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81.
S. Bhattacharyya 《Il Nuovo Cimento C》1987,10(6):669-676
Summary The rising ratio of cosmic-ray positrons at ultra-high energies of interactions seems to have puzzled the theorists to a great
extent. We have made here a somewhat successful attempt to interpret the behaviour of this ratio,R=e+/(e++e−), by putting into use the main physical ideas from our two previous works. The importance and the implications of this observation
have also been highlighted and emphasized in the proper background.
Riassunto Il crescente rapporto dei positroni dei raggi cosmici ad energie ultra-alte di interazioni sembra aver non poco confuso i teorici. Qui si tenta con un certo successo di interpretare il comportamento di questo rapportoR=e+/(e++e−) usando i principali concetti fisici dei nostri due precedenti lavori. L'importanza e le implicazioni di questa osservazione sono state sottolineate ed enfatizzate nell'appropriato contesto.
Резюме Увеличивающиеся отношение позитронов космических лучей при ультравыс оких энергиях, по-видимому, представляет загадку для теоретиков. В этой статье мы предпринимает отчасти успешную попытку интерпретировать поведение этого отношенияR=e+/(e++e−), используя основные физические идеи из наших двух предыдущих публикаций. Отмчаются важностя и приложения полученных результатов.相似文献
82.
Finite-incremental Tresca and von Mises theories are developed for solid circular-section torsion-tension members subjected to proportionate and nonproportionate loading. The materials are assumed to be isotropic and even. Two Tresca theories and a von Mises theory are compared with test data obtained from torsion-tension members. Three different kinds of steels were tested; they are hot-rolled mild steel, annealed mild steel, and hot-rolled SAE 1017 steel. The fully plastic values of axial load and torque predicted by the Tresca theories agree with the experimental results; however, the deformations, in the strain-hardening region, predicted by both of the Tresca theories were greater than observed. The von Mises theory is nonconservative in predicting the fully plastic loads of torsion members and torsion-tension members and in predicting the deformations of torsion members in the strain-hardening region, but gives good correlation between predicted and experimental deformations for the torsion-tension members in the strain-hardening region. 相似文献
83.
Subhendu Naskar Priyankar Paira Rupankar Paira Shyamal Mondal Arindam Maity Abhijit Hazra Krishnendu B. Sahu Pritam Saha Sukdeb Banerjee Peter Luger Manuela Webe Nirup B. Mondal 《Tetrahedron》2010,66(27-28):5196-5203
An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives. 相似文献
84.
Structure, stability, and dissociation of H2BSiN, H2NSiN, H2PSiN and their isomers H2BNSi, H2NNSi, H2PNSi have been studied in detail using ab initio MP2 and CCSD(T) methods. After dissociation of H2BNSi, H2NNSi, H2PNSi and their isomers, the fragmented atoms have been considered to be either in their ground state or in their valence excited state in various dissociation channels. Only allowed dissociations of these molecules are considered. Various dissociation channels of H2BNSi, H2NNSi, H2PNSi and their isomers have been explored and interesting trends are observed for the dissociation of stable isomers H2BNSi, H2NNSi, H2PNSi and less stable isomers H2BSiN, H2NSiN, H2PSiN. The effect of substituents on their structural properties has been discussed. The potential energy surfaces for the RSiN ? RNSi isomerization reactions have been analyzed. The structural properties of these molecules agree well with the theoretical values wherever available. 相似文献
85.
Residual stress modulation in the diamond-like carbon coatings with incorporation of gold nanoparticles was studied critically. The films were deposited on glass and Si (1 0 0) substrates by using capacitatively coupled plasma chemical vapor deposition. Stresses in the films were determined from the broadening of the optical absorption tail and were found to decrease from 2.3 GPa to 0.48 GPa with increasing gold content (2-7 at.% Au) in the DLC matrix. Gold incorporation also made the films harder than the corresponding DLC coatings. Modulation of stress with nanocrystalline gold content in the DLC matrix was related to the relative amount of sp2/sp3 content in the DLC films. 相似文献
86.
One of the interesting properties of the NMSSM is that it can accommodate a light pseudoscalar of order 10 GeV. However, such scenarios are challenged by several experimental constraints, especially those related to the fermionic decays of the pseudoscalar. In this Letter, we extend the NMSSM field content by two gauge singlets, with lepton numbers +1 and −1. This serves the twin purpose of generating neutrino masses via the inverse seesaw mechanism and keeping the option of a very light pseudoscalar experimentally viable by opening dominant invisible decay channels of the pseudoscalar which help it evade the existing bounds. 相似文献
87.
88.
An analysis is made using a four-dimensional mathematical model where there is a constant rate of flow of input nutrient. An organism is introduced in the model which is growing by taking in that nutrient. Two other predators on that organism are also introduced. The predators at the second and third trophic levels belong to the same species, though of different age groups. The predator at the third trophic level exhibits a distinct cannibalistic attitude to the predator of the second trophic level. Our analysis leads to different thresholds in terms of the model parameters acting as conditions under which the species associated with the system cannot thrive even in the absence of competition. Local stability of the system is obtained when one or more of the predators go extinct. Under appropriate circumstances a positive rest point of the system is obtained. Computer simulations have been carried out to illustrate different analytical results. 相似文献
89.
This paper deals with bimetallic (Fe/Pd) nanoparticle synthesis inside the membrane pores and application for catalytic dechlorination of toxic organic compounds form aqueous streams. Membranes have been used as platforms for nanoparticle synthesis in order to reduce the agglomeration, encountered in solution phase synthesis which leads to a dramatic loss of reactivity. The membrane support, polyvinylidene fluoride (PVDF) was modified by in situ polymerization of acrylic acid in aqueous phase. Subsequent steps included ion exchange with Fe2+, reduction to Fe0 with sodium borohydride and Pd deposition. Various techniques, such as STEM, EDX, FTIR and permeability measurements, were used for membrane characterization and showed that bimetallic (Fe/Pd) nanoparticles with an average size of 20–30 nm have been incorporated inside of the PAA-coated membrane pores. The Fe/Pd-modified membranes showed a high reactivity toward a model compound, 2,2′-dichlorobiphenyl and a strong dependence of degradation on Pd (hydrogenation catalyst) content. The use of convective flow substantially reduces the degradation time: 43% conversion of dichlorobiphenyl to biphenyl can be achieved in less than 40 s residence time. Another important aspect is the ability to regenerate and reuse the Fe/Pd bimetallic systems by washing with a solution of sodium borohydride, because the iron becomes inactivated (corroded) as the dechlorination reaction proceeds. 相似文献
90.
In the light of the equation of motion method a general expression for polarisability calculation has been derived. From this
general expression, different approximation methods can be deduced for different choices of ground state and excitation manifold.
Among these the coupled Hartree-Fock theory is the most extensively used one for polarisability calculations. It has also
been shown that this theory has a simple relationship with random phase approximation. 相似文献