Hyperpolarized (HP) tracers dramatically increase the sensitivity of magnetic resonance imaging (MRI) to monitor metabolism non-invasively and in vivo. Their production, however, requires an extra ...polarizing device (polarizer) whose complexity, operation and cost can exceed that of an MRI system itself. Furthermore, the lifetime of HP tracers is short and some of the enhancement is lost during transfer to the application site. Here, we present the production of HP tracers in water without an external polarizer: by Synthesis Amid the Magnet Bore, A Dramatically Enhanced Nuclear Alignment (SAMBADENA) is achieved within seconds, corresponding to a hyperpolarization of ∼20%. As transfer of the tracer is no longer required, SAMBADENA may permit a higher polarization at the time of detection at a fraction of the cost and complexity of external polarizers. This development is particularly promising in light of the recently extended portfolio of biomedically relevant para-hydrogen-tracers and may lead to new diagnostic applications.
The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c\(^{2}\). It investigates ...the kinematics of \(\beta\)-particles from tritium \(\beta\)-decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about \(12\%\) of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than \(17\%\) (\(90\%\) confidence level) of the overall MS background.
A modification of the GAB isotherm (Guggenheim–Anderson–De Boer) is proposed in order to correlate the sorption data for water activities higher than 0.9. The proposed isotherm retains the desirable ...properties of the GAB isotherm, i.e. good fitting in the range of
a
w between 0.05 and 0.80, and also provides a noticeable improvement in the fitting quality for high values of
a
w, by introducing a new term with an additional constant. Sorption data for native potato starch and gluten at different temperatures (2°C, 20°C, 40°C and 67°C) were well correlated for the whole
a
w range. For starch at 67°C, the values of the constants of the proposed equation do not follow the same tendency obtained for lower temperatures, suggesting that the structure of the material could be changed due to the high temperature. The proposed isotherm can be of interest in the area of drying given that there are few isotherms that accurately represent sorption data at different temperatures in the zone of high
a
w. Also, it can be useful to predict other thermodynamic functions. In addition, a new procedure is proposed to determine the isosteric heat by using a second order polynomial for representing the variation of moisture as a function of temperature at a fixed water activity.
Introduction. Longo’s technique (or PPH technique) is well known worldwide. Meta-analysis suggests that the failure due to persistence or recurrence is close to 7.7%. One of the reasons for the ...recurrence is the treatment of the advanced hemorrhoidal prolapse with a single stapling device, which is not enough to resect the appropriate amount of prolapse. Materials and methods. We describe the application of “Double PPH Technique” (D-PPH) to treat large hemorrhoidal prolapses. We performed a multicentric, prospective, and nonrandomized trial from July 2008 to July 2009, wherein 2 groups of patients with prolapse and hemorrhoids were treated with a single PPH or a D-PPH. Results were compared. The primary outcome was evaluation of safety and efficacy of the D-PPH procedure in selected patients with large hemorrhoidal prolapse. Results. In all, 281 consecutive patients suffering from hemorrhoidal prolapse underwent surgery, of whom 74 were assigned intraoperatively to D-PPH, whereas 207 underwent single PPH. Postoperative complications were 5% in both groups (P = .32), in particular: postoperative major bleeding 3.0% in PPH versus 4.1% D-PPH (P = .59); pain 37.9 % PPH versus 27.3% D-PPH (mean visual analog scale VAS = 2.5 vs 2.9, respectively; P = .72); and fecal urgency 2.1% PPH versus 5.7% D-PPH (P = .8). Persistence of hemorrhoidal prolapse at 12-month follow-up was 3.7% in the PPH group versus 5.9% in the D-PPH group (P = .5). Conclusions. Our data support the hypothesis that an accurate intraoperative patient selection for single (PPH) or double (D-PPH) stapled technique will lower in a significant way the incidence of recurrence after Longo’s procedure for hemorrhoidal prolapse.
A mathematical model to predict the drying kinetics of shrinking bodies was proposed, assuming unidirectional drying and three-dimensional shrinkage. The differential equation for mass transfer in a ...finite slab was solved, using boundary conditions of the first kind. The model was numerically solved by finite differences, taking into account a convective term in the mass balance equation, which appears as a consequence of non-unidirectional shrinkage. This additional term significantly changed the value of the predicted diffusion coefficient. Differences when compared with previous solutions are significant for drying of solids with high initial moisture content.
Numerical solutions were obtained for absorption as well as for desorption processes. The predicted apparent diffusion coefficients, calculated from the slopes of the semilog drying kinetics curves, were different in both cases.
Drying of foods: Evaluation of a drying model Rovedo, Clara O.; Suarez, Constantino; Viollaz, Pascual E.
Journal of food engineering,
1995, 1995-00-00, Letnik:
26, Številka:
1
Journal Article
Recenzirano
The drying of potato slabs in air flow is analysed by the simultaneous numerical solution of the differential heat balance and diffusion equations for a shrinking body. A uniform temperature profile ...in the solid and temperature dependent diffusion coefficient is assumed.
Comparison between predicted and experimental mean moisture content and temperature variations in the sample provides a satisfactory agreement for the moisture range from approximately 5.0 to 0.4 kg water/ kg dry solid. For this moisture range it can be assumed that the diffusion coefficient is not a function of moisture content.
The drying of shrinking bodies is analysed by numerically solving a drying model in order to obtain a deeper insight into the drying process, calculating moisture profiles and various forms of Biot ...number. Moisture profiles shows great differences when different units of concentration are used. Calculated Biot numbers do not satisfactorily explain the drying kinetic curves for solids with a high initial moisture content, because the equilibrium curve is not a straight line. Kinetics drying curves are satisfactorily analysed in terms of variation of total driving force with time, which differs markedly from the corresponding variation of the total driving force in terms of temperature, for a pure heat transfer process.
PMOS degradation with the blanket-stress-memory-technique (SMT) nitride layer on the (100) wafer with ?100? orientation has been observed, and the degradation mechanism is examined. The boron-doping ...loss from both the PMOS gate and the source/drain region during the SMT process is the root cause. In situ N2 plasma treatment before the SMT layer deposition has been implemented for the first time to recover PMOS performance on the ?100? wafer by reducing the boron-doping loss from the gate and the source/drain region. Reliability like PMOS NBTI has been examined, and no degradation is observed.
The rheological behavior of commercial samples of Dulce de Leche (sweet milk) for household and confectionery use was studied. Both products have thixotropic and pseudoplastic characteristics. ...Apparent viscosity, determined at 25, 40, and 55°C, demonstrated that this magnitude decreased with increased temperature. Activation energies were 9.9 and 10.4 kcal/mol for household and confectionery types, respectively.
Apparent viscosities of household samples were determined at pH = 3.0, 6.1, and 8.3. At acid pH, the apparent viscosity was lower than that of the original sample (pH = 6.1); at alkaline pH viscosity was higher than that of the original. The effect of pH becomes more pronounced with time.
From shear stress and shear rate flow diagrams, the Herschel-Bulkley model was adequate for both types of Dulce de Leche investigated.
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