Non-toxic Media Research Articles

Eco-friendly Approach for Creation of Resonant Silicon Nanoparticle Colloids

The commercial application of Mie-resonant nanophotonic technologies currently used in various laboratory studies, from biosensing to quantum optics, appears to be challenging. Development of colloidal-based fabrication approaches is a solution to face the issue. In our research, we studied the fabrication of resonant Si nanoparticle (NP) arrays on a surface with controlled wettability. First, we use nanosecond (ns) laser ablation in water and subsequent density gradient separation to obtain colloids of resonant spherical crystalline silicon NPs with a low polydispersity index. Then, the same industrial ns laser is applied to create a wetting gradient on the steel substrate to initiate a self-assembly of the NPs deposited by drop casting. Thus, we use a single commercial ns laser for producing both the NPs and the hydrophilic wetting gradient. We apply an easily operating size separation technique and only non-toxic media. This research contributes to the large-scale fabrication of various optical devices based on resonant high-refractive index nanostructures by ecologically friendly self-assembly techniques.

Fe(III)-Catalyzed N-Amidomethylation of Secondary and Primary Anilines with TosMIC.

A Fe(III)-catalyzed N-amidomethylation of secondary and primary anilines with p-toluenesulfonylmethyl isocyanide (TosMIC) in water is described. TosMIC plays dual roles as the source of methylene as well as an amidating reagent to form α-amino amides in this multicomponent reaction. The combination of TosMIC and other isocyanides was also investigated to give the desired products in acceptable yields. The current protocol features use of iron catalyst and nontoxic media, broad substrate scope, mild conditions, and operational simplicity.

Sulfonitrocarburizing of High-Speed Steel Cutting Tools: Kinetics and Performances.

The scholarly literature records information related to the performance increase of the cutting tools covered by the superficial layers formed “in situ” when applying thermochemical processing. In this context, information is frequently reported on the carbamide role in processes aiming carbon and nitrogen surface saturation. Sulfur, together with these elements adsorbed and diffused in the cutting tools superficial layers, undoubtedly ensures an increase of their operating sustainability. The present paper discusses the process of sulfonitrocarburizing in pulverulent solid media of high-speed tools steel (AISI T1, HS18-0-1) and its consequences. The peculiarity of the considered process is that the source of nitrogen and carbon is mainly carbamide (CON2H4), which is found in solid powdery mixtures together with components that do not lead to cyan complex formation (non-toxic media), and the sulfur source is native sulfur. The kinetics of the sulfonitrocarburizing process, depending on the carbamide proportion in the powdered solid mixture and the processing temperature, was studied. The consequences of the achieved sulfonitrocarburized layers on the cutting tools’ performance are expressed by the maximum permissible cutting speed and the maximum cut length. An interesting aspect is highlighted, namely the possibility of using chemically active mixtures. Their components, by initiation of the metallothermic reduction reaction, become able to provide both elements of interest and the amount of heat needed for the ultrafast saturation of the targeted metal surfaces.

Iron-Mediated Selective Sulfonylmethylation of Aniline Derivatives with p-Toluenesulfonylmethyl Isocyanide (TosMIC).

An iron-mediated highly selective C-H sulfonylmethylation of aniline derivatives with p-toluenesulfonylmethyl isocyanide in a mixture solvent of H2O and PEG400 under an Ar atmosphere has been realized. This transformation proceeds with operational convenience, use of earth-abundant metal catalyst and nontoxic media, broad substrate scope, and good functional group tolerance. The current methodology could be applied to the regioselective C-H sulfonylmethylation of indolines, tetrahydroquinolines, and tertiary anilines.

A Practical Green Synthesis of bis(Pyrazolyl)methanes Using Mohr’s Salt

In recent decades, safe green synthetic approaches have attracted much interest from chemists.1–3 Running chemical reactions in safe and non-toxic media, such as water, is one of these approaches, ...

Characteristics of a New Polymer Electrolyte Electrolysis Technique with Only Cathodic Media Supply Coupled to a Photovoltaic Panel

Herein we discuss polymer electrolyte membrane (PEM) electrolysis stacks and systems we developed that are optimized for direct coupling to a photovoltaic (PV) panel. One advantage of PEM systems is their use of non-corrosive and non-toxic media. Thus, safe outdoor operation can be guaranteed, even in the case of a leakage. The system design was adapted to reduce the number of connection tubes, allowing for a series connection of multiple stacks at low cost and high reliability. One coupled PEM/PV system was tested under various temperature and irradiance conditions. All system components were also thoroughly characterized. The characterization was used to calibrate simple models of the individual components. Finally, the models were used to predict the system’s solar-to-hydrogen efficiency under different operating conditions and to find an optimal configuration for real-world outdoor operation.

Toxin-Producing Anabaena flos-aquae Induces Settling of Chlamydomonas reinhardtii, a Competing Motile Alga.

Toxin production is an adaptation that allows cyanobacteria in resource-limiting environments to ameliorate the effects of herbivory and competition with other phototrophs. We demonstrate that the cyanobacterial toxins anatoxin-a and microcystin-LR paralyze the motile green alga Chlamydomonas reinhardtii. In addition, both purified toxins and cyanobacterial extracellular products containing these toxins cause the alga to settle faster than in nontoxic media. In microcosm experiments, the presence of either the cyanobacterium or its extracellular products induce settling in the alga, similar to the response observed with the addition of both anatoxin-a and microcystin-LR. The cyanobacterial production of paralyzing toxins represents a novel mechanism for phytoplankton settling. This prokaryotic/eukaryotic chemical interaction may create a competitor-free zone for cyanobacteria in lake environments, predicating optimal conditions for a toxic cyanobacterial bloom.

Cryopreservation of mammalian ova and embryos by vitrification

Vitrification is a new approach to oocyte and embryo cryoconservation. It consists in the solidification of a solution caused not by crystallization, but by a drastic increase in viscosity during cooling. The application of this approach to cryoconservation of oocytes and embryos of different species depends upon the development of proper procedures and non-toxic media. From the technical point of view, the vitrification method is simple and relatively easily applicable under field conditions. The authors review the current procedures applied to oocytes and embryos of laboratory and farm animals.

Wheat gliadin: digital imaging and database construction using a 4-band reference system of agarose isoelectric focusing patterns.

An isoelectric focusing method using thin-layer agarose gel has been developed for wheat gliadin. Using flat-bed units with a third electrode, up to 72 samples per gel may be analyzed. Advantages over traditional acid polyacrylamide gel electrophoresis methodology include: faster run times, nontoxic media, and greater sample capacity. The method is suitable for fingerprinting or purity testing of wheat varieties. Using digital images captured by a flat-bed scanner, a 4-band reference system using isoelectric points was devised. Software enables separated bands to be assigned pI values based upon reference tracks. Precision of assigned isoelectric points is shown to be on the order of 0.02 pH units. Captured images may be stored in a computer database and compared to unknown patterns to enable an identification. Parameters for a match with a stored pattern may be adjusted for pI interval required for a match, and number of best matches.

An experimental search for phytoplanktonic algae producing external metabolites which condition natural sea waters

In a search for phytoplanktonic algae which may condition water masses by excreted metabolites monocultures of 29 species of diatoms and flagellates, also of one sedentary alga, were tested with developing eggs and larvae of two species of sea-urchin and of a polychaete. Results indicated that about half of the algal species examined, using both unfiltered cultures and filtrates from them, probably do not produce metabolites affecting development of the three animal species employed in this work. Others were harmful or favourable to them in various ways. One flagellate species in particular, Olisthodiscus luteus N. Carter was of outstanding interest, with effects on larvae varying from toxic to favourable according to culture density and amount of dilution with normal sea water. Ancillary experiments eliminated the possibility that excessively high or low pH could be responsible for observed effects, while others showed that in a semi-toxic environment crowding of eggs and larvae can be beneficial but not in non-toxic media. In the main experimental search for possible effects of metabolites, eggs and larvae were never crowded.