Comparison between mainstream (Capnostat 5) and a low-flow sidestream capnometer (Capnostream) in mechanically ventilated,sevoflurane-anesthetized rabbits using a Bain coaxial delivery system

ObjectiveTo evaluate agreement between end-tidal carbon dioxide (Pe′CO₂) and PaCO₂ with sidestream and mainstream capnometers in mechanically ventilated anesthetized rabbits, with two ventilatory strategies.Study designProspective experimental study.AnimalsA total of 10 New Zealand White rabbits weighing 3.6 ± 0.3 kg (mean ± standard deviation).MethodsRabbits anesthetized with sevoflurane were intubated with an uncuffed endotracheal tube (3.0 mm internal diameter) and adequate seal. For Pe′CO₂, the sidestream capnometer sampling adapter or the mainstream capnometer was placed between the endotracheal tube and Bain breathing system (1.5 L minute^–1 oxygen). PaCO₂ was obtained from arterial blood collected every 5 minutes. A time-cycled ventilator delivered an inspiratory time of 1 second and 12 or 20 breaths minute^–1. Peak inspiratory pressure was initially set to achieve Pe′CO₂ normocapnia of 35–45 mmHg (4.6–6.0 kPa). A total of five paired Pe′CO₂ and PaCO₂ measurements were obtained with each ventilation mode for each capnometer. Anesthetic episodes were separated by 7 days. Agreement was assessed using Bland-Altman analysis and linear mixed models; p < 0.05.ResultsThere were 90 and 83 pairs for the mainstream and sidestream capnometers, respectively. The mainstream capnometer underestimated PaCO₂ by 12.6 ± 2.9 mmHg (proportional bias 0.44 ± 0.06 mmHg per 1 mmHg PaCO₂ increase). With the sidestream capnometer, ventilation mode had a significant effect on Pe′CO₂. At 12 breaths minute^–1, Pe′CO₂ underestimated PaCO₂ by 23.9 ± 8.2 mmHg (proportional bias: 0.81 ± 0.18 mmHg per 1 mmHg PaCO₂ increase). At 20 breaths minute^–1, Pe′CO₂ underestimated PaCO₂ by 38.8 ± 5.0 mmHg (proportional bias 1.13 ± 0.10 mmHg per 1 mmHg PaCO₂ increase).Conclusions and clinical relevanceBoth capnometers underestimated PaCO₂. The sidestream capnometer underestimated PaCO₂ more than the mainstream capnometer, and was affected by ventilation mode.     

活性炭吸附汽油机冷起动HC排放的实验

为控制汽油机的冷起动HC排放，开发了一个活性炭吸附器，用于吸附车用汽油机冷起动阶段排放的HC。吸附材料采用煤质蜂窝状定型活性炭块，吸附器外表面用薄钢板焊接封装，整个吸附器串接在排气管上。进行汽油机冷起动排放实验，测量起动后200s内的HC排放量，实验结果表明，在冷却水温度为20U、40℃、60℃和85℃时，活性炭吸附器对HC的吸附率分别达到86．64％、70．34％、79．69％、77．45％。     

陕北农牧交错带牧草生产力分析

根据陕北农牧交错带的生态环境特点以及牧草生长发育过程对水热资源的要求和利用效率,运用迈阿密模型定量估算陕北农牧交错带七县区牧草自然生产力。并与牧草现实生产力进行比较。研究表明:陕北农牧交错带牧草现实生产力仅为自然生产力的30.80%。基本掌握了该区牧草生产力状况和特点,并据此提出了相应的开发战略和实施途径。     

CO2-O2混合喷吹对铁液中C、V元素氧化的影响

为了验证用CO2替代部分O2进行转炉氧化提钒的可行性,在实验室进行了CO2-O2混合喷吹提钒模拟实验。结果显示C的氧化量与C的氧化速率随CO2含量的增加而升高;V的氧化量随CO2含量的增加而降低,其中CO2含量为20%与纯O2对C、V的氧化量接近;纯O2喷吹时C的氧化量为34.56%,V的氧化量为96.85%;CO2含量为20%混合气体喷吹时C的氧化量为36.83%,V的氧化量为93.29%;以V的相对氧化量与C的相对氧化量的比值(ΔV/ΔC)来衡量提钒保碳能力,CO2含量为20%的最终ΔV/ΔC为5.96,CO2含量,40%、60%、80%的最终ΔV/ΔC均小于3.8;反应前期,V的氧化速率随CO2含量的增加而升高,反应后期V的氧化速率随CO2含量的增加而降低。     

The Application of Relevant Homology in the Unified Representation of Electromagnetic Potentials and Gauge Transformation

Electromagnetic potentials and gauge transformation are derived for non-cloSedexterior differential forms with the help of relevant homology.Since de Rham ccahomology is sure-ly a relavant homology. potentials for both closed and non-closed forms and the gauge transforma-tion ean be unified in terms of relavent homology.     

玉米人工合成群体产量相关性状选择潜势及杂种优势模式分析

采用NCⅡ遗传交配设计 ,以分属于不同杂种优势群的 6个自交系做测验种 ,与 6个合成群体组配成 36个组合。结果表明 :单株产量的GCA以LBM最高 ,其次为WBM ,从株型、穗型性状的SCA分析合成群体与自交系组成了 9个优良杂种优势模式。单株产量最高的组合为HZ85×WBM ,其均值为 10 8 75g。通过对优良杂优模式内的变异参数估计 ,在群体内有丰富的变异个体 ,具有很强的选择潜势。组合内个体产量分布以及出现的频率对选系和轮回选择具有明确的指导意义。人工合成群体具有丰富的遗传变异 ,分属于不同的杂种优势类群 ,具有多元种质的特性。作为选系和轮回选择群体 ,具有明显的选择潜势     

高氨氮厌氧消化液后处理技术研究

采用SBR-絮凝沉淀-Fenton氧化-活性炭吸附组合工艺对高氨氮厌氧消化液的后处理进行实验研究.结果表明,当进水COD浓度为4516 mg·L^-1时,SBR出水COD可降为1752 mg·L^-1,去除率达到61.2%;絮凝沉淀出水COD浓度为1189 mg·L^-1,去除率为32.1%;Fenton氧化和活性炭吸附出水COD浓度分别为452和216 mg·L^-1,去除率分别为61.7%和52.7%.当进水NH3-N浓度2162 mg·L^-1时,SBR出水NH3-N浓度降至13.8 mg·L^-1,去除率为99.4%,NH3-N主要在该段去除.整个组合工艺对COD和NH3-N的去除率分别达到95.2%和99.9%,达到了很好的有机物和氨氮去除效果,在技术上是可行的.     

Effect of soil matric potential on tomato yield and water use under drip irrigation condition

Field experiment was carried out to investigate the effect of soil matric potential (SMP) on tomato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under drip irrigation condition in North China Plain. The experiment included five treatments, which controlled SMP at 0.2 m depth immediately under drip emitter higher than −10 (S1), −20 (S2), −30 (S3), −40 (S4) and −50 kPa (S5), respectively, after tomato plant establishment. The results showed that different SMP affected irrigation amount and tomato ET. Irrigation amount decreased from 185 mm (S1) to 83.6 mm (S5) in 2004, and from 165 mm (S1) to 109 mm (S5) in 2005, respectively. The ET decreased from 270 mm (S1) to 202 mm (S5) in both years. However, it was found that SMP did not affect the tomato yield significantly, for the range of SMP investigated. Both WUE and IWUE increased as SMP decreased. The maximum WUE (253 and 217 kg/ha mm) and IWUE (620 and 406 kg/ha mm) were for S5 in 2 years, whereas the minimum WUE (178 and 155 kg/ha mm) and IWUE 261 and 259 kg/ha mm) were for S1 in 2004 and 2005. Based on the above results, therefore, it is recommended that if the tomatoes are well irrigated (SMP is higher than −20 kPa) during establishment, controlling SMP higher than −50 kPa at 0.2 m depth immediately under drip emitter can be used as an indicator for drip irrigation scheduling during following period of tomato growth in North China Plain.     

Irrigation scheduling in a mature peach orchard using tensiometers and dendrometers

Three trickle irrigation schedules, two of which were scheduled according to soil water potential ( soil) (tensiometer method) and daily stem contraction (DSC) (dendrometer method) respectively and the other one was a schedule of restricted water supply, were applied to a mature peach orchard.The annual water application based on soil was greater than that based on DSC. However, tree growth, fruit size and leaf water potential (leaf) on the trees in the dendrometer scheduling plot did not differ from those in the tensiometer scheduling plot while the premature fruit drop and fruit bud initiation were greatly different. The restricted water supply treatment limited significantly both tree and fruit growth. In addition, the lower leaf was observed on the trees in this plot.Further study shows that use of the dendrometer method for scheduling irrigation satisfies the water needs of the plant and that the tensiometer method is less accurate.Abbreviations leaf leaf water potential - soil soil water potential - DSC daily stem contraction - LVDT linear variable displacement transducer - PET potential evapotranspiration