Thermodynamic Modeling as a Strategy for Casting High Alloy Steels

Strategies based on thermodynamic calculations can be used to overcome the problems associated with oxides encountered in steel plant operations, which can lead to certain difficulties in the process such as clogging of submerged entry nozzle during continuous casting. Approaches to producing high alloy steels by continuous casting have been taken. One of the strategies to avoid the oxidation of chromium is to add a small amount of other elements (subject to other constraints), which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and the results obtained for different process conditions or generic com-positions have been presented.     

Comparative numerical and experimental investigation of static and dynamic characteristics of composite plates

Journal of Mechanical Science and Technology - In order to investigate both static and dynamic characteristics of composite plates and validate a contemporary, non-invasive experimental technique a...     

Poly(N-hydroxymethyl acrylamide-co-acrylic acid) and poly(N-hydroxymethyl acrylamide-co-acrylamidoglycolic acid): synthesis, characterization, and metal ion removal properties

Macroreticular chelating resins containing carboxylic groups, poly(N-hydroxymethyl acrylamide-co-acrylic acid) P(HMA-co-AA) and poly(N-hydroxymethyl acrylamide-co-2-acrylamido glycolic acid) P(HMA-co-AGA) were synthesized by solution radical polymerization with ammonium persulfate as initiator and N,N′-methylene-bis-acrylamide as cross-linking reagent. The polymerization yield was 98.9 and 91.9% for P(HMA-co-AA) and P(HMA-co-AGA), respectively. The retention properties were studied under competitive and noncompetitive conditions by batch equilibrium procedure for the following metal ions: Cd(II), Cr(III), Zn(II), Pb(II), and Hg(II). The effects of pH, time, temperature, and initial ion concentration on adsorption were investigated. The resins showed a significant ability to retain Pb(II), greater than 79%, at pH 5.     

Sorption of zinc by novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid

Novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid were applied as adsorbents for the removal of Zn²⁺ ions from aqueous solution. In batch tests, the influence of solution pH, contact time, initial metal ion concentration and temperature was examined. The sorption was found pH dependent, pH 5.5 being the optimum value. The adsorption process was well described by the pseudo-second order kinetic. The hydrogels were characterized by spectral (Fourier transform infrared—FTIR) and structural (SEM/EDX and atomic force microscopy—AFM) analyses. The surface topography changes were observed by atomic force microscopy, while the changes in surface composition were detected using phase imaging AFM. The negative values of free energy and enthalpy indicated that the adsorption is spontaneous and exothermic one. The best fitting isotherms were Langmuir and Redlich-Peterson and it was found that both linear and nonlinear methods were appropriate for obtaining the isotherm parameters. However, the increase of temperature leads to higher adsorption capacity, since swelling degree increased with temperature.     

Nanoparticle Removal Using Laser-Induced Plasma Shock Waves

Removal of sub-100 nm particles from substrates such as wafers and photo masks is an essential requirement in semiconductor, microelectronics, and nanotechnology applications. The proposed laser-induced plasma (LIP) based approach is an effective technique for removal of sub-100 nm particles, as the minimum tolerable particle on the substrates shrinks to sub-100 nm levels with each technological node. In the current study, our progress in sub-100 nm particle removal is reviewed, and the results of the kinetic theory simulations conducted to understand the dynamics of the gas molecule-nanoparticle interactions excited by the shock front are discussed. It is shown from the simulations and experiments that particles as small as sub-100 nm can be successfully detached. To explain possible mechanisms for the nanoparticle detachment in nanoscale, the concepts of rolling resistance moment and rocking motion are utilized as novel detachment mechanisms. The pressure experiments illustrate that the peak pressure levels achieved with the LIP shock wave fields are below damage thresholds of most substrate materials. The potential of the proposed approach as a practical noncontact, dry, fast, and damage-free method for removal of sub-100 nm particles is discussed.     

Initial corrosion protection of Zn–Mn alloys electrodeposited from alkaline solution

The effects of a deposition current density (c.d.) on the corrosion behaviour of Zn–Mn alloy coatings, deposited from alkaline pyrophosphate solution, were investigated by atomic absorption spectrophotometry (AAS), X-ray diffraction (XRD), atomic force microscopy (AFM), optical microscopy, electrochemical impedance spectroscopy (EIS) and measurement of corrosion potential (E_corr). XRD analysis disclosed that zinc hydroxide chloride was the main corrosion product on Zn–Mn coatings immersed in 0.5 mol dm⁻³ NaCl solution. EIS investigations revealed that less porous protective layer was produced on the alloy coating deposited at c.d. of 30 mA cm⁻² as compared to that deposited at 80 mA cm⁻².     

On a new class of quasi-orthogonal filters

In this article, a new class of quasi-orthogonal filters, based on the Legendre and Malmquist-type quasi-orthogonal polynomials, is presented. These filters are generators of quasi-orthogonal functions for which we derive and present all important properties and relations. Our article is based on the classical theory of orthogonality and orthogonal functions, and also on new results in this field of mathematics. Based on theoretical results, we design schemes for the realisation of these filters. Finally, a trail quasi-orthogonal filter is practically realised and its quasi-orthogonality is proven by performing experiments. Quasi-orthogonal filters can be successfully used for signal approximation as well as for modelling, identification, analysis, synthesis and simulation of dynamical systems.     

Antioxidative and Functional Properties of Pumpkin Oil Cake Globulin Hydrolysates

Cucurbitin extracted from pumpkin (Cucurbita pepo) oil cake was enzymatically hydrolysed with three different enzymes viz. alcalase, flavourzyme and pepsin. Antioxidative and functional properties of cucurbitin hydrolysates with different degrees of hydrolysis (DH) were investigated. The antioxidant activity of the hydrolysates was strongly dependent on the enzyme used. The hydrolysates obtained by alcalase and pepsin showed antioxidative potential whereas flavourzyme hydrolysates did not demonstrate these activities. Reducing power and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging activity of cucurbitin hydrolysate were positively related to DH. The highest antioxidant activity was found in the hydrolysate obtained by alcalase at DH 25.6 % [reducing power of 0.25 ± 0.01 A700 nm and ABTS scavenging activity of 3.34 ± 0.02 mmol/L Trolox equivalent antioxidant coefficients (TEAC)]. Hydrolysis by all enzymes increased the protein solubility within the studied pH range. The best emulsion activity and stability index (EAI = 143.28 ± 3.05 m²/g and ESI = 87.5 ± 1.96 min) have hydrolysates produced by flavourzyme (DH 9.2 %) whereas alcalase produced hydrolysates with the best foaming capacity (FC = 242 ± 3.21). The results demonstrate that hydrolysates produced in the present study have good functional properties as well as antioxidant activity indicating their possible use in different food systems.     

Optimization of Transglutaminase Cross-linking of Pumpkin Oil Cake Globulin; Improvement of the Solubility and Gelation Properties

Enzymatic cross-linking of hull-less pumpkin oil cake globulin was studied using microbial transglutaminase. Response surface methodology was employed to study the effect of enzyme/substrate ratio, temperature, and reaction time on protein cross-linking reaction, measured by degree of polymerization (DP) as a response. The second-order polynomial model showed good fit with the experimental data since the coefficient of determination was R ²?=?0.9297. Reaction time of 39.2 min, E/S ratio of 1/4.9 (w/w) and temperature of 28 °C were found to be optimal conditions to achieve the highest value of DP (69%). The solubility and gelation properties of the cross-linked proteins with different values of DP were assessed for improvement. The solubility of polymerized proteins was increased over the pH range 5.0–8.0 and affected with increase of DP, at each pH value studied. The highest solubility was achieved at DP of 60%, at pH 7.0 and was 24-fold higher than solubility of unmodified protein. Gelation properties of cross-linked protein were also improved and the highest decrease of least gelation concentration was achieved at pH 9.0.