scholarly journals Influence of Capping Groups on the Synthesis of γ-Fe2O3 Nanocrystals

2004 ◽  
Vol 19 (4) ◽  
pp. 1208-1215 ◽  
Author(s):  
Ming Yin ◽  
Amanda Willis ◽  
Franz Redl ◽  
Nicholas J. Turro ◽  
Stephen P. O’Brien
Keyword(s):  
Self Assembly ◽  
Carbon Chain ◽  
Iron Pentacarbonyl ◽  
Decomposition Temperature ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Nonpolar Solvents ◽  
Transmission Electron ◽  
Iron Precursor ◽  
Chain Lengths

Monodisperse and uniform γ-Fe2O3 (maghemite) nanocrystals of variable size were prepared by thermal decomposition of iron pentacarbonyl [Fe(CO)5] in the presence of surfactants, following controlled oxidation with trimethylamine N-oxide as a mild oxidant. The influence of carboxylic acids with variable alkyl carbon chain lengths on the synthesis of γ-Fe2O3 nanocrystals was investigated. The effect of the molar ratios of surfactant to iron precursor was also studied. The nanocrystals were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD showed the particles were highly crystalline at the nanometer scale. The results showed that the size and shape of the nanocrystal is strongly influenced by the decomposition temperature of iron pentacarbonyl and closely related to the length of carbon chain of the capping groups and the molar ratio of surfactant to iron precursor. Following controlled evaporation from nonpolar solvents, self-assembly into two-dimensional arrays could be observed by TEM. It was also found that the distance between the nanocrystals in self-assembled structures matched the length of the capping molecules very well.

Wüstite nanocrystals: Synthesis, structure and superlattice formation

2007 ◽  
Vol 22 (7) ◽  
pp. 1987-1995 ◽  
Author(s):  
Ming Yin ◽  
Zhuoying Chen ◽  
Brian Deegan ◽  
Stephen O’Brien
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Size Control ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Salt Crystal ◽  
Uniform Size ◽  
Nonpolar Solvents ◽  
Transmission Electron ◽  
State Kinetic

Monodisperse ligand-capped cubic wüstite FexO nanocrystals were prepared by a novel thermal decomposition method of iron (II) acetate in the presence of oleic acid as the surfactant. Controlled size distributions of cubic nanoparticles possessing the rock salt crystal structure were isolated in the range 10–18 nm. The influence of molar ratio of surfactant to precursor was investigated to understand size control and monodispersity. Using inexpensive, nontoxic metal salts as reactants, we were able to synthesize gram-scale quantities of relatively monodisperse nanocrystals in a single reaction, without further size selection, characterized by x-ray diffraction and transmission electron microscopy. The procedure enables the collection of samples of uniform size as a function of time, thus permitting a preliminary solid-state kinetic analysis of the reaction as a function of increasing particle size. Following controlled evaporation from nonpolar solvents, self-assembly into two-dimensional arrays, three-dimensional single-component superlattices, and binary superlattices with gold nanoparticles were observed and characterized.

scholarly journals PAN Nanofibers Reinforced with MMT/GO Hybrid Nanofillers

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Qingqing Wang ◽  
Guohui Li ◽  
Jinning Zhang ◽  
Fenglin Huang ◽  
Keyu Lu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Self Assembly ◽  
Decomposition Temperature ◽  
Electrospinning Process ◽  
Test Machine ◽  
Force Microscopy ◽  
Noticeable Increase ◽  
Atomic Force ◽  
Transmission Electron

Single component nanofiller has shown some limitations in its performance, which can be overcome by hybrid nanofillers with two different components. In this work, montmorillonite (MMT)/graphene oxide (GO) hybrid nanofillers were formed by self-assembly and then incorporated into the polyacrylonitrile (PAN) nanofibers by electrospinning process. X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) were utilized to analyze the structures of MMT/GO hybrid nanofillers. And the effects of MMT/GO hybrid nanofillers on the morphology, thermal stability, and mechanical properties of PAN/MMT/GO composite nanofibrous membrane were examined by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and tensile test machine, respectively. The incorporation of MMT/GO hybrid nanofillers into PAN nanofibers showed a noticeable increase up to 30°C for the onset decomposition temperature and 1.32 times larger tensile strength than the pure PAN, indicating that the hybrid nanofiller is a promising candidate in improving thermal and mechanical properties of polymers.

scholarly journals Liquid petroleum gas sensing performance enhanced by CuO modification of nanocrystalline ZnO-TiO2

2016 ◽  
Vol 34 (3) ◽  
pp. 571-581
Author(s):  
R.B. Pedhekar ◽  
F.C. Raghuwanshi ◽  
V.D. Kapse
Keyword(s):  
Thick Film ◽  
Gas Sensing ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Liquid Petroleum Gas ◽  
Synthesized Materials ◽  
Sensing Characteristics

AbstractNanocrystalline ZnO-TiO2 (with molar ratios 9:1, 7:3, 1:1, 3:7 and 1:9) were successfully synthesized by hydrothermal method. Synthesized materials were examined with the help of X-ray diffraction and transmission electron microscope. Liquid petroleum gas sensing characteristics of the ZnO-TiO2 films were investigated at different operating temperatures. The ZnO-TiO2 thick film (with 1:1 molar ratio) exhibited good response toward liquid petroleum gas as compared to other investigated compositions. Further, liquid petroleum gas sensing characteristics of CuO modified ZnO-TiO2 thick films were investigated. 0.2 M CuO modified ZnO-TiO2 thick film exhibited excellent liquid petroleum gas sensing characteristics such as higher response (~ 1637.49 at 185 °C) with quick response time (~30 s), low recovery time (~70 s), excellent repeatability and stability at low operating temperature.

STM STUDY OF A SELF-ASSEMBLY BEHAVIOR OF PHTHALOCYANINE AND 1-BROMOHEXADECANE ON HIGHLY ORIENTED PYROLYTIC GRAPHITE

2006 ◽  
Vol 05 (06) ◽  
pp. 877-882
Author(s):  
WU YANG ◽  
WEILIAN LV ◽  
LILI BO ◽  
XIAOYAN HE ◽  
GANG NI ◽  
...  
Keyword(s):  
Self Assembly ◽  
Substrate Surface ◽  
Pyrolytic Graphite ◽  
Molar Ratio ◽  
Highly Oriented Pyrolytic Graphite ◽  
Molar Ratios ◽  
Molecular Features ◽  
Planar Molecules ◽  
Assembly Behavior ◽  
Stm Images

In this paper, we present the results of using alkane derivatives to assist in the adsorption of planar molecules by employing 1-bromohexadecane( C 16 Br ) and phthalocyanine (Pc) as examples. Their assembly behaviors have been well resolved on the observed STM images. The observations presented in this work demonstrate that single molecular arrays of Pc can be obtained with a template of C 16 Br on highly oriented pyrolytic graphite (HOPG) substrate surface to allow high-resolution STM studies. Binary mixtures of different molar ratios were also observed. By adjusting the molar ratio of Pc to C 16 Br to about 1:3–1:4, uniform assembly can become dominative on the surface. The resulting high stability and the well ordered assembly are attributed to the increased adsorption barrier of alkanes. This approach could be adapted to the studies of other molecules to observe molecular features and could be helpful in obtaining two-dimensional assemblies of monodispersed molecules, especially planar molecules.

scholarly journals Amphiphilic Antimony(V) Complexes for Oral Treatment of Visceral Leishmaniasis

2013 ◽  
Vol 57 (9) ◽  
pp. 4229-4236 ◽  
Author(s):  
Flaviana R. Fernandes ◽  
Weverson A. Ferreira ◽  
Mariana A. Campos ◽  
Guilherme S. Ramos ◽  
Kelly C. Kato ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Oral Treatment ◽  
Carbon Chain ◽  
Oral Route ◽  
Control Group ◽  
Pharmacokinetic Studies ◽  
Content Type ◽  
Transmission Electron ◽  
Parasitic Load ◽  
Chain Lengths

ABSTRACTThe need for daily parenteral administration is an important limitation in the clinical use of pentavalent antimonial drugs against leishmaniasis. In this study, amphiphilic antimony(V) complexes were prepared from alkylmethylglucamides (L8 and L10, with carbon chain lengths of 8 and 10, respectively), and their potential for the oral treatment of visceral leishmaniasis (VL) was evaluated. Complexes of Sb and ligand at 1:3 (SbL8 and SbL10) were obtained from the reaction of antimony(V) with L8 and L10, as evidenced by elemental and electrospray ionization-tandem mass spectrometry (ESI-MS) analyses. Fluorescence probing of hydrophobic environment and negative-staining transmission electron microscopy showed that SbL8 forms kinetically stabilized nanoassemblies in water. Pharmacokinetic studies with mice in which the compound was administered by the oral route at 200 mg of Sb/kg of body weight indicated that the SbL8 complex promoted greater and more sustained Sb levels in serum and liver than the levels obtained for the conventional antimonial drug meglumine antimoniate (Glucantime [Glu]). The efficacy of SbL8 and SbL10 administered by the oral route was evaluated in BALB/c mice infected withLeishmania infantumafter a daily dose of 200 mg of Sb/kg for 20 days. Both complexes promoted significant reduction in the liver and spleen parasite burdens in relation to those in the saline-treated control group. The extent of parasite suppression (>99.96%) was similar to that achieved after Glu given intraperitoneally at 80 mg of Sb/kg/day. As expected, there was no significant reduction in the parasitic load in the group treated orally with Glu at 200 mg of Sb/(kg day). In conclusion, amphiphilic antimony(V) complexes emerge as an innovative and promising strategy for the oral treatment of VL.

Preparation of TiO2/CNTs Nanocomposite and its Photocatalytic Activity for Methyl Orange in Aqueous Solutions

2011 ◽  
Vol 130-134 ◽  
pp. 1539-1543
Author(s):  
Xuan Hui Zhang ◽  
Su Juan Hu ◽  
Shao Ping Tong ◽  
Yuan Cheng ◽  
Dan Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Aqueous Solutions ◽  
Average Diameter ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Hydrolysis Method ◽  
Transmission Electron ◽  
Supernatant Liquid

TiO2/CNTs nanocomposites with different Ti/C molar ratios were prepared by a sol-hydrolysis method at 368 K, using titanium tetrachloride as a precursor and nitrified carbon nanotubes as a support. The crystal phase, morphology and microstructure of the sample were characterized by X-ray Diffraction (XRD) and High-Resolution Transmission Electron Microscope (HRTEM). The photocatalytic activity of the samples was performed by methyl orange in aqueous solutions under UV light.The supernatant liquid of methyl orange during degradation was determined by using an UV-vis spectrophotometer (UV-vis). XRD results show that the crystal phases of the sample are composed of carbon nanotubes, anatase and rutile. HRTEM results show that the average diameter of oval titania is about 4.2 nm, and it decorates on the surface of carbon nanotubes uniformly. UV-vis results show that the photocatalytic activity of the TiO2/CNTs nanocomposite with the optimum Ti/C molar ratio is much higher than that of P25. These results indicate that a synergistic effect exists between titania and carbon nanotubes in the nanocomposite.

The Effect of Zinc to Aluminium Molar Ratio on the Physico-Chemical Properties of Zinc-Aluminium-3,4-Dichlorophenoxy Acetate Nanocomposite

2013 ◽  
Vol 756 ◽  
pp. 127-134
Author(s):  
Sheikh Ahmad Izaddin Sheikh Mohd Ghazali ◽  
Mohd Zobir Hussein ◽  
Siti Halimah Sarijo
Keyword(s):  
Layered Double Hydroxide ◽  
Mole Fraction ◽  
Self Assembly ◽  
Chemical Properties ◽  
Zinc Ion ◽  
Molar Ratio ◽  
Basal Spacing ◽  
Molar Ratios ◽  
Assembly Method ◽  
Double Hydroxide

Layered double hydroxide (LDH) hybrid materials of Zn-Al-layered double hydroxide-3,4-dichlorophenoxy acetate acidnanocomposites (ZADs) were prepared by direct self-assembly method. The pH of the solution was adjusted to 7.5 using 2M NaOH. Various Zn2+ to Al3+ molar ratios, R ranging from 1 to 6 were used with a fixed concentration of 3,4-D at 0.3 M. The Powder X-ray diffraction (PXRD) patterns showed the formation of well-ordered nanocomposite with the expansion of basal spacing from 8.9 Å in the Zinc-Aluminium-Layered Double Hydroxide (ZAL) to 18.7 - 22.1 Å in the resulting nanocomposites. The Fourier transform infrared (FTIR)spectra for the nanocomposites showed features for both ZAL and ZAD, showing the successful intercalation of the organic moiety into the LDH interlayer. The percentage loading of 3,4-dichlorophenoxy acetati acid(3,4-D) in LDH was found to be increased from 34.7-48.1 % (w/w), as the mole fraction of Al decreased from 0.44-0.15. This study shows that the mole fraction of zinc ion was replaced by aluminium ion in the LDH plays an important role in controlling the physic-chemical properties of the resulting material.

Convenient Route to Cu-Ag Bimetallic Nanoleaflets with High Content of Cu and their Electrochemical Properties

2017 ◽  
Vol 727 ◽  
pp. 395-402
Author(s):  
Zi Run Wang ◽  
Xin Liu ◽  
Gui Qi Xie ◽  
Yi Wu ◽  
Ming Nie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Reduction Method ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Phase Reduction ◽  
Transmission Electron ◽  
Convenient Route

Cu-Ag alloy nanoparticles were synthesized by a liquid phase reduction method. Using sodium formaldehyde sulfoxylate (SFS) as reducing agents, copper-silver bimetallic nanoleaflets with high content of Cu were prepared. The obtained Cu-Ag bimetallic nanocrystal were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM) and transmission electron microscopy (TEM). Different molar ratio of Cu-Ag bimetallic nanomaterials could produce different morphologies. The surfactant β-CD plays a crucial role on the structure of the products. The different molar ratios of Cu-Ag were also investigated. The electrochemical activity was evaluated using cyclic voltammetry (CV), electrochemical hydrogen evolution reaction (HER) in a 0.5M Na2SO4 electrolyte.

scholarly journals Stimuli-Responsive Nucleotide–Amino Acid Hybrid Supramolecular Hydrogels

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 146
Author(s):  
Matthew Mulvee ◽  
Natasa Vasiljevic ◽  
Stephen Mann ◽  
Avinash J. Patil
Keyword(s):  
Mechanical Properties ◽  
Amino Acid ◽  
Self Assembly ◽  
Soft Materials ◽  
Guanosine Monophosphate ◽  
Molar Ratio ◽  
Stimuli Responsive ◽  
Molar Ratios ◽  
Hybrid Hydrogels ◽  
Guanine Residue

The ability to assemble chemically different gelator molecules into complex supramolecular hydrogels provides excellent opportunities to construct functional soft materials. Herein, we demonstrate the formation of hybrid nucleotide–amino acid supramolecular hydrogels. These are generated by the silver ion (Ag+)-triggered formation of silver–guanosine monophosphate (GMP) dimers, which undergo self-assembly through non-covalent interactions to produce nanofilaments. This process results in a concomitant pH reduction due to the abstraction of a proton from the guanine residue, which triggers the in situ gelation of a pH-sensitive amino acid, N-fluorenylmethyloxycarbonyl tyrosine (FY), to form nucleotide–amino acid hybrid hydrogels. Alterations in the supramolecular structures due to changes in the assembly process are observed, with the molar ratio of Ag:GMP:FY affecting the assembly kinetics, and the resulting supramolecular organisation and mechanical properties of the hydrogels. Higher Ag:GMP stoichiometries result in almost instantaneous gelation with non-orthogonal assembly of the gelators, while at lower molar ratios, orthogonal assembly is observed. Significantly, by increasing the pH as an external stimulus, nanofilaments comprising FY can be selectively disassembled from the hybrid hydrogels. Our results demonstrate a simple approach for the construction of multicomponent stimuli-responsive supramolecular hydrogels with adaptable network and mechanical properties.

One-pot Preparation of Cu2(OH)3NO3 Nanosheets and Cu(OH)2 Nanowires

2019 ◽  
Vol 9 (4) ◽  
pp. 467-471
Author(s):  
Wenzhe Zhang ◽  
Ailing Yang ◽  
Xichang Bao
Keyword(s):  
Crystal Structures ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
One Pot ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Reaction Solution ◽  
Cuo Nanosheets

Introduction: By using Cu(NO3)2 as precursor and polyvinylpyrrolidone (PVP) as surfactant, nanosheets of Cu2(OH)3NO3, nanowires of Cu(OH)2 or the mixture of the two were prepared under different molar ratios of OH− to Cu2+. Materials and Methods: The crystal structures and morphologies of the products were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). Results: When the molar ratio of OH− to Cu2+ in reaction solution is lower than 1.28, pure Cu2(OH)3NO3 nanosheets were obtained. The thickness of one piece of nanosheet is about 167 nm. The Cu2(OH)3NO3 nanosheets consists of two types of crystal structures, monoclinic phase and orthorhombic phase. With increase of the molar ratio of OH− to Cu2+, the monoclinic phase of Cu2(OH)3NO3 was transferred to the orthorhombic phase of Cu2(OH)3NO3. When the molar ratio of OH− to Cu2+ is within 1.28-2.24, the product is the mixture of Cu2(OH)3NO3 nanosheets and Cu(OH)2 nanowires. And when this molar ratio is higher than 2.24, only Cu(OH)2 nanowires were produced. The lengths and the diameters of the Cu(OH)2 nanowires are in the region of 50-250 nm and 10 nm, respectively. Conclusion: The reason of the Cu2(OH)3NO3 nanosheets changing into the Cu(OH)2 nanowires is that the OH− anions replace the NO3 − anions in the layered Cu2(OH)3NO3 nanosheets, which causes the rupture of hydrogen bonds connecting the adjacent layers. The Cu(OH)2 nanowires were not stable and found to become spindled CuO nanosheets in air at room temperature.

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