Increasing Polymer Concentration Research Articles

Development and Evaluation of Floating Microspheres of Sumatriptan Succinate using Ethyl Cellulose and Mucilage Extracted from Vigna Mungo

Aim: The present investigation is to formulate and evaluate gastroretentive floating microspheres for sumatriptan succinate. Gastric retention is widely used approach to retain dosage form in stomach and to enhance absorption of drugs.
 Methods: The gastroretentive floating microspheres was prepared by two different techniques as solvent evaporation and W/O/W multiple emulsion technique. Ethyl cellulose, HPMC K4M polymer and mucilage extracted from Vigna Mungo in various proportions were used for formulation of microspheres. Combination of ethyl acetate and acetone in different proportion was used as organic phase and the microspheres were characterized for particle size, shape, morphology, percentage yield, entrapment efficiency, drug loading, In-Vitro Floating/Buoyancy study, In-vitro Floating/Buoyancy study and release kinetics.
 Results: The average particle size of all batches was found in the range 100 to 210 μm and the entrapment efficiency of all formulations was found in the range of 17.46 % to 59.28 %.Total floating time for Sumatriptan succinate floating microspheres was observed more than 12 h. The In-Vitro drug release study was performed for all formulations showed drug release in controlled manner.
 Conclusion: The particle size was increased with increased polymer concentration and it showed that polymer concentration has an impact on the entrapment efficiency. Ethyl cellulose microspheres showed more entrapment and sustained delivery of sumatriptan Succinate than microspheres prepared by combination of Ethyl cellulose: HPMC K4M and Ethyl cellulose: Vigna mungo mucilage.

Mechanoadaptive injectable hydrogel based on poly(γ-glutamic acid) and hyaluronic acid regulates fibroblast migration for wound healing

Injectable hydrogels have shown therapeutic effects on wound repair, but most of them exhibit poor mechanical strength. The impacts of stiff injectable hydrogels on cell behavior and wound healing remain unclear. Herein, an injectable hydrogel was developed based on thiolated poly(γ-glutamic acid) (γ-PGA-SH) and glycidyl methacrylate-conjuated oxidized hyaluronic acid (OHA-GMA). Thiol−methacrylate Michael chemistry-mediated post-stabilization and increase of polymer concentration were found to improve the mechanical strength of γ-PGA-SH/OHA-GMA hydrogel. Moreover, in vitro studies confirmed its biodegradability, biocompatibility, and self-healing property. Using the mechanically-tunable hydrogel, it further showed that fibroblasts migrated faster on the surface of stiffer hydrogel, but infiltrated slowly inside it compared with softer hydrogel. In animal experiments, the injectable hydrogel could promote wound healing by increasing collagen deposition and vascularization. In summary, γ-PGA-SH/OHA-GMA hydrogel is able to regulate migration and infiltration of fibroblasts by altering stiffness and offers effective in situ forming scaffolds towards skin tissue regeneration.

Design, Formulation and Characterization of Microspheres containing Mesalamine for the Treatment of Ulcerative Colitis

The purpose of the present study was to prepare, characterize and evaluate the colon-targeted microspheres of mesalamine for the treatment and management of ulcerative colitis (UC). Microspheres were prepared by the ionic-gelation emulsification method using tripolyphosphate (TPP) as cross linking agent. The microspheres were coated with Eudragit S-100 by the solvent evaporation technique to prevent drug release in the stomach. The prepared microspheres were evaluated for surface morphology, entrapment efficiency, drug loading, micromeritic properties and in-vitro drug release. The microspheres formed had rough surface as observed in scanning electron microscopy. The entrapment efficiency of microspheres ranged from 43.72% - 82.27%, drug loading from 20.28% - 33.26%. The size of the prepared microspheres ranged between 61.22-90.41μm which was found to increase with increase in polymer concentration. All values are statistically significant as p<0.05. The release profile of mesalamine from eudragit-coated chitosan micro-spheres was found to be pH dependent. It was observed that Eudragit S100 coated chitosan microspheres gave no release in the simulated gastric fluid, negligible release in the simulated intestinal fluid and maximum release in the colonic environment. It was concluded from the study that Eudragit-coated chitosan microspheres were promising carriers for colon-targeted delivery of Mesalamine.

Formulation and Evaluation of Ranitidine Hydrochloride Loaded Floating Microspheres for the Treatment of Gastric Ulcer

The study was aimed to prepare gastro retentive floating microsphere of Ranitidine Hydrochloride by Ionotropic Gelation technique and solvent evaporation technique by using the different carriers’ ratios (Carbopol 934, Chitosan, and sodium alginate). Both natural and synthetic polymers have been used to prepare floating microspheres and evaluated the relevant parameters. There was no drug and carrier interactions assessed from FTIR. Depending upon the ratio, the percentage yield was found between 58.33% to 90.38%. in all formulations. The surface morphology of microspheres was characterized by SEM and it was discrete, spherical in shape with rough outer surface and showed free flowing properties. The mean particle size of microspheres significantly increases with increasing polymer concentration and the range between 99.92±1.221 to 168.23±1.963 µm. Among all the formulations, RF3 showed high drug entrapment efficiency (87.52%). The percentage in-vitro buoyancy of the floating microspheres was in the range of 66.92% to 81.52%. The in-vitro drug release study revealed that RF3, RF6 and RF9 Formulations having 89.97%,92.91%,93.68% drug released at the end of dissolution studies respectively. It could be concluded that the developed floating microsphere of Ranitidine Hydrochloride can be used for prolonged release in stomach. Therefore improving the bioavailability and patient compliance.

Inorganic-organic composite solid electrolyte based on cement and Polyacrylamide prepared by a synchronous reaction method

Inorganic-organic composite solid electrolyte (CSE) has a high potential for future energy storage. Compared with ceramic-based CSE, cement-based CSE can be prepared at room temperature, which is conducive to incorporation of polymer into CSE. However, the content of polymer in CSE is limited to the small level, which hinders the performance of the electrolyte. In this work, a novel synchronous reaction method (SRM) is proposed to prepare CES, which can exceed the content limit of polymer remarkably. Through SRM, cement hydration and polymer polymerization are simultaneously carried out to solve the problem of cement slurry fluidity caused by the addition of polymer. Infrared and 1H-NMR spectra confirm that the CSE has been successfully prepared, and Polyacrylamide (PAM) can be detected in CSE. GPC results show that the molecular mass of PAM in the CSE increases with the monomer content. SEM results reveal that PAM and hardened cement are well combined and evenly distributed at the micro level. The microstructure, ionic conductivity and compressive strength of CSE change considerably with the polymer content. In general, with the increase of polymer content, the internal structure is gradually improved, also the ionic conductivity and compressive strength are improved remarkably. The multi-functionality results indicate that the CSE prepared by synchronous reaction method with 20 wt.% PAM shows the best combination of the ionic conductivity (10.52 mS/cm) and the compressive strength (53.78 MPa). An all-solid supercapacitor (ASS) was assembled by the solid electrolyte and rGO/Ni foam composite electrodes, which shows good electrochemical energy storage performance. Therefore, the solid electrolyte synthetized with SRM provides a promising way for the application of all-solid electrochemical energy storage.

Formulation, In Vitro Evaluation, and Toxicity Studies of A. vulgaris-co-AAm Carrier for Vildagliptin

This study investigated the use of Artemisia vulgaris L. seed mucilage as a new excipient for sustained delivery of Vildagliptin. Copolymeric carrier of A. vulgaris seed mucilage-co-AAm was devised by using acrylamide (AAm) as a monomer, methylene-bis-acrylamide (MBA) as a crosslinker, and potassium persulfate (KPS) as an initiator through free radical polymerization. Different formulations of A. vulgaris-co-AAm were devised by varying contents of polymer, monomer, crosslinking agent, initiator, and reaction temperature. Copolymeric structures were characterized through XRD analysis, Fourier transform infrared (FTIR) spectroscopy, TGA and DSC analysis, and scanning electron microscopy. Porosity, gel fraction, and Vildagliptin loading capacity of copolymers were also established. Swelling and in vitro drug release studies were conducted. XRD evaluation showed the alteration of the crystalline structure of Vildagliptin into an amorphous form. FTIR analysis confirmed the successful grafting of AAm to A. vulgaris seed mucilage backbone. Porosity was increased with increasing polymer concentration and reaction temperature while it was decreased with an increasing amount of AAm, MBA, and KPS. Gel content was decreased with increasing polymer concentration and reaction temperature while it was increased with an increasing amount of AAm, MBA, and KPS. Acute oral toxicity of copolymeric network was done in animal models to evaluate the safety. Copolymers showed the same swelling behavior at all pH 1.2, 4.5, 6.8, and 7.4. Vildagliptin release from copolymer showed a cumulative trend by increasing polymer content and reaction temperature, while a declining trend was observed with increasing contents of monomer, crosslinking agent, and initiator. Sustained release of Vildagliptin was observed from copolymers and release followed the Korsmeyer-Peppas model. From the acute oral toxicity studies, it is evident that newly synthesized copolymeric carriers are potentially safe for eyes, skin, and vital organs.

A statistical analysis on the influence of process and solution properties on centrifugally spun nanofiber morphology

Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN) nanofibers have been widely studied for many applications including energy storage, filtration, sensors, and biomedical applications. Nanofiber morphology, specific surface area, porosity and average fiber diameter are important to determine the performance of nanofibers in these fields. In centrifugal spinning, nanofiber morphology and average fiber diameter are influenced by solution properties and process parameters including rotational speed, feeding rate, collector distance, and nozzle diameter. In this study, the effect of solution concentration, rotational speed, feeding rate, collector distance and nozzle diameter on average fiber diameter and fiber morphology were studied and statistical analysis was performed to determine the main factors. Optimum solution and process parameters were determined as well. Increased average fiber diameter was seen with increasing polymer concentration and nanofibers produced at 4000 rpm with the feeding rate of 60 ml/h had the lowest average fiber diameter for all studied nozzle sizes (0.3 mm, 0.5 mm and 0.8 mm). 8 wt. % PAN solution was centrifugally spun with the rotational speed of 4000 rpm, feeding rate of 60 ml/h, collector distance of 20 cm and nozzle diameter of 0.3 mm and bead free nanofibers with the average fiber diameter of 680 ± 87 nm was observed.

Microsponges for controlled release and enhanced oral bioavailability of carbamazepine

The oral absorption and hence the oral bioavailability of carbamazepine (CBZ) is variable even after administration of rapidly dissolving formulation. This problem was attributed to supersaturation of CBZ and transformation to the less soluble carbamazepine dihydrate (CBD). Accordingly, formulation of sustained release products of CBZ is a promising approach to overcome this problem. Microsponges are an emerging formulation which can help in this direction. The aim of this work was to optimize the composition of microsponges for better encapsulation and sustained release of CBZ for oral administration. CBZ microsponges were prepared using quasi emulsion solvent diffusion technique with varying composition of ethyl cellulose and polyvinyl alcohol (PVA). Microsponges were evaluated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction. Production yield, entrapment efficiency and surface morphology of microsponges were assessed in addition to drug release. Optimum formulation was administered orally to albino rabbits to evaluate the oral bioavailability with reference to unprocessed CBZ. The Instrumental analysis reflected the encapsulation of CBZ in amorphous or molecularly dispersed form in the microsponges. The size and entrapment efficiency of the microsponges increased with increasing polymer contents. This was associated with reduction in CBZ release. Optimum formulation enhanced the oral absorption of CBZ. This was manifested by 2.6-fold increase in the area under the plasma concentration versus time curve compared to that of unprocessed CBZ. The study introduced microsponges as promising carriers for sustained oral delivery of CBZ.

Adsorption and Desorption of Polymers on Bioinspired Chemically Structured Substrates.

Natural biological surfaces exhibit interesting properties due to their inhomogeneous chemical and physical structure at the micro- and nanoscale. In the case of hair or skin, this also influences how waterborne macromolecules ingredients will adsorb and form cosmetically performing deposits (i.e., shampoos, cleansers, etc.). Here, we study the adsorption of hydrophilic flexible homopolymers on heterogeneous, chemically patterned substrates that represent the surface of the hair by employing coarse-grained molecular dynamics simulations. We develop a method in which the experimental images of the substrate are used to obtain information about the surface properties. We investigate the polymer adsorption as a function of polymer chain length and polymer concentration spanning both dilute and semidilute regimes. Adsorbed structures are quantified in terms of trains, loops, and tails. We show that upon increasing polymer concentration, the length of tails and loops increases at the cost of monomers belonging to trains. Furthermore, using an effective description, we probe the stability of the resulting adsorbed structures under a linear shear flow. Our work is a first step toward developing models of complex macromolecules interacting with realistic biological surfaces, as needed for the development of more ecofriendly industrial products.

Non-Newtonian Two-Phase Flow in a Turbulent Pipe.(Dept.M)

The presented study in this paper is concerned with the performance of an orifice meter handling water-polymer solution, water-sand mixture (two-phase flow), and water-sand mixture with polymer additives (two-phase non-Newtonian flow). An ASME recommendation orifice meter was constructed and installed in a hydraulic circuit. Sand of different grain sizes (0.063-0.125, 0.125-0.25 and 0.25-0.5 mm) with concentrations 0.25%, 0.5%, 1.0% and 1,5% by weight was tested. One type of polymers (polyacrylamid) was used with an average concentrations of 20, 30 and 40 wppm. The results show that both polymer and sand concentrations affects the coefficient of discharge of the orifice meter. The coefficient of discharge was found to be increased with increasing polymer concentration, while increasing sand concentration decreases the coefficient of discharge. The used sand grain sizes has no effect on the coefficient of discharge.

The Performance of Orifice Meter Handling Two-Phase Non-Newtonian Flow.(Dept.M)

The presented study in this paper is concerned with the performance of an orifice meter handling water-polymer solution, water-sand mixture (two-phase flow), and water-sand mixture with polymer additives (two-phase non-Newtonian flow). An ASME recommendation orifice meter was constructed and installed in a hydraulic circuit. Sand of different grain sizes (0.063-0.125, 0.125-0.25 and 0.25-0.5 mm) with concentrations 0.25%, 0.5%, 1.0% and 1,5% by weight was tested. One type of polymers (polyacrylamid) was used with an average concentrations of 20, 30 and 40 wppm. The results show that both polymer and sand concentrations affects the coefficient of discharge of the orifice meter. The coefficient of discharge was found to be increased with increasing polymer concentration, while increasing sand concentration decreases the coefficient of discharge. The used sand grain sizes has no effect on the coefficient of discharge.

Effects of preparation parameters on the properties of the crosslinked pectin nanofiber mats

Pectin nanofiber mats prepared with periodate oxidation–electrospinning–adipic acid dihydrazide crosslinking strategy are promising for biomedical applications. In this study, we systematically examined the effects of electrospinning and crosslinking conditions on the properties of pectin nanofiber mats. The properties of mats were tunable in the range of 200–400 nm fiber size, 11–21% ADH residue content, 13–28 times absorbency, 13°–21° contact angle, 2 weeks or longer degradation time, 1.5–2.2 MPa tensile strength, 40–70% elongation, and 0.25–0.27 g/(cm2·24 h) permeability. Increasing polymer concentration, adipic acid dihydrazide amount, time or temperature could increase fiber size and its tensile strength, and decrease the absorbency, hydrophilicity, degradation rate, and elongation. These results indicate that controlling the process parameters can effectively regulate the properties of pectin nanofiber mats and meet the requirements of various biomedical applications.

The Effects of Weak Viscoelasticity on Enhanced Particle Removal for CMP

Highly elastic solutions have been shown to increase particulate removal from silicon wafers, indicating the possibility for reduced reliance upon hazardous chemicals and expensive technologies during post-CMP cleaning processes. We explored the onset of this enhanced removal using micron-sized silica particles in rinsing and siphoning experiments with polymer fluids of high molecular weights that ranged from dilute to entangled concentrations. Increases in particle removal with less than 100 ppm of polymer were observed using both methods, with 10% increased removal observed in the rinsing experiment and 4% increased removal in the siphoning experiment relative to water. Further increases in polymer concentration increased removal significantly, as the solutions entered the semidilute regime. Highly concentrated solutions showed “streaking” patterns, consistent with the viscoelastic nature of the solution. Additionally, we examined particle removal as a spatially dependent parameter in siphoning experiments, showing a plateau of significant removal near the siphon with a sharp decay to a constant value at distances farther away from the siphon.Rheological characterization of the siphoning and rinsing polymer solutions was used to explore relationships between observed removal and solution properties. Increases in particle removal with solutions having nearly indistinguishable shear rheology and immeasurable extensional character were observed, indicating the need for more precise methods for extensional characterization of dilute polymer solutions. The application of polymer solutions to particle-removal processes has the potential to simplify post-CMP cleaning and reduce the environmental impact that is associated with present particle-removal chemistries. Figure 1: Removal profile of micron-sized silica particles on glass slides that were subjected to fluid siphoning. Crosshairs indicate the point on the glass slide directly under siphon. Siphoning solutions consisted of water (a), and poly (ethylene oxide) at concentrations of 50, 100, 500, 1000, and 5000 parts-per-million (b-f, respectively). Particulate area was determined by the total pixel count of silica particles in each image. Removal profiles for dilute solutions (a-c) show similar spatial dependence with mild increases in average removal. Removal profiles for semidilute solutions (d-e) show clear radial dependence while the concentrated solution showed behavior associated with significant elastic character. Figure 1

Formulation and Evaluation of Sustained Release Matrix Tablets of Aceclofenac

This study aimed to improve the dissolution rate of aceclofenac and release the drug in a controlled manner over a period of 24 hours. Matrix tablets were prepared by direct compression method, using hydrophilic polymers (HPMC/guar gum). Matrix tablets were prepared by wet granulation method using different hydrophilic polymers (HPMC/guar gum). Tablets were evaluated for in vitro drug release profile in phosphate buffer with pH 6.8 (without enzymes). The thickness and hardness of prepared tablets were 3.23 ± 0.035 to 3.28 ± 0.008 mm and 3.26 ± 0.115 to 3.60 ± 0.200 kg/cm2, respectively. The friability was within the acceptable limits of pharmacopoeial specifications (0.31 to 0.71%), which indicates the good mechanical strength of the tablets. Drug release was retarded with an increase in polymer concentration due to the gelling property of polymers. The in vitro drug release from the proposed system was best explained by Higuchi’s model, indicating that drug release from tablets displayed a diffusion-controlled mechanism. The results clearly indicate that guar gum could be a potential hydrophilic carrier in developing oral controlled drug delivery systems. Based on the study results, formulations F8 was selected as the best formulation.

Stress-stain behavior, elastic modulus, and toughness of the soilcrete modified with powder polymers

This article discusses the effect of two types of polymer on the stress–strain (σ–ε) behavior, elastic modulus and total toughness of soilcrete. Soilcrete properties modified with two types of polymer content up to 0.20% (% wt.) were tested. The σ–ε behavior of modified soilcrete with polymeric admixtures was examined for curing periods up to 28 days. Additional polymer content maintains the flowability of soilcrete with the range of 105 to 110% as recommended by ASTM C109, and the water/cement ratio (w/c) decreased by 14.5 to 25.5% with the addition of polymer. The compression strength of soilcrete increased by 72 to 153% when 0.20% of the polymer was added to the soilcrete, and therefore the compression toughness was increased with increasing polymer content. Modifying the soilcrete with polymer content increased the initial elastic modulus (Ei) of soilcrete by 55% to 195% according to polymeric admixture types, curing age (t), w/c, and polymeric admixture percent. With increasing polymer content, the soilcrete samples become brittle, and the strain at failure is reduced. Adding polymeric admixture creates an amorphous gel that fills the spaces between cement particles with working fibers net or meshes covering the sand particles, which cause a reduction in the voids, porosity and increasing the density of the soilcrete; subsequently, the mechanical properties significantly increased. The nonlinear Vipulanandan p-q model was employed to predict the σ–ε relationship of the modified soilcrete with polymer and was compared with the β model prediction. Statistical assessment tools were used to evaluate the compressive stress–strain models and nonlinear approaches to predict the compressive strength and the modulus of elasticity as a function of water/cement ratio, curing age, and amount of the polymers.

Facile preparation of water-soluble multiwalled carbon nanotubes bearing phosphorylcholine groups for heat generation under near-infrared irradiation

In the present study, water-soluble molecular complexes between carboxylic acid-functionalized multiwalled carbon nanotubes (MWCNTs) and biocompatible poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) were prepared by hand grinding. MWCNTs could be solubilized in phosphate-buffered saline using this simple method. The suspended concentration of MWCNTs was found to increase with increasing polymer concentration and pH of the solution. Heat generation from the complexes was studied upon irradiation with near-infrared (NIR) radiation at a wavelength of 808 nm. The results demonstrated that MWCNTs absorbed light and generated heat when the molecular complex was irradiated by NIR. The solution temperature increased with increasing MWCNT concentration and irradiation time. This study presents a facile method for preparation of water-soluble molecular complexes between carboxylic acid-functionalized multiwalled carbon nanotube and poly(2-methacryloyloxyethyl phosphorylcholine) (MWCNTs/PMPC) by hand grinding. MWCNTs could be solubilized in aqueous environment with higher suspended concentrations when increasing polymer concentration and pH of the solution. MWCNTs/PMPC adsorbed light and induced heat generation to reach the temperature required for photothermal therapy (PTT) when the complexes were irradiated by near-infrared (NIR) at a wavelength of 808 nm. The water-soluble MWCNT complex covered by biocompatible PMPC is a promising candidate for PTT application.

SOLID DISPERSION OF NEBIVOLOL HYDROCHLORIDE IMPREGNATED BUCCAL PATCH: FORMULATION AND CHARACTERIZATION

Objective: The objective of the present investigation was to design and characterize a mucoadhesive buccal patch of Nebivolol hydrochloride in order to administer a small dose of a drug to treat hypertension effectively and thereby avoiding disadvantages such as patient noncompliance and low bioavailability.
 Methods: The buccal patches were prepared by solvent casting method. The polymers used to formulate patches were HPMC K 15 M, PVP K 30, and propylene glycol was used as plasticizer and ethanol as the solvent. The drug-polymer compatibility studied was conducted by FTIR.
 Results: All the developed Patches had good transparency and stability. All formulated patches showed pH in the range of 6.49 to 7.22, and drug content was more than 90%. The folding endurance value showed that the patches are flexible and non-brittle. The in vitro residence time was found to more than 30 min. Thickness, % moisture absorption, and % moisture loss values were in a normal range. The drug release study was conducted for 8 h, and it was found drug release was decreased with the increase in polymer concentration. The in vitro release profiles of the drug from all the formulations appeared to follow Korsmeyer Peppa's exponential model, and release exponent (n) was found to be more than 0.45 so that the release can be characterized by Non–Fickian (anomalous) diffusion.
 Conclusion: From the results, it was concluded that drug released from formulated buccal patches follows sustained release pattern, Hence can be used for the treatment of the hypertensive patient.

An Advanced Material with Synergistic Viscoelasticity Enhancement of Hydrophobically Associated Water‐Soluble Polymer and Surfactant

In order to prepare materials with controllable properties, changeable microstructure, and high viscoelasticity solution with low polymer and surfactant concentration, a composite is constituted by adding surfactant (sodium dodecyl sulfate, SDS) to hydrophobically associated water-soluble polymer (abbreviated as PAAC) solution. The viscoelasticity, aggregate microstructure, and interaction mechanism of the composite are investigated by rheometery, Cryo-transmission electron microscopy (Cryo-TEM), and fluorescence spectrum. The results show that when the mass ratio of polymer to surfactant is 15:1, the viscosity of the composite reaches the maximum. The viscosity of the composite system increases hundredfold. The viscosity plateau under dynamic shear is generated. The composite has the properties of high viscoelasticity, strong shear thinning behavior, and good salt tolerance, and temperature resistance. The maximum viscosity of the composite is shown at the salinity of 20000mg L-1 . In addition, there is no phase separation in the composite with the increase of polymer and surfactant concentration, which indicates the good stability of the system. It is proposed a method to obtain a high viscoelasticity solution by adding surfactants without wormlike micelles to a hydrophobically associated water-soluble polymer solution.

Foaming Properties and Foam Structure of Produced Liquid in Alkali/Surfactant/Polymer Flooding Production

AbstractAlkali/surfactant/polymer (ASP) flooding process is proven to be vitally effective for enhancing oil recovery (EOR) in the oil industry. However, foaming behavior is generated by the breakthrough of chemical agents in the produced liquid and is increasingly concerned as a terrible problem during production. A set of experiments were recently performed to investigate the effects of foaming properties of ASP flooding produced liquid. The factors affecting foaming capacity and foam stabilization were discussed, and the differences in foaming properties of produced liquid between the strong base and weak base ASP flooding were first compared. The results indicated that in addition to temperature and pressure, the concentrations of chemical agents in the produced liquid were responsible for the foaming properties and foam stabilization. The foaming capacity could enhance 3–7% at 45 °C compared with a lower temperature of 35 °C. The average comprehensive index of the foam could increase from 2.2 × 105 at 29 psi to 2.5× 105 at 73 psi. The regularity of Plateau borders was highlighted at higher pH and surfactant concentration and thus facilitated the foam stabilization. The liquid film thickened and its shape expanded to the state of maintaining foam stabilization with the increase of polymer concentration. Furthermore, the foaming behavior of produced liquid in strong base ASP flooding production is much-more troublesome than that in weak base ASP flooding production. This study is significant in that it further supports the development of efficient treatment technology for produced liquid in the oilfield.

Evaluation of the effect of 3D porous Chitosan-alginate scaffold stiffness on breast cancer proliferation and migration.

Breast cancer (BCa) is one of the most common cancers for women and metastatic BCa causes the majority of deaths. The extracellular matrix (ECM) stiffens during cancer progression and provides biophysical signals to modulate proliferation, morphology, and metastasis. Cells utilize mechanotransduction and integrins to sense and respond to ECM stiffness. Chitosan-alginate (CA) scaffolds have been used for 3D culture, but lack integrin binding ligands, resulting in round cell morphology and limited cell-material interaction. In this study, 2, 4, and 6wt% CA scaffolds were produced to mimic the stages of BCa progression and evaluate the BCa response to CA scaffold stiffness. All three CA scaffold compositions highly porous with interconnected pores and scaffold stiffness increased with increasing polymer concentration. MDA-MB-231 (231) cells were cultured in CA scaffolds and 2D cultures for 7 d. All CA scaffold cultures had similar cell numbers at 7 d and the 231 cells formed clusters that increased in size during the culture. The 2wt% CA had the largest clusters throughout the 7 d culture compared with the 4 and 6wt% CA. The 231 cell migration was evaluated on 2D surfaces after 7 d culture. The 6wt% CA cultured cells had the greatest migration speed, followed by 4wt% CA, 2D cultures, and 2wt% CA. These results suggest that 231 cells sensed the stiffness of CA scaffolds without the presence of focal adhesions. This indicates that a non-integrin-based mechanism may explain the observed mechanotransduction response.