Erbium-doped fiber amplifier for video distribution networks

The possibility of an application of Er-doped fiber amplifiers to AM-FDM (frequency division multiplexing) or FM-FDM video distribution networks is discussed. The measured noise and modulation distortion properties of ER-doped fiber amplifiers are good enough to meet even the severe quality standards set for trunk lines. A carrier-to-noise ratio (CNR) of 57 dB for an AM-FDM transmission was measured. A second-order harmonic distortion (HD2) of less than -56 dB was measured by the monotone method (modulation depth m=50%), and a cross modulation distortion (XM) of less than -63 dB was measured by the two-tone method (m=25%×channel). On the basis of these values, composite second-order distortion (CSO) and XM in a 40-channel transmission were estimated as less than -57 dB and -73 dB, respectively. Significant reduction of noise and modulation distortion is made possible by optimizing the length of Er-doped fiber amplifiers and using input- and output-port isolators     

Interfacial microstructure and strength of steel/aluminum alloy joints welded by resistance spot welding with cover plate

We joined aluminum alloy A5052 to cold-rolled steel SPCC (Steel Plate Cold Commercial) and austenitic stainless steel SUS304 using resistance spot welding with a cover plate. The interfacial microstructure was observed using transmission electron microscopy. A thick two-layered reaction layer contains Fe₂Al₅ and FeAl₃ and a thin serration reaction layer contains Fe₂Al₅ and FeAl₃ were observed at the A5052/SPCC and A5052/SUS304 interface, respectively. Mechanical property analysis suggested that the reaction layer has no effect on the tensile shear strength of the A5052/SUS304 joint and that the tensile shear strength of the A5052/SPCC joint is influenced by the reaction layer formed at its interface.     

Towards a local learning (innovation) model of solar photovoltaic deployment

It is by now familiar that in the deployment of solar photovoltaic (PV) systems, the cost dynamics of major system component like solar cell/module is subjected to experience curve effects driven by production learning and research and development at the supplier side. What is less clear, however, is the economics of system integration or system deployment that takes place locally close to the user, involving other market players, in the downstream solar PV value chain. Experts have agreed that suppliers of solar PV system must customize their flexible characteristics to address local unique users’ and applications requirements and compete on price/performance basis. A lack of understanding of the drivers of the economics of system customization therefore is a deficiency in our understanding of the overall economics of this renewable energy technology option.     

Poly(4-diphenylaminostyrene) with a well-defined polymer chain structure: Controllable optical and electrical properties

The effect of polymer chain structure on the optical and electrical properties are reported for poly(4-diphenylaminostyrene) (PDAS), which was prepared by the living anionic polymerization of 4-diphenylaminostyrene (DAS) with the benzyllithium (BzLi)/N,N,N′,N′-tetramethylethylenediamine (TMEDA) system. The optical properties of PDAS are strongly affected by the stereoregularity of the PDAS polymer chain; intramolecular excimer-forming fluorescence was observed from PDAS with a syndiotactic-rich configuration. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of PDAS were approximately −5.4 and −2.0 eV, respectively, regardless of the polymer chain structure. The hole and electron drift mobilities for PDAS were in the order of 10⁻⁴ to 10⁻⁵ (cm²/V s) and 10⁻⁵ (cm²/V s), respectively, with negative slopes. The distance of each triphenylamino (TPA) group in the polymer chain was a major factor influencing the drift mobility of PDAS. The current-voltage (I-V) characteristics of PDAS were controllable according to the polymer chain structure of PDAS.     

Burning velocities and kinetics of H2/NF3/N2, CH4/NF3/N2, and C3H8/NF3/N2 flames

The combustion characteristics and reaction mechanism of mixtures containing nitrogen trifluoride (NF₃) were investigated. Burning velocities for H₂/NF₃/N₂, CH₄/NF₃/N₂, and C₃H₈/NF₃/N₂ flames were determined for the first time at various equivalence ratios and N₂ mole fractions. The burning velocities of the latter two flames were similar and showed peaks at equivalence ratios of ∼1.0, while those of the H₂/NF₃/N₂ flames had the pronounced peak at low equivalence ratios where the formation of the wrinkled flames was observed. A detailed kinetic model was constructed to simulate the laminar burning velocities of H₂/NF₃/N₂ and CH₄/NF₃/N₂ flames. The model accurately reproduced the experimental results. Analyses of the reaction mechanism revealed the major reaction pathways that involve the decomposition of NF₃, the oxidation and chain-fluoridation of H₂ and CH₄, and the formation of N₂.     

High-performance liquid chromatographic analysis of chlorhexidine in saliva after mouthrinsing

BACKGROUND: Neutrophils contribute to the host defense mechanism, but they can cause remote organ injury in peritonitis. The purpose of this study was to examine neutrophil adhesion to the peritoneum and remote organs simultaneously in peritonitis using a fluorescence microscopic method. STUDY DESIGN: Experiment 1: Sprague-Dawley rats (n = 16) were injected intraperitoneally (ip) with saline solution or 10(5), 10(7), or 10(9) Escherichia coli. Five hours after challenge, 1 x 10(6) fluorescein-labeled neutrophils were infused. Two minutes after neutrophil injection, five peritoneal samples (the greater omentum, mesentery, parietal peritoneum, colon, and ileum), both lungs, the liver, and the right kidney were harvested for counting of labeled neutrophils under epifluorescent microscopy. Lung myeloperoxidase (MPO) activity was also determined. Experiment 2: Rats (n = 23) were given 10(9) E. coli ip. Before challenge (0 h) or at 1, 5, or 10 h after challenge, labeled neutrophils were infused. Then, the labeled neutrophil numbers in organs and lung MPO activities were assessed as described for Experiment 1. Hemodynamic and arterial blood gas data were also obtained in another set of rats before and at 1, 5, 8 and 10 h after 10(9) E. coli ip challenge. RESULTS: Experiment 1: The labeled neutrophil numbers in the peritoneum, lungs, and kidney showed significant positive correlations with the injected bacterial numbers. Lung MPO also positively correlated with E. coli number and labeled neutrophil number in the lungs. Experiment 2: Labeled neutrophil numbers in the peritoneum and kidney peaked at 5 h. The pulmonary labeled neutrophil number rose, reaching a plateau at 5 h. No remarkable change was observed in the hepatic labeled neutrophil number. There was a positive correlation between lung MPO activity and pulmonary labeled neutrophil number. Hemodynamic and blood gas data reflected a hyperdynamic state. CONCLUSIONS: Concomitant dose-dependent increases in neutrophil adhesion in the peritoneum, lungs, and kidney were observed in this peritonitis model. Increased neutrophil adhesion was transient in the peritoneum and kidney but persistent in the lungs. Strategies modulating neutrophil adhesion in organs are anticipated to be useful for the treatment of peritonitis.     

Advanced energy saving in the reaction section of the hydro-desulfurization process with self-heat recuperation technology

The reaction section of the naphtha hydro-desulfurization (HDS) process is a heating and cooling thermal process consisting of a feed/effluent heat exchanger and a fired heater. Energy savings are fundamentally made as a result of the maximized heat recovery in the heat exchanger and the reduced heat duty of the fired heater. To achieve further energy saving in the process, “self-heat recuperation technology” (SHRT) was adopted. In this technology, a compressor was introduced. The suction side of the compressor needed a lower pressure and the feed stream evaporated much easily. The discharged side of the compressor satisfied the operating conditions of both pressure and temperature at the inlet of the reactor. And the reactor effluent stream was able to be used completely to preheat and vaporize the feed stream. All the heat in the process stream was re-circulated without using a fired heater. SHRT was applied to the naphtha HDS process of 18,000 barrel per stream day (BPSD) in the refinery and the mass and energy balance of the process was calculated using commercially available simulation software, Invensys PROII version 8.1. This process-simulation case study confirmed that despite there being no more energy saving potential in the conventional process that makes use of a fired heater, the advanced process with SHRT can reduce the energy consumption significantly by using the recuperated heat of the feed stream.     

Synthesis of porphyrin-end-functionalized poly(p-phenylene) as a leaf-green-colored soluble semiconducting polymer: Control of π–π interactions for visible-light absorption

The synthesis of tetraphenylporphyrin (H₂TPP)-end-functionalized poly(p-phenylene) (H₂TPP-PPP) as a leaf-green-colored soluble semiconducting polymer with a well-controlled and defined polymer chain structure was achieved for the first time. Chloromethyl-end-functionalized poly(1,3-cyclohexadiene) (CM-PCHD) was prepared by the living anionic polymerization of 1,3-cyclohexadiene and the post-polymerization reaction of poly(1,3-cyclohexadienyl)lithium and chloro(chloromethyl)dimethylsilane. H₂TPP-end-functionalized PCHD (H₂TPP-PCHD) was then prepared by the addition of 5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin to CM-PCHD. The dehydrogenation of H₂TPP-PCHD with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone was performed under ultrasonic irradiation, and H₂TPP-PPP was obtained as a target polymer in almost quantitative yield. The –Si(CH₃)₂–CH₂–O– bond in H₂TPP-PPP effectively inhibited the coordination of the H₂TPP end-group onto the PPP moiety, and the aggregation of H₂TPP-PPP with the accumulation of the H₂TPP end-group was formed. H₂TPP-PPP exhibited a leaf-green color and had a very broad absorption band overlapping the visible-light region, similar to chlorophyll a.     

An innovative modularity of heat circulation for fractional distillation

A novel modularity of heat circulation for distillation process, which reduces the energy consumption, is proposed. By incorporating compressors and heat exchangers, the heat of the distillate is recuperated and exchanged with the heat of the feed streams. The proposed technology achieves the reduction in the required energy more than 75% as compared with a benchmark process which uses external heat source for heating. This shows the proposed modularity of heat circulation for distillation process is very promising technology to drastically reduce energy demand for distillation.