Supercritical fluid extraction of hops

Five cultivars of hop were extracted by the method of supercritical fluid extraction using carbon dioxide (SFE–CO2) as extractant. The extraction (50 g of hop sample using a CO2 flow rate of 97.725 L/h) was done in the two steps: 1. extraction at 150 bar and 40°C for 2.5 h (sample of series A was obtained) and, after that, the same sample of hop was extracted in the second step: 2. extraction at 300 bar and 40 °C for 2.5 h (sample of series B was obtained). The Magnum cultivar was chosen for the investigation of the extraction kinetics. For the qualitative and quantitative analysis of the obtained hop extracts, the GC-MS method was used. Two of four themost common compounds of hop aroma (a-humulene and b-caryophyllene) were detected in samples of series A. In addition, isomerized a-acids and a high content of b-acids were detected. The a-acids content in the samples of series B was the highest in the extract of the Magnum cultivar (it is a bitter variety of hop). The low contents of a-acids in all the other hop samples resulted in extracts with low a-acids content, i.e., that contents were under the prescribed a-acids content

Performance Comparison of Alternating Direction Optimization Methods for Linear-OPF based Real-time Predictive Control

International audienceThe paper contributes to improving the computational performance of controls of distributed energy resources (DERs) in distribution grids for efficient real-time control and short-term scheduling. The considered setting is a distribution grid with heterogeneous DERs controlled with model predictive control (MPC) to track a dispatch plan at its grid connection point (GCP) subject to DERs’ and grid’s constraints. The MPC control is first expressed as a quadratic programming (using linearized grid models) and, then, solved with several state-of-the-art alternating direction optimization methods: AMA, ADMM, AADMM (ADMM with adaptive penalty parameter) and their accelerated variants: FAMA, FAADMM, and FAADMM with restart rule. Performance is tested in terms of computational performance, constraints satisfaction, and optimality against the centralized MPC. The case studies are the CIGRE and IEEE benchmark grid for low- and medium voltage systems hosting different numbers of controllable DERs

CHARACTERIZATION AND MONITORING OF THE CRACK SELF-HEALING ABILITY OF BIO-MORTAR

It is known that bacteria can promote self-healing of the cracks in concrete structures, but the elevated pH value of the cement-based concrete matrix affects negatively the bacteria living time and consequently the self-healing effect. Therefore, a method for encapsulation of bacteria healing agent in a polymer hydrogel system has been successfully established to protect the bacteria from surrounding environment. In order to investigate the healing capacity of the employed bacterial colony and the effectiveness of the proposed encapsulation methods, three groups of mortar specimens were systematically prepared: standard reference samples, samples with hydrogel and bio-mortar samples (with bacteria species encapsulated in the hydrogel system surrounded with nutrition). Microstructure and texture analysis were performed before and after the healing treatment. The mortar specimens were notched at mid-span and pre-cracked by means of 3-point bending tests performed in CMOD-control mode. Water sorption tests were performed periodically in order to ascertain the effects of healing on the recovery of durability performance. The healing ability was also measured by crack opening displacement change by optical microscopy. The specimens were tested in 3-point bending up to failure, to assess the effect of the healing, if any. A cross-comparison analysis of the obtained results was provided

Arsenic contamination in environment in the region of Vojvodina

Ground waters in the region of Autonomous Province of Vojvodina, Republic of Serbia are endangered by arsenic (up to 0.750 mg/l). Total arsenic concentration was determined In samples of untreated and treated water from some local and central water-supply systems. Results are compared to actual regulations in the country. This analysis encompassed 324 drinking water samples of various sources. Analyzed in the Inst. of Pub. Hlth. Novi Sad, during 2005. Determined Concentration of Total Arsenic in Drinking Water Varies from 0.005 to 0.450 Mg/l. Arsenic Concentration in the River Danube Water Was Within Recommended Value for L-ll Class. Maximum Arsenic Daily Intake Through Food and Nutr. Was 60.9 ± 22.3 (G/day in 2000. to Understand Importance of the Prob. of Arsenic Environ. Contamination in Vojvodina Reg., Our Own Results, As Well As the Results of Other Authors Are Presented and Analyzed (Drinking Water: 173 Samples, Moss Deposition and Daily Intake Through Nutr.)