8,660 research outputs found
Biologia e potencial de Doru luteipes no controle de Spodoptera frugiperda.
0 trabalho foi realizado no Centro Nacional de Pesquisa de Milho c Sorgo (CNPMS), em Sete Lagoas, MG, tendo como objetivo conhecer a biologia e o potencial de Doru luteipes (Scudder, 1876) como predador de ovos e larvas do Spodoptera frugiperda (J.E. Smith, 1797), em condições de laboratório. Estudou-se também, em condições do campo, o efeito do diversos inseticidas sobre o predador. Dos estudos bioecológicos, observou-se que as posturas possuem, em média, 26,6 ovos, e o período de incubação é do 7,31 dias. A fase ninfal variou de 37,1 a 50,1 dias, conforme o tratamento, e a fase adulta, de 83,2 dias para individuos alimentados com ovos, a 143 dias para individuos alimentados com larvas. 0 inseto mostrou urn bom potencial como predador de S. frugiperda, apresentando um consumo diário na fase ninfal de 12, 10 e 8 larvas, conforme estas foram oferecidas isoladamente, com folhas do milho ou com dieta. Na fase adulta, o consumo foi na mesma sequência da anterior, de 21, 19 e 10 larvas. Com relação aos inseticidas testados, os produtos permethrin, deltamethrin e methomyl foram eficientes no controle de S. frugiperda, e praticamente não afetaram o predador. Com base nos resultados, conclue-se que D. luteipes, em condições do laboratório, apresentou-se eficiente no controle de S. frugiperda e possui grande potencial para utilizado no controle deste inseto em milho, em condições do campo
Finite-size effects in roughness distribution scaling
We study numerically finite-size corrections in scaling relations for
roughness distributions of various interface growth models. The most common
relation, which considers the average roughness . This illustrates how
finite-size corrections can be obtained from roughness distributions scaling.
However, we discard the usual interpretation that the intrinsic width is a
consequence of high surface steps by analyzing data of restricted
solid-on-solid models with various maximal height differences between
neighboring columns. We also observe that large finite-size corrections in the
roughness distributions are usually accompanied by huge corrections in height
distributions and average local slopes, as well as in estimates of scaling
exponents. The molecular-beam epitaxy model of Das Sarma and Tamborenea in 1+1
dimensions is a case example in which none of the proposed scaling relations
works properly, while the other measured quantities do not converge to the
expected asymptotic values. Thus, although roughness distributions are clearly
better than other quantities to determine the universality class of a growing
system, it is not the final solution for this task.Comment: 25 pages, including 9 figures and 1 tabl
Core-shell silk hydrogels with spatially tuned conformations as drug delivery system
Hydrogels of spatially controlled physicochemical properties are appealing platforms for tissue engineering and drug delivery. In this study, core-shell silk fibroin (SF) hydrogels of spatially controlled conformation were developed. The core-shell structure in the hydrogels was formed by means of soaking the preformed (enzymatically crosslinked) random coil SF hydrogels in methanol. When increasing the methanol treatment time from 1 to 10 minutes, the thickness of the shell layer can be tuned from about 200 to around 850 µm as measured in wet status. After lyophilization of the rehydrated core-shell hydrogels, the shell layer displayed compact morphology and the core layer presented porous structure, when observed by scanning electron microscopy. The conformation of the hydrogels was evaluated by Fourier transform infrared spectroscopy in wet status. The results revealed that the shell layer possessed dominant β-sheet conformation and the core layer maintained mainly random coil conformation. Enzymatic degradation data showed that the shell layers presented superior stability to the core layer. The mechanical analysis displayed that the compressive modulus of the core-shell hydrogels ranged from around 25 kPa to about 1.1 MPa by increasing the immersion time in methanol. When incorporated with albumin, the core-shell SF hydrogels demonstrated slower and more controllable release profiles compared with the non-treated hydrogel. These core-shell SF hydrogels of highly tuned properties are useful systems as drug delivery system and may be applied as cartilage substitute.This study was funded by the Portuguese Foundation for Science and Technology (FCT) projects Tissue2Tissue (PTDC/CTM/105703/2008) and OsteoCart (PTDC/CTM-BPC/115977/2009), as well as the European Union’s FP7 Programme under grant agreement no. REGPOT-CT2012-316331-POLARIS. Le-Ping Yan was awarded a FCT PhD scholarship (SFRH/BD/ 64717/2009). The FCT distinctions attributed to J.M. Oliveira and A.L. Oliveira under the Investigador FCT program (IF/ 00423/2012) and (IF/00411/2013) are also greatly acknowledged, respectively
Development of a bilayered scaffold based on silk fibroin and silk fibroin/nano-calcium phosphate for osteochondral regeneration
Objectives: Osteochondral defect is a common condtion in clinic. Satisfactory
outcomes are rarely achieved by traditional methods. Tissue
engineering might be a promising strategy for this hinder. The aim of
this study is to mimick the stratified structure of osteochondral tissue,
by developing a bilayered scaffold for osteochondral regeneration. The
developed bilayered scaffold is composed of a porous silk fibroin scaffold
as the cartilage-like layer and a porous silk fibroin/nano-calcium
phosphate (CaP) scaffold as the bone-like layer
Silk Fibroin/Nano-CaP Bilayered scaffolds for osteochondral tissue engineering
In this study, bilayered silk and silk/nano-CaP scaffolds were developed for
osteochondral (OC) tissue engineering. Aqueous silk solution (16 wt.%) was used for preparation of
the cartilage-like layer and, for generation of the silk/nano-CaP suspension and the bottom layer
(CaP/Silk: 16 wt.%). The scaffolds were formed by using salt-leaching/lyophilization approach. The
scanning electron microscopy revealed that the both layers presented porous structure and
integrated well. Micro-computed tomography images confirmed that the CaP phase was only
retained in the silk/nano-CaP layer. The hydration degree and mechanical properties of the
bilayered scaffold were comparable to the ones of each single layer. The apatite crystal formation
was limited to the silk/nano-CaP layer, when soaking the scaffold in a simulated body fluid
solution, which is a must for the application of the developed scaffolds in OC tissue engineerin
Ortodeoxia recorrente e foramen ovale patente.
Introdução: Foramen ovale patente (FOP)
ocorre em até 25% dos adultos saudáveis.
Pode favorecer embolização paradoxal,
enxaqueca e insuficiência respiratória (IR).
Apresenta-se caso de IR e ortodeoxia por
shunt direito-esquerdo via FOP sem
evidência prévia de aumento da pressão
intra-auricular direita. Encerramento do
FOP resolveu eficazmente IR.
Caso clínico: Homem, 52 anos. Mieloma
múltiplo IgA/k diagnosticado um ano antes.
Internado por IR hipoxémica grave com
ortodeoxia e má resposta à oxigenoterapia,
após colocação de cateter venoso central
(CVC) na subclávia direita. Referia
parestesias e alterações visuais
inespecíficas, após manipulações do CVC.
Características da IR sugeriam shunt entre
circulação pulmonar e sistémica. Sem
evidência clínica ou imagiológica de shunt
intra-pulmonar. Ecocardiograma
transtorácico com contraste: shunt direito-
-esquerdo. Ecocardiograma transesofágico:
FOP. Cateterismo cardíaco (após resolução
espontânea da IR): sem shunt. Uma semana
depois recorreu IR grave, que resolveu (bem
como queixas neurológicas) com
encerramento do FOP.
Discussão: IR por shunt intra-cardíaco sem
aumento da pressão nas cavidades direitas é
de difícil interpretação hemodinâmica.
Raros relatos (em adultos) associam esta
entidade a anomalias anatómicas, que favorecerão shunt por orientação
preferencial do fluxo sanguíneo para o FOP.
São exemplos parésia diafragmática direita
e ectasia da aorta ascendente, identificadas
no doente apresentado. O papel do CVC,
colocado imediatamente antes da IR, é
especulativo. O completo sucesso
terapêutico após encerramento do FOP
apoia o diagnóstico.
Conclusão: Avaliar correctamente IR
(pesquisar ortodeoxia e resposta à
oxigenoterapia) permite suspeitar de shunt,
que se diagnostica utilizando meios
acessíveis, seguros e rentáveis. Shunt
intra-cardíaco sem aumento da pressão à
direita deve ser considerado porque tem
tratamento eficaz. Background: Patent foramen ovale (PFO)
occurs in 25% of healthy adults. It can lead
to paradoxical embolization, migraine and
respiratory failure (RF). The authors present
a case of RF and orthodeoxia due to a rightto-
left shunt via a PFO without previous elevation
of right atrial pressure. Closure of the
PFO effectively resolved the RF.
Case report: A 52-year-old man, with IgA-k
multiple myeloma diagnosed one year
before, was admitted for severe hypoxemic
RF, with orthodeoxia and poor response to
oxygen supplementation, after placement of
a central venous catheter (CVC) in the right
subclavian vein. The patient reported paresthesia
and nonspecific visual changes after
manipulation of the CVC. The RF suggested
a shunt between the pulmonary and systemic
circulations. There was no clinical or
radiological evidence of an intrapulmonary
shunt. Contrast echocardiography showed a
right-to-left shunt and transesophageal
echocardiography revealed a PFO. Cardiac
catheterization, after spontaneous resolution
of the RF, showed no shunt. A week later,
severe RF recurred. Complete resolution of
respiratory dysfunction and neurological
symptoms was seen after PFO closure.
Discussion: RF due to an intracardiac shunt
without increased right-sided pressure is hemodynamically difficult to interpret. A
few reports (in adults) relate this entity to
anatomical anomalies, which can lead to a
shunt by directing blood flow preferentially
to the PFO. Examples include right
diaphragmatic paresis and ectasia of the
ascending aorta, which were observed in
this patient. The role of the CVC, which was
placed immediately before the RF, is uncertain.
Complete therapeutic success after closure
of the PFO supports the diagnosis.
Conclusion: Correct evaluation of RF (by
investigating orthodeoxia and response to
oxygen therapy) enables the suspicion of a
shunt, which can be confirmed through simple,
safe and cost-effective exams.
Intracardiac shunt without increased rightsided
pressure should be considered
because it can be successfully treatment
Sodium silicate gel as a precursor for the in vitro nucleation and grow of a bone-like apatite coating in compact and porous polymeric structures
In the present work, a new methodology to produce bioactive coatings on the surface of starch-based biodegradable polymers or other polymeric biomaterials is proposed. A sodium silicate gel is employed as an alternative nucleating agent to the more typical bioactive glasses for inducing the formation of a calcium-phosphate (Ca-P) layer. The method has the advantage of being able to coat efficiently both compact materials and porous 3D architectures aimed at being used on tissue replacement applications and as tissue engineering scaffolds. By means of this treatment, it is possible to observe the formation of an apatite-like layer, only after 6 hours of simulated body fluid immersion. For the porous materials, this layer could also be observed inside the pores, clearly covering the cell walls. Furthermore, an increase of the surface hydrophilicity (higher amount of polar groups in the surface) might contribute to the formation of silanol groups that also act as apatite inductors. After 30 days of SBF immersion, the apatite-like films exhibit a partially amorphous nature and the Ca/P ratios became much closer to the value attributed to hydroxyapatite (1.67). The obtained results are very promising for the development of cancellous bone replacement materials and for pre-calcifying bone tissue engineering scaffolds
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