Drug diffusivities in nanofibrillar cellulose hydrogel by combined time-resolved Raman and fluorescence spectroscopy

Hydrogels, natural and synthetic origin, are actively studied for their use for implants and payload carriers. These biomaterials for delivery systems have enormous potential in basic biomedical research, drug development, and long-term delivery of biologics. Nanofibrillated cellulose (NFC) hydrogels, both natural and anionic (ANFC) ones, allow drug loading for immediate and controlled release via the slow drug dissolution of solid drug crystals into hydrogel and its subsequent release. This property makes NFC originated hydrogels an interesting non-toxic and non-human origin material as drug reservoir for long-term controlled release formulation or implant for patient care. A compelling tool for studying NFC hydrogels is Raman spectroscopy, which enables to resolve the chemical structures of different molecules in a high-water content like hydrogels, since Raman spectroscopy is insensitive to water molecules. That offers real time investigation of label-free drugs and their release in high-water-content media. Despite the huge potential of Raman spectroscopy in bio-pharmaceutical applications, the strong fluorescence background of many drug samples masking the faint Raman signal has restricted the widespread use of it. In this study we used a Raman spectrometer capable of suppressing the unpleasant fluorescence background by combining a pulsed laser and time-resolved complementary metal-oxide-semiconductor (CMOS) singlephoton avalanche diode (SPAD) line sensor for the label-free investigation of Metronidazole and Vitamin C diffusivities in ANFC. The results show the possibility to modulate the ANFC-based implants and drug delivery systems, when the release rate needs to be set to a desired value. More importantly, the now developed label free real-time method is universal and can be adapted to any hydrogel/drug combination for producing reliable drug diffusion coefficient data in complex and heterogeneous systems, where traditional sampling-based methods are cumbersome to use. The wide temporal range of the time-resolved CMOS SPAD sensors makes it possible to capture also the fluorescence decay of samples, giving rise to a combined time-resolved Raman and fluorescence spectroscopy, which provides additional information on the chemical, functional and structural changes in samples.Peer reviewe

UMC100 Toiminnallisuus

Opinnäytetyön tavoitteena oli kartoittaa älykkään moottorinohjaimen toiminnallisuus ja selvittää pystytäänkö sillä toteuttamaan kaikki metsäteollisuuden sovellutuksissa esiintyvät moottorinohjaukset. Työssä selvitettiin myös UMC100:n ja UMC22:n väliset erot, sekä tarvittavat muutokset kun UMC22 korvataan UMC100:lla. Työ tehtiin ABB:n Prosessiteollisuusosastolle ja oli osana UMC100:lle perustuvaa moottorinohjausprojektia. Työssä moottorinohjaimille tehtiin erilaisia toiminnallisuuteen ja vikoihin liittyviä testejä. Testausta varten suunniteltiin testiprotokolla, jonka mukaan molemmat moottorinohjaimet testattiin. Testeissä havaitut toiminnallisuudet kirjattiin ylös ja saaduista tuloksista suoritettiin vertailu. Testaus suoritettiin Prosessiteollisuus-osaston demohuoneessa. Työssä tehtiin myös vasteaikatestaus ja Siemens S7-testaus. Vasteaikatestauksessa tarkasteltiin eri viiveitä UMC100:ssa, UMC100:n ja laajennusmoduulin välillä sekä UMC100:n ja automaation välillä. Siemens S7-testauksessa oli tarkoituksena saada UMC100 toimimaan yhdessä S7-järjestelmän kanssa. S7-testaus suoritettiin Tecnobotnia-laboratoriossa. Työssä saatiin selville UMC100:n ja UMC22:n erot, eri viiveet UMC100:ssa ja kaikki tarvittavat muutokset, mikäli UMC22 korvataan UMC100:lla. Työssä selvitettiin myös eroja kilpailijoiden tuotteisiin ja avattiin moottorinohjaimille tehtävää tehdaskoestusta

Position-sensitive devices and sensor systems for optical tracking and displacement sensing applications

Abstract This thesis describes position-sensitive devices (PSDs) and optical sensor systems suitable for industrial tracking and displacement sensing applications. The main application areas of the proposed sensors include automatic pointing of a rangefinder beam and measuring the lateral displacement of an object. A conventional tracking sensor is composed of a laser illuminator, a misfocused quadrant detector (QD) receiver and a corner cube retroreflector (CCR) attached to the target. The angular displacement of a target from the receiver optical axis is detected by illuminating the target and determining the direction of the reflection using the QD receiver. The main contribution of the thesis is related to the modifications proposed for this conventional construction in order to make its performance sufficient for industrial applications that require a few millimetre to submillimetre accuracy. The work includes sensor optical construction modifications and the designing of new types of PSDs. The conventional QD-based sensor, although electrically very sensitive, is not considered optimal for industrial applications since its precision is severely hampered by atmospheric turbulence due to the misfocusing needed for its operation. Replacing the CCR with a sheet reflector is found to improve the precision of the conventional sensor construction in outdoor beam pointing applications, and is estimated to allow subcentimetre precision over distances of up to 100 m under most operating conditions. Submillimetre accuracy is achievable in close-range beam pointing applications using a small piece of sheet reflector, coaxial illumination and a focused QD receiver. Polarisation filtering is found to be effective in eliminating the main error contributor in close-range applications, which is low reflector background contrast, especially in cases when a sheet reflector has a specularly reflecting background. The tracking sensor construction is also proposed for measuring the aiming trajectory of a firearm in an outdoor environment. This time an order of magnitude improvement in precision is achieved by replacing the QD with a focused lateral effect photodiode (LEP). Use of this construction in cases of intermediate atmospheric turbulence allows a precision better than 1 cm to be achieved up to a distance of 300 m. A method based on averaging the positions of multiple reflectors is also proposed in order to improve the precision in turbulence-limited cases. Finally, various types of custom-designed PSDs utilising a photodetector array structure are presented for long-range displacement sensing applications. The goal was to be able to replace the noisy LEP with a low-noise PSD without compromising the low turbulence sensitivity achievable with the LEP. An order of magnitude improvement in incremental sensitivity is achievable with the proposed array PSDs

Properties and suitability of liquid electrode plasma optical emission spectrometry (LEP-OES) for the determination of potassium, lithium, iron, and zinc in aqueous sample solutions

Abstract The effects of different parameters and the nitric acid concentration on the sensitivity and repeatability of elemental analysis were characterized for liquid electrode plasma optical emission spectrometry (LEP-OES). In addition, internal standardization for LEP-OES was investigated. The developed LEP-OES method was used for the determination of lithium, potassium, iron, and zinc in aqueous solutions and in samples with high acid concentrations after microwave-assisted digestion. The results were compared with those obtained by inductively coupled plasma — optical emission spectrometry. The sensitivity was improved when the plasma parameters were optimized. In addition, some improvement in the accuracy and reproducibility of the results was achieved when internal standardization by gold was employed. However, due to the strong matrix effects, the calibration standards should be made as similar as possible to the sample matrix

Instrument and method for measuring ice accretion in mixed-phase cloud conditions

Abstract The ICEMET-sensor is a novel cloud droplet and particle imaging instrument which measures icing conditions by determining the number and sizes of the supercooled droplets in a known air volume. The sensor captures digital holograms from 0.5 cm 3 sample volume with a maximum rate of 3.0 cm 3 /s. This lensless imaging instrument uses a computational imaging method to reconstruct the shadow images of the objects in the measurement volume. The size, position and shape descriptors of the individual particles and droplets are calculated and saved into a database. This data can be used to separate between cloud droplets and other particles. The calculated features are used to determine the two essential parameters needed for ice accretion modeling according to the ISO 12494 icing standard: liquid water content (LWC) of the air and median volume diameter (MVD) of the droplets. The basic working principle of the sensor and the image processing method are described. The performance of the sensor was tested in a wind tunnel under mixed-phase icing conditions. The measured LWC and MVD values were used to model ice accretion using the ISO 12494 icing standard for rotating cylinders. The modeled ice accretions were compared with weighed ice masses obtained from the wind tunnel with the same sized cylinder. The results show that accurate droplet size measurement and separation between droplets and ice crystals are essential for estimating the ice accretion rate properly. Without filtering out the ice crystals, the calculated accretion rates were overestimated by 65.6 % on average

Study of the aerodynamic sampling effects of a holographic cloud droplet instrument

Abstract Computational fluid dynamics and particle tracing simulations are presented for a cloud droplet sensor. Airspeeds and streamlines around the sensor are calculated at several wind speeds and their effect on the droplet sampling are examined. Particle tracing is used to study the effect of different wind speeds and droplet sizes on the sampling of the cloud droplets. Simulated droplet concentrations are confirmed by comparing them with measured wind tunnel data. Results demonstrate clear sampling effects that are functions of both wind speed and droplet size. Optimal compromise between maximal measurement volume and sampling effects is found and a simple approximation for sensor’s sampling bias is presented. The results show that CFD simulations can give valuable information about the sampling of droplets in an ideal environment with known droplet concentrations. Even in a wind tunnel, the true test conditions are often impossible to accurately determine. Thus by simulating the sampling effects in different conditions, the sensor can be calibrated for a wide range of naturally occurring cloud conditions