Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Colloids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMed2006

Orientational coupling amplification in ferroelectric nematic colloids.

We investigated the physical properties of low concentration ferroelectric nematic colloids, using calorimetry, optical methods, infrared spectroscopy, and capacitance studies. The resulting homogeneous colloids possess a significantly amplified nematic orientational coupling. We find that the nematic orientation coupling increases by approximately 10% for particle concentrations of 0.2%. A manifestation of the increased orientational order is that the clearing temperature of a nematic colloid increases by up to 40 degrees C compared to the pure liquid crystal host. A theoretical model is proposed in which the ferroelectric particles induce local dipoles whose effective interaction is proportional to the square of the orientational order parameter.

Journal Article↗
PubMed2006

Realizing colloidal artificial ice on arrays of optical traps.

We demonstrate how a colloidal version of artificial ice can be realized on optical trap lattices. Using numerical simulations, we show that this system obeys the ice rules and that for strong colloid-colloid interactions, an ordered ground state appears. We show that the ice-rule ordering can occur for systems with as few as 24 traps and that the ordering transition can be observed at constant temperature by varying the barrier strength of the traps.

Journal Article↗
PubMed2006

Pigmented coalescing papules on the dorsa of the hands: pigmented colloid milium associated with exogenous ochronosis.

Colloid milium is a rare cutaneous deposition disorder that frequently occurs in areas of chronic sun exposure such as the face, neck and backs of the hands and is characterized by multiple small, discrete, usually amber-colored, dome-shaped papules that cluster to form large plaques. A 50-year-old white woman with esophageal squamous cell carcinoma was referred to us with asymptomatic, slowly spreading lesions localized to the dorsa of her hands which had been present for 4 years. The condition was diagnosed histopathologically as pigmented colloid milium associated with exogenous ochronosis (EO). Colloid milium associated with EO is very rarely reported in the published work. We think that a possible interaction between sunlight and exposure to chemical fertilizers may have played a role in the pathogenesis of both of the disorders in our case.

Carcinoma, Squamous Cell↗
PubMed1992

Colloid solutions in the critically ill. A randomised comparison of albumin and polygeline 2. Serum albumin concentration and incidences of pulmonary oedema and acute renal failure.

All patients admitted to an Intensive Care Unit were assigned randomly to one of two groups, A and B. Group A received colloid volume replacement as 4.5% albumin whilst group B received a synthetic colloid, polygeline. This study describes the changes in serum albumin concentration in survivors and nonsurvivors in the two groups during their stay in the Intensive Care Unit. The incidences of renal failure and pulmonary oedema were also assessed. Serum albumin concentration decreased in all nonsurvivors. In survivors the serum albumin concentration decreased to a greater extent in the synthetic colloid group than in the albumin group. Despite the differences in serum albumin concentration there were no significant differences between the groups in the incidences of pulmonary oedema or renal failure.

Acute Kidney Injury↗
PubMed1975

Light and electron microscopic differentiation of amyloid and colloid or hyaline bodies.

Hyaline or colloid bodies (Civatte bodies) and amyloid are sometimes confused because of their similar appearance under the light microscope. A differentiation can be made by histochemical means (DMAB-Nitrite method) and by fluorescence or polarization microscopy. At the ultrastructural level hyaline or colloid bodies as well as amyloid exhibit a fibrillar structure, but can be differentiated by the diameter and arrangement of fibrils and the localization of the aggregations. A clearcut differentiation between hyaline or colloid bodies and amyloid seems of great importance in any dicussion of the epidermal origin of amyloid and the classification of fibrillar aggregations associated with skin tumours.

Amyloid↗
PubMed2006

Effect of treatment with a colloidal oatmeal lotion on the acneform eruption induced by epidermal growth factor receptor and multiple tyrosine-kinase inhibitors.

Current treatment modalities for epidermal growth factor (EGFR)-positive cancers have recently included the use of antibodies and small-molecule tyrosine-kinase inhibitors (TKI). A significant limiting step in the use of these agents is dermatological toxicity, frequently in the form of an acneiform eruption. Present management modalities for this toxicity are largely ineffective. Colloidal oatmeal lotion demonstrates multiple anti-inflammatory properties with known effects on arachidonic acid, cytosolic phospholipase A2 and tumour necrosis factor-alpha pathways, along with an excellent side-effect profile. Treatment with colloidal oatmeal was applied to 11 patients with a rash induced by cetuximab, erlotinib, panitumumab and sorafenib. Of the 10 assessable patients, 6 had complete response and 4 partial response, giving a response rate of 100% with no associated toxicities. Treatment with colloidal oatmeal lotion is efficient in controlling the rash associated with EGFR and multiple TKI, and allows continuation of the antineoplastic treatment.

Acneiform Eruptions↗
PubMed2006

Colloid milium arising on a non-sun-exposed area in an adult.

A 59-year-old woman presented with multiple translucent papules on the inner surface of the tragus of the right ear. Initially they were treated with cryotherapy, with a later biopsy revealing the diagnosis of colloid milium. The histology was unusual for adult colloid milium as the lesion lacked a Grenz zone and evidence of solar elastosis. This together with a lack of aetiological factors made it difficult to classify the subtype of colloid milium.

Dermatitis↗
PubMed1993

Colloid cyst of the 3rd ventricle as a cause of acute neurological deterioration and sudden death.

A 13 year old girl presented with a 24 h history of headache and vomiting. There were no focal neurological signs. The diagnoses considered were vascular headache, meningitis and subarachnoid haemorrhage. Lumbar puncture revealed clear cerebrospinal fluid under high pressure and subsequent cerebral computed tomography (CT) scan revealed hydrocephalus. Death occurred some hours after the lumbar puncture. Autopsy revealed a colloid cyst of the 3rd ventricle causing the hydrocephalus. Cerebellar tonsillar herniation was present. This case is reported because although 3rd ventricular colloid cysts are a recognized cause of acute neurological deterioration and sudden death, they rarely present in childhood. In this case, it is considered that lumbar puncture may have hastened death by increasing brain-stem compression due to cerebellar tonsillar herniation. It raises the question of whether cerebral CT scan, where readily available, should be performed prior to lumbar puncture. Pathologically, colloid cysts may be easily missed if the brain is examined fresh as the cysts are fragile and have a tendency to be destroyed or fall out.

Adolescent↗
PubMed1981

Albumin concentration and colloid osmotic pressure of interstitial fluid collected by wick technique from rat skeletal muscle. Evaluation of the method.

Interstitial fluid from rat skeletal muscle has been collected by multifilamentous nylon wicks. The wicks consisted of 5-600 single filaments and had an overall diameter of 1-2 mm. The wicks were implanted in the muscle by means of a mending needle. The wicks were removed at various times after implantation, and colloid osmotic pressure (COP) or albumin concentration in wick fluid was measured. The fluid contained in the wick had a COP of 8-10 mmHg and an albumin concentration about 1/3 that of plasma. COP in wicks preloaded with serum of serum/saline dilution was higher after 1/2 and 1 h of implantation, but was nearly identical to that of saline soaked wicks after 2 h implantation. Intravenous injection of labelled albumin showed that wick implantation caused a marked leakage of proteins from plasma to the wick. However, 1/2 to 1 h after implantation the leakage was markedly reduced. The initial leakage of albumin could be diminished with protease inhibitor (aprotinin), but not with prostaglandin-, serotonin-, or histamine antagonists. The experiments show that wick fluid colloid osmotic pressure reflects interstitial fluid colloid osmotic pressure, while the protein composition of wick fluid may not be identical to that of undisturbed interstitial fluid.

Albumins↗
PubMed2001

Soluble and colloidal iron in the oligotrophic North Atlantic and North Pacific.

In the oligotrophic North Atlantic and North Pacific, ultrafiltration studies show that concentrations of soluble iron and soluble iron-binding organic ligands are much lower than previously presumed "dissolved" concentrations, which were operationally defined as that passing through a 0.4-micrometer pore filter. Our studies indicate that substantial portions of the previously presumed "dissolved" iron (and probably also iron-binding ligands) are present in colloidal size range. The soluble iron and iron-binding organic ligands are depleted at the surface and enriched at depth, similar to distributions of major nutrients. By contrast, colloidal iron shows a maximum at the surface and a minimum in the upper nutricline. Our results suggest that "dissolved" iron may be less bioavailable to phytoplankton than previously thought and that iron removal through colloid aggregation and settling should be considered in models of the oceanic iron cycle.

Journal Article↗
PubMed2002

Layer-by-layer growth of binary colloidal crystals.

We report the growth of binary colloidal crystals with control over the crystal orientation through a simple layer-by-layer process. Well-ordered single binary colloidal crystals with a stoichiometry of large (L) and small (S) particles of LS2 and LS were generated. In addition, we observed the formation of an LS3 superstructure. The structures formed as a result of the templating effect of the first layer and the forces exerted by the surface tension of the drying liquid. By using spheres of different composition, one component can be selectively removed, as is demonstrated in the growth of a hexagonal non-close-packed colloidal crystal.

Journal Article↗
PubMed2005

Premelting at defects within bulk colloidal crystals.

Premelting is the localized loss of crystalline order at surfaces and defects at temperatures below the bulk melting transition. It can be thought of as the nucleation of the melting process. Premelting has been observed at the surfaces of crystals but not within. We report observations of premelting at grain boundaries and dislocations within bulk colloidal crystals using real-time video microscopy. The crystals are equilibrium close-packed, three-dimensional colloidal structures made from thermally responsive microgel spheres. Particle tracking reveals increased disorder in crystalline regions bordering defects, the amount of which depends on the type of defect, distance from the defect, and particle volume fraction. Our observations suggest that interfacial free energy is the crucial parameter for premelting in colloidal and atomic-scale crystals.

Journal Article↗
PubMed2005

Colloidal jamming at interfaces: a route to fluid-bicontinuous gels.

Colloidal particles or nanoparticles, with equal affinity for two fluids, are known to adsorb irreversibly to the fluid-fluid interface. We present large-scale computer simulations of the demixing of a binary solvent containing such particles. The newly formed interface sequesters the colloidal particles; as the interface coarsens, the particles are forced into close contact by interfacial tension. Coarsening is markedly curtailed, and the jammed colloidal layer seemingly enters a glassy state, creating a multiply connected, solidlike film in three dimensions. The resulting gel contains percolating domains of both fluids, with possible uses as, for example, a microreaction medium.

Journal Article↗
PubMed1997

Novel Colloidal Interactions in Anisotropic Fluids

Small water droplets dispersed in a nematic liquid crystal exhibit a novel class of colloidal interactions, arising from the orientational elastic energy of the anisotropic host fluid. These interactions include a short-range repulsion and a long-range dipolar attraction, and they lead to the formation of anisotropic chainlike structures by the colloidal particles. The repulsive interaction can lead to novel mechanisms for colloid stabilization.

Journal Article↗
PubMed1998

Nanoengineering of inorganic and hybrid hollow spheres by colloidal templating

Hollow silica and silica-polymer spheres with diameters between 720 and 1000 nanometers were fabricated by consecutively assembling silica nanoparticles and polymer onto colloids and subsequently removing the templated colloid either by calcination or decomposition upon exposure to solvents. Scanning and transmission electron microscopy images demonstrate that the wall thickness of the hollow spheres can be readily controlled by varying the number of nanoparticle-polymer deposition cycles, and the size and shape are determined by the morphology of the templating colloid. The hollow spheres produced are envisioned to have applications in areas ranging from medicine to pharmaceutics to materials science.

Journal Article↗
PubMed1991

Visualization of Trichoderma reesei Cellobiohydrolase I and Endoglucanase I on Aspen Cellulose by Using Monoclonal Antibody-Colloidal Gold Conjugates.

Monoclonal antibodies (MAbs) specific for cellobiohydrolase I (CBH I) and endoglucanase I (EG I) were conjugated to 10- and 15-nm colloidal gold particles, respectively. The binding of CBH I and EG I was visualized by utilizing the MAb-colloidal gold probes. The visualization procedure involved immobilization of cellulose microfibrils on copper electron microscopy grids, incubation of the cellulose-coated grids with cellulase(s), binding of MAb-colloidal gold conjugates to cellulase(s), and visualization via transmission electron microscopy. CBH I was seen bound to apparent crystalline cellulose as well as apparent amorphous cellulose. EG I was seen bound extensively to apparent amorphous cellulose with minimal binding to crystalline cellulose.

Journal Article↗
PubMed1994

Colloidal and Dissolved Organic Matter Excreted by a Mixotrophic Flagellate during Bacterivory and Autotrophy.

Excretion of dissolved and colloidal organic carbon by a mixotrophic flagellate, the chrysophyte Poterioochromonas malhamensis, was studied. Flagellates were incubated either with C-labeled bacteria or with inorganic C, in order to compare organic exudates originating from primary production with exudates originating from ingested bacteria. Colloids of >0.02 mum constituted a larger fraction of the exudates originating from ingested bacteria, compared with exudates derived from primary production. Flagellate feeding on bacteria specifically labeled in different cell components was compared. Cell wall components gave rise to less colloidal organic carbon than did other cell constituents. To investigate the degradability of flagellate C-exudates, they were added to lake water and mineralization to CO(2) was monitored. Bacterially derived exudates were more recalcitrant than exudates originating from photosynthesis. The results support the hypothesis that bacterial utilization of labile organic compounds, followed by flagellate bacterivory and exudation, results in a transformation of labile organic matter into more recalcitrant forms.

Journal Article↗
PubMed1990

Colloidal gold immunolabeling of immunoglobulin-binding sites and beta antigen in group B streptococci.

We have characterized the immunoglobulin A (IgA)-Fc-binding properties and beta-antigen expression of several strains of group B streptococci by using ultrastructural immunocytochemistry. Colloidal gold-labeled tracers were used with intact and sectioned bacteria in order to gain information regarding the location and distribution of cell surface and cytoplasmic IgA-Fc-binding molecules and beta antigen. Colloidal gold (5- or 15-nm particles) was conjugated to IgA to characterize IgA-binding properties and to IgG to test for IgG binding. Rabbit anti-beta antiserum was reacted with the bacteria and then with protein G labeled with 15-nm colloidal gold particles. A double-labeling technique was used for simultaneous localization of IgA-Fc- and anti-beta-antibody-binding properties on sectioned bacteria. The data corroborated previous results which indicated that (i) IgA-Fc-binding and IgA-Fc-nonbinding forms of beta antigen can be secreted by strains which do not express beta antigen on the cell surfaces (HG806, VC75); (ii) differences in levels of expression of beta antigen and/or IgA-Fc-binding proteins can be detected among various group B isolates; (iii) group B streptococci do not express human IgG-Fc-binding proteins; and (iv) not all forms of beta antigen are capable of binding human IgA.

Animals↗