ABSTRACT Explaining where plants originated and how plants migrated between eastern Asia and other Northern Hemisphere regions is still challenging. The genus Arisaema is considered a good example to illuminate this process, due to its wide distribution in both the tropical and temperate zones. Based on comprehensive taxon sampling, the historical biogeography of Arisaema was conducted using the molecular data from four chloroplast DNA regions. The phylogeny of Arisaema was studied by using ML and BI methods. Divergence times of Arisaema species were estimated by the uncorrelated lognormal Bayesian method. The ancestral area reconstruction of Arisaema was performed with BioGeoBEARS and Bayes-DIVA. Our results indicated that the crown group of Arisaema originated in Southeast Asia ca. 31.28 Ma. After the initial origin, Arisaema was inferred to have become widespread in Southeast Asia. Members in Himalayas, Africa and North China, Japan, the Korean Peninsula region (NJK region) were derived from migrants originating in Southeast Asia. American members were derived from migrants originating in the NJK region. Arisaema originated in Southeast Asia during the Oligocene with the development of tropical rainforest and a warm, moist climate. During the Oligocene to Miocene, Southeast Asia was the original center for the diversification of Arisaema in the NJK region.

Abstract: The radial variation in cell morphology of ten-year-old Melia azedarach trees planted in northern Vietnam was experimentally investigated. The earlywood fiber lumen diameter and latewood fiber lumen diameter were almost unchanged from pith to 6th ring before significantly decreasing and remaining constant from 7th ring outwards. In contrast, fiber cell wall thickness in both earlywood and latewood increased from pith to 7th ring before becoming stable towards the bark. The maturation age of earlywood vessel lumen diameter estimated by segmented regression analysis indicated that wood of the Melia azedarach could be classified into core wood and outer wood, and the boundary between core and outer wood may be located at 7th ring from pith. This should be taken into account in wood processing using M. azedarach grown in northern Vietnam.

Abstract In this research, a novel organic photocatalyst of 10-(Perylene-3-yl-10H-Phenoxazine (PHP) has been synthesized successfully from perylene and phenoxazine via Buchwald-Hartwig C-N coupling. The chemical structure of catalyst was determined via proton nuclear magnetic resonance (1H-NMR) spectrum and optical properties were investigated through UV-Vis spectroscopy. The PHP has been used as the reducing photoredox catalyst for organocatalyzed atom transfer radical polymerization (ATRP) under UV irradiation. The well controlled molecular weight of polymers based on methyl methacrylate monomers have been obtained with monomer conversion up to 77.61% and low polydispersity index under 1.5.

Abstract In the present paper, the free and forced vibration of multiple cracked multi span continuous beams made of functionally graded material (FGM) is investigated by the dynamic stiffness method. First, there are constructed dynamic stiffness matrix and nodal load vector of multiple cracked FGM beam element using Timoshenko beam theory and massless double spring model of crack. Then, effect of cracks parameters on free and forced vibration of the FGM continuous beams is examined. The theoretical developments are validated by numerical examples. The obtained results provide an efficient method to analyze free and forced vibration of multiple cracked FGM framed structures and assessment of the behavior of damaged structures.

Abstract In this paper, authors present the study of free vibration of bending multiple cracked functionally graded material (FGM) beam. Vibration equations of multiple cracked FGM beam were established by using the rotational spring model of cracks, dynamic stiffness method (DSM) and actual position of neutral plane. The frequency equation obtained was in a simple form, that provides an effective approach to study not only free vibration of the beams but also inverse problems like identification of material and crack parameters in structure. The obtained numerical results show good agreement with other previous published results. Thence, numerical computation has been carried out to investigate the effect of each crack, the number of cracks, material and geometric parameters on the natural frequencies of multiple cracked Timoshenko FGM beams.

Abstract The present paper addresses free vibration of multiple cracked Timoshenko beams made of Functionally Graded Material (FGM). Cracks are modeled by rotational spring of stiffness calculated from the crack depth and material properties vary according to the power law throughout the beam thickness. Governing equations for free vibration of the beam are formulated with taking into account actual position of the neutral plane. The obtained frequency equation and mode shapes are used for analysis of the beam mode shapes in dependence on the material and crack parameters. Numerical results validate usefulness of the proposed herein theory and show that mode shapes are good indication for detecting multiple cracks in Timoshenko FGM beams.