| 1. |
- Trubetskaya, Anna, 1984-, et al.
(författare)
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One way of representing the size and shape of biomass particles in combustion modeling
- 2017
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 206, s. 675-683
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to provide a geometrical description of biomass particles that can be used in combustion models. The particle size of wood and herbaceous biomass was compared using light microscope, 2D dynamic imaging, laser diffraction, sieve analysis and focused beam reflectance measurement. The results from light microscope and 2D dynamic imaging analysis were compared and it showed that the data on particle width, measured by these two techniques, were identical. Indeed, 2D dynamic imaging was found to be the most convenient particle characterization method, providing information on both the shape and the external surface area. Importantly, a way to quantify all three dimensions of biomass particles has been established. It was recommended to represent a biomass particle in combustion models as an infinite cylinder with the volume-to-surface ratio (V/A) measured using 2D dynamic imaging.
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| 2. |
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| 3. |
- Basavoju, Srinivas, et al.
(författare)
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Pharmaceutical salts of fluoroquinolone antibacterial drugs with acesulfame sweetener
- 2012
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Ingår i: Molecular Crystals and Liquid Crystals. - : Informa UK Limited. - 1542-1406 .- 1563-5287. ; 562:1, s. 254-264
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Tidskriftsartikel (refereegranskat)abstract
- Novel organic salts of norfloxacin and ciprofloxacin with artificial sweeteners such as saccharin and acesulfame were prepared. The two salts 1 and 2 were characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Finally, the crystal structures were solved by single crystal X-ray diffraction data and the structures were analyzed in terms of supramolecular synthons. In norfloxacin acesulfamate 1, two norfloxacin cations and two acesulfame anions form an eight membered cyclic tetramer supramolecular synthon. The salt, ciprofloxacin acesulfamate 2, has a similar structure as salt 1. This study contributes the importance of crystal engineering and supramolecular chemistry to the pharmaceutical applications in terms of interactions and structural correlations in the design of new solid phases. Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.
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| 4. |
- Högberg, Sofie, et al.
(författare)
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Fluid mechanics of particle deposition in human lungs
- 2005
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Ingår i: Contributed paper abstracts / American Association of Pharmaceutical Scientists.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aim: To develop an ideal Computational Fluid Dynamic (CFD) model, which provides knowledge of fundamental characteristics of particles and their eventual deposition patterns in the respiratory system, to design an effective formulation for a specific therapeutic application (local or systemic) Methods: The whole flow field was measured in a single measurement using Particle Image Velocimetry (PIV). The concept was to add small sized particles to the flow. These particles were then illuminated by a thin laser-layer in the region of interest and the motion of the formed speckle pattern was captured by a CCD-camera. Results: In a preliminary study, the flow in the uppermost three generations of airways, with a focus on branches of rectangular cross-sections, has been investigated. This geometry was easily built from blocks of PMMA. The model captured the main flow features. A qualitative agreement between experiments and simulations was obtained as shown in Figure 1, a snap-shot taken during inhalation. The experiments further enable a more detailed study of the quality and trust of the simulations. The result of this is then applied on a more realistic model of the uppermost airways and the particle deposition simulated (Figure 2). Fig 1 Fig 2 Figure 1: PIV-measurements showing the velocity field, the upper CFD-graph is obtained for a k-? turbulent flow and the lower graph shows the field for a laminar; Figure 2: Virtual model of the upper part of the air-ways. Please notice that the grid was refined for the initial simulations Conclusions: Preliminary studies were initiated with an ultimate aim of developing a complete lung model. Our efforts so far yielded a good understanding of experimental and numerical visualisation of the flow in the uppermost airways and we are currently engaged in quantifying the results.
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| 5. |
- Lou, Benyong, et al.
(författare)
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Polymorph control of Felodipine form II in an attempted cocrystallization
- 2009
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 9:3, s. 1254-1257
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Tidskriftsartikel (refereegranskat)abstract
- The metastable form II of racemic felodipine was obtained in an attempted cocrystallization with isonicotinamide. Its low temperature crystal structure was characterized by a 1D hydrogen-bonded chain consisting of four independent felodipine molecules.
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| 6. |
- Velaga, Sitaram, et al.
(författare)
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Experimental Studies and Modeling of the Drying Kinetics of Multicomponent Polymer Films
- 2018
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Ingår i: AAPS PharmSciTech. - : Springer. - 1530-9932. ; 19:1, s. 425-435
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Tidskriftsartikel (refereegranskat)abstract
- The process of drying thin polymer films is an important operation that influences the film structure and solid state, and the stability of the product. The purpose of this work was to study and model the drying kinetics of multicomponent films based on two polymers: hydroxypropyl methylcellulose (HPMC, amorphous) and polyvinyl alcohol (PVA, semicrystalline). The isothermal drying kinetics of the films at different temperatures (40, 60, and 80°C) were studied using thermo-gravimetric analysis (TGA) and convection oven methods. Solid-state characterization tools used in the study included polarization and hot-stage microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The drying kinetics of HPMC and PVA films in the TGA apparatus and convection oven were comparable. The three-parameter (Wmax, τ, n) Hill equation successfully modeled the experimental drying kinetics. The time factor τ in the Hill equation nicely explained two drying phases in the films. Solid-state phase changes occurring in the films during dehydration had a bearing on the drying kinetics and mechanisms. TGA can be used as a simple tool to determine the end points in drying processes using ovens or tunnels. The three-parameter Hill equation explained the drying kinetics and diffusion mechanisms of the solvent through the polymer films for the first time. This study advances our understanding of film drying, in particular for pharmaceutically relevant thin films.
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| 7. |
- Velaga, Sitaram, et al.
(författare)
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Polymorphism in acesulfame sweetener : structure-property and stability relationships of bending and brittle crystals
- 2010
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 46:21, s. 3562-3564
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Tidskriftsartikel (refereegranskat)abstract
- Acesulfame is found to exist in two crystalline forms of which Form I (needles) shows bending upon mechanical stress. Crystal structures explain their mechanical response. This is the first case of aliphatic organic compounds featuring a bending phenomenon. Form I is physically more stable than Form II in ambient conditions.
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| 8. |
- Velaga, Sitaram, et al.
(författare)
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Reducing the stigma of long acting injectable antipsychotics : current concepts and future developments
- 2018
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Ingår i: Conference proceedings of the 4th Masterclass Psychiatry. - : Taylor & Francis. ; , s. 30-33
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Konferensbidrag (refereegranskat)abstract
- Background: Long acting injectable antipsychotics (LAIAPs) are considered a major advance in psychiatric treatment concerning treatment adherence and outcomes. Yet, both, doctors and patients, remain sceptical.Aim: To explain the rationale for using LAI-APs, review their effectiveness and explore barriers to use. Method: Clinical overview of LAI-APs from the patient and doctor perspective.Results: LAI-APs were developed to increase adherence to treatment, thereby improving treatment outcomes. LAI-APs may reduce risk of relapse and hospitalization. Yet, the evidence from the few meta-analyses available remains weak. Both patients and doctors may associate LAI-APs with stigma and coercion. Current means of improving adherence include more focus on the therapeutic relationship, better information, adverse effects minimization and halflife extension of LAI-APs. Future means of improving adherence include novel administration techniques that abolish the need for injection.Conclusions: For both, clinicians and drug developers, drug adherence remains a major target for improving treatment outcomes.
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| 9. |
- Vuddanda, Parameswara Rao, et al.
(författare)
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Electrospun nanofiber Mats for ultrafast release of ondansetron
- 2016
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Ingår i: Reactive & functional polymers. - : Elsevier BV. - 1381-5148 .- 1873-166X. ; 99, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- Nanofiber mats or films are promising platforms that can offer unique opportunities in oromucosoal drug delivery. However, the conventional film forming technologies are unable to produce mats with unique internal microstructure and properties. Thus, the present study was aimed to develop electrospun nanofiber mats of a model drug -ondansetron hydrochloride (OND) for ultrafast drug release. Polyvinyl alcohol (PVA), a water soluble synthetic polymer was used in the preparation of nanofiber mats and casting film. The OND nanofiber mats and conventional films were prepared by electrospinning and casting methods, respectively. Different electrospinning process variables (feed rate, electric voltage and tip to collector distance) were investigated. Nanofiber mats and casted films were characterized using Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Differential scanning calorimetry (DSC), Powder X-ray diffraction (PXRD), and Attenuated total reflection – Fourier transform infrared spectroscopy (ATR-FTIR). The folding endurance, drug content, wetting behaviour and disintegration properties and in-vitro drug release studies were also performed.The SEM and AFM had revealed that the nanofiber mats were formed with smooth uniform texture. Solid state studies indicated that the OND was in amorphous state and uniformly dispersed in PVA mats and a film. The electrospun nanofiber mat and casted film of OND showed sufficient mechanical properties. Wet sponge method suggested that OND nanofiber mats were simultaneously wetted and disintegrated within 10 s, which is ultrafast compared to casted films. The total amount of OND was released in 90 s (1.5 min) and 1800 s (30 min) from OND-PVA electrospun nanofiber mats and casted film, respectively. OND nanofiber mats can be promising alternatives to existing solid dosage forms for ultrafast release of drugs.
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