Analytical Modeling for Translating Statistical Changes to Circuit Variability by Ultra-Deep Submicron Digital Circuit Design

This paper presents a physics-based compact gate delay model that includes all short-channel phenomena prevalent at the ultra-deep submicron technology node of 32 nm. To simplify calculations, the proposed model is connected to a compact α-power law-based (Sakurai-Newton) model. The model has been tested on a wide range of supply voltages. The model accurately predicts nominal delays and the delays under process variations. It has been shown that at lower technology nodes, the delay is more sensitive to threshold voltage variations, specifically at the sub-threshold operating region as compared with effective channel length variations above the threshold region.     

Revealing Nanomechanical Domains and Their Transient Behavior in Mixed-Halide Perovskite Films

Halide perovskites are a versatile class of semiconductors employed for high performance emerging optoelectronic devices, including flexoelectric systems, yet the influence of their ionic nature on their mechanical behavior is still to be understood. Here, a combination of atomic-force, optical, and compositional X-ray microscopy techniques is employed to shed light on the mechanical properties of halide perovskite films at the nanoscale. Mechanical domains within and between morphological grains, enclosed by mechanical boundaries of higher Young's Modulus (YM) than the bulk parent material, are revealed. These mechanical boundaries are associated with the presence of bromide-rich clusters as visualized by nano-X-ray fluorescence mapping. Stiffer regions are specifically selectively modified upon light soaking the sample, resulting in an overall homogenization of the mechanical properties toward the bulk YM. This behavior is attributed to light-induced ion migration processes that homogenize the local chemical distribution, which is accompanied by photobrightening of the photoluminescence within the same region. This work highlights critical links between mechanical, chemical, and optoelectronic characteristics in this family of perovskites, and demonstrates the potential of combinational imaging studies to understand and design halide perovskite films for emerging applications such as photoflexoelectricity.     

Resolving Deep Sub-Wavelength Scattering of Nanoscale Sidewalls Using Parametric Microscopy

The quantitative optical measurement of deep sub-wavelength features with sub-nanometer sensitivity addresses the measurement challenge in the semiconductor fabrication process. Optical scatterings from the sidewalls of patterned devices reveal abundant structural and material information. We demonstrated a parametric indirect microscopic imaging (PIMI) technique that enables recovery of the profile of wavelength-scale objects with deep sub-wavelength resolution, based on measuring and filtering the variations of far-field scattering intensities when the illumination was modulated. The finite-difference time-domain (FDTD) numerical simulation was performed, and the experimental results were compared with atomic force microscopic (AFM) images to verify the resolution improvement achieved with PIMI. This work may provide a new approach to exploring the detailed structure and material properties of sidewalls and edges in semiconductor-patterned devices with enhanced contrast and resolution, compared with using the conventional optical microscopy, while retaining its advantage of a wide field of view and relatively low cost.     

纳米零价铁材料对放射性核素的 去除及机理研究进展

随着人类社会的发展，放射性铀矿的开采和使用越来越多，环境面临着越来越严重的放射性污染问题。从生物和环境的角度来看，有效地清除环境中的放射性核素是核能利用过程中最重要的问题之一。纳米零价铁（nanoscale zero valent iron, nZVI）具有较大的比表面积和较高的活性位点，能显著提高放射性污染物的修复效率。本综述的目的是展示nZVI基材料对放射性核素的高效去除能力和环境修复作用。简介了常用的nZVI基材料（表面改性或多孔材料支撑的nZVI材料）及其对放射性核素的去除效果和相互作用机制（如吸附和氧化还原）。最后，对nZVI材料的应用和挑战给出个人见解。本综述有助于为高效去除放射性核素的nZVI材料的设计指明方向，为放射性核素的高效处理处置提供新材料。     

Microtopography‐Guided Radial Gradient Circle Array Film with Nanoscale Resolution

Distribution of multimaterials at arbitrary positions with nanoscale resolution and over a large area substrate is essential to future advances in functional graded materials. Such stringent requirements are highly beyond the reach of current techniques, although newly developed 3D printing technologies are addressed. Here, a radial gradient circle array film with the distribution accuracy up to ≈18 nm is fabricated by using microtopographic substrate. A mathematical model is developed to guide the distribution of position, size, shape, and type of materials on an arbitrary section for the given morphology of substrate. The periodic electrical and mechanical properties of the radial gradient circle film are identified, which can be beneficial for further functionalization and applications, such as gradient refractive index lenses, microcoils, and microantennas.     

Analytical attractive functions and their derivatives in bulk and nanoconfined pores

In this paper, two new analytical attractive (alpha) functions and their derivatives in bulk and nanoconfined pores are developed based on the virial equation of state (EOS) and statistical thermodynamics and are evaluated at different conditions for the first time. A cubic EOS is modified to nanometer scale and applied to predict the thermodynamic and phase properties in bulk and nanoconfined pores coupled with the new analytical alpha functions. The nanoscale-extended EOS coupled with the analytical alpha functions are validated to be accurate by means of the experimental data for the thermodynamic and phase calculations. The alpha functions and dimensionless attractive term A for the O₂, Ar, CO₂, N₂, and C₁-C₁₀ are always positive and monotonically decrease with the temperature increases at T ≤ 2000 K in the bulk phase, whereas the second virial coefficients (B₂) are always negative and increase with the temperature increases. Moreover, the alpha functions, A, and B₂ for all of components remain constant with the decreasing pore radius until r_p = 50 nm, the former two of which decrease while the latter one increases by further reducing the pore radius. It should be noted that the intermolecular attractive force (ie, A) is a function of the pressure, which is gradually increased at P ≤ 10 MPa though drastically increases afterwards. Also, the enhanced confinement effects lead the same-component intermolecular attractive forces to be smaller. The analytical formulations in the SRK type slightly outperform in the gaseous or light component cases, while those in the PR type are better for the heavy component cases in terms of the thermodynamic property calculations, both of which are compatible with the modified EOS and analytical alpha functions.     

聚氨酯防水涂料的发展

聚氨酯涂料因其优异的防水性能,已广泛应用于建筑领域。介绍了我国聚氨酯防水涂料的现状。简单总结了聚氨酯防水涂料组成、分类和今后的发展趋势。     

超声作用联合纳米腐植酸处理苯酚废水

采用静态吸附法研究了超声联合纳米腐植酸处理苯酚废水;用红外光谱(FT-IR)、扫描电镜(SEM)、比表面积测试仪(BET)对纳米腐植酸的粒径大小、形貌、比表面积及孔径等进行表征,结果表明:纳米腐植酸粒度分布均匀,平均粒径为50 nm,比表面积为110.31 m2/g,孔径为6.56 nm;考察了苯酚初始浓度、纳米腐植酸用量、超声声强及频率等因素对纳米腐植酸和超声作用协同处理苯酚废水的最佳工艺条件。实验结果表明:超声频率为20 kHz,超声声强0.2 W/cm2,苯酚初始质量浓度为100 mg/L,pH值为6.0,溶液体积100 mL,吸附温度40℃,吸附时间120min,纳米腐植酸用量为40 g/L的条件下,纳米腐植酸与超声作用协同处理苯酚废水吸附率可以达到95.7%;吸附剂纳米腐植酸对苯酚的吸附主要受颗粒内扩散所控,其再生循环使用5次后,苯酚的吸附容量仅减少18.9%。     

不同pH环境下CMS改性纳米铁在异质多孔介质中的迁移

纳米铁在污染土壤和地下水的修复中受到广泛关注。为进一步探究其在多孔介质的迁移行为，本研究采用羧甲基淀粉钠（CMS）对纳米零价铁（nZVI）进行包覆，进行了改性纳米零价铁的沉降试验，测量zeta电位与粒径分布探究其分散性；进行了不同pH条件下改性纳米零价铁在酸洗砂与水洗砂的柱实验，分析了化学异质性与pH对纳米铁在多孔介质迁移的影响。结果表明，CMS包覆纳米铁不仅使纳米颗粒本身稳定，而且还减少其在多孔介质表面沉积，大大提高了迁移性。pH=6～8时，nZVI的zeta电位由18.3mV减小到2.9mV，有效粒径由685nm增大到880nm，稳定性变差；而CMS-nZVI的zeta电位值由-19.7mV增大到-53.5mV，颗粒间静电排斥力增强稳定性变好。经能量色散X射线光谱（EDS）分析，水洗砂表面存在碳、铝、铁等氧化物杂质，这些杂质带有正电荷，会增强与带负电的CMS-nZVI的吸附作用，不利于其迁移；而经过酸洗后的石英砂，其表面杂质大大减少，在pH=8时，CMS-nZVI在酸洗砂最大迁移率为77.0%要好于水洗砂的63.0%。此外较高pH环境有助于增加石英砂介质的表面负电荷，减少颗粒与介质的吸附，促进纳米颗粒的迁移。     

纳米铁的绿色合成及其在环境中的应用研究进展

纳米铁（零价铁及铁氧化物）比表面积大、还原能力强、反应活性高，是一种良好的环境功能材料。传统的纳米铁合成方法中，物理方法对反应所需仪器设备要求较高，化学方法使用的还原剂具有毒性，绿色合成方法能够有效克服传统方法的不足之处。本文首先根据合成途径、纳米铁的类型介绍了利用植物和微生物对纳米零价铁（nZVI）及纳米铁氧化物（IONPs）进行绿色合成的方法，同时论述了制备的纳米铁所表现的特征（如形貌、尺寸、聚集倾向、等电位点）。随后总结了纳米铁通过不同反应机制（吸附、还原、催化氧化）去除环境有机、无机污染物（染料、芳香族化合物、硝酸盐、重金属）的应用。最后指出了纳米铁在绿色合成与实际应用过程中存在的挑战性问题及解决方法，以期为纳米铁今后的深入研究和大规模的工业生产应用提供参考依据。