Color Differences Highlight Concomitant Polymorphism of Chalcones

The meta- and para-nitro isomers of (E)-3′-dimethylamino-nitrochalcone (Gm8m and Gm8p) are shown to exhibit concomitant color polymorphism, with Gm8m appearing as yellow (P2_{1}/c) or orange (P1̅) crystals and Gm8p appearing as red (P2_{1}/n) or black (P2_{1}/c) crystals. Each of the polymorphs was characterized optically via UV–vis spectroscopy, and their thermal behavior was characterized via differential scanning calorimetry and low-temperature powder X-ray diffraction. To assess the effect of molecular configuration and crystal packing on the colors of crystals of the different polymorphs, time dependent density functional theory (ωB97x) calculations were carried out on isolated molecules, dimers, stacks, and small clusters cut from the crystal structures of the four polymorphs. The calculated color comes from several excitations and is affected by conformation and most intermolecular contacts within the crystal, with the color differences between polymorphs mainly being due to the differences in the π–π stacking. The visual differences between these related polymorphic systems make them particularly useful for studying polymorph behavior such as phase transitions and concomitant polymorph growth

Food Allergy and Quality of Life:What Have We Learned?

<p>Health-related quality of life (HRQL) has become an emerging focus of interest in food allergy. Food allergy is a disease characterized by low mortality and symptoms which only occur during an allergic reaction. However, food-allergic patients continuously need to be alert when eating in order to prevent potentially severe allergic reactions, which may be fatal. Fear of such reactions and the need to be continuously vigilant may seriously compromise their HRQL. During the last decade, numerous studies have been published on food allergy and HRQL. The development of reliable, valid and responsive instruments for measuring HRQL in food allergic patients has facilitated this research even further. Such instruments have given insight into the specific problems a patient may face and the impact of food allergy-related interventions from the patient's perspective. This paper focuses on the most significant findings regarding this topic since its first appearance in the literature in 2000.</p>

Review of Measurement Techniques in Site Productivity Studies

This book is a synthesis of knowledge on the impacts of harvesting on long-term site productivity, stemming from information gathered from the International Energy Agency Bioenergy Agreement Project on Environmental Impacts of Intensive Harvesting. Annual workshops during the project have produced much new and important information and the work of over 150 collaborators on the project has been carefully synthesised into this book