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1

The layered double hydroxide (LDH) of Zn with Ga: Synthesis and reversible thermal behaviour  

Microsoft Academic Search

The carbonate containing layered double hydroxide (LDH) of Zn with Ga, crystallizes in an ordered 3R1 polytype having the rhombohedral structure with a fixed composition corresponding to [Zn2+]\\/[Ga3+] = 2.0. The sulphate containing LDH on the other hand crystallizes in the turbostratically disordered ‘11 Œ phase. The layered structure collapses at 400?°C. The oxide residue obtained from the carbonate containing

Grace S. Thomas; P. Vishnu Kamath

2006-01-01

2

Removal of Trace Levels of Arsenic and Selenium from Aqueous Solutions by Calcined and Uncalcined Layered Double Hydroxides (LDH)  

Microsoft Academic Search

The adsorption of As and Se from dilute aqueous solutions, representing model power-plant effluent streams, by calcined and uncalcined layered double hydroxide (LDH) adsorbents has been investigated. The results indicate that As(V) has a greater adsorption capacity than Se(IV) for both calcined and uncalcined LDHs. An mth-order kinetic rate equation describes the adsorption kinetics of As and Se on these

Li Yang; Zoya Shahrivari; Paul K. T. Liu; Muhammad Sahimi; Theodore T. Tsotsis

2005-01-01

3

Electrochemical synthesis of Zn-Al layered double hydroxide (LDH) films.  

PubMed

A new electrodeposition condition to produce Zn-Al LDH films was developed using nitrate solutions containing Zn (2+) and Al (3+) ions. Deposition was achieved by reducing nitrate ions to generate hydroxide ions on the working electrode. This elevates the local pH on the working electrode, resulting in precipitation of Zn-Al LDH films. The effect of deposition potential, pH of the plating solution, and the Zn (2+) to Al (3+) ratio in the plating solution on the purity and crystallinity of the LDH films deposited was systematically studied using X-ray diffraction and energy dispersive spectroscopy (EDS). The optimum deposition potential to deposit pure and well-ordered Zn-Al LDH films was E = -1.65V versus a Ag/AgCl in 4 M KCl reference electrode at room temperature using a solution containing 12.5 mM Zn(NO 3) 2.6H 2O and 7.5 mM Al(NO 3) 3.9H 2O with pH adjusted to 3.8. The resulting film contained 39 atomic %Al (3+) ions replacing Zn (2+) ions, leading to a composition of Zn 0.61Al 0.39(OH) 2(NO 3) 0.39. xH 2O. Increasing or decreasing the aluminum concentration in the plating solution resulted in the formation of aluminum- or zinc-containing impurities, respectively, instead of varying aluminum content incorporated into the LDH phase. Choosing an optimum deposition potential was important to obtain LDH as a pure phase in the film. When the potential more negative than the optimum potential is used, zinc metal or zinc hydroxide was deposited as a side product, whereas making the potential less negative than the optimum potential resulted in the formation of zinc oxide as the major phase. The pH condition of the plating solution was also critical, as increasing pH destabilizes the formation of the LDH phase while decreasing pH promoted deposition of other impurities. PMID:18533629

Yarger, Matthew S; Steinmiller, Ellen M P; Choi, Kyoung-Shin

2008-07-01

4

Composition and structure of an iron-bearing, layered double hydroxide (LDH) - Green rust sodium sulphate  

NASA Astrophysics Data System (ADS)

Mixed-valent Fe(II),Fe(III)-layered hydroxide, known as green rust, was synthesized from slightly basic, sodium sulphate solutions in an oxygen-free glove box. Solution conditions were monitored with pH and Eh electrodes and optimized to ensure a pure sulphate green-rust phase. The solid was characterised using Mössbauer spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the solution from which the green rust precipitated was established by mass and absorption spectroscopy. The sulphate form of green rust is composed of brucite-like layers with Fe(II) and Fe(III) in an ordered distribution. The interlayers contain sulphate, water and sodium in an arrangement characteristic for the nikischerite group. The crystal structure is highly disordered by stacking faults. The composition, formula and crystallographic parameters are: NaFe(II) 6Fe(III) 3(SO 4) 2(OH) 18·12H 2O, space group P-3, a = 9.528(6) Å, c = 10.968(8) Å and Z = 1. Green rust sodium sulphate, GR, crystallizes in thin, hexagonal plates. Particles range from less than 50 nm to 2 ?m in diameter and are 40 nm thick or less. The material is redox active and reaction rates are fast. Extremely small particle size and high surface area contribute to rapid oxidation, transforming green rust to an Fe(III)-phase within minutes.

Christiansen, B. C.; Balic-Zunic, T.; Petit, P.-O.; Frandsen, C.; Mørup, S.; Geckeis, H.; Katerinopoulou, A.; Stipp, S. L. Svane

2009-06-01

5

Synthesis of well-dispersed layered double hydroxide core@ordered mesoporous silica shell nanostructure (LDH@mSiO2) and its application in drug delivery  

NASA Astrophysics Data System (ADS)

We demonstrate an efficient synthesis of novel layered double hydroxide mesoporous silica core-shell nanostructures (LDH@mSiO2) that have a hexagonal MgAl-LDH nanoplate core and an ordered mesoporous silica shell with perpendicularly oriented channels via a surfactant-templating method. Transmission electron microscopy, X-ray diffraction and N2 sorption analyses confirmed that the obtained nanostructures have uniform accessible mesopores (~2.2 nm), high surface area (~430 m2 g-1), and large pore volume (~0.22 cm3 g-1). Investigations of drug release and bio-imaging showed that this material has a slow release effect of ibuprofen and good biocompatibility. This work provides an economical approach to fabricate LDH@mSiO2 core-shell nanostructures, which may have great potential in broad drug delivery and hyperthermia therapy applications.We demonstrate an efficient synthesis of novel layered double hydroxide mesoporous silica core-shell nanostructures (LDH@mSiO2) that have a hexagonal MgAl-LDH nanoplate core and an ordered mesoporous silica shell with perpendicularly oriented channels via a surfactant-templating method. Transmission electron microscopy, X-ray diffraction and N2 sorption analyses confirmed that the obtained nanostructures have uniform accessible mesopores (~2.2 nm), high surface area (~430 m2 g-1), and large pore volume (~0.22 cm3 g-1). Investigations of drug release and bio-imaging showed that this material has a slow release effect of ibuprofen and good biocompatibility. This work provides an economical approach to fabricate LDH@mSiO2 core-shell nanostructures, which may have great potential in broad drug delivery and hyperthermia therapy applications. Electronic supplementary information (ESI) available: Additional XRD, SEM, TEM, DLS and LSCM data. See DOI: 10.1039/c1nr10718f

Bao, Haifeng; Yang, Jianping; Huang, Yan; Xu, Zhi Ping; Hao, Na; Wu, Zhangxiong; Lu, Gao Qing (Max); Zhao, Dongyuan

2011-10-01

6

A new approach to reducing the flammability of layered double hydroxide (LDH)-based polymer composites: preparation and characterization of dye structure-intercalated LDH and its effect on the flammability of polypropylene-grafted maleic anhydride/d-LDH composites.  

PubMed

Dye structure-intercalated layered double hydroxide (d-LDH) was synthesized using a one-step method, and its intercalated behaviors have been characterized by Fourier transform infrared spectroscopy (FTIR), wide angle X-ray scattering (WAXS), scanning electron microscopy, thermogravimetric analysis (TGA), etc. As a novel functional potential fire-retarding nanofiller, it was used to prepare a polypropylene-grafted maleic anhydride (PP-g-MA)/d-LDH composite by refluxing the mixture of d-LDH and PP-g-MA in xylene, aiming to investigate its effect on the flammability of the PP-g-MA composite. The morphological properties, thermal stability, and flame retardant properties of the PP-g-MA/d-LDH composite were determined by FTIR, WAXS, transmission electron microscopy, TGA, and microscale combustion calorimetry. Compared with NO3-LDH (unmodified LDH) and LDH intercalated by sodium dodecylbenzenesulfonate (conventional organo-modified LDH), d-LDH can significantly decrease the heat release rate and the total heat release of the PP-g-MA composite, offering a new approach to imparting low flammability to LDH-based polymer composites. PMID:23927608

Kang, Nian-Jun; Wang, De-Yi; Kutlu, Burak; Zhao, Peng-Cheng; Leuteritz, Andreas; Wagenknecht, Udo; Heinrich, Gert

2013-09-25

7

Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit ® S 100 covering  

NASA Astrophysics Data System (ADS)

Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+, Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 Å. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit ® S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7.

del Arco, M.; Fernández, A.; Martín, C.; Rives, V.

2010-12-01

8

Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering  

SciTech Connect

Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg{sup 2+} and Al{sup 3+} or Mg{sup 2+}, Al{sup 3+} and Fe{sup 3+} in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

Arco, M. del; Fernandez, A.; Martin, C. [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, 37008 Salamanca (Spain); Rives, V., E-mail: vrives@usal.e [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, 37008 Salamanca (Spain)

2010-12-15

9

Effective inhibition of colon cancer cell growth with MgAl-layered double hydroxide (LDH) loaded 5-FU and PI3K/mTOR dual inhibitor BEZ-235 through apoptotic pathways  

PubMed Central

Colon cancer is the third most common cancer and the third largest cause of cancer-related death. Fluorouracil (5-FU) is the front-line chemotherapeutic agent for colon cancer. However, its response rate is less than 60%, even in combination with other chemotherapeutic agents. The side effects of 5-FU also limit its application. Nanoparticles have been used to deliver 5-FU, to increase its effectiveness and reduce side effects. Another common approach for colon cancer treatment is targeted therapy against the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. A recently-invented inhibitor of this pathway, BEZ-235, has been tested in several clinical trials and has shown effectiveness and low side effects. Thus, it is a very promising drug for colon cancer treatment. The combination of these two drugs, especially nanoparticle-packed 5-FU and BEZ-235, has not been studied. In the present study, we demonstrated that nanoparticles of layered double hydroxide (LDH) loaded with 5-FU were more effective than a free drug at inhibiting colon cancer cell growth, and that a combination treatment with BEZ-235 further increased the sensitivity of colon cancer cells to the treatment of LDH-packed 5-FU (LDH-5-FU). BEZ-235 alone can decrease colon cancer HCT-116 cell viability to 46% of the control, and the addition of LDH-5-FU produced a greater effect, reducing cell survival to 8% of the control. Our data indicate that the combination therapy of nanodelivered 5-FU with a PI3K/Akt inhibitor, BEZ-235, may promise a more effective approach for colon cancer treatment. PMID:25075187

Chen, Jiezhong; Shao, Renfu; Li, Li; Xu, Zhi Ping; Gu, Wenyi

2014-01-01

10

Methotrexate intercalated ZnAl-layered double hydroxide  

SciTech Connect

The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Chakraborty, Jui, E-mail: jui@cgcri.res.in [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Mitra, Manoj K. [Department of Metallurgical and Materials Engineering, Jadavpur University, Kolkata 700032 (India); Basu, Debabrata [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata 700032 (India)

2011-09-15

11

Biological evaluation of layered double hydroxides as efficient drug vehicles  

NASA Astrophysics Data System (ADS)

Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

Li, Yan; Liu, Dan; Ai, Hanhua; Chang, Qing; Liu, Dandan; Xia, Ying; Liu, Shuwen; Peng, Nanfang; Xi, Zhuge; Yang, Xu

2010-03-01

12

Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor  

NASA Astrophysics Data System (ADS)

The synthesis of Mg2Al-NO3 layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1-2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials.

Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming; Hou, Wanguo

2014-02-01

13

Adsorption of Trace Levels of Arsenic from Aqueous Solutions by Conditioned Layered Double Hydroxides: Batch and Flow  

E-print Network

calcined layered double hydroxide (LDH) adsorbents. Conditioning the adsorbent significantly reduced the dissolution observed with uncalcined and calcined LDH3. The adsorption rates and isotherms have been invariant with particle size4. The removal of As(V) on conditioned, calcined LDH adsorbents was also

Southern California, University of

14

APPLICATIONS OF LAYERED DOUBLE HYDROXIDES IN REMOVING OXYANIONS FROM OIL REFINING AND COAL MINING WASTEWATER  

Microsoft Academic Search

Western Research Institute (WRI), in conjunction with the U.S. Department of Energy (DOE), conducted a study of using the layered double hydroxides (LDH) as filter material to remove microorganisms, large biological molecules, certain anions and toxic oxyanions from various waste streams, including wastewater from refineries. Results demonstrate that LDH has a high adsorbing capability to those compounds with negative surface

Song Jin; Paul Fallgren

2006-01-01

15

Preparation and properties of layered double hydroxide–carboxymethylcellulose sodium\\/glycerol plasticized starch nanocomposites  

Microsoft Academic Search

The Zn–Al layered double hydroxide (LDH) was fabricated using carboxymethyl-cellulose sodium (CMC) as the stabilizer in aqueous solution, and then used as the filler to prepare LDH–CMC\\/glycerol plasticized-starch (GPS) nanocomposites in the casting process. Transmission electron microscopy exhibited the platelets of LDH–CMC with a lateral size of 30–60nm and the thickness of 5–10nm. X-ray diffraction showed that the presence of

Dongliang Wu; Peter R. Chang; Xiaofei Ma

2011-01-01

16

Layered double hydroxide as an efficient drug reservoir for folate derivatives  

Microsoft Academic Search

Folic acid derivatives such as folinic acid and methotrexate (MTX) have been successfully hybridized with layered double hydroxide (LDH) by ion-exchange reaction. The X-ray diffraction patterns and spectroscopic analyses indicate that these molecules intercalated into the hydroxide interlayer space are stabilized in the tilted longitudinal monolayer mode by electrostatic interaction. No significant changes in their structural and functional properties are

Jin-Ho Choy; Ji-Sun Jung; Jae-Min Oh; Man Park; Jinyoung Jeong; Young-Koo Kang; Ok-Jin Han

2004-01-01

17

An advanced Ni-Fe layered double hydroxide electrocatalyst for water oxidation.  

PubMed

Highly active, durable, and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions, including water-splitting and rechargeable metal-air batteries. Here, we report the synthesis of ultrathin nickel-iron layered double hydroxide (NiFe-LDH) nanoplates on mildly oxidized multiwalled carbon nanotubes (CNTs). Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-LDH. The crystalline NiFe-LDH phase in nanoplate form is found to be highly active for oxygen evolution reaction in alkaline solutions. For NiFe-LDH grown on a network of CNTs, the resulting NiFe-LDH/CNT complex exhibits higher electrocatalytic activity and stability for oxygen evolution than commercial precious metal Ir catalysts. PMID:23701670

Gong, Ming; Li, Yanguang; Wang, Hailiang; Liang, Yongye; Wu, Justin Z; Zhou, Jigang; Wang, Jian; Regier, Tom; Wei, Fei; Dai, Hongjie

2013-06-12

18

Molecular dynamics simulation of layered double hydroxides  

SciTech Connect

The interlayer structure and the dynamics of Cl{sup {minus}} ions and H{sub 2}O molecules in the interlayer space of two typical LDH [Layered Double Hydroxide] phases were investigated by molecular dynamics computer simulations. The simulations of hydrocalumite, [Ca{sub 2}Al(OH){sub 6}]Cl{center_dot}2H{sub 2}O reveal significant dynamic disorder in the orientations of interlayer water molecules. The hydration energy of hydrotalcite, [Mg{sub 2}Al(0H){sub 6}]Cl{center_dot}nH{sub 2}O, is found to have a minimum at approximately n = 2, in good agreement with experiment. The calculated diffusion coefficient of Cl{sup {minus}} as an outer-sphere surface complex is almost three times that of inner-sphere Cl{sup {minus}}, but is still about an order of magnitude less than that of Cl{sup {minus}} in bulk solution. The simulations demonstrate unique capabilities of combined NMR and molecular dynamics studies to understand the structure and dynamics of surface and interlayer species in mineral/water systems.

KALINICHEV,ANDREY G.; WANG,JIANWEI; KIRKPATRICK,R. JAMES; CYGAN,RANDALL T.

2000-05-19

19

Elution Behavior of Phosphate Contained in Mg/Fe and Zn/Fe Layered Double Hydroxides  

NASA Astrophysics Data System (ADS)

Layered double hydroxide (LDH) is a layered hydroxide and exchangeable anion is intercalated in its interlayer. Application of the LDH as a controlled-release material of interlayer anions has become of interest, thus it is important to clarify the elution behavior of interlayer anions. We synthesized hydrogenphosphate-intercalated Mg/Fe and Zn/Fe LDH and elution of phosphate from these LDH were tested in deionized water, sodium chloride solution, sodium sulfate solution, and sodium carbonate solution. For Mg/Fe LDH, the amount of eluted phosphate increased with time and reached to maximum that increased as higher concentrate solution was used. The elution of phosphate from Mg/Fe LDH could be described by the pseudo second-order equation. This elution behavior was explained as ion-exchange reaction of phosphate with sulfate or carbonate in tested solution by means of kinetic simulation using Runge-Kutta method. In the eluted solution, metal ions contained in the LDH were detected and its amount depended on pH of the tested solution, that is, amounts of eluted Mg and Zn ions were small at higher pH (ca. 10) for Mg/Fe and Zn/Fe LDH respectively, but large amount of Zn ion was detected when 2.03 mol·l-1 carbonate solution (pH = 13) was used. Thus elution of phosphate was caused by two main reactions: ion exchange and decomposition of the LDH.

Kurashina, Masashi; Amatsu, Tomohiro; Ochi, Takaaki; Ohigashi, Nozomi; Kanezaki, Eiji

20

Uptake of chloride ion from aqueous solution by calcined layered double hydroxides: Equilibrium and kinetic studies  

Microsoft Academic Search

Layered double hydroxides (LDH) calcined within a certain temperature range (denoted as CLDH) have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called “memory effect”, uptake of chloride ion from aqueous solution by calcined MgAl–CO3 LDH was investigated in batch mode. The equilibrium isotherm showed that the uptake of

Liang Lv; Jing He; Min Wei; D. G. Evans; Xue Duan

2006-01-01

21

Hybrid layered double hydroxides-polypyrrole composites for construction of glucose\\/O 2 biofuel cell  

Microsoft Academic Search

In this work, two layered double hydroxides, Zn2Cr–ABTS and Zn2Al–Fe(CN)6 LDH, have been synthesized and characterized by X ray diffraction and FTIR spectroscopy to confirm the intercalation of redox anions between inorganic layers. These redox active hybrid materials have been used to electrically connect laccase (Lac) and glucose oxidase (GOx) in biofuel cell devices. Co-immobilization of hybrid LDH and enzymes

Abdelkader Zebda; Sophie Tingry; Christophe Innocent; Serge Cosnier; Claude Forano; Christine Mousty

22

Zinc aluminium layered double hydroxides for the removal of iodine and iodide from aqueous solutions  

Microsoft Academic Search

I is a radioactive isotope of iodine that is readily absorbed by the body. In this paper we investigated the potential of a 3:1 Zn\\/Al layered double hydroxide (LDH) as a sorbent for the removal of iodine and iodide from water. Synthetic ZnAl(OH)(CO)·4HO was prepared by the co-precipitation before thermal activation. The LDH was treated with solutions containing iodide and

Frederick L. Theiss; Michael J. Sear-Hall; Sara J. Palmer; Ray L. Frost

2012-01-01

23

Fluorescence of Mg-Al-Eu Ternary Layered Double Hydroxide Sensitivity to Phenylalanine  

Microsoft Academic Search

We reported for the first time the fluorescence sensitivity of a Mg-Al-Eu ternary layered double hydroxide (LDH) to phenylalanine\\u000a (Phe). As shown in fluorescent spectra, the red emissions resulted from 5D0-7FJ transition (J?=?1, 2) of Eu3+ were quenched by Phe, and a strong peak around at 492 nm emerged. A strong interaction between the Mg-Al-Eu LDH and Phe was\\u000a manifested by

Yufeng Chen; Songhua Zhou; Fei Li; Junchao Wei; Yanfeng Dai; Yiwang Chen

24

Factors influencing the removal of fluoride from aqueous solution by calcined Mg–Al–CO 3 layered double hydroxides  

Microsoft Academic Search

Layered double hydroxides (LDH) calcined at different temperatures (denoted as CLDH) have been demonstrated to recover their original layered structure in the presence of appropriate anions. In the light of this so-called “memory effect”, a study of removal of fluoride from aqueous solution by calcined Mg–Al–CO3-LDH has been carried out. The LDH calcined at 500°C had the highest capacity of

Liang Lv; Jing He; Min Wei; D. G. Evans; Xue Duan

2006-01-01

25

Carbon ceramic electrodes bulk-modified with nanoparticles of ferrocenebutyrate-intercalated Mg–Al layered double hydroxide  

Microsoft Academic Search

Ferrocenebutyrate-intercalated layered double hydroxide (FcLDH) was prepared by the coprecipitation method and characterized by PXRD, FTIR, TEM and elemental analysis. FcLDH nanoparticles in deionized water were deposited onto the surface of graphite powder to yield graphite powder-supported FcLDH, which was subsequently dispersed into methyltrimethoxysilane-derived gels to fabricate surface-renewable, stable, rigid carbon ceramic electrodes containing the electroactive ferrocenyl group. Cyclic voltammetric

Peng Wang; Guoyi Zhu

2002-01-01

26

Photocatalytic conversion of carbon dioxide into methanol using zinc–copper–M(III) (M = aluminum, gallium) layered double hydroxides  

Microsoft Academic Search

Ordered layered double hydroxides (LDHs) consisting of zinc and\\/or copper hydroxides were synthesized and combined with aluminum or gallium. These LDH compounds were then applied as photocatalysts to convert gaseous CO2 (2.3kPa) to methanol or CO under UV–visible light using hydrogen. ZnAl LDH was the most active for CO2 photoreduction and the major product was CO formed at a rate

Naveed Ahmed; Yoshiyuki Shibata; Tatsuo Taniguchi; Yasuo Izumi

2011-01-01

27

Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids.  

PubMed

A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites. PMID:18243238

Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; da Costa Gardolinski, José Eduardo Ferreira; Wypych, Fernando

2008-04-01

28

Layered Double Hydroxide-Based Nanocarriers for Drug Delivery  

PubMed Central

Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed. PMID:24940733

Bi, Xue; Zhang, Hui; Dou, Liguang

2014-01-01

29

Treatment with coated layer double hydroxide clays decreases the toxicity of copper-contaminated water.  

PubMed

Copper is a common pollutant found in watersheds that exerts toxic effects on both invertebrates and vertebrates. Layer double hydroxide (LDH) clays are able to adsorb a wide range of contaminants through ion-exchange mechanisms. Coating LDH clays with various materials alters the aggregation of clay particles into the nano-size range, thus increasing relative surface area and offering great potential for contaminant remediation. The goal of this study was to determine if treatment with coated LDH clays decreases the toxicity of copper-containing solutions to Daphnia magna. Four LDH clays with different coatings used to alter hydrophobicity were as follows: used: Na(+) montmorillonite, Zn-Al LDH-nitrate, Zn-Al LDH-stearate, and Zn-Al LDH-carbonate. It was determined that coated LDH clays decreased copper toxicity by decreasing bioavailability and that smaller aggregate sizes decreased bioavailability the most. 96 h LC50 values increased by as much as 4.2 times with the treatment of the solutions with 100 mg/L LDH clay. Copper analysis of the clay and solutions indicated that the clays work by decreasing copper bioavailability by way of a binding mechanism. Coated LDH clays hold promise as a small-scale remediation tool or as an innovative tool for toxicity identification and evaluation characterization of metals. PMID:24442186

Blake, Deanne; Nar, Mangesh; D'Souza, Nandika Anne; Glenn, J Brad; Klaine, Stephen J; Roberts, Aaron P

2014-05-01

30

A Chiroptical Switch Based on DNA/Layered Double Hydroxide Ultrathin Films.  

PubMed

A highly oriented film was fabricated by layer-by-layer self-assembly of DNA and MgAl-layered double hydroxide nanosheets, and its application in chiroptical switch was demonstrated via intercalation and deintercalation of an achiral molecule into the DNA cavity. DNA molecules are prone to forming an ordered and dispersive state in the interlayer region of rigid layered double hydroxide (LDH) nanosheets as confirmed by scanning electron microscopy and atomic force microscopy. The induced chiroptical ultrathin film (UTF) is achieved via the intercalation of an achiral chromophore [5,10,15,20-tetrakis(4-N-methylpyridyl)porphine tetra(p-toluenesulfonate) (TMPyP)] into the spiral cavity of DNA stabilized in the LDH matrix [denoted as TMPyP-(DNA/LDH)20]. Fluorescence and circular dichroism spectroscopy are utilized to testify the intercalation of TMPyP into (DNA/LDH)20 UTF that involves two steps: the electrostatic binding of TMPyP onto the surface of (DNA/LDH)20 followed by intercalation into base pairs of DNA. In addition, the TMPyP-(DNA/LDH)20 UTF exhibits good reversibility and repeatability in induced optical chirality, based on the intercalation and deintercalation of TMPyP by alternate exposure to HCl and NH3/H2O vapor, which can be potentially used as a chiroptical switch in data storage. PMID:25285378

Shi, Wenying; Jia, Yankun; Xu, Simin; Li, Zhixiong; Fu, Yi; Wei, Min; Shi, Shuxian

2014-11-01

31

Bionanocomposites based on layered double hydroxides as drug delivery systems  

NASA Astrophysics Data System (ADS)

The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biopolymers to produce bionanocomposites, able to act as effective drug delivery systems (DDS). Ibuprofen (IBU) and 5-aminosalicylic acid (5-ASA) have been chosen as model drugs, being intercalated in a Mg-Al LDH matrix. On the one side, the LDHIBU intercalation compound prepared by ion-exchange reaction was blended with the biopolymers zein, a highly hydrophobic protein, and alginate, a polysaccharide widely applied for encapsulating drugs. On the other side, the LDH- 5-ASA intercalation compound prepared by co-precipitation was assembled to the polysaccharides chitosan and pectin, which show mucoadhesive properties and resistance to acid pH values, respectively. Characterization of the intercalation compounds and the resulting bionanocomposites was carried out by means of different experimental techniques: X-ray diffraction, infrared spectroscopy, chemical and thermal analysis, as well as optical and scanning electron microscopies. Data on the swelling behavior and drug release under different pH conditions are also reported.

Aranda, Pilar; Alcântara, Ana C. S.; Ribeiro, Ligia N. M.; Darder, Margarita; Ruiz-Hitzky, Eduardo

2012-10-01

32

Nitrogen-enriched, double-shelled carbon/layered double hydroxide hollow microspheres for excellent electrochemical performance  

NASA Astrophysics Data System (ADS)

A unique, double-shelled, hollow, carbon-based composite with enriched nitrogen has been prepared through a facile and versatile synthetic strategy. The hierarchical composite employs the nitrogen-enriched carbon hollow sphere as an interior shell and intercrossed Ni/Al layered double hydroxide (LDH) nanosheets as an exterior shell. The obtained N-C@LDH hollow microspheres (HMS) have high nitrogen enrichment, large specific surface area (337 m2 g-1), and uniform and open mesoporous structure. Taking advantage of these characteristics, the composite exhibits obviously superior capacitive behavior, including high specific capacitance, excellent rate capability and good cycling stability, compared with nitrogen-free carbon@LDH composite and hollow LDH without carbon shell. The composite displays high specific capacitance of 1711.51 F g-1 at a current density of 1 A g-1. In particular, the high specific capacitance can be kept to 997.3 F g-1 at a high current density of 10 A g-1, which still retains 94.97% of the initial specific capacitance after 500 cycles at this high current density. This N-enriched, hollow carbon/LDH composite can be expected to be a promising electrode material for electrochemical capacitors due to its high electrochemical performance.A unique, double-shelled, hollow, carbon-based composite with enriched nitrogen has been prepared through a facile and versatile synthetic strategy. The hierarchical composite employs the nitrogen-enriched carbon hollow sphere as an interior shell and intercrossed Ni/Al layered double hydroxide (LDH) nanosheets as an exterior shell. The obtained N-C@LDH hollow microspheres (HMS) have high nitrogen enrichment, large specific surface area (337 m2 g-1), and uniform and open mesoporous structure. Taking advantage of these characteristics, the composite exhibits obviously superior capacitive behavior, including high specific capacitance, excellent rate capability and good cycling stability, compared with nitrogen-free carbon@LDH composite and hollow LDH without carbon shell. The composite displays high specific capacitance of 1711.51 F g-1 at a current density of 1 A g-1. In particular, the high specific capacitance can be kept to 997.3 F g-1 at a high current density of 10 A g-1, which still retains 94.97% of the initial specific capacitance after 500 cycles at this high current density. This N-enriched, hollow carbon/LDH composite can be expected to be a promising electrode material for electrochemical capacitors due to its high electrochemical performance. Electronic supplementary information (ESI) available: IR spectrum of N-C@LDH hollow microspheres, Enlarged TEM images of SiO2@C and carbon hollow spheres, TEM image of N-enriched carbon spheres, SEM images of LDH HMS and C@LDH HMS, EDS analysis of N-enriched carbon spheres, SEM image of the product prepared under the same condition of C@LDH HMS without the AlOOH sol layer deposited on carbon spheres, survey and element XPS spectra of LDH HMS, C@LDH HMS and N-C@LDH HMS, the specific capacitance of as-prepared N-C@LDH HMS, C@LDH HMS and LDH HMS at different discharge current densities. See DOI: 10.1039/c4nr02756f

Xu, Jie; He, Fei; Gai, Shili; Zhang, Shenghuan; Li, Lei; Yang, Piaoping

2014-08-01

33

Reverse micelle synthesis of colloidal nickel-manganese layered double hydroxide nanosheets and their pseudocapacitive properties.  

PubMed

Colloidal nanosheets of nickel-manganese layered double hydroxides (LDHs) have been synthesized in high yields through a facile reverse micelle method with xylene as an oil phase and oleylamine as a surfactant. Electron microscopy studies of the product revealed the formation of colloidal nanoplatelets with sizes of 50-150?nm, and X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy studies showed that the Ni-Mn LDH nanosheets had a hydrotalcite-like structure with a formula of [Ni3 Mn(OH)8 ](Cl(-) )?n?H2 O. We found that the presence of both Ni and Mn precursors was required for the growth of Ni-Mn LDH nanosheets. As pseudocapacitors, the Ni-Mn LDH nanosheets exhibited much higher specific capacitance than unitary nickel hydroxides and manganese oxides. PMID:25224653

Sim, Hwansu; Jo, Changshin; Yu, Taekyung; Lim, Eunho; Yoon, Songhun; Lee, Jung Heon; Yoo, Jibeom; Lee, Jinwoo; Lim, Byungkwon

2014-11-01

34

A SEM, EDX and XAS characterization of Ba(II)Fe(III) layered double hydroxides  

NASA Astrophysics Data System (ADS)

The structural characteristics of Ba-Fe double hydroxides were studied by various methods, such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX) fluorescence and X-ray absorption spectroscopies (XAS). It was verified that under hyperalkaline conditions (using 10 M or 20 M NaOH solution for precipitating the substances) layered double hydroxides could be prepared and the structure collapsed on heat treatment at 523 K. Important structural parameters could also be obtained through the quantitative analysis of the XAS spectrum of Ba 3Fe-LDH made using 20 M NaOH for precipitating the material.

Srankó, D.; Sipiczki, M.; Bajnóczi, É. G.; Darányi, M.; Kukovecz, Á.; Kónya, Z.; Canton, S. E.; Norén, K.; Sipos, P.; Pálinkó, I.

2011-05-01

35

Adsorption and photodegradation properties of anionic dyes by layered double hydroxides  

NASA Astrophysics Data System (ADS)

The adsorption and photodegradation behavior of methyl orange (MO) and fast green (FG) over ZnAl- and MgAl-based layered double hydroxide (LDH) adsorbents have been examined. ZnAl-LDHs were prepared with Zn/Al ratios of 2 to 4 by co-precipitation at pH 8. The ZnAl-LDHs and a commercial MgAl-LDH with a Mg/Al ratio of 3 were evaluated for their ability to adsorb MO and FG and for the photodegradation behavior of these dyes under UV irradiation. Structure analysis of the LDH-dyes-adsorbed complexes revealed that the adsorption produced two types of structures, an intercalation complex for MO and a surface-adsorbed complex for FG. The maximum adsorption of MO on the LDHs was significantly higher (more than tenfold) than FG. Results indicated the adsorption isotherms for the retention of both dyes by ZnAl- and MgAl-LDHs could be fitted to a Freundlich equation, showing a higher affinity for dyes on MgAl-LDH compared to those on ZnAl-LDH. The catalytic degradation ability of dye-LDH complex solid films on a quartz plate was superior to pure dye films under UV irradiation. The FG non-intercalated LDH complexes showed much faster photodegradation under UV irradiation than the MO-intercalated LDH complexes, which pointed to the important role of the LDH materials containing sensitized dyes in enhancing the generation of labile hydroxyl ions from the hydrophilic LDH surface.

Morimoto, Kazuya; Tamura, Kenji; Iyi, Nobuo; Ye, Jinhua; Yamada, Hirohisa

2011-09-01

36

Synthesis and release behavior of composites of camptothecin and layered double hydroxide  

NASA Astrophysics Data System (ADS)

A simple method, reconstruction of calcinated layered double hydroxides (CLDH) in an organic (ethanol)-water mixed solvent medium containing drug, was developed to intercalate partially a non-ionic and poorly water-soluble drug (camptothecin) into the gallery of layered double hydroxides (LDHs) to form the drug-LDH composites. The purpose of choosing organic-water mixed solvent is to increase remarkably the solubility of camptothecin (CPT) in the reconstruction medium. A probable morphology of CPT molecules in the gallery of LDHs is that CPT molecules arrange as monolayer with the long axis parallel to the LDH layers. The in vitro drug release from the composites was remarkably lower than that from the corresponding physical mixture, which shows these drug-inorganic composites can be used as a potential drug delivery system.

Dong, Lun; Yan, Li; Hou, Wan-Guo; Liu, Shao-Jie

2010-08-01

37

Structural characterization and electrocatalytic application of hemoglobin immobilized in layered double hydroxides modified with hydroxyl functionalized ionic liquid.  

PubMed

Hemoglobin (Hb) was immobilized in Zn2Al-Layered Double Hydroxides (LDH) modified with Hydroxyl Functionalized Ionic Liquid (HFIL) through adsorption and coprecipitation method, respectively. Adsorption experiments showed that the presence of HFIL could enhance the maximum protein loading. However, the Hb loading through coprecipitation technique was far higher than that for adsorption. The role of HFIL on the interaction between Hb and LDH was investigated by XRD, FTIR, UV-vis and fluorescence spectroscopies. Although the quaternary structure of Hb entrapped in HFIL-LDH through coprecipitation technique (denoted as HFIL-LDH-Hbcop) might be altered slightly more than that in LDH (LDH-Hbcop), its secondary structure and redox-active heme groups kept intact. Morphologies of LDH-Hbcop and HFIL-LDH-Hbcop biohybrids were analyzed through SEM and TEM images. The direct electrochemistry of the immobilized Hb indicated that the coprecipitation bioelectrode performed better than that of the corresponding adsorption one. Regardless of adsorption and coprecipitation, the introduction of HFIL could distinctly promote the electron transport. Among all bioelectrodes, HFIL-LDH-Hbcop/GCE displayed the best electrocatalytic activity for H2O2 determination with a larger electroactive Hb percentage (6.76%), higher sensitivity (40.63A/Mcm(2)) and lower detection limit (0.0054?mol/L). So HFIL-LDH could effectively immobilize enzymes via coprecipitation technique, which had potential applications in the fabrication of electrochemical biosensors. PMID:25112912

Zhan, Tianrong; Yang, Qi; Zhang, Yumei; Wang, Xinjun; Xu, Jie; Hou, Wanguo

2014-11-01

38

Synthesis of ACECLOFENAC/HYDROXYPROPYL-?-CYCLODEXTRIN Intercalated Layered Double Hydroxides and Controlled Release Properties  

NASA Astrophysics Data System (ADS)

Aceclofenac (AC)/hydroxypropyl-?-cyclodextrin (HP-?-CD) complex intercalated layered double hydroxides (LDHs) have been synthesized by reconstruction method. X-ray diffraction, Fourier transform infrared and thermal gravimetric analyses indicated a successful intercalation of AC/HP-?-CD complex into the LDHs gallery. The AC release properties were also studied in different pH values buffer solution. The results indicate that the AC/HP-?-CD intercalated LDH has a potential application in drug delivery agent.

Li, Shifeng; Shen, Yanming; Liu, Dongbin; Fan, Lihui; Wu, Keke; Xiao, Min

2013-06-01

39

Layered double hydroxides: A novel nano-sorbent for solid-phase extraction  

Microsoft Academic Search

The nickel–aluminum layered double hydroxide (Ni–Al LDH) was synthesized by a simple co-precipitation method with controlled pH and followed by hydrothermal treatment. The obtained nano-structured inorganic material was employed, for the first time, as a new solid-phase extraction (SPE) sorbent for the extraction and pre-concentration of trace levels of fluoride ions from aqueous solutions. An indirect method was used for

H. Abdolmohammad-Zadeh; Z. Rezvani; G. H. Sadeghi; E. Zorufi

2011-01-01

40

Sorption/desorption of arsenate on/from Mg-Al layered double hydroxides: influence of phosphate.  

PubMed

We have studied: (i) the sorption of arsenate on Mg-Al layered double hydroxides (LDHs) containing chloride (LDH-Cl) or carbonate (LDH-CO(3)) in the absence or presence of phosphate; (ii) the competitive sorption of arsenate and phosphate as affected by reaction time and pH and; (iii) the desorption of arsenate previously sorbed on the LDH by phosphate. The LDH samples were uncalcined (LDH-Cl-20 and LDH-CO(3)-20) or calcined at 450 degrees C (LDH-Cl-450 and LDH-CO(3)-450). More phosphate than arsenate was sorbed onto all the minerals but LDH-Cl-450 sorbed much lower amounts of both the ligands than LDH-Cl-20; vice versa LDH-CO(3)-450 showed a capacity to sorb arsenate and phosphate much greater than LDH-CO(3)-20. XRD analysis showed that arsenate was included into the layer spaces of LDH-Cl-20, but not in those of LDH-CO(3)-20. Competition in sorption between arsenate and phosphate was affected by pH, reaction time, surface coverage and sequence of addition of the ligands. Phosphate showed a greater affinity for LDHs than arsenate. The final arsenate sorbed/phosphate sorbed molar ratio increased with reaction time or by adding arsenate before phosphate, but decreased by increasing pH and by adding phosphate before arsenate. The effect of reaction time on the desorption of arsenate by phosphate was also studied. PMID:19211108

Violante, Antonio; Pucci, Marianna; Cozzolino, Vincenza; Zhu, Jun; Pigna, Massimo

2009-05-01

41

Hierarchical construction of an ultrathin layered double hydroxide nanoarray for highly-efficient oxygen evolution reaction  

NASA Astrophysics Data System (ADS)

Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (?) of 257 mV is needed for a current density of 80 mA cm-2 with a Tafel slope of 53 mV per decade. The hierarchical LDH nanoarray also shows excellent structural stability in alkaline media. After continuous testing under a high OER current density (~300 mA cm-2) for 10 h, the sample maintains the ordered hierarchical structure with no significant deactivation of the catalytic properties.Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (?) of 257 mV is needed for a current density of 80 mA cm-2 with a Tafel slope of 53 mV per decade. The hierarchical LDH nanoarray also shows excellent structural stability in alkaline media. After continuous testing under a high OER current density (~300 mA cm-2) for 10 h, the sample maintains the ordered hierarchical structure with no significant deactivation of the catalytic properties. Electronic supplementary information (ESI) available: SEM images of the Ni foam and Co-based nanowire arrays; XPS and EDS results of the hierarchical LDH nanoarrays, and gas bubble adhesive force data. See DOI: 10.1039/c4nr03371j

Yang, Qiu; Li, Tian; Lu, Zhiyi; Sun, Xiaoming; Liu, Junfeng

2014-09-01

42

Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine  

NASA Astrophysics Data System (ADS)

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach. Electronic supplementary information (ESI) available: Fig. S1 showing 2D fast Fourier transform (FFT) image of NiAl-LDH phase in NiAl-LDH/G composites, and Fig. S2 showing CV curve of the pristine G modified electrode. See DOI: 10.1039/c1nr10592b.

Li, Meixia; Zhu, Jun E.; Zhang, Lili; Chen, Xu; Zhang, Huimin; Zhang, Fazhi; Xu, Sailong; Evans, David G.

2011-10-01

43

Mg-Al layered double hydroxide-methotrexate nanohybrid drug delivery system: evaluation of efficacy.  

PubMed

Mg-Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH-MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH-MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH-MTX hybrids in phosphate buffer saline at pH7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism. PMID:23498245

Chakraborty, Jui; Roychowdhury, Susanta; Sengupta, Somoshree; Ghosh, Swapankumar

2013-05-01

44

The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids  

PubMed Central

Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16) were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84–1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications. PMID:23737669

Qin, Lili; Wang, Mei; Zhu, Rongrong; You, Songhui; Zhou, Ping; Wang, Shilong

2013-01-01

45

Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide  

NASA Astrophysics Data System (ADS)

Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

2013-07-01

46

Synthesis and adsorption properties of p-sulfonated calix[4 and 6]arene-intercalated layered double hydroxides  

SciTech Connect

The intercalation of water-soluble p-sulfonated calix[4 and 6]arene (CS4 and CS6) in the interlayer of the Mg-Al and Zn-Al layered double hydroxide (LDH) by the coprecipitation method has been investigated, as well as the adsorption properties of the resulting CS/LDHs for benzyl alcohol (BA) and p-nitrophenol (NP) to prepare new microporous organic-inorganic hybrid adsorbents. The amount and arrangement of CS intercalated was different by the kind of the host metal ions. CS4 cavity axis was perpendicular for the Mg-Al LDH basal layer and parallel for the Zn-Al LDH basal layer, while CS6 cavity axis was perpendicular for both the LDH basal layers. In the BET surface area measurement, the surface area of the Zn-Al/CS4/LDH was four times than that of the Mg-Al/CS4/LDH, expecting that the former has higher adsorption capacity than the latter. In fact, the adsorption ability of the CS/LDHs for BA and NP in aqueous solution was found to be larger in the Zn-Al/CS4/LDH than in the Mg-Al/CS4/LDH. In addition, the adsorption ability of both the LDHs was larger in the CS6/LDHs than in the CS4/LDHs. These results were explained by the difference in the amount and arrangement of CS intercalated in the LDH interlayer space.

Sasaki, Satoru [Department of Material Science, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio [Department of Material Science, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Material Science, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sasaki, Akira [Department of Sanitary Science, Research Institute for Environmental Sciences and Public Health of Iwate Prefecture, 1-36-1 Iiokashinden, Morioka 020-0852 (Japan); Nakayama, Hirokazu [Department of Functional Molecular Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakitamachi, Higashinada-ku, Kobe 658-8558 (Japan); Narita, Eiichi [Department of Material Science, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan)]. E-mail: enarita@iwate-u.ac.jp

2006-04-15

47

High pseudocapacitive cobalt carbonate hydroxide films derived from CoAl layered double hydroxides  

NASA Astrophysics Data System (ADS)

A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles).A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles). Electronic supplementary information (ESI) available: Detailed experimental procedure, specific capacitance calculation, EDS and FTIR results, electrochemical results of CoAl-LDH and SEM image. See DOI: 10.1039/c2nr30617d

Lu, Zhiyi; Zhu, Wei; Lei, Xiaodong; Williams, Gareth R.; O'Hare, Dermot; Chang, Zheng; Sun, Xiaoming; Duan, Xue

2012-05-01

48

Thermal decomposition behavior of Cu–Al layered double hydroxide, and ethylenediaminetetraacetate-intercalated Cu–Al layered double hydroxide reconstructed from Cu–Al oxide for uptake of Y{sup 3+} from aqueous solution  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. ? The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. ? The edta·Cu–Al LDH could selectively take up rare earth ions from a mixed solution. -- Abstract: CO{sub 3}{sup 2?}-intercalated Cu–Al layered double hydroxide (CO{sub 3}·Cu–Al LDH) was calcined to yield Cu–Al oxide, and then ethylenediaminetetraacetate-intercalated Cu–Al LDH (edta·Cu–Al LDH) was prepared by reconstructing Cu–Al oxide in edta solution. Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. The production of Cu–Al oxide was caused by the thermal decomposition of CO{sub 3}·Cu–Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO{sub 3}·Cu–Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO{sub 3}{sup 2?} intercalated in the interlayers. The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. The uptake of Y{sup 3+} was caused not only by the chelating function of Hedta{sup 3?} in the interlayer but also by the chemical behavior of Cu–Al LDH itself. The edta·Cu–Al LDH was found to selectively take up rare earth ions from a mixed solution. The degree of uptake was high, in the order Sc{sup 3+} > Y{sup 3+} > La{sup 3+} for all time durations, which was attributable to differences among the stabilities of Sc(edta){sup ?}, Y(edta){sup ?} and La(edta){sup ?}.

Kameda, Tomohito, E-mail: kameda@env.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)] [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Hoshi, Kazuaki; Yoshioka, Toshiaki [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)] [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2012-12-15

49

Concomitant synthesis of highly crystalline Zn-Al layered double hydroxide and ZnO: phase interconversion and enhanced photocatalytic activity.  

PubMed

Metal oxide/hydroxide with hierarchical nanostructures has emerged as one of the most promising materials for their unique, attractive properties and feasibility of applications in various fields. In this report, a concomitant synthesis of crystalline zinc aluminum layered double hydroxide (ZnAl-LDH) nanostructure and ZnO is presented using Al substrate as template. Studies on interconversion of ZnO to LDH phase in bulk solution under hydrothermal conditions produced Al-doped ZnO (AZO) in one case, and in other, it improves the crystallinity of LDH film templated on Al substrate. In presence of Al salt, the self-limiting growth nature of plate LDH turned to non-self-limiting. Materials obtained during phase transition, AZO in bulk solution and crystalline porous ZnAl-LDH on substrate, have been demonstrated as effective photocatalysts for decomposition of congo red in aqueous medium. PMID:22024370

Dutta, Kingshuk; Das, Somnath; Pramanik, Amitava

2012-01-15

50

Anticancer Drug-Incorporated Layered Double Hydroxide Nanohybrids and Their Enhanced Anticancer Therapeutic Efficacy in Combination Cancer Treatment  

PubMed Central

Objective. Layered double hydroxide (LDH) nanoparticles have been studied as cellular delivery carriers for anionic anticancer agents. As MTX and 5-FU are clinically utilized anticancer drugs in combination therapy, we aimed to enhance the therapeutic performance with the help of LDH nanoparticles. Method. Anticancer drugs, MTX and 5-FU, and their combination, were incorporated into LDH by reconstruction method. Simply, LDHs were thermally pretreated at 400°C, and then reacted with drug solution to simultaneously form drug-incorporated LDH. Thus prepared MTX/LDH (ML), 5-FU/LDH (FL), and (MTX + 5-FU)/LDH (MFL) nanohybrids were characterized by X-ray diffractometer, scanning electron microscopy, infrared spectroscopy, thermal analysis, zeta potential measurement, dynamic light scattering, and so forth. The nanohybrids were administrated to the human cervical adenocarcinoma, HeLa cells, in concentration-dependent manner, comparing with drug itself to verify the enhanced therapeutic efficacy. Conclusion. All the nanohybrids successfully accommodated intended drug molecules in their house-of-card-like structures during reconstruction reaction. It was found that the anticancer efficacy of MFL nanohybrid was higher than other nanohybrids, free drugs, or their mixtures, which means the multidrug-incorporated LDH nanohybrids could be potential drug delivery carriers for efficient cancer treatment via combination therapy. PMID:24860812

Lee, Gyeong Jin; Kang, Joo-Hee

2014-01-01

51

Polarized immune responses modulated by layered double hydroxides nanoparticle conjugated with CpG.  

PubMed

Modulation of the immune response is an important step in the induction of protective humoral and cellular immunity against pathogens. In this study, we investigated the possibility of using a nanomaterial conjugated with the toll-like receptor (TLR) ligand CpG to modulate the immune response towards the preferred polarity. MgAl-layered double hydroxide (LDH) nanomaterial has a very similar chemical composition to Alum, an FDA approved adjuvant for human vaccination. We used a model antigen, ovalbumin (OVA) to demonstrate that MgAl-LDH had comparable adjuvant activity to Alum, but much weaker inflammation. Conjugation of TLR9 ligand CpG to LDH nanoparticles significantly enhanced the antibody response and promoted a switch from Th2 toward Th1 response, demonstrated by a change in the IgG2a:IgG1 ratio. Moreover, immunization of mice with CpG-OVA-conjugated LDH before challenge with OVA-expressing B16/F10 tumor cells retarded tumor growth. Together, these data indicate that LDH nanomaterial can be used as an immune adjuvant to promote Th1 or Th2 dominant immune responses suitable for vaccination purposes. PMID:25145853

Yan, Shiyu; Rolfe, Barbara E; Zhang, Bing; Mohammed, Yousuf H; Gu, Wenyi; Xu, Zhi P

2014-11-01

52

Hierarchical construction of an ultrathin layered double hydroxide nanoarray for highly-efficient oxygen evolution reaction.  

PubMed

Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (?) of 257 mV is needed for a current density of 80 mA cm(-2) with a Tafel slope of 53 mV per decade. The hierarchical LDH nanoarray also shows excellent structural stability in alkaline media. After continuous testing under a high OER current density (?300 mA cm(-2)) for 10 h, the sample maintains the ordered hierarchical structure with no significant deactivation of the catalytic properties. PMID:25162938

Yang, Qiu; Li, Tian; Lu, Zhiyi; Sun, Xiaoming; Liu, Junfeng

2014-10-21

53

Rapid Exchange between Atmospheric CO2 and Carbonate Anion Intercalated within Magnesium Rich Layered Double Hydroxide.  

PubMed

The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation. PMID:25275963

Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

2014-10-22

54

Preparation of Mg-Al layered double hydroxides intercalated with alkyl sulfates and investigation of their capacity to take up N, N-dimethylaniline from aqueous solutions  

NASA Astrophysics Data System (ADS)

This study examined the effect of the interlayer spacing of a Mg-Al layered double hydroxide (Mg-Al LDH) on the ability of the Mg-Al LDH to take up a nonionic organic material. Mg-Al LDHs, intercalated with 1-propanesulfonate (PS -), 1-hexanesulfonate (HS -), and 1-dodecanesulfonate (DS -), were prepared by coprecipitation, yielding PS·Mg-Al LDH, HS·Mg-Al LDH, and DS·Mg-Al LDH, respectively. The increase in the alkyl chain lengths of the Mg-Al LDHs (PS - < HS - < DS -) resulted in the perpendicular orientation of the organic acid anions in the interlayer of Mg-Al LDH, which in turn resulted in more organic acid anions being accommodated in the interlayer space. An organic acid anion with a large molecular length was more easily intercalated in the interlayer of Mg-Al LDH than one with a small molecular length. This was attributed to the hydrophobic interaction between the alkyl chains, affecting the intercalation of the organic acid anions. The uptake of N, N-dimethylaniline (DMA) by Mg-Al LDHs increased in the order PS·Mg-Al LDH < HS·Mg-Al LDH < DS·Mg-Al LDH. The uptake was attributed to the hydrophobic interactions between DMA and the intercalated PS -, HS -, and DS -. Thus, Mg-Al LDH, which has a lot of large interlayer spacings when intercalated with organic acid anions, can take up a large number of DMA molecules from an aqueous solution.

Kameda, Tomohito; Tsuchiya, Yuuichi; Yamazaki, Takashi; Yoshioka, Toshiaki

2009-12-01

55

Amperometric nitrite biosensor based on a gold electrode modified with cytochrome c on Nafion and Cu-Mg-Al layered double hydroxides  

Microsoft Academic Search

An amperometric biosensor for nitrite was prepared by immobilizing cytochrome c (Cyt c) on a gold electrode that was modified\\u000a with Nafion and a Cu-Mg-Al layered double hydroxide (Cu-LDH). The Cu-LDH was characterized by Fourier transform infrared spectroscopy\\u000a and powder X-ray diffraction. The UV-visible spectrum suggests that Cyt c retains its native conformation in the modified\\u000a film. The direct electrochemical

Huanshun Yin; Yunlei Zhou; Tao Liu; Lin Cui; Shiyun Ai; Yanyan Qiu; Lusheng Zhu

2010-01-01

56

GEOC Andrew Stack Sunday, March 16, 2014 28 Spectroscopic evidence of mixed divalent metal layered double hydroxide phase formation from the cosorption  

E-print Network

the formation of green rust and Fe(II)Al(III)LDH from Fe(II)/Zn cosorption reactions with pyrophyllite and Al2O in the formation of a green rust, rather than a Fe(II)Al(III)LDH. The Zn Kedge data (Figure 1) show the formation layered double hydroxide phase formation from the cosorption of Fe(II) and Zn with Albearing mineral

Sparks, Donald L.

57

Non-isothermal crystallization kinetics and activity of filler in polypropylene\\/Mg–Al layered double hydroxide nanocomposites  

Microsoft Academic Search

The non-isothermal crystallization behaviour of Mg–Al layered double hydroxide (LDH)\\/polypropylene (PP) nanocomposites prepared by melt-dispersion was investigated through differential scanning calorimetry and discussed in comparison with that of montmorillonite (MMT)\\/PP ones. Combined effects of the LDH interlamellar modification and blending the PP with maleic anhydride-grafted PP (PP-g-MAH) and maleic anhydride-grafted poly(styrene-co-ethylenebutylene-co-styrene) (SEBS-g-MAH) were analysed. Different approaches were applied to determinate

M. Ardanuy; J. I. Velasco; V. Realinho; D. Arencón; A. B. Martínez

2008-01-01

58

Large-scale simulations of layered double hydroxide nanocomposite materials  

NASA Astrophysics Data System (ADS)

Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up to 480 base pairs in length intercalated within LDHs. Our models are found to be in agreement with experimental observations, according to which hydration is a crucial factor in determining the structural stability of DNA. At elevated tem peratures and pressures, the structural stability of LDH-intercalated DNA is substantially enhanced as compared to DNA in bulk water. We also discuss how the properties of LDHs are modified due to DNA intercalation. Our studies show that LDHs are flexible enough to deform around bulky intercalants such as DNA. The flexibility of layered materials has been shown to affect the pathway by which intercalation occurs. Recent experimental studies of LDHs have shown that these minerals can form staged intermediate structures during intercalation. However, the mechanism which produces staged structures remains un determined. We simulated three differently stacked structures and show that even though the structures under study are all energetically very similar, overall there is greater diffusion of DNA strands in a Daumas-Herold configuration compared to a Rudorff model and a stage-1 structure. The picture on the titlepage was produced using a visualisation package called Visual Molecular Dy namics (VMD) and represents a plasmid strand of DNA containing 480 base pairs intercalated inside an LDH. Only one layer of the LDH is displayed and water molecules have been hidden in order to aid viewing of the structure. The visualisation was produced from our largest simulation which contained 1,157,038 atoms, with lateral dimensions of 588.3Ax677.7A.

Thyveetil, Mary-Ann

59

Layered double hydroxide-carbon dot composite: high-performance adsorbent for removal of anionic organic dye.  

PubMed

It would be of significance to design a green composite for efficient removal of contaminants. Herein, we fabricated a facile and environmentally friendly composite via direct assembly of surface passivated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (LDH). The resulting LDH-carbon dot composites were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and N2 adsorption-desorption technique. The adsorption performances of the resulting LDH-carbon dot composites were evaluated for the removal of anionic methyl blue dye. Taking advantage of the combined benefits of LDH and carbon dots, the as-prepared composites exhibited high uptake capability of methyl blue (185 mg/g). The adsorption behavior of this new adsorbent fitted well with Langmuir isotherm and the pseudo-second-order kinetic model. The reasons for the excellent adsorption capacity of methyl blue on the surface of the LDH-carbon dot hybrid were further discussed. A probable mechanism was speculated to involve the cooperative contributions of hydrogen bonding between methyl blue and carbon dots and electrostatic attraction between methyl blue and LDH, in the adsorption process. This work is anticipated to open up new possibilities in fabricating LDH-carbon dot materials in dealing with anionic dye pollutants. PMID:25313875

Zhang, Manlin; Yao, Qingfeng; Lu, Chao; Li, Zenghe; Wang, Wenxing

2014-11-26

60

Removal of arsenate from aqueous solution by nanocrystalline Mg/Al layered double hydroxide: sorption characteristics, prospects, and challenges.  

PubMed

Removal of arsenate (As(V)) from aqueous solution using both nanocrystalline and coprecipitated Mg/Al layered double hydroxides (LDHs) was examined under different sorption/desorption conditions. The surface area, pore volume, and pore size of the nanocrystalline LDH were significantly higher than those of the coprecipitated LDH, thus resulting in a higher As(V) sorption maximum than the coprecipitated LDH. The calculated activation energy (E(a)) value was 24.7 kJ/mol, suggesting the occurrence of anion exchange process for As(V) removal by the nanocrystalline LDH. The predominance of anion exchange process was further supported by the investigation of ionic strength effect, and XRD and FTIR analyses. The effect of aqueous matrix on As(V) sorption by the nanocrystalline LDH was found to increase in the order of nitrate < silica < sulfate < carbonate < phosphate. Regeneration study showed that a secondary sorption mechanism might occur concurrently for the As(V) sorption by nanocrystalline LDH besides the predominant anion exchange process. Prospects and challenges for practical application of the nanocrystalline LDH were also discussed in the latter part of this study. PMID:20351419

Goh, K H; Lim, T T; Dong, Z L

2010-01-01

61

Layered Double Hydroxides as an Effective Additive in Polymer Gelled Electrolyte based Dye-Sensitized Solar Cells.  

PubMed

Layered double hydroxides (LDH), a class of anionic clay materials, were developed as an effective additive for polymer gelled electrolytes for use in dye-sensitized solar cells (DSSC). Carbonate and chloride intercalated Zn-Al LDHs, ZnAl-CO3 LDH, and ZnAl-Cl LDH were prepared with coprecipitation methods. The addition of the two LDHs significantly improved, in terms of power conversion efficiency (PCE), over the plain poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gelled electrolyte and competed favorably with the liquid electrolyte based DSSCs, 8.13% for the liquid electrolyte, 7.48% for the plain PVDF-HFP gelled electrolyte, 8.11% for the ZnAl-CO3 LDH/PVDF-HFP gelled electrolyte, and 8.00% for the ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The good performance in PCEs achieved by the LDH-loaded DSSCs came mainly from the significant boost in open circuit voltages (Voc), from 0.74 V for both the liquid electrolyte and PVDF-HFP gelled electrolyte based DSSCs to 0.79 V for both the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The boost in Voc was contributed mainly by the positive shift in redox potential of the redox couple, I(-)/I3(-), as revealed from cyclic voltammetry analyses. As for the long-term stability, PCE retention rates of 96 and 99% after 504 h were achieved by the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs, respectively, appreciably better than 92% achieved by the liquid electrolyte based one after 480 h. PMID:25245099

Ho, Hsu-Wen; Cheng, Wei-Yun; Lo, Yu-Chun; Wei, Tzu-Chien; Lu, Shih-Yuan

2014-10-22

62

Cyanide Self-Addition, Controlled Adsorption, and Other Processes at Layered Double Hydroxides  

NASA Astrophysics Data System (ADS)

Layered double hydroxides (LDH) are anion-exchanging materials of the type M(III)-M(II)_x(OH)_(2x+2)Y that occur abundantly in nature, and can concentrate, protect, and activate simple organic anionic species of possible relevance to the earliest organisms. We now wish to report progress in the following areas: 1) Internal vs. external uptake of anions. Ferrocyanide does not displace carbonate from synthetic hydrotalcite (Mg:Al LDH carbonate) but is nevertheless taken up on the outside of the particles. In other cases, anion uptake is controlled by specific hydrogen bonding requirements rather than by charge density alone, a feature that can be used to control whether uptake will be both internal and external, or external only. These two findings taken together have important implications for specific catalysis by LDH, since specific hydrogen bonding will affect the individual and relative conformations of substrate anions, and anions occupying space in the interlayer will be under tighter constraints than those adsorbed externally. 2) Specific reactions catalyzed by LDH. We have found that the LDH Mg_2Al(OH)_6Cl catalyzes the self-addition of cyanide, to give in a one-pot reaction at low concentrations an increased yield of diaminomaleonitrile and in addition, at higher (>= 0.05M) concentrations, a purple-pink material that adheres to the LDH. We are investigating whether this reaction also occurs with hydrotalcite itself, what is the minimum effective concentration of cyanide, and what can be learned about the products and how they compare with those reported at high HCN concentrations in the absence of catalyst.

Boclair, Joseph W.; Braterman, Paul S.; Brister, Brian D.; Jiang, Jianping; Lou, Shaowei; Wang, Zhiming; Yarberry, Faith

2001-02-01

63

Fire and thermal properties of layered double hydroxides and polyurea nanocomposites  

NASA Astrophysics Data System (ADS)

Layered double hydroxide (LDH) intercalated with linear alkyl carboxylates (CH3(CH2)n COO-, n = 8, 10, 12, 14, 16, 20), borate and benzyl anions were prepared. The effect on fire and thermal properties of the mode of preparation for LDHs (i.e. ion exchange, coprecipitation and rehydration of the calcined LDH methods) has been studied. After characterization, the LDHs were used to prepare nanocomposites with a range of polar and non-polar polymers. Characterization of the LDHs and the nanocomposites was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), transmission electron microscopy (TEM) and cone calorimetry. FTIR and XRD analyses confirmed the presence of the charge balancing anions in the galleries of the LDHs. Improvements in fire and thermal properties of the nanocomposites were observed. The cone calorimeter revealed that the addition of LDHs reduces the peak heat release rate significantly. LDHs were combined with commercial fire retardants. Synergistic effects were observed in both TGA and cone calorimetry for formulations containing both LDH and ammonium polyphosphate (APP). Physical and chemical interactions between LDH and APP are responsible for the observed synergy in thermal stability and fire performance.

Nyambo, Calistor

64

Facile assembly for fast construction of intercalation hybrids of layered double hydroxides with anionic metalloporphyrin.  

PubMed

Anionic manganese tetrasulfonatophenyl porphyrin (MnTSPP) has been intercalated into the interlamellar space of Mg-Al and Ni-Al layered double hydroxides (LDHs) through the exfoliation/restacking approach by using exfoliated LDH nanosheets and guest molecules as building blocks. The obtained hybrids were characterized by a variety of analytical techniques such as CHN analysis, XRD, FTIR, SEM, HRTEM, UV-vis spectroscopy and thermal analysis. Interlayer spacings determined from XRD patterns reveal a perpendicular orientation of the MnTSPP anions between the hyroxylated layers of both LDHs. The results of zeta potential measurements give information about the surface charge change of LDH nanoparticles associated with the spontaneous coassembly process. The catalytic performance of the heterogeneous catalysts MnTSPP/Mg-Al LDH2.0 and MnTSPP/Ni-Al LDH1.0 for the epoxidation of cyclohexene was investigated using molecular oxygen as an oxidant and isobutylaldehyde as a co-reductant. The intercalated hybrids appear to be promising catalysts owing to their good catalytic activity and selectivity. PMID:24849716

Ma, Juanjuan; Liu, Lin; Li, Shanzhong; Chen, Yonghao; Zhuo, Meng; Shao, Feng; Gong, Junyan; Tong, Zhiwei

2014-07-14

65

Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products  

SciTech Connect

Cu-Al layered double hydroxides (LDHs) with [Cu]/[Al] ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH){sub 2} and CuCO{sub 3} and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 deg. C), hydrothermally (150 deg. C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 deg. C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 deg. C itself. Reductive decomposition yields a composite of Cu{sub 2}O and Al(OH){sub 3}, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu{sub 2}O (<1 {mu}m). - Graphical abstract: SEM image of (a) the Cu{sub 2}O-Al(OH){sub 3} composite obtained on reductive decomposition of CuAl{sub 4}-LDH and (b) Cu{sub 2}O obtained on leaching of Al(OH){sub 3} from (a).

Britto, Sylvia [Department of Chemistry, Central College, Bangalore University, Bangalore 560 001 (India); Vishnu Kamath, P., E-mail: vishnukamath8@hotmail.co [Department of Chemistry, Central College, Bangalore University, Bangalore 560 001 (India)

2009-05-15

66

Photo-switching in a hybrid material made of magnetic layered double hydroxides intercalated with azobenzene molecules.  

PubMed

A magnetic photoresponsive hybrid material is prepared by intercalation of a switchable trans-azobenzene-4,4'-dicarboxylate guest in the interlamellar space offered by a ferromagnetic Co(2+)Al(3+)-layered double hydroxide (LDH) host. Magnetic switching is triggered by compression/modification of the in-plane structure coupled the guest's isomerization causing a change in the magnetization of 27%. PMID:24706546

Abellán, Gonzalo; Coronado, Eugenio; Martí-Gastaldo, Carlos; Ribera, Antonio; Jordá, Jose Luis; García, Hermenegildo

2014-06-25

67

Mechano-hydrothermal synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxides  

SciTech Connect

A mechano-hydrothermal method was developed to synthesize Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) from MgO, Al{sub 2}O{sub 3} and NaNO{sub 3} as starting materials. A two-step synthesis was conducted, that is, a mixture of MgO and Al{sub 2}O{sub 3} was milled for 1 h, followed by hydrothermal treatment with NaNO{sub 3} solution. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and elemental analyses. Pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The process is advantageous in terms of low reaction temperature and short reaction time compared with the conventional hydrothermal method, and the target products are of high crystallinity, good dispersion and regular shape compared with the conventional mechanochemical method. - Graphical abstract: The novel mechano-hydrothermal route to synthesize LDH has advantages in low reaction temperature and short reaction time, and the target product was of high crystallinity, good dispersion and regular shape. Display Omitted - Highlights: • A mechano-hydrothermal route was developed for layered double hydroxide synthesis. • Synthesis could be achieved at low temperature and in a short time. • Resulting layered double hydroxide samples were well dispersed and of regular shape. • A dissolution–recrystallization mechanism was proposed for the formation process.

Zhang, Fengrong [Environment Research Institute, Shandong University, Jinan 250100 (China); Du, Na; Song, Shue [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China); Liu, Jianqiang [School of Physics, Shandong University, Jinan 250100 (China); Hou, Wanguo, E-mail: wghou@sdu.edu.cn [Environment Research Institute, Shandong University, Jinan 250100 (China); Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China)

2013-10-15

68

Intercalation of biomolecules into NiAl-NO 3 layered double hydroxide films synthesized in situ on anodic alumina/aluminium support  

NASA Astrophysics Data System (ADS)

Layered double hydroxide (LDH) films were synthesized in situ on anodic alumina/aluminium (AAO/Al). Glucose oxidase (GOD) and L-ascorbic acid (vitamin C, VC) were intercalated respectively into the in-situ grown LDH films by anion-exchange in aqueous solutions. Dodecylsulfate (SDS) was used to expand the lamellar structure before GOD intercalation into the LDH film. The resulting products were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). The results showed that VC and GOD were successfully intercalated into the in-situ synthesized LDH film. These biomolecules loaded LDH films could have potential applications in electrode modification, safe storage and effective delivery of bioactive compounds.

Zhao, Hua-Zhang; Chang, Ying-Yue; Yang, Jing; Yang, Qin-Zheng

2013-03-01

69

Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate  

SciTech Connect

The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO{sub 3}{sup -} compound and its H{sub 2}PO{sub 4}{sup -}-intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO{sub 4}{sup 2-} caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil. -- Graphical abstract: We synthesized phosphate-intercalated Ca-Fe-LDH materials that can act as bifunctional inorganic vectors for the slow release of phosphate fertilizer and also the neutralization of acid soil. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. Display Omitted Research Highlights: {yields} The phosphate forms of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) were synthesized via co-precipitation method. The crystal structure, bonding character, and release kinetics of phosphate of the phosphate-intercalates were investigated. These Ca-Fe-LDH materials are applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho [Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Hwang, Seong-Ju, E-mail: hwangsju@ewha.ac.k [Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

2011-01-15

70

Ultrathin cobalt-manganese layered double hydroxide is an efficient oxygen evolution catalyst.  

PubMed

Cost-effective production of solar fuels requires robust and earth-abundant oxygen evolution reaction (OER) catalysts. Herein, we report that ultrathin nanoplates of cobalt-manganese layered double hydroxide (CoMn LDH) are a highly active and stable oxygen evolution catalyst. The catalyst was fabricated by a one-pot coprecipitation method at room temperature, and its turnover frequency (TOF) is more than 20 times higher than the TOFs of Co and Mn oxides and hydroxides, and 9 times higher than the TOF of a precious IrO2 catalyst. The activity of the catalyst was promoted by anodic conditioning, which was proposed to form amorphous regions and reactive Co(IV) species on the surface. The stability of the catalyst was demonstrated by continued electrolysis. PMID:25380057

Song, Fang; Hu, Xile

2014-11-26

71

Exfoliation of layered double hydroxides for enhanced oxygen evolution catalysis  

NASA Astrophysics Data System (ADS)

The oxygen evolution reaction is a key reaction in water splitting. The common approach in the development of oxygen evolution catalysts is to search for catalytic materials with new and optimized chemical compositions and structures. Here we report an orthogonal approach to improve the activity of catalysts without alternating their compositions or structures. Specifically, liquid phase exfoliation is applied to enhance the oxygen evolution activity of layered double hydroxides. The exfoliated single-layer nanosheets exhibit significantly higher oxygen evolution activity than the corresponding bulk layered double hydroxides in alkaline conditions. The nanosheets from nickel iron and nickel cobalt layered double hydroxides outperform a commercial iridium dioxide catalyst in both activity and stability. The exfoliation creates more active sites and improves the electronic conductivity. This work demonstrates the promising catalytic activity of single-layered double hydroxides for the oxygen evolution reaction.

Song, Fang; Hu, Xile

2014-07-01

72

Multi-level three-dimensional Mg-Al layered double hydroxide hierarchical microstructures with enhanced basic catalytic property.  

PubMed

Novel three-dimensional (3D) rosette-like carbonate-type Mg-Al layered double hydroxide (MgAl-LDH) hierarchical microstructures were fabricated successfully by a surfactant-assisted coprecipitation method in the presence of hexamethylenetetramine as precipitant, and the morphology-dependent basic catalytic property was exploited. The morphologies of MgAl-LDH aggregates were diversified depending on the synthesis parameters including the type of precipitant, concentration of sodium stearate surfactant, and hydrothermal aging time. Specifically, the morphology of MgAl-LDH particles could change progressively from platelet-like aggregates to rosette-like microspheres with the increasing concentration of sodium stearate. A possible formation mechanism for special 3D flower-like MgAl-LDH microstructures was proposed based on the synergistic effect of precipitant with surfactant. Moreover, the resulting activated rosette-like MgAl-LDH, which was prepared through calcination-rehydration process, showed a higher catalytic activity in the transesterification of tributyrin with methanol, compared with that derived from the conventional platelet-like MgAl-LDH precursor, which was attributed to its higher specific basicity originating from multi-level hierarchical superstructure offering an advantage in contact with more exposed base sites. PMID:25036381

Yu, Jiaying; Fan, Guoli; Yang, Yang; Li, Feng

2014-10-15

73

Electrochemical synthesis of nickel-iron layered double hydroxide: application as a novel modified electrode in electrocatalytic reduction of metronidazole.  

PubMed

A new and simple approach based on the electrochemical method was used for preparation of reproducible nanostructure thin film of Ni/Fe-layered double hydroxides (Ni/Fe-LDH) on the glassy carbon electrode (GCE). The electrochemical behavior of the Ni/Fe-LDH deposited on GCE electrode is studied. Study of the scanning electron microscopy shows the formation of a nanostructure thin film on the glassy carbon electrode. Electrochemical experiments show that Ni/Fe-LDH modified glassy carbon electrode exhibits excellent electrocatalytic reduction activity with Metronidazole. The method was successfully applied for the analysis of Metronidazole in tablets. The results were favorably compared to those obtained by the reported BP method. PMID:24411366

Nejati, Kamellia; Asadpour-Zeynali, Karim

2014-02-01

74

Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane  

PubMed Central

Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core–shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core–shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy. PMID:25364245

Yan, Mina; Zhang, Zhaoguo; Cui, Shengmiao; Lei, Ming; Zeng, Ke; Liao, Yunhui; Chu, Weijing; Deng, Yihui; Zhao, Chunshun

2014-01-01

75

Preparation of 5-benzotriazolyl-4-hydroxy-3-sec-butylbenzenesulfonate anion-intercalated layered double hydroxide and its photostabilizing effect on polypropylene  

SciTech Connect

An organic UV absorber has been intercalated into a layered double hydroxide (LDH) host by ion-exchange method using ZnAl-NO{sub 3}-LDH as a precursor with an aqueous solution of the sodium salt of 5-benzotriazolyl-4-hydroxy-3-sec-butylbenzenesulfonic acid (BZO). After intercalation of the UV absorber, the interlayer distance in the LDHs increases from 0.89 to 2.32 nm. Infrared spectra and thermogravimetry and differential thermal analysis (TG-DTA) curves reveal the presence of a complex system of supramolecular host-guest interactions. The thermostability of BZO is markedly enhanced by intercalation in the LDH host. ZnAl-BZO-LDHs/polypropylene composite materials exhibit excellent UV photostability. - Graphical abstract: Intercalation of an organic UV absorber in a layered double hydroxide host leads to an enhancement of its photo- and thermal stability.

Li Dianqing [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Tuo Zhenjun [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Evans, David G. [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Duan Xue [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)]. E-mail: duanx@mail.buct.edu.cn

2006-10-15

76

Abstract We had previously shown that succinic acid production in a pfl ldhA double mutant strain of Escheri-  

E-print Network

succinic acid production. More reduced carbon substrate sorbitol was thus examined for the possibilityAbstract We had previously shown that succinic acid production in a pfl ldhA double mutant strain gene, produced a considerable amount of malic acid along with the desired product, succinic acid

77

Layered double hydroxides as supports for intercalation and sustained release of antihypertensive drugs  

SciTech Connect

Zn/Al layered double hydroxides (LDHs) were intercalated with the anionic antihypertensive drugs Enalpril, Lisinopril, Captopril and Ramipril by using coprecipitation or ion-exchange technique. TG-MS analyses suggested that the thermal stability of Ena{sup -}, Lis{sup -} (arranged with monolayer, resulted from X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) analysis was enhanced much more than Cap{sup -} and Ram{sup -} (arranged with bilayer). The release studies show that the release rate of all samples markedly decreased in both pH 4.25 and 7.45. However, the release time of Ena{sup -}, Lis{sup -} were much longer compared with Cap{sup -}, Ram{sup -} in both pH 4.25 and 7.45, it is possible that the intercalated guests, arranged with monolayer in the interlayer, show lesser repulsive force and strong affinity with the LDH layers. And the release data followed both the Higuchi-square-root law and the first-order equation well. Based on the analysis of batch release, intercalated structural models as well as the TG-DTA results, we conclude that for drug-LDH, stronger the affinity between intercalated anions and the layers is, better the thermal property and the stability to the acid attack of drug-LDH, and the intercalated anions are easier apt to monolayer arrangement within the interlayer, were presented. - Graphical abstract: A series of antihypertensive drugs including Enalpril, Lisinopril, Captopril and Ramipril were intercalated into Zn/Al-NO{sub 3}-LDHs successfully by coprecipitation or ion-exchange technique. We focus on the structure, thermal property and low/controlled release property of as-synthesized drug-LDH composite intended for the possibility of applying these LDH-antihypertensive nanohybrids in drug delivery and controlled release systems.

Xia Shengjie [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Ni Zheming [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)], E-mail: jchx@zjut.edu.cn; Xu Qian; Hu Baoxiang; Hu Jun [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

2008-10-15

78

Synthesis, characterization, and controlled release anticorrosion behavior of benzoate intercalated Zn-Al layered double hydroxides  

SciTech Connect

Graphical abstract: The benzoate anion released from Zn-Al LDHs provides a more effective long-term protection against corrosion of Q235 carbon steel in 3.5% NaCl solution. Highlights: {yields} A benzoate anion corrosion inhibitor intercalated Zn-Al layered double hydroxides (LDHs) has been assembled by coprecipitation method. {yields} The kinetic simulation indicates that the ion-exchange one is responsible for the release process and the diffusion through particle is the rate limiting step. {yields} A significant reduction of the corrosion rate is observed when the LDH nanohybrid is present in the corrosive media. -- Abstract: Corrosion inhibitor-inorganic clay composite including benzoate anion intercalated Zn-Al layered double hydroxides (LDHs) are assembled by coprecipitation. Powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectrum analyses indicate that the benzoate anion is successfully intercalated into the LDH interlayer and the benzene planes are vertically bilayer-positioned as a quasi-guest ion-pair form in the gallery space. Kinetic simulation for the release data, XRD and FT-IR analyses of samples recovered from the release medium indicate that ion-exchange is responsible for the release process and diffusion through the particle is also indicated to be the rate-limiting step. The anticorrosion capabilities of LDHs loaded with corrosion inhibitor toward Q235 carbon steel are analyzed by polarization curve and electrochemical impedance spectroscopy methods. Significant reduction of corrosion rate is observed when the LDH nanohybrid is present in the corrosive medium. This hybrid material may potentially be applied as a nanocontainer in self-healing coatings.

Wang, Yi [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)] [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Zhang, Dun, E-mail: zhangdun@qdio.ac.cn [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)] [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)

2011-11-15

79

Optimization of UV absorptivity of layered double hydroxide by intercalating organic UV-absorbent molecules.  

PubMed

Intercalation of Zn/Al layered double hydroxide (LDH) with benzophenone 9 (B9), a strong ultraviolet (UV) absorber, had been carried out by two different routes; co-precipitation and ion exchange method. Powder X-ray diffraction (PXRD) patterns of co-precipitated (ZB9C) and ion exchanged product (ZB91) showed basal spacing of 15.9 angstrom and 16.6 angstrom, respectively, as a result of the intercalation of B9 anions into the lamellae spaces of LDH. Intercalation was further confirmed by Fourier transform infrared spectra (FTIR), carbon, hydrogen, nitrogen and sulfur (CHNS) and thermogravimetric and differential thermogravimetric (TGA/DTG) studies. UV-vis absorption properties of the nanocomposite was investigated with diffuse reflectance UV-visible spectrometer and showed broader UV absorption range. Furthermore, stability of sunscreen molecules in LDH interlayer space was tested in deionized water, artificial sea water and skin pH condition to show slow deintercalation and high retention in host. Cytotoxicity study of the synthesized nanocomposites on human dermal fibroblast (HDF) cells shows no significant cytotoxicity after 24 h exposure for test concentrations up to 25 microg/mL. PMID:25016649

Mohsin, Sumaiyah Megat Nabil; Hussein, Mohd Zobir; Sarijo, Siti Halimah; Fakurazi, Sharida; Arulselvan, Palanisamy; Taufiq-Yap, Yun Hin

2014-08-01

80

Aluminium substitution in iron(II III)-layered double hydroxides: Formation and cationic order  

NASA Astrophysics Data System (ADS)

The formation and the modifications of the structural properties of an aluminium-substituted iron(II-III)-layered double hydroxide (LDH) of formula Fe4IIFe(2-6y)IIIAl6yIII (OH) 12 SO 4, 8H 2O are followed by pH titration curves, Mössbauer spectroscopy and high-resolution X-ray powder diffraction using synchrotron radiation. Rietveld refinements allow to build a structural model for hydroxysulphate green rust, GR(SO 42-), i.e. y=0, in which a bilayer of sulphate anions points to the Fe 3+ species. A cationic order is proposed to occur in both GR(SO 42-) and aluminium-substituted hydroxysulphate green rust when y<0.08. Variation of the cell parameters and a sharp decrease in average crystal size and anisotropy are detected for an aluminium content as low as y=0.01. The formation of Al-GR(SO 42-) is preceded by the successive precipitation of Fe III and Al III (oxy)hydroxides. Adsorption of more soluble Al III species onto the initially formed ferric oxyhydroxide may be responsible for this slowdown of crystal growth. Therefore, the insertion of low aluminium amount ( y˜0.01) could be an interesting way for increasing the surface reactivity of iron(II-III) LDH that maintains constant the quantity of the reactive Fe II species of the material.

Ruby, Christian; Abdelmoula, Mustapha; Aissa, Rabha; Medjahdi, Ghouti; Brunelli, Michela; François, Michel

2008-09-01

81

Synthesis and characterization of metal (Core) - layered double hydroxide (Shell) nanostructures  

NASA Astrophysics Data System (ADS)

Layered double hydroxides (LDH) which belong to a class of inorganic ceramic layered materials have been studied since the mid-19th century for a variety of applications including catalysis, anion exchange, adsorbents and antacid, but more recently as a potential drug and gene delivery platform. Drug delivery platforms based on nano-sized geometries are nanovectors which promise a revolutionary impact on the therapy and imaging of various types of cancers and diseases. To date, various polymeric platforms have been the focus of intense research, but the development of inorganic, bio-hybrid nanoparticles for therapeutics and molecular imaging are at a stage of infancy. The hybridization of LDH with bioactive agents or the fabrication of metal (Core)---LDH (Shell) nanostructures could have many beneficial effects including multimodality, active targetability, and efficacy. For example, Core---Shell nanostructures may be designed to have a high scattering optical cross-section for imaging, but may also be tailored to strongly absorb near infrared (NIR) light for hyperthermic ablation. The central theme of this thesis was to demonstrate proof-of-concept of spherical silver and gold metal (Core)---LDH (Shell) nanostructures that have uniform size distribution and are agglomeration free. The effects of processing parameters on the characteristics of LDH as well as LDH-coated spherical metal (Ag, Au) nanoparticles have been evaluated using X-ray Diffraction, Dynamic Light Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy, Rutherford Backscattering Spectrometry, and Inductively Coupled Plasma Emission Spectrometry to arrive at appropriate process windows. The core---shell nanostructures were also characterized for their optical properties in the ultra---violet---visible region, and the data were compared with simulated data, computed by using a quasi static model from Mie scattering theory. Moreover, in order to achieve a strong plasmon resonance band in the NIR region, silver nanorods were synthesized to demonstrate the precise control of the plasmon resonance behavior through aspect ratio adjustments. Consequently, it is proposed that LDH-coated metal nanorods must be the primary platform for a potential multimodel nanovector.

Noh, Woo C.

82

The importance of proper crystal-chemical and geometrical reasoning demonstrated using layered single and double hydroxides  

PubMed Central

Atomistic modelling techniques and Rietveld refinement of X-ray powder diffraction data are widely used but often result in crystal structures that are not realistic, presumably because the authors neglect to check the crystal-chemical plausibility of their structure. The purpose of this paper is to reinforce the importance and utility of proper crystal-chemical and geometrical reasoning in structural studies. It is achieved by using such reasoning to generate new yet fundamental information about layered double hydroxides (LDH), a large, much-studied family of compounds. LDH phases are derived from layered single hydroxides by the substitution of a fraction (x) of the divalent cations by trivalent. Equations are derived that enable calculation of x from the a parameter of the unit cell and vice versa, which can be expected to be of widespread utility as a sanity test for extant and future structure determinations and computer simulation studies. The phase at x = 0 is shown to be an ? form of divalent metal hydroxide rather than the ? polymorph. Crystal-chemically sensible model structures are provided for ?-Zn(OH)2 and Ni- and Mg-based carbonate LDH phases that have any trivalent cation and any value of x, including x = 0 [i.e. for ?-M(OH)2·mH2O phases]. PMID:23719702

Richardson, Ian G.

2013-01-01

83

Influences of co-existing species on the sorption of toxic oxyanions from aqueous solution by nanocrystalline Mg/Al layered double hydroxide.  

PubMed

The influences of common oxyanions (i.e. nitrate, silica, sulfate, carbonate, and phosphate) and natural organic matter (NOM) on the sorption of arsenate, chromate, bromate and vanadate (toxic oxyanions) by nanocrystalline Mg/Al layered double hydroxide (LDH) were investigated. Besides the type and concentration of the co-existing species, sorption competition was greatly dependent on the solution pH. In general, based on their sorption competitiveness with the toxic oxyanions, the co-existing common oxyanions were ranked in the order of nitrate < silica < or = sulfate < carbonate < phosphate, while the toxic oxyanions could be ranked in the order of bromate < arsenate approximately chromate < or = vanadate, indicating the oxyanions with lower ionic potentials were less preferably sorbed by the LDH. Based on the comprehensive study on sorption of arsenate by the LDH, the decrease in sorption of toxic oxyanions could be attributed to the competition of common oxyanions for common sorption sites on the LDH which predominantly occurred via ion exchange mechanism. NOM inhibited toxic oxyanion sorption through shielding LDH surface sites, directly competing for sorption sites of LDH, and co-precipitating the LDH. The presence of common oxyanions and NOM generally did not affect the mineral stability of the nanocrystalline LDH. PMID:20452119

Goh, Kok-Hui; Lim, Teik-Thye

2010-08-15

84

In situ synthesis of poly(methyl methacrylate)/MgAl layered double hydroxide nanocomposite with high transparency and enhanced thermal properties  

NASA Astrophysics Data System (ADS)

A novel poly(methyl methacrylate)/MgAl layered double hydroxide (LDH) nanocomposite (PMMA-MgAl NC) with high transparency and enhanced thermal properties was synthesized in situ by adding sodium hydroxide aqueous solution to an emulsion consisting of metal ion aqueous solution, sodium dodecyl sulfate, methyl methacrylate, and benzoyl peroxide, then followed by the thermal initiation polymerization. The basal spacing of PMMA-MgAl NC was 2.72 nm determined by X-ray diffraction measurement. The intercalated MgAl LDH particles of 60-120 nm width and 25-40 nm thickness were well dispersed at molecular level in the PMMA matrix. When the 50% weight loss was selected as a comparison point, the decomposition temperature of PMMA-MgAl NC sample with 30 wt% MgAl LDH (including dodecyl sulfate) was ca. 45 °C higher than that of pure PMMA.

Chen, Wei; Feng, Li; Qu, Baojun

2004-04-01

85

Urea biosensors based on immobilization of urease into two oppositely charged clays (laponite and Zn-Al layered double hydroxides).  

PubMed

Enzyme-based field effect transistors (ENFETs) for urea determination were developed based on the immobilization of urease within two different clay matrixes, one cationic (Laponite) and the other anionic (layered double hydroxide (LDH)), cross-linked with glutaraldehyde. The biosensor based on the enzyme immobilized in Laponite shows a greater sensitivity and smaller dynamic linear range, because the enzymatic reaction is protected from the effect of the buffer capacity of the outer medium. The apparent Michaelis-Menten constant, Km(app), is quite similar for both biosensors. Inhibition of the enzyme by sodium tetraborate was investigated. Tetraborate acts as a competitive inhibitor for urease in the two different types of clay, the inhibitor effect being stronger for the LDH/urease biosensor. In particular, the maximum limit of the dynamic linear range extends from 1.4 mM in the absence of the inhibitor to 12 mM in the presence of 0.5 mM tetraborate. The Km(app) values in the presence of 0.5 mM tetraborate for Laponite and LDH biomembranes were 10 and 62 mM, respectively. Comparison of the inhibition constant values, Ki 0.16 and 0.05 mM for Laponite and LDH biosensors, respectively, clearly indicates a stronger enzyme-inhibitor interaction in the LDH/urease biomembrane. PMID:12199571

de Melo, J V; Cosnier, S; Mousty, C; Martelet, C; Jaffrezic-Renault, N

2002-08-15

86

Characterization and film properties of electrophoretically deposited nanosheets of anionic titanate and cationic MgAl-layered double hydroxide.  

PubMed

Anionic hydrated titanate (H(n)TiO(m): HTO) nanosheets and cationic magnesium-aluminum layered double hydroxide (Mg-Al LDH) nanosheets were electrophoretically deposited on positively and negatively charged indium tin oxide (ITO)-coated glass substrates, respectively. The HTO nanosheets and Mg-Al LDH nanosheets obtained were identified in neutral water as H(2)Ti(4)O(9)·nH(2)O with a ?-potential of -23 mV and Mg(6)Al(2)(OH)(18)·4.5H(2)O with a ?-potential of +41 mV, respectively. Dense and smooth HTO and Mg-Al LDH films with layered structures with thicknesses of about 10-15 ?m were prepared in 300 s at 7.5 V by electrophoretic deposition (EPD) from the nanosheet suspensions. Both EPD HTO and LDH films showed elasticity because of their layered laminate structures. The HTO thick films demonstrated large adsorption properties and high photocatalytic activity, while the Mg-Al LDH thick films showed relatively high ionic conductivity of 10(-5) S cm(-1) at 80 °C and 80% relative humidity. PMID:23205857

Matsuda, Atsunori; Sakamoto, Hisatoshi; Mohd Nor, Mohd Arif Bin; Kawamura, Go; Muto, Hiroyuki

2013-02-14

87

Synthesis and investigation of magnetic nanocomposite of Fe3O4 with cetirizine-intercalated layered double hydroxide  

NASA Astrophysics Data System (ADS)

In this research work the nanocomposite CT-LDH/Fe3O4 was prepared by deposition of cetirizine (CT) intercalated-Mg-Al layered double hydroxide (LDH) on Fe3O4 using a co-precipitation method for sustained drug-targeting delivery. The obtained products were characterized by the variety of methods such as (XRD), (FT-IR), (TG) and the elemental analysis. The size and morphology of nanoparticles were examined by the transmission electron microscopy (TEM). The XRD results, showed the coexistence of the strong diffractions of Fe3O4 and cetirizine intercalated LDH. Also, after intercalation, the basal spacing of LDH increased from 0.88 nm to 2.52 nm, indicating that cetirizine anions were successfully intercalated into the interlayer space of LDH as a monolayer. The thermal gravimetric studies indicate the thermal stability of cetirizine molecule has increased with intercalation. In vitro drug release experiments in phosphate buffer solution (pH = 7.4) have been investigated. Magnetic measurements revealed that the nanocomposite displayed superparamagnetic properties at room temperature.

Nejati, K.; Davaran, S.; Baggalzadeh, R.

2014-11-01

88

Fabrication of a hybrid graphene\\/layered double hydroxide material  

Microsoft Academic Search

A hybrid graphene\\/Ni2+–Fe3+ layered double hydroxide material has been fabricated by the hydrothermal treatment of a mixed suspension of the exfoliated graphite oxide, Ni(NO3)2 6H2O, Fe(NO3)3·9H2O, urea and trisodium citrate. The Ni2+–Fe3+ layered double hydroxide platelets are first homogeneously grown on the surface of GO nanosheets which are then reduced to graphene under a mild hydrothermal treatment. In the hybrid

Hongjuan Li; Gang Zhu; Zong-Huai Liu; Zupei Yang; Zenglin Wang

2010-01-01

89

Polypropylene/layered double hydroxide nanocomposites Qiang Wang,a  

E-print Network

/ Cu­Fe­LDH, and PS/Cu­Cr­LDH,28 ethylene vinyl acetate (EVA)/Mg­Al­LDH, EVA/Zn­Al­LDH,29 polylactic acid (PLA)/Zn­Al­LDH,30 polyamide (PL)/Co­Al­LDH,31,32 Epoxy (EP)/Mg­Al­LDH,33 poly(propylene carbonate

Guo, John Zhanhu

90

Thermal behavior of the hydrotalcite-like layered structure of Mg and Al-layered double hydroxides with interlayer carbonate by means of in situ powder HTXRD and DTA\\/TG  

Microsoft Academic Search

High temperature powder X-ray diffraction (HTXRD) patterns of Mg\\/Al-layered double hydroxides (LDH) with interlayer carbonate (Mg\\/Al\\/CO3-LDH) indicate that a solid phase having a hydrotalcite-like layered structure (Phase I) is not stable when the temperature of solid samples is elevated. Another phase (Phase II) grows eminently and simultaneously with the degradation of Phase I. Phase II has smaller basal spacing than

Eiji Kanezaki

1998-01-01

91

Synthesis of mesoporous silica@Co-Al layered double hydroxide spheres: layer-by-layer method and their effects on the flame retardancy of epoxy resins.  

PubMed

Hierarchical mesoporous silica@Co-Al layered double hydroxide (m-SiO2@Co-Al LDH) spheres were prepared through a layer-by-layer assembly process, in order to integrate their excellent physical and chemical functionalities. TEM results depicted that, due to the electrostatic potential difference between m-SiO2 and Co-Al LDH, the synthetic m-SiO2@Co-Al LDH hybrids exhibited that m-SiO2 spheres were packaged by the Co-Al LDH nanosheets. Subsequently, the m-SiO2@Co-Al LDH spheres were incorporated into epoxy resin (EP) to prepare specimens for investigation of their flame-retardant performance. Cone results indicated that m-SiO2@Co-Al LDH incorporated obviously improved fire retardant of EP. A plausible mechanism of fire retardant was hypothesized based on the analyses of thermal conductivity, char residues, and pyrolysis fragments. Labyrinth effect of m-SiO2 and formation of graphitized carbon char catalyzed by Co-Al LDH play pivotal roles in the flame retardance enhancement. PMID:25062606

Jiang, Shu-Dong; Bai, Zhi-Man; Tang, Gang; Song, Lei; Stec, Anna A; Hull, T Richard; Hu, Yuan; Hu, Wei-Zhao

2014-08-27

92

Carbon quantum dot/NiFe layered double-hydroxide composite as a highly efficient electrocatalyst for water oxidation.  

PubMed

The design of highly efficient, durable, and earth-abundant catalysts for the oxygen evolution reaction is crucial to a variety of important energy conversion and storage processes. Here, we use carbon quantum dots (CQDs, ?5 nm) to form hybrids with the ultrathin nickel-iron layered double-hydroxide (NiFe-LDH) nanoplates. The resulting CQD/NiFe-LDH complex exhibits high electrocatalytic activity (with an overpotential of ?235 mV in 1 M KOH at a current density of 10 mA cm(-2)) and stability for oxygen evolution, which almost exceed the values of all previously reported Ni-Fe compounds and were comparable to those of the most active perovskite-based catalyst. PMID:24735390

Tang, Di; Liu, Juan; Wu, Xuanyu; Liu, Ruihua; Han, Xiao; Han, Yuzhi; Huang, Hui; Liu, Yang; Kang, Zhenhui

2014-05-28

93

A novel and easy chemical-clock synthesis of nanocrystalline iron-cobalt bearing layered double hydroxides.  

PubMed

A novel synthesis of cobalt-iron layered double hydroxide (LDH) with interlayer chlorides was investigated. The method consists in mixing concentrated solutions of hexaamminecobalt(III) trichloride with ferrous chloride at room temperature and in anoxic conditions. Four initial Fe/Co atomic ratios have been tried out (0.12, 0.6, 1.2 and 1.8). Neither heating nor addition of alkali was employed for adjusting the pH and precipitating the metal hydroxides. Still, each mixture led to the spontaneous precipitation of a LDH-rich solid having a crystal-chemistry that depended on the initial solution Fe/Co. These LDHs phases were carefully characterized by mean of X-ray diffraction, (57)Fe Mössbauer spectrometry, transmission electron microscopy and chemical analysis (total dissolution and phenanthroline method). Solution Eh and pH were also monitored during the synthesis. Increasing initial Fe/Co ratio impacted the dynamic of the observed stepwise reaction and the composition of the resulting product. Once the two solutions are mixed, a spontaneous and abrupt color change occurs after an induction time which depends on the starting Fe/Co ratio. This makes the overall process acting as a chemical clock. This spontaneous generation of CoFe-LDH arises from the interplay between redox chemistries of iron and cobalt-ammonium complexes. PMID:25173991

Hadi, Jebril; Grangeon, Sylvain; Warmont, Fabienne; Seron, Alain; Greneche, Jean-Marc

2014-11-15

94

Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O2 reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode

Shou-Nian Ding; Michael Holzinger; Christine Mousty; Serge Cosnier

2010-01-01

95

Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al  

SciTech Connect

The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

Radha, S. [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India); Milius, Wolfgang [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Breu, Josef, E-mail: josef.breu@uni-bayreuth.de [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Kamath, P. Vishnu, E-mail: vishnukamath8@hotmail.com [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India)

2013-08-15

96

Potential for Layered Double Hydroxides-Based, Innovative Drug Delivery Systems  

PubMed Central

Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications. PMID:24786098

Zhang, Kai; Xu, Zhi Ping; Lu, Ji; Tang, Zhi Yong; Zhao, Hui Jun; Good, David A.; Wei, Ming Qian

2014-01-01

97

Synthesis, characterization, and controlled release antibacterial behavior of antibiotic intercalated Mg–Al layered double hydroxides  

SciTech Connect

Graphical abstract: The antibiotic anion released from Mg–Al LDHs provides a controlled release antibacterial activity against the growth of Micrococcus lysodeikticus in 3.5% NaCl solution. Highlights: ? Antibiotic anion intercalated LDHs were synthesized and characterized. ? The ion-exchange one is responsible for the release process. ? The diffusion through particle is the release rate limiting step. ? LDHs loaded with antibiotic anion have high antibacterial capabilities. -- Abstract: Antibiotic–inorganic clay composites including four antibiotic anions, namely, benzoate (BZ), succinate (SU), benzylpenicillin (BP), and ticarcillin (TC) anions, intercalated Mg–Al layered double hydroxides (LDHs) were synthesized via ion-exchange. Powder X-ray diffraction and Fourier transform infrared spectrum analyses showed the successful intercalation of antibiotic anion into the LDH interlayer. BZ and BP anions were accommodated in the interlayer region as a bilayer, whereas SU and TC anions were intercalated in a monolayer arrangement. Kinetic simulation of the release data indicated that ion-exchange was responsible for the release process, and the diffusion through the particles was the rate-limiting step. The antibacterial capabilities of LDHs loaded with antibiotic anion toward Micrococcus lysodeikticus growth were analyzed using a turbidimetric method. Significant high inhibition rate was observed when LDH nanohybrid was introduced in 3.5% NaCl solution. Therefore, this hybrid material may be applied as nanocontainer in active antifouling coating for marine equipment.

Wang, Yi [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)] [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Zhang, Dun, E-mail: zhangdun@qdio.ac.cn [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)] [Shandong Provincial Key Lab of Corrosion Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)

2012-11-15

98

Preparation of polymer/LDH nanocomposite by UV-initiated photopolymerization of acrylate through photoinitiator-modified LDH precursor  

SciTech Connect

Graphical abstract: This is the HR-TEM micrograph of UV cured nanocomposite at 5 wt% LDH-2959 loading for a-5 sample. The dark lines are the intersections of LDH platelets. It can be seen that samples a-5 dispersed in the polymer matrix and lost the ordered stacking-structure and show the completely exfoliation after UV curing. This can be explained by the fact that the sample a-5 only containing LDH-2959 exhibited a relative lower photopolymerization rate, which was propitious to further expand the LDH intergallery to form the exfoliated structure. Research highlights: {yields} The UV cured polymer/LDH nanocomposites were prepared through the photopolymerization initiated by the photoinitiator-modified LDH precursor, LDH-2959. {yields} The exfoliated UV cured nanocomposites were achieved in the presence of LDH-2959 only. However, the UV cured nanocomposites prepared using both LDH-2959 and Irgacure 2959 showed the intercalated structure. {yields} Compared with the pure polymer, the exfoliated polymer/LDH nanocomposite showed remarkable enhanced thermal stability and mechanical properties because of their well dispersion in the polymer matrix. -- Abstract: The exfoliated polymer/layered double hydroxide (LDH) nanocomposite by UV-initiated photopolymerization of acrylate systems through an Irgacure 2959-modified LDH precursor (LDH-2959) as a photoinitiator complex was prepared. The LDH-2959 was obtained by the esterification of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) with thioglycolic acid, following by the addition reaction with 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), finally intercalation into the sodium dodecyl sulfate-modified LDH. For comparison, the intercalated polymer/LDH nanocomposite was obtained with additive Irgacure 2959 addition. From the X-ray diffraction (XRD) measurements and HR-TEM observations, the LDH lost the ordered stacking-structure and well dispersed in the polymer matrix at 5 wt% LDH-2959 loading. The glass transition temperature of UV-cured exfoliated nanocomposites increased to 64 {sup o}C from 55 {sup o}C of pure polymer without LDH addition. The tensile strength was improved from 10.1 MPa to 25.2 MPa, as well the Persoz hardness enhanced greatly, while the elongation at break remained an acceptable level.

Hu, Lihua; Yuan, Yan [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Wenfang, E-mail: wfshi@ustc.edu [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2011-02-15

99

Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols  

NASA Astrophysics Data System (ADS)

M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen. Electronic supplementary information (ESI) available: Details in experimental and further characterization. See DOI: 10.1039/c3nr05604j

Li, Lun; Dou, Liguang; Zhang, Hui

2014-03-01

100

A novel thermotropic elastomer based on highly-filled LDH-SSB composites.  

PubMed

Elastomeric composites are prepared based on solution styrene butadiene elastomer and zinc-aluminium layered double hydroxides (LDH), using a conventional sulphur cure system. Up to 100 parts per hundred rubber of LDH are incorporated into the elastomer matrix. The composites exhibit an interesting phenomenon of thermoreversible transparency, i.e. the transparent sample becomes opaque at warm condition and restores the transparency at room temperature. The transparency is found to be increased as the amount of LDH was increased. The addition of LDH gradually improved the mechanical, dynamic mechanical performance and thermal stability of the base elastomer. These developped elastomers could be utilised as smart materials in different applications. PMID:22271599

Das, Amit; George, Jinu Jacob; Kutlu, Burak; Leuteritz, Andreas; Wang, De-Yi; Rooj, Sandip; Jurk, René; Rajeshbabu, Ramanujam; Stöckelhuber, Klaus Werner; Galiatsatos, Vassilios; Heinrich, Gert

2012-02-27

101

Synthesis of mesoporous Cu/Mg/Fe layered double hydroxide and its adsorption performance for arsenate in aqueous solutions.  

PubMed

The mesoporous Cu/Mg/Fe layered double hydroxide (Cu/Mg/Fe-LDH) with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions. The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry, X-ray diffraction crystallography, scanning electron microscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. Effects of various physico-chemical parameters such as pH, adsorbent dosage, contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated. Results showed that it was efficient for the removal of arsenate, and the removal efficiency of arsenate increased with the increment of the adsorbent dosage, while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11. The adsorption isotherms can be well described by the Langmuir model with R2 > 0.99. Its adsorption kinetics followed the pseudo second-order kinetic model. Coexisting ions such as HPO4(2-), CO3(2-), SO4(2-) and NO3(-) could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH. The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process. It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of < 10 microg/L under the experimental conditions, and makes it a potential material for the decontamination of arsenate polluted water. PMID:24218824

Guo, Yanwei; Zhu, Zhiliang; Qiu, Yanling; Zhao, Jianfu

2013-05-01

102

Evolution of biogenic amine concentrations in foods through their induced chemiluminescence inactivation of layered double hydroxide nanosheet colloids.  

PubMed

Turn-on/off fluorescence and visual sensors through hydrogen bonding recognition have been clearly established in the literature. There is apparently no good reason to disregard hydrogen bonding-induced inactivation of chemiluminescence (CL). In this work, serving as novel CL catalyst and CL resonance energy transfer acceptor (CRET), layered double hydroxide (LDH) nanosheet colloids can induce a significant increase in the CL intensity of bis(2,4,6-trichlorophenyl) oxalate (TCPO)-H2O2 system. On the other hand, biogenic amines can selectively inhibit the CL intensity of the LDH nanosheet-TCPO-H2O2 system as a result of inactivation of photoluminescence LDH nanosheets through the displacement of O-H ? O bonding by O-H ? N bonding. In addition, histamine is used as a common indicator of food spoilage, and it is found that the CL intensity is linear with histamine concentration in the range of 0.1-100 µM, and the detection limit for histamine (S/N=3) is 3.2 nM. The proposed method has been successfully applied to trace histamine evolution of spoiled fish and pork meat samples, displaying a time-dependent increase in the biogenic amines levels in such samples. PMID:24813913

Wang, Zhihua; Liu, Fang; Lu, Chao

2014-10-15

103

Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment  

SciTech Connect

Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), {sup 27}Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al{sup 3+} and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M{sup 2+}/M{sup 3+} ratio and consequent modification of the cell parameters. - Graphical Abstract: The influence of the nature of the interlayer anion during the ageing process of carboxylate-intercalated (TA and ox) hydrotalcite-like compounds (HTlcs) is studied. Well crystallized for TA-containing compounds were obtained. However, the non-desired side-reaction of ox with the aluminum of the layers is enhanced by the microwaves and a partial destruction of the structure takes place.

Benito, P.; Labajos, F.M. [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, Salamanca 37008 (Spain); Mafra, L.; Rocha, J. [Departamento de Quimica, Universidade de Aveiro, Aveiro, CICECO (Portugal); Rives, V. [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, Salamanca 37008 (Spain)], E-mail: vrives@usal.es

2009-01-15

104

Biodiesel synthesis using calcined layered double hydroxide catalysts  

SciTech Connect

The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

Schumaker, J. Link [University of Kentucky; Crofcheck, Czarena [University of Kentucky; TAckett, S. Adam [University of Kentucky; Santillan-Jimenez, Eduardo [University of Kentucky; Morgan, Tonya [University of Kentucky; Ji, Yaying [University of Kentucky; Crocker, Mark [University of Kentucky; Toops, Todd J [ORNL

2008-01-01

105

Magnetic-field-assisted assembly of layered double hydroxide/metal porphyrin ultrathin films and their application for glucose sensors.  

PubMed

The ordered ultrathin films (UTFs) based on CoFe-LDH (layered double hydroxide) nanoplatelets and manganese porphyrin (Mn-TPPS) have been fabricated on ITO substrates via a magnetic-field-assisted (MFA) layer-by-layer (LBL) method and were demonstrated as an electrochemical sensor for glucose. The XRD pattern for the film indicates a long-range stacking order in the normal direction of the substrate. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the MFA LDH/Mn-TPPS UTFs reveal a continuous and uniform surface morphology. Cyclic voltammetry, impedance spectroscopy, and chronoamperometry were used to evaluate the electrochemical performance of the film, and the results show that the MFA-0.5 (0.5 T magnetic field) CoFe-LDH/Mn-TPPS-modified electrode displays the strongest redox current peaks and fastest electron transfer process compared with those of MFA-0 (without magnetic-field) and MFA-0.15 (0.15 T magnetic field). Furthermore, the MFA-0.5 CoFe-LDH/Mn-TPPS exhibits remarkable electrocatalytic activity toward the oxidation of glucose with a linear response range (0.1-15 mM; R(2) = 0.999), low detection limit (0.79 ?M) and high sensitivity (66.3 ?A mM(-1) cm(-2)). In addition, the glucose sensor prepared by the MFA LBL method also shows good selectivity and reproducibility as well as resistance to poisoning in a chloride ion solution. Therefore, the novel strategy in this work creates new opportunities for the fabrication of nonenzyme sensors with prospective applications in practical detection. PMID:21650214

Shao, Mingfei; Xu, Xiangyu; Han, Jingbin; Zhao, Jingwen; Shi, Wenying; Kong, Xianggui; Wei, Min; Evans, David G; Duan, Xue

2011-07-01

106

Three dimensionally honeycomb layered double hydroxides framework as a novel fiber coating for headspace solid-phase microextraction of phenolic compounds.  

PubMed

A new solid phase microextraction (SPME) fiber based on high-temperature three dimensionally honeycomb layered double hydroxide (TDH-LDH) material is presented. The fiber coating can be prepared easily, it is mechanically stable and exhibits relatively high thermal stability. This study shows that three dimensionally honeycomb layered double hydroxide generated porous morphology. The TDH-LDH material was tested for the extraction of some phenolic and polycyclic aromatic hydrocarbon compounds from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). The TDH-LDH fiber contains polar groups and its efficiency for non-polar polycyclic aromatic hydrocarbon compounds was lower than phenolic compounds. On the other hand, a high tendency towards the adsorption of polar phenolic compounds was observed for the proposed fiber. The effects of the extraction and desorption parameters including extraction temperature, extraction time, ionic strength, stirring rate, pH and desorption temperature and time have been studied. In optimum conditions, the repeatability for one fiber (n=5), expressed as relative standard deviation (R.S.D. %), was between 2.8% and 7.1% for the phenolic compounds. The detection limits for the studied phenolic compounds were between 0.02 and 5.8 ng mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis. PMID:24780259

Abolghasemi, Mir Mahdi; Yousefi, Vahid

2014-06-01

107

Aluminium substitution in iron(II-III)-layered double hydroxides: Formation and cationic order  

SciTech Connect

The formation and the modifications of the structural properties of an aluminium-substituted iron(II-III)-layered double hydroxide (LDH) of formula Fe{sub 4}{sup II}Fe{sub (2-6y)}{sup III}Al{sub 6y}{sup III} (OH){sub 12} SO{sub 4}, 8H{sub 2}O are followed by pH titration curves, Moessbauer spectroscopy and high-resolution X-ray powder diffraction using synchrotron radiation. Rietveld refinements allow to build a structural model for hydroxysulphate green rust, GR(SO{sub 4}{sup 2-}), i.e. y=0, in which a bilayer of sulphate anions points to the Fe{sup 3+} species. A cationic order is proposed to occur in both GR(SO{sub 4}{sup 2-}) and aluminium-substituted hydroxysulphate green rust when y<0.08. Variation of the cell parameters and a sharp decrease in average crystal size and anisotropy are detected for an aluminium content as low as y=0.01. The formation of Al-GR(SO{sub 4}{sup 2-}) is preceded by the successive precipitation of Fe{sup III} and Al{sup III} (oxy)hydroxides. Adsorption of more soluble Al{sup III} species onto the initially formed ferric oxyhydroxide may be responsible for this slowdown of crystal growth. Therefore, the insertion of low aluminium amount (y{approx}0.01) could be an interesting way for increasing the surface reactivity of iron(II-III) LDH that maintains constant the quantity of the reactive Fe{sup II} species of the material. - Graphical abstract: (a) Crystallographical structure of sulphated green rust: SO{sub 4}{sup 2-} point to the Fe{sup 3+} cations (red) that form an ordered array with the Fe{sup 2+} cations (green). (b) Width and asymmetry of the synchrotron XRD peaks increase rapidly when some Al{sup 3+} species substitute the Fe{sup 3+} cations; z is molar ratio Al{sup 3+}/Fe{sup 3+}.

Ruby, Christian [Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME UMR7564 CNRS-Nancy Universite, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France)], E-mail: Christian.ruby@lcpme.cnrs-nancy.fr; Abdelmoula, Mustapha; Aissa, Rabha [Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME UMR7564 CNRS-Nancy Universite, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); Medjahdi, Ghouti [Laboratoire de Chimie du Solide Mineral, LCSM UMR 7555 CNRS-Nancy Universite, Faculte des Sciences, BP239, 54506 Vandoeuvre-les-Nancy (France); Brunelli, Michela [European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex (France); Francois, Michel [Laboratoire de Chimie du Solide Mineral, LCSM UMR 7555 CNRS-Nancy Universite, Faculte des Sciences, BP239, 54506 Vandoeuvre-les-Nancy (France)

2008-09-15

108

The double hydroxide of Al with Li: mechanism of formation and reversible thermal behavior  

Microsoft Academic Search

All the polymorphic modifications of Al(OH)3 and the oxide–hydroxide of Al, boehmite, on hydrothermal treatment in Li+ containing solutions transform into the layered double hydroxide of Al with Li having the nominal composition [LiAl2(OH)6](CO3)1\\/2·1.5H2O, suggesting that these compounds form via a dissolution–reprecipitation mechanism. The oxide residue obtained by the thermal decomposition of this layered double hydroxide also partially reconstructs the

Grace S. Thomas; P. Vishnu Kamath

2002-01-01

109

ISOLATION OF CAFFEIC ACID FROM EUPATORIUM ADENOPHORUM SPRENG BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY AND SYNTHESIS OF CAFFEIC ACID-INTERCALATED LAYERED DOUBLE HYDROXIDE  

PubMed Central

Preparative high-speed countercurrent chromatography (HSCCC) was successfully used for isolation and purification of caffeic acid from Eupatorium adenophorum Spreng with a solvent system composed of ethyl acetate-methanol-water at a volume ratio of 10:1:10, v/v. Using a preparative unit of the HSCCC centrifuge, about a 938 mg amount of the crude extract was separated, yielding 63.2 mg of caffeic acid at purity of 96.0%. Then, the anti-microbial and anti-virus drug caffeic acid (C9H8O4) was intercalated into layered double hydroxides for the first time by anion exchange under a nitrogen atmosphere. The product caffeic acid–LDH has been characterized by powder X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), Scanning electron micrographs (SEM), indicating that the drug has been successfully intercalated into LDH. PMID:20454592

Wei, Yun; Gao, Yali; Zhang, Kai; Ito, Yoichiro

2010-01-01

110

Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Ordering of gallium(III) in a series of magnesium gallium (MgGa) layered double hydroxides (LDHs), [Mg1-xGax(OH)2(NO3)x·yH2O] was investigated using solid-state 1H and 71Ga NMR spectroscopy as well as powder X-ray diffraction. Three different proton environments from Mg3sbnd OH, Mg2Gasbnd OH and intergallery water molecules were assigned and quantified using {1H,71Ga} HETCOR and 1H MAS NMR. A single 71Ga site originating from the unique Ga site in the MgGa LDH's was observed in 71Ga MAS and 3QMAS NMR spectra. Both 1H MAS NMR spectra recorded at 21.1 T (900 MHz) and elemental analysis show that the synthesized MgGa LDH's had a lower Mg:Ga ratio than that of the starting reactant solution. The origin of this is the formation of soluble [Ga(OH)4]- complexes formed during synthesis, and not due to formation of insoluble gallium (oxy)hydroxides. No sign of Gasbnd Osbnd Ga connectivities or defects were detected for the MgGa LDH's.

Petersen, Line Boisen; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

2014-11-01

111

Synthesis of highly efficient flame retardant high-density polyethylene nanocomposites with inorgano-layered double hydroxides as nanofiller using solvent mixing method.  

PubMed

High-density polyethylene (HDPE) polymer nanocomposites containing Zn2Al-X (X= CO3(2-), NO3(-), Cl(-), SO4(2-)) layered double hydroxide (LDH) nanoparticles with different loadings from 10 to 40 wt % were synthesized using a modified solvent mixing method. Synthesized LDH nanofillers and the corresponding nanocomposites were carefully characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, etc. The thermal stability and flame retardancy behavior were investigated using a thermo gravimetric analyzer and microscale combustion calorimeter. Comparing to neat HDPE, the thermal stability of nanocomposites was significantly enhanced. With the addition of 15 wt % Zn2Al-Cl LDH, the 50% weight loss temperature was increased by 67 °C. After adding LDHs, the flame retardant performance was significantly improved as well. With 40 wt % of LDH loading, the peak heat release rate was reduced by 24%, 41%, 48%, and 54% for HDPE/Zn2Al-Cl, HDPE/Zn2Al-CO3, HDPE/Zn2Al-NO3, and HDPE/Zn2Al-SO4, respectively. We also noticed that different interlayer anions could result in different rheological properties and the influence on storage and loss moduli follows the order of SO4(2-) > NO3(-) > CO3(2-) > Cl(-). Another important finding of this work is that the influence of anions on flame retardancy follows the exact same order on rheological properties. PMID:24597470

Gao, Yanshan; Wang, Qiang; Wang, Junya; Huang, Liang; Yan, Xingru; Zhang, Xi; He, Qingliang; Xing, Zipeng; Guo, Zhanhu

2014-04-01

112

Coexistence of adsorption and coagulation processes of both arsenate and NOM from contaminated groundwater by nanocrystallined Mg/Al layered double hydroxides.  

PubMed

In this study, nanocrystallined Mg/Al layered double hydroxides (LDH-CO3) and chloridion intercalated nanocrystallined Mg/Al LDHs (LDH-Cl) were synthesized and used for simultaneous removal of arsenic and natural organic matter (NOM) from contaminated groundwater. Humic acid (HA) was selected as a model compound of NOM. The maximum adsorption capacities of arsenate (As(V)) on LDH-CO3 and LDH-Cl are 44.66 and 88.30 mg/g, respectively, and those of HA on LDH-CO3 and LDH-Cl are 53.16 and 269.24 mg/g, respectively. It was found that more than 98% of arsenic and 94% of NOM were eliminated by LDH-Cl from both arsenic and NOM-rich groundwater, which is used as drinking water in Togtoh County, Inner Mongolia, China. The arsenic concentration declined from 231 to 4 ?g/L, which meets the drinking water standard. The adsorption mechanisms were determined by using X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and extended X-ray absorption fine structure spectroscopy techniques (EXAFS). The results showed that the removal of HA was mainly via surface complexation as well as coagulation at the surface of LDHs, while the adsorption of As(V) was mainly via ion-exchange process. The presence of HA exhibited little inhibiting effect on As(V) adsorption by occupying partial binding sites on LDH surfaces. Nevertheless, it could not affect the ion-exchange process of As(V) with the interlayer anions of LDHs. The removal of As(V) and HA can be carried out independently due to the different adsorption mechanisms. By integrating the experimental results, it is clear that LDH-Cl can be potentially used as a cost-effective material for the purification of both arsenic and NOM contaminated groundwater. PMID:23582669

Wu, Xilin; Tan, Xiaoli; Yang, Shitong; Wen, Tao; Guo, Hongli; Wang, Xiangke; Xu, Anwu

2013-08-01

113

A Ni-Fe Layered Double Hydroxide-Carbon Nanotube Complex for Water Oxidation  

E-print Network

Highly active, durable and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions including water splitting and rechargeable metal-air batteries. Here, we report the synthesis of ultrathin nickel iron layered double hydroxide nanoplates on mildly oxidized multi-walled carbon nanotubes. Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-layered double hydroxide. The nanoplates were covalently attached to a network of nanotubes, affording excellent electrical wiring to the nanoplates. The ultra-thin Ni-Fe layered double hydroxide nanoplates/carbon nanotube complex was found to exhibit unusually high electro-catalytic activity and stability for oxygen evolution and outperformed commercial precious metal Ir catalysts.

Gong, Ming; Wang, Hailiang; Liang, Yongye; Wu, Justin Zachary; Zhou, Jigang; Wang, Jian; Regier, Tom; Wei, Fei; Dai, Hongjie

2013-01-01

114

Layered double hydroxide formation in Bayer liquor and its promotional effect on oxalate precipitation  

SciTech Connect

Enhancing the precipitation of sodium oxalate from Bayer process liquor to improve the quality of alumina product remains an important objective for Bayer refining. The formation of layered double hydroxides by the reaction of alkaline earth oxides, such as lime and magnesia, with Bayer liquor gives a crystal structure which is capable of intercalating anions, both inorganic and organic, within its structure. Both lime and magnesia, with long contact times in Bayer liquor, show layered double hydroxide formation. This layered double hydroxide formation is accompanied with a decrease in the sodium oxalate content in the liquor from about 3 g/L to below 1 g/L. Short contact times lead to a destabilization of the liquor which facilitates sodium oxalate precipitation. Additional work on magnesium hydroxide shows, in comparison to lime and magnesia, much less layered double hydroxide formation with equivalent residence time in the liquor. Destabilization of the liquor also occurs, giving enhanced oxalate precipitation with less alumina being consumed in agreement with lower layered double hydroxide formation. Thermal regeneration of these structures, followed by in-situ recrystallization in Bayer liquor, also gives enhanced oxalate precipitation, suggesting that there is an opportunity for a regenerable oxalate reduction system. The implementation of these experiments and other related technology into the plant has resulted in the Purox Process for enhancing the precipitation of sodium oxalate from Bayer liquor.

Perrotta, A.J. [Alcoa Technical Center, Alcoa Center, PA (United States); Williams, F. [Alcoa Operations, Pt. Comfort, TX (United States)

1996-10-01

115

Reversible hydration and aqueous exfoliation of the acetate-intercalated layered double hydroxide of Ni and Al: Observation of an ordered interstratified phase  

SciTech Connect

Acetate-intercalated layered double hydroxides (LDHs) of Ni and Al undergo reversible hydration in the solid state in response to the ambient humidity. The LDH with a high layer charge (0.33/formula unit) undergoes facile hydration in a single step, whereas the LDH with a lower layer charge (0.24/formula unit) exhibits an ordered interstratified intermediate, comprising the hydrated and dehydrated layers stacked alternatively. This phase, also known as the staged S-2 phase, coexists with the end members suggesting the existence of a solution-type equilibrium between the S-2 phase and the end members of the hydration cycle. These LDHs also undergo facile aqueous exfoliation into 2-5 nm-thick tactoids with a radial dimension of 0.2-0.5 {mu}m. - Graphical abstract: Schematic of the hydrated, dehydrated and interstratified phases observed during the hydration-dehydration of Ni/Al-CH{sub 3}COO LDH. Highlights: Black-Right-Pointing-Pointer Ni/Al-acetate LDHs were synthesized by HPFS method by hydrolysis of acetamide. Black-Right-Pointing-Pointer Intercalated acetate ion shows reversible hydration with variation in humidity. Black-Right-Pointing-Pointer An ordered interstratified phase was observed during hydration/dehydration cycle. Black-Right-Pointing-Pointer A solution type equilibrium is observed between hydration-dehydration phases. Black-Right-Pointing-Pointer These LDHs undergo facile aqueous exfoliation.

Manohara, G.V. [Department of Chemistry, The Central College Campus, Bangalore University, Bangalore 560 001 (India)] [Department of Chemistry, The Central College Campus, Bangalore University, Bangalore 560 001 (India); Vishnu Kamath, P., E-mail: vishnukamath8@hotmail.com [Department of Chemistry, The Central College Campus, Bangalore University, Bangalore 560 001 (India); Milius, Wolfgang [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth D-95440 (Germany)] [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth D-95440 (Germany)

2012-12-15

116

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition  

PubMed Central

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids. PMID:25080007

Nakayama, Hirokazu; Hayashi, Aki

2014-01-01

117

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition.  

PubMed

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids. PMID:25080007

Nakayama, Hirokazu; Hayashi, Aki

2014-01-01

118

Thermal evolution of the Cl(-)-LiAl(2) layered double hydroxide: a multinuclear MAS NMR and XRD perspective.  

PubMed

Layered double hydroxides (LDHs) with a cation composition of LiAl(2) have a wide range of potential applications as catalysts, catalyst supports, and precursors for refractory oxide materials, including several industrially important lithium aluminate phases. The understanding of the calcination behavior of this group of LDH phases is essential to advancing these applications, and the research described here focuses on the thermal decomposition and structural evolution of LiAl(2)(OH)(6)Cl.nH(2)O in the temperature range of 20-1100 degrees C. (27)Al, (35)Cl, and (6,7)Li magic angle spinning nuclear magnetic resonance spectroscopy, powder X-ray diffraction, thermal analysis (including thermogravimetric and differential scanning calorimetry), and compositional analysis provide a highly consistent picture of the thermally induced phase formation and transformations of this LDH. The loss of the surface and interlayer water can begin as low as room temperature, depending on the relative humidity. Beginning at about 300 degrees C, the simultaneous volatilization of H(2)O and HCl and the exsolution of crystalline LiCl result in the formation of amorphous Li-Al-O-OH. By at least 500 degrees C, volumes with the structures of alpha-LiAlO(2) and LiAl(5)O(8) appear, and these phases become progressively more ordered with increasing temperature. LiCl begins to volatilize by 850 degrees C and is present only in trace amounts above ca. 1000 degrees C. alpha-LiAlO(2) converts to gamma-LiAlO(2) between 970 and 1100 degrees C. Because of the delithiation due to LiCl volatilization, the final products are dominated by LiAl(5)O(8), in contrast to the calcination products of previously studied LiAl(2) LDHs which are dominated by LiAlO(2). PMID:11720493

Hou, X; Kirkpatrick, R J

2001-12-01

119

Effect of hydrothermal treatment on properties of Ni-Al layered double hydroxides and related mixed oxides  

NASA Astrophysics Data System (ADS)

The Ni-Al layered double hydroxides (LDHs) with Ni/Al molar ratio of 2, 3, and 4 were prepared by coprecipitation and treated under hydrothermal conditions at 180 °C for times up to 20 h. Thermal decomposition of the prepared samples was studied using thermal analysis and high-temperature X-ray diffraction. Hydrothermal treatment increased significantly the crystallite size of coprecipitated samples. The characteristic LDH diffraction lines disappeared completely at ca. 350 °C and a gradual crystallization of NiO-like mixed oxide was observed at higher temperatures. Hydrothermal treatment improved thermal stability of the Ni2Al and Ni3Al LDHs but only a slight effect of hydrothermal treatment was observed with the Ni4Al sample. The Rietveld refinement of powder XRD patterns of calcination products obtained at 450 °C showed a formation of Al-containing NiO-like oxide and a presence of a considerable amount of Al-rich amorphous component. Hydrothermal aging of the LDHs resulted in decreasing content of the amorphous component and enhanced substitution of Al cations into NiO-like structure. The hydrothermally treated samples also exhibited a worse reducibility of Ni 2+ components. The NiAl 2O 4 spinel and NiO still containing a marked part of Al in the cationic sublattice were detected in the samples calcined at 900 °C. The Ni2Al LDHs hydrothermally treated for various times and related mixed oxides obtained at 450 °C showed an increase in pore size with increasing time of hydrothermal aging. The hydrothermal treatment of LDH precursor considerably improved the catalytic activity of Ni2Al mixed oxides in N 2O decomposition, which can be explained by suppressing internal diffusion effect in catalysts grains.

Kovanda, František; Rojka, Tomáš; Bezdi?ka, Petr; Jirátová, Kv?ta; Obalová, Lucie; Pacultová, Kate?ina; Bastl, Zden?k; Grygar, Tomáš

2009-01-01

120

Intercalation of a molybdenum ?3-allyl dicarbonyl complex in a layered double hydroxide and catalytic performance in olefin epoxidation.  

PubMed

A Zn-Al layered double hydroxide (LDH) intercalated by [Mo(?(3)-C3H5)Cl(CO)2(bpdc)](2-) anions (bpdc = 2,2'-bipyridine-5,5'-dicarboxylate) has been prepared by coprecipitation from aqueous solution and characterised by various techniques. The one-pot method gives rise to a highly organised intercalate with an interlayer spacing of 18.3 Å and up to six (00l) basal reflections in the powder X-ray diffraction pattern. Spectroscopic studies (FT-IR, FT-Raman, (13)C CP MAS NMR and UV-Vis) confirm the presence of structurally intact [Mo(?(3)-C3H5)Cl(CO)2(bpdc)](2-) anions. The interlayer spacing of 18.3 Å indicates that the material contains a monolayer of guest anions positioned in such a way that the bpdc ligands are arranged with their longest dimension roughly perpendicular to the hydroxide layers of the host. Thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. The intracrystalline reactivity of intercalated dicarbonyl complexes was probed by using the hybrid nanocomposite as a precatalyst in the liquid phase epoxidation of cis-cyclooctene with tert-butylhydroperoxide as oxidant. Under the reaction conditions used, oxidative decarbonylation of the guest molecules takes place (with release of CO and CO2 as confirmed by on-line gas chromatography experiments) to give intercalated molybdenum oxide/bipyridine species that selectively catalyse the epoxidation reaction. The intracrystalline oxidative decarbonylation reaction is topotactic in nature. PMID:23588706

Gomes, Ana C; Bruno, Sofia M; Gamelas, Carla A; Valente, Anabela A; Abrantes, Marta; Gonçalves, Isabel S; Romão, Carlos C; Pillinger, Martyn

2013-06-21

121

Polytypism, disorder, and anion exchange properties of divalent ion (Zn, Co) containing bayerite-derived layered double hydroxides.  

PubMed

Incorporation of Zn(2+) into bayerite results in the formation of a cation-ordered layered double hydroxide (LDH) of monoclinic symmetry in which about half the vacancies of Al(OH)(3) are occupied by Zn(2+) giving rise to positively charged layers. Charge compensation takes place by the incorporation of sulfate ions in the interlayer region. Structure refinement reveals that the adjacent layers in the crystal are related by a 2(1) axis (we call it 2M(1) polytype) with sulfate coordinating in the D(2d) symmetry in the interlayer region. Another polytype in which adjacent layers are related by a 2-fold axis (2M(2) polytype) can also be envisaged. Faulted crystals arising from intergrowths of the 2M(2) polytype within the 2M(1) structure were also obtained. These bayerite-based LDHs have a distinctly different interlayer chemistry when compared to the better known brucite-based LDHs, in that they have a strong affinity for tetrahedral ions such as SO(4)(2-), CrO(4)(2-), and MoO(4)(2-) and a poor affinity for CO(3)(2-) ions. These observations have implications for the use of LDHs in applications related to chromate sorption. PMID:21077586

Britto, Sylvia; Kamath, P Vishnu

2010-12-20

122

Interstratified nanohybrid assembled by alternating cationic layered double hydroxide nanosheets and anionic layered titanate nanosheets with superior photocatalytic activity.  

PubMed

Oppositely charged 2D inorganic nanosheets of ZnAl-layered double hydroxide and layered titanate were successfully assembled into an interstratified nanohybrid through simply mixing the corresponding nanosheet suspensions. Powder X-ray diffraction and high-resolution transmission electron microscope clearly revealed that the component nanosheets in the as-obtained nanohybrid ZnAl-Ti3O7 retain the 2D sheet skeletons of the pristine materials and that the two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion with a basal spacing of about 1.3nm, coincident with the thickness summation of the two component nanosheets. The effective interfacial heterojunction between them and the high specific surface area resulted in that the nanohybrid exhibits a superior photocatalytic activity in the degradation of methylene blue with a reaction constant k of 2.81×10(-2)min(-1), which is about 9 and 4 times higher than its precursors H2Ti3O7 and ZnAl-LDH, respectively. Based on UV-vis, XPS and photoelectrochemical measurements, a proposed photoexcitation model was provided to understand its photocatalytic behavior. PMID:25151238

Lin, Bizhou; Sun, Ping; Zhou, Yi; Jiang, Shaofeng; Gao, Bifen; Chen, Yilin

2014-09-15

123

Synthesis of Mg-Al-Fe-NO3 layered double hydroxides via a mechano-hydrothermal route  

NASA Astrophysics Data System (ADS)

Mg-Al-Fe-NO3 layered double hydroxides (LDHs) with a constant Mg2+/(Al3+ + Fe3+) molar ratio but varying Al3+/Fe3+ molar ratios were successfully synthesized by a mechano-hydrothermal (MHT) method from Mg(OH)2, Al(OH)3 and Fe(NO3)3·9H2O or Mg(NO3)2·6H2O as starting materials. The resulting LDHs (MHT-LDHs) were characterized by XRD, TEM, SEM, FT-IR, and zeta potential, size distribution and specific surface area analyses. It was found that pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The MHT route is advantageous in terms of low reaction temperature compared with the conventional hydrothermal method, and the target products are of high crystallinity and good dispersion compared with the conventional mechanochemical (MC) method. The MHT-LDHs had higher specific surface area and zeta potential, and lower hydrodynamic diameter than LDHs obtained by MC method (MC-LDHs). Furthermore, the removal of Cr(VI) from aqueous solutions using the LDHs was examined, showing that the MHT-LDHs are of higher removal efficiency than MC-LDHs for the heavy metal pollutant.

Zhang, Fengrong; Du, Na; Li, Haiping; Liu, Jianqiang; Hou, Wanguo

2014-06-01

124

A facile synthesis of strong near infrared fluorescent layered double hydroxide nanovehicles with an anticancer drug for tumor optical imaging and therapy  

NASA Astrophysics Data System (ADS)

In this work, a new multifunctional nanovehicle for tumor optical imaging and therapy was developed using Y2O3:Er3+,Yb3+ nanoparticles as near infrared fluorescent nanophosphors, and MgAl-layered double hydroxide (LDH) nanosheets as anticancer drug nanovehicles. Monodispersed Y2O3:Er3+,Yb3+ nanophosphors were readily synthesized by the urea assisted homogenous precipitation method. Hierarchically structured LDH nanosheets intercalated with an anticancer drug, fluorouracil (5FU), were deposited on the surface of Y2O3:Er3+,Yb3+@SiO2 by a simple precipitation method followed by hydrothermal treatment. The resultant Y2O3:Er3+,Yb3+@SiO2@LDH-5FU nanovehicles exhibit strong red upconversion fluorescence under the excitation of a 980 nm laser, which allows tracking of the nanovehicles after localization in cancer cells. A better anticancer efficiency was obtained over the nanovehicles than the free drug which can be attributed to their positively charged surfaces for favorable interaction with the negatively charged cell membranes. The multifunctional nanovehicles designed in this work are expected to be promising material candidates for simultaneous tumor optical imaging and therapy.In this work, a new multifunctional nanovehicle for tumor optical imaging and therapy was developed using Y2O3:Er3+,Yb3+ nanoparticles as near infrared fluorescent nanophosphors, and MgAl-layered double hydroxide (LDH) nanosheets as anticancer drug nanovehicles. Monodispersed Y2O3:Er3+,Yb3+ nanophosphors were readily synthesized by the urea assisted homogenous precipitation method. Hierarchically structured LDH nanosheets intercalated with an anticancer drug, fluorouracil (5FU), were deposited on the surface of Y2O3:Er3+,Yb3+@SiO2 by a simple precipitation method followed by hydrothermal treatment. The resultant Y2O3:Er3+,Yb3+@SiO2@LDH-5FU nanovehicles exhibit strong red upconversion fluorescence under the excitation of a 980 nm laser, which allows tracking of the nanovehicles after localization in cancer cells. A better anticancer efficiency was obtained over the nanovehicles than the free drug which can be attributed to their positively charged surfaces for favorable interaction with the negatively charged cell membranes. The multifunctional nanovehicles designed in this work are expected to be promising material candidates for simultaneous tumor optical imaging and therapy. Electronic supplementary information (ESI) available: TEM images of Y2O3:Er3+,Yb3+@SiO2 synthesized by using different amounts of TEOS, and confocal scanning laser microscopy images (Z stack) of MCF-7 cells incubated with Y2O3:Er3+,Yb3+@SiO2@LDH-5FU for 30 min and 24 h. See DOI: 10.1039/c3nr00781b

Chen, Chunping; Yee, Lee Kim; Gong, Hua; Zhang, Yong; Xu, Rong

2013-05-01

125

Structural characterization and thermal properties of polyamide 6.6/Mg, Al/adipate-LDH nanocomposites obtained by solid state polymerization  

SciTech Connect

A new nanocomposite was obtained by dispersing an adipate-modified layered double hydroxide (Ad-LDH) with adipic acid and hexamethylene diamine. These samples were polymerized in the solid phase under a nitrogen flow for 200 min at 190 {sup o}C. The structural and compositional details of the nanocomposite were determined by powder X-ray diffraction (PXRD), fourier transform infrared (FTIR) spectroscopy, focused ion beam (FIB), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The PXRD patterns and FIB images show a partially intercalated and partially exfoliated dispersion of layered crystalline materials in the polyamide 6.6 matrix. The best dispersion level is achieved in polyamide 6.6/LDH nanocomposites with low LDH loading. Some residual tactoids and particle agglomerates are also evident at high concentration. The best thermal stability of the nanocomposites is shown by the sample with 0.1% LDH content, for which it is higher than that of pure polyamide. - Graphical abstract: A new nanocomposite was obtained by compounding an adipate-modified layered double hydroxides (LDH) with adipic acid and hexamethylene diamine. These samples were polymerized in the solid phase under a nitrogen flow for 200 min at 190 {sup o}C. The nanodispersion of LDH in polyamide 6.6 may be qualitatively estimated from the analysis and PXRD patterns and FIB images. The decomposition temperature in the nanocomposite with 0.1 % LDH increases significantly compared to that for pristine PA6.6. .

Herrero, M.; Benito, P.; Labajos, F.M. [GIR-QUESCAT-Departamento de Quimica Inorganica, Universidad de Salamanca, 37008 Salamanca (Spain); Rives, V., E-mail: vrives@usal.e [GIR-QUESCAT-Departamento de Quimica Inorganica, Universidad de Salamanca, 37008 Salamanca (Spain); Zhu, Y.D.; Allen, G.C. [Interface Analysis Centre, University of Bristol, Bristol BS2 8BS (United Kingdom); Adams, J.M. [School of Engineering and Computer Science, University of Exeter, Exeter EX4 4QF (United Kingdom)

2010-07-15

126

Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions.  

PubMed

A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions. PMID:18255088

Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; Wypych, Fernando

2008-04-01

127

Preparation of melt-spun antimicrobially modified LDH/polyolefin nanocomposite fibers.  

PubMed

Layered double hydroxide (LDH) was synthesized and organically modified with camphorsulfonic acid (CSA) and ciprofloxacin. The thermal stability of CSA was improved remarkably under LDH shielding. A minimal inhibitory concentration of free CSA against tested bacteria was determined in order to define the essential quantity in LDH modification. The modified LDHs were melt-compounded with high density polyethylene and the prepared nanocomposites were further melt-spun using a piston-type spinning device. The melt-spun fibers were tested for their antimicrobial activity against Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. CSA integrated fibers show susceptibility against Gram-positive bacteria and ciprofloxacin integrated fibers showed activity against both Gram-positive and Gram-negative bacteria. PMID:24907731

Kutlu, Burak; Schröttner, Percy; Leuteritz, Andreas; Boldt, Regine; Jacobs, Enno; Heinrich, Gert

2014-08-01

128

Bifunctional sensor of pentachlorophenol and copper ions based on nanostructured hybrid films of humic acid and exfoliated layered double hydroxide via a facile layer-by-layer assembly.  

PubMed

A new, highly sensitive bifunctional electrochemical sensor for the simultaneous determination of pentachlorophenol (PCP) and copper ions (Cu(2+)) has been developed, where organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of humic acid (HA) and exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets onto ITO substrates via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of UV-vis spectrometry, scanning electron microscopy (SEM), and atomic force microscope (AFM). These films were found to have a relatively smooth surface with almost equal amounts of HA incorporated in each cycle. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/HA)n multilayer films, combining the individual properties of HA (dual recognition ability for organic herbicides and metal ions) together with LDH nanosheets (a rigid inorganic matrix), can be applied to the simultaneous analysis of PCP and Cu(II) without interference from each other. The LBL assembled nanoarchitectures were further investigated by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR), which provides insight for bifunctional sensing behavior. Under the optimized conditions, the detection limit was found to be as low as 0.4 nM PCP, well below the guideline value of PCP in drinking water (3.7 nM) set by the United States Environmental Protection Agency (U.S. EPA), and 2.0 nM Cu(2+), much below the guideline value (2.0 mg L(-1), ~31.2 nM) from the World Health Organization (WHO), respectively. Toward the goal for practical applications, this simple and cost-effective probe was further evaluated by monitoring PCP and Cu(II) in water samples. PMID:23764441

Yuan, Shuang; Peng, Dinghua; Hu, Xianluo; Gong, Jingming

2013-06-27

129

Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc-iron layered double hydroxides by one-step coprecipitation route  

SciTech Connect

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Moessbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO{sub 4} {sup 2-}-containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO{sub 4} {sup 2-}-containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn{sub 0.435}.Fe{sup II} {sub 0.094}.Fe{sup III} {sub 0.470}.(OH){sub 2}].(SO{sub 4} {sup 2-}){sub 0.235}.1.0H{sub 2}O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO{sub 4} {sup 2-}-containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS. - Graphical abstract: For Zn{sup 2+}-Fe{sup 2+}-Fe{sup 3+} GR2(SO{sub 4} {sup 2-}), according to the derived chemical formula, Fe{sup 3+} was arranged at 1a (0, 0, 0) position, while all Zn{sup 2+} were in 2d position with the occupancy 0.645, and the left part of 2d positions were taken by Fe{sup 2+}/Fe{sup 3+}.

Zhang Hui [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Box 98, Beijing 100029 (China)], E-mail: huizhang67@gst21.com; Wen Xing [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Box 98, Beijing 100029 (China); Wang Yingxia [State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2007-05-15

130

Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System  

PubMed Central

We incorporated anti-Parkinsonian drug, levodopa (dopa), in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay). PMID:24782658

Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Hussein, Mohd Zobir; Fakurazi, Sharida

2014-01-01

131

Photophysical properties of donor- N-Ary-Product -acceptor azoic chromophores adsorbed and intercalated into Mg--Al--LDH  

SciTech Connect

Ethyl Orange (EO) and 4-aminoazobenzene-4-sulfonic (AS) anions with Donor- N-Ary-Product -Acceptor structure have been intercalated into the layered double hydroxide (LDH), [Mg{sub 0.66} Al{sub 0.34} (OH){sub 2}] (CO{sub 3}){sub 0.17}{center_dot}0.67H{sub 2}O or adsorbed on the external surface of the host by the method of ion-exchange procedures. The photoabsorption and fluorescence properties of the obtained compounds were different from the pure solid phase of EO and AS. It was suggested that the photophysical properties of guests were closely related to the geometry and electrical structure of the guest molecule, which can affect the distribution and orientation of the guests in the layers or on the surface of the host. The host-guest interactions modulate photophysical properties of guest. In addition, the guest having higher molecular dipole moments surface exchanged on Mg--Al--CO{sub 3}--LDH are beneficial to the enhancement of the blue emission than that of intercalation into LDH. - Graphical abstract: Emission spectra of (a) EO (b) EO surface exchanged on Mg--Al--CO{sub 3}--LDH (c) Mg--Al--EO--LDH. Emission spectra of (a) AS (b) Mg--Al--AS--LDH (c) AS surface exchanged on Mg--Al--CO{sub 3}--LDH. The guests having higher molecular dipole moments surface exchanged on Mg--Al--CO{sub 3}--LDH are beneficial to the enhancement of the blue emission than that of intercalation into LDH. Highlights: Black-Right-Pointing-Pointer EO and AS are intercalated into LDHs or adsorbed on the external surface of LDHs. Black-Right-Pointing-Pointer The host-guest interactions modulate photophysical properties of the guest. Black-Right-Pointing-Pointer The guests having higher molecular dipole moments can enhance the blue emission.

Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)] [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Liu, Pengfei; Zhang, Li [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)] [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Dazhou [National Research Center for Certified Reference Materials, Beijing 100013 (China)] [National Research Center for Certified Reference Materials, Beijing 100013 (China)

2013-02-15

132

Double layer hydroxide minerals as host structures for bioorganic molecules. [Abstract only  

NASA Technical Reports Server (NTRS)

A central problem in molecular evolution concerns the selective concentration from dilute, multicomponent solution of source molecules into a reactive environment, where formation of larger molecular assemblages can take place. Minerals consisting of positively charged, separable metal hydroxide sheets have proven capable of these functions. This common structural type is represented by minerals such as pyroaurite (Mg-Fe(3+) hydroxide), hydrotalcite (Mg-Al), green rust Fe(2+)-Fe(3+) and others. Effective interlayer sorption is demonstrated for orthophosphate and condensed phosphates, anionic alkyl compounds, polypeptides, nucleic acids, cyanide complexes and glycolaldehyde phosphate, the latter shown to readily oligomerize to form and selectively retain racemic hexose -2, 4, 6-phosphates, preferentially of altrose (Pitsch, et al, 1993). The selective aldomerization and retention effects correlate with the charge distribution in the host mineral structure and the stereochemistry of the substrate molecules. Interaction between nucleic acid bases, and between the cyanide groups of glycolaldehyde phosphate nitrile at the low water activity in the mineral interlayer is indicated by doubling of the monomeric separation of the hydroxide mineral sheets.

Lee, Ton; Arrhenius, Meichia L.; Hui, Stella S.-Y.; Ring, Ken M.; Gedulin, Benjamin I.; Orgel, Leslie E.; Arrhenius, Gustaf

1994-01-01

133

Mg/Al Ordering in Layered Double Hydroxides Revealed by Multinuclear NMR Spectroscopy  

SciTech Connect

The anion-exchange ability of layered double hydroxides (LDHs) has been exploited to create materials for use in catalysis, drug delivery, and environmental remediation. The specific cation arrangements in the hydroxide layers of hydrotalcite-like LDHs, of general formula Mg2+1–xAl3+xOH2(Anionn– x/n)·yH2O, have, however, remained elusive, and their elucidation could enhance the functional optimization of these materials. We applied rapid (60 kilohertz) magic angle spinning (MAS) to obtain high-resolution hydrogen-1 nuclear magnetic resonance (1H NMR) spectra and characterize the magnesium and aluminum distribution. These data, in combination with 1H-27Al double-resonance and 25Mg triple-quantum MAS NMR data, show that the cations are fully ordered for magnesium:aluminum ratios of 2:1 and that at lower aluminum content, a nonrandom distribution of cations persists, with no Al3+-Al3+ close contacts. The application of rapid MAS NMR methods to investigate proton distributions in a wide range of materials is readily envisaged.

Sideris, Paul J.; Nielsen, Ulla G.; Gan, Zhehong; Grey, Clare P.

2008-07-04

134

Controlled synthesis and investigation of the mechanism of formation of hollow hemispherical protrusions on laurate anion-intercalated Zn/Al layered double hydroxide hybrid films.  

PubMed

Films of laurate (La) anion-intercalated zinc-aluminum layered double hydroxides (ZnAl-La-LDHs) with hollow hemispherical protrusions on the surface of the hybrid film have been conveniently prepared by an ion-exchange reaction of a nitrate-containing LDH film previously grown in situ on a porous anodic alumina/aluminum (PAO/Al) substrate. No template is required to form the hemispherical protrusions, thus avoiding a complicated template removal process. The dimensions, morphology, and resistance to bursting of the hollow hemispherical protrusions can be easily tuned by varying the experimental conditions such as sodium laurate concentration, reaction time, and reaction temperature. The evolution of the hollow protrusions was investigated by scanning electron microscopy (SEM), and a "bubble template-reconfiguration assembly" mechanism, in which air bubbles on the film surface act as a template, has been proposed to explain their formation. When the ion-exchange reaction was carried out on a film that had been treated by ultrasound to eliminate surface air bubbles, no hemispherical protrusions were formed, which is consistent with the proposed mechanism. PMID:22840873

Yue, Caili; Chen, Hongyun; Xu, Sailong; Zhang, Fazhi

2012-11-01

135

Zinc/Aluminum layered double hydroxide-titanium dioxide composite nanosheet film as novel solid phase microextraction fiber for the gas chromatographic determination of valproic acid.  

PubMed

A nanosheet thin film based on Zn/Al layered double hydroxide (LDH) and TiO(2) composite was prepared via sol-gel process on capillary glass rod. Characterization of the fiber coating using X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) images showed that it consists of a large number of intercrossed and curved nanosheets with hexagonal architecture. The thickness of these plates is about few nanometers, and the lateral dimension is varying from 400 to 1000 nm. Application of the proposed coating as a solid phase microextraction fiber was investigated. As a model analyte, valproic acid (VPA, antiepileptic drug) was selected and its extraction from biological (human serum) and pharmaceutical (tablet and syrup) samples were performed without any considerable matrix effect. Analytical merits of the method, under optimum conditions (extraction temperature: 50 ± 1°C, extraction time: 15 min, desorption temperature: 250°C, desorption time: 2 min, solution pH: 1.5, salt concentration: 5 mol L(-1)), are 70 ?g L(-1) and 0.20-100 mg L(-1) for LOD and LDR, respectively. PMID:23200379

Matin, Amir Abbas; Biparva, Pourya; Amanzadeh, Hatam; Farhadi, Khalil

2013-01-15

136

Effect of intercalated aromatic sulfonates on uptake of aromatic compounds from aqueous solutions by modified Mg-Al layered double hydroxide  

SciTech Connect

In this study, we utilized Mg-Al layered double hydroxide (Mg-Al LDH) modified by intercalation with three aromatic sulfonates-2,7-naphthalene disulfonate (2,7-NDS{sup 2-}), benzenesulfonate (BS{sup -}), and benzenedisulfonate (BDS{sup 2-})-for the uptake of two aromatics-1,3-dinitrobenzene (DNB) and anisole (AS)-from aqueous solution and determined the effect of the aromatic sulfonates on the uptake of these aromatics. We found that the electron-rich aromatic ring of the intercalated aromatic sulfonates such as 2,7-NDS{sup 2-} undergoes strong {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB in aqueous solution, and these interactions result in a higher uptake of DNB by the modified Mg-Al LDHs. In contrast, the electron-poor aromatic ring of the aromatic sulfonates such as BDS{sup 2-} undergoes weak {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB, and these interactions result in a lower uptake of DNB by the modified Mg-Al LDHs.

Kameda, Tomohito, E-mail: kameda@env.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)] [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yamazaki, Takashi; Yoshioka, Toshiaki [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)] [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2010-06-15

137

Mesoporous mixed metal oxides derived from P123-templated Mg-Al layered double hydroxides  

NASA Astrophysics Data System (ADS)

We report the preparation of mesoporous mixed metal oxides (MMOs) through a soft template method. Different amounts of P123 were used as structure directing agent to synthesize P123-templated Mg-Al layered double hydroxides (LDHs). After calcination of as-synthesized LDHs at 500 °C, the ordered mesopores were obtained by removal of P123. The mesoporous Mg-Al MMOs fabricated by using 2 wt% P123 exhibited a high specific surface area of 108.1 m 2/g, and wide distribution of pore size (2-18 nm). An investigation of the "memory effect" of the mesoporous MMOs revealed that they were successfully reconstructed to ibuprofen intercalated LDHs having different gallery heights, which indicated different intercalation capacities. Due to their mesoporosity these unique MMOs have particular potential as drug or catalyst carriers.

Wang, Jun; Zhou, Jideng; Li, Zhanshuang; He, Yang; Lin, Shuangshuang; Liu, Qi; Zhang, Milin; Jiang, Zhaohua

2010-11-01

138

Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-} redox in the interlayer determined by the charge density of Zn{sub n}Cr-layered double hydroxides  

SciTech Connect

Redox of Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} in the ZnCr layered double hydroxide interlayer has been investigated. The conversion from Fe(CN){sub 6}{sup 3-} to Fe(CN){sub 6}{sup 4-} or from Fe(CN){sub 6}{sup 4-} to Fe(CN){sub 6}{sup 3-} in the ZnCr-LDH interlayer has been confirmed, depending on the Zn:Cr molar ratio. Both Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} are observed in all samples no matter whether the initial anion is Fe(CN){sub 6}{sup 3-} or Fe(CN){sub 6}{sup 4-} before precipitation. Deconvolution of the FTIR band around 2100 cm{sup -1} reveals that the relative amount of Fe(CN){sub 6}{sup 4-} and Fe(CN){sub 6}{sup 3-} in the LDH interlayer is considerably dependent on the Zn:Cr molar ratio. In brief, Fe(CN){sub 6}{sup 4-} is preferred at the ratio of 2:1 while there is more Fe(CN){sub 6}{sup 3-} in the ratio of 4:1. Therefore, it is our hypothesis that the charge density of the hydroxide layer is a key factor that directs the redox of Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-}. The possible redox processes have also been proposed. - Graphical abstract: Redox reactions of Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} take place in the ZnCr layered double hydroxide (LDH) interlayer, which are reflected by Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-} FTIR area ratio. Highlights: Black-Right-Pointing-Pointer An interlayer redox phenomena was observed in Fe(CN){sub 6}{sup 3/4-} intercalated ZnCr-LDHs. Black-Right-Pointing-Pointer The ratio of interlayer redox was examined by FTIR fitting analysis. Black-Right-Pointing-Pointer The tendency of redox was influenced by Zn:Cr molar ratio. Black-Right-Pointing-Pointer The mechanism relies on the charge density of metal hydroxyl layer.

Zhang, Jia; Xu, Yunfeng; Liu, Jiangyong; Zhou, Jizhi [School of Environmental and Chemical Engineering, Shanghai University, No. 333 Nanchen Rd, Shanghai 200444 (China)] [School of Environmental and Chemical Engineering, Shanghai University, No. 333 Nanchen Rd, Shanghai 200444 (China); Xu, Zhi Ping, E-mail: gordonxu@uq.edu.au [ARC Centre of Excellence for Functional Nanomaterials, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072 (Australia); Qian, Guangren, E-mail: grqian@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, No. 333 Nanchen Rd, Shanghai 200444 (China)] [School of Environmental and Chemical Engineering, Shanghai University, No. 333 Nanchen Rd, Shanghai 200444 (China)

2013-02-15

139

Friction behavior of Mg-Al-CO3 layered double hydroxide prepared by magnesite  

NASA Astrophysics Data System (ADS)

In this paper, Mg-Al-CO3 LDH was prepared by magnesite under chemical precipitation and hydrothermal methods. In order to improve the dispersion of LDH in base oil, the as-prepared sample was modified with sodium laurate. The obtained material (GMAC-LDH) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry and thermo gravimetric analyzer (DSC-TGA) and scanning electron microscope (SEM). The results show that the modified LDH has platelet morphology with a near hexagon shape. In addition, the tribological properties of GMAC-LDH were evaluated by four-ball friction tester and gear tester. As a lubricant, GMAC-LDH possesses an excellent property on reducing friction and wear of friction pair. The results of friction tests indicated that the friction coefficient, diameter of wear scar and power consumption of the oil with GMAC-LDH was reduced by 11.0%, 8.5% and 2.1% as compared with that of base oil.

Wang, Xiaobo; Bai, Zhimin; Zhao, Dong; Zhao, Fuyan

2013-07-01

140

Flexible CoAl LDH@PEDOT core/shell nanoplatelet array for high-performance energy storage.  

PubMed

A CoAl-layered double hydroxide (LDH)@poly(3,4-ethylenedioxythiophene) (PEDOT) core/shell nanoplatelet array (NPA) is grown on a flexible Ni foil substrate as a high-performance pseudocapacitor. The LDH@PEDOT core/shell NPA shows a maximum specific capacitance of 649 F/g (based on the total mass) by cyclic voltammetry (scan rate: 2 mV/s) and 672 F/g by galvanostatic discharge (current density: 1 A/g). Furthermore, the hybrid NPA electrode also exhibits excellent rate capability with a specific energy of 39.4 Wh/kg at a current density of 40 A/g, as well as good long-term cycling stability (92.5% of its original capacitance is retained after 5000 cycles). These performances are superior to those of conventional supercapacitors and LDH NPA without the PEDOT coating. The largely enhanced pseudocapacitor behavior of the LDH@PEDOT NPA electrode is related to the synergistic effect of its individual components: the LDH nanoplatelet core provides abundant energy-storage capacity, while the highly conductive PEDOT shell and porous architecture facilitate the electron/mass transport in the redox reaction. PMID:22961997

Han, Jingbin; Dou, Yibo; Zhao, Jingwen; Wei, Min; Evans, David G; Duan, Xue

2013-01-14

141

DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION  

SciTech Connect

This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.

OGDEN DM; KIRCH NW

2007-10-31

142

Pectin-coated chitosan-LDH bionanocomposite beads as potential systems for colon-targeted drug delivery.  

PubMed

This work introduces results on a new drug delivery system (DDS) based on the use of chitosan/layered double hydroxide (LDH) biohybrid beads coated with pectin for controlled release in the treatment of colon diseases. Thus, the 5-aminosalicylic acid (5ASA), the most used non-steroid-anti-inflammatory drug (NSAID) in the treatment of ulcerative colitis and Crohn's disease, was chosen as model drug aiming to a controlled and selective delivery in the colon. The pure 5ASA drug and the hybrid material prepared by intercalation in a layered double hydroxide of Mg2Al using the co-precipitation method, were incorporated in a chitosan matrix in order to profit from its mucoadhesiveness. These compounds processed as beads were further treated with the polysaccharide pectin to create a protective coating that ensures the stability of both chitosan and layered double hydroxide at the acid pH of the gastric fluid. The resulting composite beads presenting the pectin coating are stable to water swelling and procure a controlled release of the drug along their passage through the simulated gastrointestinal tract in in vitro experiments, due to their resistance to pH changes. Based on these results, the pectin@chitosan/LDH-5ASA bionanocomposite beads could be proposed as promising candidates for the colon-targeted delivery of 5ASA, with the aim of acting only in the focus of the disease and minimizing side effects. PMID:24374607

Ribeiro, Lígia N M; Alcântara, Ana C S; Darder, Margarita; Aranda, Pilar; Araújo-Moreira, Fernando M; Ruiz-Hitzky, Eduardo

2014-03-10

143

Direct synthesis of Co2Al(OH)7-2x(CO3)x·nH2O layered double hydroxide nanolayers by successive ionic layer deposition and their capacitive performance  

NASA Astrophysics Data System (ADS)

New method of synthesis of Co2Al(OH)7-2x(CO3)x·nH2O layered double hydroxide (LDH) films by successive ionic layer deposition (SILD) is presented in this paper. The obtained nanolayers were characterized by SEM, EDX, XRD, XPS, FTIR spectroscopy and electrochemical techniques. The results showed that the as-synthesized product is formed by nanosheets with a thickness of 3-5 nm, having hydrotalcite crystal structure. Electrochemical characterization of the sample prepared by 50 cycles of SILD indicated a capacitive behavior with the specific capacitance value of 900 F/g at a current density of 1 A/g and 950 F/g at 0.5 A/g in 1 mol/L KOH aqueous solution. Repeated cycling for 1000 charge-discharge cycles demonstrate that capacitance increases by 6%, so such electrodes may be used as electrodes of hybrid supercapacitors. The presented convenient route of synthesis may be used for the preparation of LDH films with high surface area and a large capacitance.

Lobinsky, A. A.; Tolstoy, V. P.; Gulina, L. B.

2014-11-01

144

Catalytic performance of Ni-Al layered double hydroxides in CO purification processes  

NASA Astrophysics Data System (ADS)

Ni-Al layered double hydroxides with Ni2+/Al3+ molar ratios of 1.5 and 3.0 have been synthesized by co-precipitation and studied as catalyst precursors for purification of CO-containing gas-mixtures by means of CO oxidation to CO2 and conversion of CO by water vapor (water-gas shift reaction). The influence of the alkali additives (K+ ions) on the water-gas shift activity has been also examined. It was established that the catalytic activity of both reactions increases with the temperature and the nickel content. Hypothetic schemes are proposed about activation of the catalysts in the WGSR and CO oxidation including redox Ni2+ ? Ni3+ transition on the catalyst surface. The activity in WGSR is positively affected by the presence of potassium promoter, depending on its amount. The sample with higher nickel loading is the most effective catalyst as for CO oxidation as well as for WGSR at intermediate temperatures after potassium promotion.

Gabrovska, M.; Idakiev, V.; Tenchev, K.; Nikolova, D.; Edreva-Kardjieva, R.; Crisan, D.

2013-12-01

145

Adsorption properties of Mg-Al layered double hydroxides thin films grown by laser based techniques  

NASA Astrophysics Data System (ADS)

Powdered layered double hydroxides (LDHs) have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic and/or organic molecules. Assembling nano-sized LDHs onto flat solid substrates forming thin films is an expanding area of research due to the prospects of novel applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. Continuous and adherent thin films were grown by laser techniques (pulsed laser deposition - PLD and matrix assisted pulsed laser evaporation - MAPLE) starting from targets of Mg-Al LDHs. The capacity of the grown thin films to retain a metal (Ni) from contaminated water has been also explored. The thin films were immersed in an Ni(NO3)2 aqueous solutions with Ni concentrations of 10-3% (w/w) (1 g/L) and 10-4% (w/w) (0.1 g/L), respectively. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) were the techniques used to characterize the prepared materials.

Matei, A.; Birjega, R.; Vlad, A.; Filipescu, M.; Nedelcea, A.; Luculescu, C.; Zavoianu, R.; Pavel, O. D.; Dinescu, M.

2012-09-01

146

Synthesis and UV absorption properties of 5-sulfosalicylate-intercalated Zn-Al layered double hydroxides  

SciTech Connect

5-sulfosalicylic acid (SSA) anions have been intercalated into layered double hydroxides (LDHs) by an anion-exchange reaction using ZnAl-NO{sub 3}-LDHs as a precursor. The samples were characterized by XRD, FT-IR, TG-DTA/MS and UV-visible spectroscopy. The results show that the NO{sub 3} {sup -} anions in the precursor have been completely replaced by SSA anions to give ZnAl-SSA-LDHs having a high degree of crystallinity. Detailed studies reveal the existence of a supramolecular structure in ZnAl-SSA-LDHs involving electrostatic attraction between opposite charges, hydrogen bonding and other weak chemical bonding interactions between host layers and SSA anions. The thermal stability of ZnAl-SSA-LDHs is considerably enhanced compared with that of a mixture of ZnAl-NO{sub 3}-LDHs and SSA. After addition of 2.0 wt% ZnAl-SSA-LDHs to polypropylene (PP), the resistance of the polymer to UV degradation is significantly improved. - Graphical abstract: UV-visible absorbance curves of SSA (a), ZnAl-NO{sub 3}-LDHs precursor (b) and ZnAl-SSA-LDHs (c)

Zhang Linyan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Lin Yanjun [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tuo Zhenjun [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Evans, David G. [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Li Dianqing [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: lidq@mail.buct.edu.cn

2007-04-15

147

Deconstruction of Lignin Model Compounds and Biomass-Derived Lignin using Layered Double Hydroxide Catalysts  

SciTech Connect

Lignin is an underutilized value stream in current biomass conversion technologies because there exist no economic and technically feasible routes for lignin depolymerization and upgrading. Base-catalyzed deconstruction (BCD) has been applied for lignin depolymerization (e.g., the Kraft process) in the pulp and paper industry for more than a century using aqueous-phase media. However, these efforts require treatment to neutralize the resulting streams, which adds significantly to the cost of lignin deconstruction. To circumvent the need for downstream treatment, here we report recent advances in the synthesis of layered double hydroxide and metal oxide catalysts to be applied to the BCD of lignin. These catalysts may prove more cost-effective than liquid-phase, non-recyclable base, and their use obviates downstream processing steps such as neutralization. Synthetic procedures for various transition-metal containing catalysts, detailed kinetics measurements using lignin model compounds, and results of the application of these catalysts to biomass-derived lignin will be presented.

Chmely, S. C.; McKinney, K. A.; Lawrence, K. R.; Sturgeon, M.; Katahira, R.; Beckham, G. T.

2013-01-01

148

Preparation of layered double hydroxide/chlorophyll a hybrid nano-antennae: a key step.  

PubMed

In the first step to obtain an efficient nano-antenna in a bottom-up approach, new hybrid materials were synthesized using a set of layered double hydroxides (LDHs) with basic properties and pure chlorophyll a (Chl a). The stability of the adsorbed monolayer of Chl a was shown to be dependent on the nature and the ratio of the different metal ions present in the LDHs tested. The hybrid materials turned out to be adequate for stabilizing Chl a on Mg/Al LDHs for more than a month under ambient conditions while a limited catalytic decomposition was observed for the Ni/Al LDHs leading to the formation of pheophytin. These changes were followed by namely XRD, DR-UV-vis and fluorescence spectroscopies of the hybrid antennae and of the solutions obtained from their lixiviation with acetone or diethylether. On Mg/Al hydrotalcites the stability of the adsorbed Chl a was equivalent for values of the metal atom ratio ranging from 2 to 4. The latter hybrids should constitute a good basis to form efficient nanoscale light harvesting units following intercalation of selected dyes. This work describes an efficient preparation of Chl a that allows scale-up as well as the obtention of a stable Chl a monolayer on the surface of various LDHs. PMID:24676400

Sommer Márquez, Alicia E; Lerner, Dan A; Fetter, Geolar; Bosch, Pedro; Tichit, Didier; Palomares, Eduardo

2014-07-21

149

Mechanochemical approach to get layered double hydroxides: Mechanism explore on crystallite growth  

NASA Astrophysics Data System (ADS)

In this paper, the mechanochemical approach, which includes solid state reactions and hydrothermal treatment, has been proposed to synthesize magnesium-aluminum-layered double hydroxides (Mg-Al-LDHs). Specially, the reaction process of solid state reactions has been explored, and it presents that crystallite growth is the rate-controlling process. The hydrothermal treatment is performed after solid state reactions, on one hand, the crystallinity and monodispersity of final LDHs particles can be improved, on the other hand, such treatment can tailor the particle size efficiently. Furthermore, the relationship between particle size and hydrothermal conditions (time and temperature) has been systematically investigated, which indicates that the particle size and monodispersity can be effectively controlled. The crystallite growth along a-b plane and c-axis has been emphatically discussed, and the results show that under relatively low temperatures such as 100 °C, the gradual growth along c-axis has been found in the range of 48 h, and high temperatures will hider its growth on the contrary. Crystal growth along a-b plane could be accelerated by higher hydrothermal temperature and longer treatment time. Our studies also show that during the hydrothermal treatment, such events as aggregation, disaggregation and particle growth, occur in series or in parallel with time. At last, the Mg-Al-CO3-LDHs samples (synthesized at 100 °C for 24, 36 and 48 h) which were acid activated by HCOOH were used to adsorb fluoride ions present in aqueous solution.

Zeng, Mei-Gui; Huo, Xiao-Lei; Liu, Su-Qing; Li, Shu-Ping; Li, Xiao-Dong

2014-02-01

150

Concentration of simple aldehydes by sulfite-containing double-layer hydroxide minerals: implications for biopoesis  

NASA Technical Reports Server (NTRS)

Environmental conditions play an important role in conceptual studies of prebiotically relevant chemical reactions that could have led to functional biomolecules. The necessary source compounds are likely to have been present in dilute solution, raising the question of how to achieve selective concentration and to reach activation. With the assumption of an initial 'RNA World', the questions of production, concentration, and interaction of aldehydes and aldehyde phosphates, potential precursors of sugar phosphates, come into the foreground. As a possible concentration process for simple, uncharged aldehydes, we investigated their adduct formation with sulfite ion bound in the interlayer of positively charged expanding-sheet-structure double-layer hydroxide minerals. Minerals of this type, initially with chloride as interlayer counter anion, have previously been shown to induce concentration and subsequent aldolization of aldehyde phosphates to form tetrose, pentose, and hexose phosphates. The reversible uptake of the simple aldehydes formaldehyde, glycolaldehyde, and glyceraldehyde by adduct formation with the immobilized sulfite ions is characterized by equilibrium constants of K=1.5, 9, and 11, respectively. This translates into an observable uptake at concentrations exceeding 50 mM.

Pitsch, S.; Krishnamurthy, R.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

2000-01-01

151

Evolution of rheological properties of the nanofluids composed of laponite particles and Mg-Fe layered double hydroxide nanosheets  

SciTech Connect

The thixotropic clay suspensions composed of laponite particles and Mg–Fe layered double hydroxide nanosheets were examined. By adding a very small amount of the layered double hydroxide nanosheets overall rheological properties of the host laponite suspension have been changed. Though the particle concentration of the mixture suspension is only about 1 wt%, the mixture quickly becomes a gel in a day by the electrostatic attraction between nano-materials. When a constant shear rate is applied to the mixture gel suspension, at short time, stress increases linearly with elastic deformation of the mixture. Beyond the maximum of stress, while the solid-like gel structure is being broken down with time of shearing, the stress increases again by reflecting shear enhanced association of solid phase. This is likely that the mixture suspension shows partially the behavior of memory effect.

Hur, Tae-Bong; Phuoc, Tran X.; Chyu, Minking K.; Romanov, Vyacheslav

2011-05-04

152

Controlled release of herbicide into water from beta-naphtoxyacetic acid-layered double hydroxide nanohybrid formulation  

Microsoft Academic Search

At present, the use of huge quantities of herbicides in conventional agriculture has lead to some major environmental problems. Controlled release formulations (CRF) are now being developed to avoid such problems. The release of beta-naphtoxyacetic acid (BNOA) into aqueous solution from controlled-release formulation (CRF) prepared by the intercalation of BNOA anion into Zn-Al-layered double hydroxide (ZAL) was studied. CRF consisting

Z. binti Jubri; N. Z. A. binti Mohd Yusoff; E. S. binti Marsom; S. H. binti Sarijo

2009-01-01

153

Ni-based supported catalysts from layered double hydroxides: Tunable microstructure and controlled property for the synthesis of carbon nanotubes  

Microsoft Academic Search

The carbon nanotubes (CNTs) with straight and helical nanostructures have been synthesized by catalytic chemical vapor deposition of acetylene over a series of Ni-based supported catalysts, which were formed from Ni–Mg–Al layered double hydroxide precursors (LDHs) synthesized through homogenous decomposition of urea under hydrothermal conditions. The materials were characterized by power X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron

Lu Zhang; Feng Li; Xu Xiang; Min Wei; David G. Evans

2009-01-01

154

Influence of reduction temperature on composition, particle size, and magnetic properties of CoFe alloy nanomaterials derived from layered double hydroxide precursors.  

PubMed

Individual CoFe alloy nanoparticles and CoFe-MgO nanocomposites were prepared through thermal reduction of single-source layered double hydroxide (LDH) precursors at various temperatures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses to investigate the influence of reduction temperature on the composition, particle size and size distribution, as well as the magnetic properties of the resulting materials. XRD and SEM results show that the as-prepared CoFe alloy nanoparticles and CoFe-MgO nanocomposites display high crystallinity and high purity. The average particle size of individual CoFe nanoparticles increases with the increase of reduction temperature. In the presence of the MgO matrix, uniform CoFe alloy nanoparticles with a narrow diameter distribution (8-11 nm) were obtained. Magnetic measurements indicate that the saturation magnetization strength (Ms) of the resulting materials increases with reduction temperature. The individual CoFe alloy nanoparticles exhibit excellent soft magnetic behavior with an extremely high Ms value (213 emu g(-1) at 800 °C), comparable to that of bulk CoFe alloy (230 emu g(-1)). For CoFe-MgO nanocomposites, small Ms values were obtained due to the small CoFe alloy particle size and low percentage of magnetic component. However, the coercivities are greatly enhanced (663 Oe at 450 °C) for the composites, implying their potential applications in data storage and other magnetic devices. PMID:24695765

Yang, Shuangxia; Wang, Lianying; Yue, Shuang; Lu, Yanluo; He, Jing; Zhao, Dongye

2014-06-14

155

Organic Bilayers Intercalated in Zinc(II)Chromium(III) Layered Double Hydroxides  

Microsoft Academic Search

The intercalation of three different anions derived from carboxylic acids is reported. It was shown that the intercalated anions of cholic and diphenylacetic acids form bilayers in the LDH interlamellar domain with different interactions involved in such arrangements. Each anion species showed the same interlayer arrangement for different Zn(II)\\/Cr(III) ratios, probably due to the intermolecular interactions that maintain the interlayer

Cleberson Cipriano De Paula; Eduardo Luis Crepaldi; Jairo Tronto; Paulo César Pavan; João Barros Valim

2001-01-01

156

Selenium adsorption and speciation with Mg-FeCO? layered double hydroxides loaded cellulose fibre.  

PubMed

A novel adsorbent was developed by coating Mg-FeCO(3) layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO(3) LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 ? L of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L(-1) HCl at 80°C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L(-1) within a linear range of 0.04-4.0 ?g L(-1). A relative standard deviation (RSD) of 3.3% (0.5 ?g L(-1), n=11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. PMID:22748552

Chen, Ming-Li; An, Myog-Il

2012-06-15

157

The Synthesis and Characterization of Gold-Core/LDH-Shell Nanoparticles  

NASA Astrophysics Data System (ADS)

In recent years, the field of nanomedicine has progressed at an astonishing rate, particularly with respect to applications in cancer treatment and molecular imaging. Although organic systems have been the frontrunners, inorganic systems have also begun to show promise, especially those based upon silica and magnetic nanoparticles (NPs). Many of these systems are being designed for simultaneous therapeutic and diagnostic capabilities, thus coining the term, theranostics. A unique class of inorganic systems that shows great promise as theranostics is that of layered double hydroxides (LDH). By synthesis of a core/shell structures, e.g. a gold nanoparticle (NP) core and LDH shell, the multifunctional theranostic may be developed without a drastic increase in the structural complexity. To demonstrate initial proof-of-concept of a potential (inorganic) theranostic platform, a Au-core/LDH-shell nanovector has been synthesized and characterized. The LDH shell was heterogeneously nucleated and grown on the surface of silica coated gold NPs via a coprecipitation method. Polyethylene glycol (PEG) was introduced in the initial synthesis steps to improve crystallinity and colloidal stability. Additionally, during synthesis, fluorescein isothiocyanate (FITC) was intercalated into the interlayer spacing of the LDH. In contrast to the PEG stabilization, a post synthesis citric acid treatment was used as a method to control the size and short-term stability. The heterogeneous core-shell system was characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), dynamic light scattering (DLS), and powder x-ray diffraction (PXRD). A preliminary in vitro study carried out with the assistance of Dr. Kaushal Rege's group at Arizona State University was to demonstrate the endocytosis capability of homogeneously-grown LDH NPs. The DLS measurements of the core-shell NPs indicated an average particle size of 212nm. The PXRD analysis showed that PEG greatly improved the crystallinity of the system while simultaneously preventing aggregation of the NPs. The preliminary in vitro fluorescence microscopy revealed a moderate uptake of homogeneous LDH NPs into the cells.

Rearick, Colton

158

New SnO2/MgAl-layered double hydroxide composites as photocatalysts for cationic dyes bleaching.  

PubMed

A new type of nanocomposite containing SnO(2) has been obtained by wet impregnation of dehydrated Mg/Al-hydrotalcite-type compounds with ethanolic solutions of SnCl(4).2H(2)O. Tin chloride hydrolysis was achieved using NaOH or NH(4)OH aqueous solutions, at pH around 9, followed by the conversion into corresponding hydroxides through calcinations. The powder X-ray diffraction (PXRD) and UV-Vis diffuse reflectance (UV-DR) methods confirmed the structure of as-synthesized solids. The chemical composition and morphology of the synthesized materials were investigated by energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-synthesized materials were used for photocatalytic studies showing a good activity for methylene blue decolourization, which varies with SnO(2) content and used as a hydrolysing agent. The proposed mechanism is based on the shifting of flat band potential of SnO(2) due to the interaction with Mg/Al-LDH, this being energetically favourable to the formation of hydroxyl radicals responsible for methylene blue degradation. PMID:20045244

Dvininov, E; Ignat, M; Barvinschi, P; Smithers, M A; Popovici, E

2010-05-15

159

Mixed oxides obtained from Co and Mn containing layered double hydroxides: Preparation, characterization, and catalytic properties  

SciTech Connect

Co-Mn-Al layered double hydroxides (LDHs) with various Co:Mn:Al molar ratios (4:2:0, 4:1.5:0.5, 4:1:1, 4:0.5:1.5, and 4:0:2) were prepared and characterized. Magnesium containing LDHs Co-Mg-Mn (2:2:2), Co-Mg-Mn-Al (2:2:1:1), and Co-Mg-Al (2:2:2) were also studied. Thermal decomposition of prepared LDHs and formation of related mixed oxides were studied using high-temperature X-ray powder diffraction and thermal analysis. The thermal decomposition of Mg-free LDHs starts by their partial dehydration accompanied by shrinkage of the lattice parameter c from ca. 0.76 to 0.66 nm. The dehydration temperature of the Co-Mn-Al LDHs decreases with increasing Mn content from 180 deg. C in Co-Al sample to 120 deg. C in sample with Co:Mn:Al molar ratio of 4:1.5:0.5. A subsequent step is a complete decomposition of the layered structure to nanocrystalline spinel, the complete dehydration, and finally decarbonation of the mixed oxide phase. Spinel-type oxides were the primary crystallization products. Mg-containing primary spinels had practically empty tetrahedral cationic sites. A dramatic increase of the spinel cell size upon heating and analysis by Raman spectroscopy revealed a segregation of Co-rich spinel in Co-Mn and Co-Mn-Al specimens. In calcination products obtained at 500 deg. C, the spinel mean coherence length was 5-10 nm, and the total content of the X-ray diffraction crystalline portion was 50-90%. These calcination products were tested as catalysts in the total oxidation of ethanol and decomposition of N{sub 2}O. The catalytic activity in ethanol combustion was enhanced by increasing (Co+Mn) content while an optimum content of reducible components was necessary for high activity in N{sub 2}O decomposition, where the highest conversions were found for calcined Co-Mn-Al sample with Co:Mn:Al molar ratio of 4:1:1.

Kovanda, Frantisek [Department of Solid State Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic)]. E-mail: Frantisek.Kovanda@vscht.cz; Rojka, Tomas [Department of Solid State Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Dobesova, Jana [Department of Solid State Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Machovic, Vladimir [Laboratory of Molecular Spectroscopy, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Bezdicka, Petr [Institute of Inorganic Chemistry, Academy of Sciences of Czech Republic, 250 68 Rez (Czech Republic); Obalova, Lucie [Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava (Czech Republic); Jiratova, Kveta [Institute of Chemical Process Fundamentals, Academy of Sciences of Czech Republic, Rozvojova 135, 165 02 Prague (Czech Republic); Grygar, Tomas [Institute of Inorganic Chemistry, Academy of Sciences of Czech Republic, 250 68 Rez (Czech Republic)

2006-03-15

160

Mixed oxides obtained from Co and Mn containing layered double hydroxides: Preparation, characterization, and catalytic properties  

NASA Astrophysics Data System (ADS)

Co-Mn-Al layered double hydroxides (LDHs) with various Co:Mn:Al molar ratios (4:2:0, 4:1.5:0.5, 4:1:1, 4:0.5:1.5, and 4:0:2) were prepared and characterized. Magnesium containing LDHs Co-Mg-Mn (2:2:2), Co-Mg-Mn-Al (2:2:1:1), and Co-Mg-Al (2:2:2) were also studied. Thermal decomposition of prepared LDHs and formation of related mixed oxides were studied using high-temperature X-ray powder diffraction and thermal analysis. The thermal decomposition of Mg-free LDHs starts by their partial dehydration accompanied by shrinkage of the lattice parameter c from ca. 0.76 to 0.66 nm. The dehydration temperature of the Co-Mn-Al LDHs decreases with increasing Mn content from 180 °C in Co-Al sample to 120 °C in sample with Co:Mn:Al molar ratio of 4:1.5:0.5. A subsequent step is a complete decomposition of the layered structure to nanocrystalline spinel, the complete dehydration, and finally decarbonation of the mixed oxide phase. Spinel-type oxides were the primary crystallization products. Mg-containing primary spinels had practically empty tetrahedral cationic sites. A dramatic increase of the spinel cell size upon heating and analysis by Raman spectroscopy revealed a segregation of Co-rich spinel in Co-Mn and Co-Mn-Al specimens. In calcination products obtained at 500 °C, the spinel mean coherence length was 5-10 nm, and the total content of the X-ray diffraction crystalline portion was 50-90%. These calcination products were tested as catalysts in the total oxidation of ethanol and decomposition of N 2O. The catalytic activity in ethanol combustion was enhanced by increasing (Co+Mn) content while an optimum content of reducible components was necessary for high activity in N 2O decomposition, where the highest conversions were found for calcined Co-Mn-Al sample with Co:Mn:Al molar ratio of 4:1:1.

Kovanda, František; Rojka, Tomáš; Dobešová, Jana; Machovi?, Vladimír; Bezdi?ka, Petr; Obalová, Lucie; Jirátová, Kv?ta; Grygar, Tomáš

2006-03-01

161

Dramatic activities of vanadate intercalated bismuth doped LDH for solar light photocatalysis.  

PubMed

To harvest solar energy efficiently, a series of Zn/Bi layered double hydroxide (LDH) photocatalysts with different molar ratios of Zn/Bi (2?:?1, 3?:?1, 4?:?1) has been synthesized by a coprecipitation method at constant pH. All the Bi doped LDH samples displayed hydrotalcite-like structure with interlayer carbonate, in which crystallinity decreases as the bismuth content increases. The Zn/Bi (4?:?1) LDH with a small amount of bismuth in the brucite layer and possessing high crystallinity was further modified hydrothermally by intercalating decavanadate and it showed high photochemical stability and photocatalytic activity for the degradation of different organic pollutants for practical applications under solar light irradiation. The structural integrity of the materials has been successfully characterized by studying their structural, morphological, electronic and optical properties by various physico-chemical techniques. The present study provided an insight into oxo-bridged MMCT of the LDH and established that the Zn(II)-O-Bi(III) units resulted in the generation of superoxide radicals which is clearly observed by the EPR technique. The ?OH radicals formed during photocatalysis were revealed by means of the terephthalic acid fluorescence probe method. The photoelectrochemical measurement confirmed that the intercalated vanadate anion was crucial to obtain an optimal synergistic effect for the degradation of organic pollutants. The prolonged lifetime of photogenerated charges and improved charge transfer capability were confirmed by time-resolved fluorescence emission spectra. Furthermore, a detailed mechanism for the enhanced photocatalytic activity was discussed. PMID:25005613

Mohapatra, Lagnamayee; Parida, K M

2014-08-28

162

Synthesis of layered cathode material Li[Co x Mn 1? x ]O 2 from layered double hydroxides precursors  

Microsoft Academic Search

Cathode materials Li[CoxMn1?x]O2 for lithium secondary batteries have been prepared by a new route—precursor method of layered double hydroxides (LDHs). In situ high-temperature X-ray diffraction (HT-XRD) and thermogravimetric analysis coupled with mass spectrometry (TG–MS) were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH·H2O: firstly the layered structure of LDHs transformed to an intermediate phase

Yanluo Lu; Min Wei; Lan Yang; Congju Li

2007-01-01

163

Structure and surface chemistry of manganese-doped copper-based mixed metal oxides derived from layered double hydroxides  

Microsoft Academic Search

The paper reports data relative to the preparation of a series of manganese-doped copper-based mixed metal oxides under identical conditions by calcination of layered double hydroxides (LDHs) at 773K for 5h. LDHs with Cu2+\\/Zn2+\\/Mn2+\\/Fe3+\\/Al3+ molar ratios in synthesis mixture from 1:1:0:0.3:0.7 to 1:0:1:0.3:0.7 have been synthesized by co-precipitation method. The samples of both the as-synthesized LDHs and the corresponding calcined

Feng Li; Lihong Zhang; David G. Evans; Xue Duan

2004-01-01

164

Topochemical synthesis of alkali-metal hydroxide layers within double- and triple-layered perovskites.  

PubMed

The formation of alkali-metal hydroxide layers within lamellar perovskites has been accomplished by a two-step topochemical reaction strategy. Reductive intercalation of ALaNb2O7 with alkali metal (A = K, Rb) and RbCa2Nb3O10 with Rb leads to A2LaNb2O7 and Rb2Ca2Nb3O10, respectively. Oxidative intercalation with stoichiometric amounts of water vapor, produced by the decomposition of calcium oxalate monohydrate in a sealed ampule, allows the insertion hydroxide species. Compounds of the form (A2OH)LaNb2O7 (A = K, Rb) and (Rb2OH)Ca2Nb3O10 are accessible. X-ray diffraction data indicates a clear layer expansion of almost 3 Å on the insertion of hydroxide relative to that of the parent. Rietveld refinement of neutron diffraction data collected on deuterated samples of (Rb2OD)LaNb2O7 (P4/mmm space group, a = 3.9348(1) Å, c = 14.7950(7) Å) finds that both rubidium and oxygen species reside in cubic sites forming a CsCl-like interlayer structure between niobate perovskite blocks. Hydrogens, attached to the interlayer oxygens, are disordered over a 4-fold site in the x-y plane and have O-H bond distances (0.98 Å) consistent with known hydroxide species. This synthetic approach expands the library of available topochemical reactions, providing a facile method for the construction of alkali-metal hydroxide layers within receptive perovskite hosts. PMID:24410708

Montasserasadi, Dariush; Mohanty, Debasish; Huq, Ashfia; Heroux, Luke; Payzant, Edward Andrew; Wiley, John B

2014-02-01

165

Layered double hydroxides as efficient photocatalysts for visible-light degradation of Rhodamine B.  

PubMed

A series of Zn/M-NO3-LDHs (M=Al, Fe, Ti, and Fe/Ti) have been synthesized by two different methods, and their activities for visible-light photocatalytic degradation on Rhodamine B (RB) were tested. Solids were analyzed by XRD, FT-IR, and ICP characterization, confirming the formation of pure LDH phase with good crystal structure. It was observed that the band gap of these nitrate LDH materials was following this order: Zn/Fe-NO3-LDHs (2.55 eV)>Zn/Fe/Ti-NO3-LDHs (2.88 eV)>Zn/Ti-NO3-LDHs (3.0 3eV)>Zn/Al-NO3-LDHs (3.23 eV); however, the degradation performance of RB by four materials followed the order: Zn/Ti-NO3-LDHs (98%)>Zn/Al-NO3-LDHs (96%)>Zn/Fe/Ti-NO3-LDHs (88%)>Zn/Fe-NO3-LDHs (72%). In addition, a possible mechanism for photocatalytic degradation on RB has also been presumed. Moreover, after three regeneration cycles, the percentage of RB degradation rate was still close to 90%. PMID:23786832

Xia, Sheng-Jie; Liu, Feng-Xian; Ni, Zhe-Ming; Xue, Ji-Long; Qian, Ping-Ping

2013-09-01

166

Toxicity and Metabolism of Layered Double Hydroxide Intercalated with Levodopa in a Parkinson's Disease Model  

PubMed Central

Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL) nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 ?g/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA) released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment. PMID:24722565

Kura, Aminu Umar; Ain, Nooraini Mohd; Hussein, Mohd Zobir; Fakurazi, Sharida; Hussein-Al-Ali, Samer Hasan

2014-01-01

167

Toxicity and metabolism of layered double hydroxide intercalated with levodopa in a Parkinson's disease model.  

PubMed

Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL) nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 µg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA) released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment. PMID:24722565

Kura, Aminu Umar; Ain, Nooraini Mohd; Hussein, Mohd Zobir; Fakurazi, Sharida; Hussein-Al-Ali, Samer Hasan

2014-01-01

168

Synthesis and characterization of a mixture of CoFe2O4 and MgFe2O4 from layered double hydroxides: Band gap energy and magnetic responses  

NASA Astrophysics Data System (ADS)

A mixture of nanocrystals of cobalt ferrite and magnesium ferrite was obtained from Layered Double Hydroxides (LDH) through a co-precitation method with a theoretical molar ratio M2+:Fe3+=3:1, where M2+represents Mg2+ and/or Co2+. The molar ratios between Co2+:Fe3+ were 0.0 (0Co), 0.2 (5Co), and 0.4 (10Co). In order to assess the effect on the properties of the LDH and their oxides, the molar percentages were 0, 5 and 10%. Two different synthesis methods were evaluated; (i) ageing at room temperature (rt), and (ii) hydrothermal ageing at 200 °C in autoclave (ht), both methods needed 15 h of ageing. Then, these LDH were calcined in air atmosphere at 550 °C for 10 h. The calcined materials were characterized by X-ray diffraction (XRD), thermogravymetric analysis (TGA), temperature-programmed reduction (TPR), infrared spectroscopy with Fourier transform (FTIR), Diffuse Reflectance UV-visible spectroscopy (UV-vis-DRS), Mössbauer spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES). The magnetic response was analyzed using a vibrating sample magnetometer (VSM). The band gap energy of the iron oxides was determined through the UV-vis-DRS analysis. Through these studies it was possible to identify the presence of a mixture of cobalt ferrite and magnesium ferrite. Samples did not show hematite and cobalt oxides, but the presence of MgO in the periclase phase was determined. This magnesium oxide promoted a good dispersion of the ferrites. Moreover, when a single ferrite phase of Co or Mg was formed, a diminution of the crystal size with consequent enlarged values of band gap energy was observed. Thus, materials synthesized by room temperature ageing promoted the superparamagnetic behaviour of samples, attributed to the content of the cobalt ferrite structure in nanocrystals. In regard to the estimated band gap energy, all samples exhibited low levels. These results indicate that these solids would be suitable for photocatalysts use in all visible light range, and that they could be easily removed from the reaction medium by a simple magnetic separation procedure.

Agú, Ulises A.; Oliva, Marcos I.; Marchetti, Sergio G.; Heredia, Angélica C.; Casuscelli, Sandra G.; Crivello, Mónica E.

2014-11-01

169

Synergetic Effect of SLN-Curcumin and LDH-5-Fu on SMMC-7721 Liver Cancer Cell Line  

PubMed Central

Abstract Curcumin and 5-Fluorouracil (5-Fu) have been reported to have anticancer potentials and show certain synergetic effect on some cancer cell lines. However, the poor bioavailability and rapid metabolism limited their medical application. In this study, we encapsulated curcumin with solid lipid nanoparticles (SLN), 5-Fu with Layered double hydroxides (LDHs) separately and tested its properties and anticancer potentials. SLN-curcumin and LDH-5-Fu were determined to be 100 and 60?nm by Transmission Electron Microscopy detection, and the loading efficiency were 28%±2.5% and 16.7%±1.8%, individually. Furthermore, SLN-curcumin and LDH-5-Fu showed a significantly synergetic effect on SMMC-7721 cell stronger than plain drugs together, of which the Idrug loaded nano-carriers was only 0.315. FACS analysis revealed that the combination of SLN-curcumin and LDH-5-Fu induced 80.1% apoptosis in SMMC-7721 cells, which were 1.7-folds of the sum of the two plain drug loaded carriers. The results demonstrated the significant synergetic anticancer potentials of nano-encapsulated curcumin and 5-Fu, which could be further explored for the treatment of other carcinoma. PMID:23808828

Zhu, Rongrong; Wu, Xianzheng; Xiao, Yu; Gao, Bo; Xie, Qian

2013-01-01

170

Effect of Silicate on the Formation and Stability of Ni-Al LDH at the ?-Al2O3 Surface.  

PubMed

The formation of mixed metal precipitates has been identified as a significant mechanism for the immobilization and elimination of heavy metal ions. Silicate is present in natural systems ubiquitously, which may interfere with metal uptake on the mineral surface and thereby influences the solubility of the precipitate. Herein, kinetic sorption and dissolution experiments combined with extended X-ray absorption fine structure spectroscopy (EXAFS) were performed to elucidate the effect of silicate on the formation of Ni precipitates at the ?-Al2O3 surfaces. The uptake of Ni on ?-Al2O3 decreased with increasing amounts of silicate coated onto the ?-Al2O3 surface. Results of EXAFS analyses suggested the formation of Ni-Al layered double hydroxide (LDH) phases. The surface coating of silicate on ?-Al2O3 reduced Al release and finally resulted in a high Ni:Al ratio due to a lower extent of Al substitution into the precipitates. The presence of silicate prevented the growth of the precipitates and led to the formation of less stable Ni-Al LDH. The influence of silicate on the precipitate formation provided the evidence for the growth relationship between the precipitate and mineral substrate in the real environment. Increased rates of proton-promoted dissolution of Ni surface precipitates were mainly attributed to higher Ni:Al ratios in Ni-Al LDH precipitates formed in the presence of silicate. PMID:25339547

Tan, Xiaoli; Fang, Ming; Ren, Xuemei; Mei, Huiyang; Shao, Dadong; Wang, Xiangke

2014-11-18

171

Development of a biocompatible nanodelivery system for tuberculosis drugs based on isoniazid-Mg/Al layered double hydroxide  

PubMed Central

The primary challenge in finding a treatment for tuberculosis (TB) is patient non-compliance to treatment due to long treatment duration, high dosing frequency, and adverse effects of anti-TB drugs. This study reports on the development of a nanodelivery system that intercalates the anti-TB drug isoniazid into Mg/Al layered double hydroxides (LDHs). Isoniazid was found to be released in a sustained manner from the novel nanodelivery system in humans in simulated phosphate buffer solutions at pH 4.8 and pH 7.4. The nanodelivery formulation was highly biocompatible compared to free isoniazid against human normal lung and 3T3 mouse fibroblast cells. The formulation was active against Mycobacterium tuberculosis and gram-positive bacteria and gram-negative bacteria. Thus results show significant promise for the further study of these nanocomposites for the treatment of TB. PMID:25336952

Saifullah, Bullo; Arulselvan, Palanisamy; El Zowalaty, Mohamed Ezzat; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

2014-01-01

172

Self-assembled 3D flower-like Ni2+-Fe3+ layered double hydroxides and their calcined products.  

PubMed

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets. PMID:19858561

Xiao, Ting; Tang, Yiwen; Jia, Zhiyong; Li, Dawei; Hu, Xiaoyan; Li, Bihui; Luo, Lijuan

2009-11-25

173

Clarification of possible ordered distributions of trivalent cations in layered double hydroxides and an explanation for the observed variation in the lower solid-solution limit  

PubMed Central

The sequence of hexagonal ordered distributions of trivalent cations that are possible in the octahedral layer of layered double hydroxides is clarified, including the link between the composition and the supercell a parameter. A plausible explanation is provided for the observed variation in the lower solid-solution limit. PMID:24253089

Richardson, Ian G.

2013-01-01

174

Zn- and Co-based layered double hydroxides: prediction of the a parameter from the fraction of trivalent cations and vice versa  

PubMed Central

A recently proposed method to calculate the a parameter of the unit cell of layered double hydroxides from the fraction of trivalent cations is extended to Zn- and Co-based phases. It is shown to be useful as a sanity test for extant and future structure determinations and computer-simulation studies. PMID:23873067

Richardson, Ian G.

2013-01-01

175

Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions  

SciTech Connect

A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 A, typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 A. Thermal treatment at 150 {sup o}C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 A. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH{sub 4}(NH{sub 3}){sub n}]{sup +} species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 A basal distance) at pH=7, as well as a pure crystalline phase with 13.9 A basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 {sup o}C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. - Graphical abstract: LDH-nitrate precipitated with ammonia expands the interlayer space if ammonia is bubbled up to pH 10. The basal distance decreased when the compound was heated at 150 {sup o}C or stirred in acetone. Nitrate ions are not exchanged.

Carbajal Arizaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.m [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km. 107 Carretera Tijuana-Ensenada, Apdo. Postal 14, C.P. 22800. Ensenada, Baja California (Mexico); Wypych, Fernando [CEPESQ-Research Centre of Applied Chemistry, Department of Chemistry, Federal University of Parana, P.O. Box 19081, 81531-980 Curitiba, PR (Brazil); Castillon Barraza, Felipe; Contreras Lopez, Oscar Edel [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km. 107 Carretera Tijuana-Ensenada, Apdo. Postal 14, C.P. 22800. Ensenada, Baja California (Mexico)

2010-10-15

176

Aluminum Hydroxide and Magnesium Hydroxide  

MedlinePLUS

Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They ... They combine with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription. ...

177

Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides  

PubMed Central

Background The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. Methodology/Principal Findings The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. Conclusions/Significance S-Ni0.1MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni0.1MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites. PMID:22693627

Wang, Lili; Li, Bin; Zhao, Xiaohong; Chen, Chunxia; Cao, Jingjing

2012-01-01

178

Influence of nature of precursors on the formation and structure of Cu–Ni–Cr mixed oxides from layered double hydroxides  

Microsoft Academic Search

Analogous layered double hydroxides (LDHs) with the Cu2+\\/Ni2+\\/Cr3+ molar ratio of 1\\/2\\/1 on the brucite-like layers and interlayer anions (viz sulfate, nitrate and carbonate, respectively) were synthesized by a coprecipitation method. For the first time, the effects of interlayer anions on the structural properties of as-synthesized LDHs and resulting calcined products at 773K were investigated by means of powder X-ray

Lihong Zhang; Jia Zhu; Xiaorui Jiang; David G. Evans; Feng Li

2006-01-01

179

Influence of the compensating anions of Ni\\/Al and Ni\\/Mg\\/Al layered double hydroxides on their activation under oxidising and reducing atmospheres  

Microsoft Academic Search

The activities and selectivities in the hydrogenation of acetonitrile on catalysts obtained from Ni\\/Al and Ni\\/Mg\\/Al layered double hydroxides (LDHs) precursors depend on the nature of their compensating anions: CO2?3,NO?3 or Cl?. The latter gives rise to sample with low activity and the less selective to primary amine. Studies by XRD, TG–DSC, mass spectrometry and TPR experiments show that the

Olga Lebedeva; Didier Tichit; Bernard Coq

1999-01-01

180

Development of a high analytical performance amperometric glucose biosensor based on glucose oxidase immobilized in a composite matrix: layered double hydroxides\\/chitosan  

Microsoft Academic Search

This paper aimed at showing the interest of the composite material based on layered double hydroxides (LDHs) and chitosan\\u000a (CHT) as suitable host matrix likely to immobilize enzyme onto electrode surface for amperometric biosensing application.\\u000a This hybrid material combined the advantages of inorganic LDHs and organic biopolymer, CHT. Glucose oxidase (GOD) immobilized\\u000a in the composite material maintained its activity well

Qiaofang Shi; En Han; Dan Shan; Wenjuan Yao; Huaiguo Xue

2008-01-01

181

Preparation of single phase Zn2TiO4 spinel from a new ZnTi layered double hydroxide precursor.  

PubMed

A single-source ZnTi-layered double hydroxide precursor was used to prepare single phase Zn2TiO4. This approach involves two steps: the calcination of a ZnTi-layered double hydroxide precursor and selective leaching zinc oxide from the resultant calcined products. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) thermogravimetric and differential thermal analysis (TG-DTA), transmission electron microscope (TEM), surface area measurement and UVvis diffuse reflection spectroscopy. The results indicated that a single phase Zn2TiO4 could be successfully obtained from a ZnTi-layered double hydroxide precursor at a relatively low temperature in short calcination time. The TEM and SEM show that the diameter of Zn2TiO4 particles prepared at 900 degrees C is in the range of 20-100 nm and smaller than that prepared by the solid-state method. UV-Vis diffuse reflection spectroscopy demonstrates that the material has an energy bandgap around 3.7 eV. PMID:24738443

Song, Jianye; Leng, Mingzhe; Xiao, Hongdi; Zhang, Liangji; Qin, Yaowei; Hou, Wanguo; Du, Na; Liu, Jianqiang

2014-06-01

182

Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme  

PubMed Central

The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w) indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 ?g/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril. PMID:22904631

Hussein Al Ali, Samer Hasan; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

2012-01-01

183

Photocatalytic degradation of 2,4-dichlorophenol with MgAlTi mixed oxides catalysts obtained from layered double hydroxides.  

PubMed

MgAl and MgAlTi mixed oxides were obtained from the thermal treatment of LDH materials synthesized by the sol-gel method; these materials were characterized by N2 physisorption, XRD, UV-vis, XPS, EDS-SEM and TEM techniques. According to the results, Ti was incorporated in the LDH layer when content in the material was low. The MgAl and MgAlTi mixed oxides were evaluated in the photo-degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of UV light. A superior efficiency in the photo-degradation of 2,4-DCP, in comparison with the Degussa P-25 TiO2 reference catalyst was observed, reaching a total decomposition of the 2,4-DCP molecule in less than 60 min. According to the results, Ti was incorporated in the LDH layer when the content in the material was low. The MgAl and MgAlTi mixed oxides were evaluated in the photo-degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of UV light. A superior efficiency in the photo-degradation of 2,4-DCP with the MgAl and MgAlTi mixed oxides, in comparison with the Degussa P-25 TiO2 reference catalyst was observed, reaching a total decomposition of the 2,4-DCP molecule in less than 60 min. PMID:24184126

Mendoza-Damián, G; Tzompantzi, F; Mantilla, A; Barrera, A; Lartundo-Rojas, L

2013-12-15

184

Synthesis and characterization of Ni 1? x Zn x Fe 2O 4 spinel ferrites from tailored layered double hydroxide precursors  

Microsoft Academic Search

In this paper, a series of pure Ni1?xZnxFe2O4 (0?x?1) spinel ferrites have been synthesized successfully using a novel route through calcination of tailored hydrotalcite-like layered double hydroxide molecular precursors of the type [(Ni+Zn)1?x?yFey2+Fex3+(OH)2]x+(SO42?)x\\/2·mH2O at 900°C for 2h, in which the molar ratio of (Ni2++Zn2+)\\/(Fe2++Fe3+) was adjusted to the same value as that in single spinel ferrite itself. The physico-chemical characteristics

Feng Li; Xiaofeng Liu; Qiaozhen Yang; Junjie Liu; David G. Evans; Xue Duan

2005-01-01

185

Synthesis and characterization of Ni{sub 1-x}Zn âFeâOâ spinel ferrites from tailored layered double hydroxide precursors  

Microsoft Academic Search

In this paper, a series of pure Ni{sub 1-x}Zn âFeâOâ (0 {<=} x {<=} 1) spinel ferrites have been synthesized successfully using a novel route through calcination of tailored hydrotalcite-like layered double hydroxide molecular precursors of the type [(Ni + Zn){sub 1-x-y}Fe {sub y} {sup 2+}Fe â {sup 3+}(OH)â] {sup x+}(SOâ ²⁻) {sub x\\/2}.mHâO at 900 deg. C for 2

Li Feng; Liu Xiaofeng; Yang Qiaozhen; Liu Junjie; David G. Evans; Duan Xue

2005-01-01

186

Aluminum Hydroxide  

MedlinePLUS

Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

187

Controlled release and angiotensin-converting enzyme inhibition properties of an antihypertensive drug based on a perindopril erbumine-layered double hydroxide nanocomposite  

PubMed Central

Background The intercalation of perindopril erbumine into Zn/Al-NO3-layered double hydroxide resulted in the formation of a host-guest type of material. By virtue of the ion-exchange properties of layered double hydroxide, perindopril erbumine was released in a sustained manner. Therefore, this intercalated material can be used as a controlled-release formulation. Results Perindopril was intercalated into the interlayers and formed a well ordered, layered organic-inorganic nanocomposite. The basal spacing of the products was expanded to 21.7 Å and 19.9 Å by the ion-exchange and coprecipitation methods, respectively, in a bilayer and a monolayer arrangement, respectively. The release of perindopril from the nanocomposite synthesized by the coprecipitation method was slower than that of its counterpart synthesized by the ion-exchange method. The rate of release was governed by pseudo-second order kinetics. An in vitro antihypertensive assay showed that the intercalation process results in effectiveness similar to that of the antihypertensive properties of perindopril. Conclusion Intercalated perindopril showed better thermal stability than its free counterpart. The resulting material showed sustained-release properties and can therefore be used as a controlled-release formulation. PMID:22619549

Al Ali, Samer Hasan Hussein; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

2012-01-01

188

Dissolvable layered double hydroxide coated magnetic nanoparticles for extraction followed by high performance liquid chromatography for the determination of phenolic acids in fruit juices.  

PubMed

A magnesium-aluminum layered double hydroxide coated on magnetic nanoparticles was synthesized and used as a sorbent to extract some phenolic acids including p-hydroxy benzoic acid, caffeic acid, syringic acid, p-coumaric acid and ferulic acid from fruit juices. After extraction, the elution step was performed through dissolving double hydroxide layers containing the analytes by changing the solution pH. The extracted phenolic acids were separated and quantified using high performance liquid chromatography-photodiode array detection. Experimental parameters such as sorbent amount, solution pH, desorption solvent volume and extraction time were studied and optimized. The linearity range of the method was between 2 and 500?gL(-1) with the determination coefficient (r(2)) higher than 0.991. Relative standard deviations for intra- and inter-day precision for the analytes at 100?gL(-1) were in the range of 4.3-9.2% and 4.9-8.6%, respectively. Batch-to-batch reproducibility at 100?gL(-1) concentration level was in the range of 7.8-11% (n=3). The limits of detection were between 0.44 and 1.3?gL(-1). Relative recoveries higher than 81% with RSDs in the range of 4.2-9.7% were obtained in the analysis of fruit juice samples. PMID:25260344

Saraji, Mohammad; Ghani, Milad

2014-10-31

189

DNA-enhanced peroxidase-like activity of layered double hydroxide nanosheets and applications in H2O2 and glucose sensing.  

PubMed

LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields. PMID:24065121

Chen, Lijian; Sun, Kaifang; Li, Peipei; Fan, Xianzhong; Sun, Jianchao; Ai, Shiyun

2013-11-21

190

Magnetic-field-assisted assembly of CoFe layered double hydroxide ultrathin films with enhanced electrochemical behavior and magnetic anisotropy.  

PubMed

Magnetic films based on CoFe LDH nanoplatelets and porphyrin anions were fabricated by the layer-by-layer assembly technique with an assistance of an external magnetic field, which show enhanced electrochemical behavior and magnetic anisotropy. PMID:21283892

Shao, Mingfei; Wei, Min; Evans, David G; Duan, Xue

2011-03-21

191

Characteristics of selective fluoride adsorption by biocarbon-Mg/Al layered double hydroxides composites from protein solutions: kinetics and equilibrium isotherms study.  

PubMed

In the study, two novel applied biocarbon-Mg/Al layered double hydroxides composites (CPLDH and CPLDH-Ca) were successfully prepared and characterized by TEM, ICP-AES, XFS, EDS, FTIR, XRD, BET and pHpzc. The fluoride removal efficiency (RF) and protein recovery ratio (RP) of the adsorbents were studied in protein systems of lysozyme (LSZ) and bovine serum albumin (BSA). The results showed that the CPLDH-Ca presented remarkable performance for selective fluoride removal from protein solution. It reached the maximum RF of 92.1% and 94.8% at the CPLDH-Ca dose of 2.0g/L in LSZ and BSA system, respectively. The RP in both systems of LSZ and BSA were more than 90%. Additionally, the RP of CPLDH-Ca increased with the increase of ionic strengths, and it almost can be 100% with more than 93% RF. Fluoride adsorption by the CPLDH-Ca with different initial fluoride concentrations was found to obey the mixed surface reaction and diffusion controlled adsorption kinetic model, and the overall reaction rate is probably controlled by intra-particle diffusion, boundary layer diffusion and reaction process. The adsorption isotherms of fluoride in BSA system fit the Langmuir-Freundlich model well. The BSA has synergistic effect on fluoride adsorption and the degree increased with the increase of the initial BSA concentration. PMID:24486617

Ma, Wei; Lv, Tengfei; Song, Xiaoyan; Cheng, Zihong; Duan, Shibo; Xin, Gang; Liu, Fujun; Pan, Decong

2014-03-15

192

[Influence of reaction time of urea hydrolysis-based co-precipitation on the structure of ZnAl layered double hydroxides and the phosphate adsorption].  

PubMed

A series of ZnAl layered double hydroxides (LDHs) were prepared by urea hydrolysis-based homogeneous co-precipitation for studying their structure and phosphate adsorption capacities. The results show that all the samples exhibited a typical layered structure as the reaction time extended from 12 h to 96 h, whereas Zn/Al molar ratio in the ZnAls decreased from 2.06 to 0.70 and the specific surface area markedly increased to be 7.6-fold higher than that of ZnAl-12. Phosphate adsorption capacity of the ZnAl was in general increased gradually with the reaction time extension, which can be attributed to the surface area rising as well as the increased positive charge of LDHs layer caused by a higher proportion of Al. This reveals that physicochemical adsorption on LDHs surface would have played an important role during the phosphate adsorption. With a reaction time of 24 h, a high amount of exchangeable interlayer anions was observed, giving rise to a highest phosphate uptake of 34.1 mg x g(-1) by the ZnAl-24. It indicates the ion exchange was another major pathway for the phosphate removal. For all the ZnAls with different reaction times, the phosphate adsorption isotherms fit well with Langmuir-type equations; the adsorption kinetics followed pseudo-second-order models. PMID:23213917

Lu, Ying; Cheng, Xiang; Xing, Bo; Sun, Zhong-en; Sun, De-zhi

2012-08-01

193

Enhancing electrochemical reaction sites in nickel-cobalt layered double hydroxides on zinc tin oxide nanowires: a hybrid material for an asymmetric supercapacitor device.  

PubMed

Conducting nanowires are of particular interest in energy-related research on devices such as supercapacitors, batteries, water splitting electrodes and solar cells. Their direct electrode/current collector contact and highly conductive 1D structure enable conducting nanowires to provide ultrafast charge transportation. In this paper, we report the facile synthesis of nickel cobalt layered double hydroxides (LDHs) on conducting Zn(2)SnO(4) (ZTO) and the application of this material to a supercapacitor. This study also presents the first report of an enhancement of the active faradic reaction sites (electroactive sites) resulting from the heterostructure. This novel material demonstrates outstanding electrochemical performance with a high specific capacitance of 1805 F g(-1) at 0.5 A g(-1), and an excellent rate performance of 1275 F g(-1) can be achieved at 100 A g(-1). Furthermore, an asymmetric supercapacitor was successfully fabricated using active carbon as a negative electrode. This asymmetric device exhibits a high energy density of 23.7 W h kg(-1) at a power density of 284.2 W kg(-1). Meanwhile, a high power density of 5817.2 W kg(-1) can be achieved at an energy density of 9.7 W h kg(-1). More importantly, this device exhibits long-term cycling stability, with 92.7% capacity retention after 5000 cycles. PMID:23076678

Wang, Xu; Sumboja, Afriyanti; Lin, Mengfang; Yan, Jian; Lee, Pooi See

2012-11-21

194

Solvothermal synthesis of NiAl double hydroxide microspheres on a nickel foam-graphene as an electrode material for pseudo-capacitors  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate excellent pseudo-capacitance behavior of nickel-aluminum double hydroxide microspheres (NiAl DHM) synthesized by a facile solvothermal technique using tertbutanol as a structure-directing agent on nickel foam-graphene (NF-G) current collector as compared to use of nickel foam current collector alone. The structure and surface morphology were studied by X-ray diffraction analysis, Raman spectroscopy and scanning and transmission electron microscopies respectively. NF-G current collector was fabricated by chemical vapor deposition followed by an ex situ coating method of NiAl DHM active material which forms a composite electrode. The pseudocapacitive performance of the composite electrode was investigated by cyclic voltammetry, constant charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrode with the NF-G current collector exhibits an enhanced electrochemical performance due to the presence of the conductive graphene layer on the nickel foam and gives a specific capacitance of 1252 F g-1 at a current density of 1 A g-1 and a capacitive retention of about 97% after 1000 charge-discharge cycles. This shows that these composites are promising electrode materials for energy storage devices.

Momodu, Damilola; Bello, Abdulhakeem; Dangbegnon, Julien; Barzeger, Farshad; Taghizadeh, Fatimeh; Fabiane, Mopeli; Johnson, A. T. Charlie; Manyala, Ncholu

2014-09-01

195

Organo-modified layered double hydroxide-catalyzed Fenton-like ultra-weak chemiluminescence for specific sensing of vitamin B?? in egg yolks.  

PubMed

In general, the chemiluminescence (CL) sensing of vitamin B12 is achieved by determining Co(II) liberated from acidified vitamin B12 by a luminol system. However, the luminol system for sensing vitamin B12 has poor selectivity due to serious interference from other metal ions. In this study, as a novel CL amplifier of the Co(II)+H2O2+OH(-) ultra-weak CL reaction (Fenton-like system), dodecylbenzene sulfonate (DBS)-layered double hydroxides (LDHs) have been applied to the specific determination of vitamin B12 by liberating Co(II). The CL intensity increased with increasing the concentration of vitamin B12 in a wide range from 1.0 ng mL(-1) to 5 ?g mL(-1) with a detection limit of 0.57 ng mL(-1) (S/N=3). The proposed method has been successfully applied to determine vitamin B12 in egg yolk with simple procedures, shorter time and higher selectivity. Recoveries from spiked real samples were 96-103%. The results of the proposed method for sensing vitamin B12 in real samples were agreed with those obtained by the standard inductively coupled plasma mass spectrometry (ICP-MS) method. To the best of our knowledge, this is the first report on the CL sensing of vitamin B12 with high selectivity in the absence of luminol. PMID:25127574

Zhang, Lijuan; Rong, Wanqi; Lu, Chao; Zhao, Lixia

2014-11-01

196

Determination of Iodate in Food, Environmental, and Biological Samples after Solid-Phase Extraction with Ni-Al-Zr Ternary Layered Double Hydroxide as a Nanosorbent  

PubMed Central

Nanostructured nickel-aluminum-zirconium ternary layered double hydroxide was successfully applied as a solid-phase extraction sorbent for the separation and pre-concentration of trace levels of iodate in food, environmental and biological samples. An indirect method was used for monitoring of the extracted iodate ions. The method is based on the reaction of the iodate with iodide in acidic solution to produce iodine, which can be spectrophotometrically monitored at 352?nm. The absorbance is directly proportional to the concentration of iodate in the sample. The effect of several parameters such as pH, sample flow rate, amount of nanosorbent, elution conditions, sample volume, and coexisting ions on the recovery was investigated. In the optimum experimental conditions, the limit of detection (3s) and enrichment factor were 0.12??g?mL?1 and 20, respectively. The calibration graph using the preconcentration system was linear in the range of 0.2–2.8??g?mL?1 with a correlation coefficient of 0.998. In order to validate the presented method, a certified reference material, NIST SRM 1549, was also analyzed. PMID:22619590

Abdolmohammad-Zadeh, Hossein; Tavarid, Keyvan; Talleb, Zeynab

2012-01-01

197

Antituberculosis nanodelivery system with controlled-release properties based on para-amino salicylate-zinc aluminum-layered double-hydroxide nanocomposites.  

PubMed

We report the intercalation and characterization of para-amino salicylic acid (PASA) into zinc/aluminum-layered double hydroxides (ZLDHs) by two methods, direct and indirect, to form nanocomposites: PASA nanocomposite prepared by a direct method (PASA-D) and PASA nanocomposite prepared by an indirect method (PASA-I). Powder X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis revealed that the PASA drugs were accommodated within the ZLDH interlayers. The anions of the drug were accommodated as an alternate monolayer (along the long-axis orientation) between ZLDH interlayers. Drug loading was estimated to be 22.8% and 16.6% for PASA-D and PASA-I, respectively. The in vitro release properties of the drug were investigated in physiological simulated phosphate-buffered saline solution of pH 7.4 and 4.8. The release followed the pseudo-second-order model for both nanocomposites. Cell viability (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide [MTT] assays) was assessed against normal human lung fibroblast MRC-5 and 3T3 mouse fibroblast cells at 24, 48, and 72 hours. The results showed that the nanocomposite formulations did not possess any cytotoxicity, at least up to 72 hours. PMID:24255593

Saifullah, Bullo; Hussein, Mohd Zobir; Hussein-Al-Ali, Samer Hasan; Arulselvan, Palanisamy; Fakurazi, Sharida

2013-01-01

198

Homogeneous precipitation of nickel hydroxide powders  

NASA Astrophysics Data System (ADS)

Structure of nickel precipitate from decomposition of urea was found to be alpha-Ni(OH)2. FTIR analysis revealed the intercalation of cyanate (OCN), which is an intermediate product of urea decomposition. This observation implied that the assumption of single step decomposition of urea to carbon dioxide and ammonia was over simplified. Role of critical experimental parameters like initial pH and metal ion concentration on the powder characteristics was carried out. Numerical solutions to reaction pathways predicted significant accumulation of the intermediate cyanate in the time-temperature range investigated. Numerical simulations included the effects of hydrolysis products of Ni2+ and Ni-amine, Ni-cyanate, and Ni-carbonate complexes. Chemical analysis of the precipitate showed a decrease in nitrogen content with increasing reaction times. This was consistent with the predicted decrease in concentration of Ni-cyanate complexes with time. Layer double hydroxides (LDHs) are intercalation compounds represented by the formula [M2+1-xM3+ x(OH)2]x+[An-x/n ]x-·mH2O. alpha-Ni(OH) 2 and Ni-Al layer double hydroxides precipitated by urea were investigated with FTIR and XPS. The role of cyanate in nucleation and growth of precipitates is demonstrated. In the early stages, cyanate ion is found mainly to be grafted into alpha-Ni(OH)2 via nitrogen, whereas later in the growth stages, it is bonded through oxygen. In LDHs cyanate remains N-bonded. Precipitation with substituted ureas, revealed the link between spectral features and structures observed in XRD patterns. With slower decomposition rates and low levels of supersaturation an extensively hydrated structure was observed. From the two phases of Ni(OH)2, alpha-phase, with its larger interlayer spacing, offers enhanced electrochemical properties but it transforms into thermodynamically stable beta-phase. Stabilizing effects of Ni2+ substitution with Co2+ and Al3+ was investigated. A number of three-component LDHs (TCLDHs) with Ni2+1-(x+y) /Co2+x and Al3+y (x and y were varied between 0.00 and, 0.25) were produced by urea precipitation. From the compositions studied, the ones containing [Al3+] o ? 0.015 M resulted with the LDH structure and proved to be stable in the electrolyte for prolonged times. Chronopotentiometry results indicated that TC-LDHs could deliver capacities up to about 30% higher than the beta-phase.

Mavis, Bora

199

Enhancing electrochemical reaction sites in nickel-cobalt layered double hydroxides on zinc tin oxide nanowires: a hybrid material for an asymmetric supercapacitor device  

NASA Astrophysics Data System (ADS)

Conducting nanowires are of particular interest in energy-related research on devices such as supercapacitors, batteries, water splitting electrodes and solar cells. Their direct electrode/current collector contact and highly conductive 1D structure enable conducting nanowires to provide ultrafast charge transportation. In this paper, we report the facile synthesis of nickel cobalt layered double hydroxides (LDHs) on conducting Zn2SnO4 (ZTO) and the application of this material to a supercapacitor. This study also presents the first report of an enhancement of the active faradic reaction sites (electroactive sites) resulting from the heterostructure. This novel material demonstrates outstanding electrochemical performance with a high specific capacitance of 1805 F g-1 at 0.5 A g-1, and an excellent rate performance of 1275 F g-1 can be achieved at 100 A g-1. Furthermore, an asymmetric supercapacitor was successfully fabricated using active carbon as a negative electrode. This asymmetric device exhibits a high energy density of 23.7 W h kg-1 at a power density of 284.2 W kg-1. Meanwhile, a high power density of 5817.2 W kg-1 can be achieved at an energy density of 9.7 W h kg-1. More importantly, this device exhibits long-term cycling stability, with 92.7% capacity retention after 5000 cycles.Conducting nanowires are of particular interest in energy-related research on devices such as supercapacitors, batteries, water splitting electrodes and solar cells. Their direct electrode/current collector contact and highly conductive 1D structure enable conducting nanowires to provide ultrafast charge transportation. In this paper, we report the facile synthesis of nickel cobalt layered double hydroxides (LDHs) on conducting Zn2SnO4 (ZTO) and the application of this material to a supercapacitor. This study also presents the first report of an enhancement of the active faradic reaction sites (electroactive sites) resulting from the heterostructure. This novel material demonstrates outstanding electrochemical performance with a high specific capacitance of 1805 F g-1 at 0.5 A g-1, and an excellent rate performance of 1275 F g-1 can be achieved at 100 A g-1. Furthermore, an asymmetric supercapacitor was successfully fabricated using active carbon as a negative electrode. This asymmetric device exhibits a high energy density of 23.7 W h kg-1 at a power density of 284.2 W kg-1. Meanwhile, a high power density of 5817.2 W kg-1 can be achieved at an energy density of 9.7 W h kg-1. More importantly, this device exhibits long-term cycling stability, with 92.7% capacity retention after 5000 cycles. Electronic supplementary information (ESI) available: SAED pattern of Zn2SnO4 nanowires, EDX analysis of the Ni/Co = 1 : 1 sample, BET tests of activated carbon, electrochemical characterization of activated carbon, CV curves of positive and negative asymmetric supercapacitors, CV curves of different potential windows of an asymmetric supercapacitor, schematic comparison of direct deposition and the heterostructure. See DOI: 10.1039/c2nr31590d

Wang, Xu; Sumboja, Afriyanti; Lin, Mengfang; Yan, Jian; Lee, Pooi See

2012-10-01

200

Synthesis of layered cathode material Li[Co xMn 1-x]O 2 from layered double hydroxides precursors  

NASA Astrophysics Data System (ADS)

Cathode materials Li[Co xMn 1-x]O 2 for lithium secondary batteries have been prepared by a new route—precursor method of layered double hydroxides (LDHs). In situ high-temperature X-ray diffraction (HT-XRD) and thermogravimetric analysis coupled with mass spectrometry (TG-MS) were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH·H 2O: firstly the layered structure of LDHs transformed to an intermediate phase with spinel structure; then the distortion of the structure occurred with the intercalation of Li + into the lattice, resulting in the formation of layered Li[Co xMn 1-x]O 2 with ?-NaFeO 2 structure. Extended X-ray absorption fine structure (EXAFS) data showed that the Co-O bonding length and the coordination number of Co were close to those of Mn in Li[Co xMn 1-x]O 2, which indicates that the local environments of the transitional metals are rather similar. X-ray photoelectron spectroscopy (XPS) was used to measure the oxidation state of Co and Mn. The influences of Co/Mn ratio on both the structure and electrochemical property of Li[Co xMn 1-x]O 2 have been investigated by XRD and electrochemical tests. It has been found that the products synthesized by the precursor method demonstrated a rather stable cycling behavior, with a reversible capacity of 122.5 mAh g -1 for the layered material Li[Co 0.80Mn 0.20]O 2.

Lu, Yanluo; Wei, Min; Yang, Lan; Li, Congju

2007-05-01

201

Automated Dispersive Solid-Phase Extraction Using Dissolvable Fe3O4-Layered Double Hydroxide Core-Shell Microspheres as Sorbent.  

PubMed

Automation of dispersive solid-phase extraction (d-SPE) presents significant challenges. Separation of the sorbent from the spent sample cannot be conducted without manual operations, including centrifugation, a widely used means of isolating a solid material from solution. In this work, we report an approach to d-SPE using dissolvable magnetic Fe3O4-layered double hydroxide core-shell microspheres as sorbent to enable automation of the integrative extraction and analytical processes. Through magnetic force, the sorbent, after extraction, was isolated from the sample and then dissolved by acid to release the analytes. Thus the customary analyte elution step in conventional SPE was unnecessary. The automated d-SPE step was coupled to high-performance liquid chromatography (HPLC) with photodiode array detection for determination of several pharmaceuticals and personal care products (PPCPs) [acetylsalicylic acid (ASA), 2,5-dihydroxybenzoic acid (DBA), 2-phenylphenol (PP), and fenoprofen (FP)] in aqueous samples. For the automated d-SPE process, experimental parameters such as agitation speed, temperature, time, and pH were optimized. The results showed that this method provided low limits of detection (between 0.021 and 0.042 ?g/L), good linearity (r(2) ? 0.9956), and good repeatability of extractions (relative standard deviations ?4.1%, n = 6). The optimized procedure was then applied to determination of PPCPs in a sewage sample and ASA and FP in drug preparations. This fully automated extraction-HPLC approach was demonstrated to be an efficient procedure for extraction and analysis of ASA, DBA, PP, and FP in these samples. PMID:25320871

Tang, Sheng; Chia, Guo Hui; Chang, Yuepeng; Lee, Hian Kee

2014-11-18

202

Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH.  

PubMed

Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs. PMID:25380526

Hussein, Mohd Zobir; Jaafar, Adila Mohamad; Yahaya, Asmah Hj; Masarudin, Mas Jaffri; Zainal, Zulkarnain

2014-01-01

203

Small-molecule inhibitors of human LDH5  

PubMed Central

The latest findings on the role played by human LDH5 (hLDH5) in the promotion of glycolysis in invasive tumor cells indicates that this enzyme subtype is a promising therapeutic target for invasive cancer. Compounds able to selectively inhibit hLDH5 hold promise for the cure of neoplastic diseases. hLDH5 has so far been a rather unexplored target, since its importance in the promotion of cancer progression has been neglected for decades. This enzyme should also be considered as a challenging target due the high polar character (mostly cationic) of its ligand cavity. Recently, significant progresses have been reached with small-molecule inhibitors of hLDH5 displaying remarkable potencies and selectivities. This review provides an overview of the newly developed hLDH5 inhibitors. The roles of hLDH isoforms will be briefly discussed, and then the inhibitors will be grouped into chemical classes. Furthermore, general pharmacophore features will be emphasized throughout the structural subgroups analyzed. PMID:24175747

Granchi, Carlotta; Paterni, Ilaria; Rani, Reshma; Minutolo, Filippo

2014-01-01

204

The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4-Dichlorophenoxyacetate Intercalated into the Zn-Al-layered Double Hydroxide Nanohybrid  

NASA Astrophysics Data System (ADS)

Intercalation of beneficial anion into inorganic host has lead to an opportunity to synthesize various combinations of new organic-inorganic nanohybrids with various potential applications; especially, for the controlled release formulation and storage purposes. Investigation on the release behavior of 2,4-dichlorophenoxyacetate (2,4-D) intercalated into the interlayer of Zn-Al-layered double hydroxide (ZAN) have been carried out using single, binary and ternary aqueous systems of chloride, carbonate and phosphate. The release behavior of the active agent 2,4-D from its double-layered hydroxide nanohybrid ZANDI was found to be of controlled manner governed by pseudo-second order kinetics. It was found that carbonate medium yielded the highest accumulated release of 2,4-D, while phosphate in combination with carbonate and/or nitrate speeds up the release rate of 2,4-D. These results indicate that it is possible to design and develop new delivery system of latex stimulant compound with controlled release property based on 2,4-D that is known as a substance to increase latex production of rubber tree, Hevea brasiliensis.

Hussein, Mohd Zobir; Jaafar, Adila Mohamad; Yahaya, Asmah Hj.; Zainal, Zulkarnain

2009-11-01

205

Utilization of LDH isoenzymes in the diagnosis of myocardial infarction.  

PubMed

With the arrival of managed care, increased pressure is being placed on the health-care system to reduce the use of laboratory services. When evaluating less expensive methods to measure CK-MB to help reduce costs of triaging patients suspected of having myocardial infarction (MI), we also had an opportunity to evaluate the ordering pattern of LDH isoenzymes for these same patients. We found that LDH isoenzymes were continuously ordered as a routine test at least 14% of the time. We worked with the Division of Cardiology to reduce the use of LDH isoenzymes in two ways: 1) by changing the protocol of triaging suspected MI patients and 2) by reporting the test result only after director approval. This article summarizes our approach to reducing the use of LDH isoenzymes, an expensive test in terms of reagent cost and technician time. PMID:10172984

Petersen, J R; Smith, E; Okorodudu, A O; Valbuena, G; Bissell, M G

1997-01-01

206

Pediococcus acidilactici ldhD gene: cloning, nucleotide sequence, and transcriptional analysis.  

PubMed Central

The gene encoding D-lactate dehydrogenase was isolated on a 2.9-kb insert from a library of Pediococcus acidilactici DNA by complementation for growth under anaerobiosis of an Escherichia coli lactate dehydrogenase and pyruvate-formate lyase double mutant. The nucleotide sequence of ldhD encodes a protein of 331 amino acids (predicted molecular mass of 37,210 Da) which shows similarity to the family of D-2-hydroxyacid dehydrogenases. The enzyme encoded by the cloned fragment is equally active on pyruvate and hydroxypyruvate, indicating that the enzyme has both D-lactate and D-glycerate dehydrogenase activities. Three other open reading frames were found in the 2.9-kb insert, one of which (rpsB) is highly similar to bacterial genes coding for ribosomal protein S2. Northern (RNA) blotting analyses indicated the presence of a 2-kb dicistronic transcript of ldhD (a metabolic gene) and rpsB (a putative ribosomal protein gene) together with a 1-kb monocistronic rpsB mRNA. These transcripts are abundant in the early phase of exponential growth but steadily fade away to disappear in the stationary phase. Primer extension analysis identified two distinct promoters driving either cotranscription of ldhD and rpsB or transcription of rpsB alone. PMID:7539419

Garmyn, D; Ferain, T; Bernard, N; Hols, P; Delplace, B; Delcour, J

1995-01-01

207

REPORT ON QUALITATIVE VALIDATION EXPERIMENTS USING LITHIUM-ALUMINUM LAYERED DOUBLE-HYDROXIDES FOR THE REDUCTION OF ALUMINUM FROM THE WASTE TREATMENT PLANT FEEDSTOCK  

SciTech Connect

A process for removing aluminum from tank waste simulants by adding lithium and precipitating Li-Al-dihydroxide (Lithiumhydrotalcite, [LiAl{sub 2}(OH){sub 6}]{sup +}X{sup -}) has been verified. The tests involved a double-shell tank (DST) simulant and a single-shell tank (SST) simulant. In the case of the DST simulant, the product was the anticipated Li-hydrotalcite. For the SST simulant, the product formed was primarily Li-phosphate. However, adding excess Li to the solution did result in the formation of traces of Li-hydrotalcite. The Li-hydrotalcite from the DST supernate was an easily filterable solid. After four water washes the filter cake was a fluffy white material made of < 100 {micro}m particles made of smaller spheres. These spheres are agglomerates of {approx} 5 {micro}m diameter platelets with < 1 {micro}m thickness. Chemical and mineralogical analyses of the filtrate, filter cake, and wash waters indicate a removal of 90+ wt% of the dissolved Al for the DST simulant. For the SST simulant, the main competing reaction to the formation of lithium hydrotalcite appears to be the formation of lithium phosphate. In case of the DST simulant, phosphorus co-precipitated with the hydrotalcite. This would imply the added benefit of the removal of phosphorus along with aluminum in the pre-treatment part of the waste treatment and immobilization plant (WTP). For this endeavor to be successful, a serious effort toward process parameter optimization is necessary. Among the major issues to be addressed are the dependency of the reaction yield on the solution chemistry, as well as residence times, temperatures, and an understanding of particle growth.

HUBER HJ; DUNCAN JB; COOKE GA

2010-05-11

208

Evolutionary relationships of lactate dehydrogenases (LDHs) from mammals, birds, an amphibian, fish, barley, and bacteria: LDH cDNA sequences from Xenopus, pig, and rat.  

PubMed Central

The nucleotide sequences of the cDNAs encoding LDH (EC 1.1.1.27) subunits LDH-A (muscle), LDH-B (liver), and LDH-C (oocyte) from Xenopus laevis, LDH-A (muscle) and LDH-B (heart) from pig, and LDH-B (heart) and LDH-C (testis) from rat were determined. These seven newly deduced amino acid sequences and 22 other published LDH sequences, and three unpublished fish LDH-A sequences kindly provided by G. N. Somero and D. A. Powers, were used to construct the most parsimonious phylogenetic tree of these 32 LDH subunits from mammals, birds, an amphibian, fish, barley, and bacteria. There have been at least six LDH gene duplications among the vertebrates. The Xenopus LDH-A, LDH-B, and LDH-C subunits are most closely related to each other and then are more closely related to vertebrate LDH-B than LDH-A. Three fish LDH-As, as well as a single LDH of lamprey, also seem to be more related to vertebrate LDH-B than to land vertebrate LDH-A. The mammalian LDH-C (testis) subunit appears to have diverged very early, prior to the divergence of vertebrate LDH-A and LDH-B subunits, as reported previously. Images PMID:7937776

Tsuji, S; Qureshi, M A; Hou, E W; Fitch, W M; Li, S S

1994-01-01

209

LDH-C4: a target with therapeutic potential for cancer and contraception.  

PubMed

The lactate dehydrogenase (LDH) has been studied widely because it exists in various isozymic forms. The association of A and B subunits of LDH can generate five tetrameric isozymes, but the finding of the sixth isozyme in mature human testis and sperm indicated the presence of an additional subunit of LDH, designated as LDH-X (also termed LDH-C4 due to tetrameric nature of C-subunit). LDH-C4 isozyme is an iso-, allo-, and auto-antigen present in mammalian sperm cells. The synthesis of LDH-C4 in the testis takes place during sexual maturation, and it is the predominant fraction in mature spermatozoa. Though, originally considered to be testis specific, LDH-C or Ldh3 in mice was later detected in the murine oocyte and early embryo. Ldh3 in mouse supports its role in energy production in spermatids that favor lactate as substrate and in spermatozoa with a characteristic aerobic glycolytic path to yield ATP. During last two decades, cancer/testis-associated genes (CTAs) which are expressed only in the germinal epithelium of the testis are also expressed in some cancer cells, but not in non-cancerous somatic tissues. The CTAs are considered promising candidates for diagnosis and immunotherapy of cancer. The sperm-specific Ldh-c gene has been shown to express in a broad spectrum of human tumors, with high frequency in lung cancer, melanoma, and breast cancer; the protein being expressed virtually in all tumor types tested. Accordingly, LDH-C4 is the unique target for contraception in both males and females and offers potential future for immunotherapy of different types of cancers. As LDH-C has a preference for lactate as a substrate, LDH-C activation in cancer may depend on lactate for ATP production. The major aim of this article is to review the salient features of LDH-C subunit and the immune responses of LDH-C4 in homologous and heterologous species in relation to its role in acceptance or rejection of the allograft and its application in contraception and immunotherapy of cancer, directly or indirectly through the regulation of its substrate, the lactate. PMID:22893065

Gupta, G S

2012-12-01

210

Electrochemical performance of cobalt hydroxide nanosheets formed by the delamination of layered cobalt hydroxide in water.  

PubMed

We report the preparation of monometallic Co(2+)/Co(3+) layered double hydroxide, intercalated with lactate anions (LCoH-Lactate), and its spontaneous delamination in water to form cobalt hydroxide nanosheets. These hydroxide nanosheets formed stable aqueous dispersions. The thickness of a nanosheet was estimated to be approximately 1 nm by atomic force microscopy and small angle X-ray scattering experiments, and corresponds to a single hydroxide layer. Some of the Co(2+) cations were oxidised by oxygen, resulting in a mixed Co(2+)(0.76)Co(3+)(0.24) layer composition. Upon water evaporation, the nanosheets restacked to form transparent self-standing films with a layered structure like that of the original material. The coverage of the surface with side-by-side stacks of nanosheets indicated two-dimensional agglomeration and suggested that these dispersions could be applied to prepare large monolayers of nanosheets. The layers prepared by spin-coating were stable and featured reversible and reproducible redox properties in an alkaline electrolyte. In an evaluation of their electrochemical performance, the cobalt hydroxide nanosheets exhibited durability and fast charge transfer kinetics during repetitive potential cycling up to 200 mV s(-1). The nanosheets prepared by the present method show promise for use in nanocomposite materials for energy storage applications. PMID:24647991

Schneiderová, B; Demel, J; Pleštil, J; Tarábková, H; Bohuslav, J; Lang, K

2014-07-21

211

Histamine and lactate dehydrogenase (LDH) release in ischemic myocardium of the guinea-pig  

Microsoft Academic Search

Histamine has been proved to be released during myocardial infarction and ischemic arrhythmias in dogs. The aim of the present experiments was to evaluate if ischemia and reperfusion modify histamine and lactate dehydrogenase (LDH) release in isolated guinea-pig heart. The results obtained show a steady increase of LDH release both in the ischemic and reperfusion phases. The release of histamine

E. Masini; E. Giannella; S. Bianchi; P. F. Mannaioni

1987-01-01

212

Relationships between LDH-A, Lactate and Metastases in 4T1 Breast Tumors  

PubMed Central

Purpose To investigate the relationship between LDH-A expression, lactate concentration, cell metabolism and metastases in murine 4T1 breast tumors. Experimental Design Inhibition of LDH-A expression and protein levels were achieved in a metastatic breast cancer cell line (4T1) using shRNA technology. The relationship between tumor LDH-A protein levels and lactate concentration (measured by magnetic resonance spectroscopic imaging-MRSI) and metastases was assessed. Results LDH-A knockdown cells (KD9) showed a significant reduction in LDH-A protein and LDH activity, less acid production, decreased transwell migration and invasion, lower proliferation, reduced glucose utilization and glycolysis and increase in oxygen consumption, ROS and cellular ATP levels, compared to control (NC) cells cultured in 25 mM glucose. In vivo studies showed lower lactate levels in KD9, KD5, KD317 tumors than in NC or 4T1 wild-type tumors (p<0.01), and a linear relationship between tumor LDH-A protein expression and lactate concentration. Metastases were delayed and primary tumor growth rate decreased. Conclusions We show for the first time that LDH-A knockdown inhibited the formation of metastases, and was accompanied by in vivo changes in tumor cell metabolism. Lactate MRSI can be used as a surrogate to monitor targeted inhibition of LDH-A in a pre-clinical setting and provides a non-invasive imaging strategy to monitor LDH-A targeted therapy. This imaging strategy can be translated to the clinic to identify and monitor patients who are at high risk of developing metastatic disease. PMID:23833310

Rizwan, Asif; Serganova, Inna; Khanin, Raya; Karabeber, Hazem; Ni, Xiaohui; Thakur, Sunitha; Zakian, Kristen L.; Blasberg, Ronald; Koutcher, Jason A.

2013-01-01

213

Molecular Structure of Hydroxide ion  

NSDL National Science Digital Library

In 1923, Johannes Bronsted and Thomas Lowry proposed that a Bronsted-Lowry base is any substance that can accept a proton. They found that hydroxide anion acts as a proton acceptor. When high concentrations of hydroxide are present in solution, the solution is said to be basic, having a pH above 7. It falls into the Bronstead-Lowry definition of a base because it acts as a proton acceptor. Hydroxide, when combined with other elements, serves many purposes. Aluminum hydroxide is a safe antacid used to treat indigestion, gastric and duodenal ulcers, and efflux oesophagitis.

2002-09-11

214

LDH Concentration in Nasal-Wash Fluid as a Biochemical Predictor of Bronchiolitis Severity  

PubMed Central

Objective Because the decision to hospitalize an infant with bronchiolitis is often supported by subjective criteria and objective indicators of bronchiolitis severity are lacking, we tested the hypothesis that lactate dehydrogenase (LDH), which is released from injured cells, is a useful biochemical indicator of bronchiolitis severity. Patients and Methods We retrospectively analyzed a study of children <24 months old presenting to the emergency department with bronchiolitis. Demographic, clinical information, nasal-wash (NW) and serum specimens were obtained. NW samples were analyzed for respiratory viruses, caspase 3/7 activity and a panel of cytokines and chemokines. Total LDH activity was tested in NW samples and sera. Results Of 101 enrolled children (median age, 5.6 months), 98 had NW specimens available. A viral etiology was found in 82 patients (83.6%), with respiratory syncytial virus (RSV) (66%) and rhinovirus (19%) being the most common viruses detected. Concentrations of LDH in NW specimens were independent from those in sera, and were higher in children with RSV infection or with dual infection. Significant correlations were found between NW LDH and NW cytokines/chemokines. Similarly, NW LDH correlated with NW-caspase 3/7 activity (r=0.75; P<.001). In a multivariate analysis, NW LDH concentration in the upper quartile was significantly associated with a reduced risk of hospitalization (odds ratio: 0.19; 95% confidence interval: 0.05–0.68; P=0.011). Conclusions NW LDH levels in young children with bronchiolitis varied according to viral etiology and disease severity. Values in the upper quartile were associated with ~80% risk reduction in hospitalization, likely reflecting a robust antiviral response. NW LDH may be a useful biomarker to assist the clinician in the decision to hospitalize a child with bronchiolitis. PMID:20100751

Laham, Federico R.; Trott, Amanda A.; Bennett, Berkeley L.; Kozinetz, Claudia A.; Jewell, Alan M.; Garofalo, Roberto P.; Piedra, Pedro A.

2011-01-01

215

21 CFR 582.1428 - Magnesium hydroxide.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

2013-04-01

216

21 CFR 582.1428 - Magnesium hydroxide.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

2011-04-01

217

21 CFR 582.1428 - Magnesium hydroxide.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

2010-04-01

218

21 CFR 582.1428 - Magnesium hydroxide.  

... 2014-04-01 2014-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

2014-04-01

219

21 CFR 582.1428 - Magnesium hydroxide.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 2012-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

2012-04-01

220

PCR-RFLPs within the lactate dehydrogenase (LDH-A) gene of the domestic pigeon (Columba livia var. domestica).  

PubMed

A total of 45 racing pigeons were genotyped using PCR-RFLP method. PCR product of the LDH-A gene was amplified according to the Long-PCR procedure. The amplification products were digested with restriction enzymes. PCR-RFLPs for two restriction enzymes, HaeIII and NlaIV, were observed. Two pairs of alleles LDH-A(A) and LDH-A(B) for LDH-A-NlaIV polymorphism and LDH-A(C) and LDH-A(D) for LDH-A-HaeIII polymorphism were detected in the homozygous and heterozygous states. Frequencies of alleles were as follows: A - 0.622, B - 0.378 and C - 0.256, D - 0.744. PMID:12441634

Dybus, Andrzej; Kmie?, Marek

2002-01-01

221

Physical and Functional Association of Lactate Dehydrogenase (LDH) with Skeletal Muscle Mitochondria*  

PubMed Central

The intracellular lactate shuttle hypothesis posits that lactate generated in the cytosol is oxidized by mitochondrial lactate dehydrogenase (LDH) of the same cell. To examine whether skeletal muscle mitochondria oxidize lactate, mitochondrial respiratory oxygen flux (JO2) was measured during the sequential addition of various substrates and cofactors onto permeabilized rat gastrocnemius muscle fibers, as well as isolated mitochondrial subpopulations. Addition of lactate did not alter JO2. However, subsequent addition of NAD+ significantly increased JO2, and was abolished by the inhibitor of mitochondrial pyruvate transport, ?-cyano-4-hydroxycinnamate. In experiments with isolated subsarcolemmal and intermyofibrillar mitochondrial subpopulations, only subsarcolemmal exhibited NAD+-dependent lactate oxidation. To further investigate the details of the physical association of LDH with mitochondria in muscle, immunofluorescence/confocal microscopy and immunoblotting approaches were used. LDH clearly colocalized with mitochondria in intact, as well as permeabilized fibers. LDH is likely localized inside the outer mitochondrial membrane, but not in the mitochondrial matrix. Collectively, these results suggest that extra-matrix LDH is strategically positioned within skeletal muscle fibers to functionally interact with mitochondria. PMID:23873936

Elustondo, Pia A.; White, Adrienne E.; Hughes, Meghan E.; Brebner, Karen; Pavlov, Evgeny; Kane, Daniel A.

2013-01-01

222

New TiO2/MgAl-LDH nanocomposites for the photocatalytic degradation of dyes.  

PubMed

In this study we report the synthesis of a series of composite nanostructures comprising LDH and TiO2 phases. The materials characterization showed that the LDH crystallites are encapsulated inside the TiO2 matrix after the anatase seeds are deposited on MgxAl-LDHs. The structure in which LDH phase is embedded into anatase matrix is unique bringing important advantages to the photocatalytic performances of the nanocomposites. The photocatalytic activity of the prepared nanocomposites was tested on the degradation of the methylene blue (MB) in aqueous solution. The photocatalytic activities of the nanocomposites were compared with commercial TiO2 nanoparticles Degussa P25. The nanocomposites exhibited superior photocatalytic activity in basic environment because the negatively charged surface of TiO2 nanoparticles at high pH attracts the positively charged methylene blue species. PMID:21121320

Seftel, E M; Popovici, E; Beyers, E; Mertens, M; Zhu, H Y; Vansant, E F; Cool, P

2010-12-01

223

Hypoxia and cobalt stimulate lactate dehydrogenase (LDH) activity in vascular smooth muscle cells  

Microsoft Academic Search

O2 plays a dominant role in the metabolism and viability of cells; changes in O2 supply lead to many physiological responses in the cell. Recent reports have shown that hypoxia induces the transcription of a number of genes, among them those for the glycolytic enzymes. We have investigated signalling events that may lead to enhanced activity of lactate dehydrogenase (LDH)

Hugo H. Marti; Hans H. Jung; Josef Pfeilschifter; Christian Bauer

1994-01-01

224

Particle-induced artifacts in the MTT and LDH viability assays  

PubMed Central

In vitro testing is a common first step in assessing combustion generated and engineered nanoparticle related health hazards. Commercially available viability assays are frequently used to compare the toxicity of different particle types and to generate dose response data. Nanoparticles, well known for having large surface areas and chemically active surfaces, may interfere with viability assays, producing a false assessment of toxicity and making it difficult to compare toxicity data. The objective of this study is to measure the extent of particle interference in two common viability assays, the MTT reduction and the lactate dehydrogenase (LDH) release assays. Diesel particles, activated carbon, flame soot, oxidized flame soot, and titanium dioxide particles are assessed for interactions with the MTT and LDH assay under cell-free conditions. Diesel particles, at concentrations as low as 0.05 ?g/ml, reduce MTT. Other particle types reduce MTT only at a concentration of 50 ?g/ml and higher. The activated carbon, soot, and oxidized soot particles bind LDH to varying extents, reducing the concentration measured in the LDH assay. The interfering effects of the particles explain in part the different toxicities measured in human bronchial epithelial cells (16HBE14o). We conclude that valid particle toxicity assessments can only be assured after first performing controls to verify that the particles under investigation do not interfere with a specific assay at the expected concentrations. PMID:22799765

Holder, Amara L.; Goth-Goldstein, Regine; Lucas, Donald; Koshland, Catherine P.

2012-01-01

225

High-Throughput Screening to Identify Plant Derived Human LDH-A Inhibitors  

PubMed Central

Aims Lactate dehydrogenase (LDH)-A is highly expressed in diverse human malignant tumors, parallel to aggressive metastatic disease, resistance to radiation/chemotherapy and clinically poor outcome. Although this enzyme constitutes a plausible target in treatment of advanced cancer, there are few known LDH-A inhibitors. Study Design In this work, we utilized a high-throughput enzyme micro-array format to screen and evaluate > 900 commonly used medicinal plant extracts (0.00001-.5 mg/ml) for capacity to inhibit activity of recombinant full length human LDHA; EC .1.1.1.27. Methodology The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis- MALDI-TOF-MS/MS, enzyme activity was validated by oxidation of NADH (500?M) and kinetic inhibition established in the presence of a known inhibitor (Oxalic Acid). Results Of the natural extracts tested, the lowest IC50s [<0.001 mg/ml] were obtained by: Chinese Gallnut (Melaphis chinensis gallnut), Bladderwrack (Fucus vesiculosus), Kelp (Laminaria Japonica) and Babul (Acacia Arabica). Forty-six additional herbs contained significant LDH-A inhibitory properties with IC50s [<0.07 mg/ml], some of which have common names of Arjun, Pipsissewa, Cinnamon, Pink Rose Buds/Petals, Wintergreen, Cat’s Claw, Witch Hazel Root and Rhodiola Root. Conclusion These findings reflect relative potency by rank of commonly used herbs and plants that contain human LDH-A inhibitory properties. Future research will be required to isolate chemical constituents within these plants responsible for LDH-A inhibition and investigate potential therapeutic application. PMID:24478981

Deiab, S.; Mazzio, E.; Messeha, S.; Mack, N.; Soliman, K. F. A.

2014-01-01

226

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2012 CFR

...hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2012-04-01

227

21 CFR 184.1763 - Sodium hydroxide.  

...hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2014-04-01

228

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2010 CFR

...hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2010-04-01

229

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2011 CFR

...hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2011-04-01

230

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2013 CFR

...hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2013-04-01

231

Potassium hydroxide for shale stability  

Microsoft Academic Search

Use of potassium hydroxide (KOH) in lime mud treated with modified starch deflocculant provides excellent shale stability in either weighted or unweighted muds. The added benefits are achieved with little difference in mud cost per barrel when compared to conventional lime muds. Also, the muds have reduced hole enlargement, cuttings dispersion and mud costs in comparison to lignosulfonate and KCl\\/

T. O. Walker; H. L. Dearing; J. P. Simpson

1983-01-01

232

The phase composition of carbonized aluminum hydroxide  

Microsoft Academic Search

1.In the carbonization of aluminate solutions under conditions of pH 10–11.5 and 25–40°C, amorphous aluminum hydroxide precipitates.2.The gelatinous precipitates, which are products of aging of the amorphous aluminum hydroxide during the process of washing, are not any definite crystalline modification of aluminum hydroxide, but occupy an intermediate position between the amorphous and crystalline states. The molecules of aluminum hydroxide form

Ya. R. Katsobashvili; N. S. Kurkova; M. M. Getsiu

1969-01-01

233

Contribution to the knowledge of nickel hydroxide electrodes. 5. Analysis and electrochemical behavior of cadmium nickel hydroxides  

NASA Technical Reports Server (NTRS)

Electrochemical experiments performed at sintered and bulk electrodes show that beta nickel hydroxide contains an electrochemically inactive proportion of cadmium hydroxide of up to 10%. The electrochemically ineffective cadmium hydroxide is homogeneously dissolved in beta nickel hydroxide.

Bode, H.; Dennstedt, W.

1981-01-01

234

Organically pillared layered zinc hydroxides  

Microsoft Academic Search

The two organically pillared layered zinc hydroxides [Zn2(OH)2(ndc)], CPO-6, and [Zn3(OH)4(bpdc)], CPO-7, were obtained in hydrothermal reactions between 2,6-naphthalenedicarboxylic acid (ndc) and zinc nitrate (CPO-6) and 4,4?biphenyldicarboxylate (bpdc) and zinc nitrate (CPO-7), respectively. In CPO-6, the tetrahedral zinc atoms are connected by two ?2-OH groups and two carboxylate oxygen atoms, forming infinite layers extending parallel to the bc-plane. These layers

Kjell Ove Kongshaug; Helmer Fjellvåg

2004-01-01

235

Alteration of hydrogen metabolism of ldh- deleted Enterobacter aerogenes by overexpression of NAD(+)-dependent formate dehydrogenase  

Microsoft Academic Search

The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate\\u000a in the ldh-deleted mutant. The knockout of NADH-consuming

Yuan Lu; Hongxin Zhao; Chong Zhang; Qiheng Lai; Xi Wu; Xin-Hui Xing

2010-01-01

236

Local Diffusion Homogeneity (LDH): An Inter-Voxel Diffusion MRI Metric for Assessing Inter-Subject White Matter Variability  

PubMed Central

Many diffusion parameters and indices (e.g., fractional anisotropy [FA] and mean diffusivity [MD]) have been derived from diffusion magnetic resonance imaging (MRI) data. These parameters have been extensively applied as imaging markers for localizing white matter (WM) changes under various conditions (e.g., development, degeneration and disease). However, the vast majority of the existing parameters is derived from intra-voxel analyses and represents the diffusion properties solely within the voxel unit. Other types of parameters that characterize inter-voxel relationships have been largely overlooked. In the present study, we propose a novel inter-voxel metric referred to as the local diffusion homogeneity (LDH). This metric quantifies the local coherence of water molecule diffusion in a model-free manner. It can serve as an additional marker for evaluating the WM microstructural properties of the brain. To assess the distinguishing features between LDH and FA/MD, the metrics were systematically compared across space and subjects. As an example, both the LDH and FA/MD metrics were applied to measure age-related WM changes. The results indicate that LDH reveals unique inter-subject variability in specific WM regions (e.g., cerebral peduncle, internal capsule and splenium). Furthermore, there are regions in which measurements of age-related WM alterations with the LDH and FA/MD metrics yield discrepant results. These findings suggest that LDH and FA/MD have different sensitivities to specific WM microstructural properties. Taken together, the present study shows that LDH is complementary to the conventional diffusion-MRI markers and may provide additional insights into inter-subject WM variability. Further studies, however, are needed to uncover the neuronal mechanisms underlying the LDH. PMID:23776665

Gong, Gaolang

2013-01-01

237

Cetuximab reverses the Warburg effect by inhibiting HIF-1-regulated LDH-A  

PubMed Central

Hypoxia-inducible factor-1 (HIF-1) plays a critical role in reprogramming cancer metabolism towards aerobic glycolysis (i.e., the Warburg effect), which is critical to supplying cancer cells with the biomass needed for proliferation. Previous studies have shown that cetuximab, an epidermal growth factor receptor-blocking monoclonal antibody, downregulates the alpha subunit of HIF-1 (HIF-1?) through the inhibition of epidermal growth factor receptor downstream cell signaling and that downregulation of HIF-1? is required for cetuximab-induced antiproliferative effects. However, the mechanism underlying these actions has yet to be identified. In this study, we used the Seahorse XF96 extracellular flux analyzer to assess the effect of cetuximab treatment on changes in glycolysis and mitochondrial respiration, the two major energy-producing pathways, in live cells. We found that cetuximab downregulated lactate dehydrogenase A (LDH-A) and inhibited glycolysis in cetuximab-sensitive head and neck squamous cell carcinoma (HNSCC) cells in a HIF-1? downregulation–dependent manner. HNSCC cells with acquired cetuximab resistance expressed a high level of HIF-1? and were highly glycolytic. Overexpression of a HIF-1? mutant (HIF-1?/?ODD) conferred resistance to cetuximab-induced G1-phase cell cycle arrest, which could be overcome by knockdown of LDH-A expression. Inhibition of LDH-A activity with oxamate enhanced the response of cetuximab-resistant cells to cetuximab. Cetuximab had no noticeable inhibitory effect on glycolysis in nontransformed cells. These findings provide novel mechanistic insights into cetuximab-induced cell cycle arrest from the perspective of cancer metabolism and suggest novel strategies for enhancing cetuximab response. PMID:23920275

Lu, Haiquan; Li, Xinqun; Luo, Zhongguang; Liu, Jie; Fan, Zhen

2013-01-01

238

Cetuximab reverses the Warburg effect by inhibiting HIF-1-regulated LDH-A.  

PubMed

Hypoxia-inducible factor-1 (HIF-1) plays a critical role in reprogramming cancer metabolism toward aerobic glycolysis (i.e., the Warburg effect), which is critical to supplying cancer cells with the biomass needed for proliferation. Previous studies have shown that cetuximab, an EGF receptor-blocking monoclonal antibody, downregulates the alpha subunit of HIF-1 (HIF-1?) through the inhibition of EGF receptor downstream cell signaling and that downregulation of HIF-1? is required for cetuximab-induced antiproliferative effects. However, the mechanism underlying these actions has yet to be identified. In this study, we used the Seahorse XF96 extracellular flux analyzer to assess the effect of cetuximab treatment on changes in glycolysis and mitochondrial respiration, the two major energy-producing pathways, in live cells. We found that cetuximab downregulated lactate dehydrogenase A (LDH-A) and inhibited glycolysis in cetuximab-sensitive head and neck squamous cell carcinoma (HNSCC) cells in an HIF-1? downregulation-dependent manner. HNSCC cells with acquired cetuximab resistance expressed a high level of HIF-1? and were highly glycolytic. Overexpression of a HIF-1? mutant (HIF-1?/?ODD) conferred resistance to cetuximab-induced G1 phase cell-cycle arrest, which could be overcome by knockdown of LDH-A expression. Inhibition of LDH-A activity with oxamate enhanced the response of cetuximab-resistant cells to cetuximab. Cetuximab had no noticeable inhibitory effect on glycolysis in nontransformed cells. These findings provide novel mechanistic insights into cetuximab-induced cell-cycle arrest from the perspective of cancer metabolism and suggest novel strategies for enhancing cetuximab response. PMID:23920275

Lu, Haiquan; Li, Xinqun; Luo, Zhongguang; Liu, Jie; Fan, Zhen

2013-10-01

239

Aluminum chlorohydrate III: Conversion to aluminum hydroxide.  

PubMed

Bayerite, an aluminum hydroxide polymorph, readily forms when the hydroxyl to aluminum ratio of aluminum chlorohydrate is raised to 3 by titration with sodium hydroxide. Dilution of aluminum chlorhydrate solutions with water leads to the formation of gibbsite, another aluminum hydroxide polymorph. The mechanism of conversion in each instance is related to the structure of the Al13O4(OH)24(H2O)7+(12) complex. PMID:7264935

Teagarden, D L; White, J L; Hem, S L

1981-07-01

240

ENZYMOLOGIE SRIQUE DE LA CHVRE : VALEURS USUELLES DE CPK, LDH, ICDH et SDH1  

E-print Network

level of milk production, the authors determined the enzymic activities of CPK, LDH, ICDH and SDH.1.1.42). libérée de façon très précoce par les cellules lors d'affections aiguës du foie. - Sorbitol deshydrogénase dans la production laitière de haut niveau (élevage A: 800 kg/an; élevage B: 820 kg/an). �levés en

Paris-Sud XI, Université de

241

Removal of phosphate by aluminum oxide hydroxide.  

PubMed

The development and manufacture of an adsorbent to remove phosphate ion for the prevention of eutrophication in lakes are very important. The characteristics of phosphate adsorption onto aluminum oxide hydroxide were investigated to estimate the adsorption isotherms, the rate of adsorption, and the selectivity of adsorption. Phosphate was easily adsorbed onto aluminum oxide hydroxide, because of the hydroxyl groups. The adsorption of phosphate onto aluminum oxide hydroxide was influenced by pH in solution: the amount adsorbed was greatest at pH 4, ranging with pH from 2 to 9. The optimum pH for phosphate removal by aluminum oxide hydroxide is 4. The selectivity of phosphate adsorption onto aluminum oxide hydroxide was evaluated based on the amount of phosphate ion adsorbed onto aluminum oxide hydroxide from several anion complex solutions. It is phosphate that aluminum oxide hydroxide can selectively adsorb. The selectivity of phosphate onto aluminum oxide hydroxide was about 7000 times that of chloride. This result indicated that the hydroxyl groups on aluminum oxide hydroxide have selective adsorptivity for phosphate and could be used for the removal of phosphate from seawater. PMID:16256465

Tanada, Seiki; Kabayama, Mineaki; Kawasaki, Naohito; Sakiyama, Toru; Nakamura, Takeo; Araki, Mamiko; Tamura, Takamichi

2003-01-01

242

Effects of gossypol acetic acid on the activity of LDH-C4 from human and rabbit spermatozoa.  

PubMed

This report focuses on the effect of gossypol acetic acid on LDH-C4 from human and rabbit spermatozoa. Human semen was obtained by masturbation after 3-5 days of abstinence. Semen from successfully vasectomized healthy men was used for studies on the LDH isoenzymes other than LDH-C4 in seminal plasma. Rabbit semen was collected by an artificial vagina. Human samples containing less than 100 million spermatozoa/ml were pooled to obtain a sufficient number of spermatozoa. Rabbit samples were not pooled. LDH activity was analyzed spectrophotometrically. Gossypol acetic acid was obtained from the Special Program of Research on Human Reproduction, World Health Organization, Switzerland through their collaboration with the National Institute of Health in the US and was dissolved in ethanol. Freshly prepared solutions were used for each experiment and 20 mcl added to the cuvette. LDH-C4 from human spermatozoa was inhibited by GAA in a dose dependent manner, with 50% inhibition noted between 50-75 mcm. LDH-C4 from rabbit spermatozoa was slightly less sensitive to GAA as 50% inhibition was observed at concentrations between 75-100 mcm. The interindividual differences in sensitivity to GAA was small in human samples but in the experiment with rabbit semen the interindividual and the intraindividual differences were great. The total LDH activity in seminal plasma from both human (normal and vasectomized men) and rabbit was insensitive to GAA but a minor inhibition was sometimes noted at 100 mcm. It has been proposed that inhibition of LDH-C4 in the testis and/or in ejaculated spermatozoa could provide a possible explanation for the antifertility effect of gossypol. Gossypol has been reported to be much less effective as a male contraceptive in the rabbit than in man. In this study gossypol was slightly less active as an inhibitor of sperm LDH-C4 from rabbits than from humans. This could indicate that an effect by gossypol on sperm LDH-C4 activity is not a major mode of action for its antifertility action. The mode of action of gossypol is most likely complex, involving a number of essential enzyme systems. PMID:6840877

Eliasson, R; Virji, N

1983-02-01

243

Lactate dehydrogenase-5 (LDH-5) overexpression in non-small-cell lung cancer tissues is linked to tumour hypoxia, angiogenic factor production and poor prognosis.  

PubMed

Lactate dehydrogenase-5 (LDH-5) catalyses the reversible transformation of pyruvate to lactate, having a principal position in the anaerobic cellular metabolism. Induction of LDH-5 occurs during hypoxia and LDH-5 transcription is directly regulated by the hypoxia-inducible factor 1 (HIF1). Serum LDH levels have been correlated with poor prognosis and resistance to chemotherapy and radiotherapy in various neoplastic diseases. The expression, however, of LDH in tumours has never been investigated in the past. In the present study, we established an immunohistochemical method to evaluate the LDH-5 overexpression in tumours, using two novel antibodies raised against the rat muscle LDH-5 and the human LDH-5 (Abcam, UK). The subcellular patterns of expression in cancer cells were mixed nuclear and cytoplasmic. In direct contrast to cancer cells, stromal fibroblasts were reactive for LDH-5 only in a minority of cases. Serum LDH, although positively correlated with, does not reliably reflect the intratumoral LDH-5 status. Lactate dehydrogenase-5 overexpression was directly related to HIF1alpha and 2alpha, but not with the carbonic anhydrase 9 expression. Patients with tumours bearing high LDH-5 expression had a poor prognosis. Tumours with simultaneous LDH-5 and HIF1alpha (or HIF2alpha) overexpression, indicative of a functional HIF pathway, had a particularly aggressive behaviour. It is concluded that overexpression of LDH-5 is a common event in non-small-cell lung cancer, can be easily assessed in paraffin-embedded material and provides important prognostic information, particularly when combined with other endogenous markers of hypoxia and acidity. PMID:12942121

Koukourakis, M I; Giatromanolaki, A; Sivridis, E; Bougioukas, G; Didilis, V; Gatter, K C; Harris, A L

2003-09-01

244

Precipitation of reactive aluminium hydroxide from an acidic aluminium sulphate solution by addition of sodium hydroxide  

Microsoft Academic Search

The goal of the present thesis was to study the possibilities of producing an aluminium hydroxide, which would easily dissolve in hydrochloric ac id. Furthermore, the product should be easy to dewater. In the experiments, which were made batch-wise, a 50% sodium hydroxide was used to accomplish the precipitation. The precipitation of aluminium hydroxide is a dynamic process that depends

Emilia Andersson; Henrik Hansson

245

40 CFR 721.10504 - Surface modified magnesium hydroxide (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Surface modified magnesium hydroxide (generic). 721.10504...Substances § 721.10504 Surface modified magnesium hydroxide (generic). (a) Chemical...identified generically as surface modified magnesium hydroxide (PMN P-06-682) is...

2013-07-01

246

21 CFR 73.2326 - Chromium hydroxide green.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 ...CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity...specifications. The color additive chromium hydroxide green shall...

2010-04-01

247

21 CFR 73.1326 - Chromium hydroxide green.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section...CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally...

2010-04-01

248

21 CFR 184.1205 - Calcium hydroxide.  

Code of Federal Regulations, 2010 CFR

...hydroxide. (a) Calcium hydroxide (Ca(OH)2 , CAS Reg. No. 1305-62-0) is also known as slaked lime or calcium hydrate. It is produced by the hydration of lime. (b) The ingredient meets the specifications of the Food Chemicals...

2010-04-01

249

METAL VALUE RECOVERY FROM METAL HYDROXIDE SLUDGES  

EPA Science Inventory

A two-year study investigating the potential for metal value recovery from metal hydroxide sludges has been completed. The objectives of the study were to: Develop a flowsheet to separate and recover metal values from metal finishing hydroxide sludge materials and operate on a la...

250

Layered double hydroxides as nanoreactors for prebiotic chemistry  

NASA Astrophysics Data System (ADS)

The conversion of simple organic molecules to macromolecules, possessing functional activities is one of the key hurdles limiting our understanding on how life began on Earth in the Hadean period. Here, we aim to report new data showing the potential of anionic lamellar compounds to concentrate, protect, and catalyze the condensation reactions of aminoacids to form oligopeptides.

Grégoire, B.; Carteret, C.; Erastova, V.; Greenwell, H. C.; Fraser, D.

2013-09-01

251

Pretreatment of rapeseed straw by sodium hydroxide.  

PubMed

Pretreatment method for rapeseed straw by sodium hydroxide was investigated for production of bioethanol and biobutanol. Various pretreatment parameters, including temperature, time, and sodium hydroxide concentration were optimized using a statistical method which is a central composite design of response surface methodology. In the case of sodium hydroxide pretreatment, optimal pretreatment conditions were found to be 7.9% sodium hydroxide concentration, 5.5 h of reaction time, and 68.4 °C of reaction temperature. The maximum glucose yield which can be recovered by enzymatic hydrolysis at the optimum conditions was 95.7% and the experimental result was 94.0 ± 4.8%. This experimental result was in agreement with the model prediction. An increase of surface area and pore size in pretreated rapeseed straw by sodium hydroxide pretreatment was observed by scanning electron microscope. PMID:22086290

Kang, Kyeong Eop; Jeong, Gwi-Taek; Park, Don-Hee

2012-06-01

252

Enhanced removal of triphosphate by MgCaFe-Cl-LDH: synergism of precipitation with intercalation and surface uptake.  

PubMed

Triphosphate (TPP) is an important form of phosphate pollutants while its removal investigation has been just started now. This research examined the removal of triphosphate using Mg(2-x)Ca(x)FeCl-LDH (x = 0-2) as absorbents. We found that the removal of triphosphate over Mg(2)FeCl-LDH mainly underwent the surface adsorption and the near-edge intercalation, with the practical removal amount (9-11 mg(P)/g) corresponding to 10-15% of the theoretical one. In contrast, Ca(2)FeCl-LDH removed a higher amount of triphosphate (56.4 mg(P)/g). The comprehensive analysis of the triphosphate-uptake products with XRD/XPS/FTIR reveals that Ca(2)FeCl-LDH dissolves first and then released Ca(2+) ions react with triphosphate (TPP) to form insoluble Ca-TPP precipitate. Combination of these two different removal mechanisms enables Mg(0.5)Ca(1.5)FeCl-LDH to take up 84.2mg(P)/g from aqueous solution under similar conditions. PMID:21429664

Zhou, Jizhi; Xu, Zhi Ping; Qiao, Shizhang; Liu, Qiang; Xu, Yunfeng; Qian, Guangren

2011-05-15

253

Seasonal Changes in Serum Testosterone, LDH Concentration and Semen Characteristics in Markhoz Goats.  

PubMed

This experiment was conducted to study variations of serum testosterone and seminal characteristics of Markhoz male goats. Blood samples were obtained via jugular vein, and semen was collected by using an artificial vagina from 14 fertile male goats (2-3 years of age), at 15-day intervals starting on 15 July and ending on 30 October 2010 (during breeding and non-breeding season). Semen volume, total sperm (volume×concentration), live sperm (%), abnormal sperm (%) and semen pH were significantly superior during the late summer and early autumn (breeding season). Variation of sperm density, motility and progressive motility was not significant during the sampling period. The results presented show that the lowest and highest levels of lactate dehydrogenase in the seminal plasma were recorded in late October (2.82 U/ml) and in late August (4.81 U/ml), respectively. Moreover, the study indicated that the serum testosterone concentration was higher during late summer and early autumn (p<0.05) than at any other of sampling period. There were negative correlations between volume and sperm density (-0.135, p<0.05), and positive correlations between volume and percentage live sperm (0.224) and percentage progressive motility (0.194, p<0.01). Sperm density was correlated with live sperm (0.200, p<0.05) and progressive motility (0.202, p<0.01). The correlation between live sperm and progressive motility was 0.554 (p<0.01). Furthermore, the results in this study indicated a significant positive correlation between live sperm and LDH (0.450) and a negative correlation between sperm density and LDH concentration (-0.272) (p<0.01). Significant, but positive correlations were found between sperm motility and LDH (0.542) and testosterone concentration (0.522), respectively (p<0.05). In conclusion, this study demonstrated that the best obtained semen was collected in late summer (during decreasing photoperiod) and early autumn (September and October). This also coincides with the natural breeding season of Markhoz goats in Iran. PMID:25049550

Farshad, A; Yousefi, A; Moghaddam, A; Khalili, B

2012-02-01

254

Seasonal Changes in Serum Testosterone, LDH Concentration and Semen Characteristics in Markhoz Goats  

PubMed Central

This experiment was conducted to study variations of serum testosterone and seminal characteristics of Markhoz male goats. Blood samples were obtained via jugular vein, and semen was collected by using an artificial vagina from 14 fertile male goats (2–3 years of age), at 15-day intervals starting on 15 July and ending on 30 October 2010 (during breeding and non-breeding season). Semen volume, total sperm (volume×concentration), live sperm (%), abnormal sperm (%) and semen pH were significantly superior during the late summer and early autumn (breeding season). Variation of sperm density, motility and progressive motility was not significant during the sampling period. The results presented show that the lowest and highest levels of lactate dehydrogenase in the seminal plasma were recorded in late October (2.82 U/ml) and in late August (4.81 U/ml), respectively. Moreover, the study indicated that the serum testosterone concentration was higher during late summer and early autumn (p<0.05) than at any other of sampling period. There were negative correlations between volume and sperm density (?0.135, p<0.05), and positive correlations between volume and percentage live sperm (0.224) and percentage progressive motility (0.194, p<0.01). Sperm density was correlated with live sperm (0.200, p<0.05) and progressive motility (0.202, p<0.01). The correlation between live sperm and progressive motility was 0.554 (p<0.01). Furthermore, the results in this study indicated a significant positive correlation between live sperm and LDH (0.450) and a negative correlation between sperm density and LDH concentration (?0.272) (p<0.01). Significant, but positive correlations were found between sperm motility and LDH (0.542) and testosterone concentration (0.522), respectively (p<0.05). In conclusion, this study demonstrated that the best obtained semen was collected in late summer (during decreasing photoperiod) and early autumn (September and October). This also coincides with the natural breeding season of Markhoz goats in Iran. PMID:25049550

Farshad, A.; Yousefi, A.; Moghaddam, A.; Khalili, B.

2012-01-01

255

Thermodynamics of Volatile Silicon Hydroxides Studied  

NASA Technical Reports Server (NTRS)

Silicon-based ceramics are promising candidate structural materials for heat engines. The long-term stability of these materials to environmental degradation is dependent on the formation and retention of a protective SiO2 layer. It is well known that SiO2 forms stable volatile hydroxides in the presence of water vapor at elevated temperatures. Combustion conditions, which characteristically are at high velocities, contain significant water vapor pressures, and high temperatures tend to promote continuous formation of these hydroxides with resulting material degradation. For the degradation of silicon-based ceramics to be predicted, accurate thermodynamic data on the formation of silicon hydroxides are needed.

Copland, Evan H.; Opila, Elizabeth J.; Jacobson, Nathan S.

2001-01-01

256

[Geographical variation of allele frequencies at the LDH-A* locus in the arctic grayling Thymallus arcticus Pall. and in the European grayling Thymallus arcticus L].  

PubMed

The allele frequencies of LDH-A* locus were studied in the population of Siberian grayling from the Kozhym River (Pechora basin) and in the population of European grayling from Pechora, Mezen', and Vym' rivers (Northern Dvina basin). In samples of both species (n = 134), three LDH-A phenotypes have been identified in total, which proved to be under the control of two alleles: LDH-A*100 and LDH-A*50. The alternative alleles of LDH-A* locus were identified in the populations of Siberian grayling from Kozhym River and in the population of European grayling from the same river and other Pechora tributaries, namely, LDH-A*100 and LDH-A*50 in the Siberian and the European grayling, respectively. However, in the European grayling populations from the Mezen' and Vym' rivers, both alleles occur at the frequencies of the rare LDH-A*100 allele of 0.143 and 0.222, respectively. According to the published data, the frequency of LDH-A*100 allele increases in the European grayling populations of northwestern (Finland) and southern (France) rivers, reaching 0.872 and 1.000 in Rhone and Loire, respectively, i.e., the values characteristic of the Siberian grayling populations. PMID:15575515

Shubin, P N; Efimtseva, é A; shubin, Iu P; Chelpanova, T I

2004-10-01

257

Dangerous Doubles (Doubling Numbers)  

NSDL National Science Digital Library

This lesson teaches students to use the strategy doubling numbers and doubles plus or minus one in order to use mental math to add one digit numbers. The students are engaged in learning through the read aloud of Double the Ducks by Stephen Murphy and then get to work with a partner to draw doubles and write equations that relate to their drawings. Students individually work on solving word problems using these strategies and manipulatives as necessary to solve.

Sharrer, Stephanie

2012-07-14

258

Potassium hydroxide for shale stability  

SciTech Connect

Use of potassium hydroxide (KOH) in lime mud treated with modified starch deflocculant provides excellent shale stability in either weighted or unweighted muds. The added benefits are achieved with little difference in mud cost per barrel when compared to conventional lime muds. Also, the muds have reduced hole enlargement, cuttings dispersion and mud costs in comparison to lignosulfonate and KCl/ polymer muds. No problems with gelation have occurred in any of the wells drilled to date, and muds have remained stable at bottomhole temperatures to 300/sup 0/F. Lignosulfonate dispersants are not recommended and have not been required in any of the wells drilled with this system. Commonly available treating agents, except for the modified starch deflocculant, are used for routine system maintenance. The unique interaction of lime and potassium in these systems is partially responsible for their ability to control wellbore instability caused by shale hydration. Elimination of strong dispersants also has aided in combating hole erosion. Keys to successful use of the KLM system have been proper planning of the mud program, preparation of the rig, careful rig-site monitoring and maintenance of mud composition and properties. Rig-site pilot testing was done to prepare for changing drilling conditions. Overall, it has been found that lime muds treated with KOH and modified starch deflocculant combine many features considered desirable in today's complex drilling environments, and the combination of old and new technology has proven to be a cost-effective alternative to other popular mud systems.

Walker, T.O.; Dearing, H.L.; Simpson, J.P.

1983-11-01

259

21 CFR 184.1428 - Magnesium hydroxide.  

...crystalline mineral brucite. It is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble magnesium salt or by hydration of reactive grades of magnesium oxide. (b) The ingredient meets the...

2014-04-01

260

21 CFR 184.1631 - Potassium hydroxide.  

Code of Federal Regulations, 2011 CFR

...several forms, including pellets, flakes, sticks, lumps, and powders. Potassium hydroxide is obtained commercially from the electrolysis of potassium chloride solution in the presence of a porous diaphragm. (b) The ingredient meets the...

2011-04-01

261

21 CFR 184.1631 - Potassium hydroxide.  

Code of Federal Regulations, 2010 CFR

...several forms, including pellets, flakes, sticks, lumps, and powders. Potassium hydroxide is obtained commercially from the electrolysis of potassium chloride solution in the presence of a porous diaphragm. (b) The ingredient meets the...

2010-04-01

262

Conversion of aluminum chlorohydrate to aluminum hydroxide  

Microsoft Academic Search

aluminum hydroxide. X-ray, IR, and 27A1 NMR spectroscopic data indicate that aluminum chlorohydrate is composed of a central aluminum in tetrahedral configuration surrounded by 12 aluminums each in octahedral configuration. This highly .charged complex is neutralized by 7 chloride counterions. In contrast, aluminum hydroxide has a polymer-like structure whose basic unit is a ring of six aluminums in octahedral configuration

DIRK L. TEAGARDEN; STANLEY L. HEM

263

POSTNATAL EFFECTS OF HEXACHLOROBENZENE (HCB) ON CARDIAC LACTIC DEHYDROGENASE (LDH) AND CREATINE KINASE (CK) ISOZYMES IN CD-1 MICE  

EPA Science Inventory

Pregnant CD-1 mice were treated with hexachlorobenzene (HCB) by gavage at doses of 0, 1, 10 and 50 mg HCB/kg body weight on days 6-17 of gestation and studied on day 1 or 21 postpartum (pp). Hearts of the dams and pups were assayed for lactic dehydrogenase (LDH) and creatine kina...

264

Geographical Variation of Allele Frequencies at the LDH-A* Locus in the Arctic Grayling Thymallus arcticus Pall. and in the European Grayling Thymallus thymallus L  

Microsoft Academic Search

The allele frequencies of LDH-A* locus were studied in the populations of Siberian grayling from the Kozhym River (Pechora basin) and in the population of European grayling from Pechora, Mezen', and Vym' rivers (Northern Dvina basin). In samples of both species (n = 134), three LDH-A phenotypes have been identified in total, which proved to be under the control of

P. N. Shubin; E. A. Efimtzeva; Yu. P. Shubin; T. I. Chelpanova

2004-01-01

265

The synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors  

SciTech Connect

Two aluminum oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been characterized by thermal analysis and powder X-ray diffraction. A solid state reaction model for the formation of [beta][double prime]-Al[sub 2]O[sub 3] is proposed.

Zyl, A. van; Thackeray, M.M.; Duncan, G.K.; Kingon, A.I. (Div. of Materials Science and Technology, Pretoria (South Africa)); Heckroodt, R.O. (Univ. of Cape Town, Rondebosch (South Africa))

1993-02-01

266

The synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors  

Microsoft Academic Search

Two aluminum oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been characterized by thermal analysis and powder X-ray diffraction. A solid state reaction model for the formation of [beta][double prime]-Al[sub 2]O[sub 3] is proposed.

A. van Zyl; M. M. Thackeray; G. K. Duncan; A. I. Kingon; R. O. Heckroodt

1993-01-01

267

Aluminum hydroxide dissolution in synthetic sludges  

SciTech Connect

In the revised Stage 1 Defense Waste Processing Facility, aluminum hydroxide dissolving has been moved from S Canyon to the waste tank farm. The maximum attainable temperature has been reduced from 107/sup 0/C in the stainless steel dissolver to less than 90/sup 0/C in the large mild steel waste tanks. Also, caustic strength must be maintained below 6.5 molar to avoid caustic cracking. Studies at TNX indicate that 75% of the crystalline aluminum hydroxide can be dissolved while using about one-third of the caustic quantity specified for the S Canyon dissolver. Studies were made in laboratory-scale and large-scale equipment to determine optimum conditions for dissolving the most aluminum hydroxide with the least caustic. These studies showed that gibbsite Al(OH)/sub 3/ is readily dissolved at low caustic strength, low addition rate, and at easily attainable in-tank temperatures. On the other hand, most of the boehmite AlOOH can be dissolved, but a lengthy digestion period is required at maximum temperatures and caustic strengths. Fortunately, 72% of the total aluminum hydroxide in the waste sludge is gibbsite and 28% is boehmite according to recent sludge analyses. Recommendations are made for the in-tank conditions needed to dissolve 75% of the aluminum hydroxide contacted. With low boehmite sludges, mild dissolving conditions are adequate while providing good caustic economy. With higher boehmite sludges, the harsher conditions within existing constraints are recommended.

Weber, E.J.

1982-03-01

268

Electrosurface Properties of Hydr(oxides) and Oxide Nanostructures in 1 : 1 Electrolyte Solutions: 2. Electrokinetic Characteristics of Boehmite, Goethite, and Silicon Dioxide  

Microsoft Academic Search

The electrophoretic mobility of particles of silicon dioxide, aluminum hydroxide, and iron hydroxide was measured as a function of pH in NaCl and KCl background solutions. Isoelectric points for the investigated objects were determined. Electrokinetic potentials were calculated with allowances for the particle shape and the polarization of the electrical double layer within the framework of the Overbeek–Boes–Wiersema model.

A. V. Klebanov; N. F. Bogdanova; L. E. Ermakova; M. P. Sidorova

2001-01-01

269

Synthesis of polypropylene/Mg3AlX (X CO3 ) LDH nanocomposites using a solvent mixing  

E-print Network

Synthesis of polypropylene/Mg3Al­X (X ¼ CO3 2� , NO3 � , Cl� , SO4 2� ) LDH nanocomposites using, polypropylene (PP) nanocomposites with four different inorganic anion (CO3 2� , NO3 � , Cl� , and SO4 2� with the ller size larger than 100 nm.8­10 Polypropylene (PP) is one of the most widely used commodity

Guo, John Zhanhu

270

Molecular and functional characterization of the promoter region of the mouse LDH/C gene: enhancer-assisted, Sp1-mediated transcriptional activation.  

PubMed

Molecular and functional studies of the LDH/C 5' upstream promoter elements were undertaken to elucidate the molecular mechanisms involved in temporal activation of LDH/C gene expression in differentiating germ cells. Ligation mediated-PCR (LM-PCR) gene walking techniques were exploited to isolate a 2.1 kb fragment of the mouse LDH/C 5' promoter region. DNA sequence analysis of this isolated genomic fragment indicated that the mouse LDH/C promoter contained TATA and CCAT boxes as well as a GC-box (Sp1-binding site) situated upstream from the transcription start site. PCR-based in vivo DNase I footprinting analysis of a 600 bp fragment of the proximal LDH/C promoter region (-524/+38) in isolated mouse pachytene spermatocytes identified a single footprint over the GC-box motif. Three DNase I hypersensitive sites were also detectable in vivo, in a region containing (CT)n(GA)n repeats upstream from the CCAT box domain. Functional characterization of the promoter region was carried out in a rat C6 glioma cell line and an SV40 transformed germ cell line (GC-1 spg) using wild-type and mutated LDH/C promoter CAT reporter constructs. These studies provide experimental evidence suggesting that transcriptional activation of the LDH/C promoter is regulated by enhancer-mediated coactivation of the Sp1 proteins bound to the GC-box motif footprinted in vivo in pachytene spermatocytes. PMID:9153323

Yang, J; Thomas, K

1997-06-01

271

Recycling Lithium Carbonate/Lithium Hydroxide Waste  

NASA Technical Reports Server (NTRS)

Hazardous waste disposal problem eliminated by regeneration. Li2CO3/ LiOH recycling process relies on low solubility of alkali carbonates in corresponding hydroxides. Li2CO3 precipitate calcined to LI2O, then rehydrated LiOH. Regeneration eliminates need to dispose caustic waste and uses less energy than simple calcination of entire waste mass.

Flowers, J.; Flowers, J.

1983-01-01

272

Hydroxide ion hydration in aqueous solutions.  

PubMed

Hydroxide ion hydration was studied in aqueous solutions of selected alkali metal hydroxides by means of Fourier transform infrared (FTIR) spectroscopy of HDO isotopically diluted in H2O. The quantitative difference spectra procedure was applied for the first time to investigate such systems. It allowed removal of bulk water contribution and separation of the spectra of solute-affected HDO. The obtained spectral data were confronted with ab initio calculated structures of small gas-phase and polarizable continuum solvation model (PCM) solvated aqueous clusters, OH-(H2O)n, n = 1-7, to establish the structural and energetic states of hydration spheres of the hydrated hydroxide anion. This was achieved by comparison of the calculated optimal geometries with the interatomic distances derived from HDO band positions. The energetic state of water in OH- hydration shells, as revealed by solute-affected HDO spectra, is similar to that of an isoelectronic F- anion. No evidence was found for the existence of stable hydroxide dimer, H3O2-, in an aqueous solution. Spectral data do confirm, however, existence of a weak interaction with a single water molecule at the hydrogen site of OH-. PMID:17388572

Smiechowski, Maciej; Stangret, Janusz

2007-04-19

273

Structural transformation of nickel hydroxide films during anodic oxidation  

SciTech Connect

The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

Crocker, R.W.; Muller, R.H.

1992-05-01

274

Study of nickel hydroxide electrodes. 2: Oxidation products of nickel (2) hydroxides  

NASA Technical Reports Server (NTRS)

Pure phases of some oxidized Ni oxides were prepared galvanimetrically with the Ni(2) hydroxide electrode of an alkaline battery. The crystallographic data of these phases, their chemical behavior, and conditions of transition were studied.

Bode, H.; Demelt, K.; White, J.

1986-01-01

275

Mechanisms of antimicrobial activity of calcium hydroxide: a critical review  

Microsoft Academic Search

Siqueira Jr JF, Lopes HP. Mechanisms of antimicrobial activity of calcium hydroxide: a critical review (Review). Interna- tional Endodontic Journal, 32, 361-369, 1999. Literature review The primary function of calcium hydroxide as a routine intracanal medicament is to provide antimicrobial activity. However, the mechanisms of antimicrobial activity of calcium hydroxide are not well known. Physicochemical properties of this substance may

J. F. Siqueira Jr; H. P. Lopes

1999-01-01

276

A layered polymorph of rare earth hydroxides.  

PubMed

A layered polymorph series of rare earth hydroxides has been developed by the conversion of RE2(OH)5Cl·mH2O to RE(OH)3·nH2O (RE = rare earths) with a typical layered structure with interlayer water molecules. A temperature-induced phase transition from the layered polymorph to its hexagonal form is completed at approximately 300 °C. PMID:23722997

Lee, Byung-Ii; Jeong, Heejin; Bae, Jung-soo; Byeon, Song-Ho

2013-07-11

277

Aluminum hydroxide dissolution in synthetic sludges  

Microsoft Academic Search

In the revised Stage 1 Defense Waste Processing Facility, aluminum hydroxide dissolving has been moved from S Canyon to the waste tank farm. The maximum attainable temperature has been reduced from 107°C in the stainless steel dissolver to less than 90°C in the large mild steel waste tanks. Also, caustic strength must be maintained below 6.5 molar to avoid caustic

1982-01-01

278

Particle size and shape of calcium hydroxide  

PubMed Central

The aim of this study was to examine the particle length, width, perimeter, and aspect ratio of calcium hydroxide powder using a flow particle image analyzer (FPIA). Five sample groups each with 10mg calcium hydroxide were mixed with 15mL of alcohol and sonicated. Digital images of the particle samples were taken using the FPIA and analyzed with a one-way ANOVA. The overall averages±S.D. among the five groups for particle length (?m), width (?m), perimeter (?m), and aspect ratio were 2.255±1.994, 1.620±1.464, 6.699±5.598, and 0.737±0.149, respectively. No statistical significance was observed among the groups for all parameters. When the total of 46,818 particles from all five groups were classified into the five length categories of 0.5?m increments, there were significant differences in width, perimeter, and aspect ratio (all p-values<0.0001). In conclusion, calcium hydroxide particles have a size and shape that may allow direct penetration into open dentin tubules. PMID:19166791

Komabayashi, Takashi; D'souza, Rena N; Dechow, Paul C; Safavi, Kamran E.; Spangberg, Larz S.W.

2009-01-01

279

Electrical double layer catalyzed wet-etching of silicon dioxide.  

PubMed

We show that carbon nanotubes (CNTs) accelerate the wet etching of silicon dioxide in a strong alkaline solution. This catalytic effect is due to the spontaneous adsorption of hydroxide on the surface of the CNTs. Such adsorption creates an electrical double layer around the CNTs within which the concentration of hydroxide is higher than the bulk value. Our result suggests that the electrical double layer can be used to pattern nanoscale features. Fabrication of SiO(2) trenches with approximately 60 nm lateral resolution is demonstrated. PMID:19489550

Liu, Haitao; Steigerwald, Michael L; Nuckolls, Colin

2009-12-01

280

Antimicrobial Activity of Calcium Hydroxide in Endodontics: A Review  

PubMed Central

The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. Calcium hydroxide has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also a valuable anti-endotoxin agent. However, its effect on microbial biofilms is controversial. PMID:23323217

Shalavi, S; Yazdizadeh, M

2012-01-01

281

Mullite and alumina composites preparation from cordierite and aluminium hydroxide  

SciTech Connect

Densification and phase transformation of mullite and alumina composites prepared from cordierite and aluminium hydroxide mixture were investigated. X-ray diffraction revealed the presence of mullite since the early stage of aluminium hydroxide addition to the cordierite. Above 40 wt.% of aluminium hydroxide addition, the presence of spinel and mullite phases can be detected by X-ray diffraction and confirmed by X-ray photoelectron spectroscopy. The X-ray photoelectron spectroscopy analysis showed that the amounts of spinel as well as mullite present increased with increasing aluminium hydroxide concentration at the expense of cordierite. These analyses were completed by density measurements and scanning electron microscopy observation.

Aklouche, N. [Constantine Ceramics Laboratory, Mentouri University, 25000 Constantine (Algeria)], E-mail: n.aklouche@yahoo.fr; Achour, S. [Constantine Ceramics Laboratory, Mentouri University, 25000 Constantine (Algeria); Tabet, N. [Surface Science Laboratory, Physics Department, KFUPM, 31261 Dhahran (Saudi Arabia)

2008-05-06

282

The alpha-form of the hydroxides of bivalent metals  

NASA Technical Reports Server (NTRS)

X-ray analyses were made of the hydroxides of the bivalent metals. The freshly pptd. hydroxide is usually in the alpha-form, which on standing is converted to another form or other forms. The alpha and c grating dimensions of the alpha-form and the C6-type of Co, Zn, C, Co-Zn and Ni-Zn hydroxides are tabulated. Ni hydroxide does not exhibit an alpha-form. The alpha-Co(OH)2, the blue form, is stabilized by sugar or by the higher alcohols: these compounds do not stabilize alpha-Zn(OH)2.

Feitknecht, W.

1984-01-01

283

The role of SO42- surface distribution in arsenic removal by iron oxy-hydroxides  

NASA Astrophysics Data System (ADS)

This study investigates the contribution of chemisorbed SO42- in improving arsenic removal properties of iron oxy-hydroxides through an ion-exchange mechanism. An analytical methodology was developed for the accurate quantification of sulfate ion (SO42-) distribution onto the surface and structural compartments of iron oxy-hydroxides synthesized by FeSO4 precipitation. The procedure is based on the sequential determination of SO42- presence in the diffuse and Stern layers, and the structure of these materials as defined by the sulfate-rich environments during the reaction and the variation in acidity (pH 3-12). Physically sorbed SO42-, extracted in distilled water, and physically/chemically adsorbed ions on the oxy-hydroxide's surface leached by a 5 mM NaOH solution, were determined using ion chromatography. Total sulfate content was gravimetrically measured by precipitation as BaSO4. To validate the suggested method, results were verified by X-ray photoelectron and Fourier-transformed infrared spectroscopy. Results showed that low precipitation pH-values favor the incorporation of sulfate ions into the structure and the inner double layer, while under alkaline conditions ions shift to the diffuse layer.

Tresintsi, S.; Simeonidis, K.; Pliatsikas, N.; Vourlias, G.; Patsalas, P.; Mitrakas, M.

2014-05-01

284

Exposing local adaptation: synergistic stressors elicit population-specific lactate dehydrogenase-B ( ldh - b ) expression profiles in Australian barramundi, Lates calcarifer  

Microsoft Academic Search

The molecular response of fish to independently and\\/or concurrently applied ecological stressors (e.g. thermal and\\/or aerobic\\u000a stress) can be quantified at the level of transcript abundance (i.e. gene expression). In temperate fish, the expression of\\u000a the metabolic candidate gene lactate dehydrogenase-B (ldh-b) responds to both aerobic swimming challenge and extended acclimation to various ecologically relevant temperatures. We examined\\u000a hepatic ldh-b

Richard C. Edmunds; Carolyn Smith-Keune; Lynne van Herwerden; Christopher J. Fulton; Dean R. Jerry

285

40 CFR 721.10573 - Magnesium hydroxide surface treated with substituted alkoxysilanes (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Magnesium hydroxide surface treated with substituted...Chemical Substances § 721.10573 Magnesium hydroxide surface treated with substituted...chemical substance identified generically as magnesium hydroxide surface treated with...

2013-07-01

286

ACUTE TOXICITY OF TRIPHENYLTIN HYDROXIDE TO THREE CLADOCERAN SPECIES  

EPA Science Inventory

The toxicity of an organotin pesticide, triphenyltin hydroxide, was assessed with several freshwater cladoceran species, Daphnia pulex, Daphnia magna, and Ceriodaphnia dubia were exposed for 48 h to triphenyltin hydroxide in static acute toxicity tests. Values of the 48-h trimmed...

287

Electron microscope investigations on the morphology of aluminium hydroxides  

Microsoft Academic Search

Summary  The results are given of an investigation by means of the electron microscope and electron diffraction of the morphology of\\u000a amorphous aluminium hydroxide and boehmite.\\u000a \\u000a The ageing process of amorphous aluminium hydroxide prepared from aluminium nitrate, ammonium alum and amalgamated aluminium\\u000a was studied.

L. Moscou; G. S. van der Vlies

1959-01-01

288

Sorption of terephthalate anions by calcined and uncalcined hydrotalcite-like compounds  

Microsoft Academic Search

The uptake of terephthalate anions (TA) from aqueous solutions by Mg–Al–CO3 layered double hydroxides (LDHs) has been investigated. The sorption process, that takes place by the reconstruction of the calcined LDH and involves the intercalation and adsorption of TA, is much more efficient in the uptake of such anion than the pure adsorption process occurring in the parent LDH. The

Eduardo L. Crepaldi; Jairo Tronto; Lucelena P. Cardoso; João B. Valim

2002-01-01

289

Studies on recrystallised aluminium mono-hydroxide precipitates. Kinetics of dissolution by sodium hydroxide solutions  

Microsoft Academic Search

Summary Boehmite powders were prepared by controlled hydrolysis of aluminium isopropoxide solution and recrystallisation in hot water; these were cylinders (fibres) of lengths (I0) = 0.06 to 0.10µm. The dissolution of dilute suspensions of these powders in well-stirred sodium hydroxide solutions was studied at 35 ° to 65 °C. Reaction solid and solution were analysed after different times by chemical

A. Packter

1976-01-01

290

A Ternary Catalytic System for the Room Temperature Suzuki-Miyaura Reaction in Water  

PubMed Central

The formation of Pd(0) in the absence of any classical reducing agent in a medium containing Mg2+/Al3+ layered double hydroxide (LDH) and N,N-dimethylformamide was evidenced. XRD analysis showed the presence of crystalline phases of palladium in the Pd/LDH composite. Suzuki-Miyaura reactions in aqueous medium were carried out at room temperature, and good yields were obtained with bromoarenes and iodoarenes using the ternary system LDH-Pd-CD (cyclodextrin) as catalyst. PMID:24288484

Silva, Aires da Conceicao; Senra, Jaqueline Dias; de Souza, Andrea Luzia Ferreira; Brum Malta, Luiz Fernando

2013-01-01

291

Iron hydroxides in soils: A review of publications  

NASA Astrophysics Data System (ADS)

Iron hydroxides are subdivided into thermodynamically unstable (ferrihydrite, feroxyhyte, and lepidocrocite) and stable (goethite) minerals. Hydroxides are formed either from Fe3+ (as ferrihydrite) or Fe2+ (as feroxyhyte and lepidocrocite). The high amount of feroxyhyte in ferromanganic concretions is proved, which points to the leading role of variable redox conditions in the synthesis of hydroxides. The structure of iron hydroxides is stabilized by inorganic elements, i.e., ferrihydrite, by silicon; feroxyhyte, by manganese; lepidocrocite, by phosphorus; and goethite, by aluminum. Ferrihydrite and feroxyhyte are formed with the participation of biota, whereas the abiotic formation of lepidocrocite and goethite is possible. The iron hydroxidogenesis is more pronounced in podzolic soils than in chernozems, and it is more pronounced in iron-manganic nodules than in the fine earth. Upon the dissolution of iron hydroxides, iron isotopes are fractioned with light-weight 54Fe atoms being dissolved more readily. Unstable hydroxides are transformed into stable (hydr)oxides, i.e., feroxyhyte is spontaneously converted to goethite, and ferrihydrite, to hematite or goethite.

Vodyanitskii, Yu. N.

2010-11-01

292

Nickel hydroxide/cobalt-ferrite magnetic nanocatalyst for alcohol oxidation.  

PubMed

A magnetically separable, active nickel hydroxide (Brønsted base) coated nanocobalt ferrite catalyst has been developed for oxidation of alcohols. High surface area was achieved by tuning the particle size with surfactant. The surface area of 120.94 m2 g(-1) has been achieved for the coated nanocobalt ferrite. Improved catalytic activity and selectivity were obtained by synergistic effect of transition metal hydroxide (basic hydroxide) on nanocobalt ferrite. The nanocatalyst oxidizes primary and secondary alcohols efficiently (87%) to corresponding carbonyls in good yields. PMID:25075969

Bhat, Pooja B; Inam, Fawad; Bhat, Badekai Ramachandra

2014-08-11

293

Conversion coatings prepared or treated with calcium hydroxide solutions  

NASA Technical Reports Server (NTRS)

A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.

Minevski, Zoran (Inventor); Clarke, Eric (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

2002-01-01

294

Hydroxide-Assisted Bonding of Ultra-Low-Expansion Glass  

NASA Technical Reports Server (NTRS)

A process for hydroxide-assisted bonding has been developed as a means of joining optical components made of ultra-low-expansion (ULE) glass, while maintaining sufficiently precise alignment between. The process is intended mainly for use in applications in which (1) bonding of glass optical components by use of epoxy does not enable attainment of the required accuracy and dimensional stability and (2) conventional optical contacting (which affords the required accuracy and stability) does not afford adequate bond strength. The basic concept of hydroxide-assisted bonding is not new. The development of the present process was prompted by two considerations: (1) The expertise in hydroxide-assisted bonding has resided in very few places and the experts have not been willing to reveal the details of their processes and (2) data on the reliability and strength attainable by hydroxide-assisted bonding have been scarce.

Abramovici, Alexander; White, Victor

2008-01-01

295

Reaction of nickel, cobalt, and ferric acetylacetonates with aluminum hydroxide  

Microsoft Academic Search

Fe, Co, and Ni acetylacetonates react with boehmite aluminum hydroxide upon its formation in a mother liquor containing aluminum alcoholate with separation of mixed metal-containing complexes from solution.

M. V. Tsodikov; G. F. Ivanova; O. G. Éllert; Yu. V. Maksimov; O. V. Bukhtenko; B. A. Zaslavskii

1988-01-01

296

21 CFR 872.3250 - Calcium hydroxide cavity liner.  

Code of Federal Regulations, 2010 CFR

...OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide...insertion of restorative material, such as amalgam, to protect the pulp of a tooth. (b) Classification. Class...

2010-04-01

297

68. INTERIOR VIEW LOOKING OF THE CAUSTIC SODA (SODIUM HYDROXIDE) ...  

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

68. INTERIOR VIEW LOOKING OF THE CAUSTIC SODA (SODIUM HYDROXIDE) BUILDING, LOOKING AT CAUSTIC SODA MEASURING TANKS. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

298

Characterization of Silica-Containing Aluminum Hydroxide and Oxide Aerogels  

Microsoft Academic Search

Pure and silica-containing Al hydroxide aerogels were prepared by the supercritical drying method. The samples were later calcined, giving rise to alumina and Si–Al mixed oxides. The materials were characterized from the points of view of their bulk and surface structures. The Si-free material before calcination is well-crystallized boehmite that converts to ?-alumina by calcination. The silica-containing hydroxides are composed

Marcella Trombetta; Guido Busca; Ronald J. Willey

1997-01-01

299

Structural transformation of nickel hydroxide films during anodic oxidation  

SciTech Connect

Investigation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has determined that the phase boundary between the materials evolves via a nodular structure within the electrode film during the anodic oxidation reaction. This nodular growth mechanism is caused by the disparity in conductivity between the phases. Unconverted material is trapped within the film by an overlayer which forms across the film/electrolyte interface. Scanning tunneling microscopy and spectroscopic ellipsometry experiments support this structure model.

Crocker, R.W.; Muller, R.H.

1992-05-01

300

Solvent and process for recovery of hydroxide from aqueous mixtures  

DOEpatents

Hydroxide values and associated alkali metal may be recovered from alkaline aqueous solutions using classes of fluorinated alcohols in a water immiscible solvent. The alcohols are characterized by fluorine substituents which are proximal to the acidic alcohol protons and are located to adjust the acidity of the extractant and the solubility of the extractant in the solvent. A method for stripping the extractant and solvent to regenerate the extractant and purified aqueous hydroxide solution is described.

Moyer, Bruce A. (Oak Ridge, TN); Chambliss, C. Kevin (Macon, GA); Bonnesen, Peter V. (Knoxville, TN); Keever, Tamara J. (Oak Ridge, TN)

2001-01-01

301

Calcium hydroxide suppresses Porphyromonas endodontalis lipopolysaccharide-induced bone destruction.  

PubMed

Porphyromonas endodontalis and its main virulence factor, lipopolysaccharide (LPS), are associated with the development of periapical diseases and alveolar bone loss. Calcium hydroxide is commonly used for endodontic therapy. However, the effects of calcium hydroxide on the virulence of P. endodontalis LPS and the mechanism of P. endodontalis LPS-induced bone destruction are not clear. Calcium hydroxide rescued the P. endodontalis LPS-suppressed viability of MC3T3-E1 cells and activity of nuclear factor-?B (NF-?B) in these cells, resulting in the reduced expression of interleukin-6 and tumor necrosis factor-?. In addition, calcium hydroxide inhibited P. endodontalis LPS-induced osteoclastogenesis by decreasing the activities of NF-?B, p38, and ERK1/2 and the expression of nuclear factor of activated T-cell cytoplasmic 1 in RAW264.7 cells. Calcium hydroxide also rescued the P. endodontalis LPS-induced osteoclastogenesis and bone destruction in mouse calvaria. Taken together, our present results indicate that calcium hydroxide suppressed bone destruction by attenuating the virulence of P. endodontalis LPS on bone cells. PMID:24603641

Guo, J; Yang, D; Okamura, H; Teramachi, J; Ochiai, K; Qiu, L; Haneji, T

2014-05-01

302

The role of calcium hydroxide in the formation of thaumasite  

SciTech Connect

It has recently been derived by thermodynamic calculation that the presence or absence of calcium hydroxide plays a vital role in the resistance of cement paste or concrete against the formation of thaumasite. To obtain experimental data on this matter, special binders have been mixed and used for the preparation of mortar bars. These specimens were exposed to moderate sulphate attack for a period of 18 months at a temperature of 8 deg. C. Mortar bars containing calcium hydroxide showed visual signs of attack a few months after exposure, leading to expansion, mass loss and complete failure. In contrast to this, no signs of attack were observed when no calcium hydroxide was present in the microstructure. These results confirm the conclusions of earlier thermodynamic calculations that the presence of calcium hydroxide has an important impact on the formation of thaumasite. Calcium-rich C-S-H formed in the presence of calcium hydroxide is vulnerable against sulphate attack and the formation of thaumasite. In the absence of calcium hydroxide, C-S-H has a much lower calcium/silicon ratio and a higher resistance against the formation of thaumasite.

Bellmann, F. [Institute for Building Materials Science, Department of Civil Engineering, Bauhaus-University Weimar (Germany)], E-mail: frank.bellmann@bauing.uni-weimar.de; Stark, J. [Institute for Building Materials Science, Department of Civil Engineering, Bauhaus-University Weimar (Germany)

2008-10-15

303

Kinetics of decomposition of hydrogen peroxide on Fe(III)?Al(III) hydroxide-oxide systems  

Microsoft Academic Search

The kinetics of decomposition of hydrogen peroxide have been studied on mixed Fe(III)?Al(III) hydroxide and oxide catalysts. While iron hydroxide possesses considerable catalytic activity, aluminium hydroxide has very little activity. The rate of decomposition on mixed hydroxides increases with increasing concentration of aluminium hydroxide up to about 1.5 mol% and decreases thereafter. The mixed oxides possess negligible activity compared to

B. Mani; Ch. Ravi Mohan; V. Sitakara Rao

1980-01-01

304

Form and stability of aluminum hydroxide complexes in dilute solution  

USGS Publications Warehouse

Laboratory studies of solutions 4.53 x 10 -4 to 4.5 x 10 -5 molal (12.2-1.2 ppm) in aluminum, in 0.01 molal sodium perchlorate, were conducted to obtain information as to the probable behavior of aluminum in natural water. When the solutions were brought to pH 7.5-9.5 and allowed to stand for 24 hours, a precipitate was obtained which was virtually amorphous as shown by X-rays, and which had a solubility equivalent to that of boehmite. This precipitate had a hydrolysis constant (*Ks4) of 1.93 x 10 -13a. When solutions were allowed to stead at this pH range for 10 days, their precipitates gave the X-ray pattern of bayerite (*Ks4 = 1.11 > (10- 4). These hydrolysis constants were obtained at 25?C. and corrected to zero ionic strength and are in close agreement with other published values. The predominant dissolved form in this pH range is Al(OH) -4. Below neutral pH (7.0) the dissolved aluminum species consist of octahedral units in which each aluminum ion is surrounded by six water molecules or hydroxide ions. Single units such as Al(OH2)6 + 3 and AlOH(OH2)5+2 are most abundant below pH 5.0, and where the molar ratio (r) of combined hydroxide to total dissolved aluminum is low. When r is greater than 1.0, polymerization of the octahedral units occurs. When r is between 2.0 and 3.0, solutions aged for 10 days or more contained colloidal particles between 0.10 and 0.45 ? in diameter. Particles whose diameters were greater than 0.10 ? were identified by X-ray diffraction as gibbsite. Particles smaller than 0.10 ? were also present and were shown by means of the electron microscope to have a hexagonal crystal pattern. Structured material consisting of sheets of coalesced six-membered rings of aluminum ions held together by double OH bridges has a distinctive kinetic behavior. This property was used to determine amounts of polymerized material in solutions having r between 1.0 and 3.0 after aging times ranging from a few hours to more than 4 months. Aging increased the size and orderliness of the polymeric aggregates and was accompanied by a decrease in the pH of the solution. The kinetic experiments and stoichiometric data for solutions aged for long periods provided a means of determining activities of polymerized aluminum. From these values the solubility product for microcrystalline gibbsite was determined to be 2.24 x 10 -3, and its free energy of formation, -? 272.3 0.4 kcal per mole. Where polymerization was observed, the process did not stop with small polynuclear complexes containing a few aluminum ions, but proceeded with aging until macromolecules or colloidal-sized particles were formed.

Hem, John David; Roberson, Charles Elmer

1967-01-01

305

PfHRP2 and PfLDH antigen detection for monitoring the efficacy of artemisinin-based combination therapy (ACT) in the treatment of uncomplicated falciparum malaria  

Microsoft Academic Search

BACKGROUND: An assessment of the accuracy of two malaria rapid diagnostic tests (RDT) for the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) or Pf lactate dehydrogenase (PfLDH) was undertaken in children aged between six and 59 months included in an anti-malarial efficacy study in Benin. METHODS: In Allada (Benin), 205 children aged 6-59 months with falciparum malaria received either

Sandrine Houzé; Mainoumata Dicko Boly; Jacques Le Bras; Philippe Deloron; Jean-François Faucher

2009-01-01

306

Combinatorial engineering of ldh-a and bcl-2 for reducing lactate production and improving cell growth in dihydrofolate reductase-deficient Chinese hamster ovary cells  

Microsoft Academic Search

In Chinese hamster ovary (CHO) cells, rapid glucose metabolism normally leads to inefficient use of glucose, most of which\\u000a is converted to lactate during cell cultures. Since lactate accumulation during the culture often exerts a negative effect\\u000a on cell growth and valuable product formation, several genetic engineering approaches have been developed to suppress lactate\\u000a dehydrogenase-A (LDH-A), the enzyme converting pyruvate

Min Kyoung Jeon; Da Young Yu; Gyun Min Lee

307

Layered zinc hydroxide salts: delamination, preferred orientation of hydroxide lamellae, and formation of ZnO nanodiscs.  

PubMed

Delamination of layered zinc hydroxide salts (LZH) into hydroxide layers provides nanobuilding blocs of a two-dimensional anisotropy. The methodology, extent of delamination, the size and stability of hydroxide lamellae are described in detail. The ability of lamellae to restack to form oriented hydroxide films depends on the solvent, original LZH salt, and conditions used for delamination. The most interesting results were obtained using LZH intercalated with dodecyl sulfate anions and LZH nitrate delaminated in butanol at 60 °C and in formamide at room temperature, respectively. The former method produces hydroxide lamellae of a lateral size of ca. 10-20 nm. The inner structure of the hydroxide layers is conserved and separated lamellae restack to the original layered structure of LZH dodecyl sulfate. The latter method yields lamellae with a size decreasing from 73.3 nm to 10 nm after a 2-week aging, while their thickness is nearly constant (2.6-3.8 nm). However, the use of formamide is complicated by the formation of Zn(II) formate. The major part of LZH intercalated with dodecyl sulfate anions is transformed during the delamination procedure to anisotropic ZnO nanoparticles, either needle-like particles prolonged in the [0 0 1] direction or disc-like particles flattened along the (0 0 1) plane. PMID:21636093

Demel, Jan; Pleštil, Josef; Bezdi?ka, Petr; Janda, Pavel; Klementová, Mariana; Lang, Kamil

2011-08-15

308

Solid-state 1H and 27Al NMR studies of amorphous aluminum hydroxides.  

PubMed

Two kinds of amorphous aluminum hydroxides, a sample precipitated from admixing AlCl3 and NaOH aqueous solutions and the commercial product, were measured by 27Al and 1H solid-state NMR spectroscopy. Pentahedral and tetrahedral coordinations, as well as octahedral coordination of oxygen atoms for aluminum, are observed in 27Al magic angle spinning (MAS) spectra of both amorphous samples. In contrast, octahedral coordination is only observed in gibbsite, bayerite, and boehmite. According to 1H MAS-NMR spectra under conditions of high spinning rate (35 kHz) and high field (14.09 T), free waters and OH groups coupled with aluminum for amorphous samples are observed at approximately 5 and approximately 4.5 ppm, respectively, the latter peak being broader. This is consistent with the differential spectra between spin echo and transfer of populations in double resonance. We conclude that the subunits of AlO4, AlO5, and AlO6 in amorphous aluminum hydroxides are bound through hydrogen bonds with a wide distribution of bonding strength. PMID:16256537

Isobe, T; Watanabe, T; d'Espinose de la Caillerie, J B; Legrand, A P; Massiot, D

2003-05-15

309

ALUMINUM REMOVAL AND SODIUM HYDROXIDE REGENERATION FROM HANFORD TANK WASTE BY LITHIUM HYDROTALCITE PRECIPITATION SUMMARY OF PRIOR LAB-SCALE TESTING  

SciTech Connect

Scoping laboratory scale tests were performed at the Chemical Engineering Department of the Georgia Institute of Technology (Georgia Tech), and the Hanford 222-S Laboratory, involving double-shell tank (DST) and single-shell tank (SST) Hanford waste simulants. These tests established the viability of the Lithium Hydrotalcite precipitation process as a solution to remove aluminum and recycle sodium hydroxide from the Hanford tank waste, and set the basis of a validation test campaign to demonstrate a Technology Readiness Level of 3.

SAMS TL; GUILLOT S

2011-01-27

310

Dissolution of nickel hydroxide in ammoniacal aqueous solutions  

NASA Astrophysics Data System (ADS)

The dissolution of nickel hydroxide in ammoniacal solutions was investigated to develop a new recycling process for nickel-metal hydride batteries. The effects of temperature, total ammonia concentration, and pH of the solution were examined in the range of 30 °C to 60 °C, 3.0 to 5.0 M, and 9.0 to 10.7, respectively. All dissolution-time curves showed sigmoidal shapes, which could be approximately expressed by the Johnson-Mehl-Avrami-Yerofeev-Kolmogrov (JMAYK) equation. The hydroxide particles were pitted, and some of them were broken into fragments in the course of the dissolution. An increase in the surface area of the hydroxide particles due to the formation of pits and fragmentation seemed to be the reason for the acceleration of dissolution in the early stage. The surface area of the hydroxide was measured by the Brunauer-Emmett-Teller (BET) method, and the dissolution rate per surface area was determined. The activation energy for the dissolution was obtained as 100±10 kJ mol-1, which confirmed that the dissolution was controlled by chemical reactions at the hydroxide/liquid interface. The dissolution rate was increased by the increase in ammonia concentration, and the highest rate was observed at pH ca. 10.

Miyake, Masao; Maeda, Masafumi

2006-04-01

311

Double Meanings.  

ERIC Educational Resources Information Center

Discusses the use of double meanings and figurative language or figures of speech in literature and how confusing it can be for beginning readers. Describes class activities that can help students construct, examine, and extend the meaning of what they read and includes a worksheet, evaluation suggestions, and extension activities. (LRW)

Davis, Jonathan; Davis, Lisa

2001-01-01

312

Preparation and characterization of iron oxide and hydroxide based nanomaterials  

NASA Astrophysics Data System (ADS)

Iron (Fe) oxides and hydroxides are common and abundant materials. They exhibit diverse crystal structures, properties and phenomena by virtue of which they find a wide range of scientific and technological applications. Controlled growth and manipulation of the specific structure and electronic behavior to meet the requirements of a given application is a challenging problem in view of many possible phases and composition of the resulting materials. The preparation method and experimental conditions will, therefore, significantly affect the properties and performance of Fe oxides and hydroxides. The goal of the project is to obtain Fe-based oxide/hydroxide catalytic materials and to derive a comprehensive understanding of the microstructure and electronic properties. The obvious relevance of the work it to optimize conditions to produce high quality Fe- based nanomaterials capable of dissociating the water molecules and produce hydrogen. The present approach to synthesize Fe oxides and hydroxides is based on a chemical route involving Fe-containing compounds. First step involved is the precipitation of Fe hydroxide/oxide particles from iron salts in an aqueous and non-aqueous media. The resultant precipitates consist of agglomerated nanoparticles. The size of the resulting Fe oxide and hydroxide nanoparticle depends on the concentration of the original solutions. After precipitation, a weak organic acid is added to obtain different concentrations. The samples were obtained at different intervals of time. Structure modification and dispersion of nanoparticles have been achieved and correlated with the concentration of the organic acid. It is demonstrated that the microstructure can be controlled in order to tune the materials' electronic behavior. In addition, the incorporation of various metal ions into the host matrix is explored in order to control the structure and electronic properties. The results are presented and discussed in detail in this dissertation.

Carbajal Franco, Guillermo

313

Adsorption of pepsin by aluminum hydroxide II: Pepsin inactivation.  

PubMed

Pepsin adsorbed on gibbsite or boehmite, non-acid-reactive forms of aluminum hydroxide, had a significantly lower activity than pepsin in solution. IR and desorbed pepsin activity studies showed that the reduced activity of adsorbed pepsin was not due to denaturation of pepsin on adsorption. Steric occlusion of the active site, following pepsin adsorption, was responsible for the lower activity of pepsin adsorbed on gibbsite. The porous morphology of boehmite caused diffusional resistance and steric exclusion, contributing to the decreased activity of adsorbed pepsin. The specific inactivation of pepsin by adsorption on aluminum hydroxide may be important in ulcer therapy. PMID:6440980

Sepelyak, R J; Feldkamp, J R; Regnier, F E; White, J L; Hem, S L

1984-11-01

314

The reaction of cesium hydroxide with 4-phenylvaleric acid  

E-print Network

THE REACTIOR OP CESIUM HYDROXIDE WITH 4-PHEI'YLVALERIC ACID A Thesis by Arvie Jeane Caughfield Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OP SCIENCE... August l967 Ma)or Sub) ect: Chemistry THE REACTION OF CESIUM HYDROXIDE WITH 4-PHENYLVALERIC ACID A Thesis Arvie Jeane Caugh iield Approved as to style and content by: (Chairman of Commit e (Head of De artment) (Member) (Member (Member) (Member...

Caughfield, Arvie Jeane

2012-06-07

315

Double Layers in Astrophysics  

NASA Technical Reports Server (NTRS)

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

Williams, Alton C. (editor); Moorehead, Tauna W. (editor)

1987-01-01

316

Assessing the differential action on cancer cells of LDH-A inhibitors based on the N-hydroxyindole-2-carboxylate (NHI) and malonic (Mal) scaffolds†  

PubMed Central

A head-to-head study of representative examples of N-hydroxyindole-2-carboxylates (NHI) and malonic derivatives (Mal) as LDH-A inhibitors was conducted, comparing enzyme inhibition potency, cellular uptake, reduction of lactate production in cancer cells and anti-proliferative activity. Among the compounds tested, methyl 1-hydroxy-6-phenyl-4-(trifluoromethyl)-1H-indole-2-carboxylate (2, NHI-2), a methyl ester belonging to the NHI class, displayed optimal properties in the cell-based assays, proving to be an efficient anti-glycolytic agent against cancer cells. PMID:23986182

Granchi, Carlotta; Calvaresi, Emilia C.; Tuccinardi, Tiziano; Paterni, Ilaria; Macchia, Marco; Martinelli, Adriano; Hergenrother, Paul J.; Minutolo, Filippo

2013-01-01

317

Pf HRP2 and Pf LDH antigen detection for monitoring the efficacy of artemisinin-based combination therapy (ACT) in the treatment of uncomplicated falciparum malaria  

Microsoft Academic Search

Background  An assessment of the accuracy of two malaria rapid diagnostic tests (RDT) for the detection of Plasmodium falciparum histidine-rich protein 2 (Pf HRP2) or Pf lactate dehydrogenase (Pf LDH) was undertaken in children aged between six and 59 months included in an anti-malarial efficacy study in Benin.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  In Allada (Benin), 205 children aged 6-59 months with falciparum malaria received either

Sandrine Houzé; Dicko Mainoumata Boly; Jacques Le Bras; Philippe Deloron; Jean-François Faucher

2009-01-01

318

LIGNOSULFONATE-MODIFIED CALCIUM HYDROXIDE FOR SULFUR DIOXIDE CONTROL  

EPA Science Inventory

The article discusses the use of lignosulfonate-modified calcium hydroxide Ca(OH)2 for sulfur dioxide (SO2) control. The limestone injection multistage burner (LIMB) process is currently being developed at the U.S. EPA as a low cost retrofittable technology for controlling oxides...

319

Transformations of 4-hydroxymethyl-2-carene over potassium hydroxide  

SciTech Connect

The dehydration of 4-hydroxymethyl-2-carene over potassium hydroxide at 250/sup 0/C, which leads to the formation of 4-methyl-3(10,4-caradiene and 3,4,7,7-tetramethyl-1,3,5-cycloheptatriene, was investigated. The dehydration is accompanied by a small degree of deformylation.

Manukov, E.N.; Vyglazov, O.G.; Chuiko, V.A.; Shingel, I.A.

1986-03-10

320

Engineering evaluation of a sodium hydroxide thermal energy storage module  

NASA Technical Reports Server (NTRS)

An engineering evaluation of thermal energy storage prototypes was performed in order to assess the development status of latent heat storage media. The testing and the evaluation of a prototype sodium hydroxide module is described. This module stored off-peak electrical energy as heat for later conversion to domestic hot water needs.

Perdue, D. G.; Gordon, L. H.

1980-01-01

321

Discolouration of polypropylene-based compounds containing magnesium hydroxide  

Microsoft Academic Search

Magnesium hydroxide is extensively used in the plastics industry as a flame retardant and smoke suppressant in various polymeric matrices (polyolefins, nylons etc.). However, it was found that compounding Mg(OH)2 with polymers leads to the formation of various colours ranging from light grey to rather dark beige. The effect of the temperature and processing technology, and of various properties of

G. I. Titelman; Y. Gonen; Y. Keidar; S. Bron

2002-01-01

322

Dynamic monitoring of structural changes in nickel hydroxide electrodes during discharge in batteries  

Microsoft Academic Search

The nickel hydroxide electrode is used as the positive plate of many rechargeable battery systems such as the nickel\\/cadmium, nickel\\/hydrogen, and nickel\\/metal hydrides. The electrochemical energy storage in the nickel hydroxide electrodes is related to the reversible characteristics of the redox couple nickel hydroxide\\/ox hydroxide. In the present work we describe the use of the electrochemical impedance spectroscopy (EIS) technique

M. Ortiz; D. Becker; G. Garaventta; A. Visintin; E. B. Castro; S. G. Real

2011-01-01

323

Influences of pH value on the microstructure and phase transformation of aluminum hydroxide  

Microsoft Academic Search

The effects of pH value on the composition, structure, morphology, and phase transformation of aluminum hydroxides prepared by chemical precipitation were studied. Aluminum hydroxide precipitated at the pH values of 5 and 6 is amorphous and transforms to ?-Al2O3 at 950 °C via the amorphous aluminum hydroxide ? amorphous Al2O3 ? ?-Al2O3 transformation path. Aluminum hydroxide precipitated at pH=7 is boehmite

Xuelian Du; Yanqin Wang; Xinghua Su; Jiangong Li

2009-01-01

324

Ion-Exchange Preparation of Low-Silica Hydroxide Solutions for Colorimetric Determinations of Total Silica  

Microsoft Academic Search

ATTEMPTS to determine small concentrations of total silica colorimetrically by applying the method of Straub and Grabowski1, following solubilization of the silica by boiling with hydroxide, have been frustrated by the interference of the silica present in either the sodium or potassium hydroxide used as the solubilizing agent. In studying this problem, the possibility of preparing a hydroxide solution by

Sallie Fisher; Robert Kunin

1956-01-01

325

The effect of hydroxide ion on Cd-chalcogenide\\/aqueous polysulfide photoelectrochemical cells  

Microsoft Academic Search

Alkali hydroxide, added to the aqueous polysulfide electrolyte in n-Cd chalcogenide\\/S \\/SUB r\\/ photoelectrochemical solar cells (PEC's), is is shown to be detrimental to cell performance. It is demonstrated that the added hydroxide increases visible light absorption in the polysulfide solution and decreases the solution lifetime. Even after compensation for the decrease in light tranmission by the electrolyte, added hydroxide

Stuart Licht; J. Manassen

1985-01-01

326

Are double translocations double trouble?  

PubMed Central

Double translocation heterozygotes are rare, but need not necessarily pose more of a counselling problem than single reciprocal translocation heterozygotes. Nine cases of double translocation are presented, together with a review of the few reports published to date. An attempt is made to provide simple counselling guidelines in the assessment of the risk of producing a liveborn abnormal child. This is not based on theoretical considerations of segregation patterns, but extrapolated from what is known empirically about the viable segregation patterns in carriers of single reciprocal translocations. It assumes that there is no interference with the independent assortment of the two separate exchanges, unless a common participating chromosome is involved. The possibility of an interchromosomal effect has not been taken into consideration. Images PMID:3290489

Bowser-Riley, S M; Griffiths, M J; Creasy, M R; Farndon, P A; Martin, K E; Thomson, D A; Larkins, S A; Johnson, R A; Watt, J L

1988-01-01

327

Textural and structural studies on nickel hydroxide electrodes. II. Turbostratic nickel (II) hydroxide submitted to electrochemical redox cycling  

Microsoft Academic Search

The textural and structural modifications involved in electrochemical redox cycling of turbostratic nickel (II) hydroxide has been investigated using X-ray diffraction and electron microscopy methods. It was found that during the first cycles, different phenomena compete: redox reactions which occur in the solid state, and ageing reactions via the solution. For the first galvanostatic charge performed at the C\\/5 rate

A. Delahaye-Vidal; M. Figlarz

1987-01-01

328

Production of isoamyl acetate in ackA-pta and/or ldh mutants of Escherichia coli with overexpression of yeast ATF2.  

PubMed

The gene coding for alcohol acetyltransferase ( ATF2), which catalyzes the esterification of isoamyl alcohol and acetyl coenzyme A (acetyl-CoA), was cloned from Saccharomyces cerevisiae and expressed in Escherichia coli. This genetically engineered strain of E. coli produced the ester isoamyl acetate when isoamyl alcohol was added externally to the cell culture medium. Various competing pathways at the acetyl-CoA node were inactivated to increase the intracellular acetyl-CoA pool and divert more carbon flux to the ester synthesis pathway. Several strains with deletions in the ackA-pta and/or ldh pathways and bearing the ATF2 on a high-copy-number plasmid were constructed and studied. Compared to the wild-type, ackA-pta and nuo mutants produced higher amounts of ester and an ackA-pta-ldh-nuo mutant lower amounts. Isoamyl acetate production correlated well with intracellular coenzyme A (CoA) and acetyl-CoA levels. The ackA-pta-nuo mutant had the highest intracellular CoA/acetyl-CoA level and hence produced the highest amount of ester (1.75 mM) during the growth phase under oxic conditions and during the production phase under anoxic conditions. PMID:14586577

Vadali, R V; Horton, C E; Rudolph, F B; Bennett, G N; San, K-Y

2004-02-01

329

Characterization and properties of boron-doped aluminum hydroxide for Mn 2+ adsorption and soil acidification  

Microsoft Academic Search

Al hydroxide was prepared by hydrolysis of Al(NO3)3, and oc-B-Al hydroxide was prepared by hydrolysis of Al(NO3)3 in the presence of boric acid solution. Curve-fitted B1s XPS spectrum of oc-B-Al hydroxide demonstrated that the boron atom was probably incorporated with Al hydroxide to some extent.\\u000a The IR band of Al–OH at 1,074 cm?1 of oc-B-Al hydroxide was weaker than that of

Shuijiao Liao; Guanglong Liu; Duanwei Zhu; Yue Li; Liying Ren; Jingzhen Cui

2011-01-01

330

Hierarchical cobalt-based hydroxide microspheres for water oxidation.  

PubMed

3D hierarchical cobalt hydroxide carbonate hydrate (Co(CO3)0.5(OH)·0.11H2O) has been synthesized featuring a hollow urchin-like structure by a one-step hydrothermal method at modest temperature on FTO glass substrates. The functionalities of precursor surfactants were isolated and analyzed. A plausible formation mechanism of the spherical urchin-like microclusters has been furnished through time-dependent investigations. Introduction of other transitional metal doping (Cu, Ni) would give rise to a substantial morphological change associated with a surface area drop. The directly grown cobalt-based hydroxide composite electrodes were found to be capable of catalyzing oxygen evolution reaction (OER) under both neutral pH and alkaline conditions. The favorable 3D dendritic morphology and porous structure provide large surface areas and possible defect sites that are likely responsible for their robust electrochemical activity. PMID:24525520

Zhang, Ye; Cui, Bai; Derr, Olivia; Yao, Zhibo; Qin, Zhaotong; Deng, Xiangyun; Li, Jianbao; Lin, Hong

2014-03-21

331

Evaluation of barium hydroxide treatment efficacy on a dolomitic marble.  

PubMed

The Arch of Peace, by Luigi Cagnola, is one of the most famous neoclassical monuments in Milan. It has been subjected to conservative intervention in 1998. In the present paper the efficacy of the consolidation by means of barium hydroxide has been evaluated. The stone material showed severe degradation phenomena as: erosion, pulverisation, exfoliation. The analytical data acquired through X-ray diffraction (XRD), infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM-EDX), allowed to compare the conditions of stone before and after the treatment with barium hydroxide. The presence of barium has been put in evidence mainly on the surface as barium sulphate, whereas barium is only sporadically present within the thickness of the decayed material. The treatment was judged not satisfying and its inefficacy is, most probably, due to a not suitable cleaning procedure carried out before the consolidation. PMID:11836959

Toniolo, L; Colombo, C; Realini, M; Peraio, A; Positano, M

2001-01-01

332

Hierarchical cobalt-based hydroxide microspheres for water oxidation  

NASA Astrophysics Data System (ADS)

3D hierarchical cobalt hydroxide carbonate hydrate (Co(CO3)0.5(OH).0.11H2O) has been synthesized featuring a hollow urchin-like structure by a one-step hydrothermal method at modest temperature on FTO glass substrates. The functionalities of precursor surfactants were isolated and analyzed. A plausible formation mechanism of the spherical urchin-like microclusters has been furnished through time-dependent investigations. Introduction of other transitional metal doping (Cu, Ni) would give rise to a substantial morphological change associated with a surface area drop. The directly grown cobalt-based hydroxide composite electrodes were found to be capable of catalyzing oxygen evolution reaction (OER) under both neutral pH and alkaline conditions. The favorable 3D dendritic morphology and porous structure provide large surface areas and possible defect sites that are likely responsible for their robust electrochemical activity.

Zhang, Ye; Cui, Bai; Derr, Olivia; Yao, Zhibo; Qin, Zhaotong; Deng, Xiangyun; Li, Jianbao; Lin, Hong

2014-02-01

333

Characterization of Silica-Containing Aluminum Hydroxide and Oxide Aerogels  

PubMed

Pure and silica-containing Al hydroxide aerogels were prepared by the supercritical drying method. The samples were later calcined, giving rise to alumina and Si-Al mixed oxides. The materials were characterized from the points of view of their bulk and surface structures. The Si-free material before calcination is well-crystallized boehmite that converts to gamma-alumina by calcination. The silica-containing hydroxides are composed of boehmite layers with silicates in the interlayer region. The resulting mixed oxides present silica essentially in the bulk. The surface structure of alumina seems poorly sensitive to silica addition. Surface silanol groups appear only for SiO2 more than 4%. No Bronsted acidity appears. Silica addition allows mixed oxides with higher surface areas to be obtained. PMID:9241185

Trombetta; Busca; Willey

1997-06-15

334

Preparation and photoluminescence study of mesoporous indium hydroxide nanorods  

SciTech Connect

Mesoporous indium hydroxide nanorods were successfully synthesized by a mild one-step one-pot method. The obtained samples were characterized by X-ray diffraction, transmission electron microscopy with selected area electron diffraction, N{sub 2} adsorption, ultraviolet-visible absorption and photoluminescence, respectively. Transmission electron microscopy showed that there were some pores in the samples, which were mainly composed of rod-like shapes with length of 300 nm and diameter of 90 nm. N{sub 2} adsorption/desorption measurements confirmed that the prepared powder was mesoporous with average pore diameter of 3.1 nm. The ultraviolet-visible absorption spectroscopy analysis indicated that the band gap energy of the samples was 5.15 eV. Photoluminescence spectrum showed that there were two strong emissions under ultraviolet light irradiation. The growth mechanism of indium hydroxide nanorods and the role of cetyltrimethyl ammonium bromide were also discussed.

Li, Changyu [College of Material Science and Engineering, Northeast Forestry University, Harbin 150040 (China)] [College of Material Science and Engineering, Northeast Forestry University, Harbin 150040 (China); Lian, Suoyuan [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China) [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China); School of Chemical Engineering and Materials, Dalian Polytechnic University, Dalian 116034 (China); Liu, Yang [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China)] [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China); Liu, Shouxin, E-mail: liushouxin@126.com [College of Material Science and Engineering, Northeast Forestry University, Harbin 150040 (China)] [College of Material Science and Engineering, Northeast Forestry University, Harbin 150040 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China)] [Functional Nano and Soft Materials Laboratory, Soochow University, No. 199 Renai Road, Suzhou, Jiangsu 215123 (China)

2010-02-15

335

Electrochemical impregnation of nickel hydroxide in porous electrodes  

NASA Technical Reports Server (NTRS)

The electrochemical impregnation of nickel hydroxide in porous electrode was investigated both experimentally and theoretically. The loading level and plaque expansion were the most important parameters to be considered. The effects of applied current density, stirring, ratio of solution to electrode volume and pH were identified. A novel flow through electrochemical impregnation is proposed in which the electrolyte is forced through the porous nickel plaque. The thickening of the plaque can be reduced while maintaining high loading capacity. A mathematical model is presented which describes the transport of the nitrate, nickel and hydroxyl ions and the consecutive heterogeneous electrochemical reduction of nitrate and the homogeneous precipitation reaction of nickel hydroxide. The distributions of precipitation rate and active material within the porous electrode are obtained. A semiempirical model is also proposed which takes into account the plugging of the pores.

Ho, Kuo-Chuan; Jorne, Jacob

1987-01-01

336

A Case of Recurrent Renal Aluminum Hydroxide Stone  

PubMed Central

Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca). The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics. PMID:25013740

Cak?roglu, Basri; Dogan, Akif Nuri; Tas, Tuncay; Gozukucuk, Ramazan; Uyanik, Bekir Sami

2014-01-01

337

Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide  

Microsoft Academic Search

Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide was monitored using X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Crystallite sizes and interplanar spacings for boehmite samples were determined. Changes in the crystallinity of boehmite influenced the corresponding FT-IR spectra. The maximum specific area for boehmite powder was 246 m2 g?1, as measured by the Brunauer–Emmet–Teller (BET)

? Drag?evi?; S Popovi?

1999-01-01

338

A voltammetric study of ?- and ?-hydroxides over nickel alloys  

Microsoft Academic Search

The hydrogen evolution reaction (HER) is one of the most studied electrochemical process due to the alternative energy conversion and the importance in some chemical process. The search for new electrocatalytic materials lead to investigate metals and alloys with particular characteristics\\/properties. This paper describes aspects of hydrogen adsorption and Ni-hydroxide formation over nickel alloys (SAF2205, INCONEL625 and MONEL400) utilizing cyclic

J. R. C Salgado; M. H. S Andrade; J. C. P Silva; J Tonholo

2002-01-01

339

Mechanistic study of inhibition of levofloxacin absorption by aluminum hydroxide.  

PubMed Central

The mechanisms of reduction in absorption of levofloxacin (LVFX) by coadministration of aluminum hydroxide were studied. The partition coefficient of LVFX (0.1 mM) between chloroform and phosphate buffer (pH 5.0) was reduced by 60 to 70% with the addition of metal ions such as Cu2+, Al3+, and Fe2+ (0.8 mM), which indicated the formation of LVFX-metal ion chelates. However, there was no significant difference in absorption from rat intestine between the synthetic LVFX-Al3+ (1:1) chelate (6.75 mM) and LVFX (6.75 mM) in an in situ recirculation experiment. On the other hand, Al(NO3)3 (1.5 mM) significantly inhibited the absorption of LVFX (1.5 mM) by 20% of the control in the in situ ligated loop experiment, in which partial precipitation of aluminum hydroxide was observed in the dosing solution. Data for adsorption of LVFX and ofloxacin (OFLX) from aqueous solution by aluminum hydroxide were shown to fit Langmuir plots, and the adsorptive capacities (rmax) and the K values were 7.0 mg/g and 1.77 x 10(4) M-1 for LVFX and 7.4 mg/g and 1.42 x 10(4) M-1 for OFLX, respectively. The rate of adsorption of several quinolones (50 microM) onto aluminum hydroxide (2.5 mg/ml) followed the order norfloxacin (NFLX) (72.0%) > enoxacin (ENX) (61.0%) > OFLX (47.2%) approximately LVFX (48.1%). The elution rate of adsorbed quinolones with water followed the rank order LVFX (17.9%) approximately OFLX (20.9%) approximately ENX (18.3%) > NFLX (11.9%). These results strongly suggest that adsorption of quinolones by aluminum hydroxide reprecipitated in the small intestine would play an important role in the reduced bioavailability of quinolones after coadministration with aluminum-containing antacids. Images PMID:8257141

Tanaka, M; Kurata, T; Fujisawa, C; Ohshima, Y; Aoki, H; Okazaki, O; Hakusui, H

1993-01-01

340

Sustainability Double Degree Double Degree Info  

E-print Network

Sustainability Double Degree Double Degree Info: � 36 credits in B for graduation. Sustainability Core: Take each course below for a total of 17 -20 credits. Term/Grade Course _____ ____ *NR 350 (4) Sustainable

Grünwald, Niklaus J.

341

Double inflation  

SciTech Connect

The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The ..cap omega..-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig.

Silk, J.; Turner, M.S.

1986-04-01

342

Double Your Major, Double Your Return?  

ERIC Educational Resources Information Center

We use the 2003 National Survey of College Graduates to provide the first estimates of the effect on earnings of having a double major. Overall, double majoring increases earnings by 2.3% relative to having a single major among college graduates without graduate degrees. Most of the gains from having a double major come from choosing fields across…

Del Rossi, Alison F.; Hersch, Joni

2008-01-01

343

Long-term phosphorus effects on evolving physicochemical properties of iron and aluminum hydroxides  

Microsoft Academic Search

Iron (Fe) and aluminum (Al) hydroxides are highly reactive components in environmental processes, such as contaminant fate and transport. Phosphorus (P) sorption by these components can decrease environmental problems associated with excess accumulation of P in soils. The long-term stability of P sorbed by Fe\\/Al hydroxides is of major concern. Synthetic Fe and Al hydroxides coprecipitated with P (1:1 metal:P

Konstantinos C. Makris; Willie G. Harris; George A. O'Connor; Hassan El-Shall

2005-01-01

344

Method of treating inflammatory diseases using a radiolabeled ferric hydroxide calloid  

DOEpatents

A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints.

Atcher, Robert W. (Chicago, IL); Hines, John J. (Glen Ellyn, IL)

1992-01-01

345

Modeling Saccharide, Amino Acid and Organophosphate Adsorption to Silica and Fe-Hydroxides  

Microsoft Academic Search

Three main types of molecules exist within the extracellular material surrounding bacteria: polysaccharides, proteins and DNA. This study investigated short-range interactions between small-scale, simplified models of each of these types with silica and Fe-hydroxide surfaces. The results suggest that the strongest interaction is that between phosphate groups of DNA with Fe-hydroxides followed by amino acid\\/silica and polysaccharide\\/Fe-hydroxide. The interaction of

J. D. Kubicki; K. Kwon; R. K. Campen

2003-01-01

346

Influence of aluminium precursor on physico-chemical properties of aluminium hydroxides and oxides  

Microsoft Academic Search

Summary  An attempt to obtain aluminium hydroxide that could give aluminium oxides of increased thermal stability was made. Aluminium\\u000a hydroxide was precipitated during a hydrolysis of aluminium chloride in ammonia medium. The influence of preparative conditions,\\u000a such as a dosing rate of aluminium precursor, pH, duration of the precipitate refluxing and temperature of calcination, on\\u000a the properties of obtained hydroxides and

Olga Kluk-P?osko?ska; D. Szychowski

347

a Nuclear Magnetic Resonance and a Nuclear Quadrupole Resonance Study of the Phases and Solid State Transformations in the Alkali Metal Hydroxides - Lithium-Hydroxide Sodium - Potassium-Hydroxide Rubidium-Hydroxide Cesium - and Cesium-Hydroxide - Water.  

NASA Astrophysics Data System (ADS)

The proton NMR lineshapes for all alkali metal hydroxides, except LiOH, have a weak doublet structure (most pronounced in KOH). This structure was explained by modelling the arrangement of hydrogen atoms with a 4 -spin planar zig-zag chain. The second moments of proton NMR recorded at 27 MHz and at 295 K are 8.8, 10.8, 6.5, 4.8 and 4.1 (gauss)('2) for LiOH, NaOH, KOH, RbOH and CsOH respectively. The phase diagram for NaOH and Na(,2)CO(,3) has been reviewed and appended using DTA results. The NMR of ('23)NaOH (QCC = 3.52 (+OR-) 0.06 MHz and (eta) < 0.04 at 295 K) has been measured from 77 K to 570 K. The temperature dependence of the NQR of ('23)NaOH, studied from 77 K to 550 K, shows a change in slope and a discontinuous change in NQR frequency of 6 (+OR-) 2 kHz on crossing from the orthorhombic to monoclinic phases. At 292 K, the sodium NQR frequency was 1.778 (+OR-) 0.001 MHz. The DTA and NQR results for ('23)NaOD show a phase transition at 160 K with an enthalpy change of 200 (+OR-) 75 J/mol. There is no corresponding transition in NaOH above 110 K. The deuterium NMR in NaOD was studied from 293 K to 570 K (QCC = 245 (+OR-) 2 kHz and (eta) = 0.05 (+OR-) 0.01 at 293 K). The decrease in deuterium QCC with increasing temperature was fitted to a librating molecule model and confirmed that the frequency of the OD('-) libration decreases in the monoclinic phase. The proton NMR linewidth in NaOH narrows from 10 gauss FWHM at 295 K to 1 gauss at 550 K due to proton conduction. The proton T(,1) (T(,1) = 300 sec. at 41 MHz and 293 K) decreases with increasing temperature and is extremely dependent on H(,2)O content. From the NMR of ('87)RbOH at 293 K, it was estimated that QCC = 9 (+OR-) 1 MHz. The ('133)Cs NMR in CsOH(.)H(,2)O was studied from 230 K to 470 K. At 293 K, QCC = 101 (+OR -) 2 kHz with (eta) = 0. The ('133)Cs NMR changes at the 232 K transition but varies smoothly through the 340 K transition in CsOH(.)H(,2)O. The unusual deuterium quadrupole coupling for the OD('-) ion in CsOD (QCC = 143 (+OR-) 2 kHz, (eta) = 0.66 (+OR-) 0.01 at 295 K) indicates that the OD('-) ion is orientationally disordered, with two equivalent deuterium sites in the orthorhombic phase. Below 247 K in CsOD (232 K in CsOH), the deuterium NMR suggests that the OD('-) ions are not orientationally disordered.

Amm, David Thomas

348

Mössbauer and magnetic study of Co  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrites Co x Fe3-x O4 (x = 1 or 2) have been obtained either by mechanical milling or thermal treatment of pre-prepared layered double hydroxide carbonate x-LDH CO3. Mechanical milling of the 1-LDH CO3 leads to the large-scale preparation of nearly spherical nanoparticles of CoFe2O4, the size of which (5 to 20 nm) is controlled by

C. Estournès; C. D'Orléans; J.-L. Rehspringer; E. Manova; B. Kunev; D. Paneva; I. Mitov; L. Petrov; M. Kurmoo

2005-01-01

349

Sodium hydroxide anodization of Ti-Al-4V adherends  

NASA Technical Reports Server (NTRS)

The use of sodium hydroxide anodization (SHA) for Ti-6Al-4V adherends is examined. The SHA surface is evaluated using SEM, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The SHA procedures of Kennedy et al. (1983) were employed in this experiment. The photomicrographs of the SHA (sandblasted) and PSHA (sandblasted and pickled) oxide surface reveal that the two surfaces differ. The PSHA is patchy and similar to a chromic acid anodization surface and the porosity of the PSHA is more uniform than the SHA surface. The compositions of the surfaces are studied. It is noted that SHA is an effective pretreatment for Ti-6Al-4V adherends.

Filbey, Jennifer A.; Wightman, J. P.; Progar, D. J.

1987-01-01

350

Is a Plasmodium lactate dehydrogenase (pLDH) enzyme-linked immunosorbent (ELISA)-based assay a valid tool for detecting risky malaria blood donations in Africa?  

PubMed Central

Background Malaria is a leading cause of mortality in southern Benin. The main causative agent, Plasmodium falciparum, poses a threat on critical transfusions in pregnant women and children. This study’s objective was to compare the performance of different malaria screening methods in blood donors in southern Benin, a malaria-endemic country. Methods Blood from 2,515 voluntary blood donors in Benin was collected over a period of 10 months in ethylenediaminetetraacetic acid (EDTA) tubes, which were then classified according to extraction time: long rainy season, short dry season, short rainy season, and long dry season. Microscopic examination was used to count parasites. Parasite density (PD) was expressed as the number of parasites per ?L of blood. Pan Plasmodium pLDH detection was assessed by an ELISA-malaria antigen test. Using crude soluble P. falciparum antigens, an ELISA-malaria antibody test detected anti-Plasmodium antibodies. Results Among the 2,515 blood donors (2,025 males and 488 females) screened, the rate of asymptomatic Plasmodium carriage was 295/2,515 (11.72%, 95% CI: 10.5-13.1%). Males had a higher infection rate (12.4%) than did females (8.8%). Parasite density was very low: between seven and100 parasites per ?L of blood was reported in 80% of donors with parasitaemia. Three Plasmodium species were diagnosed: P. falciparum in 280/295 patients (95.0%), Plasmodium malariae in 14/295 (5.0%), and Plasmodium ovale in 1/295 (0.34%). Malaria prevalence in donors was higher during the rainy seasons (13.7%) compared with the dry seasons (9.9%). The use of a highly sensitive assay enabled pan Plasmodium pLDH detection in 966/2,515 (38.4%, 95% CI: 36.5%-40.3%). Malaria antibody prevalence was 1,859/2,515 (73.9%, 95% CI: 72.16-75.6%). Donors’ antigenaemia and antibody levels varied significantly (P <0.05) over the course of the four seasons. The highest antigenaemia rate 323/630 (51.3%), was observed during the short rainy season, while the highest antibody prevalence, 751/886 (84.7%), was recorded during the long dry season. Conclusion Blood donations infected with Plasmodium can transmit malaria to donation recipients. Malaria diagnostic methods are currently available, but the feasibility criteria for mass screening in endemic areas become preponderant. Detection of the pLDH antigen seems to be an adequate screening tool in endemic areas, for this antigen indicates parasite presence. Routine screening of all donated blood would prevent infected blood donations and reduce P. falciparum transmission in critical patients, such as children and pregnant women. This tool would also decrease medical prophylaxis in donation recipients and contribute to lower Plasmodium resistance. PMID:23927596

2013-01-01

351

Accuracy of PfHRP2 versus Pf-pLDH antigen detection by malaria rapid diagnostic tests in hospitalized children in a seasonal hyperendemic malaria transmission area in Burkina Faso  

PubMed Central

Background In most sub-Saharan African countries malaria rapid diagnostic tests (RDTs) are now used for the diagnosis of malaria. Most RDTs used detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2), though P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH)-detecting RDTs may have advantages over PfHRP2-detecting RDTs. Only few data are available on the use of RDTs in severe illness and the present study compared Pf-pLDH to PfHRP2-detection. Methods Hospitalized children aged one month to 14 years presenting with fever or severe illness were included over one year. Venous blood samples were drawn for malaria diagnosis (microscopy and RDT), culture and complete blood count. Leftovers were stored at ?80 °C and used for additional RDT analysis and PCR. An RDT targeting both PfHRP2 and Pf-pLDH was performed on all samples for direct comparison of diagnostic accuracy with microscopy as reference method. PCR was performed to explore false-positive RDT results. Results In 376 of 694 (54.2%) included children, malaria was microscopically confirmed. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value were 100.0, 70.9, 69.4 and 100.0%, respectively for PfHRP2-detection and 98.7, 94.0, 91.6 and 99.1%, respectively for Pf-pLDH-detection. Specificity and PPV were significantly lower for PfHRP2-detection (p <0.001). For both detection antigens, specificity was lowest for children one to five years and in the rainy season. PPV for both antigens was highest in the rainy season, because of higher malaria prevalence. False positive PfHRP2 results were associated with prior anti-malarial treatment and positive PCR results (98/114 (86.0%) samples tested). Conclusion Among children presenting with severe febrile illness in a seasonal hyperendemic malaria transmission area, the present study observed similar sensitivity but lower specificity and PPV of PfHRP2 compared to Pf-pLDH-detection. Further studies should assess the diagnostic accuracy and safety of an appropriate Pf-pLDH-detecting RDT in field settings and if satisfying, replacement of PfHRP2 by Pf-pLDH-detecting RDTs should be considered. PMID:24418119

2014-01-01

352

Interaction of Pu(IV,VI) hydroxides/oxides with metal hydroxides/oxides in alkaline media  

SciTech Connect

The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.

Fedoseev, A.M.; Krot, N.N.; Budantseva, N.A.; Bessonov, A.A.; Nikonov, M.V.; Grigoriev, M.S.; Garnov, A.Y.; Perminov, V.P.; Astafurova, L.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

1998-08-01

353

Nickel hydroxide and other nanophase cathode materials for rechargeable batteries  

NASA Astrophysics Data System (ADS)

The staff of US Nanocorp, Inc. are developing unique nanostructured materials for a wide range of applications in the areas of energy storage (batteries and ultracapacitors) and energy conversion (fuel cells and thermoelectric) devices. Many of the preparations of these materials exploit a wet synthesis process (patent pending) that is scaleable to large volume manufacturing and anticipated to be low in cost. Specifically, both the ?-form of nickel hydroxide and the hollandite form of manganese dioxide have been synthesized. The hexagonal Ni(OH) 2 is anticipated to significantly boost energy densities in nickel-alkaline batteries, including nickel/cadmium, nickel/metal hydride and nickel/zinc. The nanophase MnO 2 microstructure exhibits an unusual tunnelled tubular geometry within a 'bird's nest' superstructure, and is expected to be of interest as an intercalation cathode material in lithium-ion systems as well as a catalyst for fuel cells. Characterization of these materials has been by the techniques of high resolution SEM and TEM, as well as XRD. Both Hg porosimetry and BET surface measurements for conventional and spherical nickel hydroxides are summarized. Pore distribution and electrochemical activity for the nanophase materials will be examined in the future.

Reisner, David E.; Salkind, Alvin J.; Strutt, Peter R.; Xiao, T. Danny

354

Vibrational and orientational dynamics of water in aqueous hydroxide solutions  

NASA Astrophysics Data System (ADS)

We report the vibrational and orientational dynamics of water molecules in isotopically diluted NaOH and NaOD solutions using polarization-resolved femtosecond vibrational spectroscopy and terahertz time-domain dielectric relaxation measurements. We observe a speed-up of the vibrational relaxation of the O-D stretching vibration of HDO molecules outside the first hydration shell of OH- from 1.7 ± 0.2 ps for neat water to 1.0 ± 0.2 ps for a solution of 5 M NaOH in HDO:H2O. For the O-H vibration of HDO molecules outside the first hydration shell of OD-, we observe a similar speed-up from 750 ± 50 fs to 600 ± 50 fs for a solution of 6 M NaOD in HDO:D2O. The acceleration of the decay is assigned to fluctuations in the energy levels of the HDO molecules due to charge transfer events and charge fluctuations. The reorientation dynamics of water molecules outside the first hydration shell are observed to show the same time constant of 2.5 ± 0.2 ps as in bulk liquid water, indicating that there is no long range effect of the hydroxide ion on the hydrogen-bond structure of liquid water. The terahertz dielectric relaxation experiments show that the transfer of the hydroxide ion through liquid water involves the simultaneous motion of ˜7 surrounding water molecules, considerably less than previously reported for the proton.

Hunger, Johannes; Liu, Liyuan; Tielrooij, Klaas-Jan; Bonn, Mischa; Bakker, Huib

2011-09-01

355

DIRECT ELECTROCHEMICAL POWER GENERATION FROM CARBON IN FUEL CELLS WITH MOLTEN HYDROXIDE ELECTROLYTE  

Microsoft Academic Search

Historically, despite its compelling cost and performance advantages, the use of a molten metal hydroxide electrolyte has been ignored by direct carbon fuel cell (DCFC) researchers, primarily due to the potential for formation of carbonate salt in the cell. This article describes the electrochemistry of a patented medium-temperature DCFC based on a molten hydroxide electrolyte, which overcomes the historical carbonate

Strahinja Zecevic; Edward M. Patton; Parviz Parhami

2005-01-01

356

Temporal resolution of ion and solvent transfers at nickel hydroxide films exposed to LiOH  

Microsoft Academic Search

A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor mobile species transfers on short time scales following the application of a potential step to potentiostatically deposited ?-nickel hydroxide films exposed to aqueous LiOH solution. Upon film oxidation, hydroxide ions enter the film and protons are deintercalated. However, the protons are not detected

Heidi M French; Mark J Henderson; A. Robert Hillman; Eric Vieil

2002-01-01

357

tert-Butylzinc hydroxide as an efficient predesigned precursor of ZnO nanoparticles.  

PubMed

The reaction of (t)Bu(2)Zn with water was investigated which led to isolation of the novel hexameric tert-butylzinc hydroxide. The resulting zinc hydroxide cluster appears to be an ideal predesigned single-source precursor which decomposes smoothly in one step at only ca. 120 °C into ZnO nanoparticles. PMID:21483925

Bury, Wojciech; Krajewska, El?bieta; Dutkiewicz, Micha?; Soko?owski, Kamil; Justyniak, Iwona; Kaszkur, Zbigniew; Kurzyd?owski, Krzysztof J; P?oci?ski, Tomasz; Lewi?ski, Janusz

2011-05-21

358

BIOGEOCHEMICAL PROCESSES CONTROLLING ARSENIC SPECIATION AND BIOTRANSFORMATION IN GRANULAR FERRIC HYDROXIDE COATED SAND  

EPA Science Inventory

Arsenic mobilization from solid phase Fe (III) hydroxides is an issue of concern, as water-borne arsenic can migrate into pristine environments, endangering aquatic and human life. In general, metal oxide (hydroxides) exerts a dominating effect on the fate and transport of arseni...

359

Why does the IR spectrum of hydroxide stretching vibration weaken with increase in hydration?  

PubMed

The infrared absorption intensity of hydroxide stretching vibration is strong in the gas phase, however it becomes weak in the aqueous phase. To provide an understanding of this relationship, we performed theoretical studies on OH(-)(H2O)n, n = 0-5 clusters, with the water molecules bound to the oxygen edge of the hydroxide. We found that with the increase in n, the infrared intensity of hydroxide stretching vibration decreases. This is rationalized by the positive potential that the water molecules exert on the oxygen edge of the hydroxide. Directional hydrogen bonding by the water molecules stabilizes the oxygen atomic orbitals in hydroxide, thus decreasing the electron-migration from oxygen 2p? to hydrogen in hydroxide. These characteristics cause the dipole moment derivative of the hydroxide stretching vibration to be minimal, resulting in a weaker infrared absorption intensity for large n. In addition, we showed that this hydration effect can also be observed through the successive increase in the vertical electron detachment energy as a function of n. Lastly, we discuss the implications of this study on the dangling hydroxide at the air-water interface. PMID:25252111

Morita, Masato; Takahashi, Hirokazu; Yabushita, Satoshi; Takahashi, Kaito

2014-10-01

360

Rapid collection of iron hydroxide for determination of Th isotopes in seawater.  

PubMed

This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin directly, resulting in a pH increase of the effluent by release of hydroxide ion from the iron hydroxide. The co-precipitated thorium isotopes were quantitatively collected within the column, which indicated that thorium was retained on the iron hydroxide remaining on the chelating column. The chelating column quantitatively collected (232)Th with iron hydroxide in seawater at flow rates of 20-25 mL min(-1). Based on this flow rate, a 5 L sample was processed within 3-4 h. The >20 h aging of iron hydroxide tends to reduce the recovery of (232)Th. The rapid collection method was successfully applied to the determination of (230)Th and (232)Th in open-ocean seawater samples. PMID:24267072

Okubo, Ayako; Obata, Hajime; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi

2013-12-01

361

Microstructure of aluminum hydroxides and the formation of aluminum dye lakes.  

PubMed

The effect of processing variables on the type of aluminum hydroxide and the dye content of the resultant lakes were investigated. The solid-state structure of aluminum lakes in conjunction with the associated aluminum hydroxide was studied by electron microscopy, X-ray diffraction, and IR spectroscopy. The conditions under which the aluminum hydroxide was prepared were shown to govern the amorphous/crystalline character of the product, which was reflected in changes in particle size and surface area. A hypothesis for the interaction of the dye and aluminum hydroxide is formulated in which the amount of dye adsorbed on the aluminum hydroxide is dependent on the surface area of the microstructures present. PMID:6527247

Wou, L L; Mulley, B A

1984-12-01

362

Cytotoxicity evaluation of Iranian propolis and calcium hydroxide on dental pulp fibroblasts.  

PubMed

Background and aims. Since intracanal medicaments can affect the cell viability in periapical tissues, the aim of this study was to evaluate the effect of calcium hydroxide and propolis on pulp fibroblasts. Materials and methods. Two healthy third molars were used as a source to obtain fibroblasts. The fibroblasts were cultured and subjected to 1 mg/mL of propolis and calcium hydroxide. This experiment was performed in six replicates and cell viability was evaluated with MTT assay. Statistical analysis was performed by t-test. Results. Comparison of cell viability with the use of 1 mg/mL of calcium hydroxide and propolis showed that cells subjected to propolis were more viable when compared to calcium hydroxide (P < 0.05). Conclusion. In this study, calcium hydroxide reduced fibroblast viability, significantly more than Iranian propolis. Other properties should be evaluated before Iranian propolis could be indicated for use as intracanal medicament. PMID:25346830

Zare Jahromi, Maryam; Ranjbarian, Parisa; Shiravi, Samaneh

2014-01-01

363

Cytotoxicity Evaluation of Iranian Propolis and Calcium Hydroxide on Dental Pulp Fibroblasts  

PubMed Central

Background and aims. Since intracanal medicaments can affect the cell viability in periapical tissues, the aim of this study was to evaluate the effect of calcium hydroxide and propolis on pulp fibroblasts. Materials and methods. Two healthy third molars were used as a source to obtain fibroblasts. The fibroblasts were cultured and subjected to 1 mg/mL of propolis and calcium hydroxide. This experiment was performed in six replicates and cell viability was evaluated with MTT assay. Statistical analysis was performed by t-test. Results. Comparison of cell viability with the use of 1 mg/mL of calcium hydroxide and propolis showed that cells subjected to propolis were more viable when compared to calcium hydroxide (P < 0.05). Conclusion. In this study, calcium hydroxide reduced fibroblast viability, significantly more than Iranian propolis. Other properties should be evaluated before Iranian propolis could be indicated for use as intracanal medicament.

Zare Jahromi, Maryam; Ranjbarian, Parisa; Shiravi, Samaneh

2014-01-01

364

Arsenate and arsenite adsorption and desorption behavior on coprecipitated aluminum:iron hydroxides.  

PubMed

Although arsenic adsorption/desorption behavior on aluminum and iron (oxyhydr)oxides has been extensively studied, little is known about arsenic adsorption/desorption behavior by bimetal Al:Fe hydroxides. In this study, influence of the Al:Fe molar ratio, pH, and counterion (Ca2+ versus Na+) on arsenic adsorption/desorption by preformed coprecipitated Al:Fe hydroxides was investigated. Adsorbents were formed by initial hydrolysis of mixed Al3+/ Fe3+ salts to form coprecipitated Al:Fe hydroxide products. At Al:Fe molar ratios < or = 1:4, Al3+ was largely incorporated into the iron hydroxide structure to form a poorly crystalline bimetal hydroxide; however, at higher Al:Fe molar ratios, crystalline aluminum hydroxides (bayerite and gibbsite) were formed. Although approximately equal As(V) adsorption maxima were observed for 0:1 and 1:4 Al:Fe hydroxides, the As(III) adsorption maximum was greater with the 0:1 Al: Fe hydroxide. As(V) and As(III) adsorption decreased with further increases in Al:Fe molar ratio. As(V) exhibited strong affinity to 0:1 and 1:4 Al:Fe hydroxides at pH 3-6. Adsorption decreased at pH > 6.5; however, the presence of Ca2+ compared to Na+ as the counterion enhanced As( retention by both hydroxides. There was more As(V) and especially As(III) desorption by phosphate with an increase in Al:Fe molar ratio. PMID:17328191

Masue, Yoko; Loeppert, Richard H; Kramer, Tim A

2007-02-01

365

Cellulose aerogels from aqueous alkali hydroxide-urea solution.  

PubMed

Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2. Their morphology, pore structure, and physical properties were characterized by scanning and transmission electron microscopy, X-ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400-500 m2 g(-1)) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors. PMID:18605678

Cai, Jie; Kimura, Satoshi; Wada, Masahisa; Kuga, Shigenori; Zhang, Lina

2008-01-01

366

Mixed metal hydroxide drilling fluid minimizes well bore washouts  

SciTech Connect

This paper reports that the use of a mixed metal hydroxide (MMH) drilling fluid, instead of a conventional polymer-based fluid, improved well bore stability in troublesome formations in West Africa. The unique flow and suspension characteristics of the MMH fluid improved cuttings removal and decreased well bore washouts. With fewer hole problems and better cleaning in the well, the operator reduced drilling time and cost of the well. MMH compounds were developed and introduced to the drilling industry a few years ago. Initially their utility was limited by an inability to achieve reliable filtration control without destroying the unique fluid rheology. A fully functional drilling fluid system, based on this unusual line of chemistry, has been developed and used with great success in dozens of wells around the world.

Lavoix, F. (Elf Aquitaine Production, Pau (France)); Lewis, M. (International Drilling Fluids Inc., Houston, TX (United States))

1992-09-28

367

Stabilization of aluminum hydroxide gel by specifically adsorbed carbonate.  

PubMed

Ion-free aluminum hydroxide gel, prepared by the hydrolysis of aluminum tri-sec-butoxide, was observed by IR, X-ray analysis, and pH-stat titration to undergo rapid structural changes leading to the formation of pseudoboehmite and bayerite. The rate of development of order was directly related to the water-aluminum molar ratio. The Al--O bands at 625 and 470 cm-1 were the most sensitive indicators of the development of order in the gel structure. Direct evidence for the stabilizing effect of specifically adsorbed carbonate was obtained when carbon dioxide was introduced during the hydrolysis of aluminum tri-sec-butoxide. The resulting aluminum hydroxycarbonate gel possessed excellent antacid properties, retained its amorphous nature upon aging, and contained no cations other than aluminum. Hydrolysis of aluminum tri-sec-butoxide in the presence of stoichiometric amounts of sodium bicarbonate resulted in the immediate formation of crystalline sodium aluminum hydroxycarbonate (dawsonite). PMID:6886983

Serna, C J; Lyons, J C; White, J L; Hem, S L

1983-07-01

368

Critical operating parameters for microwave solidification of hydroxide sludge  

SciTech Connect

Engineers at the Rocky Flats Plant (RFP) have developed an innovative technology for the treatment of homogeneous wet or dry solids which are contaminated with hazardous and/or radioactive materials. The process uses microwave energy to heat and melt the waste into a vitreous final form that is suitable for land disposal. The advantages include a high density, leach resistant, robust waste form; volume and toxicity reduction; favorable economics; in-container treatment; favorable public acceptance; isolated equipment; and instantaneous energy control. Regulatory certification of the final form is accomplished by meeting the limitation specified in EPA`s Toxicity Characteristic Leach Procedure (TCLP). This paper presents the results from a series of TCLP tests performed on a surrogate hydroxide coprecipitation sludge spiked with heavy metals at elevated concentrations. The results are very encouraging and support RFP`s commitment to the use of microwave technology for treatment of various mixed waste streams.

Sprenger, G.S.; Eschen, V.G.

1993-08-01

369

Extended development of a sodium hydroxide thermal energy storage module  

NASA Technical Reports Server (NTRS)

The post-test evaluation of a single heat exchanger sodium hydroxide thermal energy storage module for use in solar electric generation is reported. Chemical analyses of the storage medium used in the experimental model are presented. The experimental verification of the module performance using an alternate heat transfer fluid, Caloria HT-43, is described. Based on these results, a design analysis of a dual heat exchanger concept within the storage module is presented. A computer model and a reference design for the dual system (storage working fluid/power cycle working fluid) were completed. The dual system is estimated to have a capital cost of approximately one half that of the single heat exchanger concept.

Rice, R. E.; Rowny, P. E.; Cohen, B. M.

1980-01-01

370

Altering surface characteristics of polypropylene mesh via sodium hydroxide treatment.  

PubMed

Incisional hernias represent a serious and common complication following laparotomy. The use of synthetic (e.g. polypropylene) meshes to aid repair of these hernias has considerably reduced recurrence rates. While polypropylene is biocompatible and has a long successful clinical history in treating hernias and preventing reherniation, this material may suffer some limitations, particularly in challenging patients at risk of wound failure due to, for example, an exaggerated inflammation reaction, delayed wound healing, and infection. Surface modification of the polypropylene mesh without sacrificing its mechanical properties, critical for hernia repair, represents one way to begin to address these clinical complications. Our hypothesis is treatment of a proprietary polypropylene mesh with sodium hydroxide (NaOH) will increase in vitro NIH/3T3 cell attachment, predictive of earlier and improved cell colonization and tissue integration of polypropylene materials. Our goal is to achieve this altered surface functionality via enhanced removal of chemicals/oils used during material synthesis without compromising the mechanical properties of the mesh. We found that NaOH treatment does not appear to compromise the mechanical strength of the material, despite roughly a 10% decrease in fiber diameter. The treatment increases in vitro NIH/3T3 cell attachment within the first 72 h and this effect is sustained up to 7 days in vitro. This research demonstrates that sodium hydroxide treatment is an efficient way to modify the surface of polypropylene hernia meshes without losing the mechanical integrity of the material. This simple procedure could also allow the attachment of a variety of biomolecules to the polypropylene mesh that may aid in reducing the complications associated with polypropylene meshes today. PMID:22337661

Regis, Shawn; Jassal, Manisha; Mukherjee, Nilay; Bayon, Yves; Scarborough, Nelson; Bhowmick, Sankha

2012-05-01

371

An Aluminum Magnesium Hydroxide Stearate-based Skin Barrier Protection Cream Used for the Management of Eczematous Dermatitis  

PubMed Central

Eczematous dermatoses can often be very difficult to treat. An aluminum magnesium hydroxide stearate-based cream has recently become available for clinical use. Aluminum magnesium hydroxide stearate-based cream provides an alternative option in treating these dermatoses while providing barrier protection against external allergens and irritants. This article reviews various studies evaluating aluminum magnesium hydroxide stearate-based cream. PMID:21212843

Bhambri, Sanjay; Michaels, Brent

2008-01-01

372

Effect of hydroxides and hydroxycarbonate structure on fire retardant effectiveness and mechanical properties in ethylene-vinyl acetate copolymer  

Microsoft Academic Search

The flame retardant effect of inorganic hydroxides, like aluminum hydroxide and magnesium hydroxide in ethylene vinyl acetate copolymer, was evaluated and compared with that of other inorganic fillers such as boehmite and hydrotalcite. The thermal decomposition of the fillers and the mixtures with EVA polymer were analysed by differential scanning calorimetry (DSC), Thermogravimetry (TG) and X-ray diffraction (XRD). The most

G. Camino; A. Maffezzoli; M. Braglia; M. De Lazzaro; M. Zammarano

2001-01-01

373

Performance of a HRP-2/pLDH based rapid diagnostic test at the Bangladesh-India-Myanmar border areas for diagnosis of clinical malaria  

PubMed Central

Background The rapid diagnostic test (RDT) has been adopted in contemporary malaria control and management programmes around the world as it represents a fast and apt alternative for malaria diagnosis in a resource-limited setting. This study assessed the performance of a HRP-2/pLDH based RDT (Parascreen® Pan/Pf) in a laboratory setting utilizing clinical samples obtained from the field. Methods Whole blood samples were obtained from febrile patients referred for malaria diagnosis by clinicians from two different Upazila Health Complexes (UHCs) located near the Bangladesh-India and Bangladesh-Myanmar border where malaria is endemic. RDT was performed on archived samples and sensitivity and specificity evaluated with expert microscopy (EM) and quantitative PCR (qPCR). Results A total of 327 clinical samples were made available for the study, of which 153 were Plasmodium falciparum-positive and 54 were Plasmodium vivax-positive. In comparison with EM, for P. falciparum malaria, the RDT had sensitivity: 96.0% (95% CI, 91.2-98.3) and specificity: 98.2% (95% CI, 94.6-99.5) and for P. vivax, sensitivity: 90.7% (95% CI, 78.9-96.5) and specificity: 98.9% (95% CI, 96.5-99.7). Comparison with qPCR showed, for P. falciparum malaria, sensitivity: 95.4% (95% CI, 90.5-98.0) and specificity: 98.8% (95% CI, 95.4-99.7) and for P. vivax malaria, sensitivity: 89.0% (95% CI,77.0-95.4) and specificity: 98.8% (95% CI, 96.5-99.7). Sensitivity varied according to different parasitaemia for falciparum and vivax malaria diagnosis. Conclusion Parascreen® Pan/Pf Rapid test for malaria showed acceptable sensitivity and specificity in border belt endemic areas of Bangladesh when compared with EM and qPCR. PMID:24172045

2013-01-01

374

The effects of magnesium hydroxide on the absorption and efficacy of two glibenclamide preparations.  

PubMed Central

1. The effect of magnesium hydroxide on the absorption and efficacy of two glibenclamide preparations was investigated in healthy volunteers in two separate studies, using a randomized cross-over design with two phases. 2. A single dose of magnesium hydroxide (850 mg) or water only (150 ml) was given immediately after the ingestion of a micronised (1.75 mg, seven subjects) or a non-micronised (2.5 mg, six subjects) preparation of glibenclamide. Plasma concentrations of glibenclamide, insulin and glucose were measured. 3. Magnesium hydroxide accelerated (P less than 0.05) the absorption of glibenclamide from the micronised preparation to a small extent but the extent of absorption and the insulin and glucose responses were unaltered. 4. Coadministration of magnesium hydroxide with the non-micronised glibenclamide preparation increased the area under the plasma glibenclamide concentration-time curve from 0 to 3 h, five-fold (P less than 0.05), the total area three-fold (P less than 0.05) and the peak drug concentration three-fold (P less than 0.05). The incremental insulin area from 0 to 3 h was increased 35-fold (P less than 0.05) and the maximum insulin response 10-fold (P less than 0.05) by magnesium hydroxide. 5. Concomitant ingestion of magnesium hydroxide and non-micronised glibenclamide may greatly enhance the absorption and efficacy of glibenclamide. The absorption of micronised glibenclamide appears to be only slightly influenced by magnesium hydroxide. PMID:1931470

Neuvonen, P J; Kivisto, K T

1991-01-01

375

Synthesis, characterization, and CO(2) adsorptive behavior of mesoporous AlOOH-supported layered hydroxides.  

PubMed

A novel CO(2) solid sorbent was prepared by synthesizing and modifying AlOOH-supported CaAl layered double hydroxides (CaAl LDHs), which were prepared by using mesoporous alumina (?-Al(2)O(3)) and calcium chloride (CaCl(2)) in a hydrothermal urea reaction. The nanostructured CaAl LDHs with nanosized platelets (3-30 nm) formed and dispersed inside the crystalline framework of mesoporous AlOOH (boehmite). By calcination of AlOOH-supported LDHs at 700 °C, the mesoporous CaAl metal oxides exhibited ordered hexagonal mesoporous arrays or uniform nanotubes with a large surface area of 273 m(2) g(-1) , a narrow pore size distribution of 6.2 nm, and highly crystalline frameworks. The crystal structure of the calcined mesoporous CaAl metal oxides was multiphasic, consisting of CaO/Ca(OH)(2), Al(2)O(3), and CaAlO mixed oxides. The mesoporous metal oxides were used as a solid sorbent for CO(2) adsorption at high temperatures and displayed a maximum CO(2) capture capacity (?45 wt %) of the sorbent at 650 °C. Furthermore, it was demonstrated that the mesoporous CaAl oxides showed a more rapid adsorption rate (for 1-2 min) and longer cycle life (weight change retention: 80 % for 30 cycles) of the sorbent because of the greater surface area and increased number of activated sites in the mesostructures. A simple model for the formation mechanism of mesoporous metal oxides is tentatively proposed to account for the synergetic effect of CaAl LDHs on the adsorption of CO(2) at high temperature. PMID:22488944

Chang, Yen-Po; Chen, Yu-Chun; Chang, Po-Hsueh; Chen, San-Yuan

2012-07-01

376

Well-dispersed bi-component-active CoO/CoFe2O4 nanocomposites with tunable performances as anode materials for lithium-ion batteries.  

PubMed

CoO/CoFe(2)O(4) nanocomposites, derived from scalably prepared CoFe-layered double hydroxide (CoFe-LDH) single-resource precursors, exhibit tunable cycle performances and rate capabilities, which are supported by the homogenous dispersion of bi-component active CoO and CoFe(2)O(4) phases. PMID:22076807

Li, Meixia; Yin, Ya-Xia; Li, Congju; Zhang, Fazhi; Wan, Li-Jun; Xu, Sailong; Evans, David G

2012-01-11

377

DOI: 10.1021/la903935j 6593Langmuir 2010, 26(9), 65936603 Published on Web 02/24/2010 pubs.acs.org/Langmuir  

E-print Network

.acs.org/Langmuir © 2010 American Chemical Society Formation of Green Rust Sulfate: A Combined in Situ Time-Resolved X 11, 2010 The mechanism of green rust sulfate (GR-SO4) formation was determined using a novel in situ rust (GR) compounds are a unique class of layered double-hydroxide (LDH) phases with the general

Benning, Liane G.

378

Detection of interstellar sodium hydroxide in self-absorption toward the galactic center  

NASA Technical Reports Server (NTRS)

A weak self-absorbed emission line, which is identified as the J = 4-3 transition of sodium hydroxide, has been detected in the direction of Sgr B2(OH). The correspondingly weak Sgr B2(QH) emission line U75406, previously reported as an unidentified spectral feature by other investigators, is consistent with the J = 3-2 transition of sodium hydroxide. This detection may represent the first evidence of a grain reaction formation mechanism for simple metal hydroxides. The detection of H62 Delta toward Orion A is also reported.

Hollis, J. M.; Rhodes, P. J.

1982-01-01

379

One-dimensional copper hydroxide nitrate nanorods and nanobelts for radiochemical applications  

NASA Astrophysics Data System (ADS)

I report a facile wet-chemical method for the synthesis of one-dimensional copper hydroxide nitrate nanostructures in 2-propanol under solvothermal conditions. Single-crystalline nearly monodispersed copper hydroxide nitrate nanorods and nanobelts with selected breadths in the range of 100 nm to 1 ?m have been successfully prepared by a solvothermal method through controlling the experimental parameters, including initial concentrations of reagents, reaction temperature, solvent and reaction time. The resultant nanorods and nanobelts were characterized using FESEM, TEM, XRD, FTIR and TGA techniques. Upon thermal calcination, the copper hydroxide nitrate nanorods and nanobelts self-assemble into one-dimensional arrays (rods, belts or tubes) of copper oxide nanoparticles. The as-prepared copper hydroxide nitrate nanorods and nanobelts were tested as ion exchangers for removal of long-lived radioactive anions such as 129I- and 99TcO4-. The copper hydroxide nitrate nanorods or nanobelts were over two times more active in the removal of anion species than copper hydroxide nitrate nanoplatelets.I report a facile wet-chemical method for the synthesis of one-dimensional copper hydroxide nitrate nanostructures in 2-propanol under solvothermal conditions. Single-crystalline nearly monodispersed copper hydroxide nitrate nanorods and nanobelts with selected breadths in the range of 100 nm to 1 ?m have been successfully prepared by a solvothermal method through controlling the experimental parameters, including initial concentrations of reagents, reaction temperature, solvent and reaction time. The resultant nanorods and nanobelts were characterized using FESEM, TEM, XRD, FTIR and TGA techniques. Upon thermal calcination, the copper hydroxide nitrate nanorods and nanobelts self-assemble into one-dimensional arrays (rods, belts or tubes) of copper oxide nanoparticles. The as-prepared copper hydroxide nitrate nanorods and nanobelts were tested as ion exchangers for removal of long-lived radioactive anions such as 129I- and 99TcO4-. The copper hydroxide nitrate nanorods or nanobelts were over two times more active in the removal of anion species than copper hydroxide nitrate nanoplatelets. Electronic supplementary information (ESI) available: FESEM, TEM, EDX and SAED results for Cu2(OH)3NO3 and CuO nanostructures. See DOI: 10.1039/c2nr32439c

Liu, Bin

2012-10-01

380

Comparative Proton Transfer Efficiencies of Hydronium and Hydroxide in Aqueous Solution: Proton Transfer vs Brownian Motion.  

PubMed

With the help of QM/EFP-MD with modern correlated quantum theories, distinctly different proton transport dynamics for hydronium and hydroxide ions was revealed. The efficiency of proton transfer for hydronium was found to be significantly higher than that for hydroxide, and the difference in efficiency increased as the temperature was lowered. This difference in dynamics suggests that molecular Brownian diffusion may play an important role in hydroxide transport. Our theoretical findings are consistent with recent experimental observations of proton transfer in amorphous solid water. PMID:25365595

Uddin, Nizam; Kim, Jeongmin; Sung, Bong June; Choi, Tae Hoon; Choi, Cheol Ho; Kang, Heon

2014-11-26

381

The effect of aluminum hydroxide dissolution on the bleeding of aluminum lake dyes.  

PubMed

The effect of pH on the bleeding of FD&C yellow No. 5 aluminum lake and FD&C red No. 40 aluminum lake was investigated. The pH-bleeding profiles corresponded to the pH-solubility profile of aluminum hydroxide. The similarity of the bleeding profiles of both lake dyes and the pH-solubility profile of aluminum hydroxide indicates that pH related bleeding, other than that occurring by competition with anions, is a result of dissolution of the aluminum hydroxide substrate. This dissolution is related to the properties of the substrate rather than to the structure of adsorbed dye. PMID:8272407

Desai, A; Peck, G E; Lovell, J E; White, J L; Hem, S L

1993-10-01

382

Use of a three-band HRP2/pLDH combination rapid diagnostic test increases diagnostic specificity for falciparum malaria in Ugandan children  

PubMed Central

Background Rapid diagnostic tests (RDTs) for malaria provide a practical alternative to light microscopy for malaria diagnosis in resource-limited settings. Three-band RDTs incorporating two parasite antigens may have enhanced diagnostic specificity, relative to two-band RDTs with a single parasite antigen (typically histidine-rich protein 2 [HRP2]). Methods Phase 1: 2,000 children, two months to five years of age, admitted to a referral hospital in Jinja, Uganda, with acute febrile illness were enrolled. A WHO highly rated three-band RDT was compared to light microscopy of thick peripheral blood films read by local expert microscopists. Phase 2: the three-band RDT was used as a screening tool for inclusion of patients in a clinical trial, and subjects with three positive RDT bands were tested by microscopy using blood samples drawn in parallel. Discordant results were adjudicated by PCR. Results Phase 1: 1,648 children had both a RDT and peripheral blood smear performed. The specificity of a RDT with all three bands positive was 82% (95% CI: 79-85%) compared to 62% (95% CI: 59-66%) for HRP2 alone. The sensitivity was 88% (95%?CI: 85-89%) and 94% (95%?CI: 92-95%) for three-band positive RDT and HRP2 antigen, respectively. 119 patients (7.2%) had a positive HRP2 band, but negative parasite lactate dehydrogenase (pLHD) band and negative peripheral smear, and 72 (61%) of these had received pre-treatment with anti-malarials, suggesting a false positive HRP2 result (p?=?0.002). Phase 2: the positive predictive value (PPV) of the three-band RDT was 94% (95%?CI 89%-97%) using microscopy as the reference standard. However, microscopy-discordant results were shown to be positive for P. falciparum by PCR in all cases, suggesting that the PPV was in fact higher. Conclusion The pLDH antigen on three-band RDTs, used in combination with HRP2, provides added diagnostic specificity for malaria parasitaemia and may be useful to distinguish acute infection from recently treated infection. In situations where diagnostic specificity is desirable (e.g., for selection of malaria-infected participants in clinical trials), a three-band RDT should be considered in a sub-Saharan African setting. PMID:24484540

2014-01-01

383

Low-temperature synthesis of binary cuprates from hydroxide precursor  

NASA Astrophysics Data System (ADS)

Binary cuprates of Sr2CuO3+? and SrCuO2 have been synthesized at low temperatures below 500 °C under various values of partial oxygen-pressureP_{O_2 } by thermal decomposition of hydroxide precursors, Sr2Cu(OH)6 and SrCu(OH)4, respectively. The tetragonal Sr2CuO3+? (? ˜ 0.3) is obtained by the heat-treatment at 400 ° C andP_{O_2 } ? 0.2 atm. The value of ? appears to be independent ofP_{O_2 } and unchangeable. On the other hand, the orthorhombic Sr2CuO3+? (? ˜ 0) is obtained by the heat-treatment at 400 °C in flowing gas of N2. For 0

Kato, Masatsune; Miyajima, Toyoo; Nagai, Ichiro; Koike, Yoji

1996-12-01

384

Bromate removal from water by granular ferric hydroxide (GFH).  

PubMed

The feasibility of granular ferric hydroxide (GFH) for bromate removal from water has been studied. Batch experiments were performed to study the influence of various experimental parameters such as effect of contact time, initial bromate concentration, temperature, pH and effect of competing anions on bromate removal by GFH. The adsorption kinetics indicates that uptake rate of bromate was rapid at the beginning and 75% adsorption was completed in 5 min and equilibrium was achieved within 20 min. The sorption process was well described by pseudo-second-order kinetics. The maximum adsorption potential of GFH for bromate removal was 16.5 mg g(-1) at 25 degrees C. The adsorption data fitted well to the Langmuir model. The increase in OH peak and absence of Br-O bonding in FTIR spectra indicate that ion-exchange was the main mechanism during bromate sorption on GFH. The effects of competing anions and solution pHs (3-9) were negligible. Results of the present study suggest that GFH can be effectively utilized for bromate removal from drinking water. PMID:19481866

Bhatnagar, Amit; Choi, Yanghun; Yoon, Yeojoon; Shin, Yongsoon; Jeon, Byong-Hun; Kang, Joon-Wun

2009-10-15

385

Atomistic Simulations of Uranium Incorporation into Iron (Hydr)Oxides  

SciTech Connect

Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr)oxide minerals: goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(III) to Fe(II)). For goethite, deprotonation of first shell hydroxyls enables substitution of U for Fe(III) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ~3.6 Å were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(III) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr)oxide minerals.

Kerisit, Sebastien N.; Felmy, Andrew R.; Ilton, Eugene S.

2011-04-29

386

In vivo toxicity studies of europium hydroxide nanorods in mice  

SciTech Connect

Lanthanide nanoparticles and nanorods have been widely used for diagnostic and therapeutic applications in biomedical nanotechnology due to their fluorescence and pro-angiogenic properties to endothelial cells, respectively. Recently, we have demonstrated that europium (III) hydroxide [Eu{sup III}(OH){sub 3}] nanorods, synthesized by the microwave technique and characterized by several physico-chemical techniques, can be used as pro-angiogenic agents which introduce future therapeutic treatment strategies for severe ischemic heart/limb disease, and peripheral ischemic disease. The toxicity of these inorganic nanorods to endothelial cells was supported by several in vitro assays. To determine the in vivo toxicity, these nanorods were administered to mice through intraperitoneal injection (IP) everyday over a period of seven days in a dose dependent (1.25 to 125 mg kg{sup -1} day{sup -1}) and time dependent manner (8-60 days). Bio-distribution of europium elements in different organs was analyzed by inductively coupled plasma mass spectrometry (ICPMS). Short-term (S-T) and long-term (L-T) toxicity studies (mice euthanized on days 8 and 60 for S-T and L-T, respectively) show normal blood hematology and serum clinical chemistry with the exception of a slight elevation of liver enzymes. Histological examination of nanorod-treated vital organs (liver, kidney, spleen and lungs) showed no or only mild histological changes that indicate mild toxicity at the higher dose of nanorods.

Patra, Chitta Ranjan [Department of Biochemistry and Molecular Biology, 200 First Street S.W, Guggenheim 1321A, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States)], E-mail: patra.chittaranjan@mayo.edu; Abdel Moneim, Soha S. [Gastroenterology and Hepatology, GI Research Unit, 200 First Street S.W, Guggenheim 1034, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Wang, Enfeng; Dutta, Shamit; Patra, Sujata [Department of Biochemistry and Molecular Biology, 200 First Street S.W, Guggenheim 1321A, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Eshed, Michal [Department of Chemistry and Kanbar Laboratory for Nanomaterials, Bar-Ilan University Center for Advanced Materials and Nanotechnology, Bar-Ilan University, Ramat-Gan 52900 (Israel); Mukherjee, Priyabrata [Department of Biochemistry and Molecular Biology, 200 First Street S.W, Guggenheim 1321A, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Department of Biomedical Engineering, 200 First Street S.W, Guggenheim 1334, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Gedanken, Aharon [Department of Chemistry and Kanbar Laboratory for Nanomaterials, Bar-Ilan University Center for Advanced Materials and Nanotechnology, Bar-Ilan University, Ramat-Gan 52900 (Israel); Shah, Vijay H. [Gastroenterology and Hepatology, GI Research Unit, 200 First Street S.W, Guggenheim 1034, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Mukhopadhyay, Debabrata [Department of Biochemistry and Molecular Biology, 200 First Street S.W, Guggenheim 1321A, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States); Department of Biomedical Engineering, 200 First Street S.W, Guggenheim 1334, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905 (United States)

2009-10-01

387

Adsorption of pepsin by aluminum hydroxide I: Adsorption mechanism.  

PubMed

Adsorption of pepsin by gibbsite and boehmite, non-acid-reactive forms of aluminum hydroxide, was observed and related to the surface area of the adsorbent. Adsorption was pH dependent, with maximum adsorption occurring between pH 2.7-3.3 for gibbsite and pH 2.7-4.3 for boehmite. Electrostatic attraction was an important adsorption mechanism at the pH conditions encountered in the GI tract; the isoelectric point of pepsin was approximately 1, giving it a negative charge, and the point of zero charge for the adsorbents was greater than 9, giving them a positive charge. However, the pH-adsorption profile can not be fully explained by electrostatic considerations. Desorption studies indicate the importance of specific adsorption because pepsin was not desorbed by washing with acidified water, but was partly desorbed by exchange with phosphate. The IR spectrum of adsorbed pepsin also suggested that specific adsorption of pepsin occurred through anionic ligand exchange involving carboxylate groups of pepsin and surface aluminum ions. PMID:6440979

Sepelyak, R J; Feldkamp, J R; Moody, T E; White, J L; Hem, S L

1984-11-01

388

In Vivo Toxicity Studies of Europium Hydroxide Nanorods in Mice  

PubMed Central

Lanthanide nanoparticles and nanorods have been widely used for diagnostic and therapeutic applications in biomedical nanotechnology due to their fluorescence properties and pro-angiogenic to endothelial cells, respectively. Recently, we have demonstrated that europium (III) hydroxide [EuIII(OH)3] nanorods, synthesized by the microwave technique and characterized by several physico-chemical techniques, can be used as pro-angiogenic agents which introduce future therapeutic treatment strategies for severe ischemic heart/limb disease, and peripheral ischemic disease. The toxicity of these inorganic nanorods to endothelial cells was supported by several in vitro assays. To determine the in vivo toxicity, these nanorods were administered to mice through intraperitoneal injection (IP) everyday over a period of seven days in a dose dependent (1.25 to 125 mgKg?1day?1) and time dependent manner (8–60 days). Bio-distribution of europium elements in different organs was analyzed by inductively coupled plasma mass spectrometry (ICPMS). Short-term (S-T) and long-term (L-T) toxicity studies (mice sacrificed on day 8 and 60 for S-T and L-T, respectively) show normal blood hematology and serum clinical chemistry with the exception of a slight elevation of liver enzymes. Histological examination of nanorod treated vital organs (liver, kidney, spleen and lungs) showed no or only mild histological changes that indicate mild toxicity at the higher dose of nanorods. PMID:19616569

Patra, Chitta Ranjan; Abdel Moneim, Soha S.; Wang, Enfeng; Dutta, Shamit; Patra, Sujata; Eshed, Michal; Mukherjee, Priyabrata; Gedanken, Aharon; Shah, Vijay H; Mukhopadhyay, Debabrata

2009-01-01

389

Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags  

NASA Astrophysics Data System (ADS)

Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

Chattopadhyay, S.; Mitchell, A.

1990-08-01

390

Lack of teratogenicity of aluminum hydroxide in mice  

SciTech Connect

The embryotoxic and teratogenic potential of aluminum hydroxide, a therapeutic drug used as an antacid and phosphate binder, was investigated in Swiss mice. Mated female mice were given by gavage daily doses of 0, 66.5, 133 or 266 mg/kg of A1(OH)/sub 3/ on gestation days 6 through 15 and killed on gestation day 18. Females were evaluated for body weight gain, food consumption appearance and behavior, survival rates, and reproduction data. No significant effects attributable to A1(OH)/sub 3/ were noted in comparisons of maternal body weight and food consumption values, appearance and behavior. No treatment-related changes were recorded in the number of total implants, resorptions, the number of live and dead fetuses, fetal size parameters or fetal sex distribution data. Gross external, soft tissue and skeletal examination of the A1-treated fetuses did not reveal differences at any dose in comparison with the controls. Thus, no evidence of maternal toxicity, embryo/fetal toxicity or teratogenicity was observed with A1(OH)/sub 3/ in mice.

Domingo, J.S.; Mercedes Gomez, M.A.B.; Corbella, J.

1989-01-01

391

75 FR 28608 - Calcium Hydroxide; Receipt of Application for Emergency Exemption, Solicitation of Public Comment  

Federal Register 2010, 2011, 2012, 2013

...nurseries to control Eleutherodactylus frogs. The applicant proposes the use of a new...nurseries to control Eleutherodactylus frogs. Information in accordance with 40 CFR...hydroxide is necessary to control the tropical frogs, Eleutherodactylus coqui and E....

2010-05-21

392

Electrocatalytic reduction of nitrate and nitrite at Nafion-coated electrodes in concentrated sodium hydroxide solution.  

National Technical Information Service (NTIS)

The electrochemical reduction of nitrate ions in alkaline solution has been studied using various cathode materials and is the basis for a patent describing the conversion of nitrate into hydroxide ion in carbonate solutions. Recently, Taniguchi et al. ha...

H. Li J. Q. Chambers, D. T. Hobbs

1988-01-01

393

Ferric hydroxide and ferric hydroxysulfate precipitation by bacteria in an acid mine drainage lagoon  

E-print Network

Ferric hydroxide and ferric hydroxysulfate precipitation by bacteria in an acid mine drainage communities growing in an acid mine drainage lagoon sediment has confirmed that microorganisms were also: Ferrihydrite; Ferric hydroxysulfate; Bacteria; Biomineralization; Acid mine drainage Contents 1. Introduction

Konhauser, Kurt

394

Optical properties of porous nano-composites of zinc (hydr)oxide with graphite oxide  

NASA Astrophysics Data System (ADS)

The optical properties of zinc (hydr)oxide and the composites of zinc (hydr)oxide with 2% and 5% graphite oxide were investigated by three spectroscopic techniques: absorption, fluorescence and photocurrent techniques. The obtained energy gaps (from 2.85 eV to 2.95 eV) of the composites were smaller than that for zinc oxide (~3.2 eV) and zinc (hydr)oxide (~3.00 eV). The band gap narrowing of the composite materials is due to presence of defects, less confinement, and larger particles. The bonds between zinc (hydr)oxide lattice and the carbon of graphene phase also contribute to this phenomenon.

Islam, S. M. Z.; Gayen, Taposh; Seredych, Mykola; Bandosz, Teresa J.; Alfano, Robert

2013-03-01

395

Proton Transfer in Concentrated Aqueous Hydroxide Visualized using Ultrafast Infrared Spectroscopy  

E-print Network

While it is generally recognized that the hydroxide ion can rapidly diffuse through aqueous solution due to its ability to accept a proton from a neighboring water molecule, a description of the OH? solvation structure and ...

Roberts, Sean Thomas

396

Mixed layered Ni–Mn–Co hydroxides: Crystal structure, electronic state of ions, and thermal decomposition  

Microsoft Academic Search

It has been shown that varying conditions of co-precipitation processes, two types of mixed Ni–Mn–Co hydroxides: either brucite, or hydrotalcite-like (LDHs)—with different Ni\\/Mn\\/Co ratio can be prepared. According to XPS study, these hydroxides are mixed-valence materials: Ni ions present in 2+ oxidation state, whereas Mn and Co ions are in 3+\\/4+ and 2+\\/3+ state, respectively; their oxidation state increases with

N. V. Kosova; E. T. Devyatkina; V. V. Kaichev

2007-01-01

397

Catalytic and inhibiting effects of lithium peroxide and hydroxide on sodium chlorate decomposition  

SciTech Connect

Chemical oxygen generators based on sodium chlorate and lithium perchlorate are used in airplanes, submarines, diving, and mine rescue. Catalytic decomposition of sodium chlorate in the presence of cobalt oxide, lithium peroxide, and lithium hydroxide is studied using thermal gravimetric analysis. Lithium peroxide and hydroxide are both moderately active catalysts for the decomposition of sodium chlorate when used alone, and inhibitors when used with the more active catalyst cobalt oxide.

Cannon, J.C.; Zhang, Y. [Puritan-Bennett Corp., Lenexa, KS (United States)

1995-09-01

398

Absorption of sulfur dioxide into aqueous sodium hydroxide and sodium sulfite solutions  

Microsoft Academic Search

The rates of absorption of pure sulfur dioxide into aqueous sodium bisulfite, sodium hydroxide, and sodium sulfite solutions with and without a surface active agent were measured at 25°C using a liquid jet column. For the sulfur dioxide-sodium hydroxide system, the rate of absorption into the solution without surface active agent was higher than that into the solution with surface

Haruo Hikita; Satoru Asai; Tadashi Tsuji

1977-01-01

399

Removal of selenite using ‘waste’ Fe(III)\\/Cr(III) hydroxide: Adsorption kinetics and isotherms  

Microsoft Academic Search

Removal of selenite [Se (IV)] from aqueous solution on to industrial solid ‘waste’ Fe(III)\\/Cr(III) hydroxide as adsorbent was investigated in the present article. Maximum adsorption was found to be at pH 4.0. Pretreated Fe(III)\\/Cr(III) hydroxide was found to be more efficient for the removal of selenite compared to untreated adsorbent. Langmuir and Freundlich isotherms have been studied. The Langmuir adsorption

C. Namasivayam; K. Prathap

2006-01-01

400

Chemical injury to the tongue following contact with sodium hydroxide drain cleaner.  

PubMed

Solid sodium hydroxide compounds are used to unclog drains. In Turkey, these agents are easily available and commonly used by housewives. They are sold in weak bags and usually stored within these bags. We present the case of an elderly woman with dementia who developed severe alkaline tongue burn and edema after unintentional short contact with solid sodium hydroxide drain cleaner. Official legislation for safety packing in Turkey will lead to reduction in the incidence of accidental caustic injuries. PMID:15587249

Yanturali, Sedat; Yaka, Elif; Ersoy, Gurkan

2004-12-01

401

Facile approach to prepare loose-packed cobalt hydroxide nano-flakes materials for electrochemical capacitors  

Microsoft Academic Search

Cobalt hydroxide nano-flakes are successfully synthesized by a facile chemical precipitation method. Electrochemical characterization is performed using cyclic voltammetry, chronopotentiometry and impedance spectroscopy, respectively. These cobalt hydroxide nano-flakes maintain high utilization at high rates of discharge. A maximum specific capacitance of 735Fg?1 can be achieved in 2M aqueous KOH with the potential range from ?0.2 to 0.4V (vs. SCE) in

Ling-Bin Kong; Jun-Wei Lang; Min Liu; Yong-Chun Luo; Long Kang

2009-01-01

402

Evolution of phase composition in the thermal decomposition of nanosized aluminum hydroxides  

Microsoft Academic Search

The thermal decomposition of nanosized aluminum hydroxides, which are precipitated from solution in direct and inverse mixing\\u000a of the chemical agents, is studied. The thermal treatment of hydroxides between 370 and 870 K results in their two-stage thermal\\u000a decomposition. Intermediate decomposition products are amorphous aluminum oxyhydroxide AlO(OH)1+x\\u000a and boehmite. Nanosized ?-Al2O3 begins forming even at 570 K. The thermal decomposition

S. V. Gabelkov; R. V. Tarasov; N. S. Poltavtsev; Yu. P. Kurilo

2009-01-01

403

Formation characteristics of an aluminum hydroxide fiber by a hydrolysis of aluminum nano powder  

Microsoft Academic Search

Formation of aluminum hydroxide by a hydrolytic reaction of nano aluminum powder synthesized by a pulsed wire evaporation\\u000a (PWE) method has been studied. The type and morphology of the hydroxides were investigated with various initial pH and temperatures.\\u000a The nano fibrous boehmite (AlOOH) was formed predominantly over 40°C of the hydrolytic temperature, while the bayerite (Al(OH)3) was formed predominantly below

Young Hwa Oh; Chang Kyu Rhee; Do Hyang Kim; Geun Hee Lee; Whung Whoe KIM

2006-01-01

404

Modification Effects of Hematite with Aluminum Hydroxide on the Removal of Fluoride Ions from Water  

Microsoft Academic Search

The modification effects of hematite with aluminum hydroxide were investigated on the removal of fluoride ions from water\\u000a using batch experiments. The effects of pH, contact time, fluoride concentration, and the dose of sorbent on the sorption\\u000a of fluoride ions by a modified hematite were studied. Characterization of hematite before and after the modification with\\u000a aluminum hydroxide was studied by

A. Teutli-Sequeira; Marcos Solache-Ríos; P. Balderas-Hernández

405

Characterization and simulation of a lithium hydroxide sorbent bed for life support applications  

Microsoft Academic Search

Packed beds of lithium hydroxide (LiOH) have been used to remove carbon dioxide in closed environments where space and mass are design criteria. The space suit systems of the Apollo astronauts held a LiOH system; developmental rebreathers for the U.S. Navy Seals contained LiOH; and space suits of the Shuttle U.S. astronauts contained a packed bed of lithium hydroxide to

Bernadette Luna

2007-01-01

406

Fabrication of functional transition metal oxide and hydroxide used as catalysts and battery materials  

Microsoft Academic Search

My research is focused on developing metal oxide and hydroxide nanomaterials which can be used as battery materials, organic transformation catalysts, and photocatalysts. This research involves studying ZnO with different morphologies as photocatalysts for phenol degradation, producing CuO as olefin epoxidation catalysts, developing V and Cu incorporated manganese oxides as cathode materials for Li-ion batteries, and fabricating alpha-nickel hydroxide for

Linping Xu

2010-01-01

407

Germanium electrode in an electrochemically active heterostructure with hydroxide proton conductor at room temperature  

NASA Astrophysics Data System (ADS)

A macroscopic heterostructure synthesized in the form of a germanium-hydroxide proton conductor-graphite assembly generates electric voltage comparable with that in polymer microfuel cells (0.7 V). Germanium-containing heterostructures, operating at room temperature and involving no precious metals, can be used as electric current sources for low-power devices. From the fundamental standpoint, a new combination of solid hydroxide proton conductors with group-IV electrodes is also of interest.

Baikov, Yu. M.

2014-06-01

408

The structure of amorphous bulk and silica-supported copper(II) hydroxides  

SciTech Connect

Determination of the structure of surface hydroxocompounds is one of the most delicate areas of environmental chemistry, geochemistry, and catalysis. In nature, these compounds are formed everywhere, mostly by absorption of multicharged metal cations on different soil constitutents from water solutions. The data obtained show that at pH 7 copper(II) ions are adsorbed on a SiO{sub 2} surface as polymeric species of hydroxide nature. The structure of these species is similar to that of the bulk amorphous copper hydroxide. The amorphous state of supported Cu(OH){sub 2} is caused by a small (ca. 11 {angstrom}) size of the surface particles. In contrast, the overstoichiometric water molecules seem to act as ``amorphizers`` of the bulk copper hydroxide. The structures of the bulk and dispersed amorphous copper(II) hydroxide were determined. The amorphous Cu(OH){sub 2} has a layered structure close to the structure of the crystalline hydroxide, but the layers in the amorphous hydroxide are shifted toward one another approximately for {1/4} of the c period of the lattice.

Kriventsov, V.V.; Kochubey, D.I.; Elizarova, G.L.; Matvienko, L.G.; Parmon, V.N. [Boreskov Inst. of Catalysis, Novosibirsk (Russian Federation)] [Boreskov Inst. of Catalysis, Novosibirsk (Russian Federation)

1999-07-01

409

One-dimensional copper hydroxide nitrate nanorods and nanobelts for radiochemical applications.  

PubMed

I report a facile wet-chemical method for the synthesis of one-dimensional copper hydroxide nitrate nanostructures in 2-propanol under solvothermal conditions. Single-crystalline nearly monodispersed copper hydroxide nitrate nanorods and nanobelts with selected breadths in the range of 100 nm to 1 ?m have been successfully prepared by a solvothermal method through controlling the experimental parameters, including initial concentrations of reagents, reaction temperature, solvent and reaction time. The resultant nanorods and nanobelts were characterized using FESEM, TEM, XRD, FTIR and TGA techniques. Upon thermal calcination, the copper hydroxide nitrate nanorods and nanobelts self-assemble into one-dimensional arrays (rods, belts or tubes) of copper oxide nanoparticles. The as-prepared copper hydroxide nitrate nanorods and nanobelts were tested as ion exchangers for removal of long-lived radioactive anions such as (129)I(-) and (99)TcO(4)(-). The copper hydroxide nitrate nanorods or nanobelts were over two times more active in the removal of anion species than copper hydroxide nitrate nanoplatelets. PMID:23070067

Liu, Bin

2012-11-21

410

The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac.  

PubMed Central

1. The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac was investigated in two randomized cross-over studies, both consisting of two phases. 2. Single doses of magnesium hydroxide (850 mg) or of water (150 ml) only were given to six healthy volunteers immediately after the ingestion of ibuprofen (400 mg, Study 1), ketoprofen (50 mg, Study 2) or diclofenac (50 mg, Study 2). Plasma drug concentrations were measured up to 24 h. 3. Magnesium hydroxide increased the area under the plasma ibuprofen concentration-time curve between 0 and 1 h by 65% (P less than 0.05) and the peak concentration of ibuprofen in plasma by 31% (P less than 0.01). The time to peak was shortened by about 0.5 h. The extent of bioavailability of ibuprofen was not increased by magnesium hydroxide. 4. Neither the rate nor the extent of absorption of ketoprofen or diclofenac was changed significantly by magnesium hydroxide. 5. When rapid onset of the analgesic effect of ibuprofen is required, concomitant ingestion of an antacid, which contains magnesium hydroxide without aluminium, is recommended. PMID:2054265

Neuvonen, P J

1991-01-01

411

Simple route for the synthesis of supercapacitive Co-Ni mixed hydroxide thin films  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Novel method for deposition of Co-Ni mixed hydroxide. Black-Right-Pointing-Pointer Nanoparticle network of Co-Ni hydroxide. Black-Right-Pointing-Pointer High specific capacitance of 672 F g{sup -1}. Black-Right-Pointing-Pointer High discharge/charge rates. -- Abstract: Facile synthesis of Co-Ni mixed hydroxides films with interconnected nanoparticles networks through two step route is successfully established. These films have been characterized by X-ray diffraction (XRD), Fourier transform infrared technique (FTIR), scanning electron microscopy (SEM) and wettability test. Co-Ni film formation is confirmed from XRD and FTIR study. SEM shows that the surface of Co-Ni films is composed of interconnected nanoparticles. Contact angle measurement revealed the hydrophilic nature of films which is feasible for the supercapacitor. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance of the Co-Ni mixed hydroxide electrode achieved 672 F g{sup -1}. Impedance analysis shows that Co-Ni mixed hydroxide electrode provides less resistance for the intercalation and de-intercalation of ions. The Co-Ni mixed electrode exhibited good charge/discharge rate at different current densities. The results demonstrated that Co-Ni mixed hydroxide composite is very promising for the next generation high performance electrochemical supercapacitors.

Dubal, D.P. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India) [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India); Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Jagadale, A.D.; Patil, S.V. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India)] [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India); Lokhande, C.D., E-mail: l_chandrakant@yahoo.com [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India)

2012-05-15

412

Lanthanum lead oxide hydroxide nitrates with a nonlinear optical effect.  

PubMed

Two new lanthanum lead oxide hydroxide nitrates with acentric structure, [LaPb8O(OH)10(H2O)](NO3)7 (1) and [LaPb8O(OH)10(H2O)](NO3)7·2H2O (2), have been prepared under subcritical hydrothermal conditions and crystallize in the space groups of Cc and P212121, respectively. The crystal structure of compound 1 consists of the novel [LaPb8O(OH)10(H2O)](7+) clusters regularly arranged along the ab plane with nitrate ions as the counterions around the clusters by Pb-O bonds, developing into a three-dimensional net framework, while the structure of compound 2 is composed of [LaPb8O(OH)10(H2O)](7+) clusters and [NO3](-) groups as the bridging groups, forming a three-dimensional net framework with crystallized water molecules filling in the gaps. The experiments confirmed that compound 1 is the residue of compound 2 after efflorenscence. Besides, the [LaPb8O(OH)10(H2O)](7+) clusters present mirror symmetry in structures of the two compounds. The second-harmonic-generation (SHG) measurements for the two nitrates indicate that the SHG responses for compounds 1 and 2 are 1.3 and 1.1 times that of KH2PO4, respectively. Theoretical calculations confirmed that the SHG efficiency of compounds 1 and 2 mainly arises from the NO3(-) groups in the structure. PMID:25385570

Wang, Genxiang; Luo, Min; Lin, Chensheng; Ye, Ning; Zhou, Yuqiao; Cheng, Wendan

2014-12-01