The Effect of Temperature on Tribological Properties of Chemically Modified Bio-Based Lubricant

Vegetable oil has several characteristics that provide advantages for use as lubricant. This includes a high viscosity index, high flash point, high biodegradability, and friction and wear reduction properties. However, vegetable oil has some disadvantages such as low oxidation stability and low thermal stability. The transesterification process of palm oil using trimethylolpropane (TMP) alcohol has been proven to reduce the oxidation stability of vegetable oil. However, little research has been carried out on the effect of TMP ester as a lubricant in term of friction and wear. Therefore, this study investigated the effect of temperature on the tribological properties of TMP ester using a four-ball machine. The load and speed of the sample were set at 40 kg and 1,200 rpm, respectively. Temperature was varied between 50 and 100°C. It was found that TMP ester improved the friction properties by around 15–20%. At low temperature, TMP esters have a higher coefficient of friction (COF) compared to paraffin oil. However, as the temperature increased higher than 80°C, paraffin oil had a highere COF value. This is because at high temperature, the lubricant filmed formed by fatty acids tends to be less stable and breaks down more easily.     

Tribological Study of a Tetrahedral Diamond-Like Carbon Coating under Vegetable Oil–Based Lubricated Condition

Maintaining a clean environment is the major concern of industries that produce fuel and lubricants for automotive applications. Thus, vegetable-based oils are being explored for the preparation of biobased lubricants because of their biodegradability and nontoxicity. Despite their low thermal stability, vegetable oils show better tribological characteristics than mineral oils. Nonetheless, the thermal stability of vegetable oils could be improved by transesterification. In this study, three vegetable-based oils (sunflower, palm, and coconut) were used to investigate the tribological properties of ta-C diamond-like carbon (DLC) coating under DLC–steel contact condition. A BICERI ball-on-a plate tribotesting machine was used to conduct experiments. During the experiment, test contacts of tribopairs lubricated with sunflower oil exhibited better tribological characteristics than those using coconut oil as a lubricant.     

Hydrocarbon Group Analysis of Arabian Crude Oils TBP-Fractions

ABSTRACT

Experimental studies have been carried out on hydrocarbon group analysis of commercial Arabian crude oil fractions corresponding to the true boiling point ranges or 200–400 ast;F, 400–500 ?F 500–650 ?F, 650–850 ?F, and 850 ?F-K The crude oils included Arab heavy (API? = 28·0), Arab medium (API? = 30·0), Arab light (API? = 33·3), and Arab Berry extra light (API? = 36?9). Waters Hydrocabon Group Analyzer (HGA) system interfaced with model 730 Data Module has been used to obtain the compositional analysis in terms of saturates, neutral aromatics, polar aromatics and asphaltcnes.     

Cross‐sectional area calculation for arbitrary shape in the image using star algorithm with Green's theorem

Calculation of the cross‐sectional area is an important diagnostic tool in medical imaging modality. Curvature points arrangement (CPA) is an important step in the calculation, where the Star algorithm had been shown to be effective in segmenting the carotid artery. The algorithm however works under the assumption of circular or ellipsoid shapes, and the ability to determine its center of gravity is done by exploiting the features of equi‐space diameter of the circle. In this paper, a method of calculation of the cross‐sectional area of an arbitrary shape is discussed. The Star algorithm is modified to arrange the points of the object's edge through the CPA process in order to form a simple closed curve. Several rays are emanated from a point inside the region of interest with different angles to the far points within the segmented area. The cross‐sectional area is then calculated by using Green's theorem. To validate the concepts, several regular shaped images with different noise types (Gaussian, speckles, and salt and pepper) and ultrasound images are used in the experiments. The result shows that this method can calculate the cross‐sectional area with negligible error for an arbitrary object within the image and with different types of noises. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Learning to dislike safe water products: results from a randomized controlled trial of the effects of direct and peer experience on willingness to pay

Low-cost point-of-use (POU) safe water products have the potential to reduce waterborne illness, but adoption by the global poor remains low. We performed an eight-month randomized trial of four low-cost household water treatment products in Dhaka, Bangladesh. Intervention households (n = 600) received repeated educational messages about the importance of drinking safe water along with consecutive two-month free trials with each of four POU products in random order. Households randomly assigned to the control group (n = 200) did not receive free products or repeated educational messages. Households' willingness to pay for these products was quite low on average (as measured by bids in an incentive-compatible real-money auction), although a modest share was willing to pay the actual or expected retail price for low-cost chlorine-based products. Furthermore, contrary to our hypotheses that both one's own personal experience and the influence of one's peers would increase consumers' willingness to pay, direct experience significantly decreased mean bids by 18-55% for three of the four products and had no discernible effect on the fourth. Neighbor experience also did not increase bids. Widespread dissemination of safe water products is unlikely until we better understand the preferences and aspirations of these at-risk populations.     

Phase-formation,microstructure, and piezoelectric/dielectric properties of BiYO3-doped Pb(Zr0.53Ti0.47)O3 for piezoelectric energy harvesting devices

This paper proposes a method for the composition and synthesis of lead zirconate titanate (PZT) piezoelectric ceramic for use in energy harvesting systems. The proposed material consists of (1?x)Pb(Zr_0.53Ti_0.47)O₃–xBiYO₃ [PZT–BY(x)] (x=0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol) ceramics near the morphotropic phase boundary (MPB) region, prepared by a solid-state mixed-oxide method. The optimum sintering temperature was found to be 1160 °C, which produced high relative density for all specimens (96% of the theoretical density). Second phases were found to precipitate in the composition containing x≥0.01 mol of BY. It is shown that the addition of BY inhibits grain growth, and exhibits a denser and finer microstructure than those in the un-doped state. Fracture surface observation revealed predominant intergranular fracture for x=0 and x=0.01, while a mixed mode of transgranular and intergranular fracture appeared for x≥0.02. The optimal doping level was found to be x=0.01, for which a dielectric constant (K₃₃^T) of 750, a Curie temperature (T_C) of 373 °C, a remnant polarization (P_r) of 50 µC/cm², a piezoelectric constant (d₃₃) of 350 pC/N, and an electro-mechanical coupling factor (k_p) of 65% were obtained. In addition, the piezoelectric voltage constant (g₃₃), and transduction coefficient (d₃₃×g₃₃) of PZT–BY(x) ceramics have been calculated. The ceramic PZT–BY(0.01) shows a considerably lower K₃₃^T value, but higher d₃₃ and k_p. Therefore, the maximum transduction coefficient (d₃₃×g₃₃) of 18,549×10^?15 m²/N was obtained for PZT–BY(0.01). The large (d₃₃×g₃₃) indicates that the PZT–BY(0.01) ceramic is a good candidate material for energy harvesting devices.     

Effect of light irradiation on esterification of oleic acid with ethanol catalyzed by immobilized Pseudomonas cepacia lipase

The present study demonstrates the effect of light irradiation on the esterification of oleic acid catalyzed by immobilized Pseudomonas cepacia lipase. The reaction rates of all the experiments under light irradiation were found to be higher than dark conditions. The kinetics of reactions supported the Ping‐Pong Bi‐Bi mechanism with dead end inhibition by both the alcohol and acid substrates. Moreover, circular dichroism (CD) spectroscopy was used to analyze the effect of light on lipase enzyme. The CD spectroscopic studies confirmed that the conformational changes in the secondary structure of the lipase enzyme increased the reaction rate of light‐illuminated experiments, which might have opened up the active sites of enzymes and thus, resulted in higher reaction rates compared to dark reactions. These results have successfully demonstrated that the light illumination positively influenced the rate of P. cepacia enzyme‐catalyzed esterification reactions.     

Physico-mechanical and microstructural properties of semolina flour films as influenced by different sorbitol/glycerol concentrations

This study aimed at investigating the physico-mechanical and microstructural properties of a novel edible film based on plasticized semolina flour with different plasticizer (sorbitol/glycerol, 3:1) contents (30, 40, and 50%, w/w). As plasticizer content increased, water vapor and oxygen permeability, tensile strength, and the elastic modulus of the semolina films decreased, while their water solubility, moisture content, and elongation-at-break increased significantly (p < 0.05). Semolina-based films exhibited excellent absorption of ultraviolet light, and the addition of plasticizers improved the optical properties of the resultant films. Fourier-transform infrared spectroscopy showed no significant effect on the structure of the protein. Thermogravimetric analysis also revealed that increasing plasticizer concentration has no remarkable influence on the magnitude of weight loss. Atomic force microscopy images showed that the surface roughness of the films was influenced by plasticizer concentrations. This study demonstrated that semolina flour protein has the potential to prepare edible films.     

Antibacterial responses of zinc oxide structures against Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes

The antibacterial responses of zinc oxide (ZnO) structures against Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes were investigated. Two ZnO powder samples, one with rod-like (ZnO-1) and the other with plate-like (ZnO-2) structures, were characterized for their morphological, structural, and optical properties. The rods were 30–120 nm in diameter, and the plates were 40–100 nm thick. XRD results revealed the wurtzite crystallinity of ZnO with average crystallite sizes of 33.72 (ZnO-1) and 39.25 (ZnO-2) nm. ZnO-2 possessed a relatively higher green photoluminescence than that of ZnO-1, suggesting a relatively higher amount of oxygen vacancies in ZnO-2 structures. Optical density measurements showed that both ZnO samples inhibited the growth of S. aureus, P. aeruginosa, and S. pyogenes by 29–98% after 24 h of treatment. The most dramatic growth inhibition was observed in S. pyogenes with 96% and 98% inhibition for ZnO-1 and ZnO-2, respectively, leading to a probable bactericidal phenomenon. The toxicological effect on S. pyogenes was probably due to the absence of catalase, making the bacteria vulnerable to the harmful reactive oxygen species (ROS) released by ZnO. ZnO-1 induced higher inhibition toward S. aureus and P. aeruginosa than that of ZnO-2 because of the smaller particle size of rod structures compared to plate and slab structures. The adhesion of ZnO particles on the membrane of bacteria could be the underlying cause of zinc toxicity effect towards the bacteria. ZnO-1 possessed larger surface area and provided higher amount of zinc atom, thereby inducing higher level of toxicity toward the bacteria. Two possible mechanisms were proposed to explain the inhibition of bacteria, namely, ROS toxicity toward cellular constituents and interaction of zinc with bacteria membrane through adhesion of ZnO particle. Several ZnO morphological-antibacterial correlations were presented in this work.