I. Lassila

Controlled Expansion of Supercritical Solution: A Robust Method to Produce Pure Drug Nanoparticles With Narrow Size-Distribution.

We introduce a robust, stable, and reproducible method to produce nanoparticles based on expansion of supercritical solutions using carbon dioxide as a solvent. The method, controlled expansion of supercritical solution (CESS), uses controlled mass transfer, flow, pressure reduction, and particle collection in dry ice. CESS offers control over the crystallization process as the pressure in the system is reduced according to a specific profile. Particle formation takes place before the exit nozzle, and condensation is the main mechanism for postnucleation particle growth. A 2-step gradient pressure reduction is used to prevent Mach disk formation and particle growth by coagulation. Controlled particle growth keeps the production process stable. With CESS, we produced piroxicam nanoparticles, 60 mg/h, featuring narrow size distribution (176 ± 53 nm).

P1H-3 Monitoring Bio-Polymer Film Formation with Ultrasonic Spectroscopy Technique

Bio-based polymers have potential to replace plastics in packages. Recently, degradable bags made of potato starch, have become commercially available. One promising starting material for packing films is xylan, which is heteropolysaccharide extracted from oat grain husks. We report on efforts to monitor the mechanical properties of xylan films during layer formation. This characterization should allow recipe optimization and engineering of the layer end-use properties. The aqueous polymer suspension was placed on a quartz glass cylinder that additionally served as an acoustic delay line. The drying sample was probed from below with an ultrasonic pulse-echo set-up. Pulses that reflected from sample-quartz glass boundary were recorded. The phase and the amplitude content of these pulses were used to obtain the temporal development of the shear modulus and the out-of-plane longitudinal modulus of forming layers. In the end stage the longitudinal modulus of sorbitol plasticized xylan layer was (22.3plusmn4.2) GPa. This figure for glycerol plasticized xylan was (6.8plusmn0.7) GPa

Ultrasonic monitoring of paper and tablet coating stiffness during layer formation.

We report on efforts to monitor the shear properties and the out-of-plane stiff- ness properties of polymer coatings during layer formation. The formation determines largely the coating structure that significantly impacts end-use properties of coated prod- ucts such as the printability of coated paper and the drug-release rate of a tablet. Ultrasonic probing was conducted with a pitch-catch set-up. A 4.3 MHz ultrasonic shear wave tone burst propagated obliquely towards the coating through an aluminum slab on top of which the coating was applied and then reflected from the aluminum- sample interface. The shear modulus of the coating was calculated from the amplitude and phase of the received signal when the shear wave impedance of the aluminum and the density of the coating were known. The longitudinal mode velocity in the coating was obtained with a classical 18 MHz longitudinal wave orthogonal pulse-echo measurement through the coating. The samples were typical coating materials used in the pharmaceutical and paper industry. The tablet coating was a mixture of hydroxypropyl methylcellulose (HPMC, 12.5%wt), lactose (12.5%wt), glycerol (20%wt) and water (55%wt). The paper coating con- sisted of calcium carbonate pigment (CaCO3, 58%wt), styrene butadiene latex (6%wt) and water (36% wt). For these two samples the shear moduli and longitudinal mode velocities are pre- sented during layer consolidation. From the longitudinal mode velocity and the density information the end stage Youngs modulus estimate was determined to be (11±3) GPa for the tablet coating and (23±7) GPa for the paper coating. I. INTRODUCTION It is important to understand the coating formation occurring when high-quality coated products are manufactured. In case of printing papers the coating has a large impact on the appearance as well as on the printability (1). Moreover, during printing the coating has to endure extensional and contracting forces in the thickness direction caused by the stickiness of the off-set ink. With drug tablets the coating layer formation influences the coating adhe- sion to the tablet bulk. Furthermore, the coating layer determines the drug release rate during intestinal tablet transport. Coating characteristics also determine the form and chemical stability of the tablet during storage (2,3). Therefore, it is beneficial to under- stand the coating formation more thoroughly than currently. The aim of this work is to monitor a) the shear modulus with an ultrasonic shear wave reflection measurement, and b) the longitudinal mode velocity by means of a longi- tudinal pulse echo measurement, in ex-situ coating layers during formation. These results could provide mechanical input parameters for layer formation simulations. It is also sought after to be able to understand the layer formation process more thoroughly, which allows coating process optimization in the paper and pharmaceutical industries.

Lyophilic matrix method for dissolution and release studies of nanoscale particles

Graphical abstract Figure. No Caption available. HighlightsThe lyophilic matrix (LM) method for dissolution studies of powders, nanoparticles, and particulate systems is introduced.LM method avoids issues encountered with current dissolution methods such as the diffusion barrier and dispersion of particles.LM method permits rapid contact with the dissolution medium.The method separates the dissolved species from the non‐dissolved particles. Abstract We introduce a system with a lyophilic matrix to aid dissolution studies of powders and particulate systems. This lyophilic matrix method (LM method) is based on the ability to discriminate between non‐dissolved particles and the dissolved species. In the LM method the test substance is embedded in a thin lyophilic core‐shell matrix. This permits rapid contact with the dissolution medium while minimizing dispersion of non‐dissolved particles without presenting a substantial diffusion barrier. The method produces realistic dissolution and release results for particulate systems, especially those featuring nanoscale particles. By minimizing method‐induced effects on the dissolution profile of nanopowders, the LM method overcomes shortcomings associated with current dissolution tests.

1 MHz ultrasonic needle transducer

Broadband pointwise contacting excitation of Lamb waves into sample materials remains a problem. We present a design of a broadband ultrasonic contacting needle transducer. A prototype was built and a transmit waveform was measured using a laser Doppler vibrometer. 1 MHz bandwidth is achieved at -18dB level while the center frequency was 210 kHz. This kind of transducer could permit quantifying the stiffness of plate- and fiber-like samples in industrial environments.

Anisotropy of longitudinal and shear wave velocities in rocks under controlled pressure

Reliable interpretation of seismic surveys and borehole loggings requires that the seismic velocities and anisotropies of the bedrock are taken into account. There will be discrepancies in estimated reflector locations if one assumes isotropic velocity. Moreover, improved accuracy in determining reflector locations reduces drilling efforts in ore exploration. Our custom-built ultrasonic triaxial anvil setup permits measuring longitudinal (Vp) (1 MHz center frequency) and shear wave (Vs) (1.1 MHz center frequency with 0° and 90° polarization options) sound velocities in cubic rock samples (sides ~25 mm) under crustal-pressures up to 300 MPa in three directions (X, Y, and Z) simultaneously. Our results of eleven Precambrian rock samples from the FIRE-reflection profile in Central Finland show 3408-7250 m/s (Vs) and 2460-4140 m/s (Vp). The calculated velocity anisotropy values of these samples vary from 22% to 2% with applied pressure (up to 102 MPa).

Ultrasonic velocity anisotropy technique to enhance seismic surveys and ore prospecting

Interpretation of seismic surveys and loggings suffers from sonic velocity anisotropy in the bedrock. Locating reflectors accurately in surveys and loggings reduces the drilling in ore exploration. Hence it is important to determine the sound velocity anisotropy in core samples. Uniaxial time-of-flight measurements were carried out under low pressure (10 kPa) for the X, Y, and Z directions independently. We measured (N=11) cubic (25 mm) rock samples. The longitudinal wave velocities were obtained with 1-8 MHz broadband transducers. We also present an ultrasonic triaxial anvil setup for measuring longitudinal (Vp) and shear wave (Vs with 0° and 90° polarizations) velocities of cubic rock samples under crustal-pressures (up to 300 MPa) in three directions. Our results from a selection of Finnish Precambrian rocks show ultrasonic velocities in the range of 2990-6800 m/s and velocity anisotropies reaching from 2% to 26% at low pressure.

ULTRASONIC CHARACTERIZATION OF GLASS BEADS

We report on the progress in developing a method for an in‐line granule size measurement using ultrasonic through transmission method. The knowledge of granule size is important in the production of pharmaceutical dosage forms where the current optical and rheological methods have limitations such as fouling of the optical windows. The phase velocity of a wave propagated through interstitial air between glass balls of 1, 2 and 10 mm in diameter was 254±5 m/s, 261±3 m/s and 320±9 m/s, respectively. The power spectral density of the received signals showed that high frequencies were attenuated more in case of smaller beads due to increased scattering.

Device for Measuring P- and S-Wave Velocities in Rock Samples under Crystal Conditions

An ultrasonic instrument capable of measuring seismic velocities (Vp and Vs) under crustal temperatures (20–300°C) and pressures (0–300 MPa) is built. The results obtained with the device will be used to understand recent seismic reflection (FIRE) data from the Outokumpu area in Finland. Collectively, the data will be integrated to construct a new geological model of the Outokumpu formation.