Improvement of boron soil test

Abstract

Boron soil tests often do not adequately reflect B plant uptake or deficiency levels in the Eastern United States. In an attempt to develop a better test, the following systems were studied: Silicic acid replacement of boron; B soil buffering power; and the addition of small quantities of boron (0.175 ugB/g‐soil) to each soil sample to overcome some of the stronger boron fixing sites prior to hot water extraction.

Boron extracted with B spiked hot water (r=0.80 for plant tissue B vs. extractable B, opposed to r=0.76 for nonspiked hot water) was the only new test that showed promise.

The results appear to explain why hot water extractable B correlates well with plant uptake for soils previously treated with boron fertilizer (e.g. alfalfa fields); but why, on the other hand, hot water extractable B fails to correlate well with plant boron uptake for soils not having a recent history of boron fertilization. . . in which some fixing sites apparently have to be satisfied before the hot water test will work well.     

龙眼果肉提取物改善东莨菪碱诱导小鼠学习记忆功能

【目的】比较不同剂量龙眼果肉醇提物和水提物对东莨菪碱所致记忆获得性障碍小鼠学习记忆功能的影响,初步解释龙眼果肉改善学习记忆的作用机制。【方法】分析龙眼果肉醇提物和水提物中主要活性物质含量。将无特定病原体(SPF级)雄性昆明小鼠随机分为空白组、模型组、龙眼果肉醇提物低剂量组/高剂量组(150 mg·kg~(-1)/300mg·kg~(-1))、龙眼果肉水提物低剂量组/高剂量组(150 mg·kg~(-1)/300 mg·kg~(-1)),共6组,连续灌胃28 d后,空白组腹腔注射等量生理盐水,各试验组腹腔注射东莨菪碱造模,0.5 h后,以潜伏期和穿梭次数为考察指标,采用避暗试验进行行为学测试,作为习得成绩;24 h后再次进行避暗试验,对小鼠进行记忆保持测试,测试结束后摘眼球取血,脱颈致死,取脑组织进行生化指标检测。测定脑组织的胆碱类(乙酰胆碱转移酶choline acetyltransferase,ChAT和乙酰胆碱酯酶acetylcholinesterase,AChE活力)及抗氧化相关指标(超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧物酶(glutathione peroxidase,GSH-Px)活力及丙二醛(malondialdehyde,MDA)含量),血清中抗氧化相关指标(SOD、GSH-Px活力及MDA含量)。通过综合比较各组间行为学试验指标、脑组织、血清生化指标,判断龙眼果肉改善学习记忆功能的作用效果及作用机制。【结果】分析龙眼果肉提取物成分发现,龙眼果肉水提物主要为多糖及蛋白质,醇提物除含有糖类外,还含有较丰富的酚类、黄酮类和磷脂物质,其中,醇提物中总酚、总黄酮、总磷脂含量显著高于水提物的(P0.05)。行为学试验表明,模型组小鼠在避暗试验中5 min内穿梭次数为2.89次,是正常小鼠的6.09倍,高剂量龙眼果肉醇提物和水提物组小鼠穿梭次数分别为0.75次和0.56次,与正常组无显著差异;痴呆小鼠在避暗试验中的潜伏期仅为正常组的0.43倍,与模型组相比,各剂量龙眼果肉醇提物和水提物均能显著增加痴呆小鼠在避暗试验中的潜伏期(P0.05),且存在一定剂量效应关系,其中龙眼果肉醇提物和水提物高剂量组小鼠的避暗潜伏期分别为289.18 s、290.80 s,与正常组相比无显著差异(P0.05)。生化指标方面,与模型组相比,各剂量龙眼果肉醇提物和水提物均能显著增加痴呆小鼠脑组织中ChAT活力,显著降低AChE活力(P0.05),且存在一定的剂量效应关系。相同剂量时,龙眼果肉水提物效果优于醇提物,其中龙眼果肉醇提物高剂量组,龙眼果肉水提物低、高剂量组小鼠脑组织中ChAT活力基本恢复正常水平;在抗氧化水平方面,与模型组相比,龙眼果肉醇提物高剂量组显著增加痴呆小鼠脑组织和血清中SOD、GSH-Px活力,显著降低MDA含量(P0.05),基本达到正常水平,效果优于同等剂量的龙眼果肉水提物。【结论】龙眼果肉水提物和醇提物均可改善东莨菪碱诱导记忆获得性障碍小鼠的学习记忆功能,但二者的作用机制可能存在差异,龙眼果肉水提物主要通过调节胆碱能神经系统改善学习记忆功能,其主要作用的物质基础可能为多糖或糖蛋白;醇提物则主要通过提高机体抗氧化活力改善学习记忆功能,其主要作用物质可能为多酚、黄酮、磷脂等。     

浅谈大学生学习能力的培养

高校教师应把大学生学习能力的培养放在重要地位。本文从大学生“自我编程”能力、记忆能力、创新能力的培养三个方面，具体阐述了如何培养大学生的学习能力。     

模糊联想记忆神经网络在土地质量评价中的应用

土地是一个复杂的动态系统,受到众多因素的影响,而影响因素存在很大的模糊性,应用传统的理论和方法进行评价难以得到正确结果。本文提出一种基于模糊联想记忆神经网络的土地质量评价方法,并以实例证实了该方法的简便、快速、客观和实用性。     

大豆异黄酮对低压间歇缺氧大鼠学习记忆及脂质过氧化的影响

[目的]研究大豆异黄酮对低压间歇缺氧大鼠学习记忆能力和脂质过氧化的影响,评价大豆异黄酮对低压间歇缺氧的保护作用。[方法]采用析因设计,设置地面和7 500 m缺氧两大组,地面和缺氧各再均分5组(对照组,雌二醇组,大豆异黄酮高、中、低剂量组),每个组随机设大鼠8只,雌雄各半;缺氧组采用小动物低压氧舱模拟7 500 m环境,间断缺氧,持续15 d,地面组正常饲养;试验期间,各组大鼠分别灌胃相应的药物,每天一次。给药结束时进行水迷宫实验,并取大鼠血清测定SOD活力和MDA含量。[结果]缺氧和给药2个因素间无交互作用;缺氧组水迷宫空间搜索实验中目标象限时间,平台停留时间较地面组短,经过平台次数较地面组少,同时缺氧组SOD活力较地面组增高,MDA含量较地面组增加;缺氧组给予雌二醇和不同剂量的大豆异黄酮可不同程度地提高SOD活力,降低MDA含量。[结论]低压间歇缺氧加速了大鼠体内酯质过氧化,损害了大鼠的学习记忆能力,而大豆异黄酮能改善缺氧大鼠的脂质过氧化水平,提高学习记忆能力,对低压间歇缺氧具有一定的保护作用。     

基于时间序列的山区风向预测方法研究

为更好的预测山区风向,分别使用自回归滑动平均模型(Auto-Regressive Moving Average Model,ARMA)、极端梯度提升算法(eXtreme Gradient Boosting,XGBoost)和长短期记忆网络(Long Short Memory Network,LSTM)对山区4个气象站的风向时间观测序列进行预测,比较三种算法的优劣。针对风向独特的性质,结合传统气象学知识,探索了一种风向的预测方法：引入风速序列,将风速、风向拆分为U、V风,对其分别进行预测,进而将结果合成,使用设定的风向评分检验结果。对比结果表明：1)XGBoost获得了最高的评分;2)使用双时间序列预测风向相比单序列效果更好。     

年龄对SAMP8小鼠新物体再认能力的影响

探讨年龄对快速老化敏感小鼠8(SAMP8)短期再认记忆能力的影响.结果表明,与3及7月龄小鼠比较,11月龄SAMP8小鼠的新物体再认能力增强.与对照的11月龄SAMR1(快速老化抵抗小鼠1)小鼠比较,11月龄SAMP8小鼠的新物体再认能力也增强.这种记忆的增强不受性别因素的影响. 这些结果提示在衰老过程中,SAMP8小鼠的新物体再认能力增强.     

木质纤维制造缓冲材料的应用研究

利用木质纤维材料,通过筛选合适的胶黏剂和发泡剂,采用合理的工艺制造出环保型木质纤维缓冲材料.通过静态压缩试验对制成的环保型木质纤维缓冲材料静态缓冲性能进行了试验研究.研究结果表明,所制成的环保型木质纤维缓冲材料具有良好的缓冲性能,可以部分替代泡沫塑料作为新型环保的缓冲材料.     

Fast neutron irradiation deteriorates hippocampus-related memory ability in adult mice

Object recognition memory and contextual fear conditioning task performance in adult C57BL/6 mice exposed to cranial fast neutron irradiation (0.8 Gy) were examined to evaluate hippocampus-related behavioral dysfunction following acute exposure to relatively low doses of fast neutrons. In addition, hippocampal neurogenesis changes in adult murine brain after cranial irradiation were analyzed using the neurogenesis immunohistochemical markers Ki-67 and doublecortin (DCX). In the object recognition memory test and contextual fear conditioning, mice trained 1 and 7 days after irradiation displayed significant memory deficits compared to the sham-irradiated controls. The number of Ki-67- and DCX-positive cells decreased significantly 24 h post-irradiation. These results indicate that acute exposure of the adult mouse brain to a relatively low dose of fast neutrons interrupts hippocampal functions, including learning and memory, possibly by inhibiting neurogenesis.     

A quantitative assessment of primary and secondary immune responses in cattle using a B cell ELISPOT assay

The aim of the study was to build a comprehensive picture of the appearance in the blood stream of Ag-specific plasma cells and memory B cells in the bovine model. For this purpose, we have developed a method allowing the detection and quantification of both cell types within individual calves immunised with ovalbumin. During the primary response, we detected a burst of ovalbumin-specific plasma cells at days 6 and 7 post-immunisation, which was followed by the production of specific Ab, whereas a gradual increase of memory B cells was only detected from day 15. As expected, a boost immunisation performed 7 weeks later induced a quicker and stronger secondary response. Indeed, a burst of plasma cells was detected in the blood at days 3 and 4, which was followed by a strong increase in Ab titres. Furthermore, a burst of memory B cells, and not a gradual increase, was detected at days 5 and 6 post-boost immunisation. Importantly, we showed a strong correlation between the anti-ovalbumin-specific IgG titres detected 5 months after secondary immunisation and the plasma cell numbers detected in the blood at the peak response after secondary immunisation. The detection and quantification of plasma cells following an mmunisation/vaccination strategy could constitute a very effective means for predicting the magnitude and longevity of an Ab response.