Moisture-Induced Reversible Phase Conversion of Cesium Copper Iodine Nanocrystals Enables Advanced Anti-Counterfeiting

Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs₃Cu₂I₅ nanocrystals (NCs) possess excellent hydrochromic properties. The prepared Cs₃Cu₂I₅ NCs films can dynamically extract and insert CsI by exposing/removing water to realize the reversible conversion between blue-emissive Cs₃Cu₂I₅ and yellow-emissive CsCu₂I₃. Interestingly, polymethyl methacrylate (PMMA) coated Cs₃Cu₂I₅ can effectively avoid the extraction of CsI and maintain long-term stability in the water. Further, the hydrochromic Cs₃Cu₂I₅ and water-resistant Cs₃Cu₂I₅@PMMA are used as the inks to synergistically act on anti-counterfeiting information to achieve multiple encryption effects, which can clearly identify and authenticate the effective information after moisture decryption. Importantly, the pattern can be re-encrypted to the invalid pattern after water evaporation. In addition, the anti-counterfeiting pattern has excellent stability during repeated encryption/decryption conversion cycles, which can not only balance the accessibility of anti-counterfeiting information but also effectively improve the security of information. This new discovery may not only deepen the understanding of Cs₃Cu₂I₅ but also provide new options for the design of hydrochromic materials for anti-counterfeiting information.     

Lead-Free Double Perovskite Cs2AgBiBr6: Fundamentals,Applications, and Perspectives

Cs₂AgBiBr₆, as a benchmark lead-free double perovskite, has emerged as a promising alternative to lead-based perovskites because of its high stability, non-toxicity, exceptional optoelectronic properties, and multifunctionality. To encourage further research on Cs₂AgBiBr₆ and its broad applications, in this review, its fundamental properties including the structure-property relation, synthesis, stability, origin of absorption and photoluminescence, electron-phonon coupling, role of defects, charge carrier dynamics, and bandgap modulation are comprehensively emphasized. The recent progress on the wide applications including solar cells, light/X-ray detectors, and ferroelectric/magnetic devices are highlighted. Moreover, the challenges of Cs₂AgBiBr₆ materials and related applications are discussed and perspectives are provided for guiding the future development of this research area.     

有源效率曲线拟合γ谱法快速测定水产品中~(137)Cs

利用~(152)Eu作为刻度源对HPGe-γ谱仪进行效率刻度,拟合出效率曲线,实现对水产品鲜样中~(137)Cs进行快速测量,以满足水产品放射性污染状况评估的需要。研究结果表明,取样品可食部分绞碎后装满2 L马林杯,测量时间6 h的测量结果即可达到0.111 Bq·kg~(-1)鲜样,可以满足针对水产品放射性的食用安全评估的要求。利用此方法对台湾海峡西侧养殖水产品进行检测,部分鱼类中检出~(137)Cs,但含量很低,对人体健康不构成威胁。     

高岭土类粘土矿物材料对模拟核素Sr、Co、Cs的吸附性能研究

对苏州高岭土、北川埃洛石、贵州遵义埃洛石吸附Sr、Co、Cs的性能进行了实验研究,结果表明:①高岭土类粘土矿物对Sr2 、Co2 、Cs2 的吸附能力随着pH值增大而增强,在碱性条件下对Sr2 、Co2 、Cs2 的吸附能力随碱性程度的增加而快速增大;②高岭土类粘土矿物对Sr2 、Co2 、Cs2 的吸附随着吸附剂量的增大,吸附率逐渐增大,单位质量吸附量明显减小;③母液浓度增大,单位质量吸附量增加,吸附率减小;④贵州埃洛石、北川埃洛石对Sr2 、Co2 、Cs2 的吸附性能相近,埃洛石对Sr2 、Co2 、Cs2 的吸附能力好于苏州高岭土。     

上海市2001年～2003年环境水137Cs比活度监测

介绍对上海市2001年～2003年环境水中137Cs比活度进行监测的方法、结果和初步分析.结果表明上海市淡水中137Cs比活度低于1.00×10-4Bq/L,海水中137Cs比活度范围为2.72×10-4～7.47×10-4 Bq/L.     

4C理论在有机化工产品自营贸易中的应用

有机化工产品自营业务是化工销售分公司根据当前市场形势推出的新的业务方式。分析有机化工产品的营销特点。利用4C营销理论指导营销策略的制定,规范自营贸易业务,获取客户的实际需求,根据客户能够接受的最大成本确定价格,为客户提供便利,保证持续、有效的沟通和自营贸易业务的顺利开展。     

Simulation of f-d transition using the extended crystal-field model:parameter dependent study for Er³⁺ in various hosts

The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and various rela ted aspects,such as the ways to determining various parameters,were summarized .The impacts of various interactions on the spectra were also demonstrated clea rly with Er3+ ions in crystals CaF2 and LiYF4.Predicted results were compared w ith measured spectra.     

~(133)Cs和~(88)Sr在蚕豆苗中的蓄积及其辐射损伤效应

通过水培试验研究了蚕豆苗对不同浓度133Cs和88Sr的蓄积及其辐射损伤效应。本实验利用原子吸收方法测定蚕豆苗对133Cs和88Sr的蓄积量,研究了133Cs和88Sr在蚕豆苗各部位的分布及对其生理影响。结果表明:在133Cs和88Sr所设不同浓度下,蚕豆苗地上部和根部的133Cs和88Sr蓄积量均随浓度梯度升高而增加,表现出根部含量地上部含量,133Cs含量88Sr含量。随着时间的推移,蚕豆苗对溶液中133Cs和88Sr蓄积量表现出先骤升后趋于平稳的趋势;随核素浓度的上升,根系活力均表现为先增强后减弱的趋势;蚕豆苗叶片中的丙二醛含量增加,叶片中丙二醛含量变化均较根系的大。88Sr处理组中的可溶性糖含量高于133Cs处理组。     

利用福岛第一核电厂事故期间环境监测资料反推事故释放源项

2011年3月11日,日本福岛核事故导致放射性物质向大气环境的大规模释放。本工作利用大气数值预报模式WRFV2.2.1和大气弥散模式CALPUFF,对事故期间放射性物质的大气输运和弥散进行了模拟。应用大气释放源项的逆推算方法,结合单位释放率条件下的大气弥散模拟结果和环境监测数据,对福岛第一核电厂1到3号机组向大气环境释放的放射性核素总量进行了评估,推算的131I和137 Cs气载释放量分别为8.6×1016 Bq和8.6×1015 Bq。     

N-乙酰基-S-烯丙基-L-半胱氨酸的合成及其抗辐射活性

以L-半胱氨酸为原料,经取代和酰化两步反应合成目标产物N-乙酰基-S-烯丙基-L-半胱氨酸(N-acetyl-S-allyl-L-cysteine,NAc-SAC)。以~(137)Csγ射线照射至不同剂量的ICR小鼠作为研究对象,通过30 d存活率实验、血相和免疫系统实验、各项脏器指数以及外周血淋巴细胞彗星实验,研究目标化合物分别在200、400、600 mg/kg给药剂量下的抗辐射活性。ICR小鼠经伽马射线照射至致死剂量7.5 Gy后,其存活率由单纯照射对照组的41.6%,分别提高到NAc-SAC给药组的58.3%、50.0%和66.7%,平均存活天数明显延长。~(137)Csγ射线照射至亚致死剂量6.0 Gy后,NAc-SAC在不同程度上增加了受照小鼠的脾指数、脾结节数(CFU-S)、骨髓DNA含量和白细胞数。彗星实验中7.0 Gy伽马射线照射联合NAc-SAC给药组小鼠外周血淋巴细胞的尾长、尾矩、Olive尾矩和尾部DNA百分含量明显低于7.0 Gy伽马射线单纯照射组(p0.01),提示NAc-SAC可明显降低辐射导致的DNA损伤。本研究表明,目标化合物NAc-SAC具有一定的抗辐射损伤作用。