Binding of cadmium,copper, and zinc to humic substances originating from municipal solid waste compost

The application of municipal solid waste (MSW) compost increases both the trace metal loading and the organic matter in the soil. To characterize the quality and metal-binding capacity of the compost OM, we extracted humic acid (HA) and fulvic acid (FA) from mature MSW compost and analyzed them for elemental composition, acid-titratable functional groups, total metal content, and structural components (by ¹³C NMR). HA constituted 67% of all extracted humic substances and differed significantly from HAs of cultivated lands: The compost HA exhibited smaller molecular size, a higher N content, and lower aromaticity due to large amounts of saturated aliphatic components. Metal complexation studies of the extracted HA and FA were performed by equilibrium dialysis titration. The complexing capacity (CC) was highest for Cu: CC_HA = 3357 and CC_FA = 5221 μmol Cu g⁻¹ of dissolved organic carbon (DOC) at pH 5. Zn and Cd were bound (at pH 7) in smaller concentrations: CC_HA(Zn) = 2167, CC_FA(Zn) = 2809, CC_HA(Cd) = 2386, and CC_FA(Cd) = 2468 μmol metal g⁻¹ of DOC. Stability constants for binding on the strongest sites (pK_int) were determined as pK_intHA = 6.6 and pK_intFA = 7.3 for Cu at pH 5; and pK_intHA = 8.0 and pK_intFA = 6.4 for Cd at pH 7. Since these measured parameters fall within the ranges of values obtained for soil humic substances, we conclude that in soils with little organic matter, compost addition will significantly increase the amount of highly reactive organic complexing agents for trace metals in the soil.     

Control strategy for a distributed DC power system with renewable energy

This paper deals with a DC-micro-grid with renewable energy. The proposed method is composed of a gearless wind power generation system, a battery, and DC loads in a DC distribution system. The battery helps to avoid the DC over-voltages by absorbing the power of the permanent magnet synchronous generator (PMSG) during line-fault. In addition, the control schemes presented in this paper including the maximum power point tracking (MPPT) control and a pitch angle control for the gearless wind turbine generator. By means of the proposed method, high-reliable power can be supplied to the DC distribution system during the line-fault and stable power supply from the PMSG can be achieved after line-fault clearing. The effectiveness of the proposed method is examined in a MATLAB/Simulink^® environment.     

A new control methodology of wind turbine generators for frequency control of power system in isolated island

A wind turbine generator (WTG) system's output is not constant and fluctuates depending on wind conditions. Fluctuating power causes frequency deviations and adverse effects to an isolated power system when large output power from WTG systems is penetrated in the power system. This paper presents an output power control methodology of a WTG for frequency control using a load power estimator. The load power is estimated by a disturbance observer, and the output power command of the WTG is determined according to the estimated load. Besides, the WTG can also be controlled during wind turbulence since the output power command is determined by considering wind conditions. The reduction of the power system frequency deviation by using the WTG can be achieved by the proposed method. The effectiveness of the proposed method is validated by numerical simulations. Copyright © 2010 John Wiley & Sons, Ltd.     

Output power dispatch control for a wind farm in a small power system

Nowadays, a wind turbine generator (WTG) is required to provide control capabilities as the output power of WTG fluctuates. Under this scenario, this paper proposes an output power control method of a wind farm (WF) connected to a small power system using pitch angle control. In this control approach, the WF output power control is achieved by two control levels: central and local. In the central control, the WF output power command is determined by considering the frequency deviations and wind speeds using a fuzzy function. Then, the local output power commands for each of the WTGs are based on the proposed dispatch control. In the proposed dispatch control, the output commands of each WTG are determined by considering wind conditions for each of the WTGs. The simulation results by using an actual detailed model for the wind power system show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

The development of Israeli children's images of Jews and Arabs and their expression in human figure drawings.

The development of images of "a Jew" and "an Arab" in Jewish Israeli children who were 4–15 years of age was investigated by means of human figure drawings followed by the administration of questionnaires. The drawings were scored on structural and thematic variables. The questionnaires assessed beliefs and intentions. The hypotheses predicted a differential perception of in- and out-groups and peaks in negativity toward the out-group at preschool age and in early adolescence. Results indicate that, irrespective of age, Jewish Israeli children have generalized images of the two ethnic groups. Preschoolers expressed both positive biases toward the in-group and negativism toward the out-group, and early adolescents manifested mainly negative biases toward the out-group. Children in middle childhood and mid-adolescents manifested reductions in both in-group favoritism and out-group negativity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A One-Time Stegosystem and Applications to Efficient Covert Communication

We present the first information-theoretic steganographic protocol with an asymptotically optimal ratio of key length to message length that operates on arbitrary covertext distributions with constant min-entropy. Our results are also applicable to the computational setting: our stegosystem can be composed over a pseudorandom generator to send longer messages in a computationally secure fashion. In this respect our scheme offers a significant improvement in terms of the number of pseudorandom bits generated by the two parties in comparison to previous results known in the computational setting. Central to our approach for improving the overhead for general distributions is the use of combinatorial constructions that have been found to be useful in other contexts for derandomization: almost t-wise independent function families.     

Measurement of Fetal Movements by Moving-Coil Transducer

A transducer for the detection of fetal movements is described. The transducer is based on a coil moving in a magnetic field. It produces a signal as a result of fetal movements which create changes on the matemal anterior abdomen. The transducer is not affected by slow movements, maternal respiration, and uterine contractions. The sensitivity of the transducer in comparison with other means of fetal movement assessment is discussed.     

The influence of soluble organic matter from municipal solid waste compost on trace metal leaching in calcareous soils

The use of municipal solid waste (MSW) compost as fertilizer may cause increased leaching due to its high content of trace metals and thus pose a threat to groundwater quality. The effect of MSW compost application on trace metal leaching in calcareous soils has been studied in soil column experiments under laboratory conditions using three soils from the study area in the Gaza Strip and Israel. Higher levels of organic matter in solution (TOMS), nitrate, and the trace metals Cu, Ni and Zn were found in the leachates of a sandy soil and, to a lesser extent, a loamy soil, to which MSW compost had been applied at a rate of 65 Mg ha(-1) (dry weight basis). Nevertheless, the majority of water-soluble trace metal species from compost accumulated in the topsoil rather than washing out, with the exception of aqueous Ni species. Ni concentrations exceeded the maximum allowable limits for drinking water (in Germany: 50 microg l(-1)) at peak times in the leachates from sandy soil, while all other trace metals remained far below the corresponding limits. The highest absolute concentrations of trace metals were found for the leaching of Cu from compost-amended sandy soil (100 microg l(-1)). For Cd, Pb and Hg no evidence of downward movement was found in any assay. Gel filtration studies of the collected soil leachates showed that all trace metals encountered in the leachates existed mostly as organic complexes. In sandy soil most of the water-soluble organic matter added with the compost had leached from the rootzone after a year's equivalent of rainfall, while TOMS mobility was greatly reduced in the loamy soil. The makeup of the TOMS in the sandy soil and its metal-binding capacity was strongly influenced by compost-derived dissolved organic matter (DOM) as observed by FTIR spectrometry. Hence the vertical displacement of trace metals (Cu, Ni, Zn) in these calcareous soils seemed to result primarily from the presence of mobile metal-organic complexes in the soil solution after compost addition. Further studies are required to validate these findings in the field, especially to assess the risk of Cu and Ni leaching in sandy soil.     

Characterization of prolyl oligopeptidase from hyperthermophilic archaeon Thermococcus sp. NA1

The prolyl oligopeptidase TNA1_POP was found to be encoded in the genome of the hyperthermophilic archaeon Thermococcus sp. NA1 and showed high similarities to its archaeal homologs (76-83%). The enzyme was found to be a single polypeptide composed of 616 amino acids with conserved signature domains. A recombinant TNA1_POP expressed in Escherichia coli was capable of hydrolyzing succinyl-Ala-Pro-p-nitroanilide (Suc-Ala-Pro-pNA) with temperature and pH optimums of 80 degrees C and 7, respectively. TNA1_POP activity appeared to be significantly activated by pre-incubation at 80 degrees C and 90 degrees C with the optimum temperature unchanged. The heat-activated enzyme exhibited a k(cat) approximately twofold higher than that of the unheated enzyme, however, both enzymes showed the same K(m). TNA1_POP was thermostable at 80 degrees C retaining 80% of its heat-activated activity even after 23 h, but it lost its enzymatic activity at 90 degrees C with a half-life of 3 h. The loss of the enzymatic activity at 90 degrees C seemed to be caused by the autodegradation of the enzyme, not by thermal denaturation, as supported by circular dichroism spectropolarimetry. Autodegradation fragments ranging from 2 to 18 kDa were mapped by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.