• The neumann problem for second order hyperbolic equations in nonsmooth domainsThe neumann problem for second order hyperbolic equations in nonsmooth domains

    Abstract. In this paper, we study the Neumann problem for second order hyperbolic equations without initial data in nonsmooth domains. Our intension was to prove the existence of a generalized solution to this problem by applying the results of this problem to the initial data.

    pdf7 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 479 | Lượt tải: 0

  • In situ Raman and UV–vis spectroscopic studies of polypyrrole and poly(pyrrole-2,6-dimethyl--cyclodextrin)In situ Raman and UV–vis spectroscopic studies of polypyrrole and poly(pyrrole-2,6-dimethyl--cyclodextrin)

    Polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl--cyclodextrin) [P(Py--DMCD)] films prepared by potential cycling in aqueous acidic solutions on indium tin oxide (ITO)-coated glass and gold electrodes were studied by in situ UV–vis and Raman spectroscopy. Characteristic UV–vis and Raman bands were identified and their dependencies on the electrod...

    pdf6 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 447 | Lượt tải: 0

  • Theoretical investigation of the interaction between monohalogenated ethenes and hydrogen peroxideTheoretical investigation of the interaction between monohalogenated ethenes and hydrogen peroxide

    The complexes between monohalogenated ethenes CH2@CHX (X = F, Cl, Br) and hydrogen peroxide (HP) have been studied theoretically at the MP2/6-311++G(3df,2p) level. The calculations include the optimization of the geometries, the vibrational frequencies and IR intensities of the m(OH) and m(CH) vibrations along with a natural bond orbital (NBO) an...

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  • Genetic algorithms and application in examination schedulingGenetic algorithms and application in examination scheduling

    Abstract. Examination Scheduling is an optimization problem with constraints, a scheduling problem is one of the NP-hard problems, there is no algorithm that can solve them in polynomial time. Genetic algorithm is an algorithm for finding approximate optimal test of the global optimization problems. Application of genetic algorithms on the speci...

    pdf10 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 474 | Lượt tải: 0

  • Study on band gap energy of pure and Tb3+ doped Zno powderStudy on band gap energy of pure and Tb3+ doped Zno powder

    Abstract. In this paper, we present one method to determine the band gap energy of ZnO and ZnO:Tb3+materials. ZnO:Tb3+ material has prepared by forced hydrolysis method. All samples have zinc oxide hexagonal wurzite structure. The obtained results show that the energy of the band gap depends on Tb3+ molar ratio.

    pdf6 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 435 | Lượt tải: 0

  • Determination of the volatile constituents of liverwort porella densifolia (Hepaticae) by using gas chromatography/mass spectrometry (GC/MS)Determination of the volatile constituents of liverwort porella densifolia (Hepaticae) by using gas chromatography/mass spectrometry (GC/MS)

    Abstract. Twelve volatile constituents were identified from Liverwort Porella densifolia (Hepaticae) collected at Ham Rong Mountain, Sapa, Lao Cai Province by gas chromatography/mass spectrometry (GC/MS). The volatile constituents including some monoterpenes (β-myrcene, α- pinene and camphene); two major sesquiterpenes, deoxopinguisone and bic...

    pdf4 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 456 | Lượt tải: 0

  • Study on the chemical constituents in roots of Smilax glabra Roxb. cultivated in Thai Nguyen provinceStudy on the chemical constituents in roots of Smilax glabra Roxb. cultivated in Thai Nguyen province

    Abstract. From the ethanol extract of the Smilax glabra growing in Thai Nguyen province, five compounds such as stigmasta-5,22-diene-3β-ol (1), 3β-sitosterol-glucopyranoside (2), 4’,5,7-trihydroxyflavanone-3-O-α-Lrhamnopyranoside (engeletin) (3), 3’,5,5’,7-tetrahydroxyflavanone-3-O-α-Lrhamnopyranoside (smitilbin) (4), and 3’,4’,5,7-tetrahydroxyfl...

    pdf9 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 473 | Lượt tải: 0

  • New monomers for chemical vapor deposition polymerization of poly(p-Xylylene)New monomers for chemical vapor deposition polymerization of poly(p-Xylylene)

    Abstract. It was demonstrated that Poly(p-Xylylene) (PPX) could be prepared from α,α’-Bis(Alkoxy or Aryloxy) –p-Xylenes via chemical vapor decomposition (CVD)- method. This is one-step process and there are side products by the CVD-process. This effect depends both on the CVD- condition and the properties of the starting monomer. The structure ...

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  • A study on methanation of carbon monoxide over catalysts NiO/TiO2 AND NiO/γ-Al2O3A study on methanation of carbon monoxide over catalysts NiO/TiO2 AND NiO/γ-Al2O3

    Abstract. The catalyst 7.5% NiO/TiO2 and seven samples of NiO/γ-Al2O3 with NiO content from 7.5% to 60% have been obtained and studied. Physico-chemical characteristics of the catalysts were determined by methods of Adsorption (BET), X-ray Diffraction (XRD), TemperatureProgrammed Reduction (TPR) and Hydrogen Pulse Titration. The catalytic properti...

    pdf16 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 482 | Lượt tải: 0

  • Preparation of superabsorbent polymers by the inverse suspension methodPreparation of superabsorbent polymers by the inverse suspension method

    Abstract. The superabsorbent polymers based on acrylic acid have been prepared in the presence of ammonium persulfate (APS) as initiator and N,N-methylene- bis- acrylamide (MBA) as crosslinking agent. The suspension polymerisation occurred in aqueous drops dispersed in toluene and stabilised by sorbitan monooleate. Some effects on the swelling de...

    pdf6 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 538 | Lượt tải: 0