Grain Boundary Diffusivity Measurement Through Kinetic Analysis Of Discontinuous Precipitation

1991 ◽  
Vol 238 ◽  
Author(s):  
I. Manna ◽  
J. N. Jha ◽  
S. K. Pabi ◽  
W. Gust
Keyword(s):  
Grain Boundary ◽  
Supersaturated Solid Solution ◽  
Discontinuous Precipitation ◽  
Chemical Diffusion ◽  
Chemical Diffusivity ◽  
Two Phase ◽  
Diffusivity Measurement ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time

ABSTRACTDiscontinuous precipitation involves formation of a two phase aggregate from a supersaturated solid solution behind a migrating boundary. It is established that the solute transport occurs primarily through the migrating boundary, called the reaction front. This report presents a systematic study of discontinuous precipitation in a Zn-Ag alloy and measurement of grain boundary chemical diffusivity of Ag in Zn-Ag using a suitable analytical model for the first time. The necessary kinetic parameters were determined by optical and scanning electron microscopes. The activation energy for boundary chemical diffusion of Ag in Zn-Ag has been estimated to be 65.8 kJ/mol.

Choosing a Scanning Electron Microscope

1998 ◽  
Vol 4 (S2) ◽  
pp. 896-897
Author(s):  
W. A. Lambe ◽  
P.M. Brady
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Selection Process ◽  
The Other ◽  
Hard Data ◽  
Methodical Approach ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

The variety of instrumentation available to the researcher today can be overwhelming and confusing. Scanning Electron Microscopes (“SEM's) are no exception, and choosing one can often serve as an exercise in dealing with complexity. First time purchasers are most at risk, being subject to a barrage of information that attempts to sway the purchaser in one direction or the other. As a result, one can sometimes be drawn to the details of the latest “high end” performance parameter, while overlooking the basics. At its worst, the selection process can degrade to one of vague guesswork with little hard data to serve as a compass.By applying a methodical approach to define your individual requirements, carefully designed tests of actual instruments, and discussions with your collaborators, potential and experienced users, one can begin to ensure a successful selection process.

scholarly journals Pollen morphology of some Turkish Campanula spp. and their taxonomic value

1970 ◽  
Vol 37 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Ismuhan Potoglu Erkara ◽  
Atila Ocak ◽  
Sevil Pehlivan
Keyword(s):  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

Detailed pollen morphological structures of 12 Turkish species of Campanula L., e.g. C. argaea, C. cymbalaria, C. glomerata subsp. hispida, C. latiloba subsp. latiloba, C. lyrata subsp. lyrata, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia, C. rapunculus var. rapunculus, C. stricta var. stricta, C. pamphylica subsp. tokurii have been studied under light (LM) and scanning electron microscopes (SEM) for the first time. LM and SEM investigations show that the pollen grains of 12 taxa are more or less oblato-sphaeroidal, triporate (and/or tetraporate), tectum-scabrate, or with circular amb. The exine sculpture is granulate-scabrate in C. argaea, C. lyrata subsp. lyrata, C. stricta var. stricta, C. glomerata subsp. hispida and C. pamphylica subsp. tokurii; but those of C. cymbalaria, C. latiloba subsp. latiloba, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia and C. rapunculus var. rapunculus are rugulate-scabrate.   Key words: Campanula, Pollen grains, Pollen morphology doi:10.3329/bjb.v37i1.1561 Bangladesh J. Bot. 37(1): 33-42, 2008 (June)

scholarly journals Ploidy level and obligate apogamy in two populations of Argyrochosma nivea var. tenera (Pteridaceae)

Hoehnea ◽  
2015 ◽  
Vol 42 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Marcela A. Hernández ◽  
Aldo R. Andrada ◽  
Valeria de los A. Páez ◽  
Olga G. Martínez
Keyword(s):  
Meiotic Chromosome ◽  
Glandular Trichomes ◽  
Hybrid Origin ◽  
American Continent ◽  
Reproduction Mode ◽  
Ethanol Acetic Acid ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Two Populations

ABSTRACT Argyrochosma nivea var. tenera is a cheilanthoid fern from the American continent. We present herewith the study of meiotic behavior and gametic number as well as number of spores and reproduction mode (with observations from cultured gametophytes). The study material is from Northwestern Argentina. For the study of meiosis, sporangia were fixed in ethanol-acetic acid (3:1) and stained with 2% propionic haematoxylin. Micrographs were taken using light and scanning electron microscopes. Meiotic chromosome number is 2n = 3x = 81 and the presence of lagging chromosomes at telophase II is mentioned for the first time; three sets of chromosome occur at diakinesis. Sporangia have 32 trilete spores. Adult gametophytes are laminar, cordiform, asymetrical, glabrous, without glandular trichomes. In our samples, the adult gametophytes were neuter, without antheridia or archegonia, with obligate apogamous reproduction. Both populations studied might be of hybrid origin.

Determination of Polymorphic Transformation Temperature for Alloy VT8

2019 ◽  
Vol 946 ◽  
pp. 42-46
Author(s):  
Nikita A. Zavartsev ◽  
Nadezhda T. Kareva
Keyword(s):  
Chemical Composition ◽  
Transformation Temperature ◽  
Polymorphic Transformation ◽  
Graphical Form ◽  
Two Phase ◽  
Quenching Temperature ◽  
Different Temperatures ◽  
Electron Microscopes ◽  
The Individual ◽  
Scanning Electron Microscopes

The temperature of polymorphic transformation (Tpt) has been determined for accurate composition of two-phase titanium alloy which has been marked like VT8 through different ways: the method of trial quench and with the help of dilatometric and differential thermal analyzes. The close values of Tpt have been received. Herewith the phase composition has been estimated qualitatively and quantitatively for the hardened samples of alloy VT8 using optical and scanning electron microscopes and the chemical composition with the help of the micro X-ray spectral analysis. The influence of the quenching temperature on the hardness has been investigated. Also, the hardness of the individual structural components and alloy VT8 as a whole unit has been measured. Hardness curves are based depending of the quenching temperature; the results are displayed in tabular and graphical form. The coefficientkhas been found for the calculation of allotropic transformation temperature for this alloy using the known temperature of hardening and quantity of preserved α-phase of hardened structure. The album of the microstructures after quench with different temperatures has been created, this album will allow to reduce the duration of preliminary works for finding specific temperature of polymorphic transformation in production conditions for each new batch of alloy VT8 with another chemical composition (but within the vintage), knowledge of which is necessary for setting the temperature regime of treatment.

scholarly journals Investigation of post-weld heat treatment (T6) and welding orientation on the strength of TIG-welded AL6061

2020 ◽  
Vol 10 (1) ◽  
pp. 753-761
Author(s):  
Gunawan Dwi Haryadi ◽  
Rando Tungga Dewa ◽  
I. M. W. Ekaputra ◽  
Agus Suprihanto
Keyword(s):  
Heat Treatment ◽  
Artificial Aging ◽  
Rolling Direction ◽  
Post Weld Heat Treatment ◽  
Two Phase ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Precipitate Strengthening ◽  
Strength And Ductility ◽  
Weld Heat

AbstractThis paper investigates the influence of T6 post-weld heat treatment (PWHT), and welding orientation on the strength and microstructure of tungsten inert gas (TIG) welded AL6061 aluminum alloy. The TIG process was used to weld the AL6061 at the transversal and longitudinal orientations with reference to the rolling direction. The T6-PWHT is a two-phase heat treatment process, and was applied to AL6061 in order to increase its strength. This T6 was carried out under three different artificial aging; 8, 18, and 24 hours. The influence of PWHT and welding orientation on the strength of AL6061-T6 were investigated through a series of tensile and microhardness tests. In addition, the microstructure observations were performed using the optical and scanning electron microscopes. It was established that the strength and microstructural characteristics of AL6061 are significantly dependent on the T6 artificial aging. Accordingly, the improvements in the strength and ductility were mainly contributed by the grain growth and subsequent precipitate strengthening. Moreover, the welding orientation only affects their fracture surfaces and locations after tensile testing.

scholarly journals Pollen morphology of some Turkish Ajuga L. (Lamiaceae) and its taxonomic value

1970 ◽  
Vol 40 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Yavuz Bulent Kose ◽  
Ismahan Potoglu Erkara ◽  
Sevim Alan
Keyword(s):  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

Pollen morphological structures of eight Turkish species of Ajuga, namely A. bombycina Boiss., A. chamaepitys (L.) Schreber ssp. chia var. chia (Schreber) Arcangeli, A. chamaepitys (L.) Schreber ssp. chia var. ciliata Briq., A. chamaepitys (L.) Schreber ssp. cuneatifolia (Stapf) P. H. Davis, A. genevensis L., A. laxmannii (L.) Benthum, A.orientalis L. and A. reptans L. have been studied under light and scanning electron microscopes for the first time. It is revealed that the pollen grains of Ajuga taxa are more or less suboblata-subprolata and tricolpatae. The exine sculpture is granulate in A. chamaepitys subsp. chia var. chia, A. chamaepitys subsp. cuneatifolia, A. genevensis, A. laxmannii, A. orientalis and A. reptans, but it is reticulate in A. bombycina and A. chamaepitys subsp. chia var. ciliata. Key words: Turkish Ajuga; Pollen morphology; Taxonomic value DOI: http://dx.doi.org/10.3329/bjb.v40i1.7994 Bangladesh J. Bot. 40(1): 29-33, 2011 (June)

scholarly journals A Novel Design of Continuous Culture for In Vitro Formation of Gallstones by Salmonella Typhi

2021 ◽  
pp. 1-5
Author(s):  
Sahira Al-Sanjary ◽  
Amera Al-Rawi
Keyword(s):  
Calcium Carbonate ◽  
Continuous Culture ◽  
Salmonella Typhi ◽  
Infrared Spectrometry ◽  
Electron Microscopes ◽  
The Fourier Transform ◽  
Model Bile ◽  
Scanning Electron Microscopes ◽  
First Time

The current research focused on detecting the role of Salmonella typhi (S. typhi) in the formation of gallbladder stones in the laboratory following isolation and diagnosis of S. typhi from bile samples of patients suffering from gallstone. Locally and for the first time, a novel continuous culture was designed, and Brilliant Green Bile Broth (BGBB) was used by adding 60% cholesterol and 20% Calcium Carbonate (CaCO3) to form the gallstone nucleation. The continuous culture was inoculated with 1% S. typhi then incubated in optimal conditions for 20 days. After 14 days of incubation, results revealed the formation of spherical aggregations with various sizes in the test flask compared to the control flask. Moreover, an increase in the size of the stone formed was observed after 20 days of incubation. The morphology of cholesterol and Calcium Carbonate crystals were studied using light, fluorescent and scanning electron microscopes, and the functional groups were diagnosed using the Fourier transform infrared spectrometry (FTIR) technique. KEYWORDS Biliary microbiota, model Bile, polysaccharide production

Hydathodal pores in lodicules of Avena (Gramineae)

1970 ◽  
Vol 48 (12) ◽  
pp. 2360-2360 ◽  
Author(s):  
B. R. Baum ◽  
J. N. Findlay
Keyword(s):  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

The occurrence of hydathodal pores in lodicules of various species of Avena is reported for the first time. Those of cultivated oats (A. sativa L.) are described from examinations made under interference contrast and scanning electron microscopes.

Toward High-Resolution Low-Voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 218-219
Author(s):  
Zhifeng Shao
Keyword(s):  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Limiting Factor ◽  
Operating Voltage ◽  
Probe Radius ◽  
Non Local ◽  
Electron Microscopes ◽  
Image Position ◽  
Scanning Electron Microscopes

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as

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