白首乌化学成分与药理活性研究进展

白首乌类植物含有C21甾体酯甙类、磷脂类、苯乙酮甙类等化学成分,具有抗氧化、调节免疫功能、抗肿瘤、抗缺氧、降血脂等多种药理活性.主要综述了近年来白首乌类植物化学成分及药理活性研究进展概况.     

From complexation to computation: Recent progress in molecular logic

The new thrusts in molecular logic are gathered together in this short review, while paying attention to the seeds from which these developments have arisen. The original demonstration of a few basic logic operations has now been extended to cover many of the one- and two-input varieties and even some of the three-input types. Many kinds of inputs and outputs have emerged, including various chemical species and some physical properties. The latter can include heat, light and, arguably, polarity. Reconfigurable logic has grown up to include a range of examples. Even superposable logic has proved possible with molecular systems. Numerical processors have flowered in recent years with several diverse approaches being revealed in recent years. Photochemical concepts such as photoinduced electron transfer (PET), internal charge transfer (ICT) and electronic energy transfer (EET) can be discerned among the designs in the field.     

Physico-chemical study of first row transition metal ions coordination compounds with N,N′-bis(2-tosylaminobenzylidene)-1,3-diaminopropanol. The crystal structure of bis-azomethine and its cobalt(II) complex

The novel Cu(II), Ni(II), Zn(II), Co(II) coordination compounds with Schiff base ligand - N,N′-bis(2-tosylaminobenzylidene)-1,3-diaminopropanol have been synthesized and studied. The structures of bis-azomethine as well as Co(II) and Zn(II) mononuclear metallochelates have been determined by X-ray analysis. The magnetic properties of all complexes were studied and interpreted in terms of HDVV theory. It was shown that exchange interaction in binuclear copper(II) complexes was affected by tosyl groups.     

Polypyrazolates of the heavier group 13 and 14 elements: A review

Heavy group 13 and 14 analogs of the poly(pyrazolyl)borates are the subject of this review. Within these, the most extensive research has been performed on the study of polypyrazolylgallates Me₂Ga(R₂pz)₂]⁻ (R = H or Me) and [MeGa(pz)₃]⁻, and their complexes with transition metals. In this review, the common features shared with the boron analogs are presented and contrasted. Other recently reported series of group 13 analogs are the alkali polypyrazolylaluminates Na[(R₂pz)₃] with R = Me, ^tBu; R′ = M. The complexes with one or two pyrazolyl ligands on aluminum display anagostic Al-CH₃?Na interactions, these interactions are persistent even if complexes were obtained from solutions with THF that normally coordinate alkali ions. The polypyrazolylsilane ligands Me₂Si(R₂pz)₂ and MeSi(R₂pz)₃ with R = H, Me are remarkably easy to obtain and isolate, in contrast is the fact that the carbon analogs are much harder to obtain and isolate in reasonable yields. Therefore it is surprising that the chemistry of the former ligands is not as developed as could be anticipated. Nevertheless there are examples of the use of these silanes as ligands with the following transition metals: Cr, Mn, Cu, Zn, Sc and Zr. The heavier group 14 analogs with Ge and Sn display coordination patterns with alkali and alkaline ions that resemble those observed with the borates and aluminates. The formation of cationic bimetallic cages of the type [E₂(R₂pz)₃]⁺ and neutral complexes [E₂(R₂pz)₄] has also been observed that can be consider formal isomers of the alkenes. The use of these compounds as ligands has been recently reported.     

Taylor-made palladium-pincer complexes: A new source of more efficient catalysts for sustainable organic synthesis

The synthesis and catalytic activity of different pincer type palladium complexes synthesized in our laboratory are compiled in this report. The specific design of these palladacycles allows the employment of sustainable protocols and the recycle of the catalytic systems.The results obtained by our group in this context will be compared with other previously reported and new advances in this field.     

光胁迫对杂种杨无性系光合放氧,光化学能量贮藏的影响

以光声光谱技术对经不同光强预处理的 3个杂种杨无性系即三倍体无性系B34 2、二倍体无性系B1 1[(Populusalba×P .glandulosa)× (P .tomentosa×P .bolleana) ]和三倍体无性系B34 6 [(P .tomentosa×P .bolleana)×(P .alba×P .glandulosa) ]的光合放氧、光声热信号及光化学能量贮藏进行测定。叶圆片的光声放氧信号和光化学能量贮藏与预处理光强度成反比 ;而光声热信号与预处理光强度成正比。光化学能量贮藏分配到PSⅡ的份额要比分配到PSⅠ的多。在强光胁迫下PSⅠ的光化学能量贮藏要比PSⅡ的光化学能量贮藏稳定。 3种抑制剂 (strepto mycin ,dithiothreitol,sodiumfluoride)均对叶圆片的光声放氧信号有影响。无性系B1 1和B34 2抵抗光胁迫的能力比无性系B34 6高     

Nuclear import of Ran is mediated by the transport factor NTF2

A concentration gradient of the GTP-bound form of the GTPase Ran across nuclear pores is essential for the transport of many proteins and nucleic acids between the nuclear and cytoplasmic compartments of eukaryotic cells [1], [2], [3] and [4]. The mechanisms responsible for the dynamics and maintenance of this Ran gradient have been unclear. We now show that Ran shuttles between the nucleosol and cytosol, and that cytosolic Ran accumulates rapidly in the nucleus in a saturable manner that is dependent on temperature and on the guanine-nucleotide exchange factor RCC1. Nuclear import in digitonin-permeabilized cells in the absence of added factors was minimal. The addition of energy and nuclear transport factor 2 (NTF2) [5] was sufficient for the accumulation of Ran in the nucleus. An NTF2 mutant that cannot bind Ran [6] was unable to facilitate Ran import. A GTP-bound form of a Ran mutant that cannot bind NTF2 was not a substrate for import. A dominant-negative importin-β mutant inhibited nuclear import of Ran, whereas addition of transportin, which accumulates in the nucleus, enhanced NTF2-dependent Ran import. We conclude that NTF2 functions as a transport receptor for Ran, permitting rapid entry into the nucleus where GTP-GDP exchange mediated by RCC1 [7] converts Ran into its GTP-bound state. The Ran–GTP can associate with nuclear Ran-binding proteins, thereby creating a Ran gradient across nuclear pores.     

Heavier halides of transition metals by halide exchange

Examples are reported of heavier (bromides or iodides) metal halides of the d or f transition series being prepared through the halide exchange reaction from the lighter congeners (fluorides or chlorides, easily prepared by direct combination from the elements), by using gaseous hydrogen halides HX or alkyl halides RX in an anhydrous organic solvent at room temperature or even below. This represents a considerable improvement with respect to the traditional high-temperature experimental procedures from the elements. Thermodynamic data show that this synthetic route is of quite general validity.     

Analysis of the center of pressure displacement, ground reaction force and muscular activity during step exercises

Anterior Knee Pain (AKP) is considered as one of the most common, yet misunderstood, knee pathologies. The aim of this study was to evaluate the displacement area of the center of pressure, Ground Reaction Force (GRF), and the electromyography activity of the hip and the quadriceps muscles in healthy and AKP individuals during the step-up and step-down exercises. Both groups (Control group and AKP group) were composed of 15 volunteers submitted to the exercises on a force plate. The AKP group presented greater displacement area of the center of pressure for all the situations evaluated than the Control group (p < 0.05), as well as a lesser magnitude of the GRF during the step-down exercise. The AKP group presented lower electromyography activity than the Control group in all situations evaluated. AKP individuals do not have muscle imbalances; they present a lower electromyography activity of the stabilizing muscles of the patella and hip and show greater instability in activities such as step up and down compared to normal subjects.     

A comparison of a maximum exertion method and a model-based, sub-maximum exertion method for normalizing trunk EMG

The problem with normalizing EMG data from patients with painful symptoms (e.g., low back pain) is that such patients may be unwilling or unable to perform maximum exertions. Furthermore, the normalization to a reference signal, obtained from a maximal or sub-maximal task, tends to mask differences that might exist as a result of pathology. Therefore, we presented a novel method (GAIN method) for normalizing trunk EMG data that overcomes both problems. The GAIN method does not require maximal exertions (MVC) and tends to preserve distinct features in the muscle recruitment patterns for various tasks. Ten healthy subjects performed various isometric trunk exertions, while EMG data from 10 muscles were recorded and later normalized using the GAIN and MVC methods. The MVC method resulted in smaller variation between subjects when tasks were executed at the three relative force levels (10%, 20%, and 30% MVC), while the GAIN method resulted in smaller variation between subjects when the tasks were executed at the three absolute force levels (50 N, 100 N, and 145 N). This outcome implies that the MVC method provides a relative measure of muscle effort, while the GAIN-normalized data gives an estimate of the absolute muscle force. Therefore, the GAIN-normalized data tends to preserve the differences between subjects in the way they recruit their muscles to execute various tasks, while the MVC-normalized data will tend to suppress such differences. The appropriate choice of the EMG normalization method will depend on the specific question that an experimenter is attempting to answer.