603 research outputs found
PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL ACTIVITY OF SWIETENIA MAHAGONI – A HIGHLY MEDICINAL PLANT IN INDIA
The present study was designed to evaluate the phytochemical analysis and antibacterial activity of Swietenia mahagoni leaf extract. The leaf extract was subjected to a variety of phytochemical analysis. The qualitative phytochemical tests exhibited the presence of common phytocompounds like alkaloids, tannins, saponins, phlobatannins, flavanoids, terpenoids and volatile oils as major active constituents. The plant (Swietenia mahagoni) leaf has valuable medicinal uses, hence petroleum ether (18.2g) was found to be a good solvent for the phytochemical and antibacterial study. Similarly, the Methanolic leaf extract of Swietenia mahagoni has highest zone of inhibition on Bacillus subtilis
Perspective on Quark Mass and Mixing Relations
Recent data indicate that , while
seems to be GeV. The relations and suggest that %a plausible clean separation of
the %origin of the quark mixing matrix: the down type sector is responsible for
and , while comes from the up
type sector. Five to six parameters might suffice to account for the ten quark
mass and mixing parameters, resulting in specific power series representations
for the mass matrices. In this picture, seems to be the more sensible
expansion parameter, while is
tied empirically to .Comment: 10 pages, ReVtex, no figure
Proton Decay in a Minimal SUSY SO(10) Model for Neutrino Mixings
A minimal renormalizable SUSY SO(10) model with B-L symmetry broken by {\bf
126} Higgs field has recently been shown to predict all neutrino mixings and
the ratio in agreement with observations.
Unlike models where B-L is broken by {\bf 16} Higgs, this model guarantees
automatic R-parity conservation and hence a stable dark matter as well as the
absence of dim=4 baryon violating operator without any additional symmetry
assumptions. In this paper, we discuss the predictions of the model for proton
decay induced at the GUT scale. We scan over the parameter space of the model
allowed by neutrino data and find upper bounds on the partial lifetime for the
modes yrs and yrs for the
average squark mass of a TeV and wino mass of 200 GeV, when the parameters
satisfy the present lower limits on mode. These
results can be used to test the model.Comment: 17 pages, 6 figures; Minor corrections with improved predictions;
references update
The design and in vivo testing of a locally stiffness-matched porous scaffold
An increasing volume of work supports utilising the mechanobiology of bone for bone ingrowth into a porous scaffold. However, typically during in vivo testing of implants, the mechanical properties of the bone being replaced are not quantified. Consequently there remains inconsistencies in the literature regarding ‘optimum’ pore size and porosity for bone ingrowth. It is also difficult to compare ingrowth results between studies and to translate in vivo animal testing to human subjects without understanding the mechanical environment. This study presents a clinically applicable approach to determining local bone mechanical properties and design of a scaffold with similar properties. The performance of the scaffold was investigated in vivo in an ovine model. The density, modulus and strength of trabecular bone from the medial femoral condyle from ovine bones was characterised and power-law relationships were established. A porous titanium scaffold, intended to maintain bone mechanical homeostasis, was additively manufactured and implanted into the medial femoral condyle of 6 ewes. The stiffness of the scaffold varied throughout the heterogeneous structure and matched the stiffness variation of bone at the surgical site. Bone ingrowth into the scaffold was 10.73 ± 2.97% after 6 weeks. Fine woven bone, in the interior of the scaffold, and intense formations of more developed woven bone overlaid with lamellar bone at the implant periphery were observed. The workflow presented will allow future in vivo testing to test specific bone strains on bone ingrowth in response to a scaffold and allow for better translation from in vivo testing to commercial implants
tRNA epitranscriptomics and biased codon are linked to proteome expression in
Among components of the translational machinery, ribonucleoside modifications on tRNAs are emerging as critical regulators of cell physiology and stress response. Here, we demonstrate highly coordinated behavior of the repertoire of tRNA modifications of Plasmodium falciparum throughout the intra-erythrocytic developmental cycle (IDC). We observed both a synchronized increase in 22 of 28 modifications from ring to trophozoite stage, consistent with tRNA maturation during translational up-regulation, and asynchronous changes in six modifications. Quantitative analysis of ~2,100 proteins across the IDC revealed that up- and down-regulated proteins in late but not early stages have a marked codon bias that directly correlates with parallel changes in tRNA modifications and enhanced translational efficiency. We thus propose a model in which tRNA modifications modulate the abundance of stage-specific proteins by enhancing translation efficiency of codon-biased transcripts for critical genes. These findings reveal novel epitranscriptomic and translational control mechanisms in the development and pathogenesis of Plasmodium parasites.Singapore. National Research FoundationSingapore-MIT Alliance (Graduate Fellowship
Leptophobic Character of the Z' in an SU(3)_C x SU(3)_L x U(1)_X model
We show that the extra Z boson predicted within the so-called "3-3-1" model
has a leptophobic character, and analyse its effects on Z decay widths and on
the t\bar t production cross section in p\bar p collisions at the Fermilab
Tevatron. Recent model-independent analysis are applied in order to estimate
the contribution of this Z' to the observables that will be measured at LEP2.Comment: 11 pages, REVTeX. To be published in Phys. Lett.
Flavon exchange effects in models with abelian flavor symmetry
In models with abelian flavor symmetry the small mixing angles and mass
ratios of quarks and leptons are typically given by powers of small parameters
characterizing the spontaneous breaking of flavor symmetry by "flavon" fields.
If the scale of the breaking of flavor symmetry is near the weak scale, flavon
exchange can lead to interesting flavor-violating and CP violating effects.
These are studied. It is found that d_e, mu -> e + gamma, and mu-e conversion
on nuclei can be near present limits. For significant range of parameters mu-e
conversion can be the most sensitive way to look for such effects.Comment: 19 pages, 5 Postscript figures, LATE
Phenomenological Consequences of Singlet Neutrinos
In this paper, we study the phenomenology of right-handed neutrino
isosinglets. We consider the general situation where the neutrino masses are
not necessarily given by , where and are the Dirac and
Majorana mass terms respectively. The consequent mixing between the light and
heavy neutrinos is then not suppressed, and we treat it as an independent
parameter in the analysis. It turns out that conversion is an important
experiment in placing limits on the heavy mass scale () and the mixing.
Mixings among light neutrinos are constrained by neutrinoless double beta
decay, as well as by solar and atmospheric neutrino experiments. Detailed
one-loop calculations for lepton number violating vertices are provided.Comment: Revtex file,TRI-PP-94-1,VPI-IHEP-94-1, 23 pages, a compressed for 8
figures is appende
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
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