Solutions to the Problem of Substitution of ERL 4221 for Vinyl Cyclohexene Dioxide in Spurr Low Viscosity Embedding Formulations

Spurr low viscosity embedding medium was introduced in 1969 and used vinyl cyclohexene dioxide (VCD or ERL 4206) as the low viscosity epoxy resin together with nonenyl succinic anhydride (NSA), the flexibilizer DER 736, and the accelerator dimethylaminoethanol (DMAE or S-1). This low viscosity formulation has been used extensively for embedding plant materials, microrganisms and other difficult specimens. Over the years numerous concerns about the toxicity and carcinogenicity of VCD have been raised. VCD (Fig. 1) was finally removed from the market in 2005 and replaced with ERL 4221 (Fig. 2), a cyclic epoxide with a higher molecular weight and higher viscosity. Vendors instructed that ERL 4221 be substituted for VCD at the same rates as used in the original Spurr formulation. This direct substitution resulted in a more viscous resin and blocks were extremely hard and brittle and lacked the sectioning qualities of the original formulation. Vendors then suggested modifications to the dehydration schedule and reductions in the amount of DMAE to improve the quality of the blocks.

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A Simplified Method for Formulation of Epoxy Resin Embedding Media

Microscopy Today ◽

10.1017/s1551929500058703 ◽

2006 ◽

Vol 14 (5) ◽

pp. 50-51 ◽

Cited By ~ 2

Author(s):

E. Ann Ellis

Keyword(s):

Molecular Weight ◽

Epoxy Resin ◽

Molar Ratio ◽

Molecular Weights ◽

Molar Ratios ◽

Low Viscosity ◽

Simplified Method ◽

Beam Stability ◽

Embedding Medium

In a recent paper on the revised formulation of Spurr low viscosity embedding medium with ERL 4221 the importance of maintaining an appropriate anhydride:epoxide (A:E) ratio was discussed. By understanding a few simple concepts about epoxy resin formulations and setting up a formulation table it is possible to create new resin mixtures with good sectioning properties and other desirable properties such as decreased viscosity and increased beam stability.Before starting a formulation you need to know the molecular weight of the anhydride and the WPE (weight per epoxide equivalent) of the epoxy resin component. The molecular weights and WPEs are usually printed on the bottle or can be obtained from the vendor. An A:E ratio of 0.7:1.0 -1.0:1.0 is used for most biological specimens. Increasing the A:E ratio results in a harder block; decreasing the A:E ratio results in a softer block. Table 1 shows a basic formulation spreadsheet where the molecular weights of the anhydrides and the WPEs of the epoxy resin components can be entered. The A:E ratio is entered under the anhydride for the molar ratio and the molar ratios of the epoxy components are entered under the epoxy components. The calculations are done as shown in each column and row.

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Rapid Infiltration of Biological Tissues Utilizing n-Hexenyl Succinic Anhydride (HXSA)/Vinyl Cyclohexene Dioxide (VCD), An Ultra-Low Viscosity Embedding Medium.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091718 ◽

1976 ◽

Vol 34 ◽

pp. 346-347 ◽

Cited By ~ 3

Author(s):

Joe A. Mascorro ◽

Margaret W. Ladd ◽

Robert D. Yates

Keyword(s):

Electron Microscopy ◽

Succinic Anhydride ◽

Biological Tissues ◽

Carbon Chain ◽

Minimum Time ◽

Joint Symposium ◽

Low Viscosity ◽

Embedding Medium ◽

Short Carbon

HXSA/VCD recently was introduced as an ultra-low viscosity embedding medium for biological electron microscopy (Mascorro et al., TSEM/LSEM Joint Symposium Proceedings, In Press, 1976). The medium utilizes a newly developed short carbon chain anhydride (HXSA) in combination with components of known low viscosities. The completed medium exhibits a markedly low viscosity (20 ±1 cps d 25°C) which facilitates rapid and complete infiltration in minimum time. The components and preparation of the medium are as follows:A small amount of standard mix includes 5 grams VCD, 10 grams HXSA, 0.75 gram Araldite RD-2 and 0.15 gram DMAE, combined gravimetrically. Components are drawn by syringe and dispensed into a dry beaker placed on a Mettler balance. The fluid nature of the medium allows precise measuring.

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A low-viscosity epoxy resin embedding medium for electron microscopy

Journal of Ultrastructure Research ◽

10.1016/s0022-5320(69)90033-1 ◽

1969 ◽

Vol 26 (1-2) ◽

pp. 31-43 ◽

Cited By ~ 8642

Author(s):

Arthur R. Spurr

Keyword(s):

Electron Microscopy ◽

Epoxy Resin ◽

Low Viscosity ◽

Embedding Medium

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The Application of Ultra-Thin Sectioning Techniques to Non-Biological Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101402 ◽

1968 ◽

Vol 26 ◽

pp. 332-333

Author(s):

C. F. Oster

Keyword(s):

Biological Sciences ◽

Epoxy Resin ◽

Cross Sections ◽

Biological Samples ◽

Industrial Applications ◽

Photographic Film ◽

Silver Particles ◽

Thin Sectioning ◽

Embedding Medium

Although ultra-thin sectioning techniques are widely used in the biological sciences, their applications are somewhat less popular but very useful in industrial applications. This presentation will review several specific applications where ultra-thin sectioning techniques have proven invaluable.The preparation of samples for sectioning usually involves embedding in an epoxy resin. Araldite 6005 Resin and Hardener are mixed so that the hardness of the embedding medium matches that of the sample to reduce any distortion of the sample during the sectioning process. No dehydration series are needed to prepare our usual samples for embedding, but some types require hardening and staining steps. The embedded samples are sectioned with either a prototype of a Porter-Blum Microtome or an LKB Ultrotome III. Both instruments are equipped with diamond knives.In the study of photographic film, the distribution of the developed silver particles through the layer is important to the image tone and/or scattering power. Also, the morphology of the developed silver is an important factor, and cross sections will show this structure.

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Crystallization of Isotactic Poly(propylene) in Solution as Followed by Slow Calorimetry

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19951905 ◽

1995 ◽

Vol 60 (11) ◽

pp. 1905-1924 ◽

Cited By ~ 4

Author(s):

Hong Phuong-Nguyen ◽

Geneviève Delmas

Keyword(s):

Molecular Weight ◽

Crystal Growth ◽

High Temperature ◽

Heat Of Fusion ◽

Complete Dissolution ◽

Polymer Molecular Weight ◽

Solvent Quality ◽

Temperature Ramp ◽

Poly Propylene

Dissolution, crystallization and second dissolution traces of isotactic poly(propylene) have been obtained in a slow temperature ramp (3 K h-1) with the C80 Setaram calorimeter. Traces of phase-change, in presence of solvent, are comparable to traces without solvent. The change of enthalpy on heating or cooling, ∆Htotal, over the 40-170 °C temperature range, is the sum of two contributions, ∆HDSC and ∆Hnetwork. The change ∆HDSC is the usual heat obtained in a fast temperature ramp and ∆Hnetwork is associated with a physical network whose disordering is slow and subject to superheating due to strain. When dissolution is complete, ∆Htotal is equal to ∆H0, the heat of fusion of perfect crystals. The values of ∆Htota for nascent and recrystallized samples are compared. Dissolution is the tool to evaluate the quality of the crystals. The repartition of ∆Htotal, into the two endotherms, reflects the quality of crystals. The crystals grown more rapidly have a higher fraction of network crystals which are stable at high T in the solvents. A complete dissolution, i.e. a high temperature (170 °C or more) is necessary to obtain good crystals. The effect of concentration, polymer molecular weight and solvent quality on crystal growth is analyzed.

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Late-Maturity Alpha-Amylase in Wheat (Triticum aestivum) and Its Impact on Fresh White Sauce Qualities

Foods ◽

10.3390/foods10020201 ◽

2021 ◽

Vol 10 (2) ◽

pp. 201

Author(s):

Galex K. S. Neoh ◽

Mark J. Dieters ◽

Keyu Tao ◽

Glen P. Fox ◽

Phuong T. M. Nguyen ◽

...

Keyword(s):

Grain Filling ◽

Drastic Reduction ◽

Product Usage ◽

Low Viscosity ◽

Pasting Characteristics ◽

Late Maturity ◽

Semi Solid ◽

New Applications ◽

White Sauce

When wheat experiences a cold-temperature ‘shock’ during the late stage of grain filling, it triggers the abnormal synthesis of late-maturity α-amylase (LMA). This increases the enzyme content in affected grain, which can lead to a drastic reduction in falling number (FN). By commercial standards, a low FN is taken as an indication of inferior quality, deemed unsuitable for end-product usage. Hence, LMA-affected grains are either rejected or downgraded to feed grade at the grain receiving point. However, previous studies have found no substantial correlation between low FN-LMA and bread quality. The present study extends previous investigations to semi-solid food, evaluating the physical quality of fresh white sauce processed from LMA-affected flour. Results show that high-LMA flours had low FNs and exhibited poor pasting characteristics. However, gelation occurred in the presence of other components during fresh white sauce processing. This demonstrates that LMA-affected flours may have new applications in low-viscosity products.

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An Effective Method for Preparation of Liquid Phosphoric Anhydride and Its Application in Flame Retardant Epoxy Resin

Materials ◽

10.3390/ma14092205 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2205

Author(s):

Qian Li ◽

Yujie Li ◽

Yifan Chen ◽

Qiang Wu ◽

Siqun Wang

Keyword(s):

Flame Retardant ◽

Epoxy Resin ◽

Epoxy Resins ◽

Oxygen Index ◽

Decomposition Temperature ◽

Ease Of Use ◽

Limiting Oxygen Index ◽

Good Thermal Stability ◽

Low Viscosity ◽

The Impact

A novel liquid phosphorous-containing flame retardant anhydride (LPFA) with low viscosity was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and methyl tetrahydrophthalic anhydride (MeTHPA) and further cured with bisphenol-A epoxy resin E-51 for the preparation of the flame retardant epoxy resins. Both Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR) measurements revealed the successful incorporation of DOPO on the molecular chains of MeTHPA through chemical reaction. The oxygen index analysis showed that the LPFA-cured epoxy resin exhibited excellent flame retardant performance, and the corresponding limiting oxygen index (LOI) value could reach 31.2%. The UL-94V-0 rating was achieved for the flame retardant epoxy resin with the phosphorus content of 2.7%. With the addition of LPFA, the impact strength of the cured epoxy resins remained almost unchanged, but the flexural strength gradually increased. Meanwhile, all the epoxy resins showed good thermal stability. The glass transition temperature (Tg) and thermal decomposition temperature (Td) of epoxy resin cured by LPFA decreased slightly compared with that of MeTHPA-cured epoxy resin. Based on such excellent flame retardancy, low viscosity at room temperature and ease of use, LPFA showed potential as an appropriate curing agent in the field of electrical insulation materials.

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