New Protocol for Twinning of Raman Devices Toward a Raman Intensity Harmonization.

The use of Raman spectroscopy has rapidly been on the rise across a great number of industries where comparability, reproducibility, and reliability of the data are of paramount importance. However, controlling the intensity of the Raman signal depends on a large number of factors such as the wavelength of the laser light, the optical components of each device, or the number of molecules in the illuminated volume. For this reason, in this study, a new protocol has been applied to twin Raman devices to achieve a conversion of the signal between them, by pairing the intensity response of the units using a reference sample. The new reference material is a homogenous dispersion of a 0.5 wt% anatase (titanium dioxide, or TiO2) in an epoxy resin matrix, with deviations <2.5% in Raman intensity across the reference material. The proposed protocol for Raman-twinned devices takes a well-defined approach that leads to obtaining a correction factor that relates the differences in the signal intensity between the two Raman devices, in order to obtain the same Raman intensity counts. The performance of the proposed method was evaluated based on the data from the devices, which presented the most common user cases: twinning Raman devices of the non-confocal same model for two different wavelengths; and twinning confocal and non-confocal devices. The results obtained show that the protocol has worked for both of the Raman twinning cases, allowing the Raman intensity harmonization of Raman spectra between two different devices.

Highly Efficient Antimicrobial Ceramics Based on Electrically Charged Interfaces.

The increasing threat of multidrug-resistant microorganisms is a cause of worldwide concern. This motivates a necessity to discover new antimicrobial agents or new mechanisms for microorganism eradication, different from those currently used. Here, we report an effective antibacterial ceramic glaze that combines different bactericidal mechanisms. Specifically, the used methodology of the glaze results in glass-free edge crystallizations of feldspar structures at the ceramic surface. A combination of Rutherford backscattering spectroscopy, scanning electron microscopy, and Raman microscopy is used to determine the chemical elements and crystallizations at the ceramic surface. Moreover, Kelvin probe force microscopy demonstrates that the presence of glass-free edges in feldspar needle crystals (semiconductor phase) on a glass matrix (insulator phase) promotes the formation of semiconductor-insulator interface barriers. These barriers act as reservoirs of electric charges of ∼1.5 V, producing a discharge exceeding the microorganism membrane breakdown value (up to 0.5 V). Furthermore, the surface crystallizations account for the formation of a microroughness that limits biofilm formation. Both factors result in high antibacterial activity in the range of R > 4 for Escherichia coli and Staphylococcus aureus. This approach opens new possibilities to attain bactericidal surfaces and to understand the role of physical interaction as a main antimicrobial mechanism.

Revealing the Role of the Intermediates during the Synthesis of BaTi5O11.

BaTi5O11 has been extensively studied because of their microwave dielectrics properties. Traditionally, it is difficult to achieve this material as single-phase. Here, we report an effective method to obtain BaTi5O11 powder with nanometer-scale crystals, by solid-state reaction at moderate temperatures and using as precursors nanostructured particles consisting of BaTiO3 and TiO2. The main advantage is the intimate contact between the BaTiO3 and TiO2 that ensure, when the solid-state reaction takes place, the formation of complex solid compounds from three or more constituents. The formation mechanism of BaTi5O11 has been studied as a function of both the thermal treatment and the time reaction. The reaction was monitored by Raman spectroscopy combined with Confocal microscopy, the aim of this characterization technique is to provide the description of the general strategy and design principles to obtain BaTi5O11 powder. Consequently, this work is a challenging task for the compositional and structural study of complex inorganic nanoparticles.