Suspension Agent Research Articles

Vehicle Effect on In-Vitro and In-Vivo Performance of Spray- Dried Dispersions

In early drug development, amorphous spray-dried dispersions (SDDs) applied to enhance the bioavailability of poorly water-soluble compounds are typically administered to preclinical species via oral gavage in the form of suspensions. The liquid formulations are usually prepared on the same day of dosing to minimize the exposure of the amorphous material to the aqueous vehicle, thereby reducing the risk of crystallization. Dose-ability (e.g. syringe-ability) of the suspensions is also a critical factor for the administration, particularly when high doses, thus concentrations, are required for toxicology studies. As a result, it is standard practice during early formulation screening to assess the stability and the maximum feasible concentration of SDDs in various vehicles. In this study, we evaluated the impact of different vehicles on the performance of a model SDD in-vitro and in-vivo settings, to mitigate the risks associated with its administration in liquid form. A poorly water-soluble compound (GEN-A) was selected to screen various SDDs and generate the SDD model at 30 % drug load with HPMCAS-MF polymer carrier. The SDD was suspended in selected aqueous vehicles after a careful vehicle components screening, that included suspending agents (HPC-SL), solubilizers (PEG400, Propylene glycol), surfactants (Vitamin E TPGS, SLS, Tween 80, Poloxamer 188), and complexing agents (HP-β-CD, SBE-β-CD). The suspensions were characterized for stability, dose-ability and dissolution in biorelevant media, prior administration in pre-clinical species. The SDD dissolution profile revealed that the drug's supersaturation level was positively impacted by the presence of a surfactant (SLS) and a complexing agent (SBE-β-CD) with respect to a suspending agents (HPC-SL) in the vehicle. Similarly, the pharmacokinetics profiles of the drug following the administration of the SDD in a vehicle with a complexing agent (SBE-β-CD) achieved greater exposure compare to the SDD in a vehicle with a suspending agent (HPC-SL). These findings confirm a synergistic effect between the SDD and the vehicles, suggesting that this combination could be leveraged to maximize the advantages of the amorphous approach.

Synthesized Crosslinking Suspension Stabilizer for Spacer Fluid in High-Temperature Conditions: Synthesis, Behavior, and Mechanism Research

Summary High-temperature stability of spacer fluid is a vital prerequisite to ensure the safety of cementing operations in deep or ultradeep wells. Faced with this problem, the thermal stability of the suspension agent in the spacer fluid at high temperatures is improved from the aspects of polymerization monomer and molecular chain. A terpolymer SAD was synthesized by free radical polymerization of sodium styrene sulfonate (SSS), acrylamide (AM), and N, N’-diethylacrylamide (DEAA) in aqueous solution. The name of the terpolymer, SAD, is the initial letter composition of the three polymerization monomers. Polyethyleneimine (PEI) can improve the molecular chain structure of SAD by transamidation reaction with the amide group in SAD, so a high temperature suspension agent PSAD (polyethyleneimine + SAD) was obtained by compounding PEI with SAD. The structure and properties of PSAD were characterized by Fourier infrared spectroscopy, hydrogen nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, scanning electron microscopy (SEM), and viscosity test. In addition, the comprehensive properties of the spacer fluid under the action of PSAD are evaluated. The results showed that the crosslinking degree of PSAD gradually increased with the increase in temperature. After aging at 200°C, the decomposition temperature of PSAD was 305°C, which show terrific thermal stability. At the same time, the spacer fluid prepared by PSAD not only has excellent rheological properties in the range of 90 ~ 200°C but also keeps the density difference between the upper and lower parts of the slurry less than 0.02 g/cm3 and the filtration loss of the slurry less than 50 mL.

Synthesis and performance study of amphoteric polymer suspension stabilizer for cementing slurry at ultra-high temperature

As the number of ultra-deep wells increases, maintaining the suspension stability of cement slurry at ultra-high temperatures becomes increasingly challenging; the development of a suspension stabilizer suitable for ultra-high temperature environments is imperative. Therefore, this study synthesized a temperature-resistant polymer suspension stabilizer (LHAP) using 2-acrylamide-2-methylpropanesulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAA), 4-acryloylmorpholine (ACMO), and quaternary ammonium cationic hydrophobic long-chain monomer hexadecyl dimethylallyl ammonium chloride (DMAAC-16) as raw materials. It was applied to maintain the suspension stability of cement slurry at ultra-high temperatures. The molecular structure and molecular weight of LHAP were characterized and tested using infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, and Ubbelohde viscometer. The thermal stability and viscosity-temperature performance of LHAP were measured using thermogravimetric analysis and rheometer, respectively. Through the segmented density difference testing of cement stone columns, the suspension stability effect of LHAP on cement slurry under high temperature was evaluated. The suspension stabilization mechanism of LHAP was studied through fluorescence probe testing, variable temperature UV visible light testing, variable temperature particle size distribution testing, Zeta potential analysis, Environmental Scanning Electron Microscopy (ESEM) analysis, and scanning electron microscopy (SEM) analysis. The results indicated that the polymer suspension agent LHAP had excellent temperature resistance, and the molecules didn’t undergo significant thermal degradation below 302 ℃. At high temperatures of 220 ℃, LHAP could maintain the suspension stability of cement slurry, and the segmented density difference of cement columns was less than 0.01 g/cm3. Mechanism analysis revealed that in addition to enhancing temperature resistance by introducing sulfonic acid groups and rigid rings, LHAP also effectively maintains the stability of the slurry suspension at ultra-high temperatures by coordinating electrostatic interactions and molecular associations. LHAP can effectively solve the settlement instability problem of cement slurry under ultra-high temperature, which is beneficial for improving the safety and quality of cementing construction in ultra-deep wells.

Biological Characteristics of the Mycelium and Optimization of the Culture Medium for Phallus dongsun.

This study aimed to elucidate the influence of various culture medium components, including carbon sources, nitrogen sources, inorganic salts, suspension agents, and temperature, on the mycelial growth characteristics of Phallus dongsun. Employing single-factor experiments and response surface methodology within glass Petri dishes, the research identified that carrot powder, soybean powder, and ZnSO4 notably enhanced the proliferation of aerial mycelium, significantly augmenting the growth rate of P. dongsun mycelium. The resultant mycelium was observed to be dense, robust, and fluffy in texture. In particular, ZnSO4 markedly accelerated the mycelium growth rate. Furthermore, xanthan gum was found to effectively modulate the medium's viscosity, ensuring a stable suspension and facilitating nutrient equilibrium. The optimal cultivation temperature was determined to be 25°C, with mycelial growth ceasing below 5°C and mycelium perishing at temperatures exceeding 35°C. The optimal medium composition was established as follows: wheat starch 5 g/l, carrot powder 5 g/l, soybean powder 7.50 g/l, glucose 10 g/l, ZnSO4 0.71 g/l, NH4Cl 0.68 g/l, xanthan gum 0.5 g/l, and agar 20 g/l. Under these optimized conditions, the mycelium of P. dongsun exhibited a rapid growth rate (1.04 ± 0.14 mm/day), characterized by a thick, dense, and well-developed structure. This investigation provides a theoretical foundation for the conservation, strain selection, and breeding of P. dongsun.

Modeling the impact of the temperature profile on the sedimentation process for shear thinning suspensions in the annulus of oil well

The particle settling phenomena were broadly studied in the literature experimentally and numerically. To the best of our knowledge, previous works do not consider the temperature effect on the suspension rheology and, consequently, the influence over the settling velocity. Motivated by the problem of the sedimentation in confined drilling fluids exposed to a geothermal temperature gradient, this work proposed a continuum model for the sedimentation process of weighting agents in non-Newtonian suspensions based on the Mixture Theory. A temperature-dependent correction for the suspension consistency index was proposed and the results were discussed for different temperature profile cases, including uniform temperature profile, linear and geothermal profiles. Numerical simulations were performed, using the Finite Volume technique. Results for the solids concentration along the column for up to five years were discussed as well as the solids concentration evolution for selected points along the column. The results showed that the temperature gradient significantly impacts the settling velocity and the evolution of sedimentation regions. The main affected zones were the free settling and the sediment zones, which can alter directly parameters of interest for applications in oil wells, such as the height of sediment.

Colloidal gelation induced by ring polymers

We provide unambiguous experimental evidence that ring polymers are stronger depleting agents in colloidal suspensions than their linear counterparts. We use an intermediate volume fraction (ϕc=0.44) colloidal gel based on the classic poly(methyl methacrylate) (PMMA) hard spheres, in which the polystyrene depletant is either linear or ring of the same molar mass or the same size. We systematically increase the depletant concentration from zero (no attraction) to well above the gelation point and find that in the presence of rings, gels are formed at smaller concentrations and possess a larger storage modulus in comparison to those induced by the linear chains. Consequently, the yield stress is enhanced; however, the yield strain (gel deformability) remains concomitantly unaffected. Our experimental findings are in agreement with theoretical calculations based on effective interaction potentials. Hence, polymer architecture is a powerful entropic tool to tailor the strength of colloidal gels. Published by the American Physical Society 2024

Insights into the synthesis of hydrogels containing glycerol-based macromonomers for wastewater treatment: Focus on the efficient extraction of caffeine and mercury

The present study explores the production of microparticulate hydrogels for the selective adsorption of caffeine and mercury in wastewater treatment. Modified glycerol macromonomers, obtained through esterification reactions of glycerol with acrylic acid (n-ACG AA) and methacrylic acid (n-ACG MA), were successfully employed for the synthesis of these versatile materials using inverse suspension polymerization. The impact of different parameters, such as initiator, suspension agents, and monomers concentrations, and reaction time, on the final hydrogel characteristics – including morphology, swelling degree, and reaction yield – was assessed. Ultimately, microparticulate hydrogels (∼110 µm) with distinct absorption capacities were synthesized. Among the hydrogels produced, the n-ACG AA hydrogel exhibited an absorption capacity of 542% (w/w). This hydrogel was synthesized under optimized conditions using n-ACG AA (20 wt%), acrylic acid (50 wt%), bis-acrylamide (30 wt%), and 5% Span-60. The n-ACG MA hydrogel displayed an absorption capacity of 445% (w/w) and was synthesized with n-ACG MA (20 wt%), acrylic acid (50 wt%), bis-acrylamide (30 wt%), and 5% Span-80. Lastly, the hydrogel resulting from the combination of n-ACG AA and sodium acrylate (n-ACG AA/SA) demonstrated the highest absorption of 760% (w/w). It was synthesized with n-ACG AA (20 wt%), sodium acrylate (50 wt%), bis-acrylamide (30 wt%), and 5% Span-60. To evaluate the adsorption capacity of the materials, equilibrium adsorption isotherm assays were performed. The maximum adsorption capacity observed in caffeine assays was 91.55 mg g−1 for the n-ACG AA hydrogel. In mercury assays, the best capacity was found to be 369.75 mg g−1 with the hydrogel synthesized using n-ACG AA macromonomer combined with sodium acrylate. For both adsorbates, the Freündlich model was proven to be the most suitable for describing the adsorption isotherms. These results reveal the potential application of modified glycerol-based hydrogels in wastewater treatment processes.

Study on Simulation of Mold Filling and Solidification Characteristics of Hypereutectic High-Chromium Cast Iron by Lost Foam Suspension Casting

In this paper, the finite element software ProCAST version 14.5 was used to simulate the temperature field, flow field and defect prediction in the filling and solidification process of hypereutectic high-chromium cast iron. The effects of pouring temperature, negative pressure and the amount of suspension agent added during the technological process were explored. The optimum process parameters were presented. It was found that the suspension agent has a certain hindrance to the filling process, but the filling process remains stable. In the solidification stage, 89.4% of the suspension agent melted, resulting in a relative supercooling degree of 50 °C, which had a certain chilling effect and improved the solidification rate.

Formulation and Evaluation of Ornidazole Oral Re-Constitutable Suspension

Large numbers of drugs are available in the market in form of dry syrup, where reconstitution has to be done by patient. Ornidazole is an antibiotic used to treat some protozoan infections. It has also been investigated for use in Crohn's disease after bowel resection. In the present investigation the drug Ornidazole was selected for the design of oral reconstitutable suspension for improving its stability and palatability by using various techniques like physical mixing, solvent evaporation and co-grinding method with different suspending agents like Xanthan gum, SCMC, Guar gum and sodium alginate. The reconstitutable suspensions were evaluated for flow properties, particle size, pH, viscosity, sedimentation volume, redispersibility and drug release by in-vitro dissolution studies. Formulated OFS reconstitutable suspension has acceptable sedimentation properties. The drug excipients interactions and crystal morphology of optimized reconstitutable suspension were evaluated by Fourier transform infrared spectroscopy (FTIR), differential scanning Calorimetry (DSC), analysis. The results indicated that the release of the Ornidazole was rapid from all formulations than the pure drug. The drug release from the suspensions followed first order kinetics. From the results it is concluded that effective taste masking of Ornidazole was achieved using SCMC and successfully evaluated in reconstitutable suspension.

The Controversy: Whether Sucralose Could Increase Blood Glucose in The Body?

Sucralose is the most used artificial sweetener around the world, accounted for 30% of the global low-calorie sweetener market in 2016. According to the inspection of 19915 pre-packaged foods in Hong Kong, sucralose is the most used non-nutritive sweetener, followed by acesulfame. In addition to the food industry, sucralose can also be used as one kind of subsidiary materials for correcting taste in suspension agent, oral liquid, tablets, and granules, which could cover up the bitter taste of medicines such as aspirin or traditional Chinese medicine compound. The Food and Drug Administration (FDA) had approved the use of sucralose, but whether sucralose intake has effect on blood glucose is not clarified clearly. For this purpose, we collected and summarized the clinical studies to evaluate the effect of sucralose intake on blood glucose since 1996 from PubMed database, hope it may provide some evidence for sucralose applications in food excipient or drug sweet excipient.

Mitigation of SARS-CoV-2 by Using Transition Metal Nanozeolites and Quaternary Ammonium Compounds as Antiviral Agents in Suspensions and Soft Fabric Materials.

The coronavirus disease 2019 (COVID-19) pandemic has demonstrated the need for novel, affordable, and efficient reagents to help reduce viral transmission, especially in high-risk environments including medical treatment facilities, close quarters, and austere settings. We examined transition-metal nanozeolite suspensions and quaternary ammonium compounds as an antiviral surface coating for various textile materials. Zeolites are crystalline porous aluminosilicate materials, with the ability of ion-exchanging different cations. Nanozeolites (30 nm) were synthesized and then ion-exchanged with silver, zinc and copper ions. Benzalkonium nitrate (BZN) was examined as the quaternary ammonium ion (quat). Suspensions of these materials were tested for antiviral activity towards SARS-CoV-2 using plaque assay and immunostaining. Suspensions of the nanozeolite and quat were deposited on polyester and cotton fabrics and the ability of these textiles towards neutralizing SARS-CoV-2 was examined. We hypothesized that transition metal ion containing zeolites, particularly silver and zinc (AM30) and silver and copper (AV30), would be effective in reducing the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Additionally, AM30 and AV30 antiviral potency was tested when combined with a quaternary ammonium carrier, BZN. Our results indicate that exposure of SARS-CoV-2 to AM30 and/or AV30 suspensions reduced viral loads with time and exhibited dose-dependence. Antiviral activities of the combination of zeolite and BZN compositions were significantly enhanced. When used in textiles, AM30 and AV30-coated cotton and polyester fabrics alone or in combination with BZN exhibited significant antiviral properties, which were maintained even after various stress tests, including washes, SARS-CoV-2-repeated exposures, or treatments with soil-like materials. This study shows the efficacy of transition metal nanozeolite formulations as novel antiviral agents and establishes that nanozeolite with silver and zinc ions (AM30) and nanozeolite with silver and copper ions (AV30) when combined with benzalkonium nitrate (BZN) quickly and continuously inactivate SARS-CoV-2 in suspension and on fabric materials.

Bioactivity, Uptake, and Distribution of Prothioconazole Loaded on Fluorescent Double-Hollow Shelled Mesoporous Silica in Soybean Plants.

Prothioconazole (PTC) has been widely utilized for plant fungal disease control, but its metabolite prothioconazole-desthio (PTC-d) exhibits reproductive toxicity. In the present study, carbon quantum dot (CQD)-modified fluorescent double-hollow shelled mesoporous silica nanoparticles (FL-MSNs) loaded with PTC, referred to as PTC@FL-MSNs, were constructed with an average size of 369 nm and a loading capacity of 28.1 wt %, which could increase the antifungal efficiency of PTC. In addition, upright fluorescence microscope and UPLC-MS/MS studies showed that PTC@FL-MSNs could be effectively transported via root uptake and foliar spray in soybean plants. Compared to a 30% PTC dispersible oil suspension agent, the PTC@FL-MSN treatment group showed higher concentrations (leaves: 0.50 > 0.48 mg/kg), longer half-lives for degradation (leaves: 3.62 > 3.21 d; roots: 3.39 > 2.82 d), and fewer metabolites. These findings suggest that sustained pesticide release and toxicity reduction are potential applications for PTC nanofungicide delivery technology.

Multiple-open-tubular column enabling transverse diffusion. Part 3: Simulation of solute dispersion along a real three dimensional-printed column with quadratic channels

Multiple-open-tubular columns enabling transverse diffusion (MOTTD) consist of straight and parallel flow-through channels separated by a mesoporous stationary phase. In Part 1, a stochastic model of band broadening along MOTTD columns accounting for longitudinal diffusion, trans-channel velocity bias, and mass transfer resistance in the stationary phase was derived to demonstrate the intrinsic advantage of MOTTD columns over classical particulate columns. In Part 2, the model was refined for the critical contribution of the channel-to-channel polydispersity and applied to address the best trade-off between analysis speed and performance. In this Part 3, a MOTTD column with a square array of quadratic channels is fabricated by 3D-printing (combining polymer stereolithography with photolithography using photomasks) to deliver unprecedently small apparent channel diameters of 117.6 ± 5.0 μm. The colors in the microscopy photographs of the actual 3D-printed channels are binarized to delimitate the mobile phase volume from the stationary phase volume. The same numerical simulations as those in Part 2 are then performed for two MOTTD columns (external porosity ϵe=31.7%, same apparent channel diameter 117.6 μm): one containing 16 virtual perfect quadratic channels and the other 16 real 3D-printed channels. The reduced velocities (or Peclet numbers) are varied over a wide range from 0.2 to 5000 and the zone retention factors were fixed at k1=1.04, 5, and 25.The results demonstrate that smoothing the edges of the targeted quadratic channels by the 3D-printed technique is advantageous in terms of solute dispersion. It outperforms the negative effect of the channel-to-channel polydispersity which is mitigated by transverse diffusion of the analyte in the stationary phase. For Peclet numbers larger than 50, the HETP of the 3D-printed MOTTD column is found 7%, 15%, and 16% smaller than that of the MOTTD column consisting of a square array of perfect quadratic channels. This confirms the known effect of channel geometry on solute dispersion in microfluidic systems. Flow channels in fabricated MOTTD columns are preferred to be circular so that the distribution of transverse diffusion lengths across the open channels remains as tight as possible. Finally, the general theory of nonuniform columns of Giddings reveals that the polydispersity of the cross-sectional area (RSD 8.4%) along a single 3D-printed channel has no negative impact on solute dispersion in MOTTD columns. Overall, MOTTD columns could become a serious alternative technology to conventional particulate columns. This implies a novel fabrication process that delivers circular channel diameters smaller than 10 μm, cross-sectional area polydispersity no larger than 25%, external porosities in a range from 15% (high speed separations) to 75% (high performance separations), and conventional mesoporous silica as the stationary phase. It adresses new synthesis routes based on either organic fibers or tubular micelle templating agents in suspension with silica gel solutions.

Properties of Coated Paper Containing Cellulose Nanofibrils as an Additive

Cellulose nanofibrils (CNF) derived from wood can be used as thickening agents for suspensions or slurries because they form a gel structure by absorbing water and demonstrate an excellent shear thinning behavior. When used as a thickening agent for paper coating, CNF influences the rheological properties and water retention of the coating color, affecting the properties of the coated paper. In this study, the effects of CNF and carboxymethyl cellulose (CMC) on the properties of the coated paper were investigated. In contrast to the CMC-coating, the gloss of the CNF-coating was not improved, even when the coating weight was increased, because of the irregular shrinkage of CNF in the wet coating layer through its gel-formation characteristics. The CNF-coating exhibited a much higher ink and vehicle absorption rate than the CMC-coating. The CNF-coating showed lower variation in the printing density depending on the coat weights. Moreover, the open structure of the CNF-coating improved the absorption rate of the coated paper compared to the CMC-coating, resulting in reduced mottling.

Preparation and Performance Investigation of Optimized Cement-Based Sealing Materials Based on the Response Surface Methodology.

A new cement-based sealing material, which used Portland cement (PC) as a raw material and supplemented several gel components, such as accelerant, alkali activator, suspension agent, expansion agent, reinforcing agent, was prepared in this work. The effects of these components on the fluidity, setting time, and expansion rate of these sealing materials were investigated by an orthogonal test. The results show that the water–cement ratio and the reinforcing agent content, the accelerant content and the water–cement ratio, and the expansion agent content and the accelerant content are the most important influencing factors on fluidity, setting time, and expansion rate, respectively. In addition, the regression models and response surfaces of the factors were established using a multiple linear regression method. By this means, the influences of the two main factors on each performance of this sealing material were accurately and intuitively reflected for obtaining the optimal value in the optimization area. The results indicate that the sealing materials possess the best performances when the water–cement ratio is 1.1, the accelerant content is 50%, the expansion agent content is 0.1%, and the reinforcing agent content is 3%, which is corresponding to a fluidity of 360–380 mm, an initial (final) setting time of 60 (80)–80 (100) min, and an expansion rate of 2–12%. Furthermore, the microstructures of the optimized sealing material also reveal that the main hydration products of PC are transformed from layered Ca(OH)2 crystals into fine needle-like AFt crystals and C–S–H gels by the promotion effect of the optimizing ratio, thus leading to a more compact structure of optimized cement-based sealing materials.

Development of Prasman Leaf Suspension in Combination With Pulvis Gummi Arabici and Hydroxyethylcellulose Using Simplex Lattice Design Method

Suspending agents affect the viscosity, storage, and re-dispersal of suspension preparations. This study aims to optimize the combination of suspending agent PGA and hydroxyethylcellulose to obtain the optimum suspension preparation. This suspension formulation uses a computer program design expert version 11 using the Simplex Lattice Design (SLD) method with 2 suspending agents, namely PGA and hydroxyethylcellulose. This SLD method produces 8 formulas. The parameters of these eight formulas were measured including their physical properties, such as organoleptic, pH, viscosity, sedimentation volume, and redispersibility of the preparation. Data were analyzed and produced a graphic equation of each response that gave the optimum suspension formulation. The formula I showed optimal parameters, i.e. physical stability, organoleptic stability, the pH of 5, the viscosity value of 59 cP, 0.04 mL sedimentation, and 95% redispersibility value with the concentration of the suspending agent is 6.25% of PGA and 0.775% of hydroxyethylcellulose, and the desirability value of 0.57. The results indicated that the suspension preparation had the characteristics of low viscosity, the particles settle quickly and are easily re-dispersed. Analysis of ANOVA statistical data on viscosity, sedimentation volume, and redispersibility of suspension preparations showed a p-value 5 or significant meaning that the use of the SLD method affected increasing and decreasing the response value.

Kaolin in pharmaceutical preparations: a review

Background: Kaolin is a clay mineral with Al2Si2O5(OH)4 structure which can be found in sedimentary rocks also known as clay stones. Kaolin consists of clay materials such as quartz, illite, smectite, and hematite, with the largest constituent component being kaolinite. Kaolin is one of the most common minerals with an abundant presence in the earth's crust compared to other minerals, especially in Indonesia. In the pharmaceutical sector, this clay mineral is widely used in Indonesia. Kaolin is known to be a good adsorbent and has good physical, chemical, and surface physicochemical properties. Objective: This review article aims to provide information about the uses of kaolin in the pharmaceutical industry. Methods: This review article was written by conducting a literature search study method in the PubMed, ScienceDirect, and Google Scholar databases. Results: In the pharmaceutical field, kaolin is used as an excipient in various types of medicinal preparations, one of which is as a suspension agent because of its ability to stabilize suspensions in a deflocculated state as an emulsifying agent, crushing agent, filling agent, and drug carrier. As an active substance, kaolin is widely used because it has a therapeutic activity. In the cosmetic industry, kaolin can be administered in a variety of topical dosage forms which act as skin protective agents or sunscreens. Conclusion: Based on the results of the review, it was found that kaolin, with its abundant presence on earth and its great potential in the pharmaceutical field, is used as an active medicinal substance, excipient ingredient, and in the cosmetic field as a sunscreen. Keywords: Kaolin, excipient, active pharmaceutical ingredient, cosmetics

Synthesis and properties of temperature-tolerance resistant hydrophobically associating polymer suspension agent using response surface method

Aiming at the problem that the oil well cement slurry is easy to settle and lose its stability under high temperature environment, and combining with the characteristics of traditional cement admixtures "thickening at low temperature and thinning at high temperature", we developed a kind of high-temperature resistant cement suspension agent. A quadripolymer suspension agent P-AN18 was synthesized by free radical polymerization using 2-Acrylamido-2-methylpropane sulfonic acid (AMPS), acrylamide (AM), quaternary ammonium salt monomer N-N octadecyl dimethyl allyl ammonium chloride (DMAAC-18), and high-temperature resistant monomer N-Vinyl-2-Pyrrolidinone (NVP). The synthesis conditions were optimized using the response surface method (RSM) innovatively, the response surface graph (3D) showed the influence of independent variables on the rheological properties and density difference of cement slurry influence. The hydrophobic association structure and high-temperature resistance mechanism of P-AN18 were analyzed by infrared spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), nanoparticle size analyzer, fluorescence probe test and scanning electron microscope (SEM) in a freezing environment. The effect of P-AN18 on maintaining the stability of cement slurry system at high temperature was evaluated. The results showed that the polymer suspension P-AN18 has good temperature resistance and compatibility with cement slurry. At 200 ℃, P-AN18 can keep the cement slurry system stable, and the density difference between the upper and lower part of the solidified cement column is less than 0.01 g/cm 3 . P-AN18 provides a new method for controlling the settlement stability of high-temperature cement slurry, which is expected to be used to improve the safety and cementing quality of deep well cementing. • Predicting density contrast using RSM model. • Characterizing Polymer suspensions from macro and micro perspectives. • Effective prevention of thermal thinning and particle settling of cement slurry.

Formulation, Physical Characterization and Antioxidant Potential of Silymarin Suspensions and Emulsions

Silymarin, is a therapeutically important flavonoid act as a hepatoprotective agent. However, has a positive effect on metabolism act as a hydrophobic drug but has a very low bioavailability. The aim of the present study was to prepare appropriate formulations of Silymarin in order to enhance its bioavailability. The natural suspending agents like (Xanthan gum, Tragacanth gum, Acacia gum and Iranian gum) were used for the formulation of suspensions, while emulsions were prepared with the combination of surfactant, co-surfactant and oil. The formulations were evaluated for their physical stability, pH, refractive index and conductivity. Among different formulations and suspensions prepared with xanthan gum as a green stabilizing agents were most stable. Emulsions formulated with tween 80 as a surfactant, polyethylene glycol as co-surfactant and olive oil were clear and stable for more than six months. The refractive index, pH and conductivity of the most stable suspension and emulsions were 1.347, 6.9 and 0.18 s/m and 1.43, 6.9, 0.01 s/m respectively. It was concluded that xanthan gum and tween 80 with polyethylene glycol has a good potential to enhance the therapeutic efficiency and stability of silymarin suspension and emulsion.
 

Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing.

Gas drainage is an important method to prevent and control gas disasters. Sealing materials have an important impact on the gas drainage effect. To improve the extraction rate, the configuration and related characteristics of sealing materials were studied in this study. It was found that the fluidity increased gradually with the increase of the dosage of the suspension concentrate (SC). The water–cement ratio was directly proportional to the setting time of the slurry. Also, the mixing amount of the special cement was inversely proportional to the setting time of the slurry. The influence of the amount of foaming agent, special cement, and suspending agent on the expansion rate of the slurry was positive, and the influence gradually weakened. When the water–cement ratio of cement-based materials was 0.6, the special cement content percentage was 6, the suspension agent content percentage was 3, the plasticizer content percentage was 0.7, the early strength agent content percentage was 1.2, and the foaming agent content percentage was 0.2, the sealing effect was the best. The research results suggest that the porosity and pore length of the cement-based material are smaller than those of polyurethane, and its sealing property was better. This could further increase the sealing effect of the gas borehole, thereby facilitating gas extraction.