Diameter of titanium nanotubes influences anti-bacterial efficacy

Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.     

Optimization of Process-Control Parameters for the Diameter of Electrospun Hydrophilic Polymeric Composite Nanofibers

A composite nanofiber composed of three polymers, namely polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene oxide, is produced. The experiments are constructed using three design of experiment techniques, Taguchi L₉, Taguchi L₂₇, and Screening method. The experiments are verified using the analysis of variance (ANOVA) method and later a mathematical model is developed using the regression method. The impact of electrospun processing parameters, namely applied voltage, flow rate, and working distance, on nanofibers' diameter is measured. The working distance is a significant factor in controlling the size of the fiber diameter, while the applied voltage has the lowest effect on it. As a result of the regression equation, a Genetic algorithm is used to find the optimum variables for the required fiber diameter, which is 156 nm for flow rate = 0.001 mL h⁻¹, voltage = 30 kV, and distance = 200 mm with a 3% difference from the experimental fiber diameter.     

Energy and exergy analyses of a raw mill in a cement production

Cement production has been one of the most energy intensive industries in the world. In order to produce raw materials preparation, clinker and rotary kilns are widely used in cement plants. The objective of this study is to perform energy and exergy analysis of a raw mill (RM) and raw materials preparation unit in a cement plant in Turkey using the actual operational data. The RM has a capacity of 82.9 ton-material hourly. Both energy and exergy efficiencies of the RM are investigated for the plant performance analysis and improvement, and are determined to be 84.3% and 25.2%, respectively. The present technique is proposed as a useful tool in the analysis of energy and exergy utilization, developing energy policies and providing energy conservation measures.     

Preparation of polyurethane/hectorite,polyurethane/montmorillonite,and polyurethane/laponite nanocomposites without organic modifiers

Polyurethane (PU) nanocomposites were prepared from hectorite (HEC) and laponite without adding any organic modifier. PU‐montmorillonite nanocomposites were prepared for comparison. The structure of the composites were investigated by transmission electron microscopy, X‐ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. Thermal gravimetric analysis and dynamic mechanic analysis were used for determination of the thermal and viscoelastic behaviors, respectively. Tensile tests were conducted for characterization of the mechanical properties. The results showed a 113.5% increase in the tensile strength of PU containing 7 wt % HEC compared to that of neat PU. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Heat transfer reduction at the separation point on a spinning sphere in mixed convection

The unsteady laminar thermal boundary‐layer flow over an impulsively started translating and spinning isothermal body of revolution in the case of mixed convection is investigated. Velocity components and temperature are obtained as series of functions in powers of time. The general results are applied to a spinning sphere and the development of the surface heat flux evaluated at the separation point as it advances upstream is determined. The surface heat flux evaluated at the separation point as it moves forward decreases due to the increasing magnitude and influence of the centrifugal force and it is augmented by the opposing flow and reduced by the aiding flow. Reduction of the surface heat flux at the separation point is as low as 50 per cent as compared to the heat flux at the front stagnation point. Copyright © 2002 John Wiley & Sons, Ltd.     

Investigation of adsorption and corrosion inhibition effect of 1,1’-thiocarbonyldiimidazole on mild steel in hydrochloric acid solution

The adsorption and inhibition effect of 1,1′-thiocarbonyldiimidazole (TCDI) on the corrosion of mild steel (MS) in 0.5 M HCl solution was studied in both short and long immersion time (120 h) with the help of electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. For long-time tests, the hydrogen gas evolution (VH₂-t) and the change of open circuit potential with immersion time (E _ocp-t) were also utilized in addition to the former two techniques. The surface morphology of MS after its exposure to 0.5 M HCl solution with and without 1.0 × 10⁻² M TCDI was examined by scanning electron microscopy (SEM). It was demonstrated that the inhibition efficiency of studied inhibitor is concentration depended and increased with TCDI concentration. The higher value of inhibition efficiency was obtained after longer immersion time merely on the basis of strong increase of corrosion rate of mild steel in the blank solution. The high inhibition efficiency was discussed in terms of adsorption of inhibitor molecules and protective film formation on the mild steel surface which was substantiated by SEM micrographs. The adsorption of TCDI on MS was found to obey Langmuir adsorption isotherm.     

The Use of Vacuum Impregnation for Debittering Green Olives

The aim of this research was to assess the possibility of shortening the length of the debittering process for green table olive ‘Domat’ cultivar by vacuum impregnation (VI). For this purpose, debittering was carried out with NaCl (3 %), NaOH (1.5 %) and NaOH (1.5 %) + NaCl (3 %) solutions at atmospheric conditions and under vacuum (68 kPa). The effects of these applications on some physicochemical properties (total dry matter, total ash, titratable acidity, salt, protein, oil, oleuropein, total phenolics, antioxidant activity and colour) of the processed samples were determined. Total dry matter, titratable acidity, salt, protein and oil contents of the samples changed between 24.23 and 27.90, 0.22 and 0.45, 2.27 and 2.58, 0.50 and 1.26 and 6.79 and 9.42 % (w/w), respectively. Colour parameters (lightness (L*); redness (a*); yellowness (b*)) of the processed olives were measured as between 41.72 and 51.29, 15.09 and 13.30 and 22.79 and 34.84, respectively. Hue angles of the processed samples were changed between 59.78 and 68.52. VI was a useful tool for the shortening of the period of debittering process. Use of NaOH combined with NaCl in VI process caused the debittering period to decrease to 6 h. However, reduction of the amount of total phenolic compounds was the highest (21.43 %) in this condition. Use of alkali for debittering caused more dry matter diffusion from olive to the solution. There was no statistically significant difference between the oleuropein and total ash contents of the processed samples (p?<?0.01). Alkali treatment also caused more oil loss from the olives. Antioxidant activity of the samples reduced up to 59.89 %. This research was the first using VI for debittering of olives; further studies are necessary to optimise process conditions of debittering for limiting loss of natural antioxidants and other components and to ensure maximum benefits to the consumer.     

The initial boundary-layer flow past a translating and spinning rotational symmetric body

The boundary-layer flow on an impulsively started translating and spinning rotational symmetric body is considered. The stream function and the swirl component of the velocity are expanded in series in powers of time. Leading and first order solutions are obtained analytically and the second order solutions are determined numerically. The results are applied to a translating and spinning sphere and the rotation is found to reduce the friction drag and facilitate flow separation.     

Condition monitoring of speed controlled induction motors using wavelet packets and discriminant analysis

This work presents an intelligent method for the condition monitoring of induction motors supplied with adjustable speed drives (ASD). Most of the previous work in this area concentrated on the fault detection and classification of induction motors supplied directly from an a.c. line. However, ASD driven induction motors are widely used in industrial processes and therefore obtaining an intelligent tool for the condition monitoring of these motors is necessary in terms of preventive maintenance and reducing down time due to motor faults. Here 3-phase supply side current of the ASD driving an induction motor is used to extract statistical features of wavelet packet decomposition coefficients within a frequency range of interest. This way, the information regarding the output frequency of the ASD and hence the motor speed is not required. Six identical three-phase induction motors were used for the experimental verification of the proposed method. One healthy machine was used as a reference, while other five with various synthetic faults were used for condition detection and classification. Extracted features obtained from decomposition coefficients of different wavelet filter types for all motors were employed in three different and popular classifiers. The proposed method and the performance of the features used for fault detection and classification are examined at various motor loads and speed levels, and it is shown that a successful condition monitoring system for induction motors supplied with ASDs is developed. The effect of selected filter type in wavelet decomposition to the condition monitoring process is analyzed and presented.     

A symmetric lattice-based wideband wide phase range digital phase shifter topology

In this paper, a novel digital phase shifter topology that achieves wideband and wide phase range is proposed. Wide frequency band operation is accomplished employing symmetrical all-pass lattice structures. Compact phase shifter size is obtained utilizing the miniaturized microwave monolithic integrated circuit (MMIC) design implementation technology. Therefore, resulting phase shifter units are suitable for various communication systems such as radar and cellular communication smart antenna arrays. This paper provides complete design equations together with design algorithm for the selected phase shift and the center frequency. Design algorithm is developed on MatLab environment. The proposed phase shifting circuit is implemented employing the commercially available 0.18-μm silicon CMOS technology. The new phase shifter topology provides 0⁰ to 360⁰ phase shift range over X-band, even beyond.