Preliminary analysis on roles of metal–organic compounds in the formation of invisible gold

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen, closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit (Kazakhstan), related to post-collisional magmatic-hydrothermal origin. Gold mineralization of the deposit occurs mainly in the form of an “invisible” type of gold in the structures of arsenian pyrite and arsenopyrite, and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous formation. Microscopic and electron microscopic analysis, Raman and FT-Infrared analysis, mineralogical and three-step sequential extraction analysis (NH2OH·HCl, H2O2, HNO3 + HCl) has been carried out using 9 ore samples (from 3 different types of ores) for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic matter. The sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm, Pt 31 ppb, and Pd 26 ppb, forming metal–organic compounds, while arsenic sulfide minerals incorporate 11 ppm gold, 39 ppm Ag, 0.49 ppm Pt. The enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this study. Organic matter was active in the migration of gold and the capture of gold by pyrobitumen. Moreover, the reductive organic matter agent released gold, most likely for the sulfide arsenic ore minerals. Pyrobitumen was a decisive factor in the concentration, transportation, and preservation of gold in the deposit.

The Fiery Test of Critique

The book aims to provide a comprehensive study of the ‘Transcendental Dialectic’ of Kant’s first Critique. It argues that Kant conceives of ‘critique’ as a kind of winnowing exercise, aimed to separate the wheat of good metaphysics from the chaff of bad. However, he uses a less familiar metaphor to make this point, namely, that of ‘the fiery test of critique’. This turns out to be, not a medieval ordeal (a trial by fire), but rather a metallurgical assay: so-called ‘cupellation’—a procedure in which ore samples are tested for their precious-metal content. The upshot is that critique has a positive, investigatory side: it seeks not merely to eliminate the dross of bad ‘dogmatic’ metaphysics but also to uncover any hidden nuggets of value that might be contained in traditional speculative metaphysics. There are both gold and silver to be found. The gold is the indirect proof of Transcendental Idealism afforded by the resolution of the Antinomies, the silver Kant’s defence of theoretically grounded ‘doctrinal beliefs’ in a wise and great originator and in an afterlife. In the course of making these points, the book engages with Kant’s views on a number of central problems in philosophy and meta-philosophy, including: the explanation of the enduring human impulse towards metaphysics, correct philosophical method, the limits of self-knowledge, the possibility of human freedom, the resolution of metaphysical paradox (‘Antinomy’), the justification of faith, the nature of scepticism, and the role of ‘as if’ reasoning in natural science.

Introduction

This chapter presents the main themes of the book, including, most importantly, a re-interpretation of Kant’s guiding metaphor for critique, namely, the ‘fiery test’ of the title. The image to which Kant is appealing is not that of an ordeal (a trial by fire) but rather a metallurgical test in which ore samples are checked for their precious metal content. The upshot is that critique is not a pass–fail affair, but has variegated results; moreover, it is in part optimistic: the test, in addition to burning. off the dross, seeks to uncover nuggets of value in traditional speculative metaphysics. Other topics examined in the chapter include: dogmatism and scepticism, method and experiment as guiding metaphors; Kant’s idiosyncratic take on Pyrrhonism; his practice of this idiosyncratic Pyrrhonism; Kantian charity; denying knowledge in order to make room for faith; the nature of speculation; the pre-eminence of the Antinomies; and Kant’s methodological influences.

Tuning the electronic structure of Ag-Pd alloys to enhance performance for alkaline oxygen reduction

Alloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Herein, we enhance the activity of Pd-based electrocatalysts via Ag-Pd alloying while simultaneously lowering precious metal content in a broad-range compositional study focusing on highly comparable Ag-Pd thin films synthesized systematically via electron-beam physical vapor co-deposition. Cyclic voltammetry in 0.1 M KOH shows enhancements across a wide range of alloys; even slight alloying with Ag (e.g. Ag0.1Pd0.9) leads to intrinsic activity enhancements up to 5-fold at 0.9 V vs. RHE compared to pure Pd. Based on density functional theory and x-ray absorption, we hypothesize that these enhancements arise mainly from ligand effects that optimize adsorbate–metal binding energies with enhanced Ag-Pd hybridization. This work shows the versatility of coupled experimental-theoretical methods in designing materials with specific and tunable properties and aids the development of highly active electrocatalysts with decreased precious-metal content.

Value Retention Options in Circular Economy: Issues and Challenges of LED Lamp Preprocessing

The Circular Economy is gaining recognition for its attention to increasing material circularity by proposing a set of value retention options, and organizing business, institutions, and policies for their implementation. Light emitting diode (LED) lamp recycling is becoming increasingly important due to their growing market share and precious metal content. Instead of the current shredding approach, this study applied higher value retention options, such as testing for the functionality of the bulb at the product level, manual disassembly to reuse parts at the component level, and automatic disassembly for industrial scale reuse. This study finds that the effort that is needed to implement higher value retention options (such as reuse) requires a new form of secondary business, wider networks of recycling chains, and favorable policies. It also shows that about 50% of the lamp waste stream is still functioning and economically attractive if they are remarketed. However, the demand-pull market conditions seem to be missing. For manual disassembly, the output fractions are cleaner, but it is not economically feasible due to high labor cost. On the other hand, automatic disassembly does not produce cleaner fractions due to wide design variability. Thus, this study suggests that shifting from shredding-focused-resource recovery to reuse-based-resource circularity requires a comprehensive framework that simultaneously encourages secondary market formation, collaboration between manufacturers, recyclers and companies, and the formulation of favorable reuse policies. This study applies insights from circular economy principles to LED lamp recycling, and it also contributes to the latter by identifying challenges and possible solutions.

‘A place of great trust to be supplied by men of skill and integrity’: assayers and knowledge cultures in late sixteenth- and seventeenth-century London

This article suggests that institutional workshops of assay were significant experimental sites in early modern London. Master assayers at Goldsmiths’ Hall on Foster Lane, in the heart of the city, and at the Royal Mint, in the Tower, made trials to determine the precious-metal content of bullion, plate and coinage. The results of their metallurgical experiments directly impacted upon the reputations and livelihoods of London's goldsmiths and merchants, and the fineness of coin and bullion. Engaged in the separation and transformation of matter, assayers and the affairs of their workshops were also a curiosity for those interested in the secrets of nature. Making use of a wide-ranging body of sources, including institutional court minutes, artisanal petitions, mercantile guidebooks, recipe books and natural-philosophical treatises, this article uncovers a complex culture of metropolitan expertise. We first examine the workshop spaces in which assayers undertook their professional activities, and their secretive corporate cultures. We turn next to the manuscript culture through which assayers codified and communicated knowledge, ‘secrets’ and techniques to broader urban audiences. Finally, we assess exchanges and tensions between assayers and the wider community of Londoners engaged in scientific knowledge production and dissemination.

Money and Flows of Coinage in the Red Sea Trade

This chapter considers the financial scale of Indo-Roman trade via the Red Sea, comparing the large sums mentioned by Pliny with the evidence of customs dues, ostraca from the Red Sea port of Berenike, and hoards of Roman coins found in India. Analysis of the finds of Roman coins in India by value rather than number over time suggests that, contrary to prevailing opinion, there was not a major diminution in the value of the trade after the reign of Tiberius. Although there was apparently some decline in the Flavian period, the face value of coin finds recovers in the second century until the reign of Antoninus Pius. Coins for export to India were specially selected for their higher precious metal content, and older issues with a higher silver content continued to be exported to India long after they had largely ceased to circulate within the Roman Mediterranean.

Amorphous NiCoPt/Ce2O3 Nanoparticles as Highly Efficient Catalyst for Hydrogen Generation from Hydrous Hydrazine

Hydrous hydrazine is a promising hydrogen carrier material because of its high content of hydrogen (8.0 wt.%) and easy recharging as a liquid. Amorphous Ni8.1Co1.0Pt0.9/Ce2O3 nanoparticles with low precious-metal content were synthesized by a facile co-reduction method at room temperature under ambient atmosphere. The increased degree of amorphization was attributed to the introduction of Ce2O3. The resultant Ni8.1Co1.0Pt0.9/Ce2O3 nanocomposite was employed as an efficient nanocatalyst towards the decomposition of hydrous hydrazine to H2, and exhibited excellent catalytic activity and 100% H2 selectivity. Turnover frequency (TOF) value catalyzed by amorphous Ni8.1Co1.0Pt0.9/Ce2O3 is 93.75 h-1, which is much higher than Ni8.1Co1.0Pt0.9 (4.39 h-1) at 298 K. The development of the improved catalytic performance and low-cost catalyst with amorphous structure is believed to strongly promote the practical application of hydrous hydrazine as a hydrogen storage material.