超光滑光学基底表面原子力显微镜测试方法

原子力显微镜(AFM)是评价亚纳米级表面粗糙度σRMS最主要的测试仪器,但其测试结果会因采样条件(采样间距、采样点数)及测量点位置变化而改变。以AFM测试超光滑光学基底随机表面为例,应用累积功率谱理论建立了确定合理采样条件的方法,避免了采样条件选取不当带来的数据丢失或冗余;通过全局优化选取测量点和局部优化选取测量点相结合,降低了样品表面区域性差异给测试结果带来的不确定性,并大大减少了获得可靠测试结果所需的测试量。上述工作为超光滑光学基底AFM测试提供了有效方案。     

Chemical characterzation of fine particle emissions from the fireplace combustion of woods grown in the Southern United States

The fireplace combustion of wood is a significant and largely unregulated source of fine particle pollution in the United States. Source apportionment techniques that use particulate organic compounds as tracers have been successful in determining the contribution of wood smoke to ambient fine particle levels in specific areas in California. To apply these techniques to the rest of the United States, the differences in emissions profiles between different wood smoke sources and fuel types should be resolved. To this end, a series of fireplace source tests was conducted on six fuel wood species found in the Southern United States to determine fine particulate emission factors for total mass, ionic and elemental species, elemental and organic carbon, and over 250 individual organic compounds. The wood species tested, chosen for their high abundance and availability in the Southern U.S. region, were yellow poplar, white ash, sweetgum, mockernut hickory, loblolly pine, and slash pine. The differences in the emissions of compounds such as substituted phenols and resin acids help to distinguish between the smoke from hardwood and softwood combustion. Levoglucosan, a cellulose pyrolysis product which may serve as a tracer for wood smoke in general, was quantified in the emissions from all the wood species burned. The furofuran lignan, yangambin, which was emitted in significant quantities from yellow poplar combustion and not detected in any of the other North American wood smokes, is a potential species-specific molecular tracer which may be useful in qualitatively identifying particulate emissions from a specific geographical area where yellow poplar is being burned.     

宽调谐室温Co∶MgF_2激光器

用双折射滤光片不同干涉级次和多组谐振腔镜连续调谐室温Co∶MgF2 激光器,波长调谐范围达到 170 0～2 5 5 0nm,在 2 0 90nm峰值波长的输出能量及效率分别为 115mJ和 16 %     

激光雷达高精度跟踪运动目标的方法研究

本文论述了卡尔曼滤波估值理论在激光雷达跟踪系统中的应用方法,首先建立目标和激光雷达测量值的数学模型;然后讨论了跟踪数学模型线性变换方法以及对滤波器精度的影响,在此基础上,提出了激光雷达跟踪运动目标时高精度的跟踪方法。     

30.4 nm Si/C多层膜反射镜的制备与测量

采用离子束溅射镀膜装置制备了一种新的材料组合Si/C多层膜 ,用于 30 4nm波段的正入射多层膜反射镜。并用软X射线反射率计测得其反射比最大值为 0 14。有效地抑制了 15 0nm处的二级衍射峰。     

Flux development for lead-free solders containing zinc

New lead-free solders containing zinc are promising candidates to replace near-eutectic tin-lead solders because the solders melt at lower temperatures than Sn-Ag-base solders. They also possess good mechanical and fatigue properties and are less expensive. However, the contact angle on copper for Sn-Zn solders is high when fluxes used for Sn-Pb solders are utilized. A novel approach for flux development to improve wetting of copper surfaces by tin-zinc eutectic solder was developed: tin containing organic compounds, which decomposes at soldering temperatures and produces metallic tin on surfaces to be soldered was added to several specially formulated fluxes. This process improves wetting of copper surfaces by molten tin-zinc eutectic solder. Fluxes were developed that give a contact angle as low as 20°.     

Flip chip underfill flow characteristics and prediction

This paper presents recent results on underfill flow characterization. The flow properties of a number of commercial and experimental underfills were recorded and analyzed using quartz test chips with specially designed bump patterns (e.g., peripheral, full array, and mixed designs). Each was bonded onto an organic laminate substrate to form a flip chip package. Underfill was then applied to the packages and flow time, filler settling, and air entrapment were evaluated. Good flow can be described in terms of three measurable parameters, namely, viscosity, contact angle, and more importantly, filler size and distribution. Viscosity and contact angle are commonly used in Hele Shaw and Washburn models. However, these models do not take filler properties into consideration. In general, underfills with particles less than 5 μm exhibited faster and more uniform flow fronts than materials with larger particles. The best flowing materials worked well with standoff heights between 50 and 75 μm, while the poorer flowing materials showed streaking, voiding, and fingering at these heights. At gaps of 25 μm, however, nearly all the materials exhibited pronounced and reproducible streaking     

Adult pertussis: a salesman''s dream--and an epidemiologist''s nightmare

In human neuroblastoma SH-SY5Y cells, treatment with immunosuppressants such as FK506, cyclosporin A or rapamycin for 4 days induced the enhancement of the 27-kDa Bcl-2alpha protein level. Among immunosuppressants, rapamycin has most potency. Treatment with herbimycin A or wortmannin also enhanced Bcl-2 expression, but the BB type of platelet-derived growth factor decreased the level. These results suggest that Bcl-2 expression is probably regulated by the cascade of tyrosine kinase, phosphatidylinositol 3-kinase and rapamycin-sensitive p70 S6-kinase in human neuroblastoma SH-SY5Y cells.     

Effect of plastic deformation on the coarsening of

Particle coarsening has been studied in a rapidly solidified Al-8.8 wt pct Fe-3.7 wt pct Ce alloy subjected to isothermal annealing for various times at 425 °C. The effect of static and dynamic loading on the particle coarsening rates at the same temperature also has been examined. The dispersed particles in all specimens of the present study are the equilibrium Al¹³Fe⁴ and Al¹⁰Fe²Ce phases. They are incoherent with the matrix and constitute 23 pct of the total volume. The coarsening rate in isothermally annealed specimens is orders of magnitude greater than predicted by the modified Lifshitz-Slyozov-Wagner theory for volume diffusion controlled coarsening but can be explained using Kirchner’s model for coarsening by diffusion along grain boundaries. In the case of intragranular particles, coarsening by diffusion along dislocation cores also is likely to be significant. Creep loading is seen to cause a significant enhancement of the coarsening rate. Fatigue testing with a hold period at the maximum tensile stress also accelerates coarsening whereas continuous cycling appears initially to retard the increase in the average particle size. Dislocations connecting dispersed phase particles are observed more frequently in crept specimens and specimens fatigued with a hold period than in specimens fatigued with no hold period. The effects of plastic deformation on particle coarsening rates are discussed in terms of excess vacancy generation, short circuiting along dislocations, and fine precipitation during fatigue.     

Valuating privacy

In several experimental auctions, participants put a dollar value on private information before revealing it to a group. An analysis of results show that a trait's desirability in relation to the group played a key role in the amount people demanded to publicize private information. Because people can easily obtain, aggregate, and disperse personal data electronically, privacy is a central concern in the information age. This concern is clear in relation to financial data and genetic information, both of which can lead to identity abuse and discrimination. However, other relatively harmless information can also be abused, including a person's gender, salary, age, marital status, or shopping preferences. What's unclear is whether it's the fear of such abuse that actually causes people's stated hesitance to reveal their data. Our hypothesis - and the motivation for our study - is that people reveal information when they feel that they're somewhat typical or positively atypical compared to the target group. To test this hypothesis, we conducted experiments that elicit the value people place on their private data. We found, with great significance (more than 95 percent statistical confidence) that a linear relationship exists between an individual's belief about a trait and the value he or she places on it. That is, the less desirable the trait, the greater the price a person demands for releasing the information. Furthermore, we found that small deviations in a socially positive direction are associated with a lower asking price.