Jasmonic acid changes the composition of essential oil isolated from narrow-leaved lavender propagated in in vitro cultures

The aim of the present study was to determine the effect of jasmonic acid added to the culture medium on composition of Lavandula angustifolia essential oils. The chemical composition was determined by gas chromatography coupled to mass detector (GC/MS). The experiment was conducted with the use of MS medium supplemented with increasing concentration of JA (0.2, 0.5, 1, 1.5 mg?dm^?3). It was found that the analysed essential oils varied in terms of chemical composition depending on the content of JA in the medium. All obtained essential oils were characterised by a high content of σ-cadinene (17.06–29.64%), borneol (6.66–17.47%), caryophyllene oxide (8.30–14.01%), τ-cadinol (4.87–9.16%), beta-caryophyllene (3.54–6.57%), 1.8-cineole (1.94–5.87%), β-pinene (1.48–3.05%), geranyl acetate (0.56–2.14%) and myrtenal (0.65–2.14%).     

A new amino amidine derivative from the wood-decaying fungus Xylaria cf. cubensis SWUF08-86

The secondary metabolites of Xylaria cf. cubensis SWUF08-86 fungus were investigated, and the chromatographic separation of the crude extracts yielded seventeen compounds. The structure elucidation by spectroscopic analysis including 1D and 2D NMR and the comparison of these data with literature, along with HREIMS spectrometry, revealed one new amino amidine derivative (1), together with five known simple cyclic dipeptide analogs, diketopiperazines (2–6) and eleven other known compounds, including one hemi-cycline (10), three aromatic derivatives (11–13), one sesquiterpene (14) and three sterols (15–17). The isolated compounds were screened for anticancer and anti-pathogenic bacterial and fungal activities. Based on this work, Xylaria cf. cubensis SWUF08-86 has proven to be a diverse secondary metabolites producer.     

A novel phenylspirodrimane dimer from cultures of the fungus Stachybotrys chartarum

Stachartone A (1), a novel phenylspirodrimane dimer, was isolated from cultures of the tin mine tailings-associated fungus Stachybotrys chartarum. Its structure was elucidated by means of spectroscopic methods. At the same time, compound (1) was tested for its cytotoxicity against five human cancer cell lines.     

化学模拟在反应堆水化学课程中的应用

高温高压化学反应对反应堆设备的可靠性、反应堆性能的控制、核电站运行的安全持久性等具有重要影响,但相关实验难以在高校教学中开展。借助PHREEQC程序及最新热力学数据,建立了反应堆一回路硼酸-氢氧化锂添加配比、腐蚀沉淀物产生及二回路pH控制方案的化学反应模型。运用化学模拟来教学,促进了学生对所学知识的理解与掌握,丰富了现代教学方法。相关模型对核电企业的培训也具有一定参考价值。     

四个Cd(Ⅱ)配位聚合物:辅助配体对晶体结构以及荧光性能的影响

采用溶剂热的方法,将配位模式丰富的多羧酸有机配体5-(2-硝基-4-羧基苯氧基)-间苯二甲酸(H3ncpoi)与Cd~(2+)离子以及不同的辅助配体原位组装而成4个新的配位聚合物晶体:[Cd(Hncpoi)(2,2′-bpy)(H2O)]n(1),{[Cd2(Hncpoi)2(bpyp)(H2O)4]·3H2O}n(2),{[Cd2(Hncpoi)2(azpy)(H2O)2]·2H2O}n(3),{[Cd2(Hncpoi)2(dpe)(H2O)2]·2H2O}n(4),其中H3ncpoi为5-(2-硝基-4-羧基苯氧基)-间苯二甲酸,2,2′-bpy为2,2′-联吡啶,bpyp为1,4-二-吡啶基-4-亚甲基-哌嗪,azpy为4,4′-偶氮吡啶,dpe为1,2-二-(4-吡啶基)乙烯。对4个配合物进行了X射线单晶衍射、粉末衍射,元素分析、热重、荧光光谱等表征。X射线单晶结构分析表明,配合物1,2具有一维链状结构,而配合物3,4则具有二维(4,4)格子层状结构,一维链和二维层之间通过分子间作用力连接成三维超分子结构。进一步研究表明,辅助配体的构型、配位方式等对晶体结构具有决定性作用。与此同时,对几个配合物的荧光光谱进行分析,发现不同的辅助配体对配合物的荧光性能有着显著的影响。     

Structure and Dynamics in the Nucleosome Revealed by Solid‐State NMR

Eukaryotic chromatin structure and dynamics play key roles in genomic regulation. In the current study, the secondary structure and intramolecular dynamics of human histone H4 (hH4) in the nucleosome core particle (NCP) and in a nucleosome array are determined by solid‐state NMR (SSNMR). Secondary structure elements are successfully localized in the hH4 in the NCP precipitated with Mg²⁺. In particular, dynamics on nanosecond to microsecond and microsecond to millisecond timescales are elucidated, revealing diverse internal motions in the hH4 protein. Relatively higher flexibility is observed for residues participating in the regulation of chromatin mobility and DNA accessibility. Furthermore, our study reveals that hH4 in the nucleosome array adopts the same structure and show similar internal dynamics as that in the NCP assembly while exhibiting relatively restricted motions in several regions consisting of residues in the N‐terminus, Loop 1, and the α3 helix region.     

混合碱处理制备微介孔催化剂及其噻吩烷基化催化性能

以SiO_2/Al2O3物质的量比为50的H-ZSM-5分子筛为母体,分别采用Na_2CO_3溶液处理后加入TPAOH溶液进行二次晶化法以及Na_2CO_3/TPAOH混合溶液同时处理法,制备了微孔-介孔多级孔HZSM-5催化剂,对其噻吩烷基化反应催化性能进行了研究。结果表明,采用4 mol/L的Na_2CO_3溶液处理后的催化剂在TPAOH溶液中发生了二次晶化;当TPAOH溶液浓度为0.3 mol/L、晶化温度为170℃、晶化时间为24 h时,得到的HZ(CO_2-3-TPA+,0.3-24-170)催化剂具有适宜的孔径和酸性,其噻吩烷基化转化率最高(99.1%)。而Na_2CO_3/TPAOH同时处理HZSM-5分子筛所得的催化剂,由于生成大量SiO_2堵塞了孔道,覆盖了催化剂表面,降低了催化剂的平均孔径和酸性,不适合噻吩烷基化反应。     

Continuous spin models on annealed generalized random graphs

We study Gibbs distributions of spins taking values in a general compact Polish space, interacting via a pair potential along the edges of a generalized random graph with a given asymptotic weight distribution $P$, obtained by annealing over the random graph distribution.First we prove a variational formula for the corresponding annealed pressure and provide criteria for absence of phase transitions in the general case.We furthermore study classes of models with second order phase transitions which include rotation-invariant models on spheres and models on intervals, and classify their critical exponents. We find critical exponents which are modified relative to the corresponding mean-field values when $P$ becomes too heavy-tailed, in which case they move continuously with the tail-exponent of $P$. For large classes of models they are the same as for the Ising model treated in Dommers et al. (2016). On the other hand, we provide conditions under which the model is in a different universality class, and construct an explicit example of such a model on the interval.     

On exceptional groups of order p5

A finite group G is exceptional if it has a quotient Q whose minimal faithful permutation degree is greater than that of G. We say that Q is a distinguished quotient.The smallest examples of exceptional p-groups have order $p^5$. For an odd prime p, we classify all pairs $(G,Q)$ where G has order $p^5$ and Q is a distinguished quotient. (The case $p=2$ has already been treated by Easdown and Praeger.) We establish the striking asymptotic result that as p increases, the proportion of groups of order $p^5$ with at least one exceptional quotient tends to 1/2.     

Generalized Bayes minimax estimators of the mean of multivariate normal distribution with unknown variance

We construct a broad class of generalized Bayes minimax estimators of the mean of a multivariate normal distribution with covariance equal to σ²I_p, with σ² unknown, and under the invariant loss δ(X)−θ²/σ². Examples that illustrate the theory are given. Most notably it is shown that a hierarchical version of the multivariate Student-t prior yields a Bayes minimax estimate.