Strong Isotope Effects on Melting Dynamics and Ice Crystallisation Processes in Cryo Vitrification Solutions

The nucleation and growth of crystalline ice during cooling, and further crystallization processes during re-warming are considered to be key processes determining the success of low temperature storage of biological objects, as used in medical, agricultural and nature conservation applications. To avoid these problems a method, termed vitrification, is being developed to inhibit ice formation by use of high concentration of cryoprotectants and ultrarapid cooling, but this is only successful across a limited number of biological objects and in small volume applications. This study explores physical processes of ice crystal formation in a model cryoprotective solution used previously in trials on vitrification of complex biological systems, to improve our understanding of the process and identify limiting biophysical factors. Here we present results of neutron scattering experiments which show that even if ice crystal formation has been suppressed during quench cooling, the water molecules, mobilised during warming, can crystallise as detectable ice. The crystallisation happens right after melting of the glass phase formed during quench cooling, whilst the sample is still transiting deep cryogenic temperatures. We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture. In the neutron scattering experiment with a fully protiated water component, we observe ready crystallisation occurring just after the glass melting transition. On the contrary with a fully deuteriated water component, the process of crystallisation is either completely or substantially supressed. This behaviour might be explained by nuclear quantum effects in water. The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies

Coronavirus Occurrence and Transmission Over 8 Years in the HIVE Cohort of Households in Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156082/1/jiaa161.pdfSEL

Supramolecular binding and separation of hydrocarbons within a functionalised porous metal-organic framework

Supramolecular interactions are fundamental to host-guest binding in chemical and biological processes. Direct visualisation of such supramolecular interactions within host-guest systems is extremely challenging but crucial for the understanding of their function. We report a comprehensive study combining neutron scattering with synchrotron X-ray and neutron diffraction, coupled with computational modelling, to define the detailed binding at a molecular level of acetylene, ethylene and ethane within the porous host NOTT-300. This study reveals the simultaneous and cooperative hydrogen-bonding, π···π stacking interactions and inter-molecular dipole interactions in the binding of acetylene and ethylene to give up to twelve individual weak supramolecular interactions aligned within the host to form an optimal geometry for intelligent, selective binding of hydrocarbons. We also report, for the first time, the cooperative binding of a mixture of acetylene and ethylene within the porous host together with the corresponding breakthrough experiment and analysis of mixed gas adsorption isotherms

Oxidation of Reduced Sulfur Species: Carbon Disulfide

Article on the oxidation of reduced sulfur species and carbon disulfide

Three individuals, three stories, three burials from medieval Trondheim, Norway

This article presents the life stories of three individuals who lived in Trondheim, Norway, dur- ing the 13th century. Based on skeletal examinations, facial reconstructions, genetic analy- ses, and stable oxygen isotope analyses, the birthplace, mobility, ancestry, pathology, and physical appearance of these people are presented. The stories are discussed within the relevant historical context. These three people would have been ordinary citizens, without any privileges out of the ordinary, which makes them quite rare in the academic literature. Through the study of individuals one gets a unique look into the Norwegian medieval society

Spectroscopic measurement of the rate of the gas-phase combination of methyl radicals with nitric oxide and oxygen at 295.deg.K

The rates of combination of Me. with NO and O2 were measured by flash spectroscopy at 295 DegK. The highpressure rate coeff. for Me. + NO(+M) -> MeNO(+M) was recorded as 1.0(+-0.15) * 1013 cm3 mole-1 sec-1. The low-pressure fall-off was interpreted with the Rice-Marcus model for D0(Me-NO) = 46.8kcal mole-1. The high-pressure rate coeff. for Me + O2(+M) -> MeO2(+M) was deduced to be .apprx.1.1 * 1012 cm3 mole-1 sec-1

Spectroscopic measurement of the rate of the gas-phase combination of methyl radicals with nitric oxide and oxygen at 295.deg.K

The rates of combination of Me. with NO and O2 were measured by flash spectroscopy at 295 DegK. The highpressure rate coeff. for Me. + NO(+M) -> MeNO(+M) was recorded as 1.0(+-0.15) * 1013 cm3 mole-1 sec-1. The low-pressure fall-off was interpreted with the Rice-Marcus model for D0(Me-NO) = 46.8kcal mole-1. The high-pressure rate coeff. for Me + O2(+M) -> MeO2(+M) was deduced to be .apprx.1.1 * 1012 cm3 mole-1 sec-1