Effect of lateral substituent and chain length on mesomorphic properties of novel alkoxy benzyloxy benzoates of cyanophenyl rod-shaped compounds

Three novel homologous series of rod-shaped cyanophenyl alkoxy benzoate liquid crystalline compounds with lateral polar fluorine and chlorine substituent were prepared, and chemical structures of novel materials have been characterized by standard spectral technique and elemental analysis. The mesophase characterization was carried out using the combination of polarized optical microscopy and differential scanning calorimetry. All the compounds exhibit wide thermal range of enantiotropic SmA phase

In-patient operating exposure for dental undergraduates: a valuable experience?

The General Dental Council, the Association of Dental Education in Europe and the Association of British Academic Oral and Maxillofacial Surgeons have all issued syllabuses suggesting undergraduate dental students should gain experience of oral and maxillofacial in-patient operating.Aim To examine whether final year dental students in a UK dental school had observed, and were comfortable providing an explanation of, oral and maxillofacial in-patient operating.Materials and methods Students at Newcastle University's School of Dental Sciences have block allocations to in-patient operating (16 half-day sessions). A questionnaire was distributed to the whole of the final year (n = 78) at the end of these allocations examining different aspects of their exposure to in-patient operating.Results A response rate of 81% (n = 63) was achieved. Those responding reported that they had seen a wide variety of surgery. The most common procedural group that had not been observed was orthognathic surgery (n = 33, 52%). There was no correlation (p >0.05) between total number of procedural groups observed and total number of procedural groups that students were confident to explain, although there were significant correlations (

Fracture morphology of carbon fiber reinforced plastic composite laminates

Carbon fiber reinforced plastic (CFRP) composites have been extensively used in fabrication of primary structures for aerospace, automobile and other engineering applications. With continuous and widespread use of these composites in several advanced technology, the frequency of failures is likely to increase. Therefore, to establish the reasons for failures, the fracture modes should be understood thoroughly and unambiguously. In this paper, CFRP composite have been tested in tension, compression and flexural loadings; and microscopic study with the aid of Scanning Electron Microscope (SEM) has been performed on failed (fractured) composite surfaces to identify the principle features of failure. Efforts have been made in correlating the fracture surface characteristics to the failure mode. The micro-mechanics analysis of failure serves as a useful guide in selecting constituent materials and designing composites from the failure behavior point of view. Also, the local failure initiation results obtained here has been reliably extended to global failure prediction