Bioinspired materials that self-shape through programmed microstructures

Nature displays numerous examples of materials that can autonomously change their shape in response to external stimuli. Remarkably, shape changes in biological systems can be programmed within the material's microstructure to enable self-shaping capabilities even in the absence of cellular control. Here, we revisit recent attempts to replicate in synthetic materials the shape-changing behavior of selected natural materials displaying deliberately tuned fibrous architectures. Simple processing methods like drawing, spinning or casting under magnetic fields are shown to be effective in mimicking the orientation and spatial distribution of reinforcing fibers of natural materials, thus enabling unique shape-changing features in synthetic systems. The bioinspired design and creation of self-shaping microstructures represent a new pathway to program shape changes in synthetic materials. In contrast to shape-memory polymers and metallic alloys, the self-shaping capabilities in these bioinspired materials originate at the microstructural level rather than the molecular scale. This enables the creation of programmable shape changes using building blocks that would otherwise not display the intrinsic molecular/atomic phase transitions required in conventional shape-memory materials.ISSN:1744-683XISSN:1744-684

Cisto ovariano em vacas de leite: incidência, resposta à aplicação de GnRH e desempenho reprodutivo Ovarian cysts in lactating dairy cows: incidence, response to GnRH, and reproductive performance

A incidência de cistos ovarianos, a resposta ao tratamento com GnRH e os efeitos da ocorrência de cisto no desempenho reprodutivo e na taxa de descarte foram determinados em vacas lactantes da raça Holandesa. Vacas lactantes (n=333) foram avaliadas semanalmente por ultrassonografia a partir da quarta semana pós-parto, visando à detecção de corpos lúteos (CL) e de folículos ovarianos maiores que 10mm. Na sétima semana pós-parto, as vacas foram classificadas: em ciclando (n=248; presença de CL em um dos exames ultrassonográficos); em anestro (n=54; ausência de CL e de folículos >25mm) e com cisto (n=31; ausência de CL e presença de estruturas >25mm), quando foram distribuídas em: grupo-controle (n=16; sem tratamento) e grupo-tratamento (n=15; vacas que receberam uma aplicação de GnRH). A taxa de cura foi de 60,0% no grupo das vacas tratadas e de 87,5% no grupo-controle. As vacas com cistos apresentaram maior intervalo parto-primeira inseminação artificial (P<0,05; 91,4±8,3 vs. 77,8±2,5), maior número de serviços por concepção (P<0,05; 4,4±1,2 vs. 3,6±1,5), maior intervalo parto-concepção (P<0,05; 214,8±25,9 vs. 174,9±7,7) e maior taxa de descarte (P<0,05; 41,2 vs. 21,8%) do que as vacas ciclando. Vacas diagnosticadas com cisto na sétima semana pós-parto apresentaram recuperação espontânea, embora o intervalo parto-concepção e a taxa de descarte tenham sido maiores para essas vacas.<br>The incidence of ovarian cysts, response to GnRH treatment, and effects on reproductive performance and culling rate of Holstein cows were determined. Ovaries of lactating cows (n=333), were weekly monitored by ultrasound, beginning at fourth week postpartum, to determine the presence of corpus luteum (CL) and follicles greater than 10mm. In the seventh week the cows were classified as cycling (n=248; presence of corpus luteum (CL) in one of the ultrasound evaluations); anovulatory (n=54; absence of CL and follicles less than 25mm), and cystic (n=31; absence of CL and presence of structures greater than 25mm). The cysts cows were distributed in two groups in the seventh week: control group (n=16; without treatment) and treatment group (n=15; cows received one GnRH injection). The recovery rate was 60.0% in treated cows and 87.5% in control cows. The cystic cows had longer average interval from parturition to first AI (P<0.05; 91.4±8.3 vs. 77.8±2.5), higher number of services per conception (P<0.05; 4.4±1.2 vs. 3.6±1.5), longer interval parturition to conception (P<0.05; 214.8± 25.9 vs. 174.9±7.7), and higher percentage of culled cows (P<0.05; 41.2% vs. 21.8%), than cycling cows. Cystic cows without treatment had the same recovery rate as cows treated with GnRH. Cystic cows had longer intervals from parturition to conception, and higher culling rate