Simultaneous Reduction Oxidation Research Articles

The Photoelectric Behavior and Antimicrobial Effect of Titanium Dioxide Deposition for Dental Implants

This work presents a pilot study on the photoelectric effect of anatase titanium dioxide (TiO2) deposited on grade 4 titanium discs on their antimicrobial properties, especially for dental implants applications. The prepared specimens are characterized by X-ray diffraction and Raman spectroscopy to ensure a homogenous coverage of the TiO2 material on the discs. The samples were further tested to outline the photoelectric response of titanium dioxide to ultraviolet radiation in the form of electrical current within the discs. Six discs (three bare Ti, and three coated with TiO2) were seeded with a 5 μl of Escherichia coli culture. One disc of each group was subjected to the same UV light source used for the opto-electrical analysis for 0, 1 or 5 minutes. Bacteria on the discs were then harvested and incubated to examine number of viable cells. The obtained electrical properties confirmed the suitability of the surface-coating to provide simultaneous oxidation-reduction driven reactions under the photoinduced catalytic activity. This activity highlighted the benefits of the added TiO2 layer in reducing the numbers of active E-Coli bacteria in a microbial setup by as much as 21% after 5 minutes of UV exposure. This photoelectrical effect has a profound impact on the development of an in-situ oral disinfectant material deposited on titanium-based dental implants.

Organothiol‐Based Hybrid‐Layer Strategy for High‐Performance Copper Adhesion and Stress‐Migration via Simultaneous Oxide Reduction

The presence of defective native copper‐oxide (CuxO) remains a challenge for device technologies owing to its detrimental effects on the adhesion, moisture sensitivity and stress‐migration. Here we demonstrate a rapid, single‐step, and organic‐solvent‐free sol‐gel deposition process that is capable of simultaneously reducing the weak native Cu‐oxide while forming a densely connected Cu/hybrid interface. A marked 9‐fold improvement in adhesion is reported, along with a substantial decrease in the Cu stress‐migration rate during in‐situ isothermal stress‐relaxation experiments. The enhanced Cu/hybrid interface adhesion and the improved Cu stress‐migration performance were attributed to the partial reduction of the ~2 nm native Cu2O layer as demonstrated via atomic‐resolution transmission electron microscopy. The hybrid‐layer strategy we developed is expected to be effective in not only being a strong candidate for adhesion improvement to Cu, but in promoting Cu stress‐ and the related electro‐migration performance.

Chlorophenol degradation using a one-pot reduction–oxidation process

Chlorophenol degradation was achieved using a combination of hydrodechlorination and heterogeneous Fenton-like oxidation. The process was conducted at ambient conditions (25±2°C, atmospheric pressure) as a one-pot reaction involving formic acid as H2 source for both hydrodechlorination of chlorophenols and H2O2 formation. An alumina-supported Pd–Fe catalyst was applied, which is able to decompose formic acid at the Pd sites, forming H2 and CO2, and additionally H2O2 in the presence of O2. At the same time, due to presence of iron sites on the catalyst, the H2O2 formed can be utilized for a Fenton-like oxidation reaction. Three different reaction protocols were tested, including: (i) consecutive reduction–oxidation with an initial oxygen-free phase adjusted by He purging (CRO–He), (ii) consecutive reduction–oxidation with initially oxygen-limited conditions (CRO) and (iii) simultaneous reduction–oxidation where O2 flowing was started at the beginning of the reaction (SRO). 2,4-Dichlorophenol (DCP) and pentachlorophenol (PCP) were selected as representatives for the group of chlorophenols. For DCP degradation, CRO–He and SRO showed similar efficiencies with respect to the mineralization degree (up to 70%), whereas SRO achieved a better detoxification as observed in bioluminescence tests. The CRO–He reaction over the catalyst used showed only a small decrease in its activity during the oxidation stage, with no further change after the catalyst had been recovered twice. For PCP degradation, a self-inhibition effect was observed for the SRO process, indicating that PCP is hardly degradable by catalytic oxidation. In this case, the CRO–He process, which was facilitated by initial transformation of PCP into phenol and its subsequent oxidation, clearly produced a cleaner medium. This was also confirmed by the results of the toxicity measurements. The catalyst indicated a promising stability based upon the Pd and Fe leaching results measured at the end of each run.

One-Step Preparation of Fibrous Aggregates of Gold Nanoparticles Using Aniline as Reducing Agent as well as Monomer

Nanoscaled fibrous aggregates of gold nanoparticles have been synthesized by a simultaneous reduction-oxidation polymerization process using aniline as reducing agent as well as monomer in an ethanol medium. Time-dependent UV-Vis absorption spectroscopy was used to track the formation process of gold nanoparticles. The transmission electron microscopy (TEM) images and Fourier transform infrared (FT-IR) spectrum of the as-preapred products indicate these gold nanoparticles were binded by the oxidation polymerization resultant of aniline.

Simultaneous reduction of oxides and dissolution of alumina in stainless steelmaking slag

During stainless steelmaking, reductions of oxides, dissolution of oxides in the slag, and foam formation take place simultaneously. Each of these phenomena independently has been studied by a number of investigators, but little information is available for these phenomena acting simultaneously. Experiments have been conducted to study the simultaneous reduction of oxides of chromium, vanadium, and iron from stainless steelmaking slag by carbon along with the dissolution of alumina in the slag. The overall phenomena and the effect on the chromium oxide reduction have been studied.

Reduction of Iron Oxide by Carbon in Stainless Steelmaking Slags

Kinetics of iron oxide reduction by carbon in typical stainless steelmaking slags where slag chemistry changed continuously due to dissolution of $Al_2O_3$ was studied. The progress of reaction was monitored by Xray equipment. A foamy slag formed in all cases. The foaming characteristics and the rate of reduction were dependent on the slag composition. Both chromium and vanadium oxides reduce the reaction rate. Change of slag chemistry due to dissolution of $Al_2O_3$ does not affect the reaction rate. The rate controlling step depends on the stirring of slag due to gas generation by simultaneous reduction of oxides.

Processes occurring during reduction and alloy formation in the MoO3-WO3-H2 system. II. Low-temperature alloy formation in the molybdenum-tungsten system

A study was made of the effect of the composition on low-temperature alloy formation in the molybdenum-tungsten system, using metals obtained at various reduction temperatures from mixed oxides. Reduction of the starting materials was performed by raising the temperature in steps from 370/sup 0/ to 900/sup 0/C. Simultaneous reduction of oxides lowers the temperature of alloy formation in a system composed of fully intersoluble components, and more effective mixing improves still further the homogenization of the alloys. Comparing the lines of molybdenum-tungsten alloys of various compositions, the authors concluded that lowering the concentration of tungsten in the alloys slowed down its dissolution. Comparing data on alloy formation with results of investigations and particle shapes and sizes, it is concluded that the rate of mutual dissolution of molybdenum and tungsten at low temperatures was determined mainly by the mixing of the fine powders. Thus, the conditions of mutual dissolution of tungsten and molybdenum improve when the metals are simultaneously reduced from mixed oxides at the same specific reaction rates.

Investigation of the conditions of preparation of YB6-LaB6 alloys

1. A study was made of the effect of temperature and holding duration on the alloy formation process in the system YB6-LaB6 during the simultaneous reduction of oxides with boron in a vacuum. The optimum conditions of preparation of these alloys are a temperature of 1850°C and a holding period of 1 h. 2. It was established that homogeneous solid solutions of the hexaborides can be produced when, instead of one of the oxides, the charge contains the hexaboride of the given metal. This method can best be employed when one of the oxides exhibits increased volatility. 3. The mechanism of formation of solid solutions of the hexaborides during the simultaneous reduction of oxides is analyzed, and a hypothesis is advanced that the principal accelerating factor is the formation of close contact between the hexaboride particles, resulting from the simultaneous crystallization of the hexaborides on each other. The mobility of the atoms forming during reduction plays a secondary part. 4. It was established that the lattice parameter of solid solutions in the system YB6-LaB6 varies according to a smooth curve with positive deviations from Vegard's rule.