Heat pipes with self-rewetting fluids under low-gravity conditions

The work presents experimental tests about the performance of heat pipes filled with a “self-rewetting“ fluid (alcohol aqueous solutions). Comparison with conventional commercial water heat pipes is also considered. The used fluid exhibits an anomalous increase in the surface tension with increasing temperature. Along these lines, the fluid has been investigated as a possible means to improve heat transfer inside the heat pipes with a focus, in particular, on space applications (next generation satellites). The experiments have been carried out both in normal and in low-gravity conditions (attained onboard a ‘zero-g’ plane, during a parabilic flight campaign). The results have confirmed improved capability of the considered heat pipes with respect to traditional heat pipes filled with water.     

Equilibrium moisture content of clay bricks: The influence of the porous structure

The comprehension of the influence exerted by the material microstructure on the hygrometric properties of clay bricks plays a fundamental role in order to control the condensation phenomena and to avoid the deterioration of the masonry structure. The equilibrium moisture content (MEq) of ordinary and lightweight clay bricks was measured and the correlation with microstructure and pore morphology was investigated. The influence of the pore size and specific surface on the amount of MEq was found to be prevalent when compared to the other physical variables. A statistical model was also set up in order to predict the MEq values.     

Substrate Selection for Full Exploitation of Organic Semiconductor Films: Epitaxial Rubrene on β‐Alanine Single Crystals

Rubrene (RUB) is one of the most studied organic semiconductors because, in the orthorhombic single‐crystal phase, it exhibits a record exciton diffusion length and one of the highest charge carrier mobilities ever reported. Here, thin films of oriented crystalline RUB are successfully grown in vacuum on millimeter‐sized (010)‐β‐alanine (β‐ala) single crystals with a step‐growth protocol, exploiting organic epitaxy. The experimental characterization demonstrates that these RUB films grow in the orthorhombic polymorph with the (100)_RUB plane in contact with the (010)_β‐ala surface and with precise azimuthal orientations. A complementary study of the RUB(100)/β‐ala(010) interface, performed by computational simulations, confirms the epitaxial relations expected by considering the molecular scale corrugations of the surfaces. Moreover, thanks to the wide transparency region of β‐ala, the RUB absorption bands in the UV range are directly detected for the first time. Finally, removal of the water‐soluble substrate enables the integration of the films in field effect transistors as high quality active organic layers. The characteristics of such RUB‐based devices confirm the quality and versatility of epitaxial thin films for use in organic electronics.     

Electrospun Membranes Designed for Burst Release of New Gold-Complexes Inducing Apoptosis of Melanoma Cells

Two non-commercial metallic Au-based complexes were tested against one of the most aggressive malignant melanomas of the skin (MeWo cells), through cell viability and time-lapse live-cell imaging system assays. The tests with the complexes were carried out both in the form of free metallic complexes, directly in contact with the MeWo cell line culture, and embedded in fibers of Polycaprolactone (PCL) membranes produced by the electrospinning technique. Membranes functionalized with complexes were prepared to evaluate the efficiency of the membranes against the melanoma cells and therefore their feasibility in the application as an antitumoral patch for topical use. Both series of tests highlighted a very effective antitumoral activity, manifesting a very relevant cell viability inhibition after both 24 h and 48 h. In the case of the AuM1 complex at the concentration of 20 mM, melanoma cells completely died in this short period of time. A mortality of around 70% was detected from the tests performed using the membranes functionalized with AuM1 complex at a very low concentration (3 wt.%), even after 24 h of the contact period. The synthesized complexes also manifest high selectivity with respect to the MeWo cells. The peculiar structural and morphological organization of the nanofibers constituting the membranes allows for a very effective antitumoral activity in the first 3 h of treatment. Experimental points of the release profiles were perfectly fitted with theoretical curves, which easily allow interpretation of the kinetic phenomena occurring in the release of the synthesized complexes in the chosen medium.     

Analysis of biases in automatic white balance datasets and methods

Annotated datasets for automatic white balance (AWB) are used for the evaluation and, when necessary, the training, of AWB methods. Relying on such datasets requires awareness of the potential bias in their content and characteristics: some methods are designed to rely on the presence of particular elements, such as human skin, while other methods learn implicit relationships between image content and light properties from training data. The dependency on these relationships makes it fundamental to understand whether the available datasets are actually representative of common application scenarios, such as the presence of human subjects, the diversity of composition, or the illumination conditions. In this paper we overview the most common datasets for Automatic White Balance, including those for single as well as multiple illuminant estimation, providing a critical analysis on their characteristics. Furthermore, we identify a number of existing methods for single illuminant estimation, as a representative pool of approaches to the problem with various levels of complexity. We investigate how the performance of these correlate to the image content of common datasets.     

Self-Healing Ability of Poly(PEGMA-5-UPy) Evaluated by Thermomechanical Analysis

The synthesis and characterization of polyethylene glycol monomethyl ether methacrylate (PEGMA) based copolymers incorporating three different percentages (2.5 wt%, 5.0 wt%, and 7.8 wt%) of urea-N-2-amino-4-hydroxy-6-methylpyrimidine-N’-(hexametylen-n-carboxyethyl methacrylate) (HEMA-UPy) are reported. Nuclear magnetic resonance (NMR) and infrared spectroscopy (IR) confirm the synthesis procedure. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are employed to evaluate the thermal properties of the samples. DSC measurements evidence a slight increase in glass transition temperature (T_g), a consistent increase in crystallization and melting temperatures (T_c and T_m), and a reduction in the crystallization degree (X_c) with increasing the amount of HEMA-UPy moiety. Dynamic mechanical analysis (DMA) is carried out at different values of temperature and oscillation frequency. It highlights the ability of the healed copolymer to recover the pristine values of storage modulus. The healing efficiency depends on the temperature history of the sample. For the sample healed at room temperature, the value of healing efficiency is 64%. DMA tests performed at higher temperatures, after some permanence at room temperature, evidence higher values in the healing efficiency. This demonstrates that the higher value of the temperature employed during DMA tests determines greater mobility of the chains causing an enhancement in the healing efficiency.