Compensation for neutral current harmonics in a three-phase four-wire system by a synchronous machine

This paper presents a new method that passively reduces the neutral current harmonics in a three-phase four-wire system by a synchronous machine. Selecting 2/3 as the coil pitch of the armature winding can minimize the zero-sequence reactance of the synchronous machine. The proposed method utilizes such a characteristic, which allows harmonic compensation by the synchronous machine. For analysis and design, an equivalent circuit for the third harmonic component of the basic system is derived. Using this equivalent circuit, its harmonic compensation characteristics are theoretically analyzed and design fundamentals are provided. Experimental results demonstrate the effectiveness of the proposed method and validate the theoretical analysis.     

Fischer–Tropsch synthesis in slurry-phase reactors over Mn- and Zr-modified Co/SiO2 catalysts

Fischer–Tropsch (F–T) synthesis was carried out in a gas-flowed slurry-phase reaction system over Mn- and Zr-modified Co/SiO₂ catalysts. A 0.5 L stirred tank slurry reactor (STSR) was used for catalyst screening and a 12.5 L slurry bubble column reactor (SBCR) was used for trial pilot operation. While using the 0.5 L reactor for catalyst screening, Co supported on the SiO₂ with an average pore size of 10 nm showed a high catalytic performance for the F–T synthesis due to the suitable Co particle size in the catalyst. Zr promoter improved the activity and Mn promoter improved the stability of Co/SiO₂ catalyst for the F–T synthesis. H₂-TPR profiles indicated that Zr and Mn promoters improved the reduction degree of Co₃O₄ particles (on SiO₂ surface) to Co⁰ active species in H₂ flow at low temperature. While using the 12.5 L reactor for trial pilot operation over Mn–Zr–Co/SiO₂ catalyst, the space-time yield (STY) of C₅₊ hydrocarbons (liquid fuel) showed almost the same values when various solvents (n-C₁₆H₃₄, n-C₁₄H₃₀, diesel from petrol station, F–T crude oil) were used. Diesel and F–T crude oil are suitable for using in a large-scaled F–T synthesis plant owing to the low prices. Mn–Zr–Co/SiO₂ catalyst achieved a STY of C₅₊ hydrocarbons larger than 1000 g-C₅₊ kg-cat^? 1 h^? 1 in the 12.5 L reactor. The production capacity of liquid fuel from the 12.5 L reactor reached to 15.6 L per day (assumed for 24 h continuous operation). The stirring was very important for the F–T synthesis both reaction in the 0.5 L reactor and reaction in the 12.5 L reactor. The shape of slurry reactor also influenced the CO conversion for the F–T synthesis: reaction in the 12.5 L SBCR gave a higher CO conversion than that of reaction in the 0.5 L STSR (at the same W/F value under the same stirring speed) because the slender column reactor (SBCR) extended the residue time of reaction gas in the slurry-phase containing catalyst.     

Synthesis of l-theanine using enzyme/mesoporous silica conjugates under high pH conditions

We present a new enzymatic process for synthesis of l-theanine using glutaminase combined with immobilization technique on a mesoporous silica (MPS). The MPS was firstly attempted to modify with zirconia in order to enhance the durability against the reaction under high pH conditions. The glutaminase on the MPS successfully catalyzed the reaction for the synthesis of l-theanine. The glutaminase/MPS conjugate was subsequently recovered and employed for the reaction again. The conjugate showed the corresponding activity to the first synthesis. This indicates that the conjugate functions as a catalyst for synthesis of l-theanine, having the operational stability sufficient for reuse.     

A new Drosophila ultraviolet light-damaged DNA recognition endonuclease that selectively nicks a (6-4) photoproduct site

Airborne substances can stimulate both the olfactory and the trigeminal nerve in the nose, giving rise to odor and pungent (irritant) sensations, respectively. Nose, eye, and throat irritation constitute common adverse effects in indoor environments. We measured odor and nasal pungency thresholds for homologous aliphatic aldehydes (butanal through octanal) and carboxylic acids (formic, acetic, butanoic, hexanoic, and octanoic). Nasal pungency was measured in subjects lacking olfaction (i.e., anosmics) to avoid odor biases. Similar to other homologous series, odor and pungency thresholds declined (i.e., sensory potency increased) with increasing carbon chain length. A previously derived quantitative structure-activity relationship (QSAR) based on solvation energies predicted all nasal pungency thresholds, except for acetic acid, implying that a key step in the mechanism for threshold pungency involves transfer of the inhaled substance from the vapor phase to the receptive biological phase. In contrast, acetic acid - with a pungency threshold lower than predicted - is likely to produce threshold pungency through direct chemical reaction with the mucosa. Both in the series studied here and in those studied previously, we reach a member at longer chain-lengths beyond which pungency fades. The evidence suggests a biological cut-off, presumably based upon molecular size, across the various series.     

A study of multiple biomarkers in coke oven workers--a cross-sectional study in China

We conducted a cross-sectional molecular epidemiological study of coke oven workers exposed to the established carcinogen polycyclic aromatic hydrocarbons (PAHs) to evaluate the relationships between both traditional 'exposure markers' and a series of biomarkers, including urinary 1-hydroxypyrene as a marker of internal dose, leukocyte aromatic DNA adducts as markers of biologically effective dose, serum p53 protein as a response marker and genetic polymorphisms of cytochrome P4501A1 and glutathione S-transferase MI as susceptibility markers. Twenty-five male subjects each were randomly selected from the top, middle and bottom work areas of the oven, and the control plant. They were matched for age and smoking status. The mean levels of PAH exposure, monitored by stationary and personal samplers, and of worker urinary 1-hydroxypyrene differed significantly between the top, middle and bottom of the oven and control work areas. The highest stationary and personal PAH concentrations and 1-hydroxypyrene levels were demonstrated at the top work area. Good correlations were found between the stationary PAH levels, personal PAH levels and urinary 1-hydroxypyrene levels. No positive correlations were demonstrated between aromatic DNA adduct levels and current or cumulative PAH exposure dose. In the presence of genetic polymorphisms of cytochrome P4501A1, a positive correlation was demonstrated between aromatic DNA adducts and urinary 1-hydroxypyrene levels. There was also a significant correlation between serum p53 protein levels and the cumulated benzo[a]pyrene exposure dose. Although these biomarkers have certain limitations, they are applicable to cancer epidemiology, and may contribute to our understanding of the mechanisms of carcinogenesis.     

Hyperpolarization-activated Cl- current elicited by pituitary adenylate cyclase activating polypeptide in Xenopus oocytes

We examined the electrophysiological effect of pituitary adenylate cyclase activating polypeptide (PACAP) in isolated Xenopus laevis oocytes in vitro. In conventional two-electrode voltage clamp experiments, PACAP (1-10 microM) activated an inward rectifier current at membrane potentials more negative than -60 mV without causing any significant change in currents at potentials more positive than -60 mV both in the follicle-enclosed oocyte and in the defolliculated oocyte. This current reversed at -22.5 mV, close to the theoretical value of Cl- equilibrium potential and the reversal potential of this current was shifted positively by reducing [Cl-]o. This current was blocked by Cl- channel blocker SITS and Ba2+. Furthermore, VIP and adenylate cyclase activator forskolin did not elicit the currents. In conclusion, PACAP elicited the hyperpolarization-activated Cl- current in Xenopus laevis oocytes. This current may modulate the membrane potential of the oocyte, thereby affecting the oocyte physiology.     

Analysis of a 36.2 kb DNA sequence including the right telomere of chromosome VI from Saccharomyces cerevisiae

The nucleotide sequence of a 36.2-kb distal region containing the right telomere of chromosome VI was determined. Both strands of DNA cloned into cosmid clone 9965 and plasmid clone pEL174P2 were sequenced with an average redundancy of 7.9 per base pair, by both dye primer and dye terminator cycle sequencing methods. The G+C content of the sequence was found to be 37.9%. Eighteen open reading frames (ORFs) longer than 100 amino acids were detected. Four of these ORFs (9965orfR017, 9965orfF016, 9965orfR009 and 9965orfF003) were found to encode previously identified genes (YMR31, PRE4, NIN1 and HXK1, respectively). Six ORFs (9965orfR013, 9965orfF018, 9965orfF006, 9965orfR014, 9965orfF013 and 9965orfR020) were found to be homologous to hypothetical 121.4-kDa protein in the BCK 5' region, Bacillus subtilis DnaJ protein, hypothetical Trp-Asp repeats containing protein in DBP3-MRPL27, putative mitochondrial carrier YBR291C protein, Salmonella typhimurium nicotinate-nucleotide pyrophosphorylase, and Escherichia coli cystathionine beta-lyase, respectively. The putative proteins encoded by 9965orfF018, 9965orfR014 and 9965orfR020 were found to be, respectively, a new member of the family of DnaJ-like proteins, the mitochondrial carrier protein and cystathionine lyase.     

Antenna-gain measurement of handheld terminals at 900 MHz

This paper presents antenna-gain measurements of handheld terminals by the random-field measurement (RFM) method. We have measured the relative antenna gain for different-sized terminal boxes in indoor and outdoor environments to show a gain decrease caused by the box size. The measured results are explained by calculating the average gain of the horizontal radiation pattern. To find the effect by a different human carrier, we also measured the antenna gain for several parameters, such as weight, height, head parameters, and the antenna protruding length from the head. We present a correlation factor of the antenna-gain deviation due to different human carriers