Showing papers by "Yonsei University published in 1998"
TL;DR: In this paper, the authors model the firm's decision to invest in liquid assets when external financing is costly, and the optimal amount of liquidity is determined by a tradeoff between the low return earned on liquid assets and the benefit of minimizing the need for costly external financing.
Abstract: We model the firm's decision to invest in liquid assets when external financing is costly. The optimal amount of liquidity is determined by a tradeoff between the low return earned on liquid assets and the benefit of minimizing the need for costly external financing. The model predicts that the optimal investment in liquidity is increasing in the cost of external financing, the variance of future cash flows, and the return on future investment opportunities, while it is decreasing in the return differential between the firm's physical assets and liquid assets. Empirical tests on a large panel of U.S. industrial firms support the model's predictions.
1,236 citations
TL;DR: An industry case study is presented to demonstrate that the prices of goods traded through electronic marketplaces can actually be higher than those of products sold in traditional markets.
Abstract: The efficiency of electronic means for commerce is sometimes countered by increased product cost, as demonstrated in this case involving an auction system for used cars in Japan. E lectronic marketplaces have become increasingly popular alternatives to traditional forms of commerce [8, 9]. This increase in popularity has led many to predict that one effect will be to lower the market price of goods. This reduced price hypothesis was proposed by Bakos in his seminal article on electronic marketplaces [2]. Buyers in market-inter-mediated transactions have to bear search costs to obtain information about the prices and product offerings of sellers. High search costs of buyers enable sellers to maintain prices substantially above their marginal costs and result in alloca-tional inefficiencies in market transactions. Electronic market systems can reduce the search costs that buyers must incur to acquire information about seller prices and product offerings, thus enabling buyers to locate suppliers that better match their needs. The lowered search costs allow buyers to look at more product offerings and make it difficult for sellers to sustain high prices. The reduced price hypothesis predicts that buyers will enjoy lower product prices as a result of the increased competition among sellers in electronic marketplaces. An industry case study is presented in this article to demonstrate that the prices of goods traded through electronic marketplaces can actually be higher than those of products sold in traditional markets. AUCNET is an electronic marketplace introduced to reduce search costs of buyers for used-car transactions in Japan. The average contract price of secondhand cars sold through AUCNET is much higher than that of traditional, non-electronic markets. The industry case study suggests that the analysis of electronic market impacts on product prices should take into account economic factors beyond the buyers' search costs. This article investigates why the product prices in AUCNET are higher than those of traditional markets by examining other economic variables than the buyer's search costs.
491 citations
TL;DR: Results suggest that surface modification with PEG1k-SO3, PEG3.4k-heparin seems to be effective for prevention of bacterial adhesion and subsequent infection.
456 citations
TL;DR: The results indicate that it is possible to manipulate the visual design factors of the customer interface in order to induce a target emotion, such as trustworthiness, in customers using electronic commerce systems.
429 citations
TL;DR: In this article, the authors report the findings from a cross-cultural study that attempts to show whether Hall's description of the characteristics of high and low-context cultures can indeed be empirically confirmed.
Abstract: The potential usefulness of Hall's concept of high- versus low-context cultures to international marketing has been discussed widely. However, implications of this concept in marketing have largely been discussed descriptively and little attempt has been made to empirically compare various cultures in a real setting. In this article the authors report the findings from a cross-cultural study that attempts to show whether Hall's description of the characteristics of high- and low-context cultures can indeed be empirically confirmed. With the use of a survey consisting of 16 items, subjects from three different countries—China, Korea, and the U.S.—representing both high- and low-context cultures, are studied. Overall, the results show that the three cultures differ in a way that is consistent with Hall's conceptualization. Specifically, the Chinese and Korean subjects are shown to exhibit tendencies that are consistent with Hall's description of high-context cultures, and the American subjects are shown to exhibit tendencies that are consistent with low-context cultures. For example, the subjects from China and Korea are found to be more socially oriented, to be more confrontation-avoiding, and to have more trouble dealing with new situations. The article concludes by pointing to a further need for efforts in developing measurement scales for the concept. © 1998 John Wiley & Sons, Inc.
390 citations
TL;DR: In this article, the effect of Nafion loading on the electrode polarization characteristics of a conventional proton exchange membrane (PEM) fuel cell electrode has been investigated in terms of both H 2/O2 and H2/air performance.
380 citations
TL;DR: The PCR assay for the detection of the repeating sequences combined with PCR amplification of the nonrepeating sequences of either the toxin A or the toxin B gene is indicated to be useful for differentiating toxin A−, toxin B+ strains from toxin A+.
Abstract: Toxigenic strains of Clostridium difficile have been reported to produce both toxins A and B nearly always, and nontoxigenic strains have been reported to produce neither of these toxins. Recent studies indicate that it is not always true. We established a PCR assay to differentiate toxin A-negative, toxin B-positive (toxin A-, toxin B+) strains from both toxin-positive (toxin A+, toxin B+) strains and both toxin-negative (toxin A-, toxin B-) strains as an alternative to cell culture assay and enzyme-linked immunosorbent assay (ELISA). By using the PCR primer set NK11 and NK9 derived from the repeating sequences of the toxin A gene, a shorter segment (ca. 700 bp) was amplified from toxin A-, toxin B+ strains compared to the size of the segment amplified from toxin A+, toxin B+ strains (ca. 1,200 bp), and no product was amplified from toxin A-, toxin B-strains. We examined a total of 421 C. difficile isolates by PCR. Of these, 48 strains showed a shorter segment by the PCR, were negative by ELISAs for the detection of toxin A, and were positive by cell culture assay. Although the cytotoxin produced by the toxin A-, toxin B+ strains was neutralized by anti-toxin B serum, the appearance of the cytotoxic effects on Vero cell monolayers was distinguishable from that of toxin A+, toxin B+ strains. By immunoblotting, the 44 toxin A-, toxin B+ strains were typed to serogroup F and the remaining four strains were serogroup X. Pulsed-field gel electrophoresis separated the 48 strains into 19 types. The PCR assay for the detection of the repeating sequences combined with PCR amplification of the nonrepeating sequences of either the toxin A or the toxin B gene is indicated to be useful for differentiating toxin A-, toxin B+ strains from toxin A+, toxin B+ and toxin A-, toxin B- strains and will contribute to elucidation of the precise role of toxin A-, toxin B+ strains in intestinal diseases.
369 citations
TL;DR: The results strongly suggest that defects in the DHCR7 gene cause the Smith-Lemli-Opitz syndrome, where missense mutations reduced heterologous protein expression by >90%.
Abstract: The Smith–Lemli–Opitz syndrome (SLOS) is an inborn disorder of sterol metabolism with characteristic congenital malformations and dysmorphias. All patients suffer from mental retardation. Here we identify the SLOS gene as a Δ7-sterol reductase (DHCR7, EC 1.3.1.21) required for the de novo biosynthesis of cholesterol. The human and murine genes were characterized and assigned to syntenic regions on chromosomes 11q13 and 7F5 by fluorescense in situ hybridization. Among the mutations found in patients with the SLOS, are missense (P51S, T93M, L99P, L157P, A247V, V326L, R352W, C380S, R404C, and G410S), nonsense (W151X), and splice site (IVS8–1G>C) mutations as well as an out of frame deletion (720–735 del). The missense mutations L99P, V326L, R352W, R404C, and G410S reduced heterologous protein expression by >90%. Our results strongly suggest that defects in the DHCR7 gene cause the SLOS.
355 citations
TL;DR: In this article, a passive smart-healing cementitious composite has been demonstrated, in the laboratory, to be feasible, to demonstrate the basic elements of this smart material include the sensors and actuators in the form of controlled microcracks and hollow glass fibers carrying air-curing chemicals.
Abstract: The basic concept of a passive smart-healing cementitious composite has been demonstrated, in the laboratory, to be feasible. The basic elements of this smart material include the sensors and actuators in the form of controlled microcracks and hollow glass fibers carrying air-curing chemicals. Controlled microcracking is offered by a strain-hardening engineered cementitious composite developed previously. The mechanisms of sensing and actuation are revealed through in situ environmental scanning electron microscopy observations. The self-healing effectiveness is confirmed by measurement of the elastic modulus of the composite. The elastic modulus is found to regain its original value in a repeat loading subsequent to damage in a first load cycle.
347 citations
TL;DR: A complete survey of CMOS multipliers can be found in this article, where a unified generation of multipliers architectures and the most recommended MOS multiplier structure are presented. But, despite the large number of papers proposing new CMOS multiplier structures, they can be roughly grouped into a few categories: high performance bipolar junction transistor multipliers have been available for some time, the implementation is still a challenging subject especially for lowvoltage and low power circuit design.
Abstract: Real time analog multiplication of two signals is one of the most important operations in analog signal processing. The multiplier is used not only as a computational building block but also as a programming element in systems such as filters, neural networks, and as mixers and modulators in a communication system. Although high performance bipolar junction transistor multipliers have been available for some time, the CMOS multiplier implementation is still a challenging subject especially for low-voltage and low-power circuit design. Despite the large number of papers proposing new CMOS multiplier structures, they can be roughly grouped into a few categories. This tutorial provides a complete survey of CMOS multipliers, presents a unified generation of multiplier architectures, and proposes the most recommended MOS multiplier structure. This tutorial could serve as a starting reference point (and metric) for comparison of new CMOS multiplier circuit configurations. An illustrative CMOS chip prototype verifying theoretical results is presented.
327 citations
TL;DR: Findings showed that distributions of sinusoidal capillarization and unpaired arteries in dysplastic nodules are intermediate between those in cirrhotic nodules and HCC, supporting dysplastics nodules as premalignant lesions, and unpaired arteries are histologically useful for distinguishing dyspl Plastic nodules from large cirrhosis nodules.
Abstract: The blood supply of hepatocellular carcinoma (HCC) is primarily arterial. Recent studies reported differences of vascular, especially arterial, supply among low- and high-grade dysplastic nodules and HCC. We assessed arterialization using monoclonal antibody specific for smooth muscle actin as well as simultaneous changes in sinusoidal capillarization in cirrhotic nodules, dysplastic nodules, and HCC. We immunohistochemically stained 56 cirrhotic nodules, 20 low-grade dysplastic nodules, 27 high-grade dysplastic nodules, and 20 HCCs for alpha smooth muscle actin (to identify unpaired arteries (i.e., arteries not accompanied by bile ducts) and CD34 (indicating sinusoidal capillarization). Distribution and number of unpaired arteries and distribution of sinusoidal capillarization were graded semiquantitatively. Unpaired arteries were rare in cirrhotic nodules, significantly more common in dysplastic nodules of both types (p < 0.00001), and most common in HCC. Sinusoidal capillarization was least common in cirrhotic nodules, significantly more common in dysplastic nodules (p < 0.0035), and most common in HCC. No topographic relationship between unpaired arteries and sinusoidal capillarization was identified. These findings showed that (1) distributions of sinusoidal capillarization and unpaired arteries in dysplastic nodules are intermediate between those in cirrhotic nodules and HCC, supporting dysplastic nodules as premalignant lesions; (2) unpaired arteries are histologically useful for distinguishing dysplastic nodules from large cirrhotic nodules; and (3) areas of sinusoidal capillarization within dysplastic nodules are unrelated to location of arterialization.
TL;DR: Topical application of [6]-gingerol onto shaven backs of female ICR mice prior to each topical dose of 12-O-tetradecanoylphorbol-13-acetate (TPA) significantly inhibited 7,12-dimethylbenz[a]anthracene-induced skin papillomagenesis and suppressed TPA-induced epidermal ornithine decarboxylase activity and inflammation.
Journal Article•
TL;DR: Serum levels ofIL-10 are elevated in SLE patients and increased IL-10 correlates well with SLE disease activity, and changes in serum IL- 10 levels also correlated with the changes in the SLEDAI score during the patients' disease course.
Abstract: Objective To determine serum interleukin-10 (IL-10) levels in systemic lupus erythematosus (SLE) patients and to assess their relationship with disease activity. Methods Forty-one SLE patients and 35 controls were studied. Paired serum samples were collected from all SLE patients at the time of their presentation with active disease and at 4 weeks after the institution of treatment. IL-10 levels were determined in the sera and were compared with disease activity, measured using the SLE Disease Activity Index (SLEDAI) and laboratory parameters such as the circulating immune complexes (CIC), C3, C4, anti-DNA antibody, IgG, IgM, and IgA. Results The IL-10 levels in SLE patients were significantly higher than those of controls (mean ± SE, 29.2 ± 6.8 vs 3.5 ± 0.6 pg/ml, p < 0.01). Elevated IL-10 levels correlated well with the SLEDAI in SLE patients (r = 0.46, p < 0.01), but did not correlate with other laboratory activity indices. The changes in serum IL-10 levels also correlated with the changes in the SLEDAI score during the patients' disease course (r = 0.51, p < 0.01). Conclusion Serum levels of IL-10 are elevated in SLE patients and increased IL-10 correlates well with SLE disease activity.
TL;DR: The results suggest that the behavioral pattern changes observed in the irritated nerve root model are caused in part by a high level of phospholipase A2 activity initiated by inflammation, and that the mechanism of action of epidural steroid injection in this model is inhibition of phosphate A1 activity.
Abstract: Study design The possible role of phospholipase A2 in an animal model for lumbar radiculopathy and mechanisms of epidural steroid injections were studied. Objectives To clarify the pathophysiologic mechanism of the recently proved animal model for lumbar radiculopathy and to characterize further the mechanisms of action of steroids. Summary of background data There have been several reported animal models of peripheral neuropathy. Recently an animal model that shows reliable behavioral and neurochemical changes was proposed, and epidural steroid injections in this model were effective in the reduction of thermal hyperalgesia and allodynia. Method In a behavioral study, 24 rats were divided into 4 groups: Group I, loose ligature of the left L4 and L5 nerve roots with 4-0 chromic gut sutures and an epidural injection of 0.1 mL of saline at 3 days after surgery; Group II, same as Group I but with an epidural injection of 0.1 mL of betamethasone on the day before the operation; Group II, same as Group II except injection at 1 day after surgery; Group IV, same as Group II except injection at 3 days after surgery. To test the phospholipase A2 activity in the nerve roots and dorsal root ganglia after the operation, eight rats were killed at given intervals. Analysis of variance techniques were used to test behavioral pattern changes and phospholipase A2 activity across time in each group. Results Thermal hyperalgesia reached its maximal point at 3 weeks after surgery in Group I, but in steroid injection groups, the recovery from hyperalgesia was faster than in Group I. However, there was no significant difference in recovery time among steroid injection groups. The level of phospholipase A2 activity was at its maximum at 1 week after surgery in Groups I and IV. It showed a steady reduction in the steroid group, whereas it remained relatively high and dropped rapidly after 3 weeks in the saline-treated group, and returned to the level of a normal nerve root at 6 weeks after surgery. Conclusion These results suggest that the behavioral pattern changes observed in the irritated nerve root model are caused in part by a high level of phospholipase A2 activity initiated by inflammation, and that the mechanism of action of epidural steroid injection in this model is inhibition of phospholipase A2 activity.
TL;DR: In this article, the Δ7-sterol reductase (EC 1.3.1) was found to be defective in the Smith-Lemli-Opitz syndrome, a frequent inborn disorder of sterol metabolism.
Abstract: Inhibitors of the last steps of cholesterol biosynthesis such as AY9944 and BM15766 severely impair brain development. Their molecular target is the Δ7-sterol reductase (EC 1.3.1.21), suspected to be defective in the Smith–Lemli–Opitz syndrome, a frequent inborn disorder of sterol metabolism. Molecular cloning of the cDNA revealed that the human enzyme is a membrane-bound protein with a predicted molecular mass of 55 kDa and six to nine putative transmembrane segments. The protein is structurally related to plant and yeast sterol reductases. In adults the ubiquitously transcribed mRNA is most abundant in adrenal gland, liver, testis, and brain. The Δ7-sterol reductase is the ultimate enzyme of cholesterol biosynthesis in vertebrates and is absent from yeast. Microsomes from Saccharomyces cerevisiae strains heterologously expressing the human cDNA remove the C7–8 double bond in 7-dehydrocholesterol. The conversion to cholesterol depends on NADPH and is potently inhibited by AY9944 (IC50 0.013 μM), BM15766 (IC50 1.2 μM), and triparanol (IC50 14 μM). Our work paves the way to clarify whether a defect in the Δ7-sterol reductase gene underlies the Smith–Lemli–Opitz syndrome.
TL;DR: In this article, two relaxor materials, Pb(Mg 1/3Nb2/3)O3 and Pb (Fe 1/2Nb1/2), were successfully synthesized at a low temperature in a very short time by the MSS method.
Abstract: The molten salt synthesis (MSS) of lead-based relaxors which have a perovskite structure, A(BIBII)O3 where BI is Mg2+, Fe3+, Zn2+, Ni2+ or Co2+, and BII is Nb5+, has been reviewed with regard to the formation of the perovskites, phase stability and morphology characteristics. Two relaxor materials, Pb(Mg1/3Nb2/3)O3 and Pb(Fe1/2Nb1/2)O3 were found to be successfully synthesized at a low temperature in a very short time by the MSS method. Using the example of Pb(Mg1/3Nb2/3)O3, the phase stability has been discussed on the basis of thermal and chemical analyses. The influences of the processing parameters, such as temperature, time, type and amount of salt, and non-stoichiometry, on the formation and the powder characteristics of the perovskite phase were investigated with possible explanations for the observed differences which were induced by changing the parameters. Finally, densification behaviour and dielectric properties resulting from the MSS powder were examined and compared to those of powders obtained by using the conventional mixed oxides (CMO) method. © 1998 Kluwer Academic Publishers
TL;DR: In this paper, the kinetics and mechanism of the sonolytic degradation of methyl tert-butyl ether (MTBE) have been investigated at an ultrasonic frequency of 205 kHz and power of 200 W L-1.
Abstract: The kinetics and mechanism of the sonolytic degradation of methyl tert-butyl ether (MTBE) have been investigated at an ultrasonic frequency of 205 kHz and power of 200 W L-1. The observed first-order degradation rate constant for the loss of MTBE increased from 4.1 × 10-4 s-1 to 8.5 × 10-4 s-1 as the concentration of MTBE decreased from 1.0 to 0.01 mM. In the presence of O3, the sonolytic rate of destruction of MTBE was accelerated substantially. The rate of MTBE sonolysis with ozone was enhanced by a factor of 1.5−3.9 depending on the initial concentration of MTBE. tert-Butyl formate, tert-butyl alcohol, methyl acetate, and acetone were found to be the primary intermediates and byproducts of the degradation reaction with yields of 8, 5, 3, and 12%, respectively. A reaction mechanism involving three parallel pathways that include the direct pyrolytic decomposition of MTBE, the direct reaction of MTBE with ozone, and the reaction of MTBE with hydroxyl radical is proposed.
TL;DR: In this paper, microwave dielectric properties and far infrared reflectivity spectra were investigated in the (Zr0.8Sn 0.2)TiO4 ceramics with 1 mol% Sb2O5, Sb 2O3 and Nd2O3, respectively.
Abstract: Microwave dielectric properties and far infrared reflectivity spectra were investigated in the (Zr0.8Sn0.2)TiO4 ceramics with 1 mol% Sb2O5, Sb2O3 and Nd2O3, respectively. Dielectric constant was not significantly changed, while the unloaded Q value was affected with additives. The unloaded Q of the pure (Zr0.8Sn0.2)TiO4 specimens was higher than that of the specimens with Sb2O3 and/or Nd2O3, but lower than that of the specimens with Sb2O5. The high unloaded Q value of 6600 at 7 GHz was obtained for the specimens with 1 mol% Sb2O5 due to elimination of oxygen vacancies. The effects of additives on the intrinsic microwave losses of the specimens were investigated by the infrared reflectivity spectra from 50 to 4000 cm-1, which were evaluated using the Kramers-Kronig analysis and classical oscillator model. The relative tendency of microwave dielectric properties calculated from the reflectivity data was in good agreement with the results by the Hakki and Coleman's method.
01 Dec 1998
TL;DR: An electromyographic (EMG) pattern recognition method to identify motion commands for the control of a prosthetic arm by evidence accumulation based on artificial intelligence with multiple parameters is presented.
Abstract: This paper presents an electromyographic (EMG) pattern recognition method to identify motion commands for the control of a prosthetic arm by evidence accumulation based on artificial intelligence with multiple parameters. The integral absolute value, variance, autoregressive (AR) model coefficients, linear cepstrum coefficients, and adaptive cepstrum vector are extracted as feature parameters from several time segments of EMG signals. Pattern recognition is carried out through the evidence accumulation procedure using the distances measured with reference parameters. A fuzzy mapping function is designed to transform the distances for the application of the evidence accumulation method. Results are presented to support the feasibility of the suggested approach for EMG pattern recognition.
TL;DR: Serum CRP at enrollment is an independent predictor of 2-year patient survival in CAPD patients, and it was found that cardiovascular disease, diabetes mellitus, and high hematocrit were independent predictors of mortality.
Abstract: ObjectiveTo evaluate the predictive value of a single baseline serum C-reactive protein (sCRP) as a marker of mortality in continuous ambulatory peritoneal dialysis (CAPD) patients.DesignA review o...
TL;DR: MR artifacts can be minimized by optimally positioning in the magnet subjects with metallic implants and by choosing fast spin-echo sequences with an anterior-posterior frequency-encoding direction and the smallest voxel size.
Abstract: The purpose of this study was to investigate the effect of metallic implant positioning on MR imaging artifacts, to determine the optimal imaging conditions for minimizing artifacts, and to show the usefulness of artifact-minimizing methods in imaging of the knee.Using MR images of experimental phantoms (titanium alloy and stainless steel screws), we compared the magnitude of metal-induced artifacts for various pulse sequences, different imaging parameters for the fast spin-echo sequence, and different imaging parameters for several incremental angles between the long axis of the screw and the direction of the main magnetic field. In clinical MR imaging of knees with metallic implants (n = 19), we assessed geometric distortion of anatomic structures to compare the influence of different pulse sequences (n = 19), frequency-encoding directions (n = 7), and knee positions (n = 15).Titanium alloy screws consistently produced smaller artifacts than did stainless steel screws. In experimental MR studies, artifa...
TL;DR: Living donors including related, unrelated, and exchange donors should be considered as potential donors for kidney transplantation to relieve the pressure on donor organ shortage in countries where brain death has not been socially or legally accepted.
Abstract: The donor organ shortage has been one of the major barriers to kidney transplantation in Korea, even though there has been a small but steady flow of cadaveric kidney donations for the last decade. To expand the donor pool in kidney transplantation, we have developed the exchange donor program at our institution and in Korea. The donor exchange program was first started for end-stage renal disease patients who had willing but incompatible related donors due to positive lymphocyte cross-match. The kidney transplantations were performed using exchanged kidneys between two families with successful results. Since this success, we have expanded the donor pool by accepting close relatives, spouses, friends of recipients, and willing voluntary donors as candidates for exchange donors with careful donor screening procedures. It helps relieve stress on donor supply. Particularly in those countries where brain death has not been socially or legally accepted, living donors including related, unrelated, and exchange donors should be considered as potential donors for kidney transplantation to relieve the pressure on donor organ shortage.
TL;DR: In situ hybridization on tissue embedded in plastic proved to be a useful method to study mixed bacterial infections since it combines excellent histological conservation of tissue with identification of bacterial species by simultaneous use of probes labelled with different fluorescent dyes.
Abstract: Fluorescence in situ hybridization (FISH) was performed on sections of plastic-embedded tissue using 16S rRNA-directed oligonucleotide probes to visualize uncultured treponemes in skin biopsies of cows with digital dermatitis. Plastic as embedding material allowed sectioning of hard and soft tissue with a defined thickness, avoiding the risk of dragging bacteria into the tissue while sectioning. Furthermore, it provided a good signal-to-noise ratio. Using this method the spatial distribution of three different bacterial phylotypes was visualized simultaneously within the tissue. Whereas debris covering the ulcers contained a mixture of different micro-organisms, a layering of certain treponemal phylotypes was observed deeper in the epidermis. Confocal laser scanning microscopy and subsequent three-dimensional reconstruction of series of optical sections confirmed that the treponemes migrated intercellularly around the cells, most of them directed towards the dermis. In situ hybridization on tissue embedded in plastic proved to be a useful method to study mixed bacterial infections since it combines excellent histological conservation of tissue with identification of bacterial species by simultaneous use of probes labelled with different fluorescent dyes. This technique may have implications for in situ detection, identification and localization of microorganisms in veterinary as well as in human medicine.
TL;DR: In this article, the compositional dependence of the photoluminescence of ZnGa2O4 has been studied to identify the optical centers, and the new self activated optical centers are due to the tetrahedral GaO groups in the spinel lattice.
TL;DR: In this paper, microstructural observation and thermal analysis of Al-21 wt % Si alloys with different rare earth metals were performed to examine the effect of rare earth metal on the refinement of primary silicon phase.
Abstract: Microstructural observation and thermal analysis of Al-21 wt % Si alloys with different rare earth metals were performed to examine the effect of rare earth metal on the refinement of primary silicon phase. Simultaneous refinement of both primary and eutectic silicon morphology is achieved with the addition of rare earth and its effect increases with the amount of rare earth addition and cooling rate. Depression of 12–17 °C in primary reaction temperature and 2–7 °C in eutectic temperature is measured with the addition of rare earth. Rare earth bearing compounds were not believed to act as a nucleation agent of primary silicon phase. Some rare earth bearing compounds determined to AlCe were around primary silicon in the matrix. The twin density of eutectic silicon remains same regardless of the addition of rare earth. The refinement of silicon in rare earth treated hypereutectic Al-Si alloys is supposed to be due to the suppression of the nucleation temperature of silicon phase.
TL;DR: The first nucleic sequence report on phytase from a bacterial strain is reported, which would decrease the addition of phosphorus to feedstuffs for monogastric animals and thus reduce environmental pollution.
Abstract: Phytase hydrolyzes phytate to release inorganic phosphate, which would decrease the addition of phosphorus to feedstuffs for monogastric animals and thus reduce environmental pollution. The gene encoding phytase from Bacillus sp. DS11 was cloned in Escherichia coli and its sequence determined. A 560-bp DNA fragment was used as a probe to screen the genomic library. It was obtained through PCR of Bacillus sp. DS11 chromosomal DNA and two oligonucleotide primers based on N-terminal amino acid sequences of the purified protein and the cyanogen bromide-cleaved 21-kDa fragment. The phy cloned was encoded by a 2.2-kb fragment. This gene comprises 1152 nucleotides and encodes a polypeptide of 383 amino acids with a deduced molecular mass of 41 808 Da. Phytase was produced to 20% content of total soluble proteins in E. coli BL21 (DE3) using the pET22b(+) vector with the inducible T7 promoter. This is the first nucleic sequence report on phytase from a bacterial strain.
TL;DR: In this article, the adsorption dynamics of a layered bed packed with activated carbon and zeolite 5A were studied experimentally and theoretically through breakthrough experiments and two-bed pressure swing adsorment (PSA) processes by using coke oven gas.
Abstract: The adsorption dynamics of a layered bed packed with activated carbon and zeolite 5A were studied experimentally and theoretically through breakthrough experiments and two-bed pressure swing adsorption (PSA) processes by using coke oven gas (56.4 vol.% H{sub 2}; 26.6 vol.% CH{sub 4}; 8.4 vol.% CO; 5.5 vol.% N{sub 2}; and 3.1 vol.% CO{sub 2}). The results of breakthrough curves of a layered bed showed an intermediate behavior of those of zeolite-5A bed and activated carbon bed, because each concentration front propagates with its own wavefront velocity in each layer by a different adsorption equilibrium. Since a fast and dispersed mass-transfer zone of CO in the zeolite layer of a layered bed leads to a long leading front of the N{sub 2} wavefront, controlling the leading wavefront of the N{sub 2} plays a very important role in obtaining a high-purity product and in determining the optimum carbon ratio of a PSA process for H{sub 2} recovery from coke oven gas. The layered bed PSA process was simulated in a simplified form of two single-adsorbent beds linked in series. The dynamic model incorporating mass, energy, and momentum balances agreed well with the experimental data. Concentration profiles inside the adsorption bed were alsomore » investigated.« less
TL;DR: A small region on chromosome 6 (band 6p21) containing only ∼30 Mbp DNA, and chromosomes 6 and 7, associate with the domain significantly more than other chromosomes, and is christened the Oct1/PTF/transcription (OPT) domain.
Abstract: PTF (PSE-binding transcription factor) activates transcription of snRNA and related genes. We investigated its distribution in HeLa nuclei by immunofluorescence, and found it spread throughout the nucleoplasm in small foci. In some cells, PTF is also concentrated in one, or very few, discrete regions (diameter approximately 1.3 micron) that appear during G1 phase and disappear in S phase. Oct1, a transcription factor that interacts with PTF, is also enriched in these domains; RNA polymerase II, TBP and Sp1 are also present. Each domain typically contains 2 or 3 transcription 'factories' where Br-UTP is incorporated into nascent transcripts. Accordingly, we have christened this region the Oct1/PTF/transcription (OPT) domain. It colocalizes with some, but not all, PIKA domains. It is distinct from other nuclear domains, including coiled bodies, gemini bodies, PML bodies and the perinucleolar compartment. A small region on chromosome 6 (band 6p21) containing only approximately 30 Mbp DNA, and chromosomes 6 and 7, associate with the domain significantly more than other chromosomes. The domains may act like nucleoli to bring particular genes on specific chromosomes together to a region where the appropriate transcription and processing factors are concentrated, thereby facilitating the expression of those genes.
TL;DR: In this article, the authors used SEM, DSC, AES, and XRD combined techniques in elucidating detailed interfacial phenomena in the SiC p /Al composite and showed that there exists a transition temperature at which a sudden increase in equilibrium Si contents required to prevent Al 4 C 3 formation occurs.
TL;DR: A new fuzzy modeling algorithm is proposed, which partitions the input space more effectively than conventional fuzzy modeling algorithms by taking into consideration the correlation among components of sample data.
Abstract: This paper presents an explanation of a fuzzy model considering the correlation among components of input data. Generally, fuzzy models have a capability of dividing an input space into several subspaces compared to a linear model. But hitherto suggested fuzzy modeling algorithms have not taken into consideration the correlation among components of sample data and have addressed them independently, which results in an ineffective partition of the input space. In order to solve this problem, this paper proposes a new fuzzy modeling algorithm, which partitions the input space more effectively than conventional fuzzy modeling algorithms by taking into consideration the correlation among components of sample data. As a way to use the correlation and divide the input space, the method of principal component is used. Finally, the results of the computer simulation are given to demonstrate the validity of this algorithm.