scholarly journals Uranium Carbide Fibers with Nano-Grains as Starting Materials for ISOL Targets

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2458
Author(s):  
Sanjib Chowdhury ◽  
Leonor Maria ◽  
Adelaide Cruz ◽  
Dario Manara ◽  
Olivier Dieste-Blanco ◽  
...  
Keyword(s):  
Cellulose Acetate ◽  
Uranyl Acetate ◽  
Slow Heating ◽  
Acetate Solution ◽  
Fiber Morphology ◽  
Uranium Carbide ◽  
C Fibers ◽  
Effective Contact ◽  
Viscous Solutions ◽  
Nano Grains

This paper presents an experimental study about the preparation, by electrospinning, of uranium carbide fibers with nanometric grain size. Viscous solutions of cellulose acetate and uranyl salts (acetate, acetylacetonate, and formate) on acetic acid and 2,4-pentanedione, adjusted to three different polymer concentrations, 10, 12.5, and 15 weight %, were used for electrospinning. Good quality precursor fibers were obtained from solutions with a 15% cellulose acetate concentration, the best ones being produced from the uranyl acetate solution. As-spun precursor fibers were then decomposed by slow heating until 823 K under argon, resulting in a mixture of nano-grained UO2 and C fibers. A last carboreduction was then carried out under vacuum at 2073 K for 2 h. The final material displayed UC2−y as the major phase, with grain sizes in the 4 nm–10 nm range. UO2+x was still present in moderate concentrations (~30 vol.%). This is due to uncomplete carboreduction that can be explained by the fiber morphology, limiting the effective contact between C and UO2 grains.

Reconstruction of Two-Dimensional Projections of GP 32*I

1981 ◽  
Vol 39 ◽  
pp. 38-39
Author(s):  
H.A. Cohen ◽  
W. Chiu ◽  
J. Hosoda
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Uranyl Acetate ◽  
Distilled Water ◽  
Acetate Solution ◽  
Two Dimensional ◽  
Parent Molecule ◽  
T4 Bacteriophage ◽  
Electron Imaging ◽  
Better Than

GP 32 (molecular weight 35000) is a T4 bacteriophage protein that destabilizes the DNA helix. The fragment GP32*I (77% of the total weight), which destabilizes helices better than does the parent molecule, crystallizes as platelets thin enough for electron diffraction and electron imaging. In this paper we discuss the structure of this protein as revealed in images reconstructed from stained and unstained crystals.Crystals were prepared as previously described. Crystals for electron microscopy were pelleted from the buffer suspension, washed in distilled water, and resuspended in 1% glucose. Two lambda droplets were placed on grids over freshly evaporated carbon, allowed to sit for five minutes, and then were drained. Stained crystals were prepared the same way, except that prior to draining the droplet, two lambda of aqueous 1% uranyl acetate solution were applied for 20 seconds. Micrographs were produced using less than 2 e/Å2 for unstained crystals or less than 8 e/Å2 for stained crystals.

Alkaline Dissociation Products of Lumbricus Terrestris Hemoglobin Viewed with the STEM

1981 ◽  
Vol 39 ◽  
pp. 434-435
Author(s):  
O. H. Kapp ◽  
M. Ohtsuki ◽  
N. Robin ◽  
S. N. Vinogradov ◽  
A. V. Crewe
Keyword(s):  
Carbon Film ◽  
Lumbricus Terrestris ◽  
Uranyl Acetate ◽  
Acetate Solution ◽  
Oxygen Carriers ◽  
Complex Molecules ◽  
Thin Carbon ◽  
Thin Carbon Film ◽  
Multiple Copies ◽  
Hill Coefficients

Annelid extracellular hemoglobins are among the largest known proteins (M.W = 3.9 x 106), and together with the hemocyanins are the largest known oxygen carriers. They display oxygen affinities generally higher than those o vertebrate hemoglobins with Hill coefficients ranging from slightly higher than unity to values as high as 5-6. These complex molecules are composed of multiple copies of as many as six different polypeptides and posse: approximately 150 hemes per molecule.The samples were diluted to 100-200 μg/ml with distilled water just before application to a thin carbon film (∽15 Å thick). One percent (w/v) uranyl acetate solution was used for negative staining for 2 minutes and dried in air. The specimens were examined with the high resolution STEM. Their general appearance is that of a hexagonal bilayer (Fig. 1), each layer consisting of six spheroidal subunits. The corner to corner hexagonal dimensic is approximately 300 Å and the bilayer thickness approximately 200 Å.

Simply Electrospun Gelatin/Cellulose Acetate Nanofibers and their Physico-Chemical Characteristics

2016 ◽  
Vol 880 ◽  
pp. 95-98 ◽  
Author(s):  
Fuji Hernawati Kusumah ◽  
Ida Sriyanti ◽  
Dhewa Edikresnha ◽  
Muhammad Miftahul Munir ◽  
Khairurrijal
Keyword(s):  
Cellulose Acetate ◽  
Structural Changes ◽  
Drug Carrier ◽  
Precursor Solution ◽  
Average Diameter ◽  
Acetate Solution ◽  
Mass Reduction ◽  
Sem Images ◽  
Physico Chemical ◽  
Electrospun Gelatin

Gelatin in fibers form can be used for tissue engineering, wound dressing, or drug carrier. However, it is easily damaged if exposed to water. Thus, it was blended with cellulose acetate. Acetic acid was used as a solvent because it is less toxic. The mass ratios of gelatin to cellulose acetate of 10:0, 8:2, and 6:4 were as precursor solutions. Simple electrospinning was employed to produce gelatin/cellulose acetate fibers. From SEM images, it was shown that the average diameters of gelatin/cellulose acetate fibers from the precursor solutions of 10:0, 8:2, and 6:4 were 534, 649, and 765 nm, respectively. The addition of cellulose acetate increased the viscosity of gelatin/cellulose acetate solution. Moreover, gelatin mass reduction caused a decrease in conductivity of gelatin/cellulose acetate solution. Therefore, increasing in the viscosity or reducing in the conductivity of the precursor solution increased the average diameter of the gelatin/cellulose acetate fibers. The analysis of FTIR spectra showed that the structural changes of gelatin and cellulose acetate occurred after being transformed into gelatin/cellulose acetate nanofibers.

scholarly journals Evaluation of contact time and fiber morphology on bacterial immobilization for development of novel surfactant degrading nanofibrous webs

RSC Advances ◽  
2015 ◽  
Vol 5 (124) ◽  
pp. 102750-102758 ◽  
Author(s):  
Omer Faruk Sarioglu ◽  
Asli Celebioglu ◽  
Turgay Tekinay ◽  
Tamer Uyar
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Cellulose Acetate ◽  
Contact Time ◽  
Sodium Dodecyl ◽  
Bacterial Strains ◽  
Fiber Morphology ◽  
Dodecyl Sulfate ◽  
Bacterial Immobilization

Novel electrospun fibrous biocomposites were developed by immobilizing two different sodium dodecyl sulfate (SDS) biodegrading bacterial strains on electrospun non-porous cellulose acetate (nCA) and porous cellulose acetate (pCA) webs.

scholarly journals Observations of Microcrystalline Plagioclase Spherulites With the Transmission Electron Microscope

1982 ◽  
Vol 5 (1) ◽  
pp. 63-70
Author(s):  
R. Mark Bailey ◽  
H. R. Wenk
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Fiber Diameter ◽  
Growth Direction ◽  
Fiber Axis ◽  
Constant Thickness ◽  
Fiber Morphology ◽  
Thin Sections ◽  
C Fibers ◽  
Transmission Electron

Two thin sections of macroscopic plagioclase spherulites of approximately 1 cm diameter found in a rhyolitic glass have been studied with the transmission electron microscope (TEM). Orientations of the thin sections were chosen to give views down and perpendicular to the major fiber axis. The crystalline fiber phase is high albite microtwinned on the (010) composition plane, elongated in the major growth direction, [001]. Fiber morphology is non-polygonal with an average fiber diameter of 2000 Å perpendicular to c*. Fibers are separated by a non-crystalline residuum layer of approximately constant thickness (300–500 Å). Microtwinning relationships, as well as selected area diffraction (SAD) patterns, reveal both crystallographic and non-crystallographic branching with the former unexpectedly dominant.

scholarly journals Comparison of Rosin and Propolis Antimicrobials in Cellulose Acetate Fibers Against Staphylococcus aureus

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3756-3773
Keyword(s):  
Staphylococcus Aureus ◽  
Cellulose Acetate ◽  
Dermal Fibroblast ◽  
Quantitative Difference ◽  
Antibacterial Properties ◽  
Acetate Solution ◽  
Solvent Type ◽  
Colony Forming Units ◽  
High Concentrations ◽  
The Fourier Transform

The quantitative difference in the antibacterial response was measured for pine rosin and propolis against Staphylococcus aureus ATCC 12598. The activity was studied for fibrous networks that form entirely bio-based cellulose-acetate (CA) materials. The analysis considers the effects of bacterial input, additive dosage, solvent type, variation in preparation, as well as the effect of storage time. Based on the results, the electrospun network structure is dependent on the solvent and the concentration of rosin and propolis. Both rosin and propolis improved the cellulose acetate solution processability, yet they formed beads at high concentrations. Rosin and propolis created strong antibacterial properties when these material systems were immersed in the liquid for 24 h at room temperature. The response remained visible for a minimum of two months. The electrospun networks of water and DMAc solvent systems with 1 to 5 wt% rosin content were clearly more efficient (i.e., decrease of 4 to 6 logs in colony forming units per mL) than the propolis networks, even after two months. This efficiency is likely due to the high content of abietic acids present in the rosin, which is based on the Fourier transform infrared spectra. The results of the additional analysis and cell cultivation with dermal fibroblast cells indicated an impairing effect on skin tissue by the rosin at a 1 wt% concentration compared to the pure CA fibers.

scholarly journals Filtration Performance of Ultrathin Electrospun Cellulose Acetate Filters Doped with TiO2 and Activated Charcoal

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 557
Author(s):  
Roberta Orlando ◽  
Yilun Gao ◽  
Peter Fojan ◽  
Jinhan Mo ◽  
Alireza Afshari
Keyword(s):  
Pressure Drop ◽  
Cellulose Acetate ◽  
Removal Efficiency ◽  
Activated Charcoal ◽  
Charged Particles ◽  
Particle Sizes ◽  
Acetate Solution ◽  
Electrospun Fibre ◽  
Filtration Performance ◽  
Composite Filter

Air filters are crucial components of a building ventilation system that contribute to improving indoor air quality, but they are typically associated with relatively high pressure drops. The purpose of the study is to evaluate the effect of additives on ultrathin electrospun filters, the pressure drop, and the particle removal efficiency of uniformly charged particles. The fibres were electrospun under optimised conditions that resulted in a fast-fabricating process due to the properties of the cellulose acetate solution. Different ultrathin electrospun fibre filters based on cellulose acetate (CA) were fabricated: a pure CA electrospun fibre filter, two filters based on CA fibres separately doped with activated charcoal (AC) and titanium dioxide (TiO2), respectively, and a composite filter where the two additives, AC and TiO2, were embedded between two CA fibres layers. The ultrathin filters exhibited a low pressure drop of between 63.0 and 63.8 Pa at a face velocity of 0.8 m s−1. The filtration performance of uniformly charged particles showed a removal efficiency above 70% for particle sizes between 0.3 and 0.5 μm for all filters, rising above 90% for larger particles between 1 and 10 μm, which translates to the average sizes of pollens and other allergenic contaminant particles. Due to the positive impact on the fibre morphology caused by the additives, the composite filter showed the highest filtration performance among the produced filters, reaching 82.3% removal efficiency towards smaller particles and a removal of up to 100% for particle sizes between 5 and 10 μm. Furthermore, cellulose acetate itself is not a source of microparticles and is fully biodegradable compared to other polymers commonly used for filters. These ultrathin electrospun filters are expected to be practical in applications for better building environments.

scholarly journals CONFIGURATION OF A FILAMENTOUS NETWORK IN THE AXOPLASM OF THE SQUID (LOLIGO PEALII L.) GIANT NERVE FIBER

1969 ◽  
Vol 43 (3) ◽  
pp. 480-505 ◽  
Author(s):  
J. Metuzals
Keyword(s):  
Nerve Fiber ◽  
Protein Structures ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Uranyl Acetate ◽  
Nerve Fibers ◽  
Acetate Solution ◽  
Thin Sections ◽  
Resolution Electron ◽  
Specific Affinity

High-resolution electron microscopy is integrated with physicochemical methods in order to investigate the following preparations of the giant nerve fibers of the squid (Loligo pealii L.): (1) Thin sections of fibers fixed in four different fixatives; (2) fresh axoplasm stained negatively in solutions of different pH and composition; (3) chemically isolated threadlike elements of the axoplasm. A continuous, three-dimensional network can be identified in all these preparations of the axoplasm. The network is composed of coiled or looped unit-filaments ∼30 A wide. The unit-filaments are intercoiled in strands ∼ 70–250 A wide. The strands are oriented longitudinally in the axoplasm, often having a sinuous course and cross-associations. Microtubules are surrounded by intercoiled unit-filaments and filamentous strands. Calcium ions cause loosening and disintegration of the network configuration. UO2++ ions of a 1% uranyl acetate solution at pH 4.4 display a specific affinity for filamentous protein structures of the squid giant nerve fiber axoplasm, segregating the filamentous elements of the axoplasm in a coiled, threadlike preparation. The uranyl ions combine probably with the carboxyl groups of the main amino acids of the protein—glutamic and aspartic acids. It is proposed that by coiling/decoiling and folding/unfolding of the unit-filaments, shifts in physicochemical properties of the axoplasm are maintained.

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