Magnetite in soils: I. The synthesis of single-domain and superparamagnetic magnetite

AbstractA series of experiments has been carried out to investigate the possible formation of magnetite, Fe3O4, under ambient soil-forming conditions. Rapid and easy synthesis of magnetite was achieved through controlled oxidation of Fe2+ solutions at room temperatures and near neutral pH values. The synthetic products were found to range in size between 0·01–0·07 µm (mean diameter) and hence span the theoretical superparamagnetic-single-domain grain-size boundary.

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Slip traces caused by plastic deformation during recrystallization of thin metal sheets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170839 ◽

1994 ◽

Vol 52 ◽

pp. 620-621

Author(s):

H. Lin ◽

D. P. Pope

Keyword(s):

Grain Size ◽

Grain Boundaries ◽

Sample Thickness ◽

List Type ◽

Metal Sheets ◽

Second Phases ◽

Slip Traces ◽

Series Of Experiments ◽

Cold Rolled ◽

Individual Grains

During a study of mechanical properties of recrystallized B-free Ni3Al single crystals, regularly spaced parallel traces within individual grains were discovered on the surfaces of thin recrystallized sheets, see Fig. 1. They appeared to be slip traces, but since we could not find similar observations in the literature, a series of experiments was performed to identify them. We will refer to them “traces”, because they contain some, if not all, of the properties of slip traces. A variety of techniques, including the Electron Backscattering Pattern (EBSP) method, was used to ascertain the composition, geometry, and crystallography of these traces. The effect of sample thickness on their formation was also investigated.In summary, these traces on the surface of recrystallized Ni3Al have the following properties:1.The chemistry and crystallographic orientation of the traces are the same as the bulk. No oxides or other second phases were observed.2.The traces are not grooves caused by thermal etching at previous locations of grain boundaries.3.The traces form after recrystallization (because the starting Ni3Al is a single crystal).4.For thicknesses between 50 μm and 720 μm, the density of the traces increases as the sample thickness decreases. Only one set of “protrusion-like” traces is visible in a given grain on the thicker samples, but multiple sets of “cliff-like” traces are visible on the thinner ones (See Fig. 1 and Fig. 2).5.They are linear and parallel to the traces of {111} planes on the surface, see Fig. 3.6.Some of the traces terminate within the interior of the grains, and the rest of them either terminate at or are continuous across grain boundaries. The portion of latter increases with decreasing thickness.7.The grain size decreases with decreasing thickness, the decrease is more pronounced when the grain size is comparable with the thickness, Fig. 4.8.Traces also formed during the recrystallization of cold-rolled polycrystalline Cu thin sheets, Fig. 5.

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Technical Variations in Koelle's Histochemical Method for Demonstrating Cholinesterase Activity

Journal of Cell Science ◽

10.1242/jcs.s3-104.65.89 ◽

1963 ◽

Vol s3-104 (65) ◽

pp. 89-100

Author(s):

N. T. NAIK

Keyword(s):

Cold Storage ◽

Cholinesterase Activity ◽

Enzyme Reaction ◽

Progressive Increase ◽

Histochemical Method ◽

Appreciable Effect ◽

Selective Inhibitors ◽

Ph Values ◽

Contrast Microscopy ◽

Series Of Experiments

Koelle's histochemical method for demonstrating cholinesterase activity and the literature on its subsequent modifications have been reviewed. Experiments were carried out on the effect on the cholinesterase reaction of formaldehyde fixation, cold storage of tissues, pH of incubation solution, and progressive increase of incubation time. A series of experiments was also carried out in testing the specificity of substrates and selective inhibitors used in the Koelle method. Enzyme reaction was visualized by the ammonium sulphide method. As a result of these experiments the following technical desiderata have been established: 1. Fixation of tissues for 3 h in neutral formaldehyde solution at 4° C preserved the morphology of the tissues without appreciably affecting the histochemical results. Fixation for more than 6 h produced definitive inhibition of cholinesterases, especially AChE, in most tissues. 2. Periods of up to 24 h of cold storage before fixation had no appreciable effect on the cholinesterase reaction. 3. Incubation at pH values between 5.0 and 6.0 produced neither significant diffusion artifacts nor loss of enzyme activity. Below pH 5 the AChE reaction was affected to a varying extent according to the tissues used. 4. B.W. 284 at a concentration of 5 x 10-5 M and ethopropazine hydrochloride at a concentration of 1 x 10-4 M were found to be suitable selective inhibitors for AChE and ChE respectively. 5. Visualization of results by means of ammonium sulphide method was found to be preferable to phase-contrast microscopy.

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Inactivation of tyrosine aminotransferase in neutral homogenates and rat liver slices

Biochemical Journal ◽

10.1042/bj1291131 ◽

1972 ◽

Vol 129 (5) ◽

pp. 1131-1138 ◽

Cited By ~ 20

Author(s):

F. Auricchio ◽

L. Mollica ◽

A. Liguori

Keyword(s):

Amino Acid ◽

Rat Liver ◽

Acid Concentration ◽

Tyrosine Aminotransferase ◽

Amino Acid Concentration ◽

Acidic Ph ◽

Ph Values ◽

Neutral Ph ◽

Liver Slices

Inactivation of tyrosine aminotransferase induced in vivo by triamcinolone was studied in a homogenate incubated at neutral pH values. The integrity and the presence of subcellular particles together with a compartment of acidic pH are necessary for inactivation of tyrosine aminotransferase. It is suggested that tyrosine aminotransferase is inactivated inside lysosomes. The system responsible for inactivation of tyrosine aminotransferase was partially purified and identified with lysosomal cathepsins B and B1. Inactivation of tyrosine aminotransferase in liver slices is controlled by the amino acid concentration and strongly stimulated by cysteine. 3,3′,5-Tri-iodo-l-thyronine reversibly and strongly decreases the rate of inactivation of tyrosine aminotransferase. The effect is not due to an increased rate of tyrosine aminotransferase synthesis.

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Integrated Magnetic Analyses for the Discrimination of Urban and Industrial Dusts

Minerals ◽

10.3390/min10121056 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1056

Author(s):

Beata Górka-Kostrubiec ◽

Tadeusz Magiera ◽

Katarzyna Dudzisz ◽

Sylwia Dytłow ◽

Małgorzata Wawer ◽

...

Keyword(s):

Grain Size ◽

Magnetic Particles ◽

Steel Production ◽

Hysteresis Loops ◽

Street Dust ◽

Single Domain ◽

Magnetic Fraction ◽

Magnetic Methods ◽

Urban Dusts ◽

Traffic Related Pollution

Industrial and urban dusts were characterized by investigating their magnetic properties. Topsoil composed of technogenic magnetic particles (TMP) originating from areas affected by three ironworks, street dust mainly composed of traffic-related pollution, and particulate matter (PM) from urban agglomeration in Warsaw, Poland were investigated. Several magnetic methods, namely magnetic susceptibility, thermomagnetic curves, hysteresis loops, decomposition of isothermal remanent magnetization acquisition curves, and first-order reversal curves, were performed to evaluate the magnetic fraction of dust. Magnetite was the main magnetic phase in all types of samples, with a small amount of high-coercive hematite within ironworks and street dust samples. Significant differences were observed in the domain structure (grain size) of industrial and traffic-related magnetic particles. The grain size of TMP obtained from steel production was in the range of 5–20 µm and was predominated by a mixture of single-domain (SD) and multidomain (MD) grains, with the prevalence of SD grains in the topsoil affected by Třinec ironwork. The traffic-related dust contained finer grains with a size of about 0.1 µm, which is characteristic of the pseudo-single-domain (PSD)/SD threshold. Street dusts were composed of a slightly higher proportion of MD grains, while PM also revealed the typical behavior of superparamagnetic particles.

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The Role of Electrochemical Conditions in Near-Neutral pH SCC Initiation Mechanism(s)

2010 8th International Pipeline Conference, Volume 1 ◽

10.1115/ipc2010-31190 ◽

2010 ◽

Author(s):

Abdoulmajid Eslami ◽

Mohammadhassan Marvasti ◽

Weixing Chen ◽

Reg Eadie ◽

Richard Kania ◽

...

Keyword(s):

Cathodic Protection ◽

Pipeline Steel ◽

Synergistic Effects ◽

Co2 Concentration ◽

Initiation Mechanism ◽

Ph Values ◽

Neutral Ph ◽

Comprehensive Test ◽

Disbonded Coating

In order to improve our understanding of near-neutral pH SCC initiation mechanism(s), a comprehensive test setup was used to study the electrochemical conditions beneath the disbonded coatings in cracking environments. In this setup the synergistic effects of cyclic loading, coating disbondment, and cathodic protection were considered. Our previous results showed that there can be a significant variation in the pH of the localized environment under the disbonded coating of pipeline steel. The pH inside the disbondment can change significantly from near-neutral to high pH values, strongly depending on the level of cathodic protection and CO2 concentration. Both of these variables affected the electrochemical conditions on the steel surface and therefore the initiation mechanisms. This work highlights the role of electrochemical conditions in near-neutral pH SCC initiation mechanisms.

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Effect of Headspace Oxygen Concentration on Growth and Toxin Production by Proteolytic Strains of Clostridium botulinum

Journal of Food Protection ◽

10.4315/0362-028x-55.1.23 ◽

1992 ◽

Vol 55 (1) ◽

pp. 23-27 ◽

Cited By ~ 11

Author(s):

R. C. WHITING ◽

K. A. NAFTULIN

Keyword(s):

Clostridium Botulinum ◽

Critical Level ◽

Toxin Production ◽

Inoculum Size ◽

Oxygen Levels ◽

Ph Values ◽

Headspace Oxygen ◽

Series Of Experiments ◽

Germination And Growth ◽

Toxin Formation

A series of experiments was conducted to determine growth and toxin formation by proteolytic strains of Clostridium botulinum in broth media that have known pH values (5–7), NaCl concentrations (0–4%), and controlled oxygen-nitrogen atmospheres. Lower pH and higher NaCl levels inhibited growth and toxin production by vegetative cells, but 15% oxygen in the headspace was insufficient for inhibition in all media. When spores were used as inocula and the tubes were gas flushed, outgrowth and toxin production generally occurred only under a 1% or less oxygen atmosphere. Occurrence of growth and toxin was favored by high pH and low NaCl levels and was related to spore inoculum size. Spores were also inoculated into a mixed fermenter with controlled oxygen levels in the headspace. Times to measurable turbidity increased with greater oxygen levels from 36 h at 0.005% O2 to 109 h at 0.7% O2; however, growth rates were unaffected by headspace oxygen levels. No toxin was observed with 0.9% O2, further demonstrating that the critical level of oxygen for germination and growth is approximately 1%.

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Synthesis and Dispersity of YBCO Powder Produced by Oxalic Acid Precipitation Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.645-646.145 ◽

2015 ◽

Vol 645-646 ◽

pp. 145-150 ◽

Cited By ~ 2

Author(s):

Ai Qin Wang ◽

Hui Hui Han ◽

Min Li ◽

Jing Pei Xie ◽

Qing Jie Wu ◽

...

Keyword(s):

Grain Size ◽

Oxalic Acid ◽

Technological Parameter ◽

Oxalic Acid Solution ◽

Acid Precipitation ◽

Precipitation Method ◽

Test Results ◽

Ph Values ◽

Mean Grain Size ◽

The Mean

The YBCO powder was prepared by oxalic acid precipitation method and consequent annealing. The correlation between pH values of oxalic acid solution and the precipitation percentage of precursors were analysed based on thermodynamics analysis. The differential scanning calorimetryanalysis (DSC) was used to confirm the synthetic technological parameter. The phases of powder in each process were investigated by XRD. The microstructures of each powder were tested by SEM and TEM. The mean grain size was calculated by the scherrer’s equation. The test results indicated that the YBCO powder with high purity, less impurities, smaller particle, but severe agglomeration, was Y123 when annealing at 900°C. However, adding dispersants could effectively solve the severe agglomeration. The size of YBCO particles was nanosized and coincided with the calculation.

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Multiple α-mannosidase activities in mammalian tissues as shown by metal-ion activation

Biochemical Journal ◽

10.1042/bj1630557 ◽

1977 ◽

Vol 163 (3) ◽

pp. 557-564 ◽

Cited By ~ 7

Author(s):

S M Snaith

Keyword(s):

Metal Ions ◽

Metal Ion ◽

Active Enzyme ◽

Thiol Groups ◽

Ion Activation ◽

Ph Values ◽

Neutral Ph ◽

Mammalian Tissues ◽

Different Types ◽

Metal Ion Activation

1. Four different types of alpha-mannosidase activity were shown to occur in several tissues from the rat. There is the Zn2+-dependent enzyme, active at acidic pH, and three enzymes that are active near to neutral pH. 2. The ‘neutral’ enzymes are activated by Fe2+, Co2+ or Mn2+. 3. Optimum activities for these three enzymes are shown at pH values of 5.2, 6.5 and 7.3. The activity at pH6.5 is the only one evident without metal-ion activation, but activity is enhanced by all three metal ions. The activity at pH 5.2 is seen only in the presence of Fe2+ or Co2+, and the activity at pH7.3 is seen only in the presence of Co2+ or Mn2+ and in a non-chelating buffer medium. 4. The pH6.5-active enzyme is inactivated by EDTA, but activity is restored by excess of metal ion. 5. The enzymes differ markedly in their stability. The pH6.5-active enzyme is very labile and the pH7.3-active enzyme is the most stable. 6. Tissue preparations vary widely in their activity at pH6.5, but where activity is low it can be increased by incubation with one of the activating metal cations. 7. All the enzymes active at neutral pH are inhibited by heavy-metal ions and stabilized to some extent by thiol groups.

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THE EFFECT OF CELLULOSE ADDITIONS AND MOISTURE LEVEL ON MYCOFLORA OF SOIL

Canadian Journal of Microbiology ◽

10.1139/m63-071 ◽

1963 ◽

Vol 9 (4) ◽

pp. 555-561 ◽

Cited By ~ 5

Author(s):

Zofia Maciejowska ◽

E. B. Williams

Keyword(s):

Water Holding Capacity ◽

Moisture Level ◽

High Moisture ◽

Fungus Flora ◽

Amended Soils ◽

Cellulose Decomposition ◽

Ph Values ◽

Neutral Ph ◽

Major Factors ◽

Water Holding

The fungus flora developing in cellulose-amended and non-amended soils of neutral pH at moisture levels of 60, 70, and 80% water-holding capacity (WHC) was investigated. A distinct, successive development of three species, Staphylotrichum coccosporum, Coccospora agricola, and Sependonium sp., was observed in soil held at 60% WHC. More species developed in soil held at 70% WHC, and they could effectively coexist during cellulose decomposition. S. coccosporum developed in smaller numbers at 80% WHC than at 60 and 70% WHC. Sepedonium sp. was associated with cellulose decomposition only at 80% WHC. Species of Trichoderma, Monilia, and Fusarium developed better at high moisture levels. It was concluded that available inoculum and the moisture of soils of similar pH values are major factors in determining composition of the microflora of cellulose-amended soil.

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