Investigation of dangerous dusts

Summary Filters are described suitable for the collection of dust samples for microchemical analysis. These are of two types: A, volatile solid filters, when the filter medium is removable by sublimation. B, porous solid filters, with which the filter medium is removable by solution in a non-aqueous solution and separation of the dust by centrifuging.Two materials are used for the filter typeA: naphthalene and anthracene.Naphthalene being readily volatile can only be used for the passage of relatively small volumes of air (of the order of 100 litres for filters of 40 mm diameter), and therefore for collection of samples from very dusty atmospheres. The small size naphthalene filters are suited for collection of samples for petrographic analysis from all types of atmospheres.Anthracene is very resistant to flow and is only suitable for small filters (15 mm.) and small rates of flow, 0·2 cft./min. and therefore for slow collection of dust over long periods of time, or small samples from dusty atmospheres.Crystalline solid filters using salicylic acid crystals are adapted for very rapid rates of filtering and for large filters. Filters 7 cm in diameter will allow a flow of air of 200 cft./minute.All types of filters act as efficient filters within their special range of use.The authors wish to thank MissP. M. Sanderson and Mr.P. L. Holt who have collaborated in the latter portion of this work. They are indebted to the Institute of Chemistry for the Pedlar award (toJ. W. M.) which has rendered this work possible.

---

Zusammenfassung Es werden zwei Typen von Filtern beschrieben, die sich zum Sammeln von Staubproben für die Mikroanalyse eignen.A. Flüchtige feste Filter (die Filtermasse wird durch Sublimation entfernt);B. Poröse feste Filter (die Filtermasse wird durch Lösen in nicht wäßrigen Lösungsmitteln entfernt und vom Staub durch Zentrifugieren getrennt).Für Filter vom Typ A werden zwei Materialien verwendet: Naphthalin und Anthracen.Da Naphthalin leicht flüchtig ist, kann man nur verhältnismäßig geringe Luftmengen hindurchstreichen lassen (in der Größenordnung von 100 1 für Filter von 40 mm Durchmesser), weshalb sich dieses Filtermaterial nur zur Probensammlung aus sehr staubigen Atmosphären eignet. Naphthalinfilter von kleinen Abmessungen eignen sich zur Sammlung von Proben für petrographische Analyse aus allen Atmosphärenarten.Anthracen setzt dem Durchgang einen großen Widerstand entgegen und ist nur für kleine Filter (15 mm) und kleine Strömungsgeschwindigkeiten (0,2 Kubikfuß pro Minute) geeignet, demnach zur langsamen Staubsammlung während langer Zeiträume oder zur Gewinnung kleiner Proben aus staubigen Atmosphären.Für sehr hohe Filtergeschwindigkeiten und große Filter sind kristallinische feste Filter zu verwenden, deren Schicht aus Salizylsäurekristallen besteht. Filter von 7 cm Durchmesser lassen einen Luftstrom von 200 Kubikfuß Luft pro Minute durch.Jede der erwähnten Filtertypen erfüllt ihren Zweck in ihrem besonderen Anwendungsbereich in wirksamer Weise.

---

Résumé Deux types de filtres par moyen desquels on peut recueillir des échantillons de poussière pour l'analyse microchimique, sont décrits:A. Filtres solides volatiles (la masse filtrante peut être éloignée par sublimation).B. Filtres solides poreux (la masse filtrante peut être éloignée en la dissolvant dans un liquide non-aqueux et en la séparant de la poussière, à l'aide d'une centrifuge).Deux espèces de matériaux sont employées pour le filtre type A: Le naphthalène et l'anthracène. Vu que le naphthalène est très volatile, on ne peut l'employer que pour le passage de volumes d'air relativement petits (de 100 1 environ, pour filtres à 40 mm de diamètre) et, par conséquent, pour recueillir des échantillons dans les atmosphères très poussièreuses. Les petits modèles des filtres à naphthalène sont aptes à recueillir, dans les tous les types d'atmosphères, des échantillons pour analyse pétrographique.Comme l'anthracène est très refractaire au passage gazeux, il ne peut être utilisé que pour petits filtres (15 mm) et petites vitesses du courant gazeux (0,2 pieds cub./min.); par conséquent, on s'en sert pour recueillir la poussière lentement, pendant un long parcours de temps — ou bien, à recueillir de petits échantillons, dans les atmosphères poussièreuses.On emploie convenablement, pour des vitesses de filtration très élevées et pour de grands filtres, une souche filtrante solide qui est composée de cristaux d'acide salicylique. Les filtres à 7 cm de diamètre font passer un courant de 200 pieds cub. d'air par min.Chacun de ces types de filtres, dans les limites de son usage, permet une filtration efficace.

---

---

Some of the matter described here has been presented before two meetings of the Institution of Mining and Metallurgy in London in 1934 and 1936; and before a meeting of the Microchemical Club in 1936.     

Measuring the coordination number and entropy of a 3D jammed emulsion packing by confocal microscopy

Jammed matter is by definition impenetrable to light, such that little is known about the geometry of jammed systems. Using confocal microscopy to image an emulsion in 3D, we first explain the origin of the enhanced fluorescence at the droplet contacts and then determine the contact network inside the model frictionless system. This enables the experimental determination of the average coordination number which agrees with the isostatic predicted value of approximately 6. Furthermore, we calculate the entropy of the packing from the network of contacts.     

Biomass‐Derived Carbon Quantum Dot Sensitizers for Solid‐State Nanostructured Solar Cells

New hybrid materials consisting of ZnO nanorods sensitized with three different biomass‐derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid‐state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer‐by‐layer coating of two different types of CQDs.     

Atomgewichte

Analytical and Bioanalytical Chemistry -     

Analysis of drug–protein binding by ultrafast affinity chromatography using immobilized human serum albumin

Human serum albumin (HSA) was explored for use as a stationary phase and ligand in affinity microcolumns for the ultrafast extraction of free drug fractions and the use of this information for the analysis of drug–protein binding. Warfarin, imipramine, and ibuprofen were used as model analytes in this study. It was found that greater than 95% extraction of all these drugs could be achieved in as little as 250 ms on HSA microcolumns. The retained drug fraction was then eluted from the same column under isocratic conditions, giving elution in less than 40 s when working at 4.5 mL/min. The chromatographic behavior of this system gave a good fit with that predicted by computer simulations based on a reversible, saturable model for the binding of an injected drug with immobilized HSA. The free fractions measured by this method were found to be comparable to those determined by ultrafiltration, and equilibrium constants estimated by this approach gave good agreement with literature values. Advantages of this method include its speed and the relatively low cost of microcolumns that contain HSA. The ability of HSA to bind many types of drugs also creates the possibility of using the same affinity microcolumn to study and measure the free fractions for a variety of pharmaceutical agents. These properties make this technique appealing for use in drug-binding studies and in the high-throughput screening of new drug candidates.