Anisotropic lattice softening near the structural phase transition in the thermosalient crystal 1,2,4,5-tetrabromobenzene

Mechanism of crystal jumping on heating was revealed by X-ray diffraction and computational techniques.</p

Electroencephalographic Intercentral Interaction as a Reflection of Normal and Pathological Human Brain Activity

The authors summarized EEG findings and defined the nature of the intercentral EEG relationships in different functional states in healthy subjects and patients with organic cerebral pathology, based on a coherence analysis. Similar EEG characteristics in healthy individuals were identified: an anterior-posterior gradient of average coherence levels, the type of cortical-subcortical relationships in anterior cerebral structures. Right- and left-handed individuals showed frequent and regional differences in EEG coherence, which mainly reflected specificity of intracortical relationships. Development and regression of pathology in right-and left-handed individuals with organic brain lesions were thought to be caused by these differences. Lesions of regulatory structures (diencephalic, brain stem and limbic structures) provoked a more diffused kind of changes of intercentral relationships, in contrast to cortical pathology. These changes tended to reciprocate. The dynamic nature of intercentral relationships and their interhemispheric differences was revealed when changing functional states of the brain (increase and decrease of functional level) in healthy individuals and patients with organic cerebral pathology in the process of conscious and psychic activity restoration. Changing activity predominance of certain regulatory structures was considered one of the most important factors determining the dynamic nature of EEG coherenceLos autores resumen los resultados de las investigaciones de las relaciones intercentrales de EEG de personas sanas en distintos estados funcionales y de enfermos con lesiones orgánicas del SNC, mediante análisis de coherencia. Se revelan características semejantes de la estructura de relaciones de EEG de personas sanas: la gradiente anterior-posterior de niveles medios de coherencia, el carácter de la interacción cortical-subcortical de las secciones anteriores de los hemisferios. A su vez, se detectan diferencias de frecuencia y regionales en la coherencia de EEG en diestros y zurdos, que reflejan mayoritariamente la especificidad de la interacción intracortical. Se cree que estas diferencias causan la especificidad del desarrollo y la regresión de los estados patológicos de diestros y zurdos en lesiones cerebrales orgánicas. Se señala que en las lesiones de formaciones reguladoras (diencefálicas, troncales, límbicas) Provocan unos cambios de las relaciones intercentrales más difusos que en casos de patología cortical. Estos cambios tienden a la reciprocidad. Se revela el carácter dinámico de las relaciones intercentrales y sus diferencias interhemisféricas en los cambios de los estados funcionales del cerebro (incremento, disminución del nivel de funcionamiento) en personas sanas así como en la recuperación de la conciencia y la actividad psíquica en enfermos con patología cerebral orgánica. Uno de los factores que determina el carácter dinámico del cambio de la coherencia del EEG es el cambio del predominio de la actividad de ciertas estructuras reguladoras

Ball-free mechanochemistry: in situ real-time monitoring of pharmaceutical co-crystal formation by resonant acoustic mixing

Co-crystal formation by resonant acoustic mixing was followed for the first time by in situ real-time X-ray powder diffraction.</p

Tribenzoatobismuth(III): a new ­polymorph

A new polymorph (β) was obtained for an active pharmaceutical ingredient, bis­muth tribenzoate, [Bi(C6H5CO2)3]. The new β-polymorph is 1.05 times denser than the previously known polymorph [Rae et al. (1998 ▶). Acta Cryst. B54, 438–442]. In the β-polymorph, the Bi atom is linked with three benzoate anions, each of them acting as a bidentate ligand, and these assemblies with C 3 point symmetry can be considered as ‘mol­ecules’. The structure of the β-polymorph has no polymeric chains, in contrast to the previously known polymorph. The ‘mol­ecules’ in the β-polymorph are stacked along [001], so that the phenyl rings of the neighbouring mol­ecules are parallel to each other. Based on the pronounced difference in the crystal structures, one can suppose that two polymorphs should differ in the dissolution kinetics and bioavailability

Polymorphism of chlorpropamide on liquid-assisted mechanical treatment:Choice of liquid and type of mechanical treatment matter

Different types of mechanical treatment (tableting, grinding, milling,etc.) are important technological operations in the pharmaceutical industry.</p

Identical Functional Organization of Nonpolytene and Polytene Chromosomes in Drosophila melanogaster

Salivary gland polytene chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of polytene chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in chromosomes of regular diploid mitotically dividing nonpolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genome-wide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the polytene and interphase cell line chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of chromosomes

Crystallographic Education in the 21st Century

There are many methods that can be used to incorporate concepts of crystallography into the learning experiences of students, whether they are in elementary school, at university or part of the public at large. It is not always critical that those who teach crystallography have immediate access to diffraction equipment to be able to introduce the concepts of symmetry, packing or molecular structure in an age- and audience-appropriate manner. Crystallography can be used as a tool for teaching general chemistry concepts as well as general research techniques without ever having a student determine a crystal structure. Thus, methods for younger students to perform crystal growth experiments of simple inorganic salts, organic compounds and even metals are presented. For settings where crystallographic instrumentation is accessible (proximally or remotely), students can be involved in all steps of the process, from crystal growth, to data collection, through structure solution and refinement, to final publication. Several approaches based on the presentations in the MS92 Microsymposium at the IUCr 23rd Congress and General Assembly are reported. The topics cover methods for introducing crystallography to undergraduate students as part of a core chemistry curriculum; a successful short-course workshop intended to bootstrap researchers who rely on crystallography for their work; and efforts to bring crystallography to secondary school children and non-science majors. In addition to these workshops, demonstrations and long-format courses, open-format crystallographic databases and three-dimensional printed models as tools that can be used to excite target audiences and inspire them to pursue a deeper understanding of crystallography are described