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Articles 26401 - 26430 of 27312

Full-Text Articles in Engineering

Investigation On The Collagen Fiber Network In Human Dental Tissues - Transmission And Scanning Electron Microscopy, C. Marchetti, P. Menghini, C. Piacentini Jan 1992

Investigation On The Collagen Fiber Network In Human Dental Tissues - Transmission And Scanning Electron Microscopy, C. Marchetti, P. Menghini, C. Piacentini

Cells and Materials

The collagen fiber component of pulp, dentine and cementum, has been studied by isolating it from the inorganic component and the organic non-collagen matrix. This study was carried out on healthy molar and premolar adult teeth. Following demineralization all of the non-collagenous components of the tooth were removed by sequential treatment with H202, with different concentrations of trypsin and with EDTA. The transmission (TEM) and scanning (SEM) electron microscopy investigation confirmed that such a technique is an accurate method for isolating the collagen fibers while preserving their position and their ultrastructure in the dental tissue. The use of TEM and …

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Scanning Electron Microscope Observation Of Lubricious Polymer Surface For Medical Use, Hiroyuki Inoue, Yoshikimi Uyama, Emiko Uchida, Yoshito Ikada Jan 1992

Scanning Electron Microscope Observation Of Lubricious Polymer Surface For Medical Use, Hiroyuki Inoue, Yoshikimi Uyama, Emiko Uchida, Yoshito Ikada

Cells and Materials

A peculiar textured structure was found by scanning electron microscopic (SEM) observation on polymer films surface-grafted with water-soluble polyacrylamide and poly(N,N-dimethylacrylamide) after exposure to ozone. The grafted surface became very hydrophilic and highly lubricated when brought into contact with water, due to hydration of the grafted surface layer. Unless water was present, the surface did not become slippery at all. SEM of the grafted surface revealed different profiles, depending on the graft density as well as the process of drying prior to the SEM observation. There was no significant difference between the virgin and the surface-grafted film, when air-dried under …

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Interaction Of Liposomal Drug Delivery Systems With Cells And Tissues: Microscopic Studies, M. Foldvari, G. T. Faulkner, C. Mezei, M. Mezei Jan 1992

Interaction Of Liposomal Drug Delivery Systems With Cells And Tissues: Microscopic Studies, M. Foldvari, G. T. Faulkner, C. Mezei, M. Mezei

Cells and Materials

Liposomes , as drug carriers, can be administered into the body by several routes e.g. intravenously, intraperitoneally, intramuscularly, intratracheally and topically among others. Radiolabelled markers are suitable to monitor the distribution and elimination of liposomes, but the tissue deposition of intact liposomes, the mode and sites of drug release from the liposomes and liposome-cell interactions cannot be investigated morphologically. Microscopic techniques could provide information regarding the intact state of liposomes and possibly the dynamics of liposomes in tissues provided that they can be identified with certainty in vivo. This is a formidable problem and in spite of several attempts, there …

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Evaluation Of Bacterial Glycocalyx Preservation And Staining By Ruthenium Red, Ruthenium Red-Lysine And Alcian Blue For Several Methanotroph And Staphylococcal Species, Theresa A. Fassel, James E. Van Over, Christopher C. Hauser, Lorie E. Buchholz, Charles E. Edmiston, James R. Sanger, Charles C. Remsen Jan 1992

Evaluation Of Bacterial Glycocalyx Preservation And Staining By Ruthenium Red, Ruthenium Red-Lysine And Alcian Blue For Several Methanotroph And Staphylococcal Species, Theresa A. Fassel, James E. Van Over, Christopher C. Hauser, Lorie E. Buchholz, Charles E. Edmiston, James R. Sanger, Charles C. Remsen

Cells and Materials

The cationic reagents, ruthenium red (RR), alcian blue (AB) and ruthenium red -lysine were compared for ultrastructural preservation and staining of the bacterial glycocalyx. En bloc RR, AB and RR-lysine procedures, and a glutaraldehyde/OsO4 fixation withou t cationic reagent, were evaluated by transmission electron microscopy (TEM) for several methanotroph and staphylococcal species. The glutaraldehyde/OsO4 fixation was totally ineffective in preserving or staining the glycocalyx material in all species studied. The RR procedure was more effective than the glutaraldehyde/OsO4 fixation but was generally less so than the RR-lysine procedure. By the RR-lysine procedure, extensive layers that were often filamentous or fibrous …

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Stubble : Friend And Foe, Department Of Agriculture And Food, Western Australia Jan 1992

Stubble : Friend And Foe, Department Of Agriculture And Food, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

Several articles in this issue of the Journal of Agriculture discuss some of the important issues of stubble management. The articles are condensed from some of the papers presented at a stubble workshop at Geraldton in 1991.

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Stubble Handling Machinery, Greg Haydon Jan 1992

Stubble Handling Machinery, Greg Haydon

Journal of the Department of Agriculture, Western Australia, Series 4

Farming in Western Australia, and in Australia, has undergone a revolution over the past 15 to 20 years. Two significant changes have been the cessation of ploughing to kill weeds, that is, the change from discs to tines, and the reduction in tillage through the use of agricultural chemicals. These have been important changes that have had conservation benefits. However, to handle stubble to best effect, further changes in machinery, newer machinery and combinations of machines will be needed. In this article, the author discusses current and possible future practces.

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Stubble Handling Begins At Harvest, Ed Blanchard Jan 1992

Stubble Handling Begins At Harvest, Ed Blanchard

Journal of the Department of Agriculture, Western Australia, Series 4

Long stubble left in the paddock after harvest causes major difficulties at seeding time. To demonstrate the benefits of having short stubble at seeding, the Trayning Land Conservation District Committee created four stubble treatments at harvest in 1988 and sowed into these stubble treatments in 1989.

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Cost Effective Stubble Retention Practices, Andrew Green, Ed Blanchard Jan 1992

Cost Effective Stubble Retention Practices, Andrew Green, Ed Blanchard

Journal of the Department of Agriculture, Western Australia, Series 4

To increase the rate of adoption of stubble retention farming systems the Grains Research and Development Corporation is funding a three-year project with the Farm Machinery Unit to develop low cost, stubble handling systems from harvest to seeding

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Documented Aids Cases As The Basis For Projections Of Adolescence Hiv Infections In The Us, R. Ron Goforth, S. A. Goforth Jan 1992

Documented Aids Cases As The Basis For Projections Of Adolescence Hiv Infections In The Us, R. Ron Goforth, S. A. Goforth

Journal of the Arkansas Academy of Science

Twenty percent of AIDS cases in the U.S. occur in individuals in the age range 20 to 29. The mean incubation time, the time from infection to the onset of AIDS, is in the order of 8 years. Therefore, most of these AIDS cases represent HIV infections that occurred during mid- to late-adolescence. About 800 officially reported cases in the age group 13 to 19 have occurred in the U.S. This low occurrence of AIDS should not be a source of complacency in assessing the need to provide education and behavioral alternatives to this age group. As the predominate mode …

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Application Of Stable Operating Criterion To Grating Tuned Strong External Feedback Semiconductor Lasers, Haiyin Sun, Malay K. Mazumder Jan 1992

Application Of Stable Operating Criterion To Grating Tuned Strong External Feedback Semiconductor Lasers, Haiyin Sun, Malay K. Mazumder

Journal of the Arkansas Academy of Science

Stability analysis is done by applying criterion dnQ((o)/cfco>0 for grating tuned strong external feedback semiconductor lasers. The resulting stable and unstable operating ranges agree well with experiment results.

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Techniques For Efficiency Calibration Of Photon Detectors For X-Rays And Low Energy Gamma Rays, Rahul Mehta Jan 1992

Techniques For Efficiency Calibration Of Photon Detectors For X-Rays And Low Energy Gamma Rays, Rahul Mehta

Journal of the Arkansas Academy of Science

No abstract provided.

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Measurement Of The Coefficient Of Thermal Expansion Of Superconducting Thin Films Using Powder X-Ray Diffraction, Biju Chandran, R. Calvin Goforth, S. Nasrazadani Jan 1992

Measurement Of The Coefficient Of Thermal Expansion Of Superconducting Thin Films Using Powder X-Ray Diffraction, Biju Chandran, R. Calvin Goforth, S. Nasrazadani

Journal of the Arkansas Academy of Science

The High Density Electronics Center (HiDEC) at the University of Arkansas, Fayetteville is developing the technology for High Temperature Superconductor Multi-Chip Modules (HTSC-MCM's). As part of this work, we are looking at the mechanical properties of HTSC materials. An important mechanical property which influences the mechanical integrity of the hybrid MCMis the coefficient of thermal expansion (CTE) of the HTSC films. As a first step in developing a procedure for the determination of the CTE of HTSC materials, the lattice parameters and the CTE of an alpha-alumina substrate have been determined by powder x-ray diffraction technique. An extension of this …

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The Risk Of Reliance On Perceived Risk, Frank B. Cross Jan 1992

The Risk Of Reliance On Perceived Risk, Frank B. Cross

RISK: Health, Safety & Environment (1990-2002)

Professor Cross's comment is closely related to the debate between Thompson and Valverde. Using examples that do not commonly appear in the "Risk" literature, he argues that: Giving weight to perceived Risk may seem liberal insofar as it gives more say to the "little guy," but giving perceived Risk too much weight could have distinctly illiberal social consequences.

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Bs News Jan 1992

Bs News

Building Services Engineering

No abstract provided.

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Bs News Jan 1992

Bs News

Building Services Engineering

No abstract provided.

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Parking Demand And Supply In The Central Business District Of Dar Es Salaam City, Theophil Rwebangira Dec 1991

Parking Demand And Supply In The Central Business District Of Dar Es Salaam City, Theophil Rwebangira

Tanzania Journal of Engineering and Technology (TJET)

The Central Business District (CBD) Of Dar es Salaam city is currently experiencing severe congestion. Among the major causes of this condition is lack cf enough parking facilities. Obstructions due to vehicles parked on the roadway and increased vehicle circulation by drivers looking for a mace to park This paper reports on a recent study are major contributors to congestion. which evaluated the demand and supply as vell as usage of parking spaces in the CED. The f indings indicate that there is currently an acute shortage Of parking spaces, especially of off—street parking spaces. For the existing facilities, there …

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Energy From Biomass: Combustion And Gasification, G John Dec 1991

Energy From Biomass: Combustion And Gasification, G John

Tanzania Journal of Engineering and Technology (TJET)

Some fundamental facts of the combustion Of BIOMAS are outlined and di scussed . It is suggested that these provide guidelines for rhe development Of successful practical combustors. Furthemore, a realisation Of energy conversion from the same in gasfier is presented.

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Design, Operation And Maintenance Considerations Of Iiorizontal Flow Roughing Filters Preceding Slow Sand Filters, T Mbwette, Dec 1991

Design, Operation And Maintenance Considerations Of Iiorizontal Flow Roughing Filters Preceding Slow Sand Filters, T Mbwette,

Tanzania Journal of Engineering and Technology (TJET)

The paper mentions some of the reported uses of Horizontal Flow Roughing Filters (IIRF) in drinking water treatment plants in Europe before briefly reviewing research activities carried out in the use of IIRF prior to Slow Sand Filters. Design, operation and maintenance aspects Of HRF are reviewed on the basis of the laboratory and field tests carried out in Tanzania and Switzerland, respectively in addition to experience gained in operation of a number of plants already built to date. Design aspects are introduced from the point of view Of its philosophy and optimization strategies before design guidelines are given. Important …

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Flood Forecasting In Tanzanian Catchments, Omari Rumambo Dec 1991

Flood Forecasting In Tanzanian Catchments, Omari Rumambo

Tanzania Journal of Engineering and Technology (TJET)

Floods are still a problem to many countries in the world todate. Floods do cause damages to property and sometimes loss to human life. Flood control measures by structural and non—structural methods are avail able in the literature . However , structural flood control measures are financially infeasible in most developing countries today. Flood forecasting is a non—structural measure for reducing flood damages. It is a means of providing early The Li near f 1 ood warnings to flood prone areas . Perturbation Model has been appl ied for real time flood The Linear forecasting in Tan zanian catchments . …

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The Hydraulic Performance Of A Vortex Tube Foector, F Mtaro Dec 1991

The Hydraulic Performance Of A Vortex Tube Foector, F Mtaro

Tanzania Journal of Engineering and Technology (TJET)

The vorle.r tube silt exrrac/or consists of a pipe, rhe crest of which has a slit and lies flush across lhe canal bed.With minimal warer loss, I.oe bedload is extracted through lhe slil settling canal back ro the river, thus reducing or eliminating the bedload transported in main canal. Ihe resulting swirling flow phenomena is of complex nature and depends on sc conirol paramerers, as a result of which previous empirical design approaches have yielded conflicting guidelines. By means Of a simplified hydraulic system, the flow mechanism and energy in rhe can be determined.

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Absorption Of Nitrogen Oxides Into Sodium Hydroxide Solution In A Packed Column: Effect Of Gas Flowrate And Temperature, J Katima Dec 1991

Absorption Of Nitrogen Oxides Into Sodium Hydroxide Solution In A Packed Column: Effect Of Gas Flowrate And Temperature, J Katima

Tanzania Journal of Engineering and Technology (TJET)

The effect of gas flow rate and temperature on the absorption rate of nitrogen oxides (NO ) and column absorption eff iciency has been studied using a 2M goåium hydroxide (NaOH) solution in a packed The absorpt ion process was carried out at atmospheric column. pressure, with NOV concentration ranging between 150 and 10000 pp:tt, NO/N02 ratio of O and 1 iquid flow rate of O .8 1/ min. The gas flow rate was varied from 20 to 60 1/17 in and the temperature from 25 to 45 c. It was found that Ehe column absorption efficiency increases with decreasing …

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The Stability And Sate Dimensioning Of Circular Masonry Arches, A Mrema Dec 1991

The Stability And Sate Dimensioning Of Circular Masonry Arches, A Mrema

Tanzania Journal of Engineering and Technology (TJET)

An analysis of masonry arches where collapse is assumed to occur by the hinging of voussoirs upon each other is made. The behaviour of the arch material is assumed to be such that the plastic theory is valid. Certain aspects related to the properties So far the approach by of the line of thrust are clarif led. writers has been based on the conventional view that the 1 ine of It is shown that pressure is tangential to the line of thrust. this is not the case in general. Definitions are given on what is meant by "line of thrust" …

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Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima Dec 1991

Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima

Tanzania Journal of Engineering and Technology (TJET)

An experimental study was carried out on the performance of a packed column to study the absorption mechanism of nitrogen oxides (NOx). Two packed columns were set up, one with wall wiper rings to reduce wall effects and one without. Both columns were packed with stainless steel lessing rings and operated at fixed gas and liquid flow rates (40 and 8 L/min, respectively), atmospheric pressure, temperature (25°C), and sodium hydroxide concentration (8% w/w). The NOx (NO₂ and N₂O₄) equilibrium concentration and feed concentrations of up to 7000 ppm were used. The results indicated improved performance in the column with wall …

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Nitrogen Oxides Rbsorption Into Sodium Hydroxide Solution In A Packed Column Column: Effect Of Naoh Concentration, J Katima Dec 1991

Nitrogen Oxides Rbsorption Into Sodium Hydroxide Solution In A Packed Column Column: Effect Of Naoh Concentration, J Katima

Tanzania Journal of Engineering and Technology (TJET)

Experiments have been conducted to evaluate the ettect of sodium hydroxide (NaOH) concentration upon the absorption rate of nitrogen oxides (NO ) and packed column performance. The absorption process using was carried out at atmospheric pressure and 29B K, concentrations between zero and w/ w, NO/ NO ratio of 0.5 and NO concentrations between 150 and 10000 ppm in an air mixture. The performance of the calumn was enhanced by the presence of hydroxyl ions ( 0B - ) relative to the absorption into water, however, The absorption it was found to be independent of NaOH concentration. rate of NO …

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Carrying Capacity And Cracking Resistance At The Of Halving Joints In Reinforced Concrete Beams, S Mpinzire; Dec 1991

Carrying Capacity And Cracking Resistance At The Of Halving Joints In Reinforced Concrete Beams, S Mpinzire;

Tanzania Journal of Engineering and Technology (TJET)

Results are presented from tests on 3 beams having discont inuous support zones. All Of them had web and diagonal shear reinforcement. TWO out Of the three represented beams, their test results have been analysed in a paper designated part I which appeared in the Uhandisi Journal , Vol. I December 1989. They have been presented in this paper for compar ison purposes. The third beam has been made to invest i gate the effect of anchoring diagonal shear reinforcement by spot Welding method. The third beam was tested With two concentrated loads in the span. In all beams several …

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A Finite Element Analysis Of Wood In Transverse Compression, A Mrema Dec 1991

A Finite Element Analysis Of Wood In Transverse Compression, A Mrema

Tanzania Journal of Engineering and Technology (TJET)

A two dimensional finite element analysis is utilized to predict the stress and strain distributions for wood in transverse compression. Important key var iables are incorporated into the ana lysis to define their influence on the stress and strain distributions. These variables are geometry of loading, geometry of specimen and the orthotropic ratio of the material. Based on the finite element analysis results, relationships are arising stress from developed relat ing maximum stress concentrations to the above three variables. possible appl ications of the results from this study relate to the development of more efficient design of connections such as …

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Comparative Study Of Inlet Manifold Tuning To Enhance Supercharge, Mtui L Dec 1991

Comparative Study Of Inlet Manifold Tuning To Enhance Supercharge, Mtui L

Tanzania Journal of Engineering and Technology (TJET)

Computer model ing and experimental results on a single cylinder, four-stroke cycle engine for best air flow characteristic is The modeling analysis is based on hornet ropie fluid di scussed . The model n g resul s is flow w it. h constant: specific heats. included to val idat.e the s imulation program against experimental results with widely vary ing manifold lengths and engine speeds. ExperimenLal results are obtained by measuring air f low rates Lo the inlet valve during steady g Late speed Of Lhe engine. Manifold tuned lengths are Obtained for a range Of speeds by exper and …

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Experimental Investigations On The Behaviour Of Wood In Transverse Compression, A Mrema Dec 1991

Experimental Investigations On The Behaviour Of Wood In Transverse Compression, A Mrema

Tanzania Journal of Engineering and Technology (TJET)

Experimental investigations were done to study the behaviour of wood in transverse compress ion. Three key variables were incorporated in the experiments to study their influence on the •nriables were the orthotropic ratio of the behav iour. These material, the geometry of loading and that of the specimen . Deformation measurements were made at selected locations on test specimens by means of strain—gage based clip gages. Results from the experimental measurements were compared to previous deformation predictions made by a finite element analysis (9) . There is a very good agreement between measured values and those obtained trom the finite …

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Density Measurement For Corrosive Solutions At Elevated Temperatures, Kimweri, H Dec 1991

Density Measurement For Corrosive Solutions At Elevated Temperatures, Kimweri, H

Tanzania Journal of Engineering and Technology (TJET)

In this work, apparatus for measuring densities of corrosive solutions at high temperatures was developed and used. Densities of dilute aqueous sulphuric acid solutions, containing different amounts of zinc and iron salts were measured at temperatures up to 185°C. In view of the good agreement between consecutive measurements for each solution and the density of water obtained by using this apparatus with that given in literature, for all experiments, the apparatus is recommended to be used for measuring densities of corrosive solutions at high temperatures.

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Electrical Equivalent Method For The Calculation Of Vibrations In Transformers, D Chambega Dec 1991

Electrical Equivalent Method For The Calculation Of Vibrations In Transformers, D Chambega

Tanzania Journal of Engineering and Technology (TJET)

Noiselevel calculations may be done using an electrical equivalent method. So far a single mass and a double mass vibrating system may easily be represented by equivalent electrical circuits which are in turn useful for analysis. Multimass vibrating systems like transformers do not have straightforward methods which can enable analysis of noiselevels. This paper attempts to develop such a method by extending the method applicable to a double mass vibrating system. Then the validity of the method is tested using a transforme

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