刚架拱桥破坏机理的分析

本文根据刚架拱桥结构的受力特性建立全桥及局部实体模型分析刚架拱桥的破坏机理,文中利用MIDAS/Civil模型,逐步减少模型中的横系梁,以考察横向联系的破坏对桥梁整体性的影响,研究表明由于微弯板产生的水平推力导致了横系梁的破坏,跨中截面和外弦杆破坏主要原因为截面高度不够。     

The response to lighting of minimally processed chard: Influence on its shelf life

BACKGROUND: The effect of lighting on minimally processed chard during storage was studied. To compare the influence of pigmentation on the behaviour of the vegetable when exposed to light, the white and green parts were processed separately. Four films with different permeabilities were tested. RESULTS: Lighting caused an increase in stomatal aperture and respiratory rate. White chard stored under lighting achieved atmospheres with higher CO₂ and lower O₂ content than samples packed in the same film kept in the dark. The green part stored under lighting saw respiratory activity compensated by photosynthesis and the composition of the atmosphere remained similar to atmospheric conditions inside all films. After day 15 of storage, with pigment breakdown terminating photosynthesis, respiratory activity gave atmospheres of up to 10% O₂ and 9% CO₂ in P‐Plus 120 film. CONCLUSION: Exposure to light lowered quality in both the green and white parts of chard, significantly reducing its shelf life. P‐Plus 120 film best preserved the sensory qualities and allowed a longer shelf life to be achieved for both white and green chard in all storage conditions. Colour was particularly affected in lit conditions in the white section samples. For the green samples, it was texture that deteriorated the most. Copyright © 2008 Society of Chemical Industry     

Characterization of Native Microbial Population of Swiss Chard (Beta vulgaris, type cicla)

The native microflora of fresh Swiss chard (Beta vulgaris, type cicla) was quantified and characterized. The populations concentration of the different microorganism groups presented great variability among different lots, that was attributed to their separated histories. The mean populations of the native microflora were: 3.0×10⁶ cfu/g for mesophilic, 3.25×10⁵ cfu/g for psycrotrophic microorganisms, 9.23×10³ cfu/g for lactic acid bacteria, 2.95×10³ cfu/g for total coliforms, 1.21×10⁴ cfu/g for yeasts, 4.75×10³ cfu/g for molds and 4.2×10³ cfu/g for staphylococci. The following species were identified: Micrococcus roseus, Micrococcus sedentarius, Lactobacillus paracasei subsp. paracasei, Bacillus subtilis, Bacillus pumilus, Alternaria spp., Botrytis spp.,Aspergillus spp., Microsporium spp., Fusarium spp. and Trychophyton spp. Neither fecal nor pathogens were found. Immersion of Swiss chard leaves in tap water at 18 °C for 4 min reduced microbial populations but did not accomplish more than 70 percent removal in any of the populations under study.     

Folate fortification of white and whole-grain bread by adding Swiss chard and spinach. Acceptability by consumers

The aim of this work was to study the effect of bread-making on the content of endogenous folate of white and whole-grain bread fortified with either Swiss chard or spinach at 20 g/100 g and 40 g/100 g measured by HPLC (H4-folate and 5-CH3-H4-folate); and to assess the sensory acceptability of folate-fortified breads compared to non-fortified breads. The fortification of breads with 20 g/100 g and 40 g/100 g vegetables significantly (p < 0.001) increased the total folate content (from 19.9 to 57.9 μg/100 g in white bread and from 37.4 to 75.5 μg/100 g in whole-grain bread). Moreover, 40 g/100 g Swiss chard- and spinach-fortified breads obtained higher scores in overall acceptability than 20 g/100 g fortified or control bread for both white and whole-grain breads. The consumption of two servings (56 g each) per day of 40 g/100 g fortified bread would meet the daily folate requirements by 14.3–21.8% in adults and 9.6–14.5% in some special states like women of child-bearing age.     

Purification and characterisation of polyphenol oxidase from red Swiss chard (Beta vulgaris subspecies cicla) leaves

We report purification and characterisation of a polyphenol oxidase from red Swiss chard (rcPPO). Our purification procedure resulted in a 39-fold enrichment in specific activity and 17% recovery of total enzyme activity. The purified rcPPO appeared as a monomeric protein of 41 kDa, with a specific conformation conserved in the Cu²⁺ combining region. It was optimally active at pH 7.5 and 45 °C. It had a diphenolase substrate preference towards l-DOPA, catechol and chlorogenic acid, but also exhibited weak monophenolase one toward 4-methoxyphenol and l-tyrosine. We also found that the enzyme was activated by K⁺, Na⁺, SDS and laurouyl sarcosine, but inhibited by divalent cations including Ca²⁺, Cu²⁺. Its activity was completely inhibited by ascorbic acid, cysteine, 1,4-dithiothreitol, β-mercaptoethanol, sodium diethyldithiocarbamate, sodium metabisulphite, sodium sulphite and thiourea. This first report on the purification and characterisation of red Swiss chard PPO provides a basis for understanding and use of this enzyme.     

叶用甜菜农艺特性及综合利用价值分析

叶用甜菜是以叶片作为主要原料的二年生草本植物。其营养丰富,柔嫩多汁,适口性好,不仅是猪、牛等喜食的青饲料之一,也可用作草药或作为蔬菜食用。叶用甜菜是糖甜菜的近缘种,作为不可多得的甜菜遗传种质材料,是改良糖甜菜遗传基础的重要资源之一。近年来国内外科研人员从叶用形态学、色泽以及风味品质等方面入手培育出了一些新的品种,具有食用、观赏等兼用的特性,有着广阔的开发利用前景。本文针对叶用甜菜的生物学分类、植物学特性等农艺特征及食用、饲用、药用等营养功能的综合利用价值进行了分析。     

The effect of three organic pre-harvest treatments on Swiss chard (Beta vulgaris L. var. cycla L.) quality

Despite the increasing interest in organic products, our understanding of how different organic treatments affect fruit and vegetable quality is still limited. The effect of three organic pre-harvest treatments [effective microorganisms (EM), a fermented mixture of effective microorganisms with organic matter (EM-Bokashi + EM), and an auxiliary soil product (Greengold^®)] on Swiss chard quality was evaluated. The Swiss chard was analyzed 8 and 19 weeks after sowing. The treatments did not notably modify the physical and chemical quality of the chard when compared with control plants. Chard harvested 19 weeks after sowing showed greater differences in nutritional quality than chard harvested 8 weeks after sowing. Control plants had higher water content than the plants treated with EM, EM-Bokashi + EM and Greengold^®. Chards treated with EM-Bokashi + EM had lower ascorbic acid content and higher phosphor and magnesium content than control plants. Application of EM to plants induced higher levels of calcium compared with non-treated plants.