陕西省蔬菜中稀土元素的含量特征及评价

目的 调查陕西省蔬菜中稀土含量水平,并评估其对人体健康的影响。方法 采用微波消解-电感耦合等离子体质谱法测定蔬菜中16种稀土元素含量。以GB 2762-2005《食品中污染物限量》为标准对蔬菜中稀土含量进行评价。采用点评估法计算陕西省居民通过蔬菜摄入稀土含量。结果 陕西省蔬菜中稀土氧化物均值为0.274 1 mg/kg,含量范围在0.003 3~2.661 8mg/kg。不同种类蔬菜的稀土污染情况存在显著差异,叶菜类、鳞茎类稀土超标率分别为19.6%和17.4%,其余类别蔬菜均未超标。单因子污染指数评价结果叶菜类为警戒线、尚清洁,其余各类蔬菜均为安全、清洁。16种稀土元素在蔬菜中含量差异较大,铈、钕、镧、钇含量高,表现为轻稀土相对富集。陕西省居民通过蔬菜摄入稀土氧化物的含量均值为67.10μg/d,占ADI的比例为1.60%。结论 陕西省蔬菜存在一定的稀土污染情况,居民通过蔬菜摄入稀土的量是安全的。     

《临证指南医案》“木乘土门”特色探微

通过分析《临证指南医案》"木乘土门"中的医案,根据木与土的生理联系,总结出胃病与肝的相关性以及叶氏从肝论治胃病的独特经验。其在肝胃同调的基础上,根据邪正盛衰、标本虚实等进行加减;用药顺应脏腑生理特性,以恢复脏腑功能为首要。     

稀土元素La、Gd和Ce对培养大鼠细胞生物学效应的研究

目的 在细胞水平上研究稀土元素（REE）La,Gd和Ce对培养大鼠细胞的生物学作用及机。方法 采用同位素示踪、质子激发X荧光分析（PIXE）结合生化及细胞学等技术观察La对细胞的生物学作用,La,Gd及Ce的亚细胞分布及Gd,Ce对细胞钙含量及钙内流的影响。结果 La^3 在10^－10（或10^-9)-10^-6mol/L时促进细胞蛋白质合成、线粒体琥珀酸脱氢酶活性增加、DNA合成以及S期细胞比率增加,但La^2 在高剂量时（10^-4-10^-3mol/L)降低平滑肌细胞总蛋白质含量、抑制线粒体琥珀酸脱氢酶酸活性以及S期细胞比率减少。通过PIXE发现La,Gd,Ce可进入细胞,且在核内含量最高,其次为胞膜。Gd和Ce使细胞内钙含量增加,促进细胞钙内流。结论（1）La^3 对细胞有明显剂量－效应关系,在10^-10(或10^-19)-10^-6mol/L剂量范围内有促进细胞增殖作用。在10^-4-10^-3mol/L时有细胞毒性作用。（2）REE可进入细胞,且在核内富集。（3）REE可促进细胞外钙进入细胞。     

含稀土有机复混肥的研制及其在甘蔗上的应用研究

在考虑土壤肥力、甘蔗营养特性的基础上,研制出含有改性配方稀土、甘蔗滤泥和氮、磷、钾的甘蔗专用肥。３年９个大田试验的平均结果表明：甘蔗施用含稀土有机复混肥后,平均产量为８８ ６８０ ｋｇ／ｈｍ２,平均田间锤度为 １９． ８％,理论产糖量平均为 １０ ５３０ ｋｇ／ｈｍ２,比不含稀土,但含等量氮、磷、钾、有机质的有机复混肥增产 ８ ４１５ ｋｇ／ｈｍ２,增产率为１０．５％,田间锤度提高１％,增糖１６．４％。     

Schiff碱稀土金属配合物对辐射导致肿瘤细胞DNA损伤及？…

的　Schiff碱具有抗瘤抑菌活性 ,其抗癌作用与其对肿瘤细胞DNA的破坏有关。方法　利用脉冲电场凝胶电泳 (PFGE)的方法 ,观察了某种Schiff碱稀土金属化合物对肿瘤细胞DNA双链断裂及修复的影响。结果　该化合物能够增加辐射导致的DNA双链断裂的生成 ,并抑制其修复。结论　Schiff碱稀土金属配合物能提高肿瘤细胞对辐射的敏感性 ,为开发放化疗修饰剂提供了新的研究方向     

Schiff碱稀土金属配合物对辐射导致肿瘤细胞DNA损伤及修复的影响

目的 Schiff碱具有抗瘤抑菌活性, 其抗癌作用与其对肿瘤细胞DNA的破坏有关。方法 利用脉冲电场凝胶电泳(PFGE)的方法, 观察了某种Schiff碱稀土金属化合物对肿瘤细胞DNA双链断裂及修复的影响。结果 该化合物能够增加辐射导致的DNA双链断裂的生成, 并抑制其修复。结论 Schiff碱稀土金属配合物能提高肿瘤细胞对辐射的敏感性, 为开发放化疗修饰剂提供了新的研究方向。     

Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to the atmosphere are reduced. Furthermore, the abrupt reduction in emissions during the lockdown periods led to clearly observable changes in atmospheric composition, which provide direct insight into feedbacks between the Earth system and human activity. While air pollutants and greenhouse gases share many common anthropogenic sources, there is a sharp difference in the response of their atmospheric concentrations to COVID-19 emissions changes, due in large part to their different lifetimes. Here, we discuss several key takeaways from modeling and observational studies. First, despite dramatic declines in mobility and associated vehicular emissions, the atmospheric growth rates of greenhouse gases were not slowed, in part due to decreased ocean uptake of CO₂ and a likely increase in CH₄ lifetime from reduced NO_x emissions. Second, the response of O₃ to decreased NO_x emissions showed significant spatial and temporal variability, due to differing chemical regimes around the world. Finally, the overall response of atmospheric composition to emissions changes is heavily modulated by factors including carbon-cycle feedbacks to CH₄ and CO₂, background pollutant levels, the timing and location of emissions changes, and climate feedbacks on air quality, such as wildfires and the ozone climate penalty.

The effects of the COVID-19 pandemic and associated lockdown measures have provided a way to observationally test predictions of future atmospheric composition. This is illustrated conceptually in Fig. 1. With many people working from home and limiting travel, the pandemic caused a significant decrease in anthropogenic emissions. These emissions reductions can be thought of as a jump forward in time to a future where additional systemic emissions controls have been adopted. However, because these changes occurred in a matter of months, the changes to the concentrations of key air quality (AQ) and climate-relevant gases in the atmosphere were readily observable. Combining these observations with current state-of-science models allows us an important window into the underlying processes governing the response of the Earth system to reductions in anthropogenic emissions and thus a preview of the relative effectiveness of different emissions-control strategies.Open in a separate windowFig. 1Illustration of the conceptual foundation for this study. The COVID-19–induced reductions in human activity led to reduced anthropogenic emissions. The fact that these reductions occurred over months rather than decades allows us to observe how the atmosphere, land, and ocean are likely to respond in a future scenario with stricter emissions controls. This analysis helps to identify effective pathways to mitigate air pollution and climate-relevant GHG emissions. Image credit: Chuck Carter (Keck Institute for Space Studies, Pasadena, CA).Our goal is to synthesize some of the key results from the past year into a coherent understanding of what we have learned about the effectiveness of different strategies to reduce greenhouse gas (GHG) emissions and improve AQ. We briefly highlight individual components of the changes in composition (which are well-described in the literature) but focus on the interactions and feedbacks between different parts of the Earth system. We will do so in four parts. First, we summarize the observed changes in anthropogenic emissions during 2020. Second, we examine how the reduction in CO₂ emissions impacted the atmospheric CO₂ growth rate. Third, we show that the response of AQ to NO_x emissions reductions differs for cities around the world and depends strongly on the interaction with meteorology. We focus on ozone and nitrate particulate matter (PM) as key AQ metrics that are strongly driven by NO_x emissions. Fourth, we discuss the implications of these results for future AQ improvement strategies; our understanding of processes controlling GHG concentrations in the atmosphere; feedbacks between AQ, GHGs, and climate; and, finally, close by identifying strengths and gaps in our current observing networks. We draw three primary conclusions from this synthesis:

• 1.Despite drastic reductions in mobility and resulting vehicular emissions during 2020, the growth rates of GHGs in the atmosphere were not slowed.
• 2.The lack of clear declines in the atmospheric growth rates of CO₂ and CH₄, despite large reductions in human activity, reflect carbon-cycle feedbacks in air–sea carbon exchange, large interannual variability in the land carbon sink, and the chemical lifetime of CH₄. These feedbacks foreshadow similar challenges to intentional mitigation.
• 3.The response of AQ to emissions changes is heavily modulated by factors including background pollutant levels, the timing and location of emissions changes, and climate-related factors like heat waves and wildfires. Achieving robust improvements to AQ thus requires sustained reductions of both air pollutant (AP) and GHG emissions.

     

Effect of Ceramic Formation on the Emission of Eu3+ and Nd3+ Ions in Double Perovskites

Herein, the structure, morphology, as well as optical properties of the powder and ceramic samples of Ba₂MgWO₆ are presented. Powder samples were obtained by high temperature solid-state reaction, while, for the ceramics, the SPS technique under 50-MPa pressure was applied. The morphology of the investigated samples showed some agglomeration and grains with a submicron size of 490–492 µm. The theoretical density and relative density of ceramics were calculated using the Archimedes method. The influence of sample preparation on the position, shape, and character of the host, as well as dopants emission was investigated. Sample sintering enhances regular emission of WO₆ groups causing a blue shift of Ba₂MgWO₆ emission. Nonetheless, under X-ray excitation, only the green emission of inversion WO₆ group was detected. For the ceramic doped with Eu³⁺ ions, the emission of both host and dopant was detected. However, for the powder efficient host to activator energy, the transfer process occurred, and only the magnetic dipole emission of Eu³⁺ was detected. The intensity of Nd³⁺ ions of Ba₂MgWO₆ powder sample is five times higher than for the ceramic. The sintering process reduces inversion defects and creates a highly symmetrical site of neodymium ions. The emission of Ba₂MgWO₆:Nd³⁺ consists of transitions from the ⁴F_3/2 excited level to the ⁴I_J multiplet states with the dominance of the ⁴F_3/2→⁴I_11/2 one. The spectroscopic quality parameter and branching ratio of Nd³⁺ emission are presented.     

Mud-Based Construction Material: Promising Properties of French Gravel Wash Mud Mixed with Byproducts,Seashells and Fly Ash as a Binder

The French gravel industry produces approximatively 6.5 million tons of gravel wash mud each year. This material offers very promising properties which require an in-depth characterization study before its use as a construction material, otherwise it is removed from value cycles by disposal in landfills. We examined the suitability of gravel wash mud and seashells, with fly ash as a binder, as an unfired earth construction material. Thermal and mechanical characterizations of the smart mixture composed of gravel wash mud, Crepidula fornicata shells and fly ash are performed. The new specimens exhibit high compressive strengths compared to usual earth construction materials, which appears as a good opportunity for a reduction in the thickness of walls. The use of fly ash and Crepidula shells in addition to gravel wash mud provides high silica and calcium contents, which both react with clay, leading to the formation of tobermorite and Al-tobermorite as a result of a pozzolanic reaction. Considering the reduction in porosity and improvements in strength, these new materials are good candidates to contribute significantly to the Sustainable Development Goals (SDGs) and reduce carbon emissions.     

Fiber Reinforced Compressed Earth Blocks: Evaluating Flexural Strength Characteristics Using Short Flexural Beams

There are ongoing research efforts directed at addressing strength limitations of compressed earth blocks (CEB) that inhibit their deployment for structural applications, particularly in areas where masonry systems are regularly subjected to lateral loads from high winds. In this paper, the authors focus specifically on the extent to which polypropylene (PP) fibers can be used to enhance the flexural performance of CEB. Cementitious matrices used for CEB production exhibit low tensile and flexural strength (brittle) properties. This work investigates plain (unreinforced) and fiber-reinforced specimens (short flexural beams) with fiber mass content of 0.2, 0.4, 0.6, 0.8, and 1.0% and ordinary Portland cement (OPC) content of 8%. The influence of the inclusion of fiber was based on tests conducted using the Standard Test Method for Flexural Performance of Fiber-Reinforced Concrete (ASTM C1609). Material properties that were quantified included first-peak strength, peak strength, equivalent flexural strength, residual strength, and flexural toughness. There was an observed improvement in the performance of the soil-fiber matrixes based on these results of these tests. It was also observed that when the fiber content exceeded 0.6% and above, specimens exhibited a deflection- hardening behavior; an indication of improvement in ductility. An equivalent flexural strength predictive model is proposed.