6,687 research outputs found

    The Key Successful Factors of Internet Business: The Study of Online Bookshop

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    Electronic commerce is viewed as a more and more important issue for the rapid growth of online commercial activities. The books, having the properties of numerous categories, low unit price, and the convenience of delivering, have become the major products on line. So the online bookshops are appropriate for study to find out the key successful factors of Internet business. We first conduct twice Delphi to confirm several factors that are important to success in Internet business and there are 32 factors to be chosen. We then calculate the relative weigh of each factor with the Analytic Hierarchy Process (AHP) and select 14 factors having the highest weight to be the key successful factors of Internet business. These 14 factors in order of weight include the ability of managing the business change, filling the Place with Entrepreneurs and growing with them, the ability of managing the customer relationship, targeting the right customers, the price can react to market quickly, building the knowledge management systems, excellent sever ice after payment, building distribution center to develop unbeatable logistics, the ability of managing the cost, offering Great Value, the ability of marketing by database, building the goodwill and brand image, getting the trust of virtual community and maintain it continually, and the ability of developing the technology

    Significance of CO2 donor on the production of succinic acid by Actinobacillus succinogenes ATCC 55618

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    <p>Abstract</p> <p>Background</p> <p>Succinic acid is a building-block chemical which could be used as the precursor of many industrial products. The dissolved CO<sub>2 </sub>concentration in the fermentation broth could strongly regulate the metabolic flux of carbon and the activity of phosphoenolpyruvate (PEP) carboxykinase, which are the important committed steps for the biosynthesis of succinic acid by <it>Actinobacillus succinogenes</it>. Previous reports showed that succinic acid production could be promoted by regulating the supply of CO<sub>2 </sub>donor in the fermentation broth. Therefore, the effects of dissolved CO<sub>2 </sub>concentration and MgCO<sub>3 </sub>on the fermentation process should be investigated. In this article, we studied the impacts of gaseous CO<sub>2 </sub>partial pressure, dissolved CO<sub>2 </sub>concentration, and the addition amount of MgCO<sub>3 </sub>on succinic acid production by <it>Actinobacillus succinogenes </it>ATCC 55618. We also demonstrated that gaseous CO<sub>2 </sub>could be removed when MgCO<sub>3 </sub>was fully supplied.</p> <p>Results</p> <p>An effective CO<sub>2 </sub>quantitative mathematical model was developed to calculate the dissolved CO<sub>2 </sub>concentration in the fermentation broth. The highest succinic acid production of 61.92 g/L was obtained at 159.22 mM dissolved CO<sub>2 </sub>concentration, which was supplied by 40 g/L MgCO<sub>3 </sub>at the CO<sub>2 </sub>partial pressure of 101.33 kPa. When MgCO<sub>3 </sub>was used as the only CO<sub>2 </sub>donor, a maximal succinic acid production of 56.1 g/L was obtained, which was just decreased by 7.03% compared with that obtained under the supply of gaseous CO<sub>2 </sub>and MgCO<sub>3</sub>.</p> <p>Conclusions</p> <p>Besides the high dissolved CO<sub>2 </sub>concentration, the excessive addition of MgCO<sub>3 </sub>was beneficial to promote the succinic acid synthesis. This was the first report investigating the replaceable of gaseous CO2 in the fermentation of succinic acid. The results obtained in this study may be useful for reducing the cost of succinic acid fermentation process.</p

    Superconductivity induced by doping Platinum in BaFe2As2

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    By substituting Fe with the 5d-transition metal Pt in BaFe2As2, we have successfully synthesized the superconductors BaFe2-xPtxAs2. The systematic evolution of the lattice constants indicates that the Fe ions were successfully replaced by Pt ions. By increasing the doping content of Pt, the antiferromagnetic order and structural transition of the parent phase is suppressed and superconductivity emerges at a doping level of about x = 0.02. At a doping level of x = 0.1, we get a maximum transition temperature Tc of about 25 K. The synchrotron powder x-ray diffraction shows that the resistivity anomaly is in good agreement with the structural transition. The superconducting transitions at different magnetic fields were also measured at the doping level of about x = 0.1, yielding a slope of -dHc2/dT = 5.4 T/K near Tc. A phase diagram was established for the Pt doped 122 system. Our results suggest that superconductivity can also be easily induced in the FeAs family by substituting the Fe with Pt, with almost the similar maximum transition temperatures as doping Ni, Co, Rh and Ir.Comment: 6 pages, 5 figure

    Submerzni uzgoj gljiva u bioreaktorima – izazovi, dostignuća i budućnost proizvodnje

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    Medicinal mushrooms have profound health-promoting benefits. Recently, a number of substances of mushroom origin have been isolated, identified and shown to have physiological activities, such as antitumor, immunomodulating, cardiovascular, antihypercholesterolemia, antibacterial, antiviral, antiparasitic, hepatoprotective, and antidiabetic activities. Currently, commercial products from medicinal mushrooms are mostly obtained through the field-cultivation of the fruiting body. However, in this case it is difficult to control the quality of the final product. Submerged fermentation of the mycelial form of mushroom-producing fungi has received much attention as a promising alternative for efficient production of the biomass of medicinal mushrooms and their active metabolites. However, in order for the production to be successful at industrial scale, various technical problems need to be solved, including characterization of the variations that occur during the submerged cultivation of mushrooms in bioreactors and their effects on growth and product formation. This review outlines the major factors that affect the submerged cultivation of mushrooms in bioreactors, including oxygen supply, shear and mixing, morphology and rheology, as well as two-stage cultivation strategies and high-cell-density cultivation strategies such as fed-batch fermentation.Medicinske gljive pozitivno djeluju na ljudsko zdravlje. U novije vrijeme izolirane su brojne tvari iz gljiva koje utječu na fiziološke procese i imaju antitumorski, imunomodulacijski i kardiovaskularni učinak, snizuju kolesterol, imaju antibakterijski, antivirusni, antiparazitski i hepatoprotektivni učinak i sprečavaju pojavu dijabetesa. Komercijalni proizvodi dobivaju se uzgojem medicinskih gljiva na polju. Međutim, tim se postupkom teško kontrolira kakvoća gotovog proizvoda. Submerzna fermentacija micelija gljiva moguća je alternativa za uspješnu proizvodnju biomase medicinskih gljiva i njihovih aktivnih metabolita. Međutim, da bi se postigla uspješna industrijska proizvodnja, treba riješiti razne tehničke probleme, između ostalog odrediti odstupanja pri submerznom uzgoju gljiva u bioreaktorima i njihov utjecaj na rast i formiranje gotovog proizvoda. U ovom se revijalnom prikazu razmatraju glavni faktori utjecaja na submerzni uzgoj gljiva u bioreaktorima, a to su opskrba kisikom, posmično naprezanje i miješanje, te morfologija i reologija, opisuje strategija uzgoja gljiva u dvije faze te proizvodnja stanica velike gustoće šaržnom fermentacijom

    An efficient human body contour extraction method for mobile apps.

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    With the increasing prevalence of powerful mobile technology, many applications involve human body measurements, such as online cloth shopping. Aiming at the application of non contact human body measurement and modeling system, this paper presents a new method for extracting human contours in complex background environment. Since the H component on the HSV color space is independent of the light changes, the hair and the lower garment can be divided. Therefore, a method of using the elliptical skin model on YCbCr color space is proposed to detect the skin color, then, automatically extract the skin samples to determine the threshold segmentation range. The combination of the two improves the skin color point recognition rate, gradually separating the body skin, clot and the hair by using these binary values of the linear fusion operation to get the final body contours. Our experiments demonstrates that this algorithm effectively reduces constraints on background environment when extracting contours

    Submerzni uzgoj gljiva u bioreaktorima – izazovi, dostignuća i budućnost proizvodnje

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    Medicinal mushrooms have profound health-promoting benefits. Recently, a number of substances of mushroom origin have been isolated, identified and shown to have physiological activities, such as antitumor, immunomodulating, cardiovascular, antihypercholesterolemia, antibacterial, antiviral, antiparasitic, hepatoprotective, and antidiabetic activities. Currently, commercial products from medicinal mushrooms are mostly obtained through the field-cultivation of the fruiting body. However, in this case it is difficult to control the quality of the final product. Submerged fermentation of the mycelial form of mushroom-producing fungi has received much attention as a promising alternative for efficient production of the biomass of medicinal mushrooms and their active metabolites. However, in order for the production to be successful at industrial scale, various technical problems need to be solved, including characterization of the variations that occur during the submerged cultivation of mushrooms in bioreactors and their effects on growth and product formation. This review outlines the major factors that affect the submerged cultivation of mushrooms in bioreactors, including oxygen supply, shear and mixing, morphology and rheology, as well as two-stage cultivation strategies and high-cell-density cultivation strategies such as fed-batch fermentation.Medicinske gljive pozitivno djeluju na ljudsko zdravlje. U novije vrijeme izolirane su brojne tvari iz gljiva koje utječu na fiziološke procese i imaju antitumorski, imunomodulacijski i kardiovaskularni učinak, snizuju kolesterol, imaju antibakterijski, antivirusni, antiparazitski i hepatoprotektivni učinak i sprečavaju pojavu dijabetesa. Komercijalni proizvodi dobivaju se uzgojem medicinskih gljiva na polju. Međutim, tim se postupkom teško kontrolira kakvoća gotovog proizvoda. Submerzna fermentacija micelija gljiva moguća je alternativa za uspješnu proizvodnju biomase medicinskih gljiva i njihovih aktivnih metabolita. Međutim, da bi se postigla uspješna industrijska proizvodnja, treba riješiti razne tehničke probleme, između ostalog odrediti odstupanja pri submerznom uzgoju gljiva u bioreaktorima i njihov utjecaj na rast i formiranje gotovog proizvoda. U ovom se revijalnom prikazu razmatraju glavni faktori utjecaja na submerzni uzgoj gljiva u bioreaktorima, a to su opskrba kisikom, posmično naprezanje i miješanje, te morfologija i reologija, opisuje strategija uzgoja gljiva u dvije faze te proizvodnja stanica velike gustoće šaržnom fermentacijom

    Human Mitochondrial tRNA Mutations in Maternally Inherited Deafness

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    AbstractMutations in mitochondrial tRNA genes have been shown to be associated with maternally inherited syndromic and non-syndromic deafness. Among those, mutations such as tRNALeu(UUR)3243A>G associated with syndromic deafness are often present in heteroplasmy, and the non-syndromic deafness-associated tRNA mutations including tRNASer(UCN)7445A>G are often in homoplasmy or in high levels of heteroplasmy. These tRNA mutations are the primary factors underlying the development of hearing loss. However, other tRNA mutations such as tRNAThr15927G>A and tRNASer(UCN)7444G>A are insufficient to produce a deafness phenotype, but always act in synergy with the primary mitochondrial DNA mutations, and can modulate their phenotypic manifestation. These tRNA mutations may alter the structure and function of the corresponding mitochondrial tRNAs and cause failures in tRNAs metabolism. Thereby, the impairment of mitochondrial protein synthesis and subsequent defects in respiration caused by these tRNA mutations, results in mitochondrial dysfunctions and eventually leads to the development of hearing loss. Here, we summarized the deafness-associated mitochondrial tRNA mutations and discussed the pathophysiology of these mitochondrial tRNA mutations, and we hope these data will provide a foundation for the early diagnosis, management, and treatment of maternally inherited deafness
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