Colloidal suspensions of carbon nanostructures (CNSs) were prepared by laser fragmentation in various liquid media using heat-treated coffee grounds as carbon precursor. A study by calorimetry was done in powder of waste coffee grounds to determine the temperature of obtaining carbon. The experiments were carried out in two stages, the first one consisted in obtaining the carbon source, for which powder of waste coffee grounds was thermally treated in air. The as-obtained carbon was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and infrared spectroscopy. In the second step the as-obtained carbon was separately dispersed in four liquid media (acetone, toluene, methanol and isopropyl alcohol) to be fragmented by using a ns-pulsed Nd:YAG laser at its 1064 nm fundamental emission. The morphological features of the carbon nanostructures were obtained by transmission electron microscopy, while the optical properties of the colloidal suspensions were characterized by UV-Vis and photoluminescence spectroscopies. Results indicate that carbon nanostructures are successfully obtained in the four liquid media after the fragmentation process. The four colloidal suspensions show photoluminescent properties, which are seen to depend on the liquid medium nature. We found that the liquid medium also influences the efficiency of the laser fragmentation.

Numerical calculations were performed on NbN/Nb and TiN/Ti nanostructured bilayers. Discrete dipole approximationimplemented in the DDSCAT code was utilized. In order to design a TUC (Target Unit Cell) with realistic surfaceroughnesspattern, Atomic Force Microscope images of 100 ±10 nm Nb thin films were used. The optical properties of nanostructured bilayers (60-100 nm thickness with a ±10 nm surface roughness) were calculated, keeping the interfacebetween the layers as smooth flat surfaces. For the NbN/Nb nanostructure with a thickness between 100 ±10 nm, and 70 ±10 nm, in a wavelength range between 200 and 350 nm, the reflectance and absorptance show a nearly flat spectrumwith an intensity of 20% and 80%, respectively. For larger wavelengths, absorptance decays smoothly. In contrast, for the 60 ±10 nm bilayer, the absorptance decays faster. For the TiN/Ti nanostructure, at 415 nm, a relative maximum in the reflectance, and a minimum in absorptance, are observed. The critical value of the absorbed light spectra begins to shift to higher wavelengths as the thickness of the TiN layer increases. We demonstrate that adding a rough nitride layer on top of its metallized layer drastically modifies the optical response of the nanostructured bilayer, an interesting result forplasmonics and nanoelectronics applications.

The setting and hardening of cement paste can be taken as the progressive hydration reaction of cement. This paper reports the findings on setting time of cement paste at early hydration by using a novel method named relative electrical impedance (REI). The novel REI method measures the relative electrical impedance between electrodes (ring shaped) embedded in the cement paste. REI measurements were conducted on cement paste samples with a water-cement ratio of 1:2 over 24 hours. REI measurements were compared with VICAT and heat latent methods for indirect validation. It was found that the proposed REI technique determined the 4 periods of the setting time process (sleeping, hydration, deceleration, and diffusion) and allowed the measurement of the sleeping period in detail. It was concluded that the novel REI method could be used as a new method to measure the setting time of cement paste in early hydration.

TiO2 has been widely studied and synthesized by various methods due to its excellent optoelectronic properties. It is possible to modify the optical properties of TiO2 by incorporating noble metal nanoparticles in order to improve its photoresponse. In this work, TiO2-Au thin film composites were grown by pulsed laser deposition technique. Ti and Au targets were simultaneously ablated in order to produce combined plasmas under a reactive atmosphere containing oxygen at a pressure of 2×10-2 Torr. The plasmas were analyzed individually by means of a planar Langmuir probe in order to calculate their mean kinetic ion energy and plasma density. Ti plasma parameters were kept constant at 196 eV and 2.06×1013 cm-3 while the Au plasma density was varied from 2.65×1012 cm-3 to 22.4×1012 cm-3. The samples were characterized by UV-Vis spectroscopy and scanning electron microscopy. The band gap of the films was determined by means of the Tauc method, which decreased from 2.36 to 1.54 eV as the Au plasma density increased. The resultant morphology of the films shows the formation of spherical Au nanoparticles, whose average sizes increases as the Au plasma density increased, resulting in values ranging from 15 to 72 nm.

Photopyroelectric technique, in the transmission configuration, was shown adequate for the measurement of the optical properties of pure liquids. The analytical scheme involves the scanning of the photopyroelectric signal as a function of the sample thickness. Optical absorption coefficients, at four wavelengths in the near infrared region (904 nm, 980 nm, 1310 nm, and 1550 nm), were measured for eight pure substances, distilled water and glycerol, among them. Strong optical absorption was obtained, particularly for pure liquids with a hydroxyl group in their molecular structure. In order to figure out about the influence of this chemical group on optical properties as function of the size of the molecule, optical absorption coefficient for a series of linear alcohols at 1550 nm was also measured.

We present the preliminary theoretical-experimental study of the structural properties for rare earths: hydroxide, hydroxycarbonate and Oxide; Sm(OH)3, NdOHCO3, CeO2, and Ho2O3 powders, respectively. In the experimental preparation, Chemical Bath Deposition (CBD) technique is applied at ~20 ±2 °C. In our experimental conditions, the parameters of crystal growth are: concentration of progenitor reagents, stirring, pH and temperature, remain constant. The chemical kinetics of crystal growth is systematically examined at key synthesis steps, considering the physicochemical and electrodynamic parameters: ionic radii, electron affinity, and hydration enthalpy of the rare earth (Sm3+, Nd3+, Ce3+, and Ho3+) cation. The main objective of this report is to investigate the theoretical-experimental correlation associated with the experimental conditions and the physicochemical parameters in the synthesis of hydroxide, hydrocarbonates and oxide. The crystallographic study of the powders is carried out using the X-ray Diffraction (XDR) technique. Analyzing the crystal phase, it is found that Sm(OH)3 and NdOHCO3 present hexagonal crystal phase, CeO2 and Ho2O3 are identified cubic crystal structure. The quantified grain size turns out to be: Sm(OH)3: ~1.40 - 2.03 nm, NdOHCO3: ~14.33 - 22.25 nm; CeO2: ~1.65 - 3.05 nm; and Ho2O3: ~3.72 - 6.08 nm. The Dislocation density (?) is: Sm(OH)3: ~2.47 - 5.10×1017 lines/m2; NdOHCO3: 2.01 - 4.68×1015 lines/m2; CeO2: 1.07 - 3.67×1017 lines/m2.

Surface coating is a method used for protection against corrosion and environmental impact for metals. In the case of solid surfaces, coatings can be achieved by radio-frequency magnetron sputtering or other corrosion-resistant substances, which may involve the deposition of one or more layers, depending on the procedure involved, modifying the morphology of the surface and surface area. This work aims to study the relationship of two surface morphological methods through roughness and fractal dimension measurements in top-surface coatings, bilayer Ti/WTiN/WTiC (named as n = 1); multilayer [Ti/WTiN/WTiC] (named as n = 40) deposited by RF-magnetron sputtering. The measurements were obtained by profilometer and image processing pixel intensity. The topography of each coating exhibited texture with impurities as domes distributed in small cluster island types. The surface roughness were 9.42 and 18.63 nm; fractal dimension measurements were 2.55 and 2.32, respectively, with a low correlation between roughness and fractal dimension. The R-squared analysis exhibited a good relationship between the fractal dimension values, tending linear regression negative. The result of factorial design 22 confirmed the performance correlation and linear regression analyses. The fractal dimension measurements by the optical method can be great potential to evaluate surface roughness complementary in applications such as laboratories and even in scale industrial. Thus the result of statistical treatment shows high accuracy in the measurements.

In this paper, we have shown the results of the analysis by the SIMS method of mouse fibroblast cells (3T3-F44A2 line) grown on the silicon surface and fixed by using different chemicals. It was concluded that the standard method of dehydration and fixation of cells with the help of glutaraldehyde allows us to prepare relevant samples for analysis by the SIMS in ultrahigh vacuum. Ion images of chemical elements inside cells with a sufficiently high lateral resolution were obtained, allowing us to study, among other things, the internal structure of cells. The use of SIMS looks preferable for the analysis of cellular metabolism, cell differentiation, ischemia and other processes in cells and tissues grown using special medications and (or) reagents with an artificial isotopic composition of stable isotopes.