CyclinG2在喉鳞癌组织中的表达及其与微血管密度的相关性研究

目的检测喉鳞状细胞癌(laryngeal squmaous cell carcinoma,LSCC)组织中CyclinG2蛋白表达和微血管密度(microvessel density,MVD),并探讨其与LSCC预后的关系。方法应用免疫组织化学技术对81例喉鳞癌组织的CyclinG2蛋白表达和MVD进行检测,并取20例喉正常黏膜组织(normal laryngeal tissues,NLT)及20例声带息肉组织(vocal cord polyp,VCP)作为对照。采用SPSS12.0统计软件系统分析CyclinG2蛋白的表达和MVD与LSCC、NLT、VCP的相关性,以及LSCC组织中MVD的表达与临床病理特征的关系。结果81例LSCC组织中平均MVD为36.15土11.23,CyclinG2蛋白表达阳性组平均MVD为32.18土11.31,阴性者平均MVD为50.34土17.34,其差异具有统计学意义(P<0.05)。LSCC总的5年生存率约77.8%,且CyclinG2蛋白表达阳性组5年生存率(89.1%)明显高于阴性组(53.8%),其差异具有统计学意义(P<0.01)。结论CyclinG2蛋白在LSCC中的表达与MVD关系密切。CyclinG2可能抑制喉鳞癌中微血管形成,进而抑制癌细胞的侵袭与转移。

细胞周期蛋白G2在胃癌组织中的表达和其对胃癌细胞株体外增殖影响的研究

目的研究G型细胞周期蛋白(cyclin)家族中的新成员cyclinG2在胃癌组织中的表达和其对胃癌细胞株SGC7901体外增殖的影响。方法通过免疫组织化学技术检测40例胃癌标本中cyclinG2蛋白的表达情况并进行显微图像分析;利用阳离子介导的脂质体转染试剂将包含有cyclinG2的真核表达载体pIRESG2转染SGC7901,经G418克隆筛选后获得稳定表达cyclinG2的细胞克隆,噻唑蓝法(MTT)比色法测定转染后细胞增殖活性的改变。结果①CyclinG2在非癌组织、分化型癌和差分化型癌组织中的阳性率和表达强度逐渐下降且差异有统计学意义(P<0.01)。②转染pIRESG2获得的克隆细胞的体外增殖能力降低(P<0.01)。结论CyclinG2基因很可能是一种候选的抑癌基因,随着胃癌恶性程度的增加其表达水平降低;外源性基因转染导致的cyclinG2异常性高表达可显著抑制胃癌细胞株的体外增殖能力。

Multi-objective optimization and evaluation of supercritical CO_(2) Brayton cycle for nuclear power generation

The supercritical CO_(2) Brayton cycle is considered a promising energy conversion system for Generation IV reactors for its simple layout,compact structure,and high cycle efficiency.Mathematical models of four Brayton cycle layouts are developed in this study for different reactors to reduce the cost and increase the thermohydraulic performance of nuclear power generation to promote the commercialization of nuclear energy.Parametric analysis,multi-objective optimizations,and four decision-making methods are applied to obtain each Brayton scheme’s optimal thermohydraulic and economic indexes.Results show that for the same design thermal power scale of reactors,the higher the core’s exit temperature,the better the Brayton cycle’s thermo-economic performance.Among the four-cycle layouts,the recompression cycle(RC)has the best overall performance,followed by the simple recuperation cycle(SR)and the intercooling cycle(IC),and the worst is the reheating cycle(RH).However,RH has the lowest total cost of investment(C_(tot))of$1619.85 million,and IC has the lowest levelized cost of energy(LCOE)of 0.012$/(kWh).The nuclear Brayton cycle system’s overall performance has been improved due to optimization.The performance of the molten salt reactor combined with the intercooling cycle(MSR-IC)scheme has the greatest improvement,with the net output power(W_(net)),thermal efficiencyη_(t),and exergy efficiency(η_(e))improved by 8.58%,8.58%,and 11.21%,respectively.The performance of the lead-cooled fast reactor combined with the simple recuperation cycle scheme was optimized to increase C_(tot) by 27.78%.In comparison,the internal rate of return(IRR)increased by only 7.8%,which is not friendly to investors with limited funds.For the nuclear Brayton cycle,the molten salt reactor combined with the recompression cycle scheme should receive priority,and the gas-cooled fast reactor combined with the reheating cycle scheme should be considered carefully.

A Review on Technologies for the Use of CO2 as a Working Fluid in Refrigeration and Power Cycles

The use of carbon dioxide as a working fluid has been the subject of extensive studies in recent years, particularly in the field of refrigeration where it is at the heart of research to replace CFC and HCFC. Its thermodynamic properties make it a fluid of choice in the efficient use of energy at low and medium temperatures in engine cycles. However, the performance of transcritical CO2 cycles weakens under high temperature and pressure conditions, especially in refrigeration systems;On the other hand, this disadvantage becomes rather interesting in engine cycles where CO2 can be used as an alternative to the organic working fluid in small and medium-sized electrical systems for low quality or waste heat sources. In order to improve the performance of systems operating with CO2 in the field of refrigeration and electricity production, research has made it possible to develop several concepts, of which this article deals with a review of the state of the art, followed by analyzes in-depth and critical of the various developments to the most recent modifications in these fields. Detailed discussions on the performance and technical characteristics of the different evolutions are also highlighted as well as the factors affecting the overall performance of the systems studied. Finally, perspectives on the future development of the use of CO2 in these different cycles are presented.

Numerical Models and Methods of Atmospheric Parameters Originating in the Formation of the Earth’s Climatic Cycle

Atmospheric models are physical equations based on the ideal gas law. Applied to the atmosphere, this law yields equations for water, vapor (gas), ice, air, humidity, dryness, fire, and heat, thus defining the model of key atmospheric parameters. The distribution of these parameters across the entire planet Earth is the origin of the formation of the climatic cycle, which is a normal climatic variation. To do this, the Earth is divided into eight (8) parts according to the number of key parameters to be defined in a physical representation of the model. Following this distribution, numerical models calculate the constants for the formation of water, vapor, ice, dryness, thermal energy (fire), heat, air, and humidity. These models vary in complexity depending on the indirect trigonometric direction and simplicity in the sum of neighboring models. Note that the constants obtained from the equations yield 275.156˚K (2.006˚C) for water, 273.1596˚K (0.00963˚C) for vapor, 273.1633˚K (0.0133˚C) for ice, 0.00365 in/s for atmospheric dryness, 1.996 in2/s for humidity, 2.993 in2/s for air, 1 J for thermal energy of fire, and 0.9963 J for heat. In summary, this study aims to define the main parameters and natural phenomena contributing to the modification of planetary climate. .

Cyclin G2抑制肿瘤细胞增殖的研究

背景与目的:周期蛋白(cyclin)是调节细胞周期活动的重要蛋白质,是细胞增殖的正调节因子。CyclinG2可能不同于其它周期蛋白,其表达可被DNA损伤和抑癌基因VHL诱导,对细胞增殖可能起负性调节作用。此外,我们在对口腔鳞癌进行基因表达谱研究时发现,癌组织中cyclinG2表达降低。本研究的目的是为了弄清cyclinG2表达究竟是促进还是抑制肿瘤细胞体外增殖。方法:应用RT-PCR扩增获得cyclinG2基因cDNA,将其插入到真核表达载体pIRESneo的BamHI和BstXI酶切位点处,获得重组表达质粒,命名为pIRES-G2。通过脂质体介导将pIRES-G2转染肿瘤细胞系HeLa,经G418筛选2周,观察细胞集落形成情况并计数形成的集落数。结果:实验组集落的数量显著少于对照组,而且所形成的集落大小也明显比对照组小,细胞皱缩、形态不规则,胞质内颗粒增多、出现空泡。pIRESneo空载体对照组的集落数为76.7±24.8;实验组的集落数为18±10.4,占对照组的23.4%。结论:CyclinG2基因高表达对HeLa细胞的体外增殖和生长有显著抑制作用。

余甘子对三阴性乳腺癌MDA-MB-231细胞增殖的影响及分子机制

目的研究藏药余甘子对人三阴性乳腺癌MDA-MB-231细胞增殖的影响及可能分子机制。方法 (1)设置实验组和对照组,在体外培养人三阴性乳腺癌MDA-MB-231细胞,采用四氮唑蓝(MTT)比色法检测经余甘子(320、160、80、40、20μg/m L)处理MDA-MB-231细胞24 h后的细胞活性并计算IC50;(2)采用流式细胞术分析经余甘子(20μg/m L)处理MDA-MB-231细胞24 h后细胞的周期变化;(3)采用荧光定量PCR(Real-time PCR)法检测经余甘子(20μg/m L)处理MDA-MB-231细胞24 h后的细胞周期蛋白CyclinG2和细胞周期依赖性蛋白激酶抑制因子p21的表达水平;(4)通过Kmplot数据库分析三阴性乳腺癌患者CyclinG2、p21的表达与预后情况。结果与对照组比较,余甘子(320、160、80、40、20μg/m L)在体外对MDA-MB-231细胞活性具有明显的抑制作用(P<0.05),且这种抑制作用呈浓度依赖效应;余甘子(20μg/m L)可以促进乳腺癌MDA-MB-231细胞G1/S期凋亡;余甘子(20μg/m L)能显著上调MDA-MB-231细胞中CyclinG2、p21mRNA的表达水平(P<0.05);CyclinG2、p21表达水平高可起到潜在提高三阴性乳腺癌患者良好预后的作用。结论余甘子可抑制人乳腺癌MDA-MB-231细胞体外增殖,细胞周期阻滞在G1/S期,机制可能与上调CyclinG2、p21mRNA水平有关;三阴性乳腺癌患者CyclinG2、p21的高表达对预后有潜在的良性作用。

一种具有噪声整形功能的2bit/cycle SAR ADC的设计

基于180nm CMOS工艺,设计了一种2 bit/cycle结构的8 bit、100 MS/s逐次逼近模数转换器(SAR ADC).采用两个DAC电容阵列SIG_DAC、REF_DAC实现了2 bit/cycle量化,其中SIG_DAC采用上极板采样大大减少了电容数目,分裂电容式结构和优化的异步SAR逻辑提高了ADC的转换速度.应用一种噪声整形技术,有效提高了过采样时ADC的信噪失真比(SNDR).在1.8 V电源电压和100 MS/s采样率条件下,未加入噪声整形时,仿真得到ADC的SNDR为46.22 dB,加入噪声整形后,过采样率为10时,仿真得到的SNDR为57.49 dB,提高了11.27 dB,ADC的有效位数提高了约1.88 bit,达到9.26 bit.

Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis

Objective： To examine the apoptotic effect of ent-llα-hydroxy-15-oxo-kaur-16-en-19-oic-acid （5F）, a compound isolated from Pteris semipinnata L （PsL）, in human lung cancer A549 cells. Methods： A549 cells were treated with 5F （0-80 lag/ml） for different time periods. Cytotoxicity was examined using a Ml-I- method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay （ELISA） and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species （ROS） level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined. Results： 5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor （AIF）, and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin. Conclusion： 5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.

Karst subzone division in vertical cycle zone and its significance

Vertical cycle karst zone has been studied for more than 100 years, however karst subzones in the zone have never been divided and affected depth of CO2 from rainwater in the zone has never been studied. On the basis of field observation, survey and chemical analysis, the difference of karst processes indicated by CaCO3 and pH values in fine and loose sedimentary strata as well as limestone strata, and the vertical cycle zone ascertained by predecessors can be divided into three subzones, that is, the upper first subzone, characterized by unsaturated water solution and strong dissolution processes, the middle second subzone, characterized by supersaturated water solution and precipitation, and the lower third subzone, characterized by unstable water solution and weak dissolution or weak precipitation. The three subzones can indicate the vertical CO2 cycle. In fine and loose sediment strata, the bottom of the first subzone is the lower boundary strongly influenced by CO2 from rainwater, soil and air; all CO2 from rainwater, soil and air is almost exhausted in the second subzone. In the early developmental period of karst process in limestone strata, karst funnels and vertical caves do not form, vertical seeping of rainwater and soil water is very slow, and CO2 from soil, rainwater and air almost can reach the third subzone, but in the middle and late developmental periods, karst funnels and vertical caves occur, CO2 from soil, rainwater and air can reach deep seasonal change zone and horizontal cycle zone and quicken development of karst morphology. Deep karst morphology near groundwater level under vertical cycle zone develops better in the middle and late periods of karst process.

Prognostic Impact of Cell Division Cycle Associated 2 Expression on Pancreatic Ductal Adenocarcinoma

Objective To examine the expression of cell division cycle associated 2(CDCA 2) in pancreatic ductal adenocarcinoma(PDAC) and investigate its role in prognosis of PDAC patients.Methods This retrospective study included 155 PDAC patients who underwent surgical treatment and complete post-operative follow-up.Clinicopathologic data were collected through clinical database.Tissue microarray was constructed and immunohistochemistry was performed to detect CDCA2 expression in the PDAC tumor tissues and adjacent non-tumor tissues.Clinicopathological characteristics between high and low CDCA2 expression were compared.Correlation of CDCA2 expressions with patients' survival was analyzed using Kaplan-Meier method and Cox regression analysis.Results Expression of CDCA2 in PDAC cells was significantly higher than that in adjacent non-tumor tissues(U=4056.5,P<0.001).Univariate analysis showed that CDCA2 expression [hazard ratio(HR)=1.574,95% confidence interval(CI)=1.014-2.443,P=0.043] and node metastasis(HR=1.704,95%CI=1.183-2.454,P=0.004) were significantly associated with prognosis.Cox regression analysis showed CDCA2 expression was not an independent prognostic risk factor(HR=1.418,95%CI=0.897-2.242,P=0.135) for PDCA patients.Stratification survival analysis demonstrated CDCA2 expression as an independent prognostic risk factor in male patients(HR=2.554,95%CI=1.446-4.511,P=0.003) or in non-perineural invasion patients(HR=2.290,95%CI=1.146-4.577,P=0.012).Conclusions CDCA2 is highly expressed in PDAC tumor tissue.Although CDCA2 is not an independent prognostic risk factor for PDAC patients,it might be used to help predict prognosis of male or non-perineural invasion patients of PDAC.

Progress in Research and Development of Molten Chloride Salt Technology for Next Generation Concentrated Solar Power Plants

Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-cost electricity with abundant but intermittent solar energy.In order to significantly reduce the levelized cost of electricity(LCOE)of the present commercial CSP plants,the next generation CSP technology with higher process temperature and energy efficiency is being developed.The TES system in the next generation CSP plants works with new TES materials at higher temperatures(>565℃)compared to that with the commercial nitrate salt mixtures.This paper reviews recent progressin research and development of the next generation CSP and TES technology.Emphasis is given on theadvanced'TES technology based on molten chloride salt mixtures such as MgCl_(2)/NaCl/KCl which hassimilar thermo-physical properties as the commercial nitrate salt mixtures,higher thermal stability(>800℃),and lower costs(<0.35USD·kg^(-1)).Recent progress in the selection/optimization of chloridesalts,determination of molten chloride salt properties,and corrosion control of construction materials(eg.,alloys)in molten chlorides is reviewed.

A review of recent researches on Bunsen reaction for hydrogen production via S–I water and H2S splitting cycles

The Bunsen reaction is the center reaction for both the sulfur–iodine water splitting cycle for hydrogen production and the novel hydrogen sulfide splitting cycle for hydrogen and sulfuric acid production from the sulfur-containing gases.This paper reviews the research progress of the Bunsen reaction in recent 10–15 years.Researches were initially focused on the optimization of the operating conditions of the conventional Bunsen reaction requiring excessive water and iodine to improve the products separation efficiency and to avoid the side reactions and iodine vapor deposition.Alternative methods including electrochemical methods,precipitation methods,and non-aqueous solvent methods had their respective advantages,but still faced challenges.In development of the technology of H2S splitting cycle,dissolving iodine in toluene solvent could render the Bunsen reaction to occur with the flowable I2 stream at ambient temperature such that the side reactions and iodine vaporization can be avoided and the corrosion hazard lessened.It also prevented the Bunsen reaction from using excessive iodine and water.The products from the Bunsen reaction including HI,H2SO4,H2O,and toluene could be directly electrolyzed.

Intrinsic apoptotic pathway and G2/M cell cycle arrest involved in tubeimoside I-induced EC109 cell death

Objective： Squamous esophageal carcinoma is highly prevalent in developing countries, especially in China. Tu Bei Mu （TBM）, a traditional folk medicine, has been used to treat esophageal squamous cell carcinoma （ESCC） for a long term. tubeimoside I （TBMS1） is the main component of TBM, exhibiting great anticancer potential. In this study, we investigated the mechanism of TBMS1 cytotoxic effect on EC109 cells. Methods： Comparative nuclear proteomic approach was applied in the current study and we identified several altered protein spots. Further biochemical studies were carried out to detect the mitochondrial membrane potential, cell cycle and corresponding proteins＇ expression and location. Results： Subcellular proteomic study in the nucleus from EC109 cells revealed that altered proteins were associated with mitochondrial function and cell proliferation. Further biochemical studies showed that TBMSl-induced molecular events were related to mitochondria-induced intrinsic apoptosis and P21-cyclin B 1/cdc2 complex-related G2/M cell cycle arrest. Conclusions： Considering the conventional application of TBM in esophageal cancer, TBMS1 therefore may have a great potential as a chemotherapeutic drug candidate for ESCC.

Arsenic Trioxide Inhibits Proliferation in K562 Cells by Changing Cell Cycle and Survivin Expression

To study the mechanisms involved in the inhibition of chronic myeloid leukemic cells (K562) proliferation induced by arsenic trioxide (As 2O 3) and to explore the potential role of Survivin, an inhibitor of apoptosis protein, in the regulation of As 2O 3 induced cell apoptosis, K562 cells were cultured with As 2O 3 of different concentrations. Cells were collected for proliferation analysis by MTT assay. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. Expression of Survivin protein and mRNA were detected by flow cytometry and RT-PCR, respectively. Our results showed that As 2O 3 (2-10 μmol/L) inhibited K562 cells growth effectively, but it did not induce cells apoptosis significantly. The percentage of K562 cells at G 2/M phase increased in proportion to As 2O 3 concentrations, and the expression of Survivin mRNA and content of Survivin protein was up-regulated accordingly. It is concluded that As 2O 3 inhibited K562 cells growth by inducing cell cycle arrest mainly at G 2/M phase. Over-expression of Survivin gene and protein might be one of the possible mechanisms contributing to K562 cells' resistance to As 2O 3-induced apoptosis.

Viral infections and cell cycle G2/M regulation

Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both human and fission yeast (Schizosaccharomyces pombe) cells, the activity of Cdc2 is regulated in part by the phosphorylation status of tyrosine 15 (Tyr15) on Cdc2, which is phosphorylated by Wee1 kinase during late G2 and is rapidly dephosphorylated by the Cdc25 tyrosine phosphatase to trigger entry into mitosis. These Cdc2 regulators are the downstream targets of two well- characterized G2/M checkpoint pathways which prevent cells from entering mitosis when cellular DNA is damaged or when DNA replication is inhibited. Increasing evidence suggests that Cdc2 is also commonly targeted by viral proteins, which modulate host cell cycle machinery to benefit viral survival or replication. In this review, we describe the effect of viral protein R (Vpr) encoded by human immunodeficiency virus type 1 (HIV-1) on cell cycle G2/M regulation. Based on our current knowledge about this viral effect, we hypothesize that Vpr induces cell cycle G2 arrest through a mechanism that is to some extent different from the classic G2/M checkpoints. One the unique features distinguishing Vpr-induced G2 arrest from the classic checkpoints is the role of phosphatase 2A (PP2A) in Vpr-induced G2 arrest. Interestingly, PP2A is targeted by a number of other viral proteins including SV40 small T antigen, polyomavirus T antigen, HTLV Tax and adenovirus E4orf4. Thus an in-depth understanding of the molecular mechanisms underlying Vpr-induced G2 arrest will provide additional insights into the basic biology of cell cycle G2/M regulation and into the biological significance of this effect during host-pathogen interactions.

Thermodynamic Comparison Analysis on CO_2 Transcritical Reverse Cycles with IHX or Expander

To improve the coefficient of performance （COP） of CO2 transcritical reverse cycle and determine the most efficient cycle, comparison analysis on （single-and） two-stage CO2 transcritical cycles with internal heat exchanger （IHX） or expander is presented adopting the principle of thermodynamics. Results indicate that the COP of four cycles,namely single-stage compression with IHX （SI）, single-stage compression with expander （SE）, two-stage compression with IHX （TI） and two-stage compression with expander （TE）, can be ranged as TE>SE>TI>SI. It presents that adopting an expander to recover expansion power is the primary method to improve the COP of CO2 transcritical reverse cycle if the efficiency of the expander is up to a certain value. Under supposed operating condition, where the outlet temperature of gas cooler is 35 ℃ and the evaporating temperature is 5 ℃, the COP of TE cycle is about 4200 higher than that of SI cycle when the expander efficiency is 0.6 and the degree of superheat of IHX is 15 ℃. Therefore TE cycle is the most recommendatory one and it is better to adopt TE in those high-cooling capacity systems because its technology cost will be higher.

Application of Supercritical CO2 Gas Turbine for the Fossil Fired Thermal Plant

A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.

Theoretical Study on CO_2 Transcritical Cycle Combined Ejector Cycle Refrigeration System

Chlorofluorocarbons(CFCs) or hydrochlorofluorocarbons(HCFCs) are as main refrigerants used in traditional refrigeration systems driven by electricity from burning fossil fuels, which is regarded as one of the major reasons for ozone depletion (man-made refrigerants emission) and global warming (CO 2 emission). So people pay more and more attention to natural refrigerants and energy saving technologies. An innovative system combining CO 2 transcritical cycle with ejector cycle is proposed in this paper. The CO 2 compression sub-cycle is powered by electricity with the characteristics of relatively high temperature in the gas cooler (defined as an intercooler by the proposed system). In order to recover the waste heat, an ejector sub-cycle operating with the natural refrigerants (NH 3, H 2O) is employed. The two sub-cycles are connected by an intercooler. This combined cycle joins the advantages of the two cycles together and eliminates the disadvantages. The influences of the evaporation temperature in CO 2 compression sub-cycle, the evaporation temperature in the ejector sub-cycle, the temperature in the intercooler and the condensation temperature in the proposed system performance are discussed theoretically in this study. In addition, some unique features of the system are presented.

THE SUPPORTED GOLD CATALYSTS FOR CLOSED CYCLE CO_2 LASER

Sealed-off carbon dioxide lasers encounter problem of dissociation of CO2, Which causes the output power to fall. Reformation of CO2 is therefore essential for long life CO2 lasers. Au/Fe2O3 and Au/NiFe2O4 are promising candidates for this application.