谈化学反应的转化率

本文讨论了化学反应转化率的正确定义,并纠正了某些教材中的不正确说法。     

Induction and effector functions of T(H)17 cells

T helper (T(H)) cells constitute an important arm of the adaptive immune system because they coordinate defence against specific pathogens, and their unique cytokines and effector functions mediate different types of tissue inflammation. The recently discovered T(H)17 cells, the third subset of effector T helper cells, have been the subject of intense research aimed at understanding their role in immunity and disease. Here we review emerging data suggesting that T(H)17 cells have an important role in host defence against specific pathogens and are potent inducers of autoimmunity and tissue inflammation. In addition, the differentiation factors responsible for their generation have revealed an interesting reciprocal relationship with regulatory T (T(reg)) cells, which prevent tissue inflammation and mediate self-tolerance.     

Memory CD4 T cells emerge from effector T-cell progenitors

A hallmark of adaptive immunity is the generation of memory T cells that confer long-lived, antigen-specific protection against repeat challenges by pathogens. Understanding the mechanisms by which memory T cells arise is important for rational vaccination strategies and improved therapeutic interventions for chronic infections and autoimmune disorders. The large clonal expansion of CD8 T cells in response to some infections has made the development of CD8 T-cell memory more amenable to study, giving rise to a model of memory cell differentiation in which a fraction of fully competent effector T cells transition into long-lived memory T cells. Delineation of CD4 T-cell memory development has proved more difficult as a result of limitations on tracking the smaller populations of CD4 effector T cells generated during a pathogenic challenge, complicating efforts to determine whether CD4 memory T cells are direct descendants of effector T cells or whether they develop by alternative pathways. Here, using two complementary cytokine reporter mouse models to identify interferon (IFN)-gamma-positive effector T cells and track their fate, we show that the lineage relationship between effector and memory CD4 T cells resembles that for CD8 T cells responding to the same pathogen. We find that, in parallel with effector CD8 T cells, IFN-gamma-positive effector CD4 T cells give rise to long-lived memory T cells capable of anamnestic responses to antigenic rechallenge.     

Common effector processing mediates cell-specific responses to stimuli

The fundamental components of many signalling pathways are common to all cells. However, stimulating or perturbing the intracellular network often causes distinct phenotypes that are specific to a given cell type. This 'cell specificity' presents a challenge in understanding how intracellular networks regulate cell behaviour and an obstacle to developing drugs that treat signalling dysfunctions. Here we apply a systems-modelling approach to investigate how cell-specific signalling events are integrated through effector proteins to cause cell-specific outcomes. We focus on the synergy between tumour necrosis factor and an adenoviral vector as a therapeutically relevant stimulus that induces cell-specific responses. By constructing models that estimate how kinase-signalling events are processed into phenotypes through effector substrates, we find that accurate predictions of cell specificity are possible when different cell types share a common 'effector-processing' mechanism. Partial-least-squares regression models based on common effector processing accurately predict cell-specific apoptosis, chemokine release, gene induction, and drug sensitivity across divergent epithelial cell lines. We conclude that cell specificity originates from the differential activation of kinases and other upstream transducers, which together enable different cell types to use common effectors to generate diverse outcomes. The common processing of network signals by downstream effectors points towards an important cell biological principle, which can be applied to the understanding of cell-specific responses to targeted drug therapies.     

Peptidergic transmitters in synaptic boutons of sympathetic ganglia

In sympathetic ganglia of the bullfrog, a slow synaptic potential lasting for minutes--the late slow excitatory postsynaptic potential (e.p.s.p.)--was discovered. This slow response, unlike other previously known synaptic potentials in the autonomic nervous system, is not mediated by acetylcholine or monoamines. Similar non-cholinergic, non-adrenergic slow synaptic potentials have since been found in several other vertebrate autonomic ganglia. We found that the late slow e.p.s.p. is probably mediated by a peptide that is identical to, or closely resembles, mammalian luteinizing hormone releasing hormone (LHRH), because (1) when applied directly to sympathetic neurones, LHRH and its agonists elicit a slow depolarization, associated with similar changes in membrane conductance and excitability as those occurring during the late slow e.p.s.p. Furthermore, both peptide-induced and nerve-evoked responses are blocked by antagonists of LHRH; and (2) radioimmunoassays indicate that a chain of sympathetic ganglia contains 100-800 pg of a LHRH-like peptide. Its distribution among spinal nerves, the great reduction of this substance following denervation, and its release from ganglia following isotonic KCl treatment or nerve stimulation suggest that the LHRH-like material is contained in preganglionic nerve fibres. Here we report that immunohistochemical staining of sympathetic ganglia shows that LHRH-like immunoreactivity is indeed present in synaptic boutons. We also show that the two types of ganglion cells (B cells and C cells) receive strikingly different patterns of peptidergic innervation.     

非理想发射机情况下的OQPSK性能分析

偏移四相相移键控(OQPSK)是一种适用于在限带非线性信道中使用的高效恒包络数字调制技术。OQPSK调制器的不均衡以及放大器的非线性对接收机的性能具有非常大影响。由于不均衡对载波跟踪环路的稳态锁定点的影响,使得平均误比特率(BEP)的性能受到了的决定性影响。通过对OQPSK调制器不均衡的模型讨论,深刻分析了调制器不均衡对载波跟踪环路稳态锁定点和平均BEP的影响。     

化学链燃烧钴基载氧体炉内脱汞机理研究

煤化学链燃烧炉内脱汞对降低煤燃烧单质汞的排放有重要意义,但是汞在载氧体作用下的氧化机制尚不明确。本文采用Co3O4载氧体在固定床反应器中进行脱汞实验,并在线检测反应器出口Hg0浓度。通过热力学计算揭示Hg0的催化氧化机制。实验结果表明,HCl与Co3O4的异相反应和HCl与Hg0的均相反应对Hg0脱除效率贡献都很大。随...     

基于SIB/PCA的通信辐射源个体识别

提出了一种新的同类通信辐射源个体识别方法.该方法选择矩形积分双谱(SIB)作为个体识别的主体特征参数.然后采用主元分析(PCA)方法从大量训练样本特征参数集中挑选低维、低复杂度的特征矢量,并在识别特征矢量中融合对分类具有显著贡献的辐射源调制特征参量,最后采用基于核函数的支撑矢量机(SVM)实现对辐射源个体识别.实验表明该方法在较低信噪比条件下具有较高的正确识别率(90%),并能够较好地解决同型号、同批次通信辐射源的个体识别问题.     

Inhibition of pathogenic effect of effector T cells by specific suppressor T cells during influenza virus infection in mice

Mice infected with an aerosol of influenza type A virus, or immunized with purified UV-inactivated whole virus or with viral subunits, develop a transient delayed-type hypersensitivity (DTH) which peaks 5-7 days after immunization. The intensity of DTH is greatly enhanced and sustained when mice are pretreated with cyclophosphamide. The reaction is maximal 24 h after elicitation, has classical tuberculin-type histology and is transferable by immune H-21 region restricted Lyt-1+2- T cells (Td) but not by immune serum. These Td cells not only fail to protect mice against influenza virus infection, but increase the mortality rate due to influenzal pneumonia following challenge with homologous lethal virus. On the other hand, antigen-specific suppressor T (Ts) cells which inhibit DTH are readily generated during influenza virus infection, and are detectable for at least 40 days thereafter. The ease with which they are induced and maintained during the infection may be of evolutionary advantage. In support of this, we now report that these Ts cells can reverse the pathogenic effect of Td cells thereby demonstrating a beneficial influence of Ts cells in a viral disease.     

Application of the multi-cycle estimator of Doppler and TDOA to passively locating targets exploiting non-cooperative transmitters

By exploiting the cyclostationary property of non-cooperative source signals, the problem of joint time-difference-of-arrival (TDOA) and Doppler estimation is discussed, and the multi-cycle estimator is developed by generalizing the single-cycle estimator. Utilizing a special commercial FM radio as a non-cooperative transmitter, some practical experiments are carried out. The right estimates of TDOA and Doppler of a particular airplane can really be obtained by processing the measurements with the multi-cycle estimation algorithm. Through adding some slowly time-variant white Gaussian noise to the original measurements, some independent Monte Carlo simulations are performed, and the simulation results reveal that the multi-cycle estimator is really superior to the single-cycle estimator and the conventional cross-correlation method.     

烧结矿应用于化学链燃烧的反应特性

本文通过热重实验研究了烧结矿作为载氧体的H2还原反应特性,将其与通过溶解法制备的Fe2 O3/Al2 O3载氧体进行了氧化还原反应性比较,在500~1250℃范围内研究了温度对于烧结矿还原反应过程的影响,在950℃下进行了30次循环反应实验,采用四种模型进行了反应动力学分析.结果表明,烧结矿的H2还原转化率大于80%,可以完全再氧化,并具有良好的循环反应性能.在500~950℃范围内,随温度升高还原反应速率及最终转化率都显著增加;而当温度高于1100℃时,在反应后期还原反应速率和最终转化率有下降的趋势.在500~950℃范围内,对烧结矿的还原过程第一反应阶段( Fe2 O3-Fe3 O4/FeO,还原转化率<25%)可采用二阶反应模型( M2)拟合,得到表观活化能为E=36.018 kJ·mol-1,指前因子为A0=1.053×10-2 s-1;第二反应阶段(Fe3O4/FeO-Fe,还原转化率>25%)采用收缩核模型(M4)拟合,得到的表观活化能为E=51.176 kJ·mol-1,指前因子为A0=1.066×10-2 s-1.     

Reciprocal developmental pathways for the generation of pathogenic effector TH17 and regulatory T cells

On activation, T cells undergo distinct developmental pathways, attaining specialized properties and effector functions. T-helper (T(H)) cells are traditionally thought to differentiate into T(H)1 and T(H)2 cell subsets. T(H)1 cells are necessary to clear intracellular pathogens and T(H)2 cells are important for clearing extracellular organisms. Recently, a subset of interleukin (IL)-17-producing T (T(H)17) cells distinct from T(H)1 or T(H)2 cells has been described and shown to have a crucial role in the induction of autoimmune tissue injury. In contrast, CD4+CD25+Foxp3+ regulatory T (T(reg)) cells inhibit autoimmunity and protect against tissue injury. Transforming growth factor-beta (TGF-beta) is a critical differentiation factor for the generation of T(reg) cells. Here we show, using mice with a reporter introduced into the endogenous Foxp3 locus, that IL-6, an acute phase protein induced during inflammation, completely inhibits the generation of Foxp3+ T(reg) cells induced by TGF-beta. We also demonstrate that IL-23 is not the differentiation factor for the generation of T(H)17 cells. Instead, IL-6 and TGF-beta together induce the differentiation of pathogenic T(H)17 cells from naive T cells. Our data demonstrate a dichotomy in the generation of pathogenic (T(H)17) T cells that induce autoimmunity and regulatory (Foxp3+) T cells that inhibit autoimmune tissue injury.     

反应矩阵在化学反应上的应用（一）—反应定理

从化学反应中提出反应矩阵的新概念,建立了用反应矩阵刻划出化学反应的反应定理,成功地应用于化学反应的实例.     

反应矩阵在化学反应上的应用（二）——配平定理

建立第1类型反应矩阵的2个配平定理,同时获得配平化学反应的矩阵法.     

A novel epitope of the LFA-1 antigen which can distinguish killer effector and suppressor cells in human CD8 cells

The CD4 subset of cells displays helper/inducer activity and recognizes class II antigens of the major histocompatibility complex (MHC), while the CD8 subset recognizes class I MHC antigens and exhibits cytotoxic or suppressor function. Considerable functional as well as corresponding phenotypic heterogeneity exists within the two major T cell subsets. Although the CD8+ population contains pre-cytotoxic, cytotoxic, pre-suppressor and suppressor effector T cells, these distinctions still rest largely on the use of functional assays. Attempts have been made to define the CD8+ precursor of the killer cell with new monoclonal antibodies. But more precise phenotypic distinctions between the functional subpopulations within CD8+ cells will be needed. We have now developed a monoclonal antibody, anti-S6F1 which can distinguish killer effector and suppressor effector cells in CD8 lymphocyte populations. The cell-surface structure defined by this antibody comprises two glycoproteins with relative molecular mass (Mr) 180K and 95K respectively. Also sequential immunoprecipitation studies and two dimensional gel electrophoresis indicate that anti-S6F1 recognizes a novel epitope on the LFA-1 antigen.