3 research outputs found
Fatigue reliability assessment of ageing railway truss bridges: Rationality of probabilistic stress-life approach
No full textAbstractRail authorities all over the world are paying attention to extend the service lives of railway bridges. The famous Miner’s rule employed deterministic or probabilistic fatigue assessment approaches are generally used to predict remaining fatigue life of ageing railway bridges. Under many variable amplitude loading conditions, life predictions have been found to be unreliable since Miner’s rule does not properly take account the loading sequence effect. Therefore, this paper presents a comparison of a new probabilistic fatigue assessment approach with deterministic approach consisting of a new damage indicator, which captures the loading sequence effect of variable amplitude loads more precisely than the Miner’s rule. The comparison is performed by applying both fatigue assessment approaches to predict the remaining fatigue life of an ageing railway bridge. This comparison intends to conclude the possibility of capturing uncertainty behind loading sequence effect by proposed probabilistic fatigue assessment approach. Initially the paper presents the both approaches. Then the proposed approaches are applied to predict the fatigue lives of an ageing railway bridge. Finally predicted fatigue lives are compared and rationality, significance and validity of the proposed approaches are discussed
Phytochemical study on black pepper berries (Piper nigrum L.)
No full textBlack pepper is one of the well-known spices rich in aromatic and medicinal components, along with substantial levels of several other functional components that have health-promoting properties. The use of black pepper has been recorded in various fields such as traditional medicine, food processing, and the pharmaceutical industry. It is also recognised as an important source of natural antioxidants that have anticarcinogenic properties. In this study, a chemical investigation using black pepper berries (Piper nigrum) was conducted. The purpose of doing that is to determine the chemical component of this species. The sequential maceration extraction methods utilising solvents with different polarities, namely hexane, dichloromethane, and methanol, yielded the corresponding crude extracts. The quantitative phytochemical analysis was performed on the crude extracts. Separation and isolation work was focused on the dichloromethane crude extract using Thin Layer Chromatography (TLC), Column Chromatography (CC), and Preparative Thin Layer Chromatography (PTLC). The outcomes revealed that the berries of P. nigrum contained alkaloid, terpenoid, steroid, and flavonoid metabolites. Two semi-pure compounds have been isolated from the dichloromethane crude extract. The obtained compounds were analysed using Fourier Transform Infrared (FTIR) spectroscopy and Ultraviolet-Visible (UV-Vis) spectrophotometer. Based on the FTIR spectrums and previous studies, these semi-pure compounds, K1A (2) and K3C (3), are expected to be 2, 4-di-tert-butylphenol and ethyl linoleate, respectively. This significant data provides preliminary findings that may lead to further purification and structure determination as a potential source of herbal medicinal compounds
Physiological behavior of greenhouse-grown chrysanthemum (Chrysanthemum morifolium ´’Shrek’ ´ and ´Bomber Green´) in response to the plant growth retardant B-9 and the cytokinin BAP
No full textilustraciones, diagramas, fotografías, tablasEl crisantemo (Chrysanthemum morifolium Ram) representa la tercera flor de corte de
importancia económica en el mercado internacional. En el presente estudio, se caracterizó
la respuesta de plantas de crisantemo ‘Shrek’ y ‘Bomber Green’ y la vida de florero de
tallos cortados, a la aplicación del retardante de crecimiento B-9 (daminozida) y la
citoquinina (6-benciladenina, BAP). En un primer ensayo se evaluó la aplicación de B-9,
con un testigo absoluto sin adición de B-9 y un testigo comercial (TC), usando 6
concentraciones diferentes aplicadas a los 28, 36, 44 y 52 días después del trasplante
(DDT). En un segundo ensayo, se evaluó la aplicación de la citoquinina (CK) BAP (0, 33,3,
66,6 y 100 mg kg-1
) suministrada a los 28, 36, 44 y 52 DDT. La respuesta a estos
tratamientos fue evaluada con una cuantificación de la masa seca acumulada en órganos
(raíz, tallo, hojas y flores) y cálculos de algunos parámetros de crecimiento. Se determinó
el índice de clorofilas con medidor portátil SPAD-502 en hojas del estrato bajo, medio y
superior. Se caracterizó también la duración en días de la vida en florero, inicio de
amarillamiento y grado de amarillamiento de las hojas. La aplicación de B-9 generó una
reducción en la altura de la planta. El cultivar ‘Shrek’ tuvo diferencias estadísticas (P<0,05)
en la acumulación y en parámetros de crecimiento relacionados con el área foliar. La
acumulación de masa seca fue mayor en tallos de los dos cultivares. Con aplicación de
CK, el índice de clorofila incrementó en los estratos medio y superior, mientras que, en las
hojas del estrato inferior disminuyó y se presentó amarillamiento del follaje. La mayor vida
en florero se obtuvo en tallos de ‘Bomber Green’. Los factores que promueven el
amarillamiento del follaje podrían estar relacionados con el material vegetal y la interacción
con las condiciones ambientales a las cuales se expongan las plantas durante el crecimiento y desarrollo (Texto tomado de la fuente).The chrysanthemum (Chrysanthemum morifolium Ram) represents the third cut flower of
economic importance in the international market. The present study characterized the
responses of chrysanthemum plants ‘Shrek’ and ‘Bomber Green’ to the application of the
growth retardant B-9 (active ingredient daminozide), and the addition of the citokinin 6-
benzyladenine (6-BAP) on the chlorophyll content and vase life of cut flower stems. The
first trial evaluated the application of seven concentrations of B-9 applied at 28, 36, 44 and
52 days after transplant (DAT). A second trial evaluated the application of three
concentrations of 6-BAP supplied at 28, 36, 44 and 52 DAT. Dry mass accumulation in the
various plant organs (roots, stems, leaves and flowers) were evaluated along with
calculation of some growth parameters. The chlorophyll index was determined with a
SPAD-502 portable meter in leaves of the lower, middle, and upper third of plants. Finally,
the duration in days of vase life and the onset and degree of leaf yellowing were
characterized in the two cultivars. The application of B-9 caused a reduction in plant height
and the cultivar ‘Shrek’ had statistical differences (P<0.05) in biomass accumulation and
growth parameters related to leaf area. Dry mass gain was greater in stems of the two
cultivars. With CK application the chlorophyll index increased in the middle and upper
leaves, while in the leaves of the lower third had lower values and yellowing symptoms.
The longest vase life was observed in flower stems of ‘Bomber Green’. The factors that
promote the yellowing of the foliage could be related to plant genetics and its interaction
with environmental conditions during the crop growing cycle.MaestríaMagíster en Ciencias AgrariasFisiología de Cultivo
