Identification of Ultraviolet radiation induced Gallic acid and Caffeic acid formation in Palm juice (Borassus flabellifer) by HPLC & Mass Spectra Technique.

Palm juice, a common-cheap-antioxidants rich natural plant juice has been investigated for optimizing the effect of UV-radiation on the antioxidant activity using a DPPH free radical scavenging activity method. In this study separate set of samples of raw palm juice has been treated with 365 and 254 nm UV-lights (UVL) respectively for different exposure time. When exposed for 15 min with 365 nm UVL induces concentration factor of caffeic acid, whereas, 254 nm UVL induces gallic acid accumulation, but overall antioxidant activity was higher for 365 nm UVradiation. Caffeic acid and other polyphenol compounds are increased by 5.5 ± 0.5 % than normal palm juice, observed after irradiation with 365 nm UVL. Even after the exposure of UV irradiation for 15 min, did not affect on peptide bond modification of protein molecules present in palm juice, therefore a green effect of UVL is explored for the effective increase of antioxidant activity.

Gravitational actions upon a tether in a non-uniform gravity field with arbitrary number of zonal harmonics

We develop general closed-form expressions for the mutual gravitational potential, resultant and torque acting upon a rigid tethered system moving in a non-uniform gravity field produced by an attracting body with revolution symmetry, such that an arbitrary number of zonal harmonics is considered. The final expressions are series expansion in two small parameters related to the reference radius of the primary and the length of the tether, respectively, each of which are scaled by the mutual distance between their centers of mass. A few numerical experiments are performed to study the convergence behavior of the final expressions, and conclude that for high precision applications it might be necessary to take into account additional perturbation terms, which come from the mutual Two-Body interaction.

An experimental study of the breakage of liquid bridges at stability limit of minimum volume

An experimental apparatus to study the breaking process of axisymmetric liquid bridges has been developed, and the breaking sequences of a large number of liquid bridge configurations at minimum-volume stability limit have been analyzed. Experimental results show that very close to the breaking moment the neck radius of the liquid bridge varies as t1/3, where t is the time to breakage, irrespective of the value of the distance between the solid disks that support the liquid column.

Doubling the width of the platform of the San Pedro bridge in Spain

The San Pedro Bridge has six spans and is 750 m (2460 ft) long, 88 m (290 ft) high, 12 m (39 ft) wide, and curved with a radius of 700 m (2300 ft). It was built in 1993 using the cantilever method. Its super - structure is a prestressed concrete box girder with main spans of 150 m (490 ft). In 2008 and 2009, the width of the platform was enlarged to 23 m (75 ft) using five movable sets of scaffolding. The bridge remained open to traffic during construction. The original platform was widened 6 m (20 ft) on each side by connecting a new lightweight concrete cantilever to the original upper slab. These cantilevers were supported by steelstruts. The tie into the upper slab was made with new transverse post-tensioned tendons. The original superstructure was strengthened to resist the additional dead load of the expansion and live loads of the extra traffic. An additional new central web and a composite concrete-steel section were constructed and connected to the concrete box and central web using vertical high-strength post-tensioning bars. Also, external post-tensioning cables were implemented. It was also necessary to strengthen the connection of the original concrete box section to the piers. Detailed calculations were performed to evaluate the load distribution transmitted to the piers by the webs and by the original inclined concrete walls of the box girder. Finally, a detailed second-order-analysis of the complete structure was made to guarantee the resistance of the piers compared with actual loads

Propellantless deorbiting of space debris by bare electrodynamic tethers : final report

A Space tether is a thin, multi-kilometers long conductive wire, joining a satellite and some opposite end mass, and keeping vertical in orbit by the gravity-gradient. The ambient plasma, being highly conductive, is equipotential in its own co-moving frame. In the tether frame, in relative motion however, there is in the plasma a motional electric field of order of 100 V/km, product of (near) orbital velocity and geomagnetic field. The electromotive force established over the tether length allows plasma contactor devices to collect electrons at one polarized-positive (anodic) end and eject electrons at the opposite end, setting up a current along a standard, fully insulated tether. The Lorentz force exerted on the current by the geomagnetic field itself is always drag; this relies on just thermodynamics, like air drag. The bare tether concept, introduced in 1992 at the Universidad Politécnica de Madrid (UPM), takes away the insulation and has electrons collected over the tether segment coming out polarized positive; the concept rests on 2D (Langmuir probe) current-collection in plasmas being greatly more efficient than 3D collection. A Plasma Contactor ejects electrons at the cathodic end. A bare tether with a thin-tape cross section has much greater perimeter and de-orbits much faster than a (corresponding) round bare tether of equal length and mass. Further, tethers being long and thin, they are prone to cuts by abundant small space debris, but BETs has shown that the tape has a probability of being cut per unit time smaller by more than one order of magnitude than the corresponding round tether (debris comparable to its width are much less abundant than debris comparable to the radius of the corresponding round tether). Also, the tape collects much more current, and de-orbits much faster, than a corresponding multi-line “tape” made of thin round wires cross-connected to survive debris cuts. Tethers use a dissipative mechanism quite different from air drag and can de-orbit in just a few months; also, tape tethers are much lighter than round tethers of equal length and perimeter, which can capture equal current. The 3 disparate tape dimensions allow easily scalable design. Switching the cathodic Contactor off-on allows maneuvering to avoid catastrophic collisions with big tracked debris. Lorentz braking is as reliable as air drag. Tethers are still reasonably effective at high inclinations, where the motional field is small, because the geomagnetic field is not just a dipole along the Earth polar axis. BETs is the EC FP7/Space Project 262972, financed in about 1.8 million euros, from 1 November 2010 to 31 January 2014, and carrying out RTD work on de-orbiting space debris. Coordinated by UPM, it has partners Università di Padova, ONERA-Toulouse, Colorado State University, SME Emxys, DLR–Bremen, and Fundación Tecnalia. BETs work involves 1) Designing, building, and ground-testing basic hardware subsystems Cathodic Plasma Contactor, Tether Deployment Mechanism, Power Control Module, and Tape with crosswise and lengthwise structure. 2) Testing current collection and verifying tether dynamical stability. 3) Preliminary design of tape dimensions for a generic mission, conducive to low system-to-satellite mass ratio and probability of cut by small debris, and ohmic-effects regime of tether current for fast de-orbiting. Reaching TRL 4-5, BETs appears ready for in-orbit demostration.

Development and Testing of a Fiber Bragg Grating Strain Sensor for Uniaxial Compression of Rock Specimens

Los sensores de fibra óptica son una tecnología que ha madurado en los últimos años, sin embargo, se requiere un mayor desarrollo de aplicaciones para materiales naturales como las rocas, que por ser agregados complejos pueden contener partículas minerales y fracturas de tamaño mucho mayor que las galgas eléctricas usadas tradicionalmente para medir deformaciones en las pruebas de laboratorio, ocasionando que los resultados obtenidos puedan ser no representativos. En este trabajo fueron diseñados, fabricados y probados sensores de deformación de gran área y forma curvada, usando redes de Bragg en fibra óptica (FBG) con el objetivo de obtener registros representativos en rocas que contienen minerales y estructuras de diversas composiciones, tamaños y direcciones. Se presenta el proceso de elaboración del transductor, su caracterización mecánica, su calibración y su evaluación en pruebas de compresión uniaxial en muestras de roca. Para verificar la eficiencia en la transmisión de la deformación de la roca al sensor una vez pegado, también fue realizado el análisis de la transferencia incluyendo los efectos del adhesivo, de la muestra y del transductor. Los resultados experimentales indican que el sensor desarrollado permite registro y transferencia de la deformación fiables, avance necesario para uso en rocas y otros materiales heterogénos, señalando una interesante perspectiva para aplicaciones sobre superficies irregulares, pues permite aumentar a voluntad el tamaño y forma del área de registro, posibilita también obtener mayor fiabilidad de resultados en muestras de pequeño tamaño y sugiere su conveniencia en obras, en las cuales los sistemas eléctricos tradicionales tienen limitaciones. ABSTRACT Optical fiber sensors are a technology that has matured in recent years, however, further development for rock applications is needed. Rocks contain mineral particles and features larger than electrical strain gauges traditionally used in laboratory tests, causing the results to be unrepresentative. In this work were designed, manufactured, and tested large area and curved shape strain gages, using fiber Bragg gratings in optical fiber (FBG) in order to obtain representative measurement on surface rocks samples containing minerals and structures of different compositions, sizes and directions. This reports presents the processes of manufacturing, mechanical characterization, calibration and evaluation under uniaxial compression tests on rock samples. To verify the efficiency of rock deformation transmitted to attached sensor, it was also performed the analysis of the strain transfer including the effects of the bonding, the sample and the transducer. The experimental results indicate that the developed sensor enables reliable measurements of the strain and its transmission from rock to sensor, appropriate for use in heterogeneous materials, pointing an interesting perspective for applications on irregular surfaces, allowing increasing at will the size and shape of the measurement area. This research suggests suitability of the optical strain gauge for real scale, where traditional electrical systems have demonstrated some limitations.

Sonic anemometry of planetary atmospheres

The application of a recently developed model of sonic anemometers measuring process has revealed that these sensors cannot be considered as absolute ones when measuring spectral characteristics of turbulent wind speed since it is demonstrated that the ratios of measured to real spectral density functions depend on the composition and temperature of the considered planetary atmosphere. The new model of the measuring process of sonic anemometers is applied to describe the measuring characteristics of these sensors as fluid/flow dependent (against the traditional hypothesis of fluid/flow independence) and hence dependent on the considered planetary atmosphere. The influence of fluid and flow characteristics (quantified via the Mach number of the flow) and the influence of the design parameters of sonic anemometers (mainly represented by time delay between pulses shots and geometry) on turbulence measurement are quantified for the atmospheres of Mars, Jupiter, and Earth. Important differences between the behavior of these sensors for the same averaged wind speed in the three considered atmospheres are detected in terms of characteristics of turbulence measurement as well as in terms of optimum values of anemometer design parameters for application on the different considered planetary atmospheres. These differences cannot be detected by traditional models of sonic anemometer measuring process based on line averaging along the sonic acoustic paths.

How do Impurity Inclusions Influence the Mechanical Properties of Multicrystalline Silicon?

The purpose of this research is to characterise the mechanical properties of multicrystalline silicon for photovoltaic applications that was crystallised from silicon feedstock with a high content of several types of impurities. The mechanical strength, fracture toughness and elastic modulus were measured at different positions within a multicrystalline silicon block to quantify the effect of impurity segregation on these mechanical properties. The microstructure and fracture surfaces of the samples was exhaustively analysed with a scanning electron microscope in order to correlate the values of mechanical properties with material microstructure. Fracture stresses values were treated statistically via the Weibull statistics. The results of this research show that metals segregate to the top of the block, produce moderate microcracking and introduce high thermal stresses. Silicon oxide is produced at the bottom part of the silicon block, and its presence significantly reduces the mechanical strength and fracture toughness of multicrystalline silicon due to both thermal and elastic mismatch between silicon and the silicon oxide inclusions. Silicon carbide inclusions from the upper parts of the block increase the fracture toughness and elastic modulus of multicrystalline silicon. Additionally, the mechanical strength of multicrystalline silicon can increase when the radius of the silicon carbide inclusions is smaller than ~10 µm. The most damaging type of impurity inclusion for the multicrystalline silicon block studied in this work was amorphous silicon oxide. The oriented precipitation of silicon oxide at grain and twin boundaries eases the formation of radial cracks between inclusions and decreases significatively the mechanical strength of multicrystalline silicon. The second most influencing type of impurity inclusions were metals like aluminium and copper, that cause spontaneous microcracking in their surroundings after the crystallisation process, therefore reducing the mechanical response of multicrystalline silicon. Therefore, solar cell producers should pay attention to the content of metals and oxygen within the silicon feedstock in order to produce solar cells with reliable mechanical properties.