1000 resultados para 760-4
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Percutaneous valve replacement for severe aortic stenosis has shown to be an alternative treatment option for non-surgical candidates. We report on the first successful valve in valve procedure in an 80-year-old patient with a severe regurgitation of a degenerated aortic bioprosthesis using the Corevalve Revalving system.
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"November 1978."
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"3 June 1981."
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本工作对下面两种端乙炔基芳醚砜单体的核磁共振谱进行了研究。通过加入位移试剂Eu(fod)_3引起共振吸收峰化学位移值的变化趋热及同核去偶,'H选择质子去偶的方法分别对其'H谱和~(13)C谱(COM)做了归属。在确认对化合物<I>'H谱和~(13)C谱(COM)归属的基础上,演绎出三种苯环上取代基团的'H和~(13)C化学位移取代参数。这些基团的取代参数目前在文献中尚未见报导,用这些参数来计算化的<II>的'H和~(13)C谱(COM)化学位移值时,与观测值有较好的吻合。本工作对双[4-(4-乙炔基苯氧基)苯基]砜的溶液聚合反就(DMSO)作溶剂、PdCl_2·2DMSO作催化剂)进行了研究。采用高压液体色谱和旋转薄层色谱分离反应的各种中间产物,通过中间产物的红外和'HNMR谱变化,演绎聚合反应的历程,还在'H核磁谱仪样品管内做了短时间反应,跟踪记录反应信息。聚合产物自始至终可分为溶于二氯甲烷和不溶于二氯甲烷两部分。在整个反应过程中,可溶性产物逐渐转变成不溶性产物,色谱分析表明可溶性产物是由未反应的单体、线型及环状低聚物、聚合度在9-10的齐聚物和少量聚合度更高的组分构成的。从称重测量不溶性产物所占比重和可溶性产物的高压液体色谱诸吸收峰峰高的变化,推算出聚合反应过程中单体、主要中间产物的变化趋势。可溶性产物的红外光谱中2920、1665-25、960-930、890,760-730 cm~(-1)吸收峰和'HNMR谱中的5.3, 3.5ppm吸收表明产物具有共轭多烯结构。'HNMR谱在芳核质子区出现7.7ppm吸收峰表明反应初期已有环化现象,这点与本体聚合反应是不同的。不溶性产物除聚合度或交联度高以外,与可溶性产物在结构上也有差异,其芳化程度高很多。从不同反应时间中间产物的红外和'HNMR谱(可溶部分)变化,显示了溶液聚合反应历程十分复杂,同时存在着几种反应。主反应是氯化钯络合物引发的配位络合聚合反应,钯络合物与单体的端乙炔基络合生成活性中心,三键在顺式位打开,生成共轭多烯增长链。链增长过程中伴随着热引起的多烯链顺-反异构化,部分反式多烯分子内环化,继而脱质于芳化生成三取代苯形式的环交联,芳化过程中可发生链的局部断裂。最终产物是共轭多烯链间通过芳环,炔烯桥交联成的体型聚合物。多烯和端乙炔基之间,多烯-多烯之间可发生Diels-Alder反应,因此溶液聚合产物再经短时间热处理,芳化程度增高,玻璃化温度大幅度提高。另外还研究了反应的溶剂效应和增加因含量对反应产率的影响,发现用氯仿和二氯甲烷作溶剂有利于共轭多烯链的顺-反异构化,固含量在2.25-11.25%范围,聚合产率变化不大。本文还对适用于双端炔基聚合反应的催化剂作了广泛的试探,首先考察了若干钯络合物,发现除PdCl_2·2DMSO外,PdCl_2·2MeCN、PdCl_2·2PhCN络合物也可作为双端炔基芳醚砜溶液聚合的催化剂。钴、镍的膦络合物[Co(PPh_3)_2]Cl_2、[Ni(PPh_3)_2]Cl_2可使双端炔基芳醚砜环化生成环状低聚物。极性溶剂四氢呋,二氧六环。氯仿和三氯甲烷可以用作Ziegler-Natta催化剂聚合双端炔基芳醚砜的溶剂。用AlEt_3-Ti(OBu)_4催化得到的聚合物以顺式多烯为主,玻璃化浊度高于250℃,热形变稳定性好。Al/Ti比在6-8时催化活性较高。用稀土体系的Ziegler-Natta催化剂AlEt_3-NdCl_3·2THF、AlEt_3-(CF_3COO)_3Nd也可得到类似的催化效果。制备了以双氰为配位基的高分子-钯络合物,在催化双端炔基单体聚合时具有与类似的低分子钯络合物PdCl_2·2MeCN相近的效果。改变高分子催化剂的N/Pd比未出现明显的活性高峰。这部分工作还有待深入,予期在进一步深入研究之后,该高分子催化剂可用于制备双端乙炔基芒醚砜增强复合材料的连续化浸渍工序,让单体的氯仿溶液流经高分子-钯络合物填充的柱子形成齐聚物后,再浸渍涂层,可缩短成型的热固化时间,具有较大的经济意义。用非等温DSC法测定了双[4-(4-乙炔基苯氧(基)苯基]砜和双[4-(4-乙炔基苯氧基)苯基]酮的本体热聚合及有PdCl_2·2DMSO存在下的催化聚合的反劝力学参数,并与文献报导的(3-乙炔基苯氧基)苯模型物和双[4-(3-乙炔基苯氧基)苯基]砜的本体热聚合反应动力学参数进行比较。经电子计算机最小二乘曲线拟合程序汞得的结果表明表现反就活化能Eap,指数前因子A均与DSC的升温速率和转化率无关。讨论了模型物端乙炔基的位置和链上砜基,羰基的存在对聚合反应的影响,还通过对DSC升温过程中试样的红外光谱跟踪,解释了DSC峰表征的化学反应。
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BACKGROUND Cardiac sodium channel β-subunit mutations have been associated with several inherited cardiac arrhythmia syndromes. OBJECTIVE To identify and characterize variations in SCN1Bb associated with Brugada syndrome (BrS) and sudden infant death syndrome (SIDS). METHODS All known exons and intron borders of the BrS-susceptibility genes were amplified and sequenced in both directions. Wild type (WT) and mutant genes were expressed in TSA201 cells and studied using co-immunoprecipitation and whole-cell patch-clamp techniques. RESULTS Patient 1 was a 44-year-old man with an ajmaline-induced type 1 ST-segment elevation in V1 and V2 supporting the diagnosis of BrS. Patient 2 was a 62-year-old woman displaying a coved-type BrS electrocardiogram who developed cardiac arrest during fever. Patient 3 was a 4-month-old female SIDS case. A R214Q variant was detected in exon 3A of SCN1Bb (Na(v)1B) in all three probands, but not in any other gene previously associated with BrS or SIDS. R214Q was identified in 4 of 807 ethnically-matched healthy controls (0.50%). Co-expression of SCN5A/WT + SCN1Bb/R214Q resulted in peak sodium channel current (I(Na)) 56.5% smaller compared to SCN5A/WT + SCN1Bb/WT (n = 11-12, P<0.05). Co-expression of KCND3/WT + SCN1Bb/R214Q induced a Kv4.3 current (transient outward potassium current, I(to)) 70.6% greater compared with KCND3/WT + SCN1Bb/WT (n = 10-11, P<0.01). Co-immunoprecipitation indicated structural association between Na(v)β1B and Na(v)1.5 and K(v)4.3. CONCLUSION Our results suggest that R214Q variation in SCN1Bb is a functional polymorphism that may serve as a modifier of the substrate responsible for BrS or SIDS phenotypes via a combined loss of function of sodium channel current and gain of function of transient outward potassium current.
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A large population of the colonial pelagic tunicate Pyrosoma atlanticum occurred in April 1991 in offshore waters of the Ligurian Sea (Northwestern Mediterranean). The high numbers of colonies caught allowed their vertical distribution and diel migration in the 0-965 m water column to be described as a function of their size. Daytime depths and amplitudes of the migration were correlated with colony size. The amplitude of the migration ranged from 90 m for 3-mm-length colonies to 760 m for 51-mm-length colonies, with a mean amplitude of 410 m for the whole population, all sizes pooled. The results of horizontal hauls at a given depth around sunrise and sunset showed a marked diurnal symmetry of the migratory cycle relative to noon, and that migration of the population was not cohesive. For example, the larger the colonies, the later after sunset they reached the upper layers during their upward migration.
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Phycobiliproteins are a family of water-soluble pigment proteins that play an important role as accessory or antenna pigments and absorb in the green part of the light spectrum poorly used by chlorophyll a. The phycoerythrins (PEs) are one of four types of phycobiliproteins that are generally distinguished based on their absorption properties. As PEs are water soluble, they are generally not captured with conventional pigment analysis. Here we present a statistical model based on in situ measurements of three transatlantic cruises which allows us to derive relative PE concentration from standardized hyperspectral underwater radiance measurements (Lu). The model relies on Empirical Orthogonal Function (EOF) analysis of Lu spectra and, subsequently, a Generalized Linear Model with measured PE concentrations as the response variable and EOF loadings as predictor variables. The method is used to predict relative PE concentrations throughout the water column and to calculate integrated PE estimates based on those profiles.