Effect of gamma irradiation on the physico-chemical and visual properties of mango (Mangifera indica L.), cv. ‘Dushehri’ and ‘Fazli’ stored at 20 °C

The effect of γ-irradiation doses (0.3, 0.5, 0.7, 1.0, 6.0, 10.0 kGy) on different physico-chemical and visual properties of two Indian cultivars of mango, cv. ‘Dushehri’ and ‘Fazli’ was observed during storage at 20 °C for the evaluation of delayed ripening and extension of shelf-life. Visually all the irradiated fruit showed greener peel and lighter pulp throughout the storage, however, radiation injuries were present in ‘Dushehri’ treated with 6–10 kGy and in ‘Fazli’ with 1–10 kGy. Loss of fruit due to rotting was less in the irradiated samples, treated up to 1 kGy of both the cultivars. Irradiated fruit of both the cultivars at high doses (6–10 kGy) showed increased sugar content from 0 d, however, all the treated fruit registered a slower rate of increase of sugars with storage compared to the respective controls and those treated with the lower doses of 0.5 and 0.7 kGy attained peak sugar concentration later. Significant (p ≤ 0.05) textural deterioration could be detected immediately after irradiation, in ‘Dushehri’ at doses ≥1 kGy and in ‘Fazli’ at doses ≥0.7 kGy. However, low dose treated fruit (0.3–1 kGy) of both the cultivars softened at a considerably slower rate during storage and registered significantly greater fruit firmness (compression strength) throughout the storage period. Similarly, ‘Dushehri’ treated with 0.3–0.7 kGy and Fazli treated with 0.7 kGy registered significantly greater flesh firmness (shear strength). ‘Dushehri’ treated with 0.3–1 kGy and ‘Fazli’ with 0.5–1 kGy also registered significantly harder and tougher peel, as determined by puncture test, throughout the storage. Scanning electron microscopy (SEM) performed on 3rd and 2nd d of storage of ‘Dushehri’ and ‘Fazli’ respectively, revealed microstructural breakdown at and above 1 kGy in both cultivars. Cell separation could be observed in ‘Fazli’ even at 0.7 kGy. SEM also revealed that the control fruit were in a more advanced stage of ripening than the low dose treated fruit. The study showed the feasibility of low dose γ-irradiation on ‘Dushehri’ (0.3–0.7 kGy) and ‘Fazli’ (0.5 and 0.7 kGy) that induced useful delay in ripening and extension of shelf-life by a minimum of 3 and 4 d, respectively.     

2种广东丛生竹炭性能的研究

利用广东小叶龙竹和马来甜龙竹2种丛生竹,在砖土窑设备中炭化制取竹炭。测试分析其基本理化性能,进行甲醛、苯等有害物质吸附特性试验,并用扫描电子显微镜分析其微观结构。研究结果表明:(1)2种丛生竹炭的基本理化性能差异不明显,但小叶龙竹炭比表面积是马来巨竹炭的3倍,相差比较大。(2)2种竹炭对甲醛、氨、苯和甲苯都具有吸附功能,但吸附的回归方程不同,吸附效果小叶龙竹炭比马来巨竹炭好。(3)经电子扫描电镜观测2种竹炭的微观结构是有差异的。     

音乐在体育教学中的运用

本文从音乐与体育的有机联系上论述了音乐对提高体育教学效果的积极作用,以及在运用中对音乐内容、节奏的选择,以期引起对体育教学中引入音乐的重视,从而更好地提高体育教学质量.     

FRW阻燃桦木胶合板的性能研究

选用东北林业大学木材科学与应用技术研究所研制的专利产品——新型FRW木材阻燃剂处理桦木单板,用以研制阻燃性能优异的FRW阻燃桦木胶合板,并对其各项物理力学性能和阻燃性能进行了测试。研究结果表明:FRW阻燃桦木胶合板的物理力学性能可达到国家标准GB 9846.4—88《胶合板 普通胶合板通用技术条件》的规定,阻燃性能达到日本标准JISD1322-77中规定的难燃一级品的标准和国家标准GA/T42.1《阻燃木材燃烧性能试验方法—木垛法》中的规定的阻燃木材标准。     

硬质纤维板压制混凝土模板的研究

探讨用硬质纤维板制造混凝土模板的可行性。用正交试验法研究浸胶时间、浸胶后干燥时间、树脂与水的比率、热压压力、时间和温度对硬质纤维板混凝土模板性能的综合影响；进而进行生产性试验，以验证优化工艺的可靠性。     

Influences of moisture content on the catalysis of sulfur dioxide and attainable properties in a vapor-phase treatment of wood with formaldehyde

Influences of moisture content on the catalysis of sulfur dioxide and physical properties of reaction products were examined for a vapor-phase treatment of spruce wood with formaldehyde. The reaction rate was strongly dependent on the amounts of water and sulfur dioxide in the reaction system, and this was consistent with a proposal that the hydroxymethylsulfonic acid (HOCH₂SO₃H) formed from sulfur dioxide, water, and formaldehyde acts as a catalyst for the reaction. However, not all water molecules contributed to the formation of HOCH₂SO₃H, because some were adsorbed by the wood components. When the initial moisture content was high, polymeric cross-linking was likely because the ultimate weight gain was much greater than the value estimated based on monomeric cross-links. The lower values of antiswelling efficiency and higher equilibrium moisture content at a specific level of weight gain also suggested the existence of polymeric cross-links. However, the difference in the length of cross-links did not significantly influence the mechanical properties.Part of this research was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, April 2003     

人工复合基质对微型盆栽月季生长发育影响的研究

比较系统地研究了7种不同无土人工复合基质对微型盆栽月季(Rosa hybrida ‘Miniature Pink’)生长与发育的影响。结果表明，100％泥炭，70％泥炭 30％珍珠岩，70％珍珠岩 30％泥炭这3种基质比较理想，其对微型盆栽月季的株高、枝叶鲜样质量及干样质量、叶面积、平均根长、最长根长、根鲜样质量及干样质量、现蕾日期、开花日期、花朵直径等均表现为显著的促进作用；微型盆栽月季无土基质的优化物理性状为：容重O．12～0．19g／cm^3，比重1．6～1．9g／cm^3，含水量(风干基质)6％～16％，总孔隙度90％～94％。     

Nitrate fate in a Mexican Andosol: Is it affected by preferential flow?

Andosols are the dominant soils in the Valle de Bravo basin, the origin of a significant amount of Mexico City's drinking water. The main land use is agriculture and most of the existing surface water bodies are eutrophic. Nitrogen fertilizer is used extensively. There have been very few studies on nitrate (NO₃⁻) fate in this type of soil and region. Comprehensive laboratory studies were conducted to determine the fate of NO₃⁻ in an Andosol profile from Valle de Bravo, in order to assess the risk of water resources contamination. Nitrate retention was analysed statically (using batch experiments) and dynamically (using intact and packed soil columns) at different soil depths and its competition with Cl⁻ was evaluated. Complementary laboratory experiments were conducted to study water transport through the columns and nitrogen transformations in the soil. In batch and columns, NO₃⁻ adsorption was linear in the range of concentrations studied and higher in the deepest soil layer. Preferential flow pathways were found in the unaltered deeper soil layers, while tillage activity in the top layer destroyed the pore continuity. In spite of the deeper soil layer's greater capacity for NO₃⁻ retention, the presence of preferential flow pathways coupled with high rainfall intensities, makes the NO₃⁻ mobile below the root zone at 1 m depth and increases the risk of groundwater contamination. The results illustrate the complexity of nitrate fate in Andosols and can be used to improve agricultural practices in the central Mexico region.     

The effect of organic supplementation of solarized soil on the quality of tomato fruit

Soil solarization, used to control weeds and soil-borne pathogens in hot climates, has not yet been widely adapted as a commercial practice because of its lack of efficacy. Experiments were carried out in southern Italy over two growing seasons to study the effect of three levels (0, 0.35 and 0.7 kg m⁻²) of organic supplementation of the soil prior to solarization on soil mineral availability and fruit quality attributes. Soil temperature and chemical properties were monitored, together with changes in the physical characteristics and chemical composition of tomato fruits grown under commercial greenhouse conditions. Organic supplementation increased the soil temperature achieved through solarization by 3.9 to 5.5 °C. Organic supplementation increased (P ≤ 0.05) the soil concentration of NO₃⁻-N, exchangeable K₂O, Ca²⁺, Na⁺ and Mg²⁺ and the level of electrical conductivity in the soil extract. Physical characteristics of tomato fruits were improved by supplementation, with fresh and dry weight enhanced up to 11 and 21%, respectively, mesocarp thickness up to 19%, firmness up to 36% and skin redness (a^*/b^* ratio) up to 24%. As the supplementation rate was raised from 0 to 0.7 kg m⁻², the fruit content of reducing sugars increased (P ≤ 0.01) from 1.75 to 2.14 g per 100 g f.w., ash from 0.49 to 0.62%, soluble solid from 5.12 to 6.18 °Brix, titratable acidity from 0.16 to 0.19%, and ascorbic acid from 25.1 to 32.5 mg 100 mL⁻¹. We concluded that organic supplementation appears to be a valuable and environmentally friendly way to improve the mineral availability in the soil and improve fruit quality of tomato.