Simultaneous determination of dissolved organic carbon and phosphorus in waters using flame ionization and photometric detectors

An apparatus with flame ionization and photometric detectors was assembled for the simultaneous determination of dissolved organic carbon (DOC) and phosphorus (DP) in waters. The optimum operating conditions were described. The long-term precision (relative standard deviation) is 5.8% for DOC and 5.2% for DP. The detection limits are 0.09 μg ml⁻¹ for DOC and 0.03 μg ml⁻¹ for DP. The responses for various DOC and DP compounds agreed almost with those obtained by combustion-infrared and persulfate digestion-colorimetric methods, respectively. DOC and DP in several water samples were determined by this method and other methods, and the results obtained by those methods were discussed.     

Effect of molding pressure on fabrication of low-crystalline calcite block

We have reported that low-crystalline porous calcite block, which is useful as a bone substitute or a source material to prepare apatite-type bone fillers could be fabricated by exposing calcium hydroxide compact to carbon dioxide gas saturated with water vapor. In the present study, we investigated the effect of molding pressure on the transformation of calcium hydroxide into calcite and the mechanical strength of the carbonated compact. Transformation into calcite was almost completed within 72 h, however, a small amount of Ca(OH)₂ still remained unreacted at higher molding pressure because of incomplete penetration of CO₂ gas into the interparticle space due to dense packing of Ca(OH)₂ particles. On the other hand, high molding pressure resulted in an increase in diametral tensile strength (DTS) of the calcite compact formed. Critical porosity of the calcite block was calculated as approximately 68%.     

Dehydration of d-glucose in high temperature water at pressures up to 80 MPa

Reaction of d-glucose in water to yield 5-hydroxymethylfurfural (5-HMF), 1,2,4-benzenetriol (BTO) and furfural was studied at high temperatures (up to 400 °C) and high pressures (up to 80 MPa) using a continuous flow reactor. Maximum temperature and pressure conditions gave maximum furfural yield. Increasing pressure from 40 to 70 and 80 MPa enhanced dehydration reactions to 5-HMF, but also enhanced hydrolysis of 5-HMF leading to the production of BTO and thus lead to lower yields of 5-HMF (below 10%). Remarkably, the dehydration reaction to 5-HMF and the hydrolysis of 5-HMF were both enhanced by the increase in water density at 400 °C.     

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     

Development of an on‐line partial discharge monitoring system for gas insulated substations

This paper describes the results of tests and discussions carried out to develop a system for partial discharge monitoring in GIS. They include the propagation characteristics of partial discharge pulses in each GIS component, as well as the test results obtained using an actual 300‐kV GIS. We also report the results of verification test on the GIS partial discharge monitoring and location system developed by the authors. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 40–50, 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