助力火箭，推动梦想——神秘的助推剂

生存在古丝绸之路上河西走廊的朱雀家族成立了蓝箭基地,一直在探索环保、经济和安全的助推剂。小朱雀来参观,了解了多种液体推进剂,有推力巨大但容易积碳的液氧煤油、环保但耗能的液氧液氢、稳定但有毒性的偏二甲肼和四氧化二氮,最后他们了解到由蓝箭基地发射的朱雀二号运载火箭是全球首枚以液氧甲烷为推进剂的火箭。甲烷有丰富的储量、温和的储存条件和运输安全性、燃烧充分而且产物无污染,在未来有更广阔的用途。     

液体推进剂偏二甲肼自动电位滴定分析方法的建立

设计了Metrohm809型自动电位滴定仪分析液体推进剂偏二甲肼的应用程序,解决了程序设计中滴定模式和终点确定方式选择、滴定速度确定等关键性技术问题,考察了环境温度对分析结果的影响,确定了最佳条件,实现了液体推进剂偏二甲肼的自动电位滴定分析。重复性试验和准确度试验表明,自动电位滴定法分析偏二甲肼具有准确度高、精密度好等优点,测量结果完全符合GJB753-89的要求：     

氟化学及其工艺的最新进展

氟应用于火箭技术中的优点一枚大火箭主要是一个或一组飞行的化学品储箱。在这些储箱中化学反应势能的释放,是通过构造精密的泵系统或压力传导系统对流向液体火箭发动机的推进剂流量加以控制,或用化学方法控制固体推进剂颗粒的燃烧速度。一枚大火箭的起飞重量主要是化学推进剂的重量;然而火箭的成本则主要在于它的桔构,飞行操作部分和它的导航及所携带的设备。因此,增加推进剂系统的蕴藏能量将大大地影响火箭的总成本。     

胶体推进剂——胶体化学在航天技术中的应用

推进剂是能使推进装置产生推动力的物质。常用的推进剂有化学推进剂,核能推进剂,电能推进剂和太阳能推进剂。它们分别利用化学能,核能,电能或太阳能加热、加速工质(液体H2),使其高速排出,产生使飞行器上天的推动力。化学推进剂是为火箭发动机提供能源和工质的化学制剂,通常含可     

偏二甲肼有机凝胶液滴蒸发燃烧模型展望

有机凝胶推进剂兼具有固体和液体推进剂的优点, 但其液滴在着火燃烧过程出现了剧烈的膨胀-爆裂及火焰扰动现象, 明显不同于常规液体液滴准稳态蒸发燃烧现象, 影响了凝胶液体火箭发动机喷雾燃烧流场及其优化设计工作.根据偏二甲肼(UDMH)有机凝胶液滴着火燃烧过程的内部非稳态蒸发特性及其微观分子结构, 提出了非稳态多组分蒸发模型、界面追踪多相流蒸发模型、离散元多相流蒸发模型三种有机凝胶液滴液相蒸发模型, 重点发展并实现了其中的非稳态多组分蒸发模型, 详细分析了后两种多相流蒸发模型所需的技术储备. 然后针对静止及对流气相环境下的UDMH有机凝胶液滴, 提出了分别采用有限速率化学反应模型、相容性层流火焰面模型解决其气相混合燃烧问题, 并详细分析了其中的刚性化学反应源项处理及火焰面方程求解所面临的困难及其解决措施.     

恒电流动态库仑法检测空气中偏二甲肼

偏二甲肼[(CH_3)_2NNH_2](UDMH)是液体火箭的主要推进剂,具有中等偏高毒性,极易挥发.空气中最大允许浓度为0.5ml/m~3.因此,研制检测空气中微量UDMH的装置.对于预防其中毒,具有十分重要的意义.空气中UDMH的测定方法主要有:固体吸附/分光光度法;固体吸附/气相色谱法.这两种方法均有测量范围大、下限低、测量准确等优点,但操作复杂、仪器条件要求高,且不能连续测定.本文采用库仑滴定法测定空气中的UDMH,依据法拉第电解定律,研究空气中UDMH与库仑池中电解液进行电化学反应,测量其在反应过程中产生的电流值,得到空气中UDMH浓度与响应电流的关系,从而求出UDMH气体的浓度.     

新型水红外分析仪的研制

研制测定液体推进剂四氧化二氮中相当水含量的新型水红外分析仪。基于近红外光谱法,依据朗伯–比耳定律,设计仪器组成单元,采用单光束测量方式,光路调节和数据处理自动完成,单个样品测量时间只需20 s。利用四氧化二氮相当水含量滤光片标准物质对设计仪器的性能参数进行测试,仪器测量范围为0~0.400%,测量重复性不大于0.000 7%,稳定性不大于0.000 9%,相当水含量示值误差不大于0.001 6%。新型水红外分析仪测试过程方便快捷,结果准确可靠,满足相关实验室和火箭发射现场的测试需求。     

Cr_2O_3/硝化棉的相容性及热分解机理研究

正硝化棉(NC)是固体推进剂中常见的含能组分,广泛应用于火炸药、爆炸胶、火箭推进剂中~(1–3),其分解特性与固体推进剂的燃烧性能密切相关~4。近年来,纳米金属氧化物作为燃烧催化剂对含能材料热分解过程的催化作用受到广泛关注~(5–7)。研     

煤油残留量的标记色谱法分析

煤油无法用光谱法测定其总含量,用其他方法测定也有困难。煤油用途广泛。在航空航天领域用煤油作火箭推进剂,具有成本低、污染小等优点。其发动机的工作过程是：先由供氧泵将液态氧送入燃气发生器,再根据所需产生的能量供给相应量的煤油。因此燃烧器煤油的残留量直接影响下次的使用性能,残留量过高还会引起爆炸。为此本文设计了一种标记色谱法,以测定液氧／煤油补燃循环液体火箭发动机“试完车”、经清洗后煤油的残留量。     

中国化学会第21届全国高中学生化学竞赛(决赛)理论试题

第1题 叠氮化合物不仅是重要的化工原料,也是良好的炸药和火箭推进剂,在国防和工业生产中有着广泛的应用.     

偏二甲肼纯度分析方法的改进

采用毛细管气相色谱内标法代替标准工作曲线法测定偏二甲肼纯度(UDMH),内标法的使用避免了微量进样不准确的缺陷.结果显示,该方法线性范围宽,偏二甲肼的标准曲线相关系数为0.9959,样品加标回收率98.39%,样品的测定标准偏差为0.0015,方法的准确度高、重现性好.     

Preparation and Deprotection of Aldehyde Dimethylhydrazones

Aldehydes were conveniently protected as dimethylhydrazones by stirring a mixture of the aldehyde, N,N‐dimethylhydrazine, anhydrous magnesium sulfate, and dichloromethane at room temperature. Azeotropic removal of water, formed during the course of the reaction, was not required because anhydrous magnesium sulfate functions as a water scavenger. Deprotection of aldehyde dimethylhydrazones was accomplished by stirring a mixture of the aldehyde dimethylhydrazone and aqueous glyoxylic acid at room temperature. The reaction time for the preparation and deprotection of aldehyde dimethylhydrazones varied with the structure of the aldehyde.     

Transformations of asymmetric dimethylhydrazine in soils

High-performance liquid chromatography and mass spectrometry were used to find that the decomposition of asymmetric dimethylhydrazine (I) in soils occurred with the formation of dimethylamine, formaldehyde dimethylhydrazone, methylhydrazine, trimethylhydrazine, N-nitrosodimethylamine, 1-methyl-1,2,4-triazole, formic acid dimethylhydrazide, 1,5,5-trimethylformazane, 1-methyl-1,6-dihydro-1,2,4,5-tetrazine, N,N-dimethylaminoguanidine, and several other products. High-reliability structure identification was achieved using independent methods, including gas chromatography-mass spectrometry, ¹H and ¹³C NMR, and UV spectroscopy, and by measuring retention times and spectral characteristics after the counter-synthesis of the suggested structures. The products of the decomposition of I potentially capable of forming initial I and characterized by high migration mobility in soils were identified.     

Analysis of formaldehyde formation in wastewater using on-fiber derivatization-solid-phase microextraction-gas chromatography-mass spectrometry

A method has been developed for the quantification of the formation of formaldehyde during the advanced oxidation treatment (AOT) of wastewater destined for reuse. This method uses solid-phase microextraction (SPME) with on-fiber derivatization followed by gas chromatography-mass spectrometry (GC-MS) analysis. Based on calculated method detection limits (MDL) and ambient background levels, the method reporting (MRL) limit for formaldehyde was set at 10 microg/L. Precision for formaldehyde using this technique resulted in 23% relative standard deviation (RSD), while the internal standard, acetone-d(6), was only 6%. This method was used to evaluate the formation of formaldehyde in bench scale UV-AOT experiments using natural organic matter (NOM) fortified reagent water and tertiary treated wastewater effluent. Results suggest that the formation of formaldehyde increases in both the reagent water and wastewater matrices with increasing UV exposure and hydrogen peroxide concentrations, with overall higher concentrations of formaldehyde in the wastewater samples. No appreciable amount of formaldehyde formation was observed when UV was applied in the absence of hydrogen peroxide in both matrices tested.     

Gene analysis of multiple oral bacteria by the polymerase chain reaction coupled with capillary polymer electrophoresis

Capillary polymer electrophoresis is identified as a promising technology for the analysis of DNA from bacteria, virus and cell samples. In this paper, we propose an innovative capillary polymer electrophoresis protocol for the quantification of polymerase chain reaction products. The internal standard method was modified and applied to capillary polymer electrophoresis. The precision of our modified internal standard protocol was evaluated by measuring the relative standard deviation of intermediate capillary polymer electrophoresis experiments. Results showed that the relative standard deviation was reduced from 12.4–15.1 to 0.6–2.3%. Linear regression tests were also implemented to validate our protocol. The modified internal standard method showed good linearity and robust properties. Finally, the ease of our method was illustrated by analyzing a real clinical oral sample using a one‐run capillary polymer electrophoresis experiment.     

碱蒸馏/超声波衍生化-气相色谱-质谱法测定土壤中的偏二甲肼

建立了碱蒸馏/超声波衍生化预处理的气相色谱-质谱法测定土壤中偏二甲肼的分析方法。通过碱蒸馏预处理方法,以水杨醛为衍生化试剂,采用超声波加速衍生化反应,在选择离子检测( SIM)模式下进行定量分析,衍生化产物的特征离子为m/z 164。考察了碱蒸馏、超声波衍生化条件的影响,并对衍生化条件进行优化,方法的线性范围在0.4~30 mg/L之间,方法检出限为0.0078 mg/kg。以此方法测定已知浓度的土壤样品,目标化合物的含量在10~100 mg/kg之间,回收率在76％~108％之间,相对标准偏差在12％~19％之间。与分光光度法、索氏提取/超声波衍生化-气相色谱-质谱法相比较,本方法检出限显著优于二者。     

Accurate analysis of trace earthy-musty odorants in water by headspace solid phase microextraction gas chromatography-mass spectrometry

A simple and sensitive method was developed for the simultaneous separation and determination of trace earthy-musty compounds including geosmin, 2-methylisoborneol, 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,3,4-trichloroanisole, 2,4,6-trichloroanisole, and 2,3,6-trichloroanisole in water samples. This method combined headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry and used naphthalene-d(8) as internal standard. A divinylbenzene/carboxen/polydimethylsiloxane fiber exposing at 90°C for 30 min provided effective sample enrichment in HS-SPME. These compounds were separated by a DB-1701MS capillary column and detected in selected ion monitoring mode within 12 min. The method showed a good linearity from 1 to 100 ng L(-1) and detection limits within (0.25-0.61 ng L(-1)) for all compounds. Using naphthalene-d(8) as the internal standard, the intra-day relative standard deviation (RSD) was within (2.6-3.4%), while the inter-day RSD was (3.5-4.9%). Good recoveries were obtained for tap water (80.5-90.6%), river water (81.5-92.4%), and lake water (83.5-95.2%) spiked at 10 ng L(-1). Compared with other methods using HS-SPME for determination of odor compounds in water samples, this present method had more analytes, better precision, and recovery. This method was successfully applied for analysis of earthy-musty odors in water samples from different sources.     

气相色谱-质谱法测定水中痕量的四乙基铅

建立了气相色谱-质谱(GC-MS)测定水中痕量四乙基铅的分析方法。用正己烷萃取水样中的四乙基铅,萃取液浓缩后加入同位素内标萘-d8,采用GC-MS选择离子方式(SIM)进行检测,在200 mL水样中四乙基铅的检出限可达0.04 μg/L;添加回收率为92.2%～103%,准确度好;平行5次测定的相对标准差为4.4%～13.3%。结果表明: 方法简便、快速、准确、实用,可用于水中痕量四乙基铅的测定。     

高效毛细管电泳测定虎耳草属植物中虎耳草素含量

以苯乙胺为内标，建立了高效毛细管电泳法(HPCE)测定虎耳草属植物中虎耳草素含量的方法．讨论了缓冲溶液体系、pH值及缓冲液浓度对分离的影响．结果表明，以10mmol／L硼砂-盐酸缓冲液(pH9．00)为分离介质，虎耳草素标准品与内标实现基线分离，且实验结果线性关系良好(r=0．9989)，日内和日间相对标准偏差分别为1．7％和4．6％．