Twin screw extrusion is the preferred process to commercially produce nanocomposites by compounding the nanoparticles and polymer melts. Polymer nanocomposites, which contain nanoparticles dispersed in a polymer matrix, provide improved proper-ties at low filler loadings. Nanoalumina particles recently have been used as fillers to polymer matrix that contributed enhanced physical properties of nanocomposites. Recently, concerns had been expressed that airborne nanoparticles particularly of nanoalumina. released during compounding might present serious contamination of the air in the workplace. Researchers with experience in environmental health and polymer manufacturing monitored the compounding process for a model nanoalumina-containing nanocomposite using a TSI Fast Mobility Particle Spectrometer (FMPS). FMPS measurements were taken at background locations, source locations, and operators' breathing zones; in parallel to the FMPS real time measurement, airborne nanoparticles were collected using polycarbonate filters fitted with filmed grids driven by a personal air sampling pump. Filter samples were analyzed for particle morphology and elemental composition. It was found that the nanoparticle number concentration was elevated during processing. The released nanoparticles are a complex mixture of the individual nanoalumina particles, agglomerates of those particles, polymer fume particles, and perhaps others.

Abstract. Amblypygi is a small order of arachnids that includes the whip spiders. Like other members of the clade Pedipalpi, these arachnids are cryptic predators that use their antenniform appendages to detect prey, and spinose pedipalps for quick prey capture. To date, there is very little information on the composition of their exoskeleton despite its importance in predation and defense. Here, we performed the first analysis of a whip spider exoskeleton using energy-dispersive X-ray spectroscopy (SEM-EDS). Our studies of Phrynus marginemaculatus CL Koch, 1840 were designed to (1) determine if elemental profiles differ between instars and (2) determine if and how elemental profiles of whip spiders differ from other closely related arachnids. We found the whip spider exoskeleton to contain several trace metal elements including calcium, magnesium, manganese, potassium, sodium, and zinc. The diversity and abundance of trace elements is relatively low throughout the exoskeleton of 2nd instars but increases in adults. In particular, the chelicerae and pedipalps are well reinforced with several metal elements, most notably calcium and zinc, which are also present in the tarsal claws. A similar elemental distribution is known for adult whip scorpions (Thelyphonida). In P. marginemaculatus, these metal elements are similarly present in adult exuviae. The elemental enrichment of the whip spider exoskeleton is comparable to that present in other members of the Pedipalpi and Tetrapulmonata, reflecting a relatively conserved profile for the few species that have been examined.

Three species of adult hard tick (Ixodidae) were examined with scanning electron microscopy-energy dispersive X-ray spectroscopy to obtain elemental profiles of their exoskeletons and determine the presence of trace elements. The scutum, tarsal claws, chelicerae, and hypostome were examined on females and males of Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis. The only trace elements present included chlorine, calcium, and sodium. Chlorine was the most abundant trace element and occurred in all examined regions. The chelicerae generally possessed the highest weight percentages of Cl (up to 11.32 ± 1.36%) across all 3 species, although high weight percentages of Cl (up to 8.78 ± 2.77%) were also present in the hypostome teeth of most specimens. All 3 trace elements were present in the hypostome of A. americanum and I. scapularis, but Ca and Na appear to be absent from the teeth of D. variabilis. In general, there were few differences in the elemental profiles of the exoskeletons between the sexes of any species. This study confirms the presence of alkali metals (Na) and alkaline earth metals (Ca) in adult ticks, which are also common in other arachnids; however, the absence of transition metals such as zinc from the exoskeletons of ticks is uncommon and only shared with species of Ricinulei and Opiliones.

Ring-functionalized semiconducting polythiophene dots (Pdots) were synthesized rapidly and in one step by the hydrazine hydrate reduction of doped parent polythiophene, obtained by conventional chemical oxidation of thiophene monomer by FeCl3 in anhydrous acetonitrile. Dispersions of these Pdots display robust (pseudo) solvatochromism and solvatofluorism. Polythiophene Pdots exhibit significant cytotoxicity towards prostate cancer cells (expected) although when injected subcutaneously in vivo in live mouse, no toxicity is observed for 24 days when monitored in real time using fluorescence imaging.

We studied the effective contact potential difference (ECPD) of thin film nanostructures and its role in self-powered X-ray sensors, which use the high-energy current detection scheme. We compared the response to kilovoltage X-rays of several nanostructures made of disparate combinations of conductors (Al, Cu, Ta, ITO) and oxides (SiO2, Ta2O5, Al2O3). We measured current-voltage curves in parallel-plate configuration separated by an air gap and determined three characteristic parameters: current at zero voltage bias I0, the voltage offset for zero current ECPD, and saturation current Isat. We found that the metals' ECPD values measured with our technique were higher than the CPD values measured with photoelectron spectroscopy in situ, i.e., no air contact. These differences are related to natural oxidization and to the presence of photo-/Auger-electron current leaking from the high-Z toward the low-Z electrode, as suggested by additional experiments carried out in vacuum. Further, the deposition of the 40-500 nm oxide layer on the surface of metallic substrates strongly affects their contact potential. This technique exploits ionization and charge carrier transport in both solid insulators and in air, and it opens the possibility of measuring the ECPD between metals separated by a solid insulator in a metal-insulator-metal (MIM) configuration. Additionally, we demonstrated that certain configurations of MIM structures are suitable for X-ray detection in self-powered mode.

Arthropods are well known to biomineralize and metallize their exoskeletons with naturally occurring elements that function to stabilize the protein component and add hardness to surfaces that endure wear. In this study, we provide the first description of the trace elements in the cuticle of a marine intertidal pseudoscorpion, Halobisium occidentale, using energy-dispersive x-ray spectroscopy. We characterized the trace element composition of six regions on four specimens: the prosoma, opisthosoma, tarsal claws, arolia, chelicerae, and pedipalps. In addition to the elements C, O, and N that make up the -chitin component of the cuticle, we found 11 trace elements across the body, but only five of these elements were present at significant levels (1%wt): Ni, P, Al, Zn, and Fe. The only trace element on both tagmata is P, while the appendages and their structures contain varying amounts of other elements. The tarsal claws are supplemented with Zn and Ni, while the adhesive arolia contain either Ni or P. The pedipalps are enriched with Al along their proximodistal axis, with P, Zn, and Fe present only around the venom pore. The chelicerae have P, Zn, and Fe present only on the distal regions. This study confirms that pseudoscorpions, like many other arthropods, enrich their cuticle with specific elements at precise locations that are important in predation (cheliceral fingers, pedipalps, venom pore) and locomotion (tarsal claws, arolia). This is also the first study to reveal the presence of Al and Ni in any significant quantities in the arthropod exoskeleton.

We describe a simple and general approach to conjugate nanoparticles on pristine graphene. The method takes advantage of the high reactivity of perfluorophenyl nitrene towards the C[double bond, length as m-dash]C bonds in graphene, where perfluorophenyl azide-functionalized nanoparticles are conjugated to pristine graphene through the [2+1] cycloaddition reaction by a fast photoactivation.

Airborne nanoparticles released during the synthesis of single-walled and multi-walled carbon nanotubes were measured and characterized. This study reported the field measurements during the development of carbon nanotube production. Monitoring data were taken and the sampling methods to characterize aerosol release were developed along with the modification of carbon nanotube production in a time period from 2006 to 2009. Particle number concentrations for diameters from 5 nm to 20 microm were measured using the fast mobility particle sizer and the aerodynamic particle sizer; the particles released from the furnace were found to be less than 500 nm in diameter. The morphology and elemental composition of the released nanoparticles were characterized by scanning and transmission electron microscopy and energy dispersive spectroscopy. Different operating conditions of multi-walled carbon nanotubes (MWCNT) production were studied to evaluate their effects on the number and morphology of aerosol particles, and the number of particles released. Carbon nanotube filaments and carbon particles in clusters were found among the released aerosol particles during production of multiwalled carbon nanotubes.

The microstructure and composition of a nanosized Co catalyst supported on alpha-alumina prior to and after the auto-thermal reformation were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The support of the fresh catalyst exhibits a homogenous aggregation of amorphous granules with sizes ranging between 10 to 40 nm. The crystalline structure of the fresh catalyst support is of hexagonal alumina phase. Cobalt in the fresh catalyst is highly dispersed and embedded in the matrix in the form of contrasted but faceted crystallites with size in the range of 5 - 10 nm. The support of the used catalyst exhibits external coating made of carbon related compound, but show very little grain growth. Co particles in the reformed sample were found to be in the mooted but non-faceted form. Crystallographic information in relation to this auto-thermal reformation of alpha-alumina supported Co nanoparticles has been discussed in the light of the efficiency of Co as catalyst.

In this paper, we report the synthesis of stilbene-based fluorophore, 3,4-dihydroxy-4′-aminostilbene (DHAS) for the detection of chemical warfare agents such as organophosphorus nerve gases. DHAS was characterized by various spectroscopic methods and grafted on to electrospun nanofibers. The interaction of DHAS with nerve agents simulant, diethyl chlorophosphate (DCP) was investigated in solution and vapor phase by fluorescence spectroscopy.

Manual handling of nanoparticles is a fundamental task of most nanomaterial research; such handling may expose workers to ultrafine or nanoparticles. Recent studies confirm that exposures to ultrafine or nanoparticles produce adverse inflammatory responses in rodent lungs and such particles may translocate to other areas of the body, including the brain. An important method for protecting workers handling nanoparticles from exposure to airborne nanoparticles is the laboratory fume hood. Such hoods rely on the proper face velocity for optimum performance. In addition, several other hood design and operating factors can affect worker exposure. Handling experiments were performed to measure airborne particle concentration while handling nanoparticles in three fume hoods located in different buildings under a range of operating conditions. Nanoalumina and nanosilver were selected to perform handling experiments in the fume hoods. Air samples were also collected on polycarbonate membrane filters and particles were characterized by scanning electron microscopy. Handling tasks included transferring particles from beaker to beaker by spatula and by pouring. Measurement locations were the room background, the researcher’s breathing zone and upstream and downstream from the handling location. Variable factors studied included hood design, transfer method, face velocity/sash location and material types. Airborne particle concentrations measured at breathing zone locations were analyzed to characterize exposure level. Statistics were used to test the correlation between data. The test results found that the handling of dry powders consisting of nano-sized particles inside laboratory fume hoods can result in a significant release of airborne nanoparticles from the fume hood into the laboratory environment and the researcher’s breathing zone. Many variables were found to affect the extent of particle release including hood design, hood operation (sash height, face velocity), work practices, type and quantity of the material being handled, room conditions, and the adequacy of the room exhaust.

Polymer nanocomposites, which contain nanoparticles dispersed in a polymer matrix, provide improved properties at low filler loadings. These materials are already produced commercially, with twin-screw extrusion being the preferred process for compounding the nanoparticles and polymer melts. Several recent studies have demonstrated that nanoparticles can enter the body through inhalation, but the risk assessments for nanoparticle exposures are incomplete. Recently, concerns had been expressed that airborne nanoparticles released during compounding might present significant exposure to extruder operators. To assess the impact of the nanoparticles during twin-screw compounding of nanocomposites, researchers with experience in occupational and environmental health and polymer manufacturing monitored the compounding process for a model nanoalumina-containing nanocomposite using a TSI Fast Mobility Particle Spectrometer (FMPS). FMPS measurements were taken at background locations, source locations, and operators' breathing zones. In parallel to the FMPS real time measurement, airborne nanoparticles were collected using polycarbonate filters fitted with filmed grids driven by a personal air sampling pump. Filter samples were analyzed for particle morphology and elemental composition, and the results were found to be in good agreement with particle measurements by FMPS. Engineering controls and administrative controls were applied to reduce particle release from the compounding process and other operations in the laboratory. The administrative controls dramatically eliminated nanoparticles in the laboratory air, reducing total concentration by as much as 53 000 particles/cm3. Engineering controls were investigated and significant reductions of particle release were attained. The primary solution to reduce exposure level of nanoalumina is to isolate the releasing source. Overall, the engineering controls and administrative controls were effective in reducing airborne nanoparticle release during compounding.

Aspirin, a non-steroidal anti-inflammatory drug, widely used for its anti-inflammatory properties is associated with several systemic side effects including gastro-intestinal discomfort. Inflammation can be mediated by pro-inflammatory cytokines and, along with various other host factors eventually give rise to edema at the inflamed site. Because of the adverse side effects oftentimes associated with systemic exposure to aspirin, the aim of the present study was to investigate whether the anti-inflammatory property of aspirin would enhance if delivered as nano-emulsion preparation. Nano-emulsion preparations of aspirin prepared with a Microfluidizer (R) Processor were evaluated in the croton-oil-induced ear edema CD-1 mouse model using ear lobe thickness and the accumulation of specific in situ cytokines as biomarkers of inflammation. The results showed that particle size (90 nm) populations of nano-emulsion preparations of aspirin compared to an aspirin suspension (363 nm), significantly decreased (p<0. 05) ear lobe thickness approximately 2 fold greater than the aspirin suspension. In addition, the aspirin nano-emulsion further reduced the auricular levels of IL-1 alpha (-37%) and TNF alpha (-69%) compared to the aspirin suspension preparation (p<0.05). The reductions in ear lobe thickness were also significantly associated with accumulated tissue levels of IL-l alpha (r=0.5, p<0.009) and TNF alpha (r=0.7, p<0.0004), respectively. In conclusion, these studies indicate that a nano-emulsion preparation of aspirin significantly improved the anti-inflammatory properties of an aspirin suspension in a CD-1 mouse model of induced inflammation. (C) 2008 Elsevier B.V. All rights reserved.

In this report, we describe the fabrication of a chiral metamaterial based on a periodic array of Y‐shaped Al structures on a dielectric Mylar substrate. The unit cell dimensions of the Y‐structure are ∼100 μm on a side with 8 μm linewidths. The fabricated Y‐structure elements are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative elemental analyses were carried out on both the Y‐structure, comprised of Al and its oxide, as well as adjacent regions of the underlying mylar substrate using the energy dispersive X‐ray spectroscopy (EDS) capability of the SEM. Finite‐Difference Time‐Domain (FDTD) calculations of the negative index of refraction for a 3D wedge of multiple layers of the 2D metamaterials showed that these metamaterials possess double negative (−μ,−ϵ) electromagnetic bulk properties at THz frequencies. The same negative index of refraction was determined for a wedge comprised of appropriately scaled larger Y‐structures simulated in the microwave region. This double negative property was confirmed experimentally by microwave measurements on a 3D wedge comprised of stacked and registered Y‐structure sheets. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.

Well-dispersed Pt nanoparticles with controlled size and narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent. The particle size was varied from 3.5nm to 11.5nm by decreasing the amount of oleylamine added in the synthesis. Size selection of the as-prepared particles by solvent fractionation yielded nearly monodispersed Pt particles. The as-prepared particles were loaded on a carbon support by physical deposition, but showed no electrocatalytic activity due to the oleylamine bound to the particle surface. The particles were activated for electrocatalysis after heating the particles in air at 185°C for 5h, conditions that gave no particle-sintering and no oxidation. Cyclic voltammetry showed that the particles after the heat treatment in air were electrocatalytically active for methanol oxidation. The smaller 3.5nm and 4.0nm Pt particles had a higher intrinsic activity for methanol oxidation, but a lower tolerance to CO poisoning, compared with 6.0nm, 9.5nm and 11.5nm particles. CO-stripping results suggest that CO is more easily oxidized on larger Pt particles.

The microstructure and composition of a nanoparticle Ni catalyst supported on gadolinium-doped ceria (Ce1−xGdxO(4−x)/2) were studied using transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The support of the fresh catalyst exhibits a homogenous aggregation of crystalline grains, with sizes ranging between 20 nm and 50 nm. The crystalline structure of the fresh catalyst support is of the CeO2 phase, in which gadolinium atoms exist in a solid solution of CeO2. Nickel in the fresh catalyst is highly dispersed and forms granular crystals that are 5–30 nm in size on the surface of the ceria support. The support of the used catalyst exhibits a bimodal distribution of grains in which smaller grains have similar structure and morphology as those in the fresh catalyst, while the larger sized grains appear dull and exhibit nonfaceted crystal morphology resulting either from the sintering of a number of CeO2 grains or by the occupation of highly defective crystals of Ce2O3 and CeO phases. A thin amorphous layer of carbon also covers most of the larger grains in the used catalyst. The Ni particles could not be imaged by TEM in the used catalyst, but energy dispersive x-ray spectroscopy (EDX) detected their presence. The XPS analysis of the catalyst samples suggests the participation of lattice O atoms from the ceria support in the catalytic reaction. The XPS data also show the presence of carbonate species and a higher hydrocarbon concentration in the used catalyst.

FCC PtRu nanoparticles with narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate and ruthenium acetylacetonate in diphenyl ether, using oleylamine as the capping agent. The particle size ranged from 3.5 to 6.5 nm and was controlled by varying the amount of capping agent added in the synthesis. Adjusting the stoichiometric ratio of introduced Pt and Ru precursors yielded particles with different compositions. A simple fractionation was employed to narrow the size distribution of particles and nearly monodispersed particles were obtained. To activate the catalytic activity of the particles, oleylamine bound to the particle surface was removed through repeated washing of the as-prepared particles with ethanol and tetramethylammonium hydroxide (TMAOH) aqueous solution. The washed particles could be well redispersed and electrostatically stabilized in TMAOH aqueous solution and uniformly loaded on a Vulcan XC-72 carbon support. A cyclic voltammetry (CV) study revealed that the carbon-supported, cleaned PtRu nanoparticles exhibit considerably higher electrocatalytic activity for methanol oxidation compared with the as-prepared particles that have oleylamine ligands.

Tailoring the surface of nanoparticles is essential for biological applications of magnetic nanoparticles. FePt nanoparticles are interesting candidates owing to their high magnetic moment. Established procedures to make FePt nanoparticles use oleic acid and oleylamine as the surfactants, which make them dispersed in nonpolar solvents such as hexane. As a model study to demonstrate the modification of the surface chemistry, stable aqueous dispersions of FePt nanoparticles were synthesized after ligand exchange with mercaptoalkanoic acids. This report focuses on understanding the surface chemistry of FePt upon ligand exchange with mercapto compounds by conducting X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies. It was found that the mercapto end displaces oleylamine on the Pt atoms and the carboxylic acid end displaces the oleic acid on the Fe atoms, thus exposing carboxylate and thiolate groups on the surface that provide the necessary electrostatic repulsion to form stable aqueous dispersions of FePt nanoparticles.