Dustiness Quantification of Powders by the Fractional Release Rate

The handling of dispersed solids may lead to undesirable release of dust particles. Size and quantity of the particles transferred into the gas with time depend on the binding and separating forces in the powder. These in turn are determined by characteristic parameters of the powder and of the process. Analogous to the well‐known “fractional collection efficiency” describing the dust separation, a newly defined “fractional release rate” to quantify the release of dust is introduced. The application is demonstrated by an example and the way to further development of this innovative approach is demonstrated.     

Characterization of piezoelectric ceramics using the burst/transient method with resonance and antiresonance analysis

In this paper, a comprehensive methodology for characterizing the high power resonance behavior of bulk piezoelectric ceramics using the burst method is described. In the burst method, the sample is electrically driven at its resonance frequency, and then either a short circuit or an open circuit condition is imposed, after which the vibration decays at the resonance or antiresonance frequency, respectively. This decay can be used to measure the quality factor in either of these conditions. The resulting current in the short circuit vibration condition is related to the vibration velocity through the “force factor.” The generated voltage in the open circuit vibration condition corresponds to the displacement by the “voltage factor.” The force factor and the voltage factor are related to material properties and physical dimensions of the sample. Using this method, the high power behavior of the permittivity, compliance, effective piezoelectric charge constant, electromechanical coupling factor, and material losses can be determined directly by measuring the resonance (short circuit) and antiresonance (open circuit) frequencies, their corresponding quality factors, the force factor A, and the voltage factor B. The experimental procedure to apply this method is described and demonstrated on commercially available hard and semi‐hard PZT materials of geometry.     

A Preliminary Study of the Toxicological Properties of Selected Polymer–Ferrocene Conjugates

Prompted by early observations of the cytotoxic and antineoplastic properties of certain ferrocene and ferricenium derivatives, efforts in this laboratory were focused on the synthesis of carrier-bound ferrocene compounds. Subsequent cell culture tests carried out with selected conjugates obtained in that program showed these polymers to be highly active antiproliferative agents. In the present project toxicological work has been performed in vivo on several ferrocene conjugates in an effort to assess their toxic effects in experimental animals (CD-1 mice). The conjugates, all based on an ,-DL-polyaspartamide backbone structure, comprise the ferrocene drug model as a terminal on short side chains containing biofissionable amide or ester links for intracellular drug release. The polymers, dissolved in phosphate-buffered saline, have been injected in predetermined concentrations into the vein of the mice, and the maximum tolerated dose (MTD) levels have been determined, the latter referring to the highest dose levels administered that would allow long-term survival of the test animals. For the five conjugates tested, MTD levels range from about 3 to 30 mg Fe/kg or 0.05–0.66 mmol Fe/kg. Compared on a molar metal-to-metal basis with similarly structured platinum conjugates tested previously (MTD, 0.14–2.66 mmol Pt/kg), these values are indicative of comparatively high toxicity of the ferrocene polymers. Some implications of these findings are discussed.     

Opportunities,Challenges and Pitfalls of Using Cannabidiol as an Adjuvant Drug in COVID-19 †

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may lead to coronavirus disease 2019 (COVID-19) which, in turn, may be associated with multiple organ dysfunction. In this review, we present advantages and disadvantages of cannabidiol (CBD), a non-intoxicating phytocannabinoid from the cannabis plant, as a potential agent for the treatment of COVID-19. CBD has been shown to downregulate proteins responsible for viral entry and to inhibit SARS-CoV-2 replication. Preclinical studies have demonstrated its effectiveness against diseases of the respiratory system as well as its cardioprotective, nephroprotective, hepatoprotective, neuroprotective and anti-convulsant properties, that is, effects that may be beneficial for COVID-19. Only the latter two properties have been demonstrated in clinical studies, which also revealed anxiolytic and antinociceptive effects of CBD (given alone or together with Δ⁹-tetrahydrocannabinol), which may be important for an adjuvant treatment to improve the quality of life in patients with COVID-19 and to limit post-traumatic stress symptoms. However, one should be aware of side effects of CBD (which are rarely serious), drug interactions (also extending to drugs acting against COVID-19) and the proper route of its administration (vaping may be dangerous). Clearly, further clinical studies are necessary to prove the suitability of CBD for the treatment of COVID-19.     

Corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D alloys

The microstructure and the corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D magnesium alloys have been investigated. Semi-solid processing leads to a structure with large rounded grains of a solid solution of magnesium (α phase) whereas die-cast alloys are more homogeneous. Electrochemical measurements, particularly with impedance spectroscopy, have shown that the semi-solid cast alloy possesses a corrosion rate at least 35% below that of the die-cast alloy. This can be explained with considering the differences between the composition of the primary α phase and the volume fraction of the β phase, in the two types of alloy.     

Partial electrode method for loss and physical parameter determination of piezoceramics: Simplification,error investigation and applicability

The IEEE standard to determine physical parameters of piezoceramics has been utilized for decades by many researchers, yet it omits presence of important loss factors and possesses serious deficits that restrict accurate parameter determination. To resolve these issues, the partial electrode (PE) method was previously proposed, though the focus has been merely made on development of the method itself. In this study, we provide method simplification and more detailed analysis. The omission of unnecessary samples greatly boosts experiment and analysis process. To prove that the PE method is reliable, possible causes of errors were investigated; it is shown that they were either negligibly small or can be resolved with proper calibration. Furthermore, Applicability of PE method to various types of piezoceramic materials and compatibility with impedance analyzers are shown. Finally, PE method is proved to be reliable and can be alternative to IEEE Standard on Piezoelectricity.     

Polymer–Ferrocene Conjugates Containing an Ester Function in the Connecting Links

Ferrocene, the parent of the metallocene family of organotransition metal compounds, has come to occupy a significant niche in cancer research. Developmental work in the authors' laboratory has been focused on the synthesis of antiproliferative ferrocene conjugates in which the bioactive ferrocene unit is covalently, yet bioreversibly bound (anchored) to water-soluble carrier polymers designed in accordance with requisite biomedical specifications. The anchoring link in most of these conjugates has been an aliphatic spacer containing the biofissionable amide group. In this communication the synthesis of a class of ferrocene conjugates is reported in which the ferrocene group is carrier-anchored through spacers containing an ester link, of interest here because of potentially different drug release behavior. The carriers are polyamides equipped with variously spaced hydroxyl side groups, to which the ferrocenylation agent, 4-ferrocenylbutanoic acid, is connected through esterification. The coupling reactions, mediated by carbodiimide agent and catalyzed by 4-(dimethylamino)pyridine, are carried out in DMF at temperatures not exceeding 65°C, and the water-soluble product polymers are isolated in yields of typically 70–85% by precipitation, aqueous dialysis, and freeze-drying. With the molar feed ratios chosen in these coupling experiments, the incorporation of ferrocene, assessed by ¹H NMR spectroscopy, corresponds to iron contents of roughly 2.5–5.5%, by mass. The conjugates will be included in a forthcoming bioactivity screening program.     

Comments on solid state hydrogen storage systems design for fuel cell vehicles

In recent years, significant research and development efforts were spent on hydrogen storage technologies with the goal of realizing a breakthrough for fuel cell vehicle applications. This article scrutinizes design targets and material screening criteria for solid state hydrogen storage. Adopting an automotive engineering point of view, four important, but often neglected, issues are discussed: 1) volumetric storage capacity, 2) heat transfer for desorption, 3) recharging at low temperatures and 4) cold start of the vehicle. The article shall help to understand the requirements and support the research community when screening new materials.     

Determination of trace isoflavone phytoestrogens in biological materials by capillary electrochromatography

Capillary electrochromatography using a specialty monolithic matrix was utilized in developing a rapid and highly efficient separation of isoflavones in biological materials. Without a preconcentration technique, it is relatively easy to reach ppm-ppb concentrations of these compounds in soy-based foods and verify them structurally using a photodiode array detector. With on-column preconcentration, we were able to measure low-ppb levels in human serum. Using blood samples from human volunteers, whose diet was supplemented by a soy-based product, the method has been validated for high-throughput screening of isoflavones in clinical studies.