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In several types of coating processes a solid substrate is removed at a controlled velocity U from a liquid bath. The shape of the liquid meniscus and the thickness of the coating layer depend on U. These dependencies have to be understood in detail for non-volatile liquids to control the deposition of such a liquid and to lay the basis for the control in more complicated cases (volatile pure liquid, solution with volatile solvent). We study the case of non-volatile liquids employing a precursor film model that describes partial wettability with a Derjaguin (or disjoining) pressure. In particular, we focus on the relation of the deposition of (i) an ultrathin precursor film at small velocities and (ii) a macroscopic film of thickness h ∝ U^(2/3) (corresponding to the classical Landau Levich film). Depending on the plate inclination, four regimes are found for the change from case (i) to (ii). The different regimes and the transitions between them are analysed employing numerical continuation of steady states and saddle-node bifurcations and simulations in time. We discuss the relation of our results to results obtained with a slip model. In connection with evaporative processes, we will study the pinning of a droplet due to a sharp corner. The approach employs an evolution equation for the height profile of an evaporating thin film (small contact angle droplet) on a substrate with a rounded edge, and enables one to predict the dependence of the apparent contact angle on the position of the contact line. The calculations confirm experimental observations, namely that there exists a dynamically produced critical angle for depinning that increases with the evaporation rate. This suggests that one may introduce a simple modification of the Gibbs criterion for pinning that accounts for the non-equilibrium effect of evaporation.

Voltammetric methods for the determination of diazepam (DZ) and nordiazepam (NDZ) were developed. Techniques differential pulse voltammetry (DPV) and DC voltammetry for determination of both substances at meniscus modified silver solid amalgam electrode (m-AgSAE) were used. Effect of pHa in media of mixture of Britton-Robinson buffer and methanol (9:1) and 0,1 mol.l-1 NaOH was studied. Stability of the signal with repeated measurements in 0,1 mol.l-1 and methanol (9:1) was monitored. Optimal pHa 13,2 of 0,1 mol.l-1 NaOH was used for determination of DZ by DPV and DCV techniques. Optimal pHa 10,2 in media of mixture of Britton-Robinson buffer and methanol (9:1) was used for determination of NDZ by DPV and DCV techniques. Under these conditions were measured linear dependences in the calibration. Concentration range of DZ was measured with DCV in range of 1.10-4 - 6.10-6 mol.l-1 and DPV with DCV technique in range of 1.10-4 - 2.10-6 mol.l-1. Concentration range of NDZ was measured with DCV technique in range of 1.10-4 - 4.10-6 mol.l-1 and DPV technique in range of 1.10-4 - 2.10-6 mol.l-1. The limit of detection was calculated for DZ 6,6 .10-6 mol.l-1 with DCV and 1.10-6 mol.l-1 with DPV. The limit of detection was calculated for NDZ 5,5.10-6 mol.l-1 with DCV and 1,7.10-6 mol.l-1 with DPV. Developed method...

Voltammetric methods for the determination of diazepam (DZ) and nordiazepam (NDZ) were developed. Techniques differential pulse voltammetry (DPV) and DC voltammetry were used for determination of DZ and NDZ at meniscus modified silver solid amalgam electrode (m-AgSAE). The effect of pHa on the intensity of signal was observed in the mixture of Britton-Robinson buffer and methanol (9:1), and in the mixture of 0.1 mol.l−1 NaOH and methanol (9:1). The stability of the signal during repeated measurements in the mixture of 0.1 mol.l−1 NaOH and methanol (9:1), and in the mixture of BR buffer and methanol (9:1) was monitored. Optimal pHa 13.2 of medium of 0.1 mol.l−1 NaOH and methanol (9:1) was used for determination of DZ with DPV and DCV techniques. Optimal pHa 10.1 of medium of BR buffer and methanol (9:1) was used for determination of NDZ with DPV and DCV techniques. Under these conditions linear dependencies calibration were measured. Concentration range of DZ was measured with DCV in range of 10x10−5 - 6x10−6 mol.l−1 and with DPV technique in range of 10x10−5 - 2x10−6 mol.l−1 . Concentration range of NDZ was measured with DCV technique in range of 10x10−5 - 4x10−6 mol.l−1 and with DPV technique in range of 10x10−5 - 2x10−6 mol.l−1 . The limit of detection for DZ was calculated 6.6x10−6 mol.l−1 with DCV and...

No description available.

No description available.

As drop-on-demand (DOD) applications continue to gain ground in desktop inkjet-printing, 3D printing, fluid mixing, and other areas the demand for higher frequency operations are beginning to push against the current physical boundaries in DOD technology. The current research is exploring the possibility of controlling drop volume and velocity at high frequency ranges where meniscus vibrations can occur between drop formations and affect drop formation characteristics. A periodic voltage is applied to a piezoelectric disk in order to generate pressure fluctuations in a single nozzle droplet generator, causing the fluid meniscus at the nozzle to vibrate. A single stronger pulse is then superimposed over the periodic waveform at different phases in order to drive drop ejection. The characteristics of the resulting drop, specifically the volume and velocity, are experimentally measured using a high speed camera with precise timing control. The results of these experiments are then compared to a lumped element model (LEM) developed for the droplet generator geometry used. Within the LEM model framework, special attention was given to the definition of a novel method by which one can measure drop volume within an electroacoustic circuit and also allow meniscus dynamics to affect present and future drop formations. Experimental results indicate a strong dependence of both drop volume and drop velocity on the phase of the vibrating meniscus at the start of drop formation. Positive meniscus displacements and momentums resulted in large drop volumes and velocities while negative displacements could reduce drop volume or altogether eliminate drop formation. Specifically, positive displacements and momentum of a vibrating meniscus could lead to drop volumes approximately 50% larger than the original drop volume without a vibrating meniscus. Meanwhile, negative meniscus displacements and momentums were shown to have the ability to completely prevent drop formation. Additional potential for drop characteristic control with a vibrating meniscus is discussed alongside observations on the stabilizing affect the vibrating meniscus appears to have on drop velocity as a function of time. Also, flow visualization of the drop formation is provided to demonstrate the added affect the meniscus vibrations have on the drop shapes and break-off profiles. The LEM model presented demonstrates qualitative agreement with the experimental model, but fails to quantitatively predict drop volumes. Sources of error for the LEM model and potential improvements are discussed. / Graduation date: 2012

Title: Biomechanical response of the knee meniscus to the axial loads Work Title: The quantification of the structural changes in deep layer of the knee meniscus using the standardized axial loading Purpose: Due to the internal structure of the knee joint, the ability to characterize and quantify the dynamic response of the meniscal tissue directly in vivo is highly problematic. The main purpose of this study was to investigate the behavior of the meniscus under loading conditions, using parametric MR imaging. Methods: Subjects with no history of knee pain or meniscal problems were included in the study (mean age 27.8 ± 1.3 years). To obtain values of relaxation times T2* in the meniscus, the vTE sequence was used with 10 echoes ranging from 0.8 to 10.1 ms. This has resulted in minimizing the echo time, which is an advantage when differentiating meniscal tissue from surrounding components. First of all, an unloaded limb was scanned and immediately after, the limb loaded half of the person's weight was measured repeatedly in 4 consecutive scans. A custom - made diamagnetic apparatus was developed to simulate stress conditions on the lower limb in a conventional MR scanner. At each 6:10 min measurement, the knee joint was scanned in 64 sections, each image displaying a 1.3 mm section.The two -...

Abstract Osteoarthritis (OA) is a common degenerative disease of synovial joints becoming more frequent with age. Pain, stiffness and functional disability caused by OA negatively affect the quality of individuals’ lives. In order to prevent the manifestation of symptoms and further OA progress, early diagnosis is essential. Ultrasonography has the potential to detect various abnormalities in the knee joint, however its place in clinical practice remains uncertain. The present study aimed to determine the diagnostic performance of the semi-quantitative wide-area ultrasound (US) scanning of knee femoral cartilage degeneration, osteophytes and meniscal extrusion using magnetic resonance imaging as the reference tool. Diagnostic ability of conventional radiography (CR) was also determined and the performances of both modalities compared. Subsequently, the association of structural US findings with knee pain and function was investigated. Finally, quantitative US image analysis focusing on detection and evaluation of subchondral bone integrity in early OA was developed. The US quantitative outcomes were compared with CR and arthroscopy. Tibio-femoral osteophytes, medial meniscal extrusion and medial femoral cartilage morphological degeneration were identified by US with better or at least comparable accuracy than by CR, in which joint space narrowing was used as a composite measure of cartilage damage and meniscal extrusion. The global femoral cartilage grade associated strongly with increased pain and disability. Site-specifically, especially medial cartilage degeneration and femoral lateral osteophytes were associated with increased pain and disability. Regarding the quantitative outcomes, significant increase in US intensity in the femoral subchondral bone depth 0.35–0.7 mm and decrease in intensity slope up to 0.7 mm depth were observed during radiographic or arthroscopic OA progression. Novel wide-area US scanning provides relevant additional diagnostic information on tissue-specific OA pathology not depicted by CR. US-detected changes of femoral cartilage and osteophytes are also associated with clinical symptoms. Consequently, the use of US as a complementary imaging tool along with CR may enable more accurate diagnostics of knee OA. Furthermore, developed quantitative US analysis is a promising tool for detection of femoral subchondral bone changes in knee OA. / Tiivistelmä Nivelrikko on erittäin yleinen nivelten rappeumasairaus, joka aiheuttaa kipua, jäykkyyttä sekä liikkumisvaikeutta. Nivelrikon nykyistä varhaisempi diagnosointi olisi äärimmäisen tärkeää, jotta voitaisiin vähentää oireiden esiintymistä ja hidastaa sairauden etenemistä. Ultraäänikuvaus on lupaava menetelmä nivelrikon varhaisdiagnostiikkaan, mutta sitä ei kuitenkaan ole vielä yleisesti hyväksytty rutiininomaiseen kliiniseen käyttöön. Tämän tutkimuksen päätavoitteena oli selvittää polven semi-kvantitatiivisen ultraäänikuvauksen diagnostista kykyä verrattuna perinteiseen röntgenkuvaukseen, kun arvioidaan rustokudoksen kulumista, luupiikkejä sekä nivelkierukan siirtymää. Magneettikuvausta käytettiin vertailumenetelmänä. Toisena tavoitteena oli selvittää yhteyttä polven ultraäänilöydösten ja polven kivun sekä liikkuvuuden välillä. Lopuksi selvitettiin, voidaanko kvantitatiivisella analyysilla parantaa ultraäänikuvauksen tarkkuutta varhaisvaiheen nivelrikkopotilaiden rustonalaisen luun kunnon määrittämiseen. Röntgenkuvaukseen verrattuna ultraäänikuvaus osoittautui vähintään yhtä hyväksi tai paremmaksi kuvantamismenetelmäksi, kun arvioitiin reisi- ja sääriluun luupiikkejä, sisemmän nivelkierukan siirtymää tai rustokudoksen kulumista. Reisiluun nivelruston yleinen kulumisen aste oli suoraan verrannollinen potilaiden polvinivelen liikerajoituksiin ja kipuun. Erityisesti reisiluun sisemmän puolen nivelruston kuluminen sekä ulomman puolen luupiikit liittyivät potilaiden oireisiin. Kvantitatiiviset ultraäänitulokset osoittivat, että ultraäänen rusto-luurajapinnalta tulevan heijastuksen maksimi-intensiteetti lisääntyi sekä intensiteetin tason laskunopeus vähentyi nivelrikon vaikeusasteen kasvaessa. Tutkimus osoitti, että ultraäänikuvauksella voidaan saada tärkeää diagnostista lisätietoa polven nivelrikon aiheuttamista kudosmuutoksista, joita ei pystytä havaitsemaan perinteisellä röntgenkuvauksella. Ultraäänikuvauksessa näkyvät kudosmuutokset liittyvät myös potilaan kliinisiin oireisiin. Lisäksi rustonalaista luuta voidaan analysoida kvantitatiivisesti ultraäänikuvien perusteella, mikä edelleen helpottaa kuvien tulkintaa. Tutkimuksen perusteella voidaankin suositella ultraäänikuvauksen nykyistä laajempaa kliinistä käyttöä röntgenkuvausta täydentävänä tutkimusmenetelmänä nivelrikon varhaisdiagnostiikassa.

The diploma thesis deals with The study of transition between fully flooded and starved regimes in EHL Contact. The work is focused on problems of starved contact and surface texturing of rubbing surfaces. Surface texturing of rubbing surfaces is one of the adjustments that cause in a sense improved lubricity and reduce friction and wear. The aim of this study is to compare numerical models with real experimental results measured on the Experimental apparatus.