Eksperimentalna raziskava procesa skoraj suhe žične elektroerozijske obdelave v kisikovi meglici s kriogenim hlajenjem žice

In this paper, a novel method of cryogenically cooled (low-temperature nitrogen gas) wire tool is used during the oxygen-mist near-dry wire-cut electrical discharge machining (NDWEDM) process to cut Inconel 718 alloy material. The current, pulse-width, pulse-interval, and flow rate are the controllable variables for response characteristics, such as the material removal rate (MRR) and wire wear ratio (WWR). The Box-Behnken method is applied to design the experiments to collect the observations from experiments. The mathematical models for each response were developed using significant individual, interaction, and quadratic terms by the sequential sum of the square test. The response surfaces were developed. It was revealed from the analysis that 52.92 % of current, 24.63 % of Pulse-width, 12.81 % of pulse- interval and 5.75 % of flow rate contributed to MRR, while 14.89 % of current, 9.75 % of pulse-width, 62.20 % of pulse-interval, and 5.44 % of flow rate contributed to WWR. The pulse-width has more contribution on MRR due to the long period of spark between the wire and work materials. It was also observed that the pulse-interval has more effect on WWR due to the more ideal period (high spark-pause-time) between two consecutive high-temperature sparks in the wire tool. The wear of the wire tool has been analysed using scanning electron microscopy (SEM) photographs. The desirability principles were first applied to obtain multi-objective solutions with a combination of process parameters to achieve the optimal values of both responses. The predicted combination of results has been validated by data that were collected from confirmation experiments

A comparative study of pH-responsive microcapsules from different nanocomposites

In this paper, the authors report the preparation of pH-responsive microcapsules using poly(methacrylic acid) and different carbon nanomaterials, graphene oxide (GO) and fullerenol (FOH). Potential non-covalent interactions, as well as a comparative study in terms of stability and structural/morphological aspects of the graphene oxide microcapsules (MGO) and fullerenol microcapsules (MFOH), were carried out using Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry analysis, field emission scanning electron microscopy and high-resolution transition electron microscopy. The comparative drug release study for MGO and MFOH was done using ultraviolet illumination, fluorescence spectroscopy and so on. It was observed that the release of the drug (riboflavin) at pH 4 from MGO was faster, reaching the saturation point before 12 h, compared to that in MFOH, where the saturation point was achieved after 18 h. To the best of the authors' knowledge, this is the first report on a comparative study of MGO and MFOH in terms of their stability, pH-responsive nature and other characteristics. This study can be utilized where the carbon nanomaterials (GO/FOH) are used in the preparation of designer microcapsules for targeted drug delivery applications, since the pH varies in different parts of the human body

Fullerene-Tetrabenzofluorene (C60-TBF) in Multivalent Photosensitisation for Enhanced ZnO-based Photo-catalysts: Mono vs. Hexakis Adduct

Photo-catalysts offer a simple catalytic method with widespread applications like degradation of polluting dyes, hydrogen generation from water, etc., in the presence of a photon source like sunlight. The development of a second-generation photo-catalyst in the form of a nanocomposite is an integral part of research to improve the practical usefulness and efficiency of the process. A systematic study using the active material with controlled functional groups is required to understand the process in detail as well as to develop efficient photocatalytic systems. In this paper, we report the design, synthesis, detailed physicochemical studies, and self-assembly of interesting materials where fullerenes have been functionalized with polycyclic, aromatic, conjugated, butterfly-shaped molecules like Tetrabenzofluorene (TBF) using a well-known click chemistry approach. Detailed analyses using spectroscopic, electrochemical, and microscopic or X-ray diffraction (single crystal) techniques were undertaken for a clear understanding of their photophysical or self-assembly behavior. The functionalized fullerene material was mainly used so that comparative results could be presented where two units (mono adduct) or twelve units (hexakis adduct) of TBF molecules were attached separately. These comparative studies were beneficial for unambiguous interpretation of results and drawing definitive conclusions regarding the energy transfer with cascade-type systems. Finally, those results were useful for the logical understanding of photo-catalytic experiments using those designer fullerene materials