Prussian Blue Analogue‑Templated Nanocomposites for Alkali‑Ion Batteries:Progress and Perspective

Lithium-ion batteries(LIBs)have dominated the portable electronic and electrochemical energy markets since their commercialisation,whose high cost and lithium scarcity have prompted the development of other alkali-ion batteries(AIBs)including sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).Owing to larger ion sizes of Na^(+)and K^(+)compared with Li^(+),nanocomposites with excellent crystallinity orientation and well-developed porosity show unprecedented potential for advanced lithium/sodium/potassium storage.With enticing open rigid framework structures,Prussian blue analogues(PBAs)remain promising self-sacrificial templates for the preparation of various nanocomposites,whose appeal originates from the well-retained porous structures and exceptional electrochemical activities after thermal decomposition.This review focuses on the recent progress of PBA-derived nanocomposites from their fabrication,lithium/sodium/potassium storage mechanism,and applications in AIBs(LIBs,SIBs,and PIBs).To distinguish various PBA derivatives,the working mechanism and applications of PBA-templated metal oxides,metal chalcogenides,metal phosphides,and other nanocomposites are systematically evaluated,facilitating the establishment of a structure–activity correlation for these materials.Based on the fruitful achievements of PBA-derived nanocomposites,perspectives for their future development are envisioned,aiming to narrow down the gap between laboratory study and industrial reality.

BLUE-plus方案的肺超声评分在急性呼吸衰竭患者胸部物理治疗中的应用

为了探究BLUE-plus方案的肺超声评分引导胸部物理治疗(CPT)在急性呼吸衰竭患者氧合能力、感染指标和肺通气功能方面的效果,根据样本量估算招募急性呼吸衰竭患者102例,随机分为试验组和对照组。试验组根据BLUE-plus肺超声征象、肺超声评分实施精准CPT,对照组采用常规CPT。比较两组患者入ICU第1~5天的氧合指数和第1、5天的血感染指标(降钙素原(PCT)、白介素-6(IL-6))及肺部超声评分、机械通气时长和ICU住院时长,发现BLUE-plus方案的肺超声评分指导的CPT可以改善急性呼吸衰竭患者的氧合指数、感染指标(IL-6)、肺部情况,缩短机械通气的时间。相较于对照组,试验组在第3~5天的氧合指数具有统计学差异(P<0.05),第5天IL-6、肺部超声评分、机械通气时长差异具有统计学意义(P<0.05),PCT、ICU住院时长无统计学差异(P>0.05)。

Apatinib and gamabufotalin co-loaded lipid/Prussian blue nanoparticles for synergistic therapy to gastric cancer with metastasis

Due to the non-targeted release and low solubility of anti-gastric cancer agent,apatinib(Apa),a first-line drug with long-term usage in a high dosage often induces multi-drug resistance and causes serious side effects.In order to avoid these drawbacks,lipid-film-coated Prussian blue nanoparticles(PB NPs)with hyaluronan(HA)modification was used for Apa loading to improve its solubility and targeting ability.Furthermore,anti-tumor compound of gamabufotalin(CS-6)was selected as a partner of Apawith reducing dosage for combinational gastric therapy.Thus,HA-Apa-Lip@PB-CS-6 NPs were constructed to synchronously transport the two drugs into tumor tissue.In vitro assay indicated that HA-Apa-Lip@PB-CS-6 NPs can synergistically inhibit proliferation and invasion/metastasis of BGC-823 cells via downregulating vascular endothelial growth factor receptor(VEGFR)and matrix metalloproteinase-9(MMP-9).In vivo assay demonstrated strongest anti-tumor growth and liver metastasis of HA-Apa-Lip@PB-CS-6 NPs administration in BGC-823 cells-bearing mice compared with other groups due to the excellent penetration in tumor tissues and outstanding synergistic effects.In summary,we have successfully developed a new nanocomplexes for synchronous Apa/CS-6 delivery and synergistic gastric cancer(GC)therapy.

Progress on Transition Metal Ions Dissolution Suppression Strategies in Prussian Blue Analogs for Aqueous Sodium-/Potassium-Ion Batteries

Aqueous sodium-ion batteries(ASIBs)and aqueous potassium-ion batteries(APIBs)present significant potential for large-scale energy storage due to their cost-effectiveness,safety,and environmental compatibility.Nonetheless,the intricate energy storage mechanisms in aqueous electrolytes place stringent require-ments on the host materials.Prussian blue analogs(PBAs),with their open three-dimensional framework and facile synthesis,stand out as leading candidates for aqueous energy storage.However,PBAs possess a swift capacity fade and limited cycle longevity,for their structural integrity is compromised by the pronounced dis-solution of transition metal(TM)ions in the aqueous milieu.This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs.The dissolution mechanisms of TM ions in PBAs,informed by their structural attributes and redox processes,are thoroughly examined.Moreover,this study delves into innovative design tactics to alleviate the dissolution issue of TM ions.In conclusion,the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries.

Isotherm,kinetic and thermodynamic investigations of boron phosphide to remove methylene blue from aqueous solution

In this work,the boron phosphide(BP)was synthesized and used for the adsorptive removal of methylene blue(MB)dye from aqueous solutions.To determine the optimum adsorption conditions,studies were performed by varying parameters of temperature(298–328 K),pH(2–12),contact time(0–120 min),adsorbent dose(0.01–0.20 g/50 mL),and dye concentration(10–50 mg/L).Different isotherm and kinetic models were applied to the adsorption data.The linear correlations coefficient showed that the Langmuir isotherm best fits(R^(2)=0.9996).The maximum adsorption capacity of BP was obtained as 555.56 mg/g at 55℃and the removal rate reached up to 84.11%.Additionally,the pseudo-second-order kinetic model described the adsorption process best(R^(2)=0.9998).The thermodynamic studies represented that the adsorption occurred spontaneously(ΔG_(A)^(Θ)=−24.90 kJ/mol)and endothermically(ΔH_(A)^(Θ)=16.67 kJ/mol).The results showed that BP is an efficient adsorbent for removing cationic dyes from aqueous solutions.

Cesium-doped manganese-based Prussian blue analogue as a high-efficiency cathode material for potassium-ion batteries

Prussian blue analogues (PBAs) are regarded as promising cathode materials for potassium-ion batteries(PIBs) owing to their low cost and high reversible capacity.Compared to other PBAs,potassium manganese hexacyanoferrate (KMnHCF) stands out for its superior capacity and operating voltage.However,Jahn-Teller effect of Mn^(3+)and the structural collapse caused by potassium ion insertion/extraction still affect the structural stability and electrochemical performance of this material.Herein,a green and efficient synthesis method is adopted to substitute potassium ions in KMnHCF with an appropriate amount of cesium ions to form a column effect.Cesium-doped KMnHCF (Cs-KMnHCF) mitigates the irreversible structural damage caused by potassiation/depotassiation and the Jahn-Teller effect,thereby improving the cycling stability.In addition,it widens the lattice channels,reduces the diffusion barrier of potassium ions,and optimizes the diffusion kinetics.By rationally controlling the doping amount of Cs^(+),the obtained K_(1.71)Cs_(0.05)Mn[Fe(CN)_(6)]_(0.95·0.05)·0.88H_(2)O exhibits remarkable electrochemical performance,with an initial discharge capacity of 137.6 mA h g^(-1)at a current density of 20 mA g^(-1)and a capacity retention of 89.6%after 600 cycles at 200 mA g^(-1).More importantly,when assembled with a pitch-derived soft carbon anode,the full cell manifests excellent cycle stability and rate performance.This work is expected to provide a highly efficient cathode material for the practical application of PIBs.

Achieving a superior Na storage performance of Fe-based Prussian blue cathode by coating perylene tetracarboxylic dianhydride amine

Fe-based Prussian blue(Fe-PB)cathode material shows great application potential in sodium(Na)-ion batteries due to its high theoretical capacity,long cycle life,low cost,and simple preparation process.However,the crystalline water and vacancies of Fe-PB lattice,the low electrical conductivity,and the dissolution of metal ions lead to limited capacity and poor cycling stability.In this work,a perylene tetracarboxylic dianhydride amine(PTCDA)coating layer is successfully fabricated on the surface of Fe-PB by a liquid-phase method.The aminated PTCDA(PTCA)coating not only increases the specific surface area and electronic conductivity but also effectively reduces the crystalline water and vacancies,which avoids the erosion of Fe-PB by electrolyte.Consequently,the PTCA layer reduces the charge transfer resistance,enhances the Na-ion diffusion coefficient,and improves the structure stability.The PTCA-coated Fe-PB exhibits superior Na storage performance with a first discharge capacity of 145.2 mAh g^(−1) at 100 mA g^(−1).Long cycling tests exhibit minimal capacity decay of 0.027%per cycle over 1000 cycles at 1 A g^(−1).Therefore,this PTCA coating strategy has shown promising competence in enhancing the electrochemical performance of Fe-PB,which can potentially serve as a universal electrode coating strategy for Na-ion batteries.

In vivo pilot study into superficial microcirculatory characteristics of colorectal adenomas using novel high-resolution magnifying endoscopy with blue laser imaging

BACKGROUND No studies have yet been conducted on changes in microcirculatory hemody-namics of colorectal adenomas in vivo under endoscopy.The microcirculation of the colorectal adenoma could be observed in vivo by a novel high-resolution magnification endoscopy with blue laser imaging(BLI),thus providing a new insight into the microcirculation of early colon tumors.AIM To observe the superficial microcirculation of colorectal adenomas using the novel magnifying colonoscope with BLI and quantitatively analyzed the changes in hemodynamic parameters.METHODS From October 2019 to January 2020,11 patients were screened for colon adenomas with the novel high-resolution magnification endoscope with BLI.Video images were recorded and processed with Adobe Premiere,Adobe Photoshop and Image-pro Plus software.Four microcirculation parameters:Microcirculation vessel density(MVD),mean vessel width(MVW)with width standard deviation(WSD),and blood flow velocity(BFV),were calculated for adenomas and the surrounding normal mucosa.RESULTS A total of 16 adenomas were identified.Compared with the normal surrounding mucosa,the superficial vessel density in the adenomas was decreased(MVD:0.95±0.18 vs 1.17±0.28μm/μm2,P<0.05).MVW(5.11±1.19 vs 4.16±0.76μm,P<0.05)and WSD(11.94±3.44 vs 9.04±3.74,P<0.05)were both increased.BFV slowed in the adenomas(709.74±213.28 vs 1256.51±383.31μm/s,P<0.05).CONCLUSION The novel high-resolution magnification endoscope with BLI can be used for in vivo study of adenoma superficial microcirculation.Superficial vessel density was decreased,more irregular,with slower blood flow.

Blue rubber blister nevus syndrome: A case report

BACKGROUND Blue rubber blister nevus syndrome(BRBNS)is a congenital,rare disease charac-terized by venous malformations of the skin and internal organs,affecting all systems throughout the body.The pathogenesis is unknown.There is no con-sensus on the treatment of BRBNS.Most of the previously reported cases were mild to moderate with a good prognosis,and this case was a critically ill patient with severe gastrointestinal hemorrhage,disseminated intravascular coagulation(DIC),and severe joint fusion that was different from previously reported cases.CASE SUMMARY An 18-year-old man with early onset of BRBNS in early childhood is reported.He presented with recurrent melena and underwent malformed phlebectomy and partial jejunectomy and ileal resection.The patient had melena before and after surgery.After active treatment,the patient's gastrointestinal bleeding improved.This was a case of atypical BRBNS with severe gastrointestinal bleeding and severe joint fusion,which should be differentiated from other serious joint lesions and provide clinicians with better understanding of this rare disease.CONCLUSION This case of critical BRBNS with gastrointestinal hemorrhage,DIC and severe joint fusion provides further understanding of this rare disease.

Experimental and computational optimization of Prussian blue analogues as high-performance cathodes for sodium-ion batteries:A review

In this review,we discuss the electrochemical properties of Prussian blue(PB)for Na^(+)storage by combining structural engineering and electrolyte modifications.We integrated experimental data and density functional theory(DFT)in sodium-ion battery(SIB)research to refine the atomic arrangements and crystal lattices and introduce substitutions and dopants.These changes affect the lattice stability,intercalation,electronic and ionic conductivities,and electrochemical performance.We unraveled the intricate structure-electrochemical behavior relationship by combining experimental data with computational models,including first-principles calculations.This holistic approach identified techniques for optimizing PB and Prussian blue analog(PBA)structu ral properties for SIBs.We also discuss the tuning of electrolytes by systematically adjusting their composition,concentration,and additives using a combination of molecular dynamics(MD)simulations and DFT computations.Our review offers a comprehensive assessment of strategies for enhancing the electrochemical properties of PB and PBAs through structural engineering and electrolyte modifications,combining experimental insights with advanced computational simulations,and paving the way for next-generation energy storage systems.

The Secret Toxic Legacies of Chemical Warfare: Agent Blue Use during the 2nd Indochina and Vietnam Wars in Laos, Cambodia, and Vietnam (1961 to 1971)

During the 2nd Indochina War which started in 1959, the United States Central Intelligence Agency (CIA), Air America, and the Air Force waged a secret and unconventional air war in Laos from Udorn Air Force base located in Thailand and across the Mekong River from Vientiane, Laos. Starting in 1961, four years before the official start of the American-Vietnam War, Agent Blue, the arsenic-based herbicide used to kill rice and other food crops, was used extensively in Laos, Vietnam and to a lesser extent in Cambodia. During the secret 2nd Indochina War and the Vietnam Civil War the public knew little about the use of Agent Blue. After the official start of the American-Vietnam War in 1965, the United States media news reports, about chemical warfare were dominated by the story of Agent Orange and its devastating impacts. The public knew very little about the previous use of Agent Blue in both wars. The first known media pick up of the Agent Blue (arsenic based) and Agent Pink, Agent Green, and Agent Purple (all three contain 2, 4, 5-T and unknown amounts of dioxin TCDD) was in May of 1964. Jim G. Lucas, a Scripps-Howard staff reporter submitted an article that was published as an editorial in Washington Post on May 26, 1964. The next news reference to this chemical weapon was a Letter to the Editor published in the New York Times titled “Agent Blue” in Vietnam by Arthur H. Westing in (1971). The use of herbicides, including Agent Blue in Laos during the 2nd Indochina War, was kept a secret until 1982, when a draft of Buckingham’s study of Operation Ranch Hand was made public. Much about the U.S. war effort in Laos is still classified. In a 2014 issue of the VVA Veteran magazine, Loana Hoylman published an article on “Today’s Blue Arsenic in the Environment”. The first refereed journal article on this topic, “The Fate of Agent Blue, the Arsenic-Based Herbicide, Used in South Vietnam during the Vietnam War” was published in 2020 in the Open Journal of Soil Science by Kenneth R. Olson and Larry Cihacek. In 2021 the Asia Times (print) and VietnamVeteranNews (radio podcast) picked up the Agent Blue story. During the early 2020s, Olson published six additional refereed journal articles on Agent Blue, cacodylic acid, and arsenic. The primary objective is to determine why no major news organization in the United States, including the New York Times and Washington Post, have never investigated Agent Blue use during the 2nd Indochina and Vietnam wars? Why did the use of Agent Blue story, used to destroy Laotian and South Vietnamese civilian food (rice) sources and production sites, received only very limited coverage by US print media news organizations during the last 64 years?

蓝色鳞鲤(Cyprinus carpio blue var)同工酶分析

采用聚丙烯酰胺凝胶垂直板电泳法对蓝色鳞鲤(Cyprinus carpio blue var)进行同工酶分析。结果表明:在蓝色鳞鲤的眼睛、肌肉、肝脏、心脏、肾脏5种组织中,14种酶(LDH、ADH、GDH、MDH、G-6-PDH、EST、POD、SDH、FDH、SOD、α-AMY、CAT、COX、ME)的同工酶谱均存在明显的组织特异性。14种酶共记录出33个基因位点,其中α-Amy-2、Cox-2、Est-1、Ldh-1、Mdh-1、Mdh-2和Sod-1为多态位点。蓝色鳞鲤群体的多态位点百分数为21.21%(P0.99),平均预期杂合度和平均实际杂合度分别为0.1079和0.2121,遗传偏离指数(d)值为正。平均有效等位基因数(Ne)为1.24。实验表明,目前蓝色鳞鲤群体的种质资源状况尚好,表现出明显的杂交优势。

Microstructure Observation on the Follicular Development of Blue Fox during the Estrous Period

[Objective] The ovary microstructure and the changes of the follicle during the development period of blue fox during the estrous period were studied.[Method] Ten left ovaries were collected from 10 female blue foxes during the estrous period. The histological structure of the ovary and follicular development process were observed by using optical microscope. And 30 primordial follicles, 30 primary follicles, 15 growing follicles, 15 vesicular follicle, 15 mature follicles and the oocytes in the follicles of different developing stages were measured and photographed by eyepiece micrometer and photomicrographic technique respectively. [Result] The ovary of blue fox consisted of germinal epithelium, tunica albuginea, cortex and medulla. The cor- tex, which was located at the periphery of the ovary, contained many interstitial cells and follicles at different developing stages. Medulla was located below the cortex, with a lot of blood vessels. The diameters of follicles at different developmental stages and oocytes had greater differences during the developmental period of follicle. The diameter of follicles was 45.45-974.55 μm and the diameter of oocytes was 30.23-147.27 μm. The zona pellucida appeared at the primary follicle stage. The atresia of follicles occurred at all the developmental stages of follicle and the main manifestations were the shrunk oocyte and karyon, and loose and degraded granular cells. [Conclusion] The research provided histological basis for revealing the reproductive mechanism of female blue fox.

肺部超声BLUE-plus方案对急性呼吸衰竭病因诊断的价值

目的探讨肺部超声BLUE-plus(bedside lungultrasoundinemergency-PLUS)方案对急性呼吸衰竭病因诊断的价值。方法选取2018年11月至2020年8月贵阳市第一人民医院重症医学科收治的急性呼吸衰竭患者61例作为研究对象。探讨应用BLUE-plus方案筛查呼吸衰竭病因的准确性。结果BLUE-plus方案对胸腔积液敏感性为97.6%,特异性为100.0%,阳性预期值为100.0%,阴性预期值为95.0%;BLUE-plus方案对肺实变/肺不张的敏感性为89.3%,特异性为97.0%,阳性预期值为96.2%,阴性预期值为91.4%。床旁胸片对胸腔积液敏感性为85.6%,特异性为94.7%,阳性预期值为97.3%,阴性预期值为75.0%;床旁胸片对肺实变/肺不张的敏感性为78.6%,特异性为94.0%,阳性预期值为83.8%,阴性预期值为86.9%。肺部超声对胸腔积液诊断的正确率及敏感性高于床旁胸片,差异有统计学意义(P<0.05)。结论肺部超声BLUE-plus是急性呼吸衰竭病因诊断的快速有效方法,尤其对胸腔积液诊断的敏感性及正确率均高于床旁胸片。

蓝色鳞鲤(Cyprinus carpio blue var)的细胞遗传学分析

采用体内注射PHA和秋水仙素,肾细胞短期培养,常规空气干燥法制备蓝色鳞鲤染色体,对100个中期分裂相记数统计,确定蓝色鳞鲤(Cyprinuscarpiobluevar)的染色体数为2n=100。测得核型参数按Levan等的染色体划分标准得出:蓝色鳞鲤有15对中部着丝点染色体(m);13对亚中部着丝点染色体(sm);22对端部和亚端部着丝点染色体(st,t),其染色体总臂数(NF)为156,蓝色鳞鲤核型公式为2n=30m+26sm+44st,t。采用流式细胞分析仪测定了蓝色鳞鲤的DNA含量,与鸡血细胞标准对照相比为1.73±0.10,以鸡红细胞DNA含量2.3pg.N-1计,则蓝色鳞鲤的体细胞DNA含量为3.99pg.N-1。

一般Gauss-Markoff型中LSE和BLUE的关系

通过运用估计的效率和广义相关系数,讨论了一般Gauss-Markoff模型中最小二乘估计(LSE)和最小方差线性无偏估计(BLUE)的关系。在M(X)M(V)的条件下,求出了效率e(c)的下界的估计式以及广义相关系数的几个界的估计式。

肺超声BLUE方案和ETUDES-plus方案在ICU呼吸困难患者中的应用价值

目的探讨肺超声BLUE方案和ETUDES-plus方案在ICU呼吸困难患者中的应用价值。方法选择2018年9月至2019年10月在黄山首康医院重症医学科(ICU)住院的94例患者为研究对象。所有患者入ICU后进行床旁超声BLUE方案和ETUDES-plus方案检查,以胸部CT作为诊断标准比较两种检查方案在呼吸困难患者病因诊断中的价值。结果以胸部CT作为诊断标准,ETUDES-plus方案病因诊断总正确率为97.87%(92/94),显著高于肺超声BLUE方案的84.04%(79/94),差异有统计学意义(χ^(2)=128.61,P<0.001)。ETUDES-plus方案在肺炎诊断上正确率为96.87%(31/32),显著高于BLUE方案的68.75%(22/32),差异有统计学意义(P=0.003);两种方案在充血性心力衰竭、AECOPD、气胸、支气管哮喘、ARDS、肺挫伤及其他诊断上差异无统计学意义(P>0.05)。肺超声BLUE方案和ETUDES-plus方案不同部位超声表现比较,A征象、平流层征最常见的部位是BLUE方案的上BLUE点和ETUDESplus方案的前胸壁上。胸腔积液、碎片征和组织样征最常见的部位是BLUE方案的PLAPS点和ETUDES-plus方案的背部下。结论ETUDES-plus方案在ICU呼吸困难患者病因诊断中有较高的正确率,值得临床应用。

基于Packet Tracer的虚拟医疗网络设计与性能分析

在Packet Tracer模拟环境中针对虚拟医疗网络进行设计与性能分析。系统需求与设计部分详细考虑了医疗网络的功能需求、拓扑设计和安全性措施。通过Packet Tracer模拟环境的建立,成功模拟了医院内部网络、医疗设备网络和远程连接,符合实际医疗场景。在性能分析中,使用Packet Tracer工具对带宽、延迟、安全性和可靠性进行了全面评估。通过优化网络配置,确保实时医疗应用的高效运行,同时强调了网络的安全性和可靠性。这一综合性的设计和性能分析为虚拟医疗网络的实际部署提供了有力的支持。

Enhanced adsorption of Methylene Blue from aqueous solution by chitosan-g-poly(acrylic acid)/vermiculite hydrogel composites

A series of chitosan-g-poly （acrylic acid）/vermiculite hydrogel composites were synthesized and used as adsorbents for the investigation of the effect of process parameters such as vermiculite content, pH of dye solution, contact time, initial concentration of dye solution, temperature, ionic strength and concentration of surfactant sodium dodecyl sulfate on the removal of Methylene Blue （MB） from aqueous solution. The results showed that the adsorption capacity for dye increased with increasing pH, contact time and initial dye concentration, but decreased with increasing temperature, ionic strength and sodium dodecyl sulfate concentration in the present of the surfactant. The adsorption kinetics of MB onto the hydrogel composite followed pseudo second-order kinetics and the adsorption equilibrium data obeyed Langmuir isotherm. By introducing 10 wt.% vermiculite into chitosan-g-poly （acrylic acid） polymeric network, the obtaining hydrogel composite showed the highest adsorption capacity for MB, and then could be regarded as a potential adsorbent for cationic dye removal in a wastewater treatment process.

Use and application of CFC-11,CFC-12,CFC-113 and SF6 as environmental tracers of groundwater residence time:A review

Groundwater residence time is a fundamental property of groundwater to understand important hydrogeological issues,such as deriving sustainable abstraction volumes,or,the evolution of groundwater quality.The anthropogenic trace gases chlorofluorocarbons (CFC-11,CFC-12 and CFC-113) and sulphur hexafluoride (SF6) are ideal in this regard because they have been released globally at known rates and become dissolved in groundwater following Henry’s Law,integrating over large spatial (global) and temporal (decades) scales.The CFCs and SF6 are able to date groundwater up to w100 years old with the caveat of certain simplifying assumptions.However,the inversion of environmental tracer concentrations (CFCs and SF6) to derive groundwater age rests on the accurate determination of groundwater recharge parameters,namely temperature,elevation,salinity and excess air,in addition to resolving the potential for contamination,degradation and unsaturated zone effects.This review explores the fundamentals of CFC-11,CFC-12,CFC-113 and SF6 as environmental tracers of groundwater age and recommends complementary techniques throughout.Once this relatively simple and inexpensive technique has been used to determine initial concentrations at the recharge zone,setting the groundwater dating ‘clock’ to zero,this review then explores the meaning of groundwater ‘age’ in relation to measured environmental tracer concentrations.It is shown that the CFCs and SF6 may be applied to a wide-range of hydrogeological problems and suggests that environmental tracers are particularly powerful tools when integrated with numerical flow and transport models.