Effects of Monomer Structure on Their Organization and Polymerization in a Smectic Liquid Crystal     

CA Guymon  EN Hoggan  NA Clark  TP Rieker  DM Walba  CN Bowman 《Science (New York, N.Y.)》1997,275(5296):57-59

Photopolymerizable diacrylate monomers dissolved in fluid-layer smectic A and smectic C liquid crystal (LC) hosts exhibited significant spatial segregation and orientation that depend strongly on monomer structure. Small, flexible monomers such as 1,6-hexanediol diacrylate (HDDA) oriented parallel to the smectic layers and intercalated, whereas rod-shaped mesogen-like monomers such as 1,4-di-(4-(6-acryloyloxyhexyloxy)benzoyloxy)-2-methylbenzene (C6M) oriented normal to the smectic layers and collected within them. Such spatial segregation caused by the smectic layering dramatically enhanced photopolymerization rates; for HDDA, termination rates were reduced, whereas for C6M, both the termination and propagation rates were increased. These polymerization precursor structures suggest novel materials-design paradigms for gel LCs and nanophase-separated polymer systems.  相似文献   

Role of Gene Interactions in Hybrid Speciation: Evidence from Ancient and Experimental Hybrids   总被引：6，自引：0，他引：6  

LH Rieseberg  B Sinervo  CR Linder  MC Ungerer  DM Arias 《Science (New York, N.Y.)》1996,272(5262):741-745

The origin of a new diploid species by means of hybridization requires the successful merger of differentiated parental species' genomes. To study this process, the genomic composition of three experimentally synthesized hybrid lineages was compared with that of an ancient hybrid species. The genomic composition of the synthesized and ancient hybrids was concordant (rs = 0.68, P < 0.0001), indicating that selection to a large extent governs hybrid species formation. Further, nonrandom rates of introgression and significant associations among unlinked markers in each of the three synthesized hybrid lineages imply that interactions between coadapted parental species' genes constrain the genomic composition of hybrid species.  相似文献   

Heritability of agronomic traits correlated with reduced stink bug damage in an F2:3 soybean population derived from IAC-100     

Michelle Da Fonseca Santos  Milene Möller  Steven J. Clough 《Journal of Crop Improvement》2018,32(1):1-18

In Brazil, some of the most important insect pests causing damage to soybean (Glycine max) are stink bugs. Soybean production would increase if varieties with enhanced resistance were developed. The aim of this work was to examine different traits associated with plant development, and yield-related traits, in an F_2:3 soybean population in a stink bug-infested field and to evaluate genetic parameters and correlations among those traits. The parents and progeny from 229 F₂ plants developed by crossing a resistant cultivar (IAC-100) with a susceptible cultivar (CD-215) were evaluated in three replications in a single environment. Seven agronomic traits and eight indicators of insect resistance were measured. Genotypes showed significant differences for all traits except lodging. The grain-filling period exhibited a positive genotypic correlation of 0.66 with hundred-seed weight, whereas a negative genotypic correlation of ?0.53 was found between pod damage index (%) and weight of healthy seeds. In general, a shorter pod-filling period, lower weight of hundred-seeds, lower indices of pod damage, and higher seed-yield per plant were phenotypic traits of genotypes resistant to these insects.  相似文献   

Evaluation of the global DNA methylation in canine mast cell tumour samples by immunostaining of 5‐methyl cytosine          下载免费PDF全文

C. Y. Morimoto  M. V. Tedardi  I. I. M. da Fonseca  K. C. Kimura  D. S. Sanches  T. F. Epiphanio  R. de Francisco Strefezzi  M. L. Z. Dagli 《Veterinary and comparative oncology》2017,15(3):1014-1018

Cutaneous mast cell tumours (MCT) are the most common skin tumour in dogs, and to our knowledge, there are no previous studies regarding the global methylation of these tumours. DNA hypomethylation and hypermethylation have been described in several tumours and both mechanisms can lead to carcinogenesis. The purpose of this study was to evaluate the global DNA methylation in canine MCT. A total of 48 MCT samples were classified in grades 1, 2 and 3 or high‐grade or low‐grade. Monoclonal antibodies were used for the immunohistochemical detection of the 5‐methylcytosine. The immunostained nuclei were classified in strong, weak or negative pattern, and these were quantified in five distinct microscopic fields (40× objective) in each slide. The results showed that global DNA hypomethylation was predominant in grade 3, high‐grade, less differentiated MCT. These epigenetic changes in neoplastic mast cells warrant further detailed investigation aiming the establishment of tumour epigenetic therapies.  相似文献   

Arterial pulse wave propagation velocity in healthy dogs by pulse wave Doppler ultrasound     

Rodrigo B. Nogueira  Lucas A. Pereira  Alice F. Basso  Ingrid S. da Fonseca  Lorena A. Alves 《Veterinary research communications》2017,41(1):33-40

The aim of this study was to prospectively evaluate the carotid-femoral pulse wave velocity (PWV) values in healthy dogs using pulse wave Doppler ultrasound. A secondary aim was to determine the feasibility of this method and to report the intra- and interobserver reproducibilities of the PWV in conscious dogs. The data were studied in 30 healthy, adult, male (n?=?15) and female (n?=?15) dogs. The time interval marked between the R wave peak of the electrocardiogram and the intersection of the blood flow wave upstroke of the Doppler spectrum with the baseline of zero frequency was determined for the carotid (T₁) and for the femoral (T₂) arteries. The distance covered by the pulse wave (L) was determined. The PWV was then calculated using the following formula: L/T₂ - T₁. The mean values of PWV calculated from the total sample (n?=?30) evaluated were 13.41?±?2.20 m/s. No significant statistical difference was observed for the PWV measurements between males (14.82?±?3.18 m/s) and females (12.64?±?2.45 m/s). The analysis revealed no intra nor interobserver differences. A reasonable reproducibility of the PWV measurements was showed by intraclass correlation coefficients (ICC), and the coefficients of variation (CV). These data demonstrate that noninvasive vascular Doppler analysis is a feasible and reproducible method to determine the carotid-femoral PWV in dogs.  相似文献   

Control of <Emphasis Type="Italic">Haemonchus contortus</Emphasis> in sheep using basidiocarps of <Emphasis Type="Italic">Agaricus blazei</Emphasis> Murril     

Thallyta Maria Vieira  Leydiana Duarte Fonseca  Gabriela Almeida Bastos  Viviane de Oliveira Vasconcelos  Maria Luíza França Silva  Franciellen Morais-Costa  Adriano Vinícius de Paiva Ferreira  Neide Judith Faria de Oliveira  Eduardo Robson Duarte 《Veterinary research communications》2017,41(2):99-106

  相似文献