Fate of fertilizer nitrogen applied to wheat under simulated mediterranean environmental conditions

Triticum aestivumThe fate of fertilizer nitrogen applied to dryland wheat was studied in the greenhouse under simulated Mediterranian-type climatic conditions. Wheat, L., was grown in 76-cm-deep pots, each containing 50–70 kg of soil, and subjected to different watering regimes. Two calcareous clay soils were used in the experiments, Uvalde clay (Aridic Calciustoll) and Vernon clay (Typic Ustochrept). Fertilizer nitrogen balance studies were conducted using various¹⁵N-labeled nitrogen sources, including ammonium nitrate, urea, and urea amended with urea phosphate, phenyl phosphorodiamidate (a urease inhibitor), and dicyandiamide (a nitrification inhibitor). Wheat yields were most significantly affected by available water. With additional water during the growing period, the recovery of fertilizer nitrogen by wheat increased and the fraction of fertilizer nitrogen remaining in the soil decreased. In the driest regimes, from 40 to 65% of the fertilizer nitrogen remained in the soils. In most experiments the gaseous loss of fertilizer nitrogen, as estimated from unaccounted for¹⁵N, was not significantly affected by water regime. The¹⁵N not accounted for in the plant and the soil at harvest ranged from 12 to 25% for ammonium nitrate and from 12 to 38% for regular urea. Direct measurement of labeled ammonia loss from soil indicated that ammonia volatilization probably was the main N loss mechanism. Low unaccounted-for¹⁵N from nitrate-labeled ammonium nitrate, 4 to 10%, indicated that N losses due to denitrification, gaseous loss from plants, or shedding of anthers and pollen were small or negligible. Amendment of urea with urea phosphate to form a 36% N and 7.3% P product was ineffective in reducing N loss. Dicyandiamide did not reduce N loss from urea presumably because N was not leached from the sealed pots and denitrification was insignificant. Amendment of urea with 2% phenyl phosphorodiamidate reduced N loss significantly. However, band placement of urea at as 2-cm soil depth was more effective in reducing N loss than was amendment of broadcast urea with phenyl phosphorodiamidate.     

Tracing axons in the human brain: A method utilizing light and TEM techniques

The neuroanatomy of experimental animals has been investigated through a variety of histological and physiological techniques. Recently, more sophisticated methods have permitted a better understanding of the complex connections of animal brains. In contrast, the methods available for the direct examination of the human brain have remained relatively primitive. We have developed a staining method (paraphenylene-diamine method: PPD) which bridges the techniques of light and electron microscopy. The method permits the tracing of degenerated fibers in the human brain even after very long survival periods. With this method we have documented several visual pathways not previously described in man. We have also demonstrated, in several species, that products of axonal degeneration remain far longer than previously supposed. The PPD technique is relatively simple, reliable, provides high resolution, works in human brains, and can be used in conjunction with TEM.     

Review of thermal comfort design based on PMV/PPD in cabins of Korean maritime patrol vessels

This study has focused on the evaluation of the optimal temperature in each cabin of the Korean maritime patrol vessels. We aptly modified the inland indoor items and criteria of clothing and activities, and then investigated the human factors in the cabins of Korean maritime patrol vessels. The total thermal resistance of clothing in the wheelhouse was 0.097, 0.079, 0.096, and 0.130 m² °C/W and that for the accommodation areas was 0.067, 0.059, 0.084, and 0.101 m² °C/W in spring, summer, fall, and winter, respectively. The metabolic rate was 228.04 W/m² in the training room and above 100 W/m² in the engine room and auxiliary machine room. In the wheelhouse and accommodation, the metabolic rate was 78.14 and 44.45 W/m², respectively. Based on human factors, the optimum temperature was 23 °C in the wheelhouse and 29 °C in the accommodation. Therefore, 6 °C of energy can be saved in case of PMV/PPD-based air conditioning.     

基于PMV/PPD的船舶舱室热舒适探讨

对某1000t巡逻船各舱室内的最佳温度加以估计。适当的修正陆上人员穿着和活动的规则和标准,调查了该巡逻船的各种人为因素。驾驶室一年四季总的服装热阻分别为0.097,0.079,0.096,0.130 m2℃/W,生活区一年四季总的服装热阻分别为0.067,0.059,0.084,0.101m2℃/W。培训室的新陈代谢率...     

用透射电镜考察柴油中蜡晶的形态

测定了兰州石化0#柴油、大庆石化0#柴油和格尔木炼油厂0#柴油中正构烷烃的碳数分布, 也测定了它们添加降凝剂前后的冷滤点(CFPP), 并利用透射电镜观察了添加降凝剂(PPD)前后样品在低温下的蜡晶微观形态。结果表明,柴油未加降凝剂时,蜡晶在低温下的尺寸在200nm以上;添加降凝剂后,若能将柴油的蜡晶颗粒分散为100nm以下,则具有较好的降凝效果。从蜡晶的微观尺寸解释了柴油降凝剂的作用机理。     

船舶中央空调热舒适性影响因素及其评价方法

对船舶中央空调热舒适性的影响因素进行了分析,同时对舱室微气候条件、空气品质及船员人体因素对热舒适性的影响进行了研究,并介绍了船舶空调热舒适性的评价和预测。     

The migration and degradation of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine from rubber hoses in milk lines

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), an anti-ageing agent in rubber hoses used in milk lines, may migrate into the milk and cause safety issues. Thus its migration and degradation in simulants/milk were studied to explore the changing trends and final levels, by high-performance liquid chromatography. The results showed that 6PPD continuously increased in 95% ethanol and degraded more easily in simulants with a high water content. The degradation may be attributed to the π-conjugated system of 6PPD and smaller steric hindrance of degradation products. No migration was observed into milk after 10 min. This study provides a novel and effective approach to evaluating 6PPD trends and safety for the dairy industry.