Mechanical and erosion properties of CaCO3‐EMAA thermal sprayed coatings

Polymer‐ceramic composite coatings manufactured from calcium carbonate and ethylene‐methacrylic acid copolymer (EMAA) were prepared via a thermal spray process employing different CaCO₃ filler sizes (average size of 2.8, 9 or 36 μm) and loading levels from about 2.5 to 7 wt%. The optimum filler feeding characteristics, deposition efficiency and deposition rate were obtained with a 36 μm sized CaCO₃. Tensile properties, peel strength, and the erosion resistance of a pure EMAA and CaCO₃‐EMAA composite coatings were investigated. It was found that the tensile strain at fracture of the composite coating decreased with the addition of filler to a greater degree than that observed in compression‐molded polymer composites. This is attributed to an inhomogenous distribution of the filler, with more being concentrated at the boundaries of the deposited polymer particles, thereby establishing a rigid framework within the coating. Only a small filler content is necessary to establish large changes in the mechanical properties of the coating. The peel strength of a composite coating decreases with filler content, both on a mild steel substrate and a previously sprayed polymer coating. Bonding to the latter is significantly higher and offers a possibility as a bonding layer between substrates and composite coatings. The coefficient of friction is lowered with the addition of a filler. Erosion testing has shown that the erosion resistance of PF111 is little improved overall with filler addition, although some increase is found for filler contents less than 5 vol%. Polym. Eng. Sci. 44:1448–1459, 2004. © 2004 Society of Plastics Engineers.     

Assessment of a redox alkaline/iron-chelate absorption process for the removal of dilute hydrogen sulfide in air emissions

The oxidative absorption of hydrogen sulfide (H₂S) into a solution of ferric chelate of trans-1,2- diaminocyclohexanetetraacetate (CDTA) was studied in a counter-current laboratory column randomly packed with 15 mm plastic Ralu rings. The present investigation takes concern about the Kraft pulping situation where dilute H₂S concentrations are omnipresent in large-volume gas effluents. A fractional two-level factorial approach was instigated to determine the significance of six operating variables, namely the solution's alkalinity (pH; 8.5-10.5), the liquid mass flow rate (L;1.73-), the solution's ionic strength (I_C;0.01-), the gas mass flow rate (G;0.19-), the inlet H₂S concentration (C_H2S,0;70-430 ppm) and the initial ferric CDTA concentration (C_Fe,0;100 -). Initially, a Plackett-Burman design matrix of seven duplicated experiments revealed that pH is the leading factor controlling the H₂S conversion rate while the ionic strength and ferric CDTA concentration effects remained negligible within the factorial domain. Surface response analysis based on 11 duplicated factorial experiments plus 10 central composite trials revealed that the H₂S conversion significantly increases with liquid flow rate but decreases with growing H₂S load up. Further examination about the influence of ferric CDTA on H₂S absorption rate was set up over a broader concentration range (C_Fe,0;0- at pH of 9.5 and 10.5. It showed good potential at as H₂S conversion increased by a significant 25% for both pH values in comparison to pure alkaline solutions containing no ferric CDTA.     

A biomarker of n−3 compliance in patients taking fish oil for rheumatoid arthritis

Dietary fish oil supplements have been shown to have benefits in rheumatoid arthritis (RA), other inflammatory diseases, and in cardiovascular disease. As with any medical advice, variability will exist with regard to adherence and consequent biochemical or pharmacophysiologic effects. The aim was to explore the utility of plasma phospholipid EPA as a measure of n−3 PUFA intake and response to standardized therapeutic advice given in an outpatient or office practice setting, to increase dietary n−3 PUFA, including a fish oil supplement. Patients with early RA were given verbal and written advice to alter their dietary n−3 PUFA intake, including ingestion of 20 mL of bottled fish oil on juice daily. The advice included instructions to increase n−3 PUFA and to avoid foods rich in n−6 PUFA. Every 3 mon, blood samples were obtained for analysis of plasma phospholipid FA. Plasma phospholipid EPA was used as the primary index of n−3 PUFA intake. A diverse response was seen, with about one-third of patients achieving a substantial elevation of plasma phospholipid EPA over the 12-mon study period. A third had little change, with the remainder achieving intermediate levels. Data obtained longitudinally from individual patients indicated that substantial elevations of EPA (>5% total plasma phospholipid FA) could be maintained for more than 3 yr. Plasma phospholipid EPA is a convenient measure of adherence to advice to take a dietary n−3 PUFA-rich fish oil supplement. This measure may prove a useful adjunct to intention to treat analyses in determining the effect of dietary fish oil supplements on long-term outcomes in arthritis and other chronic inflammatory diseases. It may also provide a guide to the effectiveness of therapeutic and preventive messages designed to increase n−3 PUFA intake.     

Der Sicherheitsaspekt beim Eintrag von Schüttgütern in Behälter

Safety aspects of charging bulk material into vessels or containers . The safe charging of bulk material requires a careful analysis of the potential sources of danger which can result from the physical properties of the materials and the design and construction material of plant and equipment. The method adopted in this analysis is illustrated and explained for selected examples. Criteria for safe charging methods are compiled and explained. A selection of proven charging equipment is listed and technically evaluated with respect to safety and operating criteria. Steps that must be taken to avoid charging errors are discussed. Special problems encountered on connecting pressureless charging devices to pressure vessels are outlined explained. The utilization of inert gas as a preferred method of explosion protection is discussed. Various methods are compared, and their application to special problems in charging bulk material is illustrated.     

Receptance coupling for end mills

Identification of chatter free cutting conditions, the chatter stability lobes, requires a measurement of the frequency response function (FRF) of each tool mounted on the spindle. This paper presents a method of assembling known dynamics of the spindle–tool holder with an analytically modeled end mill using the receptance coupling technique. The classical receptance technique is enhanced by proposing a method of identifying the end mill–spindle/tool holder joint dynamics, which include both translational and rotational degrees of freedom. The method requires measurement of FRFs with impact tests applied on the spindle–tool holder assembly and blank calibration cylinders attached to the spindle. The spindle and tool holder characteristics are completely identified from the two experiments, and used for the mathematical prediction of FRF for end mills with arbitrary dimensions. The proposed method is experimentally proven and verified in cutting tests.     

Effects of ring substituents on the protective properties of self-assembled benzenethiols on copper

The self-assembled monolayers (SAMs) of a series of substituted benzenethiol (BT) molecules, X-C₆H₄-SH (where X = meta-NH₂, ortho-NH₂, para-NH₂, para-NHCOCH₃, para-F, para-CH₃ and para-CH(CH₃)₂), have been prepared by adsorption from a solution onto a fresh copper (Cu) surface pretreated by a nitric acid etch. The corrosion inhibition efficiency of the modified Cu surfaces in a sulfuric acid solution was investigated by electrochemical characterization. The protection afforded by the substituted functional groups on BT is strongly influenced by the type and the position of the substituent on the benzene ring. BT molecules without any substituent group on the ring are ineffective corrosion inhibitors, indicating that the chemical configuration is the key factor in determining the efficacy of the SAMs as barriers to electrochemically corrosive ions. It is further proposed that the steric hindrance offered by the substituted group in the SAMs plays a very important role in determining its barrier properties.     

Influence of diurnal and seasonal temperature variations on the detection of corrosion in reinforced concrete by acoustic emission

Chloride rich reinforced concrete prisms were coupled to chloride-free prisms and exposed to diurnal and seasonal temperature cycles typical of those found in the UK. Acoustic emissions (AE) and galvanic currents were continuously monitored and correlated with ambient temperature. AE and galvanic currents were found to emulate the evolution of temperature in the diurnal cycles, although no specific relationship between AE and galvanic current could be obtained. The influence of seasonal variations in galvanic current had no obvious influence on AE Energy per second over the range of corrosion rates studied. The findings suggest that AE is more sensitive to short term (diurnal) changes in corrosion rates than the longer (seasonal) effects. It was hypothesised that this is due to transitory changes in the internal microclimate of the concrete.     

Evolution-in-materio: solving computational problems using carbon nanotube–polymer composites

Evolution-in-materio uses evolutionary algorithms to exploit properties of materials to solve computational problems without requiring a detailed understanding of such properties. We show that using a purpose-built hardware platform called Mecobo, it is possible to solve computational problems by evolving voltages and signals applied to an electrode array covered with a carbon nanotube–polymer composite. We demonstrate for the first time that this methodology can be applied to function optimization and also to the tone discriminator problem (TDP). For function optimization, we evaluate the approach on a suite of optimization benchmarks and obtain results that in some cases come very close to the global optimum or are comparable with those obtained using well-known software-based evolutionary approach. We also obtain good results in comparison with prior work on the tone discriminator problem. In the case of the TDP we also investigated the relative merits of different mixtures of materials and organizations of electrode array.