NAg inhibited S. mutans in dentin blocks, reducing the viable CFU in dentin by three orders of magnitude, compared to control dentin without primer. Using QADM+NAg was more effective than QADM alone. Higher NAg content increased the potency. Dentin shear bond strength was similar for all groups (p > 0.1). Significance Antibacterial primer with QADM and NAg were shown to inhibit the S. mutans impregnated into dentin blocks for the first time. Bonding agent containing QADM and NAg is promising to eradicate bacteria in tooth cavity and inhibit caries. The QADM and NAg may have applicability to other adhesives, cements, sealants and composites. PMID:23422420

Cheng, Lei; Zhang, Ke; Weir, Michael D.; Liu, Huaibing; Zhou, Xuedong; Xu, Hockin H. K.

2013-01-01

126

Evaluation of an ammonium ionophore for use in poly(vinyl chloride) membrane ion-selective electrodes: solvent mediator effects.  

PubMed

A macrotetrolide nonactin-based ammonium ionophore (AI) preparation containing 25% nonactin optimized for use in liquid membrane ion-selective electrodes was investigated for its possible use in poly(vinyl chloride) (PVC) matrix membrane-type electrodes. Nine different plasticizing solvent mediators were employed in the ammonium ion-selective membranes with PVC and the AI preparation. Near Nernstian responses were observed in aqueous solution with electrodes fabricated with dioctyl sebacate-, 2-nitrophenyl phenyl ether-, dibutyl sebacate-, trioctyl phosphate-, dioctyl adipate-, dioctyl phenyl phosphonate- and 2-nitrophenyl octyl ether-plasticized membranes. The responses of these electrodes were found to improve in the presence of a background concentration of non-interfering calcium ions. PMID:7872484

Ghauri, M S; Thomas, J D

1994-11-01

127

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

128

Nutrient Leaching in Undisturbed Cores of an Acidic Sandy Podosol Following Simultaneous Potassium Chloride and Di-Ammonium Phosphate Application  

Microsoft Academic Search

In south-east Queensland, Australia, extensive areas of sandy soils (Podosols) with shallow (<1 m) watertables are used for\\u000a exotic pine tree production. Despite concerns that surface-applied fertilisers (di-ammonium phosphate (DAP) and potassium\\u000a chloride (KCl)) may be contributing to a decline in local groundwater quality, published information on nutrient leaching\\u000a in these Podosols is scarce. Large (0.3 m i.d. ×0.85 m long) undisturbed soil cores

Ian R Phillips; Edward D Burton

2005-01-01

129

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

130

Synthesis and structural studies of a new class of quaternary ammonium salts, which are derivatives of cage adamanzane type aminal 1, 3, 6, 8-tetraazatricyclo[4.3.1.13,8]undecane (TATU)  

PubMed Central

Background Novel mono N-alkyl quaternary ammonium salts (3a-f) were prepared using the Menschutkin reaction from the cage adamanzane type aminal 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU) and alkyl iodides, such as methyl, ethyl, propyl, butyl, pentyl and hexyl iodide (2a-f), in dry acetonitrile at room temperature. Results The structures of these new quaternary ammonium salts were established using various spectral and electrospray ionization mass spectrometry (ESI-MS) analyses. Compound (3b) was also analyzed using X-ray crystallography. Conclusion It was noted that alkyl chain length did not significantly affect the reaction because all employed alkyl iodide electrophiles reacted in a similar fashion with the aminal 1 to produce the corresponding mono N-quaternary ammonium salts, which were characterized by spectroscopic and analytical techniques. PMID:21933409

2011-01-01

131

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

132

Rapid Fixation of Methylene Chloride by a Macrocyclic Amine Jung-Jae Lee, Keith J. Stanger, Bruce C. Noll, Carlos Gonzalez, Manuel Marquez, and  

E-print Network

with the macrocyclic ether oxygens.4 The macrocyclic nitrogen attacks the methylene chloride with a classic SN2 by methylene chloride, but the reaction is very slow with half-lives of many weeks to several months.2 Here, we to give the quaternary ammonium salt 2. Initially, we studied the reaction using methylene chloride

Smith, Bradley D.

133

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants  

Microsoft Academic Search

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds\\u000a (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance\\u000a of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium\\u000a phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated

Evren Terzi; S. Nami Kartal; Robert H. White; Katsumi Shinoda; Yuji Imamura

2011-01-01

134

Synthesis, growth and characterization of non linear optical Bisthiourea ammonium chloride single crystals by slow evaporation technique  

NASA Astrophysics Data System (ADS)

A new semi-organic nonlinear optical crystal of Bisthiourea Ammonium Chloride (BTAC) has been grown by slow evaporation technique. The crystal system and lattice parameters were determined from X-ray diffraction. Fourier Transform Infrared (FTIR) studies confirm the various functional groups present in the grown crystal. The transmittance and absorbance of electromagnetic radiation is studied through UV-Visible spectrum. The thermal behavior of the grown crystals has been investigated by TG/DTA analysis. The dielectric constant and dielectric loss has been studied as a function of frequency for various temperatures and the result were discussed in detail. The SEM analysis was also done and it revealed the surface morphology of BTAC crystal. The second harmonic generation has been confirmed by the Kurtz powder test and it is found to be 1.4 times more than that of KDP crystal.

Ilango, E.; Rajasekaran, R.; Shankar, K.; Krishnan, S.; Chithambaram, V.

2014-11-01

135

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

136

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

137

Cationic quaternization of cellulose with methacryloyloxy ethyl trimethyl ammonium chloride via ATRP method  

NASA Astrophysics Data System (ADS)

The synthesis of a cationic cellulose copolymer from cellulose macro-initiator (MCC-BiB) and quaternary compound monomer (METMA) via atom transfer radical polymerization (ATRP) was studied. By using dimethylformamide (DMF), the optimum condition for successful synthesis was at the mole ratio of MCC-BIB:Catalyst:METMA = 1:1:26. The highest copolymer recovery was 93.2 % for 6 h and at 40°C. The copolymer was insoluble in weak polar solvents such as THF and DMF but soluble in methanol and water. The chemistry of cellulose copolymer was confirmed by the FTIR and TGA in which the METMA monomer was used as a reference. The absence of CC bond in the CiB-g-METMA spectrum indicated that graft copolymerization occurred.

Supeno, Daik, Rusli; El-Sheikh, Said M.

2014-09-01

138

HYPERSONIC INVESTIGATION OF THE A -T y p E PHASE TRANSITION IN AMMONIUM-CHLORIDE M. GROSS -D. GERLICH -and S. SZAPIRO  

E-print Network

HYPERSONIC INVESTIGATION OF THE A - T y p E PHASE TRANSITION IN AMMONIUM-CHLORIDE M. GROSS - D method.The hypersonic sound velocities and elastic constants have been measured in the immediate vicinity measurements. The difference between the present hypersonic measurement and previous ultrasonic results

Paris-Sud XI, Université de

139

Influence of varying levels of ammonium chloride on urine pH and specific gravity, overall feed conversion, and water consumption in mature wether goats.  

E-print Network

The objective of this study was to evaluate the effect of orally administered ammonium chloride (NH4CL) on pH and specific gravity of urine, overall gain, and water consumption in mature wethers on a grower/finisher ration. Obstructive urolithiasis...

Kennedy, Matthew joseph

2009-05-15

140

Ammonium chloride-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1 H)-ones under solvent-free conditions  

Microsoft Academic Search

Ammonium chloride as a very inexpensive and readily available reagent, and efficiently catalyzes one-pot, three component, Biginelli condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2-(1H)-ones in high yields at 100°C.

Ahmad Shaabani; Ayoob Bazgir; Fatemeh Teimouri

2003-01-01

141

Synergistic Solvent Extraction and Separation of Lanthanides Using Mixtures of 1?Phenyl?3?methyl?4?benzoyl?pyrazol?5?one and Aliquat?336: Influence of the Ammonium Salt Anion  

Microsoft Academic Search

The synergistic solvent extraction of lanthanide ions with mixtures of 1?phenyl?3?methyl?4?benzoyl?pyrazol?5?one (HP) and the quaternary ammonium salt Aliquat 336 in chloride (QCl) or perchlorate (QClO4) forms in C6H6 was studied. The composition of the extracted species was determined as Q[LnP4] (Q is a quaternary ammonium salt cation). The values of the equilibrium constant were calculated. The extraction mechanism as well

I. L. Dukov; M. Atanassova

2005-01-01

142

A polymethacrylate-based quaternary ammonium OH- ionomer binder for non-precious metal alkaline anion exchange membrane water electrolysers  

NASA Astrophysics Data System (ADS)

In order to develop the alkaline anion exchange membrane water electrolysers (AAEMWE), a quaternary OH- conductive ionomer binder based on polymethacrylate was synthesized by copolymerization of three kinds of methacrylate monomers, which was followed by quaternization. Tensile strength of this ionomer membrane was 7.629 MPa, with Young's modulus 0.229 GPa and elongation 45.8%. The conductivity of this ionomer could reach 0.059 S cm-1 at 50 °C. With this ionomer in catalyst layers of an AAEMWE, the voltage of 1.9 V gave a current density of 100 mA cm-2. Satisfactory stability of the membrane electrode assembly was observed from chronocoulometry.

Wu, Xu; Scott, Keith

2012-09-01

143

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

144

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

145

Conditions for defect-free solidification of aqueous ammonium chloride in a quasi two-dimensional directional solidification facility  

NASA Astrophysics Data System (ADS)

Experimental and theoretical approaches to the problem of the solidification of a binary melt are presented. We describe a series of experiments in which aqueous solutions of ammonium chloride of above eutectic composition are cooled from below in a Hele-Shaw cell that is translated downwards at a constant rate. A mushy layer of solid dendrites bathed in a salt-depleted interstitial fluid is formed. For certain combinations of initial concentration and translation speed, convection in the mush gives rise to chimneys which result in defects in the solidified material. Our experiments demonstrate that using a higher temperature gradient for solidification increases the range of conditions for which a mushy layer forms that is free from both chimneys and secondary nucleation. We present a mathematical model of the system, to which we derive an approximate analytical solution. Predictions of the height of the mushy layer given by this approximate solution are found to be in excellent agreement with full numerical predictions when the height is small. Both numerical and analytical predictions are a better match to experimental data when the temperature gradient is low.

Whiteoak, S. H.; Huppert, Herbert E.; Worster, M. Grae

2008-07-01

146

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

147

Tris(cyclo-hexyl-ammonium) cis-di-chlorido-bis-(oxalato-?(2) O (1),O (2))stann-ate(IV) chloride monohydrate.  

PubMed

The crystal structure of the title compound, (C6H14N)3[Sn(C2O4)2Cl2]Cl·H2O, contains three cyclo-hexyl-ammonium cations, one stannate(IV) dianion, one isolated chloride anion and one lattice water mol-ecule. The cyclo-hexyl-ammonium cations adopt chair conformations. In the complex anion, two bidentate oxalate ligands and two chloride anions in cis positions coordinate octa-hedrally to the central Sn(IV) atom. The cohesion of the mol-ecular entities is ensured by the formation of N-H?O, O-H?O, O-H?Cl and N-H?Cl inter-actions involving cations, anions and the lattice water mol-ecule, giving rise to a layer-like arrangement parallel to (010). PMID:24454022

Sarr, Modou; Diallo, Waly; Diasse-Sarr, Aminata; Plasseraud, Laurent; Cattey, Hélène

2013-10-01

148

Tris(cyclo-hexyl-ammonium) cis-di-chlorido-bis-(oxalato-?2 O 1,O 2)stann-ate(IV) chloride monohydrate  

PubMed Central

The crystal structure of the title compound, (C6H14N)3[Sn(C2O4)2Cl2]Cl·H2O, contains three cyclo­hexyl­ammonium cations, one stannate(IV) dianion, one isolated chloride anion and one lattice water mol­ecule. The cyclo­hexyl­ammonium cations adopt chair conformations. In the complex anion, two bidentate oxalate ligands and two chloride anions in cis positions coordinate octa­hedrally to the central SnIV atom. The cohesion of the mol­ecular entities is ensured by the formation of N—H?O, O—H?O, O—H?Cl and N—H?Cl inter­actions involving cations, anions and the lattice water mol­ecule, giving rise to a layer-like arrangement parallel to (010). PMID:24454022

Sarr, Modou; Diallo, Waly; Diasse-Sarr, Aminata; Plasseraud, Laurent; Cattey, Helene

2013-01-01

149

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

Microsoft Academic Search

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.

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

2011-01-01

150

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

151

Bifunctional quaternary ammonium compounds to inhibit biofilm growth and enhance performance for activated carbon air-cathode in microbial fuel cells  

NASA Astrophysics Data System (ADS)

The slow diffusion of hydroxyl out of the catalyst layer as well as the biofouling on the surface of cathode are two problems affecting power for membrane-less air-cathode microbial fuel cells (MFCs). In order to solve both of them simultaneously, here we simply modify activated carbon air-cathode using a bifunctional quaternary ammonium compound (QAC) by forced evaporation. The maximum power density reaches 1041 ± 12 mW m-2 in an unbuffered medium (0.5 g L-1 NaCl), which is 17% higher than the control, probably due to the accelerated anion transport in the catalyst layer. After 2 months, the protein content reduced by a factor of 26 and the power density increases by 33%, indicating that the QAC modification can effectively inhibit the growth of cathodic biofilm and improve the stability of performance. The addition of NaOH and QAC epoxy have a negative effect on power production due to the clogging of pores in catalyst layer.

Li, Nan; Liu, Yinan; An, Jingkun; Feng, Cuijuan; Wang, Xin

2014-12-01

152

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

153

QSAR study on maximal inhibition (Imax) of quaternary ammonium antagonists for S-(-)-nicotine-evoked dopamine release from dopaminergic nerve terminals in rat striatum  

PubMed Central

Maximal inhibition (Imax) of the agonist effect is an important pharmacological property of inhibitors that interact with multiple receptor subtypes that are activated by the same agonist and which elicit the same functional response. This report represents the first QSAR study on a set of 66 mono- and bis-quaternary ammonium salts that act as antagonists at neuronal nicotinic acetylcholine receptors mediating nicotine-evoked dopamine release, conducted using multi-linear regression (MLR) and neural network (NN) analysis with the maximal inhibition (Imax) values of the antagonists as target values. The statistical results for the generated MLR model were: r2 = 0.89, rmsd = 9.01, q2 = 0.83 and loormsd = 11.1; the statistical results for the generated NN model were: r2 = 0.89, rmsd = 8.98, q2 = 0.83 and loormsd = 11.2. The maximal inhibition values of the compounds exhibited a good correlation with the predictions made by the QSAR models developed, which provide a basis for rationalizing selection of compounds for synthesis in the discovery of effective and selective second generation inhibitors of nAChRs mediating nicotine-evoked dopamine release. PMID:19477134

Zheng, Fang; McConnell, Matthew J.; Zhan, Chang-Guo; Dwoskin, Linda P.; Crooks, Peter A.

2013-01-01

154

Effect of supplementation of dry cat food with D,L-methionine and ammonium chloride on struvite activity product and sediment in urine.  

PubMed

Feeding dry foods supplemented with urine acidifier (D,L-methionine (Met) or ammonium chloride) decreased urinary pH and struvite activity product in clinically normal cats. As a result, the number of struvite crystals in urine was greatly reduced. Supplementation with 3% Met but not 1% Met caused decrease in the urinary concentration of sediment, which resulted from a reduction in the HCl-soluble fraction. The concentration of HCl-insoluble sediment was not affected by supplementation with the urine acidifier. PMID:11307939

Funaba, M; Yamate, T; Narukawa, Y; Gotoh, K; Iriki, T; Hatano, Y; Abe, M

2001-03-01

155

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

156

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

PubMed

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the species and structures existing in a series of ZnCl(2)-H(2)O-NaCl solutions with different chloride/zinc ratios and in a solution of ZnCl(2) 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 Zn(2+) is significantly related to the chloride/zinc ratio, and no inner complex formation between Zn(2+) and Cl(-) ions has been detected for low ZnCl(2) concentration (0.1 and 0.2 M). Conversely, in the same concentration range (0.13 M) the ZnCl(2) species do not dissociate in EAN and the Zn(2+) 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. PMID:22029326

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

2011-10-21

157

N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride nanoparticle as a novel delivery system for parathyroid hormone-related protein 1-34.  

PubMed

Chitosan (CS) and epoxy propyl trimethyl ammonium chloride (EPTAC) were used to prepare the water-soluble N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC). HTCC and sodium tripolyphosphate (TPP) were mixed to form HTCC nanoparticles based on ionic gelation. Parathyroid hormone-related protein 1-34 (PTHrP1-34) was incorporated into the HTCC nanoparticles. The particle size and morphology of nanoparticles were determined by transmission electron microscopy (TEM). HTCC/PTHrP1-34 nanoparticles were 100-180 nm in size and their encapsulation efficiency and loading capacity were related to HTCC concentration, TPP concentration and initial concentration of PTHrP1-34. Relatively optimum encapsulation efficiency (78.4%) and loading capacity (13.7%) of PTHrP1-34 is achieved, and the in vitro release profile of PTHrP1-34 from nanoparticles has an initial burst, which is followed up by a slow release phase. These studies showed that HTCC/PTHrP1-34 nanoparticles are suitable for the treatment of osteoporosis, because of their slow-continuous-release properties, and the relevant in vivo experiments and clinical trials should be further studied. PMID:20435115

Zhao, Sheng-hao; Wu, Xiao-ting; Guo, Wei-chun; Du, Yu-min; Yu, Ling; Tang, Jin

2010-06-30

158

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

159

Facile preparation of magnetic 2-hydroxypropyltrimethyl ammonium chloride chitosan/Fe3O4/halloysite nanotubes microspheres for the controlled release of ofloxacin.  

PubMed

Magnetic microspheres, 2-hydroxypropyltrimethyl ammonium chloride chitosan/Fe3O4/halloysite nanotubes/ofloxacin (HACC/Fe3O4/HNTs/OFL), for the controlled release of OFL were prepared by in situ crosslinking with glutaraldehyde in the spray-drying process. The magnetic microspheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and a magnetometer. Various parameters influencing the encapsulation efficiency, drug loading and in vitro controlled release properties of the magnetic microspheres for OFL were also studied. Many stripes were formed and some tubular HNTs could be seen at higher magnification on the surface of the HACC/Fe3O4/HNTs/OFL magnetic microspheres. The magnetic microspheres show superparamagnetic property and fast magnetic response. The encapsulation efficiency and the cumulative release of OFL are closely related to HACC concentration, HNTs contents and crosslinking density. The release of OFL follows the first-order kinetics. PMID:24507359

Wang, Qin; Zhang, Junping; Mu, Bin; Fan, Ling; Wang, Aiqin

2014-02-15

160

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

161

Investigations of the ex situ ionic conductivities at 30 degrees C of metal-cation-free quaternary ammonium alkaline anion-exchange membranes in static atmospheres of different relative humidities.  

PubMed

This article presents the first systematic study of the effect of Relative Humidity (RH) on the water content and hydroxide ion conductivity of quaternary ammonium-based Alkaline Anion-Exchange Membranes (AAEMs). These AAEMs have been developed specifically for application in alkaline membrane fuel cells, where conductivities of >0.01 S cm(-1) are mandatory. When fully hydrated, an ETFE-based radiation-grafted AAEM exhibited a hydroxide ion conductivity of 0.030 +/- 0.005 S cm(-1) at 30 degrees C without additional incorporation of metal hydroxide salts; this is contrary to the previous wisdom that anion-exchange membranes are very low in ionic conductivity and represents a significant breakthrough for metal-cation-free alkaline ionomers. Desirably, this AAEM also showed increased dimensional stability on full hydration compared to a Nafion-115 proton-exchange membrane; this dimensional stability is further improved (with no concomitant reduction in ionic conductivity) with a commercial AAEM of similar density but containing additional cross-linking. However, all of the AAEMs evaluated in this study demonstrated unacceptably low conductivities when the humidity of the surrounding static atmospheres was reduced (RH = 33-91%); this highlights the requirement for continued AAEM development for operation in H(2)/air fuel cells with low humidity gas supplies. Preliminary investigations indicate that the activation energies for OH(-) conduction in these quaternary ammonium-based solid polymer electrolytes are typically 2-3 times higher than for H(+) conduction in acidic Nafion-115 at all humidities. PMID:17356755

Varcoe, John R

2007-03-28

162

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

163

Calibration and measurement uncertainties of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment  

Microsoft Academic Search

Experimental and theoretical uncertainties in the measurement of cloud condensation nuclei (CCN) with a continuous-flow thermal-gradient CCN counter from Droplet Measurement Technologies (DMT-CCNC) have been assessed by model calculations and calibration experiments with ammonium sulfate and sodium chloride aerosol particles in the diameter range of 20-220 nm. Experiments have been performed in the laboratory and during field measurement campaigns, covering

D. Rose; S. S. Gunthe; E. Mikhailov; G. P. Frank; U. Dusek; M. O. Andreae; U. Pöschl

2008-01-01

164

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

165

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

166

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

167

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

168

The relationship between the pharmacokinetics, cholinesterase inhibition and facilitation of twitch tension of the quaternary ammonium anticholinesterase drugs, neostigmine, pyridostigmine, edrophonium and 3-hydroxyphenyltrimethylammonium.  

PubMed Central

1 The relationship between the concentration of drug in plasma, the inhibition of erythrocyte acetylcholinesterase and the facilitation of neuromuscular transmission has been studied in the rat after the administration of neostigmine, pyridostigmine, edrophonium and 3-hydroxyphenyltrimethyl-ammonium (3-OH PTMA). 2 After the administration of neostigmine or pyridostigmine, acetylcholinesterase activity recovered only slowly due to the covalent nature of the inhibition. In contrast, recovery from the reversible inhibition caused by edrophonium or 3-OH PTMA was rapid and showed a direct relationship to the plasma concentration of these drugs. 3 There was a statistically significant linear correlation between the logarithm of the plasma concentration of the drugs and the increase in the tibialis twitch tension. 4 The relationship between the inhibition of acetylcholinesterase and the facilitation of neuromuscular transmission was complex. When the enzyme was less than 85% inhibited no facilitation occurred. Between 85% and 98% inhibition, facilitation was linearly related to enzyme inhibition. Above 98% inhibition, facilitation was unrelated to inhibition of the enzyme. PMID:223706

Barber, H. E.; Calvey, T. N.; Muir, K. T.

1979-01-01

169

Highly sensitive assay for tiotropium, a quaternary ammonium, in human plasma by high-performance liquid chromatography/tandem mass spectrometry.  

PubMed

Tiotropium bromide, a long-acting inhaled bronchodilator analogous to ipratropium bromide, is currently undergoing development for the treatment of chronic obstructive pulmonary disease. To evaluate its systemic absorption in humans, we have developed a rapid and sensitive method for its determination in human plasma based on high-performance liquid chromatography with tandem mass spectrometric detection (HPLC/MS/MS). Reversed-phase chromatography of tiotropium and the internal standard clenbuterol was carried out using acetonitrile/10 mM ammonium acetate (1% formic acid) 40:60 as mobile phase in a run time of 3.0 min. The sample preparation involved deproteination with acetonitrile, extraction into dichloromethane and back-extraction into hydrochloric acid. The assay was linear over the concentration range 0.500-50.0 pg/mL with intra- and inter-day precision (as relative standard deviation) both

Wang, Jiang; Jiang, Yao; Wang, Yingwu; Li, Hao; Fawcett, J Paul; Gu, Jingkai

2007-01-01

170

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

171

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

172

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

173

Synthesis and application of a quaternary phosphonium polymer coagulant to avoid N-nitrosamine formation.  

PubMed

Quaternary ammonium cationic polymers, such as poly(diallyldimethylammonium chloride) (polyDADMAC) are widely used for coagulating and removing negatively charged particles and dissolved organic matter (DOM) from drinking water. Their use, however, has been linked to the formation of carcinogenic N-nitrosamines as byproducts during chloramine-based drinking water disinfection. In this study, a novel quaternary phosphonium cationic polymer, poly(diallyldiethylphosphonium chloride) (polyDADEPC), was synthesized such that the quaternary nitrogen atom of polyDADMAC was substituted with a phosphorus atom. Formation potential tests revealed that even under strong nitrosation conditions, polyDADEPC and related lower-order P-based compounds formed oxygenated and not nitrosated products. Bench-scale jar tests using three different source waters further demonstrated that polyDADEPC achieved coagulation performance comparable to commercial polyDADMACs for particle and DOM removals within the typical dose range used for drinking water treatment. This work highlights the potential use of a phosphonium coagulant polymer, polyDADEPC, as a viable alternative to polyDADMAC to avoid nitrosated byproduct formation during chloramination. PMID:25322258

Zeng, Teng; Pignatello, Joseph J; Li, Russell Jingxian; Mitch, William A

2014-11-18

174

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

175

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

176

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

177

Estimation of bottom ammonium affinity in the New Caledonia lagoon  

Microsoft Academic Search

Ammonium affinity of New Caledonia lagoon benthic communities was measured during the course of 33 in situ enrichment experiments, in order to estimate the contribution of benthos to ammonium fluxes. Ammonium chloride was injected into enclosures pushed into the sediment, in order to obtain a concentration of 20–22 µmol l-1 in the enclosed water which approximated the interstitial water content.

G. Boucher; J. Clavier; C. Garrigue

1994-01-01

178

The size of hydroxyl groups in solution and the changes in size associated with the ionization of phenolic, carboxylic and amino groups in phenolic quaternary ammonium salts, nicotine and some amino acids: possible implications for drug-water and drug-receptor interactions.  

PubMed Central

Size in solution can be expressed either as the apparent molal volume at infinite dilution (phi 0v) amd the concentration parameter (j) or as the partial molal volume of the solute at infinite dilution (V0(2)) and the concentration parameter for the solute or solvent (qs or qw). Although calculated differently, these are derived from the same results and are equivalent. From measurement with phenolic quaternary ammonium salts, including compounds with high nicotine-like activity, the apparent size of the hydroxyl group in water is small and variable. Phenolic groups are slightly larger than alcoholic groups, which should be better hydrogen donors. By measuring the volume change associated with ionisation it is possible to measure the size of charged groups such as phenate and carboxylate; these are much smaller than phenolic and carboxyl. Ammonium groups, however, are only slightly smaller than the corresponding amines. The zwitterion forms of amino acids are associated with a minimum in volume but the volume changes increase with chain length from glycine to gamma-aminobutyric acid. Groups separated by less than this distance interact in their effects on water. Decreases in volume or unexpectedly small increments in apparent molal volume represent decreases in entropy which must be taken into account in drug-water-receptor interactions. Although they may be offset by enthalpy changes, they should favour binding because there is more scope for an increase in entropy. This might explain the association of the small apparent size in water of the hydroxyl group in many compounds with its effects of their affinity for receptors. PMID:7470734

Barlow, R. B.

1980-01-01

179

Comparative Effects of Ammonium and Nitrate Compounds on Pacific Treefrog and African Clawed Frog Embryos  

Microsoft Academic Search

.   The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific\\u000a 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

G. S. Schuytema; A. V. Nebeker

1999-01-01

180

Effects of ammonium concentration and charge exchange on ammonium recovery from high strength wastewater using a microbial fuel cell.  

PubMed

Ammonium recovery using a two chamber microbial fuel cell (MFC) was investigated at high ammonium concentration. Increasing the ammonium concentration (from 0.07 to 4 g ammonium-nitrogen/L) by addition of ammonium chloride did not affect the performance of the MFC. The obtained current densities by DC-voltammetry were higher than 6A/m(2) for both operated MFCs. Also continuous operation at lower external resistance (250 ?) showed an increased current density (0.9A/m(2)). Effective ammonium recovery can be achieved by migrational ion flux through the cation exchange membrane to the cathode chamber, driven by the electron production from degradation of organic substrate. The charge transport was proportional to the concentration of ions. Nonetheless, a concentration gradient will influence the charge transport. Furthermore, a charge exchange process can influence the charge transport and therefore the recovery of specific ions. PMID:21277769

Kuntke, P; Geleji, M; Bruning, H; Zeeman, G; Hamelers, H V M; Buisman, C J N

2011-03-01

181

Quaternary ammonium borohydride adsorption in mesoporous silicate MCM-48  

SciTech Connect

Inorganic borohydrides have a high gravimetric hydrogen density but release H2 only under energetically unfavorable conditions. Surface chemistry may help in lowering thermodynamic barriers, but inclusion of inorganic borohydrides in porous silica materials has proved hitherto difficult or impossible. We show that borohydrides with a large organic cation are readily adsorbed inside mesoporous silicates, particularly after surface treatment. Thermal analysis reveals that the decomposition thermodynamics of tetraalkylammonium borohydrides are substantially affected by inclusion in MCM-48. Inelastic neutron scattering (INS) data show that the compounds adsorb on the silica surface. Evidence of pore loading is supplemented by DSC/TGA, XRD, FTIR, and BET isotherm measurements. Mass spectrometry shows significant hydrogen release at lower temperature from adsorbed borohydrides in comparison with the bulk borohydrides. INS data measured for partially decomposed samples indicates that the decomposition of the cation and anion is likely simultaneous. Additionally, these data confirm the formation of Si-H bonds on the silica surface upon decomposition of adsorbed tetramethylammonium borohydride.

Wolverton, Michael J [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

2010-01-01

182

[Radioprotective activity, toxicity and mechanism of action of bis-(beta-dimethyl octyl ammonium ethyl)disulfide].  

PubMed

Disulfide bis-(beta-dimethyl octyl ammonium ethyl) and some of its analogues were shown to have a radioprotective effect. It is suggested that the mechanism of radioprotective action of quaternary ammonium compounds involves both a temporary inhibition of DNA synthesis in radiosensitive tissues and inhibition of oxidative processes in the organism. PMID:3194499

Vladimirov, V G; Strel'nikov, Iu E; Libikova, N I; Krasnil'nikov, I I; Kokushkina, A V

1988-01-01

183

Cesium Chloride  

MedlinePLUS

... tachycardia after alternative treatment with cesium chloride for brain cancer. Mayo Clin Proc . 2004:79(8);1065-1069. ... Zero efficacy with cesium chloride self-treatment for brain cancer. Mayo Clin Proc. 2004;79:1588. Sartori HE. ...

184

Contribution of ammonium ions to the lethality and antimetamorphic effects of ammonium perchlorate.  

PubMed

Ammonium perchlorate (AP) is a widespread military waste product in the United States and is a potent thyroid function disruptor in all vertebrates tested thus far. To determine the relative contribution of ammonium ions to the toxicity of AP, we exposed embryonic and larval Xenopus laevis to various concentrations of sodium perchlorate (SP) or ammonium chloride (AC). Ammonium perchlorate was significantly more lethal than SP; 5-d LC50s were 83 and 2,780 mg/L, respectively. To determine whether ammonium ions contribute to the antithyroid effects of AP, we exposed embryonic and larval X. laevis to two sublethal, environmentally relevant concentrations of AP or identical concentrations of AC or SP. At the smaller concentration, only AP delayed metamorphosis and reduced hindlimb growth. Sodium perchlorate and AP, but not AC, prevented metamorphosis and reduced hindlimb growth at the greater concentration. Although AP was slightly more effective in reducing outward manifestations of thyroid disruption, both perchlorate salts, unlike AC, caused profound histopathologic changes in the thyroid. Exposure to the higher concentration of either perchlorate salt produced a feminizing effect, resulting in a skewed sex ratio. We conclude that ammonium ions contribute significantly to the toxicity of AP but not to the direct antithyroid effects of perchlorate. PMID:16629145

Goleman, Wanda L; Carr, James A

2006-04-01

185

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

186

Listeria monocytogenes Strains Selected on Ciprofloxacin or the Disinfectant Benzalkonium Chloride Exhibit Reduced Susceptibility to Ciprofloxacin, Gentamicin, Benzalkonium Chloride, and Other Toxic Compounds?  

PubMed Central

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

2011-01-01

187

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

188

Quaternary Research Center  

NSDL National Science Digital Library

"The Quaternary Research Center (QRC) fosters interdisciplinary research on the last two million years of the global environment: a time which encompasses massive, abrupt changes of climate, sea level, global biota and ice extent, as well the evolution of humans and the advent of civilization." Divided into six laboratories, the University of Washington's Center studies Cosmogenic Isotopes, Stable Isotopes, Old Quaternary Isotopes, Periglacial environments, quaternary ecology, paleoecology, and remote sensing. Researchers can find a tremendous amount of isotope, carbon dioxide, and chemistry data on the Taylor Dome, a part of the East Antarctic ice sheet. Students and educators can read papers by the center covering topics such as interactions among climate, surface, and tectonics; and glaciations and climate variations in the Pacific Northwest.

189

Ammonium nitrate explosive systems  

DOEpatents

Novel explosives which comprise mixtures of ammonium nitrate and an ammonium salt of a nitroazole in desired ratios are disclosed. A preferred nitroazole is 3,5-dinitro-1,2,4-triazole. The explosive and physical properties of these explosives may readily be varied by the addition of other explosives and oxidizers. Certain of these mixtures have been found to act as ideal explosives.

Stinecipher, Mary M. (Los Alamos, NM); Coburn, Michael D. (Los Alamos, NM)

1981-01-01

190

Ammonium nitrate explosive systems  

SciTech Connect

Novel explosives which comprise mixtures of ammonium nitrate and an ammonium salt of a nitroazole in desired ratios are disclosed. A preferred nitroazole is 3,5-dinitro-1,2,4-triazole. The explosive and physical properties of these explosives may readily be varied by the addition of other explosives and oxidizers. Certain of these mixtures have been found to act as ideal explosives.

Coburn, M.D.; Stinecipher, M.M.

1981-11-17

191

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.

Hill, Christopher

192

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

193

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

194

Dimethyl-ammonium dichloridotriphenyl-stannate(IV)  

PubMed Central

The title salt, [(CH3)2NH2][Sn(C6H5)3Cl2], was obtained as a by-product of the reaction between bis­(dimethyl­ammonium) oxalate and triphenyl­tin chloride. In the stannate anion, the trigonal–bipyramidal coordination environment of the SnIV atom is defined by the phenyl groups in equatorial and the Cl atoms in axial positions. The cations are connected to adjacent anions through N—H?Cl and C—H?Cl hydrogen-bonding inter­actions, leading to a chain motif parallel to [100]. PMID:22807710

Sow, Yaya; Diop, Libasse; Kociok-Kohn, Gabriele; Molloy, Kieran C.

2012-01-01

195

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

196

Ammonium Handling by Superficial and Juxtamedullary Nephrons in the Rat  

PubMed Central

Papillary and surface micropuncture was used to assess the effects of a chronic metabolic acidosis on the renal tubular handling of ammonium by surface nephrons, juxtamedullary nephrons, and the terminal segment of collecting duct. Rats chronically fed ammonium chloride had an expected decline in arterial pH and bicarbonate concentration associated with a doubling in the amount of ammonium excreted and a decline in urine pH. The glomerular filtration rate and absolute delivery of water and sodium to micropuncture sites of surface and deep nephrons was not measurably altered. Ammonium delivery to the end of the proximal tubule increased from 853±102% to 1,197±142% (SE) of the filtered load of ammonium after the induction of metabolic acidosis. This increase was due to a rise in tubular fluid ammonium content from 2.31±0.23 to 4.06±0.28 mM/liter. After the induction of acidosis, absolute and fractional delivery of ammonium ion to the end of the distal tubule was less than to the end of the accessible portion of the proximal tubule. These findings indicate that ammonium is lost in the intervening segment. Ammonium handling by deep nephrons was profoundly affected by acid loading. Absolute delivery to the bend of the loop of Henle increased twofold while fractional delivery rose from 1,222±108% to 1,780±132% of the filtered ammonium. This was due to a marked increase in ammonia entry. During acidosis, ammonium delivery to the terminal segment of the collecting duct was doubled (709±137% in controls vs. 1,415±150% in acidosis, P < 0.005) but did not change between proximal and tip collecting duct sites. In both groups of animals delivery of ammonium to the terminal segment of the collecting duct was greater than to end distal tubular micropuncture sites suggesting that ammonia entry occurred between these two sites. The differences in delivery was greater after the induction of a metabolic acidosis (887±140% vs. 384±144%, P < 0.05). Thus, the present study indicates that deep nephrons contribute to the adaptive increase in ammonium excretion seen during the induction of metabolic acidosis. The data also suggest that ammonia leaves the nephrons at a site(s) along the loop of Henle to enter the collecting duct and that the induction of a metabolic acidosis enhances this reentry. PMID:7085880

Buerkert, John; Martin, Daniel; Trigg, David

1982-01-01

197

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

PubMed Central

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

198

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.

199

Poly-N-Acetylglucosamine Matrix Polysaccharide Impedes Fluid Convection and Transport of the Cationic Surfactant Cetylpyridinium Chloride through Bacterial Biofilms?  

PubMed Central

Biofilms are composed of bacterial cells encased in a self-synthesized, extracellular polymeric matrix. Poly-?(1,6)-N-acetyl-d-glucosamine (PNAG) is a major biofilm matrix component in phylogenetically diverse bacteria. In this study we investigated the physical and chemical properties of the PNAG matrix in biofilms produced in vitro by the gram-negative porcine respiratory pathogen Actinobacillus pleuropneumoniae and the gram-positive device-associated pathogen Staphylococcus epidermidis. The effect of PNAG on bulk fluid flow was determined by measuring the rate of fluid convection through biofilms cultured in centrifugal filter devices. The rate of fluid convection was significantly higher in biofilms cultured in the presence of the PNAG-degrading enzyme dispersin B than in biofilms cultured without the enzyme, indicating that PNAG decreases bulk fluid flow. PNAG also blocked transport of the quaternary ammonium compound cetylpyridinium chloride (CPC) through the biofilms. Binding of CPC to biofilms further impeded fluid convection and blocked transport of the azo dye Allura red. Bioactive CPC was efficiently eluted from biofilms by treatment with 1 M sodium chloride. Taken together, these findings suggest that CPC reacts directly with the PNAG matrix and alters its physical and chemical properties. Our results indicate that PNAG plays an important role in controlling the physiological state of biofilms and may contribute to additional biofilm-associated processes such as biocide resistance. PMID:19114520

Ganeshnarayan, Krishnaraj; Shah, Suhagi M.; Libera, Matthew R.; Santostefano, Anthony; Kaplan, Jeffrey B.

2009-01-01

200

Poly-N-acetylglucosamine matrix polysaccharide impedes fluid convection and transport of the cationic surfactant cetylpyridinium chloride through bacterial biofilms.  

PubMed

Biofilms are composed of bacterial cells encased in a self-synthesized, extracellular polymeric matrix. Poly-beta(1,6)-N-acetyl-d-glucosamine (PNAG) is a major biofilm matrix component in phylogenetically diverse bacteria. In this study we investigated the physical and chemical properties of the PNAG matrix in biofilms produced in vitro by the gram-negative porcine respiratory pathogen Actinobacillus pleuropneumoniae and the gram-positive device-associated pathogen Staphylococcus epidermidis. The effect of PNAG on bulk fluid flow was determined by measuring the rate of fluid convection through biofilms cultured in centrifugal filter devices. The rate of fluid convection was significantly higher in biofilms cultured in the presence of the PNAG-degrading enzyme dispersin B than in biofilms cultured without the enzyme, indicating that PNAG decreases bulk fluid flow. PNAG also blocked transport of the quaternary ammonium compound cetylpyridinium chloride (CPC) through the biofilms. Binding of CPC to biofilms further impeded fluid convection and blocked transport of the azo dye Allura red. Bioactive CPC was efficiently eluted from biofilms by treatment with 1 M sodium chloride. Taken together, these findings suggest that CPC reacts directly with the PNAG matrix and alters its physical and chemical properties. Our results indicate that PNAG plays an important role in controlling the physiological state of biofilms and may contribute to additional biofilm-associated processes such as biocide resistance. PMID:19114520

Ganeshnarayan, Krishnaraj; Shah, Suhagi M; Libera, Matthew R; Santostefano, Anthony; Kaplan, Jeffrey B

2009-03-01

201

Novel pretreatment of steam explosion associated with ammonium chloride preimpregnation.  

PubMed

Improving nitrogen content and enhancing enzymatic hydrolysis are key processes involved in cellulosic ethanol production. Steam explosion (SE) associated with NH4Cl preimpregnation was carried out to investigate effects of the pretreatment on nitrogen content, enzymatic digestibility, and ethanol production. Results showed that nitrogen content in pretreated samples increased, which can be used as nitrogen resource for ethanol fermentation. The highest glucose yield of sample pretreated by 1.4MPa SE with 90g/l NH4Cl preimpregnation was 62.64%, which was 2.1 and 0.2 times higher than that of untreated sample and 1.4MPa SE pretreated sample, respectively. Ethanol yield of sample pretreated by 1.1MPa SE with 135g/l NH4Cl preimpregnation resulted in 1.93 and 0.69 times higher than that of untreated sample and 1.1MPa SE pretreated sample, respectively. This novel pretreatment improved nitrogen content and enhanced enzymatic digestibility under mild conditions, and could be recommended to further industrial application. PMID:24362247

Chen, Hongzhang; Li, Guanhua; Li, Hongqiang

2014-02-01

202

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.

2007-02-27

203

Isotopic and Hydrogeochemical Studies on Abnormally High Ammonium of Natural Origin in A Coastal Aquifer-aquitard System  

NASA Astrophysics Data System (ADS)

Excessive nitrogen concentration in water bodies is regarded as an environmental contamination because of its possible harm to human bodies and significant ecological effects. Previous studies commonly concerned on elevated nitrogen in water of anthropogenic origins, such as agricultural, domestic, sewage and industrial discharges, because people realize that it is necessary to manage negative influences of human being to the natural environment. Understanding contamination sources of nitrogen is crucial for both waste discharge management and pollutants cleanup. This study was aimed to 1) understand the spatial distribution of abnormally high ammonium groundwater in the Quaternary basalt aquifer in the Pearl River Delta (PRD), China; 2) to distinguish sources of recharge to the basalt aquifer; and 3) to identify the origin of the ammonium in the aquitard and aquifer system. Total 40 boreholes were drilled, and approximately 1000 deposit samples from the aquitard and over 200 groundwater samples from the Quaternary basalt aquifer were collected. A cluster of 7 piezometers was installed in Minzhong Town to study the hydraulic relationships between the aquitard and the basalt aquifer. The results demonstrated that the greater groundwater ammonium concentrations were preserved in the aquifer buried deeper. The ammonium concentration up to 390 mg/L was observed in the basalt sand and gravel Pleistocene aquifer of 20-50m deep, and this is the greatest concentration ever reported for natural groundwater globally. The Quaternary aquitard, which contained abundant sedimentary organic matter and was mainly composed of silt and clay, provided a strict anaerobic environment for sedimentary organic matter mineralization and ammonium preservation. Ammonium concentrations in the aquifer were predominantly controlled by the aquitard ammonium content. This naturally occurring abnormally high ammonium in the Quaternary sediments is areally extensive (over 1600 km2). Great groundwater salinity originated from a marine source redounded to the release of adsorbed ammonium to groundwater via ion exchange processes. This naturally originated high ammonium groundwater may find its way to the river channels and estuary. The flow paths are likely shortened by sand dredging activities Literature shows that no particular studies have been developed for ammonium research in delta aquitards and aquifers. The geological settings of fine texture of delta sediments containing abundant sedimentary organic matter are not unique to the PRD, and this “geological” ammonium may not be an uncommon source of nitrogen and may present as a large and hitherto unappreciated source of nitrogen for surface water bodies.

Wang, Y.; Jiao, J. J.; Cherry, J.

2010-12-01

204

Hydrothermal synthesis of ammonium illite  

USGS Publications Warehouse

Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

Sucha, V.; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.

1998-01-01

205

Effect of impurities on crystal growth rate of ammonium pentaborate  

NASA Astrophysics Data System (ADS)

The effect of sodium chloride, borax and boric acid of different concentrations on the growth rate of ammonium pentaborate octahydrate crystals (APBO) was measured and was found to depend on supersaturation in a fluidized bed crystallizer. The presence of impurities in APBO solution increases the growth rate compared with growth from pure solution. It was found that the presence of sodium chloride, borax and boric acid decreases the reaction rate constant kr, while it increases the mass-transfer coefficient, K, of APBO crystals. In pure aqueous solution, the crystal growth rate of APBO is mainly controlled by diffusion. However, both diffusion and integration steps affect the growth rate of APBO crystals in the presence of sodium chloride, borax and boric acid. The mass-transfer coefficient, K, reaction rate constant, kr and reaction order, r were calculated from general mass-transfer equation by using genetic algorithm method making no assumption.

?ahin, Ö.; Özdemir, M.; Genli, N.

2004-01-01

206

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation...176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a) This...

2012-10-01

207

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation...176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a) This...

2010-10-01

208

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 Transportation...176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a) This...

2013-10-01

209

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

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation...176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a) This...

2011-10-01

210

76 FR 70366 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013

...DHS-2008-0076] RIN 1601-AA52 Ammonium Nitrate Security Program AGENCY: National Protection...rulemaking (NPRM), entitled ``Ammonium Nitrate Security Program,'' which was published...62311). Under the proposed Ammonium Nitrate Security Program, the DHS will...

2011-11-14

211

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 basis...the antidumping duty order on ammonium nitrate from Russia would be likely to lead to...4249 (August 2011), entitled Ammonium Nitrate from Russia: Investigation No....

2011-08-04

212

76 FR 11273 - Ammonium Nitrate From Russia  

Federal Register 2010, 2011, 2012, 2013

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

2011-03-01

213

The Quaternary History of Scandinavia  

NASA Astrophysics Data System (ADS)

During the Quaternary Period, Scandinavia's mountains were the source for repeated glaciation that covered much of eastern, central and western Europe. With a particular emphasis on Denmark, Norway, Sweden and Finland, this text describes how these glaciations, and their intervening warmer stages, affected Scandinavia and the surrounding areas. In particular, this account focuses on the last cold stage, the Weichselian, with its extensive Late Weichselian glaciation and the subsequent deglaciation, and on the last 10,000 years, the Holocene, with its well documented environmental changes. The Quaternary History of Scandinavia provides a cross-frontier synthesis of how the glaciation affected this vast region.

Donner, Joakim

2005-08-01

214

Quaternary alkaloids of Argemone mexicana.  

PubMed

Four quaternary isoquinoline alkaloids, dehydrocorydalmine, jatrorrhizine, columbamine, and oxyberberine, have been isolated from the whole plant of Argemone mexicana Linn. (Papaveraceae) and their structures established by spectral evidence. This is the first report of these alkaloids (dehydrocorydalmine, jatrorrhizine, columbamine, and oxyberberine) from Argemone mexicana and the Argemone genus. PMID:20645832

Singh, Sarita; Singh, Tryambak Deo; Singh, Virendra Pratap; Pandey, Vidya Bhushan

2010-02-01

215

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

216

Deliquescence, Efflorescence, and Water Activity in Ammonium Nitrate and Mixed Ammonium Nitrate/Succinic Acid Microparticles  

E-print Network

Deliquescence, Efflorescence, and Water Activity in Ammonium Nitrate and Mixed Ammonium Nitrate of ammonium nitrate/water and mixed ammonium nitrate/succinic acid/water microparticles. The water activity of ammonium nitrate microparticles is determined as a function of composition down to 12% relative humidity

217

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

218

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

219

Andrei Sher and Quaternary science  

NASA Astrophysics Data System (ADS)

Andrei Sher (1939-2008) was a key individual in Beringian studies who made substantial and original contributions, but also, importantly, built bridges between western and eastern Beringian scientists spanning some five decades of research. He is perhaps best known as a Quaternary palaeontologist, specializing in large mammals, and mammoths in particular, but his field of his scientific research was much broader, encompassing Quaternary geology, stratigraphy, geocryology, and paleoenvironmental reconstructions. He worked mainly in Siberia, in the Kolyma and Indigirka lowlands, and Chukotka, but also completed fieldwork in Alaska and Yukon through joint projects with American and Canadian scientists. Andrei was an active scientist until the last days of his life. He was involved in many different research projects ranging from mammoth evolution, fossil insects and environmental changes and ancient DNA. Without Andrei's connections between researchers, many unique discoveries would likely be unknown.

Kuzmina, Svetlana; Lister, Adrian M.; Edwards, Mary E.

2011-08-01

220

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

221

Quaternary glaciation of Mount Everest  

Microsoft Academic Search

The Quaternary glacial history of the Rongbuk valley on the northern slopes of Mount Everest is examined using field mapping, geomorphic and sedimentological methods, and optically stimulated luminescence (OSL) and 10Be terrestrial cosmogenic nuclide (TCN) dating. Six major sets of moraines are present representing significant glacier advances or still-stands. These date to >330ka (Tingri moraine), >41ka (Dzakar moraine), 24–27ka (Jilong

Lewis A. Owen; Ruth Robinson; Douglas I. Benn; Robert C. Finkel; Nicole K. Davis; Chaolu Yi; Jaakko Putkonen; Dewen Li; Andrew S. Murray

2009-01-01

222

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

223

Determinants of quaternary association in legume lectins  

PubMed Central

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. The class of proteins called legume lectins is an interesting model system to investigate this problem, because they have very high sequence and tertiary structure homology, with diverse forms of quaternary association. Hence, we have used legume lectins as a probe in this paper to (1) gain novel insights about the relationship between sequence and quaternary structure; (2) identify the sequence motifs that are characteristic of a given type of quaternary association; and (3) predict the quaternary association from the sequence motif. PMID:15215518

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

2004-01-01

224

Cyclo-hexyl-ammonium 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

225

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

226

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

227

Mercuric chloride poisoning  

MedlinePLUS

Mercuric chloride is a very poisonous form of mercury. It is a type of mercury salt. There are ... mercury poisonings . This article discusses poisoning from swallowing mercuric chloride. This is for information only and not for ...

228

TOXICOLOGICAL REVIEW OF METHYL CHLORIDE [AND IRIS SUMMARY] (EXTERNAL PEER REVIEW DRAFT)  

EPA Science Inventory

Methyl chloride (CAS No. 74-87-3) is a gaseous chlorohydrocarbon under ambient conditions. It is principally used in the manufacture of silicones, agrichemicals, methyl cellulose and quaternary amines. Numerous case reports involving overexposure over the last 60 years indicate t...

229

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2010 CFR

...Affirmed as GRAS § 184.1137 Ammonium carbonate. (a) Ammonium carbonate ((NH4 )2 CO3 , CAS Reg. No. 8000-73-5...sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard,...

2010-04-01

230

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2013 CFR

...Affirmed as GRAS § 184.1137 Ammonium carbonate. (a) Ammonium carbonate ((NH4 )2 CO3 , CAS Reg. No. 8000-73-5...sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard,...

2013-04-01

231

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2011 CFR

...Affirmed as GRAS § 184.1137 Ammonium carbonate. (a) Ammonium carbonate ((NH4 )2 CO3 , CAS Reg. No. 8000-73-5...sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard,...

2011-04-01

232

21 CFR 184.1137 - Ammonium carbonate.  

Code of Federal Regulations, 2012 CFR

...Affirmed as GRAS § 184.1137 Ammonium carbonate. (a) Ammonium carbonate ((NH4 )2 CO3 , CAS Reg. No. 8000-73-5...sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard,...

2012-04-01

233

21 CFR 184.1137 - Ammonium carbonate.  

...Affirmed as GRAS § 184.1137 Ammonium carbonate. (a) Ammonium carbonate ((NH4 )2 CO3 , CAS Reg. No. 8000-73-5...sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard,...

2014-04-01

234

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

235

Ammonium content and buoyancy in midwater cephalopods  

E-print Network

Ammonium content and buoyancy in midwater cephalopods Brad A. Seibela,*, Shana K. Goffredib , Erik for neutral buoyancy. However, previous methods for measuring ammonium did not distinguish between NH4 Elsevier B.V. All rights reserved. Keywords: Buoyancy; Ammonium; Cephalopoda; Locomotion; Deep-sea; Pelagic

Thuesen, Erik V.

236

76 FR 62311 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013

...DHS-2008-0076] RIN 1601-AA52 Ammonium Nitrate Security Program AGENCY: National Protection...rulemaking (NPRM), entitled ``Ammonium Nitrate Security Program,'' which was published...regulate the sale and transfer of ammonium nitrate pursuant to section 563 of the...

2011-10-07

237

Ancient biomolecules in Quaternary palaeoecology  

NASA Astrophysics Data System (ADS)

The last few years have seen an enormous proliferation of ancient biomolecules research, especially in the field of ancient DNA. Ancient DNA studies have been transformed by the advent of next generation sequencing, with the first Pleistocene sample being analysed in 2005, and several complete and draft genomes that have been compiled from ancient DNA to date. At the same time, although less conspicuous, research on ancient proteins has also seen advances, with the time limit for research on ancient biomolecules now extending to over 1 million years. Here we review which effects these developments have on research in Quaternary science. We identify several lines of research that have the potential to profit substantially from these recent developments in ancient biomolecules research. First, the identification of taxa can be made using ancient biomolecules, and in the case of ancient DNA, specimens can even be assigned to specific populations within a species. Second, increasingly large DNA data sets from Pleistocene animals allow the elucidation of ever more precise pictures of the population dynamic processes whereby organisms respond to climate and environmental change. With the accompanying better understanding of process in the Quaternary, past ecologies can also more realistically be interpreted from proxy data sets. The dominant message from this research so far is that the Quaternary saw a great deal more dynamism in populations than had been forecast by conventional palaeoecology. This suggests that reconstructions of past environmental conditions need to be done with caution. Third, ancient DNA can also now be obtained directly from sediments to elucidate the presence of both plant and animal species in an area even in the absence of identifiable fossils, be it macro- or micro-fossils. Finally, the analysis of proteins enables the identification of bone remains to genus and sometimes species level far beyond the survival time of DNA, at least in temperate regions, illustrating that precise data is now forthcoming from seemingly unlikely sources. Together, these approaches allow the study of environmental dynamics throughout a substantial part, and perhaps even the entire Quaternary (the last 2.6 million years).

Hofreiter, Michael; Collins, Matthew; Stewart, John R.

2012-02-01

238

Phase diagram of ammonium nitrate  

NASA Astrophysics Data System (ADS)

Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.

Dunuwille, M.; Yoo, C. S.

2014-05-01

239

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

240

Quaternary glaciation of the Himalayan-Tibetan  

Microsoft Academic Search

Glacial geological evidence from throughout the Himalayan-Tibetan orogen is examined to determine the timing and extent of late Quaternary glaciation in this region and its relation to similar changes on a global scale. The evidence summarised here supports the existence of expanded ice caps and extensive valley glacier systems throughout the region during the late Quaternary. However, it cannot yet

LEWIS A. OWEN; MARC W. CAFFEE; ROBERT C. FINKEL; YEONG BAE SEONG

241

Ammonium removal from aqueous solutions by using natural Chinese (Chende) zeolite as adsorbent.  

PubMed

This paper presents a study of the removal of ammonium ion from aqueous solutions using natural Chinese (Chende) zeolite. A series of experiments was conducted to examine the effects of solution pH, particle size, contact time, adsorbent dosage, and the presence of other cation- and anion species on ammonium removal. The findings indicated that these parameters named had a significant effect on the removal of ammonium by the zeolite. The effect of other cations on the removal of ammonium followed the order of preference Na(+)>K(+)>Ca(2+)>Mg(2+) at identical mass concentrations, and the effect of the presence of individual anions followed the order of preference carbonate>chloride>sulfate>phosphate at identical mass concentrations of ammonium ions. Kinetic analysis showed that the adsorption of ammonium on zeolite at different ranges of particle size well followed the pseudo-second-order model and followed the intra-particle diffusion model only during the initial 60 min of the adsorption process. Equilibrium isotherm data was fitted to the linear Langmuir- and Freundlich models with the latter model providing the better description of the process (R(2)=0.991-0.997) compared to the former (R(2)=0.902-0.989). PMID:19875231

Huang, Haiming; Xiao, Xianming; Yan, Bo; Yang, Liping

2010-03-15

242

Influence of Ammonium Salts and Cane Molasses on Growth of Alcaligenes eutrophus and Production of Polyhydroxybutyrate  

PubMed Central

The production of polyhydroxybutyrate (PHB) by Alcaligenes eutrophus DSM 545 was studied in a synthetic medium with 3% glucose at pH 7.0 supplemented with several ammonium substrates and cane molasses. Growth was measured by dry cell weight, and the PHB content was measured by gas chromatography. The effects of ammonium sources such as sulfate, nitrate, phosphate, and chloride salts and those of different ammonium sulfate concentrations were evaluated. The best growth and PHB production were obtained with ammonium sulfate; however, NH(inf4)(sup+) concentrations between 0.5 and 1.5 g/liter showed no significant difference. Ammonium sulfate was therefore used as the sole source of NH(inf4)(sup+) for experiments with cane molasses as the growth activator. Optimal growth and PHB production were obtained with 0.3% molasses. However, the yields of biomass (39 to 48%) and PHB (17 to 26%) varied significantly among the different ammonium substrates and cane molasses concentrations. PMID:16534900

Beaulieu, M.; Beaulieu, Y.; Melinard, J.; Pandian, S.; Goulet, J.

1995-01-01

243

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

Code of Federal Regulations, 2013 CFR

...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate...

2013-10-01

244

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

Code of Federal Regulations, 2012 CFR

...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate...

2012-10-01

245

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

Code of Federal Regulations, 2011 CFR

...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate...

2011-10-01

246

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

Code of Federal Regulations, 2010 CFR

...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415...Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate...

2010-10-01

247

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...bis(fattyalkyl) dimethyl, salts with tannins (generic...bis(fattyalkyl) dimethyl, salts with tannins (PMN P-12-437...j). (ii) Release to water. Requirements as...

2013-07-01

248

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

NASA Astrophysics Data System (ADS)

A new borate [C6H16N][B5O6(OH)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 [B5O6(OH)4]- anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH3)3(i-C3H7) N+ 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.

Liang, Jie; Wang, Yong-gang; Wang, Ying-xia; Liao, Fu-hui; Lin, Jian-hua

2013-04-01

249

Studies on extraction of thorium from nitrate solutions with quaternary ammonium halides.  

PubMed

Thorium can be quantitatively extracted with 0.1 M Hyamine 1622 in dichloroethane from 0.25M nitric acid/2M sodium nitrate and stripped from the organic phase with 0.1M sulphuric acid. The equilibration takes 20 min. Thorium can thus be separated from a large number of elements which are usually associated with it in monazite and in fission products of nuclear fuel. PMID:18963665

El-Yamani, I S; Shabana, E I

1984-08-01

250

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

251

Comparing Effectiveness of Rhamnolipid Biosurfactant with a Quaternary Ammonium Salt Surfactant for Hydrate Anti-Agglomeration  

Microsoft Academic Search

Natural gas is projected to be the premium fuel of the 21st century because of availability, as well as economical and environmental considerations. Natural gas is coproduced with water from the subsurface forming gas hydrates. Hydrate formation may result in shutdown of onshore and offshore operations. Industry practice has been usage of alcoholsswhich have undesirable environmental impactssto affect bulk-phase properties

J. Dalton York; Abbas Firoozabadi

2008-01-01

252

Surface modification and antibacterial activity of electrospun polyurethane fibrous membranes with quaternary ammonium moieties  

Microsoft Academic Search

A novel antibacterial material was developed by surface modification of electrospun polyurethane (PU) fibrous membranes, using a process which involved plasma pretreatment, UV-induced graft copolymerization of 4-vinylpyridine (4VP), and quaternization of the grafted pyridine groups with hexylbromide. The success of modification with poly(4-vinyl-N-hexyl pyridinium bromide) groups on these was ascertained by X-ray photoelectron spectroscopy (XPS). The morphologies and mechanical properties

Chen Yao; Xinsong Li; K. G. Neoh; Zhilong Shi; E. T. Kang

2008-01-01

253

Intriguing Role of a Quaternary Ammonium Cation in the Dissociation Chemistry of Keggin Polyoxometalate Anions  

NASA Astrophysics Data System (ADS)

The gas-phase fragmentations of a series of Keggin polyoxometalate anions with molecular formula of TBAn[XM12O40] (X = P, Si; M = Mo, W) were studied by electrospray ionization tandem mass spectrometry. The bare polyoxoanions [XM12O40]n- as well as the non-covalent complexes {TBA[XM12O40]}(n-1)- and {TBAm[XM12O40]2}3- displayed characteristic dissociation pathways. Fragmentation of [XM12O40]n- led to pairs of complementary product anions whose total stoichiometry and charge matched those of the precursor anion, consistent with the previous study by Ma et al. The nature of the non-covalent interaction between [XM12O40]n- and TBA+ was addressed in detail via the example of {TBA[XM12O40]}(n-1)-. The non-covalent interaction [1] primarily dominated by the Coulombic attraction of the opposite charges completely changed the dissociation chemistry of [XM12O40]n-. The non-covalent complexes {TBA[XM12O40]}(n-1)- and {TBAm[XM12O40]2}3-, formed by the charge reduction during the electrospray process, underwent distinct dissociation routes: {TBA[XM12O40]}(n-1)- fragmented to give rise to its product ion {(C4H9)[XM12O40]}(n-1)- by cleaving the N-C covalent bond inside the TBA+ cation whereas {TBAm[XM12O40]2}3- dissociated into a pair of product ions, {TBAi[XM12O40]}2- and {TBAm-i[XM12O40]}-, by breaking the non-covalent bond between [XM12O40]n- and TBA+. In addition, energy-variable CID was used to map the relative stabilities of the ion clusters in the gas phase, which was in excellent agreement with the relative orders of thermal stability in the condensed phase.

Cao, Jie; Li, Chenchen; Zhang, Zhengxiang; Xu, Chong; Yan, Jie; Cui, Fengyun; Hu, Changwen

2012-02-01

254

Interactions between Quaternary Ammonium Surfactant Oligomers and Water-Soluble Modified Guars  

Microsoft Academic Search

The interaction between hydroxypropylguar (HPG) and its dodecyl-modified derivative (HMHPG) and cationic surfactant oligomers has been investigated by measurements of the solution viscosity at constant shear rate, microviscosity of the aggregates (dipyrenylpropane fluorescence emission spectra), and aggregation number of the polymer hydrophobe and of the surfactant (time-resolved fluorescence quenching). The surfactants are dodecyltrimethylammonium bromide (DTAB, monomeric surfactant) and some of

U. Kästner; R. Zana

1999-01-01

255

Comparison of the bacterial removal performance of silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane coated point-of-use ceramic water filters.  

PubMed

This study compares the disinfection performance of ceramic water filters impregnated with two antibacterial compounds: silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane (poly(trihydroxysilyl) propyldimethyloctadecyl ammonium chloride (TPA)). This study evaluated these compounds using ceramic disks manufactures with clay obtained from a ceramic filter factory located in San Mateo Ixtatan, Guatemala. Instead of using full size ceramic water filters, manufactured 6.5 cm diameter ceramic water filter disks were used. Results showed that TPA can achieve a log bacterial reduction value of 10 while silver nanoparticles reached up to 2 log reduction using a initial concentration of bacteria of 10(10)-10(11)CFU/ml. Similarly, bacterial transport demonstrated that ceramic filter disks painted with TPA achieved a bacterial log reduction value of 6.24, which is about 2 log higher than the values obtained for disks painted with silver nanoparticles (bacterial log reduction value: 4.42). The release of both disinfectants from the ceramic materials to the treated water was determined measuring the effluent concentrations in each test performed. Regarding TPA, about 3% of the total mass applied to the ceramic disks was released in the effluent over 300 min, which is slightly lower than the release percentage for silver nanoparticles (4%). This study showed that TPA provides a comparable disinfection performance than silver nanoparticles in ceramic water filter. Another advantage of using TPA is the cost as the price of TPA is considerable lower than silver nanoparticles. In spite of the use of TPA in several medical related products, there is only partial information regarding the health risk associated with the ingestion of this compound. Additional long-term toxicological information for TPA should be evaluated before its future application in ceramic water filters. PMID:23770490

Zhang, Hongyin; Oyanedel-Craver, Vinka

2013-09-15

256

Ammonium Metabolism in the Green Hydra Symbiosis  

Microsoft Academic Search

Abstract. Inhibitors of enzymes,of ammonium,assimi- lation were used to test if assimilation of ammonium,in the green,hydra-Chlorella symbiosis,was,due,to host or symbionts. Both methionine sulphoximine (MSX, an in- hibitor of glutamine synthetase, found in both host and symbionts) and azaserine (AZS, an inhibitor of 2-oxoglu- tarate amido transferase, not found in the host) inhibited ammonium,uptake by the intact symbiosis. MSX was taken

P. J. Mcauley

1995-01-01

257

ANAEROBIC AMMONIUM OXIDATION IN THE MARINE ENVIRONMENT  

Microsoft Academic Search

Oceanographers noticed already many years ago that far less ammonium accumulated in anoxic fjords and basins, than would be\\u000a expected from the stoichiometry of heterotrophic denitrification. It was suggested that this ‘missing’ ammonium was oxidized\\u000a with nitrate to freeN2. Since then several otherworkers have argued based on chemical profiles that ammonium is oxidized anaerobically in oxygen\\u000a deficient marine sediments and

Marcel M. M. Kuypers; Gaute Lavik; Bo Thamdrup

258

Construction of quaternary stereogenic carbon centers through copper-catalyzed enantioselective allylic cross-coupling with alkylboranes.  

PubMed

A combination of an in situ generated chiral Cu(I) /DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective SN 2'-type allylic cross-coupling between alkylborane reagents and ?,?-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3) -alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross-coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed. PMID:24668885

Hojoh, Kentaro; Shido, Yoshinori; Ohmiya, Hirohisa; Sawamura, Masaya

2014-05-01

259

Strontium-89 Chloride  

MedlinePLUS

Your doctor has ordered the drug strontium-89 chloride to help treat your illness. The drug is given by injection into a vein or a catheter that ... Strontium-89 chloride is in a class of drugs known as radioisotopes. It delivers radiation to cancer ...

260

33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...  

...Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126.28 Navigation and...

2014-07-01

261

33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...  

Code of Federal Regulations, 2013 CFR

...Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126.28 Navigation and...

2013-07-01

262

33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...  

Code of Federal Regulations, 2011 CFR

...Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126.28 Navigation and...

2011-07-01

263

33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...  

Code of Federal Regulations, 2012 CFR

...Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126.28 Navigation and...

2012-07-01

264

33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...  

Code of Federal Regulations, 2010 CFR

...Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126.28 Navigation and...

2010-07-01

265

Enantioselective Construction of Remote Quaternary Stereocenters  

PubMed Central

Summary Molecules containing all-carbon quaternary stereocenters – carbon atoms bonded to four distinct carbon substituents – are prevalent in Nature. However, the construction of such compounds in an enantioselective fashion remains a long-standing challenge to synthetic organic chemists. In particular, methods for forging quaternary stereocenters that are remote from other functional groups are underdeveloped. Herein we report a catalytic and enantioselective intermolecular Heck-type reaction of trisubstituted-alkenyl alcohols with aryl boronic acids. The reported method allows direct access to quaternary all-carbon-substituted ?-, ?-, ?-, ?- or ? aryl carbonyl compounds, as the unsaturation of the alkene is relayed to the alcohol resulting in the formation of a carbonyl group. The scope of the process also includes incorporation of pre-existing stereocenters along the alkyl chain, which links the alkene and the alcohol, wherein the stereocenter is preserved. The described method is flexible, allowing access to diverse building blocks containing an enantiomerically enriched, quaternary center. PMID:24717439

Mei, Tian-Sheng; Patel, Harshkumar H.; Sigman, Matthew S.

2014-01-01

266

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2012 CFR

...70 percent of ammonium nitrate and a maximum of 0.4 percent combustible material; (2) Ammonium nitrate with calcium carbonate and/or dolomite, containing more than 80 percent but less than 90 percent of ammonium nitrate and a maximum...

2012-10-01

267

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2013 CFR

...70 percent of ammonium nitrate and a maximum of 0.4 percent combustible material; (2) Ammonium nitrate with calcium carbonate and/or dolomite, containing more than 80 percent but less than 90 percent of ammonium nitrate and a maximum...

2013-10-01

268

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2011 CFR

...70 percent of ammonium nitrate and a maximum of 0.4 percent combustible material; (2) Ammonium nitrate with calcium carbonate and/or dolomite, containing more than 80 percent but less than 90 percent of ammonium nitrate and a maximum...

2011-10-01

269

Field leaching of alkaline copper quaternary-treated red pine lumber over 3 years: long-term dynamics.  

PubMed

Alkaline copper quaternary (ACQ), a wood preservative, consists of copper oxide and quaternary ammonium compounds. Three red pine piles were monitored over 3 years to evaluate the dynamics of contaminant leaching from ACQ-treated and untreated lumber. There were small temporal changes in the volumetric leachate/rain ratio with the ACQ-treated lumber, while the volumetric ratio decreased across the 3 years with the untreated lumber, most likely due to considerable weathering that increased the capacity of the untreated lumber to absorb rain water. The average copper (Cu) concentration in leachate from the ACQ-treated lumber (4,033 ?g/L) was much higher than that in leachate from the untreated lumber (87 ?g/L) and rain (48 ?g/L) in the first leaching year. Cu concentration in leachate from the ACQ-treated lumber in the second and third years decreased to 46-51% of that in the first year. There were significant seasonal decreases of Cu concentration in leachate from the ACQ-treated lumber, which were correlated to exposure time and meteorological parameters. ACQ-treatment did not affect leachate pH and concentrations of quaternary ammonium compounds and chemical oxygen demand. There were insignificant temporal changes of leachate pH and concentrations of chemical oxygen demand and total dissolved solids in leachate from both ACQ-treated and untreated lumber piles. PMID:24718339

Tao, Wendong

2014-01-01

270

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

271

Nitric oxide supplementation alleviates ammonium toxicity in the submerged macrophyte Hydrilla verticillata (L.f.) Royle.  

PubMed

The likely protective effects of nitric oxide (NO) against ammonium toxicity were investigated in the submerged macrophyte Hydrilla verticillata. The plants were subjected to ammonium stress (3mM ammonium chloride) in the presence of sodium nitroprusside (SNP, 10 ?M), an NO donor. Treatment with SNP significantly increased the NO content and partially reversed the ammonium-induced negative effects, including membrane damage and the decrease in levels of chlorophyll, malondialdehyde, glutathione and ascorbic acid. Further, SNP application increased the catalytic activities of ascorbate peroxidase, superoxide dismutase, guaiacol peroxidase, catalase and glutathione S-transferase, but decreased that of NADH-oxidase. Histochemical staining showed that SNP application caused a significant decrease in the levels of superoxides and hydrogen peroxide. In contrast, application of other breakdown products of SNP (10 ?M sodium ferrocyanide, 10 ?M sodium nitrite and 10 ?M sodium nitrate) failed to show any protective effect. The results suggest that the increased intracellular NO, resulting from SNP application, improved the antioxidant capacity of H. verticillata plants in coping with ammonium-induced oxidative stress. PMID:20655590

Wang, Chao; Zhang, Song He; Li, Wei; Wang, Pei Fang; Li, Li

2011-01-01

272

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-Sanchez, Luis; Martinez-Manez, Ramon

2013-01-01

273

Ammonium repression of nitrate reductase formation in Lemna minor L  

Microsoft Academic Search

The presence of ammonium is shown to inhibit the nitrate-promoted formation of nitrate reductase in Lemna minor L. The ammonium inhibition does not result from an inhibition of nitrate accumulation. The kinetics of the ammonium inhibition suggest it is not a direct effect of ammonium. The inhibition could result from the build up of a product of ammonium assimilation or

T. O. Orebamjo; G. R. Stewart

1975-01-01

274

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

275

Quaternary geologic map of Minnesota  

NASA Technical Reports Server (NTRS)

The Quaternary Geologic Map of Minnesota is a compilation based both on the unique characteristics of satellite imagery and on the results of previous field investigations, both published and unpublished. The use of satellite imagery has made possible the timely and economical construction of this map. LANDSAT imagery interpretation proved more useful than expected. Most of the geologic units could be identified by extrapolating from specific sites where the geology had been investigated into areas where little was known. The excellent geographic registry coupled with the multi-spectral record of these images served to identify places where the geologic materials responded to their ecological environment and where the ecology responded to the geologic materials. Units were well located on the map at the scale selected for the study. Contacts between till units could be placed with reasonable accuracy. The reference points that were used to project delineations between units (rivers, lakes, hills, roads and other features), which had not been accurately located on early maps, could be accurately located with the help of the imagery. The tonal and color contrasts, the patterns reflecting geologic change and the resolution of the images permitted focusing attention on features which could be represented at the final scale of the map without distraction by other interesting but site-specific details.

Goebel, J. E.

1977-01-01

276

Quaternary glaciation of Mount Everest  

NASA Astrophysics Data System (ADS)

The Quaternary glacial history of the Rongbuk valley on the northern slopes of Mount Everest is examined using field mapping, geomorphic and sedimentological methods, and optically stimulated luminescence (OSL) and 10Be terrestrial cosmogenic nuclide (TCN) dating. Six major sets of moraines are present representing significant glacier advances or still-stands. These date to >330 ka (Tingri moraine), >41 ka (Dzakar moraine), 24-27 ka (Jilong moraine), 14-17 ka (Rongbuk moraine), 8-2 ka (Samdupo moraines) and ˜1.6 ka (Xarlungnama moraine), and each is assigned to a distinct glacial stage named after the moraine. The Samdupo glacial stage is subdivided into Samdupo I (6.8-7.7 ka) and Samdupo II (˜2.4 ka). Comparison with OSL and TCN defined ages on moraines on the southern slopes of Mount Everest in the Khumbu Himal show that glaciations across the Everest massif were broadly synchronous. However, unlike the Khumbu Himal, no early Holocene glacier advance is recognized in the Rongbuk valley. This suggests that the Khumbu Himal may have received increased monsoon precipitation in the early Holocene to help increase positive glacier mass balances, while the Rongbuk valley was too sheltered to receive monsoon moisture during this time and glaciers could not advance. Comparison of equilibrium-line altitude depressions for glacial stages across Mount Everest reveals asymmetric patterns of glacier retreat that likely reflects greater glacier sensitivity to climate change on the northern slopes, possibly due to precipitation starvation.

Owen, Lewis A.; Robinson, Ruth; Benn, Douglas I.; Finkel, Robert C.; Davis, Nicole K.; Yi, Chaolu; Putkonen, Jaakko; Li, Dewen; Murray, Andrew S.

2009-07-01

277

Ice Age refugia and Quaternary extinctions: An issue of Quaternary evolutionary palaeoecology  

NASA Astrophysics Data System (ADS)

Quaternary palaeoecology, as a discipline, involves the analysis of a large range of fossil organisms from the last ca. 2 million years. This paper considers the role that these Quaternary records can take in better understanding the evolution of those organisms. We also discuss the surprisingly low uptake of evolutionary biology in Quaternary palaeoecological studies. This leads us to encourage an advance on both these fronts with a greater degree of collaboration with phylogeographic and ancient DNA researchers. These discussions accompany a summary of a special issue of Quaternary Science Reviews representing the proceedings of the XVII INQUA held in Cairns Australia in 2007. This special issue includes papers on a wide variety of Quaternary evolutionary palaeoecological and population dynamic subjects including extinct Pacific Island palm trees, Beringian beetles, Scandinavian trees, and the effects on human and animal populations of an extraterrestrial impact event in the Late Glacial of North America.

Stewart, John R.; Cooper, Alan

2008-12-01

278

40 CFR 721.6070 - Alkyl phosphonate ammonium salts.  

Code of Federal Regulations, 2011 CFR

... Alkyl phosphonate ammonium salts. 721.6070 Section 721... Alkyl phosphonate ammonium salts. (a) Chemical substances...as alkyl phosphonate ammonium salts (PMNs P-93-725 and P-93-726...uses are: (i) Release to water. Requirements as...

2011-07-01

279

40 CFR 721.6070 - Alkyl phosphonate ammonium salts.  

Code of Federal Regulations, 2013 CFR

... Alkyl phosphonate ammonium salts. 721.6070 Section 721... Alkyl phosphonate ammonium salts. (a) Chemical substances...as alkyl phosphonate ammonium salts (PMNs P-93-725 and P-93-726...uses are: (i) Release to water. Requirements as...

2013-07-01

280

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

281

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

282

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 the basis...antidumping duty order on certain ammonium nitrate from Ukraine would be likely to lead to...May 2013), entitled Certain Ammonium Nitrate from Ukraine: Investigation No....

2013-05-31

283

40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...General . Tolerances are established for residues of the herbicide glufosinate ammonium, including its metabolites...are established for indirect or inadvertent residues of the herbicide glufosinate ammonium, including...

2012-07-01

284

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

285

Development of new ammonium nitrate composite explosives. Final report, October 1982-January 1984. [Ammonium salt of 5-nitrotetrazole (ANT); ethylene diamine salt of 5-nitrotetrazole (ENT); diethylene triamine trinitrate (DETN); ethylene diaminedinitrate (EDD)  

SciTech Connect

Studies of several ammonium nitrate (AN)-based composite explosive systems were continued from earlier work. The critical temperature (T/sub c/) of AN/ANT, AN/ENT, and AN/DETN systems were measured and their thermal stabilities evaluated. We have also studied the effect of ENT on the melt temperature of EA (EDD/AN) and found that ENT forms a eutectic with EA. The eutectic temperature of the ternary system AN/EDD/ENT (AENT) is 89/sup 0/C. Results from an initial phase-diagram study of the quaternary system AN/KN/EDD/DETN (DEAK) are also presented. 4 refs., 9 figs., 5 tabs.

Lee, K.Y.

1985-03-01

286

Surface behavior of hydrated guanidinium and ammonium ions: a comparative study by photoelectron spectroscopy and molecular dynamics.  

PubMed

Through the combination of surface sensitive photoelectron spectroscopy and molecular dynamics simulation, the relative surface propensities of guanidinium and ammonium ions in aqueous solution are characterized. The fact that the N 1s binding energies differ between these two species was exploited to monitor their relative surface concentration through their respective photoemission intensities. Aqueous solutions of ammonium and guanidinium chloride, and mixtures of these salts, have been studied in a wide concentration range, and it is found that the guanidinium ion has a greater propensity to reside at the aqueous surface than the ammonium ion. A large portion of the relative excess of guanidinium ions in the surface region of the mixed solutions can be explained by replacement of ammonium ions by guanidinium ions in the surface region in combination with a strong salting-out effect of guanidinium by ammonium ions at increased concentrations. This interpretation is supported by molecular dynamics simulations, which reproduce the experimental trends very well. The simulations suggest that the relatively higher surface propensity of guanidinium compared with ammonium ions is due to the ease of dehydration of the faces of the almost planar guanidinium ion, which allows it to approach the water-vapor interface oriented parallel to it. PMID:24871810

Werner, Josephina; Wernersson, Erik; Ekholm, Victor; Ottosson, Niklas; Ohrwall, Gunnar; Heyda, Jan; Persson, Ingmar; Söderström, Johan; Jungwirth, Pavel; Björneholm, Olle

2014-06-26

287

Late Quaternary history of Washington Land, North Greenland OLE BENNIKE  

E-print Network

Late Quaternary history of Washington Land, North Greenland OLE BENNIKE Bennike, O. 2002 (September): Late Quaternary history of Washington Land, North Greenland. Boreas, Vol. 31, 260­272. Oslo. ISSN 0300 Quaternary history of the region. The lack of data re ects the inaccessibility of this remote region

Ingólfsson, �lafur

288

21 CFR 184.1135 - Ammonium bicarbonate.  

Code of Federal Regulations, 2011 CFR

...bicarbonate (NH4 HCO3 , CAS Reg. No. 1066-33-7) is prepared by reacting gaseous carbon dioxide with aqueous ammonia. Crystals of ammonium bicarbonate are precipitated from solution and subsequently washed and dried. (b) The ingredient...

2011-04-01

289

21 CFR 184.1143 - Ammonium sulfate.  

Code of Federal Regulations, 2010 CFR

...sulfate ((NH4 )2 SO4 , CAS Reg. No. 7783-20-2) occurs naturally and consists of colorless or white, odorless crystals or granules. It is prepared by the neutralization of sulfuric acid with ammonium hydroxide. (b) The...

2010-04-01

290

21 CFR 184.1143 - Ammonium sulfate.  

...sulfate ((NH4 )2 SO4 , CAS Reg. No. 7783-20-2) occurs naturally and consists of colorless or white, odorless crystals or granules. It is prepared by the neutralization of sulfuric acid with ammonium hydroxide. (b) The...

2014-04-01

291

21 CFR 184.1135 - Ammonium bicarbonate.  

...bicarbonate (NH4 HCO3 , CAS Reg. No. 1066-33-7) is prepared by reacting gaseous carbon dioxide with aqueous ammonia. Crystals of ammonium bicarbonate are precipitated from solution and subsequently washed and dried. (b) The ingredient...

2014-04-01

292

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

293

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

294

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

295

Enantioselective construction of remote quaternary stereocentres  

NASA Astrophysics Data System (ADS)

Small molecules that contain all-carbon quaternary stereocentres--carbon atoms bonded to four distinct carbon substituents--are found in many secondary metabolites and some pharmaceutical agents. The construction of such compounds in an enantioselective fashion remains a long-standing challenge to synthetic organic chemists. In particular, methods for synthesizing quaternary stereocentres that are remote from other functional groups are underdeveloped. Here we report a catalytic and enantioselective intermolecular Heck-type reaction of trisubstituted-alkenyl alcohols with aryl boronic acids. This method provides direct access to quaternary all-carbon-substituted ?-, ?-, ?-, ?- or ?-aryl carbonyl compounds, because the unsaturation of the alkene is relayed to the alcohol, resulting in the formation of a carbonyl group. The scope of the process also includes incorporation of pre-existing stereocentres along the alkyl chain, which links the alkene and the alcohol, in which the stereocentre is preserved. The method described allows access to diverse molecular building blocks containing an enantiomerically enriched quaternary centre.

Mei, Tian-Sheng; Patel, Harshkumar H.; Sigman, Matthew S.

2014-04-01

296

Quaternary deformation mapping with ground penetrating radar  

Microsoft Academic Search

Ground penetrating radar (GPR) was used in a programme of geological and hydrogeological investigations into the Quaternary of west Cumbria, UK. The investigations were part of an extensive programme to determine the suitability of the area for a deep radioactive waste repository. The hydrogeological characteristics of the drift deposits are important since they affect both recharge and discharge. The glacially

J. P Busby; J. W Merritt

1999-01-01

297

Quaternary International 138139 (2005) 14 In Memorium  

E-print Network

awards include being named a fellow of the Geological Society of America in 2004. Geoff's major galvanizing efforts to apply surface exposure dating methods to date moraines in Peru and Bolivia. Results, Geology, Quaternary Research, and GSA Bulletin. Geoff was blessed with a combination of keen intellectual

Howat, Ian M.

298

Late Quaternary fire regimes of Australasia  

Microsoft Academic Search

We have compiled 223 sedimentary charcoal records from Australasia in order to examine the temporal and spatial variability of fire regimes during the Late Quaternary. While some of these records cover more than a full glacial cycle, here we focus on the last 70,000 years when the number of individual records in the compilation allows more robust conclusions. On orbital

S. D. Mooney; S. P. Harrison; P. J. Bartlein; A.-L. Daniau; J. Stevenson; K. C. Brownlie; S. Buckman; M. Cupper; J. Luly; M. Black; E. Colhoun; D. D’Costa; J. Dodson; S. Haberle; G. S. Hope; P. Kershaw; C. Kenyon; M. McKenzie; N. Williams

2011-01-01

299

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

300

Cyclohexene hydrogenation with molybdenum disulfide catalysts prepared by ex situ decomposition of ammonium thiomolybdate-cetyltrimethylammonium thiomolybdate mixtures  

Microsoft Academic Search

Ammonium tetrathiomolybdate (ATTM) is treated with cetyltrimethylammonium chloride (CTAC) using several ATTM\\/CTAC ratios. Reaction of ATTM with the limiting reagent CTAC gives the carbon-containing compound cetyltrimethylammonium tetrathio-molybdate (CTAT), resulting in different ATTM–CTAT mixtures or precursors which are then decomposed in N2 at 723K, yielding mesoporous samples with surface areas of over 260m2\\/g. Analysis by XRD and electron microscopy correspond to

R. Romero-Rivera; M. Del Valle; G. Alonso; E. Flores; F. Castillón; S. Fuentes; J. Cruz-Reyes

2008-01-01

301

SOURCE ASSESSMENT: POLYVINYL CHLORIDE  

EPA Science Inventory

This report summarizes data on air emissions from the polyvinyl chloride (PVC) industry. PVC is manufactured by 20 companies at 35 plants. Each plant uses one or more of four possible polymerization processes: (1) suspension polymerization, (2) emulsion polymerization, (3) bulk p...

302

Moxifloxacinium chloride monohydrate  

PubMed Central

The title compound {systematic name: 7-[(1S,6S)-8-aza-2-azonia­bicyclo­[4.3.0]non-8-yl]-1-cyclo­propyl-6-fluoro-8-meth­oxy-4-oxo-1,4-dihydro­quinoline-3-carb­oxy­lic acid chloride monohydrate}, C21H25FN3O4 +·Cl?·H2O, crystallizes with two moxi­floxa­cinium cations, two chloride ions and two uncoordinated water mol­ecules in the unit cell. The crystal structure has a pseudo-inversion center except for the chloride ions. In both moxi­floxa­cinium cations, the quinoline rings are approximately planar, the maximum atomic deviations being 0.107?(3) and 0.118?(3)?Å. The piperidine rings adopt a chair conformation while the pyrrolidine rings display a half-chair conformation. In the crystal, the carboxyl groups, the protonated piperidyl groups, the uncoordinated water mol­ecule and chloride anions participate in O—H?O, O—H?Cl and N—H?Cl hydrogen bonding; weak inter­molecular C—H?O and C—H?Cl hydrogen bonding is also present in the crystal structure. PMID:22058817

Qian, Jing-Jing; Gu, Jian-Ming; Shen, Jin; Hu, Xiu-Rong; Wu, Su-Xiang

2011-01-01

303

PHOTOOXIDATION OF ALLYL CHLORIDE  

EPA Science Inventory

The photooxidation of allyl chloride was studied by irradiation either in 100-L Teflon bags or in a 22.7-cu m Teflon smog chamber in the presence of added NOx. In the absence of added hydrocarbons, the reaction involves a Cl atom chain, which leads to a highly reactive system. A ...

304

Chloride ATPase Pumps in Epithelia  

Microsoft Academic Search

\\u000a Five widely documented mechanisms for chloride transport across biological membranes are known: anion-coupled antiport, Na+ and H(+)-coupled symport, Cl? channels and an electrochemical coupling process. These transport processes for chloride are either secondarily active or\\u000a are driven by the electrochemical gradient for chloride. Until recently, the evidence in favour of a primary active transport\\u000a mechanism for chloride has been inconclusive

George A. Gerencser

305

Index HT -Scoring Sheet A1. 0.1 M Citric Acid pH 3.5, 2.0 M Ammonium Sulfate  

E-print Network

.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, 3.0 M Sodium Chloride A11. 0.1 M HEPES pH 7.5, 3.0 M Sodium Chloride A12. 0.1 M Tris pH 8.5, 3.0 M

Hill, Chris

306

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

307

Nephrocalcinosis in chloride depleted rats  

Microsoft Academic Search

The ultrastructural features of the nephrocalcinosis associated with chloride depletion in the rat are described. The extent of calcification appeared to depend on the degree of chloride restriction. Within 3 days of chloride deprivation electron-dense granules were deposited on the brush border of proximal tubules in a concentric manner. Coalescence of satellite deposits formed large, lobulated liths with laminations, which

K. Sarkar; G. Tolnai; D. Z. Levine

1973-01-01

308

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 ...

309

Bis(cyclo-hexyl-ammonium) tetra-chlorido-diphenyl-stannate(IV)  

PubMed Central

The title compound, (C6H14N)2[Sn(C6H5)2Cl4], contains cyclo­hexyl­ammonium cations in general positions and a stannate(IV) anion that is located on a twofold rotation axis. The SnIV atom in the complex anion is surrounded by four Cl? ligands and two trans-phenyl groups in a distorted octa­hedral configuration. The anions are connected with the cations through N—H?Cl hydrogen bonds. Every cation is involved in three N—H?Cl bonds to the chloride ligands of three different anions, and each chloride ligand is linked to two cations. This arrangement leads to a layered structure parallel to (010). PMID:24940206

Sarr, Modou; Merkens, Carina; Diasse-Sarr, Aminata; Diop, Libasse; Englert, Ulli

2014-01-01

310

Bis(cyclo-hexyl-ammonium) tetra-chlorido-diphenyl-stannate(IV).  

PubMed

The title compound, (C6H14N)2[Sn(C6H5)2Cl4], contains cyclo-hexyl-ammonium cations in general positions and a stannate(IV) anion that is located on a twofold rotation axis. The Sn(IV) atom in the complex anion is surrounded by four Cl(-) ligands and two trans-phenyl groups in a distorted octa-hedral configuration. The anions are connected with the cations through N-H?Cl hydrogen bonds. Every cation is involved in three N-H?Cl bonds to the chloride ligands of three different anions, and each chloride ligand is linked to two cations. This arrangement leads to a layered structure parallel to (010). PMID:24940206

Sarr, Modou; Merkens, Carina; Diassé-Sarr, Aminata; Diop, Libasse; Englert, Ulli

2014-06-01

311

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

312

Tetra-methyl-ammonium hydrogen terephthalate.  

PubMed

The asymmetric unit of the title salt, C(4)H(12)N(+)·C(8)H(5)O(4) (-), contains one half of a tetra-methyl-ammonium 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 tetra-methyl-ammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C-H?O hydrogen bonds, generating a three-dimensional supra-molecular network. The carboxyl-ate 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

2012-10-01

313

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

314

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

315

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

316

Molecular doping of graphene with ammonium groups  

SciTech Connect

Successful doping of an electronic material entails the existence of stable dopant configurations that cause a shift in the Fermi level without altering significantly the electronic states of the host system. The selection of chemical groups that satisfy these conditions when adsorbed on graphene is still an open challenge. Here we show with first-principles calculations that ammonium groups meet the criteria of stable physisorption and efficient doping of graphene. We also describe processes of deactivation of ammonium dopants through their dissociation over graphene impurities or nanoribbon edges. Finally, we show that carbon nanotubes can be used to spatially confine the dopants and avert their edge-related de-activation.

Tsetseris, L. [Vanderbilt University; Pantelides, Sokrates T [ORNL

2012-01-01

317

Molecular doping of graphene with ammonium groups  

NASA Astrophysics Data System (ADS)

Successful doping of an electronic material entails the existence of stable dopant configurations that cause a shift in the Fermi level without altering significantly the electronic states of the host system. The selection of chemical groups that satisfy these conditions when adsorbed on graphene is still an open challenge. Here we show with first-principles calculations that ammonium groups meet the criteria of stable physisorption and efficient doping of graphene. We also describe processes of deactivation of ammonium dopants through their dissociation over graphene impurities or nanoribbon edges. Finally, we show that carbon nanotubes can be used to spatially confine the dopants and avert their edge-related de-activation.

Tsetseris, L.; Pantelides, S. T.

2012-04-01

318

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

319

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

320

Late quaternary sequence stratigraphy, South Florida margin  

SciTech Connect

Late Quaternary sea-level change and the Florida Current have combined to produce a progradational shelf-slope margin along the western portion of the south Florida Platform facing the Straits of Florida. Analysis of high resolution seismic reflection profiles suggest at least eight 5th order late Quaternary sequences downlap onto the Pourtales Terrace at 250 m water depth. Along most of the south Florida margin, this Late Quaternary section is very thin, and only where significant accumulations occur can the stratigraphic patterns produced by sea-level change be clearly observed. Recognition of systems tracts and their boundaries from high-resolution seismic data is important for prediction of sedimentary facies and stratigraphic development of margins. Many south Florida seismic boundaries can be fit to the Exxon sequence stratigraphy model. Others appear to reflect the added effect of bottom-current erosion that complicates the signal produced by sea-level change. Overall, the sea-level signal appears to dominate the stratigraphic record, especially from the 2-dimensional perspective of dip-oriented seismic profiles. However, the 3-dimensional geometry of deposits are strongly influenced by along slope accumulation patterns controlled by the Florida Current. This study provides new insight on the importance of both geostrophic boundary currents and sea-level change in controlling stratigraphic development of a carbonate platform margin. Similar anomalously thick slope deposits in ancient sequences may indicate similar controls on accumulation and could lend to predictions of related paleo-platform configurations.

Locker, S.D.; Hine, A.C. [Univ. of South Florida, St. Petersburg, FL (United States). Dept. of Marine Science

1995-12-01

321

Evidence of ammonium ion-exchange properties of natural bentonite and application to ammonium detection.  

PubMed

Ammonium exchange with hybrid PVC-bentonite (mineral montmorillonite clay) thin film was revealed using FTIR spectroscopy, EDX, cyclic voltammetry and electrochemical impedance spectroscopy. The effect of ammonium exchange on the charge transfer resistance of PVC-bentonite hybrid thin film was attributed to a modification of the intersheet distance and hydration of bentonite crystals. The obtained impedimetric ammonium sensor shows a linear range of detection from 10(-4)M to 1M and a detection limit around 10(-6)M. PMID:24094228

Zazoua, A; Kazane, I; Khedimallah, N; Dernane, C; Errachid, A; Jaffrezic-Renault, N

2013-12-01

322

Original article Ammonium assimilation and ureide metabolism  

E-print Network

during the vegeta- tive and two during the reproductive period. Salinity reduced plant dry weight by 25 2000; revised 17 July 2001; accepted 21 August 2001) Abstract ­ The effect of salinity on ammonium-assimilation enzymes, as well as on the enzymes of purine catabolism, was studied in root nodules of common bean plants

Paris-Sud XI, Université de

323

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

324

Modelling Ammonium Transporters in Arbuscular Mycorrhiza Symbiosis  

E-print Network

Modelling Ammonium Transporters in Arbuscular Mycorrhiza Symbiosis Mario Coppo1 , Ferruccio Damiani, the most wide-spread plant-fungus symbiosis on earth. Inves- tigating this kind of symbiosis is considered), the most widespread symbiosis between plants and fungi, got into the focus of research because of its

Troina, Angelo

325

Efficient siRNA delivery based on PEGylated and partially quaternized polyamine nanogels: Enhanced gene silencing activity by the cooperative effect of tertiary and quaternary amino groups in the core  

Microsoft Academic Search

For the development of an siRNA delivery system using polyion complexes (PICs) based on PEGylated nanogel consisting of a cross-linked poly[2-(N,N-diethylaminoethyl) methacrylate] (PEAMA) gel core and tethered poly(ethylene glycol) (PEG) chains, quaternary ammonium groups were introduced in the polyamine gel core to enhance the binding ability with siRNA and the stability of the PICs. Consequently, the quaternization of the polyamine

Atsushi Tamura; Motoi Oishi; Yukio Nagasaki

2010-01-01

326

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

327

Journal of Theoretical Biology 251 (2008) 93107 Erythrocyte lysis in isotonic solution of ammonium chloride  

E-print Network

sulphate and albumin in neutrally buffered isotonic saline, and (3) osmotic fragility test in hypotonic spherical cells. Three different processes were applied for erythrocytes sphering: (1) colloid osmotic lysis volume changes. If the hemolysis is of colloid-osmotic type, the cell swells and eventually lyses when

Amsterdam, Universiteit van

328

Flow and morphological conditions associated with the directional solidification of aqueous ammonium chloride  

SciTech Connect

Using 27% aq. NH[sub 4]Cl solutions as transparent analog, shadowgraphy and dye injection were used to observe flow and morphology in unidirectional solidification (UDS) from below. Dendritic crystals that form at the cold surface reject lighter, solute-deficient fluid, and instability is shown by finger-type double-diffusive convection. As the mushy two-phase region grows, perturbations at the liquidus interface cause localized remelting and downward development of channels. Solsutal plumes emanate from the channels, and in time, double-diffusive convection layers also form in the melt. When the solution is chilled at the sides as well as at the bottom, conditions are influenced by detachment and settling of crystals from the sidewall and by plumes from slanted channels. When a slow, oscillatory rocking motion is imposed on UDS, the freckle-type segregates in the final cast is suppressed. Within the melt, plumes and double-diffusive convection are eliminated. Inertially induced convection mixes the melt and produces a dense slurry. Although channels are eliminated from the bottom mushy region, overall heat transfer and macrosegregation in the cavity are unaffected by the slow rocking. Numerical simulations qualitatively predict trends in the field variables and provide insights on interdendritic flows and macrosegregation (freckle-, A-type segregates), although its quantitative predictions are hampered by simplifying assumptions.

Magirl, C.S.; Incropera, F.P.

1993-01-01

329

Flow and morphological conditions associated with the directional solidification of aqueous ammonium chloride. Annual performance report  

SciTech Connect

Using 27% aq. NH{sub 4}Cl solutions as transparent analog, shadowgraphy and dye injection were used to observe flow and morphology in unidirectional solidification (UDS) from below. Dendritic crystals that form at the cold surface reject lighter, solute-deficient fluid, and instability is shown by finger-type double-diffusive convection. As the mushy two-phase region grows, perturbations at the liquidus interface cause localized remelting and downward development of channels. Solsutal plumes emanate from the channels, and in time, double-diffusive convection layers also form in the melt. When the solution is chilled at the sides as well as at the bottom, conditions are influenced by detachment and settling of crystals from the sidewall and by plumes from slanted channels. When a slow, oscillatory rocking motion is imposed on UDS, the freckle-type segregates in the final cast is suppressed. Within the melt, plumes and double-diffusive convection are eliminated. Inertially induced convection mixes the melt and produces a dense slurry. Although channels are eliminated from the bottom mushy region, overall heat transfer and macrosegregation in the cavity are unaffected by the slow rocking. Numerical simulations qualitatively predict trends in the field variables and provide insights on interdendritic flows and macrosegregation (freckle-, A-type segregates), although its quantitative predictions are hampered by simplifying assumptions.

Magirl, C.S.; Incropera, F.P.

1993-01-01

330

Evaluation of calcium chloride and ammonium thiosulfate as ammonia volatilization inhibitors for surface-applied urea  

E-print Network

(Fenn and Kissel, 1973). Ammonia exiting the soil chainber with the air-flow was captured in a boric acid indicator trap containing 40 mL of boric acid indicator solution. The boric acid indicator traps were changed every 24 h and titrated... of the air-flow through the remaining flasks was increased to 95 to 100% by replacing the concentrated HzSO4 with distilled water. As soon as NHs volatilization resumed, as indicated by the boric acid indicator solution, a soil flask was removed from each...

Sloan, John J.

2012-06-07

331

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

332

Ammonium chloride complex formation during downstream microwave ammonia plasma treatment of parylene-C  

SciTech Connect

In this work, parylene-C is exposed to the effluent from a microwave ammonia plasma with a goal of producing primary amine groups on the parylene-C. These amine groups are desired as sites for the attachment of various biomolecules that will influence the biocompatibility of the parylene-C. Ammonia plasma treatment is an effective approach for creating amine species on polymers. In this work, attenuated total reflectance infrared spectroscopy studies showed that no primary amine groups resulted from this treatment of parylene-C. Instead, reactive nitrogen-bearing radicals from the plasma appear to have been complexed by chlorine in the polymer. The formation of these complexes scavenged nitrogen-bearing radicals from the plasma and prevented the formation of nitrogenous species, such as the desired primary amines, on the parylene-C. These results are consistent with results of ammonia plasma treatment of other chlorinated polymers and suggest that alternative approaches are required to create nitrogen-bearing species on parylene-C.

Pruden, K.G.; Beaudoin, S.P. [Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287-6006 (United States); Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287-6006 and School of Chemical Engineering, Purdue University, Forney Hall of Chemical Engineering, 480 Stadium Mall Drive, West Lafayette, Indiana 47907-2100 (United States)

2005-11-15

333

The Evaluation of Antibacterial Activity of Fabrics Impregnated with Dimethyltetradecyl (3-(Trimethoxysilyl) Propyl) Ammonium Chloride  

Microsoft Academic Search

The antibacterial materials such as fabrics, cloths are became important to avoid cross infection by pathogenic microorganisms, especially bacteria such as Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, to control the infestation by microbes, and to arrest metabolism in microbes in order to reduce the formation odour. Textiles for medical and hygienic use have become important areas in the textile

Kimiran Erdem

334

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

Federal Register 2010, 2011, 2012, 2013

...soil. Therefore, draining and triple rinsing are conducted to reduce DDAC residues on the seed and there is no intended adsorption (binding) of the DDAC to the seed because the registrant is not claiming residual protection of seed from...

2012-08-08

335

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

336

Effect of ammonium thilosulfate and dicyandiamide on residual ammonium in fertilizer bands  

Microsoft Academic Search

Ammonium thiosulfate (ATS, 12–0–0–26S) and dicyandiamide (DCD, 66–0–0) are fertilizer products that also inhibit nitrification. It has also been proposed that ATS can improve the nitrification inhibition properties of DCD. The purpose of this research was to compare the effects of ATS, DCD, and ATS\\/DCD mixtures on the nitrification of banded urea solution or urea?ammonium nitrate (UAN) under laboratory, field

R. J. Goos; B. E. Johnson

1992-01-01

337

Effects of ammonium compounds on the foliar activity of acifluorfen  

E-print Network

and ammonium sulfate increased the activity of dichlorprop on Stellaria m dia (L. ) Vill. (53) Picloram (4-amino-3, 5, 6-trichloro-2-pyridinecarboxylic acid) has also shown a response to inorganic salts. The addition of ammonium sulfate to picloram spray... and ammonium sulfate increased the activity of dichlorprop on Stellaria m dia (L. ) Vill. (53) Picloram (4-amino-3, 5, 6-trichloro-2-pyridinecarboxylic acid) has also shown a response to inorganic salts. The addition of ammonium sulfate to picloram spray...

Schaffers, William Clemens

2012-06-07

338

Molecular Structure of Ferric chloride  

NSDL National Science Digital Library

Ferric chloride is a corrosive chemical, thus, it is used to deodorize sewage and industrial waste by partially reducing to ferrous chloride. It is also employed as an engraving reagent on metal surfaces. Other applications include its use as a flocculating agent in water treatment. Ferric chloride is a hazardous chemical that irritates the skin and eyes and is toxic if ingested, however it can be used as a reagent in pharmaceutical preparations.

2002-08-27

339

Degradation and bound-residue formation of nonylphenol in red soil and the effects of ammonium.  

PubMed

Fate of nonylphenol (NP) in soils and the effects of nitrogen fertilizers are unclear. Using (14)C-tracer, we studied the aerobic and anaerobic degradation of 4-NP111 in a paddy red soil amended without and with ammonium chloride. Under oxic conditions, 4-NP111 had a half-life of 16.1 ± 1.6 days and minor mineralization (3.84 ± 0.02%), forming no extractable metabolite but abundant bound residues (60.9 ± 1.7%, mostly bound to humin) after 49 days of incubation. The ammonium amendment (8 mmol/kg soil) significantly inhibited the degradation (half-life of 68.0 ± 7.7 days), mineralization (2.0 ± 1.1%), and bound-residue formation (23.7 ± 0.2%). Under anoxic conditions, 4-NP111 did not degrade during 49 days of incubation and the ammonium amendment (40 mmol/kg soil) did not affect its persistence. Our results demonstrate that bound-residue formation was a major mechanism for NP dissipation in the red soil under oxic conditions and that chemical nitrogen fertilizer at average field application rate may already considerably increase NP recalcitrance in agricultural soils. PMID:24368312

Liu, Jie; Shan, Jun; Jiang, Bingqi; Wang, Lianhong; Yu, Bin; Chen, Jianqiu; Guo, Hongyan; Ji, Rong

2014-03-01

340

Ammonium inactivation of nitrate reductase in Lemna minor L  

Microsoft Academic Search

The addition of ammonium to nitrate induced plants of Lemna minor L. brings about a rapid loss in extractable nitrate reductase activity. This inactivation is reversible both in vivo and in vitro. Inhibitors of RNA and protein synthesis do not protect nitrate reductase against ammonium inactivation. It is suggested that factors, in addition to ammonium ions, are components of the

T. O. Orebamjo; G. R. Stewart

1975-01-01

341

Removal of ammonium from greywater using natural zeolite  

Microsoft Academic Search

This paper focuses on the effectiveness of removing ammonium ion and the theoretical aspects of adsorption including adsorption isotherm, kinetics and thermodynamics as well as desorption–regeneration studies. Results have demonstrated that natural zeolite shows good performance with up to 97% for ammonium removal depending on contact time, zeolite loading, initial ammonium concentration and pH. The adsorption kinetics is best approximated

Nurul Widiastuti; Hongwei Wu; Ha Ming Ang; Dongke Zhang

2011-01-01

342

Evaporation of Ammonium Nitrate Aerosol in a Heated Nephelometer  

E-print Network

Evaporation of Ammonium Nitrate Aerosol in a Heated Nephelometer: Implications for Field National Laboratory, Upon, New York, 11973-5000 Ammonium nitrate is a semivolatile aerosol component under scattering coefficient of ammonium nitrate aerosol due to evaporation in a heated nephelometer. Changes

343

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

344

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ammonium nitrate-phosphate fertilizers. 148.220...Certain Materials § 148.220 Ammonium nitrate-phosphate fertilizers. (a...containing a maximum of 70 percent of ammonium nitrate and containing a maximum of 0.4...

2011-10-01

345

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ammonium nitrate-phosphate fertilizers. 148.220...Certain Materials § 148.220 Ammonium nitrate-phosphate fertilizers. (a...containing a maximum of 70 percent of ammonium nitrate and containing a maximum of 0.4...

2013-10-01

346

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ammonium nitrate-phosphate fertilizers. 148.220...Certain Materials § 148.220 Ammonium nitrate-phosphate fertilizers. (a...containing a maximum of 70 percent of ammonium nitrate and containing a maximum of 0.4...

2012-10-01

347

Comparing polyaluminum chloride and ferric chloride for antimony removal  

Microsoft Academic Search

Antimony has been one of the contaminants required to be regulated, however, only limited information has been collected to date regarding antimony removal by polyaluminium chloride (PACl) and ferric chloride (FC). Accordingly, the possible use of coagulation by PACl or FC for antimony removal was investigated. Jar tests were used to determine the effects of solution pH, coagulant dosage, and

Meea Kang; Tasuku Kamei; Yasumoto Magara

2003-01-01

348

Ammonium handling by superficial and juxtamedullary nephrons in the rat. Evidence for an ammonia shunt between the loop of Henle and the collecting duct.  

PubMed

Papillary and surface micropuncture was used to assess the effects of a chronic metabolic acidosis on the renal tubular handling of ammonium by surface nephrons, juxtamedullary nephrons, and the terminal segment of collecting duct. Rats chronically fed ammonium chloride had an expected decline in arterial pH and bicarbonate concentration associated with a doubling in the amount of ammonium excreted and a decline in urine pH. The glomerular filtration rate and absolute delivery of water and sodium to micropuncture sites of surface and deep nephrons was not measurably altered. Ammonium delivery to the end of the proximal tubule increased from 853+/-102% to 1,197+/-142% (SE) of the filtered load of ammonium after the induction of metabolic acidosis. This increase was due to a rise in tubular fluid ammonium content from 2.31+/-0.23 to 4.06+/-0.28 mM/liter. After the induction of acidosis, absolute and fractional delivery of ammonium ion to the end of the distal tubule was less than to the end of the accessible portion of the proximal tubule. These findings indicate that ammonium is lost in the intervening segment.Ammonium handling by deep nephrons was profoundly affected by acid loading. Absolute delivery to the bend of the loop of Henle increased twofold while fractional delivery rose from 1,222+/-108% to 1,780+/-132% of the filtered ammonium. This was due to a marked increase in ammonia entry. During acidosis, ammonium delivery to the terminal segment of the collecting duct was doubled (709+/-137% in controls vs. 1,415+/-150% in acidosis, P < 0.005) but did not change between proximal and tip collecting duct sites. In both groups of animals delivery of ammonium to the terminal segment of the collecting duct was greater than to end distal tubular micropuncture sites suggesting that ammonia entry occurred between these two sites. The differences in delivery was greater after the induction of a metabolic acidosis (887+/-140% vs. 384+/-144%, P < 0.05). Thus, the present study indicates that deep nephrons contribute to the adaptive increase in ammonium excretion seen during the induction of metabolic acidosis. The data also suggest that ammonia leaves the nephrons at a site(s) along the loop of Henle to enter the collecting duct and that the induction of a metabolic acidosis enhances this reentry. PMID:7085880

Buerkert, J; Martin, D; Trigg, D

1982-07-01

349

Evaluation of ammonium and soluble salts on grass sod production in compost. I. Addition of ammonium or nitrate salts  

Microsoft Academic Search

Inhibitions in seed germination and in plant growth in some composts have been associated with high concentrations of ammonium or soluble salts in the media. This experiment was conducted to determine changes in ammonium and soluble salts in fertilizer?amended compost with time and their impacts on plant growth. Turfgrass (Lolium perenne L.) was seeded into an ammonium?depleted municipal solid waste

Tara A. OBrien; Allen V. Barker

1996-01-01

350

Dilute Solution Properties of Poly(dimethyldiallylammonium chloride) in Aqueous Sodium Chloride Solutions  

E-print Network

Dilute Solution Properties of Poly(dimethyldiallylammonium chloride) in Aqueous Sodium Chloride fractions in sodium chloride solutions by viscosity, size-exclusionchromatography, and light(dimethyldial1ylammonium chloride) (PDMDAAC)were prepared by preparative size-exclusion chromatography

Dubin, Paul D.

351

Quaternary glacial and climate history of Antarctica lafur Inglfsson  

E-print Network

climate changes. A good un- derstanding of the Late Quaternary glacial and climate history of AntarcticaQuaternary glacial and climate history of Antarctica �lafur Ingólfsson University of Iceland, and is important for understanding the relative timing of climate changes between the polar hemispheres (Denton et

Ingólfsson, �lafur

352

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

353

Oxidation of ammonium sulfite in aqueous solutions using ozone technology  

NASA Astrophysics Data System (ADS)

How to deal with unstable ammonium sulfite, the byproduct of flue gas desulfuration by ammonia absorption methods, has been a difficult problem in recent years. Oxidation of ammonium sulfite in aqueous solutions using ozone produced by a surface discharge system was investigated in the paper. The oxidation efficiency of ammonium sulfite by ozone and traditional air aeration were compared, and the factors including ozone concentration, gas flow rate, initial concentration of ammonium sulfite solution and reaction temperature were discussed. The results show that the oxidation efficiency of ammonium sulfite by ozone technology reached nearly 100% under the optimum conditions, which had a significant increase compared with that by air aeration.

Li, Yue; Shang, Kefeng; Lu, Na; Li, Jie; Wu, Yan

2013-03-01

354

Equation of State of Ammonium Nitrate  

NASA Astrophysics Data System (ADS)

Ammonium nitrate (AN) is a widely used fertilizer and mining explosive. AN is commonly used in ammonium nitrate-fuel oil (ANFO), which is a mixture of explosive-grade AN prills and fuel oil in a 94:6 ratio by weight. ANFO is a non-ideal explosive with measured detonation velocities around 4 km/s. The equation of state properties and known initiation behavior of neat AN are limited. We present the results of a series of gas gun-driven plate impact experiments on pressed neat ammonium nitrate at 1.72 g/cm3. No evidence of initiation was observed under shock loading to 22 GPa. High pressure x-ray diffraction experiments in diamond anvil cells provided insight into the high pressure phase behavior over the same pressure range (to 25 GPa), as well as a static isotherm at ambient temperature. From the isotherm and thermodynamic properties at ambient conditions, a preliminary unreacted equation of state (EOS) has been developed based on the Murnaghan isotherm and Helmholtz formalism [1], which compares favorably with the available experimental Hugoniot data on several densities of AN.

Robbins, David L.; Sheffield, Stephen A.; Dattelbaum, Dana M.; Velisavljevic, Nenad; Stahl, David B.

2009-12-01

355

DETECTION OF THE AMMONIUM ION IN SPACE  

SciTech Connect

We report on the detection of a narrow feature at 262816.73 MHz toward Orion and the cold prestellar core B1-bS which we attribute to the 1{sub 0}-0{sub 0} line of the deuterated ammonium ion, NH{sub 3}D{sup +}. The observations were performed with the IRAM 30 m radio telescope. The carrier has to be a light molecular species as it is the only feature detected over 3.6 GHz of bandwidth. The hyperfine structure is not resolved, indicating a very low value for the electric quadrupolar coupling constant of nitrogen which is expected for NH{sub 3}D{sup +} as the electric field over the N nucleus is practically zero. Moreover, the feature is right at the predicted frequency for the 1{sub 0}-0{sub 0} transition of the ammonium ion, 262817 {+-} 6 MHz (3{sigma}), using rotational constants derived from new infrared data obtained in our laboratory in Madrid. The estimated column density is (1.1 {+-} 0.2) Multiplication-Sign 10{sup 12} cm{sup -2}. Assuming a deuterium enhancement similar to that of NH{sub 2}D, we derive N(NH{sub 4}{sup +}) {approx_equal} 2.6 Multiplication-Sign 10{sup 13} cm{sup -2}, i.e., an abundance for ammonium of a few 10{sup -11}.

Cernicharo, J.; Tercero, B. [Deparment of Astrophysics, CAB, INTA-CSIC, Crta Torrejon-Ajalvir Km 4, E-28850 Torrejon de Ardoz, Madrid (Spain); Fuente, A. [Observatorio Astronomico Nacional, Apdo. 112, E-28803 Alcala de Henares (Spain); Domenech, J. L.; Cueto, M.; Carrasco, E.; Herrero, V. J.; Tanarro, I. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Marcelino, N. [NRAO, 520 Edgemont Road, Charlottesville, VA 22902 (United States); Roueff, E. [Luth, Observatoire de Paris, CNRS UMR8102, Place J. Janssen F-92190 Meudon (France); Gerin, M. [LERMA, Observatoire de Paris, CNRS UMR8112 and Ecole Normale Superieure, 61 Avenue de lObservatoire, F-75014 Paris (France); Pearson, J., E-mail: jcernicharo@cab.inta-csic.es [Jet Propulsion Laboratory, 4800 Oak Grove Drive, MC 168-314, Pasadena, CA 91109 (United States)

2013-07-01

356

Detection of the Ammonium Ion in Space  

NASA Astrophysics Data System (ADS)

We report on the detection of a narrow feature at 262816.73 MHz toward Orion and the cold prestellar core B1-bS which we attribute to the 10-00 line of the deuterated ammonium ion, NH3D+. The observations were performed with the IRAM 30 m radio telescope. The carrier has to be a light molecular species as it is the only feature detected over 3.6 GHz of bandwidth. The hyperfine structure is not resolved, indicating a very low value for the electric quadrupolar coupling constant of nitrogen which is expected for NH3D+ as the electric field over the N nucleus is practically zero. Moreover, the feature is right at the predicted frequency for the 10-00 transition of the ammonium ion, 262817 ± 6 MHz (3?), using rotational constants derived from new infrared data obtained in our laboratory in Madrid. The estimated column density is (1.1 ± 0.2) × 1012 cm-2. Assuming a deuterium enhancement similar to that of NH2D, we derive N(NH_4^+) ~= 2.6 × 1013 cm-2, i.e., an abundance for ammonium of a few 10-11. This work was based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain)

Cernicharo, J.; Tercero, B.; Fuente, A.; Domenech, J. L.; Cueto, M.; Carrasco, E.; Herrero, V. J.; Tanarro, I.; Marcelino, N.; Roueff, E.; Gerin, M.; Pearson, J.

2013-07-01

357

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

358

Characterization of poly(vinyl chloride) aged in a bromine containing electrolyte  

SciTech Connect

Poly(vinyl chloride) (PVC) is being considered for use as a flow frame material in a developmental zinc/bromine battery. The choice of PVC was based on its low cost and the ease with which it can be molded into complex parts. The electrolyte used in this battery is a highly corrosive mixture of bromine, zinc bromide, zinc chloride, potassium bromide, potassium chloride and a quaternary amine salt. The quaternary salt serves to reduce the concentration of free bromine in the electrolyte by virtue of its complexing capability. It is well known that aqueous bromine is capable of oxidizing organic compounds. The purpose of the current study was to investigate the effect of a bromine electrolyte on two PVC formulations, PVC-1 and PVC-4. PVC-1 is the designation given to one of B.F. Goodrich's commercial formulations and is the present baseline material for the flow frame. PVC-4 is an experimental B.F. Goodrich formulation that was developed especially for battery applications. We sought answers to such questions as (1) does oxidation and/or bromination take place. (2) does bromine penetrate into the sample and, if so, how far. (3) how are the mechanical and morphological properties affected. and (4) are there differences in stability between PVC-1 and PVC-4. To accelerate the aging processes we aged the PVC samples at an elevated temperature in an electrolyte which did not contain any complexing agent. 5 refs., 6 figs.

Arnold, C. Jr.; Leo, A.; Tarjani, M.

1988-01-01

359

Acclimation and toxicity of high ammonium concentrations to unicellular algae.  

PubMed

A literature review on the effects of high ammonium concentrations on the growth of 6 classes of microalgae suggests the following rankings. Mean optimal ammonium concentrations were 7600, 2500, 1400, 340, 260, 100 ?M for Chlorophyceae, Cyanophyceae, Prymnesiophyceae, Diatomophyceae, Raphidophyceae, and Dinophyceae respectively and their tolerance to high toxic ammonium levels was 39,000, 13,000, 2300, 3600, 2500, 1200 ?M respectively. Field ammonium concentrations <100 ?M would not likely reduce the growth rate of most microalgae. Chlorophytes were significantly more tolerant to high ammonium than diatoms, prymnesiophytes, dinoflagellates, and raphidophytes. Cyanophytes were significantly more tolerant than dinoflagellates which were the least tolerant. A smaller but more complete data set was used to estimate ammonium EC?? values, and the ranking was: Chlorophyceae>Cyanophyceae, Dinophyceae, Diatomophyceae, and Raphidophyceae. Ammonia toxicity is mainly attributed to NH? at pHs >9 and at pHs <8, toxicity is likely associated with the ammonium ion rather than ammonia. PMID:24533997

Collos, Yves; Harrison, Paul J

2014-03-15

360

Inactivation of the Potassium Conductance and Related Phenomena Caused by Quaternary Ammonium Ion Injection in Squid Axons  

PubMed Central

Several analogues of the tetraethylammonium (TEA+) ion were injected into the giant axon of the squid, and the resultant changes in time course and magnitude of the potassium current (IK) were studied. For all the analogues used, three of the ethyl side chains of TEA+ were left unchanged, while the fourth chain was either lengthened or shortened. Increasing the length of this chain increased binding to the blocking site in the channel by a factor of roughly two for each added CH2 group. The effect on the rate of entry into the blocking site was relatively slight. Thus the concentration for half-suppression of gK decreased by about the same factor of two for each added CH2. All the analogues caused anomalous or ingoing rectification. The longest chain analogue used, pentyltriethylammonium ion, caused rapid inactivation of gK, and this inactivation had properties quite similar to gNa inactivation. The anomalous rectification and the gK inactivation caused by these compounds have the same basic mechanism. PMID:5346528

Armstrong, Clay M.

1969-01-01

361

Synthesis of new, single-isomer quaternary ammonium derivatives of beta-cyclodextrin for electrophoretic enantiomer separations  

E-print Network

of the permanently charged, single-isomer cationic cyclodextrin family, have been synthesized. The purity of process intermediates and final products was determined by HPLC-ELSD and indirect UV-detection capillary electrophoresis. Structural identity was verified...

Nzeadibe, Kingsley C. I.

2007-09-17

362

Modification of a Na-montmorillonite with quaternary ammonium salts and its application for organics removal from TNT red water.  

PubMed

Na-montmorillonite (Na-Mont) and organic montmorillonite modified by cetyltrimethylammonium bromide (CTAB-Mont) and tetramethylammonium bromide (TMAB-Mont) were prepared as adsorbents to remove organic contaminants from 2,4,6-trinitrotoluene (TNT) red water. The characterizations of the samples were performed with X-ray diffraction and Fourier transform infrared spectroscopy. The adsorption capacity of CTAB-Mont (15.9 mg/g) was much larger than Na-Mont (0.26 mg/g) and TMAB-Mont (1.7 mg/g). Langmuir isotherm and the pseudo-second-order kinetic models fitted the experimental results well. The main factor in the adsorption promotion was the distribution phase in the interlayer of CTAB-Mont. The arrangement of molecules analyzed by molecular simulation corresponded to the experimental data and supported the adsorption mechanism. PMID:24804652

Zhang, Qian; Meng, Zilin; Zhang, Yihe; Lv, Guocheng; Lv, Fengzhu; Wu, Limei

2014-01-01

363

Quantitative analysis of a quaternary ammonium drug: ipratropium bromide by LC/ESI-MS(n) in horse plasma and urine.  

PubMed

A quantitative method, using LC/ESI-MS(n) with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MS(n). The efficiency of extraction combined with the sensitivity and the selectivity of MS(n) allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratropium cation in post-administration samples collected from horses treated by nebulization. PMID:21989922

Garcia, P; Paris, A-C; Leufroy, A; Popot, M-A; Bonnaire, Y

2012-04-01

364

Polymer functionalized single-walled carbon nanotube composites and semi-fluorinated quaternary ammonium polymer colloids and coatings  

NASA Astrophysics Data System (ADS)

Scope and Method of Study: Current study focused on understanding of "wetting" and "dewetting" phenomena between surfaces of single-walled carbon nanotubes (SWCNT) which are lightly grafted with polymer chains by reversible-deactivation radical polymerization, when they are mixed with matrix chains of the same architecture as grafts. Effects of grafts to matrix chain lengths on SWCNT dispersion in matrix polymers were studied by measuring electrical conductivity, glass transition temperature, and storage and loss moduli of nanocomposites. Another area of work was to design semi-fluorinated copolymers with core-shell morphology by emulsion polymerization, study their catalytic activities for hydrolyses of Paraoxon, a toxic insecticide, in the forms of both colloidal dispersions and films, and to characterize the surfaces of the films by atomic force microscopy and by dynamic contact angle measurements. Findings and Conclusions: The glass transition temperature ( Tg) of polystyrene (PS) filled with SWCNT grafted with PS of different lengths increased from 99 to 109 °C at 6 wt% of SWCNT followed by a plateau. The heat capacity (DeltaCp ) at Tg continued to decrease only for the smallest chain length grafted PS nanocomposites. SWCNT/PS nanocomposites had low electrical conductivity and showed no percolation threshold due to the thick polymer coatings. A key finding was that the SWCNT surface can accommodate only a fixed numbers of styrene units. Similar results on change in Tg were obtained for SWCNT/PMMA nanocomposites when molecular weight of matrix (Mmatrix) ? molecular weight of grafts (Mgraft). No change in DeltaCp was observed for SWCNT/PMMA nanocomposites. "Wetting" to "dewetting" occurred Mmatrix/ Mgraft ? 1. For Mmatrix > Mgraft, electrical conductivity of nanocomposites reached the value of 10-9 S cm-1 at 1.0 wt% nanotube loading and had percolation threshold of electrical conductivity at ˜0.25 wt% SWCNT. Raman and UV-vis-NIR data confirmed that grafting methods have little effect on inherent electronic properties of SWCNT. A key observation was that the behavior of polymer-SWCNT composites is analogous to polymer thin films containing two different lengths of chemically same polymers. On the other hand, semifluorinated copolymers had hydrophobic and lipophilic properties similar to homopolymers of poly(perfluoroalkyl methacrylates), but were not active in detoxification of Paraoxon. Therefore, semi-fluorinated latexes can either act as phase transfer catalysts for hydrolysis of organophosporous compounds or repel the compound, but cannot do both.

Paul, Abhijit

365

Adsorption of chromium (VI) ion from aqueous solution by succinylated mercerized cellulose functionalized with quaternary ammonium groups.  

PubMed

Succinylated mercerized cellulose (cell 1) was used to synthesize an anion exchange resin. Cell 1, containing carboxylic acid groups was reacted with triethylenetetramine to introduce amine functionality to this material to obtain cell 2. Cell 2 was reacted with methyl-iodide to quaternize the amine groups from this material to obtain cell 3. Cells 2 and 3 were characterized by mass percent gain, degree of amination and quaternization, FTIR and CHN. Cells 2 and 3 showed degrees of amination and quaternization of 2.8 and 0.9 mmol/g and nitrogen content of 6.07% and 2.13%, respectively. Cell 3 was used for Cr (VI) adsorption studies. Adsorption equilibrium time and optimum pH for Cr (VI) adsorption were found to be 300 min and 3.1, respectively. The Langmuir isotherm was used to model adsorption equilibrium data. The adsorption capacity of cell 3 was found to be 0.829 mmol/g. Kinetic studies showed that the rate of adsorption of Cr (VI) on cell 3 obeyed a pseudo-second-order kinetic model. PMID:19297152

Gurgel, Leandro Vinícius Alves; Perin de Melo, Júlio César; de Lena, Jorge Carvalho; Gil, Laurent Frédéric

2009-07-01

366

Effects of structure dissymmetry on aggregation behaviors of quaternary ammonium Gemini surfactants in a protic ionic liquid EAN.  

PubMed

The aggregation behaviors of a series of dissymmetric cationic Gemini surfactants, [C(m)H(2m+1)(CH(3))(2)N(CH(2))(2)N(CH(3))(2)C(n)H(2n+1)]Br(2), designated as m-2-n (with a fixed m + n = 24, m = 16, 14, 12) have been investigated in a protic ionic liquid, ethylammonium nitrate (EAN). Surface tension, polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheological measurements are adopted to investigate the micellization and lyotropic liquid crystal (LLC) formation. The obtained results indicate that the structure dissymmetry plays an important role in aggregation process of m-2-n. With increasing degree of dissymmetry, the critical micellization concentration, the maximum reduction of solvent surface tension, and the minimum area occupied per surfactant molecule at the air/EAN interface all become smaller. The thermostability of formed LLCs is therefore improved because of the more compact molecules. These characteristics can be explained by the enhancement of solvophobic effect due to the increased structure dissymmetry of Gemini surfactants. PMID:23140416

Wang, Xudong; Li, Qintang; Chen, Xiao; Li, Zhihong

2012-12-01

367

The role of Quaternary environmental change in plant macroevolution: the exception or the rule?  

Microsoft Academic Search

The Quaternary has been described as an important time for genetic diversification and speciation. This is based on the premise that Quaternary climatic conditions fostered the isolation of populations and, in some instances, allopatric speciation. However, the 'Quaternary Ice-Age speciation model' rests on two key assumptions: (i) that biotic responses to climate change during the Quaternary were significantly different from

Katherine J. Willis; Karl J. Niklas

2004-01-01

368

Late Quaternary temperature change velocity in Mesoamerica  

NASA Astrophysics Data System (ADS)

Quaternary climate has been highly variable, and yet few quantitative continental reconstructions are available for tropical areas. Quantitative records of temperature change during the Quaternary are especially relevant for putting modern climate change into a historic context. Within this perspective, two aspects are of singular relevance: i) Identifying and quantifying past climatic variability, and ii) Providing a means to estimate the seed at which climate change happened in the past. Here we show temperature reconstructions and temperature change velocity calculations for two locations in northern tropical America. Temperature reconstruction was based on two sedimentary records form Lake Chalco (30,000 years), central Mexican highlands, and Lake Petén-Itzá, Guatemalan lowlands (86,000 years). Temperature reconstruction was based on the analysis of fossil pollen on the light of pollen-temperature transfer functions. These functions were calibrated through an extensive survey of modern pollen samples covering an elevational gradient from 0 to 4,218 m asl. Derived temperature profiles show a parallel long-term trend and a similar cooling of approximately 5 oC during the Last Glacial Maximum in the lowlands and highlands of Mexico and Guatemala. Using a digital elevation model, we ere able to reconstruct the velocity at which isotherms displaced to produce the observed temperature anomalies. Spatial velocities of temperature change in the studied areas were at least four times slower than values reported for the last 50 years, but also at least twice as fast as those obtained from recent models. This study demonstrates that modern temperature change has no precedent within the last 86,000 years, but also that tropical climate has been more variable than it has been assumed to date.

Correa-Metrio, A.; Lozano, S.; Sosa-Nájera, S.; Bush, M. B.

2013-05-01

369

A quaternary temperament model and defense cluster preferences.  

PubMed

A quaternary model of temperament constructed from orthogonal axes defined by Extraversion-Introversion and Thinking-Feeling resulted in four groups: Introverted Thinking, Introverted Feeling, Extraverted Thinking, and Extraverted Feeling. Hypothesized relationships between quaternary groups and defense cluster preferences were tested by giving 158 female college students the Myers-Briggs Type Indicator and the Defense Mechanisms Inventory. There was little support for hypothesized relationships between the quaternary model and defense preferences. The only hypothesized significant group difference showed the Extraverted Feeling group recording a greater preference for the Reversal defense cluster than the Introverted Feeling group. PMID:14650666

Kelly, Kathryn E; Tobacyk, Jerome J

2003-10-01

370

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

371

Interaction of heavy metal ions with ammonium humates  

SciTech Connect

Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.

Budaeva, A.D.; Zoltoev, E.V.; Tikhova, V.D.; Bodoev, N.V. [Russian Academy for Science, Buryatiya (Russian Federation)

2006-06-15

372

Anaerobic ammonium oxidation discovered in a denitrifying fluidized bed reactor  

Microsoft Academic Search

Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH4+ was disappearing from a denitrifying fluidized bed reactor treating effluent from a methanogenic reactor. Both nitrate and ammonium consumption increased with concomitant gas production. A maximum ammonium removal rate of 0.4 kg N · m?3 · d?1 (1.2 mM\\/h) was observed.

A. Mulder; A. A. van de Graaf; L. A. Robertson; J. G. Kuenen

1995-01-01

373

Ammonium bisulfate/water: a pseudobinary system.  

PubMed

We have studied the ammonium bisulfate/water system using thermal analysis (differential scanning calorimetry) and infrared spectroscopy of thin films. Our results for the melting points for ice and letovicite are in good agreement with other experimental work. However, we report here the first measurements of the ice/ammonium bisulfate/letovicite invariant point. We have used our observations and solubility data to construct a complete phase diagram for this system. Utilizing phase diagram theory and the Gibbs phase rule, we conclude that this system is not a true binary system but rather a pseudobinary system, which has a range of concentrations that cannot be represented by a simple binary phase diagram and thus must be viewed as part of the ternary system: H(2)SO(4)/(NH(4))(2)SO(4)/H(2)O. We also compared our results to the phase diagram predictions of the aerosol inorganics model and found the predicted melting points are in good agreement with experimental work over a limited concentration range, but the transitions predicted by the model at lower temperatures are not in agreement with experimental results. PMID:16737260

Beyer, Keith D; Bothe, Jameson

2006-06-01

374

Ammonium removal from sanitary landfill leachate using natural Gördes clinoptilolite.  

PubMed

Removal of ammonium ion (NH(4)(+)) from leachate from Odayeri sanitary landfill, located in the European part of Istanbul, was examined using Gördes (Turkish) clinoptilolite. The effects of pH, flow rate, ammonium concentration and competitive cations on the removal efficiency were investigated in both batch and column studies. Thomas model were used to analyze the breakthrough data. Nonlinear least square method was applied for fitting the column data. The competitive effect was observed more effective in lower ammonium concentration and higher cation concentrations. Conditioning and regeneration using NaCl improved removal efficiency of ammonium from leachate. PMID:17868987

Karadag, Dogan; Tok, Sema; Akgul, Eda; Turan, Mustafa; Ozturk, Mustafa; Demir, Ahmet

2008-05-01

375

Enhanced ammonia nitrogen removal using consistent ammonium exchange of modified zeolite and biological regeneration in a sequencing batch reactor process.  

PubMed

Utilizing preferential ion exchange of the modified zeolite, the zeo-sequencing batch reactor (SBR) is recommended for a new nitrogen removal process. In this study, natural zeolite was modified by sodium chloride to enhance sorption capacity for ammoniacal nitrogen. The untreated and treated zeolite was characterized by XPS and XRD techniques. The sorption isotherm tests showed that equilibrium sorption data were better represented by the Langmuir model than by the Freundlich model. Treatment of natural zeolite by sodium chloride increased the sorption capacity for ammoniacal nitrogen removal from aqueous solutions. As a result of the continuous bioregeneration of ammonium saturated zeolite-floc in the SBR, the nitrogen removal efficiency of the zeo-SBR was relatively ideal. Scanning electron microscopy results showed that microbes were abundant in the zeo-SBR process. PMID:21970175

Wei, Yun Xia; Ye, Zheng Fang; Wang, Yao Long; Ma, Ming Guang; Li, Yan Feng

2011-01-01

376

The newsletter of the CAMBRIDGE QUATERNARY ISSUE 36 LENT 2007  

E-print Network

entitled `The History of Quaternary Glaciations'. The work is also available online via ScienceDirect. #12 enjoys sport, especially floorball (which is played in Cambridge!) and ice hockey. Seminar Dates QDG

de Gispert, Adrià

377

Quaternary extension in southern Tibet: Field observations and tectonic implications  

Microsoft Academic Search

We summarize evidence for Quaternary and active faulting collected in the field during three Sino-French expeditions to southeastern Tibet (1980-1982). Detailed mapping of Quaternary and active faults as well as microtectonic measurements indicate that normal faulting has been the dominant tectonic regime north of the Himalayas in the last 2+\\/-0.5 m.y. The maximum horizontal principal stress in south Tibet appears

Rolando Armijo; Paul Tapponnier; J. L. Mercier; Han Tong-Lin

1986-01-01

378

The tempo of avian diversification during the Quaternary  

Microsoft Academic Search

It is generally assumed that the Quaternary was a period of heightened diversification in temperate ver- tebrate organisms. Previous molecular systematics studies have challenged this assertion. We re-examined this issue in north temperate birds using log-lineage plots and distributions of sister-taxon distances. Log- lineage plots support earlier conclusions that avian diversification slowed during the Quaternary. To test plots of empirical

Robert M. Zink; John Klicka; Brian R. Barber

2004-01-01

379

Late Quaternary geotechnical stratigraphy of North Texas continental shelf  

E-print Network

LATE QUATERNARY GEOTECHNICAL STRATIGRAPHY OF NORTH TEXAS CONTINENTAL SHELF A Thesis by JOHN SAL MUNSEY Submitted to the Graduate College of Texas Algi University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... December 1985 Major Subject: Geology LATE QUATERNARY GEOTECHNICAL STRATIGRAPHY OF NORTH TEXAS CONTINENTAL SHELF A Thesis by JOHN SAL MUNSEY Approved as to style and content by: br' sto er . Mathewson (Cha&r of Committee) Norman R . ' ord (Memb...

Munsey, John Sal

2012-06-07

380

A Quaternary Geomagnetic Instability Time Scale  

NASA Astrophysics Data System (ADS)

Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought. Rather, during the Quaternary period, they occur nearly three times as often as full polarity reversals. I will address analytical issues, including the size and consistency of system blanks, that have led to the recognition of minor (1%) discrepencies between the 40Ar/39Ar age for a particular reversal or excursion and the best astrochronologic estimates from ODP sediment cores. For example, re-analysis of lava flows from Haleakala volcano, Maui that record in detail the Matuyama-Brunhes polarity reversal have been undertaken with blanks an order of magntitude smaller and more stable than was common a decade ago. Using the modern astrochronologic calibration of 28.201 Ma for the age of the Fish Canyon sanidine standard, results thus far yield an 40Ar/39Ar age of 772 × 11 ka for the reversal that is identical to the most precise and accurate astrochronologic age of 773 × 2 ka for this reversal from ODP cores. Similarly, new dating of sanidine in the Cerro Santa Rosa I rhyolite dome, New Mexico reveals an age of 932 × 5 ka for the excursion it records, in perfect agreement with astrochronologically dated ODP core records. Work underway aims at refining the 40Ar/39Ar ages that underpin the entire GITS by further eliminating the bias between the radioisotopic and astrochronologically determined ages for several reversals and excursions.

Singer, B. S.

2013-12-01

381

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed Central

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

1986-01-01

382

CHLORIDE WASHER PERFORMACE TESTING  

SciTech Connect

Testing was performed to determine the chloride (Cl-) removal capabilities of the Savannah River National Laboratory (SRNL) designed and built Cl- washing equipment intended for HB-Line installation. The equipment to be deployed was tested using a cerium oxide (CeO2) based simulant in place of the 3013 plutonium oxide (PuO2) material. Two different simulant mixtures were included in this testing -- one having higher Cl- content than the other. The higher Cl- simulant was based on K-Area Interim Surveillance Inspection Program (KIS) material with Cl- content approximately equal to 70,000 ppm. The lower Cl- level simulant was comparable to KIS material containing approximately 8,000-ppm Cl- content. The performance testing results indicate that the washer is capable of reducing the Cl- content of both surrogates to below 200 ppm with three 1/2-liter washes of 0.1M sodium hydroxide (NaOH) solution. Larger wash volumes were used with similar results - all of the prescribed test parameters consistently reduced the Cl- content of the surrogate to a value below 200 ppm Cl- in the final washed surrogate material. The washer uses a 20-micron filter to retain the surrogate solids. Tests showed that 0.16-0.41% of the insoluble fraction of the starting mass passed through the 20-micron filter. The solids retention performance indicates that the fissile masses passing through the 20-micron filter should not exceed the waste acceptance criteria for discard in grout to TRU waste. It is recommended that additional testing be pursued for further verification and optimization purposes. It is likely that wash volumes smaller than those tested could still reduce the Cl- values to acceptable levels. Along with reduced wash volumes, reuse of the third wash volume (in the next run processed) should be tested as a wash solution minimization plan. A 67% reduction in the number of grouted paint pails could be realized if wash solution minimization testing returned acceptable results.

Coughlin, J; David Best, D; Robert Pierce, R

2007-11-30

383

The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some ammonium salts  

Microsoft Academic Search

Vapour pressures of water over saturated solutions of ammonium bromide, ammonium dihydrogen phosphate, ammonium thiosulfate, ammonium persulfate, ammonium acetate, ammonium oxalate and ammonium tartrate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. Molar enthalpies of solution of ammonium bromide ?solHm(NH4Br, T=293.97K, m=0.1030mol·kg?1)=(17.4±0.5)kJ·mol?1; ammonium hydrogen

Alexander Apelblat; Eli Korin

2003-01-01

384

Phase transfer catalysis: Kinetics and mechanism of hydroxide ion initiated dichlorocarbene addition to styrene catalysed by triethylbenzylammonium chloride  

Microsoft Academic Search

The kinetics of dichlorocarbene addition to styrene was studied under phase-transfer catalytic conditions using aqueous sodium\\u000a hydroxide as the base and triethylbenzyl ammonium chloride as the phase-transfer catalyst. The reaction was carried out at\\u000a 40°C under pseudo first-order condition by keeping aqueous sodium hydroxide and chloroform in excess. The fiogress of the\\u000a reaction was monitored by gas chromatography. The effects

T Balakrishnan; T K Shabeer; K Nellie

1991-01-01

385

Solubilities in the ammonium thiosulfate-urea-ammonium nitrate-water system at 0°C  

Microsoft Academic Search

Solubilities in the system CO(NH2)2-NH4NO3-(NH4)2S2O3-H2O were obtained at 0°C and pH values between 6.12 and 7.33. The new composition of matter, (NH4)6(S2O3)2(NO3)2·CO(NH2)2, was identified and characterized chemically and microscopically. Stable high-analyses solution fertilizers can be produced at 0°C utilizing waste ammonium thiosulfate solutions with standard ammonium nitrate and urea fertilizer materials. A 31-0-0-5.6S grade (%N-%P2O5-%K2O-Other) fertilizer solution can be formed

A. W. Frazier; Y. K. Kim; C. L. Griffin

1990-01-01

386

AMMONIUM SULFATE AND BISULFATE FORMATION IN AIR PREHEATERS  

EPA Science Inventory

The overall goal of this study was to investigate the problems which result from deposition of ammonium sulfates in an air preheater. More specifically, the study had three major objectives. The first was to determine the conditions under which ammonium sulfates are expected to f...

387

Anaerobic ammonium oxidation by anammox bacteria in the Black Sea  

Microsoft Academic Search

The availability of fixed inorganic nitrogen (nitrate, nitrite and ammonium) limits primary productivity in many oceanic regions. The conversion of nitrate to N2 by heterotrophic bacteria (denitrification) is believed to be the only important sink for fixed inorganic nitrogen in the ocean. Here we provide evidence for bacteria that anaerobically oxidize ammonium with nitrite to N2 in the world's largest

Marcel M. M. Kuypers; A. Olav Sliekers; Gaute Lavik; Markus Schmid; Bo Barker Jørgensen; J. Gijs Kuenen; Jaap S. Sinninghe Damsté; Marc Strous; Mike S. M. Jetten

2003-01-01

388

Ammonium determination in soil extracts by the salicylate method  

Microsoft Academic Search

An ammonium determination, based on formation of a substituted indophenol with sodiumsalicylate as phenolic reagent, has been reexamined. An increase of 70% in absorbancy compared with existing salicylate methods in soil science, and an increase in reproducibility compared with pre?existing equivalent methods in other disciplines were obtained. The method can be applied satisfactorily for ammonium in 2M KCl soil extracts

A. J. Kempers; A. Zweers

1986-01-01

389

Ammonium assimilation in Proteus vulgaris, Bacillus pasteurii , and Sporosarcina ureae  

Microsoft Academic Search

No active uptake of ammonium was detected in Proteus vulgaris, Bacillus pasteurii, and Sporosarcina ureae, which indicates that these bacteria depend on the passive diffusion of ammonia across the cell membrane. In P. vulgaris the glutamine synthetase-glutamate synthase (GS-GOGAT) pathway and glutamate dehydrogenase (GDH) were present, and these enzymes exhibited high affinities for ammonium. In B. pasteurii and S. ureae,

Gerhard Miirsdorf; Heinrich Kaltwasser

1989-01-01

390

Response of anaerobic ammonium-oxidizing bacteria to hydroxylamine  

Microsoft Academic Search

Anaerobic ammonium oxidation is a recent addition to the microbial nitrogen cycle, and its metabolic pathway, including the production and conversion of its intermediate hydrazine, is not well understood. Therefore, the effect of hydroxylamine addition on the hydrazine metabolism of anaerobic ammonium-oxidizing (anammox) bacteria was studied both experimentally and by mathematical modeling. It was observed that hydroxylamine was disproportionated biologically

Maarten J. Van De Graaf; Boran Kartal; Cristian Picioreanu; Mike S. M. Jetten

2008-01-01

391

Microbial ammonium cycling in the Mississippi River plume during  

E-print Network

Microbial ammonium cycling in the Mississippi River plume during the drought spring of 2000 FRANK J of ammonium (NH4 + ) were studied along a salinity gradient (salinities 0.2­34.4) in the Mississippi River of Mexico are influenced by riverine freshwater inputs from the Mississippi River, which introduces

Jochem, Frank J.

392

Water quality of the Quaternary and Ada-Vamoosa aquifers on the Osage Reservation, Osage County, Oklahoma, 1997  

USGS Publications Warehouse

The project was to provide information on the quality of ground water from rural-domestic-water wells within the Osage Reservation and compare the water-quality to proximity to oil wells. About 38,500 oil wells have been drilled in the Reservation since drilling began in 1896. About 1,480 square miles or 64 percent of the Reservation is within a quarter mile of an oil well. The unconfined Quaternary sand aquifer covers about 315 square miles or about 14 percent of the Reservation and the confined Ada-Vamoosa sandstone aquifer covers about 800 square miles or about 35 percent of the Reservation. Fifty-eight percent of the Quaternary aquifer and 69 percent of the outcrop area of the Ada-Vamoosa aquifer are within a quarter mile of an oil well . One hundred twenty domestic ground-water wells were sampled from the Quaternary and Ada-Vamoosa aquifers. Forty-nine percent of the Reservation is underlain by the aquifers. Ground-water quality is good on most of the Reservation, but the use of domestic water-supply wells tend to minimize water-quality problems. Existing water-supply wells commonly are located in areas that produce usable volumes of potable water. Several constituents in samples from the Ada-Vamoosa-aquifer within a quarter mile of an oil well were significantly greater than from the aquifer not near oil wells. The constituents include specific conductance, dissolved solids, sodium, sulfate, chloride, bromide, and silica. These ions are probably derived from brine water. In the Ada-Vamoosa aquifer subgroups, 57 percent of the samples near oil wells and 24 percent of the samples not near oil wells had dissolved-solids concentrations greater than 500 milligrams per liter. The water quality in the Quaternary and Ada-Vamoosa aquifers is similar in areas where no oil wells have been drilled but is significantly different for several constituents. Median concentrations of major constituents from the Ada-Vamoosa aquifer not near oil wells were less than or equal to values from the Quaternary aquifer. Sixty-four percent of the water-quality samples from the Quaternary and 51 percent from the Ada-Vamoosa aquifers have dissolved-solids concentrations less than the secondary drinking water regulations of 500 milligrams per liter. Fifty-nine percent of the aquifer samples in the Quaternary aquifer subgroups not near oil wells and 70 percent of the samples near oil wells had dissolved solids less than 500 milligrams per liter. Areas in the Ada-Vamoosa aquifer near Hominy, Pershing, and Hula Lake have dissolved-solids concentrations greater than the secondary drinking water regulations. Water-quality samples from the Quaternary aquifer in these areas also have dissolved-solids concentrations greater than 500 milligrams per liter.

Abbott, Marvin M.

2000-01-01

393

Hybrid organic-inorganic crystals based on ammonium dihydrogen phosphate and ammonium salicylate  

NASA Astrophysics Data System (ADS)

ADP-NH 4Sal hybrid crystals are grown from aqueous solutions. The influence of the acidity of the mixed solution on the conditions of co-crystallization of the components is studied. The spectral and scintillation characteristics are determined. Co-crystallization of ammonium salicylate (NH 4Sal) and ammonium dihydrogen phosphate (ADP, NH 4H 2PO 4) is shown to be feasible, the structure of the doping addition being defined by the solution ??. In basic and weak acidic media the hybrid crystals ADP:NH 4Sal are formed in which salicylate anions are located in the interplanar space between the {110}-type planes in the lattice of ADP. The luminescence spectra contain an emission band maximum with ? max=360 nm. In acidic solutions there are ADP:HSal crystals in which salicylic acid molecules captured by the growth macrosteps are located in the interplanar space of the prismatic {100} and pyramidal {101} growth sectors. The luminescence band undergoes bathochromic shift to ?max=400 nm. The sensitivity of ADP:NH 4Sal scintillation crystals to fast neutrons depends on the concentration of ammonium salicylate in ADP matrix. The highest neutron sensitivity is characteristic of the co-doped ADP:NH 4Sal/Tl scintillation crystals.

Voronov, A. P.; Salo, V. I.; Puzikov, V. M.; Babenko, G. N.; Roshal, A. D.; Tkachenko, V. F.

2011-11-01

394

Determination of thallium in potassium chloride and electrolyte replenishers by electrothermal atomic absorption spectrometry.  

PubMed

Thallium in potassium chloride and electrolyte replenishers was determined by electrothermal atomic absorption spectrometry (ETAAS) with direct injection of a resin suspension. Thallium(III) was extracted on fine particles of a cellulose nitrate resin (CNR) from dilute HCl (pH 1.6) in the presence of ammonium pyrrolidine-1-carbodithioate. The CNR particles were collected on a membrane filter by filtration under suction, suspended in 1.0 mL 10mM HNO3, and then delivered directly to ETAAS as the suspension. The effects of chloride ions were thoroughly investigated. The results showed that the addition of 0.5mM NaCl to the suspension (10mM HNO3) was recommended, after CNR and a membrane filter holding the CNR were washed thoroughly with 0.025M HCl, to eliminate interference from chloride ions. No chemical modifier was required. Extraction from the solution containing up to 2M chloride ion was allowable. The proposed method gave a concentration factor of 50 for a 50 mL sample volume. The detection limit (3sigma, n = 5) was 1 ng (20 pg/mL). The relative standard deviation was 4.9% (n = 5) at 30 ng level of thallium. The content of thallium in potassium chloride was 15.7-32.8 ng/g, and in electrolyte replenishers was 0.18-4.16 ng/mL. PMID:15295894

Nukatsuka, Isoshi; Horiguchi, Ryo; Seitoh, Hiroyuki; Ohzeki, Kunio; Miyashita, Fumihide

2004-01-01

395

Hydrophobic, ductile, and transparent nanocellulose films with quaternary alkylammonium carboxylates on nanofibril surfaces.  

PubMed

Hydrophobic, ductile, and transparent nanocellulose films were prepared by casting and drying aqueous dispersions of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibrils (TOCNs) with quaternary alkylammoniums (QAs) as counterions for the surface carboxylate groups. TOCN films with tetramethylammonium and tetraethylammonium carboxylates showed high optical transparencies, strain-to-failure values (14-22%), and work-of-fracture values (20-27 MJ m(-3)). The ductility of these films was likely caused by the alkyl chains of the QA groups densely covering the TOCN surfaces and being present at the interfaces between the TOCN elements in the films. The water contact angle of the TOCN-QA films increased to ?100° by introducing tetra(n-butyl)ammonium groups as counterions. Thus, TOCN film properties can be controlled by changing the chemical structure of the counterions from Na to QAs. The hydrophilic TOCN surfaces can be changed to hydrophobic simply and efficiently by the conversion from TOCN-Na to TOCN-QA, when TOCNs are used as nanofillers in hydrophobic polymer matrices. PMID:25310181

Shimizu, Michiko; Saito, Tsuguyuki; Fukuzumi, Hayaka; Isogai, Akira

2014-11-10

396

Evidence for intestinal chloride secretion.  

PubMed

Intestinal fluid secretion is pivotal in the creation of an ideal environment for effective enzymatic digestion, nutrient absorption and stool movement. Since fluid cannot be actively secreted into the gut, this process is dependent on an osmotic gradient, which is mainly created by chloride transport by the enterocyte. A pathological dysbalance between fluid secretion and absorption leads to obstruction or potentially fatal diarrhoea. This article reviews the widely accepted model of intestinal chloride secretion with an emphasis on the molecular players involved in this tightly regulated process. PMID:20233891

Murek, Michael; Kopic, Sascha; Geibel, John

2010-04-01

397

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2011 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The provisions...

2011-07-01

398

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The provisions...

2013-07-01

399

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2012 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The provisions...

2012-07-01

400

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The provisions...

2010-07-01

401

78 FR 35258 - Solid Agricultural Grade Ammonium Nitrate from Ukraine: Continuation of Antidumping Duty Order  

Federal Register 2010, 2011, 2012, 2013

...A-823-810] Solid Agricultural Grade Ammonium Nitrate from Ukraine: Continuation of Antidumping...on solid agricultural grade ammonium nitrate from Ukraine would likely lead to continuation...Order: Solid Agricultural Grade Ammonium Nitrate from Ukraine, 66 FR 47451...

2013-06-12

402

Polygenetic Quaternary volcanism at Crater Flat, Nevada  

NASA Astrophysics Data System (ADS)

Alkali basalts erupted during the Quaternary at Crater Flat, Nevada, record a complex history of polycyclic and polygenetic volcanism. Magmas from the two main centers (Black Cone and Red Cone) are petrographically and geochemically similar, although field evidence suggests a number of separate eruptive events. High incompatible element concentrations, low Nb/La and high Zr/Y indicate that the magmas were derived by small degrees of partial melting from the lithospheric mantle. At Red Cone, a significant range of Sr, La, Ce, Ba and Th concentrations is observed with time (e.g., Sr range 1308-1848 ppm): the youngest samples having the more elevated values. However, there is only limited variation in the compatible trace elements (e.g., Sc and Ni). The array of compositions at Red Cone could not have been produced by changes in the degree of partial melting, or by fractional crystallization. Rather, a model of magma mixing is proposed between relatively enriched and depleted end-members. The cluster of Black Cone data falls consistently at the least-enriched end of the Red Cone sample arrays, suggesting that the Black Cone magma represents one of the mixing end-members. The modeling indicates that the magmatic plumbing systems of the two centers were linked, at least during the early stages of volcanism. Moreover, volcanic activity may have occurred at a number of sites along the length of the magmatic feeder zone during a single eruptive phase. This could have significant implications for volcanic hazard assessment in the region around Yucca Mountain, and the proposed nuclear waste repository.

Bradshaw, T. K.; Smith, Eugene I.

1994-11-01

403

Receptor model source attributions for Utah?s Salt Lake City airshed and the impacts of wintertime secondary ammonium nitrate and ammonium chloride aerosol.  

EPA Science Inventory

Communities along Utah?s Wasatch Front are currently developing strategies to reduce daily average PM2.5 levels to below National Ambient Air Quality Standards during wintertime, persistent, multi-day stable atmospheric conditions or cold-air pools. Speciated PM2.5 data from the ...

404

Population of Nitrifying Bacteria and Nitrification in Ammonium Saturated Clinoptilolite  

NASA Technical Reports Server (NTRS)

As humans begin to spend longer periods of time in space, plants will be incorporated into life support systems. Ammonium saturated clinoptilolite is one plant growth substrate but a balance between ammonium and nitrate is needed. A laboratory study was conducted to determine effects of nitrifying bacteria on ammonium concentrations and kinetics of nitrification. Columns containing clinoptilolite substrate amended with nitrifying bacteria obtained from soil enrichment were analyzed weekly for a 90 day period. The enrichment culture initially contained 1 x 10(exp 5) ammonium oxidizing bacteria and 1 x 10(exp 2) nitrite oxidizing bacteria per gram of substrate. Populations of ammonium oxidizing bacteria increased to 1 x 10(exp 6) and nitrite oxidizing bacteria increased to 1 x 10(exp 3) per gram of substrate. The nitrification rate was approximately 0.25mg NO3(-)-N/kg.hr. Experiments were also conducted to enumerate nitrifying bacteria in a clinoptilolite substrate used to grow wheat (Triticum aestivum L.). Seventy days following the initial inoculation with an unknown number of commercial nitrifying bacteria, 1 x 10(exp 5) ammonium oxidizing bacteria per gram of substrate were present. The number of nitrite oxidizing bacteria was between 1 x 10(exp 3) to 10(exp 4) per gram of substrate as measured by the most probable number method. Nitrification rates were approximately 0.20mg NO3(-)-N/kg.hr. Clinoptilolite readily exchanged sufficient concentrations of ammonium to support nitrifying bacteria and they survived well in this medium.

McGilloway, R. L.; Weaver, R. W.; Ming, Douglas W.; Gruener, J.

1999-01-01

405

Chloride thresholds in marine concrete  

Microsoft Academic Search

This paper reports results from an ongoing study of the performance of fly ash concrete in marine exposure. Reinforced concrete specimens exposed to tidal conditions were retrieved at ages ranging from 1 to 4 years. Steel reinforcement mass losses are compared with chloride contents at the location of the bar for concrete specimens of various strength grades and with a

Michael Thomas

1996-01-01

406

29 CFR 1910.1017 - Vinyl chloride.  

Code of Federal Regulations, 2012 CFR

...following hazards are to be addressed: Cancer; central nervous system effects; liver... DANGER VINYL CHLORIDE MAY CAUSE CANCER AUTHORIZED PERSONNEL ONLY (ii... DANGER VINYL CHLORIDE MAY CAUSE CANCER WEAR RESPIRATORY PROTECTION AND...

2012-07-01

407

29 CFR 1910.1017 - Vinyl chloride.  

...following hazards are to be addressed: Cancer; central nervous system effects; liver... DANGER VINYL CHLORIDE MAY CAUSE CANCER AUTHORIZED PERSONNEL ONLY (ii... DANGER VINYL CHLORIDE MAY CAUSE CANCER WEAR RESPIRATORY PROTECTION AND...

2014-07-01

408

29 CFR 1910.1017 - Vinyl chloride.  

Code of Federal Regulations, 2013 CFR

...following hazards are to be addressed: Cancer; central nervous system effects; liver... DANGER VINYL CHLORIDE MAY CAUSE CANCER AUTHORIZED PERSONNEL ONLY (ii... DANGER VINYL CHLORIDE MAY CAUSE CANCER WEAR RESPIRATORY PROTECTION AND...

2013-07-01

409

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2013 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2013-04-01

410

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2012 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2012-04-01

411

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2011 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2011-04-01

412

Microbial reductive dehalogenation of vinyl chloride  

DOEpatents

Compositions and methods are provided that relate to the bioremediation of chlorinated ethenes, particularly the bioremediation of vinyl chloride by Dehalococcoides-like organisms. An isolated strain of bacteria, Dehalococcoides sp. strain VS, that metabolizes vinyl chloride is provided; the genetic sequence of the enzyme responsible for vinyl chloride dehalogenation; methods of assessing the capability of endogenous organisms at an environmental site to metabolize vinyl chloride; and a method of using the strains of the invention for bioremediation.

Spormann, Alfred M. (Stanford, CA); Muller, Jochen A. (Baltimore, MD); Rosner, Bettina M. (Berlin, DE); Von Abendroth, Gregory (Nannhein, DE); Meshulam-Simon, Galit (Los Altos, CA); McCarty, Perry L (Stanford, CA)

2011-11-22

413

Carbohydrate Binding, Quaternary Structure and a Novel Hydrophobic Binding Site in Two Legume  

E-print Network

Carbohydrate Binding, Quaternary Structure and a Novel Hydrophobic Binding Site in Two Legume to four. # 1999 Academic Press Keywords: protein-carbohydrate interactions; quaternary structure; legume carbohydrates in a reversible fashion, without showing enzymatic activity towards these carbohydrates. Lectins

Hamelryck, Thomas

414

The tempo of avian diversification during the Quaternary.  

PubMed Central

It is generally assumed that the Quaternary was a period of heightened diversification in temperate vertebrate organisms. Previous molecular systematics studies have challenged this assertion. We re-examined this issue in north temperate birds using log-lineage plots and distributions of sister-taxon distances. Log-lineage plots support earlier conclusions that avian diversification slowed during the Quaternary. To test plots of empirical sister-taxon distances we simulated three sets of phylogenies: constant speciation and extinction, a pulse of recent speciation, and a pulse of recent extinction. Previous opinions favour the model of recent speciation although our empirical dataset on 74 avian comparisons failed to reject a distribution derived from the constant and extinction models. Hence, it does not appear that the Quaternary was a period of exceptional rates of diversification, relative to the background rate. PMID:15101578

Zink, Robert M; Klicka, John; Barber, Brian R

2004-01-01

415

Tertiary and Quaternary Research with Remote Sensing Methods  

NASA Technical Reports Server (NTRS)

Problems encountered in mapping the Quaternary section of the Wind River Region using remote sensing methods are discussed. Analysis of the stratigraphic section is a fundamental aspect of the geologic study of sedimentary basins. Stratigraphic analysis of post-Cretaceous rocks in the Wind River Basin encounters problems of a distinctly different character from those involved in studying the pre-Cretaceous section. The interior of the basin is predominantly covered by Tertiary and Quaternary sediments. These rocks, except on the basin margin to the north, are mostly flat lying or gently dipping. The Tertiary section consists of sandstones, siltstones, and tuffaceous sediments, some variegated, but in general poorly bedded and of great lithologic similarity. The Quaternary sediments consist of terrace, fan, and debris tongue deposits, unconsolidated alluvium occupying the bottoms of modern watercourses, deposits of eolian origin and tufa. Terrace and fan deposits are compositionally diverse and reflect the lithologic diversity of the source terranes.

Conel, J. E.

1985-01-01

416

Quaternary naltrexone reverses radiogenic and morphine-induced locomotor hyperactivity  

SciTech Connect

The present study attempted to determine the relative role of the peripheral and central nervous system in the production of morphine-induced or radiation-induced locomotor hyperactivity of the mouse. Toward this end, we used a quaternary derivative of an opiate antagonist (naltrexone methobromide), which presumably does not cross the blood-brain barrier. Quaternary naltrexone was used to challenge the stereotypic locomotor response observed in these mice after either an i.p. injection of morphine or exposure to 1500 rads /sup 60/Co. The quaternary derivative of naltrexone reversed the locomotor hyperactivity normally observed in the C57BL/6J mouse after an injection of morphine. It also significantly attenuated radiation-induced locomotion. The data reported here support the hypothesis of endorphin involvement in radiation-induced and radiogenic behaviors. However, these conclusions are contingent upon further research which more fully evaluates naltrexone methobromide's capacity to cross the blood-brain barrier.

Mickley, G.A.; Stevens, K.E.; Galbraith, J.A.; White, G.A.; Gibbs, G.L.

1984-04-01

417

Chemical modification of poly (vinyl chloride) sheet with thiourea for cell study  

NASA Astrophysics Data System (ADS)

Plasticized poly (vinyl chloride) has been used as biomaterial to make medical equipment. An appropriate reaction situation by temperature at 60-85°C for the surface modification of PVC sheet with sodium thiourea has been investigated. Although, the use of a phase-transfer catalyst (Tetra butyl ammonium hydrogen sulphate-TBHAS) makes it feasible for the nucleophilic substitution reaction to take place, the morphology of the film is changed by the reaction, leading to a loss in both surface smoothness and transparency of the film. According to this study, the reaction with sodium thiourea occurs consistently through the sheets, and modified surface have antibacterial capacity.

Monika, Mishra, R. R.; Jaiswal, S.; Kapusetti, G.; Misra, N.

2013-06-01

418

Interactions of a cationic surfactant--(benzyloxymethyl) dodecyldimethylammonium chloride with model biomembrane systems.  

PubMed

Phospholipids are the main components of biological membranes. The aim of the present study was to determine the influence of a cationic surfactant on phospholipid structure and dynamics. Fourier transform infrared (FTIR) and dielectric relaxation (DRS) spectroscopies as well as small-angle X-ray scattering (SAXS) with synchrotron radiation have been used to analyse the structure of fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in the presence of a quaternary ammonium surfactant: (benzyloxymethyl) dodecyldimethylammoniumchloride (BzMDDAC). The presence of the surfactant caused changes in the temperature of the DMPC phase transition, as revealed using FTIR and DRS measurements. This change results from the disappearance of the multilamellar phase of DMPC and the formation of the unilamellar (most likely bicellar) phase, as indicated by the SAXS results. PMID:23584361

Wypych, Aleksandra; Szpotkowski, Kamil; Jurga, Stefan; Domka, Ludwik; Kozak, Maciej

2013-08-01

419

Characterization of Quaternary and suspected Quaternary faults, Amargosa area, Nevada and California  

SciTech Connect

This report presents the results of geologic studies that help define the Quaternary history of selected faults in the region around Yucca Mountain, Nevada. These results are relevant to the seismic-design basis of a potential nuclear waste repository at Yucca Mountain. The relevancy is based, in part, on a need for additional geologic data that became apparent in ongoing studies by S. Pezzopane (written commun., 1995) that resulted in the identification of 51 relevant and potentially relevant (see appendix A for definitions) individual and compound faults and fault zones in the 100-km-radius region around the Yucca Mountain site. These structures were divided into local and regional categories by Pezzopane (1995); this report deals with selected regional structures. In this introduction, the authors outline the scope and strategy of the studies and the tectonic environment of the studied structures.

Anderson, R.E.; Crone, A.J.; Machette, M.N.; Bradley, L.A.; Diehl, S.F.

1995-12-31

420

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2010 CFR

...from iron and chlorine or from ferric oxide and hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride hexahydrate, FeC13 . 6H2 0, CAS Reg. No. 10025-77-1)...

2010-04-01

421

21 CFR 184.1297 - Ferric chloride.  

...from iron and chlorine or from ferric oxide and hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride hexahydrate, FeC13. 6H2 0, CAS Reg. No. 10025-77-1)...

2014-04-01

422

Vinyl Chloride Loss during Laboratory Holding Time  

Microsoft Academic Search

Because vinyl chloride is a potent human carcinogen, it is important that analytical results from groundwater samples accurately reflect levels of exposure to groundwater users. This study investigated the current allowable holding time of 14 days to determine if vinyl chloride is lost from samples during this time. Samples containing an initial concentration of 2 ?g\\/liter of vinyl chloride showed

Richard Soule; Daniel Symonik; David Jones; Doug Turgeon; Betsy Gerbec

1996-01-01

423

The third-order elastic constants of potassium chloride, sodium chloride and lithium fluoride  

Microsoft Academic Search

The complete set of third-order elastic constants of potassium chloride, sodium chloride and lithium fluoride have been measured at room temperature under conditions which eliminate the possibility that plastic deformation occurred during the experiments. A partial check on these values, provided by the pressure derivatives of the elastic constants, shows satisfactory agreement with experiment for potassium chloride and sodium chloride

J. R. Drabble; R. E. B. Strathen

1967-01-01

424

Ice Age Earth: Late Quaternary geology and climate  

SciTech Connect

This book is a concise and readable account of the most important geologic records of the late Quaternary. It provides a synopsis of the major environmental changes that took place from approximately 13,000 to 7,000 years ago, highlighting the complexity and rapidity of past climate changes and the environmental responses they produced. The text is well illustrated, though some figures are rough and need more explanation. Also needed is a critical appraisal of the geochronology which places the paleoenvironmental records into the temporal domain. However, as a whole the book reaches its objective of summarizing the most important scientific findings about the nature of the late Quaternary climate changes.

Dawson, A.G.

1992-01-01

425

Quaternary glaciation of the Himalayan-Tibetan orogen  

Microsoft Academic Search

ABSTRACT: Glacial geological,evidence,from,throughout,the,Himalayan–Tibetan,orogen,is examined,to determine,the timing and,extent of late Quaternary,glaciation in this region and,its relation to similar changes,on a global scale. The evidence,summarised,here supports the existence of expanded,ice caps,and,extensive,valley glacier systems,throughout,the region,during,the late Quaternary. However, it cannot yet be determined whether the timing of the extent of maximum glaciation was synchronous,throughout,the entire region or whether,the response was more,varied. The lack

Lewis A. Owen; Marc W. Caffee; Robert C. Finkel; Yeong Bae Seong

2008-01-01

426

Studies on Acetone Powder and Purified Rhus Laccase Immobilized on Zirconium Chloride for Oxidation of Phenols  

PubMed Central

Rhus laccase was isolated and purified from acetone powder obtained from the exudates of Chinese lacquer trees (Rhus vernicifera) from the Jianshi region, Hubei province of China. There are two blue bands appearing on CM-sephadex C-50 chromatography column, and each band corresponding to Rhus laccase 1 and 2, the former being the major constituent, and each had an average molecular weight of approximately 110?kDa. The purified and crude Rhus laccases were immobilized on zirconium chloride in ammonium chloride solution, and the kinetic properties of free and immobilized Rhus laccase, such as activity, molecular weight, optimum pH, and thermostability, were examined. In addition, the behaviors on catalytic oxidation of phenols also were conducted. PMID:22545205

Lu, Rong; Miyakoshi, Tetsuo

2012-01-01

427

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2010 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2010-04-01

428

Dry process fluorination of uranium dioxide using ammonium bifluoride  

E-print Network

An experimental study was conducted to determine the practicality of various unit operations for fluorination of uranium dioxide. The objective was to prepare ammonium uranium fluoride double salts from uranium dioxide and ...

Yeamans, Charles Burnett, 1978-

2003-01-01

429

Formation of urea and guanidine by irradiation of ammonium cyanide.  

NASA Technical Reports Server (NTRS)

Aqueous solutions of ammonium cyanide yield urea, cyanamide and guanidine when exposed to sunlight or an unfiltered 254 nm ultraviolet source. The prebiotic significance of these results is discussed.

Lohrmann, R.

1972-01-01

430

Wastewater purification to remove ammonium ions by the oxidation method  

Microsoft Academic Search

Wastewater purification to remove ammonium ions and carbamide by oxidation with hypochlorites of alkali and alkaline-earth\\u000a metals was studied. The effect of various factors on the degree of purification was examined experimentally.

S. A. Lobanov; V. Z. Poilov; A. V. Sofronova

2006-01-01

431

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2014-04-01

432

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2012 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2012-04-01

433

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2013 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2013-04-01

434

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2011 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2011-04-01

435

Direct esterification of ammonium salts of carboxylic acids  

DOEpatents

A non-catalytic process for producing esters, the process comprising reacting an ammonium salt of a carboxylic acid with an alcohol and removing ammonia from the reaction mixture. Selectivities for the desired ester product can exceed 95 percent.

Halpern, Yuval (Skokie, IL)

2003-06-24

436

Ammonium ylides for the diastereoselective synthesis of glycidic amides†  

PubMed Central

A highly trans-selective protocol for the synthesis of glycidic amides was developed. This approach gave access to oxiranes by reacting stabilised ammonium ylides bearing an ?-carbonyl group and aromatic aldehydes in moderate to good yields. PMID:21180720

Waser, Mario; Herchl, Richard; Muller, Norbert

2014-01-01

437

Methods to Stabilize and Destabilize Ammonium Borohydride  

SciTech Connect

Ammonium borohydride, NH4BH4, has a high hydrogen content of ?m = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may be explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ?T = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.

Nielsen, Thomas K.; Karkamkar, Abhijeet J.; Bowden, Mark E.; Besenbacher, Fleming; Jensen, Torben R.; Autrey, Thomas

2013-01-21

438

Study on All-Solid-State Chloride Sensor Based on Tin Oxide/Indium Tin Oxide Glass  

NASA Astrophysics Data System (ADS)

An all-solid-state chloride electrode based on a tin oxide (SnO2)/indium tin oxide (ITO) glass was developed in this study. The sensing membrane of the electrode was prepared by mixing poly(vinyl chloride) (PVC), bis(2-ethylhexyl) sebacate (DOS), [4,5-dimethy-l-3,6-bis(dodecyloxy)-1,2-phenylene] bis(mercury chloride) (ETH9033), and tridodecylmethyl ammonium chloride (TDDMACl). The mixed solution was mixed with tetrahydrofuran (THF), and then dropped on the sensing window of SnO2/ITO glass. According to the experimental results, the optimal weight ratio were PVC:DOS:ETH9033:TDDMACl=33:66:2:5. At this optimum weight ratio, the sensitivity was 54 mV/dec while the range of linear concentrations of NaCl solutions was between 10-4 and 1 M. The lower detection limit of the sensor reached 8×10-5 M and the response time was less than 1 s. The selectivity coefficient was consistent with the theory of Hofmeister lipophilicity. The lifetime was over 60 days and the repeatability was over 50 times. Moreover, the chloride ion sensor was successfully applied to detecting chloride ions in rinsing solutions for contact lenses, and the experimental results revealed that the correlation coefficient was 0.99.

Cheng, Jui-Fu; Chou, Jung-Chuan; Sun, Tai-Ping; Hsiung, Shen-Kan; Kao, Hui-Ling

2011-03-01

439

Influence of Heteroanion and Ammonium Cation Size on the Composition and Gas-Phase Fragmentation of Polyoxovanadates  

SciTech Connect

This paper describes the results of a systematic experimental investigation of the influence of different size cationic ammonium ligands and heteroanions on the composition, ionic charge state and gas-phase fragmentation pathways of anionic polyoxovanadates synthesized in solution. Four separate solutions of olyoxometalates (POMs) were prepared using all possible combinations of the tetraethylammonium [(C2H5)4N+] ligand, chloride (Cl-) heteroanion, tetrabutylammonium [(C4H9)4N+] ligand and acetate (CH3CO2-) heteroanion. Employing electrospray ionization combined with high-resolution mass spectrometry (ESI-MS) we demonstrate that POM solutions synthesized using the small [(C2H5)4N+] ligand and Cl-heteroanion are composed predominately of large doubly and triply charged chlorine containing clusters with a size distribution centered at fourteen vanadium atoms. POM solutions prepared using the Cl- anion and [(C4H9)4N+] ligand are shown to contain slightly larger clusters with fifteen and sixteen vanadium atoms, thereby indicating that the size of the cationic ammonium ligand exerts only a weak influence on the polymerization of polyoxovanadates. POM solutions prepared using (C2H5)4NCl and (C4H9)4NCl also produced peaks consistent with the attachment of one and two ammonium cations to the larger clusters. Solutions prepared using the large CH3CO2 - heteroanion, in contrast, are demonstrated to contain much smaller singly and doubly *Manuscript Click here to view linked References 2 charged clusters with a size distribution centered at six vanadium atoms. In addition, while incorporation of one and two ammonium ligands into the smaller clusters was observed, no POMs containing the CH3CO2 - heteroanion were identified. The gas-phase fragmentation pathways of representative POMs containing one and two ammonium ligands were examined using collision induced dissociation (CID) and mass spectrometry. Similar primary fragmentation pathways involving partial loss of a ligand -[(CxHy)3N+ x = 2,4; y = 5,9] were observed for clusters containing both one and two ligands largely independent of the size, composition and charge state of the precursor ion. The [(C4H9)4N+] ligand was found to exhibit stronger interactions with the core of the POMs resulting in higher abundances of fragment ions containing (C4H9) units compared to (C2H5) units from [(C2H5)4N+]. These results provide fundamental insight into the interactions between anionic metal oxide clusters, heteroanions and cationic ammonium ligands that are responsible for the size and composition controlled synthesis of POMs in solution.

Johnson, Grant E.; Al Hasan, Naila M.; Laskin, Julia

2013-11-15

440

Thermal Decomposition Behavior of Ammonium Perchlorate and of an Ammonium-Perchlorate-Based Composite Propellant  

NASA Technical Reports Server (NTRS)

The thermal decomposition of ammonium perchlorate (AP) and ammonium-perchlorate-based composite propellants is studied using the simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) technique. The main objective of the present work is to evaluate whether the STMBMS can provide new data on these materials that will have sufficient detail on the reaction mechanisms and associated reaction kinetics to permit creation of a detailed model of the thermal decomposition process. Such a model is a necessary ingredient to engineering models of ignition and slow-cookoff for these AP-based composite propellants. Results show that the decomposition of pure AP is controlled by two processes. One occurs at lower temperatures (240 to 270 C), produces mainly H2O, O2, Cl2, N2O and HCl, and is shown to occur in the solid phase within the AP particles. 200(micro) diameter AP particles undergo 25% decomposition in the solid phase, whereas 20(micro) diameter AP particles undergo only 13% decomposition. The second process is dissociative sublimation of AP to NH3 + HClO4 followed by the decomposition of, and reaction between, these two products in the gas phase. The dissociative sublimation process occurs over the entire temperature range of AP decomposition, but only becomes dominant at temperatures above those for the solid-phase decomposition. AP-based composite propellants are used extensively in both small tactical rocket motors and large strategic rocket systems.

Behrens, R.; Minier, L.

1998-01-01

441

ATS (ammonium thiosulfate) Claus tail-gas cleanup process  

Microsoft Academic Search

The ATS (ammonium thiosulfate) Claus tail-gas cleanup process was developed by the Pritchard Corp. and installed for Colorado Interstate Gas Corp. (CIG) and Wycon Chemical Co. at CIG's Table Rock, Wyo., natural gas-treatment plant to process tail gas from an 80 ton\\/day Claus plant. The new unit will produce 18,140 tons\\/yr of ammonium thiosulfate fertilizer solution. In the first, absorption

A. Zey; S. White; D. Johnson

1980-01-01

442

Nitric oxide controls nitrate and ammonium assimilation in Chlamydomonas reinhardtii.  

PubMed

Nitrate and ammonium are major inorganic nitrogen sources for plants and algae. These compounds are assimilated by means of finely regulated processes at transcriptional and post-translational levels. In Chlamydomonas, the expression of several genes involved in high-affinity ammonium (AMT1.1, AMT1.2) and nitrate transport (NRT2.1) as well as nitrate reduction (NIA1) are downregulated by ammonium through a nitric oxide (NO)-dependent mechanism. At the post-translational level, nitrate/nitrite uptake and nitrate reductase (NR) are also inhibited by ammonium, but the mechanisms implicated in this regulation are scarcely known. In this work, the effect of NO on nitrate assimilation and the high-affinity ammonium uptake was addressed. NO inhibited the high-affinity uptake of ammonium and nitrate/nitrite, as well as the NR activity, in a reversible form. In contrast, nitrite reductase and glutamine synthetase activities were not affected. The in vivo and in vitro studies suggested that NR enzyme is inhibited by NO in a mediated process that requires the cell integrity. These data highlight a role of NO in inorganic nitrogen assimilation and suggest that this signalling molecule is an important regulator for the first steps of the pathway. PMID:23918969

Sanz-Luque, Emanuel; Ocaña-Calahorro, Francisco; Llamas, Angel; Galvan, Aurora; Fernandez, Emilio

2013-08-01

443

Anaerobic ammonium oxidation by anammox bacteria in the Black Sea  

NASA Astrophysics Data System (ADS)

The availability of fixed inorganic nitrogen (nitrate, nitrite and ammonium) limits primary productivity in many oceanic regions. The conversion of nitrate to N2 by heterotrophic bacteria (denitrification) is believed to be the only important sink for fixed inorganic nitrogen in the ocean. Here we provide evidence for bacteria that anaerobically oxidize ammonium with nitrite to N2 in the world's largest anoxic basin, the Black Sea. Phylogenetic analysis of 16S ribosomal RNA gene sequences shows that these bacteria are related to members of the order Planctomycetales performing the anammox (anaerobic ammonium oxidation) process in ammonium-removing bioreactors. Nutrient profiles, fluorescently labelled RNA probes, 15N tracer experiments and the distribution of specific `ladderane' membrane lipids indicate that ammonium diffusing upwards from the anoxic deep water is consumed by anammox bacteria below the oxic zone. This is the first time that anammox bacteria have been identified and directly linked to the removal of fixed inorganic nitrogen in the environment. The widespread occurrence of ammonium consumption in suboxic marine settings indicates that anammox might be important in the oceanic nitrogen cycle.

Kuypers, Marcel M. M.; Sliekers, A. Olav; Lavik, Gaute; Schmid, Markus; Jørgensen, Bo Barker; Kuenen, J. Gijs; Sinninghe Damsté, Jaap S.; Strous, Marc; Jetten, Mike S. M.

2003-04-01

444

The Spectrum of Gold Chloride  

Microsoft Academic Search

The spectrum of gold chloride vapor excited by streaming active nitrogen was photographed. It was found to consist of 43 bands comprising, for each isotope of AuCl, two intermingled systems in the green region. All the bands are shaded toward the red. No other bands were found between lambdalambda7000-2000. The band heads of each system were measured, and equations are

W. F. Ferguson

1928-01-01

445

Chloride flux out of Yellowstone National Park  

USGS Publications Warehouse

Monitoring of the chloride concentration, electrical conductivity, and discharge was carried out for the four major rivers of Yellowstone National Park from September 1982 to January 1984. Chloride flux out of the Park was determined from the measured values of chloride concentration and discharge. The annual chloride flux from the Park was 5.86 ?? 1010 g. Of this amount 45% was from the Madison River drainage basin, 32% from the Yellowstone River basin, 12% from the Snake River basin, and 11% from the Falls River basin. Of the annual chloride flux from the Yellowstone River drainage basin 36% was attributed to the Yellowstone Lake drainage basin. The geothermal contribution to the chloride flux was determined by subtracting the chloride contribution from rock weathering and atmospheric precipitation and is 94% of the total chloride flux. Calculations of the geothermal chloride flux for each river are given and the implications of an additional chloride flux out of the western Park boundary discussed. An anomalous increase in chloride flux out of the Park was observed for several weeks prior to the Mt. Borah earthquake in Central Idaho on October 28, 1983, reaching a peak value shortly thereafter. It is suggested that the rise in flux was a precursor of the earthquake. The information in this paper provides baseline data against which future changes in the hydrothermal systems can be measured. It also provides measurements related to the thermal contributions from the different drainage basins of the Park. ?? 1985.

Norton, D.R.; Friedman, I.

1985-01-01

446

Community inertia of Quaternary small mammal assemblages in North America  

E-print Network

Community inertia of Quaternary small mammal assemblages in North America Brian J. Mc is often studied by looking for the presence or absence of community inertia (lack of change) over time reference points for the amount of inertia in random biological systems, and (iii) using a robust approach

Hadly, Elizabeth

447

Impact of Quaternary Structure Dynamics on Allosteric Drug Discovery  

PubMed Central

The morpheein model of allosteric regulation draws attention to proteins that can exist as an equilibrium of functionally distinct assemblies where: one subunit conformation assembles into one multimer; a different subunit conformation assembles into a different multimer; and the various multimers are in a dynamic equilibrium whose position can be modulated by ligands that bind to a multimer-specific ligand binding site. The case study of porphobilinogen synthase (PBGS) illustrates how such an equilibrium holds lessons for disease mechanisms, drug discovery, understanding drug side effects, and identifying proteins wherein drug discovery efforts might focus on quaternary structure dynamics. The morpheein model of allostery has been proposed as applicable for a wide assortment of disease-associated proteins (Selwood, T., Jaffe, E., (2012) Arch. Bioch. Biophys, 519:131–143). Herein we discuss quaternary structure dynamics aspects to drug discovery for the disease-associated putative morpheeins phenylalanine hydroxylase, HIV integrase, pyruvate kinase, and tumor necrosis factor ?. Also highlighted is the quaternary structure equilibrium of transthyretin and successful drug discovery efforts focused on controlling its quaternary structure dynamics. PMID:23409765

Jaffe, Eileen K.

2013-01-01

448

Pliocene - Quaternary Faults and Potential Seismic Hazards in Southern Nevada  

Microsoft Academic Search

Known Quaternary faults in the Central Basin & Range Province (CBR) have a southern limit at about 35 degrees 30' N latitude, south of Las Vegas, NV. The boundary is generally aligned with the southern end of the Sierra Nevada and strike-slip faults, such as those in Death Valley, that accommodate the right-lateral motion transferred from the plate boundary to

W. J. Taylor; J. Wagoner; C. M. Depolo; B. Luke; J. Louie

2005-01-01

449

The newsletter of the CAMBRIDGE QUATERNARY ISSUE 32 MICHAELMAS 2005  

E-print Network

Research Institute and the British Antarctic Survey. The research environment at all levels is fostered in a wide range of Quaternary fields. This environment is unique in Britain, offering opportunities Antarctic Survey and Geography), Professor Roy Switsur (Godwin Lab), Professor Martin Jones (Archaeology

de Gispert, Adrià

450

Quaternary Paleoecology and Climate Change, Bladen County, NC  

NSDL National Science Digital Library

Students analyze a Quaternary pollen diagram from lakes in Bladen County, NC. This diagram contains (from the top down) the current deglaciation, the last glacial, and the previous interglacial. Students These lakes occur in Carolina Bays and students also evaluate a proposal that meteorite impact created the Bays.

Farley, Martin

451

The Quaternary Structure of the Saccharomyces cerevisiae Succinate Dehydrogenase  

Microsoft Academic Search

Succinate dehydrogenases and fumarate reductases are complex mitochondrial or bacterial respiratory chain proteins with remarkably similar structures and functions. Succinate dehydrogenase oxidizes succinate and reduces ubiquinone using a flavin adenine dinucle- otide cofactor and iron-sulfur clusters to transport elec- trons. A model of the quaternary structure of the tetrameric Saccharomyces cerevisiae succinate dehydrogenase was constructed based on the crystal structures

Kayode S. Oyedotun; Bernard D. Lemire

452

Quaternary fossil fish from the Kibish Formation, Omo Valley, Ethiopia  

Microsoft Academic Search

The late Quaternary Kibish Formation of the Omo Valley, southwestern Ethiopia, preserves environments reflecting a history of fluctuations in the level of nearby Lake Turkana over the past 200,000 years. The Kibish Formation has yielded a diverse mammalian fauna (as well as birds and crocodiles), stone tools, and the oldest anatomically modern Homo sapiens. Fish, the most common vertebrate fossils

Josh Trapani

2008-01-01

453

Recent dolomitization of quaternary biocalcarenites from fuerteventura (Canary Islands)  

Microsoft Academic Search

Quaternary marine and eolian biocalcarenites in the supratidal breaker and spray zone along the Barlovento coast of the peninsula Jandía, Fuerteventura (Canary Islands) are dolomitized by percolating brines with a high Mg\\/Ca ratio resulting from evaporation of seawater on the sediment's surface. Only fragments of calcareous algae primarily consisting of high-magnesian calcite are replaced by a cryptocrystalline variety of dolomite.

German Müller; Rerd Tietz

1966-01-01

454

Lignin biogeochemistry: from modern processes to Quaternary archives  

NASA Astrophysics Data System (ADS)

Lignin has been analysed as a proxy for vegetation change in the Quaternary science literature since the early 1990s in archives such as peat, lakes, and intertidal and marine sediment cores. Historically, it has been regarded as comparatively resistant to various types of degradation in comparison to other plant components. However, studies of modern biogeochemical processes affecting organic carbon have demonstrated significant degradation and alteration of lignin as it is transported through the terrestrial biosphere, including phase changes from particulate to dissolved organic matter, mineral binding and decay due to biotic and abiotic processes. The literature of such topics is vast, however it is not particularly useful to Quaternary research without a comprehensive review to link our understanding of modern processes involving lignin to Quaternary environments. This review will outline the current state of the art in lignin phenol research that is relevant to the Quaternary scientist, and highlight the potential future applications for this important biomarker for vegetation change and terrestrial organic carbon cycling.

Jex, Catherine N.; Pate, Gary H.; Blyth, Alison J.; Spencer, Robert G. M.; Hernes, Peter J.; Khan, Stuart J.; Baker, Andy

2014-03-01

455

Quaternary glaciation in Africa: key chronologies and climatic implications  

Microsoft Academic Search

Multiple episodes of Quaternary glaciation are evidenced on >10 distinct mountain localities throughout Africa, with the best dated sites from Kilimanjaro and Mt Kenya in equatorial East Africa. A general paucity of radiogenic dates constrains the glacial chronology, and regional sequences have largely been based on correlations by relative weathering of features. Excellent glacial moraine preservation and other features of

Bryan G. Mark; Henry A. Osmaston

2008-01-01

456

Clinoptilolite: a possible support material for nitrifying biofilms for effective control of ammonium effluent quality?  

PubMed

Ammonium selective natural zeolite clinoptilolite is suggested as a possible support material for nitrifying biofilms to help improve effluent ammonium quality through its high capacity of ammonium removal in the process of ion exchange. This will especially be helpful in cases where the biofilter receives peak or variable loads routinely or occasionally. At the time of peak loads or shocks of ammonium, ion exchange capacity will provide a buffer for the effluent ammonium quality. Data to support this suggestion is presented. PMID:16114618

Inan, H; Beler Baykal, B

2005-01-01

457

Preferential leaching of cobalt, nickel and copper from cobalt-rich ferromanganese crusts with ammoniacal solutions using ammonium thiosulfate and ammonium sulfite as reducing agents  

Microsoft Academic Search

Preferential ammoniacal leaching of Co, Ni and Cu from cobalt-rich ferromanganese crusts under reducing conditions was performed using ammonium thiosulfate and ammonium sulfite as reducing agents. The effects of reducing agent concentration, initial pH, leaching time, temperature and the combined concentration of ammonium thiosulfate and ammonium sulfite on the extraction of Mn, Fe, Co, Ni and Cu were investigated.The extraction

M. Niinae; N. Komatsu; Y. Nakahiro; T. Wakamatsu; J. Shibata

1996-01-01

458

Characterization of Quaternary and suspected Quaternary faults, regional studies, Nevada and California  

SciTech Connect

This report presents the results of geologic studies that help define the Quaternary history of selected faults in the region around Yucca Mountain, Nevada. These results are relevant to the seismic-design basis of a potential nuclear waste repository at Yucca Mountain. The relevancy is based, in part, on a need for additional geologic data that became apparent in ongoing studies that resulted in the identification of 51 relevant and potentially relevant individual and compound faults and fault zones in the 100-km-radius region around the Yucca Mountain site. Geologic data used to characterize the regional faults and fault zones as relevant or potentially relevant seismic sources includes age and displacement information, maximum fault lengths, and minimum distances between the fault and the Yucca Mountain site. For many of the regional faults, no paleoseismic field studies have previously been conducted, and age and displacement data are sparse to nonexistent. In November 1994, the Branch of Earthquake and Landslide Hazards entered into two Memoranda of Agreement with the Yucca Mountain Project Branch to conduct field reconnaissance, analysis, and interpretation of six relevant and six potentially relevant regional faults. This report describes the results of study of those faults exclusive of those in the Pahrump-Stewart Valley-Ash Meadows-Amargosa Valley areas. We also include results of a cursory study of faults on the west flank of the Specter Range and in the northern part of the Last Chance Range. A four-phase strategy was implemented for the field study.

Anderson, R.E.; Bucknam, R.C.; Crone, A.J.; Haller, K.M.; Machette, M.N.; Personius, S.F.; Barnhard, T.P.; Cecil, M.J.; Dart, R.L.

1995-12-31

459

Quaternary and pre-Quaternary( ) materials and processes of southeast Ohio: Overview, speculations, and recommendations  

SciTech Connect

Investigations and mapping of surficial deposits in Ohio have focused largely on the glacial deposits which cover nearly two-thirds of the state. Research on Quaternary deposits beyond the glacial border has been done by Foster, Hildreth, Andrews, Leverett, Tight, Stout, Goldthwait, Forsyth, Lessig, White, Totten, Hoyer, and Noltimier. However, growing human interaction with surficial materials of southeast Ohio now requires much more detailed mapping and characterization of these deposits. Recognition of periglacial, proglacial, and preglacial processes and materials in eastern and southern states has led to the search for similar processes and materials in southeast Ohio. Evidence for gelifraction, gelifluction, cryoturbation, and considerable periglacial colluviation is more extensive than previously thought. Proglacial deposits are also much more extensive, outwash and glaciolacustrine deposits cover large areas in southeast Ohio and are poorly mapped and characterized, or not mapped at all. Preglacial processes including a long span of profound weathering and formation of saprolite have been given little or no attention in southeast Ohio. The signature of protracted preglacial weathering still remains in this part of the state, and should change prevailing views of the terrain upon which periglacial processes worked. Mapping and characterization of these materials are urgently needed as citizens make important land-use decisions such as locating landfills and new developments.

Berg, T.M. (Ohio Geological Survey, Columbus, OH (United States))

1992-01-01

460

An XAFS Study of Niobium chloride in the ionic liquid 1-ethyl-3-methyl imidazolium chloride/ aluminum chloride  

SciTech Connect

Niobium chloride was studied with extended X-ray absorption fine structure spectroscopy (EXAFS) in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Although anhydrous Nb2Cl10 is more soluble in the basic melt than in the acidic melt, the EXAFS data shows that the coordination shell around the niobium does not change in the different ionic liquids. Both the acidic and basic melts show a coordination of five chlorides in the first shell. This indicates that in this series of ionic liquids, the Nb2Cl10 breaks up into two NbCl5 entities in both the acidic and the basic melts.

D Roeper; K Pandya; G Cheek; W OGrady

2011-12-31