scholarly journals Synthesis of PMMA-HoVO4 nanocomposites by emulsifier-free emulsion polymerization: radical effects

2020 ◽  
Vol 38 (1) ◽  
pp. 143-150
Author(s):  
B. Bulbul ◽  
E.Y. Pekcaliskan ◽  
S. Beyaz
Keyword(s):  
Emulsion Polymerization ◽  
Room Temperature ◽  
The Other ◽  
Nanoparticle Dispersion ◽  
Emulsion System ◽  
Polymer Beads ◽  
Polymerization System ◽  
Infrared Spectral ◽  
New Material

AbstractPoly(methyl methacrylate)-holmium orthovanadate (PMMA-HoVO4) nanocomposites were synthesized using emulsifierfree emulsion polymerization system in two ways. In the first one, the HoVO4 nanoparticle dispersion was added to the emulsion system before or after polymerization start (in situ polymerization). In the other one, nanoparticle dispersion and polymeric latex were mixed together at room temperature (blending). Crystalline HoVO4 nanoparticles (about 60 nm) were synthesized by coprecipitation method. Three different composite latexes were synthesized by varying the potassium persulfate concentration and the time of HoVO4 nanoparticles addition. According to the dynamic light scattering analysis, the size of the polymer beads in the latexes is between 244.8 nm and 502.5 nm and the PDI values are in the range of 0.005 to 0.206. Infrared spectral analysis showed that HoVO4 caused some changes in the structure of the polymer. Luminescence measurements attempted to determine optical properties of the nanocomposites. The results have shown that HoVO4 nanoparticles do not protect their structure due to the reaction with persulfate radicals but that they enter the polymer beads and change the luminescence properties of the polymer forming a new material with different properties.

scholarly journals Efficient One-Step Immobilization of CaLB Lipase over MOF Support NH2-MIL-53(Al)

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 918
Author(s):  
Victoria Gascón-Pérez ◽  
Mayra Belen Jiménez ◽  
Asunción Molina ◽  
Rosa María Blanco ◽  
Manuel Sánchez-Sánchez
Keyword(s):  
Room Temperature ◽  
Metal Organic Framework ◽  
The Other ◽  
Synthetic Method ◽  
Enzyme Loading ◽  
Synthesis Time ◽  
Ph Values ◽  
Metal Organic ◽  
One Step

Metal-organic framework (MOF) materials possess the widest versatility in structure, composition, and synthesis procedures amongst the known families of materials. On the other hand, the extraordinary affinity between MOFs and enzymes has led to widely investigating these materials as platforms to support these catalytic proteins in recent years. In this work, the MOF material NH2-MIL-53(Al) has been tested as a support to immobilize by one-step methodology (in situ) the enzyme lipase CaLB from Candida antarctica by employing conditions that are compatible with its enzymatic activity (room temperature, aqueous solution, and moderate pH values). Once the nature of the linker deprotonating agent or the synthesis time were optimized, the MOF material resulted in quite efficient entrapping of the lipase CaLB through this in situ approach (>85% of the present enzyme in the synthesis media) while the supported enzyme retained acceptable activity (29% compared to the free enzyme) and had scarce enzyme leaching. The equivalent post-synthetic method led to biocatalysts with lower enzyme loading values. These results make clear that the formation of MOF support in the presence of the enzyme to be immobilized substantially improves the efficiency of the biocatalysts support for retaining the enzyme and limits their leaching.

In-Situ SEM/EBSP Analysis during Annealing in a Pure Aluminum Foil for Capacitor

2007 ◽  
Vol 539-543 ◽  
pp. 362-367
Author(s):  
Masakazu Kobayashi ◽  
Yoshimasa Takayama ◽  
Hajime Kato ◽  
Hiroyuki Toda
Keyword(s):  
Room Temperature ◽  
Pure Aluminum ◽  
Cube Texture ◽  
Industrial Process ◽  
Aluminum Foil ◽  
The Other ◽  
Final Annealing ◽  
Small Grains ◽  
Partial Annealing

In-situ SEM/EBSP analysis has been performed during the evolution of the cube texture in a pure aluminum foil. In general, foils for capacitor are manufactured in an industrial process of casting, homogenizing, hot rolling, cold rolling (CR), partial annealing (PA), additional rolling (AR) and final annealing (FA). The foil samples after CR or AR in the process were analyzed by the SEM/EBSP technique at a constant temperature which was step-heated repeatedly by 10-20K from a room temperature to 623K or 598K. In a CRed sample, cube ({001}<100>) grains begin to grow preferentially at 503K to cover the sample. On the other hand, in a sample subjected to PA at 503K and AR, cube grains coarsened rapidly and preferentially at more than 533K in contrast to other oriented small grains remaining their sizes. Further, intragranular misorientation analysis revealed that the misorientation, which corresponds to dislocation density or strain, was much smaller in cube grains than in S ({123}<634>) and Cu ({112}<111>) ones.

Preparation and Properties Analysis of Polyaniline/Nano-SrFe12O19 Composites with Different Morphologies

2009 ◽  
Vol 79-82 ◽  
pp. 1607-1610
Author(s):  
Qiao Ling Li ◽  
Cun Rui Zhang ◽  
Yun Ye
Keyword(s):  
Magnetic Properties ◽  
Emulsion Polymerization ◽  
In Situ Polymerization ◽  
Reaction System ◽  
System A ◽  
Magnetic Variation ◽  
Polymerization System ◽  
First Time ◽  
Polymerization Method

Polyaniline/nano-SrFe12O19 composites were prepared by in situ polymerization method for the first time. Rod-like and flower-like morphologies composites were synthesized in the phase of an emulsion polymerization system. It was found that the morphology of obtained PANI/nano-SrFe12O19 composites depended on the content of SrFe12O19 of the reaction system. A possible mechanism for the formation of the different morphologic composites had been proposed. The magnetic properties of the PANI/nano- SrFe12O19 composites were inspected by VSM. The possible mechanism for magnetic variation had been proposed in the paper.

Photoinitiated Emulsion Polymerization of P(MMA-co-DVB) Microspheres with Low Power Ultraviolet Light

2011 ◽  
Vol 194-196 ◽  
pp. 952-955
Author(s):  
Li Jun Tao ◽  
Feng Qiang Sun
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Methyl Methacrylate ◽  
Emulsion Polymerization ◽  
Room Temperature ◽  
Uv Light ◽  
Polymerization System ◽  
Scanning Electron ◽  
Ultraviolet Lamp

Poly (methyl methacrylate-co-divinylbenzene) [P(MMA-co-DVB)] microspheres were first synthesized by a simple photoinitiated emulsion polymerization methods. In this polymerization system, MMA, DVB, AIBN, isopropanol and hexahydrobenzene constituted the oil phase, SDS acted as the stabilizer and an 8 W Ultraviolet lamp was employed as the light source. Under the irradiation of the UV light, AIBN could be decomposed to produce radicals and initiate the polymerization of MMA to produce P(MMA-co-DVB) microspheres.The morphologies and structures of the products were characterized by Fourier transform infrared spectroscope (FTIR),size distribution, scanning electron microscope (SEM). The average diameters of the spheres increased with the content of DVB. The research may provide a quick, green and facile room-temperature approach to prepare polymer microspheres.

scholarly journals Benzoyl Peroxide Oxidation Route to the Synthesis of Solvent Soluble Polycarbazole

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Rajender Boddula ◽  
Palaniappan Srinivasan
Keyword(s):  
Thermal Stability ◽  
Emulsion Polymerization ◽  
Benzoyl Peroxide ◽  
Room Temperature ◽  
The Other ◽  
Solution Polymerization ◽  
Peroxide Oxidation ◽  
Polar Solvents ◽  
Amorphous Nature ◽  
First Time

Carbazole was oxidized by benzoyl peroxide in presence of p-toluenesulfonic acid to polycarbazole salt at room temperature for the first time. Polycarbazole salts were synthesized via solution and emulsion polymerization pathways. Polycarbazole bases were prepared by dedoping from polycarbazole salts. Formation of polycarbazoles was confirmed from infrared, electronic absorption and EDAX spectra. Polycarbazole salt was obtained in amorphous nature in semiconductor range (10−5 S/cm), which was found to be soluble in less and high polar solvents. Polycarbazole salt prepared by emulsion polymerization pathway showed mixture of shapes with microrod, sphere, and pores, whereas its corresponding base showed only micropores structure. On the other hand, polycarbazole salt and its corresponding base prepared by solution polymerization pathway showed flake-like morphology. Higher thermal stability was obtained for polycarbazole salt prepared by emulsion polymerization pathway than that of the salt prepared by solution polymerization pathway.

Dynamic Behavior of Twins In BaTiO3

1994 ◽  
Vol 357 ◽  
Author(s):  
Kalpana S. Katti ◽  
Mehmet Sarikaya
Keyword(s):  
Room Temperature ◽  
Mechanical Stability ◽  
The Other ◽  
Ferroelectric Transition ◽  
Transmission Electron ◽  
In Situ Heating ◽  
Lattice Planes ◽  
Microscopy Techniques ◽  
Dynamic Heating

AbstractThe most prominent lattice defects in barium titanate, i.e., twins on two distinct lattice planes { 111 } and { 110 }, were characterized using dynamic transmission electron microscopy techniques in the image and diffraction modes. In-situ heating experiments from room temperature up to 130°C and then cooling down to -168°C reveal a dependence of { 110 } twins on ferroelectric transition. On the other hand, { 111 } twins are found to be completely stable through the ferroelectric transition and exist in all phases. Streaking is observed in the diffraction spots leading to an estimation of { 1111 twin wall thickness to be about 10Å while no such streaking was observed corresponding to { 1101 twins. Based on these observations and the behavior of the twin boundaries under dynamic heating cycles, an estimate of the twin wall energies indicates that { 111 } walls have three orders of magnitude higher energy than that of { 110 } walls which explains their relative thermal and mechanical stability.

A very rapid in situ Kikuchi technique to determine relative crystal misorientation

1988 ◽  
Vol 46 ◽  
pp. 830-831
Author(s):  
J. I. Bennetch
Keyword(s):  
Electron Beam ◽  
Analytical Techniques ◽  
Superplastic Forming ◽  
The Other ◽  
Kikuchi Pattern ◽  
Kikuchi Line ◽  
Line Analysis

In a recent study of the superplastic forming (SPF) behavior of certain Al-Li-X alloys, the relative misorientation between adjacent (sub)grains proved to be an important parameter. It is well established that the most accurate way to determine misorientation across boundaries is by Kikuchi line analysis. However, the SPF study required the characterization of a large number of (sub)grains in each sample to be statistically meaningful, a very time-consuming task even for comparatively rapid Kikuchi analytical techniques.In order to circumvent this problem, an alternate, even more rapid in-situ Kikuchi technique was devised, eliminating the need for the developing of negatives and any subsequent measurements on photographic plates. All that is required is a double tilt low backlash goniometer capable of tilting ± 45° in one axis and ± 30° in the other axis. The procedure is as follows. While viewing the microscope screen, one merely tilts the specimen until a standard recognizable reference Kikuchi pattern is centered, making sure, at the same time, that the focused electron beam remains on the (sub)grain in question.

Otoconia perfect/imperfect crystals

1994 ◽  
Vol 52 ◽  
pp. 42-43
Author(s):  
César D. Fermin ◽  
Dale Martin
Keyword(s):  
Image Processing ◽  
Room Temperature ◽  
Phosphotungstic Acid ◽  
Gallus Domesticus ◽  
Crystal Matrix ◽  
Organic Templates ◽  
Image Processing Algorithms ◽  
Processing Algorithms ◽  
Diffraction Patterns

Otoconia of higher vertebrates are interesting biological crystals that display the diffraction patterns of perfect crystals (e.g., calcite for birds and mammal) when intact, but fail to produce a regular crystallographic pattern when fixed. Image processing of the fixed crystal matrix, which resembles the organic templates of teeth and bone, failed to clarify a paradox of biomineralization described by Mann. Recently, we suggested that inner ear otoconia crystals contain growth plates that run in different directions, and that the arrangement of the plates may contribute to the turning angles seen at the hexagonal faces of the crystals.Using image processing algorithms described earlier, and Fourier Transform function (2FFT) of BioScan Optimas®, we evaluated the patterns in the packing of the otoconia fibrils of newly hatched chicks (Gallus domesticus) inner ears. Animals were fixed in situ by perfusion of 1% phosphotungstic acid (PTA) at room temperature through the left ventricle, after intraperitoneal Nembutal (35mg/Kg) deep anesthesia. Negatives were made with a Hitachi H-7100 TEM at 50K-400K magnifications. The negatives were then placed on a light box, where images were filtered and transferred to a 35 mm camera as described.

In Situ Localization of PPAR Gamma and Uncoupling Protein in Mouse Embryo Sections Using Digoxigenin-Labeled Riboprobes

1996 ◽  
Vol 54 ◽  
pp. 32-33
Author(s):  
C. Jennermann ◽  
S. A. Kliewer ◽  
D. C. Morris
Keyword(s):  
Alkaline Phosphatase ◽  
Room Temperature ◽  
Uncoupling Protein ◽  
Ppar Gamma ◽  
Nuclear Hormone Receptor ◽  
Full Length ◽  
Northern Analysis ◽  
Peroxisome Proliferator

Peroxisome proliferator-activated receptor gamma (PPARg) is a member of the nuclear hormone receptor superfamily and has been shown in vitro to regulate genes involved in lipid metabolism and adipocyte differentiation. By Northern analysis, we and other researchers have shown that expression of this receptor predominates in adipose tissue in adult mice, and appears first in whole-embryo mRNA at 13.5 days postconception. In situ hybridization was used to find out in which developing tissues PPARg is specifically expressed.Digoxigenin-labeled riboprobes were generated using the Genius™ 4 RNA Labeling Kit from Boehringer Mannheim. Full length PPAR gamma, obtained by PCR from mouse liver cDNA, was inserted into pBluescript SK and used as template for the transcription reaction. Probes of average size 200 base pairs were made by partial alkaline hydrolysis of the full length transcripts. The in situ hybridization assays were performed as described previously with some modifications. Frozen sections (10 μm thick) of day 18 mouse embryos were cut, fixed with 4% paraformaldehyde and acetylated with 0.25% acetic anhydride in 1.0M triethanolamine buffer. The sections were incubated for 2 hours at room temperature in pre-hybridization buffer, and were then hybridized with a probe concentration of 200μg per ml at 70° C, overnight in a humidified chamber. Following stringent washes in SSC buffers, the immunological detection steps were performed at room temperature. The alkaline phosphatase labeled, anti-digoxigenin antibody and detection buffers were purchased from Boehringer Mannheim. The sections were treated with a blocking buffer for one hour and incubated with antibody solution at a 1:5000 dilution for 2 hours, both at room temperature. Colored precipitate was formed by exposure to the alkaline phosphatase substrate nitrobluetetrazoliumchloride/ bromo-chloroindlylphosphate.

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

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