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J.E. Martin-Alfonso,M.J. Diaz,N. Nunez,C. Valencia,J.M. Franco 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.6
The influence of cellulose pulp ethylation processing conditions has been evaluated to design suitable renewable and biodegradable lubricating greases from cellulose pulp-based gel-like dispersions. Ethyl/glucose molar ratio (E/G) has a positive effect on the ethyl groups degree of substitution (DS). Gel-like biodegradable dispersions of cellulose pulp in castor oil have been prepared by adding ethylated cellulose samples differing in the substitution degree to modify the rheological properties of castor oil. The rheology of ethyl cellulose/castor oil binary systems is highly influenced by DS. The linear viscoelastic functions and consistency are very similar to those found in traditional lithium lubricating greases.
J.E. Martin-Alfonso,G. Moreno,C. Valencia,M.C. Sanchez,C. Gallegos,J.M. Franco 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.5
The main goal of this work was to study the feasibility of using a low-density polyethylene (LDPE) as additive to improve the rheological properties of lithium lubricating greases. The combined effect that both soap and LDPE concentrations exerts on the rheology of lithium lubricating greases and its relationship with grease microstructure were studied according to an experimental design based on the response surface methodology (RSM). Different lubricating grease formulations were manufactured by modifying lithium 12-hydroxystereate and LDPE concentrations. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements, as well as mechanical stability tests, were performed. In addition to these, environmental scanning electronic microscopy (ESEM) was used to determine grease microstructure. LDPE was found to be a useful additive to modify grease rheology, acting as filler in the entangled soap network. The values of both apparent viscosity and linear viscoelasticity functions increase with soap and LDPE concentration. However, the addition of LDPE distorts soapmicrostructural network, yielding greases with lower relative elastic characteristics.
Garci´a-Morales, J. A.,Franco, J. M.,Valencia, C.,Sa´nchez, M. C.,Gallegos, C. 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.3
This paper deals with the influence that the agitation speed, the temperature of processing, and the cooling profile applied during crystallization of the thickening agent exert on some rheological parameters of lubricating greases. With this aim, the in situ reaction between 12-hydroxystearic acid and lithium hydroxide was conducted to form the lithium soap. After the saponification reaction was completed, the crystallization was induced by adding different batches of the lubricating oil and cooling the stirred tank. Torque was measured during the process using a controlled-rotational-speed mixing rheometer from which the energy consumption during processing was evaluated. The Metner-Otto approach was followed to estimate the viscosity of the incipient and final lubricating greases. Linear viscoelastic and viscous flow measurements were performed on the final product. From the experimental results, we conclude that an increase in the temperature applied after the saponification reaction or a decrease in the cooling rate of the freshly prepared grease generally increases the values of the rheological parameters studied. On the other hand, by increasing the rotational speed, the values of the viscoelastic functions were significantly reduced. In addition to this finding, all of these variables affect the energy consumption during the processing. Discrepancies found in the viscosity values obtained from rotational rheometry and torque measurements during the mixing flow are attributed to the fractured layer observed in the gap between the wall and the impeller.
J.E. Martın-Alfonso,A. Romero,C. Valencia,J.M. Franco 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
This work has been focused on the development of polyolefins/oil blends potentially suitable as lubricating greases by studying the effect that some thermo-mechanical processing variables exert on their rheological properties and microstructure. Polyolefin/oil blends have been prepared by dispersing recycled and virgin polyolefins such as high-density polyethylenes (HDPEs) and polypropylenes (PPs) in mineral lubricating oil. Linear viscoelasticity functions have been significantly influenced by processing conditions. The nature of polymers used, specially the content of HDPE, has been found to modify the microstructure of blends yielding lower mechanical stability but, on the other hand, higher values of linear viscoelastic functions.
J.E. Martín-Alfonso,A.A. Cuadri,J.M. Franco 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8
Nowadays, there is a marked tendency in order to develop new composite fibers based on proteins andpolysaccharides due to these materials can exhibit a wide range of tailored functional properties. In this framework, this studyhas been focused on the development of novel potato protein (PP)-based composite fibers by electrospinning technique usingformic acid as solvent media. At the selected electrospinning conditions, PP pure solutions (3-8 wt.%) showed inadequatespinnability. Interestingly, the addition of polyethylene oxide (PEO) as co-blending polymer improved the solutionsviscoelasticity and hence, the solutions spinnability. Composite fibers with enhanced properties were obtained at higher PEOconcentrations while systems with higher PP protein contents led to electrosprayed separate aggregates of particles. Fouriertransformedinfrared spectroscopy and thermogravimetric analysis results showed that the obtained composite fibers werecomposed of both PP and PEO materials. DSC results show that PP influences on PEO polymer thermal behaviour loweringits melting point, and an increase of the PEO amount produces a decrease of the α-helix denaturation temperature. Due to theproperties of PP and PEO, these novel composite fibers could find importance in a diverse range of applications as advancedfunctional materials in fields like food science and biomedical applications.
Figueiras, J.F.,Detmann, E.,Franco, M.O.,Batista, E.D.,Reis, W.L.S.,Paulino, M.F.,Valadares Filho, S.C. Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.12
The objective of this study was to evaluate the effects of supplements with different crude protein (CP) contents on grazing cattle intake, digestibility, ruminal fermentation pattern, and nitrogen (N) metabolism characteristics during the rainy season. Five ruminal and abomasal cannulated Holstein${\times}$Zebu steers (296 kg body weight, BW) were used in a $5{\times}5$ Latin square design. The animals grazed five signal grass paddocks (0.34 ha). The five treatments evaluated were: Control (no supplement) and 1.0 g of supplement/kg BW with 0, 330, 660, and 1,000 g of CP/kg as-fed. The supplement was composed of starch, soybean meal, urea, and ammonium sulphate. There was a positive linear effect ($p{\leq}0.033$) of the CP content in the supplements on the organic matter (OM), CP, and digested OM intakes. The provision of supplements did not increase ($p{\geq}0.158$), on average, total and ruminal digestibilities of OM and CP. However, the increase in CP content in the supplements caused a positive linear effect ($p{\leq}0.018$) on ruminal digestibilities of OM and CP. Additionally, a quadratic effect of the CP contents of the supplements were observed (p = 0.041) for the ruminal digestibility of neutral detergent fiber corrected for ash and protein, with the highest estimate obtained with the CP content of 670 g/kg. The supply of supplements increased (p<0.001) the ruminal ammonia N concentration, which also changed linearly and positively (p<0.001) according to increase in CP content in the supplements. The apparent N balance and relative N balance (g/g N intake) were not, on average, changed ($p{\geq}0.164$) by the supplements supply. However, both showed a tendency of a linear increase ($p{\leq}0.099$) with increasing supplement CP content. The supplements increased (p = 0.007) microbial N production in the rumen, which also changed linearly and positively (p = 0.016) with increasing supplement CP content. In conclusion, protein supplementation in grazing cattle during the rainy season, while stimulating voluntary forage intake, results in higher efficiency of N utilization when compared to energy supplementation. This is a possible response to increased microbial protein synthesis in the rumen and improved N status in the animal body.
Chemosensitization potential of P-glycoprotein inhibitors in malaria parasites
Alcantara, L.M.,Kim, J.,Moraes, C.B.,Franco, C.H.,Franzoi, K.D.,Lee, S.,Freitas-Junior, L.H.,Ayong, L.S. Academic Press 2013 Experimental parasitology Vol.134 No.2
Members of the ATP-binding cassette (ABC)-type transporter superfamily have been implicated in multidrug resistance in malaria, and various mechanistic models have been postulated to explain their interaction with diverse antimalarial drugs. To gain insight into the pharmacological benefits of inhibiting ABC-type transporters in malaria chemotherapy, we investigated the in vitro chemosensitization potential of various P-glycoprotein inhibitors. A fluorescent chloroquine derivative was synthesized and used to assess the efflux dynamics of chloroquine in MDR and wild type Plasmodium falciparum parasites. This novel BODIPY-based probe accumulated in the digestive vacuole (DV) of CQ-sensitive parasites but less so in MDR cells. Pre-exposure of the MDR parasites to non-cytocidal concentrations of unlabeled chloroquine resulted in a diffused cytoplasmic retention of the probe whereas a similar treatment with the CQR-reversing agent, chlorpheniramine, resulted in DV accumulation. A diffused cytoplasmic distribution of the probe was also obtained following treatment with the P-gp specific inhibitors zosuquidar and tariquidar, whereas treatments with the tyrosine kinase inhibitors gefitinib or imatinib produced a partial accumulation within the DV. Isobologram analyses of the interactions between these inhibitors and the antimalarial drugs chloroquine, mefloquine, and artemisinin revealed distinct patterns of drug synergism, additivity and antagonism. Taken together, the data indicate that competitive tyrosine kinase and noncompetitive P-glycoprotein ATPase-specific inhibitors represent two new classes of chemosensitizing agents in malaria parasites, but caution against the indiscriminate use of these agents in antimalarial drug combinations.