Growth of arrays of oriented epitaxial platinum nanoparticles with controlled size and shape by natural colloidal lithography

We developed a method for production of arrays of platinum nanocrystals of controlled size and shape using templates from ordered silica bead monolayers. Silica beads with nominal sizes of 150 and 450 nm were self-assembled into monolayers over strontium titanate single crystal substrates. The monolayers were used as shadow masks for platinum metal deposition on the substrate using the three-step evaporation technique. Produced arrays of epitaxial platinum islands were transformed into nanocrystals by annealing in a quartz tube in nitrogen flow. The shape of particles is determined by the substrate crystallography, while the size of the particles and their spacing are controlled by the size of the silica beads in the monolayer mask. As a proof of concept, arrays of platinum nanocrystals of cubooctahedral shape were prepared on (100) strontium titanate substrates. The nanocrystal arrays were characterized by atomic force microscopy, scanning electron microscopy, and synchrotron X-ray diffraction techniques.     

Durability assessment of alkali activated slag (AAS) concrete

The environmental impact from the production of cement has prompted research into the development of concretes using 100% replacement materials activated by alkali solutions. This paper reports research into the durability of AAS concrete. The durability properties of AAS have been studied for a range of sodium oxide dosages and activator modulus. Properties investigated have included measurements of workability, compressive strength, water sorptivity, depth of carbonation and rapid chloride permeability. Microstructure studies have been conducted using scanning electron microscopy and energy dispersive X-ray spectroscopy. It was concluded that an activator modulus of between 1.0 and 1.25 was identified as providing the optimum performance for a sodium oxide dosage of 5% and that AAS concretes can exhibit comparable strength to concrete currently produced using Portland cement (PC) and blended cements. However, with regards to the durability properties such as water sorptivity, chloride and carbonation resistance; the AAS concretes exhibited lower durability properties than PC and blended concretes. This, in part, can be attributed to surface microcracking in the AAS concretes.     

Navigational Measures for Managing Defective Designs

Defective designs have been acknowledged as important risks in construction projects. For effective management of these risks, it is important to understand how and why the defects happen. Part of an ongoing research program, this paper aims to propose two navigational measures, with an emphasis on human elements, for managing defective designs. It starts with outlining a mechanism of defective designs causation based on the systems approach to human errors as the basis of the two measures. The first measure is a reactive measure, which works as an investigative tool after defective designs occurrence. It is proposed to give step-by-step guidance in the identification of primary causes of past defect events. The second measure is proactive process measure, which is intended to operate prior to occurrences of defective design. It periodically assesses influencing factors and indicates those most needing correction. A guideline for practical use of the measures is presented in the paper. At the center of the discussion, critical roles of management at higher levels are kept in mind.     

基于离线优化和在线决策的光伏智能楼宇能量管理算法

作为综合能源的重要发展形态，光伏智能楼宇的用电需求及光功率具有极大的不确定性，现有的能量管理方法很难完全适用，因此提出了基于离线优化和在线决策的光伏智能楼宇能量管理算法。首先，结合光伏智能楼宇的历史运行数据，建立了以运营收益最大化为目标的离线优化模型，通过离线优化为在线学习提供知识库；其次，为了实现分时电价条件下光伏智能楼宇的实时调度，建立了在线学习与认知规则相结合的在线决策算法，实时决策电动汽车充电功率以及可平移负荷的工作状况；最后，以某商业楼宇为例进行了仿真测试，结果表明所提算法在未来光功率、充电需求及可平移负荷未知的情况下具有良好的运行效果。     

Highly Stable n–i–p Structured Formamidinium Tin Triiodide Solar Cells through the Stabilization of Surface Sn2+ Cations

Improving the performance, reproducibility, and stability of Sn-based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li-TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn-based PSC, Sn²⁺ is easily oxidized to Sn⁴⁺ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI₃)-based PSCs fabricated using DPI-TPFB [4-Isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li-TFSI are reported as a dopant in Spiro-OMeTAD. The DPI-TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI₃-based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI-TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn²⁺ through coordination with Sn²⁺ on the surface of FASnI₃.     

Modeling and analysis for the development of Lightweight Piezoceramic Composite Actuators (LIPCA)

This paper focuses on the modeling and analysis of Lightweight Piezoceramic Composite Actuators (LIPCA) for developmental purposes. A simple analytical model and a numerical model for predicting the displacement of the actuators due to both an applied input voltage and transverse load to the piezoelectric ceramic layer are presented. The analytical model describing the laminated beam actuation results in two primary design parameters, an actuation coefficient of a laminated beam C_ulb and the bending stiffness of a laminated beam EI_lb. The C_ulb is a parameter when maximum displacement is required. The bending stiffness affects the displacement performance when a transverse load is applied to the actuators. An experiment was performed to verify the proposed laminated beam model. The numerical model, a NASTRAN finite element model, is used to assess the effect of initial dome heights of actuators on the displacement. An increase in the initial dome height produces a positive effect for the low anisotropic actuators and gives a negative effect for the high anisotropic actuators. In conclusion, the results indicate that designing to maximize the C_ulb, the EI_lb, and the initial dome height of the low anisotropic actuators could generate LIPCA-type actuators with larger displacement and higher force.     

A thioacetamide interlayer anchoring TiO2 and (FAPbI3)1−x(MAPbBr3)x for high-performance perovskite solar cells

In the perovskite solar cells (PSCs), traps of the perovskite film or interface are the research focus, which can severely hinder charge transfer and benefit charge recombination, thus weakening the photoelectric performance of the devices. Herein, a Thioacetamide (TAA) interfacial layer is used to passivate the traps of PSCs. Comparing to the control device (17.65%), the TAA-based solar cells can achieve an enhanced efficiency of 19.14%. It is found that the passivation caused by TAA occurs through the interactions of sulfur in TAA with undersaturated Pb in perovskite and Ti⁴⁺ in TiO₂, resulting in a faster and more efficient charge transfer and a greatly reduced trap density from 3.36 × 10¹⁶ cm⁻³ to 1.93 × 10¹⁶ cm⁻³. It is shown that the modification method using TAA may be helpful for passivating traps and obtaining excellent photoelectric properties of PSCs.     

Development of humoral immunity system of the small bowel

The study was performed in 24 children aged 2 months to 6 years, without intestinal or immunological diseases. Intestinal biopsies were obtained by a Crosby's capsule, pediatric size. The number of immunoglobulin forming cells of lamina propria was measured by planimetry. Under 12 months of age there are increased levels of IgM forming cells and a low IgA forming cells/IgM forming cells quotient, but over 1 year the difference disappears. This suggests that the maturity process is very rapid. There are no correlation between serum IgA, IgM, and IgG levels and its respective forming cells number of lamina propria. It seems to support that the participation of intestinal lymphoid tissue in serum pool of immunoglobulin is very poor and that systemic and intestinal immunity maturation are completely independent.     

Preparation of anthocyanin-rich mulberry juice by microwave-ultrasonic combined pretreatment

Food Science and Biotechnology - The work aims to study the process of microwave-ultrasonic combined treatment to obtain anthocyanin-rich mulberry juice. A Box-Behnken design was employed to...     

An ultra-tough,creep-resistant,wear-resistant hydrogel for cartilage replacement

As a load-bearing tissue, natural cartilages possess a compressive stress above 50 MPa, a water content around 60%, and a friction coefficient (FC) less than 0.1, which remains difficult for synthetic materials to realize. Herein, a facile strategy was reported to achieve this goal. The hydrogel was obtained through a three-step strategy from polyvinyl alcohol (PVA), chitosan (CS), sodium carboxymethyl cellulose (CMC-Na), lecithin (LS), and deionized water. First, freezing–thawing the aqueous solution of PVA and CS three times generated the precursor gel. Second, immersing it in aqueous solution of CMC-Na to form multiple linkages (hydrogen bonds, ionic interactions, and crystallize domains). Third, it was coated with LS to form a lubrication layer. Due to the synergy of dynamic interactions, the compressive stress was 115 MPa, superior to most tough hydrogels. Owing to existence of LS, the FC was 0.03, better than the requirement for artificial cartilage. Remarkably, the FC remained stable within 50,000 wear cycles. On account of the reversible break/reformation of physical linkages, the creep recovery efficiency was 93%. The raw materials are all biocompatible and the fabrication process exclude the adoption of toxic additives. All of these features make it an ideal material for cartilage replacement.