Photochemical synthesis of biopolymer coated Aucore-Agshell type bimetallic nanoparticles

Spherical Au nanoparticles have been prepared in the presence of a biopolymer, sodium alginate using UV-photoactivation technique. The particles are sodium alginate coated and are extremely stable. These Au nanoparticles have been used as seed for the synthesis of Aucore-Agshell type bimetallic nanoparticles. Sodium alginate is a carbohydrate-based biopolymer. In this synthesis it acts both as a reducing agent and a stabilizer for the evolved particles. Therefore, no extra capping agent is required from outside to make the generated particle stable. By varying the seed to silver ion ratios and using photoactivation technique Aucore-Agshell type bimetallic nanoparticles with various sizes and compositions have been synthesized. The method is very simple and reproducible and does not need any manipulative skill. Characterizations of these bimetallic nanoparticles have been done from their UV-visible spectroscopy, TEM/EDX, and AFM results. UV-visible extinction spectra reveal that the seed particles have an absorption maxima approximately 527 nm, attributed to the surface plasmon of the pure gold nanoparticles. From the TEM images the particle size of the gold seed particles was calculated to be 8.6 nm. The growth of bimetallic nanoparticles with time has been monitored. The finally evolved bimetallic Aucore-Agshell nanoparticles have a size in the range between approximately 10-14 nm. The particles are very stable and may have the potential for biological and catalytic applications.     

木材经催化热分解向BTX和合成燃料的转化

以废木材生物质的有效利用为目的,使用粉粒流化床反应器,对3种木材进行了催化热分解实验,以4种催化效果不同的粒子作为流化床内的流化介质来考察催化热分解过程中介质颗粒、反应气体和热分解温度对产物分布的影响.木材的挥发性物质在700K时就已几乎分解出来,挥发性物质中的轻质芳香烃碳氢化合物（苯、甲苯、二甲苯和萘：BTXN）的收率随着热分解温度的升高而增加,1173K下达到3.1%（质量分数）,daf.在氢气气氛下,当作为流化介质颗粒Zn(3%,质量分数)/HZSM-5催化剂对木材进行催化热分解时,853K下可得到6.1%, daf的轻质芳香烃碳氢化合物的收率(BTX 5.5%,daf、萘0.6%,daf).而在活性很高的NiMo-A加氢催化剂下,在863K时,催化热分解产物几乎全为甲烷.     

A scheduling method considering register‐to‐register transfers

In high‐level synthesis, scheduling is an important stage which assigns each operation appearing in a data flow graph to a specific control step, whose results influence the design quality directly. This paper describes a scheduling approach for pipelined datapaths. Since few previous approaches estimate the interconnection cost between register (register‐to‐register cost), our approach introduces a datapath model with interconnection between registers across buses, and minimizes the total hardware cost including the register‐to‐register cost by force‐directed scheduling. © 1999 Scripta Technica, Electr Eng Jpn, 128(3): 63–71, 1999     

The dissociation process in plasma-enhanced chemical vapor deposition using tetraethoxysilane

Dissociation in plasma-enhanced chemical vapor deposition for SiO₂ deposition using tetraethoxysilane (TEOS) was investigated by means of mass spectrometry. First we obtained the basic dissociation patterns of TEOS by electron impact. It was shown that TEOS was dissociated by electron impact at low electron energies below 7 eV, removing the ethyl group (C₂H₅). Next we determined dissociation patterns in TEOS/He plasma in order to eliminate the effect of oxidation. Finally, dissociation in TEOS/O₂ plasma was investigated. It was found that oxidation plays an indispensable role in the deposition of high-quality SiO₂ films due to the decrease in high-molecular-weight compounds with carbon and hydrogen, although TEOS is highly dissociated by electron impact. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 32–38, 1999     

Effect on adhesion of new polymerization initiator systems comprising 5‐monosubstituted barbituric acids,aromatic sulfinate amides,and tert‐butyl peroxymaleic acid in dental adhesive resin

To develop a multipurpose dental adhesive resin, the effects of polymerization initiator systems comprising 5‐monosubstituted barbituric acid (5‐MSBA), aromatic sulfinate amide (ASA), and tert‐butyl peroxymaleic acid (t‐BPMA) with 4‐acryloxyethyltrimellitic acid (4‐AET) or its anhydride (4‐AETA) on adhesion and curing time were investigated. Tensile bond strength values of a Ni Cr alloy are affected by the inclusion of t‐BPMA, and the optimum concentration of t‐BPMA in a 5‐MSBA–ASA–t‐BPMA‐type initiator system was found to be 0.5–2.0 wt %, and it was noteworthy that the correlation between the tensile bond strength and curing time on the t‐BPMA‐concentration showed a highly negative correlation of a benzenesulfinate morphoride (BSMo) series adhesive: r = −0.957, and a p‐toluenesulfinate morphoride (p‐TSMo) series adhesive: r = −0.949. The combination of 1‐cyclohexyl‐5‐ethylbarbiturioc acid (CEBA) with ASA provides a high level of tensile bond strength to the Ni Cr alloy, and the optimum concentration of CEBA in a CEBA–ASA–t‐BPMA‐type initiator and the bond strength values were found to be 0.75 wt % CEBA: 52.3 MPa (with BSMo), and 1.0 wt % CEBA: 50.9 MPa (with p‐TSMo), respectively. It was suggested that 5‐MSBA, ASA, and t‐BPMA and their combinations provided the environment where 4‐AETA exhibited good bonding performance with increasing wettability to metal without interference of a charge‐transfer complex derived from a polymerization initiator system such as benzoyl peroxide (BPO)–amine. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1655–1668, 1999     

Robust comprehension of natural language instructions by a domestic service robot

We present a method through which domestic service robots can comprehend natural language instructions. For each action type, a variety of natural language expressions can be used, for example, the instruction, ‘Go to the kitchen’ can also be expressed as ‘Move to the kitchen.’ We are of the view that natural language instructions are intuitive and, therefore, constitute one of the most user-friendly robot instruction methods. In this paper, we propose a method that enables robots to comprehend instructions spoken by a human user in his/her natural language. The proposed method combines action-type classification, which is based on a support vector machine, and slot extraction, which is based on conditional random fields, both of which are required in order for a robot to execute an action. Further, by considering the co-occurrence relationship between the action type and the slots along with the speech recognition score, the proposed method can avoid degradation of the robot’s comprehension accuracy in noisy environments, where inaccurate speech recognition can be problematic. We conducted experiments using a Japanese instruction data-set collected using a questionnaire-based survey. Experimental results show that the robot’s comprehension accuracy is higher in a noisy environment using our method than when using a baseline method with only a 1-best speech recognition result.     

Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature

Using multi-anvil high-pressure devices and synchrotron radiation, X-ray in situ observations of HfO₂ under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high-temperature forms of HfO₂, above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite-type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI-to-orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials.     

A tolerance criterion for tar concentration in a model wood gas for a nickel/scandia-stabilized zirconia cermet anode in a solid oxide fuel cell

Durability of a nickel and scandia-stabilized zirconia cermet anode against toluene in hydrogen was evaluated in this paper. Anode deterioration was judged by the loss of elemental nickel from a surface of an anode. Elemental nickel loss was observed when the toluene concentration was 3 or 10 g/Nm³, steam to carbon ratio was 1, and current density was 0.5 A/cm² at both temperatures: 1073 K and 1173 K. Therefore the tolerance criterion must be less than 3 g/Nm³ in hydrogen in the experimental conditions. However, the deterioration can be mitigated to some extent by increasing the operating temperature, steam-to-carbon ratio, or current density. Anode deterioration was also mitigated when hydrogen concentration in the fuel gas was nearly identical to that of wood gas. The influence of hydrogen concentration in the fuel gas on deterioration may be substantial. The loss of elemental nickel could not be detected instantaneously by electrochemical diagnosis.     

Fabrication of Ni compound nanocrystal/nanocarbon composites by cooling of chloride-based fluxes

Unique Ni compound nanocrystals were successfully grown on carbon nanotubes (CNTs) by cooling a mixed chloride flux. Cup-stacked CNTs (CSCNTs) were used as the nanocarbon materials because of their structural features. The grown nanocrystals had a nanosheet structure, which was densely assembled and had a ribbon-like morphology. Therefore, the nanocrystal/CSCNT composites were expected to have a highly active surface area for the catalyst composites. The selected area electron diffraction pattern and the related radial intensity profiles indicated that the grown nanocrystals were Ni(OH)2. When the pristine CSCNTs were used as a starting material, the formation efficiency of the nanocrystal/CSCNT composites decreased because the pristine CSCNTs were not dispersed in the KCl-LiCl flux. Therefore, functionalization of the CSCNTs was carried out with VUV light irradiation. The dispersibility of the VUV light-treated CSCNTs increased in the KCl-LiCl flux in comparison with the pristine CSCNTs because oxygen-containing functional groups, such as -COOH and -CO, were introduced onto the surfaces of the CSCNTs.