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This study aims to investigate photosensing characteristics of SiC and GaN nanowire-based devices through exposure to UV light. The photocurrent transients have been modeled to determine rise and decay process time constants. The 1D-semiconductor nanowires can exhibit higher light sensitivity compared to bulk materials because of their large surface area to volume ratio and the quantum size effects.

Nanowire devices have been fabricated through dielectrophoresis for integrating nanowires onto pre-patterned electrodes (10 nm Ti/ 90 nm Au) with a spacing about 3 µm onto SiO₂/Si (doped) substrate. The photocurrent measurements were carried out under room temperature conditions with UV light of 254 nm wavelength.

SiCNWs yield very short rise and decay time constants of 1.3 and 2.35 s, respectively. This fast response indicates an enhanced surface recombination of photoexcited electron-hole pairs. Conversely, GaNNWs yield longer rise and decay time constants of 10.3 and 15.4 s, respectively. This persistent photocurrent suggests a reduced surface recombination process for the GaNNWs.

High selective UV light sensitivity, small size, very short response time, low power consumption and high efficiency are the most important features of nanowire-based devices for new and superior applications in photodetectors, photovoltaics, optical switches, image sensors and biological and chemical sensing.

A method for rapid prototyping based on electrophotographic powder deposition was investigated to study its potentials and to identify design and implementation challenges. This technique is referred to here as the electrophotographic rapid prototyping (ERP). In this technique, powder is printed layer‐by‐layer in the shape of the cross‐sections of the part using electrophotography a very widely used non‐impact printing method. Each layer of powder is consolidated by fusing before the next layer of powder is printed. A fully automated test bed was constructed that consists of a printing system, fusing/heating plate, build platform that has two‐degrees of freedom as well as software that drives the system.

A solid freeform fabrication (SFF) technique is described where powder is deposited layer‐by‐layer using electrophotographic printing. In the electrophotography process, powder is picked up and deposited using an electrostatically charged surface. A test bed was designed and constructed to study the application of electrophotography to SFF. It can precisely deposit powder in the desired shape on each layer. A polymer toner powder was used to build small components by thermally fusing each layer of printed powder using a hot compaction plate. The feasibility of 3D printing using this approach was also studied by printing a binder powder using electrophotography on to a part powder bed.

Water‐borne coatings Increasing use of water‐borne emulsion coatings for original equipment manufacturers (OEM) and product finishes is requiring greater efficiency in coalescing‐aid solvents, an Eastman Chemical Co. representative said at a recent Chicago Society for Coatings Technology meeting. Eastman's Ronald K. Litton said emulsions designed for OEM and industrial applications have higher glass transition temperatures than emulsions used in architectural paints. That requires higher levels of coalescing aid to achieve good film formation. As a result, coalescing‐aid efficiency with a given emulsion system is a key factor, both from environmental (lower‐volatile organic compound (VOC)) and economic standpoints. Several properties should be examined when a coalescing aid is selected for water‐borne emulsion industrial coatings. The formulator should consider the evaporation rate and solubility parameter of the coalescing aid, along with its distribution pattern in a specific emulsion system. Those properties are important in defining the efficiency of a coalescing aid in terms of its ability to lower the minimum film‐forming temperature (MFFT) of an emulsion system. The coalescing aids also must be hydrolytically stable to provide minimum loss of efficiency due to ageing, Litton said. He showed several charts designed to assist formulators in the selection of optimum coalescing aids for emulsion systems. At the same conference, James T.K. Woo of The Glidden Co. discussed the grafting of high‐molecular‐weight epoxy resins with styrene‐methacrylic acid monomers, producing a water‐reducible copolymer. Grafting takes place at the aliphatic carbons of the epoxy resin, according to carbon‐13 NMR spectroscopy. The study was a follow‐up to a paper presented 14 years ago. Woo said recent research indicates that five grafting “peaks” were identified on a 400 megacycle carbon‐13 nuclear magnetic resonance spectroscopy instrument. The paper provided several theoretical calculation on grafting. Three of the graft peaks resulted from grafting at the secondary methylene carbons ‐CH2‐ and two resulted from grafting at the tertiary carbon ‐CH‐. The ratio of grafting at ‐CH2‐ to ‐CH‐appears to be 2.7:1 — lower than the 4:1 ratio of protons present on the aliphatic carbons that are susceptible to hydrogen abstraction leading to grafting. That indicates that the tertiary hydrogen is somwhat more susceptible to grafting than the methylene hydrogens, he said.

The purpose of this paper is to investigate the effect of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on improvement of physical and electrical properties of vanadyl phthalocyanine derivative. The correlation between the physical characteristics of the active layers, comprising vanadyl 2,9,16, 23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO) and PCBM, and the electrical properties of metal/organic/metal devices have been studied. The use of soluble vanadyl phthalocyanine derivative makes it very attractive for a variety of applications due to its tunable properties and high solubility.

The sandwich type structures Al/VOPcPhO/Al and Al/VOPcPhO:PCBM/Al were fabricated by spin casting the active organic layers between the top and bottom (aluminum) electrodes. The stand-alone (VOPcPhO) and composite (VOPcPhO:PCBM) thin films were characterized by X-ray diffraction, atomic force microscopy, UV/Vis and Raman spectroscopy. The electronic properties of the metal/organic/metal devices were studied using current-voltage (I-V) characteristics in dark at room temperature.

The values of barrier height for Al/VOPcPhO/Al and Al/VOPcPhO:PCBM/Al devices were obtained from the forward bias I-V curves and were found to be 0.7 eV and 0.62 eV, respectively. The present study indicates that the device employing VOPcPhO:PCBM composite film as the active layer, with better structural and morphological characteristics, results in reduced barrier height at the metal-organic film interface as compared to the one fabricated with the stand-alone film.

It is shown that doping VOPcPhO with PCBM improves the crystallinity, morphology and junction properties.

The spin coating technique provides a simple, less expensive and effective approach for preparing thin films. The soluble VOPcPhO is conveniently dissolved in a number of organic solvents.

The physical properties of the VOPcPhO:PCBM composite thin film and the electrical properties of the composite thin-film-based metal/organic/metal devices have not been reported in the literature, as far as our knowledge is concerned.

Sensors for industrial inspection exploit many basic properties of materials, which Clive Loughlin explains here in his second article on the subject.

Rheological Control Additives. Many additives to coatings affect the rheology of the composition so that application and storage properties are improved. A new rheological additive for emulsion polymers and water‐reducible resins has been described by Whitton and Masterson [Modern Paint & Coatings, November (1980) p. 33]. The authors point out that latex paints practically always require rheological additives if they are to have good application and stability properties. Without additives they are prone to dripping, sagging, and spattering as well as pigment settling, phase separation, and pigment flocculation. The most widely used rheological additives for waterborne coatings are cellulosic derivatives, and the authors estimate that 85 to 90% of latex trade sales coatings are thickened with additives such as hydroxyethylcellulose, methyl hydroxypropylcellulose, and methylcellulose. The disadvantages of these materials is that they are difficult to disperse which means that energy and time are consumed in grinding. Also, in automated pigment slurry systems the cellulosics require a large amount of water for dispersion. This limits flexibility in formulation. Also, the cellulosics can be attacked by enzymes although more expensive enzyme‐resistant forms are available.

The purpose of this paper is to develop a sensitive and cost effective colorimetric sensor for detection of methyl parathion (MP) using simple circuitry. A simple and sensitive concept of colorimetric sensor instrument represents a rapidly expanding field of sensor techniques to monitor MP neurotoxins is described within certain conditions of producing color in samples. The variation of intensity of color with concentration provides discrimination between different concentrations of MP. The colorimetric instrument displays well‐defined signals towards hydrolyzed samples of MP.

The principle of light intensity measurement has been applied to measure various concentrations of MP based on Lambert‐Beer theory. This device and its processes are useful for quantitative analysis of MP. The detection limits were found within a range of 0.1‐1.5 ppm.

The experiments from sophisticated analytical techniques are costly and time‐consuming processes that validate the proposed system.

This paper's original proposition of using quantification of MP with colorimetric sensor instrument obtained promising results.

The colorimetric sensor instrument provides a new method for quantification of MP in unknown samples within detection limits.

The purpose of this paper is to investigate in situ modification of cyclohexanone‐formaldehyde resins (CFR) by 4‐vinyl aniline (Van). The roles of the reaction temperature, the conductivity, thermal properties, and molecular weight of the product were investigated. CFR was in situ modified with VAn in the presence of sodium hydroxide. Ketonic resin‐bound 4‐vinyl aniline was synthesised with a one‐step method of in situ modification of ketonic resin. The roles of the reaction temperature and the conductivity of the product were investigated.

Ketone, formalin (37% aqueous solution), vinyl aniline were mixed and then 20% aqueous NaOH solution was added to produce the resin. The solubility, molecular weight and thermal properties of the products were investigated.

The 4‐vinyl aniline modified cyclohexanone‐formaldehyde resins were found to have conductivity values of 10⁻⁴ and 10⁻² S/cm and may be considered as conductive ketonic resin. Soluble and processable conductive ketonic resins were developed.

The reaction mixture of CFR must be stirred continuously at low temperature. Subsequently, 37% formalin was added dropwise in equal portions while refluxing. Temperature should be controlled to prevent the thermal polymerisation of vinyl group and higher branching of amino groups. The amount of vinyl aniline used in reaction mixture is limited since the formed resin may become insoluble in common organic solvents.

This study provides technical information for the synthesis of conducting resins. The modified resins contain vinyl groups. The chemical redox or radical system can be used to polymerise these vinyl groups and resins with much higher molecular weight may be produced. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating.

Vinyl aniline modified cyclohexanone formaldehyde resins have been synthesised in the presence of a basice catalyst. These soluble and conductive resins may overcome difficulties in the applications of conducting polymers and open new application areas. Therefore, the vinyl aniline modified resin may find a number of new application areas, as well as existing conducting resin and polymer applications.

This paper aims to report the synthesis of resins having fluorescence properties, with the help of phenylacetylene (PhAc) by one-step method of in situ modification of ketonic resin. Cyclohexanone-formaldehyde resin (CFR) and acetophenone formaldehyde resin (AFR) were in situ modified with PhAc, in presence of sodium hydroxide (NaOH) by condensation polymerisation.

Ketone, formalin and phenylacetylene were mixed and then 20% aqueous NaOH solution was added to produce the phenylacethylene modified ketonic resin. The solubility, molecular weight and thermal properties of the products were investigated.

These new PhAc-modified ketonic resins (PAc-CFR and PAc-AFR) have fluorescence properties.

This study focuses on obtaining a fluorescence resin using a cyclohexanone, acetophenone and PhAc monomer which is an insulator.

This study provides technical information for the synthesis of fluorescence comonomers. The modified resins contain acetylene groups. A chemical redox or radical system can be used to polymerise these acetylene groups and resins with much higher molecular weight. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating.

The resins will be used for the preparation of AB- and ABA-type block copolymers. These block copolymers may exhibit different properties due to incorporation of monomer into the block copolymer structure.

PAc-CFR and PAc-AFR have been synthesised in the presence of a basic catalyst. Higher solubility and fluorescence intensity of the modified ketonic resins may increase their applications in the field of electroactive polymers and open new areas. These comonomers have fluorescence property.