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Sample records for easily removable cationic

  1. Synthesis, characterization and application of water-soluble and easily removable cationic pressure-sensitive adhesives. Quarterly technical report

    SciTech Connect

    1999-09-30

    The Institute studied the adsorption of cationic pressure-sensitive adhesive (PSA) on wood fiber, and the buildup of PSA in a closed water system during paper recycling; the results are presented. Georgia Tech worked to develop an environmentally friendly polymerization process to synthesize a novel re-dispersible PSA by co-polymerizing an oil-soluble monomer (butyl acrylate) and a cationic monomer MAEPTAC; results are presented. At the University of Georgia at Athens the project focused on the synthesis of water-soluble and easily removable cationic polymer PSAs.

  2. Synthesis, Characterization, to application of water soluble and easily removable cationic pressure sensitive adhesives

    SciTech Connect

    Institute of Paper Science Technology

    2004-01-30

    In recent years, the world has expressed an increasing interest in the recycling of waste paper to supplement the use of virgin fiber as a way to protect the environment. Statistics show that major countries are increasing their use of recycled paper. For example, in 1991 to 1996, the U.S. increased its recovered paper utilization rate from 31% to 39%, Germany went from 50% to 60%, the UK went from 60% to 70%, France increased from 46% to 49%, and China went from 32% to 35% [1]. As recycled fiber levels and water system closures both increase, recycled product quality will need to improve in order for recycled products to compete with products made from virgin fiber [2]. The use of recycled fiber has introduced an increasing level of metal, plastic, and adhesive contamination into the papermaking process which has added to the complexity of the already overwhelming task of providing a uniform and clean recycle furnish. The most harmful of these contaminates is a mixture of adhesives and polymeric substances that are commonly known as stickies. Stickies, which enter the mill with the pulp furnish, are not easily removed from the repulper and become more difficult the further down the system they get. This can be detrimental to the final product quality. Stickies are hydrophobic, tacky, polymeric materials that are introduced into the papermaking system from a mixture of recycled fiber sources. Properties of stickies are very similar to the fibers used in papermaking, viz. size, density, hydrophobicity, and electrokinetic charge. This reduces the probability of their removal by conventional separation processes, such as screening and cleaning, which are based on such properties. Also, their physical and chemical structure allows for them to extrude through screens, attach to fibers, process equipment, wires and felts. Stickies can break down and then reagglomerate and appear at seemingly any place in the mill. When subjected to a number of factors including changes

  3. Shaft seals with an easily removable cylinder holder for low-pressure steam turbines

    NASA Astrophysics Data System (ADS)

    Zakharov, A. E.; Rodionov, D. A.; Pimenov, E. V.; Sobolev, A. S.

    2016-01-01

    The article is devoted to the problems that occur at the operation of LPC shaft seals (SS) of turbines, particularly, their bearings. The problems arising from the deterioration of oil-protecting rings of SS and bearings and also the consequences in which they can result are considered. The existing SS housing construction types are considered. Their operational features are specified. A new SS construction type with an easily removable holder is presented. The construction of its main elements is described. The sequence of operations of the repair personnel at the restoration of the new SS type spacings is proposed. The comparative analysis of the new and the existing SS construction types is carried out. The assessment results of the efficiency, the operational convenience, and the economic effect after the installation of the new type seals are given. The conclusions about the offered construction prospects are made by results of the comparative analysis and the carried-out assessment. The main advantage of this design is the possibility of spacings restoration both in SS and in oil-protecting rings during a short-term stop of a turbine, even without its cooling. This construction was successfully tested on the working K-300-23.5 LMP turbine. However, its adaptation for other turbines is quite possible.

  4. Removal of 1-ethyl-3-methylimidazolium cations with bacterial biosorbents from aqueous media.

    PubMed

    Won, Sung Wook; Choi, Sun Beom; Mao, Juan; Yun, Yeoung-Sang

    2013-01-15

    This study aims to determine whether biosorption can be used for the removal of ionic liquids (ILs), especially their cationic parts, from aqueous media. As a model IL, 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) was used. Five types of bacterial biosorbents were prepared from fermentation wastes through chemical modification of the bacterial surface. Screening study was performed to compare the cationic [EMIM] biosorption capacity among the bacterial biosorbents, indicating that the succinated Escherichia coli biomass (SB-E) was the best biosorbent for removing [EMIM] cations. The [EMIM] biosorption performance of SB-E was evaluated in detail through various experiments. The optimal pH range for [EMIM] biosorption was from 7 to 10, and biosorption equilibrium was reached within 10 min. The maximum uptake of SB-E was also estimated to be 72.6 mg/g. Moreover, [EMIM] cations were easily desorbed from [EMIM]-sorbed SB-E by adding acetic acid. PMID:23246948

  5. IS GUTTACORE MORE EASILY REMOVED FROM THE ROOT CANAL THAN THERMAFIL? AN EX-VIVO STUDY.

    PubMed

    Nevares, Giselle; de Albuquerque, Diana Santana; Bueno, Carlos Eduardo da Silveira; Cunha, Rodrigo Sanches

    2015-01-01

    GuttaCore is a new cross-linked gutta-percha carrier. Its handling time and ease of removal were compared with those of a plastic carrier (Thermafil) and the continuous wave of condensation technique (control). Forty-five maxillary central incisors were randomly divided 3 groups according to filling technique and retreatment was carried out in all samples with NiTi rotary files, hand files and ultrasonic inserts. Time required for filling removal was recorded. Roots were then split longitudinally and photographed under 5x magnification, and residual filling material was quantified. Removal time was significantly longer for Thermafil (7.10 minutes) than GuttaCore (2.91 minutes) and the control group (1.93 minutes) (p < 0.001). The amount of residual filling material did not differ among the groups: Thermafil 8.31%, GuttaCore 6.27 and control 8.68% (p > 0.05). In conclusion, replacing plastic core with cross-linked gutta-percha allows easier removal of carrier from the root canal. The remnants of filling material in all samples illustrate that retreatment remains a challenge in endodontics. PMID:26679336

  6. Copper cation removal in an electrokinetic cell containing zeolite.

    PubMed

    Elsayed-Ali, Omar H; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E

    2011-01-30

    Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers. PMID:21109348

  7. Transport of sewage molecular markers through saturated soil column and effect of easily biodegradable primary substrate on their removal.

    PubMed

    Foolad, Mahsa; Ong, Say Leong; Hu, Jiangyong

    2015-11-01

    Pharmaceutical and personal care products (PPCPs) and artificial sweeteners (ASs) are emerging organic contaminants (EOCs) in the aquatic environment. The presence of PPCPs and ASs in water bodies has an ecologic potential risk and health concern. Therefore, it is needed to detect the pollution sources by understanding the transport behavior of sewage molecular markers in a subsurface area. The aim of this study was to evaluate transport of nine selected molecular markers through saturated soil column experiments. The selected sewage molecular markers in this study were six PPCPs including acetaminophen (ACT), carbamazepine (CBZ), caffeine (CF), crotamiton (CTMT), diethyltoluamide (DEET), salicylic acid (SA) and three ASs including acesulfame (ACF), cyclamate (CYC), and saccharine (SAC). Results confirmed that ACF, CBZ, CTMT, CYC and SAC were suitable to be used as sewage molecular markers since they were almost stable against sorption and biodegradation process during soil column experiments. In contrast, transport of ACT, CF and DEET were limited by both sorption and biodegradation processes and 100% removal efficiency was achieved in the biotic column. Moreover, in this study the effect of different acetate concentration (0-100mg/L) as an easily biodegradable primary substrate on a removal of PPCPs and ASs was also studied. Results showed a negative correlation (r(2)>0.75) between the removal of some selected sewage chemical markers including ACF, CF, ACT, CYC, SAC and acetate concentration. CTMT also decreased with the addition of acetate, but increasing acetate concentration did not affect on its removal. CBZ and DEET removal were not dependent on the presence of acetate. PMID:26210019

  8. Enhanced DOC removal using anion and cation ion exchange resins.

    PubMed

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. PMID:26624231

  9. Removal of both cationic and anionic contaminants by amphoteric starch.

    PubMed

    Peng, Huanlong; Zhong, Songxiong; Lin, Qintie; Yao, Xiaosheng; Liang, Zhuoying; Yang, Muqun; Yin, Guangcai; Liu, Qianjun; He, Hongfei

    2016-03-15

    A novel amphoteric starch incorporating quaternary ammonium and phosphate groups was applied to investigate the efficiency and mechanism of cationic and anionic contaminant treatment. Its flocculation abilities for kaolin suspension and copper-containing wastewater were evaluated by turbidity reduction and copper removal efficiency, respectively. And the kinetics of formation, breakage and subsequent re-formation of aggregates were monitored using a Photometric Dispersion Analyzer (PDA) and characterized by flocculation index (FI). The results showed that amphoteric starch possessed the advantages of being lower-dosages-consuming and being stronger in shear resistance than cationic starch, and exhibited a good flocculation efficiency over a wide pH range from 3.0 to 11.0. PMID:26794754

  10. Removal of Microcystis aeruginosa using cationic starch modified soils.

    PubMed

    Shi, Wenqing; Tan, Wanqiao; Wang, Lijing; Pan, Gang

    2016-06-15

    A cheap and biodegradable modifier, cationic starch (CS), was used to turn local soils into effective flocculants for Microcystis aeruginosa (M. aeruginosa) removal. The isoelectric point of soil particles was remarkably increased from pH 0.5 to 11.8 after modification with CS, which made CS modified soil particles positively charged and obtain algal flocculation ability. At the soil concentration of 100 mg/L, when the CS modifier was 10 mg/L, 86% of M. aeruginosa cells were removed within 30 min. Lower or higher CS dosage led to limited algal removal. About 71% and 45% of M. aeruginosa cells were removed within 30 min when CS was 5 mg/L and 80 mg/L, respectively. This is because only part of algal cells combined with CS modified soil particles through charge neutralization at low dosage, while flocs formed at high CS dosage were positively charged which prevents further aggregation among the flocs. The floc stability was quantified by a floc breakage index under applied shear force. Algal flocs formed at acid and alkaline conditions were more prone to be broken than those at the neutral condition. The cost and biodegradability concerns may be largely reduced through the use of CS modified local soils. For field applications, other practical issues (e.g., re-suspension) should be further studied by jointly using other methods. PMID:26143587

  11. Dissolved organic nitrogen removal during water treatment by aluminum sulfate and cationic polymer coagulation.

    PubMed

    Lee, Wontae; Westerhoff, Paul

    2006-12-01

    Coagulation of three surface waters was conducted with aluminum salt and/or cationic polymer to assess dissolved organic nitrogen (DON) removal. Coagulation with aluminum sulfate removed equal or slightly lower amounts of DON as compared to dissolved organic carbon (DOC). At aluminum sulfate dosages up to 5mg per mg DOC, the cationic polymer improved DON removal by an additional 15% to 20% over aluminum sulfate alone. At very high aluminum sulfate dosages (>8 mg aluminum sulfate per mg DOC), however, the cationic polymer addition negligibly increased DON removal. Molecular weight fractionation before and after coagulation experiments indicated that cationic polymer addition can increase the removal of all molecular weight fractions of DON with the highest molecular weight fraction (>10,000 Da) being preferentially removed. Results indicated that the DON added as part of the cationic polymer was almost completely removed at optimum aluminum sulfate and polymer doses. PMID:17023020

  12. REMOVING BARIUM AND RADIUM THROUGH CALCIUM CATION EXCHANGE

    EPA Science Inventory

    The removal of barium (Ba) and radium (Ra), which are found in many groundwater sources, was achieved in laboratory studies with an ion exchange process. In the studies, a strong acid resin in the calcium form effectively removed Ba(+2) and Ra (+2) to meet standards. The resin wa...

  13. Removal of metal cations from water using zeolites

    SciTech Connect

    Zamzow, M.J.; Murphy, J.E. )

    1992-11-01

    Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-four zeolite samples were analyzed by x-ray diffraction and inductively coupled plasma. These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. Bulk densities of a sized fraction ([minus]40, +65 mesh) varied from 0.48 to 0.93 g/ml. Attrition losses ranged from 1 to 18% during an hour-long shake test. The 24 zeolites and an ion-exchange resin were tested for the uptake of Cd, Cu, and Zn. Of the natural zeolites, phillipsite proved to be the most efficient, while the mordenites had the lowest uptakes. Sodium was the most effective exchangeable ion for exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multi-ion wastewater. The metal ions Fe[sup 3+], Cu[sup 2+], and Zn[sup 2+] in the copper mine wastewater were removed to below drinking water standards, but Mn[sup 2+] and Ni[sup 2+] were not. Calcium and NH[sub 4][sup +] interfered with the uptake of heavy metals. Adsorbed heavy metals were eluted from zeolites with a 3% NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.

  14. Electrochemical Removal of Metal Cations from Wastewater Monitored by Differential Pulse Polarography

    ERIC Educational Resources Information Center

    Bruce, Delphine; Kuhn, Alexander; Sojic, Neso

    2004-01-01

    Electrodeposition eliminates wastewater pollutants such as electrochemically active metal cations, with different pulse polarography (DPP) scrutinizing the kinetics of the treatment process. These mechanisms produce qualitative and quantitative data about the removal process, while students appreciate the use of electrochemistry in resolving…

  15. Efficient Removal of Cationic and Anionic Radioactive Pollutants from Water Using Hydrotalcite-Based Getters.

    PubMed

    Bo, Arixin; Sarina, Sarina; Liu, Hongwei; Zheng, Zhanfeng; Xiao, Qi; Gu, Yuantong; Ayoko, Godwin A; Zhu, Huaiyong

    2016-06-29

    Hydrotalcite (HT)-based materials are usually applied to capture anionic pollutants in aqueous solutions. Generally considered anion exchangers, their ability to capture radioactive cations is rarely exploited. In the present work, we explored the ability of pristine and calcined HT getters to effectively capture radioactive cations (Sr(2+) and Ba(2+)) which can be securely stabilized at the getter surface. It is found that calcined HT outperforms its pristine counterpart in cation removal ability. Meanwhile, a novel anion removal mechanism targeting radioactive I(-) is demonstrated. This approach involves HT surface modification with silver species, namely, Ag2CO3 nanoparticles, which can attach firmly on HT surface by forming coherent interface. This HT-based anion getter can be further used to capture I(-) in aqueous solution. The observed I(-) uptake mechanism is distinctly different from the widely reported ion exchange mechanism of HT and much more efficient. As a result of the high local concentrations of precipitants on the getters, radioactive ions in water can be readily immobilized onto the getter surface by forming precipitates. The secured ionic pollutants can be subsequently removed from water by filtration or sedimentation for safe disposal. Overall, these stable, inexpensive getters are the materials of choice for removal of trace ionic pollutants from bulk radioactive liquids, especially during episodic environmental crisis. PMID:27281583

  16. Removal of natural organic matter by cationic hydrogel with magnetic properties.

    PubMed

    Rao, Pinhua; Lo, Irene M C; Yin, Ke; Tang, Samuel C N

    2011-07-01

    Magnetic cationic hydrogel (MCH) was synthesized, and its removal efficiency and mechanisms in regard to natural organic matter (NOM, represented by humic acid and fulvic acid) from the aqueous environment were studied. The effects of time, adsorbent dosage, initial pH, ionic strength, background ions, and NOM types were also investigated. MCH was characterized and found to have a strong magnetic character, yielding an extra advantage for recycling and reuse. Batch studies showed that the removal of Aldrich humic acid (AHA) by MCH was effective. The main mechanism for the removal of NOM is believed to be due to electrostatic interaction. NOM with larger molecular weight tended to be preferentially removed. Solutions with low pH, high ionic strength, and background electrolytes containing calcium, sulfate and bicarbonate were unfavorable for AHA removal. The adsorption-desorption of MCH was evaluated in three cycles, and demonstrated high regeneration rates. PMID:21377262

  17. Effective removal of cationic dyes using carboxylate-functionalized cellulose nanocrystals.

    PubMed

    Qiao, Han; Zhou, Yanmei; Yu, Fang; Wang, Enze; Min, Yinghao; Huang, Qi; Pang, Lanfang; Ma, Tongsen

    2015-12-01

    A novel carboxylate-functionalized adsorbent (CNM) based on cellulose nanocrystals (CNCs) was prepared and adsorptive removal of multiple cationic dyes (crystal violet, methylene blue, malachite green and basic fuchsin) were investigated. The maximum cationic dyes uptakes ranged from 30.0 to 348.9mgg(-1) following the order of: CNM>CNCs>raw cellulose. Furthermore, the removal of crystal violet by CNM was investigated representatively where kinetics, thermodynamics and isotherm analysis were employed to explain in-depth information associated with the adsorption process. The adsorption kinetics fitted well to the pseudo-second-order model and thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic. Meanwhile, isothermal study demonstrated a monolayer adsorption behavior following the Langmuir model with a calculated maximum absorption capacity of 243.9mgg(-1), which is higher than those of many other reported adsorbents. These findings prefigure the promising potentials of CNM as a versatile adsorbent for the efficient removal of cationic dyes from wastewater. PMID:26298027

  18. Nanotubular Halloysite Clay as Efficient Water Filtration System for Removal of Cationic and Anionic Dyes

    NASA Astrophysics Data System (ADS)

    Zhao, Yafei; Abdullayev, Elshad; Lvov, Yuri

    2014-08-01

    Halloysite nanotubes, chemically similar to kaolinite, are formed by rolling of kaolinite layers in tubes with diameter of 50 nm and length of ca. 1 μm. Halloysite has negative SiO2 outermost and positive Al2O3 inner lumen surface, which enables it to be used as potential absorbent for both cationic and anionic dyes due to the efficient bivalent adsorbancy. An adsorption study using cationic Rhodamine 6G and anionic Chrome azurol S has shown approximately two times better dye removal for halloysite as compared to kaolinite. Halloysite filters have been effectively regenerated up to 50 times by burning the adsorbed dyes. Overall removal efficiency of anionic Chrome azurol S exceeded 99.9% for 5th regeneration cycle of halloysite. Chrome azurol S adsorption capacity decreases with the increase of ionic strength, temperature and pH. For cationic Rhodamine 6G, higher ionic strength, temperature and initial solution concentration were favorable to enhanced adsorption with optimal pH 8. These results indicate a potential to utilize halloysite for the removal of ionic dyes from environmental waters.

  19. Gum karaya based hydrogel nanocomposites for the effective removal of cationic dyes from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Mittal, Hemant; Maity, Arjun; Ray, Suprakas Sinha

    2016-02-01

    Biodegradable hydrogel nanocomposites (HNC) of gum karaya (GK) grafted with poly(acrylic acid) (PAA) incorporated silicon carbide nanoparticles (SiC NPs) were synthesized using the in situ graft copolymerization method and tested for the adsorption of cationic dyes from aqueous solution. The structure and morphology of the HNC were characterized using different spectroscopic and microscopic techniques. The results showed that the surface area and porosity of the hydrogel polymer significantly increased after nanocomposite formation with SiC NPs. The HNC was employed for the removal of cationic dyes, i.e., malachite green (MG) and rhodamine B (RhB) from the aqueous solution. The HNC was found to remove 91% (MG) and 86% (RhB) of dyes with a polymer dose of 0.5 and 0.6 g l-1 in neutral medium, respectively. The adsorption process was found to be highly pH dependent and followed the pseudo-second-order rate model. The adsorption isotherm data fitted well with the Langmuir adsorption isotherm with a maximum adsorption capacity of 757.57 and 497.51 mg g-1 for MG and RhB, respectively. Furthermore, the HNC was demonstrated as a versatile adsorbent for the removal of both cationic and anionic dyes from the simulated wastewater. The HNC showed excellent regeneration capacity and was successfully used for the three cycles of adsorption-desorption. In summary, the HNC has shown its potential as an environment friendly and efficient adsorbent for the adsorption of cationic dyes from contaminated water.

  20. Bentonite modification with hexadecylpyridinium and aluminum polyoxy cations and its effectiveness in Se(IV) removal.

    PubMed

    Orucoglu, Esra; Haciyakupoglu, Sevilay

    2015-09-01

    Usage of bentonite as a buffer material is suggested in radioactive waste repositories. Although bentonites have higher sorption ability to cations, they cannot adsorp anions due to negative surface charge. Nowadays, ongoing researches focus on increasing anion adsorption ability of the bentonites with modification. Organic-pillared bentonite (OPBent) was produced by modification of sodium bentonite with aluminum polyoxy and hexadecylpyridinium cations in this study. Variation in structure after modification was demonstrated by using different characterization techniques. Se removal efficiency of OPBent is investigated by using (75)Se, since selenium (Se) is one of the important long lived fission products found in radioactive waste and has toxic anionic species in an aqueous environment. The effect of reaction time, solid/liquid ratio, pH and concentration on the adsorption performance were examined. Se speciation and its effect onto adsorption were also investigated by measuring Eh-pH values under certain experimental conditions. Additionally, importance of the amount of Al-polyoxy cations used in modification was investigated by comparing these results with the results of other organic-pillared bentonite produced in our previous research. Experimental results confirmed that both cations were successfully placed into the bentonite interlayer and significant change in the host structure leads to increase Se adsorption. Consequently, bentonite modification improves its Se adsorption ability and further investigations are needed related to the usage of this adsorbent in other remediation studies especially in sorption of other anionic pollutants. PMID:26081306

  1. Effect of Divalent Cation Removal on the Structure of Gram-Negative Bacterial Outer Membrane Models

    DOE PAGESBeta

    Clifton, Luke A.; Skoda, Maximilian W. A.; Le Brun, Anton P.; Ciesielski, Filip; Kuzmenko, Ivan; Holt, Stephen A.; Lakey, Jeremy H.

    2014-12-09

    The Gram-negative bacterial outer membrane (GNB-OM) is asymmetric in its lipid composition with a phospholipid-rich inner leaflet and an outer leaflet predominantly composed of lipopolysaccharides (LPS). LPS are polyanionic molecules, with numerous phosphate groups present in the lipid A and core oligosaccharide regions. The repulsive forces due to accumulation of the negative charges are screened and bridged by the divalent cations (Mg2+ and Ca2+) that are known to be crucial for the integrity of the bacterial OM. Indeed, chelation of divalent cations is a well-established method to permeabilize Gram-negative bacteria such as Escherichia coli. Here, we use X-ray and neutronmore » reflectivity (XRR and NR, respectively) techniques to examine the role of calcium ions in the stability of a model GNB-OM. Using XRR we show that Ca2+ binds to the core region of the rough mutant LPS (RaLPS) films, producing more ordered structures in comparison to divalent cation free monolayers. Using recently developed solid-supported models of the GNB-OM, we study the effect of calcium removal on the asymmetry of DPPC:RaLPS bilayers. We show that without the charge screening effect of divalent cations, the LPS is forced to overcome the thermodynamically unfavorable energy barrier and flip across the hydrophobic bilayer to minimize the repulsive electrostatic forces, resulting in about 20% mixing of LPS and DPPC between the inner and outer bilayer leaflets. These results reveal for the first time the molecular details behind the well-known mechanism of outer membrane stabilization by divalent cations. This confirms the relevance of the asymmetric models for future studies of outer membrane stability and antibiotic penetration.« less

  2. Effect of Divalent Cation Removal on the Structure of Gram-Negative Bacterial Outer Membrane Models

    SciTech Connect

    Clifton, Luke A.; Skoda, Maximilian W. A.; Le Brun, Anton P.; Ciesielski, Filip; Kuzmenko, Ivan; Holt, Stephen A.; Lakey, Jeremy H.

    2014-12-09

    The Gram-negative bacterial outer membrane (GNB-OM) is asymmetric in its lipid composition with a phospholipid-rich inner leaflet and an outer leaflet predominantly composed of lipopolysaccharides (LPS). LPS are polyanionic molecules, with numerous phosphate groups present in the lipid A and core oligosaccharide regions. The repulsive forces due to accumulation of the negative charges are screened and bridged by the divalent cations (Mg2+ and Ca2+) that are known to be crucial for the integrity of the bacterial OM. Indeed, chelation of divalent cations is a well-established method to permeabilize Gram-negative bacteria such as Escherichia coli. Here, we use X-ray and neutron reflectivity (XRR and NR, respectively) techniques to examine the role of calcium ions in the stability of a model GNB-OM. Using XRR we show that Ca2+ binds to the core region of the rough mutant LPS (RaLPS) films, producing more ordered structures in comparison to divalent cation free monolayers. Using recently developed solid-supported models of the GNB-OM, we study the effect of calcium removal on the asymmetry of DPPC:RaLPS bilayers. We show that without the charge screening effect of divalent cations, the LPS is forced to overcome the thermodynamically unfavorable energy barrier and flip across the hydrophobic bilayer to minimize the repulsive electrostatic forces, resulting in about 20% mixing of LPS and DPPC between the inner and outer bilayer leaflets. These results reveal for the first time the molecular details behind the well-known mechanism of outer membrane stabilization by divalent cations. This confirms the relevance of the asymmetric models for future studies of outer membrane stability and antibiotic penetration.

  3. Effect of Divalent Cation Removal on the Structure of Gram-Negative Bacterial Outer Membrane Models

    PubMed Central

    2014-01-01

    The Gram-negative bacterial outer membrane (GNB-OM) is asymmetric in its lipid composition with a phospholipid-rich inner leaflet and an outer leaflet predominantly composed of lipopolysaccharides (LPS). LPS are polyanionic molecules, with numerous phosphate groups present in the lipid A and core oligosaccharide regions. The repulsive forces due to accumulation of the negative charges are screened and bridged by the divalent cations (Mg2+ and Ca2+) that are known to be crucial for the integrity of the bacterial OM. Indeed, chelation of divalent cations is a well-established method to permeabilize Gram-negative bacteria such as Escherichia coli. Here, we use X-ray and neutron reflectivity (XRR and NR, respectively) techniques to examine the role of calcium ions in the stability of a model GNB-OM. Using XRR we show that Ca2+ binds to the core region of the rough mutant LPS (RaLPS) films, producing more ordered structures in comparison to divalent cation free monolayers. Using recently developed solid-supported models of the GNB-OM, we study the effect of calcium removal on the asymmetry of DPPC:RaLPS bilayers. We show that without the charge screening effect of divalent cations, the LPS is forced to overcome the thermodynamically unfavorable energy barrier and flip across the hydrophobic bilayer to minimize the repulsive electrostatic forces, resulting in about 20% mixing of LPS and DPPC between the inner and outer bilayer leaflets. These results reveal for the first time the molecular details behind the well-known mechanism of outer membrane stabilization by divalent cations. This confirms the relevance of the asymmetric models for future studies of outer membrane stability and antibiotic penetration. PMID:25489959

  4. A new efficient forest biowaste as biosorbent for removal of cationic heavy metals.

    PubMed

    Kim, Namgyu; Park, Munsik; Park, Donghee

    2014-10-25

    Among various forest biowastes, chestnut bur had the highest uptake values of Cd(II) and Pb(II), and these values were higher than those of agricultural biowastes used as comparable biosorbents. This study is the first report showing the high potential of chestnut bur as biosorbent for the removal of cationic heavy metals. Pseudo-second-order equation satisfactorily described the biosorption behaviors of both metals. Biosorption rate of Pb(II) was 3.12 times higher than that of Cd(II). Langmuir model could fit the equilibrium isotherm data better than Freundlich model. The maximum uptake capacities of Cd(II) and Pb(II) were determined to be 34.77mg/g and 74.35mg/g, respectively. FTIR study showed that carboxyl group on the biosorbent was involved in biosorbing the cationic metals. In conclusion, abundant and cheap forest biowastes, especially chestnut bur, is a potent candidate for efficient biosorbent capable of removing toxic heavy metals from aqueous solutions. PMID:25467000

  5. Fast removal of high quantities of toxic arsenate via cationic p(APTMACl) microgels.

    PubMed

    Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Aktas, Nahit; Sahiner, Mehtap; Demirci, Sahin; Sahiner, Nurettin

    2016-01-15

    Hydrogels are resourceful materials and can be prepared in different morphology, size, surface charge and porosity adopting different polymerization techniques and reaction conditions. The cationic poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)) microgels were synthesized by photo-initiated inverse suspension polymerization technique. These microgels were utilized as absorbents for the removal of toxic arsenate (As) from different aqueous environments. The experimental parameters affecting absorption efficiency were investigated, and it was demonstrated that these types of microgels are highly efficient in removing arsenate anions from different aqueous environments compared to the previously reported bulk hydrogel, and cryogel of the same material. A removal efficiency of approximately 97.25% was obtained by immersing 0.5 g microgel in 250 ppm 100 mL solution of arsenate anions for 60 min. Both Langmuir and Freundlich adsorption isotherms were applied to adsorption of arsenate anions by p(APTMACl) microgels, and the Langmuir isotherm was a better representation of the adsorption of arsenate with a high value of R(2) (0.9982). Furthermore, mag-p(APTMACl) microgels were synthesized for the adsorption of arsenate anions to provide easy removal of the microgel composite by using an externally applied magnetic field. Furthermore, re-usability of the p(APTMACl) microgels was also investigated for the adsorption of arsenate anions. PMID:26513320

  6. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    DOEpatents

    Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

    2013-08-13

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  7. Easily-wired toggle switch

    NASA Technical Reports Server (NTRS)

    Dean, W. T.; Stringer, E. J.

    1979-01-01

    Crimp-type connectors reduce assembly and disassembly time. With design, no switch preparation is necessary and socket contracts are crimped to wires inserted in module attached to back of toggle switch engaging pins inside module to make electrical connections. Wires are easily removed with standard detachment tool. Design can accommodate wires of any gage and as many terminals can be placed on switch as wire gage and switch dimensions will allow.

  8. Nitrogen removal from wastewater through microbial electrolysis cells and cation exchange membrane

    PubMed Central

    2014-01-01

    Vulnerability of water resources to nutrients led to progressively stricter standards for wastewater effluents. Modification of the conventional procedures to meet the new standards is inevitable. New technologies should give a priority to nitrogen removal. In this paper, ammonium chloride and urine as nitrogen sources were used to investigate the capacity of a microbial electrolysis cell (MEC) configured by cation exchange membrane (CEM) for electrochemical removal of nitrogen over open-and closed-circuit potentials (OCP and CCP) during biodegradation of organic matter. Results obtained from this study indicated that CEM was permeable to both organic and ammonium nitrogen over OCP. Power substantially mediated ammonium migration from anodic wastewater to the cathode, as well. With a urine rich wastewater in the anode, the maximum rate of ammonium intake into the cathode varied from 34.2 to 40.6 mg/L.h over CCP compared to 10.5-14.9 mg/L.h over OCP. Ammonium separation over CCP was directly related to current. For 1.46-2.12 mmol electron produced, 20.5-29.7 mg-N ammonium was removed. Current also increased cathodic pH up to 12, a desirable pH for changing ammonium ion to ammonia gas. Results emphasized the potential for MEC in control of ammonium through ammonium separation and ammonia volatilization provided that membrane characteristic is considered in their development. PMID:24533446

  9. Use of grape seed and its natural polyphenol extracts as a natural organic coagulant for removal of cationic dyes.

    PubMed

    Jeon, Jong-Rok; Kim, Eun-Ju; Kim, Young-Mo; Murugesan, Kumarasamy; Kim, Jae-Hwan; Chang, Yoon-Seok

    2009-11-01

    Natural organic coagulants (NOCs) such as chitosan and Moringa oleifera seeds have been extensively characterized for potential application in water treatment as an alternative to metal-based coagulants. However, the action of both chitosan and M. oleifera seeds is mainly restricted to anionic organic pollutants because of their cationic functional groups affording poor cationic pollutant coagulation by electrostatic repulsion. In this study, we employed ethanolic grape seed extract (GSE) and grape seed-derived polyphenols such as tannic acid and catechin in an effort to find novel NOCs showing stable anionic forms for removal of cationic organic pollutants. The target substances tested were malachite green (MG) and crystal violet (CV), both mutagenic cationic dyes. Polyphenol treatment induced fast decolorization followed by gradual floc formation concomitant with red or blue shifts in maximum absorbance wavelengths of the cationic dyes. Liquid chromatography analysis of flocs formed by polyphenols directly showed that initial supramolecular complexes attributed mainly to electrostatic attraction between polyphenol hydroxyphenyl groups and cationic dyes further progressed into stronger aggregates, leading to precipitation of dye-polyphenol complexes. Consistent with the results obtained using catechin and tannic acid, use of GSE also resulted in effective decolorization and coagulation of soluble MG and CV in aqueous solutions. Screening of several organic GSE components for NOC activity strongly suggested that natural polyphenols are the main organic ingredients causing MG and CV removal via gradual floc formation. The treatment by natural polyphenols and GSE decreased toxicity of MG- or CV-contaminated water. PMID:19786292

  10. Removal of cationic heavy metal from aqueous solution by activated carbon impregnated with anionic surfactants.

    PubMed

    Ahn, Chi K; Park, Donghee; Woo, Seung H; Park, Jong M

    2009-05-30

    To increase their capacity to adsorb heavy metals, activated carbons were impregnated with the anionic surfactants sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), or dioctyl sulfosuccinate sodium (DSS). Surfactant-impregnated activated carbons removed Cd(II) at up to 0.198 mmol g(-1), which was more than an order of magnitude better than the Cd(II) removal performance of activated carbon without surfactant (i.e., 0.016 mmol g(-1)) even at optimal pH (i.e., pH 6). The capacity of the activated carbon to adsorb Cd(II) increased in proportion to the quantity of surfactant with which they were impregnated. The kinetics of the adsorption of Cd(II) onto the surfactant-impregnated activated carbon was best described by a pseudo-second-order model, and was described better by the Freundlich adsorption isotherm than by the Langmuir isotherm. The surface charge of activated carbon was negative in all pH ranges tested (2-6). These results indicate that surface modification with anionic surfactant could be used to significantly enhance the capacity of activated carbon to adsorb cations. PMID:19022570

  11. The removal of stickies with modified starch and chitosan--highly cationic and hydrophobic types compared with unmodified ones.

    PubMed

    Petzold, Gudrun; Petzold-Welcke, Katrin; Qi, Haisong; Stengel, Knut; Schwarz, Simona; Heinze, Thomas

    2012-11-01

    The removal of dissolved and colloidal substances (DCS) in paper cycling water, so called stickies, with tailored natural polymers, having cationic as well as hydrophobic groups, was investigated using model suspensions made by the recycling of paper. The sticky content, characterized by the turbidity, the anionic charge, and the total organic carbon content (TOC) was increased by the addition of latex. The dynamic surface tension was established as useful tool for the characterization of the sticky content. The sticky removal using the starch derivatives (with benzyl- as well as ethyl-substituents), from very low up to high cationic charge and N-(benzyl)chitosan was compared. Depending on the properties of the derivatives two possible mechanisms can be found: "charge dominated removal" or "removal dominated by hydrophobicity." It seems that turbidity and TOC are lowered especially due to charge interaction whereas the increase of the surface tension is mainly caused by the hydrophobic character of the modified natural polymers. PMID:22944437

  12. Functionalization of cubic mesoporous silica SBA-16 with carboxylic acid via one-pot synthesis route for effective removal of cationic dyes.

    PubMed

    Tsai, Cheng-Hsun; Chang, Wei-Chieh; Saikia, Diganta; Wu, Cheng-En; Kao, Hsien-Ming

    2016-05-15

    In this work, we demonstrate that a high density of −COOH groups loading, up to 60 mol% based on silica, is successfully incorporated into SBA-16 via a one-pot synthesis route, which involves co-condensation of carboxyethylsilanetriol sodium salt (CES) and tetraethylorthosilicate (TEOS) templated by Pluronic F127 and P123 in an acidic medium. A variety of characterization techniques are performed to confirm quantitative incorporation of carboxylic groups into ordered cubic mesostructures. These functionalized materials are used to effectively remove two cationic dyes methylene blue (MB) and phenosafranine (PF) with the maximum adsorption capacities of 561 and 519 mg g(-1), respectively, at pH 9. The zeta potential results reveal that the electrostatic interactions between cationic dye molecule and negatively charged surface of the adsorbent play a crucial role in their high adsorption capacities. For a binary component system consisting of MB and PF, competitive adsorption of these two dyes is observed with adsorption capacity values slightly lower than those of the corresponding single dye systems. The dye adsorbed material can be easily regenerated by simple acid washing and be reused for five times with MB removal efficiency still up to 98.6%, showing its great potentials in environmental remediation. PMID:26906434

  13. Phosphate removal and recovery from water using nanocomposite of immobilized magnetite nanoparticles on cationic polymer.

    PubMed

    Abo Markeb, Ahmad; Alonso, Amanda; Dorado, Antonio David; Sánchez, Antoni; Font, Xavier

    2016-08-01

    A novel nanocomposite (NC) based on magnetite nanoparticles (Fe3O4-NPs) immobilized on the surface of a cationic exchange polymer, C100, using a modification of the co-precipitation method was developed to obtain magnetic NCs for phosphate removal and recovery from water. High-resolution transmission electron microscopy-energy-dispersive spectroscopy, scanning electron microscopy , X-ray diffraction, and inductively coupled plasma optical emission spectrometry were used to characterize the NCs. Continuous adsorption process by the so-called breakthrough curves was used to determine the adsorption capacity of the Fe3O4-based NC. The adsorption capacity conditions were studied under different conditions (pH, phosphate concentration, and concentration of nanoparticles). The optimum concentration of iron in the NC for phosphate removal was 23.59 mgFe/gNC. The sorption isotherms of this material were performed at pH 5 and 7. Taking into account the real application of this novel material in real water, the experiments were performed at pH 7, achieving an adsorption capacity higher than 4.9 mgPO4-P/gNC. Moreover, Freundlich, Langmuir, and a combination of them fit the experimental data and were used for interpreting the influence of pH on the sorption and the adsorption mechanism for this novel material. Furthermore, regeneration and reusability of the NC were tested, obtaining 97.5% recovery of phosphate for the first cycle, and at least seven cycles of adsorption-desorption were carried out with more than 40% of recovery. Thus, this work described a novel magnetic nanoadsorbent with properties for phosphate recovery in wastewater. PMID:26849360

  14. Characterization and adsorption properties of a lanthanum-loaded magnetic cationic hydrogel composite for fluoride removal.

    PubMed

    Dong, Shuoxun; Wang, Yili

    2016-01-01

    In this study, a novel lanthanum-loaded magnetic cationic hydrogel (MCH-La) was synthesized for fluoride adsorption from drinking water. The adsorption kinetics, isotherms, and effects of pH and co-existing anions on fluoride uptake by MCH-La were evaluated. FTIR, Raman and XPS were used to analyze the fluoride adsorption mechanism of MCH-La. Results showed that MCH-La had positive zeta potential values of 23.6-8.0 mV at pH 3.0-11.0, with the magnitude of saturation magnetization up to 10.3 emu/g. The fluoride adsorption kinetics by MCH-La fitted well with the fractal-like-pseudo-second-order model, and the adsorption capacity reached 93% of the ultimate adsorption capacity within the first 10 min. The maximum fluoride adsorption capacity for MCH-La was 136.78 mg F(-)/g at an equilibrium fluoride concentration of 29.3 mg/L and pH 7.0. Equilibrium adsorption data showed that the Sips model was more suitable than the Langmuir and Freundlich models. MCH-La still had more than 100 mg of F(-)/g adsorption capacity at a strongly alkaline solution (pH > 10). The adsorption process was highly pH-dependent, and the optimal adsorption was attained at pH 2.8-4.0, corresponding to ligand exchange, electrostatic interactions, and Lewis acid-base interactions. With the exception of both anions of HCO3(-) and SiO4(4-), Cl(-), NO3(-), and SO4(2-) did not evidently prevent fluoride removal by MCH-La at their real concentrations in natural groundwater. The fluoride adsorption capacity of the regenerated MCH-La approached 70% of the fresh MCH-La from the second to fifth recycles. FTIR and Raman spectra revealed that C-O and CO functional groups on MCH contributed to the fluoride adsorption, this finding was also confirmed by the XPS F 1s spectra. Deconvolution of C 1s spectra before and after fluoride adsorption indicated that the carboxyl, anhydride, and phenol groups of MCH were involved in the fluoride removal. PMID:26613180

  15. Effects of electrokinetics and cationic surfactant cetyltrimethylammonium bromide [CTAB] on the hydrocarbon removal and retention from contaminated soils.

    PubMed

    Ranjan, R Sri; Qian, Y; Krishnapillai, M

    2006-07-01

    Hydrocarbon contaminated soil and groundwater is considered to be a leading cause for increased health risk and environmental contamination. Therefore, an efficient technique is needed to retard the movement or enhance the removal of the contaminant depending on the remediation objective. The goals of this study were to evaluate the impact of the addition of a cationic surfactant on the movement of hydrocarbons within a contaminated clay soil subjected to electrokinetic treatment. Water-flushing and surfactant-flushing experiments were conducted on one-dimensional soil columns. The model diesel fuel was composed of a mixture of benzene, toluene, ethylbenzene, xylenes [BTEX] and three selected polycyclic hydrocarbons [PAHs]. In the water-flushing experiments, the application of an electrokinetic treatment was found to enhance the removal of PAHs from the clay columns by about 20%. In contrast, the application of an electrokinetic treatment, when coupled with cationic surfactant-flushing, retarded the movement of BTEX and the three selected PAHs in the clay columns. Hydraulic columns with surfactant (CTAB) removed 17% more naphthalene and 11% more 2-methylnaphthalene compared to columns subjected to electrokinetic treatment with CTAB. The flux through the electrokinetic columns during water flushing as well as surfactant flushing was higher than the flux due to hydraulic gradient alone. As the solubility of hydrocarbons increased, they moved farther with electrokinetic treatment without CTAB. However, with CTAB the electrokinetic treatment tends to retard the movement. Use of a cationic surfactant coupled with electrokinetic treatment was found to retard the movement of contaminants. PMID:16894821

  16. Removal of chromium from Cr(VI) polluted wastewaters by reduction with scrap iron and subsequent precipitation of resulted cations.

    PubMed

    Gheju, M; Balcu, I

    2011-11-30

    This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH. PMID:21955659

  17. NDTB-1: A Supertetrahedral Cationic Framework That Removes TcO4- from Solution

    SciTech Connect

    Wang, Shuao; Alekseev, Evgeny V.; Casey, William H.; Phillips, Brian L.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.

    2010-02-01

    A cubic thorium borate possesses a porous supertetrahedral cationic framework with extraframework borate anions. These anions are readily exchanged with a variety of environmental contaminants, especially those from the nuclear industry, including chromate and pertechnetate.

  18. Synthesis of magnetite-porphyrin nanocomposite and its application as a novel magnetic adsorbent for removing heavy cations

    SciTech Connect

    Bakhshayesh, Sara Dehghani, Hossein

    2013-07-15

    Graphical abstract: Magnetite-porphyrin nanocomposite (MPNC) as a novel magnetic adsorbent for removing heavy cations was synthesized. - Highlights: • Nanosized Fe{sub 3}O{sub 4} was prepared by hydrothermal reaction of iron salt in alkaline media. • The synthesized magnetite and nanocomposite had soft ferromagnetic property. • Magnetic nanocomposite as a novel magnetic adsorbent for heavy cations was prepared. • Satisfactory separation from solutions in the order of Pb{sup 2+} > Cd{sup 2+} > Hg{sup 2+} was obtained. - Abstract: Magnetite-porphyrin nanocomposite (MPNC) was synthesized as a novel magnetic adsorbent for removing heavy cations. Firstly, we prepared nano-sized magnetite using a simple hydrothermal route. The synthesis of nanoscaled magnetite was carried out through reaction between iron source and various amines. In this paper, we studied effective parameters in controlling shape and size of nanoscaled magnetite. These parameters were presence of alkaline, reaction time, kind of amine and iron salt. Morphology, particle size and magnetic properties of the nanoscaled magnetite were obtained by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), diffuse reflectance spectra (DRS) and vibrating sample magnetometer (VSM). Our study showed that the synthesized magnetite from reaction between FeSO{sub 4} and hydrazinum hydrate has spherical shape. The synthesized magnetite was a nanosized compound and used for preparation of magnetite-porphyrin nanocomposite. The synthesized magnetite-porphyrin hybrid material had magnetic property and was used as magnetic adsorbent for removing heavy cations of water. Satisfactory separation from solutions in the order of Pb{sup 2+} > Cd{sup 2+} > Hg{sup 2+} was obtained.

  19. Modelling Mixed Bed Ion Exchange Kinetics for Removal of Trace Levels of Divalent Cations in Ultrapure Water

    SciTech Connect

    B. Widman

    2003-01-01

    Ion exchanger resin fluid film mass transfer coefficients and the ionic diffusivities from which they are derived are often measured by use of ion exchange resin columns. Such tests, usually run dynamically using short resin beds, are often performed using relatively high (ppm) concentrations of ions to accurately measure output concentrations as a function of flow rate. The testing described herein was performed to determine fluid film ionic diffusivities for cationic concentrations typical of ultrapure water ({le}ppb levels) containing ppm levels of ammonia. Effective ionic diffusivities at these low ionic concentrations and high pHs were needed to complete a computer model (SIMIX) to be used in ion exchange simulations. SIMIX is a generalized multicomponent ion exchange model designed to simulate the removal of divalent cations from ultrapure water.

  20. Water soluble/dispersible and easy removable cationic adhesives and coating for paper recycling

    DOEpatents

    Deng, Yulin; Yan, Zegui

    2005-11-29

    The present invention is an adhesive or coating composition that is dispersible or dissolvable in water, making it useful in as a coating or adhesive in paper intended for recycling. The composition of the present invention is cationically charged thereby binding with the fibers of the paper slurry and thus, resulting in reduced deposition of adhesives on equipment during the recycling process. The presence of the composition of the present invention results in stronger interfiber bonding in products produced from the recycled fibers.

  1. Nitrogen and chemical oxygen demand removal from septic tank wastewater in subsurface flow constructed wetlands: substrate (cation exchange capacity) effects.

    PubMed

    Collison, Robert S; Grismer, Mark E

    2014-04-01

    The current article focuses on chemical oxygen demand (COD) and nitrogen (ammonium and nitrate) removal performance from synthetic human wastewater as affected by different substrate rocks having a range of porosities and cation exchange capacities (CECs). The aggregates included lava rock, lightweight expanded shale, meta-basalt (control), and zeolite. The first three had CECs of 1 to 4 mequiv/100 gm, whereas the zeolite CEC was much greater (-80 mequiv/100 gm). Synthetic wastewater was gravity fed to each constructed wetland system, resulting in a 4-day retention time. Effluent samples were collected, and COD and nitrogen species concentrations measured regularly during four time periods from November 2008 through June 2009. Chemical oxygen demand and nitrogen removal fractions were not significantly different between the field and laboratory constructed wetland systems when corrected for temperature. Similarly, overall COD and nitrogen removal fractions were practically the same for the aggregate substrates. The important difference between aggregate effects was the zeolite's ammonia removal process, which was primarily by adsorption. The resulting single-stage nitrogen removal process may be an alternative to nitrification and denitrification that may realize significant cost savings in practice. PMID:24851327

  2. Electronic modules easily separated from heat sink

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Metal heat sink and electronic modules bonded to a thermal bridge can be easily cleaved for removal of the modules for replacement or repair. A thin film of grease between a fluorocarbon polymer film on the metal heat sink and an adhesive film on the modules acts as the cleavage plane.

  3. In vitro adsorption removal of paraquat by activated carbon and cation exchange resin

    SciTech Connect

    Kitakouji, M.; Miyoshi, T.; Tanada, M.S.; Nakamura, T. )

    1989-06-01

    With the modernization of agriculture, environmental pollution and accidental poisoning by agricultural chemicals have become a great social problem. With the remarkable increase in the amount of paraquat used, the number of deaths by swallowing of paraquat has also increased in recent years. Presently, an effective antidote and treatment for paraquat poisoning is not available. For primary treatment, administration of an adsorbent is done at the same time as gastrointestinal lavage. As an adsorbent for paraquat poisoning, the efficacy of activated carbon, Fuller's Earth, bentonite, and a cation exchange resin have been reported. In this work, the authors discuss the adsorption characteristics of paraquat in artificial gastric juice and normal saline solution.

  4. Arsenite and arsenate removal from wastewater using cationic polymer-modified waste tyre rubber.

    PubMed

    Imyim, Apichat; Sirithaweesit, Thitayati; Ruangpornvisuti, Vithaya

    2016-01-15

    Waste tyre rubber (WTR) granulate was modified with a cationic polymer, poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)). The resulting WTR/p(APTMACl) was utilized for the adsorption of arsenite, As(III) and arsenate, As(V) from aqueous medium in both batch and column methods. The level of adsorption increased gradually with increasing monomer concentration and contact time. The adsorption behavior obeyed the Freundlich model, and the rate of adsorption could be predicted by employing the pseudo-second order model. In the column method, As(V) could be adsorbed onto the sorbent more effectively than As(III). Remarkable desorption of As(III) and As(V) (99 and 92%, respectively) from the adsorbent was achieved using 0.10 M HCl as eluent. An approach of evaluation of adsorption capacity uncertainty is proposed. PMID:26607568

  5. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media

    NASA Astrophysics Data System (ADS)

    Starukh, G.; Rozovik, O.; Oranska, O.

    2016-04-01

    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied.

  6. Microbially-Mediated Subsurface Calcite Precipitation for Removal of Hazardous Divalent Cations

    SciTech Connect

    Colwell, Frederick S.; Smith, R.W.; Ferris, F. Gratn; Ingram, Jani C.; Reysenbach, A.-L.; Fujita, Yoshiko; Tyler, T.L.; Taylor, J.L.; Banta, A.; Delwiche, M.E.; McLing, T.; Cortez, Marnie, M.; Watwood, M.E.

    2003-03-27

    We are investigating microbially-mediated acceleration of calcite precipitation and co-precipitation of hazardous divalent cations (e.g., 90Sr) in calcite saturated subsurface systems. In theory, the addition of urea to an aquifer or vadose zone and its subsequent hydrolysis by indigenous microbes will cause an increase in alkalinity, pH and calcite precipitation. Lab studies indicated the ability of various bacteria to precipitate calcite through urea hydrolysis and that incorporation of strontium in biogenically-formed calcite is greater than in abiotically formed calcite. Results from a field experiment in a pristine location in the Snake River Plain aquifer involving the phased addition of molasses and then urea showed increases in total cell numbers, rate of urea hydrolysis and calcite formation during the study. The combined diagnostic approaches of microbiology, molecular ecology and analytical chemistry demonstrate the feasibility of this biogeochemical manipulation for subsurface remediation at arid Western DOE sites such as Hanford and INEEL.

  7. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media.

    PubMed

    Starukh, G; Rozovik, O; Oranska, O

    2016-12-01

    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied. PMID:27119156

  8. Two Easily Made Astronomical Telescopes.

    ERIC Educational Resources Information Center

    Hill, M.; Jacobs, D. J.

    1991-01-01

    The directions and diagrams for making a reflecting telescope and a refracting telescope are presented. These telescopes can be made by students out of plumbing parts and easily obtainable, inexpensive, optical components. (KR)

  9. Equilibrium analysis for heavy metal cation removal using cement kiln dust.

    PubMed

    El Zayat, Mohamed; Elagroudy, Sherien; El Haggar, Salah

    2014-01-01

    Ion exchange, reverse osmosis, and chemical precipitation have been investigated extensively for heavy metal uptake. However, they are deemed too expensive to meet stringent effluent characteristics. In this study, cement kiln dust (CKD) was examined for the removal of target heavy metals. Adsorption studies in completely mixed batch reactors were used to generate equilibrium pH adsorption edges. Studies showed the ability of CKD to remove the target heavy metals in a pH range below that of precipitation after an equilibrium reaction time of 24 h. A surface titration experiment indicated negative surface charge of the CKD at pH below 10, meaning that electrostatic attraction of the divalent metals can occur below the pH required for precipitation. However, surface complexation was also important due to the substantive metal removal. Accordingly, a surface complexation model approach that utilizes an electrostatic term in the double-layer description was used to estimate equilibrium constants for the protolysis interactions of the CKD surface as well as equilibria between background ions and the sorbent surface. It was concluded that the removal strength of adsorption is in the order: Pb > Cu > Cd. The experiments were also supported by Fourier transform infrared spectroscopy (FTIR). PMID:25259489

  10. Comparing Nafion and ceramic separators used in electrochemical purification of spent chromium plating solutions: cationic impurity removal and transport.

    PubMed

    Huang, Kuo-Lin; Holsen, Thomas M; Chou, Tse-Chuan; Selman, J Robert

    2003-05-01

    This study focuses on the electrolytic regeneration of spent chromium plating solutions. These solutions contain a significant amount of chromium and a lesser amount of other heavy metals, which makes them a significant environmental concern and an obvious target for recycling and reuse. The type of separator used is extremely critical to the performance of the process because they are the major resistance in the transport-related impurity (Cu(II), Ni(II), and Fe(III)) removals from contaminated chromic acid solutions. A Nafion 117 membrane and a ceramic diaphragm separator traditionally used in the industry were tested for comparison. It was found that the mobilities of Cu(II) and Ni(II) were similar and higher than that of Fe(III) using both separators. The mobility of each cation was smaller in the Nafion membrane than in the ceramic diaphragm. The measured conductivity of the ceramic diaphragm was slightly higher than that of Nafion membrane. However, the Nafion membrane was much thinner than the ceramic diaphragm resulting in the system using the Nafion membrane having higher impurity removal rates than the system using the ceramic diaphragm. The removal rates were approximately equal for Cu(II) and Ni(II) and lowest for Fe(III). Both current and initial concentration affected the removal rates of the impurities. Modeling results indicated that a system using a Nafion separator and a small catholyte/anolyte volume ratio was better than a system using a ceramic separator for removing impurities from concentrated plating solutions if the impurities transported into the catholyte are deposited or precipitated. PMID:12775076

  11. Synthesized layered inorganic-organic magnesium organosilicate containing a disulfide moiety as a promising sorbent for cations removal.

    PubMed

    Moscofian, Andrea S O; Airoldi, Claudio

    2008-12-15

    A new-layered inorganic-organic magnesium organosilicate was synthesized through a single step template sol-gel route under mild conditions, using a new alkoxysilane, containing a 2-aminophenyldisulfide molecule. Elemental analysis data based on the nitrogen atom showed an incorporation of 1.97mmol of organic pendant groups for each gram of the hybrid formed. The X-ray diffraction patterns demonstrated that this nanocompound exhibited lamellar structure, in agreement with that found for natural inorganic silicates. Infrared spectroscopy and nuclear magnetic resonance for the (29)Si nucleus in the solid state are in agreement with the success of the proposed synthetic method. The presence of nitrogen and sulfur basic centers attached to the pendant groups inside the lamellar structure is used as basic centers to coordinate cations from aqueous solution at the solid/liquid interface. The isotherms were fitted to Langmuir and Freundlich models. The maxima adsorption capacities for copper, lead and cadmium, calculated from Langmuir model, were 3.28, 1.42 and 0.35mmol g(-1), respectively. These values are comparable to other adsorbing nanomaterials. This behavior suggested that this new inorganic-organic hybrid could be employed as a promising adsorbent for cation removal from polluted systems. PMID:18395976

  12. Quince seed mucilage magnetic nanocomposites as novel bioadsorbents for efficient removal of cationic dyes from aqueous solutions.

    PubMed

    Hosseinzadeh, Hossein; Mohammadi, Sina

    2015-12-10

    This study investigated the potential use of quince seed mucilage (QSM) as alternative bioadsorbents for methylene blue (MB) dye from aqueous solutions. This novel magnetic nanocomposite adsorbent (MNCA) based on QSM was synthesized by in situ formation of magnetic iron oxide nanoparticles into QSM solution. The MNCAs were characterized using FTIR, SEM, TEM, XRD, and VSM. Removal of MB was investigated by batch adsorption technique. The thermodynamic parameters suggest that the dye adsorption process is spontaneous and exothermic in nature. Moreover, the adsorbents showed high selectivity for the adsorption of cationic dyes with regenerated properties. The pseudo-second-order kinetics and Langmuir adsorption isotherm models also provide the best correlation of the experimental data for MB adsorption. The results indicate that the MNCAs can be employed as efficient low cost adsorbents with excellent dye adsorption performance in wastewater treatment process. PMID:26428118

  13. Bionanocomposites based on layered silicates and cationic starch as eco-friendly adsorbents for hexavalent chromium removal.

    PubMed

    Koriche, Yamina; Darder, Margarita; Aranda, Pilar; Semsari, Saida; Ruiz-Hitzky, Eduardo

    2014-07-21

    Functional bionanocomposites based on two layered silicates, the commercial montmorillonite known as Cloisite®Na and a natural bentonite from Algeria, were prepared by intercalation of cationic starch, synthesized with two different degrees of substitution, 0.85 and 0.55. After characterization of the prepared bionanocomposites by XRD and zeta potential measurements, batch studies were conducted to evaluate the adsorption capacity of hexavalent chromium anions from aqueous solution. The adsorption isotherms, adsorption kinetics, and the effect of pH on the process were studied. The removal efficiency was evaluated in the presence of competing anions such as NO3(-), ClO4(-), SO4(2-) and Cl(-). In order to regenerate the adsorbent for its repeated use, the regeneration process was studied in two different extractant solutions, 0.1 M NaCl at pH 10 and 0.28 M Na2CO3 at pH 12. PMID:24658793

  14. Preparation of cationized pine sawdust for nitrate removal: Optimization of reaction conditions.

    PubMed

    Keränen, Anni; Leiviskä, Tiina; Hormi, Osmo; Tanskanen, Juha

    2015-09-01

    Anion exchange materials were prepared from pine sawdust (Pinus sylvestris, PSD) through cationizing treatment with N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHMAC) in the presence of NaOH. Response surface methodology (RSM) was used to find the optimal reaction conditions. Three factors were chosen: reaction temperature (26-94 °C), reaction time (0.32-3.7 h) and NaOH/CHMAC molar ratio (0.19-2.2). Product yield (%) was used as a response. A quadratic model was fitted to the experimental data. The optimal conditions were: a reaction temperature of 57 °C, a reaction time of 1.8 h and a NaOH/CHMAC molar ratio of 1.32. A maximum nitrogen content of 2.6% was obtained at 60 °C, 3.7 h and a molar ratio of 1.2. The molar ratio had the greatest impact on the response. Regression analysis revealed that over 95% of the variance can be explained by the model. A maximum nitrate sorption capacity of 15.3 ± 1.4 mg N/g was achieved. The effect of CHMAC dose was also studied (a NaOH/CHMAC molar ratio of 1.2): 0.064 mol/g PSD was found to be near the optimum. Nitrate-contaminated groundwater (27.5 mg/l NO3) was treated with CPSD. Doses of 3-6 g/l resulted in 59-71% nitrate reduction. PMID:26093104

  15. Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution.

    PubMed

    Gul, Kashif; Sohni, Saima; Waqar, Muttaqia; Ahmad, Faiza; Norulaini, N A Nik; A K, Mohd Omar

    2016-11-01

    In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30μgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account. PMID:27516300

  16. Application of Ulva lactuca and Systoceira stricta algae-based activated carbons to hazardous cationic dyes removal from industrial effluents.

    PubMed

    Salima, Attouti; Benaouda, Bestani; Noureddine, Benderdouche; Duclaux, Laurent

    2013-06-15

    Marine algae Ulva lactuca (ULV-AC) and Systoceira stricta (SYS-AC) based activated carbons were investigated as potential adsorbents for the removal of hazardous cationic dyes. Both algae were surface oxidised by phosphoric acid for 2 and subsequently air activated at 600 °C for 3 h. Dyes adsorption parameters such as solution pH, contact time, carbon dosage, temperature and ionic strength were measured in batch experiments. Adsorption capacities of 400 and 526 mg/g for Malachite green and Safranine O by the SYS-AC and ULV-AC respectively were significantly enhanced by the chemical treatments. Model equations such as Langmuir, Freundlich and Temkin isotherms were used to analyse the adsorption equilibrium data and the best fits to the experimental data were provided by the first two isotherm models. BET, FT-IR, iodine number and methylene blue index determination were also performed to characterize the adsorbents. To describe the adsorption mechanism, kinetic models such as pseudo-second-order and the intra particle diffusion were applied. Thermodynamic analysis of the adsorption processes of both dyes confirms their spontaneity and endothermicity. Increasing solution ionic strength increased significantly the adsorption of Safranine O. This study shows that surface modified algae can be an alternative to the commercially available adsorbents for dyes removal from liquid effluents. PMID:23597681

  17. Modification of an Iranian clinoptilolite nano-particles by hexadecyltrimethyl ammonium cationic surfactant and dithizone for removal of Pb(II) from aqueous solution.

    PubMed

    Anari-Anaraki, Mostafa; Nezamzadeh-Ejhieh, Alireza

    2015-02-15

    Natural clinoptilolite tuff was mechanically converted to micro (MCP) and nano (NCP) particles. The MCP and NCP powders were respectively modified with hexadecyltrimethyl ammonium bromide (HDTMA) and dithizone (DTZ). The raw and modified samples were characterized by X-ray diffraction (XRD), Fourier transformation infra red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and thermogravimetry (TG) and used for the removal of Pb(II) from aqueous solution. The results confirm that both ion exchange and complexation processes are responsible for removal of Pb(II) cations in the modified samples, while Pb(II) cations were only removed via an ion exchange process by the raw clinoptilolite. In this sorbent, the anionic removal property of surfactant modified zeolites (SMZs) changed to cationic removal property by an additional modification step. The best removal efficiency was observed by NCP-HDTMA-DTZ at the following experimental conditions: C(Pb(II)): 800 mg L(-1), HDTMA dosage: 0.2 mol L(-1), DTZ dosage: 5 mmol L(-1), contact time of DTZ with NCP-HDTMA: 1800 min and contact time of the sorbent with Pb(II): 360 min. The NCP-HDTMA-DTZ sorbent showed good efficiency for the removal of lead in the presence of different multivalent cations. Adsorption isotherms of Pb(II) ions obey the Langmuir equation that indicate the monolayer sorption of Pb(II). The adsorption kinetics based on the pseudo-second-order rate equation indicates that the rate limiting step involving a chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneous process. PMID:25460715

  18. Ion-exchange and selectivity behavior of thermally treated and. gamma. -irradiated phases of zirconium(IV) arsenophosphate cation exchanger: separation of Al(III) from some metal ions and removal of cations from water

    SciTech Connect

    Varshney, K.G.; Varshney, K.; Agrawal, S.

    1983-01-01

    Ion-exchange and selectivity behavior of zirconium(IV) arsenophosphate (ZAP) has been studied systematically after thermal and irradiation treatments. As a result, an increase in the ion-exchange capacity and a complete reversal in the selectivity sequence for some common metal ions has been observed on heating. The modified phase of ZAP has been utilized successfully for the quantitative separation of aluminum from numerous metal ions and for the removal of cations from water. 5 figures, 3 tables.

  19. Selective removal of alkali metal cations from multiply-charged ions via gas-phase ion/ion reactions using weakly coordinating anions.

    PubMed

    Luongo, Carl A; Bu, Jiexun; Burke, Nicole L; Gilbert, Joshua D; Prentice, Boone M; Cummings, Steven; Reed, Christopher A; McLuckey, Scott A

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 (-)), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 (-)). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations. PMID:25560986

  20. Selective Removal of Alkali Metal Cations from Multiply-Charged Ions via Gas-Phase Ion/Ion Reactions Using Weakly Coordinating Anions

    NASA Astrophysics Data System (ADS)

    Luongo, Carl A.; Bu, Jiexun; Burke, Nicole L.; Gilbert, Joshua D.; Prentice, Boone M.; Cummings, Steven; Reed, Christopher A.; McLuckey, Scott A.

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 -), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 -). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations.

  1. Design of easily testable systems

    SciTech Connect

    Rawat, S.S.

    1988-01-01

    This thesis presents structured testability techniques that can be applied to systolic arrays. Systolic arrays for signal processing have produced processing rates far in excess of general-purpose architecture. Fast testing is considered as one of the design criteria. The main goal is to derive test vectors for one- and two-dimensional systolic arrays. The author seeks to keep the number of test vectors independent of the size of the array under a generic fault model. The testable design is based on pseudo-exhaustive testing. Conventional testing uses Level Sensitive Scan Detection (LSSD) techniques which are very time consuming for an array of systolic processors. By making the testability analysis early the logic designer will be able to make early (and repeated) design trade-offs that make design for testability a simple extension of the design process. The author shows how one-dimensional sequential systolic arrays can be designed so that the faults can be easily detected and isolated. He also considers unilateral two-dimensional sequential arrays and suggests modifications to make them easily testable. Finally, he shows how a modified carry look ahead adder of arbitrary size can be tested with just 136 test vectors. Comparisons are made against the standard LSSD technique.

  2. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons.

    PubMed

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. PMID:27403890

  3. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons

    PubMed Central

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. DOI: http://dx.doi.org/10.7554/eLife.14599.001 PMID:27403890

  4. Amazon kaolinite functionalized with diethylenetriamine moieties for U(VI) removal: thermodynamic of cation-basic interactions.

    PubMed

    Guerra, Denis L; Leidens, Victor L; Viana, Rúbia R; Airoldi, Claudio

    2010-08-15

    The compound N-[3-(trimethoxysilyl)propyl]diethylenetriamine (MPDET) was anchored onto Amazon kaolinite surface (KLT) by heterogeneous route. The modified and natural kaolinite clay samples were characterized by transmission electron microscopy (TEM), scanning electron microscopic (SEM), N(2) adsorption, powder X-ray diffraction, thermal analysis, ion exchange capacities, and nuclear magnetic nuclei of (29)Si and (13)C. The well-defined peaks obtained in the (13)C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The adsorption of uranyl on natural (KLT) and modified (KLT(MPDET)) kaolinite clays was investigated as a function of the solution pH, metal concentration, temperature, and ionic strength. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 8.37 x 10(-3) and 13.87 x 10(-3) mmol g(-1) for KLT and KLT(MPDET) at 298 K, respectively. The energetic effects (Delta(int)H, Delta(int)G, and Delta(int)S) caused by metal cations adsorption were determined through calorimetric titrations. PMID:20478656

  5. Benzene carboxylic acid derivatized graphene oxide nanosheets on natural zeolites as effective adsorbents for cationic dye removal.

    PubMed

    Yu, Yang; Murthy, Bandaru N; Shapter, Joseph G; Constantopoulos, Kristina T; Voelcker, Nicolas H; Ellis, Amanda V

    2013-09-15

    Graphene oxide (GO) nanosheets were grafted to acid-treated natural clinoptilolite-rich zeolite powders followed by a coupling reaction with a diazonium salt (4-carboxybenzenediazoniumtetrafluoroborate) to the GO surface. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) revealed successful grafting of GO nanosheets onto the zeolite surface. The application of the adsorbents for the adsorption of rhodamine B from aqueous solutions was then demonstrated. After reaching adsorption equilibrium the maximum adsorption capacities were shown to be 50.25, 55.56 and 67.56 mg g(-1) for pristine natural zeolite, GO grafted zeolite (GO-zeolite) and benzene carboxylic acid derivatized GO-zeolite powders, respectively. The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. Further, a relationship between surface functional groups, pH and adsorption efficiency was established. Results indicate that benzene carboxylic acid derivatized GO-zeolite powders are environmentally favorable adsorbents for the removal of cationic dyes from aqueous solutions. PMID:23778259

  6. Metal-air battery with easily removable anodes

    SciTech Connect

    Niksa, A.J.; Nikasa, M.J.; Noscal, J.M.; Sovich, T.J.

    1990-08-21

    This patent describes a metal-air battery. It comprises: one or more cells. Each cell comprising;a frame having opposed faces; an air cathode sealed to each face of the frame; an access opening in the frame; an anode blank comprising a consumable end inserted through the access opening into the space between the air cathodes and an exposed end protruding from the opening for replacement of the anode blank through the opening; and a labyrinth seal molded directly onto the anode blank between the consumable end and the exposed end sealing the access opening.

  7. Novel tannin-based adsorbent in removing cationic dye (Methylene Blue) from aqueous solution. Kinetics and equilibrium studies.

    PubMed

    Sánchez-Martín, J; González-Velasco, M; Beltrán-Heredia, J; Gragera-Carvajal, J; Salguero-Fernández, J

    2010-02-15

    Natural tannin-based adsorbent has been prepared on the basis of the gelification of Quebracho bark extract. The resulting product, Quebracho Tannin Gel (QTG) was tested as cationic dye adsorbent with Methylene Blue (MB). Kinetics of adsorption process were studied out and a period of 15 days was determined for reaching equilibrium. The influences of pH and temperature were evaluated. As pH or temperature raise q capacity of QTG increases. Theoretical modelization of dye-QTG adsorption was carried out by multiparametric adjustment according to Langmuir's hypothesis. Values of the k(l1), k(l2) and activation energies were calculated. PMID:19782466

  8. FINAL REPORT. REMOVAL OF RADIOACTIVE CATIONS AND ANIONS FROM POLLUTED WATER USING LIGAND-MODIFIED COLLOID-ENHANCED ULTRAFILTRATION

    EPA Science Inventory

    The purpose of this project was to develop, optimize, and evaluate new separation methods for removal of hazardous (radionuclides and toxic non-radioactive contaminants) metal ions from either ground water or aqueous waste solutions produced during Decontamination and Decommissio...

  9. Modeling and optimization of the flocculation processes for removal of cationic and anionic dyes from water by an amphoteric grafting chitosan-based flocculant using response surface methodology.

    PubMed

    Wu, Hu; Yang, Ran; Li, Ruihua; Long, Chao; Yang, Hu; Li, Aimin

    2015-09-01

    In this study, an amphoteric grafting chitosan-based flocculant (carboxymethyl chitosan-graft-poly(2-methacryloyloxyethyl) trimethyl ammonium chloride, denoted as CMC-g-PDMC) was applied to removal of the anionic and cationic dyes, acid Green 25 (AG25) and Basic Bright Yellow (7GL), from water. Flocculation conditions have been optimized by response surface methodology (RSM) on the basis of central composite design (CCD) using flocculant dosage, initial solution pH and temperature as input variables. The second-order and cubic regression models, which have been both tested by the analysis of variance (ANOVA), were constructed to link the output response (the dye removal factor) with the aforementioned input variables, respectively. The second-order regression model well described the process of AG25 removal, whereas the cubic one is more suitable for that of 7GL. The effects of those variables on the flocculation performance of CMC-g-PDMC for removal of the two dyes containing opposite charges from aqueous solutions have been studied, and the flocculation mechanisms including the interactive effects between various influencing factors have been discussed in detail also. PMID:25921759

  10. Selective removal of toxic anionic dyes using a novel nanocomposite derived from cationically modified guar gum and silica nanoparticles.

    PubMed

    Patra, Abhay Shankar; Ghorai, Soumitra; Ghosh, Shankhamala; Mandal, Barun; Pal, Sagar

    2016-01-15

    A novel nanocomposite derived from cationically modified guar gum and in-situ incorporated SiO2 NP (cat-GG/SiO2) has been developed. The cat-GG has been synthesised by grafting poly(2-(diethylamino)ethyl methacrylate) on GG backbone. Various analyses endorse the suitability of cat-GG as well-organized template for the development of homogeneous SiO2 NPs. Dye adsorption studies predict that cat-GG/SiO2 efficiently and selectively adsorb anionic dyes (reactive blue-RB and Congo red-CR) from mixture of dye solutions. This is because of high surface area, multifunctional chelating H-bonding interactions and electrostatic interactions of cationic adsorbent with anionic dyes. Dyes adsorbed on the composite surface are desorbed reversibly using pH 10 stripping solution. Besides, cat-GG/SiO2 has been recycled efficiently with no prominent loss of dye uptake capacity, even after 4 adsorption-desorption cycles. PMID:26348145

  11. Studies of cation binding in ZnCl2-regenerated bacteriorhodopsin by x-ray absorption fine structures: effects of removing water molecules and adding Cl- ions.

    PubMed Central

    Zhang, K; Song, L; Dong, J; El-Sayed, M A

    1997-01-01

    The binding of Zn2+ in Zn2+-regenerated bacteriorhodopsin (bR) was studied under various conditions by x-ray absorption fine structures (XAFS). The 0.9:1 and 2:1 Zn2+:bR samples gave similar XAFS spectra, suggesting that Zn2+ might have only one strong binding site in bR. It was found that in aqueous bR solution, Zn2+ has an average of six oxygen or nitrogen ligands. Upon drying, two ligands are lost, suggesting the existence of two weakly bound water ligands near the cation-binding site in bacteriorhodopsin. When excess Cl- ions were present before drying in the Zn2+-regenerated bR samples, it was found that two of the ligands were replaced by Cl- ions in the dried film, whereas two remain unchanged. The above observations suggest that Zn2+ has three types of ligands in regenerated bR (referred to as types I, II, and III). Type I ligands are strongly bound. These ligands cannot be removed by drying or by exchanging with Cl- ions. Type II ligands cannot be removed by drying, but can be replaced by Cl- ligands. Type III ligands are weakly bound to the metal cation and are most likely water molecules that can be removed by evaporation under vacuum or by drying with anhydrous CaSO4. The results are discussed in terms of the possible structure of the strongly binding site of Zn2+ in bR. PMID:9336205

  12. Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

    PubMed

    Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

    2015-11-25

    Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II). PMID:26540557

  13. An Easily Constructed Trigonal Prism Model.

    ERIC Educational Resources Information Center

    Yamana, Shukichi

    1984-01-01

    A model of a trigonal prism which is useful for teaching stereochemistry (especially of the neodymium enneahydrate ion), can be made easily by using a sealed, empty envelope. The steps necessary to accomplish this task are presented. (JN)

  14. Removal of Radioactive Cations and Anions from Polluted Water using Ligand-Modified Colloid-Enhanced Ultrafiltration

    SciTech Connect

    Dr. John F. Scamehorn; Dr. Richard W. Taylor; Dr. Cynthia E. Palmer

    2001-12-17

    The purpose of this project was to develop, optimize, and evaluate new separation methods for removal of hazardous (radionuclides and toxic non-radioactive contaminants) metal ions from either ground water or aqueous waste solutions produced during Decontamination and Decommissioning operations at DOE sites. Separation and concentration of the target ions will result in a substantial reduction in the volume of material requiring disposal or long-term storage. The target metal ions studied were uranium, thorium, lead, cadmium, and mercury along with chromium (as chromate). The methods tested use membrane ultrafiltration in conjunction with water-soluble polymers or surfactants with added metal-selective chelating agents. Laboratory scale tests showed removal of 99.0-99.9% of each metal tested in a single separation stage. The methods developed for selective removal of radionuclides (UO22+, Th4+) and toxic heavy metals (Pb2+, Cd2+, Hg2+) are applicable to two DOE focus areas; decontamination of sites and equipment, and in remediation of contaminated groundwater. Colloid-enhanced ultrafiltration methods have potential to be substantially less expensive than alternative methods and can result in less waste. Results of studies with varying solution composition (concentration, acidity) and filtration parameters (pressure, flow rate) have increased our understanding of the fundamental processes that control the metal ion separation and colloid recovery steps of the overall process. Further laboratory studies are needed to improve the ligand/colloid recovery step and field demonstration of the technology is needed to prove the applicability of the integrated process. A number of graduate students, post-doctoral associates, and research associates have received training and research experience in the areas of separation science, colloid chemistry, and metal ion coordination chemistry of radionuclides and toxic metals. These scientists, some with positions in industry and

  15. Separation of oil-in-water emulsions by microbubble treatment and the effect of adding coagulant or cationic surfactant on removal efficiency.

    PubMed

    Van Le, Tuan; Imai, Tsuyoshi; Higuchi, Takaya; Doi, Ryosuke; Teeka, Jantima; Xiaofeng, Sun; Teerakun, Mullika

    2012-01-01

    This study examined the efficiencies of microbubble (MB) treatment, MB treatment with polyaluminium chloride (PAC) as a coagulant, and MB treatment with cetyltrimethylammonium chloride (CTAC) as a cationic surfactant in the separation of emulsified oil (EO) by modified column flotation. Batch mode experiments were conducted by synthesizing emulsified palm oil (d<20 μm), and the chemical oxygen demand (COD) of the influent and effluent was measured to evaluate the treatment performance. MB treatment with PAC and MB treatment with CTAC were found to be more efficient in EO removal than the MB treatment alone. At an EO concentration of ∼1,000 mg L(-1) (pH 7) and under identical treatment conditions (MB generation time: 2.5 min, flotation time: 30 min), MB treatment with PAC (50 mg L(-1)) and that with CTAC (0.5 mg L(-1)) showed equally high EO removal efficiencies of 92 and 89%, respectively. This result is of significant relevance to studies focusing on the development of economical and high-efficiency flotation systems. Furthermore, the effect of pH was investigated by varying the sample pH from 3 to 8, which showed that the EO separation efficiency of MB alone increased drastically from slightly alkaline to acidic condition. PMID:22797232

  16. Ligand-modified polyelectrolyte-enhanced ultrafiltration with electrostatic attachment of ligands. 2. Use of diethylenetriaminepentaacetic acid/cationic polyelectrolyte mixtures to remove both cations and anions from aqueous streams

    SciTech Connect

    Tuncay, M. Univ. of Oklahoma, Norman, OK ); Christian, S.D.; Tucker, E.E.; Taylor, R.W.; Scamehorn, J.F. )

    1994-12-01

    A mixture of a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) or PDADMAC, and the anionic ligand diethylenetriaminepentaacetic acid (DTPA) can be added to aqueous streams as a water-soluble colloid to bind simultaneously divalent cations, such as Cu[sup 2+] and Pb[sup 2+], and anions, such as CrO[sub 4][sup 2[minus

  17. Actinide cation-cation complexes

    SciTech Connect

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO{sub 2}{sup +}) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO{sub 2}{sup +}; therefore, cation-cation complexes indicate something unique about AnO{sub 2}{sup +} cations compared to actinide cations in general. The first cation-cation complex, NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO{sub 2}{sup +} species, the cation-cation complexes of NpO{sub 2}{sup +} have been studied most extensively while the other actinides have not. The only PuO{sub 2}{sup +} cation-cation complexes that have been studied are with Fe{sup 3+} and Cr{sup 3+} and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, NpO{sub 2}{sup +}{center_dot}Th{sup 4+}, PuO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, and PuO{sub 2}{sup +}{center_dot}Th{sup 4+} at an ionic strength of 6 M using LIPAS are 2.4 {plus_minus} 0.2, 1.8 {plus_minus} 0.9, 2.2 {plus_minus} 1.5, and {approx}0.8 M{sup {minus}1}.

  18. ACECARD. Acquire CoOmmodities Easily Card

    SciTech Connect

    Soler, E.E.

    1996-09-01

    Acquire Commodities Easily Card (AceCard) provides an automated end-user method to distribute company credit card charges to internal charge numbers. AceCard will allow cardholders to record card purchases in an on-line order log, enter multiple account distributions per order that can be posted to the General Ledger, track orders, and receipt information, and provide a variety of cardholder and administrative reports. Please note: Customers must contact Ed Soler (423)-576-6151, Lockheed Martin Energy Systems, for help with the installation of the package. The fee for this installation help will be coordinated by the customer and Lockheed Martin and is in addition to cost of the package from ESTSC. Customers should contact Sandy Presley (423)-576-4708 for user help.

  19. Acquire CoOmmodities Easily Card

    Energy Science and Technology Software Center (ESTSC)

    1998-05-29

    Acquire Commodities Easily Card (AceCard) provides an automated end-user method to distribute company credit card charges to internal charge numbers. AceCard will allow cardholders to record card purchases in an on-line order log, enter multiple account distributions per order that can be posted to the General Ledger, track orders, and receipt information, and provide a variety of cardholder and administrative reports. Please note: Customers must contact Ed Soler (423)-576-6151, Lockheed Martin Energy Systems, for helpmore » with the installation of the package. The fee for this installation help will be coordinated by the customer and Lockheed Martin and is in addition to cost of the package from ESTSC. Customers should contact Sandy Presley (423)-576-4708 for user help.« less

  20. Acquire CoOmmodities Easily Card

    SciTech Connect

    Soler, E. E.

    1998-05-29

    Acquire Commodities Easily Card (AceCard) provides an automated end-user method to distribute company credit card charges to internal charge numbers. AceCard will allow cardholders to record card purchases in an on-line order log, enter multiple account distributions per order that can be posted to the General Ledger, track orders, and receipt information, and provide a variety of cardholder and administrative reports. Please note: Customers must contact Ed Soler (423)-576-6151, Lockheed Martin Energy Systems, for help with the installation of the package. The fee for this installation help will be coordinated by the customer and Lockheed Martin and is in addition to cost of the package from ESTSC. Customers should contact Sandy Presley (423)-576-4708 for user help.

  1. Material Removes Heavy Metal Ions From Water

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H., Jr.; Street, Kenneth W.; Hill, Carol; Savino, Joseph M.

    1995-01-01

    New high capacity ion-exchange polymer material removes toxic metal cations from contaminated water. Offers several advantages. High sensitivities for such heavy metals as lead, cadmium, and copper and capable of reducing concentrations in aqueous solutions to parts-per-billion range. Removes cations even when calcium present. Material made into variety of forms, such as thin films, coatings, pellets, and fibers. As result, adapted to many applications to purify contaminated water, usually hard wherever found, whether in wastewater-treatment systems, lakes, ponds, industrial plants, or homes. Another important feature that adsorbed metals easily reclaimed by either destructive or nondestructive process. Other tests show ion-exchange polymer made inexpensively; easy to use; strong, flexible, not easily torn; and chemically stable in storage, in aqueous solutions, and in acidic or basic solution.

  2. Easily retrievable objects among the NEO population

    NASA Astrophysics Data System (ADS)

    García Yárnoz, D.; Sanchez, J. P.; McInnes, C. R.

    2013-08-01

    Asteroids and comets are of strategic importance for science in an effort to understand the formation, evolution and composition of the Solar System. Near-Earth Objects (NEOs) are of particular interest because of their accessibility from Earth, but also because of their speculated wealth of material resources. The exploitation of these resources has long been discussed as a means to lower the cost of future space endeavours. In this paper, we consider the currently known NEO population and define a family of so-called Easily Retrievable Objects (EROs), objects that can be transported from accessible heliocentric orbits into the Earth's neighbourhood at affordable costs. The asteroid retrieval transfers are sought from the continuum of low energy transfers enabled by the dynamics of invariant manifolds; specifically, the retrieval transfers target planar, vertical Lyapunov and halo orbit families associated with the collinear equilibrium points of the Sun-Earth Circular Restricted Three Body problem. The judicious use of these dynamical features provides the best opportunity to find extremely low energy Earth transfers for asteroid material. A catalogue of asteroid retrieval candidates is then presented. Despite the highly incomplete census of very small asteroids, the ERO catalogue can already be populated with 12 different objects retrievable with less than 500 m/s of Δ v. Moreover, the approach proposed represents a robust search and ranking methodology for future retrieval candidates that can be automatically applied to the growing survey of NEOs.

  3. In situ remediation process using divalent metal cations

    DOEpatents

    Brady, Patrick V.; Khandaker, Nadim R.; Krumhansl, James L.; Teter, David M.

    2004-12-14

    An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu.sup.2+ or Zn.sup.2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO.sub.4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.

  4. First-Principles Calculation Study of Mechanism of Cation Adsorption Selectivity of Zeolites: A Guideline for Effective Removal of Radioactive Cesium

    NASA Astrophysics Data System (ADS)

    Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko

    2013-02-01

    Zeolites have attracted attention in the reprocessing of radioactive nuclear waste because of their high selective affinity for radioisotopes of Cs. Very recently, their useful properties have been widely utilized in decontamination after the accident at the Fukushima Daiichi Nuclear Power Plants. In this study, we study the high selectivity in the Cs adsorption of zeolites using first-principles calculations and clarify the mechanism of the cation selectivity of zeolites. We obtain energy surfaces on all capture locations for Cs/Na ions inside the micropores of a zeolite, ``mordenite'', and find three crucial conditions for the highly ion-selective exchange of Na for Cs: i) micropores with a radius of ˜3 Å, ii) a moderate Al/Si ratio, and iii) a uniform distribution of Al atoms around each micropore. These insights suggest a guideline for developing zeolites with high Cs selectivity and for enhancing the cation selectivity in more general situations.

  5. Removal of Divalent Cations Induces Structural Transitions in Red Clover Necrotic Mosaic Virus, Revealing a Potential Mechanism for RNA Release▿†

    PubMed Central

    Sherman, Michael B.; Guenther, Richard H.; Tama, Florence; Sit, Tim L.; Brooks, Charles L.; Mikhailov, Albert M.; Orlova, Elena V.; Baker, Timothy S.; Lommel, Steven A.

    2006-01-01

    The structure of Red clover necrotic mosaic virus (RCNMV), an icosahedral plant virus, was resolved to 8.5 Å by cryoelectron microscopy. The virion capsid has prominent surface protrusions and subunits with a clearly defined shell and protruding domains. The structures of both the individual capsid protein (CP) subunits and the entire virion capsid are consistent with other species in the Tombusviridae family. Within the RCNMV capsid, there is a clearly defined inner cage formed by complexes of genomic RNA and the amino termini of CP subunits. An RCNMV virion has approximately 390 ± 30 Ca2+ ions bound to the capsid and 420 ± 25 Mg2+ ions thought to be in the interior of the capsid. Depletion of both Ca2+ and Mg2+ ions from RCNMV leads to significant structural changes, including (i) formation of 11- to 13-Å-diameter channels that extend through the capsid and (ii) significant reorganization within the interior of the capsid. Genomic RNA within native capsids containing both Ca2+ and Mg2+ ions is extremely resistant to nucleases, but depletion of both of these cations results in nuclease sensitivity, as measured by a significant reduction in RCNMV infectivity. These results indicate that divalent cations play a central role in capsid dynamics and suggest a mechanism for the release of viral RNA in low-divalent-cation environments such as those found within the cytoplasm of a cell. PMID:16920821

  6. Voltage controlled oscillator is easily aligned, has low phase noise

    NASA Technical Reports Server (NTRS)

    Sydnor, R. L.

    1965-01-01

    Voltage Controlled Oscillator /VCO/, represented by an equivalent RF circuit, is easily adjusted for optimum performance by varying the circuit parameter. It contains a crystal drive level which is also easily adjusted to obtain minimum phase noise.

  7. Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery.

    PubMed

    Anirudhan, T S; Divya, L; Ramachandran, M

    2008-09-15

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R(2)=0.99; chi(2)=1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%. PMID:18313209

  8. Easily constructed mini-sextant demonstrates optical principles

    NASA Astrophysics Data System (ADS)

    Nenninger, Garet G.

    2000-04-01

    An easily constructed optical instrument for measuring the angle between the Sun and the horizon is described. The miniature sextant relies on multiple reflections to produce multiple images of the sun at fixed angles away from the true Sun.

  9. Description of the Experimental Avionics Systems Integration Laboratory (EASILY)

    NASA Technical Reports Server (NTRS)

    Outlaw, Bruce K. E.

    1994-01-01

    The Experimental Avionics Systems Integration Laboratory (EASILY) is a comprehensive facility used for development, integration, and preflight validation of hardware and software systems for the Terminal Area Productivity (TAP) Program's Transport Systems Research Vehicle (TSRV) experimental transport aircraft. This report describes the history, capabilities, and subsystems of EASILY. A functional description of the many subsystems is provided to give potential users the necessary knowledge of the capabilities of this facility.

  10. Application of Brazilian kaolinite clay as adsorbent to removal of U(VI) from aqueous solution: Kinetic and thermodynamic of cation-basic interactions

    SciTech Connect

    Guerra, Denis L.; Leidens, Victor L.; Viana, Rubia R.; Airoldi, Claudio

    2010-05-15

    The compound N{sup 1}-[3-(trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route. The modified and natural kaolinite samples were characterized by transmission electron microscopy, scanning electron microscopic, X-ray diffraction, and nuclear magnetic nuclei of {sup 29}Si and {sup 13}C. The well-defined peaks obtained in the {sup 13}C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k{sub 2} values 16.0 and 25.1 mmol g{sup -1} min{sup -1} ranges for natural and modified kaolinite clays, respectively. The energetic effects caused by metal ion adsorption were determined through calorimetric titrations. - Graphical abstract: This investigation reports the use of original and modified kaolinites as alternative absorbents. The compound N-[3-trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route.

  11. Easily disassembled electrical connector for high voltage, high frequency connections

    DOEpatents

    Milner, J.R.

    1994-05-10

    An easily accessible electrical connector capable of rapid assembly and disassembly is described wherein a wide metal conductor sheet may be evenly contacted over the entire width of the conductor sheet by opposing surfaces on the connector which provide an even clamping pressure against opposite surfaces of the metal conductor sheet using a single threaded actuating screw. 13 figures.

  12. Easily disassembled electrical connector for high voltage, high frequency connections

    DOEpatents

    Milner, Joseph R.

    1994-01-01

    An easily accessible electrical connector capable of rapid assembly and disassembly wherein a wide metal conductor sheet may be evenly contacted over the entire width of the conductor sheet by opposing surfaces on the connector which provide an even clamping pressure against opposite surfaces of the metal conductor sheet using a single threaded actuating screw.

  13. Micromanipulation tool is easily adapted to many uses

    NASA Technical Reports Server (NTRS)

    Shlichta, P. J.

    1967-01-01

    A special micromanipulation tool equipped with a plunger mounted in a small tube can be easily adapted to such work operations as cutting, precision clamping, and spot welding of microscopic filaments or other parts. This tool is valuable where extreme steadiness of high magnification is required.

  14. Modular thermoelectric cell is easily packaged in various arrays

    NASA Technical Reports Server (NTRS)

    Epstein, J.

    1965-01-01

    Modular thermoelectric cells are easily packaged in various arrays to form power supplies and have desirable voltage and current output characteristics. The cells employ two pairs of thermoelectric elements, each pair being connected in parallel between two sets of aluminum plates. They can be used as solar energy conversion devices.

  15. A method for easily customizable gradient gel electrophoresis.

    PubMed

    Miller, Andrew J; Roman, Brandon; Norstrom, Eric

    2016-09-15

    Gradient polyacrylamide gel electrophoresis is a powerful tool for the resolution of polypeptides by relative mobility. Here, we present a simplified method for generating polyacrylamide gradient gels for routine analysis without the need for specialized mixing equipment. The method allows for easily customizable gradients which can be optimized for specific polypeptide resolution requirements. Moreover, the method eliminates the possibility of buffer cross contamination in mixing equipment, and the time and resources saved with this method in place of traditional gradient mixing, or the purchase of pre-cast gels, are noteworthy given the frequency with which many labs use gradient gel SDS-PAGE. PMID:27393767

  16. Internal crankcase ventilation system with easily accessible PCV valve

    SciTech Connect

    Balsley, R.L.

    1986-07-29

    A crankcase ventilation system is described having a flow limiting PCV valve and means defining and internal passage between a crankcase and a cylinder charge induction means of an engine, the system comprising an engine valve cover forming a part of the internal passage defining means and having an exterior wall, a cavity in the cover wall and forming a portion of the internal passage, the wall further including valve mounting means surrounding the passage and receiving the valve and a valve body seal in position to control flow through the mounting means and passage and an opening through the wall to the housing exterior and generally opposite the mounting means for removing and replacing a valve on the mounting means, and closure means normally closing the opening and preventing air leakage therethrough into the induction system, the closure means engaging the valve to maintain its installed position within the wall cavity and being openable to permit removal of the PCV valve.

  17. Easily Transported CCD Systems for Use in Astronomy Labs

    NASA Astrophysics Data System (ADS)

    Meisel, D.

    1992-12-01

    Relatively inexpensive CCD cameras and portable computers are now easily obtained as commercially available products. I will describe a prototype system that can be used by introductory astronomy students, even urban enviroments, to obtain useful observations of the night sky. It is based on the ST-4 CCDs made by Santa Barbara Instruments Group and Macintosh Powerbook145 computers. Students take outdoor images directly from the college campus, bring the exposures back into the lab and download the images into our networked server. These stored images can then be processed (at a later time) using a variety of image processing programs including a new astronomical version of the popular "freeware" NIH Image package that is currently under development at Geneseo. The prototype of this system will be demonstrated and available for hands-on use during the meeting. This work is supported by NSF ILI Demonstration Grant USE9250493 and Grants from SUNY-GENESEO.

  18. Design of easily testable and reconfigurable systolic arrays

    SciTech Connect

    Kim, J.H.

    1987-01-01

    Systolic arrays are considered to be preferred architectures for executing linear algebraic operations. In this thesis, easily testable and reconfigurable (ETAR) systolic arrays are studied to achieve the yield enhancement. New 2-D systolic arrays that lend themselves to easy reconfiguration as well as efficient implementations of algorithms are proposed. The 2-D bidirectional and unidirectional systolic arrays proposed are often better architectures than the rectangular and hexagonal systolic arrays proposed earlier, if one considers area, time and reconfigurability. Methods to design linear and 2-D ETAR systolic arrays are proposed. Procedures to design linear and 2-D unidirectional and bidirectional systolic arrays are given. The main feature of the proposed designs is that the COMUs of the PEs in the linear array can all be tested simultaneously. Another feature is that the throughputs of the reconfigured linear unidirectional as well as bidirectional arrays can remain to be equal to those of the fault-free linear arrays. A reconfiguration algorithm for 2-D systolic arrays is also proposed.

  19. A highly versatile and easily configurable system for plant electrophysiology.

    PubMed

    Gunsé, Benet; Poschenrieder, Charlotte; Rankl, Simone; Schröeder, Peter; Rodrigo-Moreno, Ana; Barceló, Juan

    2016-01-01

    In this study we present a highly versatile and easily configurable system for measuring plant electrophysiological parameters and ionic flow rates, connected to a computer-controlled highly accurate positioning device. The modular software used allows easy customizable configurations for the measurement of electrophysiological parameters. Both the operational tests and the experiments already performed have been fully successful and rendered a low noise and highly stable signal. Assembly, programming and configuration examples are discussed. The system is a powerful technique that not only gives precise measuring of plant electrophysiological status, but also allows easy development of ad hoc configurations that are not constrained to plant studies. •We developed a highly modular system for electrophysiology measurements that can be used either in organs or cells and performs either steady or dynamic intra- and extracellular measurements that takes advantage of the easiness of visual object-oriented programming.•High precision accuracy in data acquisition under electrical noisy environments that allows it to run even in a laboratory close to electrical equipment that produce electrical noise.•The system makes an improvement of the currently used systems for monitoring and controlling high precision measurements and micromanipulation systems providing an open and customizable environment for multiple experimental needs. PMID:27298766

  20. Triazolophthalazines: Easily Accessible Compounds with Potent Antitubercular Activity.

    PubMed

    Veau, Damien; Krykun, Serhii; Mori, Giorgia; Orena, Beatrice S; Pasca, Maria R; Frongia, Céline; Lobjois, Valérie; Chassaing, Stefan; Lherbet, Christian; Baltas, Michel

    2016-05-19

    Tuberculosis (TB) remains one of the major causes of death worldwide, in particular because of the emergence of multidrug-resistant TB. Herein we explored the potential of an alternative class of molecules as anti-TB agents. Thus, a series of novel 3-substituted triazolophthalazines was quickly and easily prepared from commercial hydralazine hydrochloride as starting material and were further evaluated for their antimycobacterial activities and cytotoxicities. Four of the synthesized compounds were found to effectively inhibit the Mycobacterium tuberculosis (M.tb) H37 Rv strain with minimum inhibitory concentration (MIC) values <10 μg mL(-1) , whereas no compounds displayed cytotoxicity against HCT116 human cell lines (IC50 >100 μm). More remarkably, the most potent compounds proved to be active to a similar extent against various multidrug-resistant M.tb strains, thus uncovering a mode of action distinct from that of standard antitubercular agents. Overall, their ease of preparation, combined with their attractive antimycobacterial activities, make such triazolophthalazine-based derivatives promising leads for further development. PMID:27097919

  1. Easily fabricated magnetic traps for single-cell applications

    NASA Astrophysics Data System (ADS)

    Koschwanez, John H.; Carlson, Robert H.; Meldrum, Deirdre R.

    2007-04-01

    We describe a simple and inexpensive method of fabricating single cell magnetic traps within a polydimethylsiloxane (PDMS) device. These traps were developed as part of an automated system that captures individual yeast cells in a microfluidic device and analyzes each cell as it buds. To make the traps, PdCl2 catalyst is rubbed with vinyl foam onto plasma-patterned PDMS, and then Co-Ni-B alloy is electrolessly deposited onto the catalyst at a moderate temperature. We demonstrate individual yeast cell capture and estimate the capture force (1.9-4.4 pN) by measuring the flow speed required to remove the cell from its trap in a microfluidic channel.

  2. Metview and VAPOR: Exploring ECMWF forecasts easily in four dimensions

    NASA Astrophysics Data System (ADS)

    Siemen, Stephan; Kertesz, Sandor; Carver, Glenn

    2014-05-01

    The European Centre for Medium-Range Weather Forecasts (ECMWF) is an international organisation providing its member states and co-operating states with forecasts in the medium time range of up to 15 days as well as other forcasts and analysis. As part of its mission, ECMWF generates an increasing number of forecast data products for its users. To support the work of forecasters and researchers and to let them make best use of ECMWF forecasts, the Centre also provides tools and interfaces to visualise their products. This allows users to make use of and explore forecasts without having to transfer large amounts of raw data. This is especially true for products based on ECMWF's 50 member ensemble forecast. Users can choose to explore ECMWF's forecasts from the web or through visualisation tools installed locally or at ECMWF. ECMWF also develops in co-operation with INPE, Brazil, the Metview meteorological workstation and batch system. Metview enables users to easily analyse and visualise forecasts, and is routinely used by scientists and forecasters at ECMWF and other institutions. While Metview offers high quality visualisation in two-dimensional plots and animations, it uses external tools to visualise data in four dimensions. VAPOR is the Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers. VAPOR provides an interactive 3D visualisation environment that runs on most UNIX and Windows systems equipped with modern 3D graphics cards. VAPOR development is led by the National Center for Atmospheric Research's Scientific Computing Division in collaboration with U.C. Davis and Ohio State University. In this paper we will give an overview of how users, with Metview and access to ECMWF's archive, can visualise forecast data in four dimensions within VAPOR. The process of preparing the data in Metview is the key step and described in detail. The benefits to researchers are highlighted with a case study analysing a given weather scenario.

  3. The cubyl cation rearrangements.

    PubMed

    Jalife, Said; Mondal, Sukanta; Cabellos, Jose Luis; Martinez-Guajardo, Gerardo; Fernandez-Herrera, Maria A; Merino, Gabriel

    2016-02-25

    Born-Oppenheimer molecular dynamics simulations and high-level ab initio computations predict that the cage-opening rearrangement of the cubyl cation to the 7H(+)-pentalenyl cation is feasible in the gas phase. The rate-determining step is the formation of the cuneyl cation with an activation barrier of 25.3 kcal mol(-1) at the CCSD(T)/def2-TZVP//MP2/def2-TZVP level. Thus, the cubyl cation is kinetically stable enough to be formed and trapped at moderate temperatures, but it may be rearranged at higher temperatures. PMID:26880646

  4. Removal of phenols and aromatic amines from wastewater by a combination treatment with tyrosinase and a coagulant

    SciTech Connect

    Wada, Shinji; Ichikawa, Hiroyasu; Tatsumi, Kenji )

    1995-02-20

    Removal of phenols and aromatic amines from industrial wastewater by tyrosinase was investigated. A color change from colorless to dark brown was observed, but no precipitate was formed. Colored products were found to be easily removed by a combination treatment with tyrosinase and a cationic polymer coagulant containing amino group, such as hexamethylenediamine-epichlorohidrin polycondensate, polyethleneimine, or chitosan. The first two coagulants, synthetic polymers, were more effective than chitosan, a polymer produced in crustacean shells. Phenols and aromatic amines are not precipitated by any kind of coagulants, but their enzymatic reaction products are easily precipitated by a cationic polymer coagulant. These results indicate that the combination of tyrosinase and a cationic polymer coagulant is effective in removing carcinogenic phenols and aromatic amines from an aqueous solution. Immobilization of tyrosinase on magnetite gave a good retention of activity (80%) and storage stability i.e., only 5% loss after 15 days of storage at ambient temperature. In the treatment of immobilized tyrosinase, colored enzymatic reaction products were removed by less coagulant compared with soluble tyrosinase.

  5. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O`Neill, M.A.; Pellerin, P.J.M.; Warrenfeltz, D.; Vidal, S.; Darvill, A.G.; Albersheim, P.

    1999-03-02

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations. 15 figs.

  6. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O'Neill, Malcolm A.; Pellerin, Patrice J. M.; Warrenfeltz, Dennis; Vidal, Stephane; Darvill, Alan G.; Albersheim, Peter

    1999-01-01

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations.

  7. Removing heavy metals from synthetic effluents using "kamikaze" Saccharomyces cerevisiae cells.

    PubMed

    Ruta, Lavinia; Paraschivescu, Codruta; Matache, Mihaela; Avramescu, Sorin; Farcasanu, Ileana Cornelia

    2010-01-01

    One key step of the bioremediation processes designed to clean up heavy metal contaminated environments is growing resistant cells that accumulate the heavy metals to ensure better removal through a combination of biosorption and continuous metabolic uptake after physical adsorption. Saccharomyces cerevisiae cells can easily act as cation biosorbents, but isolation of mutants that are both hyperaccumulating and tolerant to heavy metals proved extremely difficult. Instead, mutants that are hypersensitive to heavy metals due to increased and continuous uptake from the environment were considered, aiming to use such mutants to reduce the heavy metal content of contaminated waters. In this study, the heavy metal hypersensitive yeast strain pmr1Delta was investigated for the ability to remove Mn2+, Cu2+, Co2+, or Cd2+ from synthetic effluents. Due to increased metal accumulation, the mutant strain was more efficient than the wild-type in removing Mn2+, Cu2+, or Co2+ from synthetic effluents containing 1-2 mM cations, with a selectivity and also in removing Mn2+ and Cd2+ from synthetic effluents containing 20-50 microM cations, with a selectivity Mn2+ > Cd2+. PMID:19795117

  8. Dynamics of poly(4-hydroxystyrene) radical cation

    NASA Astrophysics Data System (ADS)

    Okamoto, Kazumasa; Kozawa, Takahiro; Tagawa, Seiichi

    2008-03-01

    Poly(4-hydroxystyrene) (PHS) has been used in KrF excimer laser (248 nm) lithography as a backbone polymer, and is also a promising material for EUV or electron beam lithography. Analysis of the intermediate species is important for the control of reactions in resist materials. Since the size of integrated circuits fabricated for mass production will decrease below 30 nm and the size error must also be decreased to the molecular level, the elucidation of proton dynamics at the molecular level is also important for reducing the deviation of the resist pattern size. In this study, the dynamics of PHS radical cations were studied, because PHS radical cation is main source of proton. The transient absorption of PHS was observed in the near-infrared region (NIR) in p-dioxane solutions by pulse radiolysis. The intramolecular PHS dimer radical cation (M2 +.) were observed, whereas p-cresol shows no distinct CR band. Although the radical cations of phenol derivatives are known to be easily deprotonated, it was found that M2 +. formation prevents deprotonation by its charge resonance stabilization.

  9. Cation induced electrochromism in 2,4-dinitrophenylhydrazine (DNPH): Tuning optical properties of aromatic rings

    NASA Astrophysics Data System (ADS)

    Sanader, Željka; Brunet, Claire; Broyer, Michel; Antoine, Rodolphe; Dugourd, Philippe; Mitrić, Roland; Bonačić-Koutecký, Vlasta

    2013-05-01

    We have theoretically investigated the influence of protons and noble metal cations on optical properties of 2,4-dinitrophenylhydrazine (DNPH). We show that optical properties of aromatic rings can be tuned by cation-induced electrochromism in DNPH due to binding to specific NO2 groups. Our findings on cation-induced electrochromism in DNPH may open new routes in two different application areas, due to the fact that DNPH can easily bind to biological molecules and surface materials through carbonyl groups.

  10. Restructuring of a Peat in Interaction with Multivalent Cations: Effect of Cation Type and Aging Time

    PubMed Central

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J. A.; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al3+, Ca2+ or Na+, respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>>2 h) than deprotonation of functional groups (<2 h) and was described by a Langmuir model. The maximum uptake increased with pH of cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for Ca

  11. Acoustic bubble removal method

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

    1983-01-01

    A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.

  12. Easily regenerable solid adsorbents based on polyamines for carbon dioxide capture from the air.

    PubMed

    Goeppert, Alain; Zhang, Hang; Czaun, Miklos; May, Robert B; Prakash, G K Surya; Olah, George A; Narayanan, S R

    2014-05-01

    Adsorbents prepared easily by impregnation of fumed silica with polyethylenimine (PEI) are promising candidates for the capture of CO2 directly from the air. These inexpensive adsorbents have high CO2 adsorption capacity at ambient temperature and can be regenerated in repeated cycles under mild conditions. Despite the very low CO2 concentration, they are able to scrub efficiently all CO2 out of the air in the initial hours of the experiments. The influence of parameters such as PEI loading, adsorption and desorption temperature, particle size, and PEI molecular weight on the adsorption behavior were investigated. The mild regeneration temperatures required could allow the use of waste heat available in many industrial processes as well as solar heat. CO2 adsorption from the air has a number of applications. Removal of CO2 from a closed environment, such as a submarine or space vehicles, is essential for life support. The supply of CO2-free air is also critical for alkaline fuel cells and batteries. Direct air capture of CO2 could also help mitigate the rising concerns about atmospheric CO2 concentration and associated climatic changes, while, at the same time, provide the first step for an anthropogenic carbon cycle. PMID:24644023

  13. Easily Regenerable Solid Adsorbents Based on Polyamines for Carbon Dioxide Capture from the Air

    SciTech Connect

    Goeppert, A; Zhang, H; Czaun, M; May, RB; Prakash, GKS; Olah, GA; Narayanan, SR

    2014-03-18

    Adsorbents prepared easily by impregnation of fumed silica with polyethylenimine (PEI) are promising candidates for the capture of CO2 directly from the air. These inexpensive adsorbents have high CO2 adsorption capacity at ambient temperature and can be regenerated in repeated cycles under mild conditions. Despite the very low CO2 concentration, they are able to scrub efficiently all CO2 out of the air in the initial hours of the experiments. The influence of parameters such as PEI loading, adsorption and desorption temperature, particle size, and PEI molecular weight on the adsorption behavior were investigated. The mild regeneration temperatures required could allow the use of waste heat available in many industrial processes as well as solar heat. CO2 adsorption from the air has a number of applications. Removal of CO2 from a closed environment, such as a submarine or space vehicles, is essential for life support. The supply of CO2-free air is also critical for alkaline fuel cells and batteries. Direct air capture of CO2 could also help mitigate the rising concerns about atmospheric CO2 concentration and associated climatic changes, while, at the same time, provide the first step for an anthropogenic carbon cycle.

  14. Silica-based cationic bilayers as immunoadjuvants

    PubMed Central

    Lincopan, Nilton; Santana, Mariana RA; Faquim-Mauro, Eliana; da Costa, Maria Helena B; Carmona-Ribeiro, Ana M

    2009-01-01

    Background Silica particles cationized by dioctadecyldimethylammonium bromide (DODAB) bilayer were previously described. This work shows the efficiency of these particulates for antigen adsorption and presentation to the immune system and proves the concept that silica-based cationic bilayers exhibit better performance than alum regarding colloid stability and cellular immune responses for vaccine design. Results Firstly, the silica/DODAB assembly was characterized at 1 mM NaCl, pH 6.3 or 5 mM Tris.HCl, pH 7.4 and 0.1 mg/ml silica over a range of DODAB concentrations (0.001–1 mM) by means of dynamic light scattering for particle sizing and zeta-potential analysis. 0.05 mM DODAB is enough to produce cationic bilayer-covered particles with good colloid stability. Secondly, conditions for maximal adsorption of bovine serum albumin (BSA) or a recombinant, heat-shock protein from Mycobacterium leprae (18 kDa-hsp) onto DODAB-covered or onto bare silica were determined. At maximal antigen adsorption, cellular immune responses in vivo from delayed-type hypersensitivity reactions determined by foot-pad swelling tests (DTH) and cytokines analysis evidenced the superior performance of the silica/DODAB adjuvant as compared to alum or antigens alone whereas humoral response from IgG in serum was equal to the one elicited by alum as adjuvant. Conclusion Cationized silica is a biocompatible, inexpensive, easily prepared and possibly general immunoadjuvant for antigen presentation which displays higher colloid stability than alum, better performance regarding cellular immune responses and employs very low, micromolar doses of cationic and toxic synthetic lipid. PMID:19152701

  15. Modelling how incorporation of divalent cations affects calcite wettability–implications for biomineralisation and oil recovery

    NASA Astrophysics Data System (ADS)

    Andersson, M. P.; Dideriksen, K.; Sakuma, H.; Stipp, S. L. S.

    2016-06-01

    Using density functional theory and geochemical speciation modelling, we predicted how solid-fluid interfacial energy is changed, when divalent cations substitute into a calcite surface. The effect on wettability can be dramatic. Trace metal uptake can impact organic compound adsorption, with effects for example, on the ability of organisms to control crystal growth and our ability to predict the wettability of pore surfaces. Wettability influences how easily an organic phase can be removed from a surface, either organic compounds from contaminated soil or crude oil from a reservoir. In our simulations, transition metals substituted exothermically into calcite and more favourably into sites at the surface than in the bulk, meaning that surface properties are more strongly affected than results from bulk experiments imply. As a result of divalent cation substitution, calcite-fluid interfacial energy is significantly altered, enough to change macroscopic contact angle by tens of degrees. Substitution of Sr, Ba and Pb makes surfaces more hydrophobic. With substitution of Mg and the transition metals, calcite becomes more hydrophilic, weakening organic compound adsorption. For biomineralisation, this provides a switch for turning on and off the activity of organic crystal growth inhibitors, thereby controlling the shape of the associated mineral phase.

  16. Modelling how incorporation of divalent cations affects calcite wettability-implications for biomineralisation and oil recovery.

    PubMed

    Andersson, M P; Dideriksen, K; Sakuma, H; Stipp, S L S

    2016-01-01

    Using density functional theory and geochemical speciation modelling, we predicted how solid-fluid interfacial energy is changed, when divalent cations substitute into a calcite surface. The effect on wettability can be dramatic. Trace metal uptake can impact organic compound adsorption, with effects for example, on the ability of organisms to control crystal growth and our ability to predict the wettability of pore surfaces. Wettability influences how easily an organic phase can be removed from a surface, either organic compounds from contaminated soil or crude oil from a reservoir. In our simulations, transition metals substituted exothermically into calcite and more favourably into sites at the surface than in the bulk, meaning that surface properties are more strongly affected than results from bulk experiments imply. As a result of divalent cation substitution, calcite-fluid interfacial energy is significantly altered, enough to change macroscopic contact angle by tens of degrees. Substitution of Sr, Ba and Pb makes surfaces more hydrophobic. With substitution of Mg and the transition metals, calcite becomes more hydrophilic, weakening organic compound adsorption. For biomineralisation, this provides a switch for turning on and off the activity of organic crystal growth inhibitors, thereby controlling the shape of the associated mineral phase. PMID:27352933

  17. Modelling how incorporation of divalent cations affects calcite wettability–implications for biomineralisation and oil recovery

    PubMed Central

    Andersson, M. P.; Dideriksen, K.; Sakuma, H.; Stipp, S. L. S.

    2016-01-01

    Using density functional theory and geochemical speciation modelling, we predicted how solid-fluid interfacial energy is changed, when divalent cations substitute into a calcite surface. The effect on wettability can be dramatic. Trace metal uptake can impact organic compound adsorption, with effects for example, on the ability of organisms to control crystal growth and our ability to predict the wettability of pore surfaces. Wettability influences how easily an organic phase can be removed from a surface, either organic compounds from contaminated soil or crude oil from a reservoir. In our simulations, transition metals substituted exothermically into calcite and more favourably into sites at the surface than in the bulk, meaning that surface properties are more strongly affected than results from bulk experiments imply. As a result of divalent cation substitution, calcite-fluid interfacial energy is significantly altered, enough to change macroscopic contact angle by tens of degrees. Substitution of Sr, Ba and Pb makes surfaces more hydrophobic. With substitution of Mg and the transition metals, calcite becomes more hydrophilic, weakening organic compound adsorption. For biomineralisation, this provides a switch for turning on and off the activity of organic crystal growth inhibitors, thereby controlling the shape of the associated mineral phase. PMID:27352933

  18. Screw/stud removal tool

    NASA Technical Reports Server (NTRS)

    Daniels, K.; Herrick, D. E.; Rothermel, L.

    1980-01-01

    Tool removes stubborn panheaded screws or studs where conventional tools would be either too weak or inconvenient to use. Screws with damaged heads or slots can also be removed this way. Tool can be worked with one hand and easily fits limited-access and blind areas. It can be made in various sizes to fit different screwheads.

  19. Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

    NASA Astrophysics Data System (ADS)

    Fan, Zhaochuan; Lin, Li-Chiang; Buijs, Wim; Vlugt, Thijs J. H.; van Huis, Marijn A.

    2016-05-01

    Cation exchange is a powerful tool for the synthesis of nanostructures such as core-shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core-shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals.

  20. MLKL forms cation channels

    PubMed Central

    Xia, Bingqing; Fang, Sui; Chen, Xueqin; Hu, Hong; Chen, Peiyuan; Wang, Huayi; Gao, Zhaobing

    2016-01-01

    The mixed lineage kinase domain-like (MLKL) protein is a key factor in tumor necrosis factor-induced necroptosis. Recent studies on necroptosis execution revealed a commitment role of MLKL in membrane disruption. However, our knowledge of how MLKL functions on membrane remains very limited. Here we demonstrate that MLKL forms cation channels that are permeable preferentially to Mg2+ rather than Ca2+ in the presence of Na+ and K+. Moreover, the N-terminal domain containing six helices (H1-H6) is sufficient to form channels. Using the substituted cysteine accessibility method, we further determine that helix H1, H2, H3, H5 and H6 are transmembrane segments, while H4 is located in the cytoplasm. Finally, MLKL-induced membrane depolarization and cell death exhibit a positive correlation to its channel activity. The Mg2+-preferred permeability and five transmembrane segment topology distinguish MLKL from previously identified Mg2+-permeable channels and thus establish MLKL as a novel class of cation channels. PMID:27033670

  1. Adsorptive bubble separation of zinc and cadmium cations in presence of ferric and aluminum hydroxides.

    PubMed

    Jurkiewicz, Kazimierz

    2005-06-15

    The adsorptive bubble separation of zinc and cadmium cations from solution in the presence of ferric and aluminum hydroxides was carried out by means of Tween 80 (nonionic surfactant), and sodium laurate and stearate (anionic surfactants). The mechanism of metal removal is different depending on the nature of the surfactant used. The removal of zinc cations by adsorbing colloid flotation is higher than that of cadmium cations. It increases with increases in the amount of hydroxide precipitate and the concentration of Tween 80. The removal of zinc cations by ion flotation is lower than that of cadmium cations. It does not change with increases in the hydroxide amount. It increases, however, with increased sodium laurate or stearate concentration. Both separation methods turned out to be helpful for studying both the solution's structure and the interactions at the solution-solid interface. PMID:15897071

  2. The interaction of humic substances with cationic polyelectrolytes.

    PubMed

    Kam, S K; Gregory, J

    2001-10-01

    The anionic charge carried by aquatic humic substances plays a major part in their interaction with metal ions and other cationic species. Removal of such substances by coagulation and flocculation can be, at least partly, determined by charge neutralisation. In this work, the charge densities of a commercial humic acid and an aquatic humic extract have been investigated by studying their interactions with a series of synthetic cationic polyelectrolytes. These covered a range of charge densities and molecular weights. The techniques used were colloid titration by spectrophotometry and streaming current detection, and flocculation determined by colour removal and by an optical monitoring method. For a given cationic polyelectrolyte, all four methods gave charge densities for humic substances which were in good agreement. However, systematic differences in the apparent humic charge density were found, depending on the charge density of the cationic polyelectrolyte used. With low charge density polyelectrolytes, the apparent anionic charge of the humic substances was found to be low. With higher polyelectrolyte charge densities, the apparent humic substance charge density increases and reaches a limiting value when the polyelectrolyte charge is greater than about 3 meq/g. This indicates a non-stoichiometric interaction between the anionic sites of the humic substances and the cationic charges of the low-charge polyelectrolytes. Optimum flocculation of humics occurred with less cationic charge in the case of low-charge polyelectrolytes than those with higher charge density. However, the degree of removal was considerably better in the latter case. In all cases, the molecular weight of the cationic polyelectrolytes (over a range from about 50,000 to 15 million) appeared to have no effect on the results. PMID:11561615

  3. Adenoid removal

    MedlinePlus

    ... This does not cause problems most of the time. Alternative Names Adenoidectomy; Removal of adenoid glands Images Adenoid removal - series References Wetmore RF. Tonsils and adenoids. In: Kliegman ...

  4. Dissecting the cation-cation interaction between two uranyl units.

    PubMed

    Tecmer, Paweł; Hong, Sung W; Boguslawski, Katharina

    2016-07-21

    We present a state-of-the-art computational study of the uranyl(vi) and uranyl(v) cation-cation interactions (dications) in aqueous solution. Reliable electronic structures of two interacting uranyl(vi) and uranyl(v) subunits as well as those of the uranyl(vi) and uranyl(v) clusters are presented for the first time. Our theoretical study elucidates the impact of cation-cation interactions on changes in the molecular structure as well as changes in vibrational and UV-Vis spectra of the bare uranyl(vi) and uranyl(v) moieties for different total spin-states and total charges of the dications. PMID:27335229

  5. Enhanced coagulation for arsenic removal

    SciTech Connect

    Cheng, R.C.; Liang, S.; Wang, H.C.; Beuhler, M.D. )

    1994-09-01

    The possible use of enhanced coagulation for arsenic removal was examined at the facilities of a California utility in 1992 and 1993. The tests were conducted at bench, pilot, and demonstration scales, with two source waters. Alum and ferric chloride, with cationic polymer, were investigated at various influence arsenic concentrations. The investigators concluded that for the source waters tested, enhanced coagulation could be effective for arsenic removal and that less ferric chloride than alum, on a weight basis, is needed to achieve the same removal.

  6. Catalytic Carbocation Generation Enabled by the Mesolytic Cleavage of Alkoxyamine Radical Cations.

    PubMed

    Zhu, Qilei; Gentry, Emily C; Knowles, Robert R

    2016-08-16

    A new catalytic method is described to access carbocation intermediates via the mesolytic cleavage of alkoxyamine radical cations. In this process, electron transfer between an excited state oxidant and a TEMPO-derived alkoxyamine substrate gives rise to a radical cation with a remarkably weak C-O bond. Spontaneous scission results in the formation of the stable nitroxyl radical TEMPO(.) as well as a reactive carbocation intermediate that can be intercepted by a wide range of nucleophiles. Notably, this process occurs under neutral conditions and at comparatively mild potentials, enabling catalytic cation generation in the presence of both acid sensitive and easily oxidized nucleophilic partners. PMID:27403637

  7. The cation-π interaction.

    PubMed

    Dougherty, Dennis A

    2013-04-16

    The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

  8. The Cation-π Interaction

    PubMed Central

    DOUGHERTY, DENNIS A.

    2014-01-01

    CONSPECTUS The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author’s perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forgo aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction – Li+ binds to benzene with 38 kcal/mol of binding energy; NH4+ with 19 kcal/mol– distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2 – 5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) Cδ−–Hδ+ bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li+>Na+>K+>Rb+: as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane

  9. Cationic lipid-mediated nucleic acid delivery: beyond being cationic.

    PubMed

    Rao, N Madhusudhana

    2010-03-01

    Realization of the potential of nucleic acids as drugs is intricately linked to their in vivo delivery. Cationic lipids demonstrated tremendous potential as safe, efficient and scalable in vitro carriers of nucleic acids. For in vivo delivery of nucleic acids, the extant two component liposomal preparations consisting of cationic lipids and nucleic acids have been largely found to be insufficient. Being a soft matter, liposomes readily respond to many physiological variables leading to complex component and morphological changes, thus confounding the efforts in a priori identification of a "competent" formulation. In the recent past many chemical moieties that provide advantage in facing the challenges of barriers in vivo, were incorporated into cationic lipids to improve the transfection efficiency. The cationic lipids, essential for DNA condensation and protection, definitely require additional components to be efficient in vivo. In addition, formulations of cationic lipid carriers with non-lipidic components, mainly peptides, have demonstrated success in in vivo transfection. The present review describes some recent successes of in vivo nucleic acid delivery by cationic lipids. PMID:20060819

  10. Making On-Line Science Course Materials Easily Translatable and Accessible Worldwide: Challenges and Solutions

    ERIC Educational Resources Information Center

    Adams, Wendy K.; Alhadlaq, Hisham; Malley, Christopher V.; Perkins, Katherine K.; Olson, Jonathan; Alshaya, Fahad; Alabdulkareem, Saleh; Wieman, Carl E.

    2012-01-01

    The PhET Interactive Simulations Project partnered with the Excellence Research Center of Science and Mathematics Education at King Saud University with the joint goal of making simulations useable worldwide. One of the main challenges of this partnership is to make PhET simulations and the website easily translatable into any language. The PhET…

  11. Teaching the Assessment of Normality Using Large Easily-Generated Real Data Sets

    ERIC Educational Resources Information Center

    Kulp, Christopher W.; Sprechini, Gene D.

    2016-01-01

    A classroom activity is presented, which can be used in teaching students statistics with an easily generated, large, real world data set. The activity consists of analyzing a video recording of an object. The colour data of the recorded object can then be used as a data set to explore variation in the data using graphs including histograms,…

  12. An easily regenerable enzyme reactor prepared from polymerized high internal phase emulsions.

    PubMed

    Ruan, Guihua; Wu, Zhenwei; Huang, Yipeng; Wei, Meiping; Su, Rihui; Du, Fuyou

    2016-04-22

    A large-scale high-efficient enzyme reactor based on polymerized high internal phase emulsion monolith (polyHIPE) was prepared. First, a porous cross-linked polyHIPE monolith was prepared by in-situ thermal polymerization of a high internal phase emulsion containing styrene, divinylbenzene and polyglutaraldehyde. The enzyme of TPCK-Trypsin was then immobilized on the monolithic polyHIPE. The performance of the resultant enzyme reactor was assessed according to the conversion ability of Nα-benzoyl-l-arginine ethyl ester to Nα-benzoyl-l-arginine, and the protein digestibility of bovine serum albumin (BSA) and cytochrome (Cyt-C). The results showed that the prepared enzyme reactor exhibited high enzyme immobilization efficiency and fast and easy-control protein digestibility. BSA and Cyt-C could be digested in 10 min with sequence coverage of 59% and 78%, respectively. The peptides and residual protein could be easily rinsed out from reactor and the reactor could be regenerated easily with 4 M HCl without any structure destruction. Properties of multiple interconnected chambers with good permeability, fast digestion facility and easily reproducibility indicated that the polyHIPE enzyme reactor was a good selector potentially applied in proteomics and catalysis areas. PMID:26995089

  13. Lightweight and Easily Foldable MCMB-MWCNTs Composite Paper with Exceptional Electromagnetic Interference Shielding.

    PubMed

    Chaudhary, Anisha; Kumari, Saroj; Kumar, Rajeev; Teotia, Satish; Singh, Bhanu Pratap; Singh, Avanish Pratap; Dhawan, S K; Dhakate, Sanjay R

    2016-04-27

    Lightweight and easily foldable with high conductivity, multiwalled carbon nanotube (MWCNT)-based mesocarbon microbead (MCMB) composite paper is prepared using a simple, efficient, and cost-effective strategy. The developed lightweight and conductive composite paper have been reported for the first time as an efficient electromagnetic interference (EMI) shielding material in X-band frequency region having a low density of 0.26 g/cm(3). The investigation revealed that composite paper shows an excellent absorption dominated EMI shielding effectiveness (SE) of -31 to -56 dB at 0.15-0.6 mm thickness, respectively. Specific EMI-SE of as high as -215 dB cm(3)/g exceeds the best values of metal and other low-density carbon-based composites. Additionally, lightweight and easily foldable ability of this composite paper will help in providing stable EMI shielding values even after constant bending. Such intriguing performances open the framework to designing a lightweight and easily foldable composite paper as promising EMI shielding material, especially in next-generation devices and for defense industries. PMID:27035889

  14. Cation Diffusion in Xenotime

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.

    2004-05-01

    Xenotime is an important mineral in metamorphic paragenesis, and useful in isotopic dating, garnet-xenotime thermometry, and monazite-xenotime thermometry, so diffusion data for xenotime of cations of geochronological and geochemical importance are of some interest. We report here on diffusion of the rare earth elements Sm, Dy and Yb in synthetic xenotime under dry conditions. The synthetic xenotime was grown via a Na2}CO{3}-MoO_{3 flux method. The source of diffusant for the experiments were REE phosphate powders, with experiments run with sources containing a single REE. Experiments were performed by placing source and xenotime in Pt capsules, and annealing capsules in 1 atm furnaces for times ranging from thirty minutes to a month, at temperatures from 1000 to 1400C. The REE distributions in the xenotime were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relations are obtained for diffusion in xenotime, normal to (101): DSm = 1.7x10-4 exp(-442 kJ mol-1/RT) m2}sec{-1 DDy = 3.5x10-7 exp(-365 kJ mol-1/RT) m2}sec{-1 DYb = 7.4x10-7 exp(-371 kJ mol-1/RT) m2}sec{-1. Diffusivities of these REE do not differ greatly in xenotime, in contrast to the findings noted for the REE in zircon (Cherniak et al., 1997), where the LREE diffuse more slowly, and with higher activation energies for diffusion, than the heavier rare earths. In zircon, these differences among diffusion of the rare earths are attributed to the relatively large size of the REE with respect to Zr, for which they substitute in the zircon lattice. With the systematic increase in ionic radius from the heavy to lighter REE, this size mismatch becomes more pronounced and diffusivities of the LREE are as consequence slower. Although xenotime is isostructural with zircon, the REE are more closely matched in size to Y, so in xenotime this effect appears much smaller and the REE diffuse at similar rates. In addition, the process of diffusion in xenotime likely involves simple REE+3

  15. Alloyed Copper Chalcogenide Nanoplatelets via Partial Cation Exchange Reactions

    PubMed Central

    2014-01-01

    We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide–sulfide (CZSeS), copper tin selenide–sulfide (CTSeS), and copper zinc tin selenide–sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide–sulfide (Cu2–xSeyS1–y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2–xSeyS1–y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV–vis–NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps. PMID:25050455

  16. Broad Scope Aminocyclization of Enynes with Cationic JohnPhos–Gold(I) Complex as the Catalyst

    PubMed Central

    2016-01-01

    A practical aminocyclization of 1,6-enynes with a wide variety of substituted anilines, including N-alkyl anilines, has been achived by using cationic [JohnPhosAu(MeCN)]SbF6 as a general purpose catalyst. The resulting adducts can be easily converted into polycyclic compounds by palladium- and gold-catalyzed reactions. PMID:26839084

  17. Kidney removal

    MedlinePlus

    ... the surgical cut is located. Recovery after a laparoscopic procedure is most often quicker, with less pain. Outlook (Prognosis) The outcome is most often good when a single kidney is removed. If both kidneys are removed, ...

  18. Tick Removal

    MedlinePlus

    ... ticks Tickborne diseases abroad Borrelia miyamotoi Borrelia mayonii Tick Removal Recommend on Facebook Tweet Share Compartir If ... a tick quite effectively. How to remove a tick Use fine-tipped tweezers to grasp the tick ...

  19. Removing Solids From Supercritical Water

    NASA Technical Reports Server (NTRS)

    Hong, Glenn T.

    1992-01-01

    Apparatus removes precipitated inorganic salts and other solids in water-recycling process. Designed for use with oxidation in supercritical water which treats wastes and yields nearly pure water. Heating coils and insulation around vessel keep it hot. Locking bracket seals vessel but allows it to be easily opened for replacement of filled canisters.

  20. Cation Ordering in Layered Nickelates

    NASA Astrophysics Data System (ADS)

    Nelson-Cheeseman, Brittany; Zhou, Hua; Cammarata, Antonio; Hoffman, Jason; Balachandran, Prasanna; Rondinelli, James; Bhattacharya, Anand

    2013-03-01

    The single layer Ruddlesden-Popper nickelates present a model system to understand how the effects of digital dopant cation ordering may affect the properties of 2-dimensional conducting sheets. We investigate the effects of aliovalent A-site cation order on LaSrNiO4 films. Using molecular beam epitaxy, we interleave full layers of SrO and LaO in a series of chemically equivalent films, varying the pattern of SrO and LaO layers relative to the NiO2 layers. Through synchrotron surface x-ray diffraction and Coherant Bragg Rod Analysis (COBRA), we directly investigate the A-site cation order and the resulting atomic displacements for each ordering pattern. We correlate these results with theoretical calculations and transport measurements of the layered nickelate films.

  1. A transportable and easily configurable multi-projector display system for distributed virtual reality applications

    NASA Astrophysics Data System (ADS)

    Grimes, Holly; McMenemy, Karen R.; Ferguson, R. S.

    2008-02-01

    This paper details how simple PC software, a small network of consumer level PCs, some do-it-yourself hardware and four low cost video projectors can be combined to form an easily configurable and transportable projection display with applications in virtual reality training. This paper provides some observations on the practical difficulties of using such a system, its effectiveness in delivering a VE for training and what benefit may be offered through the deployment of a large number of these low cost environments.

  2. Safe, Effective and Easily Reproducible Fusion Technique for CV Junction Instability

    PubMed Central

    Sannegowda, Raghavendra Bakki

    2015-01-01

    Introduction: The Craniovertebral junction (CVJ) refers to a bony enclosure where the occipital bone surrounds the foramen magnum, the atlas and the axis vertebrae. Because of the complexity of structures, CVJ instability is associated with diagnostic and therapeutic problems. Posterior CV fusion procedures have evolved a lot over the last couple of decades. There has been a lookout for one such surgical procedure which is inherently safe, simple, easily reproducible and biomechanically sound. In our study, we present the initial experience the cases of CV junction instrumentation using O-C1-C2 screw & rod construct operated by the author. Aims and Objectives: The current study is a descriptive analysis of the cases of CVJ instability treated by us with instrumentation using O-C1-C2 screw and rod construct fusion technique. Materials and Methods: It is a retrospective, analytical study in which cases of CV junction instability operated by the author between January 2010 to March 2014 were analysed using various clinical, radiological and outcome parameters. Conclusion: CV junction instrumentation using O-C1-C2 screw and rod construct fusion technique proved to be safe, effective, easily reproducible and biomechanically sound technique which can be adopted by all surgeons who may be at any stage of their learning curve. PMID:25954660

  3. Potassium Niobate Nanolamina: A Promising Adsorbent for Entrapment of Radioactive Cations from Water

    PubMed Central

    Sun, Jin; Yang, Dongjiang; Sun, Cuihua; Liu, Long; Yang, Shuanglei; (Alec) Jia, Yi; Cai, Rongsheng; Yao, Xiangdong

    2014-01-01

    Processing and managing radioactive waste is a great challenge worldwide as it is extremely difficult and costly; the radioactive species, cations or anions, leaked into the environment are a serious threat to the health of present and future generations. We report layered potassium niobate (K4Nb6O17) nanolamina as adsorbent to remove toxic Sr2+, Ba2+ and Cs+ cations from wastewater. The results show that K4Nb6O17 nanolamina can permanently confine the toxic cations within the interlayer spacing via a considerable deformation of the metastable layered structure during the ion exchange process. At the same time, the nanolaminar adsorbent exhibits prompt adsorption kinetics, high adsorption capacity and selectivity, and superior acid resistance. These merits make it be a promising material as ion exchanger for the removal of radioactive cations from wastewater. PMID:25472721

  4. Cation-cation interactions and cation exchange in a series of isostructural framework uranyl tungstates

    NASA Astrophysics Data System (ADS)

    Balboni, Enrica; Burns, Peter C.

    2014-05-01

    The isotypical compounds (UO2)3(WO6)(H2O)5 (1), Ag(UO2)3(WO6)(OH)(H2O)3 (2), K(UO2)3(WO6)OH(H2O)4 (3), Rb(UO2)3(WO6)(OH)(H2O)3.5 (4), and Cs(UO2)3(WO6)OH(H2O)3 (5) were synthesized, characterized, and their structures determined. Each crystallizes in space group Cc. (1): a=12.979 (3), b=10.238 (2), c=11.302 (2), β=102.044 (2); (2): a=13.148 (2), b=9.520 (1), c=11.083 (2), β=101.568 (2); (3): a=13.111 (8), b=9.930 (6), c=11.242 (7), β=101.024 (7); (4): a=12.940 (2), b=10.231 (2), c=11.259(2), β=102.205 (2); (5): a=12.983 (3), b=10.191 (3), c=11.263 (4), β=101.661 (4). Compounds 1-5 are a framework of uranyl and tungsten polyhedra containing cation-cation interactions. The framework has three symmetrically distinct U(VI) cations, one tungsten, sixteen to eighteen oxygen atoms, and in 2-5, one monovalent cation. Each atom occupies a general position. Each U(VI) cation is present as a typical (UO2)2+ uranyl ion in an overall pentagonal bipyramidal coordination environment. Each pentagonal bipyramid shares two equatorial edges with two other pentagonal bipyramids, forming a trimer. Trimers are connected into chains by edge-sharing with WO6 octahedra. Chains are linked through cation-cation interactions between two symmetrically independent uranyl ions. This yields a remarkably complex system of intersecting channels that extend along [0 0 1] and [-1 1 0]. The cation exchange properties of 2 and 3 were characterized at room temperature and at 140 °C.

  5. Hot Oil Removes Wax

    NASA Technical Reports Server (NTRS)

    Herzstock, James J.

    1991-01-01

    Mineral oil heated to temperature of 250 degrees F (121 degrees C) found effective in removing wax from workpieces after fabrication. Depending upon size and shape of part to be cleaned of wax, part immersed in tank of hot oil, and/or interior of part flushed with hot oil. Pump, fittings, and ancillary tooling built easily for this purpose. After cleaning, innocuous oil residue washed off part by alkaline aqueous degreasing process. Serves as relatively safe alternative to carcinogenic and environmentally hazardous solvent perchloroethylene.

  6. Removing Bonded Integrated Circuits From Boards

    NASA Technical Reports Server (NTRS)

    Rice, John T.

    1989-01-01

    Small resistance heater makes it easier, faster, and cheaper to remove integrated circuit from hybrid-circuit board, package, or other substrate for rework. Heater, located directly in polymeric bond interface or on substrate under integrated-circuit chip, energized when necessary to remove chip. Heat generated softens adhesive or solder that bonds chip to substrate. Chip then lifted easily from substrate.

  7. A 2D zinc-organic network being easily exfoliated into isolated sheets

    NASA Astrophysics Data System (ADS)

    Yu, Guihong; Li, Ruiqing; Leng, Zhihua; Gan, Shucai

    2016-08-01

    A metal-organic aggregate, namely {Zn2Cl2(BBC)}n (BBC = 4,4‧,4‧‧-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate) was obtained by solvothermal synthesis. Its structure is featured with the Zn2(COO)3 paddle-wheels with two chloride anions on axial positions and hexagonal pores in the layers. The exclusion of water in the precursor and the solvent plays a crucial role in the formation of target compound. This compound can be easily dissolved in alkaline solution and exfoliated into isolated sheets, which shows a novel way for the preparation of 2D materials.

  8. Solving block linear systems with low-rank off-diagonal blocks is easily parallelizable

    SciTech Connect

    Menkov, V.

    1996-12-31

    An easily and efficiently parallelizable direct method is given for solving a block linear system Bx = y, where B = D + Q is the sum of a non-singular block diagonal matrix D and a matrix Q with low-rank blocks. This implicitly defines a new preconditioning method with an operation count close to the cost of calculating a matrix-vector product Qw for some w, plus at most twice the cost of calculating Qw for some w. When implemented on a parallel machine the processor utilization can be as good as that of those operations. Order estimates are given for the general case, and an implementation is compared to block SSOR preconditioning.

  9. An easily Prepared Fluorescent pH Probe Based on Dansyl.

    PubMed

    Sha, Chunming; Chen, Yuhua; Chen, Yufen; Xu, Dongmei

    2016-09-01

    A novel fluorescent pH probe from dansyl chloride and thiosemicarbazide was easily prepared and fully characterized by (1)H NMR, (13)C NMR, LC-MS, Infrared spectra and elemental analysis. The probe exhibited high selectivity and sensitivity to H(+) with a pK a value of 4.98. The fluorescence intensity at 510 nm quenched 99.5 % when the pH dropped from 10.88 to 1.98. In addition, the dansyl-based probe could respond quickly and reversibly to the pH variation and various common metal ions showed negligible interference. The recognition could be ascribed to the intramolecular charge transfer caused by the protonation of the nitrogen in the dimethylamino group. PMID:27333798

  10. The study on development of easily chewable and swallowable foods for elderly

    PubMed Central

    Kim, Soojeong

    2015-01-01

    BACKGROUND/OBJECTS When the functions involved in the ingestion of food occurs failure, not only loss of enjoyment of eating, it will be faced with protein-energy malnutrition. Dysmasesis and difficulty of swallowing occurs in various diseases, but it may be a major cause of aging, and elderly people with authoring and dysmasesis and difficulty of swallowing in the aging society is expected to increase rapidly. SUBJECTS/METHODS In this study, we carried out a survey targeting nutritionists who work in elderly care facilities, and examined characteristics of offering of foods for elderly and the degree of demand of development of easily chewable and swallowable foods for the elderly who can crush foods and take that by their own tongues, and sometimes have difficulty in drinking water and tea. RESULTS In elderly care facilities, it was found to provide a finely chopped food or ground food that was ground with water in a blender for elderly with dysmasesis. Elderly satisfaction of provided foods is appeared overall low. Results of investigating the applicability of foods for elderly and the reflection will of menus, were showed the highest response rate in a gelification method in molecular gastronomic science technics, and results of investigating the frequent food of the elderly; representative menu of beef, pork, white fish, anchovies and spinach, were showed Korean barbecue beef, hot pepper paste stir fried pork, pan fried white fish, stir fried anchovy, seasoned spinach were the highest offer frequency. CONCLUSIONS This study will provide the fundamentals of the development of easily chewable and swallowable foods, gelification, for the elderly. The study will also illustrate that, in the elderly, food undergone gelification will reduce the risk of swallowing down to the wrong pipe and improve overall food preference. PMID:26244082

  11. Easily processable multimodal spectral converters based on metal oxide/organic—inorganic hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    Julián-López, Beatriz; Gonell, Francisco; Lima, Patricia P.; Freitas, Vânia T.; André, Paulo S.; Carlos, Luis D.; Ferreira, Rute A. S.

    2015-10-01

    This manuscript reports the synthesis and characterization of the first organic-inorganic hybrid material exhibiting efficient multimodal spectral converting properties. The nanocomposite, made of Er3+, Yb3+ codoped zirconia nanoparticles (NPs) entrapped in a di-ureasil d-U(600) hybrid matrix, is prepared by an easy two-step sol-gel synthesis leading to homogeneous and transparent materials that can be very easily processed as monolith or film. Extensive structural characterization reveals that zirconia nanocrystals of 10-20 nm in size are efficiently dispersed into the hybrid matrix and that the local structure of the di-ureasil is not affected by the presence of the NPs. A significant enhancement in the refractive index of the di-ureasil matrix with the incorporation of the ZrO2 nanocrystals is observed. The optical study demonstrates that luminescent properties of both constituents are perfectly preserved in the final hybrid. Thus, the material displays a white-light photoluminescence from the di-ureasil component upon excitation at UV/visible radiation and also intense green and red emissions from the Er3+- and Yb3+-doped NPs after NIR excitation. The dynamics of the optical processes were also studied as a function of the lanthanide content and the thickness of the films. Our results indicate that these luminescent hybrids represent a low-cost, environmentally friendly, size-controlled, easily processed and chemically stable alternative material to be used in light harvesting devices such as luminescent solar concentrators, optical fibres and sensors. Furthermore, this synthetic approach can be extended to a wide variety of luminescent NPs entrapped in hybrid matrices, thus leading to multifunctional and versatile materials for efficient tuneable nonlinear optical nanodevices.

  12. Easily processable multimodal spectral converters based on metal oxide/organic-inorganic hybrid nanocomposites.

    PubMed

    Julián-López, Beatriz; Gonell, Francisco; Lima, Patricia P; Freitas, Vânia T; André, Paulo S; Carlos, Luis D; Ferreira, Rute A S

    2015-10-01

    This manuscript reports the synthesis and characterization of the first organic-inorganic hybrid material exhibiting efficient multimodal spectral converting properties. The nanocomposite, made of Er(3+), Yb(3+) codoped zirconia nanoparticles (NPs) entrapped in a di-ureasil d-U(600) hybrid matrix, is prepared by an easy two-step sol-gel synthesis leading to homogeneous and transparent materials that can be very easily processed as monolith or film. Extensive structural characterization reveals that zirconia nanocrystals of 10-20 nm in size are efficiently dispersed into the hybrid matrix and that the local structure of the di-ureasil is not affected by the presence of the NPs. A significant enhancement in the refractive index of the di-ureasil matrix with the incorporation of the ZrO2 nanocrystals is observed. The optical study demonstrates that luminescent properties of both constituents are perfectly preserved in the final hybrid. Thus, the material displays a white-light photoluminescence from the di-ureasil component upon excitation at UV/visible radiation and also intense green and red emissions from the Er(3+)- and Yb(3+)-doped NPs after NIR excitation. The dynamics of the optical processes were also studied as a function of the lanthanide content and the thickness of the films. Our results indicate that these luminescent hybrids represent a low-cost, environmentally friendly, size-controlled, easily processed and chemically stable alternative material to be used in light harvesting devices such as luminescent solar concentrators, optical fibres and sensors. Furthermore, this synthetic approach can be extended to a wide variety of luminescent NPs entrapped in hybrid matrices, thus leading to multifunctional and versatile materials for efficient tuneable nonlinear optical nanodevices. PMID:26374133

  13. Estimation of nutrient values of pig slurries in Southeast Spain using easily determined properties.

    PubMed

    Moral, R; Perez-Murcia, M D; Perez-Espinosa, A; Moreno-Caselles, J; Paredes, C

    2005-01-01

    The contents of available nutrients in pig slurries are not easy to quantify in situ without laboratory facilities, but chemical analyses using standard laboratory methods also take time and are costly and not practical for most farms. Thus, when animal slurries are applied to land, their fertiliser potential is often unknown. In addition, in the last years, the changes in the management of industrial piggeries has changed the nature of the pig slurries vg. decrease of the dry matter content, and consequently the methods and equations used for estimating the nutrient contents in these residues must be checked. In our study, slurry samples were collected from the storage tanks of 36 commercial farms in Southeast Spain. Samples were analysed for pH, electrical conductivity (EC), redox potential (RP), specific density (D), total solids (TS), sedimentable solids (SS), biological oxygen demand (BOD(5)), chemical oxygen demand (COD), total nitrogen (TKN), ammonium nitrogen (AN), organic nitrogen (ON), and total contents of phosphorus, potassium, calcium and magnesium. Relationships between major nutrient levels of pig slurries and a range of physical and chemical properties were investigated. We also analysed the variability of pig slurries according to the production stage. TKN, AN and K were closely related to EC. The P content in slurries was related more closely to solids-derived parameters such as D. The use of multiple properties to estimate nutrient contents in pig slurries, especially for AN and K, seemed unnecessary due to the limited improvement achieved with an additional property. Therefore, electrical conductivity seemed to be the most appropriate single, easily determined parameter for estimation of total and ammonium nitrogen and potassium in pig slurries, with more than 83% of the variance explained. P seemed to be the worst key nutrient for estimation using any easily determined parameter. PMID:16009306

  14. Effects of easily ionizable elements on the liquid sampling atmospheric pressure glow discharge

    NASA Astrophysics Data System (ADS)

    Venzie, Jacob L.; Marcus, R. Kenneth

    2006-06-01

    A series of studies has been undertaken to determine the susceptibility of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) atomic emission source to easily ionizable element (EIE) effects. The initial portions of the study involved monitoring the voltage drop across the plasma as a function of the pH to ascertain whether or not the conductivity of the liquid eluent alters the plasma energetics and subsequently the analyte signal strength. It was found that altering the pH (0.0 to 2.0) in the sample matrix did not significantly change the discharge voltage. The emission signal intensities for Cu(I) 327.4 nm, Mo(I) 344.7 nm, Sc(I) 326.9 nm and Hg(I) 253.6 nm were measured as a function of the easily ionizable element (sodium and calcium) concentration in the injection matrix. A range of 0.0 to 0.1% (w/v) EIE in the sample matrix did not cause a significant change in the Cu, Sc, and Mo signal-to-background ratios, with only a slight change noted for Hg. In addition to this test of analyte response, the plasma energetics as a function of EIE concentration are assessed using the ratio of Mg(II) to Mg(I) (280.2 nm and 285.2 nm, respectively) intensities. The Mg(II)/Mg(I) ratio showed that the plasma energetics did not change significantly over the same range of EIE addition. These results are best explained by the electrolytic nature of the eluent acting as an ionic (and perhaps spectrochemical) buffer.

  15. Halogenated silanes, radicals, and cations

    NASA Astrophysics Data System (ADS)

    Wang, Liming; He, Yi-Liang

    2008-09-01

    Quantum chemistry study has been carried out on the structure and energetics of halogenated silanes, radicals, and cations (SiHxXy0,+1, X = F, Cl, Br; x + y = 1-4). The geometries are optimized at B3LYP/6-31+G(2df,p) level. The adiabatic ionization energiess (IEas), relative energetics of cations, proton affinities (PAs) of silanes, and the enthalpies of formation are predicted using G3(CC) model chemistry. Non-classical ion complex structures are found for hydrogenated cations and transition states connecting classical and non-classical structures are also located. The most stable cations for silylene and silyl radicals have their classical divalent and trivalent structures, and those for silanes have non-classical structures except for SiH3Br+ and SiH2Br2+. The non-classical structures for halosilane cations imply difficulty in experimentally measurement of the adiabatic ionization energies using photoionization or photoelectron studies. For SiH3X, SiH2X2, and SiHX3, the G3(CC) adiabatic IEas to classical ionic structures closest to their neutrals agree better with the photoelectron spectroscopic measurements. The transition states between classical and non-classical structures also hamper the photoionization determination of the appearance energies for silylene cations from silanes. The G3(CC) results for SiHx0,+1 agree excellently with the photoionization mass spectrometric study, and the results for fluorinated and chlorinated species also agree with the previous theoretical predictions at correlation levels from BAC-MP4 to CCSD(T)/CBS. The predicted enthalpy differences between SiH2Cl+, SiHCl2+, and SiCl3+ are also in accordance with previous kinetics study. The G3(CC) results show large discrepancies to the collision-induced charge transfer and/or dissociation reactions involving SiFx+ and SiClx+ ions, for which the G3(CC) enthalpies of formation are also significantly differed from the previous theoretical predictions, especially on SiFx+ (x = 2-4). The G3

  16. Fly ash adsorbents for multi-cation wastewater treatment

    NASA Astrophysics Data System (ADS)

    Visa, Maria; Isac, Luminita; Duta, Anca

    2012-06-01

    Class "F" fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO2/Al2O3 over 2.4 proved good adsorbent properties, and was further used for obtaining a new substrate with good adsorption capacity for heavy metals from multi-cation wastewater treatment. Firstly, the new adsorbent was characterized by AFM, XRD, DSC, FTIR and the surface energy was evaluated by contact angle measurements. The experimental data suggested that the new type of substrate is predominant crystalline with highly polar surface. The substrate was used for removing the Pb2+, Cd2+ and Zn2+ cations from mixed solutions. The results show high efficiency and selective adsorption the Pb2+ and Zn2+ cations. The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes. The Langmuir and Freundlich models were used to describe the processes. The pseudo-second order kinetics could well model all the processes, indicating a surface concentration of the adsorption sites with the same order of magnitude as the cation concentrations.

  17. Method of making thermally removable epoxies

    DOEpatents

    Loy, Douglas A.; Wheeler, David R.; Russick, Edward M.; McElhanon, James R.; Saunders, Randall S.

    2002-01-01

    A method of making a thermally-removable epoxy by mixing a bis(maleimide) compound to a monomeric furan compound containing an oxirane group to form a di-epoxy mixture and then adding a curing agent at temperatures from approximately room temperature to less than approximately 90.degree. C. to form a thermally-removable epoxy. The thermally-removable epoxy can be easily removed within approximately an hour by heating to temperatures greater than approximately 90.degree. C. in a polar solvent. The epoxy material can be used in protecting electronic components that may require subsequent removal of the solid material for component repair, modification or quality control.

  18. Compositions and methods for removal of toxic metals and radionuclides

    NASA Technical Reports Server (NTRS)

    Cuero, Raul G. (Inventor); McKay, David S. (Inventor)

    2007-01-01

    The present invention relates to compositions and methods for the removal of toxic metals or radionuclides from source materials. Toxic metals may be removed from source materials using a clay, such as attapulgite or highly cationic bentonite, and chitin or chitosan. Toxic metals may also be removed using volcanic ash alone or in combination with chitin or chitosan. Radionuclides may be removed using volcanic ash alone or in combination with chitin or chitosan.

  19. Cationic electrodepositable coating composition comprising lignin

    DOEpatents

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  20. Gaseous protein cations are amphoteric

    SciTech Connect

    Stephenson, J.L. Jr.; McLuckey, S.A.

    1997-02-19

    Singly- and multiply-protonated ubiquitin molecules are found to react with iodide anions, and certain other anions, by attachment of the anion, in competition with proton transfer to the anion. The resulting adduct ions are relatively weakly bound and dissociate upon collisional activation by loss of the neutral acid derived from the anion. Adduct ions that behave similarly can also be formed via ion/molecule reactions involving the neutral acid. The ion/molecule reaction phenomenology, however, stands in contrast with that expected based on the reaction site(s) being charged. Reaction rates increase inversely with charge state and the total number of neutral molecules that add to the protein cations increases inversely with cation charge. These observations are inconsistent with the formation of proton-bound clusters but are fully consistent with the formation of ion pairs or dipole/dipole bonding involving the neutral acid and neutral basic sites in the protein. The ion/ion reactions can be interpreted on the basis of conjugate acid/base chemistry in which the anion, which is a strong gaseous base, reacts with a protonated site, which is a strong gaseous acid. Adduct ions can also be formed via ion/molecule reaction which, on the basis of microscopic reversibility, implies that the neutral acid interacts with neutral basic sites on the protein cation. 26 refs., 10 figs., 1 tab.

  1. Easily installable wireless behavioral monitoring system with electric field sensor for ordinary houses.

    PubMed

    Tsukamoto, S; Hoshino, H; Tamura, T

    2008-01-01

    This paper describes an indoor behavioral monitoring system for improving the quality of life in ordinary houses. It employs a device that uses weak radio waves for transmitting the obtained data and it is designed such that it can be installed by a user without requiring any technical knowledge or extra constructions. This study focuses on determining the usage statistics of home electric appliances by using an electromagnetic field sensor as a detection device. The usage of the home appliances is determined by measuring the electromagnetic field that can be observed in an area near the appliance. It is assumed that these usage statistics could provide information regarding the indoor behavior of a subject. Since the sensor is not direction sensitive and does not require precise positioning and wiring, it can be easily installed in ordinary houses by the end users. For evaluating the practicability of the sensor unit, several simple tests have been performed. The results indicate that the proposed system could be useful for collecting the usage statistics of home appliances. PMID:19415135

  2. Sexual dimorphism in venom chemistry in Tetragnatha spiders is not easily explained by adult niche differences.

    PubMed

    Binford, Greta J; Gillespie, Rosemary G; Maddison, Wayne P

    2016-05-01

    Spider venom composition typically differs between sexes. This pattern is anecdotally thought to reflect differences in adult feeding biology. We used a phylogenetic approach to compare intersexual venom dimorphism between species that differ in adult niche dimorphism. Male and female venoms were compared within and between related species of Hawaiian Tetragnatha, a mainland congener, and outgroups. In some species of Hawaiian Tetragnatha adult females spin orb-webs and adult males capture prey while wandering, while in other species both males and females capture prey by wandering. We predicted that, if venom sexual dimorphism is primarily explained by differences in adult feeding biology, species in which both sexes forage by wandering would have monomorphic venoms or venoms with reduced dimorphism relative to species with different adult feeding biology. However, we found striking sexual dimorphism in venoms of both wandering and orb-weaving Tetragnatha species with males having high molecular weight components in their venoms that were absent in females, and a reduced concentration of low molecular weight components relative to females. Intersexual differences in venom composition within Tetragnatha were significantly larger than in non-Tetragnatha species. Diet composition was not different between sexes. This striking venom dimorphism is not easily explained by differences in feeding ecology or behavior. Rather, we hypothesize that the dimorphism reflects male-specific components that play a role in mating biology possibly in sexual stimulation, nuptial gifts and/or mate recognition. PMID:26908290

  3. Open Window: When Easily Identifiable Genomes and Traits Are in the Public Domain

    PubMed Central

    Angrist, Misha

    2014-01-01

    “One can't be of an enquiring and experimental nature, and still be very sensible.” - Charles Fort [1] As the costs of personal genetic testing “self-quantification” fall, publicly accessible databases housing people's genotypic and phenotypic information are gradually increasing in number and scope. The latest entrant is openSNP, which allows participants to upload their personal genetic/genomic and self-reported phenotypic data. I believe the emergence of such open repositories of human biological data is a natural reflection of inquisitive and digitally literate people's desires to make genomic and phenotypic information more easily available to a community beyond the research establishment. Such unfettered databases hold the promise of contributing mightily to science, science education and medicine. That said, in an age of increasingly widespread governmental and corporate surveillance, we would do well to be mindful that genomic DNA is uniquely identifying. Participants in open biological databases are engaged in a real-time experiment whose outcome is unknown. PMID:24647311

  4. Easily separated silver nanoparticle-decorated magnetic graphene oxide: Synthesis and high antibacterial activity.

    PubMed

    Zhang, Huai-Zhi; Zhang, Chang; Zeng, Guang-Ming; Gong, Ji-Lai; Ou, Xiao-Ming; Huan, Shuang-Yan

    2016-06-01

    Silver nanoparticle-decorated magnetic graphene oxide (MGO-Ag) was synthesized by doping silver and Fe3O4 nanoparticles on the surface of GO, which was used as an antibacterial agent. MGO-Ag was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray (EDS), X-ray diffraction (XRD), Raman spectroscopy and magnetic property tests. It can be found that magnetic iron oxide nanoparticles and nano-Ag was well dispersed on graphene oxide; and MGO-Ag exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. Several factors were investigated to study the antibacterial effect of MGO-Ag, such as temperature, time, pH and bacterial concentration. We also found that MGO-Ag maintained high inactivation rates after use six times and can be separated easily after antibacterial process. Moreover, the antibacterial mechanism is discussed and the synergistic effect of GO, Fe3O4 nanoparticles and nano-Ag accounted for high inactivation of MGO-Ag. PMID:26994349

  5. REMOVING DISSOLVED INORGANIC CONTAMINANTS FROM WATER

    EPA Science Inventory

    Dissolved inorganic contaminants in water can be cationic, anionic, or neutral forms of ions, atoms, or molecules of any element in the periodic table. The article describes the physicochemical treatment processes typically used to remove the more common inorganic contaminants fr...

  6. Hyperconjugation in diethyl ether cation versus diethyl sulfide cation.

    PubMed

    Morita, Masato; Matsuda, Yoshiyuki; Endo, Tomoya; Mikami, Naohiko; Fujii, Asuka; Takahashi, Kaito

    2015-09-28

    Ionization of a molecule can greatly alter its electronic structure as well as its geometric structure. In this collaborative experimental and theoretical study, we examined variance in hyperconjugation upon ionization of diethyl ether (DEE) and diethyl sulfide (DES). We obtained the experimental gas phase vibrational spectra of DEE, DES, DEE(+), DES(+), DEE(+)-Ar, and DES(+)-Ar in the wavenumber region of 2500 to 3600 cm(-1). For DEE(+) and DEE(+)-Ar, we observed a greatly red shifted CH stretching peak at 2700 cm(-1), while the lowest CH stretching peaks for DEE, DES, DES(+) and DES(+)-Ar were observed around 2850 cm(-1). For DEE(+), we calculated a drastic red shifted CH stretching peak at 2760 cm(-1), but for DEE, DES, and DES(+) the lowest CH stretching peaks were calculated to be at 2860, 2945, and 2908 cm(-1), respectively. In addition, for DEE, the minima (maxima) geometry in the neutral state becomes a maxima (minima) geometry in the cationic state, while similar minima geometries are seen in neutral and cationic states of DES. These experimental and theoretical findings were rationalized through the natural bond orbital analysis by quantifying the hyperconjugation between the σCH orbital and the ionized singly occupied p orbital of the oxygen (sulfur) in DEE(+) (DES(+)). This study showed how orientation with the ionized orbital can greatly affect the neighboring CH bond strength and its polarity, as well as the geometry of the system. Furthermore, this change in the CH bond strength between DEE(+) and DES(+) is quantified from the energies for intramolecular proton transfer in the two cations. PMID:26300267

  7. Time Resolved Thermal Diffusivity of Seasonal Snow Determined from Inexpensive, Easily-Implemented Temperature Measurements

    NASA Astrophysics Data System (ADS)

    Oldroyd, H. J.; Higgins, C. W.; Huwald, H.; Selker, J. S.; Parlange, M. B.

    2011-12-01

    Thermal diffusivity of snow is an important physical property associated with key hydrological phenomena such as snow melt and heat and water vapor exchange with the atmosphere. These phenomena have broad implications in studies of climate and heat and water budgets on many scales. However, direct measurements of snow thermal diffusivity require coupled point measurements of thermal conductivity and density, which are nonstationary due to snow metamorphism. Furthermore, thermal conductivity measurements are typically obtained with specialized heating probes or plates and snow density measurements require digging snow pits. Therefore, direct measurements are difficult to obtain with high enough temporal resolution such that direct comparisons with atmospheric conditions can be made. This study uses highly resolved (7.5 to 10 cm for depth and 1min for time) temperature measurements from the Plaine Morte glacier in Switzerland as initial and boundary conditions to numerically solve the 1D heat equation and iteratively optimize for thermal diffusivity. The method uses flux boundary conditions to constrain thermal diffusivity such that spuriously high values in thermal diffusivity are eliminated. Additionally, a t-test ensuring statistical significance between solutions of varied thermal diffusivity result in further constraints on thermal diffusivity that eliminate spuriously low values. The results show that time resolved (1 minute) thermal diffusivity can be determined from easily implemented and inexpensive temperature measurements of seasonal snow with good agreement to widely used parameterizations based on snow density. This high time resolution further affords the ability to explore possible turbulence-induced enhancements to heat and mass transfer in the snow.

  8. Clearly written, easily comprehended? The readability of websites providing information on epilepsy.

    PubMed

    Brigo, Francesco; Otte, Willem M; Igwe, Stanley C; Tezzon, Frediano; Nardone, Raffaele

    2015-03-01

    There is a general need for high-quality, easily accessible, and comprehensive health-care information on epilepsy to better inform the general population about this highly stigmatized neurological disorder. The aim of this study was to evaluate the health literacy level of eight popular English-written websites that provide information on epilepsy in quantitative terms of readability. Educational epilepsy material on these websites, including 41 Wikipedia articles, were analyzed for their overall level of readability and the corresponding academic grade level needed to comprehend the published texts on the first reading. The Flesch Reading Ease (FRE) was used to assess ease of comprehension while the Gunning Fog Index, Coleman-Liau Index, Flesch-Kincaid Grade Level, Automated Readability Index, and Simple Measure of Gobbledygook scales estimated the corresponding academic grade level needed for comprehension. The average readability of websites yielded results indicative of a difficult-to-fairly-difficult readability level (FRE results: 44.0±8.2), with text readability corresponding to an 11th academic grade level (11.3±1.9). The average FRE score of the Wikipedia articles was indicative of a difficult readability level (25.6±9.5), with the other readability scales yielding results corresponding to a 14th grade level (14.3±1.7). Popular websites providing information on epilepsy, including Wikipedia, often demonstrate a low level of readability. This can be ameliorated by increasing access to clear and concise online information on epilepsy and health in general. Short "basic" summaries targeted to patients and nonmedical users should be added to articles published in specialist websites and Wikipedia to ease readability. PMID:25601720

  9. Synchronized Drumming Enhances Activity in the Caudate and Facilitates Prosocial Commitment - If the Rhythm Comes Easily

    PubMed Central

    Kokal, Idil; Engel, Annerose; Kirschner, Sebastian; Keysers, Christian

    2011-01-01

    Why does chanting, drumming or dancing together make people feel united? Here we investigate the neural mechanisms underlying interpersonal synchrony and its subsequent effects on prosocial behavior among synchronized individuals. We hypothesized that areas of the brain associated with the processing of reward would be active when individuals experience synchrony during drumming, and that these reward signals would increase prosocial behavior toward this synchronous drum partner. 18 female non-musicians were scanned with functional magnetic resonance imaging while they drummed a rhythm, in alternating blocks, with two different experimenters: one drumming in-synchrony and the other out-of-synchrony relative to the participant. In the last scanning part, which served as the experimental manipulation for the following prosocial behavioral test, one of the experimenters drummed with one half of the participants in-synchrony and with the other out-of-synchrony. After scanning, this experimenter “accidentally” dropped eight pencils, and the number of pencils collected by the participants was used as a measure of prosocial commitment. Results revealed that participants who mastered the novel rhythm easily before scanning showed increased activity in the caudate during synchronous drumming. The same area also responded to monetary reward in a localizer task with the same participants. The activity in the caudate during experiencing synchronous drumming also predicted the number of pencils the participants later collected to help the synchronous experimenter of the manipulation run. In addition, participants collected more pencils to help the experimenter when she had drummed in-synchrony than out-of-synchrony during the manipulation run. By showing an overlap in activated areas during synchronized drumming and monetary reward, our findings suggest that interpersonal synchrony is related to the brain's reward system. PMID:22110623

  10. Threshold concentration of easily assimilable organic carton in feedwater for biofouling of spiral-wound membranes.

    PubMed

    Hijnen, W A M; Biraud, D; Cornelissen, E R; van der Kooij, D

    2009-07-01

    One of the major impediments in the application of spiral-wound membranes in water treatment or desalination is clogging of the feed channel by biofouling which is induced by nutrients in the feedwater. Organic carbon is, under most conditions, limiting the microbial growth. The objective of this study is to assess the relationship between the concentration of an easily assimilable organic compound such as acetate in the feedwater and the pressure drop increase in the feed channel. For this purpose the membrane fouling simulator (MFS) was used as a model for the feed channel of a spiral-wound membrane. This MFS unit was supplied with drinking water enriched with acetate at concentrations ranging from 1 to 1000 microg C x L(-1). The pressure drop (PD) in the feed channel increased at all tested concentrations but not with the blank. The PD increase could be described by a first order process based on theoretical considerations concerning biofilm formation rate and porosity decline. The relationship between the first order fouling rate constant R(f) and the acetate concentration is described with a saturation function corresponding with the growth kinetics of bacteria. Under the applied conditions the maximum R(f) (0.555 d(-1)) was reached at 25 microg acetate-C x L(-1) and the half saturation constant k(f) was estimated at 15 microg acetate-C x L(-1). This value is higher than k(s) values for suspended bacteria grown on acetate, which is attributed to substrate limited growth conditions in the biofilm. The threshold concentration for biofouling of the feed channel is about 1 microg acetate-C x L(-1). PMID:19673281

  11. Reliable plasmonic substrates for bioanalytical SERS applications easily prepared by convective assembly of gold nanocolloids.

    PubMed

    Farcau, Cosmin; Potara, Monica; Leordean, Cosmin; Boca, Sanda; Astilean, Simion

    2013-01-21

    The ability to easily prepare Surface Enhanced Raman Scattering (SERS) substrates by the assembly of chemically synthesized gold nanocolloids is of great interest for the advancement of SERS-based optical detection and identification of molecular species of biological or chemical interest, pollutants or warfare agents. In this work we employ three very simple strategies, which can be implemented in any laboratory without the need for specialized equipment, to prepare assemblies of citrate-stabilized spherical gold colloids: (i) drop-coating, which induces the assembly of colloids in so-called coffee rings; (ii) a simplified variant of convective self-assembly (CSA), based on water evaporation in a constrained geometry, which yields highly uniform strips of nanoparticles (NP); (iii) assembly onto chemically functionalized glass surfaces which yields randomly assembled colloids and colloidal clusters. The SERS properties of the resulting colloidal assemblies are comparatively evaluated under multiple excitation lines with p-aminothiophenol (pATP) as a model Raman scatterer. The NP strips obtained by CSA prove to be SERS-active both in the visible and NIR and possess a highly uniform SERS response as demonstrated by spectra at individually selected sites and by confocal SERS mapping. Further it is shown that these NP strips are effective for the detection of cytosine, a DNA component, and for multi-analyte SERS detection. These results, showing how an efficient SERS substrate can be obtained by a very simple assembly method from easy-to-synthesize colloidal gold NP, can have an impact on the development of analytical SERS applications. PMID:23171872

  12. The Sclerotic Scatter Limbal Arc Is More Easily Elicited under Mesopic Rather Than Photopic Conditions

    PubMed Central

    Denion, Eric; Lux, Anne-Laure; Mouriaux, Frédéric; Béraud, Guillaume

    2016-01-01

    Introduction We aimed to determine the limbal lighting illuminance thresholds (LLITs) required to trigger perception of sclerotic scatter at the opposite non-illuminated limbus (i.e. perception of a light limbal scleral arc) under different levels of ambient lighting illuminance (ALI). Material and Methods Twenty healthy volunteers were enrolled. The iris shade (light or dark) was graded by retrieving the median value of the pixels of a pre-determined zone of a gray-level iris photograph. Mean keratometry and central corneal pachymetry were recorded. Each subject was asked to lie down, and the ALI at eye level was set to mesopic values (10, 20, 40 lux), then photopic values (60, 80, 100, 150, 200 lux). For each ALI level, a light beam of gradually increasing illuminance was applied to the right temporal limbus until the LLIT was reached, i.e. the level required to produce the faint light arc that is characteristic of sclerotic scatter at the nasal limbus. Results After log-log transformation, a linear relationship between the logarithm of ALI and the logarithm of the LLIT was found (p<0.001), a 10% increase in ALI being associated with an average increase in the LLIT of 28.9%. Higher keratometry values were associated with higher LLIT values (p = 0.008) under low ALI levels, but the coefficient of the interaction was very small, representing a very limited effect. Iris shade and central corneal thickness values were not significantly associated with the LLIT. We also developed a censored linear model for ALI values ≤ 40 lux, showing a linear relationship between ALI and the LLIT, in which the LLIT value was 34.4 times greater than the ALI value. Conclusion Sclerotic scatter is more easily elicited under mesopic conditions than under photopic conditions and requires the LLIT value to be much higher than the ALI value, i.e. it requires extreme contrast. PMID:26964096

  13. Superomniphobic and easily repairable coatings on copper substrates based on simple immersion or spray processes.

    PubMed

    Rangel, Thomaz C; Michels, Alexandre F; Horowitz, Flávio; Weibel, Daniel E

    2015-03-24

    Textures that resemble typical fern or bracken plant species (dendrite structures) were fabricated for liquid repellency by dipping copper substrates in a single-step process in solutions containing AgNO3 or by a simple spray liquid application. Superhydrophobic surfaces were produced using a solution containing AgNO3 and trimethoxypropylsilane (TMPSi), and superomniphobic surfaces were produced by a two-step procedure, immersing the copper substrate in a AgNO3 solution and, after that, in a solution containing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES). The simple functionalization processes can also be used when the superomniphobic surfaces were destroyed by mechanical stress. By immersion of the wrecked surfaces in the above solutions or by the spray method and soft heating, the copper substrates could be easily repaired, regenerating the surfaces' superrepellency to liquids. The micro- and nanoroughness structures generated on copper surfaces by the deposition of silver dendrites functionalized with TMPSi presented apparent contact angles greater than 150° with a contact angle hysteresis lower than 10° when water was used as the test liquid. To avoid total wettability with very low surface tension liquids, such as rapeseed oil and hexadecane, a thin perfluorinated coating of poly(tetrafluoroethylene) (PTFE), produced by physical vapor deposition, was used. A more efficient perfluorinated coating was obtained when PFDTES was used. The superomniphobic surfaces produced apparent contact angles above 150° with all of the tested liquids, including hexadecane, although the contact angle hysteresis with this liquid was above 10°. The coupling of dendritic structures with TMPSi/PTFE or directly by PFDTES coatings was responsible for the superrepellency of the as-prepared surfaces. These simple, fast, and reliable procedures allow the large area, and cost-effective scale fabrication of superrepellent surfaces on copper substrates for various industrial

  14. Kidney removal

    MedlinePlus

    ... will be on your side, just below the ribs or right over the lowest ribs. Muscle, fat, and tissue are cut and moved. Your surgeon may need to remove a rib to do the procedure. The tube that carries ...

  15. Spleen removal

    MedlinePlus

    ... disorders of blood cells, such as idiopathic thrombocytopenia purpura (ITP), hereditary spherocytosis , thalassemia, hemolytic anemia , and hereditary ... spherocytic anemia Hemolytic anemia Hodgkin lymphoma Idiopathic thrombocytopenic purpura (ITP) Patient Instructions Spleen removal - child - discharge Spleen ...

  16. Tattoo removal.

    PubMed

    Adatto, Maurice A; Halachmi, Shlomit; Lapidoth, Moshe

    2011-01-01

    Over 50,000 new tattoos are placed each year in the United States. Studies estimate that 24% of American college students have tattoos and 10% of male American adults have a tattoo. The rising popularity of tattoos has spurred a corresponding increase in tattoo removal. Not all tattoos are placed intentionally or for aesthetic reasons though. Traumatic tattoos due to unintentional penetration of exogenous pigments can also occur, as well as the placement of medical tattoos to mark treatment boundaries, for example in radiation therapy. Protocols for tattoo removal have evolved over history. The first evidence of tattoo removal attempts was found in Egyptian mummies, dated to have lived 4,000 years BC. Ancient Greek writings describe tattoo removal with salt abrasion or with a paste containing cloves of white garlic mixed with Alexandrian cantharidin. With the advent of Q-switched lasers in the late 1960s, the outcomes of tattoo removal changed radically. In addition to their selective absorption by the pigment, the extremely short pulse duration of Q-switched lasers has made them the gold standard for tattoo removal. PMID:21865802

  17. Cation coordination in oxychloride glasses

    NASA Astrophysics Data System (ADS)

    Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.

    2003-02-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

  18. Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

    PubMed Central

    Fan, Zhaochuan; Lin, Li-Chiang; Buijs, Wim; Vlugt, Thijs J. H.; van Huis, Marijn A.

    2016-01-01

    Cation exchange is a powerful tool for the synthesis of nanostructures such as core–shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core–shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals. PMID:27160371

  19. Use of laser induced photoacoustic spectroscopy (LIPAS) to determine equilibrium constants of cation-cation complexes

    SciTech Connect

    Hannink, N.J.; Hoffman, D.C.; Silva, R.J.; Russo, R.E.

    1993-12-31

    Laser Induced PhotoAcoustic Spectroscopy (LIPAS) is a relatively new, photothermal technique to examine solutions. Studies in the past have shown it to be more sensitive than conventional absorption spectroscopy, while, yielding the same information thus allowing lower concentrations to be used. This study is using LIPAS to examine solutions to determine the equilibrium constants of cation-cation complexes. It has been found that actinyl(V) cations form cation-cation complexes with a variety of cations, including actinyl(VI) cations. The radioactive nature of the actinide elements requires special handling techniques and also require limits be placed on the amount of material that can be used. The sensitivity of some oxidation states of the actinides to oxygen also presents a problem. Preliminary results will be presented for actinyl(V)-actinyl(VI) cation-cation complexes that were studied using a remote LIPAS system incorporating fiber optics for transmission of laser signals.

  20. Cation reordering in natural titanomagnetites and implications for paleointensity studies

    NASA Astrophysics Data System (ADS)

    Bowles, J. A.; Jackson, M. J.; Gee, J. S.

    2013-05-01

    Successful paleointensity experiments hinge on the underlying assumption of reciprocity; the remanence acquired over a particular temperature range should be fully removed over the same temperature range, and vice versa. This means that the blocking (TB) and unblocking (TUB) temperature spectra are identical and do not change during the course of the experiment. We will present the results of recent work demonstrating that some natural titanomagnetites undergo cation reordering on laboratory timescales and at temperatures at or below the Curie temperature (TC). The bulk composition of the titanomagnetites (Fe3-xTixO4) varies between approximately 0.2 < x < 0.4, with moderate degrees of Mg and Al substitution. Although there is no attendant structural or chemical alteration, the re-distribution of ferric and ferrous iron cations results in reversible changes in Curie temperature of up to 150°C. This necessarily changes the blocking temperature spectrum as a function of prior thermal history. These changes in TC, TUB and TB clearly pose problems for all paleointensity experiments, but the effects may be most apparent during Thellier-type experiments where the sample is step-wise heated to increasingly higher temperatures. The blocking temperature distribution will be expected to change over the course of the experiment even in the absence of chemical alteration, and one can expect the experiment to fail. We will explore the effects of cation redistribution on paleointensity experiments through numerical models and by comparison with paleointensity data from pumice samples taken from the 1980 pyroclastic flows at Mt. St. Helens (MSH). In the MSH samples, two phases are typically present: a predominantly multi-domain, homogeneous titanomagnetite (associated with the cation reordering) and an oxyexsolved, single-domain to pseudo-single-domain phase with ilmenite lamellae in a magnetite-rich host. Samples that result in technically successful paleointensity experiments

  1. Removal of heavy metals from waste streams

    SciTech Connect

    Spence, M.D.; Kozaruk, J.M.; Melvin, M.; Gardocki, S.M.

    1988-07-19

    A method for removing heavy metals from effluent water is described comprising performing sequentially the following steps: (a) adding from 7-333 ppm of an anionic surfactant to the effluent water to provide coagulatable heavy metal ion; (b) adjusting the effluent water pH to within the range of 8 to 10, (c) providing from 10-200 ppm of a cationic coagulant to coagulate the heavy metal ion, (d) providing from 0.3 to 5.0 ppm of a polymeric flocculant whereby a heavy metal containing floc is formed for removal from the effluent water, and, (e) then removing the floc from the effluent water, wherein the anionic surfactant is sodium lauryl ether sulfate. The cationic coagulant is selected from the group consisting of diallyl dimethylammonium chloride polymer, epichlorohydrin dimethylamine polymer, ethylene amine polymer, polyaluminum chloride, and alum; and the flocculant is an acrylamide/sodium acrylate copolymer having an RSV greater than 23.

  2. Laboratory Experiments on the Electrochemical Remediation of Environment. Part 4: Color Removal of Simulated Wastewater by Electrocoagulation-Electroflotation

    NASA Astrophysics Data System (ADS)

    Ibanez, Jorge G.; Singh, M. M.; Szafran, Z.

    1998-08-01

    Due to the large production of aqueous waste streams from textile mills and dye production plants, several processes have been under intense study. Electrochemical processes offer some distinctive advantages, including effects due to: 1) the production of electrolysis gases, and 2) the production of polyvalent cations from the oxidation of corrodible anodes (like Fe and Al). The gas bubbles can carry the pollutant to the top of the solution where it can be more easily concentrated, collected and removed. The metallic ions can react with the OH- ions produced at the cathode during the evolution of H2 gas to yield insoluble hydroxides that will adsorb pollutants out of the solution and also contribute to coagulation by neutralizing any negatively charged colloidal particles that might be present. In this experiment an iron electrode (paper clip) is used in conjunction with pH indicator dyes, so dramatic color changes will be noticed.

  3. In situ removal of contamination from soil

    DOEpatents

    Lindgren, E.R.; Brady, P.V.

    1997-10-14

    A process of remediation of cationic heavy metal contamination from soil utilizes gas phase manipulation to inhibit biodegradation of a chelating agent that is used in an electrokinesis process to remove the contamination. The process also uses further gas phase manipulation to stimulate biodegradation of the chelating agent after the contamination has been removed. The process ensures that the chelating agent is not attacked by bioorganisms in the soil prior to removal of the contamination, and that the chelating agent does not remain as a new contaminant after the process is completed. 5 figs.

  4. In situ removal of contamination from soil

    DOEpatents

    Lindgren, Eric R.; Brady, Patrick V.

    1997-01-01

    A process of remediation of cationic heavy metal contamination from soil utilizes gas phase manipulation to inhibit biodegradation of a chelating agent that is used in an electrokinesis process to remove the contamination, and further gas phase manipulation to stimulate biodegradation of the chelating agent after the contamination has been removed. The process ensures that the chelating agent is not attacked by bioorganisms in the soil prior to removal of the contamination, and that the chelating agent does not remain as a new contaminant after the process is completed.

  5. Removal and recovery of furfural, 5-hydroxymethylfurfural, and acetic acid from aqueous solutions using a soluble polyelectrolyte.

    PubMed

    Carter, Brian; Gilcrease, Patrick C; Menkhaus, Todd J

    2011-09-01

    In the cellulosic ethanol process, furfural, 5-hydroxymethylfurfural (HMF), and acetic acid are formed during the high temperature acidic pretreatment step needed to convert biomass into fermentable sugars. These compounds can inhibit cellulase enzymes and fermentation organisms at relatively low concentrations (≥ 1 g/L). Effective removal of these inhibitory compounds would allow the use of more severe pretreatment conditions to improve sugar yields and lead to more efficient fermentations; if recovered and purified, they could also be sold as valuable by-products. This study investigated the separation of aldhehydes (furfural and HMF) and organic acid (acetic acid) inhibitory compounds from simple aqueous solutions by using polyethyleneimene (PEI), a soluble cationic polyelectrolyte. PEI added to simple solutions of each inhibitor at a ratio of 1 mol of functional group to 1 mol inhibitor removed up to 89.1, 58.6, and 81.5 wt% of acetic acid, HMF, and furfural, respectively. Furfural and HMF were recovered after removal by washing the polyelectrolyte/inhibitor complex with dilute sulfuric acid solution. Recoveries up to 81.0 and 97.0 wt% were achieved for furfural and HMF, respectively. The interaction between PEI and acetic acid was easily disrupted by the addition of chloride ions, sulfate ions, or hydroxide ions. The use of soluble polymers for the removal and recovery of inhibitory compounds from biomass slurries is a promising approach to enhance the efficiency and economics of an envisioned biorefinery. PMID:21455937

  6. Preparation and Use of an Easily Constructed, Inexpensive Chamber for Viewing Courtship Behaviors of Fruit Flies, Drosophila sp.

    ERIC Educational Resources Information Center

    Christensen, Timothy J.; Labov, Jay B.

    1997-01-01

    Details the construction of a viewing chamber for fruit flies that connects to a dissecting microscope and features a design that enables students to easily move fruit flies in and out of the chamber. (DDR)

  7. Improved sulfur removal processes evaluated for IGCC

    SciTech Connect

    Not Available

    1986-12-01

    An inherent advantage of Integrated Coal Gasification Combined Cycle (IGCC) electric power generation is the ability to easily remove and recover sulfur. During the last several years, a number of new, improved sulfur removal and recovery processes have been commercialized. An assessment is given of alternative sulfur removal processes for IGCC based on the Texaco coal gasifier. The Selexol acid gas removal system, Claus sulfur recovery, and SCOT tail gas treating are currently used in Texaco-based IGCC. Other processes considered are: Purisol, Sulfinol-M, Selefning, 50% MDEA, Sulften, and LO-CAT. 2 tables.

  8. Nitroethane poisoning from an artificial fingernail remover.

    PubMed

    Hornfeldt, C S; Rabe, W H

    1994-01-01

    Confusion between acetone fingernail polish removers and artificial fingernail products containing acetonitrile and N,N-dimethyl-p-toluidine has resulted in pediatric morbidity and mortality. In the present case, a 20-month-old boy drank less than one ounce of Remove Artificial Nail Remover containing 100% nitroethane. In the emergency department he displayed cyanosis and 39% methemoglobinemia. Following intravenous methylene blue, the child's methemoglobin level dropped to 5.7% and he recovered uneventfully. Toxicity from nitroethane has not previously been reported in humans. Poison centers and emergency department personnel should be alert to another nail product which may be easily confused with acetone-containing nail polish removers. PMID:8007041

  9. The adsorption and mass-transfer process of cationic red X-GRL dye on natural zeolite.

    PubMed

    Tian, Jingjing; Guan, Junfang; Gao, Huimin; Wen, Yafei; Ren, Zijie

    2016-01-01

    The adsorption behavior of natural zeolite was studied in order to determine the adsorption capacity and mass-transfer process of cationic red X-GRL (C(18)H(21)BrN(6)) onto the adsorbent. The adsorption tests to determine both the uptake capacity and the mass-transfer process at equilibrium were performed under batch conditions, which showed rapid uptake in general for the initial 5 min, corresponding to 92% total removal. The equilibrium adsorption capacity value (q(e,cal)) in pseudo-second-order kinetics was 13.51 mg/g at 293 K and the whole adsorption process was governed by physical adsorption with an endothermic, endothermic spontaneous nature. Adsorption tests indicated that the zeolite has great potential as an alternative low-cost material in the treatment of X-GRL drainage. However, the mass-transfer process to determine the rate-controlling steps showed that both film diffusion and pore diffusion were important in controlling the adsorption rate. The adsorption process was governed by film diffusion while pore diffusion was poor because the X-GRL molecules could not penetrate into the zeolite easily. The X-GRL molecules were only adsorbed on the external surface of the zeolite. Hence, to improve the adsorption capacity of natural zeolite further, modification to expand its micropores is necessary. PMID:27148713

  10. Anti-inflammatory activity of cationic lipids.

    PubMed

    Filion, M C; Phillips, N C

    1997-10-01

    1. The effect of liposome phospholipid composition has been assumed to be relatively unimportant because of the presumed inert nature of phospholipids. 2. We have previously shown that cationic liposome formulations used for gene therapy inhibit, through their cationic component, the synthesis by activated macrophages of the pro-inflammatory mediators nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). 3. In this study, we have evaluated the ability of different cationic lipids to reduce footpad inflammation induced by carrageenan and by sheep red blood cell challenge. 4. Parenteral (i.p. or s.c) or local injection of the positively charged lipids dimethyldioctadecylammomium bromide (DDAB), dioleyoltrimethylammonium propane (DOTAP), dimyristoyltrimethylammonium propane (DMTAP) or dimethylaminoethanecarbamoyl cholesterol (DC-Chol) significantly reduced the inflammation observed in both models in a dose-dependent manner (maximum inhibition: 70-95%). 5. Cationic lipids associated with dioleyol- or dipalmitoyl-phosphatidylethanolamine retained their anti-inflammatory activity while cationic lipids associated with dipalmitoylphosphatidylcholine (DPPC) or dimyristoylphosphatidylglycerol (DMPG) showed no anti-inflammatory activity, indicating that the release of cationic lipids into the macrophage cytoplasm is a necessary step for anti-inflammatory activity. The anti-inflammatory activity of cationic lipids was abrogated by the addition of dipalmitoylphosphatidylethanolamine-poly(ethylene)glycol-2000 (DPPE-PEG2000) which blocks the interaction of cationic lipids with macrophages. 6. Because of the significant role of protein kinase C (PKC) in the inflammatory process we have determined whether the cationic lipids used in this study inhibit PKC activity. The cationic lipids significantly inhibited the activity of PKC but not the activity of a non-related protein kinase, PKA. The synthesis of interleukin-6 (IL-6), which is not dependent on PKC activity for its

  11. ARSENIC REMOVAL

    EPA Science Inventory

    Presentation covered five topics; arsenic chemistry, best available technology (BAT), surface water technology, ground water technology and case studies of arsenic removal. The discussion on arsenic chemistry focused on the need and method of speciation for AsIII and AsV. BAT me...

  12. Splinter removal

    MedlinePlus

    ... remove a splinter, first wash your hands with soap and water. Use tweezers to grab the splinter. Carefully pull it out at the same angle it went in. If the splinter is under the skin or hard to grab: Sterilize a pin or needle by ...

  13. REMOVING INORGANICS

    EPA Science Inventory

    When EPA sets a regulation ( a maxim contaminant level) for a contaminant, it must also specify the "best available technology" (BAT) that can be used to remove the contaminant. ecause the regulations apply to community water systems, the technologies selected are ones that are c...

  14. Selone-stabilized aryltellurenyl cations.

    PubMed

    Yadav, Sangeeta; Raju, Saravanan; Singh, Harkesh B; Butcher, Ray J

    2016-05-28

    Controlled bromination of a diarylditelluride, R2Te2 (R = 2,6-dimethylphenyl) (6) in dichloromethane led to the formation of a Te(II)-Te(IV) mixed-valent tellurenyl bromide, RBr2TeTeR (7). A further reaction of 7 with 1,3-dibutylbenzimidazolin-2-selone, C15H22N2Se (L) (9), produced the first selone adduct of the 2,6-dimethylphenyltellurenyl cation with the 2,6-dimethylphenyltellurium dibromide anion, [(2,6-Me2C6H3)Te(L)](+)[(2,6-Me2C6H3)TeBr2](-) (10). The red colored cationic adduct 10 is not stable in acetonitrile and disproportionated to give the selone adduct of 2,6-dimethylphenyltellurenyl bromide, [(2,6-Me2C6H3)Te(L)Br] (11b) and bis(2,6-dimethylphenyl)tellurium dibromide, [(2,6-Me2C6H3)2TeBr2], (13). The metathesis reaction of 11b with AgBF4 produced a stable dark red colored selone adduct of the 2,6-dimethylphenyltellurenyl cation with the BF4(-) anion, [(2,6-Me2C6H3)Te(L)](+)BF4(-) (15). The selone adducts of aryltellurenyl halides, i.e. [(2,6-Me2C6H3)Te(L)X] (X = Cl, Br, I) (11a-11c), have been synthesized by a one-pot reaction of 6 with an equimolar mixture of 9 and 1,3-dibutylbenzimidazolin-2-dihaloselones, C15H22N2SeX2 (14a-14c). Triphenylphosphine (PPh3), when treated with [(2,6-Me2C6H3)Te(L)X] (11a-11c), substitutes selone from the adduct to afford the triphenylphosphine adducts of aryltellurenyl halides, [(2,6-Me2C6H3)Te(PPh3)X] (16a-16c). PMID:27111528

  15. Cation-coupled bicarbonate transporters.

    PubMed

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-10-01

    Cation-coupled HCO3(-) transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3(-) and associated with Na(+) and Cl(-) movement. The first Na(+)-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 (SLC4A7 gene product); the Na(+)-driven Cl,HCO3-exchanger NDCBE (SLC4A8 gene product); and NBCn2/NCBE (SLC4A10 gene product), which has been characterized as an electroneutral Na,HCO3-cotransporter or a Na(+)-driven Cl,HCO3-exchanger. Despite the similarity in amino acid sequence and predicted structure among the NCBTs of the SLC4-family, they exhibit distinct differences in ion dependency, transport function, pharmacological properties, and interactions with other proteins. In epithelia, NCBTs are involved in transcellular movement of acid-base equivalents and intracellular pH control. In nonepithelial tissues, NCBTs contribute to intracellular pH regulation; and hence, they are crucial for diverse tissue functions including neuronal discharge, sensory neuron development, performance of the heart, and vascular tone regulation. The function and expression levels of the NCBTs are generally sensitive to intracellular and systemic pH. Animal models have revealed pathophysiological roles of the transporters in disease states including metabolic acidosis, hypertension, visual defects, and epileptic seizures. Studies are being conducted to understand the physiological consequences of genetic polymorphisms in the SLC4-members, which are associated with cancer, hypertension, and drug addiction. Here, we describe the current knowledge regarding the function, structure, and regulation of the mammalian cation-coupled HCO3(-) transporters of the SLC4-family. PMID:25428855

  16. Cation-Coupled Bicarbonate Transporters

    PubMed Central

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2016-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 (SLC4A7 gene product); the Na+-driven Cl,HCO3-exchanger NDCBE (SLC4A8 gene product); and NBCn2/NCBE (SLC4A10 gene product), which has been characterized as an electroneutral Na,HCO3-cotransporter or a Na+-driven Cl,HCO3-exchanger. Despite the similarity in amino acid sequence and predicted structure among the NCBTs of the SLC4-family, they exhibit distinct differences in ion dependency, transport function, pharmacological properties, and interactions with other proteins. In epithelia, NCBTs are involved in transcellular movement of acid-base equivalents and intracellular pH control. In nonepithelial tissues, NCBTs contribute to intracellular pH regulation; and hence, they are crucial for diverse tissue functions including neuronal discharge, sensory neuron development, performance of the heart, and vascular tone regulation. The function and expression levels of the NCBTs are generally sensitive to intracellular and systemic pH. Animal models have revealed pathophysiological roles of the transporters in disease states including metabolic acidosis, hypertension, visual defects, and epileptic seizures. Studies are being conducted to understand the physiological consequences of genetic polymorphisms in the SLC4-members, which are associated with cancer, hypertension, and drug addiction. Here, we describe the current knowledge regarding the function, structure, and regulation of the mammalian cation-coupled HCO3− transporters of the SLC4-family. PMID:25428855

  17. Crying without a cause and being easily upset in two-year-olds: heritability and predictive power of behavioral problems.

    PubMed

    Groen-Blokhuis, Maria M; Middeldorp, Christel M; M van Beijsterveldt, Catharina E; Boomsma, Dorret I

    2011-10-01

    In order to estimate the influence of genetic and environmental factors on 'crying without a cause' and 'being easily upset' in 2-year-old children, a large twin study was carried out. Prospective data were available for ~18,000 2-year-old twin pairs from the Netherlands Twin Register. A bivariate genetic analysis was performed using structural equation modeling in the Mx software package. The influence of maternal personality characteristics and demographic and lifestyle factors was tested to identify specific risk factors that may underlie the shared environment of twins. Furthermore, it was tested whether crying without a cause and being easily upset were predictive of later internalizing, externalizing and attention problems. Crying without a cause yielded a heritability estimate of 60% in boys and girls. For easily upset, the heritability was estimated at 43% in boys and 31% in girls. The variance explained by shared environment varied between 35% and 63%. The correlation between crying without a cause and easily upset (r = .36) was explained both by genetic and shared environmental factors. Birth cohort, gestational age, socioeconomic status, parental age, parental smoking behavior and alcohol use during pregnancy did not explain the shared environmental component. Neuroticism of the mother explained a small proportion of the additive genetic, but not of the shared environmental effects for easily upset. Crying without a cause and being easily upset at age 2 were predictive of internalizing, externalizing and attention problems at age 7, with effect sizes of .28-.42. A large influence of shared environmental factors on crying without a cause and easily upset was detected. Although these effects could be specific to these items, we could not explain them by personality characteristics of the mother or by demographic and lifestyle factors, and we recognize that these effects may reflect other maternal characteristics. A substantial influence of genetic factors

  18. Modeling the enhanced removal of emerging organic contaminants during MAR through a reactive barrier.

    NASA Astrophysics Data System (ADS)

    Valhondo, Cristina; Carrera, Jesús; Ayora, Carlos; Martinez-Landa, Lurdes; Nödler, Karsten; Licha, Tobias

    2014-05-01

    Artificial recharge of reclaimed water is often proposed as a way of increasing water resources while improving quality. However, it is also feared that recalcitrant organic contaminants (i.e., those that are not completely removed during wastewater treatment) may reach the aquifer. Specifically, emerging organic contaminants (EOCs) have been increasingly detected in surface and ground waters and are becoming a worldwide problem. Most EOCs exhibit higher concentrations in reclaimed water used for artificial recharge than in produced groundwater, indicating that these compounds are retained and/or degraded during infiltration. Removal may be the result of sorption, which depends on organic matter and inorganic surfaces contained in the sediments, and degradation, which depends on redox conditions (some EOCs are preferentially removed under specific redox conditions). To enhance removal and retention processes, we designed a reactive barrier, which consists of compost, sand, clay and is covered by iron oxide. The role of compost is to favor sorption of neutral compounds and to release easily degradable organic carbon, so as to generate diverse redox condition, thus increasing the range of degraded EOCs. The role of iron oxides and clay is to favor sorption of anionic and cationic compounds, respectively. The barrier has been tested in the field proving its ability in promoting diverse redox conditions and indeed improving EOCs removal. However, experimental data do not allow separating sorption from degradation. To do so, we have built a flow and transport model representing the infiltration system and the aquifer beneath. The model has been calibrated against head data, collected during three years that include recharge and natural flow periods, and concentration, collected during a conservative tracer test. The calibrated model was then used to predict the fate of EOCs using sorption and half-lives from the literature. Results confirm that retention and degradation

  19. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    DOEpatents

    Wasserman, Stephen R.; Anderson, Kenneth B.; Song, Kang; Yuchs, Steven E.; Marshall, Christopher L.

    1998-01-01

    A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  20. Cation channels, cell volume and the death of an erythrocyte.

    PubMed

    Lang, Florian; Lang, Karl S; Wieder, Thomas; Myssina, Svetlana; Birka, Christina; Lang, Philipp A; Kaiser, Stephanie; Kempe, Daniela; Duranton, Christophe; Huber, Stephan M

    2003-11-01

    Similar to a variety of nucleated cells, human erythrocytes activate a non-selective cation channel upon osmotic cell shrinkage. Further stimuli of channel activation include oxidative stress, energy depletion and extracellular removal of Cl-. The channel is permeable to Ca2+ and opening of the channel increases cytosolic [Ca2+]. Intriguing evidence points to a role of this channel in the elimination of erythrocytes by apoptosis. Ca2+ entering through the cation channel stimulates a scramblase, leading to breakdown of cell membrane phosphatidylserine asymmetry, and stimulates Ca(2+)-sensitive K+ channels, thus leading to KCl loss and (further) cell shrinkage. The breakdown of phosphatidylserine asymmetry is evidenced by annexin binding, a typical feature of apoptotic cells. The effects of osmotic shock, oxidative stress and energy depletion on annexin binding are mimicked by the Ca2+ ionophore ionomycin (1 microM) and blunted in the nominal absence of extracellular Ca2+. Nevertheless, the residual annexin binding points to additional mechanisms involved in the triggering of the scramblase. The exposure of phosphatidylserine at the extracellular face of the cell membrane stimulates phagocytes to engulf the apoptotic erythrocytes. Thus, sustained activation of the cation channels eventually leads to clearance of affected erythrocytes from peripheral blood. Susceptibility to annexin binding is enhanced in several genetic disorders affecting erythrocyte function, such as thalassaemia, sickle-cell disease and glucose-6-phosphate dehydrogenase deficiency. The enhanced vulnerability presumably contributes to the shortened life span of the affected erythrocytes. Beyond their role in the limitation of erythrocyte survival, cation channels may contribute to the triggering of apoptosis in nucleated cells exposed to osmotic shock and/or oxidative stress. PMID:12905029

  1. Advancements in Anion Exchange Membrane Cations

    SciTech Connect

    Sturgeon, Matthew R.; Long, Hai; Park, Andrew M.; Pivovar, Bryan S.

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  2. Tripodal Receptors for Cation and Anion Sensors

    PubMed Central

    Kuswandi, Bambang; Nuriman; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selective recognition and sensing of cations and anions. Examples on the relationship between structure and selectivity towards cations and anions are described. Furthermore, their applications as potentiometric ion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  3. Cationic-modified cyclodextrin nanosphere/anionic polymer as flocculation/sorption systems.

    PubMed

    Xiao, Huining; Cezar, Norlito

    2005-03-15

    Simultaneous removal of dissolved and colloidal substances has been a challenging task. The cationic-modified beta-cyclodextrin nanospheres synthesized in this work, in conjunction with a water-soluble polyacrylamide-based anionic polymer, potentially provide a novel approach to address the problem. The cyclodextrin was rendered cationic using (2,3-epoxypropyl)trimethylammonium chloride as a reagent. The cationicity of the modified cyclodextrin and the reaction between cyclodextrin and the reagent were characterized by electrophoresis measurement, polyelectrolyte titration, and NMR. As a dual-component flocculation system, the cationic cyclodextrin/anionic polymer significantly induced clay flocculation, lowering the relative turbidity of the clay suspension over a wide pH range. Meanwhile, as a nanospherical absorbent, the modified cyclodextrins exhibited strong affinity toward aromatic compounds via inclusion complex formation in the hydrophobic cavities, which was monitored by UV spectroscopy. These systems facilitated the simultaneous removal of dissolved and colloidal substances, which was unachievable previously. In addition, the interaction between anionic polymers and the clay particles pretreated with cationic cyclodextrin was investigated in order to reveal the flocculation mechanism. PMID:15721912

  4. Easily Accessible Rare-Earth-Containing Phosphonium Room-Temperature Ionic Liquids: EXAFS, Luminescence, and Magnetic Properties.

    PubMed

    Alvarez-Vicente, Jorge; Dandil, Sahra; Banerjee, Dipanjan; Gunaratne, H Q Nimal; Gray, Suzanne; Felton, Solveig; Srinivasan, Geetha; Kaczmarek, Anna M; Van Deun, Rik; Nockemann, Peter

    2016-06-16

    A range of liquid rare earth chlorometallate complexes with the alkyl-phosphonium cation, [P666 14](+), has been synthesized and characterized. EXAFS confirmed the predominant liquid-state speciation of the [LnCl6](3-) ion in the series with Ln = Nd, Eu, Dy. The crystal structure of the shorter-alkyl-chain cation analogue [P4444](+) has been determined and exhibits a very large unit cell. The luminescence properties, with visible-light emissions of the liquid Tb, Eu, Pr, and Sm and the NIR emissions for the Nd and Er compounds, were determined. The effective magnetic moments were measured and fitted for the Nd, Tb, Ho, Dy, Gd, and Er samples. PMID:27203286

  5. Mercury removal sorbents

    DOEpatents

    Alptekin, Gokhan

    2016-03-29

    Sorbents and methods of using them for removing mercury from flue gases over a wide range of temperatures are disclosed. Sorbent materials of this invention comprise oxy- or hydroxyl-halogen (chlorides and bromides) of manganese, copper and calcium as the active phase for Hg.sup.0 oxidation, and are dispersed on a high surface porous supports. In addition to the powder activated carbons (PACs), this support material can be comprised of commercial ceramic supports such as silica (SiO.sub.2), alumina (Al.sub.2O.sub.3), zeolites and clays. The support material may also comprise of oxides of various metals such as iron, manganese, and calcium. The non-carbon sorbents of the invention can be easily injected into the flue gas and recovered in the Particulate Control Device (PCD) along with the fly ash without altering the properties of the by-product fly ash enabling its use as a cement additive. Sorbent materials of this invention effectively remove both elemental and oxidized forms of mercury from flue gases and can be used at elevated temperatures. The sorbent combines an oxidation catalyst and a sorbent in the same particle to both oxidize the mercury and then immobilize it.

  6. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-03-20

    This patent describes a method of removing heavy metals from aqueous solution, a composition of matter used in effecting the removal, and apparatus used in effecting the removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  7. Removal of metal ions from aqueous solution

    DOEpatents

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-01-01

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  8. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1988-08-26

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  9. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-11-13

    A method is disclosed of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ([gamma]glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ([gamma]glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form. 1 fig.

  10. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-11-13

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heayv metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  11. Cationic Bolaamphiphiles for Gene Delivery

    NASA Astrophysics Data System (ADS)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  12. Removal of THM precursors by coagulation or ion exchange.

    PubMed

    Bolto, Brian; Dixon, David; Eldridge, Rob; King, Simon

    2002-12-01

    The removal of natural organic matter (NOM) from drinking water supplies can be achieved by different processes, among them coagulation and adsorption. Synthetic waters made from concentrates of humic substances from reservoir and river waters were tested in the laboratory for ease of removAl of NOM by coagulation with cationic organic polymers and with alum, and by adsorption on anion exchangers. For polymers such as high molecular weight polydiallyldimethylammonium chloride (polyDADMAC) and cationic polyacrylamides of high charge, performance was nearly as effective as alum, with colour removals 86-100% of those obtained for alum. Ion exchange using the best commercially available resins designed for this purpose, a gel polystyrene and a macroporous acrylic resin, was more effective than alum treatment for two of the natural waters studied, but inferior for a third. The resins were overall superior to cationic polymers. The NOM was separated into four fractions based on hydrophobic and hydrophilic properties. Alum was not as effective as ion exchange for the elimination of individual ionic NOM fractions. It was better than cationic polymers for removal of humic and fulvic acids, although polyDADMAC was as good for one water. For the removal of charged compounds alum then polyDADMAC were the best performers for that water. Unequivocal evidence was obtained that coagulants remove material that is not adsorbed by resins, and vice versa. A combination of coagulation with a cationic polymer and adsorption by an anion exchanger removed essentially all of the NOM. The preference of the coagulants was for the larger, more hydrophobic molecules, and of resins for smaller highly charged hydrophilic molecules. Each fraction had trihalomethane formation potentials in the range 11-24 microg/mg, except for one water that was more reactive. Hence, the actual amount of each fraction in the original water becomes a crucial factor. PMID:12448555

  13. Biosorption of cationic basic dye and cadmium by the novel biosorbent Bacillus catenulatus JB-022 strain.

    PubMed

    Kim, Su Young; Jin, Mi Ra; Chung, Chang Ho; Yun, Yeoung-Sang; Jahng, Kwang Yeop; Yu, Kang-Yeol

    2015-04-01

    Biosorption of heavy metals and dyes is a promising technology that involves the removal of toxic metals from industrial wastes. The present study aims to screen the bacterial strains isolated from soils and polluted pond for their potential biosorption of both cationic dye and cadmium. Bacillus catenulatus JB-022 strain removed 58% and 66% of cationic basic blue 3 (BB3) and cadmium (Cd(II)) at the respective concentrations of 2000 mg/L and 150 mg/L. The biosorption equilibrium data were well fitted by the Langmuir adsorption isotherm, and the kinetic studies indicated that the biosorption followed the pseudo-second-order model. The biosorption kinetics showed that the equilibrium was reached within 10 min and 5 min for BB3 and Cd(II), respectively. According to the Langmuir model, the maximum uptakes of BB3 and Cd(II) by the JB-022 biomass were estimated to be 139.74 and 64.28 mg/g, respectively. To confirm the surface morphology and functional groups, field emission scanning electron microscope, energy-dispersive X-ray spectrometer, X-ray diffraction, and Fourier transform infrared spectroscopy analyses were carried out, and the results revealed that the biomass of JB-022 has carboxyl and phosphonate groups as potential surface functional groups capable of binding to cationic pollutants. In conclusion, B. catenulatus JB-022 is proposed as an excellent biosorbent with potentially important applications in removal of cationic pollutants from wastewaters. PMID:25454694

  14. Double copper sheath multiconductor instrumentation cable is durable and easily installed in high thermal or nuclear radiation area

    NASA Technical Reports Server (NTRS)

    Mc Crae, A. W., Jr.

    1967-01-01

    Multiconductor instrumentation cable in which the conducting wires are routed through two concentric copper tube sheaths, employing a compressed insulator between the conductors and between the inner and outer sheaths, is durable and easily installed in high thermal or nuclear radiation area. The double sheath is a barrier against moisture, abrasion, and vibration.

  15. Membranes Remove Metal Ions Fron Industrial Liquids

    NASA Technical Reports Server (NTRS)

    Hsu, W. P. L.; May, C.

    1983-01-01

    Use of membrane films affords convenient and economical alternative for removing and recovering metal cations present in low concentrations from large quantities of liquid solutions. Possible applications of membrane films include use in analytical chemistry for determination of small amounts of toxic metallic impurities in lakes, streams, and municipal effluents. Also suitable for use as absorber of certain pollutant gases and odors present in confined areas.

  16. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  17. Antibacterial properties of cationic steroid antibiotics.

    PubMed

    Savage, Paul B; Li, Chunhong; Taotafa, Uale; Ding, Bangwei; Guan, Qunying

    2002-11-19

    Cationic steroid antibiotics have been developed that display broad-spectrum antibacterial activity. These compounds are comprised of steroids appended with amine groups arranged to yield facially amphiphilic morphology. Examples of these antibiotics are highly bactericidal, while related compounds effectively permeabilize the outer membranes of Gram-negative bacteria sensitizing these organisms to hydrophobic antibiotics. Cationic steroid antibiotics exhibit various levels of eukaryote vs. prokaryote cell selectivity, and cell selectivity can be increased via charge recognition of prokaryotic cells. Studies of the mechanism of action of these antibiotics suggest that they share mechanistic aspects with cationic peptide antibiotics. PMID:12445638

  18. Easily repairable networks

    NASA Astrophysics Data System (ADS)

    Fink, Thomas

    2015-03-01

    We introduce a simple class of distribution networks which withstand damage by being repairable instead of redundant. Instead of asking how hard it is to disconnect nodes through damage, we ask how easy it is to reconnect nodes after damage. We prove that optimal networks on regular lattices have an expected cost of reconnection proportional to the lattice length, and that such networks have exactly three levels of structural hierarchy. We extend our results to networks subject to repeated attacks, in which the repairs themselves must be repairable. We find that, in exchange for a modest increase in repair cost, such networks are able to withstand any number of attacks. We acknowledge support from the Defense Threat Reduction Agency, BCG and EU FP7 (Growthcom).

  19. Cation locations and dislocations in zeolites

    NASA Astrophysics Data System (ADS)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  20. Cation-cation clusters in ionic liquids: Cooperative hydrogen bonding overcomes like-charge repulsion

    PubMed Central

    Knorr, Anne; Ludwig, Ralf

    2015-01-01

    Direct spectroscopic evidence for H-bonding between like-charged ions is reported for the ionic liquid, 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate. New infrared bands in the OH frequency range appear at low temperatures indicating the formation of H-bonded cation-cation clusters similar to those known for water and alcohols. Supported by DFT calculations, these vibrational bands can be assigned to attractive interaction between the hydroxyl groups of the cations. The repulsive Coulomb interaction is overcome by cooperative hydrogen bonding between ions of like charge. The transition energy from purely cation-anion interacting configurations to those including cation-cation H-bonds is determined to be 3–4 kJmol−1. The experimental findings and DFT calculations strongly support the concept of anti-electrostatic hydrogen bonds (AEHBs) as recently suggested by Weinhold and Klein. The like-charge configurations are kinetically stabilized with decreasing temperatures. PMID:26626928

  1. Test procedure for cation exchange chromatography

    SciTech Connect

    Cooper, T.D.

    1994-08-24

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction.

  2. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    DOEpatents

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.

    1998-04-28

    A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate. 3 figs.

  3. Highly concentrated synthesis of copper-zinc-tin-sulfide nanocrystals with easily decomposable capping molecules for printed photovoltaic applications.

    PubMed

    Kim, Youngwoo; Woo, Kyoohee; Kim, Inhyuk; Cho, Yong Soo; Jeong, Sunho; Moon, Jooho

    2013-11-01

    Among various candidate materials, Cu2ZnSnS4 (CZTS) is a promising earth-abundant semiconductor for low-cost thin film solar cells. We report a facile, less toxic, highly concentrated synthetic method utilizing the heretofore unrecognized, easily decomposable capping ligand of triphenylphosphate, where phase-pure, single-crystalline, and well-dispersed colloidal CZTS nanocrystals were obtained. The favorable influence of the easily decomposable capping ligand on the microstructural evolution of device-quality CZTS absorber layers was clarified based on a comparative study with commonly used oleylamine-capped CZTS nanoparticles. The resulting CZTS nanoparticles enabled us to produce a dense and crack-free absorbing layer through annealing under a N2 + H2S (4%) atmosphere, demonstrating a solar cell with an efficiency of 3.6% under AM 1.5 illumination. PMID:24057000

  4. Selective adsorption of cationic dyes by UiO-66-NH2

    NASA Astrophysics Data System (ADS)

    Chen, Qi; He, Qinqin; Lv, Mengmeng; Xu, Yanli; Yang, Hanbiao; Liu, Xueting; Wei, Fengyu

    2015-02-01

    Herein, two zirconium(IV)-based MOFs UiO-66 and UiO-66-NH2 had been successfully prepared by a facile solvothermal method and were characterized by X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS), and zeta potential. They exhibit small size, large surface area, and can remove cationic dyes from aqueous solution more effectively than anionic dyes. This adsorption selectivity is due to the favorable electrostatic interactions between the adsorbents and cationic dyes. Furthermore, owing to the individual micropore structure of UiO-66-NH2 and its more negative zeta potential resulted from the charge balance for the protonation of -NH2, UiO-66-NH2 displays much higher adsorption capacity for cationic dyes and lower adsorption capacity for anionic dyes than UiO-66.

  5. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    NASA Astrophysics Data System (ADS)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-01

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  6. Synthesis, DTPA coupling and radio labeling of cationic aminodextran

    SciTech Connect

    Subramanian, G.; McAfee, J.G.; Schneider, R.F.; Zapf-Longo, C.; Palladino, E.; Lyons, B.J.; Roskopf, M.

    1984-01-01

    In glomerular diseases, the normal anionic charge of the basement membrane is lost at an early stage. Glomerular damage in rats has been detected more readily with cationic dextrans than with inulin. Hence, the authors attempted to demonstrate this phenomenon in vivo in rats with labeled cationic dextran. Aminated Dextran (AMDEX) was prepared by treating Dextran(mol. wt approx. = 15k) with sodium methoxide followed by a bromethylamine HBr in DMSO resulting in 10-25 aminogroups per mole. DTPA cyclic dianhydride was coupled to AMDEX using a weight ratio of 1:10 in 0.2 - 1.0 ml 0.42 M Hepes buffer at pH 7.4. Free DTPA was removed by gel filtration (Sephadex P6DG) or by using Centricon-10 (AMICON) centrifugal microconcentrators. AMDEX coupled with DTPA was labeled with Indium-111 in 0.25 M acetate buffer. Labeling yields were >90% by gel chromatography and electrophoresis (pH8.2 Barbitol buffer). AMEXDTPA was labeled also by ligand exchange with Tc-99m-Sn-citrate at neutral pH with a labeling yield of 30%. On electrophoresis, all the labeled samples retained their cationic character. The distribution of purified In-111 AMDEX, was compared with simultaneously IV injected Tc-99m DTPA in rats. The 2 hour urinary excretion, and renal clearance (calculated from the biexponential plasma clearance) were slower (70 to 80%) than those of DTPA, due to the larger molecular size of AMDEX. By 1 hr., 5% of the administered activity was retained in each kidney, probably due to adherence to anionic binding sites.

  7. Mechanism of oligonucleotide release from cationic liposomes.

    PubMed Central

    Zelphati, O; Szoka, F C

    1996-01-01

    We propose a mechanism for oligonucleotide (ODN) release from cationic lipid complexes in cells that accounts for various observations on cationic lipid-nucleic acid-cell interactions. Fluorescent confocal microscopy of cells treated with rhodamine-labeled cationic liposome/ fluorescein-labeled ODN (F-ODN) complexes show the F-ODN separates from the lipid after internalization and enters the nucleus leaving the fluorescent lipid in cytoplasmic structures. ODN displacement from the complex was studied by fluorescent resonance energy transfer. Anionic liposome compositions (e.g., phosphatidylserine) that mimic the cytoplasmic facing monolayer of the cell membrane released ODN from the complex at about a 1:1 (-/+) charge ratio. Release was independent of ionic strength and pH. Physical separation of the F-ODN from monovalent and multivalent cationic lipids was confirmed by gel electrophoresis. Fluid but not solid phase anionic liposomes are required, whereas the physical state of the cationic lipids does not effect the release. Water soluble molecules with a high negative linear charge density, dextran sulfate, or heparin also release ODN. However, ATP, spermidine, spermine, tRNA, DNA, polyglutamic acid, polylysine, bovine serum albumin, or histone did not release ODN, even at 100-fold charge excess (-/+). Based upon these results, we propose that the complex, after internalization by endocytosis, induces flip-flop of anionic lipids from the cytoplasmic facing monolayer. Anionic lipids laterally diffuse into the complex and form a charged neutralized ion-pair with the cationic lipids. This leads to displacement of the ODN from the cationic lipid and its release into the cytoplasm. Images Fig. 1 Fig. 3 PMID:8876163

  8. Reactions and structural investigation of chlorpromazine radical cation

    NASA Astrophysics Data System (ADS)

    Joshi, Ravi; Ghanty, Tapan K.; Mukherjee, T.

    2008-10-01

    Experimental and theoretical studies have been carried out to understand pro-oxidant behaviour of chlorpromazine radical cation (CPZ rad + ). Pulse radiolysis studies have shown that CPZ rad + oxidizes physiological antioxidants (uric acid and bilirubin), and biomolecules like, tyrosine and proteins (bovine serum albumin and casein), thereby acting as a pro-oxidant. Ab-initio quantum chemical calculations suggest structural and electronic changes on oxidation of CPZ. The calculations with Hartree-Fock and density functional methods show that ring nitrogen atom is the site of electron removal from CPZ and sulfur atom is the site of maximum spin in CPZ rad + . The calculations also suggest that oxidation of CPZ leads to increase in planarity of the tricyclic ring as well as tilting of alkyl side chain towards chlorine containing ring. The structural changes on oxidation of CPZ and spin delocalization in CPZ rad + fairly explain the pro-oxidant activity of CPZ.

  9. Cation-ratio dating of petroglyphs using PIXE

    NASA Astrophysics Data System (ADS)

    Whitley, David S.; Dorn, Ronald I.

    1988-12-01

    A central problem in archaeological research has been the Chronometrie dating of petroglyphs (rock engravings). Recent improvements in the understanding of the chemistry of rock varnish (or patina) that develops on rock surfaces in arid regions has resulted in the development of a calibrated dating technique, cation-ratio (CR) dating. This is based on calibrating chemical changes in minor and major trace elements in the varnish over time. PIXE is used to determine the bulk chemical constituents of small samples of varnish mechanically removed from within petroglyphs. Recent applications in western North America have yielded petroglyph dates of great importance in understanding the origins of art and the antiquity of human settlement in the western hemisphere. In particular the CR dates on petroglyphs suggest that humans moved into the New World about 10 K yrs earlier than previously believed, and that the making of petroglyphs was one of the most ancient and long-lived cultural traditions in aboriginal North America.

  10. Amitriptyline removal using palygorskite clay.

    PubMed

    Tsai, Yo-Lin; Chang, Po-Hsiang; Gao, Zong-You; Xu, Xiao-Yuan; Chen, Yan-Hsin; Wang, Zheng-Hong; Chen, Xin-Yu; Yang, Zheng-Ying; Wang, Tzu-Hao; Jean, Jiin-Shuh; Li, Zhaohui; Jiang, Wei-Teh

    2016-07-01

    With the increased detections of commonly used pharmaceuticals in surface water and wastewater, extensive attentions were paid recently to the fate and transport of these pharmaceuticals in the environment. Amitriptyline (AMI) is a tricyclic antidepressant widely applied to treat patients with anxiety and depression. In this study, the removal of AMI with palygorskite clay (PFl-1) was investigated under different physico-chemical conditions and supplemented by instrumental analyses. The uptake of AMI on PFl-1 was well fitted by the Langmuir isotherm with an adsorption capacity of 0.168 mmol g(-1) at pH 6-7. The AMI uptake was fast and reached equilibrium in 15 min. The X-ray diffraction patterns showed no shift of the (110) peak position of palygorskite after AMI uptake. However, the (001) peak position of the minor component smectite (about 10%) shifted to lower angle as the amounts of AMI input increased. These results suggested surface uptake of AMI on palygorskite and interlayer uptake of AMI in smectite. As smectite is a common component of palygorskite clays, its role in assessing the properties and performances of palygorskite clays for the uptake and removal of contaminants should not be neglected. Overall, the high affinity of AMI for PFl-1 and strong retention of AMI on PFl-1 suggested that it could be a good adsorbent to remove AMI from wastewater. Palygorskite clays can also be a sink for many cationic pharmaceuticals in the environmental of the arid regions. PMID:27131449

  11. Synthesis and Performance Properties of Cationic Fabric Softeners Derived from Free Fatty Acid of Tallow Fat.

    PubMed

    Mondal, Mithun G; Pratap, Amit Prabhakar

    2016-08-01

    Esterquat cationic softener is basically the class of surface active quaternary ammonium compounds. Esterquat compounds were synthesized and their surface behavior, antibacterial activity and Textile softening properties were investigated. Easily found cheap material was used to synthesize cationic fabric softeners. This fabric softener will be a good for commercially and industrially important because their emulsify activity, rewettability dispersing power and softness. Free fatty acids were derived from tallow oil and were treated with triethanolamine and mono-ethanolamine at 140°C. This diester was quaternaries with dimethyl sulphate and benzyl chloride. The synthesized esterquat compounds were characterized by its cationic content, 1H NMR and FT-IR analysis. In addition to the cationic content, surface tension, CMC (critical micelle concentration), rewettability, fabric softening, emulsification and dispersing power were determined as their surface-active properties. The fabric softening activity of esterquat and esteramide prepared from DMS was better softening activity of fabrics compared to untreated cotton and polyester fabrics cloth. The presented result shows that the esterquat made from BCl exhibit the best dispersing power. The esterquat made from DMS both in TEA and MEA shows good rewettability was determined. PMID:27430381

  12. Cation and anion release from broiler litter and cake activated carbons and the role of released anions in copper ion uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of activated carbons from broiler litter and broiler cake results in a large ash fraction that can be removed by acid treatment. The primary use for these carbons is in the removal of metal cations from aqueous solution. The objectives of this study were 1) to determine the extent t...

  13. Cationic isotachophoresis separation of the biomarker cardiac troponin I from a high-abundance contaminant, serum albumin

    PubMed Central

    Jacroux, Thomas; Bottenus, Danny; Rieck, Bennett; Ivory, Cornelius F.; Dong, Wen-ji

    2014-01-01

    Cationic ITP was used to separate and concentrate fluorescently tagged cardiac troponin I (cTnI) from two proteins with similar isoelectric properties in a PMMA straight-channel microfluidic chip. In an initial set of experiments, cTnI was effectively separated from R-Phycoerythrin using cationic ITP in a pH 8 buffer system. Then, a second set of experiments was conducted in which cTnI was separated from a serum contaminant, albumin. Each experiment took ~ 10 min or less at low electric field strengths (34 V/cm) and demonstrated that cationic ITP could be used as an on-chip removal technique to isolate cTnI from albumin. In addition to the experimental work, a 1D numerical simulation of our cationic ITP experiments has been included to qualitatively validate experimental observations. PMID:24723384

  14. Cationic isotachophoresis separation of the biomarker cardiac troponin I from a high-abundance contaminant, serum albumin.

    PubMed

    Jacroux, Thomas; Bottenus, Danny; Rieck, Bennett; Ivory, Cornelius F; Dong, Wen-Ji

    2014-07-01

    Cationic ITP was used to separate and concentrate fluorescently tagged cardiac troponin I (cTnI) from two proteins with similar isoelectric properties in a PMMA straight-channel microfluidic chip. In an initial set of experiments, cTnI was effectively separated from R-Phycoerythrin using cationic ITP in a pH 8 buffer system. Then, a second set of experiments was conducted in which cTnI was separated from a serum contaminant, albumin. Each experiment took ∼10 min or less at low electric field strengths (34 V/cm) and demonstrated that cationic ITP could be used as an on-chip removal technique to isolate cTnI from albumin. In addition to the experimental work, a 1D numerical simulation of our cationic ITP experiments has been included to qualitatively validate experimental observations. PMID:24723384

  15. Anomalous but massive removal of two organic dye pollutants simultaneously.

    PubMed

    Meng, Zilin; Zhang, Yihe; Zhang, Zhilei; Zhang, Qian; Chu, Paul K; Komarneni, Sridhar; Lv, Fengzhu

    2016-11-15

    A one-pot method to remove two organic dye contaminants and alkali simultaneously from alkaline wastewater was developed by forming Zn-Al layered double hydroxide (ZnAl-LDH). Using this process, not only alkali but also methyl orange (MO), an anionic contaminant was totally removed from wastewater. In addition, cationic contaminant, methylene blue (MB) was also removed effectively while maintaining the high removal efficiency of MO. The removal efficiency of MO was almost 100% and the pH of the treated wastewater decreased from 12 to 7.38. The charge-limited removal process, molecular arrangement of the contaminants in LDHs, and the anomalous removal mechanism were analyzed experimentally and through simulation. After MO accumulated in the interlayers of LDH by electrostatic interaction, MB entered and trapped by hydrophobic interaction. PMID:27399147

  16. Innate cation sensitivity in a semiconducting polymer.

    PubMed

    Althagafi, Talal M; Algarni, Saud A; Grell, Martin

    2016-09-01

    Water-gated organic thin film transistors (OTFTs) using the hole transporting semiconducting polymer, poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), show an innate response of their threshold voltage to the addition of divalent metal cations to the gating water, without deliberately introducing an ion-sensitive component. A similar threshold response is shown for several divalent cations, but is absent for monovalent cations. Response is absent for transistors using the inorganic semiconductor ZnO, or the similar organic semiconductor poly(3-hexylthiophene) (rrP3HT), instead of PBTTT. We assign innate cation sensitivity to residues of the organometallic Pd(0) complex used as catalyst in PBTTT synthesis which bears strong resemblance to typical metal chelating agents. Organometallic Pd(0) residues are absent from ZnO, and also from rrP3HT which is polymerised with a different type of catalyst. However, when Pd(0) complex is deliberately added to rrP3HT casting solutions, resulting OTFTs also display threshold response to a divalent cation. PMID:27343580

  17. Highly concentrated synthesis of copper-zinc-tin-sulfide nanocrystals with easily decomposable capping molecules for printed photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Kim, Youngwoo; Woo, Kyoohee; Kim, Inhyuk; Cho, Yong Soo; Jeong, Sunho; Moon, Jooho

    2013-10-01

    Among various candidate materials, Cu2ZnSnS4 (CZTS) is a promising earth-abundant semiconductor for low-cost thin film solar cells. We report a facile, less toxic, highly concentrated synthetic method utilizing the heretofore unrecognized, easily decomposable capping ligand of triphenylphosphate, where phase-pure, single-crystalline, and well-dispersed colloidal CZTS nanocrystals were obtained. The favorable influence of the easily decomposable capping ligand on the microstructural evolution of device-quality CZTS absorber layers was clarified based on a comparative study with commonly used oleylamine-capped CZTS nanoparticles. The resulting CZTS nanoparticles enabled us to produce a dense and crack-free absorbing layer through annealing under a N2 + H2S (4%) atmosphere, demonstrating a solar cell with an efficiency of 3.6% under AM 1.5 illumination.Among various candidate materials, Cu2ZnSnS4 (CZTS) is a promising earth-abundant semiconductor for low-cost thin film solar cells. We report a facile, less toxic, highly concentrated synthetic method utilizing the heretofore unrecognized, easily decomposable capping ligand of triphenylphosphate, where phase-pure, single-crystalline, and well-dispersed colloidal CZTS nanocrystals were obtained. The favorable influence of the easily decomposable capping ligand on the microstructural evolution of device-quality CZTS absorber layers was clarified based on a comparative study with commonly used oleylamine-capped CZTS nanoparticles. The resulting CZTS nanoparticles enabled us to produce a dense and crack-free absorbing layer through annealing under a N2 + H2S (4%) atmosphere, demonstrating a solar cell with an efficiency of 3.6% under AM 1.5 illumination. Electronic supplementary information (ESI) available: Experimental methods for CZTS nanocrystal synthesis, device fabrication, and characterization; the size distribution and energy dispersive X-ray (EDX) spectra of the synthesized CZTS nanoparticles; UV-vis spectra of the

  18. Sorting chromatic sextupoles for easily and effectively correcting second order chromaticity in the Relativistic Heavy Ion Collider

    SciTech Connect

    Luo,Y.; Tepikian, S.; Fischer, W.; Robert-Demolaize, G.; Trbojevic, D.

    2009-01-02

    Based on the contributions of the chromatic sextupole families to the half-integer resonance driving terms, we discuss how to sort the chromatic sextupoles in the arcs of the Relativistic Heavy Ion Collider (RHIC) to easily and effectively correct the second order chromaticities. We propose a method with 4 knobs corresponding to 4 pairs of chromatic sextupole families to online correct the second order chromaticities. Numerical simulation justifies this method, showing that this method reduces the unbalance in the correction strengths of sextupole families and avoids the reversal of sextupole polarities. Therefore, this method yields larger dynamic apertures for the proposed RHIC 2009 100GeV polarized proton run lattices.

  19. Controlling the actuation properties of MXene paper electrodes upon cation intercalation

    SciTech Connect

    Come, Jeremy E.; Black, Jennifer M.; Naguib, Michael; Lukatskaya, Maria R.; Beidaghi, Majid; Wesolowski, David J.; Gogotsi, Yury; Rondinone, Adam J.; Balke, Nina; Kalinin, Sergei V.

    2015-08-05

    Atomic force microscopy was used to monitor the macroscopic deformation in a delaminated Ti₃C₂ paper electrode in-situ, during charge/discharge in a variety of aqueous electrolytes to examine the effect of the cation intercalation on the electrochemical behavior and mechanical response. The results show a strong dependence of the electrode deformation on cation size and charge. The electrode undergoes a large contraction during Li⁺, Na⁺ or Mg²⁺ intercalation, differentiating the Ti₃C₂ paper from conventional electrodes where redox intercalation of ions (e.g. Li⁺) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. This feature may explain the excellent rate performance and cyclability reported for MXenes. We also demonstrated that the variation of the electromechanical contraction can be easily adjusted by electrolyte exchange, and shows interesting characteristics for the design of actuators based on 2D metal carbides.

  20. Cationic rhenium complexes ligated with N-heterocyclic carbenes - an overview.

    PubMed

    Hille, Claudia; Kühn, Fritz E

    2016-01-01

    This review provides an overview of the currently known cationic rhenium NHC complexes. Synthesis, structures and properties are described. The title compounds are potential candidates for both catalytic and medical applications. Besides the variety of ancillary ligands, which are in some cases easily substituted, functionalization can be carried out in the side chain or at the backbone of the carbene ligand as well as - in the case of biscarbene ligands - at the bridging moiety. Cationic Re NHC complexes are promising precursors for radiopharmaceuticals and diagnostics - not only because of the possibility to radiolabel the metal (steps in this direction have been made and described already) - but rather the opportunity to link the complexes to biomolecules via the different possibilities provided by the ligands. The development of OLEDs based on luminescent Re(i) carbene complexes renders another potential application. PMID:26587970

  1. Cation-pi interactions as a mechanism in technical lignin adsorption to cationic surfaces.

    PubMed

    Pillai, Karthik V; Renneckar, Scott

    2009-04-13

    The assembly of dissolved technical lignins in aqueous and organic medium has been studied at the solid-liquid interface. Adsorption of alkali lignin onto gold coated crystals treated with a cationic polymer was determined using a quartz crystal microbalance with dissipation monitoring. Complete coverage of the cationic surface with alkali lignin occurred at low solution concentration, revealing a high affinity coefficient under both alkali and neutral conditions. With additional adsorption studies from organosolv lignin in organic solvent and spectroscopic analysis of mixtures of cationic polymer and alkali lignin, a noncovalent interaction between lignin's aromatic rings and the cation of the quaternary ammonium group was shown to exist. The work underscores how polyphenolic biopolymers can strongly interact with cations through noncovalent interactions to control molecular architecture. PMID:19226174

  2. UTILITY OF ZEOLITES IN ARSENIC REMOVAL FROM WATER

    EPA Science Inventory

    Zeolites are well known for their ion exchange and adsorption properties. So far the cation exchanger properties of zeolites have been extensively studied and utilized. The anion exchanger properties of zeolites are less studied. Zeolite Faujasite Y has been used to remove arseni...

  3. REMOVAL OF CESIUM BY SORPTION FROM AQUEOUS SOLUTIONS

    DOEpatents

    Ames, L.L.

    1962-01-16

    ABS>A process is given for selectively removing cesium from acid aqueous solutions containing cesium in microquantities and other cations in macroquantities by absorption on clinoptilolite. The cesium can be eluted from the clinoptilolite with a solution of ammonia, potassium hydroxide, or rubidium hydroxide. (AEC)

  4. EVALUATING ION EXCHANGE FOR REMOVING RADIUM FROM GROUNDWATER

    EPA Science Inventory

    This article focuses on the results of bench and pilot-scale studies of ion exchange processes for radium removal from groundwater in Lemont, Ill. atch and column studies indicated a very high resin selectivity for radium compared with common cations. xhaustion-regeneration studi...

  5. EVALUATING ION EXCHANGE FOR REMOVING RADIUM FROM GROUNDWATER

    EPA Science Inventory

    This article, the second in a series, focuses on the results of bench- and pilot-scale studies of ion exchange processes for radium removal from groundwater in Lemont, Ill. Batch and column studies indicated a very high resin selectivity for radium compared with common cations. E...

  6. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1991-10-01

    The objective of this project is to make use of products obtained from renewable plant sources as monomers for the direct production of polymers which can be used for a wide range of plastic applications. In this report is described progress in the synthesis and polymerization of cationically polymerizable monomers and oligomers derived from botanical oils, terpenes, natural rubber, and lignin. Nine different botanical oils were obtained from various sources, characterized and then epoxidized. Their photopolymerization was carried out using cationic photoinitiators and the mechanical properties of the resulting polymers characterized. Preliminary biodegradation studies are being conducted on the photopolymerized films from several of these oils. Limonene was cationically polymerized to give dimers and the dimers epoxidized to yield highly reactive monomers suitable for coatings, inks and adhesives. The direct phase transfer epoxidation of squalene and natural rubber was carried out. The modified rubbers undergo facile photocrosslinking in the presence of onium salts to give crosslinked elastomers. 12 refs., 3 figs., 10 tabs.

  7. Solution of trivalent cations into uranium dioxide

    NASA Astrophysics Data System (ADS)

    Middleburgh, S. C.; Parfitt, D. C.; Grimes, R. W.; Dorado, B.; Bertolus, M.; Blair, P. R.; Hallstadius, L.; Backman, K.

    2012-01-01

    The accommodation of trivalent oxides (M 2O 3) in uranium dioxide has been investigated using atomic scale simulation. Calculations suggest that all trivalent oxides studied preferentially enter UO 2 by associating the substitutional ion with an oxygen vacancy, larger cations forming the cluster {2MU':VOrad rad }×. Solution into hyper-stoichiometric UO 2+ x was accompanied by the formation of the {MU':UUrad }× cluster and smaller solution energies than into stoichiometric UO 2. Solubility is a particularly strong function of hyper-stoichiometry for smaller cations such as Cr 3+, which has implications for the use of Cr 2O 3 as a grain enlarger but not so for larger cations such s Gd 3+.

  8. Cationic Lipid-Based Nucleic Acid Vectors.

    PubMed

    Jubeli, Emile; Goldring, William P D; Pungente, Michael D

    2016-01-01

    The delivery of nucleic acids into cells remains an important laboratory cell culture technique and potential clinical therapy, based upon the initial cellular uptake, then translation into protein (in the case of DNA), or gene deletion by RNA interference (RNAi). Although viral delivery vectors are more efficient, the high production costs, limited cargo capacity, and the potential for clinical adverse events make nonviral strategies attractive. Cationic lipids are the most widely applied and studied nonviral vectors; however, much remains to be solved to overcome limitations of these systems. Advances in the field of cationic lipid-based nucleic acid (lipoplex) delivery rely upon the development of robust and reproducible lipoplex formulations, together with the use of cell culture assays. This chapter provides detailed protocols towards the formulation, delivery, and assessment of in vitro cationic lipid-based delivery of DNA. PMID:27436310

  9. Development and validation of a quick easily used biochemical assay for evaluating the viability of small immobile arthropods.

    PubMed

    Phillips, Craig B; Iline, Ilia I; Richards, Nicola K; Novoselov, Max; McNeill, Mark R

    2013-10-01

    Quickly, accurately, and easily assessing the efficacy of treatments to control sessile arthropods (e.g., scale insects) and stationary immature life stages (e.g., eggs and pupae) is problematic because it is difficult to tell whether treated organisms are alive or dead. Current approaches usually involve either maintaining organisms in the laboratory to observe them for development, gauging their response to physical stimulation, or assessing morphological characters such as turgidity and color. These can be slow, technically difficult, or subjective, and the validity of methods other than laboratory rearing has seldom been tested. Here, we describe development and validation of a quick easily used biochemical colorimetric assay for measuring the viability of arthropods that is sufficiently sensitive to test even very small organisms such as white fly eggs. The assay was adapted from a technique for staining the enzyme hexokinase to signal the presence of adenosine triphosphate in viable specimens by reducing a tetrazolium salt to formazan. Basic laboratory facilities and skills are required for production of the stain, but no specialist equipment, expertise, or facilities are needed for its use. PMID:24224241

  10. Hemoglobin levels and circulating blasts are two easily evaluable diagnostic parameters highly predictive of leukemic transformation in primary myelofibrosis.

    PubMed

    Rago, Angela; Latagliata, Roberto; Montanaro, Marco; Montefusco, Enrico; Andriani, Alessandro; Crescenzi, Sabrina Leonetti; Mecarocci, Sergio; Spirito, Francesca; Spadea, Antonio; Recine, Umberto; Cicconi, Laura; Avvisati, Giuseppe; Cedrone, Michele; Breccia, Massimo; Porrini, Raffaele; Villivà, Nicoletta; De Gregoris, Cinzia; Alimena, Giuliana; D'Arcangelo, Enzo; Guglielmelli, Paola; Lo-Coco, Francesco; Vannucchi, Alessandro; Cimino, Giuseppe

    2015-03-01

    To predict leukemic transformation (LT), we evaluated easily detectable diagnostic parameters in 338 patients with primary myelofibrosis (PMF) followed in the Latium region (Italy) between 1981 and 2010. Forty patients (11.8%) progressed to leukemia, with a resulting 10-year leukemia-free survival (LFS) rates of 72%. Hb (<10g/dL), and circulating blasts (≥1%) were the only two independent prognostic for LT at the multivariate analysis. Two hundred-fifty patients with both the two parameters available were grouped as follows: low risk (none or one factor)=216 patients; high risk (both factors)=31 patients. The median LFS times were 269 and 45 months for the low and high-risk groups, respectively (P<.0001). The LT predictive power of these two parameters was confirmed in an external series of 270 PMF patients from Tuscany, in whom the median LFS was not reached and 61 months for the low and high risk groups, respectively (P<.0001). These results establish anemia and circulating blasts, two easily and universally available parameters, as strong predictors of LT in PMF and may help to improve prognostic stratification of these patients particularly in countries with low resources where more sophisticated molecular testing is unavailable. PMID:25636356

  11. Synthesis and properties of a cation exchange resin prepared by the pyrolysis of starch in the presence of phytic acid

    SciTech Connect

    Lehrfeld, J.

    1995-12-01

    A material having cation exchange and adsorption properties was prepared by the controlled pyrolysis of starch in the presence of a commercial phytic acid solution. Resins can be prepared with binding capacities of 0.7-5.7 meq/g. These resins also have the ability to remove atrazine from aqueous solutions.

  12. Tuning cation-binding selectivity and capacity via side chain-dependent molecular packing in the solid state.

    PubMed

    Shen, Jie; Ren, Changliang; Zeng, Huaqiang

    2016-08-16

    Cavity-containing cation-binding pentameric macrocycles readily assemble, via side chain-dependent molecular packing, into either 1D nanotube bundles with the smallest being 10 nm in diameter or nanoplates of different sizes. The resultant nanostructures are able to selectively remove metal salts from aqueous solutions with varying selectivities and capacities. PMID:27476578

  13. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year's research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  14. ABSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Tompkins, E.R.; Parker, G.W.

    1959-03-10

    An improved method is presented for the chromatographic separation of fission products wherein a substantial reduction in liquid volume is obtained. The process consists in contacting a solution containing fission products with a body of ion-exchange adsorbent to effect adsorption of fission product cations. The loaded exchange resin is then contacted with a small volume of a carboxylic acid eluant, thereby recovering the fission products. The fission product carrying eluate is acidified without increasing its volume to the volume of the original solution, and the acidified eluate is then used as a feed solution for a smaller body of ion-exchange resin effecting readsorption of the fission product cations.

  15. Solubilization of growth hormone and other recombinant proteins from Escherichia coli inclusion bodies by using a cationic surfactant.

    PubMed Central

    Puri, N K; Crivelli, E; Cardamone, M; Fiddes, R; Bertolini, J; Ninham, B; Brandon, M R

    1992-01-01

    Recombinant pig growth hormone (rPGH) was solubilized from inclusion bodies by using the cationic surfactant cetyltrimethylammonium chloride (CTAC). The solubilizing action of CTAC appeared to be dependent on the presence of a positively charged head group, as a non-charged variant was inactive. Relatively low concentrations of CTAC were required for rapid solubilization, and protein-bound CTAC was easily removed by ion-exchange chromatography. Compared with solubilization and recovery of rPGH from inclusion bodies with 7.5 M-urea and 6 M-guanidinium chloride, the relative efficiency of solubilization was lower with CTAC. However, superior refolding efficiency resulted in final yields of purified rPGH being in the order of CTAC greater than urea greater than or equal to guanidinium chloride. Detailed comparison of the different rPGH preparations as well as pituitary-derived growth hormone by h.p.l.c., native PAGE, c.d. spectral analysis and radioreceptor-binding assay showed that the CTAC-derived rPGH was essentially indistinguishable from the urea and guanidinium chloride preparations. The CTAC-derived rPGH was of greater biopotency than pituitary-derived growth hormone. The advantages of CTAC over urea and guanidinium chloride for increasing recovery of monomeric rPGH by minimizing aggregation during refolding in vitro were also found with recombinant sheep interleukin-I beta and a sheep insulin-like growth factor II fusion protein. In addition, the bioactivity of the CTAC-derived recombinant interleukin-1 beta was approximately ten-fold greater than that of an equivalent amount obtained from urea and guanidinium chloride preparations. It is concluded that CTAC represents, in general, an excellent additional approach or a superior alternative to urea and in particular guanidinium chloride for solubilization and recovery of bioactive recombinant proteins from inclusion bodies. Images Fig. 1. Fig. 3. Fig. 5. Fig. 9. PMID:1497625

  16. Improved Proteome and Phosphoproteome Analysis on a Cation Exchanger by a Combined Acid and Salt Gradient.

    PubMed

    Adachi, Jun; Hashiguchi, Kazunari; Nagano, Maiko; Sato, Misako; Sato, Ayako; Fukamizu, Kazuna; Ishihama, Yasushi; Tomonaga, Takeshi

    2016-08-16

    Currently used elution methods for strong cation exchange (SCX) chromatography are based on two principles: salt and pH gradient. In this paper, we report the first observation of peptide elution by acid gradient. The degree of peptide separation using C18-SCX StageTip was greatly improved by our acid and salt-based elution method compared with a salt-based elution method. This development enabled us to identify over 22 000 phosphopeptides from 2 mg of protein without labor-intensive sample preparation. Our method is simple, robust, scalable, and low-cost and can be easily implemented without any special equipment or techniques. PMID:27436111

  17. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

    PubMed

    Tu, Renyong; Xie, Yi; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; Trizio, Luca De; Manna, Liberato

    2016-06-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum. PMID:27177274

  18. Ionic liquid incorporating thiosalicylate for metal removal

    NASA Astrophysics Data System (ADS)

    Wilfred, Cecilia Devi; Mustafa, Fadwa Babiker; Romeli, Fatimah Julia

    2012-09-01

    Ionic liquids are a class of organic molten salts "designer solvents" that are composed totally of anions (inorganic and organic polyatomic) and organic cations. The replacement of volatile organic solvents from a separation process is of utmost importance since the use of a large excess of these solvents is hazardous and creates ecological problem. The new method for metal ion extraction is by using task-specific ionic liquids such as ionic liquids which incorporate thiosalicylate functionality. This paper looks at producing a new cluster of ionic liquids which incorporates thiosalicylate with pyridinium cation. Its thermophysical properties such as density and viscosity in single and binary mixtures are studied. The ionic liquids' capability in metal removal processes is evaluated.

  19. Novel phosphorus-containing cyclodextrin polymers and their affinity for calcium cations and hydroxyapatite.

    PubMed

    Wintgens, Véronique; Dalmas, Florent; Sébille, Bernard; Amiel, Catherine

    2013-10-15

    Novel phosphorous-containing β-cyclodextrin (βCD) polymers (CDP) were synthesized easily under "green chemistry" conditions. A simple polycondensation between the hydroxyl groups of βCD and non-toxic sodium trimetaphosphate (STMP) under basic conditions led to soluble, non-reticulated CDPs with molecular weights (Mw) higher than 10(4) g mol(-1), the actual value depending on the NaOH:βCD and STMP:βCD weight ratios. The presence of both βCD and phosphate groups in the polymer allows for strong interactions with amphiphilic probes, such as 1-adamantyl acetic acid, or with divalent cations, such as Ca(2+), whose strengths were characterized by isothermal titration microcalorimetry. The obtained phosphated compounds also display high affinity towards hydroxyapatite (HA), leading to HA nanoparticles that could easily be recovered by CDPs, as demonstrated by transmission electron microscopy and quantitative determination of the total amount of phosphated molecules fixed on HA. PMID:23987426

  20. On easily tunable wide-bandpass X-ray monochromators based on refraction in arrays of prisms.

    PubMed

    Jark, Werner

    2012-07-01

    Refractive lenses focus X-rays chromatically owing to a significant variation of the refractive index of the lens material with photon energy. Then, in combination with an exit slit in the focal plane, such lenses can be used as monochromators. The spectral resolution obtainable with refractive lenses based on prism arrays was recently systematically investigated experimentally. This contribution will show that a wide-bandpass performance can be predicted with a rather simple analytical approach. Based on the good agreement with the experimental data, one can then more rapidly and systematically optimize the lens structure for a given application. This contribution will then discuss more flexible solutions for the monochromator operation. It will be shown that a new monochromator scheme could easily provide tuning in a fixed-exit slit. PMID:22713879

  1. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation.

    PubMed

    Finnerty, Justin John; Peyser, Alexander; Carloni, Paolo

    2015-01-01

    Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores. PMID:26460827

  2. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    SciTech Connect

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.

    1996-12-31

    The problems associated with the disposal of toxic metals in an environmentally acceptable manner continues to plague industry. Such metals as nickel, vanadium, molybdenum, cobalt, iron, and antimony present physiological and ecological challenges that are best addressed through minimization of exposure and dispersion. A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  3. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation

    PubMed Central

    Finnerty, Justin John

    2015-01-01

    Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores. PMID:26460827

  4. A comprehensive risk assessment for tephra accumulation using easily accessible data: the example of Cotopaxi volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Biass, Sébastien; Frischknecht, Corine; Dell'Oro, Luca; Senegas, Olivier; Bonadonna, Costanza

    2010-05-01

    In order to answer the needs of contingency planning, we present a GIS-based method for risk assessment of tephra deposits, which is flexible enough to work with datasets of variable precision and resolution depending on data availabilty. Due to the constant increase of population density around volcanoes and the large dispersal of tephra from volcanic plumes, a wide range of threats such as roof collapses, destruction of crops, blockage of vital lifelines and health problems concern even remote communities. In the field of disaster management, there is a general agreement that a global and incomplete method, subject to revision and improvements, is better than no information at all. In this framework, our method is able to provide fast and rough insights on possible eruptive scenarios and their potential consequences on surrounding populations with only few available data, which can easily be refined later. Therefore, the knowledge of both the expected hazard (frequency and magnitude) and the vulnerability of elements at risk are required by planners in order to produce efficient emergency planning prior to a crisis. The Cotopaxi volcano, one of Ecuador's most active volcanoes, was used to develop and test this method. Cotopaxi volcano is located 60 km south of Quito and threatens a highly populated valley. Based on field data, historical reports and the Smithsonian catalogue, our hazard assessment was carried out using the numerical model TEPHRA2. We first applied a deterministic approach that evolved towards a fully probabilistic method in order to account for the most likely eruptive scenarios as well as the variability of atmospheric conditions. In parallel, we carried out a vulnerability assessment of the physical (crops and roofs), social (populations) and systemic elements-at-risk by using mainly free and easily accessible data. Both hazard and vulnerability assessments were compiled with GIS tools to draw comprehensive and tangible thematic risk maps

  5. Viscoelastic cationic polymers containing the urethane linkage

    NASA Technical Reports Server (NTRS)

    Rembaum, A. (Inventor)

    1972-01-01

    A method for the synthesis and manufacturing of elastomeric compositions and articles containing quaternary nitrogen centers and condensation residues along the polymeric backbone of the centers is presented. Linear and cross-linked straight chain and block polymers having a wide damping temperature range were synthesized. Formulae for the viscoelastic cationic polymers are presented.

  6. NMR studies of cation transport across membranes

    SciTech Connect

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

  7. ADSORPTION OF ORGANIC CATIONS TO NATURAL MATERIALS

    EPA Science Inventory

    The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. he sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concentrations of NaCl and CaC12,...

  8. ADSORPTION OF ORGANIC CATIONS TO NATURAL MATERIALS

    EPA Science Inventory

    The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. The sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concentrations of NaCl and CaCl,...

  9. Physicochemical properties of metal-doped activated carbons and relationship with their performance in the removal of SO2 and NO.

    PubMed

    Gao, Xiang; Liu, Shaojun; Zhang, Yang; Luo, Zhongyang; Cen, Kefa

    2011-04-15

    Several metal-doped activated carbons (Fe, Co, Ni, V, Mn, Cu and Ce) were prepared and characterized. The results of N(2) adsorption-desorption, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that some metals (Cu and Fe) were partly reduced by carbon during preparation. Activity tests for the removal of SO(2) and the selective catalytic reduction of NO with ammonia were carried out. Due to different physicochemical properties, different pathways for the SO(2) removal had been put out, i.e., catalytic oxidation, direct reaction and adsorption. This classification depended on the standard reduction potentials of metal redox pairs. Samples impregnated with V, Ce and Cu showed good activity for NO reduction by NH(3), which was also ascribed to the reduction potential values of metal redox pairs. Ce seemed to be a promising alternative to V due to the higher activity in NO reduction and the nontoxic property. A metal cation which could easily convert between the two valences seemed to be crucial to the good performance of both SO(2) and NO removal, just like V and Cu. PMID:21324585

  10. Synthesis of modified maghemite nanoparticles and its application for removal of Acridine Orange from aqueous solutions by using Box-Behnken design

    NASA Astrophysics Data System (ADS)

    Bagheban Shahri, Fatemeh; Niazi, Ali

    2015-12-01

    In this study, sodium dodecyl sulfate-coated maghemite nanoparticles (SDS-coated γ-Fe2O3 NPs), was used for removal of cationic dye Acridine Orange from water samples. The γ-Fe2O3 NPs were synthesized by co-precipitation method and were characterized by scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) to examine their size and magnetic moment. The adsorption experiments were performed using the batch system. The prepared magnetic adsorbent was well dispersed in water and easily separated magnetically from the medium after loaded with adsorbate. Four most important operating variables including initial pH of the solution, dosage of adsorbent, concentration of dye and contact time was studied and optimized by response surface methodology (RSM), involving Box-Behnken design matrix. Twenty-seven experiments were performed to investigate the effect of these parameters on removal of the dye. The results showed that initial pH of the solution was the most effective parameter in comparison with others. Also, experimental parameters were optimized and chose the best conditions by determination of effective factors. The optimized conditions for dye removal were at initial pH 5.1 0.8 g L-1 of adsorbent, 30.0 mg L-1 dye and 43 min adsorption time. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. The maximum predicted adsorption capacities for Acridine Orange was 285.82 mg g-1.

  11. Process and apparatus for the production of Bi-213 cations

    DOEpatents

    Horwitz, E.P.; Hines, J.J.; Chiarizia, R.; Dietz, M.

    1998-12-29

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed. 7 figs.

  12. Process and apparatus for the production of BI-213 cations

    DOEpatents

    Horwitz, E. Philip; Hines, John J.; Chiarizia, Renato; Dietz, Mark

    1998-01-01

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed.

  13. Thyroid gland removal

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002933.htm Thyroid gland removal To use the sharing features on this page, please enable JavaScript. Thyroid gland removal is surgery to remove all or ...

  14. Gallbladder removal - laparoscopic

    MedlinePlus

    Laparoscopic gallbladder removal is surgery to remove the gallbladder using a medical device called a laparoscope. ... lets the doctor see inside your belly. Gallbladder removal surgery is done while you are under general ...

  15. DESIGN MANUAL: PHOSPHORUS REMOVAL

    EPA Science Inventory

    This manual summarizes process design information for the best developed methods for removing phosphorus from wastewater. his manual discusses several proven phosphorus removal methods, including phosphorus removal obtainable through biological activity as well as chemical precip...

  16. Dendritic Cells Stimulated by Cationic Liposomes.

    PubMed

    Vitor, Micaela Tamara; Bergami-Santos, Patrícia Cruz; Cruz, Karen Steponavicius Piedade; Pinho, Mariana Pereira; Barbuto, José Alexandre Marzagão; De La Torre, Lucimara Gaziola

    2016-01-01

    Immunotherapy of cancer aims to harness the immune system to detect and destroy cancer cells. To induce an immune response against cancer, activated dendritic cells (DCs) must present tumor antigens to T lymphocytes of patients. However, cancer patients' DCs are frequently defective, therefore, they are prone to induce rather tolerance than immune responses. In this context, loading tumor antigens into DCs and, at the same time, activating these cells, is a tempting goal within the field. Thus, we investigated the effects of cationic liposomes on the DCs differentiation/maturation, evaluating their surface phenotype and ability to stimulate T lymphocytes proliferation in vitro. The cationic liposomes composed by egg phosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium propane and 1,2-dioleoylphosphatidylethanolamine (50/25/25% molar) were prepared by the thin film method followed by extrusion (65 nm, polydispersity of 0.13) and by the dehydration-rehydration method (95% of the population 107 nm, polydispersity of 0.52). The phenotypic analysis of dendritic cells and the analysis of T lymphocyte proliferation were performed by flow cytometry and showed that both cationic liposomes were incorporated and activated dendritic cells. Extruded liposomes were better incorporated and induced higher CD86 expression for dendritic cells than dehydrated-rehydrated vesicles. Furthermore, dendritic cells which internalized extruded liposomes also provided stronger T lymphocyte stimulation. Thus, cationic liposomes with a smaller size and polydispersity seem to be better incorporated by dendritic cells. Hence, these cationic liposomes could be used as a potential tool in further cancer immunotherapy strategies and contribute to new strategies in immunotherapy. PMID:27398454

  17. Characterization of activated sludge exocellular polymers using several cation-associated extraction methods.

    PubMed

    Park, Chul; Novak, John T

    2007-04-01

    Evaluation of prior research and preliminary investigations in our laboratory led to the development of an extraction strategy that can be used to target different cations in activated sludge floc and extract their associated extracellular polymeric substances (EPS). The methods we used were the cation exchange resin (CER) procedure, base extraction, and sulfide addition to extract EPS linked with divalent cations, Al, and Fe, respectively. A comparison of sludge cations before and after CER extraction revealed that most of Ca(2+) and Mg(2+) were removed while Fe and Al remained intact, suggesting that this method is highly selective for Ca(2+) and Mg(2+)-bound EPS. The correlation between sludge Fe and sulfide-extracted EPS was indicative of selectivity of this method for Fe-bound EPS. The base extraction was less specific than the other methods but it was the method releasing the largest amount of Al into the extract, indicating that the method extracted Al-bound EPS. Concomitantly, the composition of extracted EPS and the amino acid composition differed for the three methods, indicating that EPS associated with different metals were not the same. The change in EPS following anaerobic and aerobic digestion was also characterized by the three extraction methods. CER-extracted EPS were reduced after aerobic digestion while they changed little by anaerobic digestion. On the other hand, anaerobic digestion was associated with the decrease in sulfide-extracted EPS. These results suggest that different types of cation-EPS binding mechanisms exist in activated sludge and that each cation-associated EPS fraction imparts unique digestion characteristics to activated sludge. PMID:17346764

  18. Mixed-valent neptunium(IV/V) compound with cation-cation-bound six-membered neptunyl rings.

    PubMed

    Jin, Geng Bang

    2013-11-01

    A new mixed-valent neptunium(IV/V) compound has been synthesized by evaporation of a neptunium(V) acidic solution. The structure of the compound features cation-cation-bound six-membered neptunyl(V) rings. These rings are further connected by Np(IV) ions through cation-cation interactions (CCIs) into a three-dimensional neptunium cationic open framework. This example illustrates the possibility of isolating neptunyl(V) CCI oligomers in inorganic systems using other cations to compete with Np(V) in bonding with the neptunyl oxygen. PMID:24187926

  19. Cation-cation interactions, magnetic communication and reactivity of the pentavalent uraniumion [U(NR)2]+

    SciTech Connect

    Spencer, Liam P; Schelter, Eric J; Boncella, James M; Yang, Ping; Gsula, Robyn L; Scott, Brian L; Thompson, Joe D; Kiplinger, Jacqueline L; Batista, Enrique R

    2009-01-01

    The dimeric bis(imido) uranium complex [{l_brace}U(NtBu)2(I)(tBu2bpy){r_brace}2] (see picture; U green, N blue, I red) has cation-cation interactions between [U(NR)2]+ ions. This f1-f1 system also displays f orbital communication between uranium(V) centers at low temperatures, and can be oxidized to generate uranium(VI) bis(imido) complexes.

  20. Easily accessible polymer additives for tuning the crystal-growth of perovskite thin-films for highly efficient solar cells

    NASA Astrophysics Data System (ADS)

    Dong, Qingqing; Wang, Zhaowei; Zhang, Kaicheng; Yu, Hao; Huang, Peng; Liu, Xiaodong; Zhou, Yi; Chen, Ning; Song, Bo

    2016-03-01

    For perovskite solar cells (Pero-SCs), one of the key issues with respect to the power conversion efficiency (PCE) is the morphology control of the perovskite thin-films. In this study, an easily-accessible additive polyethylenimine (PEI) is utilized to tune the morphology of CH3NH3PbI3-xClx. With addition of 1.00 wt% of PEI, the smoothness and crystallinity of the perovskite were greatly improved, which were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A summit PCE of 14.07% was achieved for the p-i-n type Pero-SC, indicating a 26% increase compared to those of the devices without the additive. Both photoluminescence (PL) and alternating current impedance spectroscopy (ACIS) analyses confirm the efficiency results after the addition of PEI. This study provides a low-cost polymer additive candidate for tuning the morphology of perovskite thin-films, and might be a new clue for the mass production of Pero-SCs.For perovskite solar cells (Pero-SCs), one of the key issues with respect to the power conversion efficiency (PCE) is the morphology control of the perovskite thin-films. In this study, an easily-accessible additive polyethylenimine (PEI) is utilized to tune the morphology of CH3NH3PbI3-xClx. With addition of 1.00 wt% of PEI, the smoothness and crystallinity of the perovskite were greatly improved, which were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A summit PCE of 14.07% was achieved for the p-i-n type Pero-SC, indicating a 26% increase compared to those of the devices without the additive. Both photoluminescence (PL) and alternating current impedance spectroscopy (ACIS) analyses confirm the efficiency results after the addition of PEI. This study provides a low-cost polymer additive candidate for tuning the morphology of perovskite thin-films, and might be a new clue for the mass production of Pero-SCs. Electronic supplementary information (ESI) available: J-V curves & characteristics

  1. Transcutaneous approach for the removal of parotid gland stones.

    PubMed

    Oh, Hee-Kyun; Park, Hong-Ju; Oh, Je-Seok; Jung, Seunggon; Kook, Min-Suk

    2014-11-01

    Salivary stones in the parotid gland can be treated with a wide range of methods. Stones close to the opening of the duct can be easily removed through the oral cavity, whereas the entire salivary gland may need to be removed if stones are located close to the parotid gland. In such cases, surgical removal of the parotid gland may be lengthy and may produce facial nerve injury. We report a simple extraoral approach used for the removal of parotid gland stones located close to the parotid gland by precisely identifying the location of stones in 2 patients with parotid sialolithiasis. PMID:25318444

  2. Development of a simple chromatographic method for distinguishing between two easily confused species, Hedyotis diffusa and Hedyotis corymbosa.

    PubMed

    Lau, Clara B S; Cheng, Ling; Cheng, Bobby W H; Yue, Grace G L; Wong, Eric C W; Lau, Ching-Po; Leung, Ping-Chung; Fung, Kwok-Pui

    2012-01-01

    Hedyotis diffusa Willd. and Hedyotis corymbosa (L.) Lam. are closely related species of Rubiaceae family and they can be easily confused. Although previous reports have been found in which ultraviolet spectrum, convolution spectrometry or X-ray diffraction are reported to be used for distinguishing between the two species, these methods require specialised equipment. Hence, this study aims to develop a simple chromatographic method for the purpose. Our results illustrate the use of a thin-layer chromatographic (TLC) profile to differentiate between the two species, with a blue zone appearing at around an R(f) of 0.36 in H. corymbosa but not in H. diffusa. The compound corresponding to this blue zone was later found to be hedyotiscone A. LC-MS with multiple reaction monitoring was used as a tool to identify and quantify hedyotiscone A in the test samples. In conclusion, a quick and simple TLC assay was conducted to distinguish between the two species H. diffusa and H. corymbosa. PMID:21988612

  3. Easily Modified Factors Contribute to Delays in Diagnosis of Clostridium difficile Infection: a Cohort Study and Intervention

    PubMed Central

    Kundrapu, Sirisha; Jury, Lucy A.; Sitzlar, Brett; Sunkesula, Venkata C. K.; Sethi, Ajay K.

    2013-01-01

    Although rapid laboratory tests are available for diagnosis of Clostridium difficile infection (CDI), delays in completion of CDI testing are common in clinical practice. We conducted a cohort study of 242 inpatients tested for CDI to determine the timing of different steps involved in diagnostic testing and to identify modifiable factors contributing to delays in diagnosis. The average time from test order to test result was 1.8 days (range, 0.2 to 10.6), with time from order to stool collection accounting for most of the delay (mean, 1.0 day; range, 0 to 10). Several modifiable factors contributed to delays, including not providing stool collection supplies to patients in a timely fashion, rejection of specimens due to incorrect labeling or leaking from the container, and holding samples in the laboratory for batch processing. Delays in testing contributed to delays in initiation of treatment for patients diagnosed with CDI and to frequent prescription of empirical CDI therapy for patients with mild to moderate symptoms whose testing was ultimately negative. An intervention that addressed several easily modified factors contributing to delays resulted in a significant decrease in the time required to complete CDI testing. These findings suggest that health care facilities may benefit from a review of their processes for CDI testing to identify and address modifiable factors that contribute to delays in diagnosis and treatment of CDI. PMID:23678072

  4. Changing Preservice Science Teachers' Views of Nature of Science: Why Some Conceptions May be More Easily Altered than Others

    NASA Astrophysics Data System (ADS)

    Mesci, Gunkut; Schwartz, Renee'S.

    2016-02-01

    The purpose of this study was to assess preservice teachers' views of Nature of Science (NOS), identify aspects that were challenging for conceptual change, and explore reasons why. This study particularly focused on why and how some concepts of NOS may be more easily altered than others. Fourteen preservice science teachers enrolled in a NOS and Science Inquiry course participated in this study. Data were collected by using a pre/post format with the Views of Nature of Science questionnaire (VNOS-270), the Views of Scientific Inquiry questionnaire (VOSI-270), follow-up interviews, and classroom artifacts. The results indicated that most students initially held naïve views about certain aspects of NOS like tentativeness and subjectivity. By the end of the semester, almost all students dramatically improved their understanding about almost all aspects of NOS. However, several students still struggled with certain aspects like the differences between scientific theory and law, tentativeness, and socio-cultural embeddedness. Results suggested that instructional, motivational, and socio-cultural factors may influence if and how students changed their views about targeted NOS aspects. Students thought that classroom activities, discussions, and readings were most helpful to improve their views about NOS. The findings from the research have the potential to translate as practical advice for teachers, science educators, and future researchers.

  5. (11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals.

    PubMed

    Rotstein, Benjamin H; Liang, Steven H; Placzek, Michael S; Hooker, Jacob M; Gee, Antony D; Dollé, Frédéric; Wilson, Alan A; Vasdev, Neil

    2016-08-22

    The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry. PMID:27276357

  6. Efficient degradation of carbamazepine by easily recyclable microscaled CuFeO2 mediated heterogeneous activation of peroxymonosulfate.

    PubMed

    Ding, Yaobin; Tang, Hebin; Zhang, Shenghua; Wang, Songbo; Tang, Heqing

    2016-11-01

    Microscaled CuFeO2 particles (micro-CuFeO2) were rapidly prepared via a microwave-assisted hydrothermal method and characterized by scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. It was found that the micro-CuFeO2 was of pure phase and a rhombohedral structure with size in the range of 2.8±0.6μm. The micro-CuFeO2 efficiently catalyzed the activation of peroxymonosulfate (PMS) to generate sulfate radicals (SO4-), causing the fast degradation of carbamazepine (CBZ). The catalytic activity of micro-CuFeO2 was observed to be 6.9 and 25.3 times that of micro-Cu2O and micro-Fe2O3, respectively. The enhanced activity of micro-CuFeO2 for the activation of PMS was confirmed to be attributed to synergistic effect of surface bonded Cu(I) and Fe(III). Sulfate radical was the primary radical species responsible for the CBZ degradation. As a microscaled catalyst, micro-CuFeO2 can be easily recovered by gravity settlement and exhibited improved catalytic stability compared with micro-Cu2O during five successive degradation cycles. Oxidative degradation of CBZ by the couple of PMS/CuFeO2 was effective in the studied actual aqueous environmental systems. PMID:27329789

  7. Formation of Stable Cationic Lipid/DNA Complexes for Gene Transfer

    NASA Astrophysics Data System (ADS)

    Hofland, Hans E. J.; Shephard, Lee; Sullivan, Sean M.

    1996-07-01

    Stable cationic lipid/DNA complexes were formed by solubilizing cationic liposomes with 1% octylglucoside and complexing a DNA plasmid with the lipid in the presence of detergent. Removal of the detergent by dialysis yielded a lipid/DNA suspension that was able to transfect tissue culture cells up to 90 days after formation with no loss in activity. Similar levels of gene transfer were obtained by mixing the cationic lipid in a liposome form with DNA just prior to cell addition. However, expression was completely lost 24 hr after mixing. The transfection efficiency of the stable complex in 15% fetal calf serum was 30% of that obtained in the absence of serum, whereas the transient complex was completely inactivated with 2% fetal calf serum. A 90-day stability study comparing various storage conditions showed that the stable complex could be stored frozen or as a suspension at 4 degrees C with no loss in transfection efficiency. Centrifugation of the stable complex produced a pellet that contained approximately 90% of the DNA and 10% of the lipid. Transfection of cells with the resuspended pellet and the supernatant showed that the majority of the transfection activity was in the pellet and all the toxicity was in the supernatant. Formation of a stable cationic lipid/DNA complex has produced a transfection vehicle that can be stored indefinitely, can be concentrated with no loss in transfection efficiency, and the toxicity levels can be greatly reduced when the active complex is isolated from the uncomplexed lipid.

  8. Monovalent cation transport in irreversibly sickled cells.

    PubMed Central

    Clark, M R; Morrison, C E; Shohet, S B

    1978-01-01

    Using discontinuous density gradients of Stractan II, we have separated sickle cell blood into discrete subpopulations of reticulocytes, mature discoid cells, and irreversibly sickled cells (ISCs). We have measured active and passive fluxes of monovalent cations in mature discoid cells, ISCs, and normal control cells, also separated upon density gradients. These measurements revealed a decreased active cation transport in ISC-rich populations. However, parallel measurements of Na, K-ATPase activity showed normal ouabain-sensitive ATPase activity in ISCs. Passive permeability to external Rb was also normal in ISCs. The observation of depressed pump activity in intact ISCs, contrasted with normal ATPase activity in ISC membranes, suggests the presence of factors in the intact cell which inhibit the active transport of Na and K in ISCs. PMID:149799

  9. Structurally Distinct Cation Channelrhodopsins from Cryptophyte Algae.

    PubMed

    Govorunova, Elena G; Sineshchekov, Oleg A; Spudich, John L

    2016-06-01

    Microbial rhodopsins are remarkable for the diversity of their functional mechanisms based on the same protein scaffold. A class of rhodopsins from cryptophyte algae show close sequence homology with haloarchaeal rhodopsin proton pumps rather than with previously known channelrhodopsins from chlorophyte (green) algae. In particular, both aspartate residues that occupy the positions of the chromophore Schiff base proton acceptor and donor, a hallmark of rhodopsin proton pumps, are conserved in these cryptophyte proteins. We expressed the corresponding polynucleotides in human embryonic kidney (HEK293) cells and studied electrogenic properties of the encoded proteins with whole-cell patch-clamp recording. Despite their lack of residues characteristic of the chlorophyte cation channels, these proteins are cation-conducting channelrhodopsins that carry out light-gated passive transport of Na(+) and H(+). These findings show that channel function in rhodopsins has evolved via multiple routes. PMID:27233115

  10. Cation specific binding with protein surface charges.

    PubMed

    Hess, Berk; van der Vegt, Nico F A

    2009-08-11

    Biological organization depends on a sensitive balance of noncovalent interactions, in particular also those involving interactions between ions. Ion-pairing is qualitatively described by the law of "matching water affinities." This law predicts that cations and anions (with equal valence) form stable contact ion pairs if their sizes match. We show that this simple physical model fails to describe the interaction of cations with (molecular) anions of weak carboxylic acids, which are present on the surfaces of many intra- and extracellular proteins. We performed molecular simulations with quantitatively accurate models and observed that the order K(+) < Na(+) < Li(+) of increasing binding affinity with carboxylate ions is caused by a stronger preference for forming weak solvent-shared ion pairs. The relative insignificance of contact pair interactions with protein surfaces indicates that thermodynamic stability and interactions between proteins in alkali salt solutions is governed by interactions mediated through hydration water molecules. PMID:19666545

  11. Electronic spectrum of 9-methylanthracenium radical cation

    NASA Astrophysics Data System (ADS)

    O'Connor, Gerard D.; Sanelli, Julian A.; Dryza, Vik; Bieske, Evan J.; Schmidt, Timothy W.

    2016-04-01

    The predissociation spectrum of the cold, argon-tagged, 9-methylanthracenium radical cation is reported from 8000 cm-1 to 44 500 cm-1. The reported spectrum contains bands corresponding to at least eight electronic transitions ranging from the near infrared to the ultraviolet. These electronic transitions are assigned through comparison with ab initio energies and intensities. The infrared D1←D0 transitions exhibit significant vibronic activity, which is assigned through comparison with TD-B3LYP excited state frequencies and intensities, as well as modelled vibronic interactions. Dissociation of 9-methylanthracenium is also observed at high visible-photon energies, resulting in the loss of either CH2 or CH3. The relevance of these spectra, and the spectra of other polycyclic aromatic hydrocarbon radical cations, to the largely unassigned diffuse interstellar bands, is discussed.

  12. [PAH Cations as Viable Carriers of DIBs

    NASA Technical Reports Server (NTRS)

    Snow, Ted

    1998-01-01

    This report is intended to fill in the blanks in NASA's file system for our lab astro study of molecular ions of astrophysical interest. In order to give NASA what it needs for its files, I attach below the text of the section from our recent proposal to continue this work, in which we describe progress to date, including a large number of publications. Our initial studies were focused on PAH cations, which appear to be viable candidates as the carriers of the DIBs, an idea that has been supported by laboratory spectroscopy of PAH cations in inert matrices. Beginning with the simplest aromatic (benzene; C6H6) and moving progressively to larger species (naphthalene, C10OH8; pyrene, C16H10; and most recently chrysene, C18H12), we have been able to derive rate coefficients for reactions with neutral spices that are abundant in the diffuse interstellar medium.

  13. Ultrafast dynamics of water in cationic micelles

    NASA Astrophysics Data System (ADS)

    Dokter, Adriaan M.; Woutersen, Sander; Bakker, Huib J.

    2007-03-01

    The effect of confinement on the dynamical properties of liquid water is investigated for water enclosed in cationic reverse micelles. The authors performed mid-infrared ultrafast pump-probe spectroscopy on the OH-stretch vibration of isotopically diluted HDO in D2O in cetyltrimethylammonium bromide (CTAB) reverse micelles of various sizes. The authors observe that the surfactant counterions are inhomogeneously distributed throughout the reverse micelle, and that regions of extreme salinity occur near the interfacial Stern layer. The authors find that the water molecules in the core of the micelles show similar orientational dynamics as bulk water, and that water molecules in the counterion-rich interfacial region are much less mobile. An explicit comparison is made with the dynamics of water confined in anionic sodium bis(2-ethythexyl) sulfosuccinate (AOT) reverse micelles. The authors find that interfacial water in cationic CTAB reverse micelles has a higher orientational mobility than water in anionic AOT reverse micelles.

  14. Plant NHX cation/proton antiporters

    PubMed Central

    Rodríguez-Rosales, M Pilar; Gálvez, Francisco J; Huertas, Raúl; Aranda, M Nieves; Baghour, Mourad; Cagnac, Olivier

    2009-01-01

    Although physiological and biochemical data since long suggested that Na+/H+ and K+/H+ antiporters are involved in intracellular ion and pH regulation in plants, it has taken a long time to identify genes encoding antiporters that could fulfil these roles. Genome sequencing projects have now shown that plants contain a very large number of putative Cation/Proton antiporters, the function of which is only beginning to be studied. The intracellular NHX transporters constitute the first Cation/Proton exchanger family studied in plants. The founding member, AtNHX1, was identified as an important salt tolerance determinant and suggested to catalyze Na+ accumulation in vacuoles. It is, however, becoming increasingly clear, that this gene and other members of the family also play crucial roles in pH regulation and K+ homeostasis, regulating processes from vesicle trafficking and cell expansion to plant development. PMID:19794841

  15. C-1s NEXAFS spectroscopy reveals chemical fractionation of humic acid by cation-induced coagulation

    SciTech Connect

    Christl,I.; Kretzschmar, R.

    2007-01-01

    The influence of cation-induced coagulation on the chemical composition of dissolved and coagulated fractions of humic acid was investigated in batch coagulation experiments for additions of aluminum at pH 4 and 5, iron at pH 4, and calcium and lead at pH 6. The partitioning of organic carbon and metals was determined by analyzing total organic carbon and total metal contents of the dissolved phase. Both the dissolved and the coagulated humic acid fractions were characterized using synchrotron scanning transmission X-ray microscopy (STXM) and C-1s near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Intensities of {pi}* transitions of carboxyl carbon and {sigma}* transitions of alkyl, O-alkyl, and carboxyl carbon decreased with increasing metal concentration for the dissolved humic acid fractions. This decrease was accompanied by an increase of the respective intensities in the coagulated fraction as shown for lead. Intensities of aromatic and phenolic carbon were affected to a larger extent only by aluminum and iron additions. The changes observed in the C-1s NEXAFS spectra coincided with an increasing removal of organic carbon from the dissolved phase with increasing total metal concentrations. We conclude that humic acid was chemically fractionated by cation-induced coagulation, which preferentially removed functional groups involved in metal-cation binding from solution.

  16. Preparation and Characterization of Cotton Textile Graft Copolymers as Cation Exchanger

    NASA Astrophysics Data System (ADS)

    Mostafa, Kh. M.

    2005-03-01

    Acrylic Acid (AA) was graft copolymerized with cotton cellulose in fabric form to prepare poly (AA)-cotton graft copolymer cation exchanger using Fe2+/BrO3- redox system in aqueous medium under a nitrogen atmosphere. The effect of Fe2+, BrO3- and monomer concentrations, pH as well as time and temperature of polymerization were studied by determining the grafting parameters gravimetrically, like Graft Yield (GY %) and Graft Reaction Efficiency (GRE %). On the other hand, the newly prepared poly (AA)-cotton graft copolymers were characterized for different heavy metals ions removal to determined their suitability as cation exchanger. On the basis of a detailed investigation of the above factors, the appropriate conditions for grafting were as follows: Fe2+, 0.005 mol L-1; BrO3-, 0.001 mol L-1; pH, 2; monomer, (50% based on weight of substrate); time, 90 min and temperature, 35°C. On the other hand, the potential value of the newly prepared poly (AA)-cotton graft copolymer to serve as cation exchanger was assessed through measurements of critical properties such as removal of different heavy metal ions from their solutions as well as durability.

  17. Alkaline earth cation extraction from acid solution

    DOEpatents

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  18. Novel penetrating cations for targeting mitochondria.

    PubMed

    Chernyak, Boris V; Antonenko, Yuri N; Domnina, Lidia V; Ivanova, Olga Yu; Lyamzaev, Konstantin G; Pustovidko, Antonina V; Rokitskaya, Tatiana I; Severina, Inna I; Simonyan, Ruben A; Trendeleva, Tatiana A; Zvyagilskaya, Renata A

    2013-01-01

    Novel penetrating cations were used for the design of mitochondria-targeted compounds and tested in model lipid membranes, in isolated mitochondria and in living human cells in culture. Rhodamine-19, berberine and palmatine were conjugated by aliphatic linkers with plastoquinone possessing antioxidant activity. These conjugates (SkQR1,SkQBerb, SkQPalm) and their analogs lacking plastoquinol moiety (C12R1,C10Berb and C10Palm) penetrated bilayer phospholipid membrane in their cationic forms and accumulated in isolated mitochondria or in mitochondria of living cells due to membrane potential negative inside. Reduced forms of SkQR1, SkQBerb and SkQPalm inhibited lipid peroxidation in isolated mitochondria at nanomolar concentrations. In human fibroblasts SkQR1, SkQBerb and SkQPalm prevented fragmentation of mitochondria and apoptosis induced by hydrogen peroxide. SkQR1 was effective at subnanomolar concentrations while SkQberb, SkQPalm and SkQ1 (prototypic conjugate of plastoquinone with dodecyltriphenylphosphonium) were effective at 10-times higher concentrations. The aliphatic conjugates of berberine and palmatine (as well as the conjugates of triphenylphosphonium) induced proton transport mediated by free fatty acids (FA) both in the model and mitochondrial membrane. In mitochondria this process was facilitated by the adenine nucleotide carrier. In contrast to the other cationic conjugates, SkQR1 and C12R1 induced FA-independent proton conductivity due to protonation/deprotonation of the rhodamine residue. This property in combination with the antioxidant activity probably makes rhodamine conjugates highly effective in protection against oxidative stress. The novel cationic conjugates described here are promising candidates for drugs against various pathologies and aging as mitochondria-targeted antioxidants and selective mild uncouplers. PMID:23092317

  19. Regulation of Cation Balance in Saccharomyces cerevisiae

    PubMed Central

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  20. Sn Cation Valency Dependence in Cation Exchange Reactions Involving Cu2-xSe Nanocrystals

    PubMed Central

    2014-01-01

    We studied cation exchange reactions in colloidal Cu2-xSe nanocrystals (NCs) involving the replacement of Cu+ cations with either Sn2+ or Sn4+ cations. This is a model system in several aspects: first, the +2 and +4 oxidation states for tin are relatively stable; in addition, the phase of the Cu2-xSe NCs remains cubic regardless of the degree of copper deficiency (that is, “x”) in the NC lattice. Also, Sn4+ ions are comparable in size to the Cu+ ions, while Sn2+ ones are much larger. We show here that the valency of the entering Sn ions dictates the structure and composition not only of the final products but also of the intermediate steps of the exchange. When Sn4+ cations are used, alloyed Cu2–4ySnySe NCs (with y ≤ 0.33) are formed as intermediates, with almost no distortion of the anion framework, apart from a small contraction. In this exchange reaction the final stoichiometry of the NCs cannot go beyond Cu0.66Sn0.33Se (that is Cu2SnSe3), as any further replacement of Cu+ cations with Sn4+ cations would require a drastic reorganization of the anion framework, which is not possible at the reaction conditions of the experiments. When instead Sn2+ cations are employed, SnSe NCs are formed, mostly in the orthorhombic phase, with significant, albeit not drastic, distortion of the anion framework. Intermediate steps in this exchange reaction are represented by Janus-type Cu2-xSe/SnSe heterostructures, with no Cu–Sn–Se alloys. PMID:25340627

  1. Low cation coordination in oxide melts

    SciTech Connect

    Skinner, Lawrie; Benmore, Chris J; Du, Jincheng; Weber, Richard; Neuefeind, Joerg C; Tumber, Sonia; Parise, John B

    2014-01-01

    The complete set of Faber-Ziman partial pair distribution functions for a rare earth oxide liquid were measured for the first time by combining aerodynamic levitation, neutron diffraction, high energy x-ray diffraction and isomorphic substitution using Y2 O3 and Ho2 O3 melts. The average Y- O coordination is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2 O3 (or Ho2 O3 ). Investigation of high temperature La2 O3 , ZrO2 , SiO2 , and Al2 O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation- oxygen coordination. These measurements suggest a general trend towards lower M-O coordination compared to their crystalline counterparts. It is found that this coordination number drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  2. Reducible cationic lipids for gene transfer.

    PubMed Central

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  3. Study of the fluoro- and chlorodimethylbutyl cations

    PubMed Central

    Olah, George A.; Prakash, G. K. Surya; Rasul, Golam

    2013-01-01

    A comparative study of the 2,3-dimethyl-3-fluoro-2-butyl cation and its chloro analog was carried out by the ab initio/GIAO-CCSD(T) (gauge invariant atomic orbital-coupled cluster with single, double, and perturbative triple excitation) method. The structures and 13C NMR chemical shifts of the cations were calculated at the GIAO-CCSD(T)/tzp/dz//MP2/cc-pVTZ level. Bridged fluoronium ion 1, carbenium ion 2, and fluorocarbenium ion 3 were found to be minima on the potential energy surface. Bridged fluoronium ion 1, although a minimum on the potential energy surface, is 12.8 kcal/mol less stable than the open chain fluorobutyl cation 3. In contrast to the fluorinated ion, bridged chloronium ion 5 was found to be the lowest energy minimum being 10.6 kcal/mol more stable than ion 6 and 7.4 kcal/mol more stable than ion 7. PMID:23650369

  4. Method of preparation of removable syntactic foam

    DOEpatents

    Arnold, Jr., Charles; Derzon, Dora K.; Nelson, Jill S.; Rand, Peter B.

    1995-01-01

    Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications.

  5. Method of preparation of removable syntactic foam

    DOEpatents

    Arnold, C. Jr.; Derzon, D.K.; Nelson, J.S.; Rand, P.B.

    1995-07-11

    Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications. 1 fig.

  6. Optimizing the application of magnetic nanoparticles in Cr(VI) removal

    NASA Astrophysics Data System (ADS)

    Simeonidis, Konstantinos; Kaprara, Efthymia; Mitrakas, Manassis; Tziomaki, Magdalini; Angelakeris, Mavroidis; Vourlias, Georgios; Andritsos, Nikolaos

    2013-04-01

    The presence of heavy metals in aqueous systems is an intense health and environmental problem as implied by their harmful effects on human and other life forms. Among them, chromium is considered as an acutely hazardous compound contaminating the surface water from industrial wastes or entering the groundwater, the major source of drinking water, by leaching of chromite rocks. Chromium occurs in two stable oxidation states, Cr(III) and Cr(VI), with the hexavalent form being much more soluble and mobile in water having the ability to enter easily into living tissues or cells and thus become more toxic. Despite the established risks from Cr(VI)-containing water consumption and the increasing number of incidents, the E.U. tolerance limit for total chromium in potable water still stands at 50 μg/L. However, in the last years a worldwide debate concerning the establishment of a separate and very strict limit for the hexavalent form takes place. In practice, Cr(VI) is usually removed from water by various methods such as chemical coagulation/filtration, ion exchange, reverse osmosis and adsorption. Adsorption is considered as the simplest method which may become very effective if the process is facilitated by the incorporation of a Cr(VI) to Cr(III) reduction stage. This work studies the potential of using magnetic nanoparticles as adsorbing agents for Cr(VI) removal at the concentration levels met in contaminated drinking water. A variety of nanoparticles consisting of ferrites MFe2O4 (M=Fe, Co, Ni, Cu, Mn, Mg, Zn) were prepared by precipitating the corresponding bivalent or trivalent sulfate salts under controlled acidity and temperature. Electron microscopy and X-ray diffraction techniques were used to verify their crystal structure and determine the morphological characteristics. The mean particle size of the samples was found in the range 10-50 nm. Batch Cr(VI) removal tests were performed in aqueous nanoparticles dispersions showing the efficiency of ferrite

  7. Input of easily available organic C and N stimulates microbial decomposition of soil organic matter in arctic permafrost soil

    PubMed Central

    Wild, Birgit; Schnecker, Jörg; Alves, Ricardo J. Eloy; Barsukov, Pavel; Bárta, Jiří; Čapek, Petr; Gentsch, Norman; Gittel, Antje; Guggenberger, Georg; Lashchinskiy, Nikolay; Mikutta, Robert; Rusalimova, Olga; Šantrůčková, Hana; Shibistova, Olga; Urich, Tim; Watzka, Margarete; Zrazhevskaya, Galina; Richter, Andreas

    2014-01-01

    Rising temperatures in the Arctic can affect soil organic matter (SOM) decomposition directly and indirectly, by increasing plant primary production and thus the allocation of plant-derived organic compounds into the soil. Such compounds, for example root exudates or decaying fine roots, are easily available for microorganisms, and can alter the decomposition of older SOM (“priming effect”). We here report on a SOM priming experiment in the active layer of a permafrost soil from the central Siberian Arctic, comparing responses of organic topsoil, mineral subsoil, and cryoturbated subsoil material (i.e., poorly decomposed topsoil material subducted into the subsoil by freeze–thaw processes) to additions of 13C-labeled glucose, cellulose, a mixture of amino acids, and protein (added at levels corresponding to approximately 1% of soil organic carbon). SOM decomposition in the topsoil was barely affected by higher availability of organic compounds, whereas SOM decomposition in both subsoil horizons responded strongly. In the mineral subsoil, SOM decomposition increased by a factor of two to three after any substrate addition (glucose, cellulose, amino acids, protein), suggesting that the microbial decomposer community was limited in energy to break down more complex components of SOM. In the cryoturbated horizon, SOM decomposition increased by a factor of two after addition of amino acids or protein, but was not significantly affected by glucose or cellulose, indicating nitrogen rather than energy limitation. Since the stimulation of SOM decomposition in cryoturbated material was not connected to microbial growth or to a change in microbial community composition, the additional nitrogen was likely invested in the production of extracellular enzymes required for SOM decomposition. Our findings provide a first mechanistic understanding of priming in permafrost soils and suggest that an increase in the availability of organic carbon or nitrogen, e.g., by increased

  8. Cation uptake and allocation by red pine seedlings under cation-nutrient stress in a column growth experiment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and aims: Plant nutrient uptake is affected by environmental stress, but how plants respond to cation nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient stress on cation uptake in an experimental plant-mineral system. Methods: Column experim...

  9. ARSENIC REMOVAL BY IRON REMOVAL PROCESSES

    EPA Science Inventory

    Presentation will discuss the removal of arsenic from drinking water using iron removal processes that include oxidation/filtration and the manganese greensand processes. Presentation includes results of U.S. EPA field studies conducted in Michigan and Ohio on existing iron remo...

  10. Method of making thermally removable polyurethanes

    DOEpatents

    Loy, Douglas A.; Wheeler, David R.; McElhanon, James R.; Saunders, Randall S.; Durbin-Voss, Marvie Lou

    2002-01-01

    A method of making a thermally-removable polyurethane material by heating a mixture of a maleimide compound and a furan compound, and introducing alcohol and isocyanate functional groups, where the alcohol group and the isocyanate group reacts to form the urethane linkages and the furan compound and the maleimide compound react to form the thermally weak Diels-Alder adducts that are incorporated into the backbone of the urethane linkages during the formation of the polyurethane material at temperatures from above room temperature to less than approximately 90.degree. C. The polyurethane material can be easily removed within approximately an hour by heating to temperatures greater than approximately 90.degree. C. in a polar solvent. The polyurethane material can be used in protecting electronic components that may require subsequent removal of the solid material for component repair, modification or quality control.

  11. Comparative analysis of cation/proton antiporter superfamily in plants

    SciTech Connect

    Ye, Chuyu; Yang, Xiaohan; Xia, Xinli; Yin, Weilun

    2013-01-01

    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant specieswas reported.We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240members are separated into three families, i.e., Na+/H+ exchangers, K+ efflux antiporters, and cation/H+ exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H+ exchangers in the examined angiospermspecies. Sliding windowanalysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and foundmostmotifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants.

  12. An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

    PubMed Central

    Marano, Grazia; Gronewold, Claas; Frank, Martin; Merling, Anette; Kliem, Christian; Sauer, Sandra; Wiessler, Manfred; Frei, Eva

    2012-01-01

    Summary Oligosaccharides aberrantly expressed on tumor cells influence processes such as cell adhesion and modulation of the cell’s microenvironment resulting in an increased malignancy. Schmidt’s imidate strategy offers an effective method to synthesize libraries of various oligosaccharide mimetics. With the aim to perturb interactions of tumor cells with extracellular matrix proteins and host cells, molecules with 3,4-bis(hydroxymethyl)furan as core structure were synthesized and screened in biological assays for their abilities to interfere in cell adhesion and other steps of the metastatic cascade, such as tumor-induced angiogenesis. The most active compound, (4-{[(β-D-galactopyranosyl)oxy]methyl}furan-3-yl)methyl hydrogen sulfate (GSF), inhibited the activation of matrix-metalloproteinase-2 (MMP-2) as well as migration of the human melanoma cells of the lines WM-115 and WM-266-4 in a two-dimensional migration assay. GSF inhibited completely the adhesion of WM-115 cells to the extracellular matrix (ECM) proteins, fibrinogen and fibronectin. In an in vitro angiogenesis assay with human endothelial cells, GSF very effectively inhibited endothelial tubule formation and sprouting of blood vessels, as well as the adhesion of endothelial cells to ECM proteins. GSF was not cytotoxic at biologically active concentrations; neither were 3,4-bis{[(β-D-galactopyranosyl)oxy]methyl}furan (BGF) nor methyl β-D-galactopyranoside nor 3,4-bis(hydroxymethyl)furan, which were used as controls, eliciting comparable biological activity. In silico modeling experiments, in which binding of GSF to the extracellular domain of the integrin αvβ3 was determined, revealed specific docking of GSF to the same binding site as the natural peptidic ligands of this integrin. The sulfate in the molecule coordinated with one manganese ion in the binding site. These studies show that this chemically easily accessible molecule GSF, synthesized in three steps from 3,4-bis

  13. Radiolytic generation of radical cations in xenon matrices. Tetramethylcyclopropane radical cation and its transformations

    SciTech Connect

    Qin, X.Z.; Trifunac, A.D. )

    1990-04-05

    Radiolytic generation of radical cations in xenon matrices containing electron scavengers is illustrated by studying the 1,1,2,2-tetramethylcyclopropane radical cation. Dilute and concentrated solutions of tetramethylcyclopropane in xenon without electron scavengers and neat tetramethylcyclopropane yielded neutral radicals upon {gamma}-irradiation. Speculation on the mechanisms of radical formation is presented. The radical species observed in the {gamma}-irradiation of neat tetramethylcyclopropane appears to be identical with the paramagnetic species observed in CF{sub 2}ClCFCl{sub 2} above 120 K, suggesting that a neutral radical rather than the ring-opened distonic radical cation is observed in the CF{sub 2}ClCFCl{sub 2} matrix.

  14. Cation–cation interactions and cation exchange in a series of isostructural framework uranyl tungstates

    SciTech Connect

    Balboni, Enrica; Burns, Peter C.

    2014-05-01

    The isotypical compounds (UO{sub 2}){sub 3}(WO{sub 6})(H{sub 2}O){sub 5} (1), Ag(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3} (2), K(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 4} (3), Rb(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3.5} (4), and Cs(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 3} (5) were synthesized, characterized, and their structures determined. Each crystallizes in space group Cc. (1): a=12.979 (3), b=10.238 (2), c=11.302 (2), β=102.044 (2); (2): a=13.148 (2), b=9.520 (1), c=11.083 (2), β=101.568 (2); (3): a=13.111 (8), b=9.930 (6), c=11.242 (7), β=101.024 (7); (4): a=12.940 (2), b=10.231 (2), c=11.259(2), β=102.205 (2); (5): a=12.983 (3), b=10.191 (3), c=11.263 (4), β=101.661 (4). Compounds 1–5 are a framework of uranyl and tungsten polyhedra containing cation–cation interactions. The framework has three symmetrically distinct U(VI) cations, one tungsten, sixteen to eighteen oxygen atoms, and in 2–5, one monovalent cation. Each atom occupies a general position. Each U(VI) cation is present as a typical (UO{sub 2}){sup 2+} uranyl ion in an overall pentagonal bipyramidal coordination environment. Each pentagonal bipyramid shares two equatorial edges with two other pentagonal bipyramids, forming a trimer. Trimers are connected into chains by edge-sharing with WO{sub 6} octahedra. Chains are linked through cation–cation interactions between two symmetrically independent uranyl ions. This yields a remarkably complex system of intersecting channels that extend along [0 0 1] and [−1 1 0]. The cation exchange properties of 2 and 3 were characterized at room temperature and at 140 °C. - Graphical abstract: Chains of uranium and tungsten polyhedra are connected into a three dimensional framework by cation–cation interactions occurring between two symmetrically independent uranyl pentagonal bipyramids. Monovalent cations present in channels within the structure can be exchanged by room temperature or mild hydrothermal

  15. Long-term tobacco plantation induces soil acidification and soil base cation loss.

    PubMed

    Zhang, Yuting; He, Xinhua; Liang, Hong; Zhao, Jian; Zhang, Yueqiang; Xu, Chen; Shi, Xiaojun

    2016-03-01

    Changes in soil exchangeable cations relative to soil acidification are less studied particularly under long-term cash crop plantation. This study investigated soil acidification in an Ali-Periudic Argosols after 10-year (2002-2012) long-term continuous tobacco plantation. Soils were respectively sampled at 1933 and 2143 sites in 2002 and 2012 (also 647 tobacco plants), from seven tobacco plantation counties in the Chongqing Municipal City, southwest China. After 10-year continuous tobacco plantation, a substantial acidification was evidenced by an average decrease of 0.20 soil pH unit with a substantial increase of soil sites toward the acidic status, especially those pH ranging from 4.5 to 5.5, whereas 1.93 kmol H(+) production ha(-1) year(-1) was mostly derived from nitrogen (N) fertilizer input and plant N uptake output. After 1 decade, an average decrease of 27.6 % total exchangeable base cations or of 0.20 pH unit occurred in all seven tobacco plantation counties. Meanwhile, for one unit pH decrease, 40.3 and 28.3 mmol base cations kg(-1) soil were consumed in 2002 and 2012, respectively. Furthermore, the aboveground tobacco biomass harvest removed 339.23 kg base cations ha(-1) year(-1) from soil, which was 7.57 times higher than the anions removal, leading to a 12.52 kmol H(+) production ha(-1) year(-1) as the main reason inducing soil acidification. Overall, our results showed that long-term tobacco plantation not only stimulated soil acidification but also decreased soil acid-buffering capacity, resulting in negative effects on sustainable soil uses. On the other hand, our results addressed the importance of a continuous monitoring of soil pH changes in tobacco plantation sites, which would enhance our understanding of soil fertility of health in this region. PMID:26566613

  16. Fast doping of Cu into ZnSe NCs by hydrazine promoted cation exchange in aqueous solution at room temperature.

    PubMed

    Shao, Haibao; Wang, Chunlei; Xu, Shuhong; Wang, Zhuyuan; Yin, Haihong; Cui, Yiping

    2015-03-01

    Controllable doping is an effective way of tuning the properties of semiconductor nanocrystals (NCs). In this work, a simple strategy of fast doping Cu ions into ZnSe NCs under ambient conditions was proposed. The principle of doping is based on hydrazine (N2H4) promoted cation exchange reaction. By direct addition of Cu ion stock solution into the preformed ZnSe NCs, Cu doped ZnSe NCs can be obtained. Furthermore, the emission of doped NCs can be tuned by changing the amount of impurity ion addition. The cation exchange reaction is facilitated by three factors: 1) N2H4 addition, 2) fast impurity ions, and 3) partial stabilizer removal. The proposed cation exchange reaction in aqueous solution could be an alternate route for NC doping as well as synthesis of ionic NCs. PMID:25605441

  17. Aspartate 74 as a primary determinant in acetylcholinesterase governing specificity to cationic organophosphonates.

    PubMed

    Hosea, N A; Radić, Z; Tsigelny, I; Berman, H A; Quinn, D M; Taylor, P

    1996-08-20

    Through site-specific mutagenesis, we examined the determinants on acetylcholinesterase which govern the specificity and reactivity of three classes of substrates: enantiomeric alkyl phosphonates, trifluoromethyl acetophenones, and carboxyl esters. By employing cationic and uncharged pairs of enantiomeric alkyl methylphosphonyl thioates of known absolute stereochemistry, we find that an aspartate residue near the gorge entrance (D74) is responsible for the enhanced reactivity of the cationic organophosphonates. Removal of the charge with the mutation D74N causes a near equal reduction in the reaction rate constants for the Rp and Sp enantiomers and exerts a greater influence on the cationic organophosphonates than on the charged trimethylammonio trifluoromethyl acetophenone and acetylthiocholine. This pattern of reactivity suggests that the orientation of the leaving group for both enantiomers is directed toward the gorge exit and in apposition to Asp 74. Replacement of tryptophan 86 with alanine in the choline subsite also diminishes the reaction rates for cationic organophosphonates, although to a lesser extent than with the D74N mutation, while not affecting the reactions with the uncharged compounds. Hence, reaction with cationic OPs depends to a lesser degree on Trp 86 than on Asp 74. Docking of Sp and Rp cycloheptyl methylphosphonyl thiocholines and thioethylates in AChE as models of the reversible complex and transition state using molecular dynamics affords structural insight into the spatial arrangement of the substituents surrounding phosphorus prior to and during reaction. The leaving group of the Rp and Sp enantiomers, regardless of charge, is directed to the gorge exit and toward Asp 74, an orientation unique to tetrahedral ligands. PMID:8718893

  18. Ultrafast dynamics of pyrrolidinium cation ionic liquids.

    PubMed

    Shirota, Hideaki; Funston, Alison M; Wishart, James F; Castner, Edward W

    2005-05-01

    We have investigated the ultrafast molecular dynamics of five pyrrolidinium cation room temperature ionic liquids using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids studied are N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P14+/NTf2-), N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P1EOE+/NTf2-), N-ethoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P1EOE+/NTf2-), N-ethoxyethyl-N-methylpyrrolidinium bromide P1EOE+, and N-ethoxyethyl-N-methylpyrrolidinium dicyanoamide P1EOE+/DCA-). For comparing dynamics among the five ionic liquids, we categorize the ionic liquids into two groups. One group of liquids comprises the three pyrrolidinium cations P14+, P1EOM+, and P1EOE+ paired with the NTf2- anion. The other group of liquids consists of the P1EOE+ cation paired with each of the three anions NTf2-, Br-, and DCA-. The overdamped relaxation for time scales longer than 2 ps has been fit by a triexponential function for each of the five pyrrolidinium ionic liquids. The fast ( approximately 2 ps) and intermediate (approximately 20 ps) relaxation time constants vary little among these five ionic liquids. However, the slow relaxation time constant correlates with the viscosity. Thus, the Kerr spectra in the range from 0 to 750 cm(-1) are quite similar for the group of three pyrrolidinium ionic liquids paired with the NTf2- anion. The intermolecular vibrational line shapes between 0 and 150 cm(-1) are fit to a multimode Brownian oscillator model; adequate fits required at least three modes to be included in the line shape. PMID:15918734

  19. Ultrafast dynamics of pyrrolidinium cation ionic liquids

    NASA Astrophysics Data System (ADS)

    Shirota, Hideaki; Funston, Alison M.; Wishart, James F.; Castner, Edward W.

    2005-05-01

    We have investigated the ultrafast molecular dynamics of five pyrrolidinium cation room temperature ionic liquids using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids studied are N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P14+/NTf2-), N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P1EOE+/NTf2-), N-ethoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P1EOE+/NTf2-), N-ethoxyethyl-N-methylpyrrolidinium bromideP1EOE+, and N-ethoxyethyl-N-methylpyrrolidinium dicyanoamide P1EOE+/DCA-). For comparing dynamics among the five ionic liquids, we categorize the ionic liquids into two groups. One group of liquids comprises the three pyrrolidinium cations P14+, P1EOM+, and P1EOE+ paired with the NTf2- anion. The other group of liquids consists of the P1EOE+ cation paired with each of the three anions NTf2-,Br-, and DCA-. The overdamped relaxation for time scales longer than 2 ps has been fit by a triexponential function for each of the five pyrrolidinium ionic liquids. The fast (˜2ps) and intermediate (˜20ps) relaxation time constants vary little among these five ionic liquids. However, the slow relaxation time constant correlates with the viscosity. Thus, the Kerr spectra in the range from 0 to 750cm-1 are quite similar for the group of three pyrrolidinium ionic liquids paired with the NTf2- anion. The intermolecular vibrational line shapes between 0 and 150cm-1 are fit to a multimode Brownian oscillator model; adequate fits required at least three modes to be included in the line shape.

  20. Phenol removal pretreatment process

    DOEpatents

    Hames, Bonnie R.

    2004-04-13

    A process for removing phenols from an aqueous solution is provided, which comprises the steps of contacting a mixture comprising the solution and a metal oxide, forming a phenol metal oxide complex, and removing the complex from the mixture.

  1. ORGANIC COATING REMOVAL

    EPA Science Inventory

    Cleaner coating removal technologies are developing rapidly to meet a variety of industrial needs to replace solvent strippers having toxic properties. his guide describes cleaner technologies that can be used to reduce waste in coating removal operations. nformation is presented...

  2. Wart remover poisoning

    MedlinePlus

    ... Remover Panscol Paplex Ultra PediaPatch Sal-Acid Sal-Plant Salacid Salactic Film Trans-Plantar Trans-Ver-Sal Vergo Verukan Viranol Wart Remover Other products may also contain salicylates and other acids.

  3. CNT loading into cationic cholesterol suspensions show improved DNA binding and serum stability and ability to internalize into cancer cells

    NASA Astrophysics Data System (ADS)

    Chhikara, Bhupender S.; Misra, Santosh K.; Bhattacharya, Santanu

    2012-02-01

    Methods which disperse single-walled carbon nanotubes (SWNTs) in water as ‘debundled’, while maintaining their unique physical properties are highly useful. We present here a family of cationic cholesterol compounds (Chol+) {Cholest-5en-3β-oxyethyl pyridinium bromide (Chol-PB+), Cholest-5en-3β-oxyethyl N-methyl pyrrolidinium bromide (Chol-MPB+), Cholest-5en-3β-oxyethyl N-methyl morpholinium bromide (Chol-MMB+) and Cholest-5en-3β-oxyethyl diazabicyclo octanium bromide (Chol-DOB+)}. Each of these could be easily dispersed in water. The resulting cationic cholesterol (Chol+) suspensions solubilized single-walled carbon nanotubes (SWCNTs) by the non-specific physical adsorption of Chol+ to form stable, transparent, dark aqueous suspensions at room temperature. Electron microscopy reveals the existence of highly segregated CNTs in these samples. Zeta potential measurements showed an increase in potential of cationic cholesterol aggregates on addition of CNTs. The CNT-Chol+ suspensions were capable of forming stable complexes with genes (DNA) efficiently. The release of double-helical DNA from such CNT-Chol+ complexes could be induced upon the addition of anionic micellar solution of SDS. Furthermore, the CNT-based DNA complexes containing cationic cholesterol aggregates showed higher stability in fetal bovine serum media at physiological conditions. Confocal studies confirm that CNT-Chol+ formulations adhere to HeLa cell surfaces and get internalized more efficiently than the cationic cholesterol suspensions alone (devoid of any CNTs). These cationic cholesterol-CNT suspensions therefore appear to be a promising system for further use in biological applications.

  4. Smartphones for post-event analysis: a low-cost and easily accessible approach for mapping natural hazards

    NASA Astrophysics Data System (ADS)

    Tarolli, Paolo; Prosdocimi, Massimo; Sofia, Giulia; Dalla Fontana, Giancarlo

    2015-04-01

    technology. Anyone (included farmers, technicians or who work at Civil Protection) who has a good smartphone can take photographs and, from these photographs, they can easily obtain high-resolution DSMs. Therefore, SfM technique accomplished with smartphones can be a very strategic tool for post-event field surveys, to increase the existing knowledge on such events, and to provide fast technical solutions for risk mitigation (e.g. landslide and flood risk management). The future challenge consists of using only a smartphone for local scale post-event analyses. This can be even enhanced by the development of specific apps that are able to build quickly a 3D view of the case study and arrange a preliminary quantitative analysis of the process involved, ready to be sent to Civil Protection for further elaborations. Tarolli, P. (2014). High-resolution topography for understanding Earth surface processes: opportunities and challenges. Geomorphology, 216, 295-312, doi:10.1016/j.geomorph.2014.03.008.

  5. Cationic bituminous emulsions and emulsion aggregate slurries

    SciTech Connect

    Schilling, P.

    1986-07-01

    A cationic bituminous emulsion is described which consists of from about 30% to about 80% by weight of bitumen, from about 0.1% to about 10% by weight of an emulsifier selected from the group consisting of reaction products of a polyamine reacted with a member of the group consisting of epoxidized unsaturated fatty acids of chain lengths between C/sub 8/ and C/sub 22/ and the esters thereof and adding water to make up 100% by weight, the emulsion having a pH in the range of from 2-7.

  6. Nonclassical 21-Homododecahedryl Cation Rearrangement Revisited.

    PubMed

    Jalife, Said; Mondal, Sukanta; Osorio, Edison; Cabellos, José Luis; Martínez-Guajardo, Gerardo; Fernández-Herrera, María A; Merino, Gabriel

    2016-03-01

    The degenerate rearrangement in the 21-homododecahedryl cation (1) has been studied via density functional theory computations and Born-Oppenheimer Molecular Dynamics simulations. Compound 1 can be described as a highly fluxional hyperconjugated carbocation. Complete scrambling of 1 can be achieved by the combination of two unveiled barrierless processes. The first one is a "rotation" of one of the six-membered rings via a 0.8 kcal·mol(-1) barrier, and the second one is a slower interconvertion between two hyperconjomers via an out-of-plane methine bending (ΔG(⧧) = 4.0 kcal·mol(-1)). PMID:26862680

  7. Mobility of cations in magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    Martinelli, J. R.; Sonder, E.; Weeks, R. A.; Zuhr, R. A.

    1986-04-01

    Transport of cations in magnesium aluminate spinel due to an applied electric field at approximately 1000 °C has been measured by observing changes in elemental concentrations near the cathode and anode surfaces using ion backscattering techniques. The results indicate that magnesium ions are the mobile species at 1000 °C and that these ions combine with ambient oxygen at the cathode surface to form a MgO layer. Quantitative interpretation of the data leads to the conclusion that the ionic transference number of spinel becomes approximately 0.5 after treatment in an electric field.

  8. Fragmentation Pathways in the Uracil Radical Cation

    SciTech Connect

    Zhou, Congyi; Matsika, Spiridoula; Kotur, Marija; Weinacht, Thomas C.

    2012-08-24

    We investigate pathways for fragmentation in the uracil radical cation using ab initio electronic structure calculations. We focus on the main fragments produced in pump–probe dissociative ionization experiments. These are fragments with mass to charge ratios (m/z) of 69, 28, 41, and 42. Barriers to dissociation along the ground ionic surface are reported, which provide an estimate of the energetic requirements for the production of the main fragments. Finally, direct and sequential fragmentation mechanisms have been analyzed, and it is concluded that sequential fragmentation after production of fragment with m/z 69 is the dominant mechanism for the production of the smaller fragments.

  9. Weakly supervised glasses removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhicheng; Zhou, Yisu; Wen, Lijie

    2015-03-01

    Glasses removal is an important task on face recognition, in this paper, we provide a weakly supervised method to remove eyeglasses from an input face image automatically. We choose sparse coding as face reconstruction method, and optical flow to find exact shape of glasses. We combine the two processes iteratively to remove glasses more accurately. The experimental results reveal that our method works much better than these algorithms alone, and it can remove various glasses to obtain natural looking glassless facial images.

  10. Synthesis and evaluation of a novel cationic konjac glucomannan-based flocculant.

    PubMed

    Ren, Wen-jing; Zhang, Ai-qing; Qin, Si-yong; Li, Zhen-ke

    2016-06-25

    A novel cationic flocculant of konjac glucomannan-graft-poly-(2-methacryloyloxyethyl)trimethyl ammonium chloride (KGM-g-PDMC), was successfully synthesized by using acidic ammonium cerium (IV) nitrate (CAN) as initiator in homogeneous aqueous solution. The graft copolymer was characterized using Fourier-transform infrared (FT-IR) spectroscopy, (1)H nuclear magnetic resonance ((1)H NMR), thermogravimetric analysis (TGA) and elemental analysis. The influences of degree of substitution (DS) of KGM, concentration of NaCl and pH value on turbidity removal rate of the cationic flocculant were investigated. The results demonstrated that the flocculant exhibited excellent flocculating ability in the presence of salt and a wide range of pH (1removal rate of flocculant to 0.1% kaolin suspension could reach more than 90% at pH 7.0. The flocculation mechanisms were investigated by screening effect and means of zeta potential. Holding the positive charge, the KGM-g-PDMC could efficiently remove the negatively charged contaminants such as kaolin suspension. PMID:27083814

  11. Cation exchange pretreatment studies for high recovery - Yuma desalting plant

    SciTech Connect

    Kaakinen, J.W.; Laverty, P.E.

    1983-10-01

    The main purpose of the High Recovery Test Program was to obtain feasibility design data for cation exchange softening to allow a greater fractional recovery of desalted product water at the YDP(Yuma Desalting Plant). Compared to the original YDP design with 70-percent desalting recovery, additional removal of calcium in the desalting feed would allow recoveries over 90 percent. Pilot plant equipment to test this process was operated at the YDTF(Yuma Desalting Test Facility) and consisted of an IX unit and an electrodialyzer to supply reject-brine regenerant for the IX experiments. Gypsum scale buildup in the resin bed could be avoided by regeneration with a high upward flow rate causing a fluidized bed. Reuse of regenerant was also beneficial. Results show that the ion exchange high recovery pretreatment process is highly feasible, and that it is technically possible to achieve high recovery in the YDP. Numerous recommendations for a plant design are given and future studies are noted.

  12. Ammonium and potassium removal from swine liquid manure using clinoptilolite, chabazite and faujasite zeolites.

    PubMed

    Montégut, Gaëtan; Michelin, Laure; Brendlé, Jocelyne; Lebeau, Bénédicte; Patarin, Joël

    2016-02-01

    This study concerns cationic exchanges performed in order to remove ammonium and potassium cations from manure by using various zeolites: clinoptilolite, chabazite and NaX faujasite. First, the effect of temperature (25 °C and 40 °C) on the exchange rate between zeolites and an ammonium chloride solution was investigated. Then, cationic exchanges were performed on these three zeolites using on one side a mixed ammonium and potassium chloride solution reproducing the chemical composition of a swine manure and on the other side the corresponding liquid manure. No significant difference was observed on the exchange rate and the trapping of ammonium cations by changing the temperature (25 or 40 °C). Clinoptilolite showed a good selectivity towards ammonium cations using model (NH4Cl, and mixed NH4Cl/KCl) solutions but is less efficient with the liquid manure. Chabazite and faujasite were found more efficient than clinoptilolite for trapping ammonium cations. However, NaX faujasite enables trapping 3 times more ammonium cations than chabazite from manure (60 and 20 mg/g, respectively). Moreover, chabazite allowed to trap the same amount of potassium cations than NaX faujasite (33 and 35 mg/g, respectively). PMID:26686066

  13. Preliminary study of iron removal from hydrochloric pickling liquor by ion exchange

    SciTech Connect

    Maranon, E.; Suarez, F.; Alonso, F.; Fernandez, Y.; Sastre, H.

    1999-07-01

    Hydrochloric acid from exhausted pickling baths is a residue that has to be managed adequately because of its high pollutant potential. In this work, an ion exchange treatment for removing iron from the spent acid was studied in an attempt to make the re-utilization of said acid viable for industry while reducing the amount of waste generated. Several cationic, anionic, and chelating resins were tested. Cationic and chelating resins are able to remove Fe(II) that is present as a cation in the acid, whereas anionic resins are able to remove Fe(III) that forms anionic complexes with the chloride anion. The capacity of the cationic and chelating resins, although not high, does improve as the iron concentration in the hydrochloric acid increases and when the acid concentration decreases, because there is less competition between the ferrous cation and the protons. The anionic resins showed higher capacity for removing iron, especially the Lewatit MP-500, and this capacity also increased with iron concentration.

  14. Soil Cation Status in Southern California: Interactions of Vehicular Emissions

    NASA Astrophysics Data System (ADS)

    Rossi, R.; Bain, D. J.; Jenerette, D.; Clarke, L. W.

    2012-12-01

    Roadside soils are often enriched in trace metals due to vehicular deposition. However, less attention is given to base cation pools in roadside soils. Relatively high loadings of nitrate from vehicular exhaust should acidify roadside soils, potentially mobilizing cationic species by displacing them from soil exchange sites. In contrast, weathering of road materials can contribute substantial amounts of these cations to the same soils, potentially replenishing cation pools. Base cations are essential nutrients and these dynamics may alter ecosystem processes in near-road environments. Metal concentrations in park and garden soils collected from Southern California (Los Angeles and Riverside Counties) were examined across gradients of road network intensity, climate and geology. In these samples, base cation concentrations decrease in areas of denser road networks. Base cation concentrations also decrease with distance from the road, with near-road samples relatively depleted in base cation concentrations. In addition, base cation concentrations are associated with traffic flux density, with exchange pools decreasing near heavily trafficked areas. These relationships suggest road activity is mobilizing cations, depleting near-road soils of essential nutrient pools, despite road material weathering. This depletion of soil nutrients from exchange pools in roadside soils likely influences local ecological function in unpredictable ways. This observation lays the groundwork for continued characterization of soil metal processes in the increasingly common roadside environment.

  15. Evaluation of cation-anion interaction strength in ionic liquids.

    PubMed

    Fernandes, Ana M; Rocha, Marisa A A; Freire, Mara G; Marrucho, Isabel M; Coutinho, João A P; Santos, Luís M N B F

    2011-04-14

    Electrospray ionization mass spectrometry with variable collision induced dissociation of the isolated [(cation)(2)anion](+) and/or [(anion)(2)cation](-) ions of imidazolium-, pyridinium-, pyrrolidinium-, and piperidinium-based ionic liquids (ILs) combined with a large set of anions, such as chloride, tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonate, and bis[(trifluoromethyl)sulfonyl]imide, was used to carry out a systematic and comprehensive study on the ionic liquids relative interaction energies. The results are interpreted in terms of main influences derived from the structural characteristics of both anion and cation. On the basis of quantum chemical calculations, the effect of the anion upon the dissociation energies of the ionic liquid pair, and isolated [(cation)(2)anion](+) and/or [(anion)(2)cation](-) aggregates, were estimated and are in good agreement with the experimental data. Both experimental and computational results indicate an energetic differentiation between the cation and the anion to the ionic pair. Moreover, it was found that the quantum chemical calculations can describe the trend obtained for the electrostatic cation-anion attraction potential. The impact of the cation-anion interaction strengths in the surface tension of ionic liquids is further discussed. The surface tensions dependence on the cation alkyl chain length, and on the anion nature, follows an analogous pattern to that of the relative cation-anion interaction energies determined by mass spectrometry. PMID:21425809

  16. ARSENIC REMOVAL TECHNOLOGY

    EPA Science Inventory

    Presentation will discuss the state-of-art technology for removal of arsenic from drinking water. Presentation includes results of several EPA field studies on removal of arsenic from existing arsenic removal plants and key results from several EPA sponsored research studies. T...

  17. Removal of Cu(2+) by biochars derived from green macroalgae.

    PubMed

    Kim, Beom-Sik; Lee, Hyung Won; Park, Sung Hoon; Baek, Kitae; Jeon, Jong-Ki; Cho, Hye Jung; Jung, Sang-Chul; Kim, Sang Chai; Park, Young-Kwon

    2016-01-01

    The by-product char of the fast pyrolysis of a green macroalga Enteromorpha compressa was used to remove copper from an aqueous solution. The surface area and the amount of cation exchange capacity (CEC) were increased by steam activation, resulting in enhanced adsorption capacity. Although chemical activation using a KOH solution increased the pore volume and surface area dramatically, it decreased the adsorption capacity because of activating in the KOH solution and washing decreased CEC. Ion exchange between the Cu ions and cations (Na(+), K(+), Ca(2+), and Mg(2+)) as well as adsorption onto the functional groups on the char surface appeared to be important mechanisms for the removal of Cu. A pseudo-second-order kinetic model and Langmuir isotherm model could interpret the kinetics and equilibrium of the Cu adsorption on the E. compressa char. The maximum amount of Cu adsorption on the char was 137 mg g(-1). PMID:25813639

  18. Layered metal sulfides: Exceptionally selective agents for radioactive strontium removal

    PubMed Central

    Manos, Manolis J.; Ding, Nan; Kanatzidis, Mercouri G.

    2008-01-01

    In this article, we report the family of robust layered sulfides K2xMnxSn3-xS6 (x = 0.5–0.95) (KMS-1). These materials feature hexagonal [MnxSn3-xS6]2x− slabs of the CdI2 type and contain highly mobile K+ ions in their interlayer space that are easily exchangeable with other cations and particularly strontium. KMS-1 display outstanding preference for strontium ions in highly alkaline solutions containing extremely large excess of sodium cations as well as in acidic environment where most alternative adsorbents with oxygen ligands are nearly inactive. The implication of these results is that simple layered sulfides should be considered for the efficient remediation of certain nuclear wastes. PMID:18316731

  19. Comparison of commercial cation exchange media for performing marine Toxicity Identification Evaluations (TIEs)

    SciTech Connect

    Charles, J.B.; Burgess, R.M.; Kuhn, A.; Ho, K.T.

    1995-12-31

    In the environment, adverse effects of metals resulting from anthropogenic activity can be manifested as effluent, receiving water, and sediment toxicity to aquatic organisms. In TIEs, the chelator EDTA is commonly used to discriminate metal toxicity from other possible sources of toxicity present in an environmental sample. EDTA is extremely effective at reducing the aqueous bioavailability of toxic divalent transition metals (e.g., Cd, Cu, Ni, Pb, Zn) but, unlike C{sub 18} solid phase extraction (SPE), EDTA does not allow for retrieval of toxicity or toxicants for further identification. In this presentation, the authors report the results of comparisons of five commercially available cation exchange media for use in TIEs. Cation exchange media included three pre-packed SPE columns (Alltech, Supelco, Waters) and two loose packing materials evaluated with both metal spiked seawater and deionized water. Preliminary comparisons demonstrated that Alltech and Supelco SPE columns functioned most effectively. Blank toxicity to two marine species was not observed. Extensive studies of Alltech and Supelco columns using seawater spiked with a range of metal concentrations (e.g., 600 to 10 {micro}g/L) illustrated good precision and quality. both columns removed, on average, {ge} 90% of five metals from seawater. Furthermore, when eluted with small volumes of acid, {ge} 85% of original metal levels were recovered. Evaluations performed with a metal plating industry effluent demonstrated effective removal and subsequent elution of several toxic metals. This study shows the utility of commercial cation exchange columns for removing metals from seawater, and freshwater, for TIE applications.

  20. Effect of Early Seed Removal During Fermentation on Proanthocyanidin Extraction in Red Wine: A Commercial Production Example

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wines (Vitis vinifera L. cv. Merlot) were made by a commercial winery to examine the effects of seed removal at ~10 °Brix on the extraction of proanthocyanidins during fermentation. Seeds were removed at the point when they fell to the bottom of the fermentor, and were thus easily removed during reg...

  1. Synthesis of MnFe2O4@Mn-Co oxide core-shell nanoparticles and their excellent performance for heavy metal removal.

    PubMed

    Ma, Zichuan; Zhao, Dongyuan; Chang, Yongfang; Xing, Shengtao; Wu, Yinsu; Gao, Yuanzhe

    2013-10-21

    Magnetic nanomaterials that can be easily separated and recycled due to their magnetic properties have received considerable attention in the field of water treatment. However, these nanomaterials usually tend to aggregate and alter their properties. Herein, we report an economical and environmentally friendly method for the synthesis of magnetic nanoparticles with core-shell structure. MnFe2O4 nanoparticles have been successfully coated with amorphous Mn-Co oxide shells. The synthesized MnFe2O4@Mn-Co oxide nanoparticles have highly negatively charged surface in aqueous solution over a wide pH range, thus preventing their aggregation and enhancing their performance for heavy metal cation removal. The adsorption isotherms are well fitted to a Langmuir adsorption model, and the maximal adsorption capacities of Pb(II), Cu(II) and Cd(II) on MnFe2O4@Mn-Co oxide are 481.2, 386.2 and 345.5 mg g(-1), respectively. All the metal ions can be completely removed from the mixed metal ion solutions in a short time. Desorption studies confirm that the adsorbent can be effectively regenerated and reused. PMID:23945878

  2. The use of quantitative structure-activity relationship models to develop optimized processes for the removal of tobacco host cell proteins during biopharmaceutical production.

    PubMed

    Buyel, J F; Woo, J A; Cramer, S M; Fischer, R

    2013-12-27

    The production of recombinant pharmaceutical proteins in plants benefits from the low cost of upstream production and the greater scalability of plants compared to fermenter-based systems. Now that manufacturing processes that comply with current good manufacturing practices have been developed, plants can compete with established platforms on equal terms. However, the costs of downstream processing remain high, in part because of the dedicated process steps required to remove plant-specific process-related impurities. We therefore investigated whether the ideal strategy for the chromatographic removal of tobacco host cell proteins can be predicted by quantitative structure-activity relationship (QSAR) modeling to reduce the process development time and overall costs. We identified more than 100 tobacco proteins by mass spectrometry and their structures were reconstructed from X-ray crystallography, nuclear magnetic resonance spectroscopy and/or homology modeling data. The resulting three-dimensional models were used to calculate protein descriptors, and significant descriptors were selected based on recently-published retention data for model proteins to develop QSAR models for protein retention on anion, cation and mixed-mode resins. The predicted protein retention profiles were compared with experimental results using crude tobacco protein extracts. Because of the generic nature of the method, it can easily be transferred to other expression systems such as mammalian cells. The quality of the models and potential improvements are discussed. PMID:24268820

  3. Layered Double Hydroxides: Proposal of a One-Layer Cation-Ordered Structure Model of Monoclinic Symmetry.

    PubMed

    Jayanthi, K; Nagendran, Supreeth; Kamath, P Vishnu

    2015-09-01

    Layered double hydroxides are obtained by partial isomorphous substitution of divalent metal ions by trivalent metal ions in the structure of mineral brucite, Mg(OH)2. The widely reported three-layer polytype of rhombohedral symmetry, designated as polytype 3R1, is actually a one-layer polytype of monoclinic symmetry (space group C2/m, a = 5.401 Å, b = 9.355 Å, c = 11.02 Å, β = 98.89°). This structure has a cation-ordered metal hydroxide layer defined by a supercell a = √3 × a0; b = 3 × a0 (a0 = cell parameter of the cation-disordered rhombohedral cell). Successive layers are translated by (1/3, 0, 1) relative to one another. When successive metal hydroxide layers are translated by (2/3, 0, 1) relative to one another, the resultant crystal, also of monoclinic symmetry, generates a powder pattern corresponding to the polytype hitherto designated as 3R2. This structure model not only removes all the anomalies intrinsic to the widely accepted cation-disordered structure but also abides by Pauling's rule that forbids trivalent cations from occupying neighboring sites and suggests that it is unnecessary to invoke rhombohedral symmetry when the metal hydroxide layer is cation ordered. These results have profound implications for the correct description of polytypism in this family of layered compounds. PMID:26267263

  4. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    PubMed Central

    Boughlala, Zakaria; Fonseca Guerra, Célia

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas‐phase Cl−X and [HCl−X]+ complexes for X+= H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl− and HCl for the various cations. The Cl−X bond becomes longer and weaker along X+ = H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn–Sham molecular orbital (KS‐MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  5. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    PubMed

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  6. Photodissociation of Cerium Oxide Nanocluster Cations.

    PubMed

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)). PMID:27035210

  7. Nanoheterostructure Cation Exchange: Anionic Framework Conservation

    SciTech Connect

    Jain, Prashant K.; Amirav, Lilac; Aloni, Shaul; Alivisatos, A. Paul

    2010-05-11

    In ionic nanocrystals the cationic sub-lattice can be replaced with a different metal ion via a fast, simple, and reversible place-exchange, allowing post-synthetic modification of the composition of the nanocrystal, while preserving its size and shape. Here, we demonstrate for the first time that during such an exchange, the anionic framework of the crystal is preserved. When applied to nanoheterostructures, this phenomenon ensures that compositional interfaces within the heterostructure are conserved throughout the transformation. For instance, a morphology composed of a CdSe nanocrystal embedded in a CdS rod (CdSe/CdS) was exchanged to a PbSe/PbS nanorod via a Cu2Se/Cu2S structure. During every exchange cycle, the seed size and position within the nanorod were preserved, as evident by excitonic features, Z-contrast imaging, and elemental line-scans. Anionic framework conservation extends the domain of cation exchange to the design of more complex and unique nanostructures.

  8. Antibacterial Activity of Geminized Amphiphilic Cationic Homopolymers.

    PubMed

    Wang, Hui; Shi, Xuefeng; Yu, Danfeng; Zhang, Jian; Yang, Guang; Cui, Yingxian; Sun, Keji; Wang, Jinben; Yan, Haike

    2015-12-22

    The current study is aimed at investigating the effect of cationic charge density and hydrophobicity on the antibacterial and hemolytic activities. Two kinds of cationic surfmers, containing single or double hydrophobic tails (octyl chains or benzyl groups), and the corresponding homopolymers were synthesized. The antimicrobial activity of these candidate antibacterials was studied by microbial growth inhibition assays against Escherichia coli, and hemolysis activity was carried out using human red blood cells. It was interestingly found that the homopolymers were much more effective in antibacterial property than their corresponding monomers. Furthermore, the geminized homopolymers had significantly higher antibacterial activity than that of their counterparts but with single amphiphilic side chains in each repeated unit. Geminized homopolymers, with high positive charge density and moderate hydrophobicity (such as benzyl groups), combine both advantages of efficient antibacterial property and prominently high selectivity. To further explain the antibacterial performance of the novel polymer series, the molecular interaction mechanism is proposed according to experimental data which shows that these specimens are likely to kill microbes by disrupting bacterial membranes, leading them unlikely to induce resistance. PMID:26606647

  9. Divalent cation affinity sites in Paramecium aurelia.

    PubMed

    Fisher, G; Kaneshiro, E S; Peters, P D

    1976-05-01

    Sites with high calcium affinity in Paramecium aurelia were identified by high calcium (5 mM) fixation and electron microscope methods. Electron-opaque deposits were observed on the cytoplasmic side of surface membranes, particularly at the basal regions of cilia and trichocyst-pellicle fusion sites. Deposits were also observed on some smooth cytomembranes, within the axoneme of cilia, and on basal bodies. The divalent cations, Mg2+, Mn2+, Sr2+, Ni2+, Ba2+, and Zn2+, could be substituted for Ca2+ in the procedure. Deposits were larger with 5 mM Sr2+. Ba2+, and Mn2+ at ciliary transverse plates and the terminal plate of basal bodies. Microprobe analysis showed that Ca and C1 were concentrated within deposits. In some analyses, S and P were detected in deposits. Also, microprobe analysis of 5 mM Mn2+-fixed P. aurelia showed that those deposits were enriched in Mn and C1 and sometimes enriched in P. Deposits were seen only when the ciliates were actively swimming at the time of fixation. Locomotory mutants having defective membrane Ca-gating mechanisms and ciliates fixed while exhibiting ciliary reversal showed no obvious differences in deposition pattern and intensity. Possible correlations between electron-opaque deposits and the locations of intramembranous particles seen by freeze-fracture studied, as well as sites where fibrillar material associate with membranes are considered. The possibility that the action sites of calcium and other divalent cations were identified is discussed. PMID:1262398

  10. Cationic Antimicrobial Polymers and Their Assemblies

    PubMed Central

    Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

    2013-01-01

    Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

  11. Ceramic Spheres From Cation Exchange Beads

    NASA Technical Reports Server (NTRS)

    Dynys, F. W.

    2003-01-01

    Porous ZrO2 and hollow TiO2 spheres were synthesized from a strong acid cation exchange resin. Spherical cation exchange beads, polystyrene based polymer, were used as a morphological-directing template. Aqueous ion exchange reaction was used to chemically bind (ZrO)(2+) ions to the polystyrene structure. The pyrolysis of the polystyrene at 600 C produces porous ZrO2 spheres with a surface area of 24 sq m/g with a mean sphere size of 42 microns. Hollow TiO2 spheres were synthesized by using the beads as a micro-reactor. A direct surface reaction - between titanium isopropoxide and the resin beads forms a hydrous TiO2 shell around the polystyrene core. The pyrolysis of the polystyrene core at 600 C produces hollow anatase spheres with a surface area of 42 sq m/g with a mean sphere size of 38 microns. The formation of ceramic spheres was studied by XRD, SEM and B.E.T. nitrogen adsorption measurements.

  12. Interaction of Hyaluronan with Cationic Nanoparticles.

    PubMed

    Bano, Fouzia; Carril, Mónica; Di Gianvincenzo, Paolo; Richter, Ralf P

    2015-08-01

    The polysaccharide hyaluronan (HA) is a main component of peri- and extracellular matrix, and an attractive molecule for materials design in tissue engineering and nanomedicine. Here, we study the morphology of complexes that form upon interaction of nanometer-sized amine-coated gold particles with this anionic, linear, and regular biopolymer in solution and grafted to a surface. We find that cationic nanoparticles (NPs) have profound effects on HA morphology on the molecular and supramolecular scale. Quartz crystal microbalance (QCM-D) shows that depending on their relative abundance, cationic NPs promote either strong compaction or swelling of films of surface-grafted HA polymers (HA brushes). Transmission electron and atomic force microscopy reveal that the NPs do also give rise to complexes of distinct morphologies-compact nanoscopic spheres and extended microscopic fibers-upon interaction with HA polymers in solution. In particular, stable and hydrated spherical complexes of single HA polymers with NPs can be prepared when balancing the ionizable groups on HA and NPs. The observed self-assembly phenomena could be useful for the design of drug delivery vehicles and a better understanding of the reorganization of HA-rich synthetic or biological matrices. PMID:26146006

  13. A cation counterflux supports lysosomal acidification

    PubMed Central

    Steinberg, Benjamin E.; Huynh, Kassidy K.; Brodovitch, Alexandre; Jabs, Sabrina; Stauber, Tobias; Jentsch, Thomas J.

    2010-01-01

    The profound luminal acidification essential for the degradative function of lysosomes requires a counter-ion flux to dissipate an opposing voltage that would prohibit proton accumulation. It has generally been assumed that a parallel anion influx is the main or only counter-ion transport that enables acidification. Indeed, defective anion conductance has been suggested as the mechanism underlying attenuated lysosome acidification in cells deficient in CFTR or ClC-7. To assess the individual contribution of counter-ions to acidification, we devised means of reversibly and separately permeabilizing the plasma and lysosomal membranes to dialyze the cytosol and lysosome lumen in intact cells, while ratiometrically monitoring lysosomal pH. Replacement of cytosolic Cl− with impermeant anions did not significantly alter proton pumping, while the presence of permeant cations in the lysosomal lumen supported acidification. Accordingly, the lysosomes were found to acidify to the same pH in both CFTR- and ClC-7–deficient cells. We conclude that cations, in addition to chloride, can support lysosomal acidification and defects in lysosomal anion conductance cannot explain the impaired microbicidal capacity of CF phagocytes. PMID:20566682

  14. Diffusion of highly charged cations in olivine

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.; Liang, Y.

    2012-12-01

    Diffusion of tungsten, titanium and phosphorus have been measured in natural iron-bearing olivine (~Fo90) and synthetic forsterite. Experiments were run under buffered conditions (with iron-wustite or Ni-NiO buffers) in 1-atm furnaces. The sources of diffusant for experiments were MgWO4 for tungsten diffusion, Mg2TiO4 for Ti diffusion, and AlPO4 for P diffusion; in all cases these compounds were pre-reacted at high temperature with Mg2SiO4 or Fe-bearing olivine prior to diffusion anneals. Samples were placed with the source materials in noble metal or silica capsules, which were sealed under vacuum in silica glass ampoules with solid buffers. Rutherford backscattering spectrometry (RBS) was used to measure depth profiles for all sets of experiments; measurements of P were also made with Nuclear Reaction Analysis using the 31P(α,p)34S reaction. These new data suggest marked differences among diffusivities of these cations, with titanium diffusion faster than diffusion of tungsten, but slower than diffusion of phosphorus over the conditions investigated. Diffusivities of all of these elements appear significantly slower than those of divalent cations in olivine. These results will be discussed in context with extant diffusion data for major, trace and minor elements in olivine. The effects of oxygen fugacity and olivine composition on diffusion, and potential implications for diffusion mechanisms will also be considered.

  15. Graphitic packing removal tool

    DOEpatents

    Meyers, K.E.; Kolsun, G.J.

    1997-11-11

    Graphitic packing removal tools for removal of the seal rings in one piece are disclosed. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal. 5 figs.

  16. Graphitic packing removal tool

    DOEpatents

    Meyers, Kurt Edward; Kolsun, George J.

    1997-01-01

    Graphitic packing removal tools for removal of the seal rings in one piece. he packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  17. Graphitic packing removal tool

    SciTech Connect

    Meyers, K.E.; Kolsun, G.J.

    1996-12-31

    Graphitic packing removal tools are described for removal of the seal rings in one piece from valves and pumps. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  18. Long-term evaluation of different strategies of cationic polyelectrolyte dosage to control fouling in a membrane bioreactor treating refinery effluent.

    PubMed

    Alkmim, Aline R; da Costa, Paula R; Moser, Priscila B; França Neta, Luzia S; Santiago, Vânia M J; Cerqueira, Ana C; Amaral, Míriam C S

    2016-04-01

    In this article, the long-term use of cationic polyelectrolyte to improve the sludge filterability and to control membrane fouling in bioreactor membrane while treating refinery effluents have been evaluated in pilot scale. Corrective and preventive cationic polyelectrolyte dosages have been added to the membrane bioreactor (MBR) to evaluate the membrane fouling mitigation in both strategies. The results have confirmed that the use of the Membrane performance enhancer (MPE) increased the sludge filterability and reduced the membrane fouling. During the monitoring period, stress events occurred due to the increase in oil and grease and phenol concentrations in the MBR feeds. The preventive use of cationic polyelectrolyte allowed for a more effective and stable sludge filterability, with lower cationic polyelectrolyte consumption and without decreasing MBR's overall pollutant removal performance. PMID:26508453

  19. Electron Spin Resonance Spectroscopic Studies of Radical Cation Reactions.

    NASA Astrophysics Data System (ADS)

    Dai, Sheng

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra in this work is derived by using the general effective Hamiltonian theory in the usual Schrodinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between beta-hydrogen coupling constants and their geometric orientations is derived through the use of a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and syn-sesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl_3 matrix at low temperature. The ESR spectra of the former radical cation exhibit a novel alternating linewidth effect arising from an internal relation between the coupling constants for the four equivalent pairs of hydrogens. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is shown to be the 3-iminiopropyl distonic species(3-iminium-1-propyl radical) resulting from a symmetry-allowed 1,2-hydrogen shift in the parent radical cation. The nucleophilic endocyclization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran -3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexadiyne have resulted in the first spectroscopic characterization of the radical cation Cope rearrangement, the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5 -hexatetraene radical cation. ESR studies show that the symmetric(C_{rm 2v}) bicyclo (3.3.0) -octa-2,6-diene-4,8-diyl(a bridged 1,4 -bishomobenzene species) radical cation is

  20. Controlling Cesium Cation Recognition via Cation Metathesis within and Ion Pair Receptor

    SciTech Connect

    Kim, Sung Kuk; Vargas-Zuniga, Gabriela; Hay, Benjamin; Young, Neil J; Delmau, Laetitia Helene; Lee, Prof. Chang-Hee; Kim, Jong Seung; Lynch, Vincent M.; Sessler, Jonathan L.

    2012-01-01

    Ion pair receptor 3 bearing an anion binding site and multiple cation binding sites has been synthesized and shown to function in a novel binding-release cycle that does not necessarily require displacement to effect release. The receptor forms stable complexes with the test cesium salts, CsCl and CsNO{sub 3}, in solution (10% methanol-d{sub 4} in chloroform-d) as inferred from {sup 1}H NMR spectroscopic analyses. The addition of KClO{sub 4} to these cesium salt complexes leads to a novel type of cation metathesis in which the 'exchanged' cations occupy different binding sites. Specifically, K{sup +} becomes bound at the expense of the Cs{sup +} cation initially present in the complex. Under liquid-liquid conditions, receptor 3 is able to extract CsNO{sub 3} and CsCl from an aqueous D{sub 2}O layer into nitrobenzene-d{sub 5} as inferred from {sup 1}H NMR spectroscopic analyses and radiotracer measurements. The Cs{sup +} cation of the CsNO{sub 3} extracted into the nitrobenzene phase by receptor 3 may be released into the aqueous phase by contacting the loaded nitrobenzene phase with an aqueous KClO{sub 4} solution. Additional exposure of the nitrobenzene layer to chloroform and water gives 3 in its uncomplexed, ion-free form. This allows receptor 3 to be recovered for subsequent use. Support for the underlying complexation chemistry came from single-crystal X-ray diffraction analyses and gas-phase energy-minimization studies.

  1. Integration of a contactless conductivity detector into a commercial capillary cassette. Detection of inorganic cations and catecholamines.

    PubMed

    Vuorinen, Pasi S; Jussila, Matti; Sirén, Heli; Palonen, Sami; Riekkola, Marja-Liisa

    2003-03-21

    A contactless conductivity detector integrated into the capillary cassette of Agilent (3D)CE equipment is described. The detector is user-friendly, compact and easily modified. The UV detector of the (3D)CE equipment is available parallel with the contactless conductivity detector increasing the detection power. Two electrolyte solutions, 2-(N-morpholino)ethanesulfonic acid-histidine solution (20 mM, pH 6.0) and ammonium acetate (10 mM, pH 4.0), were used as the separation media for inorganic cations and organic catecholamines, respectively. The detection limit for all metal cations except barium was under 0.5 mg/l, and that for four catecholamines was ca. 10 mg/l. This last value was the same order of magnitude as achieved with parallel UV detection. PMID:12685582

  2. Ground state of naphthyl cation: Singlet or triplet?

    SciTech Connect

    Dutta, Achintya Kumar; Vaval, Nayana Pal, Sourav; Manohar, Prashant U.

    2014-03-21

    We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (π,σ) type, whereas in 2-naphthyl cation it is (σ,σ{sup ′}) type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz.

  3. Solvent effect on cation-π interactions with Al3+.

    PubMed

    Larrucea, Julen

    2012-09-01

    Cation-π interactions are known to be one of the strongest noncovalent forces in the gas phase, but they rarely occur in a fully solvated environment. The present work used two different ab initio molecular dynamics-based approaches to describe the correlation between the strength of the cation-π interactions and the number of water molecules surrounding the cation. Five different complexes between an aluminum cation and different molecules containing aromatic rings were studied, and the degree of hydration of each complex was varied. Results indicated that cation-π interactions vanish when the aluminum cation is surrounded by more than three water molecules. The results also highlighted the influence of -OH ligands on the interaction strength. PMID:22581060

  4. Magnetic zeolite NaA: synthesis, characterization based on metakaolin and its application for the removal of Cu2+, Pb2+.

    PubMed

    Liu, Haibo; Peng, Shuchuan; Shu, Lin; Chen, Tianhu; Bao, Teng; Frost, Ray L

    2013-06-01

    The optimum parameters for synthesis of zeolite NaA based on metakaolin were investigated according to results of cation exchange capacity and static water adsorption of all synthesis products and selected X-ray diffraction (XRD). Magnetic zeolite NaA was synthesized by adding Fe3O4 in the precursor of zeolite. Zeolite NaA and magnetic zeolite NaA were characterized with scanning electron microscopy (SEM) and XRD. Magnetic zeolite NaA with different Fe3O4 loadings was prepared and used for removal of heavy metals (Cu(2+), Pb(2+)). The results show the optimum parameters for synthesis zeolite NaA are SiO2/Al2O3=2.3, Na2O/SiO2=1.4, H2O/Na2O=50, crystallization time 8h, crystallization temperature 95 °C. The addition of Fe3O4 makes the NaA zeolite with good magnetic susceptibility and good magnetic stability regardless of the Fe3O4 loading, confirming the considerable separation efficiency. Additionally, Fe3O4 loading had a little effect on removal of heavy metal by magnetic zeolite, however, the adsorption capacity still reaches 2.3 mmol g(-1) for Cu(2+), Pb(2+) with a removal efficiency of over 95% in spite of 4.7% Fe3O4 loading. This indicates magnetic zeolite can be used to remove metal heavy at least Cu(2+), Pb(2+) from water with metallic contaminants and can be separated easily after a magnetic process. PMID:23340053

  5. Infrared spectroscopic investigations of cationic ethanol, propanol, and butanol

    NASA Astrophysics Data System (ADS)

    Matsuda, Yoshiyuki; Harigaya, Hiroyuki; Xie, Min; Takahashi, Kaito; Fujii, Asuka

    2015-11-01

    Infrared spectroscopy of the alcohol cations of ethanol, propanol, and butanol was performed to investigate their structures and hyperconjugation mechanisms. In the ethanol cation, the Csbnd C bond hyperconjugates with the singly occupied molecular orbital (SOMO) at the oxygen atom, so that the Csbnd C bond weakens and the bond length elongates. Multiple hyperconjugations among SOMO, the Csbnd C bond, and the end Csbnd H bond occur in the propanol cation and enhance the acidity of the Csbnd H bond through the delocalization of its bonding σ electron. The butanol cation forms the oxonium-type structure through the proton transfer from the terminal CH bond.

  6. Incorporation of zero valent iron nanoparticles in the matrix of cationic resin beads for the remediation of Cr(VI) contaminated waters.

    PubMed

    Toli, Aikaterini; Chalastara, Konstantina; Mystrioti, Christiana; Xenidis, Anthimos; Papassiopi, Nymphodora

    2016-07-01

    The objective of present study was to obtain the fixation of nano zero valent iron (nZVI) particles on a permeable matrix and evaluate the performance of this composite material for the removal of Cr(VI) from contaminated waters. The experiments were carried out using the cationic resin Dowex 50WX2 as porous support of the iron nanoparticles. The work was carried out in two phases. The first phase involved the fixation of nZVI on the resin matrix. The resin granules were initially mixed with a FeCl3 solution to obtain the adsorption of Fe(III). Then the Fe(III) loaded resin (RFe) was treated with polyphenol solutions to obtain the reduction of Fe(III) to the elemental state. Two polyphenol solutions were tested as reductants, i.e. green tea extract and gallic acid. Green tea was found to be inefficient, probably due to the relatively big size of the contained polyphenol molecules, but gallic acid molecules were able to reach adsorbed Fe(III) and reduce the cations to the elemental state. The second phase was focused on the investigation of Cr(VI) reduction kinetics using the nanoiron loaded resins (R-nFe). It was found that the reduction follows a kinetic law of first order with respect to Cr(VI) and to the embedded nanoiron. Compared to other similar products, this composite material was found to have comparable performance regarding reaction rates and higher degree of iron utilization. Namely the rate constant for the reduction of Cr(VI), in the presence of 1 mM nZVI, was equivalent to 1.4 h of half-life time at pH 3.2 and increased to 24 h at pH 8.5. The degree of iron utilization was as high as 0.8 mol of reduced Cr(VI) per mole of iron. It was also found that this composite material can be easily regenerated and reused for Cr(VI) reduction without significant loss of efficiency. PMID:27108046

  7. Removal of Pb(2+) from water environment using a novel magnetic chitosan/graphene oxide imprinted Pb(2.).

    PubMed

    Wang, Yanhui; Li, LeiLei; Luo, Chuannan; Wang, Xiaojiao; Duan, Huimin

    2016-05-01

    A novel, magnetic chitosan coating on the surface of graphene oxide was (Pb-MCGO) successfully synthesized using Pb(2+) as imprinted ions for adsorption and removal of Pb(2+) from aqueous solutions. The magnetic composite bioadsorbent was characterized by SEM, FTIR and XRD measurements. Batch adsorption experiments were performed to evaluate the adsorption conditions, selectivity and reusability. The results showed that the maximum adsorption capacity was 79mg/g, observed at pH 5 and 303K. Equilibrium adsorption was achieved within 40min. The kinetic data could be fitted with a pseudo-second order equation. Adsorption process could be well described by Langmuir adsorption isotherms. The selectivity coefficient of Pb(2+) and other metal cations onto Pb-MCGO indicated an overall preference for Pb(2+), which was much higher than non-imprinted MCGO beads. Moreover, the sorbent was stable and easily recovered, the adsorption capacity was about 90% of the initial saturation adsorption capacity after being used five times. PMID:26826288

  8. The removal of anionic surfactants from water in coagulation process.

    PubMed

    Kaleta, Jadwiga; Elektorowicz, Maria

    2013-01-01

    This paper presents the results of a laboratory study on the effectiveness of the coagulation process in removing surfactants from water. The application of traditional coagulants (aluminium sulfate and iron chlorides) has not brought satisfactory results, the reduction in anionic surfactant (AS) content reached 7.6% and 10%, respectively. Adding cationic polyelectrolyte (Zetag-50) increased the removal efficiency to 24%. Coagulation using a polyelectrolyte alone proved to be more efficient, the reduction in surfactant content fluctuated at a level of about 50%. Complete surfactant removal was obtained when powdered activated carbon was added 5 minutes before the basic coagulant to the coagulation process. The efficiency of surfactant coagulation also increased after the application of powdered clinoptilolite, but to a smaller degree. Then the removal of AS was found to be improved by dosing powdered clinoptilolite simultaneously or with short delay after the addition of the basic coagulant. PMID:23837351

  9. Removal of phenols from wastewater by soluble and immobilized tyrosinase

    SciTech Connect

    Wada, Shinji; Ichikawa, Hiroyasu; Tatsumi, Kenji )

    1993-09-20

    An enzymatic method for removal of phenols from industrial wastewater was investigated. Phenols in an aqueous solution were removed after treatment with mushroom tyrosinase. The reduction order of substituted phenols is catechol > p-cresol > p-chlorophenol > phenol > p-methoxyphenol. In the treatment of tyrosinase alone, no precipitate was formed but a color change from colorless to dark-brown was observed. The colored products were removed by chitin and chitosan which are available abundantly as shellfish waste. In addition, the reduction rate of phenols was observed to be accelerated in the presence of chitosan. Tyrosinase, immobilized by using amino groups in the enzyme on cation exchange resins, can be used repeatedly. By treatment with immobilized tyrosinase, 100% of phenol was removed after 2 h, and the activity was reduced very little even after 10 repeat treatments.

  10. Mechanism of paint removing by organic solvents

    SciTech Connect

    Del Nero, V.; Siat, C.; Marti, M.J.; Aubry, J.M.; Lallier, J.P.; Dupuy, N.; Huvenne, J.P.

    1996-01-01

    The mechanism of paint removing has been studied by comparing the stripping efficiency of a given solvent with its ability to swell the film. The most effective solvents have a Hildebrand{close_quote}s parameter, {delta}{sub H}, ranging from 10.5 to 12 and a Dimroth parameter, ET{sub (30)}, ranging from 0.25 to 0.4. The synergy observed with the mixtures DMSO/non polar solvent is explained by a dissociation of the DMSO clusters into individual molecules which diffuse more easily. {copyright} {ital 1996 American Institute of Physics.}

  11. Human proximal tubule epithelial cells cultured on hollow fibers: living membranes that actively transport organic cations.

    PubMed

    Jansen, J; De Napoli, I E; Fedecostante, M; Schophuizen, C M S; Chevtchik, N V; Wilmer, M J; van Asbeck, A H; Croes, H J; Pertijs, J C; Wetzels, J F M; Hilbrands, L B; van den Heuvel, L P; Hoenderop, J G; Stamatialis, D; Masereeuw, R

    2015-01-01

    The bioartificial kidney (BAK) aims at improving dialysis by developing 'living membranes' for cells-aided removal of uremic metabolites. Here, unique human conditionally immortalized proximal tubule epithelial cell (ciPTEC) monolayers were cultured on biofunctionalized MicroPES (polyethersulfone) hollow fiber membranes (HFM) and functionally tested using microfluidics. Tight monolayer formation was demonstrated by abundant zonula occludens-1 (ZO-1) protein expression along the tight junctions of matured ciPTEC on HFM. A clear barrier function of the monolayer was confirmed by limited diffusion of FITC-inulin. The activity of the organic cation transporter 2 (OCT2) in ciPTEC was evaluated in real-time using a perfusion system by confocal microscopy using 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP(+)) as a fluorescent substrate. Initial ASP(+) uptake was inhibited by a cationic uremic metabolites mixture and by the histamine H2-receptor antagonist, cimetidine. In conclusion, a 'living membrane' of renal epithelial cells on MicroPES HFM with demonstrated active organic cation transport was successfully established as a first step in BAK engineering. PMID:26567716

  12. Cationic poly(ɛ-caprolactone) surface functionalized mesoporous silica nanoparticles and their application in drug delivery

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Wang, Zhaojun; Zhou, Weimin; Min, Guoquan; Lang, Meidong

    2013-07-01

    Cationic poly(ɛ-caprolactone) modified hollow mesoporous silica (HMSNs) was achieved by a post graft method via covalent linkage between the silanols on the surface of silica and the trimethoxysilane groups at the end of the poly(γ-(carbamic acid benzyl ester)-ɛ-caprolactone). The trimethoxysilane groups were introduced to poly(γ-(carbamic acid benzyl ester)-ɛ-caprolactone) by ring opening polymerization of γ-(carbamic acid benzyl ester)-ɛ-caprolactone (γCABɛCL) with 3-aminopropyl trimethoxysilane as initiator. Subsequently, the polymer was grafted to the HMSNs and the protected groups of Cbz were removed, thus the amino groups were obtained accordingly. The structure of the polymer was confirmed by 1H NMR. In addition, the TEM and SEM demonstrated that the HMSNs were spherical and the polymer was well coated on the spheres. FTIR, TGA and N2 adsorption results proved that the modified processes were effective and the structure of the HMSNs was well reserved. The cationic surface was further confirmed by zeta potential. Moreover, the potential application of the HMSNs in drug delivery was studied with ammonium glycyrrhizinate (AMG) as model drug. Results showed that the cationic HMSNs could be an efficient AMG carrier.

  13. Solution Versus Gas-Phase Modification of Peptide Cations with NHS-Ester Reagents

    NASA Astrophysics Data System (ADS)

    Mentinova, Marija; Barefoot, Nathan Z.; McLuckey, Scott A.

    2012-02-01

    A comparison between solution and gas phase modification of primary amine sites in model peptide cations with N-hydroxysuccinimide (NHS) ester reagents is presented. In all peptides, the site of modification in solution was directed to the N-terminus by conducting reactions at pH = 5, whereas for the same peptides, a lysine residue was preferentially modified in the gas phase. The difference in pKa values of the N-terminus and ɛ-amino group of the lysine allows for a degree of control over sites of protonation of the peptides in aqueous solution. With removal of the dielectric and multiple charging of the peptide ions in the gas phase, the accommodation of excess charge can affect the preferred sites of reaction. Interaction of the lone pair of the primary nitrogen with a proton reduces its nucleophilicity and, as a result, its reactivity towards NHS-esters. While no evidence for reaction of the N-terminus with sulfo-NHS-acetate was noted in the model peptide cations, a charge inversion experiment using bis[sulfosuccinimidyl] suberate, a cross-linking reagent with two sulfo-NHS-ester functionalities, showed modification of the N-terminus. Hence, an unprotonated N-terminus can serve as a nucleophile to displace NHS, which suggests that its lack of reactivity with the peptide cations is likely due to the participation of the N-terminus in solvating excess charge.

  14. Human proximal tubule epithelial cells cultured on hollow fibers: living membranes that actively transport organic cations

    PubMed Central

    Jansen, J.; De Napoli, I. E; Fedecostante, M.; Schophuizen, C. M. S.; Chevtchik, N. V.; Wilmer, M. J.; van Asbeck, A. H.; Croes, H. J.; Pertijs, J. C.; Wetzels, J. F. M.; Hilbrands, L. B.; van den Heuvel, L. P.; Hoenderop, J. G.; Stamatialis, D.; Masereeuw, R.

    2015-01-01

    The bioartificial kidney (BAK) aims at improving dialysis by developing ‘living membranes’ for cells-aided removal of uremic metabolites. Here, unique human conditionally immortalized proximal tubule epithelial cell (ciPTEC) monolayers were cultured on biofunctionalized MicroPES (polyethersulfone) hollow fiber membranes (HFM) and functionally tested using microfluidics. Tight monolayer formation was demonstrated by abundant zonula occludens-1 (ZO-1) protein expression along the tight junctions of matured ciPTEC on HFM. A clear barrier function of the monolayer was confirmed by limited diffusion of FITC-inulin. The activity of the organic cation transporter 2 (OCT2) in ciPTEC was evaluated in real-time using a perfusion system by confocal microscopy using 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP+) as a fluorescent substrate. Initial ASP+ uptake was inhibited by a cationic uremic metabolites mixture and by the histamine H2-receptor antagonist, cimetidine. In conclusion, a ‘living membrane’ of renal epithelial cells on MicroPES HFM with demonstrated active organic cation transport was successfully established as a first step in BAK engineering. PMID:26567716

  15. Permeation of Water through Cation Exchange Membranes

    PubMed Central

    Lakshminarayanaiah, N.

    1967-01-01

    Water permeabilities as well as other membrane parameters, such as exchange capacity, water content, and specific conductance, have been measured for two cation exchange membranes in the H form. The conductance of membrane with low water content was less than that of the membrane with high water content. These data have been discussed in the light of an existing theory and found inadequate to explain the results in a quantitative way. Water permeability of the membranes subject to mechanical pressure was found to be higher than their isotopic water permeability, according to expectation. These data have been examined from the standpoint of thermodynamic and kinetic theories of water flow in membranes and used to estimate the average size of membrane pores. PMID:6048874

  16. Univalent-cation-elicited acidification by yeasts.

    PubMed

    Kotyk, A; Georghiou, G

    1994-08-01

    Addition of univalent cations to sugar-metabolizing Saccharomyces cerevisiae, Schizosaccharomyces pombe and Lodderomyces elongisporus brought about a powerful acidification of the external medium with rates up to nearly 20 nmol H+ per min per mg dry wt. in S. cerevisiae, over 15 nmol in S. pombe, and 4.7 nmol in L. elongisporus. These rates were as much as 20 times, 5.5 times and 10.3 times, respectively. higher than in the absence of K+. Use of galactose-induced cells, of H(+)-ATPase-deficient mutants and observations over the entire growth curve indicated that the K+ effect on H+ extrusion is not connected with the H(+)-ATPase function as such but rather depends on metabolic reactions producing ATP. The effect has apparently nothing to do with the electrical potential across the plasma membrane. PMID:7804140

  17. Cation Diffusion Facilitator family: Structure and function.

    PubMed

    Kolaj-Robin, Olga; Russell, David; Hayes, Kevin A; Pembroke, J Tony; Soulimane, Tewfik

    2015-05-22

    The Cation Diffusion Facilitators (CDFs) form a family of membrane-bound proteins capable of transporting zinc and other heavy metal ions. Involved in metal tolerance/resistance by efflux of ions, CDF proteins share a two-modular architecture consisting of a transmembrane domain (TMD) and C-terminal domain (CTD) that protrudes into the cytoplasm. Discovery of a Zn²⁺ and Cd²⁺ CDF transporter from a marine bacterium Maricaulis maris that does not possess the CTD questions current perceptions regarding this family of proteins. This article describes a new, CTD-lacking subfamily of CDFs and our current knowledge about this family of proteins in the view of these findings. PMID:25896018

  18. Cell Penetrating Peptides and Cationic Antibacterial Peptides

    PubMed Central

    Rodriguez Plaza, Jonathan G.; Morales-Nava, Rosmarbel; Diener, Christian; Schreiber, Gabriele; Gonzalez, Zyanya D.; Lara Ortiz, Maria Teresa; Ortega Blake, Ivan; Pantoja, Omar; Volkmer, Rudolf; Klipp, Edda; Herrmann, Andreas; Del Rio, Gabriel

    2014-01-01

    Cell penetrating peptides (CPP) and cationic antibacterial peptides (CAP) have similar physicochemical properties and yet it is not understood how such similar peptides display different activities. To address this question, we used Iztli peptide 1 (IP-1) because it has both CPP and CAP activities. Combining experimental and computational modeling of the internalization of IP-1, we show it is not internalized by receptor-mediated endocytosis, yet it permeates into many different cell types, including fungi and human cells. We also show that IP-1 makes pores in the presence of high electrical potential at the membrane, such as those found in bacteria and mitochondria. These results provide the basis to understand the functional redundancy of CPPs and CAPs. PMID:24706763

  19. Cationic nanofibrillar cellulose with high antibacterial properties.

    PubMed

    Chaker, Achraf; Boufi, Sami

    2015-10-20

    Cationic nanofibrillar cellulose (C-NFC) has been prepared via a high pressure homogenization using quaternized cellulose fibers with glycidyltrimethylammonium chloride. It has been shown that the quaternization of dried softwood pulp facilitated the defibrillation processes and prevented clogging of the homogenizer. The effects of the trimethylammonium chloride content on the fibrillation yield, the transparency degree of the gel, the rheological behavior of the NFC suspension and their electrokinetic properties were investigated. AFM observation showed that the NFC suspension consisted of individualized cellulose I nanofibrils 4-5nm in width and length in the micronic scale. In addition to their strong reinforcing potential, the inclusion of C-NFC into a polymer matrix was shown to efficiently enhance the antibacterial activity. The reinforcing potential of C-NFC, studied by dynamic mechanical analysis (DMA), was compared to anionic NFC and the difference was explained in terms of the nanofibrils capacities to build up a strong networks held by hydrogen bonding. PMID:26256179

  20. Antiviral effect of cationic compounds on bacteriophages

    PubMed Central

    Ly-Chatain, Mai H.; Moussaoui, Saliha; Vera, Annabelle; Rigobello, Véronique; Demarigny, Yann

    2013-01-01

    The antiviral activity of several cationic compounds – cetyltrimethylammonium bromide (CTAB), chitosan, nisin, and lysozyme – was investigated on the bacteriophage c2 (DNA head and non-contractile tail) infecting Lactococcus strains and the bacteriophage MS2 (F-specific RNA) infecting E. coli. Firstly, these activities were evaluated in a phosphate buffer pH 7 – 10 mM. The CTAB had a virucidal effect on the Lactococcus bacteriophages, but not on the MS2. After 1 min of contact with 0.125 mM CTAB, the c2 population was reduced from 6 to 1.5 log(pfu)/mL and completely deactivated at 1 mM. On the contrary, chitosan inhibited the MS2 more than it did the bacteriophages c2. No antiviral effect was observed for the nisin or the lysozyme on bacteriophages after 1 min of treatment. A 1 and 2.5 log reduction was respectively observed for nisin and lysozyme when the treatment time increased (5 or 10 min). These results showed that the antiviral effect depended both on the virus and structure of the antimicrobial compounds. The antiviral activity of these compounds was also evaluated in different physico-chemical conditions and in complex matrices. The antiviral activity of CTAB was impaired in acid pH and with an increase of the ionic strength. These results might be explained by the electrostatic interactions between cationic compounds and negatively charged particles such as bacteriophages or other compounds in a matrix. Milk proved to be protective suggesting the components of food could interfere with antimicrobial compounds. PMID:23487495

  1. Electronic structures, vibrational spectra, and revised assignment of aniline and its radical cation: Theoretical study

    NASA Astrophysics Data System (ADS)

    Wojciechowski, Piotr M.; Zierkiewicz, Wiktor; Michalska, Danuta; Hobza, Pavel

    2003-06-01

    Comprehensive studies of the molecular and electronic structures, vibrational frequencies, and infrared and Raman intensities of the aniline radical cation, C6H5NH2+ have been performed by using the unrestricted density functional (UB3LYP) and second-order Møller-Plesset (UMP2) methods with the extended 6-311++G(df,pd) basis set. For comparison, analogous calculations were carried out for the closed-shell neutral aniline. The studies provided detailed insight into the bonding changes that take place in aniline upon ionization. The natural bond orbital (NBO) analysis has revealed that the pπ-radical conjugative interactions are of prime importance in stabilizing the planar, quinoid-type structure of the aniline radical cation. It is shown that the natural charges calculated for aniline are consistent with the chemical properties of this molecule (an ortho- and para-directing power of the NH2 group in electrophilic substitutions), whereas Mulliken charges are not reliable. The theoretical vibrational frequencies of aniline, calculated by the B3LYP method, show excellent agreement with the available experimental data. In contrast, the MP2 method is deficient in predicting the frequencies of several modes in aniline, despite the use of the extended basis set in calculations. The frequencies of aniline radical cation, calculated at the UB3LYP/6-311++G(df,pd) level, are in very good agreement with the recently reported experimental data from zero kinetic energy photoelectron and infrared depletion spectroscopic studies. The clear- cut assignment of the IR and Raman spectra of the investigated molecules has been made on the basis of the calculated potential energy distributions. Several bands in the spectra have been reassigned. It is shown that ionization of aniline can be easily identified by the appearance of the very strong band at about 1490 cm-1, in the Raman spectrum. The redshift of the N-H stretching frequencies and the blueshift of the C-H stretching

  2. Phenolic cation exchange resin material for recovery of cesium and strontium

    DOEpatents

    Ebra, Martha A.; Wallace, Richard M.

    1983-01-01

    A phenolic cation exchange resin with a chelating group has been prepared by reacting resorcinol with iminodiacetic acid in the presence of formaldehyde at a molar ratio of about 1:1:6. The material is highly selective for the simultaneous recovery of both cesium and strontium from aqueous alkaline solutions, such as, aqueous alkaline nuclear waste solutions. The organic resins are condensation polymers of resorcinol and formaldehyde with attached chelating groups. The column performance of the resins compares favorably with that of commercially available resins for either cesium or strontium removal. By combining Cs.sup.+ and Sr.sup.2+ removal in the same bed, the resins allow significant reduction of the size and complexity of facilities for processing nuclear waste.

  3. Phenolic cation-exchange resin material for recovery of cesium and strontium. [Patent application

    DOEpatents

    Ebra, M.A.; Wallace, R.M.

    1982-05-05

    A phenolic cation exchange resin with a chelating group has been prepared by reacting resorcinol with iminodiacetic acid in the presence of formaldehyde at a molar ratio of about 1:1:6. The material is highly selective for the simultaneous recovery of both cesium and strontium from aqueous alkaline solutions, such as, aqueous alkaline nuclear wate solutions. The organic resins are condensation polymers of resorcinol and formaldehyde with attached chelating groups. The column performance of the resins compares favorably with that of commercially available resins for either cesium or strontium removal. By combining Cs/sup +/ and Sr/sup 2 +/ removal in the same bed, the resins allow significant reduction of the size and complexity of facilities for processing nuclear waste.

  4. Methods of urolith removal.

    PubMed

    Langston, Cathy; Gisselman, Kelly; Palma, Douglas; McCue, John

    2010-06-01

    Multiple techniques exist to remove uroliths from each section of the urinary tract. Minimally invasive methods for removing lower urinary tract stones include voiding urohydropropulsion, retrograde urohydropropulsion followed by dissolution or removal, catheter retrieval, cystoscopic removal, and cystoscopy-assisted laser lithotripsy and surgery. Laparoscopic cystotomy is less invasive than surgical cystotomy. Extracorporeal shock wave lithotripsy can be used for nephroliths and ureteroliths. Nephrotomy, pyelotomy, or urethrotomy may be recommended in certain situations. This article discusses each technique and gives guidance for selecting the most appropriate technique for an individual patient. PMID:20949423

  5. OPTIMIZING ARSENIC REMOVAL DURING IRON REMOVAL PROCESSES

    EPA Science Inventory

    The recently promulgated Arsenic rule will require that many new drinking water systems treat their water to remove arsenic. Many groundwaters that have arsenic in their source water also have iron in their water. As a result, arsenic treatment at these sites will most likely b...

  6. Adsorption of a water soluble cationic dye into a cationic Langmuir monolayer

    NASA Astrophysics Data System (ADS)

    Shil, Ashis; Hussain, S. A.; Bhattacharjee, D.

    2015-05-01

    This communication reports the successful adsorption of a water soluble cationic fluorescent dye Rhodamine B (RhB) into a cationic Langmuir monolayer of Octadecylamine (ODA). Anionic nano clay platelets Hectorite played an important role in the process of adsorption. Surface pressure vs. area per molecule (π-A) isotherms were studied to monitor the adsorption process. In-situ fluorescence Imaging Microscopic (FIM) technique was employed to visualize the domain structures formed at the air-water interface. Atomic Force Microscopic (AFM) image of the monolayer Langmuir-Blodgett (LB) films were taken to study the morphology and ultrastructure of the film. Detailed spectroscopic investigations were carried out on the mono- and multilayer Langmuir-Blodgett (LB) films.

  7. Applying the polarity rapid assessment method to characterize nitrosamine precursors and to understand their removal by drinking water treatment processes.

    PubMed

    Liao, Xiaobin; Bei, Er; Li, Shixiang; Ouyang, Yueying; Wang, Jun; Chen, Chao; Zhang, Xiaojian; Krasner, Stuart W; Suffet, I H Mel

    2015-12-15

    Some N-nitrosamines (NAs) have been identified as emerging disinfection by-products during water treatment. Thus, it is essential to understand the characteristics of the NA precursors. In this study, the polarity rapid assessment method (PRAM) and the classical resin fractionation method were studied as methods to fractionate the NA precursors during drinking water treatment. The results showed that PRAM has much higher selectivity for NA precursors than the resin approach. The normalized N-nitrosodimethylamine formation potential (NDMA FP) and N-nitrosodiethylamine (NDEA) FP of four resin fractions was at the same level as the average yield of the bulk organic matter whereas that of the cationic fraction by PRAM showed 50 times the average. Thus, the cationic fraction was shown to be the most important NDMA precursor contributor. The PRAM method also helped understand which portions of the NA precursor were removed by different water treatment processes. Activated carbon (AC) adsorption removed over 90% of the non-polar PRAM fraction (that sorbs onto the C18 solid phase extraction [SPE] cartridge) of NDMA and NDEA precursors. Bio-treatment removed 80-90% of the cationic fraction of PRAM (that is retained on the cation exchange SPE cartridge) and 40-60% of the non-cationic fractions. Ozonation removed 50-60% of the non-polar PRAM fraction of NA precursors and transformed part of them into the polar fraction. Coagulation and sedimentation had very limited removal of various PRAM fractions of NA precursors. PMID:26433007

  8. Does cation break the cyano bond? A critical evaluation of nitrile-cation interaction.

    PubMed

    Woi, Pei Meng; Bakar, Maizathul Akmam A; Rosli, Ahmad Nazmi; Lee, Vannajan Sanghiran; Ahmad, Mohd Rais; Zain, Sharifuddin; Alias, Yatimah

    2014-05-01

    DFT and G4 results reveal that cations display the following trends in imparting its positive charge to acrylonitrile; H⁺ > Li⁺ > Na⁺ > K⁺ for group I and Be²⁺ > Mg²⁺ > Ca²⁺ for group II. Solvation by water molecules and interaction with cation make the cyano bond more polarized and exhibits ketene-imine character. Bond order in nitrile-cation complexes has been predicted based on the s character of the covalent bond orbitals. Mulliken, CHELPG, and NPA charges are in good agreement in predicting positive charge buildup and GIAO nuclear deshileding on C1. G4 enthalpies show that Mg²⁺ is more strongly bound to acrylonitrile than to acetonitrile by 3 kcal mol⁻¹, and the proton affinity of the former is higher by 0.8 kcal mol⁻¹. G4 enthalpies of reductions support prior experimental observation that metalated conjugated nitriles show enhanced reactivity toward weak nucleophiles to afford Michael addition products. PMID:24770548

  9. Molecular simulation study on Hofmeister cations and the aqueous solubility of benzene.

    PubMed

    Ganguly, Pritam; Hajari, Timir; van der Vegt, Nico F A

    2014-05-22

    We study the ion-specific salting-out process of benzene in aqueous alkali chloride solutions using Kirkwood-Buff (KB) theory of solutions and molecular dynamics simulations with different empirical force field models for the ions and benzene. Despite inaccuracies in the force fields, the simulations indicate that the decrease of the Setchenow salting-out coefficient for the series NaCl > KCl > RbCl > CsCl is determined by direct benzene-cation correlations, with the larger cations showing weak interactions with benzene. Although ion-specific aqueous solubilities of benzene may be affected by indirect ion-ion, ion-water, and water-water correlations, too, these correlations are found to be unimportant, with little to no effect on the Setchenow salting-out coefficients of the various salts. We further considered LiCl, which is experimentally known to be a weaker salting-out agent than NaCl and KCl and, therefore, ranks at an unusual position within the Hofmeister cation series. The simulations indicate that hydrated Li(+) ions can take part of the benzene hydration shell while the other cations are repelled by it. This causes weaker Li(+) exclusion around the solute and a resulting, weaker salting-out propensity of LiCl compared to that of the other salts. Removing benzene-water and benzene-salt electrostatic interactions in the simulations does not affect this mechanism, which may therefore also explain the smaller effect of LiCl, as compared to that of NaCl or KCl, on aqueous solvation and hydrophobic interaction of nonpolar molecules. PMID:24792435

  10. 4-Spiro[2.n]alkyl cations and their rearrangements.

    PubMed

    Prakash, G K; Fung, A P; Olah, G A; Rawdah, T N

    1987-08-01

    A series of 4-spiro[2.n]alkanols, where n = 3-7, were ionized in either FSO3H x SbF5/SO2ClF or SbF5/SO2ClF at -78 degrees C and -130 degrees C. The resulting solutions were studied by 13C NMR spectroscopy over the temperature range of -130 degrees C to -10 degrees C. The 4-spiro[2.5]octanol gave the expected static 4-spiro[2.5]octyl cation, which can be considered as a long-lived secondary cyclohexyl cation stabilized by an adjacent spirocyclopropane ring. The same spiro[2.5]octyl cation was also obtained by ionization of isomeric bicyclo[4.2.0]octan-1-ol and bicyclo[4.1.0]heptyl-1-methanol. The static spiro[2.5]-octyl cation was found to rearrange to the equilibrating 1-bicyclo[3.3.0]octyl cation above -10 degrees C. On the other hand, the 4-spiro[2.4]heptanol gave the rearranged 1-methylcyclohexenyl cation. The spiro[2.6]nonanol gave directly the equilibrating 1-bicyclo[4.3.0]nonyl cation. The other 4-spiro[2.n]-alkanols (n = 3 and 7) gave unidentifiable polymeric products. The ionization of 3-spirocyclopropyl-2-norbornanol yields only the rearranged 2-methylbicyclo[3.2.1]oct-3-ene-2-yl cation. PMID:3474642

  11. 4-Spiro[2.n]alkyl cations and their rearrangements.

    PubMed Central

    Prakash, G K; Fung, A P; Olah, G A; Rawdah, T N

    1987-01-01

    A series of 4-spiro[2.n]alkanols, where n = 3-7, were ionized in either FSO3H x SbF5/SO2ClF or SbF5/SO2ClF at -78 degrees C and -130 degrees C. The resulting solutions were studied by 13C NMR spectroscopy over the temperature range of -130 degrees C to -10 degrees C. The 4-spiro[2.5]octanol gave the expected static 4-spiro[2.5]octyl cation, which can be considered as a long-lived secondary cyclohexyl cation stabilized by an adjacent spirocyclopropane ring. The same spiro[2.5]octyl cation was also obtained by ionization of isomeric bicyclo[4.2.0]octan-1-ol and bicyclo[4.1.0]heptyl-1-methanol. The static spiro[2.5]-octyl cation was found to rearrange to the equilibrating 1-bicyclo[3.3.0]octyl cation above -10 degrees C. On the other hand, the 4-spiro[2.4]heptanol gave the rearranged 1-methylcyclohexenyl cation. The spiro[2.6]nonanol gave directly the equilibrating 1-bicyclo[4.3.0]nonyl cation. The other 4-spiro[2.n]-alkanols (n = 3 and 7) gave unidentifiable polymeric products. The ionization of 3-spirocyclopropyl-2-norbornanol yields only the rearranged 2-methylbicyclo[3.2.1]oct-3-ene-2-yl cation. PMID:3474642

  12. Cation Effects on Nitrate Mobility in an Unsaturated Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transient, unsaturated, horizontal column experiments were carried out with a computer controlled syringe pump for the purpose of assessing counterion (accompanying cation) effects on nitrate (NO3-) mobility in unsaturated soil. A loam soil with calcium dominated cation exchange sites was used in al...

  13. Photodynamic Inactivation of Bacteria and Biofilms Using Cationic Bacteriochlorins

    NASA Astrophysics Data System (ADS)

    Meerovich, G. A.; Tiganova, I. G.; Makarova, E. A.; Meerovich, I. G.; Romanova Ju., M.; Tolordova, E. R.; Alekseeva, N. V.; Stepanova, T. V.; Yu, Koloskova; Luk'anets, E. A.; Krivospitskaya, N. V.; Sipailo, I. P.; Baikova, T. V.; Loschenov, V. B.; Gonchukov, S. A.

    2016-02-01

    This work is devoted to the study of two new synthetic bacteriochlorins with four and eight cationic substitutes as the photosensitizers in the photodynamic process. The spectral and antibacterial properties of these photosensitizers in saline solution were investigated. It is shown, that the aggregation ability decreases and the antibacterial efficiency grows as the cationic substitute number increases.

  14. ADSORPTION OF ORGANIC CATIONS TO SOILS AND SUBSURFACE MATERIALS

    EPA Science Inventory

    A study of the fundamentals of adsorption of amphiphilic organic cations on natural and pristine surfaces was conducted to elucidate (i) the factors that influence the extent of adsorption and (ii) indirect effects of adsorption of organic cations: the competitive adsorption of o...

  15. High capacity nickel battery material doped with alkali metal cations

    DOEpatents

    Jackovitz, John F.; Pantier, Earl A.

    1982-05-18

    A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

  16. CATION EXCHANGE METHOD FOR THE RECOVERY OF PROTACTINIUM

    DOEpatents

    Studier, M.H.; Sullivan, J.C.

    1959-07-14

    A cation exchange prccess is described for separating protactinium values from thorium values whereby they are initially adsorbed together from an aqueous 0.1 to 2 N hydrochloric acid on a cation exchange resin in a column. Then selectively eluting the thorium by an ammonium sulfate solution and subsequently eluting the protactinium by an oxalate solution.

  17. Effects of cationic hydroxyethyl cellulose on glucose tolerance and obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cholestyramine is a cationic polymer prescribed to lower cholesterol in humans. We investigated the effects of cationic hydroxyethyl cellulose (cHEC) on weight loss and metabolic disorders associated with obesity using both hamster and diet-induced obese mouse models. Golden Syrian hamsters and ob...

  18. Membrane stress increases cation permeability in red cells.

    PubMed

    Johnson, R M

    1994-11-01

    The human red cell is known to increase its cation permeability when deformed by mechanical forces. Light-scattering measurements were used to quantitate the cell deformation, as ellipticity under shear. Permeability to sodium and potassium was not proportional to the cell deformation. An ellipticity of 0.75 was required to increase the permeability of the membrane to cations, and flux thereafter increased rapidly as the limits of cell extension were reached. Induction of membrane curvature by chemical agents also did not increase cation permeability. These results indicate that membrane deformation per se does not increase permeability, and that membrane tension is the effector for increased cation permeability. This may be relevant to some cation permeabilities observed by patch clamping. PMID:7858123

  19. Cationic liposomes as non-viral vector for RNA delivery in cancer immunotherapy.

    PubMed

    Vitor, Micaela T; Bergami-Santos, Patrícia C; Barbuto, José A M; de la Torre, Lucimara G

    2013-08-01

    This review presents the current status in the use of liposomes as non-viral vector for nucleic acid delivery in cancer immunotherapy. Currently, cancer treatment uses surgery, radiotherapy and/or chemotherapy. The search for new strategies to improve the efficiency of conventional treatments is a challenge, and biological therapy has emerged as a promising technique. Immunotherapy is a branch of biological therapy that uses the body's immune system to detect and destroy cancer cells. One immunotherapy approach is the activation of T lymphocytes from cancer patients by dendritic cells (DCs) loaded with tumor antigens. Among different antigens, mRNA coding the tumor antigens is advantageous due to its capability to be amplified from small amounts of tumor tissue, its safety because it is easily degraded without integrating into the host genome, and it does not need to cross the nuclear barrier to exert its biological activity. Nanotechnology is an approach to deliver tumor antigens into DCs. Specially; we review the use of nanoliposomes in the field of cancer therapy because cationic liposomes can be used as non-viral vectors for mRNA delivery. Aside from the promise of liposomes, the development of scalable processes and facilities to the use this individualized therapy is still a challenge. Thus, we also present the recent techniques used for liposome production. In this context, the integration between technological knowledge in the production of cationic liposomes and immunotherapy using mRNA may contribute to the development of new strategies for cancer therapy. PMID:23286512

  20. A simple method to prepare magnetic modified beer yeast and its application for cationic dye adsorption.

    PubMed

    Yu, Jun-Xia; Wang, Li-Yan; Chi, Ru-An; Zhang, Yue-Fei; Xu, Zhi-Gao; Guo, Jia

    2013-01-01

    The purpose of this research is to use a simple method to prepare magnetic modified biomass with good adsorption performances for cationic ions. The magnetic modified biomass was prepared by two steps: (1) preparation of pyromellitic dianhydride (PMDA) modified biomass in N, N-dimethylacetamide solution and (2) preparation of magnetic PMDA modified biomass by a situ co-precipitation method under the assistance of ultrasound irradiation in ammonia water. The adsorption potential of the as-prepared magnetic modified biomass was analyzed by using cationic dyes: methylene blue and basic magenta as model dyes. Optical micrograph and x-ray diffraction analyses showed that Fe(3)O(4) particles were precipitated on the modified biomass surface. The as-prepared biosorbent could be recycled easily by using an applied magnetic field. Titration analysis showed that the total concentration of the functional groups on the magnetic PMDA modified biomass was calculated to be 0.75 mmol g(-1) by using the first derivative method. The adsorption capacities (q(m)) of the magnetic PMDA modified biomass for methylene blue and basic magenta were 609.0 and 520.9 mg g(-1), respectively, according to the Langmuir equation. Kinetics experiment showed that adsorption could be completed within 150 min for both dyes. The desorption experiment showed that the magnetic sorbent could be used repeatedly after regeneration. The as-prepared magnetic modified sorbent had a potential in the dyeing industry wastewater treatment. PMID:22529003

  1. Controlling the actuation properties of MXene paper electrodes upon cation intercalation

    DOE PAGESBeta

    Come, Jeremy E.; Black, Jennifer M.; Naguib, Michael; Lukatskaya, Maria R.; Beidaghi, Majid; Wesolowski, David J.; Gogotsi, Yury; Rondinone, Adam J.; Balke, Nina; Kalinin, Sergei V.

    2015-08-05

    Atomic force microscopy was used to monitor the macroscopic deformation in a delaminated Ti₃C₂ paper electrode in-situ, during charge/discharge in a variety of aqueous electrolytes to examine the effect of the cation intercalation on the electrochemical behavior and mechanical response. The results show a strong dependence of the electrode deformation on cation size and charge. The electrode undergoes a large contraction during Li⁺, Na⁺ or Mg²⁺ intercalation, differentiating the Ti₃C₂ paper from conventional electrodes where redox intercalation of ions (e.g. Li⁺) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. This feature may explain the excellent rate performancemore » and cyclability reported for MXenes. We also demonstrated that the variation of the electromechanical contraction can be easily adjusted by electrolyte exchange, and shows interesting characteristics for the design of actuators based on 2D metal carbides.« less

  2. Maximizing gene delivery efficiencies of cationic helical polypeptides via balanced membrane penetration and cellular targeting

    PubMed Central

    Zheng, Nan; Yin, Lichen; Song, Ziyuan; Ma, Liang; Tang, Haoyu; Gabrielson, Nathan P.; Lu, Hua; Cheng, Jianjun

    2014-01-01

    The application of non-viral gene delivery vectors is often accompanied with the poor correlation between transfection efficiency and the safety profiles of vectors: vectors with high transfection efficiencies often suffer from high toxicities, making it unlikely to improve their efficiencies by increasing the DNA dosage. In the current study, we developed a ternary complex system which consisted of a highly membrane-active cationic helical polypeptide (PVBLG-8), a low-toxic, membrane-inactive cationic helical polypeptide (PVBLG-7) capable of mediating mannose receptor targeting, and DNA. The PVBLG-7 moiety notably enhanced the cellular uptake and transfection efficiency of PVBLG-8 in a variety of mannose receptor-expressing cell types (HeLa, COS-7, and Raw 264.7), while it did not compromise the membrane permeability of PVBLG-8 or bring additional cytotoxicities. Because of the simplicity and adjustability of the self-assembly approach, optimal formulations of the ternary complexes with a proper balance between membrane activity and targeting capability were easily identified in each specific cell type. The optimal ternary complexes displayed desired cell tolerability and markedly outperformed the PVBLG-8/DNA binary complexes as well as commercial reagent Lipofectamine™ 2000 in terms of transfection efficiency. This study therefore provides an effective and facile strategy to overcome the efficiency-toxicity poor correlation of non-viral vectors, which contributes insights into the design strategy of effective and safe non-viral gene delivery vectors. PMID:24211080

  3. Device for removing blackheads

    DOEpatents

    Berkovich, Tamara

    1995-03-07

    A device for removing blackheads from pores in the skin having a elongated handle with a spoon shaped portion mounted on one end thereof, the spoon having multiple small holes piercing therethrough. Also covered is method for using the device to remove blackheads.

  4. Use of chitosan and chitosan-derivatives to remove arsenic from aqueous solutions--a mini review.

    PubMed

    Pontoni, Ludovico; Fabbricino, Massimiliano

    2012-07-15

    Arsenic removal has become a relevant concern due to the final confirmation of its behaviour as chronic human carcinogen, corresponding to an ever-increasing contamination of water, soil and crops in many parts of the world. Developing easily accessible removal strategies is therefore a primary environmental matter. Chitosan and chitosan derivatives show good adsorption performances against arsenic removal and are considered low cost products, easily obtainable. This review provides a summary of recent advances of the application of these compounds in the area of sorption sciences for arsenate and arsenite removal from water, focusing on equilibrium and kinetic mechanisms. PMID:22537862

  5. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  6. Relative energies, structures, vibrational frequencies, and electronic spectra of pyrylium cation, an oxygen-containing carbocyclic ring isoelectronic with benzene, and its isomers

    NASA Astrophysics Data System (ADS)

    Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

    2013-11-01

    We have studied relative energies, structures, rotational, vibrational, and electronic spectra of the pyrylium cation, an oxygen-containing six-membered carbocyclic ring, and its six isomers, using ab initio quantum chemical methods. Isoelectronic with benzene, the pyrylium cation has a benzenoid structure and is the global minimum on the singlet potential energy surface of C5H5O+. The second lowest energy isomer, the furfuryl cation, has a five membered backbone akin to a sugar, and is only 16 kcal mol-1 above the global minimum computed using coupled cluster theory with singles, doubles, and perturbative triple excitations (CCSD(T)) with the correlation consistent cc-pVTZ basis set. Other isomers are 25, 26, 37, 60, and 65 kcal mol-1 above the global minimum, respectively, at the same level of theory. Lower level methods such as density functional theory (B3LYP) and second order Møller-Plesset perturbation theory performed well when tested against the CCSD(T) results. The pyrylium and furfuryl cations, although separated by only 16 kcal mol-1, are not easily interconverted, as multiple bonds must be broken and formed, and the existence of more than one transition state is likely. Additionally, we have also investigated the asymptotes for the barrierless ion-molecule association of molecules known to exist in the interstellar medium that may lead to formation of the pyrylium cation.

  7. ESR study of the aziridine and azetidine radical cations: evidence for the C. C ring-opened aziridine radical cation

    SciTech Connect

    Qin, X.Z.; Williams, F.

    1986-05-22

    The radical cations from aziridine and azetidine have been characterized by ESR spectroscopy following their generation in the solid state by ..gamma.. irradiation of dilute solutions of the parent compounds in the CFCl/sub 3/ matrix at 77 K. The ESR parameters of the azetidine radical cation are typical of those for nitrogen-centered amine radical cations such as Me/sub 2/NH*/sup +/. On the other hand, the radical cation formed from aziridine has very different ESR parameters that compare closely to those for the isoelectronic C...C ring-opened form of the oxirane radical cation and the allyl radical. The radical cation formed from azetidine is therefore assigned a ring-closed structure with the unpaired electron in a 2p/sub z/ orbital on nitrogen perpendicular to the ring plane, whereas the cation from aziridine is an allylic C...C ring-opened planar isomer with the unpaired electron in a nonbonding ..pi.. orbital centered mainly on the two end carbon atoms. The neutral 1-aziridinyl and 1-azetidinyl radicals have been detected as radical products following the ..gamma.. irradiation of the parent compounds in the CFCl/sub 2/CF/sub 2/Cl and CF/sub 3/CCl/sub 3/ matrices. In particular, the 1-azetidinyl radical is produced cleanly from the azetidine radical cation in the CFCl/sub 2/CF/sub 2/Cl matrix at ca. 100 K.

  8. Precipitation process for the removal of technetium values from nuclear waste solutions

    DOEpatents

    Walker, D.D.; Ebra, M.A.

    1985-11-21

    High efficiency removal of techetium values from a nuclear waste stream is achieved by addition to the waste stream of a precipitant contributing tetraphenylphosphonium cation, such that a substantial portion of the technetium values are precipitated as an insoluble pertechnetate salt.

  9. Water Adsorption on Free Cobalt Cluster Cations.

    PubMed

    Kiawi, Denis M; Bakker, Joost M; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L B F M

    2015-11-01

    Cationic cobalt clusters complexed with water Con(+)-H2O (n = 6-20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200-1700 cm(-1) spectral range. All spectra exhibit a resonance close to the 1595 cm(-1) frequency of the free water bending vibration, indicating that the water molecule remains intact upon adsorption. For n = 6, the frequency of this band is blue-shifted, but it gradually converges to the free water value with increasing cluster size. In the lower-frequency range (200-650 cm(-1)) the spectra contain several bands which show a very regular frequency evolution, suggesting that the exact cluster geometry has little effect on the water-surface interaction. Density functional theory (DFT) calculations are carried out at the OPBE/TZP level for three representative sizes (n = 6, 9, 13) and indicate that the vibrations responsible for the resonances correspond to bending and torsional modes between the cluster and water moieties. The potential energy surfaces describing these interactions are very shallow, making the calculated harmonic frequencies and IR intensities very sensitive to small geometrical perturbations. We conclude that harmonic frequency calculations on (local) minima structures provide insufficient information for these types of cluster complexes and need to be complemented with calculations that provide a more extensive sampling of the potential energy surface. PMID:26447780

  10. Therapeutic potential of cationic steroid antibacterials.

    PubMed

    Salmi, Chanaz; Brunel, Jean M

    2007-08-01

    Antibiotics were one of the great health successes of the 20th century. Antibiotics, both naturally derived and synthetic, have resulted in huge decreases in both morbidity and mortality from bacterial infections. As a consequence, the 'antibiotic age' has changed public expectations about the results of infectious disease. However, this has led to high levels of inappropriate prescribing, where antibiotics may be administered to fulfil patient expectations rather than for clinical benefit. Along with unwise uses in agriculture and elsewhere, this has contributed to recent rises in numbers of antibiotic-resistant bacteria. As a result, many commentators have described this as the end of the antibiotic age and the term 'superbug' has entered the common vocabulary for multi-drug-resistant bacteria such as vancomycin-resistant Enterococcus, multi-drug-resistant Staphylococcus aureus and multi-drug-resistant Pseudomonas aeruginosa. In this context, an attractive approach for the development of antibacterial agents is the use of a new class of cationic steroidal compounds mimicking polymyxin activities. The permeabilization properties of these agents of the outer membranes of Gram-negative bacteria are reported in this review, as well as a discussion of literature results. PMID:17685865

  11. Is Iodate a Strongly Hydrated Cation?

    SciTech Connect

    Baer, Marcel D.; Pham, Thai V.; Fulton, John L.; Schenter, Gregory K.; Balasubramanian, Mahalingam; Mundy, Christopher J.

    2011-10-06

    We show, through a combination of density function theory based molecular dynamics simulations (DFTMD) and experimental x-ray absorption fine structure spectroscopy (XAFS) studies, that the iodate ion (IO3-) is a zwitterion in solution. The local region adjoining the I atom is sufficiently electropositive that three hydrating waters are oriented with their O’s atoms directly interacting with the iodine atom at an I-OH2O distance of 2.95 Å. This is the orientation of water hydrating a cation. Further, approximately 2-3 water molecules hydrate each O of IO3 - through a single H atom in an orientation of the water that is expected for an anion at an IOH2O distance of 3.85 Å. We predict that this structure persists, although to a much lesser degree, for BrO3 -, and ClO3 -. This type of local microstructure profoundly affects the behavior of the "anion" at interfaces and how it interacts with other ionic species in solution.

  12. Antiendotoxin activity of cationic peptide antimicrobial agents.

    PubMed Central

    Gough, M; Hancock, R E; Kelly, N M

    1996-01-01

    The endotoxin from gram-negative bacteria consists of a molecule lipopolysaccharide (LPS) which can be shed by bacteria during antimicrobial therapy. A resulting syndrome, endotoxic shock, is a leading cause of death in the developed world. Thus, there is great interest in the development of antimicrobial agents which can reverse rather than promote sepsis, especially given the recent disappointing clinical performance of antiendotoxin therapies. We describe here two small cationic peptides, MBI-27 and MBI-28, which have both antiendotoxic and antibacterial activities in vitro and in vivo in animal models. We had previously demonstrated that these peptides bind to LPS with an affinity equivalent to that of polymyxin B. Consistent with this, the peptides blocked the ability of LPS and intact cells to induce the endotoxic shock mediator, tumor necrosis factor (TNF), upon incubation with the RAW 264.7 murine macrophage cell line. MBI-28 was equivalent to polymyxin B in its ability to block LPS induction of TNF by this cell line, even when added 60 min after the TNF stimulus. Furthermore, MBI-28 offered significant protection in a galactosamine-sensitized mouse model of lethal endotoxic shock. This protection correlated with the ability of MBI-28 to reduce LPS-induced circulating TNF by nearly 90% in this mouse model. Both MBI-27 and MBI-28 demonstrated antibacterial activity against gram-negative bacteria in vitro and in vivo against Pseudomonas aeruginosa infections in neutropenic mice. PMID:8945527

  13. A phosphotyrosine switch regulates organic cation transporters

    PubMed Central

    Sprowl, Jason A.; Ong, Su Sien; Gibson, Alice A.; Hu, Shuiying; Du, Guoqing; Lin, Wenwei; Li, Lie; Bharill, Shashank; Ness, Rachel A.; Stecula, Adrian; Offer, Steven M.; Diasio, Robert B.; Nies, Anne T.; Schwab, Matthias; Cavaletti, Guido; Schlatter, Eberhard; Ciarimboli, Giuliano; Schellens, Jan H. M.; Isacoff, Ehud Y.; Sali, Andrej; Chen, Taosheng; Baker, Sharyn D.; Sparreboom, Alex; Pabla, Navjotsingh

    2016-01-01

    Membrane transporters are key determinants of therapeutic outcomes. They regulate systemic and cellular drug levels influencing efficacy as well as toxicities. Here we report a unique phosphorylation-dependent interaction between drug transporters and tyrosine kinase inhibitors (TKIs), which has uncovered widespread phosphotyrosine-mediated regulation of drug transporters. We initially found that organic cation transporters (OCTs), uptake carriers of metformin and oxaliplatin, were inhibited by several clinically used TKIs. Mechanistic studies showed that these TKIs inhibit the Src family kinase Yes1, which was found to be essential for OCT2 tyrosine phosphorylation and function. Yes1 inhibition in vivo diminished OCT2 activity, significantly mitigating oxaliplatin-induced acute sensory neuropathy. Along with OCT2, other SLC-family drug transporters are potentially part of an extensive ‘transporter-phosphoproteome' with unique susceptibility to TKIs. On the basis of these findings we propose that TKIs, an important and rapidly expanding class of therapeutics, can functionally modulate pharmacologically important proteins by inhibiting protein kinases essential for their post-translational regulation. PMID:26979622

  14. Cation Defects and Conductivity in Transparent Oxides

    SciTech Connect

    Exarhos, Gregory J.; Windisch, Charles F.; Ferris, Kim F.; Owings, Robert R.

    2007-10-24

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused in part by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  15. Cationic Noncovalent Interactions: Energetics and Periodic Trends.

    PubMed

    Rodgers, M T; Armentrout, P B

    2016-05-11

    In this review, noncovalent interactions of ions with neutral molecules are discussed. After defining the scope of the article, which excludes anionic and most protonated systems, methods associated with measuring thermodynamic information for such systems are briefly recounted. An extensive set of tables detailing available thermodynamic information for the noncovalent interactions of metal cations with a host of ligands is provided. Ligands include small molecules (H2, NH3, CO, CS, H2O, CH3CN, and others), organic ligands (O- and N-donors, crown ethers and related molecules, MALDI matrix molecules), π-ligands (alkenes, alkynes, benzene, and substituted benzenes), miscellaneous inorganic ligands, and biological systems (amino acids, peptides, sugars, nucleobases, nucleosides, and nucleotides). Hydration of metalated biological systems is also included along with selected proton-based systems: 18-crown-6 polyether with protonated peptides and base-pairing energies of nucleobases. In all cases, the literature thermochemistry is evaluated and, in many cases, reanchored or adjusted to 0 K bond dissociation energies. Trends in these values are discussed and related to a variety of simple molecular concepts. PMID:26953819

  16. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    PubMed

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja

    2016-07-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. PMID:27333030

  17. A Road More Easily Traveled

    ERIC Educational Resources Information Center

    Stanly, Pat

    2009-01-01

    Rough patches occur at both ends of the education pipeline, as students enter community colleges and move on to work or enrollment in four-year institutions. Career pathways--sequences of coherent, articulated, and rigorous career and academic courses that lead to an industry-recognized certificate or a college degree--are a promising approach to…

  18. Easily forgotten: elderly female prisoners.

    PubMed

    Handtke, Violet; Bretschneider, Wiebke; Elger, Bernice; Wangmo, Tenzin

    2015-01-01

    Women form a growing minority within the worldwide prison population and have special needs and distinct characteristics. Within this group exists a smaller sub-group: elderly female prisoners (EFPs) who require tailored social and health interventions that address their unique needs. Data collected from two prisons in Switzerland housing women prisoners were studied. Overall 26 medical records were analyzed, 13 from EFPs (50+ years) and for comparison 13 from young female prisoners (YFPs, 49 years and younger). Additionally, five semi-structured interviews were conducted with EFPs. Using the layer model of vulnerability, three layers of vulnerability were identified: the "prisoner" layer; followed by the layer of "woman"; both of which are encompassed by the layer of "old age." The analysis of these layers resulted in three main areas where EFPs are particularly vulnerable: their status of "double-minority," health and health-care access, and their social relations. Prison administration and policy-makers need to be more sensitive to gender and age related issues in order to remedy these vulnerabilities. PMID:25661851

  19. Some easily analyzable convolutional codes

    NASA Technical Reports Server (NTRS)

    Mceliece, R.; Dolinar, S.; Pollara, F.; Vantilborg, H.

    1989-01-01

    Convolutional codes have played and will play a key role in the downlink telemetry systems on many NASA deep-space probes, including Voyager, Magellan, and Galileo. One of the chief difficulties associated with the use of convolutional codes, however, is the notorious difficulty of analyzing them. Given a convolutional code as specified, say, by its generator polynomials, it is no easy matter to say how well that code will perform on a given noisy channel. The usual first step in such an analysis is to computer the code's free distance; this can be done with an algorithm whose complexity is exponential in the code's constraint length. The second step is often to calculate the transfer function in one, two, or three variables, or at least a few terms in its power series expansion. This step is quite hard, and for many codes of relatively short constraint lengths, it can be intractable. However, a large class of convolutional codes were discovered for which the free distance can be computed by inspection, and for which there is a closed-form expression for the three-variable transfer function. Although for large constraint lengths, these codes have relatively low rates, they are nevertheless interesting and potentially useful. Furthermore, the ideas developed here to analyze these specialized codes may well extend to a much larger class.

  20. Removal of broken hardware.

    PubMed

    Hak, David J; McElvany, Matthew

    2008-02-01

    Despite advances in metallurgy, fatigue failure of hardware is common when a fracture fails to heal. Revision procedures can be difficult, usually requiring removal of intact or broken hardware. Several different methods may need to be attempted to successfully remove intact or broken hardware. Broken intramedullary nail cross-locking screws may be advanced out by impacting with a Steinmann pin. Broken open-section (Küntscher type) intramedullary nails may be removed using a hook. Closed-section cannulated intramedullary nails require additional techniques, such as the use of guidewires or commercially available extraction tools. Removal of broken solid nails requires use of a commercial ratchet grip extractor or a bone window to directly impact the broken segment. Screw extractors, trephines, and extraction bolts are useful for removing stripped or broken screws. Cold-welded screws and plates can complicate removal of locked implants and require the use of carbide drills or high-speed metal cutting tools. Hardware removal can be a time-consuming process, and no single technique is uniformly successful. PMID:18252842

  1. Preoperative hair removal.

    PubMed

    Hamilton, H W; Hamilton, K R; Lone, F J

    1977-05-01

    This study compares the efficiency, safety and cost of hair removal before surgery, with a safety razor, an electric clipper and a depilatory. It was found that both the razor and the clipper damaged the surface of the skin, while the depilatory caused a mild lymphocytic reaction in the upper dermis. The depilatory was expensive and may cause sensitivity reactions in a few individuals, but was found to be the easiest and most efficient method of removing hair. It was concluded that if hair has to be removed a depilatory is the agent of choice. PMID:870157

  2. Three degradation pathways of 1-octyl-3-methylimidazolium cation by activated sludge from wastewater treatment process.

    PubMed

    Cho, Chul-Woong; Pham, Thi Phuong Thuy; Kim, Sok; Song, Myung-Hee; Chung, Yun-Jo; Yun, Yeoung-Sang

    2016-03-01

    The biodegradability and degradation pathways of 1-octyl-3-methylimidazolium cation [OMIM](+) by microbial community of wastewater treatment plant in Jeonju city, Korea were investigated. It was found that [OMIM](+) could be easily degraded by the microbial community. New degradation products and pathways of [OMIM](+) were identified, which are partially different from previous results (Green Chem. 2008, 10, 214-224). For the analysis of the degradation pathways and intermediates, the mass peaks observed in the range m/z of 50-300 were screened by using a tandem mass spectrometer (MS), and their fragmentation patterns were investigated by MS/MS. Surprisingly, we found three different degradation pathways of [OMIM](+), which were separated according to the initially oxidized position i.e. middle of the long alkyl chain, end of the long alkyl chain, and end of the short alkyl chain. The degradation pathways showed that the long and short alkyl chains of [OMIM](+) gradually degraded by repeating oxidation and carbon release. The results presented here shows that [OMIM](+) can be easily biodegraded through three different degradation pathways in wastewater treatment plants. PMID:26748207

  3. Penetrating cations enhance uncoupling activity of anionic protonophores in mitochondria.

    PubMed

    Antonenko, Yuri N; Khailova, Ljudmila S; Knorre, Dmitry A; Markova, Olga V; Rokitskaya, Tatyana I; Ilyasova, Tatyana M; Severina, Inna I; Kotova, Elena A; Karavaeva, Yulia E; Prikhodko, Anastasia S; Severin, Fedor F; Skulachev, Vladimir P

    2013-01-01

    Protonophorous uncouplers causing a partial decrease in mitochondrial membrane potential are promising candidates for therapeutic applications. Here we showed that hydrophobic penetrating cations specifically targeted to mitochondria in a membrane potential-driven fashion increased proton-translocating activity of the anionic uncouplers 2,4-dinitrophenol (DNP) and carbonylcyanide-p-trifluorophenylhydrazone (FCCP). In planar bilayer lipid membranes (BLM) separating two compartments with different pH values, DNP-mediated diffusion potential of H(+) ions was enhanced in the presence of dodecyltriphenylphosphonium cation (C12TPP). The mitochondria-targeted penetrating cations strongly increased DNP- and carbonylcyanide m-chlorophenylhydrazone (CCCP)-mediated steady-state current through BLM when a transmembrane electrical potential difference was applied. Carboxyfluorescein efflux from liposomes initiated by the plastoquinone-containing penetrating cation SkQ1 was inhibited by both DNP and FCCP. Formation of complexes between the cation and CCCP was observed spectophotometrically. In contrast to the less hydrophobic tetraphenylphosphonium cation (TPP), SkQ1 and C12TPP promoted the uncoupling action of DNP and FCCP on isolated mitochondria. C12TPP and FCCP exhibited a synergistic effect decreasing the membrane potential of mitochondria in yeast cells. The stimulating action of penetrating cations on the protonophore-mediated uncoupling is assumed to be useful for medical applications of low (non-toxic) concentrations of protonophores. PMID:23626747

  4. Penetrating Cations Enhance Uncoupling Activity of Anionic Protonophores in Mitochondria

    PubMed Central

    Antonenko, Yuri N.; Khailova, Ljudmila S.; Knorre, Dmitry A.; Markova, Olga V.; Rokitskaya, Tatyana I.; Ilyasova, Tatyana M.; Severina, Inna I.; Kotova, Elena A.; Karavaeva, Yulia E.; Prikhodko, Anastasia S.; Severin, Fedor F.; Skulachev, Vladimir P.

    2013-01-01

    Protonophorous uncouplers causing a partial decrease in mitochondrial membrane potential are promising candidates for therapeutic applications. Here we showed that hydrophobic penetrating cations specifically targeted to mitochondria in a membrane potential-driven fashion increased proton-translocating activity of the anionic uncouplers 2,4-dinitrophenol (DNP) and carbonylcyanide-p-trifluorophenylhydrazone (FCCP). In planar bilayer lipid membranes (BLM) separating two compartments with different pH values, DNP-mediated diffusion potential of H+ ions was enhanced in the presence of dodecyltriphenylphosphonium cation (C12TPP). The mitochondria-targeted penetrating cations strongly increased DNP- and carbonylcyanide m-chlorophenylhydrazone (CCCP)-mediated steady-state current through BLM when a transmembrane electrical potential difference was applied. Carboxyfluorescein efflux from liposomes initiated by the plastoquinone-containing penetrating cation SkQ1 was inhibited by both DNP and FCCP. Formation of complexes between the cation and CCCP was observed spectophotometrically. In contrast to the less hydrophobic tetraphenylphosphonium cation (TPP), SkQ1 and C12TPP promoted the uncoupling action of DNP and FCCP on isolated mitochondria. C12TPP and FCCP exhibited a synergistic effect decreasing the membrane potential of mitochondria in yeast cells. The stimulating action of penetrating cations on the protonophore-mediated uncoupling is assumed to be useful for medical applications of low (non-toxic) concentrations of protonophores. PMID:23626747

  5. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    PubMed

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-01

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media. PMID:25569300

  6. Lipopolythioureas: a new non-cationic system for gene transfer.

    PubMed

    Leblond, Jeanne; Mignet, Nathalie; Largeau, Céline; Spanedda, Maria-Vittoria; Seguin, Johanne; Scherman, Daniel; Herscovici, Jean

    2007-01-01

    A DNA-transfection protocol has been developed that makes use of thiourea non-cationic synthetic lipid, N-[1,3-bis(carbamothioylamino)propan-2-yl]-2-(dialkycarbamoylmethoxy)acetamide. It was found that these new compounds could be formulated without helper lipid and that the N-decanoyl and N-lauryl derivatives transfected B16 cells in the presence of serum with an efficiency at the same level as cationic lipids, under identical conditions. In vivo transfection using intratumoral injection was also investigated. It was found that compounds 18c and 19 showed an efficiency of the same magnitude as naked DNA and cationic lipid. PMID:17373770

  7. Anion, cation, and zwitterion selectivity of phospholemman channel molecules.

    PubMed Central

    Kowdley, G C; Ackerman, S J; Chen, Z; Szabo, G; Jones, L R; Moorman, J R

    1997-01-01

    Phospholemman (PLM), a 72-amino acid membrane protein with a single transmembrane domain, forms taurine-selective ion channels in lipid bilayers. Because taurine forms zwitterions, a taurine-selective channel might have binding sites for both anions and cations. Here we show that PLM channels indeed allow fluxes of both cations and anions, making instantaneous and voltage-dependent transitions among conformations with drastically different ion selectivity characteristics. This surprising and novel ion channel behavior offers a molecular explanation for selective taurine flux across cell membranes and may explain why molecules in the phospholemman family can induce cation- or anion-selective conductances when expressed in Xenopus oocytes. PMID:8994599

  8. Pyridine radical cation and its fluorine substituted derivatives

    USGS Publications Warehouse

    Bondybey, V.E.; English, J.H.; Shiley, R.H.

    1982-01-01

    The spectra and relaxation of the pyridine cation and of several of its fluorinated derivatives are studied in low temperature Ne matrices. The ions are generated by direct photoionization of the parent compounds. Of the compounds studied, laser induced → and → fluorescence is observed only for the 2, 6‐difluoropyridine cation. The analysis of the spectrum indicates that the ion is planar both in the and states. The large variety in the spectroscopic and relaxation behavior of fluoropyridine radical cations is explained in terms of their electronic structure and of the differential shifts of the individual electronic states caused by the fluorine substitution.

  9. Increased Vascular permeability produced by human platelet granule cationic extract

    PubMed Central

    Nachman, Ralph L.; Weksler, Babette; Ferris, Barbara

    1970-01-01

    A cationic protein extract obtained from isolated human platelet granules increased vascular permeability in mouse and rabbit skin. The permeability-enhancing effect was not inhibited by soybean trypsin and pancreatic trypsin inhibitor, methylsergide maleate, carboxypeptidase B, and C[unk]1 inactivator. Permeability-enhancing activity was blocked by prior treatment of challenged animals with antihistamine. The nondializable relatively heat-stable cationic granule protein extract possessed potent mastocytolytic activity. The experiments described suggest that human platelets exert a permeability-enhancing effect by lysosomal release of cationic proteins which cause histamine release from adjacent tissue mast cells. Images PMID:4391559

  10. Electrostatic charge confinement using bulky tetraoctylammonium cation and four anions

    NASA Astrophysics Data System (ADS)

    Andreeva, Nadezhda A.; Chaban, Vitaly V.

    2016-04-01

    Thanks to large opposite electrostatic charges, cations and anions establish strong ionic bonds. However, applications of ionic systems - electrolytes, gas capture, solubilization, etc. - benefit from weaker non-covalent bonds. The common approaches are addition of cosolvents and delocalization of electron charge density via functionalization of ions. We report fine tuning of closest-approach distances, effective radii, and cation geometry by different anions using the semi-empirical molecular dynamics simulations. We found that long fatty acid chains employed in the tetraalkylammonium cation are largely inefficient and new substituents must be developed. The reported results foster progress of task-specific ionic liquids.

  11. Aryl sulfoxide radical cations. Generation, spectral properties, and theoretical calculations.

    PubMed

    Baciocchi, Enrico; Del Giacco, Tiziana; Gerini, Maria Francesca; Lanzalunga, Osvaldo

    2006-08-17

    Aromatic sulfoxide radical cations have been generated by pulse radiolysis and laser flash photolysis techniques. In water (pulse radiolysis) the radical cations showed an intense absorption band in the UV region (ca. 300 nm) and a broad less intense band in the visible region (from 500 to 1000 nm) whose position depends on the nature of the ring substituent. At very low pulse energy, the radical cations decayed by first-order kinetics, the decay rate increasing as the pH increases. It is suggested that the decay involves a nucleophilic attack of H(2)O or OH(-) (in basic solutions) to the positively charged sulfur atom to give the radical ArSO(OH)CH(3)(*). By sensitized [N-methylquinolinium tetrafluoborate (NMQ(+))] laser flash photolysis (LFP) the aromatic sulfoxide radical cations were generated in acetonitrile. In these experiments, however, only the band of the radical cation in the visible region could be observed, the UV band being covered by the UV absorption of NMQ(+). The lambda(max) values of the bands in the visible region resulted almost identical to those observed in water for the same radical cations. In the LFP experiments the sulfoxide radical cations decayed by second-order kinetics at a diffusion-controlled rate, and the decay is attributed to the back electron transfer between the radical cation and NMQ(*). DFT calculations were also carried out for a number of 4-X ring substituted (X = H, Me, Br, OMe, CN) aromatic sulfoxide radical cations (and their neutral parents). In all radical cations, the conformation with the S-O bond almost coplanar with the aromatic ring is the only one corresponding to the energy minimum. The maximum of energy corresponds to the conformation where the S-O bond is perpendicular to the aromatic ring. The rotational energy barriers are not very high, ranging from 3.9 to 6.9 kcal/mol. In all radical cations, the major fraction of charge and spin density is localized on the SOMe group. However, a substantial delocalization

  12. Radical cations of sulfides and disulfides: An ESR study

    SciTech Connect

    Bonazzola, L.; Michaut, J.P.; Roncin, J.

    1985-09-15

    Exposure of dilute solutions of dimethylsulfide, methanethiol, tetrahydrothiophene, terbutyl and diterbutyl-sulfides, dimethyl-disulfide, and diterbutyldisulfide, in freon at 77 K to /sup 60/Co ..gamma.. rays gave the corresponding cations. From the reported ESR spectra, g tensors were obtained. It was found that both sulfide and disulfide cations exhibit the same g tensor: (g/sub max/ = 2.034 +- 0.002, g/sub int/ = 2.017 +- 0.001, g/sub min/ = 2.001 +- 0.005). From this result it has been shown that the disulfide cation is planar. This finding was supported by fully optimized geometry ab initio calculations.

  13. Cation exchange capacity of loess and overlying soil in the non-carbonate loess sections, North-Western Croatia

    NASA Astrophysics Data System (ADS)

    Tomašić, Nenad; Kampić, Štefica; Cindrić, Iva Juranović; Pikelj, Kristina; Lučić, Mavro; Mavrić, Danijela; Vučetić, Tajana

    2013-12-01

    The adsorption properties in terms of cation exchange capacity and their relation to the soil and sediment constituents (clay minerals, Fe-, Mn-, and Al-oxyhydroxides, organic matter) were investigated in loess, soil-loess transition zone, and soil at four loess-soil sections in North-Western Croatia. Cation exchange capacity of the bulk samples, the samples after oxalate extraction of Fe, Mn and Al, and after removal of organic matter, as well as of the separated clay fraction, was determined using copper ethylenediamine. Cation exchange capacity (pH˜7) of the bulk samples ranges from 5 to 12 cmol c /kg in soil, from 7 to 15 cmol c /kg in the soil-loess transition zone, and from 12 to 20 cmol c /kg in loess. Generally, CEC values increase with depth. Oxalate extraction of Fe, Mn, and Al, and removal of organic matter cause a CEC decrease of 3-38% and 8-55%, respectively, proving a considerable influence of these constituents to the bulk CEC values. In the separated clay fraction (<2 μm) CEC values are up to several times higher relative to those in the bulk samples. The measured CEC values of the bulk samples generally correspond to the clay mineral content identified. Also, a slight increase in muscovite/illite content with depth and the vermiculite occurrence in the loess horizon are concomitant with the CEC increase in deeper horizons, irrespective of the sample pretreatment.

  14. Cation exchange capacity of loess and overlying soil in the non-carbonate loess sections, North-Western Croatia

    NASA Astrophysics Data System (ADS)

    Tomašić, Nenad; Kampić, Štefica; Cindrić, Iva; Pikelj, Kristina; Lučić, Mavro; Mavrić, Danijela; Vučetić, Tajana

    2013-12-01

    The adsorption properties in terms of cation exchange capacity and their relation to the soil and sediment constituents (clay minerals, Fe-, Mn-, and Al-oxyhydroxides, organic matter) were investigated in loess, soil-loess transition zone, and soil at four loess-soil sections in North-Western Croatia. Cation exchange capacity of the bulk samples, the samples after oxalate extraction of Fe, Mn and Al, and after removal of organic matter, as well as of the separated clay fraction, was determined using copper ethylenediamine. Cation exchange capacity (pH˜7) of the bulk samples ranges from 5 to 12 cmolc/kg in soil, from 7 to 15 cmolc/kg in the soil-loess transition zone, and from 12 to 20 cmolc/kg in loess. Generally, CEC values increase with depth. Oxalate extraction of Fe, Mn, and Al, and removal of organic matter cause a CEC decrease of 3-38% and 8-55%, respectively, proving a considerable influence of these constituents to the bulk CEC values. In the separated clay fraction (<2 μm) CEC values are up to several times higher relative to those in the bulk samples. The measured CEC values of the bulk samples generally correspond to the clay mineral content identified. Also, a slight increase in muscovite/illite content with depth and the vermiculite occurrence in the loess horizon are concomitant with the CEC increase in deeper horizons, irrespective of the sample pretreatment.

  15. Paint removal using lasers

    NASA Astrophysics Data System (ADS)

    Liu, Katherine; Garmire, Elsa

    1995-07-01

    Experiments to investigate the potential for practical laser graffiti-removal systems are reported. A universal engineering curve for the time needed for removal of paint from nonconductive substrates that was valid over a range of 107 in intensity was measured with a variety of lasers. Comparable times were measured for conductive substrates, when pulses shorter than the thermal conduction times were used. Analysis suggests that Q-switched Nd:YAG lasers may be the most efficient means for removing graffiti and other unwanted paint. An 1-m2 area of paint 14 mu m thick can be removed in approximately 10 min with a 50-Hz laser system of 15-W average power.

  16. Paint removal using lasers.

    PubMed

    Liu, K; Garmire, E

    1995-07-20

    Experiments to investigate the potential for practical laser graffiti-removal systems are reported. A universal engineering curve for the time needed for removal of paint from nonconductive substrates that was valid over a range of 10(7) in intensity was measured with a variety of lasers. Comparable times were measured for conductive substrates, when pulses shorter than the thermal conduction times were used. Analysis suggests that Q-switched Nd:YAG lasers may be the most efficient means for removing graffiti and other unwanted paint. An 1-m(2) area of paint 14 µm thick can be removed in approximately 10 min with a 50-Hz laser system of 15-W average power. PMID:21052275

  17. Laparoscopic Spleen Removal (Splenectomy)

    MedlinePlus

    ... Login Laparoscopic Spleen Removal (Splenectomy) Patient Information from SAGES Download PDF Version Find a SAGES Surgeon What ... 2017 Meeting Information Healthy Sooner: Patient Information Contact SAGES Society of American Gastrointestinal and Endoscopic Surgeons 11300 ...

  18. Thyroid gland removal - discharge

    MedlinePlus

    ... surgery to remove part or all of your thyroid gland. This operation is called thyroidectomy . You probably ... in just a few weeks. If you had thyroid cancer, you may need to have radioactive iodine ...

  19. Gallbladder removal - open

    MedlinePlus

    ... and kidney tests) Chest x-ray or electrocardiogram ( EKG ), for some patients Several x-rays of the ... Procedure You may stay in the hospital for 3 to 5 days after open gallbladder removal. During ...

  20. Hardware removal - extremity

    MedlinePlus

    Surgeons use hardware such as pins, plates, or screws to help fix a broken bone or to correct an abnormality in ... of pain or other problems related to the hardware, you may have surgery to remove the hardware. ...

  1. Removing Hair Safely

    MedlinePlus

    ... the skin, and into the hair follicle. An electric current travels down the wire and destroys the hair ... a period of time. Tweezer epilators also use electric current to remove hair. The tweezers grasp the hair ...

  2. Laparoscopic Adrenal Gland Removal

    MedlinePlus

    ... adrenal tumors that appear malignant. What are the Advantages of Laparoscopic Adrenal Gland Removal? In the past, ... of procedure and the patients overall condition. Common advantages are: Less postoperative pain Shorter hospital stay Quicker ...

  3. Hardware removal - extremity

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/007644.htm Hardware removal - extremity To use the sharing features on this page, please enable JavaScript. Surgeons use hardware such as pins, plates, or screws to help ...

  4. Reactor for removing ammonia

    DOEpatents

    Luo, Weifang; Stewart, Kenneth D.

    2009-11-17

    Disclosed is a device for removing trace amounts of ammonia from a stream of gas, particularly hydrogen gas, prepared by a reformation apparatus. The apparatus is used to prevent PEM "poisoning" in a fuel cell receiving the incoming hydrogen stream.

  5. Gallbladder removal - laparoscopic

    MedlinePlus

    ... PA: Elsevier Saunders; 2012:chap 55. Read More Acute cholecystitis Chronic cholecystitis Gallbladder removal - open Gallstones Patient Instructions Bland diet Surgical wound care - open When you have nausea and vomiting ...

  6. BIOLOGICAL PHOSPHORUS REMOVAL

    EPA Science Inventory

    Three proprietary biological phosphorus removal processes are reviewed. The paper presents the description and development status of these technologies. The paper is a summary of the emerging technology assessment report published by U.S. Environmental Protection Agency in 1984. ...

  7. Asbestos Removal Case History.

    ERIC Educational Resources Information Center

    Haney, Stanley J.

    1986-01-01

    The engineer for a California school district describes the asbestos removal from the ceilings of El Camino High School. Discusses forming a design team, use of consultants, specifications, relations with contractors, and staff notification. (MLF)

  8. Advanced Coating Removal Techniques

    NASA Technical Reports Server (NTRS)

    Seibert, Jon

    2006-01-01

    An important step in the repair and protection against corrosion damage is the safe removal of the oxidation and protective coatings without further damaging the integrity of the substrate. Two such methods that are proving to be safe and effective in this task are liquid nitrogen and laser removal operations. Laser technology used for the removal of protective coatings is currently being researched and implemented in various areas of the aerospace industry. Delivering thousands of focused energy pulses, the laser ablates the coating surface by heating and dissolving the material applied to the substrate. The metal substrate will reflect the laser and redirect the energy to any remaining protective coating, thus preventing any collateral damage the substrate may suffer throughout the process. Liquid nitrogen jets are comparable to blasting with an ultra high-pressure water jet but without the residual liquid that requires collection and removal .As the liquid nitrogen reaches the surface it is transformed into gaseous nitrogen and reenters the atmosphere without any contamination to surrounding hardware. These innovative technologies simplify corrosion repair by eliminating hazardous chemicals and repetitive manual labor from the coating removal process. One very significant advantage is the reduction of particulate contamination exposure to personnel. With the removal of coatings adjacent to sensitive flight hardware, a benefit of each technique for the space program is that no contamination such as beads, water, or sanding residue is left behind when the job is finished. One primary concern is the safe removal of coatings from thin aluminum honeycomb face sheet. NASA recently conducted thermal testing on liquid nitrogen systems and found that no damage occurred on 1/6", aluminum substrates. Wright Patterson Air Force Base in conjunction with Boeing and NASA is currently testing the laser remOval technique for process qualification. Other applications of liquid

  9. Absorbable microparticulate cation exchanger for immunotherapeutic delivery.

    PubMed

    Shalaby, Waleed S W; Yeh, Heidi; Woo, Edward; Corbett, Joel T; Gray, Heidi; June, Carl H; Shalaby, Shalaby W

    2004-05-15

    An absorbable microparticulate cation exchanger was synthesized as a versatile carrier for biologically active proteins. In this work, acid-terminated polyglycolide (or polyglycolic acid) microparticulates (PG-MP) were surface modified for either sustained release of cytokines or as a platform for immunomodulation. The intended goal was to achieve in situ recruitment/maturation of dendritic cells and activation of T cells for tumor immunotherapy. PG-MP were prepared with a volume weighted mean diameter of 7.02 micro (range: 2.09-14.58 micro). Accessible carboxylic acid groups were determined to be 0.3 mmol/g with a corresponding zeta potential of -21.87 mV in phosphate-buffered saline. Under low magnification, scanning electron microscopy (SEM) revealed a highly textured surface due to processing from repetitive jet milling. However, a moderately porous architecture was noted at higher magnification. Electron spectroscopy for chemical analysis was used to characterize the PG-MP surface before and after adsorption of human granulocyte-macrophage colony stimulating factor (GM-CSF). Adsorption of GM-CSF on PG-MP (PG-GMCSF) resulted in a modest increase in the surface atomic concentration of nitrogen (0.97%). Pretreating the surface with poly-L-lysine (PG/Lys-GMCSF) prior to adding GM-CSF produced a nearly threefold increase in the surface nitrogen concentration (4.20% compared to 1.47%). This manipulation not only increased loading content, but also prolonged the release of GM-CSF released from 6 days to 26 days. ESCA on the post-release PG-MP samples (PG-GMCSF and PG/Lys-GMCSF) revealed a similar residual surface nitrogen concentration (2.26% vs. 2.35%). The observation was consistent with irreversibly adsorbed GM-CSF. It is postulated that irreversibly bound GM-CSF is released over time as a function of microparticulate degradation. Biological activity of released GM-CSF was confirmed by the proliferation of a GM-CSF-dependent cell line (TF-1) in the presence of

  10. Dissociative Recombination Dynamics of the Ozone Cation

    SciTech Connect

    Zhaunerchyk, Vitali; Geppert, W.; sterdahl, F.; Larsson, Mats; Thomas, R. D.; Bahati Musafiri, Eric; Bannister, Mark E; Fogle, Mark R.; Vane, C Randy

    2008-02-01

    The dissociative recombination of the ozone cation has been studied at the heavy-ion storage ring CRYRING. The total cross section and branching fractions have been measured. The cross section from {approx}0eV to 0.2 eV follows a nearly E{sup -1} dependence, which was theoretically predicted to be a characteristic of the direct dissociative recombination mechanism. The thermal rate coefficient has been deduced from the cross section to be 7.37x10{sup -7}(T/300){sup -0.55}cm{sup 3}s{sup -1}. The branching fraction analysis carried out at {approx}0eV interaction energy has shown a strong propensity (94%) to dissociate through the three-body channel. Due to the overwhelming dominance of this channel it has been investigated in more detail. Of the six energetically available three-body pathways only three are significantly populated, such that the production of O(S1) is highly unfavored and all atomic oxygen fragments are predominantly formed in P3 and D1 states. Analysis of the breakup geometries has been performed by means of the Dalitz plot. It is observed that the molecules dissociating through the O(P3)+O(P3)+O(P3) and O(P3)+O(P3)+O(D1) channels have an open linear geometry where the cleavage of two valence bonds occurs preferentially in unison, while the O(P3)+O(D1)+O(D1) breakup might proceed partly through a sequential mechanism.

  11. Anaerobic toxicity of cationic silver nanoparticles.

    PubMed

    Gitipour, Alireza; Thiel, Stephen W; Scheckel, Kirk G; Tolaymat, Thabet

    2016-07-01

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag(+) under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10-15nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5mgL(-1), the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100mgL(-1) as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag(+). Both citrate and PVP-AgNPs did not exhibit toxicity at the 100mgL(-1) as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. PMID:27016684

  12. Novel cationic polyelectrolyte coatings for capillary electrophoresis.

    PubMed

    Duša, Filip; Witos, Joanna; Karjalainen, Erno; Viitala, Tapani; Tenhu, Heikki; Wiedmer, Susanne K

    2016-01-01

    The use of bare fused silica capillary in CE can sometimes be inconvenient due to undesirable effects including adsorption of sample or instability of the EOF. This can often be avoided by coating the inner surface of the capillary. In this work, we present and characterize two novel polyelectrolyte coatings (PECs) poly(2-(methacryloyloxy)ethyl trimethylammonium iodide) (PMOTAI) and poly(3-methyl-1-(4-vinylbenzyl)-imidazolium chloride) (PIL-1) for CE. The coated capillaries were studied using a series of aqueous buffers of varying pH, ionic strength, and composition. Our results show that the investigated polyelectrolytes are usable as semi-permanent (physically adsorbed) coatings with at least five runs stability before a short coating regeneration is necessary. Both PECs showed a considerably decreased stability at pH 11.0. The EOF was higher using Good's buffers than with sodium phosphate buffer at the same pH and ionic strength. The thickness of the PEC layers studied by quartz crystal microbalance was 0.83 and 0.52 nm for PMOTAI and PIL-1, respectively. The hydrophobicity of the PEC layers was determined by analysis of a homologous series of alkyl benzoates and expressed as the distribution constants. Our result demonstrates that both PECs had comparable hydrophobicity, which enabled separation of compounds with log Po/w > 2. The ability to separate cationic drugs was shown with β-blockers, compounds often misused in doping. Both coatings were also able to separate hydrolysis products of the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate at highly acidic conditions, where bare fused silica capillaries failed to accomplish the separation. PMID:26464098

  13. Recognition of metal cations by biological systems.

    PubMed

    Truter, M R

    1975-11-01

    Recognition of metal cations by biological systems can be compared with the geochemical criteria for isomorphous replacement. Biological systems are more highly selective and much more rapid. Methods of maintaining an optimum concentration, including storage and transfer for the essential trace elements, copper and iron, used in some organisms are in part reproducible by coordination chemists while other features have not been reporduced in models. Poisoning can result from a foreign metal taking part in a reaction irreversibly so that the recognition site or molecule is not released. For major nutrients, sodium, potassium, magnesium and calcium, there are similarities to the trace metals in selective uptake but differences qualitatively and quantitatively in biological activity. Compounds selective for potassium replace all the solvation sphere with a symmetrical arrangement of oxygen atoms; those selective for sodium give an asymmetrical environment with retention of a solvent molecule. Experiments with naturally occurring antibiotics and synthetic model compounds have shown that flexibility is an important feature of selectivity and that for transfer or carrier properties there is an optimum (as opposed to a maximum) metal-ligand stability constant. Thallium is taken up instead of potassium and will activate some enzymes; it is suggested that the poisonous characteristics arise because the thallium ion may bind more strongly than potassium to part of a site and then fail to bind additional atoms as required for the biological activity. Criteria for the design of selective complexing agents are given with indications of those which might transfer more than one metal at once. PMID:1815

  14. Laser hair removal pearls.

    PubMed

    Tierney, Emily P; Goldberg, David J

    2008-03-01

    A number of lasers and light devices are now available for the treatment of unwanted hair. The goal of laser hair removal is to damage stem cells in the bulge of the follicle through the targeting of melanin, the endogenous chromophore for laser and light devices utilized to remove hair. The competing chromophores in the skin and hair, oxyhemoglobin and water, have a decreased absorption between 690 nm and 1000 nm, thus making this an ideal range for laser and light sources. Pearls of laser hair removal are presented in this review, focusing on four areas of recent development: 1 treatment of blond, white and gray hair; 2 paradoxical hypertrichosis; 3 laser hair removal in children; and 4 comparison of lasers and IPL. Laser and light-based technologies to remove hair represents one of the most exciting areas where discoveries by dermatologists have led to novel treatment approaches. It is likely that in the next decade, continued advancements in this field will bring us closer to the development of a more permanent and painless form of hair removal. PMID:18330794

  15. Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.

    PubMed

    Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K

    2014-09-15

    Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations. PMID:24934266

  16. Diverse functions of cationic Mn(III) substituted N-pyridylporphyrins, known as SOD mimics

    PubMed Central

    Batinic-Haberle, Ines; Rajic, Zrinka; Tovmasyan, Artak; Ye, Xiaodong; Leong, Kam W.; Dewhirst, Mark W.; Vujaskovic, Zeljko; Benov, Ludmil; Spasojevic, Ivan

    2011-01-01

    Oxidative stress, a redox imbalance between the endogenous reactive species and antioxidant systems, is common to numerous pathological conditions such as cancer, central nervous system injuries, radiation injury, diabetes etc. Therefore, compounds able to reduce oxidative stress have been actively sought for over 3 decades. Superoxide is the major species involved in oxidative stress either in its own right or through its progeny, such as ONOO−, H2O2, ·OH, CO3·−, and ·NO2. Therefore, the very first compounds developed in the late 1970-ies were the superoxide dismutase (SOD) mimics. Thus far the most potent mimics have been the cationic meso Mn(III) N-substituted pyridylporphyrins and N,N′-disubstituted imidazolylporphyrins (MnPs), some of them with kcat(O2·−) similar to the kcat of SOD enzymes. Most frequently studied are ortho isomers MnTE-2-PyP5+, MnTnHex-2-PyP5+, and MnTDE-2-ImP5+. The ability to disproportionate O2·− parallels their ability to remove the other major oxidizing species, peroxynitrite, ONOO−. The same structural feature that gives rise to the high kcat (O2·−) and kred (ONOO−), allows MnPs to strongly impact the activation of the redox-sensitive transcription factors, HIF-1α, NF-κB, AP-1, and SP-1, and therefore modify the excessive inflammatory and immune responses. Coupling with cellular reductants and other redox-active endogenous proteins seems to be involved in the actions of Mn porphyrins. While hydrophilic analogues, such as MnTE-2-PyP5+ and MnTDE-2-ImP5+ are potent in numerous animal models of diseases, the lipophilic analogues were developed to cross blood brain barrier and target central nervous system and critical cellular compartment, mitochondria. The modification of its structure, aimed to preserve the SOD-like potency and lipophilicity, and diminish the toxicity, has presently been pursued. The pulmonary radioprotection by MnTnHex-2-PyP5+ was the first efficacy study performed successfully with non

  17. Effect of MnSO4 on the chromium removal from the leather industry wastewater.

    PubMed

    Ozdemir, C; Karatas, M; Dursun, S; Argun, M E; Dogan, S

    2005-04-01

    Chromium (VI) is one of the heavy metals in water and wastewater that has the most toxic characteristic. Consequently, it is dangerous for human and environmental health. Various methods are used for removal of the chromium from wastewater, and new methods have been developed in recent years. Recent studies and investigations on the removal of environmental pollution selected methods that were economical, of optimum efficiently and could be carried out easily. In this study, the removal of Cr6+ in the leather industry wastewater is investigated using MnSO4 that was used easily and economically. Experimental studies are performed in two phases. In the first phase, the optimum MnSO4 dose for removal of Cr6+ was determined. In the second phase, the optimum pH was studied. About 96% removal of chromium was launched with 530 mg l(-1) MnSO4 dose at pH value 9 in the wastewater sample. PMID:15906491

  18. [Cation exchanges during the process of Cd(2+) absorption by Alfalfa in aqueous solutions].

    PubMed

    Li, Yue-Peng; Yin, Hua; Ye, Jin-Shao; Peng, Hua; Qin, Hua-Ming; Long, Yan; He, Bao-Yan; Zhang, Na; Tong, Yao; Peng, Su-Fen

    2011-11-01

    A hydroponic experiment was conducted to investigate the cation exchanges during the process of Cd2+ absorption by Alfalfa in aqueous solution. The absorption efficiency of Alfalfa plants with 0-10 mg x L(-1) Cd2+ treatments, changes of Na+, K+, Mg2+, Ca2+ and NH4(+) concentration, and the variation of pH values at different absorption time (0, 1, 2, 4, 8, 12, 24 and 72 h) were studied separately. The multiple linear regressions between Cd2+ absorption and cation variation were analyzed. The results indicated that when Cd2+ concentrations were 0.1, 1, 5, 10 mg x L(-1), the absorption efficiencies of Cd2+ by Alfalfa after 72 h were 85.86%, 52.14%, 15.97% and 7.81%. Cation exchange was involved in the removal of Cd2+ by Alfalfa in aqueous solution. Except for NH4(+), the concentrations of cationic metals Na+, K+, Mg2+ and Ca2+ in aqueous solution increased over time, which increased 11.30% - 61.72%, 21.44% - 98.73%, 24.09% - 8.90% and 37.04% - 191.96%, respectively. Kinetic studies illuminated that the release of Na+, K+, Mg2+ and Ca2+ by Alfalfa in Cd2+ solution with initial concentrations of 0, 0. 1, 1, 5, 10 mg x L(-1) best fitted pseudo-second-order equation,while the NH4(+) release fitted this model when Cd2+ concentrations were 1, 5, 10 mg x L(-1). The gradual decrease of pH during adsorption of Cd2+ by Alfalfa was observed. As the competition ion of Cd2+, H+ might affect the capacity of Alfalfa root system to absorb Cd2+. The ternary linear equation results demonstrated that the content of Cd2+ absorption by Alfalfa strongly related with the release of Ca2+, Mg2+, Na+. And this exchange mainly occurred among Cd2+ and divalent cations. PMID:22295633

  19. Cation-Cation Interactions in [(UO2)2(OH)n](4-n) Complexes

    SciTech Connect

    Odoh, Samuel O.; Govind, Niranjan; Schreckenbach, Georg; De Jong, Wibe A.

    2013-10-07

    The structures and bonding of gas-phase [(UO2)2(OH)n]4-n (n=2-6) complexes have been studied using density functional theory (DFT), MP2 and CCSD(T) methods with particular emphasis on ground state structures featuring cation-cation interactions (CCIs) between the uranyl groups. An interesting trend is observed in the stabilities of members of this series of complexes. The structures of [(UO2)2(OH)2]2+, [(UO2)2(OH)4] and [(UO2)2(OH)6]2- featuring CCIs are found at higher energies (by 3-20 kcal/mol) in comparison to their conventional μ2-dihydroxo structures. In contrast, the CCI structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- are respectively almost degenerate with and lower in energy than the structures with the μ2-dihydroxo format. The origin of this trend lies in the ‘symmetry’-based need to balance the coordination numbers and effective atomic charges of each uranium center. The calculated IR vibrational frequencies provide signature probes that can be used in differentiating the lowenergy structures and in experimentally confirming the existence of the structures featuring CCIs. Analysis of the bonding in the structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- shows that the CCIs and bridging hydroxo between the dioxo-uranium units are mainly electrostatic in nature.

  20. Hydrophobic Catalysts For Removal Of NOx From Flue Gases

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.; Voecks, Gerald E.

    1995-01-01

    Improved catalysts for removal of nitrogen oxides (NO and NO2) from combustion flue gases formulated as composites of vanadium pentoxide in carbon molecular sieves. Promotes highly efficient selective catalytic reduction of NOx at relatively low temperatures while not being adversely affected by presence of water vapor and sulfur oxide gases in flue gas. Apparatus utilizing catalyst of this type easily integrated into exhaust stream of power plant to remove nitrogen oxides, generated in combustion of fossil fuels and contribute to formation of acid rain and photochemical smog.

  1. Reduction by monovalent zinc, cadmium, and nickel cations

    NASA Technical Reports Server (NTRS)

    Meyerstein, D.; Mulac, W. A.

    1969-01-01

    Understanding of chemical properties of monovalent transition metal cations in aqueous solutions was obtained by a study of kinetics of reduction of different inorganic substrates by zinc, cadmium, and nickel.

  2. Investigation of Fragmentation of Tryptophan Nitrogen Radical Cation

    NASA Astrophysics Data System (ADS)

    Piatkivskyi, Andrii; Happ, Marshall; Lau, Justin Kai-Chi; Siu, K. W. Michael; Hopkinson, Alan C.; Ryzhov, Victor

    2015-08-01

    This work describes investigation of the fragmentation mechanism of tryptophan N-indolyl radical cation, H3N+-TrpN• ( m/ z 204) studied via DFT calculations and several gas-phase experimental techniques. The main fragment ion at m/ z 131, shown to be a mixture of up to four isomers including 3-methylindole (3MI) π-radical cation, was found to undergo further loss of an H atom to yield one of the two isomeric m/ z 130 ions. 3-Methylindole radical cation generated independently (via CID of [CuII(terpy)3MI]•2+) displayed gas-phase reactivity partially similar to that of the m/ z 131 fragment, further confirming our proposed mechanism. CID of deuterated tryptophan N-indolyl radical cation ( m/ z 208) suggested that up to six H atoms are involved in the pathway to formation of the m/ z 131 ion, consistent with hydrogen atom scrambling during CID of protonated Trp.

  3. Study on cationic photopolymerization reaction of epoxy polysiloxane

    NASA Astrophysics Data System (ADS)

    Sun, F.; Jiang, S. L.; Liu, J.

    2007-11-01

    The effects of epoxy monomers, concentration of photoinitiator and radical photoinitiators on the photosensitive properties of cationic phopolymerization system with a novel epoxy polysiloxane oligomer (CEPS) were investigated via a gel yield method. The results showed that among the tested epoxy monomers, the reactivity of ERL-4221 with cycloaliphatic epoxy groups was the highest. The optimum concentration of diaryldiodonium salt (SR-1012) was determined as 4-5 wt.%. Increasing the amounts of ERL-4221 in the CEPS cationic photopolymerization system, UV-curing rate increased. Radical photoinitiators with ArC dbnd O structure possessed sensitization capacity to the cationic photoinitiator SR-1012. The photosensitivity of the CEPS system could be up to 165 mJ/cm 2. Adding a small amount of IPA and BP could greatly improve the photosensitivity of CEPS cationic photosensitive system. The optimal quantity of isopropanol added to the system was not more than 2 wt.%.

  4. Infrared spectroscopy of mass-selected metal carbonyl cations

    NASA Astrophysics Data System (ADS)

    Ricks, A. M.; Reed, Z. E.; Duncan, M. A.

    2011-04-01

    Metal carbonyl cations of the form M(CO)n+ are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom "tagged" analogs, M(CO)n(RG)m+, are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of "non-classical" carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V +, Nb + and Ta +), while uranium cations provide an example of an eight-coordinate carbonyl.

  5. Cationic RAFT polymerization using ppm concentrations of organic acid.

    PubMed

    Uchiyama, Mineto; Satoh, Kotaro; Kamigaito, Masami

    2015-02-01

    A metal-free, cationic, reversible addition-fragmentation chain-transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10(5) and narrow molecular-weight distributions (Mw /Mn <1.1). This "living" or controlled cationic polymerization is applicable to various electron-rich monomers including vinyl ethers, p-methoxystyrene, and even p-hydroxystyrene that possesses an unprotected phenol group. A transformation from cationic to radical RAFT polymerization enables the synthesis of block copolymers between cationically and radically polymerizable monomers, such as vinyl ether and vinyl acetate or methyl acrylate. PMID:25511364

  6. DFT study on the cycloreversion of thietane radical cations.

    PubMed

    Domingo, Luis R; Pérez-Ruiz, Raúl; Argüello, Juan E; Miranda, Miguel A

    2011-06-01

    The molecular mechanism of the cycloreversion (CR) of thietane radical cations has been analyzed in detail at the UB3LYP/6-31G* level of theory. Results have shown that the process takes place via a stepwise mechanism leading to alkenes and thiobenzophenone; alternatively, formal [4+2] cycloadducts are obtained. Thus, the CR of radical cations 1a,b(•+) is initiated by C2-C3 bond breaking, giving common intermediates INa,b. At this stage, two reaction pathways are feasible involving ion molecule complexes IMCa,b (i) or radical cations 4a,b(•+) (ii). Calculations support that 1a(•+) follows reaction pathway ii (leading to the formal [4+2] cycloadducts 5a). By contrast, 1b(•+) follows pathway i, leading to trans-stilbene radical cation (2b(•+)) and thiobenzophenone. PMID:21561127

  7. α-Cationic Arsines: Synthesis, Structure, Reactivity, and Applications.

    PubMed

    Dube, Jonathan W; Zheng, Yiying; Thiel, Walter; Alcarazo, Manuel

    2016-06-01

    A series of structurally differentiated cationic arsines containing imidazolium, cyclopropenium, formamidinium, and pyridinium substituents have been synthesized through short and scalable routes. Evaluation of the donor properties of these compounds by IR spectroscopy and DFT calculations reveals similar σ-electron-releasing abilities for all of them; however, their π-acceptor properties are strongly influenced by the nature of the positively charged group. We describe the coordination chemistry of the newly prepared α-cationic arsines toward different metal centers and their reactivity in the presence of strong oxidants to afford cationic As(V) species. Their unique electronic properties have been exploited in Pt(II) catalysis to develop a new catalyst with remarkable activity in the cycloisomerization of enynes to trisubstituted cyclopropanes. To the best of our knowledge, this is the first report on the use of α-cationic arsine ligands in catalysis. PMID:27214007

  8. The Ziegler—Natta olefin insertion reaction for cationic metals

    NASA Astrophysics Data System (ADS)

    Jensen, Vidar R.; Siegban, Per E. M.

    1993-09-01

    The catalytic Ziegler—Natta polymerization reaction has been studied for a set of metal cations, in order to identify the role of the positive charge on this process. Geometry optimizations have been performed for the reactant metal—methyl systems, the π-coordinated olefin systems, the transition states for the olefin insertion and finally for the product metal—propyl systems. All valence electrons are correlated. The cations selected for this study are the transition metals Zr + and Ti +, the non-transition metals Be +, Mg +, Al + and finally also Si +. The transition metal cations are found to have very low barriers for the insertion, but the lowest barrier is actually found for Be +. The results are discussed in terms of the ionization energies and the accessibility to valence p and d orbitals. Comparisons are made to previous theoretical work on cationic model systems.

  9. Cationically polymerizable monomers derived from renewable sources. Final report

    SciTech Connect

    1995-09-01

    Objective is to use products from plant sources as monomers for direct production of polymers for plastic applications. (Epoxidized triglycerides as renewable monomers in photoinitiated cationic polymerization.) High-volume American agricultural products such as soybean, cotton or linseed oils or forestry products such as lignin and cellulose derived chemicals were targeted for use either directly or with slight modification for producing the plastics. Cationic photopolymerization will be used.

  10. Characterization of the Azirinyl Cation and Its Isomers.

    PubMed

    Kokkila Schumacher, Sara I L; Bera, Partha P; Lee, Timothy J

    2016-03-01

    The azirinyl cation (C2H2N(+)) and its geometrical isomers could be present in the interstellar medium. The C2H2N(+) isomers are, however, difficult to identify in interstellar chemistry because of the lack of high-resolution spectroscopic data from laboratory experiments. Ab initio quantum chemical methods were used to characterize the structures, relative energies, and spectroscopic and physical properties of the low energy isomers of the azirinyl cation. We have employed second-order Møller-Plesset perturbation theory (MP2), second-order Z-averaged perturbation theory (ZAPT2), and coupled cluster theory with singles and doubles with perturbative triples CCSD(T) methods along with large correlation consistent basis sets such as cc-pVTZ, cc-pCVTZ, cc-pVQZ, cc-pCVQZ, and cc-pV5Z. Harmonic vibrational frequencies, dipole moments, rotational constants, and proton affinities for the lowest energy isomers were calculated using the CCSD(T) method. Azirinyl cation, a cyclic isomer, is lowest in energy at all levels of theory employed. Azirinyl cation is followed by the cyanomethyl cation (H2CCN)(+), isocyanomethyl cation (H2CNC)(+), and a quasilinear HCCNH(+) cation, which are 13.8, 17.3, and 21.5 kcal mol(-1) above the cyclic isomer, respectively, at the CCSD(T)/cc-pV5Z level of theory. The lowest three isomers all have C2v symmetry and (1)A1 ground electronic states. The quasilinear HCCNH(+) cation has a Cs symmetry planar structure, and a (3)A″ electronic ground state, unlike what some previous work suggested. PMID:26840658

  11. Mercury release from deforested soils triggered by base cation enrichment.

    PubMed

    Farella, N; Lucotte, M; Davidson, R; Daigle, S

    2006-09-01

    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide. PMID:16781764

  12. Surfactant-modified bentonite clays: preparation, characterization, and atrazine removal.

    PubMed

    Dutta, Anirban; Singh, Neera

    2015-03-01

    Bentonite clay was modified using quaternary ammonium cations, viz. phenyltrimethylammonium (PTMA), hexadecyltrimethylammonium (HDTMA), trioctylmethylammonium (TOMA) [100 % of cation exchange capacity of clay], and stearylkonium (SK) [100 % (SK-I) and 250 % (SK-II) of cation exchange capacity of clay]. The organoclays were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning electron microscopy (SEM). Atrazine adsorption on modified clays was studied using a batch method. Bentonite clay was a poor adsorbent of atrazine as 9.4 % adsorption was observed at 1 μg mL(-1) atrazine concentration. Modification of clay by PTMA cation did not improve atrazine adsorption capacity. However, atrazine adsorption in HDTMA-, TOMA-, and SK-bentonites varied between 49 and 72.4 % and data fitted well to the Freundlich adsorption isotherm (R > 0.96). Adsorption of atrazine in organoclays was nonlinear and slope (1/n) values were <1. The product of Freundlich adsorption constants, K f(1/n) in HDTMA-, TOMA-, and SK-I-bentonites was 239.2, 302.4, and 256.6, respectively, while increasing the SK cation loading in the clay (SK-II) decreased atrazine adsorption [K f(1/n) - 196.4]. Desorption of atrazine from organoclays showed hysteresis and TOMA- and SK-I-bentonites were the best organoclays to retain the adsorbed atrazine. Organoclays showed better atrazine removal from wastewater than an aqueous solution. The synthesized organoclays may find application in soil and water decontamination and as a carrier for atrazine-controlled released formulations. PMID:25273519

  13. Proton Affinities of Cationic Carbone Adducts [AC(PPh3 )2 ](+) (A=Halogen, Hydrogen, Methyl) and Unusual Electronic Structures of the Cations and Dications [AC(H)(PPh3 )2 ](2.).

    PubMed

    Petz, Wolfgang; Kuzu, Istemi; Frenking, Gernot; Andrada, Diego M; Neumüller, Bernhard; Fritz, Maximilian; Münzer, Jörn E

    2016-06-13

    This work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3 )2 ](+) and [BrC(PPh3 )2 ](+) and the protonated dication [FC(H)(PPh3 )2 ](2+) , which are derived from the carbone C(PPh3 )2 . Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3 )2 ](+) and dications [AC(H)(PPh3 )2 ](2+) , where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)(+) ←L (L=PPh3 ), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3 )2 ](+) possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3 )2 ](2+) . The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)(2+) ←L (L=PPh3 ) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon-fluorine bonds in [FC(PPh3 )2 ](+) and [FC(H)(PPh3 )2 ](2+) exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3 )2 and carbodicarbene C(NHC)2 , we expect that analogous compounds [AC(NHC)2 ](+) and [AC(H)(NHC)2 ](2+) with similar features as [AC(PPh3 )2 ](+) and [AC(H)(PPh3 )2 ](2+) can be isolated. PMID:27166027

  14. Cationic polyelectrolyte-stabilized nanoparticles via RAFT aqueous dispersion polymerization.

    PubMed

    Semsarilar, M; Ladmiral, V; Blanazs, A; Armes, S P

    2013-06-18

    We report the synthesis of cationic sterically stabilized diblock copolymer nanoparticles via polymerization-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerization formulation. The cationic steric stabilizer is a macromolecular chain-transfer agent (macro-CTA) based on quaternized poly(2-(dimethylamino)ethyl methacrylate) (PQDMA), and the hydrophobic core-forming block is based on poly(2-hydroxypropyl methacrylate) (PHPMA). The effect of varying synthesis parameters such as the salt concentration, solids content, relative block composition, and cationic charge density has been studied. In the absence of salt, self-assembly is problematic because of the strong repulsion between the highly cationic PQDMA stabilizer chains. However, in the presence of salt this problem can be overcome by reducing the charge density within the coronal stabilizer layer by either (i) statistically copolymerizing QDMA monomer with a nonionic comonomer (e.g., glycerol monomethacrylate, GMA) or (ii) using a binary mixture of a PQDMA macro-CTA and a poly(glycerol monomethacrylate) (PGMA) macro-CTA. These cationic diblock copolymer nanoparticles were analyzed by (1)H NMR spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), and aqueous electrophoresis. NMR studies suggest that the HPMA polymerization is complete within 2 h at 70 °C. Depending on the specific reaction conditions, either spherical, wormlike or vesicular nanoparticles can be prepared with tunable cationic surface charge. PMID:23205729

  15. Photochemical generation, isomerization, and oxygenation of stilbene cation radicals

    SciTech Connect

    Lewis, F.D.; Bedell, A.M.; Dykstra, R.E.; Elbert, J.E. ); Gould, I.R.; Farid, S. )

    1990-10-24

    The cation radicals of cis- and trans-stilbene and several of their ring-substituted derivatives have been generated in solution directly by means of pulsed-laser-induced electron transfer to singlet cyanoanthracenes or indirectly via electron transfer from biphenyl to the singlet cyanoanthracene followed by secondary electron transfer from the stilbenes to the biphenyl cation radical. Transient absorption spectra of the cis- and trans-stilbene cation radicals generated by secondary electron transfer are similar to those previously obtained in 77 K matrices. Quantum yields for radical ion-pair cage escape have been measured for direct electron transfer from the stilbenes to three neutral and one charged singlet acceptor. These values increase as the ion-pair energy increases due to decreased rate constants for radical ion-pair return electron transfer, in accord with the predictions of Marcus theory for highly exergonic electron transfer. Cage-escape efficiencies are larger for trans- vs cis-stilbene cation radicals, possibly due to the greater extent of charge delocalization in the planar trans vs nonpolar cis cation radicals. Cage-escape stilbene cation radicals can initiate a concentration-dependent one way cis- {yields} trans-stilbene isomerization reaction.

  16. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Cations

    NASA Technical Reports Server (NTRS)

    Hudgins, D. M.; Allamandola, L. J.

    1995-01-01

    Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo(e)pyrene, benzo-(ghi)perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d(sub 10), and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo(ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.

  17. Cation-π interactions in lipocalins: structural and functional implications.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Glasgow, Ben J

    2012-04-10

    The cation-π interaction impacts protein folding, structural stability, specificity, and molecular recognition. Cation-π interactions have been overlooked in the lipocalin family. To fill this gap, these interactions were analyzed in the 113 crystal and solution structures from the lipocalin family. The cation-π interactions link previously identified structurally conserved regions and reveal new motifs, which are beyond the reach of a sequence alignment algorithm. Functional and structural significance of the interactions were tested experimentally in human tear lipocalin (TL). TL, a prominent and promiscuous lipocalin, has a key role in lipid binding at the ocular surface. Ligand binding modulation through the loop AB at the "open" end of the barrel has been erroneously attributed solely to electrostatic interactions. Data revealed that the interloop cation-π interaction in the pair Phe28-Lys108 contributes significantly to stabilize the holo-conformation of the loop AB. Numerous energetically significant and conserved cation-π interactions were uncovered in TL and throughout the lipocalin family. Cation-π interactions, such as the highly conserved Trp17-Arg118 pair in TL, were educed in low temperature experiments of mutants with Trp to Tyr substitutions. PMID:22439821

  18. Cation-π Interactions in Lipocalins: Structural and Functional Implications

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Glasgow, Ben J.

    2013-01-01

    The cation-π interaction impacts protein folding, structural stability, specificity, and molecular recognition. Cation-π interactions have been overlooked in the lipocalin family. To fill this gap, these interactions were analyzed in the 113 crystal and solution structures from the lipocalin family. The cation-π interactions link previously identified structurally conserved regions and reveal new motifs, which are beyond the reach of a sequence alignment algorithm. Functional and structural significance of the interactions were tested experimentally in human tear lipocalin (TL). TL, a prominent and promiscuous lipocalin, has a key role in lipid binding at the ocular surface. Ligand binding modulation through the loop AB at the “open” end the barrel has been erroneously attributed solely to electrostatic interactions. Data revealed that the interloop cation-π interaction in the pair Phe28-Lys108 contributes significantly to stabilize the holo-conformation of the loop AB. Numerous energetically significant and conserved cation-π interactions were uncovered in TL and throughout the lipocalin family. Cation-π interactions, such as the highly conserved Trp17-Arg118 pair in TL, were educed in low temperature experiments of mutants with Trp to Tyr substitutions. PMID:22439821

  19. Mechanism for radical cation transport in duplex DNA oligonucleotides.

    PubMed

    Liu, Chu-Sheng; Hernandez, Rigoberto; Schuster, Gary B

    2004-03-10

    We investigated the photoinduced one-electron oxidation of a series of DNA oligomers having a covalently linked anthraquinone group (AQ) and containing [(A)(n)GG](m) or [(T)(n)GG](m) segments. These oligomers have m GG steps, where m = 4 or 6, separated by (A)(n) or (T)(n) segments, where n = 1-7 for the (A)(n) set and 1-5 for the (T)(n) set. Irradiation with UV light that is absorbed by the AQ causes injection of a radical cation into the DNA. The radical cation migrates through the DNA, causing chemical reaction, primarily at GG steps, that leads to strand cleavage after piperidine treatment. The uniform, systematic structure of the DNA oligonucleotides investigated permits the numerical solution of a kinetic scheme that models these reactions. This analysis yields two rate constants, k(hop), for hopping of the radical cation from one site to adjacent sites, and k(trap), for irreversible reaction of the radical cation with H(2)O or O(2). Analysis of these findings indicates that radical cation hopping in these duplex DNA oligomers is a process that occurs on a microsecond time scale. The value of k(hop) depends on the number of base pairs in the (A)(n) and (T)(n) segments in a systematic way. We interpret these results in terms of a thermally activated adiabatic mechanism for radical cation hopping that we identify as phonon-assisted polaron hopping. PMID:14995205

  20. Cation-binding Capacity of Membranes Isolated from Micrococcus lysodeikticus

    PubMed Central

    Cutinelli, C.; Galdiero, F.; Tufano, M. A.

    1969-01-01

    A study was made of H+, Na+, K+, Ca++, and Mg++ binding and ion-exchange properties of the plasma-mesosome membrane system isolated from Micrococcus lysodeikticus strain NCTC 2665. Titration curves were obtained on membranes prepared according to the method of M. R. J. Salton and further exposed to pH 4 for 4 hr (membranes-H). The dissociation coefficients and binding capacities were obtained by applying the mass law equation and the plot of G. Schatchard to the data. The membranes-H possess four kinds of dissociable groups with pK 4.96, 4.18, 3.60, and 3.09, respectively, and a total binding capacity of 0.65 meq/g (dry weight). Potentiometric titrations of cations in the presence and in the absence of membranes-H show that cations (Na+, K+, Ca++, and Mg++) are bound by the dissociated groups of the membrane. The fall in pH value for bivalent cations is greater than that for monovalent cations. Cations of the same valency produce equal diminutions on pH. Furthermore, ion-exchange tests carried out on membranes saturated with Mg++ or Na+ and suspended in a medium containing 45Ca show that the cations are reversibly bound. PMID:5344091

  1. Tunable states of interlayer cations in two-dimensional materials

    SciTech Connect

    Sato, K.; Numata, K.; Dai, W.; Hunger, M.

    2014-03-31

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of {sup 23}Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and {sup 23}Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed.

  2. Complexation Between Cationic Diblock Copolymers and Plasmid DNA

    NASA Astrophysics Data System (ADS)

    Jung, Seyoung; Reineke, Theresa; Lodge, Timothy

    Deoxyribonucleic acids (DNA), as polyanions, can spontaneously bind with polycations to form polyelectrolyte complexes. When the polycation is a diblock copolymer with one cationic block and one uncharged hydrophilic block, the polyelectrolyte complexes formed with plasmid DNA (pDNA) are often colloidally stable, and show great promise in the field of polymeric gene therapy. While the resulting properties (size, stability, and toxicity to biological systems) of the complexes have been studied for numerous cationic diblocks, the fundamentals of the pDNA-diblock binding process have not been extensively investigated. Herein, we report how the cationic block content of a diblock influences the pDNA-diblock interactions. pDNA with 7164 base pairs and poly(2-deoxy-2-methacrylamido glucopyranose)-block-poly(N-(2-aminoethyl) methacrylamide) (PMAG-b-PAEMA) are used as the model pDNA and cationic diblock, respectively. To vary the cationic block content, two PMAG-b-PAEMA copolymers with similar PMAG block lengths but distinct PAEMA block lengths and a PAEMA homopolymer are utilized. We show that the enthalpy change from pDNA-diblock interactions is dependent on the cationic diblock composition, and is closely associated with both the binding strength and the pDNA tertiary structure.

  3. Hydroxide Degradation Pathways for Substituted Trimethylammonium Cations: A DFT Study

    SciTech Connect

    Long, H.; Kim, K.; Pivovar, B. S.

    2012-05-03

    Substituted trimethylammonium cations serve as small molecule analogues for tetherable cations in anion exchange membranes. In turn, these membranes serve as the basis for alkaline membrane fuel cells by allowing facile conduction of hydroxide. As these cations are susceptible to hydroxide attack, they degrade over time and greatly limit the lifetime of the fuel cell. In this research, we performed density functional theory calculations to investigate the degradation pathways of substituted trimethylammonium cations to probe the relative durability of cation tethering strategies in alkyl and aromatic tethers. Our results show that significant changes in calculated energy barriers occur when substitution groups change. Specifically, we have found that, when available, the Hofmann elimination pathway is the most vulnerable pathway for degradation; however, this barrier is also found to depend on the carbon chain length and number of hydrogens susceptible to Hofmann elimination. S{sub N}2 barriers were also investigated for both methyl groups and substitution groups. The reported findings give important insight into potential tethering strategies for trimethylammonium cations in anion exchange membranes.

  4. Feasibility of Soil Aquifer Treatment for Removal Chemical Pollutants of Wastewater

    NASA Astrophysics Data System (ADS)

    El-Hattab, Ibrahim H.; Rashed, I. M.; Khalil, M. R.

    This study evaluated Soil Aquifer Treatment (SAT) as a method applied for removal of some chemical pollutants within wastewater. This study was made on two pilot areas in Egypt, in Abu Rawash district and El Mansouria district. The study concerned with evaluating the SAT system removal efficiency by different soil types, assessing optimum soil matrix for achieving adequate SAT, evaluating the renovated water quality conjugate to various water depths and assessing the change occur in some of the wastewater constituents (zinc, iron as heavy metals and magnesium, sodium as a basic cations). The results concluded that sandy loam soil was better than clayed soil for magnesium and sodium removal through SAT and sandy soil was not recommended for Magnesium and Sodium removal. Sandy soil was better than clayed soil for zinc and Iron removal through SAT system and sandy loam soil was not recommended for zinc and iron removal.

  5. Biogenic and synthetic polyamines bind cationic dendrimers.

    PubMed

    Mandeville, Jean-Sebastian; Bourassa, Phillipe; Thomas, Thekkumkattil John; Tajmir-Riahi, Heidar-Ali

    2012-01-01

    Biogenic polyamines are essential for cell growth and differentiation, while polyamine analogues exert antitumor activity in multiple experimental model systems, including breast and lung cancer. Dendrimers are widely used for drug delivery in vitro and in vivo. We report the bindings of biogenic polyamines, spermine (spm), and spermidine (spmd), and their synthetic analogues, 3,7,11,15-tetrazaheptadecane.4HCl (BE-333) and 3,7,11,15,19-pentazahenicosane.5HCl (BE-3333) to dendrimers of different compositions, mPEG-PAMAM (G3), mPEG-PAMAM (G4) and PAMAM (G4). FTIR and UV-visible spectroscopic methods as well as molecular modeling were used to analyze polyamine binding mode, the binding constant and the effects of polyamine complexation on dendrimer stability and conformation. Structural analysis showed that polyamines bound dendrimers through both hydrophobic and hydrophilic contacts with overall binding constants of K(spm-mPEG-G3) = 7.6 × 10(4) M(-1), K(spm-mPEG-PAMAM-G4) = 4.6 × 10(4) M(-1), K(spm-PAMAM-G4) = 6.6 × 10(4) M(-1), K(spmd-mPEG-G3) = 1.0 × 10(5) M(-1), K(spmd-mPEG-PAMAM-G4) = 5.5 × 10(4) M(-1), K(spmd-PAMAM-G4) = 9.2 × 10(4) M(-1), K(BE-333-mPEG-G3) = 4.2 × 10(4) M(-1), K(Be-333-mPEG-PAMAM-G4) = 3.2 × 10(4) M(-1), K(BE-333-PAMAM-G4) = 3.6 × 10(4) M(-1), K(BE-3333-mPEG-G3) = 2.2 × 10(4) M(-1), K(Be-3333-mPEG-PAMAM-G4) = 2.4 × 10(4) M(-1), K(BE-3333-PAMAM-G4) = 2.3 × 10(4) M(-1). Biogenic polyamines showed stronger affinity toward dendrimers than those of synthetic polyamines, while weaker interaction was observed as polyamine cationic charges increased. The free binding energies calculated from docking studies were: -3.2 (spermine), -3.5 (spermidine) and -3.03 (BE-3333) kcal/mol, with the following order of binding affinity: spermidine-PAMAM-G-4>spermine-PAMMAM-G4>BE-3333-PAMAM-G4 consistent with spectroscopic data. Our results suggest that dendrimers can act as carrier vehicles for delivering antitumor polyamine analogues to target tissues

  6. Multicarboxylic hyperbranched polyglycerol modified SBA-15 for the adsorption of cationic dyes and copper ions from aqueous media

    NASA Astrophysics Data System (ADS)

    Chen, Zhengji; Zhou, Li; Zhang, Faai; Yu, Chuanbai; Wei, Zhibo

    2012-04-01

    The aim of the present work was to investigate the potential of multicarboxylic hyperbranched polyglycerol (HPG) modified mesoporous SBA-15 (SBA/HPG-COOH) as adsorbent for the removal of cationic dyes or/and heavy metal ions from aqueous media. The SBA/HPG-COOH adsorbents can be facilely synthesized through two steps: in situ anionic ring-opening polymerization of glycidol and further modification of hydroxyl groups by succinic anhydride. The resulting SBA/HPG-COOH was characterized by means of FTIR, TGA, XRD, SEM and nitrogen adsorption-desorption isotherms. The results demonstrate that the SBA/HPG-COOH was successfully synthesized and the density of carboxylic groups on the SBA/HPG-COOH is calculated to be as high as 1.5 mmol/g, posing a powerful base for adsorbing cationic adsorbates. Four kinds of dyes and copper ions were chosen as representatives to investigate the adsorption ability of SBA/HPG-COOH. The SBA/HPG-COOH adsorbent showed quick adsorption rate, high adsorption capacity (e.g., its saturated adsorption capacity for methylene blue (MB) can reach 0.50 mmol/g, while for unmodified SBA-15 is lower than 0.05 mmol/g), and high selectivity for cationic adsorbates. The fitness of Langmuir adsorption model and pseudo second-order kinetics on describing the adsorption isotherm and kinetics of SBA/HPG-COOH for MB dye was examined, respectively. It is believed that this robust SBA/HPG-COOH adsorbent will find important application in removal of cationic adsorbates from aqueous solution.

  7. Resist residue removal using UV ozone treatment

    NASA Astrophysics Data System (ADS)

    Chen, Shu-Fang; Chang, Ching-Yu; Ku, Yao-Ching

    2010-04-01

    In a conventional lithography process, the resist pattern is removed by dry strip or wet chemical etch. The wet chemical etch includes sulfuric peroxide etch and solvent etch. The wet chemical etch process is always combined with the dry strip process to meet the residue process spec. However, in some applications, only the wet-etch process can be used to avoid substrate damage during the plasma step. However, organic residue can be found from particle surface scan and TGA/DSC after normal solvent strip. In this paper, we investigate polymer residue stripping using only solvent as well as solvent in combination with UV treatment. For solvents only, some solvents different from the conventional PGMEA/PGME mixture in polarity, also exhibited stripping ability but the efficiency is not as good as PGME/PGMEA mixture. When supplemented with UV treatment, the organic residue can be further decomposed and removed completely. The UV we used contains 185nm and 254nm wavelengths. Ozone is generated during UV exposure and acts as oxidant. The organic residue is thus decomposed and removed. It has been proven as an effective method to cleave the C-C bond without damaging the wafer substrate. The organic residue on the wafer surface can be easily stripped away under UV-ozone exposure. Its defect performance is also discussed in this paper.

  8. A new material for removing heavy metals from water

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H., Jr.; Street, Kenneth W., Jr.

    1994-01-01

    The NASA Lewis Research Center developed and is patenting a new high capacity ion exchange material (IEM) that removes toxic metals from contaminated water in laboratory tests. The IEM can be made into many forms, such as thin films, coatings, pellets, and fibers. As a result, it can be adapted to many applications to purify contaminated water wherever it is found, be it in waste water treatment systems, lakes, ponds, industrial plants, or in homes. Laboratory tests have been conducted on aqueous solutions containing only one of the following metal cations: lead, copper, mercury, cadmium, silver, chromium (III), nickel, zinc, and yttrium. Tests were also conducted with: (1) calcium present to determine its effects on the uptake of cadmium and copper, and (2) uranium and lanthanides which are stand-ins for other radioactive elements, (3) drinking water for the removal of copper and lead, and (3) others compositions. The results revealed that the IEM removes all these cations, even in the presence of the calcium. Of particular interest are the results of the tests with the drinking water: the lead concentration was reduced from 142 ppb down to 2.8 ppb (well below the accepted EPA standard).

  9. Arsenic removal from water

    DOEpatents

    Moore, Robert C.; Anderson, D. Richard

    2007-07-24

    Methods for removing arsenic from water by addition of inexpensive and commonly available magnesium oxide, magnesium hydroxide, calcium oxide, or calcium hydroxide to the water. The hydroxide has a strong chemical affinity for arsenic and rapidly adsorbs arsenic, even in the presence of carbonate in the water. Simple and commercially available mechanical methods for removal of magnesium hydroxide particles with adsorbed arsenic from drinking water can be used, including filtration, dissolved air flotation, vortex separation, or centrifugal separation. A method for continuous removal of arsenic from water is provided. Also provided is a method for concentrating arsenic in a water sample to facilitate quantification of arsenic, by means of magnesium or calcium hydroxide adsorption.

  10. Laser hair removal.

    PubMed

    Wanner, Molly

    2005-01-01

    Since 1996, there have been numerous advances in hair laser removal that utilize melanin as a chromophore. All of the devices on the market may be used in patients with light skin (phototypes I-III) and yield hair reduction near 75%. The ruby (694 nm) laser, alexandrite (755 nm) laser, and diode (810 nm) laser, as well as intense pulsed light are commonly used devices for hair laser removal. The long-pulsed Nd:YAG (1064 nm) laser represents the safest device for hair removal in dark-skinned patients because of its long wavelength, although the diode laser, alexandrite laser, and intense pulse light may be used. For treatment of light hair, combination radiofrequency and optical devices as well as photodynamic therapy are under investigation. PMID:16229722

  11. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    PubMed Central

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the

  12. Environmental Remediation and Sorption of Metal Cations Using Aluminum Pillared Nano-Bentonite

    NASA Astrophysics Data System (ADS)

    Rifai, Rifai; Abou El Safa, Magda

    2015-04-01

    The release of heavy metal cations into the environment is a potential threat to water and soil quality. Some clay minerals play an important role, as physical and chemical barriers, for the isolation of metal-rich wastes and to adsorb heavy metals as well as to avoid their environmental dispersion. In the present study, the bentonitic clay (southeast El-Hammam City, Egypt) was subjected to pillaring using hydroxyl-aluminum solution. The XRD patterns of the Aluminum Pillared Nano-Bentonite (APNB) showed severe alteration of the crystal structure after pillaring. Poly metal solutions with different metal concentrations of Cu, Co, Ni, Zn, Cd and Pb (0.001, 0.005 and 0.01 moles), and pH (1, 2.5, 5 and 6) were subjected to treatment by the APNB. The removal process is very rapid and spontaneous and the contact time may be short (several minutes) for most adsorption to occur. The criterion for environmental remediation of APNB is less stringent and a short contact time is sufficient. The rate of Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+sorption remained higher or equal to the CEC. The sorption of metal ions by APNB are complex and probably involve several mechanisms. In general, APNB can be used to immobilize Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+ to any extent. For each metal ion, the most effective immobilization occurs over a particular pH around 5. According to the experimental data obtained, the uptake amount of the studied cations by APNB increased with increasing solution pH, sorbent dose and contact time. The preference of the APNB adsorption for heavy metal ions that are through the cation exchange processes decreases in the order: Cu2+>Zn2+>Co2+>Cd2+ >Ni2+ >Pb2+. Keywords: Bentonitic clay, Egypt, Aluminum Pillared Nano-Bentonite, heavy metal, environmental remediation

  13. Quickly Removable Valve

    NASA Technical Reports Server (NTRS)

    Robbins, John S.

    1988-01-01

    Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

  14. Drum lid removal tool

    DOEpatents

    Pella, Bernard M.; Smith, Philip D.

    2010-08-24

    A tool for removing the lid of a metal drum wherein the lid is clamped over the drum rim without protruding edges, the tool having an elongated handle with a blade carried by an angularly positioned holder affixed to the midsection of the handle, the blade being of selected width to slice between lid lip and the drum rim and, when the blade is so positioned, upward motion of the blade handle will cause the blade to pry the lip from the rim and allow the lid to be removed.

  15. Solder dross removal apparatus

    NASA Technical Reports Server (NTRS)

    Webb, Winston S. (Inventor)

    1990-01-01

    An automatic dross removal apparatus is disclosed for removing dross from the surface of a solder bath in an automated electric component handling system. A rotatable wiper blade is positioned adjacent the solder bath which skims the dross off of the surface prior to the dipping of a robot conveyed component into the bath. An electronic control circuit causes a motor to rotate the wiper arm one full rotational cycle each time a pulse is received from a robot controller as a component approaches the solder bath.

  16. Solder dross removal apparatus

    NASA Technical Reports Server (NTRS)

    Webb, Winston S. (Inventor)

    1992-01-01

    An automatic dross removal apparatus (10) is disclosed for removing dross from the surface of a solder bath (22) in an automated electric component handling system. A rotatable wiper blade (14) is positioned adjacent the solder bath (22) which skims the dross off of the surface prior to the dipping of a robot conveyed component into the bath. An electronic control circuit (34) causes a motor (32) to rotate the wiper arm (14) one full rotational cycle each time a pulse is received from a robot controller (44) as a component approaches the solder bath (22).

  17. Arsenic removal by coagulation

    SciTech Connect

    Scott, K.N.; Green, J.F.; Do, H.D.; McLean, S.J.

    1995-04-01

    This study evaluated the removal of naturally occurring arsenic in a full-scale (106-mgd) conventional treatment plant. When the source water was treated with 3--10 mg/L of ferric chloride or 6, 10, or 20 mg/L of alum, arsenic removal was 81--96% (ferric chloride) and 23--71% (alum). Metal concentrations in the sludge produced during this study were below the state`s current hazardous waste levels at all coagulant dosages. No operational difficulties were encountered.

  18. Optimising Laser Tattoo Removal

    PubMed Central

    Sardana, Kabir; Ranjan, Rashmi; Ghunawat, Sneha

    2015-01-01

    Lasers are the standard modality for tattoo removal. Though there are various factors that determine the results, we have divided them into three logical headings, laser dependant factors such as type of laser and beam modifications, tattoo dependent factors like size and depth, colour of pigment and lastly host dependent factors, which includes primarily the presence of a robust immune response. Modifications in the existing techniques may help in better clinical outcome with minimal risk of complications. This article provides an insight into some of these techniques along with a detailed account of the factors involved in tattoo removal. PMID:25949018

  19. Removable feedwater sparger assembly

    DOEpatents

    Challberg, R.C.

    1994-10-04

    A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith. 8 figs.

  20. Removable feedwater sparger assembly

    DOEpatents

    Challberg, Roy C.

    1994-01-01

    A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith.