Effect of dimethyl carbonate addition on ethanol-gasoline fuel blend.

The growing need for renewable and environmentally friendly sources of energy has motivated a lot of researchers to direct their efforts to meet these challenges. The use of renewable additives to gasoline, such as ethanol and methanol, has been a successful solution. However, blending ethanol into gasoline has some drawbacks, including increased gasoline volatility and significant changes in the distillation curve. This study investigated the effects of blending the eco-friendly dimethyl carbonate (DMC) with various concentrations into ethanol-gasoline fuel blend (E10) on some volatility parameters and octane number, which have not been previously reported in the literature. The fuel samples were formulated by mixing E10 with (0.0%, 2.0%, 4.0%, 6.0%, 8.0%, and 10.0%) of dimethyl carbonate. The main properties of the fuel samples were measured such as distillation curve, and octane number. The distillation process was carried out in accordance with ASTM-D86 while vapor pressure was measured in accordance with ASTM-D5191. The obtained results revealed interesting outcomes that may spark the interest of refineries in this promising fuel additive. Addition of DMC to gasoline-ethanol blend was found to have insignificant impact on the volatility of fuel. The results demonstrate that addition of ethanol to gasoline causes a significant decrease in T50 by about 20 °C, while addition of 10 volume percent of DMC to E10 causes an increase in T50 by about 2 °C. The obtained results showed also that the addition of 10 vol% of DMC to E10 fuel blend considerably increases the RON and MON by about 4 and 3.5 points, respectively.

Volatility criteria and physicochemical properties of the promising dimethyl carbonate-gasoline blends.

Increased need for energy resources, as well as the urgent need to improve the air quality, have prompted further research to meet these challenges. Great efforts have been directed to reducing the impact of exhaust emissions. In literature, the effect of blending dimethyl carbonate (DMC) into fuel on engine performance and exhaust emissions has been investigated, and the obtained results were promising in decreasing exhaust emissions. In the present work, the effect of blending DMC into gasoline on the physicochemical properties was studied. Six fuel blends were prepared by blending base gasoline (G) with (0%, 2%, 4%, 6%, 8%, and 10%) of DMC. The volatility characteristics of the fuel blends were studied, such as the distillation curve, vapor pressure, and driveability index. The octane rating and the physicochemical properties of the fuel blends were also studied. The results of the study showed interesting findings that encourage refineries to be interested in this promising fuel additive. The results showed that the addition of DMC to gasoline has a very slight effect on the volatility of gasoline, unlike other oxygenated additives like short chain alcohols which cause a significant increase in the fuel volatility. The addition of DMC to gasoline causes an insignificant increase in the vapor pressure as the addition of 10% of DMC increases the vapor pressure by 2 kPa while it does not affect the values of T10, T50, and T90, which are the most important parameters of the distillation curve. The results also showed that its addition causes a remarkable increase in the octane rating. The RON has increased for the G-10DMC blend by about 5 points making the DMC a promising octane booster.

Electrophoretic deposition of hydroxyapatite/chitosan nanocomposites: the effect of dispersing agents on the coating properties.

In this study, electrophoretic deposition (EPD) was used for the coating on titanium (Ti) substrate with a composite of hydroxyapatite (HA)-chitosan (CS) in the presence of dispersing agents such as polyvinyl butyral (PVB), polyethylene glycol (PEG), and triethanolamine (TEA). The materials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), zeta potential, and Fourier transform infrared (FT-IR) spectroscopy. The addition of PVB, PEG, and TEA agents improved the development of Ti coating during the EPD process. These additives increased the suspension stability and promoted the formation of uniform and compact HA/CS nanocomposite coatings on Ti substrates. The electrochemical polarization tests (e.g., potentiodynamic test) of the substrate with and without coating were investigated. Data analysis showed high corrosion resistance of Ti substrate coated with the HA/CS NP composite. The corrosion potentials displayed a shift toward positive values indicating the increase in the corrosion resistance of Ti after coating. In addition to measuring calcium ion release at various pH values and contact times at a biological pH value of 5.5, the stabilities of Ti substrates coated with HA/CS and different dispersing agents were also evaluated. Ti substrates with high anticorrosion properties may have a new potential application in biomedicine.

Immunocytochemical detection of cholecystokinin and corticotrophin-releasing hormone neuropeptides in the hypothalamic paraventricular nucleus of the jerboa (Jaculus orientalis): modulation by immobilisation stress.

The hypothalamic response to an environmental stress implicates the corticotrophin-releasing hormone (CRH) neuroendocrine system of the hypothalamic parvicellular paraventricular nucleus (PVN) in addition to other neuropeptides coexpressed within CRH neurones and controlling the hypothalamo-pituitary-adrenal (HPA) axis activity as well. Such neuropeptides are vasopressin, neurotensin and cholecystokinin (CCK). It has previously been demonstrated that the majority of the CRH neuronal population coexpresses CCK after a peripheral stress in rats. In the present study, we explored such neuroendocrine plasticity in the jerboa in captivity as another animal model. In particular, we studied CCK and CRH expression within the hypothalamic PVN by immunocytochemistry in control versus acute immobilisation stress-submitted jerboas. The results show that CCK- and CRH-immunoreactive neuronal systems are located in the hypothalamic parvicellular PVN. The number of CCK-immunoreactive neurones within the PVN was significantly increased (138% increase) in stressed animals compared to controls. Similarly, the number of CRH-containing neurones was higher in stressed jerboas (128%) compared to controls. These results suggest that the neurogenic stress caused by immobilisation stimulates CCK as well as CRH expression in jerboas, which correlates well with previous data obtained in rats using other stressors. The data obtained also suggest that, in addition to CRH, CCK is another neuropeptide involved in the response to stress in jerboa, acting by controlling HPA axis activity. Because CCK is involved in the phenotypical plasticity of CRH-containing neurones in response to an environmental stress, we also explored their coexpression by double immunocytochemistry within the PVN and the median eminence (i.e. the site of CRH and CCK corelease in the rat) following jerboa immobilisation. The results show that CCK is not coexpressed within CRH neurones in either control or stressed jerboa, suggesting differences between jerboas and rats in the neuroendocrine regulatory mechanisms of the stress response involving CRH and CCK. The adaptative physiological mechanisms to environmental conditions might vary from one mammal species to another.

Vasopressin-containing neurons of the hypothalamic parvocellular paraventricular nucleus of the jerboa: plasticity related to immobilization stress.

The corticotropin-releasing hormone (CRH) neurons of the hypothalamic parvocellular paraventricular nucleus (PVN) have a high potential for phenotypical plasticity, allowing them to rapidly modify their neuroendocrine output, depending upon the type of stressors. Indeed, these neurons coexpress other neuropeptides, such as cholecystokinin (CCK), vasopressin (VP), and neurotensin, subserving an eventual complementary function to CRH in the regulation of the pituitary. Unlike in rats, our previous data showed that in jerboas, CCK is not coexpressed within CRH neurons in control as well as stressed animals. The present study explored an eventual VP participation in the phenotypic plasticity of CRH neurons in the jerboa. We analyzed the VP expression within the PVN by immunocytochemistry in male jerboas submitted to acute stress. Our results showed that, contrary to CRH and CCK, no significant change concerned the number of VP-immunoreactive neurons following a 30-min immobilization. The VP/CRH coexpression within PVN and median eminence was investigated by double immunocytochemistry. In control as well as stressed animals, the CRH-immunopositive neurons coexpressed VP within cell bodies and terminals. No significant difference in the number of VP/CRH double-labeled cells was found between both groups. However, such coexpression was quantitatively more important into the posterior PVN as compared with the anterior PVN. This suggests an eventual autocrine/paracrine or endocrine role for jerboa parvocellular VP which is not correlated with acute immobilization stress. VP-immunoreactive neurons also coexpressed CCK within PVN and median eminence of control and stressed jerboas. Such coexpression was more important into the anterior PVN as compared with the posterior PVN. These results showed the occurrence of at least two VP neuronal populations within the jerboa PVN. In addition, the VP expression did not depend upon acute immobilization stress. These data highlight differences in the neuroendocrine regulatory mechanisms of the stress response involving CRH/CCK or VP. They also underline that adaptative physiological mechanisms to stress might vary from one mammal species to another.

Relationships of surfactant head group weight fraction and some polarity terms by gas chromatography.

Polarity, partition coefficient (K) , methanol carbon number of surfactant ((C(MeoH))S), and methanol carbon number of surfactant head group ((C(MeOH)) HG) are measured on six alkanolamides and five polyoxyethylenated long chain amines as stationary phases. From the measured methanol carbon numbers, polarity indices, (IP)S and (IP)HG, are calculated. The determined polarity terms are plotted against the head group weight fraction (f(HG)) of the investigated surfactants and several equations have been developed. The study reveals that the molecular structural gap between alkanolamides and polyoxyethylenated long chain amines diminished when HLB numbers of these surfactant classes are plotted against f(HG) values. Consequently, a general equation relating HLB and f(HG) is obtained.

Determination of polarity terms of some nitrogen-containing surfactants and simulated hydrophobic tail models by gas chromatography.

Some polarity terms of two groups of nitrogen-containing surfactants (six alkanolamides and nine polyoxyethylenated long chain amines) are measured through gas chromatography. The apparent methanol carbon number (C(MeOH)) and polarity index (IP) values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, C(MeOH) and IP values are determined on simulated hydrophobic tail (SHT) models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance (HLB) number and the hydrophobic group carbon number (RCN). Some equations relating the measured polarity values and these variable have been developed.