Crystal polymorphism and crystalline-state photochromism of a rhodium dithionite complex with n-methoxypropyl moieties

A rhodium dinuclear complex having n-methoxypropyltetramethylcyclopentadienyl (CpMPro = η5-C5Me4n-C3H6OCH3) and photoresponsive dithionite (μ-O2SSO2) ligands, [(CpMProRh)2(μ-CH2)2(μ-O2SSO2] (1MPro), was found to form two polymorphic crystals (a previously reported brock-like α-crystal and a...

Whey as an Alternative Nutrient Medium for Growth of Sporosarcina pasteurii and Its Effect on CaCO3 Polymorphism and Fly Ash Bioconsolidation

Whey in large quantities can cause environmental problems when discarded, because it reduces dissolved oxygen and aquatic life. Nonetheless, it could be used as an easily available and economical alternative to reduce culture medium costs in microbially induced calcium carbonate precipitation (MICP). In this work, a native Sporosarcina pasteurii was isolated and then cultured by using different proportions of whey (W) in nutrient broth (NB). The solids were characterized by XRD, FT-IR, TGA, and SEM. The potential applications in bioconsolidation were also studied. Whey concentration was directly related to CaCO3 production. Higher whey concentrations reduced calcium carbonate purity to nearly 80%. All experiments showed calcite and vaterite fractions, where a whey increment in the media increased calcite content and decreased vaterite content, causing a decrease in crystal size. MICP improved compressive strength (CS) in sand and fly ash. The best CS results were obtained by fly ash treated with 25 W-75 NB (37.2 kPa) and sand with 75 W-25 NB (32.1 kPa). Whey changed crystal polymorphism in biogenic CaCO3 production. Material bioconsolidation depends on the CaCO3 polymorph, thus fly ash was effectively bioconsolidated by crystallization of vaterite and sand by crystallization of calcite.

Characterisation of Fat Crystal Polymorphism in Cocoa Butter by Time-Domain NMR and DSC Deconvolution

The polymorphic state of edible fats is an important quality parameter in fat research as well as in industrial applications. Nowadays, X-ray diffraction (XRD) is the most commonly used method to determine the polymorphic state. However, quantification of the different polymorphic forms present in a sample is not straightforward. Differential Scanning Calorimetry (DSC) is another method which provides information about fat crystallization processes: the different peaks in the DSC spectrum can be coupled to the melting/crystallisation of certain polymorphs. During the last decade, nuclear magnetic resonance (NMR) has been proposed as a method to determine, qualitatively and/or quantitatively, the polymorphic forms present in fat samples. In this work, DSC- and NMR-deconvolution methods were evaluated on their ability to determine the polymorphic state of cocoa butter, with XRD as a reference method. Cocoa butter was subjected to two different temperature profiles, which enforced cocoa butter crystallization in different polymorphic forms. It was found that XRD remains the best method to qualitatively determine the polymorphic state of the fat. Whereas the quantitative NMR and DSC deconvolution results were not fully in line with the XRD results in all cases, NMR deconvolution showed great promise both in a qualitative and quantitative way.

Azobenzene Crystal Polymorphism Enables Tuneable Photoinduced Deformation, Mechanical Behaviors and Photoluminescent Properties

Stimuli-responsive molecular crystals are fascinating for their potential as adaptive smart materials. However, achieving one crystal that could respond to multiple stimuli and perform multiple functionalities simultaneously is still challenging....

Ambient L-Lactic Acid Crystal Polymorphism

Only one crystalline phase of the metabolite, L-Lactic acid (LLA), has been described since its isolation from sour milk as long ago as 1780. Herein, we report the structures of...

Crystal polymorphism of 8OCB liquid crystal consisting of strongly polar rod-like molecules

The studies on crystal polymorphism of 8OCB liquid crystal showing a metastable PP phase and a heterogeneous CP phase as the stable ground state.