Synthesis of granulated binder-free LTA zeolite from metakaolin using ultrasonic treatment

It was studied the influence ultrasonic treatment (22 kHz) of an aqueous suspension of metakaolin on the synthesis of the granulated binder-free LTA zeolite. Mixtures with a molar ratio of the solid ingredients of 6Al₂Si₂O₇:12NaOH (stoichiometric) and 6Al₂Si₂O₇:12NaOH:2Al₂O₃ have been investigated. XRD, SEM, FT-IR and rotational viscosimetry have been used for testing. It was established that in the mixture with an Al₂O₃ excess after the ultrasonic treatment, sodium aluminates of cubic syngony were synthesized. Moulding pastes have been prepared from the sonicated suspensions and pellets of 3 mm diameter have been formed by extrusion. It is shown that sodium aluminates increased both the strength of coagulation structure of pastes and the mechanical strength of the pellets. It was found that after the thermal treatment of the granules at 650 °C, Na₆Al₄Si₄O₁₇ was formed. In the mixture with an Al₂O₃ excess, Na₈Al₄Si₄O₁₈ was also detected. The zeolitization of sodium aluminosilicates and unreacted metakaolin during hydrothermal crystallization in the NaOH solution with concentration of 2 mol l^?1 allowed synthesizing the LTA zeolite. The pellets from the stoichiometric mixture contained 91 wt% zeolite and the remainder was unreacted Na₆Al₄Si₄O₁₇ and other byproducts. The pellets from the mixture with an Al₂O₃ excess contained 97 wt% LTA.     

Polyfluorinated Electrolyte for Fully Printed Carbon Nanotube Electronics

Flexible electronics with highly thermal stability and mechanical strength are highly needed in advanced transportation systems. Semiconducting single‐walled carbon nanotubes are one of the leading active materials for such thin film transistors because they are printable, flexible, thermally stable, and mechanically strong. Dielectrics with large capacitance are another major component, and polymer electrolytes are printed for flexible electronics, but they suffer from poor mechanical strength and low operating temperature. Here, a transparent, mechanically flexible, and thermally stable polyfluorinated electrolyte (PFE) is developed with high capacitance by curing printed polyfluorinated resin (PFR) and ionic liquid composite at high temperature. PFE inherits the mechanical flexibility and thermal stability from PFR. The immobilized ionic liquid inside the porous structures of PFE accounts for the high capacitance. With top‐gated PFE, fully printed electronically pure single‐chirality (6,5) single‐walled carbon nanotube (SWCNT) thin‐film transistors (TFTs) exhibit air stable, consistent, and reliable ambipolar characteristics with high transconductance (1 mS) and small subthreshold swing (<0.15 V dec^?1) at low voltage in ambient air for p‐type and n‐type carriers, and >10⁵ ON/OFF current ratio for both carriers under low operation voltage.     

大型体育赛事筹备阶段中的组织变革——2006年欧洲田径锦标赛案例研究

本文主要是基于对大型体育赛事组织的研究.本文重点研究了承办2006年欧洲田径锦标赛这一大型体育赛事的当地组委会中所出现的组织变革.从组织成长和组织设计的角度出发,本文主要研究了项目成员的角色和作用,以及从项目计划到项目实施过程中组织的变革等问题.对于实施阶段很短暂的项目,这些研究成果可以促进承担这类项目的组织自身的发展,并且对于研究人员和项目参与者,也有利于他们了解组织所要面临的诸多潜在挑战.本文的研究历时三年多,是针对承办赛事的当地组委会这一组织发展的跟踪研究的一部分.     

大跨异形钢连廊连体结构振动台试验研究

为研究高烈度区大跨异形钢连廊连体结构的抗震性能,开展1/30缩尺模型的模拟地震振动台试验。通过33个工况,分析连体结构的破坏特征、动力特性、加速度、位移和应变响应。结果表明：8度多遇和设防地震作用下,连体结构未发生破坏,自振频率无明显改变,基本为弹性状态;随着地震动强度的增大,连体结构的损伤逐渐累积,自振频率逐渐下降,主楼和附楼I的加速度放大系数逐渐减小,钢连廊与附楼I连接处发生微小裂缝,钢连廊跨中的竖向加速度放大系数先减小后增大,同时钢连廊对竖向振动放大效应明显,且带有明显的扭转反应;8度罕遇地震作用下,主楼和附楼I的剪力墙、框架柱出现裂缝,钢连廊与附楼I连接处的破坏加剧,其竖向自振频率下降了3.37%。连体结构的薄弱处位于钢连廊与附楼I的连接处,该处发生局部锚固破坏。连体结构的层间位移角未超过抗震规范的限值,满足“小震不坏”和“大震不倒”的抗震设防要求。     

Family dynamics across pregnant Latina adolescents' transition to parenthood.

Growth curve models were conducted on assessments of family functioning at four time points from the third-trimester of pregnancy through the first year postpartum for 96 Latino families in which an adolescent daughter was pregnant. Results indicated significant family-level change following an adolescent's childbearing, though there were notable differences between family members in their perceptions of family functioning. Family conflict, as perceived by parenting teens, increased in the latter half of the first year after an initial decline, and family companionship (as rated by mothers and siblings) decreased. Parenting adolescents and siblings perceived significant increases in family cohesion, whereas mothers perceived a significant decline. Unplanned pregnancies, family financial hardship, and expected stress predicted unfavorable family functioning at 1 year. Contrary to expectations, adolescents' greater prenatal efforts to prepare for parenting predicted subsequent family conflict and declines in family cohesion (particularly as rated by mothers). Family members' acculturation level and attitudes of familism, gender roles, and the status attained by parenthood also had predictive effects. Implications of study findings for family adjustment following an adolescent's childbearing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sparse power equalization placement for limiting jamming attack propagation in transparent optical networks

The latest advances in Wavelength Division Multiplexing (WDM) technology are making it possible to build all-optical transparent WDM networks, which are expected to be able to satisfy the rapid growth of today’s capacity demand. However, the transparency of such networks makes them highly vulnerable to deliberate attacks, specifically targeting the physical layer. Physical-layer attacks, such as high-power jamming, can cause severe service disruption or even service denial, enhanced by their capability to propagate through a transparent optical network. Several attack-aware routing and wavelength assignment algorithms have been proposed to reduce the possible disruption caused by high-power jamming attacks. However, even with network planning approaches which take network security, specifically physical-layer attacks, into account, resilience to deliberate attacks in such scenarios remains an issue.In this paper, we propose the use of wavelength-selective attenuators as power equalizers inside network nodes to limit the propagation of high-power jamming attacks. Due to the increased cost of optical switching nodes associated with the addition of power equalizers, we aim at minimizing their number through sparse power equalization placement. We developed a set of greedy algorithms to solve what we call the Power Equalization Placement (PEP) problem with the objective of minimizing the number of power equalizers needed to reduce, to a desired level, the propagation of high-power jamming attacks for a given routing scheme. We further improved upon these results by proposing a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic with a somewhat longer execution time, but with significantly superior results. The performance evaluation results indicate that the proposed GRASP heuristic can achieve the same attack propagation reduction as can be obtained by equipping all nodes with power equalizers by placing them at less than 50% of the nodes on average, potentially yielding significant cost savings.     

Compact Efficient Feed-Horn at 30–38 GHz for a Multi-beam Radio Telescope

The requirements for a feed suitable for a radio telescope multi-beam focal plane array are considered. A smooth-walled spline-profile horn covering the 30–38 GHz frequency band to be used in a multi-beam receiving array of a radio telescope has been optimized, manufactured and tested. The achieved cross-section aperture size of the horn allows us to provide a neighboring beam spacing equal or less than 2HPBW for the RATAN-600 radio telescope. The measured sidelobe levels of the radiation pattern is less than −30dB/−24dB/−26dB in H/E/45⁰-planes, cross-polarization levels better than −20 dB, an input return loss better than −18 dB and the −3dB/−10dB-beamwidths are of the order of 40o/ 80o over the frequency band. Mutual-coupling of adjacent horns is less than −38 dB.     

Links between sisters' sexual and dating victimization: The roles of neighborhood crime and parental controls.

This study examined the extent to which a sister's prior sexual and dating victimization is a risk factor for young women being similarly victimized and the possible factors underlying a co-occurrence. The sample involved 122 young adult Latina or African American sister pairs (244 women; ages 16–25) who resided in low-income, urban neighborhoods. Results indicated that women whose sisters had been victimized had increased risk of victimization even after controlling for neighborhood crime, parental controls, age and race–ethnicity (odds ratios were 4.0 for unwanted touching, 6.2 for a forced sex act, and 16.7 for dating violence). In high-crime neighborhoods, the presence of two adult parent figures in the home was associated with women's reduced likelihood of unwanted touching, and mothers' high monitoring during adolescence was associated with women's lower risk of dating aggression. Survival analysis results showed that the risk period of a second sister being victimized lasts between 7 and 10 years after a first sister's victimization. The prevention implications of study findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Action and object processing in brain-injured speakers of Chinese.

Objective: To see whether action and object processing across different tasks and modalities differs in brain-injured speakers of Chinese with varying fluency and lesion locations within the left hemisphere. Method: Words and pictures representing actions and objects were presented to a group of 33 participants whose native and/or dominant language was Mandarin Chinese: 23 patients with left-hemisphere lesions due to stroke and 10 language-, age- and education-matched healthy control participants. A set of 120 stimulus items was presented to each participant in three different forms: as black and white line drawings (for picture-naming), as written words (for reading) and as aurally presented words (for word repetition). Patients were divided into groups for two separate analyses: Analysis 1 divided and compared patients based on fluency (Fluent vs. Nonfluent) and Analysis 2 compared patients based on lesion location (Anterior vs. Posterior). Results: Both analyses yielded similar results: Fluent, Nonfluent, Anterior, and Posterior patients all produced significantly more errors when processing action (M = 0.73, SD = 0.45) relative to object (M = 0.79, SD = 0.41) stimuli, and this effect was strongest in the picture-naming task. Conclusions: As in our previous study with English-speaking participants using the same experimental design (Arévalo et al., 2007, Arévalo, Moineau, Saygin, Ludy, & Bates, 2005), we did not find evidence for a double-dissociation in action and object processing between groups with different lesion and fluency profiles. These combined data bring us closer to a more informed view of action/object processing in the brain in both healthy and brain-injured individuals. (PsycINFO Database Record (c) 2011 APA, all rights reserved)