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Understanding and controlling charge transfer through molecular nanostructures at interfaces is of paramount importance, particularly for electronic devices but also for contact electrification or in bioelectronics. We investigate the influence of intercalation and exchange of molecularly thin layers of small molecules (water, ethanol, 2-propanol, and acetone) on charge transfer at the well-defined interface between an insulator (muscovite mica) and a conductor (graphene). Raman spectroscopy is used to probe the charge carriers in graphene. While a molecular layer of water blocks charge transfer between mica and graphene, a layer of the organic molecules allows for it. The exchange of molecular water layers with ethanol layers switches the charge transfer very efficiently from off to on and back. We propose a charge transfer model between occupied mica trap states and electronic states of graphene, offset by the electrostatic potentials produced by the molecular dipole layers, as supported by molecular dynamics simulations. Our work demonstrates how intercalation of molecules of volatile liquids can reversibly affect charge transfer at interfaces. This implies its strong impact on the function of hybrid inorganic-organic electronic devices in different ambients and potential applications, including sensors and actuators.

Humidity influences friction in layered materials in peculiar ways. For example, while water improves the lubricating properties of graphite, it deteriorates those of molybdenum disulfide (MoS2). The reasons remain debated, not the least due to the difficulty in experimentally comparing dry and hydrated interface frictions. Here we show that the hydration of interfaces between a mica substrate and single-layers of graphene and MoS2 with a molecularly thin water layer affects strain transfer from the substrate to the 2D materials. For this, we strain the substrate and detect strain in graphene and MoS2 by changes in Raman and photoluminescence spectra, respectively. Strain relaxation in graphene changes from stick-slip in dry contact, to viscous when hydrated. In contrast, there is no viscous relaxation in MoS2 regardless of hydration. Our work provides a novel approach for better understanding the impact of hydration on friction in layered materials.

This paper proposes a calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system. The algorithm error of the calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system was mainly discussed. During the experiments, the laser tracer was fixed on the work surface of the rotary table, and the rotary was fixed on the work surface of the coordinate measurement machine (CMM). The rotary table was rotated with the same angular interval. In this case, an optimization method for calculating the coordinates of a laser tracer station by using Levenberg&ndash, Marquardt algorithm and singular value decomposition transform was proposed. Then, the angular positioning deviation of the rotary table was calibrated by an established geometric relationship model between the coordinates of laser tracer stations and the rotation angle of the rotary table. The angular positioning deviation of the high-precision rotary table was as low as &plusmn, 0.9&Prime, and the error of the calibration method was &plusmn, 0.4&Prime, The experimental results proved the feasibility of the proposed calibration method. The calibration method proposed in this paper is suitable for the case that the rotary table is not linked with the CMM, especially for large high-precision rotary tables.

To understand the plastic layer properties, which directly impact coke quality during the coking process, the plastic layer characteristics formed by seventeen kinds of coking coals were analyzed using a penetrometer equipped on a thermogravimetry–plastometer–swelling pressure apparatus. The penetrometer-resistance (PR) curves of the plastic layer were obtained. Characteristic parameters of the plastic layer were determined from the PR curves. The relationships between these parameters and coal thermoplastic parameters were constructed and evaluated. Additionally, the interaction between the structural zones of the plastic layer was investigated. It was found that the plastic layer is composed of four structural zones, namely the increasing, decreasing, constant, and re-rising PR zones, in which the PR decreasing zone and constant zone are the critical zones for thermoplastic development. In contrast, the PR increasing zone does not have obvious thermoplasticity, and the PR re-rising zone goes against the thermoplastic development. Some derived parameters ( PR ¯ max and PR ¯ min , Y ¯ DZ + Y ¯ CZ , Y ¯ DZ + Y ¯ CZ / Y ¯ Re - r Z ) may be used as indicators to reflect the impermeability, internal thermoplastic properties, and caking performance of the plastic layer. These findings can provide an insight into the properties of the plastic layer during coal carbonization and maybe lay a foundation for coke quality prediction.

The residual stresses in ZrB2SiC ceramics with the addition of WC or ZrC were measured using Raman spectroscopy (RS) and X-ray diffraction (XRD). The temperatures at which the residual stresses began to accumulate were calculated. The resistance to high-temperature deformation of ZrB2SiC-based ceramics was evaluated via four-point flexure test under a static load (15, 25 MPa) for 5 h at 1600 °C and 1800 °C. The results indicate that a compressive residual stress existed in SiC particles and a corresponding tensile stress applied in ZrB2 matrix. The values of thermal residual stresses increase in order of ZSZ (ZrB2SiCZrC)

The influence of CMM geometric errors on 3D gear measurements is still unclear as the requirement for a gear measurement standard with ideal geometry cannot be fulfilled. To solve this issue, the authors have proposed and developed a software program named Me2Ge to simulate 3D gear measurements with CMMs. This allows a systematic analysis of how gear deviations are affected by geometric errors of a CMM, and how the influence can be reduced. A large gear ring measurement standard and a large Cartesian CMM are used as an important application example. The simulation results achieve the gear deviations under the influence of machine geometric errors, and reveal the major error sources for profile slope deviation, helix slope deviation and single pitch deviation, which gives a first impression of geometric errors and their influence on 3D gear measurements. Finally, reversal techniques are integrated into the Me2Ge program to compensate machine errors. The results clearly prove that reversal techniques play a significant role and are worth spending the necessary time to achieve lower measurement uncertainties.

The stable solid–liquid phase equilibrium for ternary systems of terephthaldialdehyde + 4-hydroxybenzaldehyde + ethyl acetate and terephthaldialdehyde + 4-hydroxybenzaldehyde + acetone was determined using the isothermal saturation method at 293.15, 303.15, and 313.15 K under ambient pressure of 101.2 kPa. In terms of the obtained mutual solubility data, the isothermal phase diagrams of the two systems were constructed. At a given temperature, there were two pure solids formed, pure 4-hydroxybenzaldehyde and pure terephthaldialdehyde, which were identified by Schreinemakers’ wet residue method and X-ray powder diffraction analysis. The crystallization zones of pure 4-hydroxybenzaldehyde and pure terephthaldialdehyde increased with rising temperature. The crystalline zone of terephthaldialdehyde was larger than that of 4-hydroxybenzaldehyde at the same temperature. The mutual solubility data of solid–liquid phase equilibrium were correlated with nonrandom two-liquid (NRTL) and Wilson models. The calculated...

Noncovalent forces are of considerable importance in the formation of self-assembled drug-delivery systems. In addition to non-destructively linking the delivery vehicle and guest drug, they provide multiple advantages, including protecting the structure of the drug, maintaining its functional effects, and facilitating its release. In particular, π-π stacking interactions have potential application in a comprehensive range of biomedical and biotechnological fields. Because they do not alter structural or functional properties of drugs, π-π stacking interactions have been used as a driving force in loading drugs into delivery systems, and in the design of self-assembling systems. Moreover, since the π-π stacking force is affected by environmental conditions such as pH, it has been used to design environment-responsive drug-delivery systems. In this review, we cover features of π-π stacking interactions and their applications to the design of drug-delivery systems. Carbon nanotubes, graphene-based nanomaterials, micelles and hydrogels-all delivery systems capable of π-π stacking interactions-are the focus. We also cover π-π stacking interaction-based loading of chemicals or biological drugs into delivery systems, and controlled release of drugs from delivery systems in certain environments. In addition, we examine the in vivo barriers for π-π stacking interaction-based drug delivery, and discuss challenges for clinical applications and future directions.

In order to realize the holographic display by a 2D image and to suppress speckle noise of reconstructed images, Fresnel kinoform is calculated by adding the phase information, which is obtained based on the gray curve of a 2D image by computing a polynomial equation into initial phase factor of a complex object. A vivid holographic reconstructed projection image with real phase information can be observed with naked eye.

The Habib™ EndoHBP catheter is a novel bipolar radiofrequency catheter developed for intraluminal ablation to relieve malignant extrahepatic biliary obstruction. Clinical experience with its use is limited and scattered. The purpose of this study was to evaluate the clinical feasibility and safety of this technique. A single central retrospective analysis was performed with patients who underwent percutaneous intraluminal radiofrequency ablation (RFA) combined with biliary stenting for treatment of extrahepatic obstructive jaundice between September 2011 and May 2014. A Habib™ EndoHBP catheter was used for RFA. Clinical and telephonic follow-ups were carried out. Procedure-related complications, stent patency, patient survival rate and postoperative biochemical tests were investigated. All the 47 patients tolerated well a total of 65 RFA procedures with self-expandable metal stents placed. The predominant disease was distal cholangiocarcinoma (16 of 47 cases). No procedure-related hemobilia or infections occurred. The main postablation complication was pain which could be controlled by analgesics. One patient suffered abdominal hemorrhage, diagnosed by blood test and abdominal ultrasonography and cured with conservative therapy. Significantly decreased TBIL and DBIL levels (P

We report that ultra-violet (UV) emission of ZnO can be made much more intense by incorporating Ce in the ZnO films. After annealing at 1100 °C in N2 gas, the UV peak (≈3.34 eV, width 133 meV) – intensity for the film doped with Ce is two order of magnitude stronger than that of un-doped ZnO films. The large enhancement is correlated with improved crystallinity and appears due to fewer non-radiative recombination pathways. The improved crystallinity can be related to Ce affecting the self-texturing of ZnO during sputter deposition and annealing.

A relay-triggered cooperative spectrum sensing scheme is proposed in this paper to detect the spectrum opportunities for cognitive radio (CR) networks. Firstly, we design a relay-triggered individual spectrum sensing scheme. Specifically, we exploit a relay signal generated by a cognitive transmitter (CT) who has relaying capability and acts as a full-duplex amplitude-and-forward relay to trigger the primary link's close-loop power control (CLPC) which has been frequently used in practical wireless communication application, resulting in primary transmitter adjusts its transmit power under CLPC, the CR receiver observes the energy of the primary signal and decides whether the primary receivers (PRs) are within or out of CT's coverage. Then, considering the fact that local spectrum sensing may be not reliable due to the fading and shadowing effects, we further develop the proposed individual spectrum sensing scheme to a new collaborative one where multiple CRs are involved in sensing and the common receiver combines the decisions received from cooperative CRs to get a final decision which will improve the sensing performance. Finally, the performances of the proposed schemes are illustrated by simulations.

International audience; It is still a challenge for fruit robot to automatic detecting young green apples in a complex grove environment due to color similarity with the background and varying illumination conditions. The purpose of this study was developing a robust method to detect young green apples in the tree canopy from low-cost color images acquired with diverse fruit sizes and under varying light circumstances. Adaptive green and blue chromatic aberration map was designed and combined with the iterative threshold segmentation algorithm to detect the region of interest contains potential apple fruits pixels. Then every potential fruit was identified by using an improved circular Hough transformation after morphological operation and blob analysis of the ITS outs which kept as many potential apple fruits pixels as possible. Finally, a kernel support vector machine classifier optimized by using grid search algorithm was built and combined with histogram of oriented gradients feature descriptor to distinguish and remove false fruit objects. The experimental result shows that the proposed method has better detection performance for young green apples.

International audience; Automatic detection of mature apples in a complex agricultural condition is still a challenge for an autonomous picking robot due to the influence from overlapping. In order to detecting overlapped apples in tree canopy using a low-cost camera, a robust apples detection and reconstruction approach based on improved K-means and distance least square algorithm was studied. Firstly, the region of potential apple objects was extracted by using improved K-means algorithm. Then, the contours of apples were obtained by utilizing Canny edge detection algorithm on the V component map and the intact contour of unobscured apple was separated from overlapped apples contour after Y-junction searching. Finally, the contour of obscured apple was reconstructed by use of the distance least square circle fitting algorithm. The proposed method was compared with Hough transform method and the experimental result indicated that the proposed method could get much better performance for overlapped apples detection than Hough transform method. Thus it could be concluded that the proposed method is available for robotic apple picking in overlapped fruits scene with low cost.

Scanning force microscopy (SFM) and Raman spectroscopy allow the unraveling of charge doping and strain effects upon wetting and dewetting of a graphene-mica slit pore with water. SFM reveals a wetting monolayer of water, slightly thinner than a single layer of graphene. The Raman spectrum of the dry pore exhibits the ${D}^{\ensuremath{'}}$ peak of graphene, which practically disappears upon wetting, and recurs when the water layer dewets the pore. Based on the $2D$- and $G$-peak positions, the corresponding peak intensities, and the widths, we conclude that graphene on dry mica is charge-doped and variably strained. A monolayer of water in between graphene and mica removes the doping and reduces the strain. We attribute the ${D}^{\ensuremath{'}}$ peak to direct contact of the graphene with the ionic mica surface in dry conditions, and we conclude that a complete monolayer of water wetting the slit pore decouples the graphene from the mica substrate both mechanically and electronically.

This work reports the synthesis of novel nanocomposite electrodes based on MnO2 nanosheets, Pt, Au, or Pd nanoparticles (NPs), exfoliated carbon nanotubes (CNTs), and Ni foam (NF) substrates. The MnO2–Pd–CNT–NF electrode in 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIM-PF6)/N, N-dimethylformamide (DMF) electrolyte exhibits a high specific capacitance of 559.1 F/g based on MnO2 with a wide potential window (2.1 V). To the best of our knowledge, this is one of the highest capacitance for MnO2 in ionic liquid (IL) electrolytes ever reported. The IL hybrid supercapacitors are assembled using MnO2–Pd–CNTs–NF positive electrode, activated carbon (AC) negative electrode, and BMIM-PF6/DMF electrolyte displaying high operating voltage (3 V), high energy density (78.4 Wh/kg) and high power density (12.7 kW/kg). The superior performances of the MnO2 IL hybrid supercapacitors suggest their potential application for the future generation of electrochemical power sources.

A high-speed CE system for multiple samples was developed based on a short capillary and an automated sample introduction device consisting of a commercial multi-well plate and an x-y-z translation stage. The spontaneous injection method was used to achieve picoliter-scale sample injection from different sample wells. Under the optimized conditions, a 40 μm-long sample plug (corresponding to 78-pL plug volume) was obtained in a 50 μm id capillary, which ensured both the high separation speed and high separation efficiency. The performance of the system was demonstrated in the separation of FITC-labeled amino acids with LIF detection. Five FITC-labeled amino acids including arginine, phenylalanine, glycine, glutamic acid, and asparagine were separated within 15 s with an effective separation length of 1.5 cm. The separation efficiency ranged from 7.96 × 10(5)/m to 1.12 × 10(6)/m (corresponding to 1.26-0.89 μm plate heights). The repeatability of the peak heights calibrated with an inner standard for different sample wells was 2.4 and 2.7% (n = 20) for arginine and phenylalanine, respectively. The present system was also applied in consecutive separations of 20 different samples of FITC-labeled amino acids with a whole separation time of less than 6 min.

In2 S3 is a stable semiconductor material with low toxicity.We prepared In2 S3 sensitized solar cells using low-cost chemical bath deposition methodology.X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),and scanning electron microscopy (SEM) were used to reveal the microstructure of the In2 S3 sensitized TiO2 nanoporous films.Our results indicated that the deposition temperature has a remarkable effect on the morphology of In2 S3 sensitized TiO2 films,which in turn affects the photovoltaic performance of devices.When the deposition temperature was low,the deposition reaction rate was slow,resulting in only minimal deposition.However,if the deposition temperature was increased too much,there was insufficient time for the In2 S3 to be deposited within the internal pore structure of the TiO2 mesoporous films.The best homogeneous In2 S3 sensitized TiO2 films were obtained with a deposition temperature of 40 °C.At this temperature,the optical absorption of the resulting film was optimal and displayed the largest short circuit current density among the films examined.Moreover,the fill factor was also the best,approaching 65%.The best overall power conversion efficiency was 0.32%.

The clinical efficacy of intraductal radiofrequency ablation (RFA) with Habib™ EndoHPB catheter, a newly developed intervention for malignant extrahepatic biliary obstruction, remains uncertain. The aim of this study was to investigate the clinical efficacy of intraductal RFA. Data from 71 patients with extrahepatic distal cholangiocarcinoma were retrospectively analyzed. The study patients were divided into RFA and control groups. The RFA group had undergone percutaneous transhepatic intraductal RFA with a Habib™ EndoHPB catheter, followed by placement of covered or uncovered biliary self-expandable metallic stents (SEMs) whereas the control group had undergone percutaneous transhepatic covered or uncovered SEMs placement. Procedure-related complications, stent patency, patient survival, and postoperative serum bilirubin concentrations were compared between the two groups. The Functional Assessment of Cancer Therapy-Hepatobiliary (FACT-Hep) questionnaire was administered to evaluate functional status, improvement in clinical manifestations, and quality of life. The RFA group had a longer median stent patency than the control group (p = 0.001 for uncovered SEMs placement). Higher functional well-being, hepatobiliary-specific cancer subscale, Trial Outcome Index, and total FACT-Hep scores were observed during post-procedure follow-up in the RFA group. However, median survival did not differ significantly between the two groups (p > 0.05). Prolongation of stent patency and better functional status and quality of life, which are all important clinical endpoints, were observed in patients treated with intraductal RFA. Prospective randomized controlled clinical trials are necessary to further investigate the clinical efficacy and long-term benefits of intraductal RFA.

A novel MnO 2 /graphene (G)/nickel foam (NF) composite as supercapacitor electrode was fabricated by a facile electrochemical deposition approach for the first time. The approach includes electrophoretic deposition of G on NF (EPD-G/NF) and electrodeposition of MnO 2 on EPD-G/NF (MnO 2 /EPD-G/NF). Compared with other methods for preparing MnO 2 /G composite, our green strategy avoids using harsh chemicals (e.g. hydrazine) or high temperature treatment for reducing graphene oxide. Owing to unique structure, specific capacitance ( C s ) of the MnO 2 /EPD-G/NF electrode is as high as 476 F g − 1 at high current density of 1 A g − 1 in 0.5 M Na 2 SO 4 solution, which is the highest C s for MnO 2 /G composites to date, and the C s is higher than that of MnO 2 /NF electrode. Furthermore, it also exhibits high rate capacity, such as 216 F g − 1 of C s at 10 A g − 1 . On the other hand, our strategy provides a versatile method for fabrication of other G-based composites with metal oxide/hydroxide or conducting polymer as supercapacitor electrode.

Physical 3D models were established for corrugated packing used in the enrichment of the isotope 13C. Computational fluid dynamics (CFD) simulation results indicated that common corrugated packing was not well wetted when used for isotope distillation. It is concluded that liquid misdistribution in the packed tower results from the structure of the packing rather than from the height of the packing beds. The existence of entrainment was also demonstrated by CFD simulation. It is proved that mass transfer equations based on the Nusselt theory are not suitable for distillation calculation in such a corrugated packing system. By comparison, the recently developed structured packing model with a corrugation geometry based on the right-angled triangle, known as Zigzag-pak, describes vapor-liquid distribution properties well and has significant advantages over common corrugated packing due to its better liquid distribution character.

A novel cogeneration system is proposed for power generation and seawater desalination. It combines the CRGT (chemically recuperated gas turbine) with the MED-TVC (multi-effect thermal vapor compression desalination) system. The CRGT contains a MSR (methane-steam reformer). The produced syngas includes plenty of steam and hydrogen, so the working medium flow increases and NOx emissions can achieve 1 ppm low. However, the water consumption is large, ∼23 t/d water per MW power output. To solve this problem and produce water for sale, MED-TVC is introduced, driven by exhaust heat. Such a dual-purpose plant was analyzed to investigate its performance and parameter selection, and compared with four conventional cogeneration systems with the same methane input. Some main results are following: In the base case of the CRGT with a TIT of 1308 °C and a compression ratio of 15, the MED-TVC with 9 effects, the specific work output, performance ratio and CRGT-consumed water ratio are 491.5 kJ/kg, 11.3 and 18.2%, respectively. Compared with the backpressure ST (steam turbine)/CC (combined cycle) plus MED/MSF (multistage flash), the CRGT + MED has better thermal performance, lower product cost and shorter payback period, which indicates the CRGT + MED dual-purpose system is a feasible and attractive choice for power and water cogeneration.

A special high-performance structured packing, PACK- 13 C, with the surface area high as 1135 m 2 m −3 was developed, and the first stable isotope 13 C pilot-scale plant using structured packing was designed and constructed by carbon monoxide cryogenic distillation, which has run smoothly over 6 months. The height and inner diameter of the distillation column were respectively, 20 m and 45 mm and the height of packing bed was 18 m. The column was well insulated by vacuum multilayer insulation and the total heat leakage of the column was less than 30 W. When the F -factor changes from 0.18 to 0.90 ms −1 (kg m −3 ) 1/2 , the numbers of theoretical plates per meter decreases from 30 to 20, the pressure drop is less than 25 Pa for each theoretical plate, the dynamic liquid holdup is between 11% and 21%, and the pilot-scale plant produces 2.1 g 15% isotope 13 C each day. The fluid mechanical and mass transfer empirical equations were developed according to the experimental data of PACK- 13 C. The PACK- 13 C structured packing exhibits very high performances in isotope separation efficiency and operational flexibility, which is far superior to the traditional random packing. PACK- 13 C is a perfect packing to serve in 13 C separation to increase productivity and reduce consumption.

Functional sulfonic acid groups were covalently grafted onto the surface of multi-walled carbon nanotubes (MWNTS) via a facile route from sulfuric acid and acetic anhydride under mild conditions. The resulting sulfonated MWNTS (S-MWNTS) were further deposited with Pd nanoparticles (S-MWNTS/Pd) as catalysts for ethylene glycol electro-oxidation. Structural characterizations revealed that homogeneously dispersed Pd nanoparticles with an average size of 4.5 nm were loaded on the S-MWNTS supports. It was found that S-MWNTS/Pd catalysts exhibited better electrocatalytic activity and long-term stability than the unsulfonated counterparts. In contrast to the common sulfonication approaches, our strategy could make the functionalization process more easily and effectively, in this way resulting in small size and uniform dispersion of Pd nanoparticles loaded onto the nanotube surfaces. All these demonstrate that it is a simple and efficient approach towards sulfonate-assisted surface functionalization.

Polyaniline/multi-walled carbon nanotubes (MWNTs) composites were prepared by an in situ chemical oxidative polymerization method and were used as the cathode materials for rechargeable lithium batteries. The structure and morphology of the as-synthesized samples were investigated by X-ray diffraction (XRD) and transmission electron microscope (TEM). The charge/discharge property, coulombic efficiency, cyclic voltammetry and ac impedance spectroscopy of the as-prepared samples were also examined in detail. It was confirmed that MWNTs had an obvious effect on the electrochemical performance of polyaniline. The results could be attributed to the excellent electronic and electrochemical properties of MWNTs.

4-Aminobenzoic acid (4-ABA) was covalently grafted on to the surface of multiwalled carbon nanotubes (MWNTs) via a novel amine-cation induced radical reaction. Then, Pd nanoparticles were deposited on functional 4-ABA group-grafted MWNTs (F-MWNTs) by NaBH4 reduction method. The structure and nature of the resulting product were characterized by Fourier transform infrared (FT-IR) spectrometry, transmission electron microscopy (TEM), and X-ray diffraction (XRD) measurements. The electrocatalytic properties of the Pd/F-MWNTs catalyst for methanol oxidation have been investigated by cyclic voltammetry, linear sweep voltammetry and chronomperometry methods. In contrast to the unfunctionalized counterpart, the electrochemical results demonstrate that Pd/F-MWNTs exhibit better electrocatalytic activities and stability, mainly due to the uniform dispersion and small particle size of Pd nanoparticles on the F-MWNT supports. The results imply that the Pd/F-MWNTs catalyst shows the better electrocatalytic performances and has a promising application potential in fuel cells. Keywords: 4-Aminobenzoic acid, MWNTs, Pd nanoparticle, Methanol oxidation, Alkaline solution

In this work, we report a concise method to self-assemble Pd nanoparticles onto the surface of MWNTs. Highly dispersed palladium nanoparticles are loaded on the MWNTs functionalized with mercaptobenzene moieties. The structure of the resulting Pd–fMWNT composite were characterized by transmission electron microscopy (TEM), the results show that the chemically synthesized Pd nanoparticles were homogeneously dispersed and well-separated from one another on the functional MWNT surfaces. Cyclic voltammogram (CV) showed that Pd–fMWNT composite materials perform excellent electrocatalytic activity and long-term stability toward formaldehyde oxidation. Electrochemical impedance spectroscopy (EIS) revealed the strong interaction between fMWNTs and Pd facilitates the effective degree of electron dolocalization, and thus enhances the conductivity of the composite. The results imply that the self-organized Pd–fMWNT composite as a promising support material shows the excellent electrocatalytic activity and has a promising application potential in fuel cells and biosensors.

Functionalized benzenesulfonic groups were grafted onto the surface of multi-walled carbon nanotubes (MWCNTs) supported Pd catalysts in direct methanol fuel cells by a new and simple in situ radical polymerization of 4-styrenesulfonate and isoamyl nitrite. The resultant sulfonated MWCNTs-supported Pd catalysts (S-MWCNTs/Pd) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectrometry measurements. Electrochemical characterizations of S-MWCNTs/Pd catalysts for methanol electro-oxidation in alkaline solution were investigated by cyclic voltammetry techniques. These results showed that S-MWCNTs/Pd exhibited higher electrocatalytic activity, enhanced CO tolerance and better stable life than did that with the unsulfonated counterparts, mainly due to the easier access with methanol and well dispersed distribution of the S-MWCNTs/Pd catalysts in water. In addition, compared with traditional sulfonation of MWCNTs, this new approach is more advantageous to make small and uniform dispersion of Pd particles loaded onto the surfaces of sulfonated MWCNTs, indicating it is a simple, rapid, and efficient method to functionalize MWCNTs.

Polystyrene–acrylonitrile mixed with different carbon nanotube (CNT) fractions has been successfully prepared by means of in situ polymerization method. The tribological behaviors of the nanocomposites are investigated by friction and wear tester under dry conditions. Compared with the polystyrene–acrylonitrile, polystyrene–acrylonitrile–CNTs shows not only the lower friction coefficient but also the higher wear resistance, which reveals that CNT could reduce the friction and improve the wear resistance behaviors of the nanocomposites dramatically. According to the results of the microhardness measurements, CNT is found to be able to improve the microhardness of the nanocomposites effectively. The mechanism of the reinforced tribological properties and microhardness for the polystyrene–acrylonitrile–CNTs nanocomposites is also discussed in detail.

Clay-supported carbon nanotubes (Cs-CNTs) were used as novel nanofillers to improve the thermal and mechanical properties of a polymer. Cs-CNT/poly (vinyl alcohol) (PVA) nanocomposite films were successfully fabricated, and their relative properties were investigated by using differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Experimental results showed that the thermal stability and dynamic mechanical properties of PVA were remarkably enhanced by incorporating the Cs-CNTs into PVA matrix. The largest T(g) difference of 14 degrees C was obtained between pure PVA and PVA nanocomposite with 7 wt% Cs-CNTs. Moreover, the storage modulus of PVA was significantly improved by 133% at 50 degrees C, when 7 wt% Cs-CNTs was added to PVA matrix. POLYM. COMPOS., 30:702-707, 2009. (C) 2008 Society of Plastics Engineers

We demonstrate the use of molecular monolayers to enhance the nucleation of electrocatalytically active PtNi alloy nanoparticles onto the multi-walled carbon nanotubes (MWCNTs). After the siloxane was polymerized on the nanotube surfaces, the carbon nanotubes were embedded within the polysiloxane shell with a hydrophilic amino group situated outside. Subsequent deposition of PtNi nanoparticles led to high density of 3–10 nm diameter PtNi alloy nanoparticles uniformly deposited along the length of the carbon nanotubes. The presence of MWCNTs and PtNi in the composite films was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersion X-ray spectra analysis (EDS). The electrocatalytic activity of the PtNi-modified MWCNT/polysiloxane (PtNi/Si-MWCNT) composite electrode for electro-oxidation of methanol was investigated by cyclic voltammetry (CV), and excellent electrocatalytic activity can be observed.

Spinel lithium manganese oxide was prepared by sol–gel method and a series of Ag/LiMn2O4 composites with different Ag additive contents were prepared by thermal decomposition of AgNO3 added to the pure LiMn2O4 powders. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX) and various electrochemical measurement methods were used to examine the structural and electrochemical characteristics of the Ag/LiMn2O4 composite powders. Phase analysis showed that Ag particles were dispersed on the surface of LiMn2O4 instead of entering the spinel structure. According to the electrochemical tests results, it is clearly to see that Ag additives efficiently improved the cycling stability, reversibility and high-rate discharge capacity of pristine LiMn2O4 by increasing the electrical conductivity between LiMn2O4 particles, decreasing the polarization of cathode and reducing the dissolution of Mn. Meanwhile the influence of the Ag additive contents on the electrochemical properties of the Ag/LiMn2O4 composites is also investigated in detail.

A novel chemical method based on ultrasonic assisted polyol synthesis for the fabrication of highly dispersed Pt nanoparticles on multi-walled carbon nanotubes (MWCNTs) was developed. The simple and green method took only about 10 min at ambient temperature. The structure and chemical nature of the resulting Pt/MWCNT composites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry (EDS). The results showed that the prepared Pt nanoparticles were uniformly dispersed on the MWCNT surface. The mean size of Pt nanoparticles was about 2.8 nm. Electrochemical properties of Pt/MWCNT electrode for methanol oxidation were examined by cyclic voltammetry (CV) and excellent electrocatalytic activities could be observed. The possible formation mechanism of Pt/MWCNTs was also discussed.

A simple method is devised to deposit highly monodispersed Ag nanoparticles (about 5 nm) on multi-walled carbon nanotubes (CNTs), which started from an initial modification of Ag nanoparticles with benzyl mercaptan molecules. By simply tuning the relative ratio of Ag catalyst to CNTs in solution, Ag/CNT composite with different Ag content can be achieved. The as-prepared Ag/CNT composite materials showed high electrocatalytic activity towards hydrazine oxidation, which was ascribed to the high dispersion of Ag nanoparticles on CNT surface.

Polyacrylonitrile-methylmethacrylate-carbon nanotubes (AMMA-CNTs) copolymer nanocomposites with different contents have been prepared by means of in situ polymerization process successfully. The AMMA-CNTs copolymer nanocomposites are desirable for many important applications. We measured the microhardness of the AMMA-CNTs copolymer nanocomposites. It was found that CNT could increase the microhardness of the nanocomposites effectively. A friction and wear tester under dry conditions investigated the tribological behaviors of the nanocomposites. Compared with pure AMMA, AMMA-CNTs copolymer nanocomposites showed not only smaller friction coefficient but also higher wear resistance. CNT could reduce the friction and improve the wear resistance behaviors of the nanocompsites dramatically. The mechanisms of the significant improvements on the tribological properties of the AMMA-CNTs copolymer nanocomposites were also discussed.

Palladium nanoparticles were crystallized on 4-aminobenzoic acid monolayer-grafted multi-walled carbon nanotubes (MWNT) by diazotization. The structure and nature of the resulting Pd/MWNT composite were characterized by transmission electron microscopy and X-ray diffraction, the results show that the chemically synthesized Pd nanoparticles were homogeneously dispersed and well-separated from one another on the modified MWNT surfaces. Cyclic voltammogram showed that the Pd-MWNT composite materials performed higher electrocatalytic activity and better long-term stability toward methanol oxidation in alkaline solution than Pd-C. The results imply that the Pd-MWNT composite materials as a promising support material improve the excellent electrocatalytic activity for methanol oxidation greatly. So the Pd/MWNT composites have a good application potential to fuel cells.

By use of the membrane-template synthesis route, MnO 2 nanowire arrayed electrodes are successfully synthesized by means of the anodic deposition technique. The Pt nanoparticles composited MnO 2 nanowire arrayed electrodes (PME) are obtained through depositing Pt on MnO 2 nanowire arrayed electrode by cathode deposition technique. For comparison of electrochemical performance, Pt nanowire arrayed electrodes which have the same amount of Pt with PME are also prepared. The electro-oxidation of methanol on PME and Pt nanowire arrayed electrodes is investigated at room temperature by cyclic voltammetry, which show that about 110 mV decreased overpotential and 2.1-fold enhanced votammetric current are achieved on PME. The chronoamperometry result demonstrates that the resistance to carbon monoxide for PME is improved.

Embedding of carbon nanotubes in conducting polymeric matrices for various nanocomposites material is now a popular area. In this article, a concise chemical method has been described for the preparation of homogeneous nanocomposite of multi-walled carbon nanotube (MWNT)/polyaniline (PANI) by electrochemical codeposition. For this we functionalized the MWNTs via the diazotization reaction. This helped to disperse the nanotubes in aniline. The composite films were dispersed Pt by electrodeposition technique. The presence of MWNTs and platinum in the composite films was confirmed by XRD analysis and transmission electron microscopy (TEM). Four-point probe investigations revealed that the MWNT/PANI composite films exhibited a good conductivity. Cyclic voltammograms (CV) showed that Pt-modified MWNT/PANI composite films perform higher electrocatalytic activity and better long-term stability than Pt-modified pure PANI film toward formic acid oxidation. The results imply that the MWNT/PANI composite films as a promising support material improves the electrocatalytic activity for formic acid oxidation greatly.

A new hybrid electrochemical capacitor has been successfully designed by using Co(OH)2/USY composite and active carbon (AC) as positive and negative electrode, respectively. The Co(OH)2/USY composite material is cobalt hydroxide loaded on ultra-stable Y zeolite (designated Co(OH)2/USY) through self-directed growth process. The Co(OH)2/USY and AC electrodes were individually tested in 1 M KOH aqueous electrolyte in order to define the adequate balance of active materials in the capacitor as well as the working voltage. To fabricate the hybrid cell systems, it achieved the maximum capacitive performance of 110 F/g, which is the highest value compared with the other similar metal oxide in AC hybrid capacitor systems in the same medium. Also it was found that the asymmetric cell worked in the larger voltage range and exhibited higher energy and power characteristics. The notable improved electrochemical performances strongly suggest that the hybrid cell can be a promising capacitor devices applied for the energy storage.

Since the last decade, most research focus in the fields of science and engineering has been dramatically shifted toward the same fashion from the investigation of traditional macroscale properties of materials to their atomic scale level (or called nanoscale). It is believed that the mechanical, electrical and thermal properties of materials, at their nanoscale level are totally different with that measured at macro and micro scale levels due to an assumption of their perfect atomic architectures, i.e., no-defect among atoms. In such circumstance, the strength of the materials can therefore reach to their ideal level since the maximal bonding energies among the atoms can be achieved. Recently, numerous researches have been focused on using nanomaterials as reinforcements to strengthen polymer-based composites for space and bio-engineering applications. Carbon nanotubes are the most common types of nanomaterials that have been used to mix with polymer to form nanocomposites. The nanotubes possess superior mechanical strength and electrical conductivity at specified chiral arrangements for producing high strength conductive polymers. In this paper, a critical review, based on the works done by authors and other researchers on the properties and applications of the carbon nanotubes for space and bio-engineering applications is given. Their advantages and disadvantages on some particular applications are also discussed in detail.

Multi-walled carbon nanotubes (MWCNTs) were functionalized via π − π interaction with benzyl mercaptan. The subsequent bonding of thiol groups with Pt offered strong adhesion of Pt nanoparticles on MWCNT surface. Thermal treatment was introduced as the essential step of the catalyst preparation. The structure and morphology of the resulting Pt/MWCNT composite were characterized by transmission electron microscopy and X-ray diffraction, the results show that Pt nanoparticles were highly dispersed and effectively adhered on MWCNTs. The excellent electrocatalytic activity of the Pt/MWCNT composite for the oxidation of methanol was demonstrated by cyclic voltammetry.

After the siloxane is polymerized on the nanotube surfaces, the carbon nanotube is embedded within the polysiloxane shell with a hydrophilic amino group situated outside. Platinum (Pt) nanoparticles were synthesised on as-produced noncovalent functional multi-walled carbon nanotubes (MWNTs) via electrostatic interactions. The structure and nature of the resulting Pt/MWNT composite were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic properties of the Pt/MWNT electrode for oxidation of ethanol have been investigated by cyclic voltammetry (CV), and excellent electrocatalytic activity can be observed.

A new method of synthesis of highly dispersed Pt nanoparticles with large catalytic surface area on multi-walled carbon nanotubes (MWCNTs) under high-intensity ultrasonic field was developed. The method, with low processing temperature at 25 °C, took only about 5 min. The surface characterization of MWCNTs was carried out by fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy methods. The electrochemical surface area and pore volume of MWCNTs were also examined. The result showed that functional groups of the MWCNTs which favored the high loading and high dispersion of particles and electrochemical surface area of MWCNTs were reinforced in the case of high-intensity ultrasonic field. The Pt/MWCNT catalysts were characterized by energy dispersion X-ray spectra analysis (EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. The prepared Pt nanoparticles were uniformly dispersed on the MWCNT surface. The mean size of Pt particles was 3.4 ± 0.2 nm. The electrocatalytic properties of Pt/MWCNT composites and kinetic characterization for methanol electro-oxidation were investigated by cyclic voltammetry. The Pt/MWCNT catalysts prepared for 5 min in ultrasonic field present excellent electrochemical activities. The schematic of the reaction was also introduced.

Polyaniline/multi-walled carbon nanotubes composites were synthesized by an in situ chemical oxidative polymerization method and were the new electrode materials used for supercapacitor. The composites were characterized physically by transmission electron microscope and X-ray diffraction. The electrochemical capacitance performance of the composites in neutral solution (NaNO 3 ) was investigated by cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy with a three-electrode system. The polyaniline/multi-walled carbon nanotubes composites electrodes showed much higher specific capacitance (328 F g −1 ), better power characteristics and were more promising for application in capacitor than pure polyaniline electrodes. This may be attributed to the introduction of multi-walled carbon nanotubes. The improvement mechanisms of multi-walled carbon nanotubes in the composites electrode were also discussed in detail.

Single-walled carbon nanotubes (SWNTs)/polyaniline (PANI) composite films with good uniformity and dispersion were prepared by electrochemical polymerization of aniline containing well-dissolved SWNTs. The composite films were dispersed Pt by electrodeposition technique. The presence of SWNTs and platinum in the composite film was confirmed by XRD analysis and scanning electron microscopy (SEM). Four-point probe investigation and electrochemical impedance spectroscopy (EIS) revealed that the well arrangement of PANI coated SWNTs in these films enhanced electric conductivity and facilitated the charge-transfer of the composite films. Cyclic voltammogram (CV) and chronoamperogram showed that Pt-modified SWNT/PANI composite film performs higher electrocatalytic activity and better long-term stability than Pt-modified pure PANI film toward formaldehyde oxidation. The results imply that the SWNT/PANI composite film as a promising support material improves the electrocatalytic activity for formaldehyde oxidation greatly.

4-Aminobenzoic acid was covalently grafted on multi-walled carbon nanotubes (MWNTs) by amine cation radical formation in the electrooxidation process of the amino-containing compound. Then, silver (Ag) nanoparticles were electrocrystallized on 4-aminobenzoic acid monolayer-grafted MWNTs by a potential-step method. The structure and nature of the resulting Ag/MWNT composites were characterized by transmission electron microscopy and X-ray diffraction. The electrocatalytic properties of the Ag/MWNT electrode for hydrazine oxidation have been investigated by cyclic voltammetry, high electrocatalytic activity of the Ag/MWNT electrode can be observed. This may be attributed to the small particle size of the silver particles. The results imply that the Ag/MWNT composites have a good application potential in fuel cells. Keywords: 4-Aminobenzoic acid, MWNTs, Ag nanoparticles, Hydrazine

The silver seed on silicon was prepared through aqueous HF and AgNO solution at room temperature. In order to explore the formation process of silver seed on silicon, the methods of open circuit potential with time (OCP-t), anodic stripping sweep voltammetry (ASV) and scanning tunneling microscope (STM) were used in this work. The procedure of silver nucleus growing into large particles was explained by electro-negativity. The growth mechanism of silver seed on silicon has been presented: at first, the silver monolayer and multilayer firstly grows onto silicon without fully covering the surface at the expense of silicon etching due to the silver seed attracting the electron from silicon, after that, the monolayer coalesces together, forming continuous grain film with some silver atoms diffusing into the silicon and the multilayer still grows thick simultaneously. © 2007 SIOC, CAS, & Wiley-VCH Verlag GmbH & Co. KGaA.