The LIN-3 gene of the nematode C. elegans is the vulval-inducing signal

The development of the vulva of the nematode Caenorhabditis elegans is induced by a signal from the anchor cell of the somatic gonad. Activity of the gene lin-3 is required for the Vulval Precursor Cells (VPCs) to assume vulval fates. It is shown here that lin-3 encodes the vulval-inducing signal.

lin-3 was molecularly cloned by transposon-tagging and shown to encode a nematode member ofthe Epidermal Growth Factor (EGF) family. Genetic epistasis experiments indicate that lin-3 acts upstream of let-23, which encodes a homologue of the EGF-Receptor.

lin-3 transgenes that contain multiple copies of wild-type lin-3 genomic DNA clones confer a dominant multivulva phenotype in which up to all six of the VPCs assume vulval fates. The properties of these trans genes suggest that lin-3 can act in the anchor cell to induce vulval fates. Ablation of the gonadal precursors, which prevents the development of the AC, strongly reduces the ability of lin-3 transgenes to stimulate vulval development. A lin-3 recorder transgene that retains the ability to stimulate vulval development is expressed specifically in the anchor cell at the time of vulval induction.

Expression of an obligate secreted form of the EGF domain of Lin-S from a heterologous promoter is sufficient to induce vulval fates in the absence of the normal source of the inductive signal. This result suggests that Lin-S may act as a secreted factor, and that Lin-S may be the sole vulval-inducing signal made by the anchor cell.

lin-3 transgenes can cause adjacent VPCs to assume the 1° vulval fate and thus can override the action of the lateral signal mediated by lin-12 that normally prevents adjacent 1° fates. This indicates that the production of Lin-3 by the anchor cell must be limited to allow the VPCs to assume the proper pattern of fates of so 3° 3° 2° 1° 2° 3°.

New doubly periodic waves of the (2+1)-dimensional double sine-Gordon equation

New exact solutions of the (2 + 1)-dimensional double sine-Gordon equation are studied by introducing the modified mapping relations between the cubic nonlinear Klein-Gordon system and double sine-Gordon equation. Two arbitrary functions are included into the Jacobi elliptic function solutions. New doubly periodic wave solutions are obtained and displayed graphically by proper selections of the arbitrary functions.

Preparação e Avaliação da Atividade Catalítica de Polímeros de Condensação de Metilpiridinas e Tereftalaldeído em Reações de Nitroaldol e Cicloadição Heterodipolar [3+2]

Nesse estudo, foram preparadas bases poliméricas derivadas de 2,6-dimetilpiridinas e tereftaladeído utilizando a 2,4,6-trimetilpiridina como agente de reticulação. As resinas foram sintetizadas sob aquecimento convencional e purificadas por precipitação em metanol, apresentando rendimentos variando de 59 a 95%. Os copolímeros produzidos foram caracterizados por análise termogravimétrica (TGA), ressonância nuclear magnética de núcleo de hidrogênio (RMN-1H) e espectroscopia na região do infravermelho com técnica de ATR (FTIR - ATR), além de sua atividade básica. A capacidade catalítica do material produzido foi avaliada em reações nitroaldólicas, do tipo Henry, tanto em aquecimento convencional quanto com o uso de reator de micro-ondas. Não sendo observada atividade catalítica significativa para as resinas testadas, nestas reações. O material polimérico produzido também foi testado como suporte para cobre na catálise de reações de cicloadição heterodipolar do tipo [3+2] com benzilazida e propiolato de etila, para a formação de triazóis, processadas em reator de micro-ondas e sob aquecimento convencional. A reação mostrou-se regiosseletiva e processos de reciclo do catalisador se mostrou eficiente em reações consecutivas

2.1 GHz MOS mixer linearisation approach for IIP2 enhancement using multiple factor compensation

An integrated downconversion CMOS mixer incorporating a comprehensive compensation scheme is presented which aims to minimise second-order intermodulation distortion (IMD2). Unlike previously reported IMD2 calibration schemes which tune only one nonlinear factor at a time, the presented solution allows simultaneous adjustment of several different factors thus achieving a better compensation. The mixer has been implemented in UMC 0.18 μm CMOS to verify the proposed scheme and for comparison with alternative compensation methods. Measurements show that the solution described can improve the input intercept point (IIP2) by over 20 dB while maintaining good amplification and noise performance. IMD2 calibration results are presented and show useful advantages over other approaches. To the best of the authors' knowledge, this scheme for IMD2 calibration has not been previously reported. © The Institution of Engineering and Technology 2013.

1,5-二氮杂戊二烯合成非对称联吡啶研究

联吡陡及其衍生物不仅用于化工和药物合成的中间体，而且具有独特的赘合作用，可被用于金属催化剂配体等方面，因此它的合成方法研究引起了人们广泛的兴趣。但是非对称联吡陡的合成日前方法仍很少。本文利用己经被成功使用于其他含氮杂环的二碳合成子-1，5-二氮杂戊二烯（vinamidiniulnsalts），合成了单取代的2，2'-，2，3'-，2，4，一二类联吡陡。在合成1，5-二氮杂戊二烯的过程中：确立了一条以四甲氧基丙烷为原料一步合成l，5一二氮杂戊二烯的简捷，经济，易工业化的合成路线，并成功进行了公斤级的放大实验；优化了1，5-二氮杂戊二烯的亲电取代反应，高收率的获得溟代，硝化的1，5-二氮杂戊二烯；优化了从取代乙酸合成p取代1，5-二氮杂戊二烯的合成方法，高收率的获得九种p芳基取代1，5-二氮杂戊二烯。本文研究了非对称联吡睫合成的一种新方法：在碱性条件下，取代的1，5-二氮杂戊二烯盐各种乙酞基吡陡亲核加成的产物，不经分离直接和氨进行［3＋2＋1〕的成环反应，可以高收率的合成出单取代的2，2气，2，3气，2，4气三类联吡陡。这一方法己经被成功的应用于芳基取代，卤素取代，硝基取代以及无取代基的1，5-二氮杂戊二烯与三种乙酞基吡陡的反应。这种成环反应的收率与1，5-二氮杂戊二烯俘位的吸电子特征相关。因此，针对不同取代基的1，5-二氮杂戊二烯在溶剂，碱的选择以及反应温度的控制等方面进行了优化。从而成功合成出近30种单取代的非对称联吡陡。一这种合成方法，原料价格低廉，实验操作简单，而且收率高，非常适合大量合成的要求。

3～5.3μmIn_xGa_(1-x)As/Al_yGa_(1-y)As/Al_zGa_(1-z)As非对称台阶量子阱红外探测器

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