Chitosan as flocculant agent for clarification of stevia extract

Stevia is used as a sweetener due to its low calorific value and its taste, which is very similar to that of sucrose. After extraction from dried leaves, stevia extract is dark in colour, and therefore needs to be whitened to increase acceptance by consumers. In this study we tested chitosan, a cationic polyelectrolyte, as flocculant agent for the whitening of the Stevia extract. Positive charges of chitosan can interact electrostatically with a counter-ion, sodium tripolyphosphate (TPP), and then chitosan precipitates. A factorial design was used to study the whitening process, in which Glycosides Removal, Colour Removal, Turbidity Removal and Soluble Solids Removal were evaluated. The studied factors were Chitosan Mass and pH of the TPP solution. The results showed that chitosan is a good flocculant agent, being able to flocculate both the glycosides and the pigments that make the extract coloured.UNIOESTE Centro de Engenharias e Ciências ExatasUNIFESP Centro de Ciências Exatas e da TerraUNIFESP, Centro de Ciências Exatas e da TerraSciEL

Development of a slender continuum robotic system for on-wing inspection/repair of gas turbine engines

The maintenance works (e.g. inspection, repair) of aero-engines while still attached on the airframes requires a desirable approach since this can significantly shorten both the time and cost of such interventions as the aerospace industry commonly operates based on the generic concept “power by the hour”. However, navigating and performing a multi-axis movement of an end-effector in a very constrained environment such as gas turbine engines is a challenging task. This paper reports on the development of a highly flexible slender (i.e. low diameter-to-length ratios) continuum robot of 25 degrees of freedom capable to uncoil from a drum to provide the feeding motion needed to navigate into crammed environments and then perform, with its last 6 DoF, complex trajectories with a camera equipped machining end-effector for allowing in-situ interventions at a low-pressure compressor of a gas turbine engine. This continuum robot is a compact system and presents a set of innovative mechatronics solutions such as: (i) twin commanding cables to minimise the number of actuators; (ii) twin compliant joints to enable large bending angles (±90°) arranged on a tapered structure (start from 40 mm to 13 mm at its end); (iii) feeding motion provided by a rotating drum for coiling/uncoiling the continuum robot; (iv) machining end-effector equipped with vision system. To be able to achieve the in-situ maintenance tasks, a set of innovative control algorithms to enable the navigation and end-effector path generation have been developed and implemented. Finally, the continuum robot has been tested both for navigation and movement of the end-effector against a specified target within a gas turbine engine mock-up proving that: (i) max. deviations in navigation from the desired path (1000 mm length with bends between 45° and 90°) are ±10 mm; (ii) max. errors in positioning the end-effector against a target situated at the end of navigation path is 1 mm. Thus, this paper presents a compact continuum robot that could be considered as a step forward in providing aero-engine manufacturers with a solution to perform complex tasks in an invasive manner

Direct measurement of resonance strengths in S 34 (α,γ) Ar 38 at astrophysically relevant energies using the DRAGON recoil separator

Background: Nucleosynthesis of mid-mass elements is thought to occur under hot and explosive astrophysical conditions. Radiative α capture on S34 has been shown to impact nucleosynthesis in several such conditions, including core and shell oxygen burning, explosive oxygen burning, and type Ia supernovae. Purpose: Broad uncertainties exist in the literature for the strengths of three resonances within the astrophysically relevant energy range (ECM=1.94-3.42MeV at T=2.2GK). Further, there are several states in Ar38 within this energy range which have not been previously measured. This work aimed to remeasure the resonance strengths of states for which broad uncertainty existed as well as to measure the resonance strengths and energies of previously unmeasured states. Methods: Resonance strengths and energies of eight narrow resonances (five of which had not been previously studied) were measured in inverse kinematics with the DRAGON facility at TRIUMF by impinging an isotopically pure beam of S34 ions on a windowless He4 gas target. Prompt γ emissions of de-exciting Ar38 recoils were detected in an array of bismuth germanate scintillators in coincidence with recoil nuclei, which were separated from unreacted beam ions by an electromagnetic mass separator and detected by a time-of-flight system and a multianode ionization chamber. Results: The present measurements agree with previous results. Broad uncertainty in the resonance strength of the ECM=2709keV resonance persists. Resonance strengths and energies were determined for five low-energy resonances which had not been studied previously, and their strengths were determined to be significantly weaker than those of previously measured resonances. Conclusions: The five previously unmeasured resonances were found not to contribute significantly to the total thermonuclear reaction rate. A median total thermonuclear reaction rate calculated using data from the present work along with existing literature values using the STARLIB rate calculator agrees with the NON-SMOKER statistical model calculation as well as the REACLIB and STARLIB library rates at explosive and nonexplosive oxygen-burning temperatures (T=3-4GK and T=1.5-2.7GK, respectively)

2K nonvolatile shadow RAM and 265K EEPROM SONOS nonvolatile memory development

This paper describes Silicon Oxide Nitride Oxide Semiconductor (SONOS) nonvolatile memory development at Sandia National Laboratories. A 256K EEPROM nonvolatile memory and a 2K nonvolatile shadow RAM are under development using an n-channel SONOS memory technology. The technology has 1.2 {micro}m minimum features in a twin well design using shallow trench isolation

Direct measurement of astrophysically important resonances in ^(38)K(p,γ)^(39)Ca

Background: Classical novae are cataclysmic nuclear explosions occurring when a white dwarf in a binary system accretes hydrogen-rich material from its companion star. Novae are partially responsible for the galactic synthesis of a variety of nuclides up to the calcium (A∼40) region of the nuclear chart. Although the structure and dynamics of novae are thought to be relatively well understood, the predicted abundances of elements near the nucleosynthesis endpoint, in particular Ar and Ca, appear to sometimes be in disagreement with astronomical observations of the spectra of nova ejecta. Purpose: One possible source of the discrepancies between model predictions and astronomical observations is nuclear reaction data. Most reaction rates near the nova endpoint are estimated only from statistical model calculations, which carry large uncertainties. For certain key reactions, these rate uncertainties translate into large uncertainties in nucleosynthesis predictions. In particular, the ^(38)K(p,γ)^(39)Ca reaction has been identified as having a significant influence on Ar, K, and Ca production. In order to constrain the rate of this reaction, we have performed a direct measurement of the strengths of three candidate ℓ=0 resonances within the Gamow window for nova burning, at 386±10 keV, 515±10 keV, and 689±10 keV. Method: The experiment was performed in inverse kinematics using a beam of unstable ^(38)K impinged on a windowless hydrogen gas target. The ^(39)Ca recoils and prompt γ rays from ^(38)K(p,γ)^(39)Ca reactions were detected in coincidence using a recoil mass separator and a bismuth-germanate scintillator array, respectively. Results: For the 689 keV resonance, we observed a clear recoil-γ coincidence signal and extracted resonance strength and energy values of 120^(+50)_(−30)(stat.)^(+20)_(−60)(sys.)meV and 679^(+2)_(−1)(stat.)±1(sys.)keV, respectively. We also performed a singles analysis of the recoil data alone, extracting a resonance strength of 120±20(stat.)±15(sys.) meV, consistent with the coincidence result. For the 386 keV and 515 keV resonances, we extract 90% confidence level upper limits of 2.54 meV and 18.4 meV, respectively. Conclusions: We have established a new recommended ^(38)K(p,γ)^(39)Ca rate based on experimental information, which reduces overall uncertainties near the peak temperatures of nova burning by a factor of ∼250. Using the rate obtained in this work in model calculations of the hottest oxygen-neon novae reduces overall uncertainties on Ar, K, and Ca synthesis to factors of 15 or less in all cases

Cytomegalovirus-based vaccine expressing Ebola virus glycoprotein protects nonhuman primates from Ebola virus infection.

Ebolaviruses pose significant public health problems due to their high lethality, unpredictable emergence, and localization to the poorest areas of the world. In addition to implementation of standard public health control procedures, a number of experimental human vaccines are being explored as a further means for outbreak control. Recombinant cytomegalovirus (CMV)-based vectors are a novel vaccine platform that have been shown to induce substantial levels of durable, but primarily T-cell-biased responses against the encoded heterologous target antigen. Herein, we demonstrate the ability of rhesus CMV (RhCMV) expressing Ebola virus (EBOV) glycoprotein (GP) to provide protective immunity to rhesus macaques against lethal EBOV challenge. Surprisingly, vaccination was associated with high levels of GP-specific antibodies, but with no detectable GP-directed cellular immunity