Comparative toxicity of nano-ZnO and bulk ZnO suspensions to zebrafish and the effects of sedimentation, ˙OH production and particle dissolution in distilled water

Abstract In the present work, Bisphenol-A Glycidyl Methacrylate / Triethylene Glycol Dimethylacrylate based dental composites filled with 0-30 wt.% silane treated nano-ZnO were fabricated and tested for their dynamic mechanical properties. Samples were kept in each of three different mediums such as cold drink, distilled water and saliva for 7 days. The dynamic mechanical properties such as storage modulus, loss modulus and Tan delta were evaluated and compared for each composite under different conditions. The finding of results indicated that on adding 30 wt.% nano-ZnO, the storage modulus was increased by 109% in case of post cured, 120% in case of cold drink, 125% in case of artificial saliva but decreased by 70% in case of distilled water. The loss modulus was increased by 175% in case of post cured, 30% in case of cold drink, 50% in case of artificial saliva but decreased by 50% in case of distilled water. Further, minimum value of storage modulus was reported in case of distilled water medium followed by cold drink and then artificial saliva. Also, cold drink seems to be better medium than distilled water in terms of dynamic mechanical properties of dental composite. Graphical abstract Variation of storage modulus of sample kept in artificial saliva for 7 days Addition of 30 wt.% nano-ZnO increased the storage modulus by 109% in case of post cured, 120% in case of cold drink, 125% in case of artificial saliva but decreased by 70% in case of distilled water. Addition of 30 wt.% nano-ZnO increased the loss modulus by 175% in case of post cured, 30% in case of cold drink, 50% in case of artificial saliva but decreased by 50% in case of distilled water. Immersion of sample in each medium led to decrease in storage modulus but increase in Tan delta. Further, minimum value of storage modulus was reported in case of distilled water medium followed by cold drink and then artificial saliva. Cold drink seems to be better medium than distilled water in terms of dynamic mechanical properties of dental composite.

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Biophysical Measurement of Molecular Weight of Foot-and-Mouth Disease RNA Fragments

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051323 ◽

1974 ◽

Vol 32 ◽

pp. 262-263

Author(s):

Sydney S. Breese ◽

Howard L. Bachrach

Keyword(s):

Chemical Properties ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Distilled Water ◽

Bovine Plasma ◽

Mouth Disease Virus ◽

Foot And Mouth ◽

Carbon Coated ◽

Rna Fragments ◽

Physical And Chemical

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.

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Freeze-fracture, freeze-etch complementary pairs of virus-infected cells reveal value of etching even when relatively high concentrations of cryoprotectants are used

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081541 ◽

1978 ◽

Vol 36 (2) ◽

pp. 136-137

Author(s):

Russell L. Steere ◽

Eric F. Erbe

Keyword(s):

Plant Tissue ◽

Phosphate Buffer ◽

Infected Plant ◽

Freeze Fracture ◽

Distilled Water ◽

Virus Infected Plant ◽

Infected Cells ◽

High Concentrations

It has been assumed by many involved in freeze-etch or freeze-fracture studies that it would be useless to etch specimens which were cryoprotected by more than 15% glycerol. We presumed that the amount of cryoprotective material exposed at the surface would serve as a contaminating layer and prevent the visualization of fine details. Recent unexpected freeze-etch results indicated that it would be useful to compare complementary replicas in which one-half of the frozen-fractured specimen would be shadowed and replicated immediately after fracturing whereas the complement would be etched at -98°C for 1 to 10 minutes before being shadowed and replicated.Standard complementary replica holders (Steere, 1973) with hinges removed were used for this study. Specimens consisting of unfixed virus-infected plant tissue infiltrated with 0.05 M phosphate buffer or distilled water were used without cryoprotectant. Some were permitted to settle through gradients to the desired concentrations of different cryoprotectants.

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Comparison of Acrylamide and Agar Gels by Freeze-Etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080456 ◽

1977 ◽

Vol 35 ◽

pp. 606-607

Author(s):

Russell L. Steere ◽

Eric F. Erbe

Keyword(s):

Electron Microscope ◽

Sodium Hydroxide ◽

Sodium Hypochlorite ◽

Chromic Acid ◽

Distilled Water ◽

Thin Sheets ◽

Acid Cleaning ◽

Agar Gels ◽

Freeze Etching ◽

Water Cut

Thin sheets of acrylamide and agar gels of different concentrations were prepared and washed in distilled water, cut into pieces of appropriate size to fit into complementary freeze-etch specimen holders (1) and rapidly frozen. Freeze-etching was accomplished in a modified Denton DFE-2 freeze-etch unit on a DV-503 vacuum evaporator.* All samples were etched for 10 min. at -98°C then re-cooled to -150°C for deposition of Pt-C shadow- and C replica-films. Acrylamide gels were dissolved in Chlorox (5.251 sodium hypochlorite) containing 101 sodium hydroxide, whereas agar gels dissolved rapidly in the commonly used chromic acid cleaning solutions. Replicas were picked up on grids with thin Foimvar support films and stereo electron micrographs were obtained with a JEM-100 B electron microscope equipped with a 60° goniometer stage.Characteristic differences between gels of different concentrations (Figs. 1 and 2) were sufficiently pronounced to convince us that the structures observed are real and not the result of freezing artifacts.

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Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080407 ◽

1977 ◽

Vol 35 ◽

pp. 596-597

Author(s):

E. Keyhani

Keyword(s):

Plasma Membrane ◽

Candida Utilis ◽

Synthetic Medium ◽

Freeze Fracture ◽

Translational Diffusion ◽

Yeast Cells ◽

Distilled Water ◽

Intramembrane Particles ◽

The Matrix ◽

Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

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Variations in Surface Textures of Quartz Sand using Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069466 ◽

1970 ◽

Vol 28 ◽

pp. 494-495

Author(s):

Eugene J. Amaral

Keyword(s):

Electron Microscopy ◽

Glass Industry ◽

Glass Slide ◽

Distilled Water ◽

Early Paleozoic ◽

Secondary Effects ◽

Surface Textures ◽

High Silica ◽

Sand Deposit ◽

The U.S

Examination of sand grain surfaces from early Paleozoic sandstones by electron microscopy reveals a variety of secondary effects caused by rock-forming processes after final deposition of the sand. Detailed studies were conducted on both coarse (≥0.71mm) and fine (=0.25mm) fractions of St. Peter Sandstone, a widespread sand deposit underlying much of the U.S. Central Interior and used in the glass industry because of its remarkably high silica purity.The very friable sandstone was disaggregated and sieved to obtain the two size fractions, and then cleaned by boiling in HCl to remove any iron impurities and rinsed in distilled water. The sand grains were then partially embedded by sprinkling them onto a glass slide coated with a thin tacky layer of latex. Direct platinum shadowed carbon replicas were made of the exposed sand grain surfaces, and were separated by dissolution of the silica in HF acid.

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Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006756x ◽

1970 ◽

Vol 28 ◽

pp. 114-115

Author(s):

P. A. Madden ◽

W. R. Anderson

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Freeze Drying ◽

Room Temperature ◽

Secondary Electron ◽

Distilled Water ◽

Freeze Dried ◽

Silver Paint ◽

To Come ◽

Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

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High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066267 ◽

1971 ◽

Vol 29 ◽

pp. 442-443

Author(s):

Russell L. Steere

Keyword(s):

High Resolution ◽

Cardiac Muscle ◽

Electron Micrographs ◽

Chromic Acid ◽

Freeze Fracture ◽

Distilled Water ◽

Fine Scale ◽

Acid Cleaning ◽

Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

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