Search

Ordered clusters of water droplets levitating over a heated water surface can be used as chemical microreactors and computational devices. Here we show that a chemical reaction between melamine and cyanuric acid can occur during coalescence of pairs of droplets containing these reagents and lead to the sedimentation of the product, crystals of melamine cyanurate. In rotating droplets, the crystals flash with frequencies dependent mostly on the rotational velocity of the droplets defined by the rotor of the velocity field of the air-vapor flow above the heated water surface. With the Machine Learning (ML) approach, we trace the brightness and frequencies of individual crystals and convert the frequencies into musical notes thus making a "micro-orchestra" of the levitation cluster., Competing Interests: The authors declare that they have no competing interests., (This journal is © The Royal Society of Chemistry.)

New SERS detection platforms are required for the quick and easy preparation of sensing devices for food, agriculture, and environmental science. For quantitative sensing, it is important that a sensing material, in addition to efficient sensing, provides extraction and concentration of the target molecules such as toxic pesticides or healthy vitamins. We design such films adopting the Liesegang rings formation process that includes the reaction-diffusion of silver nitrate and melamine followed by the precipitation of different intermediates and their reduction by light in a pectin medium. Surprisingly, we find that the presence of melamine provides an excellent substrate for the extraction of pollutants at the solid-liquid interface giving rise to a powerful but easy and fast method for the quantification of fruits' quality. The complex silver and melamine containing films show high sensitivity even at relatively low silver concentrations.

In the present work, transparent flexible thin polymer films with silver patterns have been created. The resulting structures made by the printing method represent a new alternative approach for recording, protecting, and transmitting information as well as for nonlinear gradient material formation. An alphabet for process automatization was created, and an automated system for recording and reading information was developed. To protect the information, we suggest the usage of a classic XOR function: the idea of scrambling is to demonstrate the simple and clear example of coding the ITMO University logo, and the code is provided. Additionally, the resulting samples are functional gradient materials with peaks of surface plasmon resonance. In the following, automated peak decoding by UV-vis spectroscopy allows an additional physicochemical method for structure decoding., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Background: The rise of social media proved to be a fertile ground for the expansion of the acquired immune deficiency syndrome (AIDS)-denialist movement (in the form of online communities). While there is substantial literature devoted to disproving AIDS-denialist views, there is a lack of studies exploring AIDS-denialists online communities that interact with an external environment., Objective: We explored three research areas: (1) reasons for newcomers to come to an AIDS-denialist community, (2) the patterns of interactions of the community with the newcomers, and (3) rhetorical strategies that denialists use for persuasion in the veracity of their views., Methods: We studied the largest AIDS-denialist community on one of the most popular social networking services in Russia. We used netnography as a method for collecting data for qualitative analysis and observed the community for 9 months (at least 2-3 times a week). While doing netnography, we periodically downloaded community discussions. In total, we downloaded 4821 posts and comments for analysis. Grounded theory approach was used for data analysis., Results: Most users came to the community for the following reasons: their stories did not fit the unitary picture of AIDS disease progression translated by popular medical discourse, health problems, concern about HIV-positive tests, and desire to dissuade community members from false AIDS beliefs. On the basis of strength in AIDS-denialist beliefs, we constructed a typology of the newcomers consisting of three ideal-typical groups: (1) convinced: those who already had become denialists before coming to the group, (2) doubters: those who were undecided about the truth of either human immunodeficiency virus (HIV) science theory or AIDS-denialist theory, and (3) orthodox: those who openly held HIV science views. Reception of a newcomer mainly depended on the newcomer's belief status. Reception was very warm for the convinced, cold or slightly hostile for the doubters, and extremely hostile or derisive for the orthodox. We identified seven main rhetorical strategies of persuasion used by the denialists on the "undecided"., Conclusions: Contrary to the widespread public health depiction of AIDS denialists as totally irrational, our study suggests that some of those who become AIDS denialists have sufficiently reasonable grounds to suspect that "something is wrong" with scientific theory, because their personal experience contradicts the unitary picture of AIDS disease progression. Odd and inexplicable practices of some AIDS centers only fuel these people's suspicions. We can conclude that public health practitioners' practices may play a role in generating AIDS-denialist sentiments. In interactions with the newcomers, the experienced community members highlighted the importance of personal autonomy and freedom of choice in decision making consistent with the consumerist ideology of health care. The study findings suggest that health care workers should change a one-size-fits-all mode of counseling for a more complex and patient-tailored approach, allowing for diversity of disease progression scenarios and scientific uncertainty.

Polynuclear species of zirconium in acidic aqueous solution are investigated by combining X-ray absorption spectroscopy (XAFS) and nanoelectrospray mass spectrometry (ESI-MS). Species distributions are measured between pHC 0 and pHC 3 for [Zr]=1.5-10 mM. While the monomer remains a minor species, with increasing pH the degree of polymerization increases and the formation of tetramers, pentamers, octamers, and larger polymers is observed. The high resolution of the mass spectrometer permits the unambiguous determination of polynuclear zirconium hydroxide complexes by means of their isotopic patterns. The relative abundances of mononuclear and polynuclear species present simultaneously in solution are measured, even if one of the species contributes only 0.1% of the Zr concentration. For the first time it has been directly observed that the hydrolysis of polynuclear Zr species is a continuous process which leads to charge compensation through the sequential substitution of water molecules by hydroxide ligands until doubly charged polymers dominate at conditions (H+ and Zr concentrations) close to the solubility of Zr(OH)4(am). The invasiveness of the electrospray process was minimized by using very mild declustering conditions, leaving the polynuclear species within a solvent shell of approximately 20 water molecules.

An ion beam source using electrospray ionization is presented for nondestructive vacuum deposition of mass-selected large organic molecules and inorganic clusters. Electrospray ionization is used to create an ion beam from a solution containing the nanoparticles or molecules to be deposited. To form and guide the ion beam, radio frequency and electrostatic ion optics are utilized. The kinetic energy distribution of the particles is measured to control the beam formation and the landing process. The particle mass-to-charge ratio is analyzed by in situ time-of-flight mass spectrometry. To demonstrate the performance of the setup, deposition experiments with gold nanoclusters and bovine serum albumin proteins on graphite surfaces were performed and analyzed by ex situ atomic force microscopy. The small gold clusters are found to form three-dimensional agglomerations at the surface, preferentially decorating the step edges. In contrast, bovine serum albumin creates two-dimensional fractal nanostructures on the substrate terraces due to strong intermolecular interactions.