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The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4). The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

This research aimed to evaluate the effectiveness of new organic substances, including a novel ionic liquid based on polyhexamethylenebiguanidine, polyhexamethyleneguanidine, and safranin in the copper electrorefining process. Experiments were conducted on a small laboratory scale using industrial copper anodes. Single doses of new additives did not improve process indicators (current efficiency, average cell voltage, specific energy consumption) or the quality of copper cathode deposits. However, a combination of a new ionic liquid based on polyhexamethylenebiguanidine and thiourea resulted in a satisfactory current efficiency of 97%, an average cell voltage of 0.110 V, a low specific energy consumption index of approximately 100 kWh/t Cu , and smooth cathode surfaces. These results were superior to those obtained with industrial additives (bone glue and thiourea). The findings enhance our understanding of how these substances influence the electrorefining process and suggest the potential for more efficient and sustainable methods. Further research is recommended to validate these findings and explore their industrial applications.

Background: A growing body of evidence indicates that the COVID-19 pandemic has had detrimental mental health effects for pregnant women. However, little is known about the specific stressors that increased anxiety for pregnant women at the start of the pandemic. The present study aimed to better understand the concerns of pregnant women during the beginning COVID-19 pandemic by analyzing content posted during the month of March 2020 on online pregnancy message boards hosted on WhatToExpect.com., Methods: All posts published between March 1-31, 2020 on nine different due-date specific WhatToExpect.com message boards were reviewed for COVID-19 relevance. Posts mentioning COVID-19 or its direct effects (e.g., "quarantine" or "stay-at-home order") were included in our final sample. Data were coded by three authors according to a codebook developed inductively by all four authors. Posts were analyzed by overall frequency of appearance, by trimester, and temporally across the month of March 2020., Results: Across the 5,541 posts included in our final sample, the most common topics were fear of COVID-19 exposure, concerns with labor and delivery, navigating social interactions, and disruptions to prenatal care. The most dominant topics by trimester were disruptions to prenatal care (first trimester), fear of COVID-19 exposure (second trimester), and concerns about labor and delivery (third trimester)., Conclusion: Our findings add to prior literature by demonstrating the salience of social concerns, which was the third largest COVID-19 topic in our sample. Emotional distress was most salient with regard to restrictions on birthing partners, but was apparent in everything from disruptions to pregnancy announcements, to cancelled baby showers, and limitations on newborn visitors. Given that anxiety during pregnancy is associated with worse maternal-fetal health outcomes, in the early stages of future pandemics healthcare providers should focus not only on strictly health-related concerns expressed by pregnant women, but also more broadly on other sources of anxiety that may be impacting the well-being and mental health of their patients., (© 2022. The Author(s).)

Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.

This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders.