Analysis of bacteriophage inactivation and its attenuation by adsorption onto colloidal particles by batch agitation techniques

1999 ◽  
Vol 45 (1) ◽  
pp. 9-17 ◽  
Author(s):  
P Rossi ◽  
M Aragno
Keyword(s):  
Liquid Medium ◽  
Colloidal Particles ◽  
Dynamic Equilibrium ◽  
Virus Population ◽  
Environmental Consequence ◽  
Clay Particles ◽  
Adsorption Mechanisms ◽  
Low Concentrations ◽  
Colloidal Clay ◽  
Phage T7

A batch agitation technique was designed to specify the different parameters that influence the inactivation and adsorption mechanisms of viruses in water. The advantage of this method over the classical procedures is that the kinetic reactions of the different subfractions of the virus population can be described simultaneously. A first set of experiments with phage T7 showed that this phage is rapidly inactivated in a constantly agitated liquid medium. This inactivation rate is highly influenced by temperature, but variation of the pH (from 5 to 9) and increase in salt concentration have no effect on it. The addition of colloidal clay particles (CCPs) of montmorillonite and attapulgite into the liquid medium considerably modifies this behavior, even at very low concentrations (0.025 mg/mL). The experiments show that the viruses react quickly with the particles and that bonding is not permanent. Viruses establish a dynamic equilibrium, which is strongly dependent on physicochemical parameters such as pH, ionic concentrations, and the presence of proteins or protein hydrolysates. A major environmental consequence is that the presence of CCPs seems to effectively protect the coliphage T7 from rapid inactivation.Key words: bacteriophage T7, viruses, inactivation and adsorption kinetics, colloidal particles, protective effect.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Effects of Some Spices on Acid Production by Starter Cultures

1979 ◽  
Vol 42 (7) ◽  
pp. 572-576 ◽  
Author(s):  
LAURA L. ZAIKA ◽  
JOHN C. KISSINGER
Keyword(s):  
Liquid Medium ◽  
Lactobacillus Plantarum ◽  
Acid Production ◽  
Bacterial Population ◽  
Starter Culture ◽  
Starter Cultures ◽  
Red Pepper ◽  
Bacterial Counts ◽  
Low Concentrations ◽  
High Concentrations

Ginger, red pepper, mustard, mace, cinnamon and clove were examined to determine their effects on growth of and acid production by a starter culture containing Lactobacillus plantarum and Pediococcus cerevisiae in a liquid medium. At 4, 8, and 12 g/l levels all spices except clove stimulated acid production by the starter bacteria but did not stimulate increases in bacterial population. Clove was inhibitory to the starter bacteria at and above the 4 g/l level, but low concentrations (0.5 – 2.0 g/l) stimulated acid production. High concentrations of cinnamon (8 and 12 g/l) delayed acid production, but bacterial counts were similar to those of the control.

scholarly journals Surface and interfacial tensions of aqueous dispersions of charged colloidal (clay) particles

1994 ◽  
Vol 72 (9) ◽  
pp. 1915-1920 ◽  
Author(s):  
Laurier L. Schramm ◽  
Loren G. Hepler
Keyword(s):  
Interfacial Tension ◽  
Pure Water ◽  
Surface Tensions ◽  
Flow Rates ◽  
Aqueous Dispersions ◽  
Clay Particles ◽  
Interfacial Tensions ◽  
Aqueous Suspensions ◽  
Colloidal Clay ◽  
Effect Of Surface

We have measured (du Nouy ring and maximum bubble pressure methods) suspension–air surface tensions of aqueous suspensions of montmorillonite and have observed that these surface tensions are larger than those of pure water at the same temperatures. Further measurements have shown that dispersed montmorillonite also increases the suspension–toluene interfacial tension compared with that of pure water–toluene. Similar measurements on aqueous suspensions of kaolinite have yielded suspension–air interfacial tensions with uncertainties as large as the observed (small) effect, and also shown that the suspension–toluene interfacial tension is decreased (opposite to the effect of montmorillonite) by amounts larger than the experimental uncertainties. Measurements of maximum bubble pressures at different flow rates have provided information about the effect of surface age on observed surface tensions.

Manipulation of Organic and Inorganic Colloidal Particles by Dielectrophoretic Forces

2007 ◽  
Author(s):  
Ramazan Asmatulu ◽  
Dennis Siginer
Keyword(s):  
Liquid Medium ◽  
Electric Fields ◽  
Colloidal Particles ◽  
Dielectrophoretic Force ◽  
Inorganic Particles ◽  
Ac Electric Fields ◽  
The Creation ◽  
Manipulation Process

Recently, manipulation of the micro and nanoscale objects has been of great interest in verity of engineering and scientific areas. Dielectrophoretic force (DEP) induced technique is predominantly used in the manipulation process in a liquid medium. The phenomenon behind DEP involves the creation of electric forces on particles to generate momentum in nonuniform electric fields, usually coming from AC electric fields. In the present study, we will discuss about the effects of DEP for the manipulation of organic and inorganic particles at micro and nanoscale in detail.

Destabilization of montmorillonite suspensions by Ca2+ and succinoglycan

Clay Minerals ◽  
2003 ◽  
Vol 38 (2) ◽  
pp. 173-185 ◽  
Author(s):  
J . Labille ◽  
F. Thomas ◽  
I . Bihannic ◽  
C. Santaella
Keyword(s):  
Tensile Strength ◽  
Confocal Microscopy ◽  
Laser Diffraction ◽  
Time Resolved ◽  
Clay Particles ◽  
Bridging Flocculation ◽  
Colloidal Clay

AbstractAggregation of colloidal clay particles (Na-montmorillonite) by CaCl2 and anionic polysaccharide (succinoglycan) in turbulent conditions was investigated using time-resolved size measurements by laser diffraction on diluted (50 mg l –1) and stirred suspensions. Excess of Ca2+ ions promotes coagulation of the clay, reducing interparticle repulsions, and allows adsorption of succinoglycan, inducing bridging flocculation. Growth/breakage cycles, characteristic of the turbulent conditions, cause the macromolecules to be incorporated in the innermost of the flocs, where the morphological units are shown by confocal microscopy to be the micrometric Ca-clay particles. Such incorporation results in an increased floc tensile strength, depending on the amount of macromolecules adsorbed, with a maximum at polysaccharide concentrations of 2 wt.% with respect to clay mass.

scholarly journals Heteroagglomeration of nanosilver with colloidal SiO2 and clay

2017 ◽  
Vol 14 (1) ◽  
pp. 1 ◽  
Author(s):  
Sébastien Maillette ◽  
Caroline Peyrot ◽  
Tapas Purkait ◽  
Muhammad Iqbal ◽  
Jonathan G. C. Veinot ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Polyacrylic Acid ◽  
Natural Waters ◽  
Colloidal Particles ◽  
Colloidal Stability ◽  
Analytical Techniques ◽  
Dark Field ◽  
Correlation Spectroscopy ◽  
Colloidal Clay ◽  
High Concentrations

Environmental contextThe fate of nanomaterials in the environment is related to their colloidal stability. Although numerous studies have examined their homoagglomeration, their low concentration and the presence of high concentrations of natural particles implies that heteroagglomeration rather than homoagglomeration is likely to occur under natural conditions. In this paper, two state-of-the art analytical techniques were used to identify the conditions under which nanosilver was most likely to form heteroagglomerates in natural waters. AbstractThe environmental risk of nanomaterials will depend on their persistence, mobility, toxicity and bioaccumulation. Each of these parameters is related to their fate (especially dissolution, agglomeration). The goal of this paper was to understand the heteroagglomeration of silver nanoparticles in natural waters. Two small silver nanoparticles (nAg, ~3nm; polyacrylic acid- and citrate-stabilised) were covalently labelled with a fluorescent dye and then mixed with colloidal silicon oxides (SiO2, ~18.5nm) or clays (~550nm SWy-2 montmorillonite). Homo- and heteroagglomeration of the nAg were first studied in controlled synthetic waters that were representative of natural fresh waters (50μg Ag L–1; pH 7.0; ionic strength 10–7 to 10–1 M Ca) by following the sizes of the nAg by fluorescence correlation spectroscopy. The polyacrylic acid-coated nanosilver was extremely stable under all conditions, including in the presence of other colloids and at high ionic strengths. However, the citrate-coated nanosilver formed heteroaggregates in presence of both colloidal SiO2 and clay particles. Nanoparticle surface properties appeared to play a key role in controlling the physicochemical stability of the nAg. For example, the polyacrylic acid stabilized nAg-remained extremely stable in the water column, even under conditions for which surrounding colloidal particles were agglomerating. Finally, enhanced dark-field microscopy was then used to further characterise the heteroagglomeration of a citrate-coated nAg with suspensions of colloidal clay, colloidal SiO2 or natural (river) water.

Viscosities of dilute aqueous suspensions of montmorillonite and kaolinite clays

1986 ◽  
Vol 64 (9) ◽  
pp. 1919-1924 ◽  
Author(s):  
Kim L. Kasperski ◽  
Charles T. Hepler ◽  
Loren G. Hepler
Keyword(s):  
Einstein Equation ◽  
Colloidal Particles ◽  
Effect Of Temperature ◽  
Previous Knowledge ◽  
Swelling Clay ◽  
Clay Particles ◽  
Previous Evidence ◽  
Aqueous Suspensions ◽  
Increasing Temperature

We have measured viscosities and densities of dilute aqueous suspensions of Na-kaolinite (25 °C), of Na-montmorillonite (25–55 °C), and of mixtures of Na-kaolinite/Na-montmorillonite (25 °C). Results of the measurements at 25 °C have been analyzed in terms of the Einstein equation with conclusions that are consistent with previous knowledge that colloidal particles of these clays are non-spherical and that montmorillonite is a swelling clay. Viscosities of mixed clay systems are nearly consistent with a simple additivity model; the small non-additivities are in accord with previous evidence that relatively small montmorillonite particles are adsorbed on the surface of relatively large kaolinite particles. The effect of temperature on the viscosities of suspensions of montmorillonite is consistent with the idea that aggregation of clay particles diminishes with increasing temperature.

Effect of antibiotics on cell proliferation in the Closterium peracerosum-strigosum-littorale complex (Charophyceae, Chlorophyta)

Biologia ◽  
2008 ◽  
Vol 63 (6) ◽  
Author(s):  
Jun Abe ◽  
Kaori Sakayori ◽  
Hiroyuki Sekimoto
Keyword(s):  
Cell Proliferation ◽  
Liquid Medium ◽  
Inhibitory Concentration ◽  
Solid Medium ◽  
Marker Genes ◽  
Hygromycin B ◽  
Selectable Marker Genes ◽  
Kanamycin Sulfate ◽  
Low Concentrations ◽  
Selection Of

AbstractThe effects of several antibiotics on the proliferation of cells of the Closterium peracerosum-strigosum-littorale complex, a unicellular charophycean alga, were examined. When cells were cultured on solid medium containing hygromycin B and phleomycin the proliferation of cells was inhibited at low concentrations of these antibiotics, with a minimum inhibitory concentration of 5.0 and 0.2 µg/mL, respectively. By contrast, kanamycin sulfate was less effective at concentrations up to 50 µg/mL. When cells were incubated in liquid medium containing hygromycin B and phleomycin, cell proliferation was severely inhibited at concentrations of 5.0 and 0.01 µg/mL, respectively. It is concluded that hygromycin B and phleomycin are highly effective for inhibiting the proliferation of C. psl. complex both on solid and in liquid medium and thus are useful for the selection of the cells transformed by selectable marker genes.

OBSERVATION OF CYTOCHROME b-562 ADSORPTION ON GOLD-PARTICLE SURFACE BY OPTICAL ABSORPTION MEASUREMENT

1996 ◽  
Vol 03 (01) ◽  
pp. 1137-1141 ◽  
Author(s):  
S. AOKI ◽  
H.S. ZHOU ◽  
I. HONMA ◽  
T. NAGAMUNE ◽  
H. KOMIYAMA
Keyword(s):  
Cytochrome B ◽  
Gold Particle ◽  
Colloidal Particles ◽  
Colloidal Solution ◽  
Particle Surface ◽  
Cylindrical Shape ◽  
Gold Particles ◽  
Optical Absorption Measurement ◽  
Low Concentrations ◽  
High Concentrations

The plasmon absorption peak of 31-nm gold particles in aqueous solution was redshifted and broadened by the adsorption of protein. This effect is more striking in the acidic solution than in the alkaline solution. The adsorption is irreversible. When a small amount of protein was added to the colloidal solution, this effect was weak, but a small shoulder emerged at about 680 nm. With increasing quantity of the protein, the effect of the interaction became very strong. The small shoulder became larger and shifted to about 720 nm. But further addition of protein reduced the effect and finally the absorption spectrum became identical with the original colloidal solution. A model is presented which considers two adsorption manners of the protein on gold. Cytochrome b-562 is of cylindrical shape (height is 5.0 nm and diameter is 2.5 nm.) and has the chromophore at the position of about 3.5 nm from the bottom. Consequently, the “side-on” adsorption manner of the protein on gold which dominates at low concentrations and the “tail-on” adsorption fashion which dominates at high concentrations cause difference in the interaction distance between the surface plasmon and chromophore. The interaction between gold particles and the protein depends largely on the distance between the gold-particle surface and protoheme IX in the protein. The redshift and broadening of absorption peaks occurred at the side-on adsorption manner. We disclose an initial effort for developing a novel method to determine the configuration of protein adsorbed on colloidal particles.

scholarly journals Optimizing the solar water disinfection (SODIS) method by decreasing turbidity with NaCl

2012 ◽  
Vol 2 (2) ◽  
pp. 87-94 ◽  
Author(s):  
Brittney Dawney ◽  
Joshua M. Pearce
Keyword(s):  
Tropical Soils ◽  
Sodium Concentration ◽  
Water Disinfection ◽  
Particle Removal ◽  
Clay Particles ◽  
Solar Water ◽  
Solar Water Disinfection ◽  
Colloidal Clay ◽  
Diarrheal Incidence ◽  
Taste Thresholds

Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (<30 NTU). This study investigates the use of common table salt (NaCl) to reduce the turbidity of water containing suspended colloidal clay particles for use in the SODIS method. Three representative clays found in tropical soils (kaolinite, illite and bentonite) were tested at three levels of turbidity (50, 100 and 200 NTU) for their flocculating behavior with multiple NaCl concentrations to find the optimum. Supernatants were tested for sodium concentration for comparison against health and taste thresholds. Results show that unlike kaolinite and illite, pure bentonite solutions were shown to be very responsive to NaCl and produced supernatants with as low as 4 NTU (98% particle removal efficiency). This study has shown that NaCl, in combination with high-activity clay particles in solution, may effectively reduce turbidity to levels suitable for SODIS treatment, thereby expanding the number of people who can utilize the technology effectively.

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