Jari T.T. Leskinen

In-line ultrasound measurement system for detecting tablet integrity.

An ultrasound measurement system for tablet defect detection is introduced. The measurement system was implemented in an eccentric single station tabletting apparatus, where ultrasound transducers were placed inside the upper and lower punches. These instrumented punches were then used to measure the speed of sound and ultrasound attenuation values in both intact and defective tablets made from dibasic calcium phosphate, microcrystalline cellulose and lactose monohydrate. Ultrasound attenuation was found to be a very sensitive method to discriminate defective tablets from intact ones. In addition, it was found that the determined ultrasound attenuation was different between all three materials used in this study, which indicates that different materials could be distinguished from one another by this detection method.

Effect of fuel zinc content on toxicological responses of particulate matter from pellet combustion in vitro.

Significant amounts of transition metals such as zinc, cadmium and copper can become enriched in the fine particle fraction during biomass combustion with Zn being one of the most abundant transition metals in wood combustion. These metals may have an important role in the toxicological properties of particulate matter (PM). Indeed, many epidemiological studies have found associations between mortality and PM Zn content. The role of Zn toxicity on combustion PM was investigated. Pellets enriched with 170, 480 and 2300 mg Zn/kg of fuel were manufactured. Emission samples were generated using a pellet boiler and the four types of PM samples; native, Zn-low, Zn-medium and Zn-high were collected with an impactor from diluted flue gas. The RAW 264.7 macrophage cell line was exposed for 24h to different doses (15, 50,150 and 300 μg ml(-1)) of the emission samples to investigate their ability to cause cytotoxicity, to generate reactive oxygen species (ROS), to altering the cell cycle and to trigger genotoxicity as well as to promote inflammation. Zn enriched pellets combusted in a pellet boiler produced emission PM containing ZnO. Even the Zn-low sample caused extensive cell cycle arrest and there was massive cell death of RAW 264.7 macrophages at the two highest PM doses. Moreover, only the Zn-enriched emission samples induced a dose dependent ROS response in the exposed cells. Inflammatory responses were at a low level but macrophage inflammatory protein 2 reached a statistically significant level after exposure of RAW 264.7 macrophages to ZnO containing emission particles. ZnO content of the samples was associated with significant toxicity in almost all measured endpoints. Thus, ZnO may be a key component producing toxicological responses in the PM emissions from efficient wood combustion. Zn as well as the other transition metals, may contribute a significant amount to the ROS responses evoked by ambient PM.

Transition Metal-Doped Lithium Titanium Oxide Nanoparticles Made Using Flame Spray Pyrolysis

Defect spinel phase lithium titanate (Li4Ti5O12) has been suggested as a promising negative electrode material for next generation lithium ion batteries. However, it suffers from low electrical conductivity. To overcome this problem conduction path length can be reduced by decreasing the primary particle size. Alternatively the bulk conductivity of Li4Ti5O12 can be increased by doping it with a conductive additive. In this paper a steady, single-step gas-phase technique for lithium titanate synthesis that combines both approaches is described. The process is used to produce doped Li4Ti5O12 nanoparticles with primary particle size of only 10 nm. The product is found to consist of single-crystalline nanoparticles with high phase and elemental purity. Two dopant materials are tested and found to behave very differently. The silver dopant forms a separate phase of nanometre-sized particles of metallic silver which agglomerate with Li4Ti5O12. The copper dopant, on the other hand, reacts with the lithium titanate to form a double spinel phase of Li3(Li1−2𝑥Cu3𝑥Ti5−𝑥)O12.

Real-time tablet formation monitoring with ultrasound measurements in eccentric single station tablet press.

A real-time ultrasound measurement system for tablet compression monitoring is introduced. The measurement system was tested in actual manufacturing environment and found to be capable of measuring the ultrasound response of the tabletting process from bulk to tablet. The tablet sets were compressed and the ultrasound measurements were conducted as implemented in eccentric single station tabletting apparatus in through transmission geometry. The speed of sound and ultrasound spectrum was measured during dynamic compression for microcrystalline cellulose/paracetamol tablets. The ultrasound system introduced in this study was found to be suitable for tabletting process monitoring as the mechanical properties of compressed tablets can be estimated during compression using the ultrasound system. In addition, it was found that the ultrasound was sensitive to the mixing time of magnesium stearate and the concentration of paracetamol. Thus, ultrasound measurements made during the compression can be used to monitor the tablet formation process.

Release and characteristics of fungal fragments in various conditions.

Intact spores and submicrometer size fragments are released from moldy building materials during growth and sporulation. It is unclear whether all fragments originate from fungal growth or if small pieces of building materials are also aerosolized as a result of microbial decomposition. In addition, particles may be formed through nucleation from secondary metabolites of fungi, such as microbial volatile organic compounds (MVOCs). In this study, we used the elemental composition of particles to characterize the origin of submicrometer fragments released from materials contaminated by fungi. Particles from three fungal species (Aspergillus versicolor, Cladosporium cladosporioides and Penicillium brevicompactum), grown on agar, wood and gypsum board were aerosolized using the Fungal Spore Source Strength Tester (FSSST) at three air velocities (5, 16 and 27 m/s). Released spores (optical size, dp ≥ 0.8 μm) and fragments (dp ≤ 0.8 μm) were counted using direct-reading optical aerosol instruments. Particles were also collected on filters, and their morphology and elemental composition analyzed using scanning electron microscopes (SEMs) coupled with an Energy-Dispersive X-ray spectroscopy (EDX). Among the studied factors, air velocity resulted in the most consistent trends in the release of fungal particles. Total concentrations of both fragments and spores increased with an increase in air velocity for all species whereas fragment-spore (F/S) ratios decreased. EDX analysis showed common elements, such as C, O, Mg and Ca, for blank material samples and fungal growth. However, N and P were exclusive to the fungal growth, and therefore were used to differentiate biological fragments from non-biological ones. Our results indicated that majority of fragments contained N and P. Because we observed increased release of fragments with increased air velocities, nucleation of MVOCs was likely not a relevant process in the formation of fungal fragments. Based on elemental composition, most fragments originated from fungi, but also fragments from growth material were detected.

Physicochemical Characterization of Aerosol Generated in the Gas Tungsten Arc Welding of Stainless Steel.

OBJECTIVES Exposure to stainless steel (SS) welding aerosol that contain toxic heavy metals, chromium (Cr), manganese (Mn), and nickel (Ni), has been associated with numerous adverse health effects. The gas tungsten arc welding (GTAW) is commonly applied to SS and produces high number concentration of substantially smaller particles compared with the other welding techniques, although the mass emission rate is low. Here, a field study in a workshop with the GTAW as principal welding technique was conducted to determine the physicochemical properties of the airborne particles and to improve the understanding of the hazard the SS welding aerosols pose to welders. METHODS Particle number concentration and number size distribution were measured near the breathing zone (50cm from the arc) and in the middle of the workshop with condensation particle counters and electrical mobility particle sizers, respectively. Particle morphology and chemical composition were studied using scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy. RESULTS In the middle of the workshop, the number size distribution was unimodal with the geometric mean diameter (GMD) of 46nm. Near the breathing zone the number size distribution was multimodal, and the GMDs of the modes were in the range of 10-30nm. Two different agglomerate types existed near the breathing zone. The first type consisted of iron oxide primary particles with size up to 40nm and variable amounts of Cr, Mn, and Ni replacing iron in the structure. The second type consisted of very small primary particles and contained increased proportion of Ni compared to the proportion of (Cr + Mn) than the first agglomerate type. CONCLUSIONS The alterations in the distribution of Ni between different welding aerosol particles have not been reported previously.

Impact of Microscale and Pilot-Scale Freeze-Drying on Protein Secondary Structures: Sucrose Formulations of Lysozyme and Catalase

Microscale (MS) freeze-drying offers rapid process cycles for early-stage formulation development. The effects of the MS approach on the secondary structures of two model proteins, lysozyme and catalase, were compared with pilot-scale (PS) vial freeze-drying. The secondary structures were assessed by attenuated total reflection Fourier transformed infrared spectroscopy. Formulations were made with increasing sucrose-protein ratios. Freeze-drying protocols involved regular cooling without thermal treatment and annealing with MS and PS equipment, and cooling rate variations with the MS. Principal component analysis of smoothed second-derivative amide I spectra revealed sucrose-protein ratio-dependent shifts toward α-helical structures. Transferability of sucrose-protein formulations from MS to PS vial freeze-drying was evidenced at regular cooling rates. Local differences in protein secondary structures between the bottom and top of sucrose-catalase samples could be detected at the sucrose-catalase ratios of 1 and 2, this being related to the initial filling height and ice crystal morphology. Annealing revealed temperature, protein, formulation, and sample location-dependent effects influencing surface morphology at the top, or causing protein secondary structure perturbation at the bottom. With the MS approach, protein secondary structure differences at different cooling rates could be detected for sucrose-lysozyme samples at the sucrose-lysozyme ratio of 1.