Rate of hydrolysis of urea as influenced by thiourea and pellet size

Summary Two incubation experiments and a number of field experiments were conducted to determine the effect of soil moisture tension, pellet size and addition of thiourea to urea on the rate of urea hydrolysis. In the incubation experiments at 20°C, the rate of hydrolysis of urea increased from 15 bar to 1/3 bar soil moisture tension, with the largest change (doubling) occurring from 15 bar to 7 bar moisture tension. Increasing pellet size reduced the rate of urea hydrolysis by about 12% with urea pellets weighing 0.21 g as compared to 0.01 g urea pellets after 114h. When thiourea (a metabolic inhibitor) was pelleted with urea in a ratio of two parts urea and one part thiourea, the rate of hydrolysis was halved.In a field experiment, the addition of thiourea to urea and increasing pellet size suppressed the rate of urea hydrolysis considerably for 8 days. The amount of urea hydrolyzed with urea+thiourea (21) pellets weighing 2.51 g was one-fourth of the amount of urea hydrolyzed with 0.01 g pellets of urea alone. In the other six field experiments which were set out in October, only 22% to 39% of urea +thiourea (21) was hydrolyzed at two weeks after application, while almost all of the urea was hydrolyzed when it was mixed into the soil without an inhibitor.Unter our field conditions, we would estimate that the hydrolysis of urea can be inhibited for at least one week. The inhibition of urea hydrolysis appears to be great enough that the problems encountered from the rapid hydrolysis of urea, wherever these occur, may be reduced by combined use of thiourea and either increased pellet size or band placement.     

3D数字打印技术在重度脊柱侧弯中的临床分析研究

目的:评估和比较3D数字打印技术在重度脊柱侧弯患者手术中的临床疗效及安全性。方法:按照已经设定的纳入及排除标准,对2017年1月至2019年1月诊断为重度脊柱侧弯并在我科行手术治疗的22名患者进行前瞻性分析。根据是否采用3D打印技术辅助,将其通过随机数字表分为3D辅助组(实验组)与对照组。实验组(共11例)通过Minics软件进行3D模拟设计及打印,术中进行技术辅助。对照组(11例)则通过常规的徒手置钉办法进行手术。通过CT比较两组患者的置钉准确性,并比较两组患者的其他影像学检查和相关手术指标,包括:手术时间,输血量,透视次数等。结果:本研究纳入的患者(22例)均得到至少6个月的完整随访。两组患者在术前的影像学测评,Cobb角,年龄、性别构成等指标的比较中未见显著统计学差异(P>0.05)。实验组CT评价置钉准确率为83.6%(0级及1级),对照组的置钉准确率为72.3%。两组比较有统计学差异(P<0.05)。实验组在手术时间,术中输血量及透视次数等手术指标的比较中均显著优于对照组(P<0.05)。实验组的入院后待手术时间显著高于对照组(P<0.05)。实验组在术后3天的VAS指标显著优于对照组(P<0.05),但在术后6月的比较中无显著性差异(P>0.05)。两组患者的ODI指数较术前均有显著改善(P<0.05),且两组间无显著性差异(P>0.05)。两组患者均未出现严重并发症(P>0.05)。结论:与常规的徒手置钉相比,针对重度脊柱侧弯患者,3D数字打印辅助技术能够显著的提高置钉的准确性,减少手术时间和术中输血量,大幅度减少透视危害,且降低操作难度,值得临床进一步推广使用。     

Assessment in the visual arts: Challenges and possibilities

Abstract

Assessment in art is notoriously difficult and is probably best approached with skepticism. Artistry is notoriously difficult to assess. Yet measures of student learning in art are needed for both advocacy and art education policy. Assessments, particularly large-scale assessments, influence funding and educational policy at all levels. This article explores some of the challenges of assessment in the visual arts and critically examines the Advanced Placement Studio Art Portfolio to illustrate how a product-oriented assessment might influence teaching and policy.     

Effect of urea placement on leaching losses of nitrogen from flooded rice soils

In an effort to provide an explanation for the reported variability in fertilizer N efficiency from deepplaced urea on flooded rice, a set of controlled experiments was conducted to evaluate the effect of water percolation on fertilizer loss and plant uptake from¹⁵N labeled urea supergranules. Three soils of different texture (silt loam-clay) were subjected to various percolation rates (0–20 mm/day) while planted to rice which was harvested after approximately 40 days.The results indicate that moderate to high percolation through silt loam soil will lead to significant fertilizer N losses and drastically decrease the fertilizer uptake by plants. The permeability of the clay soil was too low for any leaching to take place. It is therefore concluded that deep placement of urea supergranules not be recommended in soils where percolation rates may exceed 5 mm/day, particularly if the cation exchange capacity of the soil is low. This experiment points to the need of evaluating and reporting the percolation rates in soils where experiments with supergranular urea are conducted.Contribution from the Agro-Economic Division of the International Fertilizer Development Center (IFDC), Muscle Shoals, Alabama 35660.     

Increasing the efficiency of fall-applied urea fertilizer by placing in big pellets or in nests

Summary In three field experiments with fall-applied urea fertilizers, placement of urea in big pellets, or in nests, produced about twice as much increase in yield of subsquent spring-sown barley than did application of urea by conventional incorporation or by banding.     

瑞舒伐他汀强化治疗对支架置入术后患者血管再狭窄的影响

目的:探究瑞舒伐他汀强化治疗对行冠状动脉支架置入术后患者再狭窄率、血管内皮功能和血脂水平的影响。方法:选择2013年1月~2015年12月90例于我院行冠状动脉支架置入术后的患者。按照治疗方法的不同将患者随机分为观察组及对照组,每组45例。观察组患者术后给予20 mg/天瑞舒伐他汀强化治疗,对照组患者术后给予常规剂量(5~10 mg/天)瑞舒伐他汀治疗,连续服用6个月。比较两组患者治疗前后的血脂、C反应蛋白(CRP)、白介素8(IL-8)、一氧化氮合酶(e NOS)、内皮素-1(ET-1)水平及术后6个月支架内再狭窄率(ISR)。结果:治疗后,两组患者的胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL-C)水平均较治疗前显著降低(P0.05),且观察组患者以上指标均显著低于对照组(P0.05);观察组患者高密度脂蛋白(HDL-C)水平较治疗前增加明显(P0.05),而对照组该指标无明显改善(P0.05)。治疗后,两组患者的CRP、IL-8水平均较治疗前显著降低(P0.05),且观察组患者以上指标显著低于对照组(P0.05);观察组患者的一氧化氮合酶(e NOS)水平较治疗前显著提高,血管内皮素-1(ET-1)水平显著降低(P0.05),但对照组以上指标与治疗前相比无明显差异(P0.05)。术后6个月,观察组患者支架内再狭窄率(ISR)显著低于对照组(P0.05)。结论:瑞舒伐他汀强化治疗可通过显著改善患者血脂水平,减轻患者机体炎症状态,积极恢复内皮组织损伤,进而预防ISR的发生。