Showing papers in "Journal of Advanced Science in 2001"
TL;DR: In this article, a Life Cycle Sustainability methodology and database has been developed for the development of sustainable products, which integrates the new Life Cycle Working Time approach for the most important work-related social issues like qualified working time, accidents, child work, working environment conditions, woman work etc.
Abstract: The development of sustainable products requires the consistent modelling of ecological, economic, and social aspects along the Life Cycle of the product A Life Cycle Sustainability methodology and database has been developed. It integrates the new Life Cycle Working Time approach for the most important work-related social issues like qualified working time, accidents, child work, working environment conditions, woman work etc. into the established Life Cycle Engineering methodology of IKP and the respective Software System GaBi. Focus of the approach is to provide reliable decision support while at the same time securing its applicability in practice through caring for data availability, international comparability, process-relatedness and other criteria. The methodology is presently applied in practice in an ongoing international project developing sustainable, biosource based foam products.
24 citations
TL;DR: Kosaku YAMADA, Ryuma FUJIMOTO, Shinichi SUEHIRO and Hidekazu SUEYOSHI Department of Mechanical Engineering at Kagoshima University.
Abstract: Kosaku YAMADA, Ryuma FUJIMOTO, Shin-ichi SUEHIRO and Hidekazu SUEYOSHI Department of Mechanical Engineering, Faculty of Engineering, Kagoshima University 1-21-40,Korimoto,Kagoshima, 890-0065 Japan TEL: 81-99-285-8260 FAX: 81-99-250-3181 e-mail: d12014@mech.kagoshima-u-ac.jp Nurul Taufiqu ROCHMAN Japan Science and Technology Corporation, Domestic Research Fellow Kagoshima Prefectural Institute of Industrial Technology, 1445-1 Oda, Hayato-cho, Aira-gun,Kagoshima, 899-5105 Japan TEL: 81-995-43-5111 FAX: 81-995-64-2111 (Received 1, October 2001 Accepted 7, December 2001)
15 citations
TL;DR: In this paper, the zeolite formation process was studied to promote the utilization of aluminum phosphate and showed the methylene blue adsorption capacity of 90mg (methylene blue)/g.
Abstract: Incinerated ashes of sewage treatment sludge contain significant amount of phosphorus. Phosphorus is a very important material, and studies on phosphorus recovering technology are going under way. However, the phosphorus recovered from this sludge is mainly composed of aluminum phosphate. To promote the utilization of aluminum phosphate, zeolite formation process was studied. On the run 1, phosphorus recovered from incinerated ash of sewage treatment sludge by using H2SO4 and NaHCO3 was treated with NaOH, which dissolves aluminum phosphate and extracted aluminum phosphate reacted with aqueous sodium silicate solution to form zeolite. In this reaction, zeolite was recovered by freezing treatment followed by recovering of Na3PO4 by vaporization. On the run 2, phosphorus recovered by using of sulfuric acid and calcium carbonate was treated with NaOH in the same way as run 1. Aluminum phosphate reacted with calcium sulfate by alkalization formed calcium phosphate. Phosphorus free aluminum reacted with sodium silicate to form zeolite, and Na2SO4. Recovered zeolite showed the methylene blue adsorption capacity of 90mg (methylene blue)/g.
9 citations
TL;DR: This study addresses the development of a consistent method for definition of system boundary using an economic input-output table, which describes all the flows of goods and services between sectors of an economy.
Abstract: Fair definition of system boundary is essential for obtaining reliable results in life cycle assessment (LCA), especially in comparative LCA studies. However, it doesn't seem that a consensus has been reached on an appropriate method for selecting system boundary. This study addresses the development of a consistent method for definition of system boundary using an economic input-output table, which describes all the flows of goods and services between sectors of an economy. The method proposed within this paper 1) is quantitative, 2) is objective 3) is reproducible, 4) is available without detail process-LCI, 5) requires little time and cost, and 6) doesn't overlook any process that significantly influences LCA results. This method is demonstrated on complicated production system of a passenger car in terms of CO2 emissions.
7 citations
7 citations
TL;DR: In this paper, two dischargeplasma systems, such as a Dielectric Barrier Discharge (DBD) and Packed Bed Reactor (PBR), were investigated in a nitrogen stream under an atmospheric condition.
Abstract: In a nitrogen stream under an atmospheric condition, NOx decomposition was investigated using two discharge-plasma systems, such as a Dielectric Barrier Discharge (DBD) and Packed Bed Reactor (PBR). In the absence of oxygen, the decomposition in the former system started at input voltage of 1kV and showed 100% conversion at 1.5kV, whereas that in the latter system started at 2kV and showed 100% at 3.5kV. With the increase of O2 concentration, the conversion rapidry decreased in the both reactors.
6 citations
TL;DR: In this article, the effects of tungsten and cobalt on the effect of the microstructure of a full-annealed 0.1C-15Cr-1Mo-3W 0.003B steel has been investigated and it has been concluded that this steel should be one of the candidate materials for low emission power plant.
Abstract: Creep strength property of a full-annealed 0.1C-15Cr-1Mo-3W 0.2V-0.05Nb-0.07N-0.003B steel and the effects of tungsten and cobalt on that have been investigated. Contrary to a tempered martensite microstructure of the conventional ferritic creep resistant steels, microstructure of full-annealed 15Cr steel is mainly ferrite. Increases in creep strength at 923K with increase in tungsten content and addition of cobalt have been obviously observed, especially with a combination of increase in tungsten content and addition of cobalt. Higher Cr content of full-annealed 15Cr steel than those of the conventional ferritic creep resistant steels is desirable for better oxidation resistance. It has been concluded that full-annealed 15Cr ferritic creep resistant steel should be one of the candidate materials for a low emission power plant.
6 citations
TL;DR: In this paper, the effect of production and treatment of fibers and semi-finished products like hybrid nonwovens and the process parameters on the properties of the part produced were studied.
Abstract: The most common methods of processing natural fibers have been tested in the production of glass-fiber reinforced polymers. This can result in problems due to inadequately adapted process parameters. Therefore the effect of production and treatment of fibers and semi-finished products like hybrid nonwovens and the process parameters on the properties of the part produced were studied. The material technology is available for using natural fibers as reinforcing agents, however, only a few effective products exist. The fiber/matrix interface is of great significance for the quality of the composite material. It can be characterized by means of the IR-spectroscopy, the scanning electron microscopy and by the determination of the mechanical properties. The fiber/matrix interaction can be improved significantly if the natural fibers are purified and alkalized, coupling agents are applied and the manufacturing process of the system natural fiber/thermoplastics is optimized.
6 citations
TL;DR: In this article, two possible energy systems for the post-fossil fuel era are compared with the present fossil fuel system by taking into consideration production costs, environmental damages and utilization efficiencies.
Abstract: Fossil fuels (i.e., petroleum, natural gas and coal), which meet most of the world energy demand today, are being depleted fast. Also, their combustion products are causing the global problems, such as the greenhouse effect, ozone layer depletion, acid rains and pollution, which we are posing great danger for our environment and eventually for the life in our planet. Many engineers and scientists agree that the solution to these global problems would be to replace the existing fossil fuel system by the Hydrogen Energy System. Hydrogen is a very efficient and clean fuel. Its combustion will produce no greenhouse gases, no ozone layer depleting chemicals, little or no acid rain ingredients and pollution. Hydrogen, produced from renewable energy (e.g., solar) sources, would result in a permanent energy system, which we shall never have to change. However, there are other energy systems proposed for the post-petroleum era, such as a synthetic fossil fuel system. In this system, synthetic gasoline and synthetic natural gas will be produced using abundant deposits of coal. In a way, this will ensure the continuation of the present fossil fuel system. The two possible energy systems for the post-fossil fuel era (i.e., the solar hydrogen energy system and the synthetic fossil fuel system) are compared with the present fossil fuel system by taking into consideration production costs, environmental damages and utilization efficiencies. The results indicate that the solar hydrogen energy system is the best energy system to ascertain a sustainable future.
6 citations
TL;DR: In this article, a grain refinement was successfully completed by applying ultrasonic vibration during the solidification process of aluminum cast alloys, and the refinement mechanism was clarified to determine the temperature range to apply the optimum vibration.
Abstract: Grain refiner has conventionally been added during the casting process of grain refinement, but it has recently become a recycling problem, which calls for the efforts for development of a new grain refinement method. In this paper, a technological breakthrough has been achieved, where grain refinement was successfully completed by applying ultrasonic vibration during the solidification process of aluminum cast alloys. The refinement mechanism was clarified to determine the temperature range to apply the optimum vibration.
6 citations
TL;DR: In this paper, the surface energy change of a sapphire lens was estimated by extended Fowkes theory and the dominant factor of wettability change is dipole factor on EB irradiated sappire lens.
Abstract: Wettability of sapphire lens was changed by electron beam irradiation. Surface energy change of sapphire lens was estimated by extended Fowkes Theory. The dominant factor of wettability change is dipole factor on EB irradiated sapphire lens.
TL;DR: In this article, the relationship between sleep rating scales (OSA, KSS) and measured all-night sleep EEG was investigated with healthy adult volunteers, and the results showed that the KSS ratings correlated with time percentage of non-REM sleep state.
Abstract: To investigate the relationship between sleep rating scales (OSA, KSS) and measured all night sleep EEG, experiments were carried out with healthy adult volunteers. Results showed that the KSS ratings correlated with time percentage of non-REM sleep state. The OSA ratings correlated with waking time in the experimental night. In evaluation of the quality of sleep, some attention should be paid to subjective ratings of the sleep.K eywords: OSA, KSS, sleep, EEG
TL;DR: In this article, the flow of materials driven by the production of products in the manufacturing sector is studied. But the focus of the paper is not on the manufacturing process, but on the materials used in the process.
Abstract: “Environmentally Benign Manufacturing” is a new approach to manufacturing which attempts to reconcile economic growth and environmental protection. EBM is the manufacturing part of the industrial ecology movement. Its goal is sustainability and its methods are based upon scientific understanding and technology development in concert with policy development.1) “Ecomaterials” is a concept developed in Japan in the 1990s that considers the broad implications of material use on society. It shares many of the same goals as EBM and industrial ecology but from a materials development point of view. As such it has served as a major research approach at many distinguished Japanese research laboratories over the past ten years.2) In this paper, we look at the flow of materials driven by the production of products in the manufacturing sector.
TL;DR: In this article, the authors investigated the catalytic performance of copper on silicon carbide (Cu/SiC) catalyst in the production of hydrogen for fuel cell applications and found that the performance of the catalyst is highly dependent upon the calcmation temperature of the catalysts.
Abstract: Methanol steam reforming reaction over copper on silicon carbide (Cu/SiC) catalyst was investigated in the production of hydrogen for fuel cell applications. Catalytic performances (activities, hydrogen production amount and concentration of carbon monoxide (CO)) were highly dependent upon the calcmation temperature of the catalyst. The calcination at the temperature below 1073K in air leads to formation of amorphous silica (SiO2) layer on the surface of the catalyst, which stabilizes Cu active sites against sintering during reactions.
TL;DR: In this paper, a composite with 28 vol% TbFe2 exhibited 820ppm strain at 15kOe of applied field and 5.5×10-2 g·hour-1 when immersing the composite in 1M-HCl.
Abstract: Tough and high corrosion resistant giant magnetostrictive composite with high cost performance was developed. Acrylic resin powder was mixed with TbFe2 powder sized from 40 to 75μm. The mixture was formed in a mold at 120°C under 4.4×108Pa for 30min.A composite with 28 vol% TbFe2 exhibited 820ppm strain at 15kOe of applied field. The corrosion rate was 5.5×10-2 g·hour-1 when immersing the composite in 1M-HCl. It was found that corrosion resistance increased by about 15 times compared with that of a giant magnetostrictive bulk material.
TL;DR: In this paper, the effects of microstructural factors and alloying elements on dezincification of (α+β) brass were revealed by melting pure Cu, Zn and Alloying elements and then pouring into a metal mold with three different solidification rates.
Abstract: From the viewpoint of ecomaterals, development of dezincification resistant Pb-less brass is required. In order to reveal the effects of microstructural factors and alloying elements on dezincification of (α+β) brass, the brasses with different β phase area ratio and mean grain size of α phase were prepared by melting pure Cu, Zn and alloying elements and then pouring into a metal mold with three different solidification rates. Dezincification corrosion of the casting brass was examined by means of galvanostatic anodic polarization test. The results show that the mean and maximum dezincification depths of Cu-Zn system decrease with the decrease of the mean grain size of α phase. However, reduction of the dezincification depth by only controlling the microstructural factors has a limitation. The dezincification can be retarded significantly by the addition of a small amount of P and the refinement of the mean grain size of α phase with controlling the solidification rate.
TL;DR: In this paper, the CRAZY and non-craze regions were processed using the unique crazing technique, and a characteristic morphology of this crazed composites indicates that a transparent film from a normal viewpoint (view field selectivity) was observed.
Abstract: Mono-component polymer composites are made of materials with the two components of the different high order structures. The mono-component polyester composites consisted of the craze and non-craze regions, which were processed the unique crazing technique. A Characteristic morphology of this crazed composites indicates that a transparent film from a normal viewpoint and an opaque film from a tilted angle viewpoint (view field selectivity) were observed. Mono-component polyester composites are ecomaterials for the separating-free of components and the suitability of a regenerated PET.
TL;DR: In this paper, the microstructure of the CC steels containing high impurities has been established through solidification and thermo-mechanical treatment, and the local equilibrium calculation was made to discuss the γ grain growth behavior in the solidification path.
Abstract: Continuously cast (CC) 0.1mass% C steels with or without P addition have been produced, and their microstructures have been characterized. The process to optimize the microstructure of the CC steels containing high impurities has been established through solidification and thermo-mechanical treatment. Although rapid solidification is effective in refining the γ grain structure and for dispersing the segregation of impurities finely, P addition changes the α grain structure dramatically and decreases the γ-grain size. Based on the mapped EPMA data for P and Mn, the local equilibrium calculation was made to discuss the γ grain growth behavior in the solidification path. Since phosphorus stabilizes the δ-ferrite and lowers the transformation temperature from δ to γ, the pinning effect of the δ-ferrite on the γ-grain boundary migration is expected in the temperature range of the rapid γ grain growth. The Mn segregation was also reduced with the P addition.
TL;DR: In this article, the magnetostriction of the microgravity sample was larger than the terrestrial gravity sample, and it has been growing interest that the alloy solidification under the micro-gravity environment yields a unique morphology.
Abstract: TbFe2 exhibits huge magnetostriction over 1000ppm. However, it is very difficult to control microstructure of TbFe2 for the peritectic reaction in solidification. It has been growing interest that the alloy solidification under the microgravity environment yields a unique morphology. The magnetostriction of the microgravity sample was larger than the terrestrial gravity sample.
TL;DR: In this paper, an ultrafine grain structure is introduced to low carbon steels to suppress the detrimental effects by the high content of P. The addition of P increases the tensile strength even in an ultra-fine ferrite-cementite microstructure as well as in a ferritepearlite micro-structure.
Abstract: Phosphorus is an element that is highly effective for solid solution strengthening, but its content is kept at minimum in steel making, because an increase in the P content decreases the toughness, especially after quenching and tempering, such as the 50% Charpy absorbed energy transition temperature and the Charpy absorbed energy at low service temperatures. On the other hand, grain refinement improves the toughness of low carbon steels. In this study, an ultrafine grain structure is introduced to low carbon steels to suppress the detrimental effects by the high content of P. The addition of P increases the tensile strength even in an ultra-fine ferrite-cementite microstructure as well as in a ferrite-pearlite microstructure. The 0.1wt. % addition of P decreases the Charpy absorbed energy of the ferrite-pearlite (FLP) and the quench-and-tempered specimens considerably at 233K. On the other hand, the ultra-fine ferrite-cementite specimen with a 0.1wt. % P shows a value that is comparable to that of the F/P specimen without P. The 50% Charpy absorbed energy transition temperature is concurrently improved by the grain refinement.
TL;DR: In this article, CaSiO3 has been used to create Ca2SiO4, Ca3SiO5,Ca3Si2O7, and Ca4SiO6.
Abstract: I.INTRODUCTION Ca-si-O 3元 系にはCasiO3(α 相、 β相)の 他、 Ca2SiO4(α 相、 β相)、Ca3SiO5、Ca3Si2O7な ど多 く の化合物が存在する。その中ではCaSiO3が 最も研究され ており、最近ではマシナブルセラミックスや超伝導物質の 基板などへの応用研究も進んでいる。1しかし、CaSiO3を 除く他の化合物合成法や性質はほとんど知られていない。 その原因として、それらの化合物が高融点であること、あ るいはこの系の複雑な相関係のため、2純度の高い単相試料 を得るのが困難であることが挙げられる。 これまで、 CaSiO3の 合成にはCaCO3とSiO2を 出発原料として使用 する固相反応法、あるいは溶融後、結晶化する方法が一般 には用いられている。共沈法も試みられており、硝酸カル シウムとテ トラエ トキシシランのエタノール溶液に濃ア ンモニア水を加えて作製した共沈物を1000°C で2時 間加 熱させることによりβ-CaSiO3単 相が得られている。3 本研究では、ゾルゲル法を取り上げ、CaSiO3お よび Ca2SiO4に ついて単相を得るための合成条件を検討 した。 ゾルゲル法は、微粉末、良混合体が得られ反応が進行 しや すいため、高融点セラミックス物質を低温で作製するのに 有効である。本実験では、金属カルシウムとテ トラメトキ シシランを用いて作製されたゲルを加熱することにより、 CaSiO3お よびCa2SiO4を 作製すると共に、その合成過程 をX線 回折により明らかにする。また、通常の固相反応で 作製 した場合と比較する。
TL;DR: In this paper, high-temperature oxidation of heat-resistant alloys with small amounts of sulfur and reactive elements (Y, Hf) was studied for 1800ks in air at 1373K.
Abstract: High-temperature oxidation of heat-resistant alloys with small amounts of sulfur and reactive elements (Y, Hf) was studied for 1800ks in air at 1373K. The mass changes of the 2, 53, 104 and 171ppmS were 0.5-0.9×10-2kg/m2. On the other hand, the mass changes of the 5, 185, 491 and 1300ppmS were less than 0.2×10-2kg/m2 or negative values because of marked spalling of oxide scale on the alloys. Oxide on the 1300ppmS was convoluted, and those on the alloys with reactive elements were planar morphology. The formation of planar morphology on the oxide and that of stable reactive elements sulfide particles may lead to good oxide adherence.
TL;DR: In this paper, the functionality controllable lignin-based polymers (lignophenols) with 1, 1-bis (aryl) propane units were synthesized.
Abstract: Through the phase-separation system, the functionality controllable lignin-based polymers (lignophenols) with 1, 1-bis (aryl) propane units were synthesized. Ligno-p-cresol with the reactive sites on the Cl-cresolic and the terminal phenolic units were hydroxymethylated (HM) to give network-type polymers by heating. On the other hand, ligno-2, 4-dimethylphenol with reactive sites only on the terminal phenolic units gave linear-type polymers. The polymerization of lignophenols could be controlled by mixing HM-ligno-p-cresol and HM-ligno-2, 4-dimethylphenol. Under alkaline conditions, the resulting polymers were depolymerized effectively to small fragments by the switching function (nucleophilic attack of C1-phenolic nuclei to C2). The recyclable composites with high dimensional stability were prepared by the combination of cellulose and HM-lignophenols. Using the switching function of lignophenols, the composites were re-separated into lignophenols and cellulose.
TL;DR: In this paper, the surface hot shortness due to copper is attributed to Cu and removal of Ni is difficult in the current refining process, therefore other ways of the suppression are desired.
Abstract: In recent years, the necessity of the promotion of steel recycling is increasing from the viewpoints of effective usage of resources and restraint of environmental problems. In case steel scrap is recycled, surface cracks occur during hot rolling process, which poses a serious problem. This phenomenon is attributed to Cu. Copper is mixed from steel scrap and Cu in steels is enriched at the steel/scale interface by selective oxidation of Fe. This copper-enriched phase liquefies over 1083°C and penetrates into austenite grain boundaries to cause surface cracking. This cracking is called surface hot shortness due to Cu. To suppress this shortness, addition of Ni is known effective. But removal of Ni is difficult in the current refining process. Therefore, other ways of the suppression are desired. In this research, in order to know the detail of the shortness effects of C and P on the surface hot shortness are investigated.
TL;DR: In this paper, a new index aggregation approach is proposed which is intended to give a measure of dematerialization by considering also the relative availability of the materials used, in order to identify and quantify the main factors contributing to changes in material use.
Abstract: One way by which the use of materials may cause environmental impacts is its potential contribution to resource depletion. Dematerialization-that is the decrease in the material intensity of the economy-may, therefore, be considered as a suitable way to a more sustainable use of materials. An objective and quantitative analysis of this phenomenon entails the application of suitable “dematerialization indices”. After a critical review of the most widespread indices in the literature and of their limitations, a new index aggregation approach is here proposed which is intended to give a measure of dematerialization by considering also the relative availability of the materials used. Moreover, in order to identify and quantify the main factors contributing to changes in material use, a simple model of decomposition analysis applied to material use is suggested.
TL;DR: In this paper, high-level crystallized tungstate and molybdate films were prepared on substrates in alkaline solutions (PH=13) containing alkaline-earth ions by electrochemical method using constant direct current treatment for 50mins.
Abstract: Highly crystallized tungstate and molybdate films (including SrWO4, CaWO4, BaWO4, CaMoO4, BaMoO4, SrMoO4 films) were prepared on substrates in alkaline solutions (PH=13) containing alkaline-earth ions by electrochemical method using constant direct current treatment for 50mins. in the range of (the current density is 1-1.5mA/cm2) at room temperature. The results of SEM and XRD measurement of the films show that they have single tetragonal structure of scheelite-type crystals and the average grain size of the films is 1-5μm for different kind of the films.
TL;DR: Fukushima et al. as discussed by the authors proposed an environment-conscious life-cycle design (eco-life-cycle-design) for new external thermal insulation systems, which can be used for building construction.
Abstract: Environment-conscious life-cycle design (eco-life-cycle-design) for new external thermal insulation systems Toshio FUKUSHIMA and Koji TAKASU Faculty of Environmental Engineering, University of Kitakyushu, 1-1, Hibikino, Wakamatsu, Kitakyushu, Fukuoka, 808-0135, Japan TEL: x81-93-695-3238 FAX: x81-93-695-3338 e-mail: fukushima@env.kitakyu-u.ac.jp Junko IDOGAWA Independent Administrative Institution Building Research Institute, 1-Tachihara, Tsukuba, Ibaraki 305-0082, Japan TEL: x81-298-64-2151 FAX: •x81-298-64-6772 (Received 7, November 2001 Accepted 7, December 2001)
TL;DR: The present review applied CLSM to the specimens prepared for optical microscopy, and demonstrated the intracellular identification of subcellular organelles and protein, which were comparable to those observed under electron microscopy.
Abstract: The recent development of optical microscopy has brought about a more refined and sophisticated apparatus, such as a confocal laser scanning microscopy (CLSM), which was originally described by Minsky (1957), and ever since has been applied to the field of medical biology. In early experiments, only fluorescent signals were detectable by CLSM. However, recent innovations have prompted the possible visualization of non-fluorescent signals such as horseradish peroxidase (HRP) and diaminobenzidine (DAB) signals by CLSM. Moreover, the combination of CLSM and image analysis system (IAS) has enabled us successfully to visualize subcellular organelles three dimensionally (3D) in routinely processed optical microscopic specimens.In the present review, we applied CLSM to the specimens prepared for optical microscopy, and demonstrated the intracellular identification of subcellular organelles and protein, which were comparable to those observed under electron microscopy. We also applied this microscopy to the observation of tumor angiogenesis and microvessel environment of tumor cells. Both the visualization of subcellular organelles, mRNA and protein products, and 3D images of microvessel environment of tumor cells are discussed in this review.
TL;DR: In this paper, life cycle inventory analyses for Pb solder and Pb-free solders were conducted to evaluate CO2 emissions during the life cycle of the solders, and it was concluded that Pb free solders has superior performance in the view of life cycle CO 2 emissions.
Abstract: Life cycle inventory analyses for Pb solder and Pb-free solder were conducted to evaluate CO2 emissions during the life cycle of the solders. CO2 emissions in material production, waste treatment and recycling of Pb solder and Pb-free solder were calculated and quantified. In the case of recycling, effective recycle rate and CO2 emission intensities of solders at the recycle rate were investigated. Life cycle CO2 emissions of Pb solder were larger than those of Pb-free solders due to large energy consumption required for rigid waste treatment (Pb solder: 83.0, Pb-free solder: 2.88 (kg-CO2Ikg-solder)). In the case of recycle system, it was found that the total CO2 emissions of Pb-free solders were smaller than those of Pb solder (Pb solder: 18.3, Pb-free solder:2.88 (kg-CO2/kg-solder)). It was concluded that Pb-free solder has superiority to Pb solder in the view point of life cycle CO2 emissions.