热集成变压精馏分离乙二胺-水共沸体系的模拟优化

针对乙二胺-水共沸物组成对压力较为敏感的特性,采用部分热集成变压精馏工艺分离该共沸物。先利用Aspen Plus软件对该工艺进行稳态模拟,再以理论塔板数、进料位置、回流比为优化变量,水和乙二胺的纯度为约束,以年度总费用（total annual cost,TAC）为目标函数建立乙二胺-水共沸体系分离系统的优化设计模型。采用列队竞争算法对该分离过程主要工艺参数进行优化,得到了变压精馏分离乙二胺-水体系的最佳工艺操作参数及设备参数。模拟结果表明,利用算法对多变量进行同时优化可得到更具经济效益的分离系统,与传统优化结果相比,可降低TAC约7.31%。在此基础上,对高压塔的操作压力进行优化分析,将其由2atm提升至4atm（1atm=101325Pa）,并对流程其他参数进行优化,可显著降低TAC约24.62%。进一步,采用部分热集成比普通变压双塔精馏降低TAC约21.87%     

钯催化H2O2分解的机制探讨

高放废物（HLW）处置库近场地下水的辐解能够产生H₂O₂,其被裂变产物合金颗粒（ε-颗粒）的催化分解属于多相表界面反应。本工作选用钯粉模拟ε-颗粒,采用高压反应釜研究体系总压和H₂分压对反应的影响,并按一级动力学模型拟合实验数据。添加HO·的捕获剂和淬灭剂的实验证明无H₂反应过程中存在HO·的生成步骤。钯的催化活性及形态变化与反应时间的关系表明,产物氧吸附在钯的表面对反应具有毒化作用。通过持续监测滤液中H₂O₂浓度的变化,发现溶液中存在类似于Haber-Weiss的反应持续消耗H₂O₂。推导出钯对H₂O₂分解的机制过程和影响因素,为处置库的安全评估提供基础数据。     

Coating porous silica by in situ polymerization of peo macromonomers for size exclusion separation of proteins

A coating method using comb-like polymers with poly(ethylene oxide) (PEO) grafts is described and studied in order to use porous silica as phase in size exclusion chromatography (SEC) of proteins. The coating is carried out by in situ polymerization and crosslinking of methacrylates of PEO with OH end groups (macromonomers) after deposition from a solution. A series of phases was prepared using two different graft lengths and two different crosslinking agents in different proportions. The efficiency of the coatings to mask the silanol groups of the matrix is characterized by pH metric titration and the best coating conditions are deduced. From calibration with PEO standards and with proteins, the SEC behavior of each phase is analyzed from column experiments and compared to results of pH metric measurements. A close interdependence between the two methods is observed. The optimized phases exhibit very good performance in SEC, except with low molecular weight basic proteins which interact with some residual unmasked silanol groups. The presence of these groups is attributed to the intrinsic porosity of the polymeric layer which increases with the length of the grafts.     

Improved H2-generation performance of Pt/CdS photocatalyst by a dual-function TiO2 mediator for effective electron transfer and hole blocking

Surface modification with noble metal cocatalysts was proved to be a useful route for boosting photocatalytic efficiency of various photocatalysts. Nevertheless, considering the random dispersion of metallic cocatalysts on the photocatalyst surface, the noble metal-loaded photocatalyst generally shows a limited enhancement of its activity because the noble metals can also work as the recombination sites of photoinduced charges. In this paper, TiO₂ as a dual-function mediator (for effective electron transport and hole block) is successfully introduced into the interface of Pt and CdS to form PtTiO₂/CdS photocatalyst, with an aim of suppressing the high recombination rate of electron-hole pairs on the Pt active sites. Under visible light, all the prepared PtTiO₂/CdS displayed distinctly enhanced photocatalytic hydrogen-generation performance and the PtTiO₂/CdS(8%) attains the highest photocatalytic H₂-production rate (294.2?μmol/h), a value significantly higher than that of Pt/CdS about 3.2 time. A dual-function TiO₂-mediated mechanism was put forward to account for the superior hydrogen production of PtTiO₂/CdS photocatalyst, namely, the TiO₂ layer in the PtTiO₂/CdS not only works as electron-transport layers to effectively transfer photogenerated electrons to promote the H₂-production reaction on Pt cocatalysts, but also acts as hole-block layer to prevent the possible recombination of photogenerated charges on the Pt active sites, resulting in a distinct improvement of final H₂-generation activity.     

Controlled-surfactant-directed solvothermal synthesis of γ-Al2O3 nanorods through a boehmite precursor route

Ceramic one-dimensional particles are fascinating nanomaterials for sustainable future industries. Nanorods of γ-Al₂O₃ with single crystallinity and 10 nm diameter regime were newly developed through solvothermal procedure between AlCl₃·6H₂O, NaOH, and sodium dodecylbenzene sulfonate at 200 °C for 24 h. Controlling the pH values, reaction time, temperature, and effect of surfactant during the solvothermal reaction was studied to control the morphology and structure of nanorods. The solvothermal procedure for preparing γ-AlOOH nanorods followed lamellar growth, assembly, and ripening routes. The γ-AlOOH nanorods were converted to γ-Al₂O₃ through calcination reaction at 500 °C for 3 h. The produced γ-Al₂O₃ nanorods were 10 nm average width, 100–200 nm average length, and exposed with [101] orientation and a linear structure. FTIR, HRTEM, FESEM, XRD, and X-ray photoelectron spectroscopy methods were used for characterizing the prepared nanomaterials. New features and applied fields are predictable for the designed γ-AlOOH and γ-Al₂O₃ nanorods.     

多因素不确定条件下的间歇生产调度优化

不确定条件下的间歇生产调度优化是生产调度问题研究中具有挑战性的课题。提出了一种基于混合整数线性规划(MILP)的鲁棒优化模型,来优化不确定条件下的生产调度决策。考虑到生产过程中的操作成本和原料成本,建立了以净利润最大为调度目标的确定性数学模型。然后考虑需求、处理时间、市场价格三种不确定因素,建立可调整保守程度的鲁棒优化模型并转换成鲁棒对应模型。实例结果表明,鲁棒优化的间歇生产调度模型较确定性模型利润减少,但生产任务数量增加,设备空闲时间缩短,从而增强了调度方案的可靠性,实现了不确定条件下生产操作性和经济性的综合优化。     

Soft gallstone-crushing robots

The current treatment for symptomatic gallstones is primarily surgical, where one of the most general surgeries, laparoscopic cholecystectomy, is the excision of the gallbladder to remove gallstones. However, postoperative site infections are a common health risk. As a result, scientists are investigating non-invasive methods to crush gallstones, but to date there are limited reports on such approaches. Herein, we propose a non-invasive lithotripsy method that uses ferromagnetic, spiny, flexible, and wireless medical robots, that can be taken orally into the human body bio-safely, to achieve efficient crushing of human gallstones. After operating for 30 minutes, a human gallstone of about 1 cm in diameter had been crushed into a pile of powdered gallstone residue by three soft gallstone-crushing robots in a pig gallbladder. The work highlights that our designed soft robot provides a promising pathway for non-invasive treatment of human gallstones disease, which brings new insights for future advancement of soft medical robots.     

Roll-to-roll processable MXene-rGO-PVA composite films with enhanced mechanical properties and environmental stability for electromagnetic interference shielding

MXene films promise potential electromagnetic interference (EMI) shielding materials, but poor scalable processability, environmental instability, and weak mechanical properties severely restrict their applications. Herein, we engineer the large-area, high-performance, and compact nacre-like MXene-based composite films through cooperative co-assembly of Ti₃C₂T_X MXene and reduced graphene oxide (rGO) in the presence of polyvinyl alcohol (PVA). The resulting MXene-rGO-PVA composite films benefit from enhanced bonding strength and extra chain bridging effect of linear PVA molecules enriched with hydroxyl groups. Therefore, the composite film achieves high tensile strength (～238 MPa) and toughness (～1.72 MJ m^?3) while having high conductivity of ～32 S cm^?1. A significant EMI shielding effectiveness (41.35 dB) is also demonstrated, with an excellent absolute shielding effectiveness of ～20,200 dB cm² g^?1 at only 12-μm thickness. Moreover, due to the synergistic effect of multiple components, the composite films maintain a stable EMI shielding performance in harsh environments (sonication, hot/cold annealing, and acid solution) with mechanical properties that fluctuate only within 10% compared to the original film. More importantly, commercial polyethylene terephthalate release liner can be applied for the film coating, facilitating continuous roll-to-roll production of large-area films and future applications.     

The devolution of urban food waste governance: Case study of food rescue in Los Angeles

In Los Angeles (LA), food waste is at record levels. This has negative outcomes for food insecurity, land use, and methane production associated with climate change. To overcome these challenges, a range of government, private, and civil society organizations (CSOs) have developed programs to reduce food waste. With the decentralization, privatization, and devolution of food waste policies to local actors, CSOs have emerged as key institutions in the governance of food waste in many contexts. However, it is unclear whether CSOs have the capacity to reduce food waste and food insecurity, empower communities, or promote social change. To this end, this paper critically analyzes a local food rescue CSO as a case study in order to understand the challenges associated with food waste governance in LA and the roles that CSOs play in food waste reduction. Through an analysis of interview and participant observation data in LA’s food system, this paper examines the ways that food waste is produced, regulated, and reused by institutions in LA. Findings illustrate that although local CSOs have expanded their food waste reduction programs, the impact of their operations may be limited. In addition, while CSOs rescue some food, they operate in conjunction with food waste surpluses and the overabundance of food, and do little to reduce the root cause of food waste or food insecurity. Although the structural causes of food waste are arguably beyond the scope of some CSOs to change, data in this paper suggest that some CSOs may contribute indirectly to neoliberal governance when they romanticize the power of local communities, depoliticize food issues, and focus on individual personal responsibility. For these reasons, this research suggests that food waste may only be reduced significantly with more government regulation of the institutions which produce food waste, namely food businesses and households.