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In this study, the highly dispersed β-FeOOH on palygorskite (H-β-FeOOH/PAL) was prepared and investigated as Fenton catalyst for H2O2 activation towards metronidazole (MTZ). Based on electron spin resonance and probe techniques, hydroxyl radicles (•OH) as main reactive oxygen species was confirmed, and much more •OH were generated over H-β-FeOOH/PAL than T-β-FeOOH/PAL using traditional impregnation method. The enhanced Fe(III) to Fe(II) cycle due to the highly dispersed β-FeOOH leads to the fast degradation of metronidazole over H-β-FeOOH/PAL. 92.8% of MTZ degradation efficiency was achieved within 180 min by adding 17 mmol/L H2O2 and 40 mg/L of H-β-FeOOH/PAL at pH 6.0. The bacterial cytotoxicity during MTZ degradation process also decreased with reaction time and achieved zero at 66 min, indicating MTZ was not only efficiently degraded but also safely transformed. Besides, the possible MTZ degradation pathway was further proposed based on the intermediates identified by HPLC-MS.

The performance of Pd electrocatalysts for formic acid electrooxidation was improved by application of metal oxide-multiwall carbon nanotubes composites as a catalyst support. Hybrid oxides/MWCNTs were synthesized by two different methods: chemical reduction method and impregnation method. Pd based catalysts were synthesized by polyol method on the MWCNTs or oxide/MWCNTs composites. The In2O3 was deposited on MWCNTs by impregnation method (In2O3/MWCNTs-IM support) and in the presence of NaBH4 (In2O3/MWCNTs-NaBH4 support). The physical properties of the Pd/In2O3/MWCNTs-IM, Pd/In2O3/MWCNTs-NaBH4, Pd/SnO2/MWCNTs, and Pd/MWCNTs catalysts were characterized and their electrocatalytical performance in formic acid oxidation was compared. During Pd deposition on In2O3/MWCNTs-NaBH4 support, InPd2 structure was formed as observed by XRD. The electrochemical tests indicate that the two Pd/ In2O3/MWCNTs electrocatalysts have higher electrocatalytic activity than those of Pd/SnO2/MWCNTs and Pd/MWCNTs. The best performance was observed for the catalyst obtained by In2O3 impregnation of MWCNTs denoted by Pd/In2O3/MWCNTs-IM.

Although pressure therapy (PT) represents the standard care for prevention and treatment of hypertrophic scar (HS) from burns, its practice is largely based on empirical evidence and its effectiveness remains controversial. To clarify the effect of PT (15–25 mmHg) for HS, we performed the systematic review and meta-analysis. Several electronic databases were screened to identify related randomized controlled trials (RCTs). 12 RCTs involving 710 patients with 761 HS resulting from burn injuries were included. Compared with non/low-PT, cases treated with PT (15–25 mmHg) showed significant differences in Vancouver Scar Scale score (MD = −0.58, 95% CI = −0.78–−0.37), thickness (SMD = −0.25, 95% CI = −0.40–−0.11), brightness (MD = 2.00, 95% CI = 0.59–3.42), redness (MD = −0.79, 95% CI = −1.52–−0.07), pigmentation (MD = −0.16, 95% CI = −0.32–−0.00) and hardness (SMD = −0.65, 95% CI = −1.07–−0.23). However, there was no difference in vascularity (MD = 0.03, 95% CI = −0.43–0.48). Our analysis indicated that patients with HS who were managed with PT (15–25 mmHg) showed significant improvements. Due to limitations, more large and well-designed studies are needed to confirm our findings and the side-effects of the PT may also need to be evaluated.

The hybrid nanomaterials of platinum/cerium oxide/multi-walled carbon nanotubes ( Pt/CeO2 /MWCNTs) are synthesized successfully via impregnation and polyol processes. MWCNTs serve as an excellent supporter where CeO2 nanoparticles are decorated with well-distributed Pt nanoparticles. Images show the average particle size of crystalline Pt and CeO2 on MWCNTs are 3–7 and 20–30 nm, respectively. In electrochemical reaction, the redox peak of Pt/CeO2 -700°C/MWCNTs reveals lower potential and higher current density in methanol electro-oxidation than those of other Pt -based ones. The study indicates that the cerium oxide in Pt/CeO2 -700°C/MWCNTs catalyst will enhance significantly the oxygen ions transportation between the interface of Pt and MWCNTs to eliminate the CO poison effect on Pt catalyst.

Multi-walled carbon nanotubes (MWCNTs) supported Pd–Au nanoparticles for electrooxidation of formic acid (FA) are prepared and compared with Pd/MWCNTs in this study. The nanocatalysts are prepared by a polyol method, and characterized using X-ray diffraction (XRD), thermogravimetry (TGA), SEM, and field emission transmission electron microscope (FE-TEM). Cyclic voltammetry (CV) is used to examine the catalytic activity towards FA electrooxidation. Controlling the contents of the precursors (PdCl2 and HAuCl4·4H2O), the different weight ratios of Pd–Au can be synthesized to form the various solid solution structures of Pd–Au. TEM image results indicate the average diameter of Pd–Au solid solution particles is about 10–30 nm. The results of electrochemical analysis show that the Au (10 wt.%)/[Pd/MWCNTs (1:9)](90 wt.%) hybrid catalysts exhibit the highest catalytic activity and better stability than that of Pd/MWCNTs in FA electrooxidation. The promoting of Pd-based catalyst with Au to form solid solution improves the performance of the catalyst in FA electrooxidation. The newly synthesized electrocatalyst is promising for application in direct formic acid fuel cell (DFAFC).

The Pd–Au multiwall carbon nanotubes (MWCNTs) supported catalyst exhibits higher power density in direct formic acid fuel cell (DFAFC) than similar Pd/MWCNTs catalyst. The Pd–Au/MWCNTs catalyst also exhibits higher activity and is more stable in electrooxidation reaction of formic acid during cyclic voltammetry (CV) measurements. After preparation by polyol method, the catalyst was subjected to two type of treatments: (I) annealing at 250 °C in 100% of Ar, (II) reducing in 5% of H2 in Ar atmosphere at 200 °C. It was observed that the catalyst after treatment I was completely inactive, whereas after treatment II exhibited high activity. In order to explain this effect the catalysts were characterized by electron spectroscopy methods. The higher initial catalytic activity of Pd–Au/MWCNTs catalyst than Pd/MWCNTs catalyst in reaction of formic acid electrooxidation was attributed to electronic effect of gold in Pd–Au solution, and larger content of small Au nanoparticles of 1 nm size. The catalytic inactivity of Pd–Au/MWCNTs catalysts annealed in argon is attributed to carbon amorphous overlayer covering of Pd oxide shell on the metallic nanoparticles.

The multiwall carbon nanotubes (MWCNTs) supported Pd catalyst, prepared by the polyol method and reduced in 5% of H2 in Ar atmosphere at temperature of 200 °C, exhibits high activity in electrooxidation of formic acid, whereas, the same catalyst calcinated at temperature of 250 °C in 100% of Ar is inactive. The structural and chemical properties of the catalyst surfaces after reducing and calcination treatments were investigated using electron spectroscopy. The catalytically active sample indicated smaller O content, with the same content of Pd and C at the surface. Simultaneously, the content of carbon–oxygen–hydrogen groups, i.e., carboxyl, carbonyl, ester, ether, and acid anhydride, was lower. In the surface layer of both catalysts, three chemical Pd forms were observed: Pd metallic crystallites, PdO and Pd in organic matrix. In active catalyst, similar content of Pd crystallites and smaller content of PdO were observed. The differences in activity of the investigated Pd/MWCNTs catalysts after reduction and calcination result from the amorphous carbon covering the PdO/Pd nanoparticles, where the PdO layer is of larger thickness for inactive catalyst. This overlayer is removed after reduction in 5% of H2 in Ar atmosphere at temperature of 200 °C.

In the present study, Ti50Cu28Ni15Sn7 metallic glass and its composite powders reinforced with 4–12 vol.% of Al2O3 added were successfully prepared by mechanical alloying. In the ball-milled composites, an amorphous matrix with a homogeneous dispersion of Al2O3 particles was developed. The metallic glass composite powders were found to exhibit a large supercooled liquid region before crystallization. The presence of Al2O3 particles did not change the glass formation ability of the amorphous Ti50Cu28Ni15Sn7 powders. Consolidation of the as-milled Ti50Cu28Ni15Sn7 composite powders was performed at a temperature slightly higher than the glass transition temperature under a pressure of ∼1.2 GPa; using this method, the bulk metallic glass composite discs were prepared successfully. However, partial crystallization of the amorphous matrix during the hot-pressing process was noticed. The fracture strength of consolidated composite compacts was increased with Al2O3 additions. The pre-existing particle boundaries may serve as the crack initiation sites which resulted in the brittle failure of the Ti50Cu28Ni15Sn7 BMG composites.

In the present study, pure TiO2 and hybrid TiO2/CNTs nanomaterials are prepared by sol gel technique. Post heat treatment is performed at 600, 800, and 1000 degrees C, respectively. The structural characterizations are performed by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and synchrotron X-ray absorption spectroscopy techniques. Experimental results show that anatase to rutile transformation can be observed for pure TiO2 nanomaterials after heat treatment at 800 degrees C. The anatase to rutile transformation is inhibited by carbon nanotubes, and therefore only anatase phases for TiO2 nanomaterials can be observed in the hybrid nanomaterials. The 600 degrees C hybrid nanomaterials show a microstructure with CNTs covered by continuous TiO2 films of numerous small nanoparticles. After applying heat treatment on the hybrid nanomaterials at 1000 degrees C, only TiO2 nanoparticles adhere individually to the uncovered CNTs. Though all hybrid nanomaterials exhibit anatase TiO2, synchrotron X-ray absorption spectra investigations reveal that hybrid TiO2/CNTs exhibit different electronic properties as compared to those of pure TiO2 nanomaterials.

Novel multi-wall carbon nanotubes (MWCNTs) supported Pd–Au catalyst for electrooxidation of formic acid was prepared and compared with a similarly prepared Pd/MWCNTs and with a commercial Pt–Ru/Vulcan catalyst. The catalysts were prepared by a two-stage polyol method, followed by H2–Ar annealing and were characterised by using X-ray diffraction, FE-TEM and EDX. Cyclic voltammetry (CV) was used to test their catalytic activity towards formic acid electrooxidation and accessible metal surface in the catalyst layer. In the case of the precursor of Pd–Au/MWCNTs catalyst (before H2–Ar annealing), subsequent deposition of Pd and Au led to a material of the core-shell structure, catalytically inactive. Annealing of the core shell Pd–Au/MWCNTs precursor in H2–Ar resulted in the formation of the novel Pd–Au/MWCNTs catalyst. A highly dispersed Pd–Au solid solution (average XRD particle size 4.8 nm) is formed, and the novel catalyst is more active than the Pd/MWCNTs one. Both the Pd–Au/MWCNTs and the Pd/MWCNTs catalysts turned out to be more active than a commercial, highly dispersed Pt–Ru/Vulcan catalyst.

Colloidal Ag nanoparticles were formed by X-ray irradiation in the presence of a polymer. This new synthesis method is simple, rapid and leads to a high production yield. Compared to the citrate-reduced Ag colloidal, polymer-protected Ag nanoparticles are smaller in size and more stable—and therefore suitable for biomedical application—as verified by TEM observation, XAFS measurement and optical characterization. Ag nanoparticles so produced were also visualized in solution and in real time by a visible light microscope based on dark field light scattering. The color-derived size and distribution of Ag nanoparticles correlates well with the hydrodynamic size data.

In the present study, hybrid Pt/TiO 2 /MWCNTs nanomaterials are prepared successfully by a combined sol–gel and polyol process. The as-prepared nanomaterials are characterized by X-ray diffraction, high resolution transmission electron microscopy, and thermogravimetry analysis. In addition, its catalytic performance by converting CO into CO 2 is also evaluated. Experimental results show that the hybrid Pt/TiO 2 /MWCNTs nanomaterials exhibit a mixture of anatase TiO 2 and Pt phases. Multi-wall carbon nanotubes serve as an excellent supporting material where anatase TiO 2 nanoparticles are decorated with well-distributed Pt nanoparticles. Excellent catalytic performance can be revealed for the hybrid Pt/TiO 2 /MWCNTs nanomaterials. When compared with its Pt/TiO 2 counterparts where ∼ 100% CO conversion occurred at 150 °C, almost 100% conversion of CO into CO 2 can be observed at a temperature ranged from 30 °C to 100 °C.

The aim of this research is to investigate the method of white X-ray irradiation (WXI) for forming nano particles or wires mostly inside multi-walled carbon nanotubes (MWCNTs). WXI approach which uses the energy of light to react with MWCNTs in aqueous solution has not yet been found. This study is mainly focusing on white X-ray irradiation technique which illustrates MWCNTs can be used as template for self-assembled nanowires. WXI synthesis technique is compared with the traditional method of heat treatments for various structures of nano hybrid materials. The research indicates that the traditional heat treatment results in nano particles being on the surfaces of MWCNTs; while the WXI keeps them inside MWCNTs. Accordingly, a model of light-heat transformation for MWCNTs is proposed to explain the mechanism of reaction inside MWCNTs. It is also found that the approach of WXI can fill nanoparticles inside MWCNTs in a comparatively shorter time.

In the present study, Ti 50 Cu 28 Ni 15 Sn 7 (at.%) metallic glass and its composite powders reinforced with 4-12 vol.% of added SiC were successfully prepared by mechanical alloying. In the ball-milled composites, an amorphous matrix with a homogeneous dispersion of SiC particles was developed. The metallic glass composite powders were found to exhibit a large supercooled liquid region before crystallization. The presence of SiC particles did not change the glass-formation ability of the amorphous Ti 50 Cu 28 Ni 15 Sn 7 powders. Consolidation of the as-milled Ti 50 Cu 28 Ni 15 Sn 7 composite powders was performed at a temperature slightly higher than the glass-transition temperature under a pressure of ∼1.2 GPa; using this method, the bulk metallic glass composite discs were prepared successfully. However, partial crystallization of the amorphous matrix during the hot-pressing process was noticed. The fracture strength of consolidated composite compacts was increased with SiC additions. The pre-existing particle boundaries may serve as the crack initiation sites which resulted in the brittle failure of the Ti 50 Cu 28 Ni 15 Sn 7 BMG composites.

Formation of surface and inclusion complexes of single-walled carbon nanotubes (SWCNT) with dextrans of M w 6000 to 2 000 000 was proven spectrally, rheologically, and calorimetrically. Band shifts in the Raman spectra, increase in the viscosity of aqueous solutions of particular dextrans after admixture of SWCNT, and enthalpies of melting of those complexes were independent on molecular weight of dextrans. Computational simulations were performed using the HyperChem 7 and Gaussian 03 packages, starting from a model of single, short SWCNT and linear dextran chain made of 12, 18 or 24 β-D-glucose units. The simulation indicated that dextran chains composed of 12 or 18 β-D-glucose units only partly enveloped SWCNT and the intermolecular interactions in both terminals of the chains prevailed. The dextran containing 24 β-D-glucose units fully enveloped SWCNT. However, the role of SWCNT in the envelop formation was limited solely to its hydrophobic interactions with the central part of the dextran chain.

Purification of multi-wall carbon nanotubes (MWCNTs) from the iron catalyst and amorphous carbon and associated with that process, their oxidation with conc. HNO 3 over 100 °C on sonication to carboxylated MWCNTs (CMWCNTs) is presented. A novel way of decoration of CMWCNTs with ZnO and ZnS quantum dots (QDs) is proposed. It involves the use of corresponding ammonium zincates. CNT–COO–Zn–X where X = OH and SH, respectively, provided nucleation for the QDs growth. That approach does not require any non-covalent mediation from either inorganic or organic carriers.

The fabrication of gold Fresnel zone plates, by a combination of e-beam lithography and electrodeposition, with a 30 nm outermost zone width and a 450 nm-thick structure is described. The e-beam lithography process was implemented with a careful evaluation of applied dosage, tests of different bake-out temperatures and durations for the photoresist, and the use of a developer without methylisobutylketone. Electrodeposition with a pulsed current mode and with a specially designed apparatus produced the desired high-aspect-ratio nanostructures. The fabricated zone plates were examined by electron microscopy and their performances were assessed using a transmission X-ray microscope. The results specifically demonstrated an image resolution of 40 nm.

Multi-wall carbon nanotubes (MWCNTs) were used as a support for the deposition of highly dispersed platinum. After characterization by several physical techniques, the catalyst was studied in reactions for: hydrodechlorination of carbon tetrachloride and the hydrodechlorination of dichlorodifluoromethane. For the first reaction Pt/MWCNTs were very effective catalysts in terms of both the overall activity and the selectivity to CHCl3; both quantities appeared high and stable. For CCl2F2 hydrodechlorination the catalyst was rather moderate, although very stable, activity and product selectivities were established at a constant level in a relatively short time-on-stream. The MWCNTs-supported Pt particles do not undergo great changes during the reactions, i.e. neither substantial metal sintering occurred nor extensive surface carbonization/chloriding took place.

Gold nanoparticles decorating the surface of multiwalled carbon nanotubes (MWCNTs) are prepared by photochemical reduction. The gold clusters form different interesting geometrical faceted shapes in accordance to time duration of synchrotron X-ray irradiation. The shape of nanogold could be spherical, rod-like, or triangular. Carbon nanotubes serve as optimal templates for the heterogeneous nucleation of gold nanocrystals. These nanocrystal structures are characterized by transmission electron microscope (TEM) and element analysis by energy dispersive spectroscopy (EDS).

Agarose, -, K-, and λ-carrageenans, and xanthan gum in aqueous solutions interacted with single-walled carbon nanotubes (SWCNTs) as proven by their wetting in solution and by the microRaman spectroscopy, rheological studies, and differential scanning calorimetry. The investigations provided evidence that the effect of complexation of polysaccharides was independent of the possibility of the formation of helical complexes. Complexation involved, to a certain extent, interactions between hydrophobic surface of nanotubes and hydrophobic sides of the saccharide units of polysaccharides. However, clathration of nanotubes in the polysaccharide matrices was also essential. Formation of the clathrate cages involved intra- and intermolecular hydrogen bonds within polysaccharides.

The behaviour of an elastomeric seal for vehicle brake Tandem master cylinder is measured and analyzed in temperature and brake fluids changed. Working conditions are simulated for different piston rod velocity and cylinder supply pressure, in temperature rising, brakefluid boundary and Nanoaluminum oxide brakefluid oxide brakefluid lubrication. The result shows that Nanoaluminum oxide brakefluid with its ball shape can highly reduce friction coefficient to avoid seal excessive wear and reduce slick slip in brake applications.

Most of the gases detecting metal oxide semiconductors are operated at temperatures above 250oC. It is not energy efficient for MOS gas sensors to operate at such high temperature. To solve this problem, research and investigations are trying to obtain new MOS sensing materials that can operate at ambient temperature. In this study, gas sensing materials consisting of MOS and carbon nanotubes (CNTs) are developed for detecting gases at lower temperature. The hybrid system, MWCNTs/TiO2, demonstrates the possibility of detecting the gases at ambient temperature with high energy efficiency.

A new hybrid SWCNTs/SnO 2 gas sensor is developed by adding single-walled carbon nanotubes (SWCNTs) into a SnO 2 substrate. The fabrication involved heat-treating the SWCNTs/SnO 2 layer, which was fabricated by spin coating using an organometallic solution of dispersed with SWCNTs. The hybrid sensor is utilized to detect NO 2 concentrations in flowing air or N 2 , by considering alterations in electrical properties. The tests are performed at room temperature. Two hybrid sensors with different concentrations of SWCNTs are examined to elucidate the effect of a concentration of SWCNTs on the sensing properties of the sensors. A SnO 2 sensor without SWCNTs, a blank sample, is also examined for comparison. Comparative gas sensing results reveal that the prepared hybrid SWCNTs/SnO 2 sensors exhibit much higher sensing sensitivity and recovery property in detecting NO 2 gas at room temperature than the blank SnO 2 sensor. This finding shows that doping with SWCNTs improves the sensitivity of hybrid sensors. Microstructural observations revealed that SWCNT bundles are embedded in the SnO 2 matrix. Therefore, a model is presented to relate potential barriers to electronic conduction in the hybrid material. This model suggests that the high sensitivity is associated with the stretching of the depletion layers at the grain boundaries of SnO 2 and the SWCNTs/SnO 2 interfaces when detected gases are adsorbed.

A piezoelectric quartz crystal microbalance (PQCM) was used to demonstrate an easy method for examining the gas adsorption behavior of O2, N2 and Ar on single-walled carbon nanotubes (SWCNTs). The coated PQCM was set in a vacuum chamber, and its temperature was controlled by a heater. Before each test, the nanotube bundles were exposed to a high vacuum for at least 2 h, to ensure that the gases were completely desorbed. The temperature of the chamber was set to 300, 323 or 343 K while the vacuum chamber was filled with a gas to increase the pressure stepwise. At the beginning of each step of the increase in pressure, the frequency of the PQCM gradually decreased and finally reached a stable value. The change in frequency is proportional to the amount of adsorption on the PQCM. According to Sauerbrey theory, the changes in frequency are expressed as adsorption isotherms. These isotherms can be used to determine experimentally the isosteric heat of adsorption (qst) of O2, N2 and Ar on the SWCNT bundles. The binding energies (e) of these gases were also calculated from the average values of qst on the SWCNT bundles. These results indicate that these values of e on the SWCNTs samples exceed those obtained for the same adsorbents on planar graphite, by approximately 41–52%. The adsorption isotherms of O2, N2 and Ar at 77 K were also investigated by the Brunauer–Emmett–Teller (BET) method to verify these results.

Single-walled carbon nanotubes (SWCNTs) are wetted in aqueous solution of pure potato and waxy corn amylopectins. Formation of weak sorption complexes of amylopectins on carbon nanotubes is postulated based on the micro-Raman spectra, differential scanning calorimetric and thermogravimetric studies as well as scanning electron micrographs and atomic force microscope images. Under an influence of ultrasounds bundles of SWCNTs disintegrated much more readily in aqueous solution of waxy corn amylopectin. In the solid state resulting from evaporation of suspensions to dryness interactions of SWCNTs with waxy corn amylopectin were also stronger than with potato amylopectin.

Amorphization behaviour of NixTa100−x alloy powders synthesized by mechanical alloying mixtures of pure crystalline Ni and Ta powders with a Spex high energy ball mill was studied. The mechanically alloyed powders were amorphous for the composition range between Ni10Ta90 and Ni80Ta20. This range is larger than amorphous alloys prepared by the rapid-quenching process or by electron-gun deposition technique. A supersaturated nickel solid solution formed for Ni-rich composition. The thermal stability has been investigated by differential thermal analysis. The crystallization temperature of amorphous Ni—Ta powders was proportional to the Ta content, and the activation energy of amorphous Ni—Ta powders exhibited a maximum near the eutectic composition. It is found that the amorphization rate at the early stage of the mechanical alloying process was faster in the intermediate compositions than those at both Ni- and Ta-rich compositions.

Extremely high financial support has been provided to different scientific institutes due to a world priority to find new kinds of energy sources. This has a clear strategic importance for the energy industry. Hydrogen is the most energetic material known and safe for our environment. However, it creates a lot of problems to achieve safe, effective and reversible storage. Some of the theoretical simulations show that carbon nanotubes (CNTs) and/or CNTs hybrid systems could be quite promising material for hydrogen storage. To study a new carbon material for gas adsorption–desorption properties the ultra-high vacuum (UHV) system is proposed here.

This study examined the amorphization behavior of Ni x Ta100−x alloy powders synthesized by mechanically alloying (MA) mixtures of pure crystalline Ni and Ta powders with a SPEX high energy ball mill. According to the results, after 20 hours of milling, the mechanically alloyed powders were amorphous for the composition range between Ni10Ta90 and Ni80Ta20. A supersaturated nickel solid solution formed for Ni90Ta10, as well. X-ray diffraction analysis reveals two different types of amorphization reactions. Through an intermediate solid solution and by direct formation of amorphous phase. The thermal stability of the amorphous powders was also investigated by differential thermal analysis. As the results demonstrated, the crystallization temperature of amorphous Ni-Ta powders increased with increasing Ta content. In addition, the activation energy of amorphous Ni-Ta powders reached a maximum near the eutectic composition.

The crystallization behavior of poly(ether ether ketone) (PEEK) under pressures from 0·1 to 200 MPa has been studied by using a tubular oven or hot isostatic pressing. The DSC results and SEM observations show that high pressure will enhance the formation of large spherulitic crystals of PEEK. Three-point bending tests of the pressure-crystallized samples indicate that the modulus, critical stress and strain at crack initiation of the CCF/PEEK composite all fall with increasing pressure. These changes in mechanical properties are considered to be associated with the effects of pressure on the crystallinity and spherulite size of PEEK.

The fabrication of devices to focus hard x-rays is one of the most difficult—and important—challenges in nanotechnology. Here we show that Fresnel zone plates combining 30 nm external zones and a high aspect ratio finally bring hard x-ray microscopy beyond the 30 nm Rayleigh spatial resolution level and measurable spatial frequencies down to 20–23 nm feature size. After presenting the overall nanofabrication process and the characterization test results, we discuss the potential research impact of these resolution levels.

Several aromatic compounds derived from benzene by its annelation (naphthalene, anthracene, phenanthrene, pyrene) and exocyclic substitution (e.g., nitrobenzene, dinitrobenzenes, trinitrobenzene, chlorobenzene, N,N-dimethylaniline, and others) and endocyclic substitution (pyridine, quinoline, isoquinoline) efficiently sorbed on multi-walled carbon nanotubes (MWCNTs). Equilibrium constants for the sorption process have been determined. Computations of the energy of formation were performed for surface complexes of those arenes on single-walled carbon nanotubes (SWCNTs). Formation energies of those complexes were correlated against the experimental equilibrium constants. The latter were also correlated against calculated LUMO energy of the arenes. Solely, limited tendencies to the linearity could be observed. The analysis of the results of the correlations indicated that the arenes acting as the charge acceptors formed stronger complexes than arenes with a high electron density in the molecular orbital, for instance, N, N-dimethylaniline. The area of the arene--SWCNT contact was very essential for the complexation. The proximity of the HOMO orbital of SWCNT and LUMO of the arene was another essential factor. Bulky substituents in the arene molecules obscured their efficient contact with SWCNT.

As proven by the UV-VIS, micro-Raman spectroscopies, differential scanning calorimetry, beta-carotene, lycopene, retinoic acid, and retinol adsorbed on the surface of single-walled carbon nanotubes (SWCNT) form electron donor-acceptor (EDA) complexes. The rate of the adsorption of carotenoids is estimated as the rate of decrease in their concentration in solution followed the exponential curve equation. The rate of the adsorption decreased with the chain length of the guest capable sorption on the surface and steric effect of the terminals in the beta-carotene was also essential. Also, increase in the polarity of the functional groups expressed, for instance, in Taft sigma* substituent constants had its impact. The HyperChem 7 followed by Gaussian 03 computations revealed that the inclusion SWCNT-carotenoid complexes were more stable than corresponding surface complexes. In the surface complexes carotenoids acted as donors in respect to SWCNT whereas in the inclusion complexes they were acceptors.

Careful preparation of iron nano-particles catalyst for carbon nanotubes (CNTs) synthesis has crucial importance for their initial growth process, what determines CNTs physical and chemical properties, such as their diameters, wall geometry, electronic structure, defects presence, etc. At present we are not able to control all factors influencing the growth of CNTs especially the geometry of the outermost shell, the numbers of shells, their external and internal diameters, the presence of different kinds of defects. Carbon offers the greatest variety of allotropic forms among all elements and it can also form one of the longest one-dimensional objects with an ordered structure and very high aspect ratio. This great structural diversity of carbon nano-objects suggests that there is great chance for their serious applications in the 21st nano-electronic century.

Closed-end single-walled carbon nanotubes were wetted in aqueous solutions of monosaccharides, forming weak surface complexes, as proven by the estimation of the content of monosaccharides in complexes isolated from aqueous solutions. The complexation was confirmed by micro-Raman spectroscopy. The Gaussian 03 (Molecular Mechanics UFF method) computations of total energy of the single-walled carbon nanotube-monosaccharides inclusion and surface complexes showed that inclusion complexes should be more stable than corresponding surface complexes. Computed total energies for particular complexes pointed to a lack of preferences for the formation of complexes with either alpha- or beta-tautomers and either pyranoses or furanoses. The forms preferred in the formation of the surface complexes usually differ from these favored in the formation of the inclusion complexes.

The carbon nanotubes provide large surface that can enhance the gas adsorption properties and increase the conductivity at a lower temperature for gas sensing. The gas sensing properties of the hybrid TiO2/CNTs material are examined in this study. The sol-gel technique is used to prepare a thin layer of nano-TiO2 coated on CNTs. The structure of TiO2/CNTs hybrid materials is identified by X-ray diffraction (XRD) and Raman spectrum. The granules and surface morphology are analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical properties of the hybrid TiO2/CNTs indicate that the operation temperature can be lowered to ambient temperature and this will enhance the gas sensitivity for detecting CO gas. The n-type or p-type behavior of hybrid TiO2/CNTs can be controlled by the coating thickness of hybrid TiO2. According to the image results, the mechanisms of the n-type and p-type behavior of hybrid TiO2/CNTs system are proposed.

We have observed the discrete structure of the FEM image in the field emission from the end cap of an individual SWCNT at room temperature. The computer calculations based on the formula of the optical interference can create a similar pattern. Our model suggests that coherent electron emission from the end cap hexagon carbon ring of the SWCNT took place.

Cold glow air plasma was used to remove the peaks of the tips of the well-aligned arrays of carbon nanotubes (CNTs) in a controlled, uniform manner. The process can be performed at about 0.1 micron/min rate without significant destruction of the bottom of CNTs. This approach might be applied to different physico-chemical modifications of the peaks of CNTs tips and removal of the peaks containing catalyst nanoparticles and/or other impurities as well as to leveling of the CNTs arrays.

In the electrodeposition of metals, a widely used industrial technique, bubbles of gas generated near the cathode can adversely affect the quality of the metal coating. Here we use phase-contrast radiology with synchrotron radiation to witness directly and in real time the accumulation of zinc on hydrogen bubbles. This process explains the origin of the bubble-shaped defects that are common in electrodeposited coatings.

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Alloys of 0, 30, 40 and 50 at.% nickel in iron have been processed in vacuum by electrohydrodynamic atomization (EHD) to produce submicron droplets. The as-solidified spheres are studied to determine which of several solidification phases has appeared. Field-emission scanning transmission electron microscopy (STEM) is used to determine the microstructure, composition and crystal structure of the 10–150 run diameter spheres. It is believed that homogeneous nucleation must be the predominant nucleation mechanism in EHD droplets during free flight. The alternative crystallization phase, b.c.c., in the Fe-Ni alloy system, is found in 30 and 40 at.% Ni alloys but not in the 50 at.% Ni alloy. A new hexagonal crystal structure of Fe-50 at.% Ni is discovered. Furthermore, the smallest spheres of each alloy ( Acta metall. 36 , 2537 (1988)], based on classical nucleation theory which predict the conditions under which alternative crystallization phases may appear.

Tests performed in different regimes reveal the interplay of two edge-enhancement mechanisms in radiological images taken with coherent synchrotron light. The relative weight of the two mechanisms, related to refraction and to Fresnel edge diffraction, can be changed in a controlled way. This makes it possible to obtain different images of the same object with complementary information. (C) 1999 American Institute of Physics. [S0021-8979(99)03720-2].