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  • Author: J. Li x
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Changes in Levels of Amino Acids and Basic Components in Burley Tobacco Produced by Roasting

Abstract

Three burley tobacco samples from three different areas in China and Brazil were roasted under three processing conditions. The amino acids and basic components of the burley tobacco samples were determined before and after roasting. Routine tobacco variables (reducing sugars, total water-soluble sugars, total nitrogen, total alkaloids, total volatile bases, and pH) were determined according to the Chinese National Standard Methods (CNSM). Free amino acids were determined by high performance liquid chromatography (HPLC). The basic compounds were isolated by use of simultaneous distillation and extraction (SDE) equipment. Their levels were determined qualitatively and quantitatively on a) a gas chromatograph (GC) equipped with a nitrogen-phosphorus detector (NPD) and b) by gas chromatography mass spectrometry (GC-MS). The results indicated that the chemical changes occurring during roasting have a significant impact on burley tobacco quality. Roasting decreased the tobacco pH value and the levels of total nitrogen, reducing sugars, free amino acids, and other nitrogenous substances, such as amines and alkaloids. The latter are usually related to the irritancy and sharp taste of burley tobacco smoke. In contrast, the levels of pyrazines, important contributors to the characteristic burley flavor, increased.

Open access
Surface Wave Speed of Functionally Graded Magneto-Electro-Elastic Materials with Initial Stresses

Abstract

The shear surface wave at the free traction surface of half- infinite functionally graded magneto-electro-elastic material with initial stress is investigated. The material parameters are assumed to vary ex- ponentially along the thickness direction, only. The velocity equations of shear surface wave are derived on the electrically or magnetically open circuit and short circuit boundary conditions, based on the equations of motion of the graded magneto-electro-elastic material with the initial stresses and the free traction boundary conditions. The dispersive curves are obtained numerically and the influences of the initial stresses and the material gradient index on the dispersive curves are discussed. The investigation provides a basis for the development of new functionally graded magneto-electro-elastic surface wave devices.

Open access
Propagation of Surface Waves in a Homogeneous Layer of Finite Thickness over an Initially Stressed Functionally Graded Magnetic-Electric-Elastic Half-Space

Abstract

The propagation behaviour of Love wave in an initially stressed functionally graded magnetic-electric-elastic half-space carrying a homogeneous layer is investigated. The material parameters in the substrate are assumed to vary exponentially along the thickness direction only. The velocity equations of Love wave are derived on the electrically or magnetically open circuit and short circuit boundary conditions, based on the equations of motion of the graded magnetic-electric-elastic mate- rial with the initial stresses and the free traction boundary conditions of surface and the continuous boundary conditions of interface. The dispersive curves are obtained numerically and the influences of the initial stresses and the material gradient index on the dispersive curves are dis- cussed. The investigation provides a basis for the development of new functionally graded magneto-electro-elastic surface wave devices.

Open access
Research on high-temperature compression and creep behavior of porous Cu–Ni–Cr alloy for molten carbonate fuel cell anodes

Abstract

The effect of porosity on high temperature compression and creep behavior of porous Cu alloy for the new molten carbonate fuel cell anodes was examined. Optical microscopy and scanning electron microscopy were used to investigate and analyze the details of the microstructure and surface deformation. Compression creep tests were utilized to evaluate the mechanical properties of the alloy at 650 °C. The compression strength, elastic modulus, and yield stress all increased with the decrease in porosity. Under the same creep stress, the materials with higher porosity exhibited inferior creep resistance and higher steadystate creep rate. The creep behavior has been classified in terms of two stages. The first stage relates to grain rearrangement which results from the destruction of large pores by the applied load. In the second stage, small pores are collapsed by a subsequent sintering process under the load. The main deformation mechanism consists in that several deformation bands generate sequentially under the perpendicular loading, and in these deformation bands the pores are deformed by flattering and collapsing sequentially. On the other hand, the shape of a pore has a severe influence on the creep resistance of the material, i.e. every increase of pore size corresponds to a decrease in creep resistance.

Open access
Genetic Analysis of Growth and Susceptibility to Bacterial Wilt (Ralstonia solanacearum) in Eucalyptus by Interspecific Factorial Crossing

Summary

Factorial mating crosses of Eucalyptus urophylla × E. tereticornis (3 x 5), E. urophylla × E. camaldulensis (3 x 3) and E. urophylla × E. exserta (3 x 3) were used for genetic analysis of growth traits and susceptibility to bacterial wilt (Ralstonia solanacearum). Genetic effects including female, male and female × male interaction were examined for height (H) and diameter at breast height (DBH) at age five as well as final bacterial wilt index (BWI) in both nursery inoculation and field assessment by five years of age. Female, male and female x male variances appeared to have a significant role in growth traits H and DBH though their magnitude varied for the factorials studied. For the trait BWI additive (male) and dominant (female x male) effects were both involved in the genetics of bacterial wilt susceptibility, and additive was the major. Estimates of narrow-sense heritability (h2) for H, DBH and BWI ranged from 0.11 ± 0.06 to 0.70 ± 0.09, varying with either trait or factorial. Growth traits (H and DBH) had low and non-significant phenotypic and genetic correlations with BWI in all the three factorials, ranging from -0.10 ± 0.08 to 0.17 ± 0.14 in coefficient of correlation. This indicates that it may be possible to select superior trees with both fast growth and high resistance to bacterial wilt in eucalypt hybrid populations in operational breeding programs.

Open access
Induction of 2n pollen by colchicine in Populus × popularis and its triploids breeding

Abstract

Induction of 2n pollen is a required technique for cultivating polyploid via sexual polyploidy. Orthogonal design or Taguchi Design was applied to select the best treatment process of 2n pollen induction in Populus × popularis from different levels of the meiosis stage of male flower buds, colchicine concentration, times of injection, and interval between injections. Flow cytometry and chromosome counting were used to identify the triploids from the offspring of P. × euramericana. (Dode) Guinier pollinated with induced pollen of P. × popularis. The results showed that high 2n pollen rate can be achieved by selecting the flower buds during diakinesis stage in meiosis, and then injecting 0.6% colchicine 4 times with 2 hours interval. The 2n pollen rate reached 62.10% by this process, and two triploids were obtained, which indicates that it is possible for cultivating triploids via 2n pollen induction by colchicine treatment in poplar. Results and protocol related to 2n pollen induction, polyploid identification and effect of 2n pollen in this study might be applicable in polyploidy breeding in section Aigeiros and Tacamahaca of poplar.

Open access
Seasonal population dynamics of the monogeneans Quadriacanthus kobinensis parasitising Clarias fuscus in Pearl River, China

Summary

This paper describes the population dynamics of Quadriacanthus kobinensis on the gills of Clarias fuscus following a field investigation from June 2012 to May 2013 in Pearl River, China. The results showed that in Q. kobinensis prevalence was highest (70.13 %) in the summer and Mean intensity reached a peak in the autumn. The maximum number of Q. kobinensis in a fish was 474. The maximum abundance occurred during summer (25.8) and the minimum values during spring. Q. Kobinensis exhibited an aggregated distribution in all seasons. The highest prevalence was in hosts of 28 cm<L and the infection intensity was also the highest in this group. In terms of infection intensity, host of 28 cm<L differed significantly from those of 24<L≤26 cm, but no significant differences existed in other body length groups.

Open access
Synthesis of 3-Oxo-α-ionol Ethyl Carbonate and its Conversion to Megastigmatrienones in Tobacco Smoke

Abstract

3-Oxo-α-ionol ethyl carbonate, a precursor of megastigmatrienones was prepared by reduction of α-ionone to α-ionol, followed by esterification with ethyl chloroformate and then by oxidation with t-butyl chromate. The total yield was about 23%. Infrared (IR) and mass spectra of this compound were determined. Upon smoking, cigarettes to which 0.002% by weight of the titled compound was added had an improved and more harmonious flavor. The smoke was sweeter and had a cleaner after taste. Experimental results suggest that the title compound added to the tobacco pyrolyzes to form megastigmatrienones during smoking.

Open access
Morphological characterization and in vitro germination of heat-treated pollen in Eucommia ulmoides

Abstract

Polyploid breeding has the potential to increase the economic secondary metabolites of Eucommia ulmoides. However, pollination with induced ploidy-mixed pollen has failed to produce polyploids (GAO, 2006). In this investigation, the morphological characterization and in vitro germination of heat-induced ploidy-mixed pollen of E. ulmoides were analysed to determine why there is no polyploid production. Heat-treated pollen grains were easily distinguished as large and small according to their length. The large pollen grains were significantly longer than both untreated and heat-treated small samples, suggesting that they were probably 2n pollen. Rather than the three germinal pores in small pollen, the large grains typically had four pores and, in some cases, shallow furrows, which might affect their germination. Although the maximal germination rates of the treated small and large pollen were not significantly different, the large pollen germinated tardily during the early stages of incubation. The small pollen maintained its growth during the incubation, but the tube growth of large pollen almost stopped after 24 h incubation. Both vegetative and generative nuclei in the large pollen moved into tubes later than in small pollen and the frequency of mitosis in generative nuclei of large pollen was low. Therefore, the tardy germination, poor tube growth, and weak activity of both vegetative and generative nuclei probably caused the poor competition of large pollen in certation. Finally, techniques to increase the competition of highploidy pollen and the prospect of 2n female gamete induction in the polyploid breeding program of E. ulmoides are discussed.

Open access
Hybridizing ability and heterosis between Eucalyptus urophylla and E. tereticornis for growth and wood density over two environments

Abstract

Interspecific hybrids of Eucalyptus urophylla × E. tereticornis in a factorial-mating design were used to analyze general hybridizing ability (GHA), specific hybridizing ability (SHA) and heterosis for height (H; 0.5, 1.5, 2.5, 4 and 7.5 years in age), diameter at breast height (D; ages 1.5, 2.5, 4 and 7.5) and wood density (WD; age 7.5) across two environments. The GHA variances were significant for all traits, and those of the SHA were also significant for most of the traits but with less magnitude, indicating the greater importance of additive gene effects in explaining the phenotypic variation among hybrids. The narrow-sense heritability (h2) and dominance (d2) estimates with hybrid growth and wood density ranged between 0.02±0.05 (d2 in D7.5) and 0.23±0.10 (d2 in H1.5) over the different ages, suggesting weak additive and dominant effects on these traits. Additive genetic correlations of growth with wood density were weak at age 7.5. Female general combining ability (GCA) based on maternal open-pollinated families was not necessarily a good indicator of GHA as their correlations were 0.48 (P=0.17), 0.65 (P=0.04) and -0.56 (P=0.10) for H7.5, D7.5 and WD7.5, respectively. A great proportion of hybrids showed positive female-parent heterosis (FPH) at age 7.5, with the highest relative FPH of 47.2% in D7.5. This study demonstrates the heterosis between inter-sectional species and could have implications for E. urophylla × E. tereticornis hybrid breeding.

Open access