Use of supercritical methanol/carbon dioxide mixtures for biodiesel production

The use of supercritical conditions for the production of biodiesel from both vegetables oils and waste-oils may be of great industrial interest because it can be carried out without those catalysts necessary in the conventional transesterification process, therefore avoiding a complex separation between the product and the catalyst. However, the use of supercritical alcohol requires higher operating temperatures and pressures. In this work, CO₂ was added to the reaction mixture in order to reduce the operating conditions (temperature, pressure and molar ratio of alcohol to vegetable oil). The novelty of using CO₂ may have two advantages: a possible combination of supercritical CO₂ extraction of the oil and its subsequent transesterification reaction without CO₂ depressurization, and a reduction of the supercritical temperature and pressure of the mixture. The effects of temperature (280-350 °C), pressure (140-280 bar), methanol-to-oil molar ratio (20-30), CO₂-to-methanol molar ratio (0.05-0.2) and residence time (0-45minutes) on the yield of methyl esters (biodiesel) were studied in a batch reactor, obtaining in all cases a relatively low increase in the yield when CO₂ was present in the medium. The yields of biodiesel were tested with three vegetable oils used as model compounds (palm, sunflower and borage), obtaining similar results.     

Monitoring sodium chloride during cod fish desalting process by flow injection spectrometry and infrared spectroscopy

In order to adapt to the market trends that are moving towards ready-to-use products cod fish industry is including into their industrial operations as the desalting step. The desalting process is a high cost and time demanding operation. The optimization of the desalting process is of vital importance for the fish industry in order to assure the homogeneity and predictable concentration of sodium chloride in the final hydrated cod fish product. On the other hand, consumers are more aware about the necessity to bring sodium consumption down to healthy levels to prevent cardiovascular diseases. The application of rapid and simple analytical methodologies that permit the control of the process and ensure food quality is essential in the food industries.This work reports the optimization and application of two analytical methodologies with the objective of monitoring the variation of sodium chloride concentration during cod desalting process. A flow injection analysis system was developed based on the reaction between chloride and silver nitrate, and the formed precipitate was assessed spectrophotometrically as a turbidity change. A Fourier-mid infrared spectroscopy attenuated total reflection method was also applied. Different chemical and physical parameters of the flow injection system were studied and the analytical characteristics of both systems were compared.     

Preparation of TiO2 coatings on PET monoliths for the photocatalytic elimination of trichloroethylene in the gas phase

This paper presents the first data on the performance of polyethylene terephthalate (PET) monoliths as photocatalytic support. For this purpose, first a protective layer of SiO₂ was applied to the polymer to prevent oxidation of the substrate, and subsequently the photoactive layer of TiO₂ was deposited on PET monoliths using the dip-coating technique. In order to increase the adherence of inorganic coatings, two different synthesis procedures were evaluated. One approach was based on reducing the surface tension of the SiO₂ sol using a fluorinated surfactant to increment the PET wettability. The second approach consisted in modifying the PET surface with a layer of the polymer poly(diallyldimethylammonium) chloride (PDDA), which provides a positively charged surface for the fixation of the alkaline SiO₂ sol. Both TiO₂/SiO₂ coated PET monoliths were assayed in a single-pass annular reactor for the destruction of trichloroethylene (TCE). The two coating procedures were compared in terms of homogeneity, durability and photocatalytic activity.     

Calcium and protein intake and bone markers in premenopausic and posmenopausic women with normal bone mineral density from Comodoro Rivadavia (Argentina)

Healthy premenopausal women (Pre n=28) and posmenopausal (Pos n=22), living in Comodoro Rivadavia (Argentina), with normal femoral neck and lumbar spine bone mineral density (BMD) were studied. Usual daily calcium intake (CaI) and protein intake (PrI) were calculated according to an special questionaire and the National Food Composition Tables. Fasting blood samples and 24 h urine were collected. Laboratory measurements were: in urine (U): calcium (Ca), creatinine (Crea) and deoxypiridinoline (Dpyr); in serum: Bone Alkaline Phosphatase (BAPh). The results presented the following media +/- SD (minimum - maximum) in Pre and Pos, respectively: CaI (mg/d): 694 +/- 411 (190 - 2,117); 918 +/- 304 (471 - 1740) (p < 0.01); PrI (g/d): 64.6 +/- 25.4 (33.5 - 136); 63.7 +/- 17.6 (41.5 - 95.2); daily UCa (mg/d): 123 +/- 85 (20 +/- 369); 114 +/- 66 (17 - 252); Ca/crea (mg/mg): 0.124 +/- 0.086 (0.014 - 0.372); 0.131 +/- 0.077 (0.020 - 0.338); Dpyr/crea (nM/mM): 5.5 +/- 1.5 (3.4 - 10.3); 7.1 +/- 2.3 (3.9 - 14.5) (p < 0.01); BAPh (UI/l): 58 +/- 12 (28 - 94); 70 +/- 20 (32 - 99) (p < 0.01). CaI was lower than the Adequate Dietary calcium intake in 86% and 82% of the Pre and Pos women, respectively. There was no correlation between CaI, PrI and the biochemical indicators. Conclusions: in these healthy women, without bone mass loss and with wide range of CaI, although usually low, markers of bone turnover, would be a balance between the increase of bone formation and resorption.     

Wind pressures and buckling of cylindrical steel tanks with a dome roof

An experimental/computational strategy is used in this paper to evaluate the buckling behavior of steel tanks with a dome roof under exposure to wind. First, wind tunnel experiments using small scale rigid models were carried out, from which pressure distributions due to wind on the cylindrical part and on the roof were obtained. Second, a computational model of the structure (using the pressures obtained in the experiments) was used to evaluate buckling loads and modes and to study the imperfection sensitivity of the tanks. The computational tools used were bifurcation buckling analysis (eigenvalue analysis) and geometrical nonlinear analysis (step-by-step incremental analysis). Geometric imperfections and changes in the buckling results due to reductions in the thickness were also included in the study to investigate reductions in the buckling strength of the shell. For the geometries considered, the results show low imperfection sensitivity of the tanks and buckling loads associated with wind speeds 45% higher than those specified by the ASCE 7-02 standard.     

Treatment of benign hepatic cysts by instillation of tetracycline hydrochloride

BACKGROUND/AIMS: Despite the high frequency of benign hepatic cysts, they rarely cause symptoms. Large cysts, however, may produce clinical manifestations. In these cases, ultrasonography-guided therapy has been proposed. We report the results of this therapy in patients with symptomatic benign hepatic cysts. METHODOLOGY: Seven patients with non-parasitic, non-neoplastic benign hepatic cysts were submitted to fine-needle ultrasonography-guided aspiration, followed by injection of diluted tetracycline hydrochloride (1 g). In all cases, cytology, tumour markers and microbiology analysis of aspirates were performed. One patient required two sessions. The grade of patient satisfaction and ultrasonography changes were assessed 1, 3 and 6 months after the procedure. RESULTS: Cyst size decreased in all patient, with total collapse in three. No major complications occurred. Cytology, alpha fetoprotein, CA19.9, CEA and microbiology of the cyst fluid confirmed the initial ultrasonographic diagnosis of simple biliary cysts. Clinical complaints improved in 2 cases, and 5 patients became asymptomatic. Ultrasonography evaluation 3 months after the procedure was more reliable in predicting successful treatment. CONCLUSION: Intracystic instillation of tetracycline hydrochloride is an effective and safe technique and may become the first choice therapy for benign hepatic cysts.     

Controlled Inline Fluid Separation Based on Smart Process Tomography Sensors

Today's mechanical fluid separators in industry are mostly operated without any control to maintain efficient separation for varying inlet conditions. Controlling inline fluid separators, on the other hand, is challenging since the process is very fast and measurements in the multiphase stream are difficult as conventional sensors typically fail here. With recent improvement of process tomography sensors and increased processing power of smart computers, such sensors can now be potentially used in inline fluid separation. Concepts for tomography-controlled inline fluid separation were developed, comprising electrical tomography and wire-mesh sensors, fast and massive data processing and appropriate process control strategy. Solutions and ideas presented in this paper base on process models derived from theoretical investigation, numerical simulations and analysis of experimental data.     

Erythrocyte protoporphyrin during recovery from malnutrition in rats

Interrelationships between Erythrocyte Protoporphyrin (EP), dietary Iron/Protein ratio (Fe/Prot) and Fe liver content (Feh) were studied during nutritional recovery in an experimental model: weanling female Wistar rats (To) were depleted with a protein-free diet (LP), losing 20% of their initial body weight. Then they were recovered until 45 days of age (T45) with diets containing: casein: 20 g/100 g; Fe (ammonium Fe citrate) (ppm.): 0, 75 or 100 (groups A1, A2 and A3, respectively). Hematocrit, Hemoglobin (Hb) (g/dL). Erythrocyte Protoporphyrin (EP) (microgram/dL Red Blood Cells) and Feh (microgram) were determined at To, LP and T45. Results were compared with control rats (C) fed with 20% of casein and Fe, 50 ppm. EP: a) decreased in C from To to T45 (99 +/- 24; 36 +/- 9; p < 0.01); b) increased in A1 and A2 at T45 (123 +/- 21; 93 +/- 29, respectively, p < 0.01) while A3 did not show significant difference (45 +/- 7) regarding to C: c) correlated inversely with Feh. According to the inverse correlation between EP and Fe/Prot (r = -0.99), we found that 92 ppm was an adequate Fe amount to prevent EP increase. These results confirm that during recovery from undernutrition EP depends on iron liver content, being an adequate indicator of iron nutritional status; therefore, EP would be useful as a predictor of the optimum Fe/Prot ratio for nutritional recovery.