988 resultados para C5
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一种小晶粒含锆ZSM-5分子筛催化剂的百分重量组成为SiO2:Al2O3:NaO2:锆=70-95:1-4:1-2:0.05-3,平均晶粒度为0.2-0.5μm总酸量为0.8-1.1毫摩尔/克分子筛,其平均晶粒度为0.2-0.5μm。本发明具有由合成气经甲醇/二甲醚制汽油反应中,甲醇/二甲醚转化率100%,汽油馏分(C5↑[+])选择性高,且产物油品烯烃含量<10%,更具有环保性,且催化剂抗积碳性能强,单程寿命可达1000小时以上的。
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制备了以超细 Zr O2 为载体的 WO3/ Zr O2 、 SO42 - / Zr O2 、 Mo O3/ Zr O2 固体强酸催化剂 ,并用 XRD、 DTA-TG、 H2 - TPR、 NH3- TPD等方法表征了其晶型结构、表面状态和酸性 .结果表明 ,超细 Zr O2 及其催化剂均主要以 T-晶相存在 ,与通常以 Zr(OH) 4为载体制备的同类催化剂相比 ,Zr O2 中的 T-晶相所占比例虽有所下降 ,但具有更大的比表面积、酸强度和对金属氧化物的负载能力 ,且酸强度随焙烧温度升高而增强 ,表明其表面状态亦有较大变化 .研究了以超细 Zr O2 为载体的固体强酸催化剂上 ,异丁烷 -丁烯的烷基化反应 ,与通常以 Zr(OH) 4为载体制得的催化剂相比 ,其具有更好的烯烃转化率 ,在烷基化产物中 ,C5 ~ C7裂解产物较多 ,使 C80的选择性有所下降
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以环戊二烯与 1 2 钼硅杂多四丁基铵为原料 ,采用光化学法合成了一种新型电荷转移盐 (Bu4N) 4(C5 H6 ) [HSiMoVI11MoVO40 ]。用元素分析、IR、CV、固体漫反射电子光谱、ESR进行了表征。X 射线晶体结构测定其晶体属三斜晶系 ,空间群P1 ,晶胞参数a =1 4.347(3) ,b =1 4.42 3(3) ,c =2 7.1 5 8(5 ) ,α =96 .90 (3) ,β =1 0 4.1 8(3) ,γ =98.2 0 (3)° ,V =5 32 2 (2 ) 3,Z =2 ,Mr=2 85 5 .30 ,Dc=1 .782 g·cm-3,F(0 0 0 ) =2 86 0 ,R =0 .0 71 9,wR =0 .1 983。标题化合物由 1个环戊二烯、4个Bu4N+阳离子和 1个 [SiMoVI11MoVO40 ]4 -阴离子构成。
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探讨了茂金属催化剂 Cpt2 MCl2 ( Cpt=t Bu C5 H4,M=Ti,Zr,Hf)的合成以及用于聚合丁烯 -1的研究 ,研究了几种不同的茂金属催化剂和不同聚合条件下的催化行为 ,并通过 IR、1 H NMR、EI-MS、DSC、粘度法测分子量和正庚烷抽提等测试手段对催化剂和聚合物进行了表征 .结果表明 ,叔丁基取代的茂金属催化剂催化丁烯 -1聚合具有较高的催化活性 ,叔丁基的引入提高了聚合物的等规度和分子量
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本文用~(13)C NMR方法研究了水溶液中三价顺磁性稀土离子Ho~(3+)和Yb~(3+)与二肽甘氨酰替亮氨酸之间的相互作用。对稀土诱导位移中的接触位移和偶极位移进行了分离。实验表明,与羧基相连的碳核所受的接触作用很大,因此不能把镱诱导的位移直接用于肽的构象分析。在水溶液中,肽通过羧基与稀土离子配位,在弱酸性条件下肽键和氨基均不参与配位。根据结构因子确定了肽在溶液中的构象,结果表明,分子片段C1-C2-C5-C6,C2-N-C3-C4和C2-C5-C6-C8为反式,而C2-C5-C6-C7和C1-C2-N-C3成旁式。
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Thioester-containing proteins are a family of proteins characterized by the unique intrachain beta-cysteinyl-gamma-glutamyl thioester, which play important roles in innate immune responses. The cDNA of Zhikong scallop Chlamys farreri thioester-containing protein (designated as CfTEP) was cloned by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of CfTEP was of 4616 bp, consisting of a 5 '-terminal untranslated region (UTR) of 30 bp and a 3 ' UTR of 140 bp with a polyadenylation signal sequence AATAAA and a poly(A) tail. The CfTEP cDNA encoded a polypeptide of 1481 amino acids with the theoretical isoelectric point of 5.98 and the predicted molecular weight of 161.4 kDa. The deduced amino acid sequence of CfTEP contained the canonical thioester motif GCGEQ, nine potential N-glycosylation sites and a C-terminal distinctive cysteine signature. It also contained a presumed catalytic histidine and proteolytic cleavage sites that were similar to C3 molecules. The high similarity of CfTEP with the thioester-containing proteins in other organisms, such as the TEPs from insects, the complement component C3, C4, C5 and the protease inhibitor alpha(2)-macroglobulin indicated that CfTEP should be a member of TEP family. The phylogenetic analysis revealed that CfTEP was closely related to TEPs from mollusc, nematodes and insects, and they formed a separate branch apart from the branches of complements factors and alpha(2)-macroglobulins. The spatial expression of CfTEP transcripts in healthy and bacterial challenged scallops was examined by semi-quantitative RT-PCR. The CfTEP transcripts were mainly detected in the tissues of hepatopancreas and gonad, and remarkably up-regulated by Microbial challenge, which suggested that CfTEP was a constitutive and inducible acute-phase protein involved in immune defense. These results provided new insights into the role of CfTEP in scallop immune responses, as well as the evolutionary origin of this important, widespread and functionally diversified family of proteins. (c) 2007 Published by Elsevier Ltd.
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中华哲水蚤是黄、东海浮游动物关键种,连接初级生产与较高营养级,在海洋生态系统中占据核心地位。在以往研究基础上,依据2006年3月至2007年8月黄海9个航次、胶州湾11个航次现场调查数据以及大量室内实验数据,本文研究了中华哲水蚤的繁殖、种群补充以及油脂积累的季节变化,期望初步阐明中华哲水蚤在黄海的种群动态及驱动因素、并构建其生活史概念模型。 3、4月份,黄海与胶州湾中华哲水蚤的生殖腺普遍发育成熟、产卵率较高,中华哲水蚤种群进入繁殖、种群补充的活跃期,恰好可以利用此时较好的食物条件。5、6月份,中华哲水蚤在黄海近岸海区仍表现出较高的产卵率,而陆架海区的中华哲水蚤生殖腺成熟度、产卵率逐渐降低,种群逐渐表现出度夏特征—C5占优势、积累大量脂类。整个夏季,中华哲水蚤的繁殖率、种群补充率在整个黄海都较低,尤其在黄海冷水团区:中华哲水蚤生殖腺停滞于未成熟的GS1-GS2期,产卵率为零。10月,中华哲水蚤在冷水团边缘潮汐锋区的繁殖、种群补充活跃,或许可以解释秋、冬季近岸种群的恢复。11月之后,随着垂直混合的加强,黄海冷水团逐渐消失,此时陆架区的中华哲水蚤种群结束度夏过程,并以较低的繁殖率进行种群补充,直到次年3、4月份食物环境转好,中华哲水蚤种群出现新一轮繁殖、补充高峰。本文依据中华哲水蚤雌体密度、产卵率、孵化率等计算了中华哲水蚤的种群潜在补充率,我们发现,陆架区种群仅在3、4月份出现较强补充以及冬季的微弱补充,而近岸海区除夏季外,于各个季节均可进行比较活跃的种群补充,其中春季种群补充规模、强度最大;整体来看,春季是黄海中华哲水蚤种群补充的最重要时期。 本文详细研究了中华哲水蚤的繁殖与各种环境、雌体自身因素之间的关系:1、统计结果表明,中华哲水蚤的产卵率与海区食物条件(浮游植物生物量、纤毛虫丰度)之间具有紧密联系,而与油囊体积无关;在饥饿培养条件下,中华哲水蚤只能维持3-6天的产卵,而添加食物2-7天内,即可逐渐恢复产卵;体内积累油脂在饥饿过程中有所消耗,不过仍然不能阻止产卵率的下降;这些结果表明中华哲水蚤繁殖的能量所需主要来自于近期摄食,而体内储存脂类可能主要用于代谢所需,是应对不利条件的一种能量缓冲。2、统计分析表明:产卵率与雌体前体长间具有一定的正相关性,这可能由于体长较长的雌体往往具有较高的怀卵量;产卵率与温度之间没有显著的统计关系,温度可能通过调节中华哲水蚤的代谢率、体长等间接影响到产卵率。3、值得一提的是,本文发现中华哲水蚤的产卵率与其生殖腺成熟度之间具有非常紧密的统计关系,这为通过保存样品估算产卵率以及长期历史样品、数据间的比较提供了可能。 春季硅藻水华是黄海及其邻近海域的重要季节性特征。本文针对硅藻水华与中华哲水蚤繁殖的关系进行了多次现场研究,我们发现,硅藻水华因其发生海区、硅藻优势种类不同而对中华哲水蚤繁殖具有复杂多样的影响。2006年3月,胶州湾东部海区发生中肋骨条藻(Skeletonema costatum)水华,中华哲水蚤的产卵率显著增高,但其孵化率相对较低(50%左右);2007年2月,胶州湾东部发生环纹劳德藻(Landeria annulata)水华,中华哲水蚤卵的孵化率在各种处理下均接近100%;2006年4月,黄海东北部发生太平洋海链藻(Thalassiosira pacifica)水华,产卵率与孵化率均处于调查海区的中等水平;2007年4月,黄海中部海区发生中肋骨条藻水华,中华哲水蚤在此次调查海区平均产卵率高达27.8 卵/雌体/天,远远高于以往同时期的调查结果,孵化率、幼体存活率也普遍较高;此次硅藻水华对于黄海陆架区中华哲水蚤的种群补充具有积极的促进作用。综上,硅藻水华对中华哲水蚤繁殖的影响表现出种类、海区特异性,其具体机理仍需进一步研究。 本文研究了黄海中华哲水蚤C5期油脂积累的区域、季节变化,并探讨了油脂积累对中华哲水蚤的生理、生活史的可能作用。黄海近岸区的C5期油囊体积常年较小,而陆架区则表现出明显的季节差异。在陆架区,C5期是中华哲水蚤度夏种群的主要组成部分,其油囊体积与度夏过程有密切联系:最大油囊体积(可占前体部体积的30%以上)出现于度夏准备期(5、6月),随着度夏过程的进行,油囊体积因代谢而不断消耗,至12月时,油囊体积降低到与近岸种群无异。次年4月以后,油脂积累可能随食物条件转好而再次开始积累。我们认为黄海中华哲水蚤所积累油脂除了可以为休眠提供能量以克服较长时期食物缺乏之外,还可能是休眠的诱导因素,对其生活史具有重要意义。 黄海近岸海区与陆架海区在水团特征、中华哲水蚤种群丰度与结构、繁殖特征、种群补充、油脂储存策略等方面具有显著差异,因此,本文分别讨论了这两个区域中华哲水蚤的生活史。黄海陆架海区中华哲水蚤在全年共有4-5个世代:11月末,中华哲水蚤结束度夏过程,种群中占优势的C5期个体开始蜕皮为成体、逐渐成熟、繁殖,由此产下的子代可称之为G0,此世代在食物条件较差的冬季发育成熟后可以产下G1;G1于3月初发育成熟,恰逢春季较好的食物条件,于是在3月初-5月中旬很可能发育G2、G3两个世代;假若陆架区食物环境适宜,5月中旬后很可能产生新的世代—G4;G3与G4两个世代的混合种群共同进入度夏过程,期间,一小部分C5蜕皮为成体,大部分C5保持滞育状态;至12月冷水团消退后,G3、G4世代C5蜕皮、成熟,开始新的生活周期。中华哲水蚤生殖腺成熟度、油囊体积的季节变化与上述概念模型具有较好的对应关系,另外,这两个参数简单易用、对环境变化敏感,可以尝试应用于气候变化与桡足类关系等长期研究中。 以往的研究更多的关注于黄海陆架区的中华哲水蚤种群,对近岸种群的关注较少,本文初步探讨了近岸种群的种群补充、世代情况。相对于陆架区,黄海近岸区中华哲水蚤的生活史更为复杂,区域差异较大。近岸海区中华哲水蚤产卵率、种群周转率较高;同时,近岸海区是多种鱼类的产卵场、索饵场,该区域的各营养级间的能量流动对黄海海洋生态系统的结构功能至关重要。因此,在将来的研究中,近岸海区中华哲水蚤种群的生态学、生活史应该受到同样的重视。
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The vertical distribution and stage-specific abundance of Calanus sinicus were investigated on three key transects in the southern Yellow Sea and the northern East China Sea in August 1999. The results showed that in summer C. sinicus shrank its distribution area to the central cold (less than or equal to10degreesC) bottom water in the Yellow Sea, i.e. the Yellow Sea Cold Bottom Water, remaining in high abundance (345.7 ind m(-3)). In the northern East China Sea on a transect from the mouth of the Yangtze River to the Okinawa trench, only a few individuals appeared in the inner side and none had been found either in the upper layer or in the deep layer of the outer shelf area. The population of C. sinicus in YSCBW consisted of mainly adults (46.83%) and C5 (37.41%). C1-C4 only accounted for 15.76%. The low proportion of the earlier copepodite stages and the high female:male ratio (11.39) indicated that the reproduction of C. sinicus in YSCBW was at a very low level due to the low temperature and low food concentration. It is concluded that the dramatic decrease of C. sinicus population in the shelf area of China seas in summer is caused by the shrinkage of its distribution area and the YSCBW served as an oversummering site.
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简要介绍了物流的发展现状 ,详细描述了基于CAN总线的物流拣选系统的结构、供电方式和参数设定方法 ,并为系统硬件设计中的电源转换、总线驱动和地址译码等公共电路以及总线控制器、电子标签和指示灯控制器等主要设备提供了设计方案 ,为系统软件设计中的C5 1编译、通信协议、命令类型和程序控制规划等问题给出了相应的解决方法 ,还与进口同类产品的性能和价格进行了比较
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King, R. D. and Ouali, M. (2004) Poly-transformation. In proceedings of 5th International Conference on Intelligent Data Engineering and Automated Learning (IDEAL 2004). Springer LNCS 3177 p99-107
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Lactococcus lactis is used extensively world-wide for the production of fermented dairy products. Bacteriophages (phages) infecting L. lactis can result in slow or incomplete fermentations, or may even cause total fermentation failure. Therefore, bacteriophages disrupting L. lactis fermentation are of economic concern. This thesis employed a multifaceted approach to investigate various molecular aspects of phage-host interaction in L. lactis. The genome sequence of an Irish dairy starter strain, the prophage-cured L. lactis subsp. cremoris UC509.9, was studied. The 2,250,427 bp circular chromosome represents the smallest among its sequenced lactococcal equivalents. The genome displays clear genetic adaptation to the dairy niche in the form of extensive reductive evolution. Gene prediction identified 2066 protein-encoding genes, including 104 which showed significant homology to transposase-specifying genes. Over 9 % of the identified genes appear to be inactivated through stop codons or frame shift mutations. Many pseudogenes were found in genes that are assigned to carbohydrate and amino acid transport and metabolism orthologous groups, reflecting L. lactis UC509.9’s adaptation to the lactose and casein-rich dairy environment. Sequence analysis of the eight plasmids of L. lactis revealed extensive adaptation to the dairy environment. Key industrial phenotypes were mapped and novel lactococcal plasmid-associated genes highlighted. In addition to chromosomally-encoded bacteriophage resistance systems, six functional such systems were identified, including two abortive infection systems, AbiB and AbiD1, explaining the observed phage resistance of L. lactis UC509.9 Molecular analysis suggests that the constitutive expression of AbiB is not lethal to cells, suggesting the protein is expressed in an un/inactivated form. Analysis of 936 species phage sk1-escape mutants of AbiB revealed that all such mutants harbour mutations in orf6, which encodes the major capsid protein. Results suggest that the major capsid protein is required for activation of the AbiB system, although this requires furrther investigations. Temporal transcriptomes of L. lactis UC509.9 undergoing lytic infection with either one of two distinct bacteriophages, Tuc2009 and c2, was determined and compared to the transcriptome of uninfected UC509.9 cells. Whole genome microarrays performed at various time-points post-infection demonstrated a rather modest impact on host transcription. Alterations in the UC509.9 transcriptome during lytic infection appear phage-specific, with a relatively small number of differentially transcribed genes shared between infection with either Tuc2009 or c2. Transcriptional profiles of both bacteriophages during lytic infection was shown to generally correlate with previous studies and allowed the confirmation of previously predicted promoter sequences. Bioinformatic analysis of genomic regions encoding the presumed cell wall polysaccharide (CW PS) biosynthesis gene cluster of several strains of L. lactis was performed. Results demonstrate the presence of three dominant genetic types of this gene cluster, termed type A, B and C. These regions were used for the development of a multiplex PCR to identify CW PS genotype of various lactococcal strains. Analysis of 936 species phage receptor binding protein phylogeny (RBP) and CW PS genotype revealed an apparent correlation between RBP phylogeny and CW PS type, thereby providing a partial explanation for the observed narrow host range of 936 phages. Further analysis of the genetic locus encompassing the presumed CW PS biosynthesis operon of eight strains identified as belonging to the CW PS C (geno)type, revealed the presence of a variable region among the examined strains. The obtained comparative analysis allowed for the identification of five subgroups of the C type, named C1 to C5. We purified an acidic polysaccharide from the cell wall of L. lactis 3107 (C2 subtype) and confirmed that it is structurally different from the CW PS of the C1 subtype L. lactis MG1363. Combinations of genes from the variable region of C2 subtype were amplified from L. lactis 3107 and introduced into a mutant of the C1 subtype L. lactis NZ9000 (a direct derivative of MG1363) deficient in CW PS biosynthesis. The resulting recombinant mutant synthesized a CW PS with a composition characteristic for that of the C2 subtype L. lactis 3107 and not the wildtype C1 L. lactis NZ9000. The recombinant mutant exhibited a changed phage resistance/sensitivity profile consistent with that of L. lactis 3107, which unambiguously demonstrated that L. lactis 3107 CW PS is the host cell surface receptor of two bacteriophages belonging to the P335 species as well as phages that are member of the 936 species. The research presented in this thesis has significantly advanced our understanding of L. lactis bacteriophage-host interactions in several ways. Firstly, the examination of plasmidencoded bacteriophage resistance systems has allowed inferences to be made regarding the mode of action of AbiB, thereby providing a platform for further elucidation of the molecular trigger of this system. Secondly, the phage infection transcriptome data presented, in addition to previous work, has made L. lactis a model organism in terms of transcriptomic studies of bacteriophage-host interactions. And finally, the research described in this thesis has for the first time explicitly revealed the nature of a carbohydrate bacteriophage receptor in L. lactis, while also providing a logical explanation for the observed narrow host ranges exhibited by 936 and P335 phages. Future research in discerning the structures of other L. lactis CW PS, combined with the determination of the molecular interplay between receptor binding proteins of these phages and CW PS will allow an in depth understanding of the mechanism by which the most prevalent lactococcal phages identify and adsorb to their specific host.
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Simian-human immunodeficiency viruses (SHIVs) that mirror natural transmitted/founder (T/F) viruses in man are needed for evaluation of HIV-1 vaccine candidates in nonhuman primates. Currently available SHIVs contain HIV-1 env genes from chronically-infected individuals and do not reflect the characteristics of biologically relevant HIV-1 strains that mediate human transmission. We chose to develop clade C SHIVs, as clade C is the major infecting subtype of HIV-1 in the world. We constructed 10 clade C SHIVs expressing Env proteins from T/F viruses. Three of these ten clade C SHIVs (SHIV KB9 C3, SHIV KB9 C4 and SHIV KB9 C5) replicated in naïve rhesus monkeys. These three SHIVs are mucosally transmissible and are neutralized by sCD4 and several HIV-1 broadly neutralizing antibodies. However, like natural T/F viruses, they exhibit low Env reactivity and a Tier 2 neutralization sensitivity. Of note, none of the clade C T/F SHIVs elicited detectable autologous neutralizing antibodies in the infected monkeys, even though antibodies that neutralized a heterologous Tier 1 HIV-1 were generated. Challenge with these three new clade C SHIVs will provide biologically relevant tests for vaccine protection in rhesus macaques.
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BACKGROUND: Generation of potent anti-HIV antibody responses in mucosal compartments is a potential requirement of a transmission-blocking HIV vaccine. HIV-specific, functional antibody responses are present in breast milk, and these mucosal antibody responses may play a role in protection of the majority of HIV-exposed, breastfeeding infants. Therefore, characterization of HIV-specific antibodies produced by B cells in milk could guide the development of vaccines that elicit protective mucosal antibody responses. METHODS: We isolated B cells from colostrum of an HIV-infected lactating woman with a detectable neutralization response in milk and recombinantly produced and characterized the resulting HIV-1 Envelope (Env)-specific monoclonal antibodies (mAbs). RESULTS: The identified HIV-1 Env-specific colostrum mAbs, CH07 and CH08, represent two of the first mucosally-derived anti-HIV antibodies yet to be reported. Colostrum mAb CH07 is a highly-autoreactive, weakly-neutralizing gp140-specific mAb that binds to linear epitopes in the gp120 C5 region and gp41 fusion domain. In contrast, colostrum mAb CH08 is a nonpolyreactive CD4-inducible (CD4i) gp120-specific mAb with moderate breadth of neutralization. CONCLUSIONS: These novel HIV-neutralizing mAbs isolated from a mucosal compartment provide insight into the ability of mucosal B cell populations to produce functional anti-HIV antibodies that may contribute to protection against virus acquisition at mucosal surfaces.
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The X-ray crystal structures of two lamotrigine derivatives (I) 2-methyl, 3-amino, 5-imino-6-(2, 3-dichlorophenyl)-1,2,4-triazine, C10H9Cl2N5, as the hemi hydrate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine, C10H10Cl2N5, as the isethionate-water solvate, have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are monoclinic and centrosymmetric, with (I) in space group C2/c, and (II) in space group P2(1)/n. For (I) the unit cell dimensions are a = 19.5466(10), b = 7.5483(4), c = 15.7861(8) angstrom, beta = 91.458(3)degrees, volume = 2328.4(2) angstrom(3), Z = 8, density = 1.590 Mg/m(3); for (II). For (II) the unit cell dimensions are a = 6.0566(2), b = 11.0084(4) c = 23.9973(9) angstrom, beta = 92.587(3)degrees, volume = 1598.35(10) angstrom(3), Z = 4, density = 1.597 Mg/m(3). For (I) final R indices [I > 2sigma(I)] are R1 = 0.0356, wR2 = 0.0782 and R indices (all data) are R1 = 0.0424, wR2 = 0.0817. For (II) final R indices [I > 2sigma(I)] are R1 = 0.0380, wR2 = 0.0871 and R indices (all data) R1 = 0.0558, wR2 = 0.0949. Both structures have a molecule of water of crystallization and (II) also includes a solvated CH3SO3. Comparisons are made between the two structures. Structure (I) is very unusual in having a = NH group at position C5' on the triazine ring. No other examples of this particular substitution, which is usually -NH2, have been reported.