Passively mode-locking Nd : Gd0.5Y0.5VO4 laser with an In(0.25)Ga(0.75)Aa absorber grown at low temperature

We have demonstrated stable self-starting passive mode locking in a diode-end-pumped Nd:Gd-0.8-Y0.5VO4 laser by using an In0.25Ga0.75As absorber grown at low temperature (LT In0.25Ga0.75As absorber). An In0.25Ga0.75As single-quantum-well absorber, which was grown directly on the GaAs buffer by use of the metal-organic chemical-vapor deposition technique, acts simultaneously as a passive mode-locking device and as an output coupler. Continuous-wave mode-locked pulses were obtained at 1063.5 nm. We achieved a pulse duration of 2.6 ps and an average output power of 2.15 W at a repetition rate of 96.4 MHz. (c) 2005 Optical Society of America.

P(AA-DAC)两性聚电解质水凝胶的合成及性质

以丙烯酸(AA)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体,采用水溶液聚合法制备了P(AA-DAC)聚电解质水凝胶.采用红外光谱和核磁共振等方法对其结构进行了表征.研究了不同组成比的聚电解质水凝胶在去离子水、不同pH值溶液以及不同离子强度盐溶液中的溶胀行为

PP-g-AA接枝共聚物的制备及表征

以部分预辐照聚丙烯(rPP)作为聚丙烯反应挤出接枝丙烯酸(AA)的引发剂,制备了PP-g-AA接枝共聚物。考察了预辐照剂量、预辐照聚丙烯用量以及单体浓度等因素对接枝反应的影响。采用红外光谱、差热扫描量热仪和偏光显微镜等测试技术对接枝产物的形态、结构及性能进行了研究。结果表明,这种新的PP-g-AA共聚物制备方法能有效抑制聚丙烯的降解并获得较高力学性能的接枝产物。研究发现,当rPP的预辐照剂量为4 kGy,反应原料的组成为m(PP)∶m(rPP)∶m(AA)=90∶10∶0.8时,得到的产物有较高的接枝率(0.19%),并且具有相对最佳的力学性能;这种接枝产物与铝板有很强的粘接效果,其剥离强度达4.88 kN/m。

LLDPE-g-AA的流变行为及力学性能

利用毛细管流变仪研究了线性低密度聚乙烯接枝丙烯酸 (LLDPE - g -AA)的流变行为。结果表明 ,在高的剪切应力下LLDPE -g -AA的表观粘度比纯LLDPE的小 ,并改进了树脂的流动性和加工性。LLDPE - g -AA的表观粘度随接枝丙烯酸含量的增加而降低 ,说明接枝到LLDPE分子链上的丙烯酸起到了内润滑剂的作用。利用Instron 112 1拉力机测试了LLDPE - g -AA的力学性能 ,结果表明其拉伸强度、杨氏模量和断裂伸长率与纯LLDPE相比没有明显的变化

LLDPE/LLDPE-g-AA共混物的接触角及红外光谱表征

利用熔融共混的方法制备了线性低密度聚乙烯/线性低密度聚乙烯接枝丙烯酸(LLDPE/LLDPE-g-AA)共混物。用傅里叶红外光谱(FT-IR)和测定接触角的方法对不同LLDPE-g-AA含量的LLDPE/LLDPE-g-AA共混物膜的表面进行了表征。结果表明,随着共混物中LLDPE-g- AA含量的增加,水和甘油等极性液体与共混物表面的接触角下降。依据共混物的FT-IR计算了其羧基峰强度。发现极性液体与LLDPE/LLDPE-g- AA共混物膜表面的接触角越小,羧基峰强度越大。

Interaction characterization of PA1010/PP blends using PP-g-AA as compatibilizer

The morphology of polyamidelOlO/polypropylene blends was found to significantly depend upon the concentration of the compatibilizer[polypropylene-grafted-acrylic acid (PP-g-AA)]. A significant reduction in phase size was observed because of the interaction that existed between the PP-g-AA and polyamide. These interactions have been confirmed by several methods. The tensile mechanical properties and impact behavior of the prepared blends were investigated and correlated with scanning electron microscope (SEM) analysis of the fracture surfaces. It was found that PP-g-AA as the compatibilizer has a profound effect upon the properties of the blends. This behavior is attributed to a series of chemical and physico-chemical interactions taking place between the two components.

PP－g－AA的制备和表征

用熔融接枝方法制备了聚丙烯－ｇ－丙烯酸（ＰＰ－ｇ－ＡＡ）。用光电子能谱，广角Ｘ射线衍射，红外光谱和化学滴定方法对接枝物进行了定性和定量表征。讨论了单体和引发剂浓度对接枝率的影响，确定了用红外光谱法测定接枝物含量的经验公式

THE CHAIN STRUCTURE AND LIGHT-SCATTERING-STUDIES FOR ACRYLAMIDE-SODIUM ACRYLIC-ACID (AM-AA) COPOLYMERS

A set of AM-AA copolymer samples with the same comonomer content and different average molecular weight have been characterized by C-13 NMB and light scattering methods in this paper. The chemical composition (comonomer AA, mole content 16.9 +/- 1.1%) of these samples is uniform. the sequence of AA in the macromolecular chain is of alone and random distribution and the light scattering theory from polyelectrolyte in added-salt solutions is suitable for the AM-AA copolymers-0.12 mol/L NaCl water systems. The actual values of M(w), the second Virial coefficient A(2) and the mean square radius of gyration (R(2)), for the studied samples have been obtained. The relationships between the molecular parameters are as follows: A(2)=0.0619 ($) over bar M(w)(-0.24), < R(2) >(1/2)(t)= 0.0210 ($) over bar M(w)(0.54).

Fruticultura: açaí.

Família. Gênero. Espécies. Euterpe oleraceae. Euterpe precatoria. Propagação. Preparo da muda. Plantio e adubação. Tratos culturais. Colheita. Beneficiamento e comercialização.

Produção de mudas de açaí em viveiros na floresta.

Neste trabalho e apresentado a recomendação técnica para a produção de mudas na floresta, um método que concilia orientações técnicas de fácil assimilação por produtores ribeirinhos que se dedicam a exploração dos açaizais, mantendo o baixo custo das mesmas.