ISOLATION AND IDENTIFICATION OF PHYTOPATHOGENIC FUNGI FROM INFECTED PLANT PARTS

Objective: The present study deals with the isolation and identification of phytopathogenic fungi. The fungal isolates were Alternaria spp (Tomato early blight), Fusarium oxysporum (Fusarium wilt), Fusarium solani (daming off and root rot), Aspergillus flavus (Ear rot) and Collectotricumspp (Anthracnose).Methods: They were isolated from infected plant parts and were identified on the basis of colony morphology andlacto phenol cotton blue (LPCB) stains were used to identifymicroscopic examination of spore structures. Pure cultures of the isolates were sub cultured and transferred onto differential media; potato dextrose agar, malt extract agar, czapek yeast extract agar and czapek dox agar for species identification using macro morphological characteristicsThe morphological characteristics of these fungal elements showed various kinds of spores have been identified up to genus/species level.Results: This study proves rapid and less expensive techniques to validate a primary alarm of contamination.Conclusion: The fivefungus which were isolated from different plant parts were very effective in distruction of the plant and found that the producionwere reduced due to the infection. This rapid and less expensive techniques to validate a primary alarm of contamination

ANTIFUNGAL ACTIVITY OF ACTINOBACTERIA WITH A POTENTIAL TO INHIBIT RICE BLAST FUNGUS MAGNAPORTHE ORYZAE (ANAMORPH PYRICULARIA ORYZAE)

Objective: The aims of the present study were to screen the actinobacteria with high potential ability to produce secondary metabolites that have inhibitory activity against plant pathogenic fungi, Magnaporthe oryzae. Production of secondary metabolites was analysis by thin-layer chromatography and bioautography assay. Methods: Screening and selection of potential Streptomyces sp. morphological, cultural, physiological, and biochemical characterization of the screened isolate was carried out. Antifungal compound was confirmed by bioautography assay. Results: Bioautography method use in this study was found to be antifungal fraction from the crude extract. Antifungal secondary metabolites can be readily located on the plates by observing clear zones where active compounds inhibit fungal growth. Conclusion: The bioautography assay shows that this isolates can produce antifungal compound. Therefore, this isolate proves to be a promising microbe which can be further studied for its applications a biocontrol agent against rice blast fungi

Reply to Comment on ``Two-dimensional charged-exciton complexes''

We respond to criticisms raised by K. Varga (cond-mat/9802262) and reaffirm that the results in our original paper obtained using a two-body analytical method remains valid within the framework of an effective excitonic composite model. The conceptual model of the excitonic systems as well as the numerical method based on variational functions utilized by Varga differ significantly from ours. Hence comparison of binding energies of the charged-biexciton remains questionable. In this reply, we discuss the shortcomings of modelling the charged-biexciton as a five-body system and treating excitonic complexes as atomic systems, as done in Varga's Comment.Comment: 3 pages, no figure

Spin dynamics of low-dimensional excitons due to acoustic phonons

We investigate the spin dynamics of excitons interacting with acoustic phonons in quantum wells, quantum wires and quantum disks by employing a multiband model based on the $4\times4$ Luttinger Hamiltonian. We also use the Bir-Pikus Hamiltonian to model the coupling of excitons to both longitudinal acoustic phonons and transverse acoustic phonons, thereby providing us with a realistic framework in which to determine details of the spin dynamics of excitons. We use a fractional dimensional formulation to model the excitonic wavefunctions and we demonstrate explicitly the decrease of spin relaxation time with dimensionality. Our numerical results are consistent with experimental results of spin relaxation times for various configurations of the GaAs/Al$_{0.3}$Ga$_{0.7}$As material system. We find that longitudinal and transverse acoustic phonons are equally significant in processes of exciton spin relaxations involving acoustic phonons.Comment: 24 pages, 3 figure

Theory of neutral and charged exciton scattering with electrons in semiconductor quantum wells

Electron scattering on both neutral ($X$) and charged ($X^-$) excitons in quantum wells is studied theoretically. A microscopic model is presented, taking into account both elastic and dissociating scattering. The model is based on calculating the exciton-electron direct and exchange interaction matrix elements, from which we derive the exciton scattering rates. We find that for an electron density of $10^9 {\rm cm}^{-2}$ in a GaAs QW at $T=5K$, the $X^-$ linewidth due to electron scattering is roughly twice as large as that of the neutral exciton. This reflects both the $X^-$ larger interaction matrix elements compared with those of $X$, and their different dependence on the transferred momentum. Calculated reflection spectra can then be obtained by considering the three electronic excitations of the system, namely, the heavy-hole and light-hole 1S neutral excitons, and the heavy-hole 1S charged exciton, with the appropriate oscillator strengths.Comment: 18 pages, 12 figure

Perception to Virtual Design Studio in the Initiation, Realization and Reflection Phase: The Faculties and Students Perspective

The study examines virtual design studio pedagogy in regional settings, providing a comprehensive understanding of the experiences of faculty members and students as they adapted to the virtual design studio due to the COVID-19 pandemic. The research focused on B.Arch., an undergraduate program affiliated with the University of Calicut, Malappuram, Kerala, India. A survey-based cluster sampling approach was made use of. The survey questionnaire collected information from faculties and students on various aspects of the virtual discourse, and SPSS software was used to analyze the data. The Mann-Whitney U test (non-parametric test) was employed to compare adaptation and acceptance levels of virtual design studios between faculties and students. The results indicated differences in adaptation and acceptance levels between the two groups. The research also outlines the various stage-wise phases of the virtual design studio model. Further explores the future of architecture studio pedagogy in a post-Covid scenario, with emphasis on hybrid mode, which could be an area for future research

A first-principles study of the dielectric properties of TiO2 polymorphs

We present an analysis of the dielectric properties of the three polymorphs of TiO2 (rutile, anatase and brookite phases), using ab initio time-dependent density functional perturbation theory based on the Vignale–Kohn functional. We implement this functional, which incorporates many-body effects, using the periodic program BAND. The improved result for the density of states spectra for brookite is suggestive of increased titanium ion Jahn–Teller effects for this phase. The imaginary and real components of the frequency-dependent dielectric functions show notable dielectric anisotropies, with implications for excitonic interactions, for all three common phases of TiO2. Comparison of the electron energy-loss spectrum for undoped and doped rutile and anatase reveals the critical role of collective charge excitations in photocatalytic mechanisms. The correlation between plasmon peaks present at lower energies and decreased photocatalytic activity due to substitutional aluminum doping in combination with oxygen vacancies in rutile and anatase is highlighted. Moreover, there is clear correlation between dielectric properties and the microstructure of the TiO2 polymorphs as suggested via the framework of the Born effective charge and Hirshfeld charge distribution schemes.

Not Available

Not AvailableNot AvailableNot Availabl