Caracterización morfológica de la semilla de Hibiscus cannabinus (Malvaceae) e influencia del tiempo de almacenamiento sobre la viabilidad

Hibiscus cannabinus L. (Malvaceae) “kenaf ” es una especie de ciclo anual primavero-otoñal, que se cultiva para la producción de fibra para papel, bioetanol de segunda generación y forraje. Los objetivos de esta investigación fueron caracterizar la morfología de la semilla de H. cannabinus y establecer la influencia del tiempo de almacenamiento sobre la viabilidad de dos cultivares, Endora y Tainung 1. Se realizaron observaciones de cortes histológicos y mediciones con microscopio óptico y estereoscópico. Se evaluó la germinación a los 30, 180 y 730 días después de cosecha. Las semillas de H. cannabinus presentan una forma asimétrica, cuneiforme y/o triangular (ca. 5,1 mm x 2,8 mm), son endospermadas y derivan de óvulos campilótropos. La cubierta seminal tiene tricomas unicelulares, eglandulares distribuidos en toda la superficie con predominio en la región del hilo. El embrión es plegado, con cotiledones conduplicados de posición axial sub tipo curvo. El episperma presenta un marcado predominio de la capa de macroesclereidas. Se encontró que las semillas de los cultivares Endora y Tainung 1, almacenadas por dos años a temperatura ambiente y con 9,5% de humedad, mantienen un alto porcentaje de germinación con valores cercanos al 80%. Los resultados permiten afirmar que las semillas de “kenaf ” mantienen las características morfológicas internas constantes típicas de las Malváceas, y que los cultivares estudiados presentan una alta viabilidad sostenida en el tiempo

Evaluación de dos fechas de siembra de Hibiscus cannabinus L. 'kenaf' (Malvaceae) en Villa del Totoral, Córdoba, Argentina

31-42El objetivo de este trabajo fue evaluar el rendimiento de fibra del cultivo de 'kenaf'en dos fechas de siembra en Villa del Totoral, Córdoba, Argentina. Se analizaron: altura de planta durante el ciclo del cultivo; diámetro basal y medio del tallo y altura a cosecha; rendimiento de fibra y contenido e índice de corteza. Se observó interacción altamente significativa entre año y fecha de siembra. En el primer año, las plantas de la siembra temprana presentaron mayores valores de altura, diámetro basal y medio y rendimiento, que las de la siembra tardía. Por el contrario en el segundo año, sólo se encontraron diferencias significativas entre fechas de siembra para ambos diámetros. El rendimiento correlacionó con altura, diámetros e índice de corteza y no con el contenido de corteza. Se sostiene que para obtener alto rendimiento de fibra de 'kenaf' en las condiciones ambientales del ensayo, es conveniente la siembra al inicio de la temporada de lluvias sin embargo, dependiendo de las condiciones ambientales, se puede esperar hasta fines de noviembre sin detrimento en los rendimientos

The power of monitoring: optimizing survey designs to detect occupancy changes in a rare amphibian population

Biodiversity conservation requires reliable species assessments and rigorously designed surveys. However, determining the survey effort required to reliably detect population change can be challenging for rare, cryptic and elusive species. We used a tropical bromeliad-dwelling frog as a model system to explore a cost-effective sampling design that optimizes the chances of detecting a population decline. Relatively few sampling visits were needed to estimate occupancy and detectability with good precision, and to detect a 30% change in occupancy with 80% power. Detectability was influenced by observer expertise, which therefore also had an effect on the sampling design – less experienced observers require more sampling visits to detect the species. Even when the sampling design provides precise parameter estimates, only moderate to large changes in occupancy will be detected with reliable power. Detecting a population change of 15% or less requires a large number of sites to be surveyed, which might be unachievable for range-restricted species occurring at relatively few sites. Unless there is high initial occupancy, rare and cryptic species will be particularly challenging when it comes to detecting small population changes. This may be a particular issue for long-term monitoring of amphibians which often display low detectability and wide natural fluctuations

Sequence and classification of FdPV2, a papillomavirus isolated from feline Bowenoid in situ carcinomas

Bowenoid in situ squamous cell carcinoma (BISC) is a rare feline skin disorder, which has been described as often associated with papillomavirus infection. It is clinically characterized by solitary or multiple hyperkeratotic plaques affecting older cats. Papillomavirus (PV) sequences amplified from feline viral plaques, and BISC lesions seldom correspond to FdPV1. The goal of the present study was to investigate three cases of BISC and to carry out initial genomic analysis of the associated viral DNA. Samples of skin biopsies taken from three BISC cats were histologically characterized. DNA was extracted and rolling-circle amplification was performed on the skin samples. Restriction enzyme analysis of the amplified DNA revealed the presence of a putative unknown PV. The whole genome was subsequently sequenced and cloned. Alignments with previously described feline PV sequences were carried out and phylogenetic trees were generated. The circular 7899 base pair sequence of Felis domesticus PV type 2 (FdPV2) contains a typical noncoding region and characteristic open reading frames (ORF) for six putative viral proteins. Phylogenetic analysis based on the nucleotide alignment of L1 genes or the amino acid alignment of E1 proteins of FdPV2 and 52 other PV types indicates that FdPV2 might represent a new genus

Sagittal osteotomy of the patella after Morscher

The aim of this study was to present long-term results of sagittal osteotomy of the patella after Morscher. The study included 70 patients treated for patellar dysplasia with a postoperative follow-up from nine to 20 years. There were 59 females and 11 males with an average age of 21 years at the time of operation. Results were evaluated for the entire group of 70 patients and then presented separately for the 30 patients in whom sagittal osteotomy of the patella was performed as a single procedure and 40 patients in whom, in addition to sagittal osteotomy of the patella, medialisation and ventralisation or distalisation of the tibial tuberosity were also performed. The mean value of the Wiberg patellar angle was 112 degrees preoperatively and 140 degrees postoperatively. In the whole group of patients excellent results were obtained in 24 (35%), good results in 30 (42%), fair results in 13 (19%) and poor results in three (4%) patients. In 30 patients with sagittal osteotomy as a single operation excellent results were obtained in 13 (43%), good results in 14 (47%) and fair results in three (10%) patients, while in the 40 patients with sagittal osteotomy and additional surgical procedures, 11 (27%) were excellent, 16 (40%) good, ten (25%) fair and three (8%) had poor results. Sagittal osteotomy of the patella after Morscher is an enrichment of the spectrum of the secondary-causal and preventive procedures for the treatment of patello-femoral disorders

ITO-based electrode: A promising candidate for the growth of piezoelectric thin films

In many ways, interfaces and surfaces dominate the behavior of thin films and multilayered devices. The critical nature that the interfaces play on numerous physical properties has stimulated significant effort to both understand such behavior and develop novel and potentially useful nanoscale systems. In particular, the use of suitable buffer layers has been shown to allow the control of nucleation and growth processes and, thus, the fabrication of a very wide range of nanostructured materials. This paper briefly overviews the relevant experimental work performed at the LPMC and related to piezoelectric thin films. Particular emphasis is given to In$_{2}$O$_{3}$:Sn oxide as an interesting conductive electrode / buffer layer for the growth of various piezoelectric compounds including LiNbO$_{3}$ (LN), Pb(Zr$_{0,52}$Ti$_{0,48})$O$_{3}$ (PZT), ZnO

LiNbO3_{\bf 3}-based ferroelectric heterostructures

We report the growth of LiNbO$_{3}$ thin films onto In$_{2}$O$_{3}$:Sn-coated $\langle$111$\rangle$-Si substrates by standard radio-frequency sputtering. Multi-layer procedures, up to 4 successive deposits, have been developed that can subsequently improve the structural and macroscopic ferroelectric properties of such as-grown composite structures. The enhancement of polarization, as high as 40 $\mu$C.cm$^{\hbox{-}2}$ in 4 stacked layers, is attributed to $c$-oriented seed-layer-induced crystallization (self-polarization) and interfacial (migratory) polarizatio

An alternative approach for the oriented growth of ZnO nanostructures

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