Photoinduced Fluidity and Viscoelasticity in Chalcogenide Glasses

This work is an attempt to apply conventional mechanical testing to characterize the photoinduced viscoelastic behavior of chalcogenide glasses. Creep or relaxation-recovery experiments are usually performed to characterize the delayed elastic contribution to deformation, during thermally activated flow. In this article, relaxation-recovery is used to characterize delayed elasticity under irradiation condition and to investigate the influence of the photon irradiation on the viscoelastic behavior. It is showed that thermally activated processes and photoinduced ones are decoupled. The viscoplastic deformation under irradiation is the sum of thermally activated and photoinduced processes. As soon as the irradiation ceases, chalcogenide glasses behave exactly as if they had never been irradiated. The photoinduced viscoelastic behavior seems to be solely due to transient photoinduced structural defects.     

Cold-set whey protein microgels for the stable immobilization of lipids

Novel sub-millimeter cold-set whey protein isolate (WPI) microgels for the stable immobilization of lipids were prepared by an emulsification/internal gelation technique. Microgels were prepared by the addition of a denatured WPI/lipid primary emulsion (containing a micronized calcium source) into an oil bath with gentle stirring, into which an oil soluble acid was added to liberate calcium and initiate gelling of the whey-based matrices. The efficiency of these matrices to entrap lipids was assessed by comparing to extrusion/externally gelled matrices, where the production process is potentially less destructive, but microgels under 1 mm in diameter are difficult to achieve. The micron-sized (below 100 μm in diameter) internally gelled matrices produced by an optimized process, successfully immobilized incorporated lipids, with greater than 93% retention of lipids, regardless of the investigated manufacturing conditions. Migration of exterior oil, during the O/W/O production process, into the microgels was also avoided. Examination of the micro-structure by scanning electron microscopy revealed voids uniformly distributed throughout the matrix, representative in size (under 0.4 μm) of the original primary emulsion lipid droplets. The study shows relevant feasibility for the stable inclusion of a wide range of sensitive lipophilic bioactive ingredients into these matrices, where the sub-millimeter size of the microgels represents potential for incorporation into a variety of food systems.     

Highly defective graphene: A key prototype of two-dimensional Anderson insulators

Electronic structure and transport properties of highly defective two-dimensional (2D) sp² graphene are investigated theoretically. Classical molecular dynamics are used to generate large graphene planes containing a considerable amount of defects. Then, a tight-binding Hamiltonian validated by ab initio calculations is constructed in order to compute quantum transport within a real-space order-N Kubo-Greenwood approach. In contrast to pristine graphene, the highly defective sp² carbon sheets exhibit a high density of states at the charge neutrality point raising challenging questions concerning the electronic transport of associated charge carriers. The analysis of the electronic wavepacket dynamics actually reveals extremely strong multiple scattering effects giving rise to mean free paths as low as 1 nm and localization phenomena. Consequently, highly defective graphene is envisioned as a remarkable prototype of 2D Anderson insulating materials.      

Investigation of microstructure-property relantionships of magnesia-hercynite refractory composites by a refined digital image correlation technique

Industrial magnesia-spinel bricks destined for thermal shock applications often show more flexibility and improved crack growth resistance. Components from the spinel structure group are usually added to promote microcracking coming from thermal expansion mismatch. This leads to the development of toughening mechanisms that are very effective in improving the crack propagation resistance.Magnesia-hercynite composites were investigated in order to highlight their fracture process, with regard to their microstructure, by using Digital Image Correlation (DIC). The direct measurement of displacement fields between digital images of the reference state and the deformed one has provided valuable information on material deformation during loading. The aim of this work was to investigate the fracture behaviour of refractories through the coupling of the Wedge Splitting Test (WST) and DIC. By using a refined DIC process transformation taking into account a discontinuity of displacement, called 2P-DIC, a more effective characterisation of the fracture behaviour was achieved.     

Infrared Spectrum of Ozone in the 4600 and 5300 cm-1 Regions: High Order Accidental Resonances through the Analysis of nu1 + 2nu2 + 3nu3 - nu2, nu1 + 2nu2 + 3nu3, and 4nu1 + nu3 Bands

The very weak bands nu1 + 2nu2 + 3nu3 and 4nu1 + nu3 of 16O3 have been observed for the first time, using the Fourier transform spectrometer (FTS) of Reims and the usual experimental setup providing a large product p x l of approximately 38 Torr x 36 m. The upper levels of these A-type bands which are rather close in energy (they appear respectively at 5291.722 and 5307.790 cm-1) belong to two different sets of interacting polyads. To correctly reproduce the rotation-vibration energy levels and account for the observed perturbations, both bands are treated in a dyad approximation: the (123) state in the Coriolis resonance with the (330) state, and the (401) state in the Coriolis resonance with the (024) state. The assignments of the rotation-vibration levels of the (123) state are confirmed by measurements of line positions of the hot band nu1 + 2nu2 + 3nu3 - nu2 which has also been observed for the first time. The fits are very satisfactory: the r.m.s. deviation for 249 energy levels of the (123) state is 2.4 x 10(-3) cm-1 and is 2.0 x 10(-3) cm-1 for 266 levels of the (401) state. These r.m.s. are near experimental accuracy. Transition moments for the three observed bands are determined from measured line intensities. Copyright 1997 Academic Press. Copyright 1997Academic Press     

3-D relative positioning sensor for indoor flying robots

Swarms of indoor flying robots are promising for many applications, including searching tasks in collapsing buildings, or mobile surveillance and monitoring tasks in complex man-made structures. For tasks that employ several flying robots, spatial-coordination between robots is essential for achieving collective operation. However, there is a lack of on-board sensors capable of sensing the highly-dynamic 3-D trajectories required for spatial-coordination of small indoor flying robots. Existing sensing methods typically utilise complex SLAM based approaches, or absolute positioning obtained from off-board tracking sensors, which is not practical for real-world operation. This paper presents an adaptable, embedded infrared based 3-D relative positioning sensor that also operates as a proximity sensor, which is designed to enable inter-robot spatial-coordination and goal-directed flight. This practical approach is robust to varying indoor environmental illumination conditions and is computationally simple.     

REPro.JPEG: a new image compression approach based on reduction/expansion image and JPEG compression for dermatological medical images

Medical images are known for their huge volume which becomes a real problem for their archiving or transmission notably for telemedicine applications. In this context, we present a new method for medical image compression which combines image definition resizing and JPEG compression. We baptise this new protocol REPro.JPEG (reduction/expansion protocol combined with JPEG compression). At first, the image is reduced then compressed before its archiving or transmission. At last, the user or the receiver decompresses the image then enlarges it before its display. The obtain results prove that, at the same number of bits per pixel lower than 0.42, that REPRo.JPEG guarantees a better preservation of image quality compared to the JPEG compression for dermatological medical images. Besides, applying the REPRo.JPEG on these colour medical images is more efficient while using the HSV colour space compared to the use of RGB or YCbCr colour spaces.     

LASER-DOPPLER ANEMOMETRY IN A BAFFLED MIXING TANK

Experiments were conducted for extremely high turbulent mixing operations in a baffled mixing lank. Three components of the mean and root-mean-square velocities were measured using a laser-Doppler anemometer. The impeller rotation rate, the impeller type, and the impeller location were considered.

Due to the complexity of flow in a baffled mixing tank, there are still several fundamental modeling and computational difficulties in simulating the flow, Thus, these experimental data based on the sophisticated and extensive measurements may improve fundamental modeling methods.

The results show that the flow patterns depend on the impeller type. The effect of the impeller location on flow was small. The axial direction of the How was caused by the baffles. The flow was three-dimensional, rotational periodic, and statistically random. This information successfully characterizes the flow in the baffled mixing tank.