Talc Suspension Research Articles

FEATURES OF THE TOPOGRAPHY AND NUMBER OF SBA+-В-LYMPHOCYTES IN THE MESENTERY OF THE INTESTINE IN NORMAL CONDITIONS AND DURING THE FORMATION OF THE ADHESION PROCESS

The study of the structural organization of the peritoneum as an immunocompetent organ will contribute to the solution of practical tasks, namely factors that control immune local and systemic reactions in the body. The question of the presence of these cells and their topography by the method of lectin histochemistry in the tissues of the peritoneum at the time of its formation, the peculiarities of the structure in different periods of onotogenesis in the norm and under the influence of endo- and exogenous factors remains not fully investigated. Carbohydrate specificity is used as a criterion for the functional classification of lectin receptors on the surface of cells, which indicates the processes of adhesion to various molecules, including fibrin and immune complexes. The aim of our study was to determine the peculiarities of the topography and the number of B-lymphocytes of the intestinal mesentery in rats in normal conditions and during the adhesion process with the help of soy lectin (SBA). The process of adhesion formation in rats of the II group was simulated by a single intraperitoneal injection of 0.5 ml of a 20% talc suspension into the area pelvis according to the method of Volyanska O.G. (2013). Animals were removed from the experiment 7, 14 and 21 days after the injection. Detection of lymphocytes that differ phenotypically according to carbohydrate residues was performed using soy lectin (SBA). The number of immunocompetent cells per standard area of 1000 μm2) was calculated.The morphology, topography and number of SBA+-lymphocytes, identified as B-lymphocytes, in the intestinal mesentery, as one of the derivatives of the peritoneum, are described. An increase in the number of SBA+ lymphocytes indicates the activation of the nonspecific humoral link of immunity, which is associated with excessive deposition of fibrinoid and affects the morphofunctional state of the peritoneum and its derivatives. Probably, lymphoid tissue associated with serous membranes (SALC) gives rise to the origin of B1-lymphocytes and is the place of their constant renewal. The leakage of fibrin leads to the formation of fibrin plaques, which are pathogenetically capable of changing the structural barrier between the connective tissue and the vessels of the peritoneum, which at the moment remains insufficiently studied. Quantitative studies of the accumulation of fibrin layers by the method of lectin histochemistry are planned.

Influence of local administration of autologous platelet-rich plasma on the level of expression of matrix metalloproteinases in experimental tendinopathy

Purpose: To evaluate the expression of matrix metalloproteinases in the calcaneal tendon tissue under conditions of experimental tendinopathy and under the influence of local administration of autologous platelet-rich plasma.
 Material and methods: The study was conducted on 20 mature Wistar rats divided into 5 groups. In all groups, experimental modeling of tendinopathy of the calcaneal tendon was performed by intra- and near-tendon injection of 0.5 ml of a 10 % suspension of sterile talc. Further, autologous platelet-rich plasma (PRP), hyaluronic acid preparation Rusvisk (Russia) or their sequential combination was injected into the area of tendinopathy. The results of the study were evaluated after 10 weeks; autopsy preparations prepared for immunohistochemical analysis were studied using light microscopy and morphometry.
 Results: Histological signs characteristic of tendinopathy were identified: disorganization of collagen structures, mucoid and lipoid degeneration, neovascularization, lymphoid-histiocytic infiltration. Injection of PRP into the area of simulated tendinopathy, hyaluronic acid, or their sequential combination led to changes in the immunohistochemical pattern of the tissue. As a result, there was a decrease in the expression of immunoreactive material in the cytoplasm of tenocytes and cells of the inflammatory infiltrate, compared with the picture observed in micropreparations in animals with tendinopathy, which were not subjected to any manipulations.
 Conclusion: The introduction of PRP into the area of the calcaneal tendon under conditions of experimental tendinopathy reduces the level of expression of matrix metalloproteinases and, thereby, preserves the structure of the tendon tissue, demonstrating tendoprotective properties.

Hospital-prepared talc suspensions for pleurodesis cause serious AEs

Hospital-prepared talc suspensions for pleurodesis cause serious AEs

Establishment of a Rat Model of Infraorbital Neuroinflammation Under CT Guidance.

The aim is to establish a rat model of infraorbital neuroinflammation with less trauma, stable pain, and a long duration of pain. The pathogenesis of trigeminal neuralgia (TN) is not fully clear. There are various models of TN in rats with different disadvantages, such as damaging the surrounding structures and inaccuracy of location for infraorbital nerve (ION). We aim to establish a rat model of infraorbital neuroinflammation with minimal trauma, a simple operation, and accurate positioning under CT guidance to help us study the pathogenesis of trigeminal neuralgia. Thirty-six adult male Sprague Dawley rats (180-220 g) were randomly divided into 2 groups and injected with talc suspension or saline through the infraorbital foramen (IOF) under CT guidance. Mechanical thresholds were measured in the right ION innervation region of 24 rats over 12 postoperative weeks. At 4 weeks, 8 weeks, and 12 weeks after the operation, the inflammatory involvement of the surgical area was evaluated by MRI, and neuropathy was observed using a transmission electron microscope (TEM). The talc group had a significant decrease in the mechanical threshold at 3 days after surgery that continued until 12 weeks post-operation, and the talc group had a significantly lower mechanical threshold than the saline group 10 weeks post-operation. The talc group had significantly impaired trigeminal nerve (TGN) myelin after 8 weeks post-operation. The rat model of infraorbital neuroinflammation established by CT-guided injection of talc into the IOF is a simple operation that results in less trauma, stable pain, and a long duration of pain. Moreover, infraorbital neuroinflammation in peripheral branches of the TGN can cause demyelination of the TGN in the intracranial segment.

Evaluation of the Efficiency of a Soft Dosage Form for the Treatment of Osteoarthritis: Influence on the Level of Pro-inflammatory Cytokines

Introduction. Osteoarthritis is now considered to be a slowly progressive inflammatory disease that completely affects the joint. An important role in the development of this pathology is played by inflammation of the synovial membrane and ligaments (synovitis), supplemented by constant mechanical stress. Normally, a balance of anti-inflammatory and pro-inflammatory mediators is observed in cartilage, however, under the influence of risk factors, this balance shifts towards the latter.Aim. Evaluation of the effect of a previously developed soft dosage form containing meloxicam, a purine derivative and an immunomodulator M on the level of pro-inflammatory cytokines: IL-1α, IL-1β, IL-6 and TNF-α in osteoarthritis.Materials and methods. The experiment included 25 animals, which were divided into 5 groups by simple randomization: 1 – test (gel 0.5 %), 2 –test (gel 1 %), 3 – reference (Amelotex®, gel 1 %), 4 – control (gel base); 5 – intact. Preclinical modeling of the pathology was carried out by combined injection of 0.1 ml of a mixture of complete Freund's adjuvant with a 10 % suspension of talc in isotonic sodium chloride solution in a ratio of 1 : 10 into the cavity of the hock (tarsal) joint of Brown Norvay Catholic Rats male rats. Enzyme immunoassay of animal blood serum on the 28th day of the experiment was performed using standard ELISA plate kits (Cloud-Clone Corp., USA). Statistical data processing was performed using GraphPad Prism 8.0.2 software (GraphPad Software Inc., USA), differences were considered statistically significant at p < 0.05.Results and discussion. The developed compositions contributed to a decrease in the level of pro-inflammatory cytokines (IL-1α, IL-6 and TNF-α) compared with the main and reference gel preparation. At the same time, differences were found between the effect observed from the use of the test agents (gel 0.5 %, gel 1 %) and the reference drug in terms of the effect on the level of IL-1α and TNF-α, which indicates a greater effectiveness of the selected combination of active substances, because, unlike the single-component gel Amelotex®, the compositions developed by us additionally included a purine derivative and an immunomodulator M. The data obtained are important from the point of view of understanding the mechanism of action of a soft dosage form.Conclusion. Based on the results of previous and present studies, it is assumed that the combined composition of the soft dosage form with a half (0.5 %) concentration of meloxicam is of greatest interest for clinical practice, since its use at a high level of effectiveness additionally reduces the likelihood of adverse reactions from the non-steroidal anti-inflammatory drug, which is important in the case of long-term therapy of osteoarthritis.

Pathogenetic features of experimental osteoarthrosis induced by dexamethasone and talc

The aim of the study was to investigate the pathogenesis of experimental osteoarthrosis induced by dexamethasone and talc by examining the structure and defining the morphometric and metabolic features of knee joint skeletal connective tissues in rats.Materials and methods. We performed a morphometric evaluation of articular cartilages (their thickness, extracellular matrix arrangement, spatial arrangement of the main components, distribution density, and main cellular indices of chondrocytes), as well as changes in subchondral bones (the presence of trabeculae in the basal layer of the articular cartilage and individual osteophytes) in 30 rats with a model of primary osteoarthrosis induced by sequential administration of 0.5 ml dexamethasone (2 mg) and 1 ml 10% sterile talc suspension mixed with normal saline into the joint cavity. We studied the histologic specimens of the knee joints stained with hematoxylin – eosin, Alcian blue (рН 1.0 and 2.5), as well as with Van Gieson’s, Masson’s, and Mallory’s trichome stains. The metabolic features of the articular cartilage and bone tissues were investigated by determining the hyaluronan, osteocalcin, and type I collagen levels in the serum of the rats.Results. In the rats with dexamethasone- and talc-induced osteoarthrosis, the thickness of cartilages in their weight-bearing areas decreased by 50%, the spatial arrangement of chondrocytes was impaired, and the nuclear – cytoplasmatic ratio (р < 0.01) decreased to 0.3. Besides, a rise in the serum levels of hyaluronan (p < 0.001) to 110.2 ng / ml, type I collagen fragments (p < 0.001) to 217.9 ng / ml, and osteocalcin (p < 0.001) to 231.1 ng / ml was detected.Conclusion. The main pathogenetic features of experimental osteoarthrosis induced by dexamethasone and talc include impaired distribution density, morphological characteristics, and functional activity of chondrocytes, which results in inhibited synthesis of extracellular matrix components in the articular cartilage and activated destruction of proteoglycans containing unsulphated glycosaminoglycans. The subchondral bone remodeling in experimental osteoarthrosis induced by dexamethasone and talc is characterized by intensification of synthetic activity of osteoblasts.

Investigation of detergent compositions on the effectiveness of alumina and aluminium titanium carbide cleaning

Particle contamination on a surface is a critical issue for the electronics manufacturing processes. Detergents that are composed of surfactants and appropriate additives can decrease the natural attraction forces between particles and surface, leading to effective particle removal. This work aims to investigate the influences of detergent pH and additives on the effectiveness in removing inorganic particles from Al2O3 and AlTiC substrates, which are commonly used materials in the electronics industry. In this study, we chose a model detergent comprised of an anionic surfactant, sodium dodecylbenzene sulfonate, and two additives, namely sodium acid pyrophosphate and ethanolamine. Talc particles were employed as a model inorganic contaminant. The effects of pH and ethanolamine concentration on the cleaning effectiveness of the model detergent were examined using optical microscopy and X-ray photoelectron spectroscopy (XPS). The stability of talc suspension in detergent solution, which is related to the possibility of particle recontamination, was determined by zeta potential. Our results indicate that the pH of the detergent directly affects its cleaning efficiency, likely by increasing the electrostatic repulsion between the surface and the talc particles. Similarly, the increasing ethanolamine concentration elevates the pH of the detergent, leading to better cleaning performances on both Al2O3 and AlTiC substrates.

Development of the composition and technology of a combined gel for the treatment of osteoarthritis with a pharmacological rationale for the content of components

Introduction. Osteoarthritis (OA) is the most common joint disease that affects more than 10 % of the world's population. More than 600 000 people are diagnosed for the first time each year, but these data do not reflect the true prevalence of the disease, since not all patients seek help from hospitals [1, 2].Aim. Pharmaceutical development of the composition and technology of a gel based on meloxicam, a purine derivative and an immunomodulating component for the treatment of OA with pharmacological substantiation of the content of active substances.Materials and methods. A combination of three active pharmaceutical substances was studied: a non-steroidal anti-inflammatory drug – meloxicam, a purine derivative and an original immunomodulator M. Sodium alginate, natrozole and xanthan gum were considered as gelling agents. Were identified two technological modes of obtaining a gel base. The concentrations of active substances were selected based on the results of preclinical studies. OA was modeled by the combined administration of 0.1 ml of a mixture of Freund's complete adjuvant with a 10 % talc suspension in isotonic sodium chloride solution in a ratio of 1 : 10 into the hock (tarsus) joint cavity. The criteria for choosing the optimal composition of the gel were the size of the damaged joint, exercise tolerance and the histological picture in comparison with intact and control animals. For quantitative data, sample mean values (M) and standard deviations (SD) were calculated. The results corresponded to the laws of normal distribution, statistical processing was carried out using one-way analysis of variance (One-Way ANOVA) using the GraphPad Prism 8.0.2 software, USA at the level of statistical significance of differences p < 0,05 и p < 0,001.Results and discussion. The composition was developed and the technology of the topical dosage form based on sodium alginate was proposed. Preclinical data indicate that the highest efficacy is achieved when using a formulation containing 3 % purine derivative, 5 % immunomodulator M and 0.5 % meloxicam. The developed composition for the effectiveness of suppressing the symptoms of OA showed results that exceeded the reference drug.Conclusion. An original combined agent for the treatment of OA has been developed. Due to the selected component composition, with greater efficiency, it was possible to reduce the dosage of meloxicam to 0.5 %, and the use of sodium alginate as a gelling agent contributed to the prolongation of the action of the gel and the subsequent reduction in the number of applications.

Structural changes of the tendon in experimental tendinopathy and administration of autologous platelet-rich plasma

Objectives assessment of structural changes in the calcaneal tendon tissue in experimental tendinopathy under autologous platelet-rich plasma.
 Material and methods. Twenty mature Wistar rats, selected for the study, were divided into 5 groups. Rats of all groups received intra- and peritendinous injections of 0.5 ml of 10% sterile talc suspension to provide the experimental modeling of tendinopathy of the calcaneal tendon. Then the tendinopathy area was treated by injections of autologous platelet-rich plasma (PRP), a hyaluronic acid preparation "Rusvisk" (Rusvisk, Russia) and their sequential combination. The results were evaluated after 10 weeks in the autopsy preparations using a light microscopy method and morphometry.
 Results. The histological signs characteristic of tendinopathy were revealed, such as the disorganization of collagen structures, mucoid and lipoid degeneration, neovascularization, lymphoid and histiocytic infiltration. The injection of PRP, hyaluronic acid, or their sequential combination in the area of simulated tendinopathy led to changes in the histological presentation of the tissue. As a result, the collagen matrix had less signs of disorganization and less pronounced degenerative changes, as well as manifestations of the inflammatory process in the peritenon and the soft tissues surrounding the tendon, in comparison with the histological profile, which was observed in micropreparations in animals with tendinopathy who had no treatment.
 Conclusion. The introduction of PRP into the area of the calcaneal tendon has reduced the manifestations of the inflammatory process, disorganization of the collagen matrix, promoted the enhancement of collagen synthesis by cells and, ultimately, the processes of tissue remodeling.

Experimental Research on the Evaluation of Left Ventricular Function by Layered Speckle Tracking in a Constrictive Pericarditis Rat Model.

In animal models with constrictive pericarditis (CP), detecting the function of cardiac systole by conventional noninvasive ultrasound is a challenge. We aimed to detect cardiac dysfunction in rat models with CP in the early stage by layered speckle tracking. We compared a rat CP model (n = 23, injected with a solution of 1-mg/mL lipopolysaccharides [0.5 mL] and a 10% talc suspension [0.5 mL]) with a control group (n = 20, no injection). After 8 weeks, conventional echocardiography and layered speckle tracking were used to assess the left ventricular structures and functions in the groups. The global circumferential strain (CS) and longitudinal strain (LS) were decreased in the CP group (P < .05). The CS of the epicardial and middle layers in the CP group was decreased (P < .05), but the endocardial layer was not statistically different. The LS of the epicardial layer was decreased (P < .05), but the middle and endocardial layers were not statistically different. The global free-wall and septal-wall CS of the CP group was decreased (P < .05), mainly due to the decrease of CS of the epicardial and middle layers. The global free-wall LS of the CP group was decreased (P < .05), mainly due to the decrease of LS of the epicardial and middle layers. There were no significant differences between the groups in global LS of the septal wall. In the early stage of CP, subepicardial myocardial damage precedes that of the subendocardial myocardium, and free-wall damage precedes that of the septal wall.

Flocculation efficiency of hybrid polymers with trivalent metal cations

Abstract Acrylamide/acrylic acid copolymers (AAm/AA) have been synthesized by microemulsion polymerization in absence and presence of trivalent cations Al+3 and Fe+3. Starch materials were obtained by introducing cations Al+3 and Fe+3, in the form of aqueous solutions of sulphates(VI) (modif. starch/Me+3), into the oxidized starch (modif. starch). The flocculation performance of obtained polyacrylamide copolymers and the one based on the natural polymer was compared with the performance of the commercial AAm/AA flocculant (CF). All materials were characterized by capillary viscometry, FTIR and DSC methods. An aqueous suspension of talc was used for the flocculation studies. The flocculation effectiveness was evaluated on the basis of reduction of suspension extinction and the sludge volume. It was found that synthesized AAm/AA/Me+3 copolymers and modif. starch/Me+3 materials exhibit better flocculation properties for a model talc suspension than a commercially available floculant.

The Prevention of Carboxymethylcellulose on Bowel Adhesions Induced by Talc Peritonitis in Mice

BackgroundPostoperative bowel adhesions may lead to various disorders, including abdominal pain, bowel obstruction, ischemia, and necrosis. In previous reports, a dose-dependent increase in bowel adhesions was observed in talc-treated animals in comparison with control animals. Although various methods have been devised to prevent peritoneal adhesions, each of these methods has advantages and disadvantages. In this study, we have attempted to reassess the effect of a carboxymethylcellulose (CMC) solution in the reduction of peritoneal adhesions induced by an intraperitoneal injection of a talc suspension in mice. Materials and methodsMice received an intraperitoneal injection of a talc suspension, followed by an injection of a CMC solution or vehicle. Two weeks after the injection, any adherent bowel mass was removed en bloc, weighed, and histologically observed. ResultsThe administration of talc induced severe bowel adhesions. CMC treatment was unable to completely inhibit the development of bowel adhesions, but treatment did reduce their weight in a dose-dependent manner. According to a histopathologic analysis, the bowel adhesions were composed of a conglomerate of talc aggregate and granulation tissue. The conglomerate was divided into two zones: the cell-rich marginal zone and the cell-scarce central zone. The injection of CMC specifically reduced the width of the marginal zone and the number of infiltrated cells. ConclusionsThis study demonstrated that CMC inhibited bowel adhesions induced by talc in mice. In addition, this is the first report on the effect of CMC on talc peritonitis accompanied by a detailed histologic examination. Our experimental model is very simple and easy to use. Therefore, it may help in the discovery of new antiadhesive agents and in the analysis of the kinetics of bowel adhesion.

Non-resonant light scattering in dispersions of 2D nanosheets

Extinction spectra of nanomaterial suspensions can be dominated by light scattering, hampering quantitative spectral analysis. No simple models exist for the wavelength-dependence of the scattering coefficients in suspensions of arbitrary-sized, high-aspect-ratio nanoparticles. Here, suspensions of BN, talc, GaS, Ni(OH)2, Mg(OH)2 and Cu(OH)2 nanosheets are used to explore non-resonant scattering in wide-bandgap 2D nanomaterials. Using an integrating sphere, scattering coefficient (σ) spectra were measured for a number of size-selected fractions for each nanosheet type. Generally, σ scales as a power-law with wavelength in the non-resonant regime: σ(λ)∝[λ/〈L〉]−m, where 〈L〉 is the mean nanosheet length. For all materials, the scattering exponent, m, forms a master-curve, transitioning from m = 4 to m = 2, as the characteristic nanosheet area increases, indicating a transition from Rayleigh to van der Hulst scattering. In addition, once material density and refractive index are factored out, the proportionality constant relating σ to [λ/〈L〉]−m, also forms a master-curve when plotted versus 〈L〉.

Quantifying the Responses of Three Bacillus cereus Strains in Isothermal Conditions and During Spray Drying of Different Carrier Agents.

Spray drying is a widely used method for producing milk powder. This process is not aimed to cause microbial inactivation, thus sporeforming bacteria may be abundant in the microbiota of milk powder. The first aim of this study was to determine the inactivation kinetics parameters in capillary tubes of three Bacillus cereus strains (436, B63, 540) in three menstrua (whole milk, phosphate buffer, and talc suspension) at 90, 100, and 110°C. D-values for B. cereus in the three menstrua were not significantly different at the highest tested temperature (p > 0.05). Thus, talc was chosen as a carrier agent to allow the recovery of B. cereus from spray dried materials given its low interference on inactivation kinetics. B. cereus spores were also inoculated in whole milk and skim milk following spray drying at 95, 105, and 110°C (outlet temperature). After the spray drying runs, B. cereus spores were counted and the number of decimal reductions (γ) calculated. A correlation between the small diameter of the particles with the survival of spores of three B. cereus strains was found, and B. cereus 436 presented consistently the lowest γ no matter temperature and a carrier agent. The highest γ was found when talc powder was used, which suggest that this carrier agent does not protect B. cereus spores during spray drying. Spray drying of milk can lead to up to 4 γ (strain 540) of B. cereus spores but depending on the strain less than one γ (strain 436) could be observed. This study contributes to the knowledge on the microbiology of low water activity foods by providing novel findings regarding the fate of three B. cereus strains to different spray drying conditions. Acknowledging the variability of inactivation of B. cereus during spray drying is key in the current context of food safety in which the quantification of effects of unit operations must be known for the validation of processes and development of more robust formulations.

Hydrophobic flocculation of talc with kerosene and effects of anionic surfactants

ABSTRACTThe variation of the hydrophobic flocculation behavior of talc mineral with pH, kerosene concentration, stirring speed, flocculation, and settling times was investigated. The experimental studies showed that the flocculation of talc suspension increased to a particular point with increasing kerosene concentration and thereafter decreased slightly. Also, the flocculation with kerosene was not much affected by the pH changes of the suspension. On the other hand, sodium oleate, sodium dodecyl sulfate (SDS), and Aero 801 used as anionic surfactant in conjunction with kerosene provided significant increases in the flocculation of talc, and depends on increasing surface hydrophobicity of the particles. Especially, in the presence of sodium oleate along with kerosene, the talc suspension could be flocculated with a recovery of 95%. Consequently, the enhancement with nonpolar oil was more significant for the hydrophobic flocculation of talc suspension promoted by long hydrocarbon chain surfactant (sodium oleate) than short hydrocarbon chain surfactants (SDS and Aero 801).

Preparation and properties of enstatite ceramic foam from talc

Abstract The effective method of preparation, stabilization and high temperature treatment of enstatite ceramic foam is described in this work. The technique is based on foaming of suspension of talc, on the stabilization of foam structure and on final high temperature treatment after drying. The spontaneous delamination of aggregates and the redistribution of talc particles in foam are driven by decreasing surface energy. The changes of phase composition as well as the mechanism and the kinetics of processes which take place during the thermal treatment were described. The treatment within the temperature range from 1150 to 1250 °C provides the ceramic foam via sintering without melted phase, whereas a liquid phase sintering occurs at higher temperatures. The final temperature of sintering is 1300 °C. Increasing amount of melted phase supports the formation of enclosed porosity and formed glass stabilizes the high temperature protoenstatite polymorph in the foam.

The influence of polymer chemistry on adsorption and flocculation of talc suspensions

The adsorption and action of four starch polymers in talc flocculation has been studied. The polymers include: two chemically modified starch polymers (carboxymethyl (CM) and phenyl succinate (PS) starch), with similar molecular weight but variation in terms of added aromatic functionality; and two unmodified starch polymers, Gelose 80 and Gelose 50, which vary in their amylose:amylopectin ratio. The adsorption behaviour of the polymers indicated that the carboxyl groups of the functionalised polymers discouraged adsorption at low ionic strength, with the non-charged Gelose polymers adsorbing to higher densities in spite of having lower molecular weights. AFM imaging and contact angle measurements indicated that the polymers interact similarly with the talc basal plane in terms of coverage and effect on hydrophobicity, with minor differences in adsorbed layer thickness. CM and PS starch had an equal and best effect on the flocculation behaviour of talc suspension. The settling rate of bare talc was 0.14mh−1; the two functionalised starch polymers increased the settling rate to 1.7 and 2mh−1 for CM and PS starch, respectively (at 8mgL−1 concentration). Whereas different chemical substitution had no pronounced effect on the settling behaviour, the relative content of amylose to amylopectin did produce differences in settling. Gelose 80 (80% amylose; 1.3mh−1 settling rate at 40mgL−1 concentration) performed better when compared Gelose 50 (50% amylose; 0.65mh−1 settling rate at 40mgL−1 concentration). Of the two unmodified starch polymers, Gelose 80 gave the best overall settling performance, highlighting the effect of the linear starch chains in encouraging good bridging flocculation.

Pathogenetic mechanisms of posttraumatic fibrosis of the uterus of white rats

Abstract

Influence of pH and Chloride-Based Metal Salts on Coagulation/Dispersion Behavior of Talc Suspension

In this study, the coagulation behavior of talc suspensions in the presence and absence of chloride-based metal salts (NaCl, CaCl2 and AlCl3) at a constant (pH 4) and different pHs was assessed by sedimentation tests and zeta potential (ZP) measurements. In addition, the pH-dependent dissolution experiments were performed on the talc powder in water. To evaluate the results of the sedimentation tests, the turbidity of supernatant liquid was considered. The isoelectric point (iep) of the talc sample was determined at around pH 1.9. Even though the talc suspension used in this work has a sufficient ZP at neutral pHs to provide a better dispersion in suspension, the sedimentation tests and also the viscosity measurements showed that the powdered talc coagulated easily, even at these pHs without the metal salt. This was attributed to the hydrophobic attraction between the basal surfaces of talc particles. At acidic pHs (i.e., pH 4) the effect of metal salts on the coagulation of talc suspension was marginal.

Microwave sintering of cordierite precursor green bodies prepared by starch consolidation

This paper reports on a study of the microwave sintering behavior of green disks prepared by the starch consolidation forming method to produce cordierite-based porous materials. Green disks were formed by thermogelling the aqueous suspensions of talc, kaolin and alumina (29.6vol.%) and potato starch (11.5vol.%) at 75 and 85°C for 4h, drying and calcining. They were characterized by bulk density and apparent porosity measurements, and SEM. Microwave sintering was carried out at 1300 and 1330°C for 15, 20 and 25min, applying 50°C/min. For purposes of comparison, an analysis of green disks prepared and calcined in the same conditions and conventionally sintered (1330°C for 4h) was also made. The materials were characterized by XRD, bulk density and apparent porosity measurements, and microstructurally analyzed SEM. The results were analyzed considering the behavior of starch in aqueous suspension at varying temperatures, and the experimental conditions of consolidation and sintering.