Mobilization and Leaching of Natural and Water Dispersible Colloids in Aggregated Volcanic Ash Soil Columns

Colloid-facilitated transport enhances migration of strongly sorbing compounds (e.g., radionuclides, phosphorus, heavy metals) in soil and groundwater. Mobilization, transport and deposition of soil colloids are the underlying processes governing colloid-facilitated contaminant transport. Although significant progress has been made in simulating mobilization and transport/deposition of model colloids in different collector systems, it may be inadequate for the prediction of natural colloidal behavior in the subsurface. This study quantifies the leaching of natural volcanic ash soil colloids (NC) as well as the simultaneous transport of applied water dispersible soil colloids (WDC) in aggregated volcanic ash soil columns. Two water-saturated soil columns were irrigated with artificial irrigation water (AIW) at an intensity of 80 mm/hr for 60 hours. Two additional columns were irrigated at the same intensity, but a colloidal suspension of 5 mg/L was applied after 20 hours for a period of 20 hours. Effluent colloid concentrations were measured in each experiment. HYDRUS-1D was used for the simulation and estimation of colloid transport parameters. The results clearly showed different kinetics for applied colloid transport and natural colloid leaching. Transport of applied WDC followed first-order attachment kinetics, while the two-site equilibrium/kinetic model with equal fractions of equilibrium and kinetic sites best described the leaching of NC. Coupling these best model approaches well predicted the simultaneous leaching of natural and applied colloids, hereby providing a useful tool for the design of colloid-based in-situ soil remediation systems.     

Gas Transport Parameters for Compacted Reddish-Brown Soil in Sri Lankan Landfill Final Cover

Gas exchange through the compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill gases. This study involved measuring the soil-gas diffusivity (Dp/Do, the ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60–1.94??g?cm-3. Existing and modified models for predicting Dp/Do and ka were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soil-water retention (SWR) dependent model. The measured ka values for differently compacted samples were highly affected by the compaction level and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type ka model was most accurate in predicting ka in the differently compacted soil samples. Equivalent air-filled pore diameters (the effective diameter of the drained pores active in leading air through the sample) for gas flow, deq, were calculated from the measured Dp/D0 and ka values. The deq increased with compaction level, suggesting that a very high compaction level creates well-connected macropores in the reduced total pore space of the cover soil. This is an important consideration when designing cover soils for optimally low water and high oxygen exchange while minimizing climate and toxic gas emissions from the waste layer to the atmosphere.     

Purification and characterization of sea squirt alpha-N-acetylgalactosaminidase

Sea squirt alpha-N-acetylgalactosaminidase was purified to homogeneity. Its molecular weight was estimated to be approximately 160,000 by gel filtration and 40,000 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing condition. The chromatographic and electrophoretic behaviors indicated that the enzyme was composed of four subunits. The optimum pH of the enzyme reaction was about 4.0 at 37 degrees C, while the enzyme was stable in the range of pH 5.0 to 6.0 during 4 h preincubation at 37 degrees C. Although the enzyme (0.1 unit) was stable at 0 degrees C for 30 min in the presence of 7.5 mM metal ions (Al3+, Ba2+, Ca2+, K+, Mn2+, Pb2+, Sr2+, and Zn2+), almost 40% of the enzyme activity was lost in the presence of Cu2+, Hg2+, monoiodoacetic acid, and EDTA. The enzyme hydrolyzed aryl N-acetyl-alpha-D-galactosaminide as well as GalNAcalpha1(-->4GalNAcalpha1-->)n 4GalNAc-p-aminobenzoic acid ethyl ester (ABEE) (n = 1-4), but GalNAcalpha1-->4GalNAc-ABEE only scarcely. Furthermore, an allergenic pentasaccharitol ABEE derivative, GalNAcalpha1-->2Fucalpha1-->3(GalNAcbeta1-->4) GlcNAcbeta1-->2(3-acetoamido-3-deoxy)L-threose-ABEE, the minimum structural unit for the sea squirt allergenicity was hydrolyzed to 95 mol% for 72 h incubation with the enzyme. The enzyme could be utilized as a powerful tool for the structural analyses of the carbohydrate epitopes of the sea squirt allergen molecules.     

Allelic diversity in the merozoite surface protein-1 and epidemiology of multiple-clone Plasmodium falciparum infections in northern Tanzania

Allelic diversity in the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum, a major malaria vaccine candidate, was examined in clinical isolates from holoendemic northern Tanzania. The variable blocks 2, 4a, 4b, 6, and 10 of the MSP-1 gene were typed by allelic type-specific polymerase chain reaction. Twenty-four possible MSP-1 gene types were defined as unique combinations of allelic types detected in each variable block. Thirteen gene types were identified, and 187 P. falciparum populations were fully typed among 79 isolates. In contrast with recent findings in Vietnam, we were unable to detect nonrandom associations between allelic types in the typed variable blocks. Most patients (60%) harbored more than 1 genetically distinct parasite population (average: 2.37 populations per isolate) and, in 1 patient, 6 different versions of this single-copy gene were found. Statistical analysis suggests that parasites carrying different MSP-1 gene types are not independently distributed in the host population. The epidemiological consequences of these findings are discussed.     

A Study on Predicting Hazard Factors for Safe Driving

This paper proposes an algorithm for detecting objects representing potential hazards to drivers based on the combination of local information derived from optical flows and global information obtained from the host vehicle's status. The algorithm uses artificial neural networks to infer the degree of danger posed by moving objects in dynamic images taken with a vehicle-mounted camera. This approach allows more flexible adaptation of the algorithm to many drivers with dissimilar characteristics. Experiments were conducted with both miniature vehicles in a virtual environment and real vehicles in a real driving situation using video images of multiple moving objects. The results show that the algorithm can infer hazardous situations similar to the judgments made by human drivers. The proposed algorithm provides the foundation for constructing a practical driving assistance system     

A fully depleted lean-channel transistor (DELTA)-a novel verticalultrathin SOI MOSFET

A fully depleted lean-channel transistor (DELTA) that has a gate with a vertical ultrathin SOI structure is reported. In the deep submicrometer region, selective oxidation is useful in realizing SOI isolation. It provides high crystalline quality, as good as that of conventional bulk single-crystal devices. Using experiments and three-dimensional simulation, it was shown that the gate structure has effective channel controllability and its vertical ultrathin SOI structure provides superior device characteristics     

Abnormality of electric field at a wedgelike edge of a conductor or a dielectric interface and methods for its relaxation

Abnormal electric field appears at a wedgelike edge of a conductor (electrode) or a dielectric interface, which usually becomes infinitely high. This paper analyzes the electric field near such an edge by the analytical variable separation method and by the numerical one of the charge simulation method. The analysis focuses on the special conditions where the electric field becomes zero at an edge. These conditions are important for the insulation design to suppress the discharge inception at such edges of conductors and dielectric interfaces. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 1–8, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20280     

Triple‐junction effect and its electric field relaxation in three dielectrics

This paper analyzes the electric field distribution near a wedge‐like edge in arrangements consisting of three dielectrics using analytical and numerical methods. The electric potential behaves exponentially as rⁿ (r is the distance from the edge) near the edge, leading to an infinitely high field with decreasing r for all cases. The value of the analytically derived exponent n agreed well with that obtained from the numerical field calculations. It has also been demonstrated that rounded contact of the spacer with a zero contact angle can make the electric field constant without showing an exponential rise near the edge. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 1– 8, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20670     

Urgent coronary artery bypass surgery by only arterial graft for acute myocardial infarction

The authors conducted urgent coronary artery bypass grafting (CABG) using only arterial graft for mild and moderate acute myocardial infarction (AMI) in 9 cases from January, 1995 through December, 1996. Mild and moderate AMI means free from cardiogenic shock by catecholamines alone or catecholamines and intra aortic balloon pumping (IABP). The period from the onset of AMI to admission was 2-24 (average 8 +/- 6) hours. Coronary arteriography (CAG) was performed immediately following admission. CABG was done immediately after CAG. CPK-MB on admission was 14-184 (average 67 +/- 61) IU/l. Three cases were main trunk disease over 90% stenosis, three cases were main trunk disease equivalent if another stenotic lesion over 99% were occluded, three cases would fall into cardiogenic shock if another stenotic lesion over 99% were occluded. Postoperative IABP was necessary for three cases. No case required repetition of IABP. For minimal operation time and to attain high graft flow, saphenous vein (SV) graft are generally used for emergencies. CABG was conducted here using only arterial graft (Mean anastomosis number was 2.3). There were 8 RITA grafts, 9 LITA grafts, and 4 RGEA grafts. Post operative CAG showed all the grafts to be patent, but string sign was noted for two LITA grafts. Prognosis was favorable in all cases. We could conduct urgent CABG surgery safely for mild and moderate AMI using only arterial grafts.