Showing papers on "Liquid paraffin published in 2010"

Size effects of SiO2 nanoparticles as oil additives on tribology of lubricant

Abstract: Purpose – The purpose of this paper is to investigate the tribological properties of liquid paraffin with SiO2 nanoparticles additive made by a sol‐gel method.Design/methodology/approach – The tribological properties of the SiO2 nanoparticles as an additive in liquid paraffin are measured using a ball‐on‐ring wear tester to determine the optimal additive concentration. The mechanism that wear and friction are reduced is studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and atomic force microscope (AFM).Findings – Experimental results indicate that the sizes of the synthesized SiO2 nanoparticles are distributed uniformly and that the optimal concentrations of SiO2 nanoparticles in liquid paraffin is associated with better tribological properties than pure paraffin oil, and an anti‐wear (AW) ability that depends on the particle size.Originality/value – It is shown in the paper that by reducing friction and AW, the lubricant prepared by the methods described can prolong ...

Thermophysical Comparison of Five Commercial Paraffin Waxes as Latent Heat Storage Materials

Abstract: Thermophysical properties of phase change materials (PCM) are of utmost importance in latent heat thermal energy storage (LHTES) applications. Therefore, an experimental study is conducted in order to determine thermophysical properties of five technical grade paraffin waxes produced by major Croatian oil company, INA d.d. Rijeka. The temperatures and enthalpies of melting and solidification (latent heat capacity) and specific heat capacities of solid and liquid paraffin waxes were measured by differential scanning calorimetry (DSC). The thermal diffusivity of paraffin waxes was determined utilizing transient method. The importance of eliminating phase transformation interferences to thermophysical properties determination is addressed. The densities and the coefficient of thermal expansion were measured using Archimedes methods. A self-adopted simple and inexpensive laboratory procedure for the determination of liquid density as a temperature function is presented. Finally, the thermal conductivities have been calculated from measured densities, heat capacities and diffusivities. Based on results obtained, the investigated paraffin waxes were evaluated in regard to their applicability as PCM for LHTES.

Experimental investigation on thermal conductivity of nanofluids containing graphene oxide nanosheets

Abstract: Nanofluids containing graphene oxide nanosheets have substantially higher thermal conductivities than the base fluids. The thermal conductivity enhancement ratios with the loading 5.0 vol % are up to 30.2%, 62.3%, and 76.8%, when the base fluids are distilled water, propyl glycol and liquid paraffin, respectively. The enhancement ratios of the nanofluids are almost constant with the tested temperature varying, and they are reduced with the increasing thermal conductivity of the base fluids. Heat transport along the graphene oxide plane is proposed to be the major contributions to the increase in the thermal conductivity.

The Effect of Morphology on the Tribological Properties of MoS2 in Liquid Paraffin

Abstract: The tribological properties of liquid paraffin (LP) containing molybdenum disulfide (MoS2) additives, including nano-balls, nano-slices, and bulk 2H-MoS2, are evaluated using a four-ball tribometer. Results show that all MoS2 additives used can improve the tribological properties of LP, and that nanosized MoS2 particles function as lubrication additives in LP better than micro-MoS2 particles do. The LP with nano-balls presents the best antifriction and antiwear properties at the MoS2 content of 1.5 wt%. This is ascribed to the chemical stability of the layer-closed spherical structure of nano-balls. The Stribeck curves confirm that the rotation speed of 1,450 rpm used is located at the mixed lubrication region under 300 N. MoS2 nano-slices have small sizes and easily enter into the interface of the friction pair with a roughness of 0.032 μm, functioning as a lubricant in LP better than nano-balls do at the MoS2 content of 1.0 wt%. The Stribeck curves also show that the differences between the two nano samples were magnified at high rotation speeds in hydrodynamic lubrication region. The application of nano-slices in high sliding speeds will be more advantageous. This work furthers the understanding of the relationship between the tribological properties and morphology of MoS2.

Eudragit S-100 entrapped chitosan microspheres of valdecoxib for colon cancer

Abstract: COX-2 inhibitors have demonstrated beneficial effects in colorectal cancer. The purpose of this study was to prepare and evaluate the colon specific microspheres of COX-2 inhibitors using valdecoxib as a model drug. Mucoadhesive core microspheres were prepared using chitosan as polymer and entrapped within Eudragit S 100 for colon targeting. FTIR spectrum of selected, coated microspheres showed peaks of valdecoxib at 3377, 3250, 1334 and 1155 cm(-1). XRD showed amorphous character and DSC showed depressed broad endotherm of valdecoxib at 169.07 degrees C, which may be attributed to dilution effect by the amorphous polymer. The coated microspheres were spherical with an average size of 90 mum. Storage of the microspheres at 40 degrees C/75% relative humidity for 6 months indicated no significant drug degradation. The coated microspheres did neither release the drug in acidic pH of stomach (pH 1.2) nor in small intestinal pH between 5 to 6.8, and the release started at pH 7.4, indicting perfect colonic delivery. The coated microspheres pretreated with phosphate buffer pH 7.4 for 30 min, when applied to mucosal surface of freshly excised goat colon, showed good mucoadhesion. The drug release at pH 7.4 and good mucoadhesive property of the microspheres make the system ideal for colonic delivery.

Dispersion and tribological properties of liquid paraffin with added aluminum nanoparticles

Abstract: Purpose – The purpose of this paper is to study the dispersion and tribological properties of liquid paraffin with aluminum nanoparticles as additive, which are prepared by the surface‐modification method using oleic acid (OA).Design/methodology/approach – The dispersion stability of aluminum nanoparticles in liquid paraffin is measured by spectrophotometry, which can be optimization by Taguchi method. The tribological properties are evaluated by using a ball‐on‐ring wear tester.Findings – The results show that few concentrations of aluminum nanoparticles as additives in liquid paraffin have better antiwear and antifriction properties than the pure paraffin oil. Scanning electron microscopy and energy dispersive spectrometer analyses can show that the thin films on the rubbing surfaces can be formed by these aluminum nanoparticles, which not only bear the load but also separate the both interfaces, thus the wear and friction can be reduced.Originality/value – Machine components and mechanism pairs rely on...

Highly-fluorescent alloyed quantum dots of CdSe1−xTex synthesized in paraffin liquid: gradient structure and promising bio-application

Abstract: By using paraffin liquid and oleic acid as the solvent and ligand, highly-fluorescent red to near-infrared (NIR)-emitting cadmium selenium telluride (CdSe1−xTex) alloyed quantum dots (QDs) with photoluminescence quantum yield (PLQY) up to 70% were successfully prepared. The as-prepared CdSe1−xTex QDs also demonstrated good optical stabilities against the temperature change and photobleaching due to their gradient “CdTe-rich core/CdSe-rich surface” quasi “core/shell” structure, which was confirmed by studying the alloying process of CdSe1−xTex QDs. Moreover, the as-prepared red to NIR CdSe1−xTex QDs were successfully incorporated into the carboxyl capped porous polystyrene (PS) microbeads to fabricate red to NIR-emitting microbeads with low in vitro cytotoxicity, and the biotinylated goat anti-mouse IgG could be specifically coupled to the optical encoded beads via mouse anti-human chorionic gonadotrophin connected to the carboxyl groups on the encoded microbeads successfully, which suggested promising application of CdSe1−xTex QDs in multiplexed bioassays.

Uptake of T-2307, a novel arylamidine, in Candida albicans

Abstract: Objectives: T-2307, a novel arylamidine synthesized at Toyama Chemical Co., Ltd, has in vitro and in vivo broadspectrum activities against pathogenic fungi. T-2307 particularly exhibits potent in vitro and in vivo activity against Candida albicans, suggesting that its uptake might be mediated by a transport system. In this report, we studied the uptake of T-2307 in C. albicans. Methods: C. albicans cells and rat hepatocytes were exposed to 0.02 m M[ 14 C]T-2307. After incubation, the reaction mixture was concentrated and layered on a silicon layer (mixture of silicon oil and liquid paraffin) inside a tube. The tube was then centrifuged to transfer cells into the bottom layer (sodium hydroxide) for solubilization. The bottom layer was neutralized and measured for radioactivity. Results: T-2307 was concentrated from the extracellular medium by C. albicans cells in 10 mM phosphate buffer solution supplemented with 1% glucose by 3200- to 5100-fold. The accumulation was approximately two orders of magnitude greater than that achieved with a rat hepatocyte preparation. T-2307 uptake was sensitive to temperature and extracellular pH, and was reduced in the presence of inhibitors of mitochondrial respiration, oxidative phosphorylation and plasma membrane proton pump, and by an uncoupler. Furthermore, T-2307 uptake was concentration dependent and an Eadie‐Hofstee plot suggested the involvement of two transport systems. Conclusions: The considerably higher concentrations of T-2307 were selectively accumulated in C. albicans via transporter-mediated systems, as compared with the concentrations in rat hepatocytes. This transportermediated uptake of T-2307 contributes to its potent anticandidal activity.

Process intensification in extraction by liquid emulsion membrane (LEM) process: A case study; enrichment of ruthenium from lean aqueous solution

Abstract: Process intensification in extraction as a unit operation can be realized through liquid emulsion membrane (LEM) process by combining extraction and stripping in one stage eliminating the need of stripper. LEM technique is very useful to enrich very lean aqueous phase containing precious metal to aid the recovery process. The technique is illustrated by applying the same to enrich platinum group noble metal, ruthenium (Ru) from its aqueous solution. The liquid membrane phase consisted of extractant (trioctylamine) dissolved in liquid paraffin modified with 1-octanol and the surfactant used was Monemul 80. The strip phase found to be very effective was perchloric acid. To facilitate extraction tin(II) chloride was added to the aqueous feed phase containing Ru at 20 ppm level. Various process parameters affecting the performance of LEM process such as extractant, surfactant, strip phase concentrations, the batch extraction time, the treat ratio and the speed of agitation were studied at bench scale to aid process development. The maximum enrichment of Ru, obtained was almost 10.3 times, in the internal strip phase (2 mol L −1 of perchloric acid), from the feed phase containing Ru at 20 ppm level.

Bioprocess engineering of Echium italicum L.: induction of shikonin and alkannin derivatives by two-liquid-phase suspension cultures

Abstract: An in vitro cell suspension culture of Echium italicum was established and assayed for the production of shikonin and alkannin derivatives. Callus tissues were induced from cotyledon explants of the plant incubated onto the solidified B5 medium. A two-liquid-phase system suspension culture was then established to elicit pigments of shikonin and alkannin derivatives using liquid paraffin. The presence of liquid paraffin efficiently induced production of pigments in cultured cells. The production and/or accumulation of these compounds in the E. italicum cells was examined using fluorescence microscopy as the naphthoquinone molecules display autofluorescent properties. Phytochemical analysis of the n-hexane extract of the medium was also carried out using preparative HPLC. The chemical structure of shikonin and alkannin derivatives were characterized by UV, 1H-NMR, and 13C-NMR techniques. Based on our findings, this bioprocess engineering approach resulted in induction of shikonin and alkannin derivatives, whereupon it may be recruited for production of these important secondary metabolites.

A Numerical Study on Heat Transfer of High Efficient Solar Flat-Plate Collectors with Energy Storage

Abstract: The integrated solar collector is considered to be a promising direction for increasing the economic feasibility of low-temperature solar systems for heating water in domestic and industrial applications. Phase change material (paraffin) energy storage can be used in solar water heaters. The paraffin-integrated solar collector eliminates the need of conventional storage tanks, thus reducing cost and space. But a negative aspect of paraffin is that the materials suffer from inherent low thermal conductivity. In this paper, new aluminum foams filled with paraffin were presented to solve this problem. Local thermal equilibrium between the solid filler and the matrix is not ensured in such systems since their thermal diffusivities are very different. A two-temperature model was used for the aluminum frame and liquid paraffin respectively in this paper. A general momentum equation, which includes the Brinkman–Forchheimer extension to Darcy flow, was employed when the paraffin was melted. Apparent heat capacity...

Synthesis and evaluation of ampicillin-conjugated gum arabic microspheres for sustained release.

Abstract: Ampicillin was conjugated to periodate-oxidized gum arabic (GA), a branched polysaccharide, to form the imino conjugate of the drug and the polysaccharide. The water-soluble conjugate was dispersed by sonication in a mixture of toluene and liquid paraffin in the presence of a non-ionic surfactant as droplet stabilizer and fabricated into microspheres by heat denaturation at 80 degrees C to obtain spheres less than 2 microm in diameter. These microspheres did not undergo dissolution in water on prolonged incubation. In-vitro release of ampicillin into phosphate buffer from the microspheres was slow and sustained with a cumulative release between 10 and 25% of the drug content in 10 days depending on the degree of oxidation of GA and the drug payload. Release into simulated gastric fluid was faster due to faster hydrolysis of the drug-GA bond in the acid medium, but when the medium was changed to intestinal fluid, the release was slowed down. Ampicillin released was functionally active and inhibited the growth of S. aureus and E. coli in cultures, although not as actively as free ampicillin. The microspheres underwent slow biodegradation on prolonged incubation in aqueous media. These studies show that ampicillin conjugated with oxidized GA and fabricated into microspheres possesses sustained-release characteristics for prolonged periods.

Setting phase change energy storage material with high-thermal conductivity and preparation method thereof

Abstract: The invention relates to a setting phase change energy storage material with high-thermal conductivity and a preparation method thereof, belonging to the field of phase change heat storage materials. The setting phase change energy storage material with high-thermal conductivity is characterized by containing 65-90 percent by mass of paraffin substances as a phase-change material, 9-34 percent by mass of high-density polyethylene as a support material and 1-7 percent by mass of expanded graphite as a heat conduction intensifier; a method for adding a proper amount of expanded graphite to paraffin/high-density polyethylene in a molten state is adopted to enable the heat conductivity of the setting phase change material to be increased to 1.35W/(m.K) or higher. The method comprises the following steps of: heating to melt the paraffin substances with the mass percent of 65-90 percent, and heating to enable the temperature of the liquid paraffin to reach 120-190 DEG C; adding high-density polyethylene with the mass percent of 9-34 percent and the expanded graphite with the mass percent of 1-7 percent to the liquid paraffin, and then melting and evenly stirring in vacuum; putting the mixture in a hot mould for pressing and molding; taking the mixture from the mould after naturally cooling. The setting phase change material has high thermal conductivity, does not need to be packaged in containers and can directly contact heat-transfer media.

Investigation of Flavonoidal Content and Biological Activities of Chorisia Insignis Hbk. Leaves

Abstract: Leaves of Chorisia insignis HBK. (Family Bombacaceae) were studied for their flavonoidal content. The n-butanol fraction of the 70% ethanol extract was subjected to different chromatographic methods (column chromatography, preparative paper chromatography and /or preparative thin layer chromatography). Three flavonoids were isolated for the first time from the genus Chorisia; Rutin, Luteolin-7-O-� -D-rutinoside and Apigenin-7-O-� -D-rutinoside. Their chemical structures were established using UV, 1 H-NMR, 13 C-NMR and ESI-MS spectral data as well as acid hydrolysis. The LD50 of the total and the aqueous extracts and the successive fractions of the 70% ethanol extract revealed low toxicity of the plant. All the extracts showed significant anti-inflammatory activities against carrageenan-induced rat paw oedema as compared with indomethacin. Significant antihyperglycemic activities were exhibited by the total and the aqueous extracts and the ethyl acetate fraction in alloxan-induced diabetic rats as compared with metformin. The total and the aqueous extracts and the ethyl acetate and n-butanol fractions showed significant antioxidant activities as indicated by the rise in blood glutathione in diabetic rats as compared with vitamin E. Pretreatment of rats with the total extract, the aqueous extract or the ethyl acetate fraction for one month before and after liver damage, induced by intraperitoneal injection of 5 ml/kg of 25% CCl4 in liquid paraffin, resulted in significant decrease in AST, ALT and ALP as compared with silymarin, revealing significant hepatoprotective activities of these extracts.

Floating-mucoadhesive beads of clarithromycin for the treatment of Helicobacter pylori infection.

Abstract: An objective of the present study was to develop alginate/hydroxypropyl methylcellulose (HPMC) based floating-mucoadhesive beads of clarithromycin to provide prolonged contact time of antibiotic to treat stomach ulcer. Floating-mucoadhesive beads were prepared and characterized for in vitro performance followed by investigation of ex vivo study in albino-wistar rats. Beads were prepared by ionic gelation technique where calcium chloride used as gelating agent and incorporated liquid paraffin for floating of the beads. Prepared beads were evaluated extensively for particle size, drug entrapment; swelling and surface morphology by using scanning electron microscopy. X-ray radioimaging study in rabbits, in vitro mucoadhesion using rat stomach mucosal membrane and in vitro drug release studies were carried out. Ex vivo performance of alginate-HPMC beads were studied using albino rats in comparison to simple alginate-calcium beads. Alginate-HPMC beads may be suitable floating-muco-adhesive drug delivery system for delivering clarithromycin to treat stomach ulcers.

“One-pot” synthesis and shape control of ZnSe semiconductor nanocrystals in liquid paraffin

Abstract: In this paper, we demonstrated a “one-pot” strategy for synthesizing ZnSe nanocrystals (NCs) in liquid paraffin. All materials, including Zn source, Se source, and ligand, were mixed in liquid paraffin beforehand, which avoided the injection of Se source at high temperature. The resultant ZnSe NCs possessed high photoluminescence quantum yields and narrow size distribution. Moreover, the size, shape, and crystal phase of NCs were controllable by altering the experimental variables, such as precursor concentration, Zn:Se molar ratio, and heating rate. Because the raw materials used here were low-cost and environmentally friendly, this “one-pot” synthetic protocol would facilitate the commercial scale synthesis of high-quality ZnSe NCs.

Synthesis and Tribology Properties of Stearate-Coated Ag Nanoparticles

Abstract: Stearate-coated silver nanoparticles were synthesized in water solutions through the chemical reduction method. The morphology, structure, and thermal properties of the coated Ag nanoparticles were investigated with transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential thermal analysis. Their tribological properties were evaluated on a four-ball test machine. The rubbed surface was investigated by scanning electron microscopy. The results show that the stearate-coated Ag nanoparticles have an average particle size in the range of 8-10 nm, and the coated Ag nanoparticles as oil additives in liquid paraffin exhibit excellent tribological properties.

Formulation and characterization of a cream containing extract of fenugreek seeds.

Abstract: Fenugreek seeds possess antioxidant effects and contain a mucilage which has emollient properties It can also produce skin healing, whitening, moisturizing, skin soothening and antiwrinkle effects The purpose of study was to formulate a stable W/O emulsion containing fenugreek seeds extract using liquid paraffin oil Fenugreek seeds extract, which was obtained by concentrating methanolic extract of fenugreek seeds, was entrapped in the inner aqueous phase of W/O emulsion A base containing no active material and a formulation containing concentrated extract of fenugreek (in a concentration of 4%) in the internal aqueous phase (W/O emulsion) were prepared and stored at different accelerated conditions for a period of four weeks to predict the stability of these creams It was found that both, the base and the formulation, were stable at all the accelerated conditions regarding color, liquifaction and phase separation However, insignificant changes in the pH of base and significant changes in the pH of the formulation were observed with the passage of time Both the base and the formulation were applied to the cheeks of human volunteers for six weeks and various parameters of the skin were evaluated every week to measure any effect produced by these creams All the effects of base were statistically significant except the sebum contents and pH, which changed but insignificantly A significant decrease on skin melanin and erythma was produced by the formulation An insignificant decrease in TEWL was observed for the formulation

Phase-change energy storage plastic

Abstract: The invention relates to a phase-change energy storage plastic, which comprises the main components of n-alkanes (paraffin and liquid paraffin), polyolefins (polyethylene, polypropylene and polybutene), ethylene and vinyl acetate copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer, plastic additives (lubricant, plasticizer, ultraviolet screener and flame retardant), reinforcing fillers (whisker, carbon fiber and white carbon black), heat conduction fillers (graphite, calcium carbonate, aluminum oxide, aluminum nitride, silicon nitride and metal powder), pigment and the like, wherein more than two types of the materials are mixed together in certain proportion, then the mixture is smelted, extruded and granulated or is molded through blow molding and injection molding to obtain particles, plates, sheets, films, containers and the like. The phase-change energy storage plastic is used for manufacturing heat storage plastic pipes (ground heating or capillary networks for heating), fresh-keeping and heat preservation containers, mobile phone shells, electronic device components and the like.

Influence of gamma-irradiation, growth retardants and coatings on the shelf life of winter guava fruits (Psidium guajava L.).

Abstract: Experiment was conducted to study the effect of gamma irradiation, growth retardants and coatings (coconut oil, mustard oil and liquid paraffin) on shelf life of winter guava fruits during storage. The results revealed that the superiority of coconut oil coating over other post harvest treatments. Physiological loss in weight (7.1%), marketable fruits retained over control (86.7%), total soluble solid (16.1%), ascorbic acid (195 mg/100 g pulp) and total sugar (10%) of fruit were positively influenced by coconut oil coating up to 12 days of storage. The treatment was found significantly effective in increasing the post harvest life of fruits for 12 days over control without adversely affecting the fruit quality. Coconut oil coating gave highest consumer acceptability while, maintaining sufficient level of total soluble solids and sugar content in fruits.