Polynomial Identities for Tangent Algebras of Monoassociative Loops

We introduce degree n Sabinin algebras, which are defined by the polynomial identities up to degree n in a Sabinin algebra. Degree 4 Sabinin algebras can be characterized by the polynomial identities satisfied by the commutator, associator, and two quaternators in the free nonassociative algebra. We consider these operations in a free power associative algebra and show that one of the quaternators is redundant. The resulting algebras provide the natural structure on the tangent space at the identity element of an analytic loop for which all local loops satisfy monoassociativity, a ² a ≡ aa ². These algebras are the next step beyond Lie, Malcev, and Bol algebras. We also present an identity of degree 5 which is satisfied by these three operations but which is not implied by the identities of lower degree.     

Stochastic Resonance in a Bistable System with Time-Delayed Feedback Loops

The phenomenon of stochastic resonance of a bistable system subjected to linear time-delayed feedback loops driven by multiplieative Gaussian coloured noise and additive Gaussian white noise is investigated. Firstly, the analytic expression of the quasi-steady distribution function Ps （x, t） is derived by applying the unified coloured noise approximation and the Novikov Theorem; Secondly, the expression of the signal-to-noise ratio （SNR） is obtained in the adiabatic limit to quantify the stochastic resonance. Finally, tile effects of the linear coefficient a, the nonlinear coefficient b, the linear time-delayed feedback coefficient c and the delay time r on Ps（x,t） and SNR^± are discussed. It is found that the effects of the linear coefficient and the nonlinear coefficient, the positive linear time-delayed feedback coefficient and the negative linear time-delayed feedback coefficient, the positive delayed time and the negative delayed time on Ps（x,t） and SNR^± are different, respectively. This discussion would be helpful to the study of the system reliability and controlling stochastic resonance.     

Reflectance and ultraviolet spectroscopy: predicting the relative growth of Saccharomyces cerevisiae in pine biomass

Ultrasound treatment favors enzymatic attack on vegetal materials and influences biological activity. The objective of this study was to develop substrates for Saccharomyces cerevisiae based on the hydrothermal treatment and ultrasound treatment of pine needle biomass. The samples subjected to ultrasound treatment at 550?°C and 650?°C showed higher reflectance bands at around 200?nm after 80?min of ultrasound treatment and lower band gap energies associated with lower IC₃₀ values. The hydrothermal treatment with 100?min of ultrasound treatment generated more promising materials for the use of the substrates with the eukaryotic model S. cerevisiae.     

三嗪噁二唑基吡唑衍生物抑酶活性的QSAR模型

基于拓扑化学理论,原子类型电拓扑态指数(Mk)被用于表征18种三嗪噁二唑基吡唑衍生物的化学微环境。采用最佳变量子集回归方法,分别建立上述化合物对蛋白酪氨酸磷酸酯酶1B(PTP1B)、细胞分裂周期25磷酸酯酶B(Cdc25B)的抑酶活性(P_t、C_d)与Mk的定量构效关系(QSAR)模型。它们的最佳三元QSAR模型的判定系数(R~2)依次为0.896、0.828,逐一剔除法交叉验证相关系数(R_(cv)~2)依次为0.830、0.688。经R_(cv)~2、VIF、FT、AC等检验,该模型具有良好的稳健性及预测能力。经训练集验证,上述模型均具有良好的外部预测能力。模型显示,影响Pt、Cd的因素既有不同的结构基团(-CH_3、-O-、-NH_2和芳环中-N=),也有相同的因素(芳环中-C=)。     

Compounds with inhibitory activity on peristalsis from the seeds of Holarrhena antidysenterica

Eight compounds were isolated from the seeds of Holarrhena antidysenterica Wall.ex A.DC. On the basis of physico-chemical properties and spectroscopic data, holarrhenanan (1) was identified as a new compound, compounds 2–3 were isolated from H. antidysenterica for the first time, and five known compounds were also obtained. Inhibitory effects of some compounds and extracts to the intestinal peristalsis were evaluated. Results showed that the extracts and compounds 4, 6 exhibited remarkable inhibitory effects with tension inhibition rate of 32.77, 32.77% and amplitude inhibition rate of 59.51, 55.98%, respectively on the vitro rabbit intestinal peristalsis.     

Thioquinomycins A-D,novel naphthothiophenediones from the marine-derived Streptomyces sp. SS17F

Thioquinomycins A-D (1–4), four novel naphthothiophenediones were isolated from the rice-based medium of the marine-derived Streptomyces sp. SS17F. Their structures were elucidated by spectroscopic methods and HRESIMS data. The absolute configurations of all the compounds were elucidated by X-ray diffraction analysis, ECD and Mosher's method combined with ¹⁹F-NMR. Compounds 1–4 showed moderate cytotoxicity against NCI-H1975 with IC₅₀ values from 17.5 to 50?μM. In addition, compounds 1–4 also exhibited inhibitory activities against PKCα and ROCK2 protein kinase.     

Phytochemical constituents from dietary plant Citrus hystrix

Chemical investigation of the fruit peel of dietary plant Citrus hystrix offered two new flavones 5,6,4′-trihydroxypyranoflavone I and 5,4′-dimethyl-6-prenylpyranoflavone XIII besides 11 known compounds. The structures of all compounds were elucidated with the aid of suitable analytical methods like 1D, 2D-NMR, mass and single crystal X-ray analysis. An X-ray crystal study of compound II was done for the first time and the compounds I–VI, XI and XII are hitherto not reported from this plant. Biological studies revealed that compound I found to have a good antidiabetic and antiacetylcholinesterase activities meanwhile compounds II, III and V showed a significant free radical scavenging ability as well as antioxidant capacity. In addition, compounds I, IV, V and VI showed cytotoxicity against U87, A549 and MCF-7 cells. Overall, the new compound I showed valuable bioactive properties. Due to insufficient quantity of compound XIII, biological studies were not done.     

Generic leaves

A remarkable theorem of E. Ghys asserts that, for any harmonic measure on a compact, foliated metric space, -almost every leaf has 0, 1, 2 or a Cantor set of ends. In this paper, analogous results are proven for topologically almost all (i.e., residual families of) leaves. More precisely, if some leaf is totally recurrent, a residual family of leaves is totally recurrent with 1, 2 or a Cantor set of ends. A "local" version of this theorem asserts that, in general, topologically almost all leaves have 0, 1, 2 or a Cantor set of dense ends. Received: October 1, 1997     

Single‐cell gel electrophoresis (the comet assay): Loops or fragments?

Single-cell gel electrophoresis, or the comet assay, is widely used to measure DNA damage and repair. Upon electrophoresis, the DNA of lysed, agarose-embedded cells known as nucleoids, extends towards the anode in a structure resembling a comet, the relative intensity of the tail reflecting the frequency of DNA breaks. The structural organization of the DNA within comet preparations is not fully understood. We have used fluorescent in situ hybridization with large-insert genomic probes and human Cot-I DNA to investigate whether the production of the comet tail is simply explained by the relaxation of supercoiled DNA loops. We find that, under neutral electrophoresis conditions, when the tail and head DNA are double-stranded, the probed sequence of DNA is seen as a linear array, consistent with extension from a fixed point on the nuclear core or matrix. After alkaline electrophoresis, the appearance of the fluorescent probes suggests that linear DNA has coalesced into a granular form.