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The arc discharge method has been used hitherto to encapsulate metal-containing structures within carbon nanotubes 1 , 2 , the arrangement of the nanotube walls playing an important role in the process. We show that KCl can be generated in the space between nanotube walls by treating potassium-intercalated uncapped tubes with CCl4. A relationship between the KCl crystal domain and the hexagonal carbon network is thought to give rise to preferential formation of a 100 plane perpendicular to the tube axes.

New advances have been made in the creation of nanostructured materials by pyrolytic and electrolytic methods. These experiments have shown that a wide range of nanostructures can be made using imaginative approaches. ALIGNED NANOTUBES VIA PYROLYTIC ROUTES Laser etching of thin cobalt ®lms (Fig. 1) provides a novel route to catalysts which, in conjunction with the pyrolysis (Fig. 2) of organic precursors yield to partly aligned nanotubes of uniform length ( 1 H. W. Kroto, D. Walton, M. Terrones, N. Grobert, J. Olivares, J. P. Zhang, H. Terrones, K. Kordatos, W. K. Hsu, J. P. Hare, P. D. Townsend, K. Prassides, A. K. Cheetham, H. W. Kroto, D. R. M. Walton. Nature 388, 52 (1997). 2 M. Terrones, N. Grobert, J. P. Zhang, H. Terrones, J. Olivares, W. K. Hsu, J. P. Hare, A. K. Cheetham, H. W. Kroto, D. R. M. Walton. Chem. Phys. Lett. 285, 299 (1998). 3 M. Terrones, P. Redlich, N. Grobert, S. Trasobares, W. K. Hsu, H. Terrones, Y. Q. Zhu, J. P. Hare, C. L. Reeves, A. K. Cheetham, M. RuEhle, H. W. Kroto, D. R. M. Walton. Adv. Mater. (1999). In press. 4 W. K. Hsu, J. P. Hare, M. Terrones, H. W. Kroto, D. R. M. Walton, P. J. F. Harris. Nature 377, 687 (1995). 5 W. K. Hsu, M. Terrones, H. Terrones, N. Grobert, A. I. Kirkland, J. P. Hare, K. Prassides, P. D. Townsend, H. W. Kroto, D. R. M. Walton. Chem. Phys. Lett. 284, 177 (1998). 6 W. K. Hsu, J. Li, H. Terrones, M. Terrones, N. Grobert, Y. Q. Zhu, S. Trasobares, J. P. Hare, C. J. Pickett, H. W. Kroto, D. R. M. Walton. Chem. Phys. Lett. 301, 159 (1999). 7 Y. Q. Zhu, W. K. Hsu, M. Terrones, N. Grobert, H. Terrones, J. P. Hare, H. W. Kroto, D. R. M. Walton. J. Mater. Chem. 8, 859 (1998). 8 Y. Q. Zhu, W. K. Hsu, W. B. Hu, M. Terrones, N. Grobert, J. P. Hare, H. W. Kroto, D. R. M. Walton, H. Terrones. Adv. Mater. (1999). In press. 9 N. Grobert, M. Terrones, A. J. Osborne, H. Terrones, W. K. Hsu, S. Trasobares, Y. Q. Zhu, J. P. Hare. Appl. Phys. A 67, 595 (1998). 2130 N. GROBERT et al. q 1999 IUPAC, Pure Appl. Chem. 71, 2125±2130 Fig. 11 TEM images of ®ve representative needle-like structures which were almost completely ®lled with Ni. Fig. 12 HRTEM image of a highly graphitised Ni-®lled carbon nanotube. The quality of graphitisation is unusual for pyrolytically grown materials.

In a manufacture system, the inventory control is one of important issues. This paper proposes a fuzzy economic order quantity (EOQ) inventory model for solving the inventory control problem in the manufacture system. Firstly, this paper discusses the square roots of a trapezoidal fuzzy number. Secondly, the square root of fuzzy number is applied to the EOQ inventory model in the manufacture system.

Research has demonstrated that the structure and properties of a nanoscale system are inextricably linked. The advent of nanoscale research in 1991 relied upon nanoscale material production through random formation techniques, such as arc discharge, and the inherent properties and morphology of the system were therefore difficult to control. This article reviews some of the methods and ideas that have developed since the inception of nanotechnology, leading to fine control over the morphology of nanoscale systems and highlighting some interesting nanoscale architecture.

The origin of electromagnetic induction from Fe-filled carbon nanotube–polymer composites has been verified using ac impedance spectra. Results clearly indicate that the electron pathway is spiral around the nanotubes.

Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.

Novel composite nanotubes, consisting of NbS2-sheathed carbon nanotubes (CNTs), have been generated successfully employing carbon nanotube template-promoted growth. Detailed experimental procedures, and the associated intermediate oxide phases during NbS2 conversion, have been evaluated using high-resolution transmission electron microscopy, coupled with EDX analysis. Our results show that CNTs act as templates and that the uniform well-crystallized NbS2 nanotubes are produced from unevenly wrapped NbO2. A multi-point nuclei site growth mechanism has been proposed to account for nanotube formation.

Multi-walled carbon nanotubes (MWCNs), coated with ordered WS2 mono- or multi-layers, are generated by pyrolysing H2S/N2 over MWCNs thinly coated with WO3. High-resolution transmission electron microscopy (HRTEM) reveals the presence of hexagonal WS2 arrays in the tube surface, consistent with the WS2 simulated structure.

A range of elegant tubular and conical nanostructures has been created by template growth of (WS2)n layers on the surfaces of single-walled carbon nanotube bundles. The structures exhibit remarkably perfect straight segments together with interesting complexities at the intersections, which are discussed here in detail in order to enhance understanding of the structural features governing tube growth.

Nb-doped WS2 nanotubes, typically W 1−x Nb x S 2 (x⩽0.2) , generated by heating Nb2O5-coated W18O49 nanorods in H2S at 1100°C, contain more structural defects within the layers than do pure WS2 nanotubes. The tube tips are invariably closed. The presence of Nb appears to inhibit nanotube formation. A two-stage process is proposed to account for the observed doped nanotube growth.

Mixed-phase WxMoyCzS2 nanotubes are generated when N2/H2S is passed over a preoxidized mixture of WC and MO2C, maintained at an elevated temperature.

Stable filaments of nanometer dimensions with overall chemical stoichiometry close to BC 2 N were generated by pyrolysis of CH 3 CN·BCl 3 over Co at 1000°C and, for the first time, their structures were investigated, at the nanometer level, using high spatial resolution electron energy-loss spectroscopy. Concentration profiles, along and across the filaments, revealed that B, C and N are not homogeneously distributed within the nanostructures but are separated into pure C and BN domains. Interestingly, pure h-BN layers are always sandwiched between graphite-like shells. A two-stage growth process is proposed involving: (a) initial extrusion of a pure carbon filament from the catalytic particle, followed by (b) subsequent thickening of the BN and C layers precipitated from the gas phase. This pyrolytic technique provides an alternative and efficient route to segregated BN/C nanomaterials, which may prove useful as robust nanocomposites and semiconductor nanodevices with enhanced resistance towards oxidation.

Pyrolysis of CH3CN · BCl3 at ca. 900–1000°C over Co powder generates novel graphitic BxCyNz nanofibres and nanotubes possessing a range of morphologies (e.g. curled, branched and bent). In these experiments the metal particles play an important role in the growth since nanotube formation appears to occur at the metal surface. High resolution electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) studies suggest that the stoichiometry of the filaments is ca. [BC2Nz]n (z = 0.3−0.6). Higher relative concentrations of carbon occur at the tips where the metal particle is found. A possible growth mechanism for these new materials is proposed.

Low threshold fields of 1.6 V/μm and 2.6 V/μm were obtained for field emission from multiwalled carbon nanotubes and boron-doped multiwalled carbon nanotubes embedded in polystyrene, respectively. A Fowler–Nordheim analysis of the results together with sheet resistivity data illustrate that the higher carbon nanotube concentrations in a polystyrene matrix result in larger effective emission areas, at the expense of higher operating threshold fields.

Removal of the carbon template from WS2-coated multi-walled carbon nanotube (MWCN) composites, produced WS2 nanotubes with intriguing microstructures. TEM characterisation shows that the intermediate phases of amorphous WO3−x-WS2 nanostructures, support the previously proposed growth model for WS2 nanotubes on MWCNs.

Single-walled carbon nanotubes (SWCNs) encapsulated in multiwalled WS2 nanotubes are produced by pyrolyzing a mixture of WO3−x and SWCNs in N2/H2S atmosphere.

Composite C-MoS2 and C-WS2 nanostructures were produced by pyrolysing H2S/N2 over a mixture of MoO3 (or WO3) and carbon particles/nanotubes. MoS2 particles embedded in the nanotubes were also observed occasionally.

Hollow fibres of crystalline W18O49, arranged in a pine-tree-like structure, were generated by heating WS2 powder in oxygen. SEM, TEM, X-ray and electron diffraction studies show that the individual fibres are composed of single-crystal tungsten oxide whiskers. One-dimensional growth, involving heat dissipation along the fibre axis, is proposed.

The MPS (master production schedule) is the most important plan that a foundry can develop for production, inventory, staffing, etc. It sets the quantity of each end-item to be completed during each specific period of a short-range planning horizon. In the past, the production control engineers in a semiconductor foundry normally provided a monthly MPS plan. However, this was thought to be too inflexible, because the foundry's customer delivery requirements were continually changing, with a variety of different and urgent requests to meet the consumer market. A foundry needs to rapidly calculate and simulate its capacity, and attempt to fulfil the delivery requirements of every customer, and has become a very important issue within the semiconductor industry. In recent years, many foundries have established a supply chain feasibility study group, and have begun to study the best solutions to integrated supply chain management system issues that provide total customer-oriented internal planning and the execution of business processes. After several years of effort, the automatic MPS was successfully implemented in certain foundries. It became possible to have a flexible daily updated MPS that included input related to capacity status, the most updated order information and WlP balance, and the net results. The foundry could then follow the up-to-date data to meet its delivery goals, providing a major enhancement to the most important aspect of customer service-delivery

An anaerobic/aerobic activated sludge system under dynamic loading is difficult to automatically control due to its ill-defined non-linear, and complex behavior. This study demonstrates the merits of a real-time fuzzy logic controller for such control purposes by comparing it with a conventional proportional (F/M)/sub an/ controller. Using the conventional system alongside our proposed system continuous-flow pilot plant experiments with automatic monitoring and control facilities were carried out. Five effluent parameters (dissolved COD, dissolved P, total SS, total COD, and total P) were utilized to evaluate their dynamic system performance. Experimental results indicate that, compared to conventional (F/M)an control. Fuzzy logic control significantly improve the effluent concentration.

Non-thermal plasma application for the synthesis of customized carbon nanotubes (CNTs) is reviewed. Carbonaceous nanostructures were deposited via a dielectric barrier discharge chemical vapor deposition using various mixtures of plasma gases and carbon-bearing reactants. Aligned carbon nanofibers/tubes (20–50 nm in diameter) were generated by hollow cathode glow discharge plasma decomposition of ferrocene in helium atmosphere on an alumina membrane. The average temperature in the reaction zone, determined by the optical emission spectroscopy, was below 200 °C. The as- deposited product consists of bundles of amorphous carbon nanofibers. Heating at 1100 °C under Ar produced well-crystallized carbon nanotubes.

A binary phase of layered nanotubes, where MWCNs (Multi-walled carbon nanotubes) are coated by WS2, are generated by pyrolysing WO3-coated MWCNs in an H2S/N2 atmosphere at 900 °C. TGA and TEM show that WS2 acts as an antioxidant with respect to the MWCN core.

The morphological and structural features of WS2 nanotubes, generated from WOx (x ≅ 2.7) needles, by an in-situ heating process, have been studied by electron microscopy and X-ray diffraction (XRD), in conjunction with computer simulation. The results show that these inorganic fullerene nanotubes exhibit interesting differences when compared with carbon nanotubes (CNTs). In some cases the tube tips or segments are open. Occasionally the tube walls may be uneven. The sulfur distribution within the tubes is uniform, except for the edge layers which appear to contain less sulfur. Defects are often observed, particularly in the outer shells, which may be due to defective encapsulated WOx phases. Octagonal and square-like defects appear to be associated with the closure of tube caps. Electron diffraction (ED) reveals that nearly half of the non-helical WS2 nanotubes are of the armchair-type. A mechanism has been proposed to account for the extended inorganic nanotube growth.

Carbon-encapsulated Sn−Pb nanowires are generated by electrolysis of graphite in molten LiCl containing these metals. SA-EDX analyses indicate a distinctive profile for the metal cores in which Sn predominates at one end and Pb at the other of the individual nanowires; X-ray diffraction measurements reveal that separate crystals of each metal can be distinguished, thus zone refining has occurred. The cores exhibit dynamic behavior under electron irradiation. A growth mechanism is proposed for the nanowires.

and Ni deposited on a silica plate at 950 °C. High-resolution transmission electron microscopy (HRTEM) studies reveal that these tapered structures are almost completely filled with Ni and are closed at both ends. The diameters of the needles (2–5 μm in length) range between 10–20 nm at one end and 30–200 nm at the other. A surprisingly high degree of graphitization is observed in the walls of the nanotubes. These unique structures may prove useful as electrodes with various applications such as precision probes in biological systems or scanning tunnelling microscope tips.

Pyrolysis of 2-amino-4,6-dichloro-s-triazine over laser-etched thin films of cobalt deposited on an inverted silica substrate generates aligned bundles and films of carbon nanotubes of uniform dimensions. Scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray analyses, electron energy loss spectroscopy and electron diffraction studies reveal that the aligned tubes, which usually grow perpendicular to the substrate surface, are mainly straight (length ⩽100 μm; 30–50 nm OD), contain traces of nitrogen (

We report a high-yield route to two-dimensional arrays (

The extent of nanotube formation arising from the electrolysis of molten LiCl, using graphite electrodes, is reduced by the addition of salts to the electrolyte. In certain cases (99% LiCl+