Laboratory Simulation Studies Research Articles

地下水中の好・嫌気性菌によるSUS304LおよびSUS316L鋼溶接部の微生物誘起腐食(第二報)

Microbiologically influenced corrosion was suspected in a corrosion failure of stainless steel (SUS316L) piping, carrying saline groundwater. Laboratory simulation studies were planned to find out the mechanism of the corrosion. Culturing of bacteria strains in the ground water revealed 7different species. Six of them were aerobic and one of them was anaerobic microbe that is Sulfate Reducing Bacteria (Desulfovibrio sp.). They were incubated separately in liquid medium and exposure studies were conducted. Formation of biofilm on SUS316L coupons was observed when they were exposed to the test solution with Comamonas sp., Sphingomonas sp., Agrobacterium sp., and Desulfovibrio sp. Pitting corrosion sites were observed on SUS316L coupons exposed in Desulfovibrio sp. inoculated solution. Corrosion potential of SUS316L coupons became noble when they exposed to the solution with Nutrient broth (NB). When SUS316L coupons exposed to the solution without NB and the sterile solution, the increasing of corrosion potential was not seen. The corrosion potential decreased when exposed to the aerobic microbes inoculated solution. However, in case of Desulfovibrio sp. inoculated solution, it stagnated in early stages, and increased after that. It was thought from the above result that Desulfovibrio sp. with aerobic microbes that are able to formed biofilm could influence this MIC.

A quantitative review of the guilty knowledge test.

The guilty knowledge polygraph test (GKT; D. T. Lykken, 1959, 1960) is a psychophysiological method of identifying suspects with concealed information about a crime. A meta-analysis of 50 treatment groups drawn from 22 laboratory simulation studies (total N = 1,247) was conducted to provide a comprehensive estimate of GKT accuracy under controlled conditions. Electrodermal measures correctly identified 76% of participants with concealed knowledge and 83% of those without information. Informed participants were detected at rates significantly in excess of chance, with a mean weighted effect size of .57. Enactment of mock crimes increased the hit rate to 82%. The rates of false-positive error among noninformed treatment groups did not significantly exceed chance. Applications and research directions are discussed.

DYNAMIC DEPOSITION PATTERN SIMULATION OF MODULATED SPRAYING

A modulated spraying nozzle control (MSNC) system can be used to adjust chemical application rates without changing droplet size or the spray pattern across the boom. This laboratory simulation study was conducted to determine the spray pattern of an MSNC system along the sprayer travel direction under different travel speeds. A discrete accumulate method was developed to determine both the spatial and temporal spray pattern for the entire spraying area. Both DG8004VS and DG11004VS flat fan nozzles were tested under four different application rates (25%, 50%, 75%, and 100%) with a travel speed range of 4 to 16 km/h. The 2D spatial spray patterns were generated to demonstrate the MSNC system spraying performance. The coefficient of variation (CV) of spray deposition was measured along the direction of travel. The results show that the MSNC system is suitable for current ground speed compensation rate control applications. If wide fan angle nozzles are used, the CV along the travel direction could be lower than that across the boom.

Study of edge effects in the breakdown process of p + on n-bulk silicon diodes

The paper describes the role of the n + edge implants in the breakdown process of p + on n-bulk silicon diodes. Laboratory measurements and simulation studies are presented on a series of test structures aimed at an optimization of the design in the edge region. The dependence of the breakdown voltage on the geometrical parameters of the devices is discussed in detail. Design rules are extracted for the use of n +-layers along the scribe line to avoid surface conduction of current generated by the exposed edges. The effect of neutron irradiation has been studied up to a fluence of 1.8×10 15 cm −2.

Experimental laboratory simulation of Titan’s atmosphere: aerosols and gas phase

The discovery that Titan, the largest satellite of Saturn, has an atmosphere and that methane is a significant constituent of it, was the starting point for a systematic study of Titan’s atmospheric organic chemistry. Since then, the results from numerous ground-based observations and two flybys of Titan, by Voyager I and II, have led to experimental laboratory simulation studies and photochemical and physical modeling. All these works have provided a more detailed picture of Titan. We report here a continuation of such a study performing an experimental laboratory simulation of Titan’s atmospheric chemistry, and considering the two physical phases involved: gases and aerosols. Concerning the gaseous phase, we report the first detection of C 4N 2 and we propose possible atmospheric abundances for 70 organic compounds on Titan’s upper atmosphere. Concerning the solid phase, we have characterized aerosol analogues synthesized in conditions close to those of Titan’s environment, using elemental analysis, pyrolysis, solubility studies and infrared spectroscopy.

The effects of fire on rock weathering: some further considerations of laboratory experimental simulation

Fire in the natural environment is a widespread agent of geomorphological and biological change. Temperatures can exceed 1000°C. There is often a rapid rise from ambient conditions through a steep thermal gradient, promoting rock disintegration. Laboratory simulation studies have established that temperature changes which are representative of natural fires affect rock material properties, which can then be related to weathering susceptibility. This study extends previous work by more closely replicating the natural environment, (a) through the simulation of rainfall and (b) by encasing samples to reflect the exposure of a single rock face to a passing fire event. Rock samples collected on Cyprus were prepared and tested following previously reported procedures. Change in modulus of elasticity was monitored using a non-destructive ultrasonic method. The data corroborate previous work but with somewhat different degrees of change. The new results are more likely to be representative of natural conditions and real-world change. The rate of rock disintegration and effects such as case-hardening appear to be a function of rock thermal characteristics, material properties and environmental constraints such as diurnal temperature range. Copyright © 1999 John Wiley & Sons, Ltd.

The Impact of Gas Injection On the Oil Recovery of a Giant Naturally Fractured Carbonate Reservoir

Abstract This paper presents the results and discusses the impact of a long-term gas cap injection project in an Iranian carbonate oil reservoir. The reservoir is naturally fractured and is located in the south west of Iran. Its estimated oil in place is 7.15 m3 × 109 (45 billion STB), making it a world giant. Laboratory and production simulation studies that were conducted prior to implementation of the gas injection project considered the uncertain effects of natural fractures on behaviour of fluids in porous media. These studies indicated that long-term reservoir pressure maintenance by gas cap injection might improve the ultimate oil recovery of the reservoir considerably. After 15 years of gas cap injection, field data combined with predicted data under natural depletion (solution gas drive, gas cap drive and gravity drainage combined) have shown that pressure maintenance would ultimately increase the recovery of oil by nearly 318 MMm3 (two billion barrels) (16% over primary recovery), but much less than predicted from the original study. A brief economic assessment also indicated that the project, besides being effective in increasing the ultimate recovery of oil in the reservoir, is commercially viable. Introduction Limestone and dolomite reservoirs constitute one of the largest sources of crude oil supply in the world. Approximately 65% of the present world production comes from carbonate reservoirs mostly located in the Middle East, Mexico, and Canada. The pore structure in these reservoirs is characterized by a wide variation in the shape and the distribution of pore sizes. These widely varying characteristics of carbonate formations, together with the frequent presence of fractures, have made the porous media so complex that the application of general analytical techniques, normally used to delineate its performance to understand the recovery processes and to predict the results of operating practices for enhancing the recovery, becomes extremely difficult(1,2). Although fractured reservoirs are scattered throughout the world, one of the highest concentration of reserves of this type is in the southwest of Iran and northeast of Iraq. The oil-in-place in the Middle Eastern fractured reservoirs represents 25 – 30% of the total oil in place in that area. This percentage may also be representative on a worldwide scale(3). Gas cap injection as a means of increasing oil recovery on a long-term basis has been applied during the last 50 years. It is stated that it improves the oil recovery through maintaining the reservoir pressure, displacing oil and/or vapourizing the intermediate fractions of the reservoir fluid(4,5,6,7). As gas cap injection for enhancing oil recovery has been applied mainly to sandstone reservoirs, a comprehensive study to investigate its potential in fractured carbonate reservoirs was launched on a laboratory scale(8). In 1975, after this intensive research program, gas cap injection was chosen as a possible technique for improving the oil recovery in Iranian naturally fractured oil reservoirs. The mechanism involved in enhancing the gravity drainage process in the gas invaded zone consists of lowering the gas-oil contact level, maintaining the oil pressure and allowing the gas cap pressure to rise to its original level.

The effect of eye closure on protein and complement deposition on Group IV hydrogel contact lenses: relationship to tear flow dynamics.

This study was designed to determine the effect of overnight eye closure on the rate and composition of protein deposition on high water content ionic matrix soft contact lenses (Group IV SCLs) and to extrapolate from this data information on the probable change in the rate of reflex-type tear secretion associated with eye closure. Group IV SCLs were temporally sampled after equivalent periods of wear under closed eye (C) or open eye (O) conditions. Lenses were rinsed in saline and the majority of the tightly bound protein extracted at 90 degrees C in 40% urea, containing 1% SDS, 1 mM DTT, 100 mM Tris-HCl (pH 8.00). Residual protein was determined by Coomassie staining of the extracted lenses and densitometric analysis. Extracted protein was quantitated and separated by SDS-PAGE. Gels were either stained with Coomassie blue or reversibly stained with imidazole-zinc and blotted. Blots were PAS stained, or lectin and antibody probed for glycoproteins, secretory IgA (sIgA), IgG, lysozyme and complement C3. Laboratory simulated deposition studies were carried out on unworn lenses exposed to HPLC purified lysozyme. The protein in the saline rinse, to a large degree mirrored the composition of tear fluid in which the lens had been residing (O or C). This would suggest that the saline wash consists of residual tear fluid and loosely adherent protein. In contrast, the urea extracts were highly homogeneous consisting primarily of lysozyme and to lesser extent lysozyme dimer. This supports the contention that the Group IV SCL functions in the eye much as cationic exchange resin selectively absorbing lysozyme. C extracts also proved relatively enriched in trace amounts of sIgA, IgG and complement C3 and its breakdown products. High levels of C3 and C3 breakdown products were specifically recovered only in the C worn lens extracts from a subject experiencing unilateral contact lens associated corneal infiltrates from the affected eye. In all subjects, markedly less protein (lysozyme) was recovered in urea extracts of lenses exposed to 7-8 h of closed eye as compared to open eye wear (0.20 +/- .08 versus 0.79 +/- .15 mg/lens (n = 6)). Temporal studies further revealed that deposition was linearly related to duration of wear during the initial phase of conditioning film formation giving rise to rate constants for lysozyme deposition of 2.2 +/- 0.29 (n = 5) and 0.20 +/- 0.06 microgram/min (n = 4) under open and closed eye conditions respectively. With further wear, deposition eventually reached a steady state. Under laboratory conditions, lysozyme was much rapidly and quantitatively removed from solution in a manner following a hyperbolic plot. This suggests that during the initial phase of deposition the rate of deposition is limited by the capacity of the tear fluid to deliver lysozyme to the lens surface under these two extremes of conditions. Eye closure profoundly affects the rate of lysozyme deposition on Group IV hydrogels and the composition of minor biofilm constituents in a manner that could affect biocompatibility. Findings support the contention that eye closure results in a > 90% reduction in the rate of reflex-type tear secretion.

On the mechanisms of dioxin formation in combustion processes

Abstract The experimental observations on dioxin formation from various combustion sources, from detailed incinerator measurements and from laboratory simulation studies including de novo synthesis and precursor formation pathways are discussed in this paper. The de novo synthesis seems to be the dominant mechanism of dioxin formation in actual combustion systems. As de novo synthesis experiments indicate that carbon morphology of certain degenerated graphitic structure is essential for dioxin formation, the morphologies of the particulate emissions from actual combustion sources are examined and it appears that soot particles formed in gas phase combustion reactions consisting of degenerated graphitic structures are the plausible source for de novo synthesis of dioxins. With this understanding dioxin formation in combustion systems is described as a two-stage process: (1) the formation of the graphitic structure of soot particles in the combustion zone; and (2) the conversion of the graphitic structure of soot particles to aromatic compounds including PCDD/Fs in the postcombustion zone. New explanations are given for some seemingly unrelated experimental observations including the high dioxin emissions from municipal waste incineration, the low dioxin emissions from coal combustion, the similar dioxin “fingerprint” from all combustion sources and the discrepancy between the dioxin formation rates observed in laboratory experiments and incinerator measurements.

On the relation of soil erosion to rainfall erosivity in southeastern Nigeria

Abstract Concern over soil improvishment and water quality problems associated with runoff and erosion from agricultural lands led to a combination of laboratory simulation and field study aimed at further understanding rainfall‐runoff‐soil loss relationships and also to improve the methods of predicting sediment loss and escape of pollutants during rainfall‐runoff events. The paper presents a relation for assesing erosivity from rainfall characteristics especially in conditions with limited facilities for rainfall intensity monitoring. Regression analysis show that soil loss can be predicted from rainfall intensity using exponential function. Some improvement in correlation between soil loss and daily rainfall depth, P was achieved with the erosivity equation: EImin = (3.64 × 10−3logP − 6.3 × 10−5)P2 This relation offers a simple, straightforward and reliable method of predicting soil loss when only daily rainfall data is available. In the study area, the contribution of rainfall to runoff on sandy loam ...

Estimation of detergent influx and impact assessment in freshwaters

An equation is derived which rigorously defines the partitioning of inorganic carbon flux into alkali addition, calcium precipitation, production and respiration in fresh waters, polluted by the influx of detergents. The model has been extended to account for the modulation of oxygen concentration due to the oxygen demand of detergents (ODD). The equation is applied to two such polluted systems receiving detergent influx in the range of 50–285 g m−3 (as calcium carbonate equivalent). The flux in the various parameters has been compared with unpolluted systems and with laboratory simulation studies, to assess the impact of detergents. Given certain assumptions, the influx can be visualized in the form of an environmental stress, reducing productivity. The degree of reduction varies with the loading of the system.

A summary of sulfur dioxide emission rate measuremnts from Guatemalan volcanoes

Measurements of the sulfur dioxide (SO2) emission rate from three Guatemalan volcanoes provide data which are consistent with theoretical and laboratory studies of eruptive and shallow magma chamber processes. In particular, unerupted magma makes a major contribution to the measured SO2 emission rates at Santiaguito, a continuously erupting dacitic volcanic dome. Varying shallow magma convection rates can explain the variations in SO2 emission rates at Santiaguito. At Fuego, a basaltic volcano currently in repose, SO2 emission rate measurements are consistent with a high level magma body that is crystallizing and releasing volatiles. At Pacaya, a continuously erupting basaltic volcano, recent SO2 emission rate measurements support laboratory simulation studies of strombolian eruptions; these studies indicate that the majority of gas escapes during eruptions and little gas escapes between eruptions. Average SO2 emission rates over the last 20 years for Santiaguito, Fuego and Pacaya are 80, 160 and 260 Mg/d, respectively. On a global scale, these three volcanoes account for 1% of the annual global volcanic output of SO2. Santiaguito and Pacaya, together, emit 6% of the total annual SO2 emitted by continuously erupting volcanoes. Even though SO2 measurements at these volcanoes have been made infrequently and by different investigators, the collective data help to establish a useful baseline by which to judge future changes. A more complete record of SO2 emission rates from these volcanoes could lead to a better understanding of their eruption mechanisms and reduce the impact of their future eruptions on Guatemalan society.

Outbreak of pyogenic abscesses after diphtheria and tetanus toxoids and pertussis vaccination.

Nine children who received diphtheria and tetanus toxoids and pertussis vaccine from the same vial at a clinic in Colorado developed pyogenic abscesses at the site of injection. Eight abscesses required surgical drainage and five children were hospitalized. Group A Streptococcus (GAS) was cultured from eight wounds and Staphylococcus aureus was also isolated from four. Epidemiologic investigation revealed that within the hour of the first child's vaccination, three children had been diagnosed in the clinic with GAS pharyngitis. GAS recovered from repeat throat swabs from two of these children and the eight case-isolates were all serotype M-12, T-12 and had identical immunoblot patterns on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Laboratory simulation studies demonstrated that GAS can survive for at least 4 days on the external surface of a vaccine vial rubber stopper and contaminate needles inserted through the stopper. Swabbing the stopper with 70% isopropyl alcohol resulted in effective disinfection. To prevent potential contamination meticulous attention to sterile technique is important when withdrawing vaccine from multidose vaccine vials.

Austempering of sintered low alloy steels: M. Kamada et al, (Kyushu Univ, Fukuoka, Japan). Int J Powder Metallurgy, Vol 27, No 3, 1991, 255–263

Austempering heat treatment practice helps in achieving high strength with good ductility and toughness by evolving a predominantly bainitic microstructure in the steel. Further, austempering practice can be modified to facilitate formation of some amount of ferrite and pearlite along with bainite which in turn enhances the ductility with some lowering of strength in the steel. The actual strength and ductility depends upon the relative amount of ferrite, pearlite and bainite present in the austempered steel. Present study was taken up to understand the influence of austempering parameters like austenitising temperature and cooling rate on the microstructure of an austempered steel with 0.4% carbon and 1.4% manganese. Laboratory simulation studies on conventional austempering showed that a microstructure comprising predominantly bainite with up to 4% ferrite was evolved which imparted a tensile strength of 120 kg/mm2 and elongation of 4% (at 150 mm gauge length) to the austempered steel. On the other hand, when the steel was subjected to modified austempering practice which included austenitising at different temperatures for a period of 2 min followed by controlled air cooling and quenching in a lead bath at 450 °C, variety of microstructures were obtained. Particularly, when the steel was austenitised at 870–900 °C, a microstructure comprising uniformly distributed fine pearlite and bainite in a matrix of ferrite was formed. This microstructure resulted in tensile strength of 95 kg/mm2 and elongation of 9% (at 150 mm gauge length). Based on the results achieved in this study, a relationship was established between tensile properties and the volume fraction of ferrite formed during austempering of steel.

Carbon deposition in the gaps between tiles: Data from the Tokamak Fusion Test Reactor and laboratory simulation studies

The bumper limiter in the Tokamak Fusion Test Reactor (TFTR) is lined with graphite tiles. Between the tiles are gaps of width ∼3 mm. Interaction of the hydrogen plasma with the graphite tiles is known to lead to the deposition of hydrogen-rich carbon layers on low-flux regions of the tiles. When these tiles were disassembled for examination, thick carbon deposits were found to penetrate ∼2 cm down the side faces of the gaps. These deposits were several microns thick, at a depth ∼5 mm below the plasma-facing surface. Experiments were performed in the plasma simulator Laser-Material-Plasma Experiment (LAMPE) to study the mechanism of carbon deposition in narrow gaps. In conjunction with calculations using the neutral transport code DEGAS, the results show that sputtered carbon can be transported deep down the gap by multiple reflections off the faces of the gap. This understanding should be taken into account in the design of tiles for future fusion reactors to minimize codeposition buildup in these nearly inaccessible regions.

PCB transport into lake sediments. Conceptual model and laboratory simulation

A laboratory simulation study was performed to observe the transport of a polychlorinated biphenyl (PCB) in lake bottom sediment. A conceptual mathematical model, which describes PCB fate due to the combination of molecular diffusion in pore water and partitioning onto sediment solids, was assessed. An experimental apparatus was designed to simulate a lake bottom sediment/water interface condition, in which Aroclor 1242 was introduced. Sampling and analytical methods were devised, so that bed depth-PCB concentration profiles could be determined from the simulation. Very thin slices, 0.02-0.1 cm, allowed the construction of concentration profiles to quantify the time variation of penetration of {sup 14}C-labeled components into bottom sediment. The consistent behavior of effective diffusivities extracted from profiles suggests the model may adequately describe chemical transport in sediment.

Design of a Tertiary Hydrocarbon Miscible Flood for the Mitsue Reservoir

A large-scale hydrocarbon miscible flood has been designed and is being conducted in the Mitsue Gilwood Sand Unit No. 1 in Alberta, Canada. The horizontal miscible flood occurs mostly in previously waterflooded zones and is a true test of the tertiary displacement mechanism. An area of 17,900 acres (7250 ha) is being flooded with a first-contact-miscible (FCM) hydrocarbon solvent followed by a lean chase, gas, both alternated with equal volumes of water. Inverted five-spot injection patterns are used. This paper reviews the evaluation and design process by use of recently developed methodologies, involving innovative laboratory techniques and simulation processes used in planning the miscible flood. Laboratory work was used to develop correlations for determining the hydrocarbon solvent enrichment required for both FCM and multiple-contact miscibility (MCM) as a function of solvent C/sub 2+/ fraction and molecular weight at the reservoir pressure of 2,500 psia (17.2 MPa). Simulation studies indicate that optimum solvent and chase-gas slug sizes of 15 and 25%, respectively, will yield an incremental 12.2% of original oil in place (OOIP), or 21.3 MMSTB (3.4 x 10/sup 6/ stock-tank m/sup 3/). Solvent and chase-gas recoveries were estimated to be 73 and 44%, respectively. Early performance of the miscible floodmore » indicates that the solvent is successfully mobilizing tertiary oil. Wells previously shut in because of high water production have experienced an increase in oil rates and a decrease in WOR's.« less

Simulated diagenesis and catagenesis of marine kerogen precursors: Melanoidins as model systems for light hydrocarbon generation

Amino acids and sugars are principal constituents of marine organisms. The condensation of amino acids and sugars is one possible nonenzymatic, early diagenetic pathway for the incorporation of these compounds into more complex geopolymers. In this study, aqueous solutions consisting of l-lysine, l-histidine, l-arginine and d-(+)-glucose were heated (100°C) for up to 288 h. Portions of the melanoidin polymer isolated after heating were reheated in the presence of water (hydrous pyrolysis) for 72 h at 325°C. Reaction products were identified by GC and GC/MS. Stable isotopic ( δ 13C) and elemental analyses were used to follow thermal evolution. While the initial melanoidin was synthesized from a simple, four component system, the products generated during hydrous pyrolysis are of considerable complexity, and include straightchain and branched alkanes, alkadienes, alkynes, indole, dimethyl indane, ethyl phenol, quinoline, and xylenes, in addition to a multitude of as yet, unidentified components. Stable carbon isotopic values for the reactants and products correspond to trends observed for naturally generated geopolymers and light gases. Elemental analyses of the melanoidin prior and subsequent to hydrous pyrolysis indicate a kerogen evolution pathway similar to that observed for natural samples. Considering the intractable nature of kerogen, laboratory simulation studies of simple systems can provide an alternative approach for elucidating the origins of geopolymers and their potential for hydrocarbon generation.

Driver's decision process on termination of the green light

The paper describes the background and evaluates the effectiveness of a flashing green phase just before the amber leading to red phase in the traffic signal cycle. This type of signal sequence, practiced in Israel and a few other countries, was thought to provide drivers with useful information which should lead to better stop or go decisions. However, accident analysis studies have shown an increase in collisions following the introduction of a flashing green. A laboratory simulation study designed to explain the accident findings was conducted. It was found that the flashing green elicited from the drivers an earlier decision response and a higher number of inappropriate stopping decisions, particularly close to the intersection. The pattern of stopping and crossing decisions in the flashing green program suggests more friction between stopping and nonstopping vehicles and, therefore, a higher likelihood of front-rear collisions compared to a regular program.

Improved conspicuity to the sides and rear of motorcycles and mopeds

This research utilized accident data analysis, expert opinion, a controlled laboratory simulation study and an observational field study to determine whether practical and feasible vehicle-mounted side and rear conspicuity aids could be developed for motorcycles and mopeds. Significant differences between various side and rear conspicuity-enhancing treatments were found in the laboratory study that simulated their appearance in day and night, urban and rural conditions. Although the observational field study did not indicate significant driver behavioral differences in response to each treatment, a trend suggesting that a twin or triple taillamp improved rear conspicuity and that reflectorization improved side conspicuity was noted.