CDP-416型压缩机密封气系统的改造

对陕京输气管道府谷压气站CDP-416型离心压缩机密封系统和密封气供应系统进行改造,更新并完善了干气密封系统的供应流程和控制过程,对密封气供应系统实施了加装手动球阀、增加辅助密封气备用气源、更新操作规范、人工控制辅助密封气的供应压力、缩短停机后机组壳体内工艺气的放空时间等改造措施,使机组在不同运行阶段,密封介质的供应流程更趋合理,满足了机组对密封气的要求,节约了大量氮气。     

黑芥与花椰菜体细胞杂种花粉母细胞的减数分裂不同步及染色体行为异常

本研究对黑芥与花椰菜体细胞杂种及其双亲的花粉母细胞减数分裂行为进行了观察和比较,结果表明黑芥与花椰菜的花粉母细胞减数分裂同步性很高,而其体细胞杂种表现出明显的减数分裂不同步,各杂种不同株系间减数分裂不同步的程度与跨度各异。减数分裂不同步发生是由于为部分花粉母细胞在减数分裂某一时期发生停滞或推迟,这一时期(或第一个停滞时期)主要发生在第一次减数分裂的前期。花粉母细胞发育虽不同步,但最后均完成减数分裂形成花粉粒,所形成的花粉粒的活性相差甚远。此外,研究结果还显示,体细胞杂种有着较高的减数分裂染色体行为异常频率,尤其是在中期Ⅰ后。主要表现为减数分裂中期Ⅰ的染色体的早迁、后期Ⅰ和后期Ⅱ的染色体滞后及染色体不均等分离、四分体时期的异常等现象。花粉粒的活性与减数分裂时期染色体行为异常程度有关,染色体行为异常及微核现象出现的频率越高,相对的花粉粒活力也越低。     

基于LUCC的冀北土石山区东北沟流域土壤侵蚀时空变化分析

 在GIS技术的支持下,利用气候、土壤、植被盖度、DEM、土地利用现状调查和影像等数据,揭示东北沟流域土地利用和土壤侵蚀变化特点,明确土地利用类型与土壤侵蚀的关系。结果表明：1）近20年来流域土地利用变化剧烈,林地增加,草地、耕地和难利用土地减少,林地和草地之间及其内部转化较为明显;2）土壤侵蚀模数由1990年的5136.13t/(km2·a)减小到2009年的1823.30t/(km2·a),土壤侵蚀强度明显减弱,土壤侵蚀由轻度侵蚀(32.78%)和中度侵蚀(28.49%)为主减弱到以微度侵蚀(42.16%)和轻度侵蚀(33.25%)为主;3）不同土地利用类型的平均土壤侵蚀模数均有大幅度的下降,其差异也比较明显,林地、居住建筑用地的侵蚀强度较小,难利用土地土壤侵蚀强度较大。难利用土地是今后水土流失治理的重点区域。     

A new 3D conceptual structure modeling of biochars by molecular mechanic and molecular dynamic simulation

Purpose

The combination of analytical chemistry and simulation methods provides more complete information about biochars.

Materials and methods

The biochars prepared by pyrolysis of the crop straw at 300 and 500 °C were investigated by elemental analysis, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and solid-state ¹³C nuclear magnetic resonance (NMR) spectrometry to build the 2D structural models of biochars. The most stable and balanced 3D conformations were gained by optimizing in the optimized potential for liquid simulation (OPLS) force field of molecular mechanic and molecular dynamic simulation of HyperChem® software.

Results and discussion

There were few O-containing and N-containing compounds in biochars. According to the results of Py-GC-MS, 41 and 28 pyrolysis products were identified for the building of the conceptual models of 300 and 500 °C biochars. Solid-state ¹³C NMR data also demonstrated that there were very high values of unsaturated C in biochars. The agreement between elemental concentration and chemical functional groups of two simulated models and experimental biochars was successfully achieved. Quantitative structure activity relationship (QSAR) properties were calculated and indicated the correlation of molecular structures with properties such as surface area, volume, polarizability, refractivity, and hydration energy.

Conclusions

The conceptual structural models of corn straw biochars produced at 300 and 500 °C were C₇₈H₆₈N₂O₂₅ and C₅₉H₂₉NO₁₀, respectively. The simulation results showed that the 3D structure of the 300 °C biochar with ?4 charges and the nonprotonated 3D structure of the 500 °C biochar were the most stable. Deprotonation reaction is an endothermic process.

     

Effect of <Emphasis Type="Italic">Eucalyptus</Emphasis> forests on understory vegetation and soil quality

Purpose

Eucalyptus forest plantations are normally devoid of understory vegetation that is often assumed to be associated with Eucalyptus allelopathic effects. The objective of this study was to determine the influence of high soil compaction and low soil moisture content on inhibition of the germination of understory seeds in Eucalyptus forests and thus would result in the scarcity of understory vegetation.

Materials and methods

The soil water content above the depth of 1 m of six major understory vegetation types was analyzed to determine if there was a correlation between soil water content and understory vegetation. The effects of soil treatment (soil-loosening vs. no soil-loosening) and water supply amount (2500, 2000, 1500, 1000, 500, 250, or 0 ml of water per day) on the seed germination rate of Stylosanthes sp. were explored using an artificial climate chamber experiment. Influence of soil source (five Eucalyptus forest soils vs. two non-Eucalyptus forest soils) and water supply (0, 50, 150, 200, or 400 ml of water every day) on the germination rate of five types of seed were assessed using a three-factor analysis of variance (ANOVA).

Results and discussion

Soil-loosening and water supply significantly (P?<?0.05) increased seed germination rate with the contribution rates of 26.14 and 42.93 %, respectively. Analysis of variance for three-factor experiments revealed a significant (P?<?0.05) effect of water supply and vegetation seed type on the germination rate of plant seeds. No significant effect of soil type was observed on germination rate, indicating that germination rate was not affected by soils in Eucalyptus forest.

Conclusions

The conservation of soil characteristics, such as water content and compaction, during the development of a Eucalyptus forest plantation may be an effective strategy for encouraging the growth of understory vegetation. This study highlights the importance that in dry areas or areas prone to long-term drought, it would be preferable to retain native vegetation.

     

Characterization of water binding and dehydration in gelatinized starch

Using near-infrared spectroscopy and thermogravimetry coupled with differential scanning calorimetry (TG-DSC), we investigated the characteristics of water in starch and the effects of the inner structure of starch on dehydration. The results directly show that the dehydration process is significantly more favorable in native starch than in gelatinized starch. When the starch was heated to 100 °C, the water retention in gelatinized starch was 22.35 per total water content, much greater than that in native starch (4.3%). The hydrogen bond network that changes from native starch to gelatinized starch was simultaneously explored, and the weaker hydrogen bonds were found to be predominant in the hydrogen bond network of gelatinized starch.     

离子色谱法测定土壤中氯离子的含量

为快速、准确地检测土壤中氯离子的含量,采用以水作为提取剂,水土比1:10(v/w),超声处理30min提取的方法,结合以氢氧化钾溶液为淋洗液,阴离子交换柱分离,电导检测器检测的离子色谱检测手段。结果表明,该方法能够达到快速、准确地检测土壤中氯离子含量的目的,该方法精密度及准确度实验结果表明其适用于各类型土壤中氯离子含量的测定。     

土地征收中农地市场价值的测算思路

对农地的市场价值进行合理评估是推进中国征地制度改革的关键问题之一。目前,国家在土地征收过程中,提倡划分区片、按价征地,要按农地的市场价值计算征地区片综合地价。针对于此,笔者在文章中提出合理确定征地区片综合地价的测算方法。通过对土地征收过程中政府与农民集体之间的权益进行综合分析,借鉴城市地价评估的方法,指出可应用收益还原法、假设开发法和社会价值量化法三种评估方法来测算农地市场价格,并具体分析了这三种方法的应用途径。     

中国森林生物量的空间分布及其影响因素

在参考前人大量研究结果基础上,探讨中国森林生物量的空间分布以及植被地域性、年均温、年降雨量和海拔对森林生物量空间分布的影响。结果表明：我国森林生物量存在明显的空间分布规律,其值从东到西逐渐降低,总体分布规律呈东北地区>西南地区>南方地区;地域性植被和非地域性植被的森林生物量均表现为暖温带<寒温带<温带<亚热带<热带林;不同林分类型的森林生物量表现为落叶阔叶林<针阔叶混交林<针叶林<常绿阔叶林<热带林的规律;年均温和年降雨量是影响森林生物量的主要因素,森林生物量基本随年均温、降雨量的升高而逐渐升高;不同海拔梯度对森林生物量有着明显的影响,随着海拔升高森林生物量基本呈逐渐降低的趋势。     

河南省中肥小麦新品种稳产性分析和品种评价

采用联合方差和回归分析方法对河南省5个中肥小麦品种8个试点的产量资料进行了分析,结果表明,豫麦十二号宜在亩产300公斤以上的环境条件下种植,而郑州853则宜在300公斤以下的产量水平环境条件下能够发挥较大的增产潜力。与其它参试品种相比,博农7023产量较低,故不宜再推广种植。本文还结合其它性状的考查,综合评阶了各品种的利用价值。