Sequential pretreatment to recover carbohydrates and phosphorus from Desmodesmus sp. cultivated in municipal wastewater.

This study focused on the simultaneous recovery of carbohydrates (CHO) and phosphorus (P) from Desmodesmus sp. biomass cultivated in municipal wastewater, through a sequential pretreatment. The pretreatment consisted first of ultrasound to trigger cell disruption followed by ozonation to recover CHO and P. For ozone pretreatment, three different parameters were considered: ozone concentration (9, 15, 21, 27, 36, and 45 mg O3/L), contact time (15, 25 and 35 min), and pH (8 and 11). The maximum simultaneous release of 84% of CHO and 58% of P was achieved at the experimental parameters of ozone concentration of 45 mg O3/L, contact time of 35 min, and pH of 11. Also, P was concentrated in solution by 8- to 14-fold with respect to municipal wastewater. The sequential pretreatment was conducted at alkaline pH of 11 and atmospheric conditions, which may considerably reduce energy demand and reagents, in comparison to a traditional hydrolysis pretreatment. The results found suggest that the sequential pretreatment could be feasible on a large scale.

Intensified recovery of lipids, proteins, and carbohydrates from wastewater-grown microalgae Desmodesmus sp. by using ultrasound or ozone.

This study evaluates the effect of ultrasound and ozone pretreatments for the subsequent recovery of Desmodesmus sp. biocomponents-lipids, proteins, and carbohydrates-using a response surface methodology. Both pretreatments impact on the recovered lipids quality, solvent waste production and extraction time is analysed for process intensification purposes. For ultrasound pretreatment, independent parameters were energy applied (50-200 kWh/kg dry biomass), biomass concentration (25-75 g/L), and ultrasonic intensity (0.32 and 0.53 W/mL). While for ozone pretreatment, independent parameters were ozone concentration (3-9 mg O3/L), biomass concentration (25-75 g/L), and contact time (5-15 min). In the case of ultrasound pretreatment, recovery yield reached 97 ±â€¯0.4%, 89 ±â€¯3%, and 73 ±â€¯0.6% for proteins, carbohydrates and lipids respectively. Given process required: energy applied of 50 kWh/kg dry biomass, 75 g/L of biomass concentration, 0.32 W/mL of ultrasonic intensity, and 56 min of time process. Ultrasound caused high cell disruption releasing all proteins, thereby obviating downstream processing for its recovery. Ozone pretreatment recovery yield was 85 ±â€¯2%, 48 ±â€¯1.4%, and 25 ±â€¯1.3%, for carbohydrates, lipids and proteins respectively, under the following conditions: 9 mg O3/L of ozone concentration, 25 g/L of biomass concentration, and 5 min of contact time that depicts an energy consumption of 30.64 kWh/kg dry biomass. It was found that ultrasound and ozone pretreatments intensified the lysis and biocomponents recovery process by reducing solvent consumption by at least 92% and extraction time between 80% and 90% compared with extraction of untreated biomass biocomponents. Both pretreatments improve the composition of the recovered lipids. It was noted that the yield of neutral lipids increased from 28% to 67% for ultrasound pretreatment while for ozone pretreatment from 49% to 63%. The method used for lipid extraction may also have an effect but here it was kept constant.

Photocatalytic reduction of Cr(VI) from agricultural soil column leachates using zinc oxide under UV light irradiation.

The photocatalytic reduction of Cr(VI) from agricultural soil leachates irrigated with Cr(VI)-containing waste hydroponic solution was evaluated in this work. For this purpose, zinc oxide was used as a catalyst under UV irradiation (lambda = 365 nm). The reduction of Cr(VI) was preliminarily evaluated on synthetic solutions with a concentration of 15 mg L(-1) to optimize the catalyst loading and the solution pH and to determine the effect of organic matter. Greater removal of Cr(VI) was observed at pH 7, and the optimum catalyst loading was found to be 2 g L(-1), which achieved an 84% Cr(VI) reduction in 6 h. The influence of dissolved organic matter on the reduction of Cr(VI) was evaluated through the addition of different concentrations of humic acid (HA) to the chromium solution. The removal of Cr(VI) was continuously enhanced as the HA concentration gradually increased from 0 to 14 mg L(-1). The percentage of hexavalent chromium reduction from soil leachates was in the range of 13-99%, and the rate constant was significantly enhanced by the presence of organic compounds in the soil pore water. Thus, a marked synergistic effect between the photocatalytic reduction of Cr(VI) and the organic matter in soil (e.g. humic substances) was observed in real samples and was similar to that observed in the Cr(VI) synthetic solution that contained HA.

Relation of serum cholesterol, lipid, serotonin and tryptophan levels to severity of depression and to suicide attempts.

OBJECTIVE: To determine if there is a relation to low serum cholesterol, lipoprotein, serotonin or tryptophan levels in patients with depression who have recently attempted suicide. DESIGN: Biochemical and behavioural study. SETTING: Inpatient and outpatient treatment at the Instituto Mexicano de Psiquiatría. PARTICIPANTS: Thirty-three patients with a diagnosis of major depressive episode. Eighteen of these patients had attempted suicide in the month before the start of the study; 15 patients had never attempted suicide. OUTCOME MEASURES: Serum levels of total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, serotonin (5-HT) and tryptophan. Scores on Hamilton Depression Rating Scale, Carroll Depression Rating Scale, Beck Hopelessness Scale and Beck Suicide Attempt Severity Scale. RESULTS: There were no significant differences between patients who had attempted suicide and those who had not in terms of serum cholesterol, HDL, LDL and triglyceride levels. Serum levels of 5-HT and tryptophan were significantly lower in patients with depression who had a recent suicide attempt than in those patients who had never attempted suicide. A comparison of patients not taking antidepressant medication found serum 5-HT levels to be more than 3 times lower in those patients with a recent suicide attempt than in patients with no history of suicide attempt. CONCLUSIONS: The study found no difference in lipid profiles between patients who had attempted suicide and those who had not. Low serum levels of 5-HT may increase the risk of suicide attempt in patients who are depressed.

The pathogenic effect of IgG4 autoantibodies in endemic pemphigus foliaceus (fogo selvagem).

Endemic pemphigus foliaceus, or fogo selvagem, is an autoimmune blistering skin disease caused by IgG autoantibodies to a desmosome-associated glycoprotein. We studied the IgG subclasses with autoantibody activity in serum from 29 patients with active disease and in the skin lesions of 18 patients by immunofluorescence, using IgG-subclass-specific monoclonal antibodies. The predominant disease autoantibodies present in all patients were of the IgG4 subclass. IgG1 and IgG2 autoantibodies were detected in low titer in the 29 patients: IgG1 in 23 patients and IgG2 in 9. IgG3 autoantibodies were not detected in the serum of any patient. Direct immunofluorescence testing of skin lesions showed a preferential deposition of IgG4 on the keratinocyte surface. The pathogenic effect of IgG4 was demonstrated by the passive transfer of fractions containing IgG4 autoantibodies from the patients to neonatal BALB/c mice. The disease of the patients was reproduced clinically, histologically, and immunologically in these animals. Only IgG4 autoantibodies were detected by direct immunofluorescence, bound to the epidermis in the lesions of the mice, and by immunoelectron microscopy at the keratinocyte surface. IgG4 has previously been reported to be a blocking or protective antibody because it has poor effector functions in vitro, as compared with the other IgG subclasses. The finding that it is the pathogenic autoantibody in fogo selvagem raises the possibility that it may also be important in other autoimmune disease.