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We report a novel approach to the instantaneous photoinitiated synthesis of mixed anatase-rutile nanocrystalline TiO2 thin films with a three-dimensional nanostructure through pulsed white light irradiation of photosensitive Ti-organic precursor films. Pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization occurred to form graphitic oxides-coated TiO2 nanograins. Subsequent pulsed light irradiation working as in situ pulsed photothermal treatment improved the crystalline quality of TiO2 film despite its low attenuation of light. The non-radiative recombination of photogenerated electrons and holes in TiO2 nanograins, coupled with inefficient heat dissipation due to low thermal conductivity, produces enough heat to provide the thermodynamic driving force for improving the crystalline quality. The graphitic oxides were reduced by pulsed photothermal treatment and can be completely removed by oxygen plasma cleaning. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides as well as TiO2 nanocrystalline thin films.

We explore the use of poly(N-isopropylacrylamide) (PNIPAm)-grafted carbon microspheres (CM) dispersed in water as a stimulus-responsive lubricant. A critical concentration between 3 and 5 mg/mL of PNIPAm-grafted CM is needed to achieve low friction (coefficient of friction ∼ 0.04) at room temperature between borosilicate and silicon surfaces. An increase in the temperature of the system above the lower critical solution temperature (LCST) causes the aggregation of PNIPAm-grafted CM which leads to an increase in friction forces. The process is not immediately reversible unless the lubricant is sonicated so as to redisperse the aggregates. This work provides insight into the rolling friction mechanism and demonstrates the importance of particle singlets in achieving effective lubrication through a rolling mechanism.

Nanoscale capsule-type particles with stimuli-respondent transport of chemical species into and out of the capsule are of significant technological interest. We describe the facile synthesis, properties, and applications of a temperature-responsive silica-poly( N-isopropylacrylamide) (PNIPAM) composite consisting of hollow silica particles with ordered mesoporous shells and a complete PNIPAM coating layer. These composites start with highly monodisperse, hollow mesoporous silica particles fabricated with precision using a template-driven approach. The particles possess a high specific surface area (1771 m2/g) and large interior voids that are accessible to the exterior environment through pore channels of the silica shell. An exterior PNIPAM coating provides thermoresponsiveness to the composite, acting as a gate to regulate the uptake and release of functional molecules. Uptake and release of a model compound (rhodamine B) occurs at temperatures below the lower critical solution temperature (LCST) of 32 °C, while the dehydrated hydrophobic polymer layer collapses over the particle at temperatures above the LCST, leading to a shutoff of uptake and release. These transitions are also manifest at an oil-water interface, where the polymer-coated hollow particles stabilize oil-in-water emulsions at temperatures below the LCST and destabilize the emulsions at temperatures above the LCST. Cryogenic scanning electron microscopy indicates patchlike particle structures at the oil-water interface of the stabilized emulsions. The silica-PNIPAM composite therefore couples advantages from both the hollow mesoporous silica structure and the thermoresponsive polymer.

The wetting behavior of a surface depends on both its surface chemistry and the characteristics of surface morphology and topography. Adding structure to a flat hydrophobic or oleophobic surface increases the effective contact angle and thus the hydrophobicity or oleophobicity of the surface, as exemplified by the lotus leaf analogy. We describe a simple strategy to introduce micropatterned roughness on surfaces of soft materials, utilizing the template of hexagonally packed pores of breath figures as molds. The generated inverse replicas represent micron scale patterned beadlike protrusions on hydrogel surfaces. This added roughness imparts superoleophobic properties (contact angle of the order of 150° and greater) to an inherently oleophobic flat hydrogel surface, when submerged. The introduced pattern on the hydrogel surface changes morphology as it swells in water to resemble morphologies remarkably analogous to the compound eye. Analysis of the wetting behavior using the Cassie-Baxter approximation leads to estimation of the contact angle in the superoleophobic regime and in agreement with the experimental value.

The carbonization of hydrophilic particle surfaces provides an effective route for tuning particle wettability in the preparation of particle-stabilized emulsions. The wettability of naturally occurring halloysite clay nanotubes (HNT) is successfully tuned by the selective carbonization of the negatively charged external HNT surface. The positively charge chitosan biopolymer binds to the negatively charged external HNT surface by electrostatic attraction and hydrogen bonding, yielding carbonized halloysite nanotubes (CHNT) on pyrolysis in an inert atmosphere. Relative to the native HNT, the oil emulsification ability of the CHNT at intermediate levels of carbonization is significantly enhanced due to the thermodynamically more favorable attachment of the particles at the oil-water interface. Cryogenic scanning electron microscopy (cryo-SEM) imaging reveals that networks of CHNT attach to the oil-water interface with the particles in a side-on orientation. The concepts advanced here can be extended to other inorganic solids and carbon sources for the optimal design of particle-stabilized emulsions.

The effect of electron–phonon interactions on transport properties of 2D materials is unclear. Transport measurements on atomically thin Nb3SiTe6 crystals now show that reduced dimensionality results in the suppression of electron–phonon coupling. It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene1 and the large direct band gaps in MoS2 monolayers2, arise from quantum confinement. However, the influence of reduced dimensions on electron–phonon (e–ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement3,4,5,6,7 is expected to produce a suppression of e–ph interactions in 2D systems with rigid boundary conditions6,7, experimental verification of this has remained elusive8. Here, we show that the e–ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3SiTe6 atomic crystals. When the thickness of the Nb3SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e–ph interactions caused by quantum confinement of phonons.

We report the ability of hydrophobically modified polypeptoids (HMPs), which are amphiphilic pseudopeptidic macromolecules, to connect across lipid bilayers and thus form layered structures on liposomes. The HMPs are obtained by attaching hydrophobic decyl groups at random points along the polypeptoid backbone. Although native polypeptoids (with no hydrophobes) have no effect on liposomal structure, the HMPs remodel the unilamellar liposomes into structures with comparable diameters but with multiple concentric bilayers. The transition from single-bilayer to multiple-bilayer structures is revealed by small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). The spacing between bilayers is found to be relatively uniform at ∼6.7 nm. We suggest that the amphiphilic nature of the HMPs explains the formation of multibilayered liposomes; i.e., the HMPs insert their hydrophobic tails into adjacent bilayers and thereby serve as the connective glue between bilayers. At higher HMP concentrations, the liposomes are entirely disrupted into much smaller micellelike structures through extensive hydrophobe insertion. Interestingly, these small structures can reattach to fresh unilamellar liposomes and self-assemble to form new two-bilayer liposomes. The two-bilayer liposomes in our study are reminiscent of two-bilayer organelles such as the nucleus in eukaryotic cells. The observations have significance in designing new nanoscale drug delivery carriers with multiple drugs on separate lipid bilayers and extending liposome circulation times with entirely biocompatible materials.

Liposomal coatings are formed on films of a biopolymer, hydrophobically modified chitosan (hm-chitosan), containing dodecyl groups as hydrophobes along the polymer backbone. The alkyl groups insert themselves into the liposome bilayer through hydrophobic interactions and thus tether liposomes, leading to a densely packed liposome layer on the film surface. Such liposomal surfaces exhibit effective lubrication properties due to their high degree of hydration, and reduce the coefficient of friction to the biologically-relevant range. The compliancy and robustness of these tethered liposomes allow retention on the film surface upon repeated applications of shear. Such liposome coated films have potential applications in biolubrication.

Water-soluble gold nanoparticles (AuNP) stabilized with cavitands having carboxylic acid groups have been synthesized and characterized by a variety of techniques. Apparently, the COOH groups similar to thiol are able to prevent aggregation of AuNP. These AuNP were stable either as solids or in aqueous solution. Most importantly, these cavitand functionalized AuNP were able to include organic guest molecules in their cavities in aqueous solution. Just like free cavitands (e.g., octa acid), cavitand functionalized AuNP includes guests such as 4,4'-dimethylbenzil and coumarin-1 through capsule formation. The exact structure of the capsular assembly is not known at this stage. Upon excitation there is communication between the excited guest present in the capsule and gold atoms and this results in quenching of phosphorescence from 4,4'-dimethylbenzil and fluorescence from coumarin-1.

A rapid solvothermal method for the fabrication of hexaniobate nanoscrolls in high-yield is reported. Surfactant-containing organic solutions of HxK4−xNb6O17 crystallites treated above 200 °C result in complete conversion to nanoscrolls in 6 h. Both simple nanoscroll structures (SNS) as well as intercalated nanoscrolls (INS) with various surfactants can be readily obtained. Nanoscrolls prepared by this route appear to be more rigid and symmetric compared to those made by standard aqueous methods. Further, on exchange of surface groups, nanoscrolls can be suspended in either hydrophobic or hydrophilic solvents. This approach is significant to bulk nanoscroll production and should be effective in the development of new composite materials.

Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain γ-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r(1) and r(2) relaxivity measurements in water and diethylene glycol (for OH and CH(2) protons) have shown a decrease in the r(2)/r(1) ratio with the particle size reduction, which correlates with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe(3)O(4) with the same particle size, but their r(1) relaxivities are similar. Because the oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor and therefore may be a better prospective imaging agent because of its chemical stability.

The morphology of hollow, double-shelled submicrometer particles is generated through a rapid aerosol-based process. The inner shell is an essentially hydrophobic carbon layer of nanoscale dimension (20 nm), and the outer shell is a hydrophilic silica layer of approximately 40 nm, with the shell thickness being a function of the particle size. The particles are synthesized by exploiting concepts of salt bridging to lock in a surfactant (CTAB) and carbon precursors together with iron species in the interior of a droplet. This deliberate negation of surfactant templating allows a silica shell to form extremely rapidly, sealing in the organic species in the particle interior. Subsequent pyrolysis results in a buildup of internal pressure, forcing carbonaceous species against the silica wall to form an inner shell of carbon. The incorporation of magnetic iron oxide into the shells opens up applications in external stimuli-responsive nanomaterials.

Uniform hard carbon spheres (HCS), synthesized by the hydrothermal decomposition of sucrose followed by pyrolysis, are effective at stabilizing water-in-trichloroethylene (TCE) emulsions. The irreversible adsorption of carbon particles at the TCE-water interface resulting in the formation of a monolayer around the water droplet in the emulsion phase is identified as the key reason for emulsion stability. Cryogenic scanning electron microscopy was used to image the assembly of carbon particles clearly at the TCE-water interface and the formation of bilayers in regions of droplet-droplet contact. The results of this study have potential implications to the subsurface injection of carbon submicrometer particles containing zero-valent iron nanoparticles to treat pools of chlorinated hydrocarbons that are sequestered in fractured bedrock.

We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH4. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH4 with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

A facile aerosol-based process (ABP) is developed to vary the placement of iron nanoparticles on the external surface of carbon microspheres or within the interior. This is accomplished through the competitive mechanisms of sucrose carbonization and the precipitation of soluble iron salts, in an aerosol droplet passing through a high temperature heating zone. At lower aerosolization temperatures, carbonization occurs first leading to iron salt precipitation on the external surface, while at higher temperatures interior placement occurs through concurrent iron salt precipitation and sucrose carbonization. The resulting composites are highly conducive to the reductive dechlorination of compounds such as trichloroethylene (TCE) as the carbon support is a strong adsorbent, and zerovalent iron effectively reduces TCE to innocuous gases such as ethane. Since both iron and carbon are widely used catalysts and catalyst supports, the simple process of modifying iron placement has significant potential applications in heterogeneous catalysis.

Mesoporous SiO(2)/TiO(2)/Fe(2)O(3) particles containing macropores of about 50 nm in diameter have been prepared by an aerosol process using cetyltrimethylammonium bromide (CTAB) as a templating agent. In contrast to the traditional templating effect of CTAB to form ordered mesoporous silicas, the morphology here is vastly different due to the presence of precursor iron salts. The particles have mesoporosity templated by CTAB but additionally have large voids leading to a combined macroporous and mesoporous structure. The morphology is explained through the formation of colloidal structures containing species such as CTA(+)X(-1)Fe(3+) colloids in the aerosol droplets, indicating of a salt bridging effect. This dual porosity has applied implications, as the macropores provide easy entry to the particle interior in potentially diffusion limited situations. Furthermore, the particles encapsulate Fe(2)O(3) and contain TiO(2) leading to the dual functional properties of magnetic response and photocatalytic activity.

The solubilization of phenols in micelles of cetyltrimethyl ammonium bromide leads to microstructural changes from spherical micelles to wormlike micelles and then to vesicles. These microstructures are then used to template silicas. There is a transition from highly ordered hexagonal mesoporous silicas of the M41S family to lamellar structures, as the phenolic dopant concentration is increased. The results have implication to the removal of phenols from aqueous waste streams through the micellar enhanced ultrafiltration process. The entrapment of phenols in mesoporous silicas provides a way to sequester such contaminants in concentrated form.

Hollow silica microspheres encapsulating ferromagnetic iron oxide nanoparticles were synthesized by a surfactant-aided aerosol process and subsequent treatment. The cationic surfactant cetyltrimethyl ammonium bromide (CTAB) played an essential role in directing the structure of the composite. Translation from mesoporous silica particles to hollow particles was a consequence of increased loading of ferric species in the precursor solution and the competitive partitioning of CTAB between silicate and ferric colloids. The hypothesis was that CTAB preferentially adsorbed onto more positively charged ferric colloids under acidic conditions. At a critical Fe/Si ratio, most of the CTAB was adsorbed onto ferric colloids and coagulated the colloids to form larger clusters. During the aerosol process, a silica shell was first formed due to the preferred silicate condensation on the gas-liquid interface of the aerosol droplet. Subsequent drying concentrated the ferric clusters inside the silica shell and resulted in a silica shell/ferric core particle. Thermal treatment of the core shell particle led to encapsulation of a single iron oxide nanoparticle inside each silica hollow microsphere.

We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2–0.3 μm with tubular diameters of ∼50–100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures.

Unimodal and bimodal nanoporous (mesoporous) carbons have been synthesized by simply removing silica from carbon/silica nanocomposites. The sucrose/silica nanocomposites are directly prepared by the sol–gel process of tetraethyl orthosilicate (TEOS) with or without colloidal silica particles in the presence of carbon precursor molecules (i.e., sucrose). Subsequent carbonization converts the sucrose/silica nanocomposites into nonporous carbon/silica composites. Removal of the silica templates results in nanoporous carbons with high surface areas (e.g., >1500 m2/g) and pore volumes (e.g., >1.0 cm3/g). Using TEOS as the only silica source, nanoporous carbons with unimodal ∼2 nm worm-like pores are produced. Nanoporous carbons with bimodal ∼2 and ∼27 nm diameter pores have been prepared by using both the TEOS-derived silica network and the colloidal silica particles as templates.

This paper describes the synthesis of new nanocomposite nanoparticles that consist of polymer coated γ-Fe2O3 superparamagnetic cores and CdSe/ZnS quantum dots (QDs) shell. A single layer of QDs was bound to the surface of thiol-modified magnetic beads through the formation of thiol−metal bonds to form luminescent/magnetic nanocomposite particles. Transmission electron microscopy (TEM) and energy disperse spectroscopy (EDS) were used to characterize the size, size distribution, and composition of the luminescent/magnetic nanoparticles. Their average diameter was 30 nm with a size variation of ±15%. The nanoparticles were modified with carboxylic groups to increase their miscibility in aqueous solution. A 3-fold decrease in the luminescence quantum yield of the luminescent/magnetic particles and a slight blue shift in their emission peaks compared to individual luminescent QDs were observed. However, the particles were bright and were easily observed using a conventional fluorescence microscope. Additionall...

High aspect ratio cadmium sulfide (CdS) quantum rods were synthesized at room temperature in the environment of water-in-oil microemulsions using a combination of two surfactants: the anionic bis(2-ethylhexyl) sulfosuccinate (AOT) and the zwitterionic phospholipid l-α-phosphatidylcholine (lecithin). These highly acicular particles, obtained from a water-in-oil microemulsion containing an equimolar mixture of AOT and lecithin, possess an average width of 4.1 nm ± 0.6 nm, with lengths ranging from 50 to 150 nm. In contrast, conventional spherical CdS quantum dots are obtained from the AOT water-in-oil microemulsion system, with an average particle diameter of 5.0 nm ± 0.6 nm. X-ray and electron diffraction analyses reveal that the quantum dots have the face centered cubic structure of zinc blende, while the quantum rods predominantly have the hexagonal structure of wurtzite. Luminescence spectrophotometry of the samples indicates a blue-shift in the emission spectra when quantum rods are synthesized. It is...

Naturally occurring halloysite clay nanotubes are effective in stabilizing oil-in-water emulsions and can serve as interfacially-active vehicles for delivering oil spill treating agents. Halloysite nanotubes adsorb at the oil-water interface and stabilize oil-in-water emulsions that are stable for months. Cryo-scanning electron microscopy (Cryo-SEM) imaging of the oil-in-water emulsions shows that these nanotubes assemble in a side-on orientation at the oil-water interface and form networks on the interface through end-to-end linkages. For application in the treatment of marine oil spills, halloysite nanotubes were successfully loaded with surfactants and utilized as an interfacially-active vehicle for the delivery of surfactant cargo. The adsorption of surfactant molecules at the interface serves to lower the interfacial tension while the adsorption of particles provides a steric barrier to drop coalescence. Pendant drop tensiometry was used to characterize the dynamic reduction in interfacial tension resulting from the release of dioctyl sulfosuccinate sodium salt (DOSS) from halloysite nanotubes. At appropriate surfactant compositions and loadings in halloysite nanotubes, the crude oil-saline water interfacial tension is effectively lowered to levels appropriate for the dispersion of oil. This work indicates a novel concept of integrating particle stabilization of emulsions together with the release of chemical surfactants from the particles for the development of an alternative, cheaper, and environmentally-benign technology for oil spill remediation.

A room-temperature electrochemical approach to synthesizing anisotropic platelike copper microcrystals and nanocrystals in the presence of potassium bromide is presented. Morphological and elemental characterization was performed using SEM, TEM, and XRD to confirm the anisotropic morphology and crystal structure of the synthesized copper particles. A possible mechanism for explaining the anisotropic crystal growth is proposed on the basis of the preferential adsorption of bromide ions to selective crystal faces. The shape-dependent electrocatalytic property of copper particles is demonstrated by its enhanced catalytic activity for methanol oxidation. Further development of such anisotropic copper particles localized on an electrode surface will lead us to find a suitable alternative for noble metal-based electrocatalysts for the methanol oxidation reaction relevant to fuel cells.

Dynamic magnetic properties of spins from Mn ions doped in semiconductor nanocrystals (Cd1−xMnxSe) have been studied using an electron paramagnetic resonance method based on two different crystalline sizes and a series of Mn concentrations. By decreasing the size of the quantum dots, the electron spin-nuclear spin interactions are reduced due to enhanced magnetic interactions between Mn ions. A linewidth analysis was also carried out, showing longer spin relaxation times and supporting the enhancement of spin coherence. We suggest that the enhancement of Mn–Mn interactions results from the quantized electrons which have longer coherence length in quantum dots. Quantum size effects may benefit to control and manipulation of spins in a semiconductor nanocrystalline system in which the magnetic ions are incorporated.

A dual-lipid liposome system consisting of a phospholipid and a skin ceramide extruded though a 100 nm membrane yields novel tubular and helical liposomes. These liposomes were used as templates to generate highly aspherical silica nanocapsules with length to diameter aspect ratios exceeding 10. Many of these nanocapsules have the morphology of a bulbous end attached to a long tip, mimicking microneedles attached to a reservoir. The fidelity of helical liposomes is transcribed to the silicas and the long tips indicate helically entwined left-handed silica structures. The silica coating is expected to protect and stabilize the internal contents of the liposomes, as well as enable surface functionalization for applications in drug or targeted delivery.

SnO(2) has successfully been doped into octahedral In(2)O(3) nanoparticles using a high-temperature nonaqueous reaction. The resultant ITO nanoparticles exhibit a particle/crystal decrease in size, sphericity in morphology, and enhancement in photoluminescence.

Nonspherical liposomes were prepared by doping L-alpha-phosphatidylcholine (PC) with ceramide VI (a skin lipid). Cryo-transmission electron microscopy shows the liposome shape changing from spherical to an undulating tubular morphology, when the amount of ceramide VI is increased. The formation of tubular liposomes is energetically favorable and is attributed to the association of ceramide VI with PC creating regions of lower curvature. Since ceramides are the major component of skin lipids in the stratum corneum, tubular liposomes containing ceramide may potentially serve as self-enhanced nanocarriers for transdermal delivery.

The aerosol OT/ L-alpha-phosphatidylcholine/isooctane/water system forms a rigid mesophase that transitions from reverse hexagonal to multilamellar in structure at specific water contents. This study shows that characteristics of ordered liquid-crystalline mesophases can be distinguished and imaged in high clarity using cryo-field emission scanning electron microscopy (cryo-FESEM). The reverse hexagonal phase consists of bundles of long cylinders, some with length scales of over 2 microm, that are randomly oriented as part of a larger domain. Cryo-imaging allows the visualization of the intercylinder spacings and the details of transitions from one domain to another. The multilamellar structured mesophase consists of spherical vesicles of 100 nm to 10 microm in diameter, with intervening noncrystalline isotropic regions. Coexistence regions containing both the reverse hexagonal and lamellar structures are also observed in the transition from the reverse hexagonal to the lamellar phase. These results complement and qualitatively verify our earlier studies with small-angle neutron scattering, high-field nuclear magnetic resonance spectroscopy, and freeze-fracture direct imaging transmission electron microscopy. The information is useful in understanding materials templating in these rigid systems.

Polystyrene-coated ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ nanoparticles through surface engineering exhibit an intergranular tunneling magnetoresistance (MR) ratio of 22.8% at room temperature and a maximum MR of 40.9% at $110\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The drastic enhancement of the MR ratio clearly suggests that there is high degree of spin polarization even at room temperature for half metallic ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$. The estimated spin polarization $P$ is about 54% and 83% at room temperature and $110\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, respectively.

V-shaped rutile twinned nanorods (VRTNs) with different aspect ratios were synthesized on large scale using a one-pot organic solvothermal method. Although several different types of VRTNs were produced, (101) twinned nanorods were the major product with minor amounts of (301) twins and straight nanorods. STEM, TEM and XRD characterizations show that [001] is the growth direction of VRTNs, with surfaces dominated by {110} facets. Intermediate formation of both brookite and anatase nanorods provides dual pathways to VRTNs' growth: one path in which anatase seeds trigger and promote brookite nanorod growth; and a second path in which anatase nanorods are formed by oriented attachment. Subsequent dissolution of both brookite and anatase nanorods provides titania to support VRTNs growth.

The gelation of hydrophobically modified chitosan solutions can be accomplished through the incorporation of uniform carbon microspheres. The carbon particles act as nodes in the gel network where hydrophobic alkyl groups, attached to the polysaccharide backbone, interact with multiple carbon microspheres to form a three-dimensional matrix. Rheological characterizations show significant increases in elastic moduli upon incorporation of the carbon microspheres.

Magnetotransport of Fe 3 O 4 -hexabromobenzene ( C 6 Br 6 ) composite has been studied. Powders of C 6 Br 6 and Fe 2 O 3 nanoparticles were mixed together. They were annealed in hydrogen flow. There was a phase transformation from Fe 2 O 3 to Fe 3 O 4 after annealing. Giant negative magnetoresistance(MR) was observed at room temperature and the MR ratio is about 13.4% in an applied field of 5 T. The maximum MR ratio is 21.5% at 130 K. The temperature dependence of the resistivity exhibits characteristics of intergranular tunneling in the samples. The enhancement of the MR ratio is attributed to the fact that the C 6 Br 6 can act as barrier material and, more importantly, can prevent the oxidation of the surface of Fe 3 O 4 , which is believed to alter the half-metallic state at the surface.

CoFe2O4 nanoparticles prepared by chemical coprecipitation method in a magnetic field exhibit novel magnetic properties. The average particle diameter was about 2 nm and larger depending on the post annealing temperature. Magnetization measurements indicate that smaller nanoparticles are superparamagnetic above their respective blocking temperatures. In the blocked state, these nanoparticles exhibit interesting behaviors in the magnetic hysteresis measurements. Constricted, or wasp waisted with extremely narrow waist, hysteresis curves have been observed in the magnetization versus field sweeps. For larger nanoparticles, the room temperature hysteresis is typical of a ferromagnet with an open loop, but the loop closes at lower temperature. The novel magnetic behavior is attributed to the directional order of Co ions and vacancies in CoFe2O4 established during the coprecipitation of the nanoparticles under an applied field.

We have observed an appearance of clear morphological structure in composites containing In2O3 nanocrystals (NCs) incorporated into polymethyl methacrylite (PMMA) matrices under optical treatment by a polarized femtosecond laser. The initial photoinduced treatment was carried out using a Ti:sapphire femtosecond laser emitting 140 fs p-polarized light at a maximum spectral wavelength 775 nm with pulse repetition 1 kHz. It was found that the average morphological radius is varied maximally only during illumination at liquid helium temperature (T = 4.2 K). The morphological average mean radius is strictly dependent on the sizes of incorporated In2O3 NCs. Afterwards we measured the linear electrooptic effect at cw He–Ne laser wavelength 633 nm during simultaneous treatment by 1060 and 530 nm coherent beams of a Nd–YAG picosecond laser. We have established that a decrease of the average morphological mean radius favours an increase of the optically poled linear electrooptic coefficient. The diameters of In2O3 NCs were evaluated using transmission electron microscopy (TEM) and light-scattering techniques, whereas the NC sizes and morphological average mean radius of formed nanocomposites were estimated by atomic force microscopy (AFM). A relationship between the diameter of the NC, composite morphological mean average radius and effective linear electrooptic coefficient was established. (Some figures in this article are in colour only in the electronic version)

A series of (Co50Fe50)x-(Al2O3)1−x cermet granular thin films deposited on glass substrates by dual electron beam evaporation was studied for their structural, magnetotransport, and magnetic properties. Upon varying the magnetic volume fraction, x, from 0.07 to 0.52 the percolation threshold (xc) was determined from resistivity measurements to be ∼0.17. This value agrees well with the theoretical prediction for a three-dimensional system of spherical particles. Values of the isotropic tunneling magnetoresistance (TMR) as high as 10% at room temperature were found for films with x