Determination of free fatty acids in soil and bryophyte plants by precolumn derivatization via HPLC with fluorescence detection and tandem mass spectrometry (HPLC-MS/MS)

A sensitive method for the determination of 30 kinds of free fatty acids (FFAs, C-1-C-30) with 1-[2-(p-toluenesulfonate)-ethyl]-2-phenylimidazole-[4,5-f] 9,10-phenan- threne (TSPP) as labeling reagent and using high performance liquid chromatography with fluorescence detection and identification by online postcolumn mass spectrometry with atmospheric pressure chemical ionization (APCI) source in positive-ion mode (HPLC/MS/APCI) has been developed. TSPP could easily and quickly label FFAs in the presence of K2CO3 catalyst at 90 degrees C for 30 min in N,N-dimethylformamide (DMF) solvent, and maximal labeling yields close to 100% were observed with a 5-fold excess of molar reagent. Derivatives were stable enough to be efficiently analyzed by high performance liquid chromatography. TSPP was introduced into fatty acid molecules and effectively augmented MS ionization of fatty acid derivatives and led to regular MS and MS/MS information. The collision induced cleavage of protonated molecular ions formed specific fragment ions at m/z [MH](+)(molecular ion), m/z [M'+CH2CH2](+)(M' was molecular mass of the corresponding FFA) and m/z 295.0 (the, mass of protonated molecular core structure of TSPP). Fatty acid derivatives were separated on a reversed-phase Eclipse XDB-C-8 column (4.6 x 150 mm, 5 mu m, Agilent) with a good baseline resolution in combination with a gradient elution. Linear ranges of 30 FFAs are 2.441 x 10(-3) to 20 mu mol/L, detection limits are 3.24 similar to 36.97 fmol (injection volume 10 mu L, at a signal-to-noise ratio of 3, S/N 3:1). The mean interday precision ranged from 93.4 to 106.2% with the largest mean coefficients of variation (R.S.D.) < 7,5%. The mean intraday precision for all standards was < 6.4% of the expected concentration. Excellent linear responses were observed with correlation coefficients of > 0.9991. Good compositional data could be obtained from the analysis of extracted fatty acids from as little as 200 mg of bryophyte plant samples.Therefore, the facile TSPP derivatization coupled with HPLC/MS/APCI analysis allowed the development of a highly sensitive method for the quantitation of trace levels of short and long chain fatty acids from biological and natural environmental samples.

Distribution and species diversity of plant communities along transect on the Northeastern Tibetan plateau

The distribution and species diversity of plant communities along a 600 km transect through the northeastern Tibetan Plateau (32 degrees 42'-35 degrees 07' N, 101 degrees 02'-97 degrees 38' E) with altitudes from 3255 to 4460 m are described. The transect started from the Youyi Bridge of Banma through Dari, Maqin and Maduo to Zaling Lake. The data from 47 plots along the transect are summarized and analyzed. The mean annual temperature, the mean annual rainfall and the length of growing season decreases from 2.6 to -4.5 degrees C, from 767.2 to 240.1 mm, from 210 to 140 days, respectively, along the transect from the southeastern Banma to northwestern Zaling Lake. The number of vascular plant species recorded in 47 plots is 242 including 2 tree, 34 shrub, 206 herb species. Main vegetation types on the transect from southeast to northwest are: Sabina convallium forest, Picea likiangensis forest, Pyracantha fortuneana + Spiraea alpina shrub, Hippophae neurocarpu shrub, Sibiraea angustata + Polygonum viviparum shrub, Stellera chamaejasme herb meadow, Potentilla fruticosa + Salix obscura + Carex sp. Shrub, Kobresia capillifolia meadow, P. froticosa + Kobresia humilis shrub, Caragana jubata + S. obscura shrub, Kobresia tibetica meadow, Kobresia pygmaea meadow, K. pygmaea + Stipa purpurea steppe meadow, Stipa purpurea steppe. Plant richness and diversity index all showed a decreasing trend with increasing of elevation along transect from southeast to northwest. Detailed information on altitudinal ranges and distribution of the alpine vegetation, vascular flora and environments over the alpine zone at northeastern Tibetan Plateau provides baseline records relevant to future assessment of probable effects of global climate changes.

单元重构问题探讨

在 CIMS 环境下,采用虚拟单元技术可以解决使用成组单元的结构中出现的过量跨单元加工和加工负荷不平衡问题.本文对实现虚拟单元的关键技术——单元重构的可行性进行了分析,对单元重构的两个主要过程,即任务的时间分解过程和任务的空间分解过程进行了详细的讨论,并对所涉及到的时间划分、计划调度、工件、机器成组等问题给出了相应的策略和算法.从而证明了在 CIMS 环境下实现虚拟单元的可行性.

一个先进的工业机器人计算机控制系统——ARCS

随着工业机器人及其应用的不断发展,要求一个强有力的计算机系统来控制它的工作,并具有灵活、方便的机器人编程语言.本文系统地介绍了我们自行设计并实现的一个先进的机器人控制系统——ARCS.该系统主要包括两部分:(1)一个实时多任务的机器人控制软件SVAL系统,该系统支持一种通用性较强的机器人编程语言——SVAL语言.(2)一个支持该软件系统工作的、具有开放式结构的硬件环境.ARCS系统具有良好的实时性、可扩展性及基于外部传感器信号进行控制的能力.由于该系统的开放式结构.使其根据不同要求可方便地增删其功能,并可控制不同类型的机器人.我们已成功地实现对PUMA760机器人的控制,并在其上引入了力觉与接近觉的传感器,采样时间可缩短到16ms.一年多的运行结果证明,该系统稳定可靠,性能良好,现在正向产品转化.

贵州红枫湖水体溶解有机质的剖面特征和季节变化

溶解有机氮(dissolved organic nitrogen , DON) 与溶解有机碳(dissolved organic carbon , DOC) 相结合在湖泊水体溶解有机质(dissolved organic matter , DOM) 的研究中少有报道. 本研究对贵州喀斯特地区高原性湖泊-红枫湖水体DOC 和DON 的含量进行了近2a 的测定,研究了DOM 的剖面特征和季节变化,并探讨了DOM 垂向分布和季节变化的影响因素. 结果表明,红枫湖DOC 的浓度范围为1160～3108 mg·L - 1 ,DON 的浓度范围为0110～0137 mg·L - 1 . 在湖水混合期表层和底层的DOC和DON 的浓度基本一致,在湖水分层期DOC 和DON 浓度表现出从表层往底层减小的趋势. 表层水体(0～2m 或3m) DOC 的浓度在春末夏初或夏季达到最大,DON 的浓度在春末夏初稍高于其它月份. 结合叶绿素和降雨的数据分析认为,藻类活动和陆源输入直接导致了表层水体DOM 的季节变化模式. DOM 的C/ N 在一般情况下向下增大,但在夏季南湖的垂向水柱上,DOC 和DON 的浓度在12m 以下增大,C/ N 从12m 的1811 下降为14m 的1419 ,并向下持续减小,这很有可能是颗粒态有机质发生降解释放出C/ N 较低的DOM ,成为水体内DOM 的一个内源.

现代分析技术在土壤腐殖质研究中的应用

土壤腐殖质的研究已成为土壤学、环境化学和地球化学等的热点方向之一。应用核磁共振兴谱（NMR）、红外光谱（IR）、荧光光谱（FS）、电子自旋共振谱（ESR）等现代分析技术，对在土壤腐殖质组成和结构研究中取得的主要成果进行了综述。

稳定碳同位素示踪农林生态转换系统中土壤有机质的含量变化

为了观察生态系统的转变对土壤有机质的影响，在贵州茂兰喀斯特原始森林保护区内农林生态系统发生转变的地域，分析了土壤有机质含量和土壤有机质的δ13C值.森林点土壤有机碳含量普遍较高于农田点，表明,毁林造田加速了土壤有机质的降解，使土壤有机质总量减少；对比森林点与农田点的δ13C值，计算表明，毁林造田同时也降低了土壤有机质中活性大的组分的比例，使土壤肥力下降.