Production of Carbopol® 974P and Carbopol® 971P Pellets by Extrusion‐Spheronization: Optimization of the Processing Parameters and Water Content

Pellets obtained by extrusion‐spheronization represent multiparticulate dosage forms whose interest in intestinal drug delivery can be potentiated and targeted through bioadhesive properties. However, adhesion itself makes the process difficult or even impossible. The problem of tackiness encountered with bioadhesive wet masses was previously eliminated by the use of electrolytes such as CaCl₂. This approach is known to reduce the viscosity of polyacrylic acids by disturbing the interactions between carboxylate groups on adjacent polymer molecules, thereby decreasing their bioadhesive properties. The present study aimed at producing pellets containing carbomers without addition of electrolytes in order to maintain their bioadhesive potentiality at its maximum. Carbopol® 974P (10%, 15% and 20%) and Carbopol® 971P (10%) were used in combination with Avicel® PH101. The extrusion speed (30, 45, 60, 90, and 150 rpm), spheronizer speed (350, 700, 960, 1000, and 1300 rpm), spheronization time (5, 10, 15, and 20 minutes) and amount of water (45%, 50%, 54%, and 58%) were optimized in order to obtain the highest yield of spherical pellets ranging 710–1000 µm in diameter. For pellets containing 10%, 15% Carbopol® 974P or 10% Carbopol® 971P and 45% water content, 30 rpm extrusion speed, 960 rpm, and 10 minutes spheronization speed and time led to the highest yields and sphericities, respectively, 72% and 0.91, 67% and 0.78, and 76% and 0.80. Production of pellets with 20% Carbopol® 974P could be achieved through the increase of the water content up to 58% and implementation of 30 rpm extrusion speed, 1300 rpm, and 10 minutes spheronization speed and time. The yield and sphericity were 42% and 0.78 respectively.     

Preparation and Evaluation of Floating Risedronate Sodium–Gelucire® 43/01 Formulations

Single and multi-unit floating matrices of risedronate sodium were prepared using Gelucire® 43/01 by melt solidification and melt granulation technique, respectively. The controlled release floating matrices were evaluated for in vitro and in vivo floating ability and in vitro drug release. Effect of aging on Gelucire® 43/01 was evaluated by hot stage microscopy (HSM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), in vitro floating ability, and in vitro drug release. Multi-unit system obtained has shown initial burst release, which was suppressed in single unit system. Both single- as well as multi-unit systems showed increase in rate of drug release on aging due to changes in the properties of the Gelucire® 43/01. Multi-unit matrices obtained by melt granulation were relatively easier for scale up and advantageous if the initial burst release does not cause any significant clinical adversity.     

The Manufacture of the Grinding Wheels Based on the Ca–K Geopolymer Matrix

This article describes the successful manufacture of new grinding wheels based on a binding agent from a clay substance and blast-furnace slag (the Ca–K geopolymer matrix) on industrial presses. Trained factory staff of the company Best – Business, a.s. tested the pressing process for the manufacture of geopolymer-bonded wheels and verified their quality by factory control equipment (Grindo Sonic and Zeiss-Mackensen methods, test of the safe peripheral speed). The results have shown that the Ca–K geopolymer matrix is suitable for grinding-tool preparation and the grinding-wheel properties are comparable with similar products based on the fired ceramic binding agent.     

Interest of Multifunctional Lipid Excipients: Case of Gelucire® 44/14

This paper focuses on the interest of a multifunctional lipid excipient from the lauroyl macrogolglycerides, i.e., Gelucire® 44/14. This compound, characterized by a drop point of 44°C and a HLB (Hydrophilic Lipophilic Balance) of 14, is made of a specific mixture, leading to particular properties. Gelucire® 44/14 forms a fine emulsion in contact with aqueous fluids, inducing a pseudo-solubilization of poorly water-soluble active substances and thus increasing their bioavailability. It could be used either as a binder for immediate release pellets by melt granulation or as a self-emulsifying drug delivery system by capsule molding or as a powder obtained by cryogenic grinding. These different methods and their interests are then discussed.     

The Use of β-Cyclodextrin as a Pelletization Agent in the Extrusion/ Spheronization Process

Abstract

The use of β-cyclodextrin for the preparation of pellets by the extrusion/spheronization process is described for different formulations and processing conditions. Sieve analysis and friability tests were performed to assess the physical and technological characteristics of pellets. Satisfactory products were obtained with β-cyclodextrin contents up to 90% by weight.     

Extrusion processing of Al–Li–Mg–Zr alloy

Abstract

The hot deformation behaviour of an Al–Li–Mg–Zr alloy was characterised in hot torsion and extrusion. The alloy was found to have similar hot ductility to existing high strength aluminium alloys, but this could be maintained at higher temperatures. Billets were extruded over a range of process conditions and a limit diagram was constructed for surface cracking. All the extrusions were found to be partially recrystallised after deformation, but the volume fraction of recrystallisation was a strong function of billet temperature and extrusion ratio. In addition, the unrecrystallised areas contained a recovered substructure where the subgrain size was inversely proportional to the temperature compensated strain rate. The as extruded structure was retained during solution treatment and as a result final mechanical properties were strongly dependent on the extrusion conditions. The use of high billet temperatures and low extrusion ratios gave the best combination of strength and toughness.

MST/839     

Extrusion of AI–Zn–Mg–Cu–Zr alloys

Abstract

Four aluminium alloys of different zinc/magnesium ratio have been studied under various extrusion conditions. The alloys were cast in steel book moulds and subjected to initial thermomechanical treatments. Studies were made of hot extrusions and cold hydrostatic extrusions and in each case the changes in the extrusion parameters were analysed. An attempt has been made to explain some of the extrusion defects which appeared in various extruded sections. The extrusion speed was found to be crucial, since sections developed surface cracks at higher speeds. The extrusion speed was also found to vary inversely with the extrusion ratio, with higher speeds at low ratios. A well defined solute–depleted weld zone was observed on each of the four faces of a square tube extruded using a porthole die. Thermal treatment was not found to improve this weak weld zone. Tubes extruded using a floating-mandrel die withstood pressure testing up to 550 MPa.

MST/43     

Bead Manufacture by Extrusion/spheronization – a Statistical Design for Process Optimization

Abstract

Our recent experience in developing bead formulations for a hydrophilic drug using an extrusion/spheronization technique highlighted several critical processing factors. It was observed that the yield of beads of desired size fraction was significantly affected by water level, water temperature, extrusion speed, spheronization speed, and spheronization time. To further elucidate the roles of these factors, a split-plot factorial design was used to evaluate their effects on the yield of desired size beads, and to determine the optimal levels to maximize the yield. Several 18 kg batches of beads were manufactured using a predetermined level of each factor. The finished beads were sieved using #14 and #20 mesh screens and the yields of beads between #14–20 mesh screen were determined. It was observed that the temperature of water used at the granulation stage significantly affected the bead formation. Using room temperature water for granulation, the significant factors were water level, extruder speed, spheronization speed, spheronization dwell time, and the interactions of water level with extruder speed and spheronization speed with dwell time. Whereas using 50 °C water, significant factors were water level, extruder speed, spheronization speed, and the interaction of water level with spheronization speed. The best fitting regression model describing the relationship between the found yields and the factors was used to find the levels of each factor that would optimize the yield. Two scale-up batches at 100 kg each were manufactured using the optimal process conditions to verify the room temperature model. The yields from the two scale-up batches were within 0.4% of the predicted yield using the regression model.     

Manufacture of photovoltaic cells with hybrid organic–inorganic bulk heterojunction

The aim of this paper is to present the influences of material composition and production conditions of the photovoltaic cells on its parameters as well as the active layer properties. The layers were made of organic compounds: metal phthalocyanine/perylene derivatives. In addition, the effects of TiO₂ and SiO₂ nanoadditives were investigated. The materials used are selected so as to allow P–N junction creation. Deposition technique allows at simultaneous applying the materials leads to obtaining homogeneous dispersion of one material in the other, which determines the formation of bulk P–N junctions. Research includes the estimate of share of individual components in the active layer, then determination of the morphology of surface and optical properties of the same layer and its implementation in photovoltaic structures. The structural researches and morphology of surface investigation were made using transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The optical properties were researched with the use of UV–Visible spectroscope. The parameters of cells have been determined on the basis of current–voltage characteristics. The work undertaken within the framework of article allowed to linking properties of active layers with the parameters of the same cells.     

Manufacture and Study of Switch p–n-Junctions for Cascade Photovoltaic Cells

Technical Physics Letters - Some results of studies on the creation of new junction elements for application in monolithic multijunction InP based photovoltaic cells are presented. A new type of...     

Extrusion of AI–5Fe–7Mn alloy prepared from rapidly solidified powder

Abstract

The characterization of rapidly solidified powders, their extrusion, and the evaluation of mechanical properties of the extrudates have been carried out for an Al–5Fe–7 Mn alloy. In the atomized powder, a metastable non–stoichiometric phase has been identified which transforms to the equilibrium (FeMn)Al₆ phase on heating at elevated temperatures (<400°C). It has been found that inhomogeneous dispersoid distribution and coarsening of phases during preheat causes deterioration of mechanical properties, both at room temperature and at elevated temperatures. It is suggested that control of atomization parameters and use of rapid heating of compacts may be essential to improve the mechanical properties.

MST/174     

Manufacture of three-layer wood–porcelain stone composite board reinforced with bamboo fiber

The objective of this study was to improve bending strength properties of three-layer wood–porcelain stone composite board. The focus of this study was on the effects of orientations and weight ratios of bamboo fiber in face layer on physical and mechanical properties of the board. Three types of board with different orientation of bamboo fibers in the face layer were manufactured: one in which the fibers were oriented at random orientation (R board), another in which the fibers were oriented at unidirectional orientation (U board), and a third in which the fibers were oriented at cross orientation (C board). The physical and mechanical properties of the boards were evaluated based on the Japanese Industrial Standard for Particleboards. The main results obtained were as follows: Bending strength properties of the board were strongly affected by both orientation and weight ratio of bamboo fibers. Perpendicular specimen of C board has larger bending strength properties than U board and the value become larger with increased weight ratio of bamboo fibers. Internal bond strength value decreased with increasing weight ratio of bamboo fibers. The effect of orientation and weight ratios of bamboo fiber on thickness swelling of the board was not significant.     

Enhanced dissolution characteristics of piroxicam–Soluplus® nanosuspensions

In the present study, we have prepared nanosuspensions of piroxicam using Soluplus® as the matrix using aqueous-based conventional ball milling. The comparative physico-chemical characteristics were assessed using PXRD (powder X-ray diffraction), DSC (differential scanning calorimetry), FESEM (field emission scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy) analysis, indicating the nanoformulations displayed lower crystallinity with no chemical interactions between the drug and polymer molecules. The cytotoxicity of the formulations was established from MTT assay performed on Caco-2 cell lines. The release rate of piroxicam from various ratios of drug/polymer nanoparticles was investigated using a USP paddle apparatus. The nanoformulations exhibited higher release of the drug in comparison with the pure drug. The enhanced dissolution characteristics of the drug in the nanoformulations could possibly increase the anti-inflammatory effects of the drug owing to superior bioavailability characteristics.     

Hot Extrusion Effect on the Microstructure and Mechanical Properties of a Mg–Y–Nd–Zr Alloy

Strength of Materials - Mg–Zn–Y–Nd alloy was prepared by casting and hot extrusion. The microstructure and mechanical properties of OM, SEM, XRD, TEM, and tensile tests were...     

Effect of Liquid–Solid Extrusion on the High-Temperature Compressive Properties of Csf/Mg Composites

Short carbon fiber reinforced Mg matrix composites (C_sf/Mg) were prepared by an infiltration–extrusion integrated technique in which pressure infiltration and liquid–solid extrusion are performed continuously. Their compressive properties were evaluated in the temperature range 20–300°C, and compared with C_sf/Mg composites fabricated by only pressure infiltration technique. The results show that after liquid–solid extrusion, the fiber tended to align along the extrusion direction, and a refined-grain microstructure was obtained, thereby contributing to a significant increase in both compressive strength and yield strength up to 200°C, but they are abnormally lower than those of the infiltrated composite at 300°C due to fiber rotation and a different deformation mechanism related to the finer grain structures.     

Processing of Al–SiCp Metal Matrix Composites by Pressureless Infiltration of SiCp Preforms

An optimum method for producing Al-SiC_p metal matrix composites was developed by determining the optimum conditions for wetting SiC by aluminum and the optimum parameters for pressureless infiltration of SiC_p preforms. The quantitative effect of magnesium and silicon additions to aluminum, free silicon on the SiC substrate, nitrogen gas in the atmosphere, and process temperature on the wetting characteristics of SiC by aluminum alloys was investigated using the sessile drop technique. The contribution of each of these parameters and their interactions, in terms of a relative power, to the contact angle, surface tension, and driving force for wetting were determined. In addition, an optimized process for enhanced wetting was suggested and validated. The optimum conditions for wetting SiC by aluminum that were arrived at were used to infiltrate SiC_p preforms and the mechanical properties of the resulting metal matrix composites were measured. The effect of SiC particle size, infiltration time, preform height, vol.% SiC in the preform, and Si coating on the SiC particles on the pressureless infiltration of SiC_p compacts with aluminum was investigated and quantified. The contribution of each of these parameters and their interactions to the retained porosity in the composite, the modulus of elasticity, and the modulus of rupture were determined. Under optimum infiltration conditions, metal matrix composites with less than 3% porosity, over 200 GPa modulus of elasticity, and about 300 MPa modulus of rupture were routinely produced.     

Microstructure and Properties of As-Cast Mg–2.0Sn–1.0Zn–1.0Y–0.3Zr Alloys at Different Extrusion Ratios

Herein, the effect of hot extrusion with different extrusion ratios (λ = 6, 8, 10, and 12) on the microstructure evolution and properties of as-cast Mg–2.0Sn–1.0Zn–1.0Y–0.3Zr magnesium alloys, using optical microscopy (OM), scanning electron microscopy (SEM), immersion corrosion and electrochemical corrosion experiment, and tensile testing, is investigated. The results show that the Mg₁₄SnY and Mg₆SnY precipitated phases exist in the alloy before and after extrusion. After hot extrusion, the second phase of the alloy is broken into particles along the extrusion direction, whereas the grain size is significantly reduced, and dynamic recrystallization and deformed grains exist in the microstructure. The mechanical properties of the extruded alloy improve, but the corrosion resistance weakens. When the extrusion ratio is λ = 10, the extruded alloy exhibits relatively good mechanical properties and corrosion resistance. The corrosion behaviors of the extruded alloys are affected by both the grain size and galvanic corrosion. In the initial stage of corrosion, intergranular corrosion plays a major role in reducing the corrosion resistance of the extruded alloys. With prolonged corrosion time, galvanic corrosion has a more significant effect on weakening the corrosion resistance of the extruded alloys.