Relationship between the Crystal Structure and Tuberculostatic Activity of Some 2-Amidinothiosemicarbazone Derivatives of Pyridine

Tuberculosis remains one of the most common diseases affecting developing countries due to difficult living conditions, the rapidly increasing resistance of M. tuberculosis strains and the small number of effective anti-tuberculosis drugs. This study concerns the relationship between molecular structure observed in a solid-state by X-ray diffraction and the 15N NMR of a group of pyridine derivatives, from which promising activity against M. tuberculosis was reported earlier. It was found that the compounds exist in two tautomeric forms: neutral and zwitterionic. The latter form forced the molecules to adopt a stable, unique, flat frame due to conjugation and the intramolecular hydrogen bond system. As the compounds exist in a zwitterionic form in the crystal state generally showing higher activity against tuberculosis, it may indicate that this geometry of molecules is the “active” form.

Energy Absorption Capacity Of Rat-Trap Bond Masonry Under Base Excitation

Brick masonry does not exhibit much capacity to resist lateral loads and hence the masonry suffers heavy damage during earthquakes, which impart lateral loads to structures. In the Bhuj earthquake of Jan 26, 2001, that occurred in majority of masonry structures failed because they were built with un-reinforced brick masonry. The EBC code of practice for brick masonry, suggests the use of lintel band and roof band that introduce a rigid box-type behavior which will help the structure to improve its performance against seismic loads. But there are no Codal provisions for use of Rat-Trap bond masonry which has been found to possess good seismic resistance characteristics. Rat-Trap bond system consists of an array of headers and stretchers with bricks laid vertically on the edge to form a cavity within a set of two headers and two stretchers. In this investigation, an attempt has been made to study the behavior of un-reinforced Rat-Trap bond masonry of two categories viz., (i) with roof slab, and (ii) without roof slab. Shock-table tests on one-third scale masonry building models ( with and without roof slabs ) were carried out to study the behavior. The peak accelerations were recorded for each shock. The scaled bricks were obtained by cutting locally available bricks using special tools. The size of the masonry models was 2m x 1m x 1m. The amount of energy imparted during each shock was measured before total collapse both for Rat-Trap bond masonry models with and without roof slabs. The results of the tests revealed that the roof weight plays an important role in the design of Rat-Trap masonry systems subject to seismic loads.

SISTEMAS VINCULARES VITIMIZADO E CIDADÃO: UMA PROPOSTA SOCIONÔMICA

In this experience report as a therapist in a governmental program on the outskirts of the city of São Paulo, the goal was to understand, focusing on the socionomic methodology, how technicians and users of assistance service managed their day-to-day challenges in the community context. Two socio-dynamics were identified in the observed roles: the first one, named Victimized Bond System (VBS), assumes that most of the responsibility of the events belongs to third parties, involving expectation, guilt, scapegoating and consequent social exclusion; and the so-called Citizen Bond System (CBS), which attributes co-responsibility, involving dialogue and negotiation in search of viable solutions and generating social inclusion. VBS was proved less efficient in overcoming challenges and the socionomic intervention facilitated a transition from VBS to CBS.

Hydrogen bond system generated by nitroamino rearrangement: new character for designing next generation energetic materials

Hydrogen bond systems stabilize molecules and shorten intermolecular distances to give higher density and lower sensitivity.

Study of IR spectra of thiacalix[4]arene with carboxyl and adamantyl groups

The IR spectra of p-(3-carboxy-1-adamantyl)thiacalix[4]arene (1) were studied. IR spectra of compound 1 do not contain bands of free hydroxyl groups. The νOH value at 3377 cm-1 signifies the formation of an intramolecular H-bond along the lower edge of compound 1. It was found that all the studied calixarene derivatives containing adamantylcarboxylic acid fragments on the upper edge form H-bonds between adjacent carboxyl groups. At the top edge of thiacalixarene, carboxyl groups form dimers or cyclic tetramers through intramolecular H-bonds. The conformation of the cone is preserved, but there is a mutual influence of Hbonds along the lower and upper edges of the thiacalixarene molecules. A structure with dimeric H-bonds between carboxyl groups is 1.5 kJ/mol less preferable than the conformation with tetrameric cyclic H-bonds of compound 1. Comparison of the νOH absorption frequency of alcohol hydroxyl groups in IR spectra of thiacalixarenes shows that the presence of the second H-bond system weakens the H-bonds of alcohol hydroxyl groups slightly.

Macroscopic Model of an Abrasive Tool

When designing an abrasive tool, it is necessary to know the most important properties of the abrasive grain-bond system. The greatest interest is the study of the physical and mechanical characteristics of the abrasive tool: hardness, density, bending strength, modulus of elasticity, Poisson's ratio, coefficient of thermal expansion, thermal properties, etc. There are extensive experimental data on mechanical testing of abrasive tools in which a number of empirical formulas have been obtained to determine the physical and mechanical characteristics of an abrasive tool (grain size, hardness, structure, grain and bond grade, etc.). The article is based on core several assumptions and hypotheses that determine the limits of applicability of the results obtained, within which the theory has a complete and complete model of the behavior of the abrasive tool.