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1.
During the service life of structural sealant glazing (SSG) facades, the load-bearing capacity of the silicone bonds needs to be guaranteed. Laboratory tests can assess the durability of SSG-systems based on mechanical characteristics of the bond after simultaneous exposure to both climatic and mechanical loads. This article studies how the material characteristics of two common structural sealants are affected by laboratory and field exposure. Dynamic mechanical analysis (DMA) confirms a reduction in the dynamic modulus of exposed silicone samples. Results from thermogravimetric analysis, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and small-angle X-ray scattering/wide-angle X-ray scattering show differences between the two sealants and indicate no/minor changes in the composition and morphology of the laboratory and field exposed sealants. Mechanical characterization methods, such as DMA, and tensile and shear testing of the structural bond, are shown to be sensitive toward the combined climatic and mechanical loadings, and are hence suitable for studying degradation mechanisms of structural sealants. 相似文献
2.
引言具有宽供电电压范围的传统单片微功率运算放大器需要一个大芯片面积,因而导致封装和占位面积都很大。非传统的双路运算放大器LT6011在一种纤巧的新型封装内实现了25μV输入的精准微功率操作以及2.7~36V的电源电压范围,这种3mm×3mm的DFN封装非常之小,甚至没有引线。LT6011还提供了轨至轨输出摆幅,并采用具有超级电流增益放大系数的输入晶体管来实现安培级的输入电流。霍尔传感器放大器图1示出了LT6011被用作一个低功率霍尔传感器放大器时的情形。霍尔传感器的磁灵敏度与加在其两端的DC激励电压成比例。当偏置电压为1V时,该霍尔传… 相似文献
3.
Thomas S. Lowry John C. Bright Murray E. Close Christina A. Robb Paul A. White Stewart G. Cameron 《国际水资源开发杂志》2003,19(4):579-592
The primary objective of this project is to identify gaps, whether real or perceived, that hinder effective groundwater management in New Zealand. These gaps show as gaps in information, gaps in implementation, gaps in technological and management tools, and gaps in understanding of fundamental processes. The secondary objective is to propose a management strategy to close the identified gaps. Several methods are used to meet these objectives: surveys distributed to selected staff in each regional council; the review of various written reports; the analysis of land-use databases; and private consultation within each regional council. Results show that groundwater management in New Zealand is generally reactionary with the main gaps being in strategic planning and national guidelines. Most gaps appear to be predominantly information and implementation issues. In some cases there are gaps in the understanding of fundamental processes within an aquifer system, including the long-term effects of land-use on groundwater quality. An adaptive management approach is suggested as a means of closing these gaps. 相似文献
4.
Karen S. Servilla Antonios H. Tzamaloukas Charles Carter Glen H. Murata 《Hemodialysis international. International Symposium on Home Hemodialysis》2002,6(1):35-39
We developed a composite compliance index as the sum of the compliance scores for interdialytic weight gain (IDWG), pre‐dialysis serum potassium and phosphorus concentrations (each scored from zero to 3, with 3 indicating the poorest compliance), and skipping hemodialysis sessions (scored from zero to 9, with 9 indicating the poorest compliance). We used this composite score to prospectively evaluate compliance in 25 prevalent hemodialysis patients over a period of 1 year. We then followed these patients for another 3.5 years. The patients studied were divided into two groups: group A (poor compliance) consisted of 9 subjects with composite score ≥ 9 (13.2 ± 3.2); group B (better compliance) consisted of 16 subjects with composite score < 9 (4.7 ± 1.8). Age, duration of hemodialysis, and frequency of diabetes mellitus did not differ between the groups. Group A contained higher fractions of subjects with history of alcoholism (66.7% vs 12.5%, p = 0.010), other substance addiction (44.4% vs 0%, p = 0.010), and severe psychosocial problems (88.9% vs 18.8%, p = 0.002). Mean survival from the beginning of observation, estimated by actuarial life‐table survival analysis, was 1.19 years in group A and 2.60 years in group B (p = 0.0265). A composite compliance index incorporating domains indicating adherence to diet, medications, and dialysis schedule identified other behavioral problems in poorly compliant patients. Hemodialysis patients characterized by this composite index as poorly compliant had shortened survival. 相似文献
5.
González Roberto Cortéz; Biever Joan L.; Gardner Glen T. 《Canadian Metallurgical Quarterly》1994,31(3):515
Discusses the theoretical and clinical applications of the postmodern paradigm of social constructionism as a basis for counseling culturally different clients. Such applications avoid the trap of perpetuating the status-quo when working with minority and marginalized clientele. The main points of multiculturalism and social constructionism are summarized, and issues of mutual concern to both perspectives are examined. Applications to psychotherapy are explored, and the challenges of applying the social constructionist approach to culturally competent counseling are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
The fabric and faces of threat, and the expediency and efficiency in the communication of threat, are examined with a threat appraisal model. This model is empirically tested on an ongoing communication challenge, the issuance of terror alerts by the United States' Department of Homeland Security (DHS), focusing on how threat is appraised by both the conservative and liberal audiences. Findings showed a shared view by the DHS and conservative audiences on the levels and nature of threats; liberal audiences thought otherwise. Though there appeared to be a consensus between the conservative and liberal audiences on the efficacy of threat communication, more internal consistency within DHS is needed to optimise its effectiveness. 相似文献
7.
Fifty-six fourth-grade children participated in this study to assess three training procedures for relative effectiveness in acquiring fire emergency skills and attaining knowledge. The first training approach was behavioral, the second used animated graphics, and the third used still graphics. Each of the training groups was compared to a control group that received no treatment. Performance on dependent measures was assessed before and immediately after training. It was hypothesized that the behavioral and animated-graphics conditions would produce the greatest level of skill and knowledge acquisition. Results demonstrated a significantly higher level of fire emergency skill acquisition and knowledge attainment for both the behavioral and animated-graphics groups relative to the still-graphics group and the control group, which had no training. The value of using computer-mediated strategies for fire-safety skills training was demonstrated. 相似文献
8.
Spontaneous regression of AK-5, a histiocytic tumor, is mediated by CD3-, CD8+ NK cells through ADCC. The onset of AK-5 regression is associated with the induction of humoral immune response and the augmentation of effector function. The mechanism of tumor cell death involves both necrosis and apoptosis. Interleukin-12, a 75-kDa heterodimeric cytokine, has multiple effects on T and NK cells. We have investigated the role of IL-12 in the NK cell-mediated AK-5 tumor regression process. Subcutaneous transplantation of AK-5 tumor induced the expression of IL-12 (p35 and p40) message by Day 6-8 in the splenocytes of syngenic rats. Similarly, analysis of serum samples from tumor-bearing animals showed the presence of circulating IL-12 around the same time. Interaction of immune cells with antibody-tagged AK-5 cells in vitro also triggered the expression of IL-12 message and protein by 3 hr. The circulating IL-12 in the sera of tumor-rejecting animals, as well as rIL-12, stimulated NK cell proliferation, expression of CD16 and CD25, and the activation of NK cells function. These observations suggest that the ability of the AK-5 tumor to induce the endogenous production of IL-12 may be responsible for keeping the NK cells constantly in an activated state, thus demonstrating an efficient mechanism for the complete regression of the tumor. 相似文献
9.
Preparation of Silicon Carbide/Aluminum Nitride Ceramics Using Organometallic Precursors 总被引:1,自引:0,他引:1
Corinna L. Czekaj Michael L. J. Hackney William J. Hurley Jr. Leonard V. Interrante Gary A. Sigel Paul J. Schields Glen A. Slack 《Journal of the American Ceramic Society》1990,73(2):352-357
Solid solutions of 2H -SiC/AlN can be prepared at temperatures less than 1600°C by rapid pyrolysis ("hot drop") of mixtures of [(Me3 Si)0.80 ((CH2 =CH)MeSi)1.0 (MeHSi)0.35 ] n (VPS) or [MeHSiCH2 ] n (MPCS) with [R2 AlNH2 ]3 , where R=Et, i -Bu or simply by slow pyrolysis of the precursor mixture in the case of [Et2 AlNH2 ]3 . In contrast, slow pyrolysis of mixtures of VPS or MPCS with [ i -Bu2 AlNH2 ]3 yields a composite of 2 H -AlN and 3 C -SiC at 1600°C, which transforms into a single 2 H -SiC/AlN solid solution on heating to 2000°C. The influences of the nature of the precursor and processing conditions on the structure, composition, and purity of the SiC/AlN materials are discussed. 相似文献
10.
A new method is presented for determining thecis/trans isomer content of edible vegetable oils. The intensities of Raman lines near 1656 and 1670 cm−1 are associated with thecis andtrans configuration, respectively. A precision of ca. 1% can be obtained in thecis/trans isomer analysis of binary mixtures of methyl esters and triglycerides of monoenes and dienes and of hydrogenated vegetable
oils. The spectroscopic data also provide the iodine value of vegetable oils or isolated fractions with precision for a single
determination of ca. 1%.
Presented at the AOCS meeting, Houston, May 1971.
W. Market. Nutr. Res. Div., ARS, USDA. 相似文献