scholarly journals Kinetic Studies of Polyhydroxybutyrate Granule Formation in Wautersia eutropha H16 by Transmission Electron Microscopy

2005 ◽  
Vol 187 (11) ◽  
pp. 3814-3824 ◽  
Author(s):  
Jiamin Tian ◽  
Anthony J. Sinskey ◽  
JoAnne Stubbe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Area ◽  
Ralstonia Eutropha ◽  
Kinetic Studies ◽  
Total Surface Area ◽  
Granule Formation ◽  
Unbiased Stereology ◽  
Transmission Electron ◽  
Wautersia Eutropha

ABSTRACT Wautersia eutropha, formerly known as Ralstonia eutropha, a gram-negative bacterium, accumulates polyhydroxybutyrate (PHB) as insoluble granules inside the cell when nutrients other than carbon are limited. In this paper, we report findings from kinetic studies of granule formation and degradation in W. eutropha H16 obtained using transmission electron microscopy (TEM). In nitrogen-limited growth medium, the phenotype of the cells at the early stages of granule formation was revealed for the first time. At the center of the cells, dark-stained “mediation elements” with small granules attached were observed. These mediation elements are proposed to serve as nucleation sites for granule initiation. TEM images also revealed that when W. eutropha cells were introduced into nitrogen-limited medium from nutrient-rich medium, the cell size increased two- to threefold, and the cells underwent additional volume changes during growth. Unbiased stereology was used to analyze the two-dimensional TEM images, from which the average volume of a W. eutropha H16 cell and the total surface area of granules per cell in nutrient-rich and PHB production media were obtained. These parameters were essential in the calculation of the concentration of proteins involved in PHB formation and utilization and their changes with time. The extent of protein coverage of the granule surface area is presented in the accompanying paper (J. Tian, A. He, A. Lawrence, P. Liu, N. Watson, A. J. Sinskey, and J. Stubbe, J. Bacteriol. 187:3825-3832, 2005).

Determination of reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica for hydrogenseparation at high temperature

2010 ◽  
Vol 25 (10) ◽  
pp. 2008-2014 ◽  
Author(s):  
Yumi H. Ikuhara ◽  
Tomohiro Saito ◽  
Yukichi Sasaki ◽  
Seiji Takahashi ◽  
Tsukasa Hirayama
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Area ◽  
Amorphous Silica ◽  
Hydrogen Adsorption ◽  
Total Surface Area ◽  
Dark Field ◽  
Adsorbed Hydrogen ◽  
Ni Nanoparticles ◽  
Transmission Electron

The reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica (Si-O) was identified by analyzing the hydrogen adsorption behavior and the microstructure. The total amount of reversibly adsorbed hydrogen was evaluated from the total surface area of Ni and the Ni concentration in the composite. The total surface area of the Ni nanoparticles in each sample powder was calculated from the mean particle size of the Ni nanoparticles in the Si-O matrix using dark field images taken by transmission electron microscopy and high-angle annular dark-field images by scanning transmission electron microscopy. The estimated amount of reversibly adsorbed hydrogen was highly consistent with that obtained experimentally by hydrogen adsorption analysis, which suggested that reversible hydrogen adsorption occurred at the Ni/Si-O interface.

scholarly journals Analysis of Transient Polyhydroxybutyrate Production in Wautersia eutropha H16 by Quantitative Western Analysis and Transmission Electron Microscopy

2005 ◽  
Vol 187 (11) ◽  
pp. 3825-3832 ◽  
Author(s):  
Jiamin Tian ◽  
Aimin He ◽  
Adam G. Lawrence ◽  
Pinghua Liu ◽  
Nicki Watson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Period ◽  
Polymerization Reaction ◽  
Alternative Mechanism ◽  
Granule Formation ◽  
Average Cell ◽  
Western Analysis ◽  
Transmission Electron ◽  
Wautersia Eutropha

ABSTRACT Polyhydroxybutyrates (PHBs) are polyoxoesters generated from (R)3-hydroxybutyryl coenzyme A by PHB synthase. During the polymerization reaction, the polymers undergo a phase transition and generate granules. Wautersia eutropha can transiently accumulate PHB when it is grown in a nutrient-rich medium (up to 23% of the cell dry weight in dextrose-free tryptic soy broth [TSB]). PHB homeostasis under these growth conditions was examined by quantitative Western analysis to monitor the proteins present, their levels, and changes in their levels over a 48-h growth period. The proteins examined include PhaC (the synthase), PhaP (a phasin), PhaR (a transcription factor), and PhaZ1a, PhaZ1b, and PhaZ1c (putative intracellular depolymerases), as well as PhaZ2 (a hydroxybutyrate oligomer hydrolase). The results show that PhaC and PhaZ1a were present simultaneously. No PhaZ1b or PhaZ1c was detected at any time throughout growth. PhaZ2 was observed and exhibited an expression pattern different from that of PhaZ1a. The levels of PhaP changed dramatically and corresponded kinetically to the levels of PHB. Transmission electron microscopy (TEM) provided the dimensions of the average cell and the average granule at 4 h and 24 h of growth (J. Tian, A. J. Sinskey, and J. Stubbe, J. Bacteriol. 187:3814-3824, 2005). This information allowed us to calculate the amount of each protein and number of granules per cell and the granule surface coverage by proteins. The molecular mass of PHB (106 Da) was determined by dynamic light scattering at 4 h, the time of maximum PHB accumulation. At this time, the surface area of the granules was maximally covered with PhaP (27 to 54%), and there were one or two PhaP molecules/PHB chain. The ratio of PHB chains to PhaC was ∼60, which required reinitiation of polymer formation on PhaC. The TEM studies of wild-type and ΔphaR strains in TSB provided further support for an alternative mechanism of granule formation (Tian et al., J. Bacteriol. 187:3814-3824, 2005).

Microstructure of LaB6-base thick film resistors

1992 ◽  
Vol 7 (8) ◽  
pp. 2225-2229 ◽  
Author(s):  
Z.G. Li ◽  
P.F. Carcia ◽  
P.C. Donohue
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thick Film ◽  
Surface Area ◽  
Ion Milling ◽  
Cross Sectional ◽  
Electrically Conductive ◽  
Transmission Electron ◽  
High Temperature Processing ◽  
Thin Wedge

The microstructure of LaB6-base thick film resistors was investigated by cross-sectional transmission electron microscopy. The specimens were prepared by a technique that polished them to a thin wedge, thus avoiding ion-milling and permitting imaging over a distance of tens of microns. The resistor microstructure contained a finely divided electrically conductive phase of TaB2 and nonconducting crystals of CaTa4O11, formed during high temperature processing of glass and LaB6 ingredients of the thick film ink. Using higher surface area ingredients virtually suppressed the formation of CaTa4O11 crystals, and the microstructure became more uniform. Resistors made with higher surface area intermediates also had better voltage withstanding properties.

Methods of analysing morphology of kaolinites: relations between crystallographic and morphological properties

Clay Minerals ◽  
1986 ◽  
Vol 21 (1) ◽  
pp. 55-68 ◽  
Author(s):  
J.M. Cases ◽  
P. Cunin ◽  
Y. Grillett ◽  
C. Poinsignon ◽  
J. Yvon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Area ◽  
Lateral Surface ◽  
Morphological Properties ◽  
Surfactant Adsorption ◽  
Adsorption Calorimetry ◽  
Crystalline Sample ◽  
Transmission Electron ◽  
Total Specific Surface Area

AbstractA study was made of the extent to which the lateral surfaces contribute to the surface area of five kaolinites of different crystallinities. Methods used included the low-temperature adsorption of N2and Ar as measured by a volumetric technique coupled with microcalorimetry, the interpretation of the adsorption isotherms of alkyldodecylammonium ions, particle-size distribution curves, and shadowed transmission electron microscopy. With the exception of surfactant adsorption and adsorption calorimetry using Ar, these methods gave different and debatable results. For instance, specific lateral surface area values expressed as a percentage of total specific surface area varied from 17·0 to 40·4% for the most crystalline sample and from 12·0 to 54·3% for the least crystalline. It is shown that the decrease in crystallinity of samples is accompanied by a reduction in crystallite size from 0·8 to 0·08 µm and a decrease in lateral surface area from 34·0 to 12·0%.

Preparation of Carbon-Encapsulated Fe Core-Shell Nanostructures by Confined Arc Plasma

2011 ◽  
Vol 688 ◽  
pp. 245-249 ◽  
Author(s):  
Zhi Qiang Wei ◽  
Xiao Yun Wang ◽  
Hua Yang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Core Shell ◽  
Arc Plasma ◽  
X Ray ◽  
The Core ◽  
Transmission Electron

Special carbon encapsulated Fe core-shell nanoparticles with a size range of 15–40 nm were successfully prepared via confined arc plasma method. The composition, morphology, microstructure, specific surface area, particle size of the product by this process were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (XEDS) and BET N2adsorption. The experiment results shown that the carbon encapsulated Fe nanoparticles with clear core-shell structure, the core of the particles is body centered cubic (BCC) structure Fe, and the shell of the particles is disorder carbons. The particle size of the nanocapsules ranges from 15 to 40nm，with an averaged value about 30nm, the particles diameter of the core is about 16nm and the thickness of the shells is about 6-8 nm, and the specific surface area is 24 m2/g.

Kinetic Studies of Nanoscale Crystallization in Electronic Materials

1995 ◽  
Vol 405 ◽  
Author(s):  
C. Hayzelden ◽  
J. L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Electronic Materials ◽  
Kinetic Studies ◽  
Subsequent Growth ◽  
Transmission Electron ◽  
Amorphous Si

AbstractWe report a kinetic analysis of low-temperature NiSi2-mediated crystallization of amorphous Si by in situ transmission electron microscopy. The initiation of crystallization by formation of crystalline Si on buried NiSi2 precipitates is shown to have an activation energy of 2.8±0.7eV. Crystallization of the amorphous Si via migrating precipitates of NiSi2 occurs with an activation energy of 2.0±0.2eV. The significance of these activation energies is discussed in terms of possible atomistic mechanisms of crystalline Si initiation and subsequent growth. Amorphous Si is reported to crystallize at temperatures as low as 450°C.

scholarly journals Template method for graphene synthesis

2019 ◽  
Vol 488 (5) ◽  
pp. 508-512
Author(s):  
V. V. Chesnokov ◽  
A. S. Chichkan ◽  
A. F. Bedilo ◽  
E. I. Shuvarakova ◽  
V. N. Parmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrochloric Acid ◽  
Surface Area ◽  
Acid Treatment ◽  
Template Method ◽  
Graphene Layers ◽  
Graphene Synthesis ◽  
Transmission Electron ◽  
Mgo Surface

A series of carbon-mineral composites with the carbon content varying from 1.5 to 12.2 wt.% was synthesized by MgO carbonization in 1,3-butadiene at 600 oC. The synthesized carbon-mineral composites were studied by EPR, XRD and transmission electron microscopy. It was shown by EPR that the MgO surface was completely covered with carbon after depositing 8-10 wt.% C. MgO from the composite was dissolved by treatment in hydrochloric acid. The surface area of the carbon samples obtained after the acid treatment was studied by thermal desorption of argon. It was shown that the synthesized carbon material consisted of several graphene layers. Specific surface area of the synthesized graphene had a maximum about 1800-1900 m2/g for samples obtained from C-MgO composites containing 8-10 wt.% C.

Transmission Electron Microscopy Studies of Pd Encapsulation by Ceria-Zirconia Oxides

1998 ◽  
Vol 4 (S2) ◽  
pp. 724-725
Author(s):  
J. C. Jiang ◽  
X. Q. Pan ◽  
G. W. Graham ◽  
R. W. McCabe ◽  
J. Schwank
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Surface Area ◽  
High Speed ◽  
High Surface ◽  
Silicon Crystal ◽  
High Surface Area ◽  
Thermal Environments ◽  
Transmission Electron

High-temperature catalysts containing Pd supported on high-surface area ceria-zirconia are optimum materials for fuel economy when automotive engines operate under high speed or load conditions. A prerequisite for developing such thermally stable catalysts is to gain a good understanding of the thermal deactivation modes contributing to the aging and degradation of catalysts in harsh thermal environments. It was discovered by X-ray diffraction that upon hightemperature aging, Pd may sinter into large (about 10 nm diameter) particles and become encapsulated in the ceria-zirconia. To confirm this conclusion, a prototype high-temperature catalyst containing Pd supported on high-surface area ceria-zirconia, aged at temperature above 1100 °C is studied by transmission electron microscopy (TEM).The ceria-zirconia supported Pd (0.25 wt%) catalyst was aged at 1105 °C and calcined at 700 °C for 2 h. For TEM sample preparations, first of all, a large-size aggregate with diameter about 1 mm was selected and sandwiched between by two pieces of silicon crystal.

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