Rapid Screening of Calcium Carbonate Precipitation in the Presence of Amino Acids: Kinetics, Structure, and Composition

Soluble additives are widely used to control crystallization, leading to a definition of properties including size, morphology, polymorph, and composition. However, because of the number of potential variables in these experiments, it is typically extremely difficult to identify reaction conditions—as defined by solution compositions, temperatures, and combinations of additives—that give the desired product. This article introduces a high-throughput methodology which addresses this challenge and enables the streamlined preparation and characterization of crystalline materials. Using calcium carbonate precipitated in the presence of selected amino acids as a model system, we use well plates as microvolume crystallizers, and an accurate liquid-handling pipetting workstation for sample preparation. Following changes in the solution turbidity using a plate reader delivers information about the reaction kinetics, while semiautomated scanning electron microscopy, powder X-ray diffraction, and Raman microscopy provide structural information about the library of crystalline products. Of particular interest for the CaCO3 system is the development of fluorescence-based protocols which rapidly evaluate the amounts of the additives occluded within the crystals. Together, these methods provide a strategy for efficiently screening a broad reaction space, where this can both accelerate the ability to generate crystalline materials with target properties and develop our understanding of additive-directed crystallization

Combinatorial microfluidic droplet engineering for biomimetic material synthesis

Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach utilizes a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials and medicine

A Divergent Synthetic Approach to Diverse Molecular Scaffolds: Assessment of Lead-Likeness using LLAMA, an Open-Access Computational Tool

Complementary cyclisation reactions of hex-2-ene-1,6-diamine derivatives were exploited in the synthesis of alternative molecular scaffolds. The value of the synthetic approach was analysed using LLAMA, an open-access computational tool for assessing the lead-likeness and novelty of molecular scaffolds

‘Caution! The Bread is Poisoned’: The Hong Kong Mass Poisoning of January 1857

This article examines the Hong Kong mass poisoning of 15 January 1857, in which bread from a Chinese bakery that supplied the colonial community was adulterated with arsenic. Even though there is a wealth of printed and manuscript documentation available many vital aspects of the poisoning remain unclear. What kind of incident was it: an act of terrorism and attempted mass murder, a war crime, a criminal conspiracy, an act of commercial sabotage, an accident or even an imagined or imaginary event? Throughout, our focus remains firmly fixed on the central act of the poisoning itself and on what it reveals about the precarious nature of early colonial Hong Kong. Interpretations have swarmed over the available ‘facts'. Equally ironic is what happened to the afterlife of how the event was understood. This article seeks to rescue the Hong Kong poisoning from being a freakish and isolated footnote of only local interest. Accepting this historical verdict would be a mistake as it is of significance not only at a local level, but geopolitically in Britain and across the empire

CCDC 644161: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures