Solubility and Crystallization of Piroxicam from Different Solvents in Evaporative and Cooling Crystallization

In this work, the solubility of a non-steroidal anti-inflammatory drug (NSAID), piroxicam, is investigated. The polymorphic form II, which is the most stable form at room temperature, was investigated in seven different solvents with various polarities. It has been found that the solubility of piroxicam in the solvents is in the following order: chloroform > dichloromethane > acetone > ethyl acetate > acetonitrile > acetic acid > methanol > hexane. Crystallization of piroxicam from different solvents has been performed with evaporative crystallization and cooling crystallization; the effects of solvent evaporation rate and solute concentration have also been studied. Both form I and form II could be produced in cooling and evaporative crystallization, and no simple link can be identified between the operating parameters and the polymorphic outcome. Results obtained in the present work showed the stochastic nature of the nucleation of different polymorphs as well as the complexity of the crystallization of a polymorphic system.

Quantum-mechanical exploration of the phase diagram of water

The set of known stable phases of water may not be complete, and some of the phase boundaries between them are fuzzy. Starting from liquid water and a comprehensive set of 50 ice structures, we compute the phase diagram at three hybrid density-functional-theory levels of approximation, accounting for thermal and nuclear fluctuations as well as proton disorder. Such calculations are only made tractable because we combine machine-learning methods and advanced free-energy techniques. The computed phase diagram is in qualitative agreement with experiment, particularly at pressures ≲ 8000 bar, and the discrepancy in chemical potential is comparable with the subtle uncertainties introduced by proton disorder and the spread between the three hybrid functionals. None of the hypothetical ice phases considered is thermodynamically stable in our calculations, suggesting the completeness of the experimental water phase diagram in the region considered. Our work demonstrates the feasibility of predicting the phase diagram of a polymorphic system from first principles and provides a thermodynamic way of testing the limits of quantum-mechanical calculations.

Evaluating of the association between ABO blood groups and coronavirus disease 2019 (COVID-19) in Iraqi patients

Background Susceptibility to the pandemic coronavirus disease 2019 (COVID-19) has recently been associated with ABO blood groups in patients of different ethnicities. This study sought to understand the genetic association of this polymorphic system with risk of disease in Iraqi patients. Two outcomes of COVID-19, recovery and death, were also explored. ABO blood groups were determined in 300 hospitalized COVID-19 Iraqi patients (159 under therapy, 104 recovered, and 37 deceased) and 595 healthy blood donors. The detection kit for 2019 novel coronavirus (2019-nCoV) RNA (PCR-Fluorescence Probing) was used in the diagnosis of disease. Results Mean age was significantly increased in patients compared to controls (49.8 ± 11.7 vs. 28.9 ± 6.6 years; p < 0.001). A similar observation was made in recovered (42.1 ± 10.4 vs. 28.9 ± 6.6 years; p < 0.001) and deceased (53.6 ± 9.7 vs. 28.9 ± 6.6 years; p < 0.001) cases. The mean age was also significantly increased in deceased cases compared to recovered cases (53.6 ± 9.7 vs. 42.1 ± 10.4 years; p < 0.001). There were gender-dependent differences in COVID-19 prevalence. The percentage of COVID-19 was higher in males than in females (all cases: 59.7 vs. 40.3%; recovered cases: 55.8 vs. 44.2%). Such male-gender preponderance was more pronounced in deceased cases (67.6 vs. 32.4%). Logistic regression analysis revealed that groups AB and B + AB were significantly associated with increased risk to develop COVID-19 (OR = 3.10; 95% CI 1.59–6.05; pc = 0.007 and OR = 2.16; 95% CI 1.28–3.63; pc = 0.028, respectively). No ABO-associated risk was observed in recovered cases. On the contrary, groups A (OR = 14.60; 95% CI 2.85–74.88; pc = 0.007), AB (OR = 12.92; 95% CI 2.11–79.29; pc = 0.042), A + AB (OR = 14.67; 95% CI 2.98–72.33; pc = 0.007), and A + B + AB (OR = 9.67; 95% CI 2.02–46.24; pc = 0.035) were associated with increased risk of death in deceased cases. Conclusions The findings of this study suggest that group AB may be a susceptibility biomarker for COVID-19, while group A may be associated with increased risk of death.

Polymorphism of high energy materials

The intimate connection between structure and properties is particularly acute in establishing the effectiveness and safety of high energy materials based on molecular compounds: chemical and physical stability, shelf-life, sensitivity to shock, pressure, and temperature. Compared to other classes of compounds treated in the book for which the polymorphs with less suitable properties are not chosen for use, and thus relegated to lower importance, for high energy materials the risks and dangers of lack of familiarity and control of the polymorphic system can entail considerable long-term risks. The chapter is divided into two major sections distinguishing between aliphatic materials and the aromatic materials, commonly known by their alphabetic moniker. Throughout the chapter the history of the development of many of these materials is provided, including some rather obscure references culled from formerly classified government research reports. A detailed discussion of the classic enigmatic polymorphism of trinitrotoluene (TNT) is presented.

Controlling the Polymorphism and Topology Transformation in Porphyrinic Zirconium Metal-Organic Frameworks via Mechanochemistry

The mechanochemical approach has been used here for preparation and polymorph resolution in porphyrinic MOF-525/PCN-223 zirconium metal-organic frameworks system, achieving pure target MOF phases in 30-60 minutes milling. In specific reaction condition, MOF-525 forms rapidly by milling but transforms into PCN-223, confirming it to be the kinetic phase in this polymorphic system. ESR measurements showed a strong effect of internal MOF structure on the spin structure of paramagnetic cations coordinated into porphyrin linkers, which show potential for these polymorphic MOFs in spintronics application.

Controlling the Polymorphism and Topology Transformation in Porphyrinic Zirconium Metal-Organic Frameworks via Mechanochemistry

The mechanochemical approach has been used here for preparation and polymorph resolution in porphyrinic MOF-525/PCN-223 zirconium metal-organic frameworks system, achieving pure target MOF phases in 30-60 minutes milling. In specific reaction condition, MOF-525 forms rapidly by milling but transforms into PCN-223, confirming it to be the kinetic phase in this polymorphic system. ESR measurements showed a strong effect of internal MOF structure on the spin structure of paramagnetic cations coordinated into porphyrin linkers, which show potential for these polymorphic MOFs in spintronics application.

The computational content of atomic polymorphism

We show that the number-theoretic functions definable in the atomic polymorphic system (${\mathbf{F}}_{\mathbf{at}}$) are exactly the extended polynomials. Two proofs of the above result are presented: one, reducing the functions’ definability problem in ${\mathbf{F}}_{\mathbf{at}}$ to definability in the simply typed lambda calculus ($\lambda ^{\rightarrow }$) and the other, directly adapting Helmut Schwichtenberg’s strategy for definability in $\lambda ^{\rightarrow }$ to the atomic polymorphic setting. The uniformity granted in the polymorphic system, when compared with the simply typed lambda calculus, is emphasized.

A non-coding region near Follistatin controls head colour polymorphism in the Gouldian finch

Discrete colour morphs coexisting within a single population are common in nature. In a broad range of organisms, sympatric colour morphs often display major differences in other traits, including morphology, physiology or behaviour. Despite the repeated occurrence of this phenomenon, our understanding of the genetics that underlie multi-trait differences and the factors that promote the long-term maintenance of phenotypic variability within a freely interbreeding population are incomplete. Here, we investigated the genetic basis of red and black head colour in the Gouldian finch ( Erythrura gouldiae ), a classic polymorphic system in which naturally occurring colour morphs also display differences in aggressivity and reproductive success. We show that the candidate locus is a small (approx. 70 kb) non-coding region mapping to the Z chromosome near the Follistatin ( FST ) gene. Unlike recent findings in other systems where phenotypic morphs are explained by large inversions containing hundreds of genes (so-called supergenes), we did not identify any structural rearrangements between the two haplotypes using linked-read sequencing technology. Nucleotide divergence between the red and black alleles was high when compared to the remainder of the Z chromosome, consistent with their maintenance as balanced polymorphisms over several million years. Our results illustrate how pleiotropic phenotypes can arise from simple genetic variation, probably regulatory in nature.