Identification of organic acids in secondary organic aerosol and the corresponding gas phase from chamber experiments

Organic acids in the gas and aerosol phase from photooxidation of 1,3,5-trimethylbenzene in the presence of 300 ppb propene and 300 ppb NOx in smog chamber experiments were determined using a wet effluent diffusion denuder/aerosol collector coupled to ion chromatography (IC) with conductivity detection. Behind the IC, the samples were collected using a fraction collector, for identification of unresolved/unidentified organic acids with IC-mass spectrometry (MS). In total, 20 organic acids were found with MS of which 10 were identified. The organic acids identified offline by IC-MS were then further quantified based on the online IC data. The identification was additionally confirmed with gas chromatography-mass spectrometry. At the maximum aerosol concentration, organic acids comprised 20-45% of the total aerosol mass. The method has a detection limit of 10-100 ng/m3 for the identified carboxylic acids.     

Design optimization of a solar tower power plant heliostat field by considering different heliostat shapes

The present study focuses on the optimization of solar tower power plant heliostat field by considering different heliostat shapes including rectangular, square, pentagon, hexagon, heptagon, octagon, and circular heliostat shapes. The optimization is carried out using an in-house developed code-based MATLAB program. The developed in-house code is validated first on a well-known PS10 Solar Thermal Power plant having rectangular heliostats shape and the resulting yearly unweighted heliostat field efficiency of about 64.43% could be obtained. The optimized PS10 heliostat field using different heliostat shapes showed that the circular and octagon heliostat shapes provide better efficiency with minimum land area. The yearly efficiency is increased from 69.65% for the rectangular heliostat shape to 70.96% and 71% for the octagon and circular shapes, respectively. In addition, the calculated field area (land area) is reduced for the case of circular and octagon heliostat shapes with a gain of about 11.10% and 10.93% (about 42.0436 × 10³ and 41.4036 × 10³ m²), respectively, in comparison with the PS10 field area.     

Pubic tuberculous osteo-arthritis. Apropos of 2 cases

OBJECTIVE: The authors report an exceptional site of tuberculous osteo-articular infection which must be diagnosed before the destructive stage. OBSERVATIONS: Case 1 : a 21 years old woman presented an inflammatory pubic pain after a trauma with weight loss of 4 kgs in 3 weeks. She presented also 2 satellite inguinal nodes. Erythrocyte sedimentation rate (ESR) was elevated, X-rays showed an important osteolysis of the left ischio-pubic rami, tuberculous skin test (TST) was positive, mycobacterium tuberculosis (MT) could not be found neither in sputtum nor in urine but the node biopsy showed the specific features of tuberculosis. Evolution under a 6 months antibiotic treatment was good. Case 2 : a 19 years old woman, with history of tuberculous contagion, presented in April 1996 cervical nodes and a month later inflammatory pubic and knee pain with weight loss and vesperal sudation. ESR was elevated, TST was phlyctenular, MT searching and HIV serology were negative. X rays showed irregular osteolysis of the pubic symphysis. Scintigraphy showed an increased fixation of pubis and left knee. Cervical nodes biopsy diagnosed tuberculosis. Evolution was good under a 6 months antibiotic treatment. DISCUSSION: Many factors can favorize the development of a pubic tuberculosis and are similar for all forms of tuberculous osteo-articular infection (trauma and contagion in our cases). Radiological features, characterized by a slow evolution, are note specific. Diagnostic confirmation must be bacteriologic or pathologic, and if possible far from the pubic foci. Any traumatic medical procedure has to be avoided because of painful outcome and local risk. Evolution under specific treatment, even of short course (6 months), is sufficient for a good outcome. CONCLUSION: One must think to pubic tuberculous osteo-arthritis in any pubic pain even if it is post-traumatic especially, in endemic countries of tuberculosis.     

Biosurfactant-Assisted Bioremediation of Polycyclic Aromatic Hydrocarbons (PAHs) in Liquid Culture System and Substrate Interactions

A lipopeptide biosurfactant was produced by the bacterium Pseudomonas aeruginosa strain LBP9 isolated from petroleum-contaminated soil. Phenanthrene, fluoranthene, and pyrene were used as model polycyclic aromatic hydrocarbons (PAHs) to study the effect of the biosurfactant on the biodegradation of mixed and sole substrate PAHs, and examine substrate interactivity effects on their biodegradation in liquid culture. At 400 mg/L amendment of lipopeptide, the solubility of phenanthrene, fluoranthene, and pyrene were increased to 19, 33, and 45 times their aqueous solubility, respectively, and the extent of substrate utilization rate (q_max?) of PAHs was enhanced up to three-fold in the sole substrate studies in comparison to the unamended controls. In the ternary PAH mixture at total concentration of 300 mg/L, with equal parts of each PAH, 77%, 57%, and 33% degradation of phenanthrene, fluoranthene, and pyrene were observed, respectively, at 400 mg/L lipopeptide amendment on day 30 of incubation. Whereas in the sole substrate experiments at 300 mg/L concentration of each PAH and the same level of lipopeptide amendment more than 98% fluoranthene and 76% pyrene were degraded and phenanthrene removal was so rapid that at day 4 of incubation more than 80% was degraded. Biosurfactants at optimum amounts enhanced biodegradation of PAHs. Lipopeptide amendments of 200 mg/L and 400 mg/L were found out to be optimum amounts for statistically significant (p < 0.05) biodegradation of the PAHs in the experiments. However, despite biosurfactant-enhanced bioavailability of the PAHs, biodegradation rate was competitively inhibited in the multisubstrate microcosms.     

Chemical characterisation and determination of sensory attributes of hydrolysates produced by enzymatic hydrolysis of whey proteins following a novel integrative process

The overall aim of this work was to characterise the major angiotensin-converting enzyme (ACE) inhibitory peptides produced by enzymatic hydrolysis of whey proteins, through the application of a novel integrative process. This process consisted of the combination of adsorption and microfiltration within a stirred cell unit for the selective immobilisation of β-lactoglobulin and casein-derived peptides (CDP) from whey. The adsorbed proteins were hydrolysed in situ, which resulted in the separation of peptide products from the substrate and fractionation of peptides. Two different hydrolysates were produced: (i) from CDP (IC₅₀ = 287 μg/mL) and (ii) from β-lactoglobulin (IC₅₀ = 128 μg/mL). The well-known antihypertensive peptide IPP and several novel peptides that have structural similarities with reported ACE inhibitory peptides were identified and characterised in both hydrolysates. Furthermore, the hydrolysates were assessed for bitterness. No significant difference was found between the bitterness of the control (milk with no hydrolysate) and hydrolysate samples at different concentrations (at, below and above the IC₅₀).     

Bioremediation of Polycyclic Aromatic Hydrocarbon Contaminated Soil by a Microbial Consortium through Supplementation of Biosurfactant Produced by Pseudomonas aeruginosa Strain

Lipopeptide biosurfactant produced by Pseudomonas aeruginosa Lbp 3 strain isolated from petroleum contaminated soil was investigated for its potential to enhance bioavailability, and hence, the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil microcosms. Experiments were conducted on a soil spiked with equal parts of the PAHs Phenanthrene, Fluoranthene, and Pyrene to a final concentration of 1200 mg of total PAHs per kg of dry soil. To evaluate biodegradation enhancement efficiency, 50 g spiked soil samples were supplemented with 50 mgL^?1, 100 mgL^?1, 300 mgL^?1, and 1000 mgL^?1of lipopeptide dissolved in 30 mL of MSM, and incubated for 40 days at 30°C in darkness. Statistically significant (P < 0.05) biodegradation rates were observed in all the amended microcosms in comparison to the unamended controls. Maximal biodegradations (> 96% of Phenanthrene and Fluoranthene and > 93% of Pyrene) were observed in the soil microcosms supplemented with 1000 mgL^?1and 50 mgL^?1 lipopeptide. The effect of substrate interactivity of the PAHs on the biodegradation kinetics was also tested in comparison with sole substrate microcosms. Competitive inhibition of the biodegradation of low molecular weight PAHs was observed as a result of substrate interactivity in the multisubstrate system.     

Evaporation, Unsaturated Flow, and Salt Accumulation in Multilayer Deposits of “Paste” Gold Tailings

Both the geotechnical and geoenvironmental performances of surface deposited “paste” mine tailings are strongly influenced by desiccation, rewetting after precipitation, as well as interlayer flow. All these processes strongly depend on unsaturated flow within the tailings. Modeling of small (0.15 m in diameter)- and large (1.7?m×1.7?m in plan)-scale tests on two-layer deposits of paste gold tailings showed that desiccation and interlayer flow can be reasonably modeled using one-dimensional unsaturated flow codes, if volume change and its effect on the water-retention curve are considered. Though significant cracking occurred during drying of the paste tailings, its influence on the rate of evaporation was minimal. In some of the tests, the accumulation of salt at the surface substantially suppressed the rate of evaporation. The transport of ions leading to the accumulation of salt is modeled using a one-dimensional contaminant transport code coupled to the unsaturated flow code. The results provide insight into the coupling between evaporation and the accumulation of salts at the tailings’ surface.