10,798 research outputs found
Anti-chiral edge states in an exciton polariton strip
We present a scheme to obtain anti-chiral edge states in an exciton-polariton
honeycomb lattice with strip geometry, where the modes corresponding to both
edges propagate in the same direction. Under resonant pumping the effect of a
polariton condensate with nonzero velocity in one linear polarization is
predicted to tilt the dispersion of polaritons in the other, which results in
an energy shift between two Dirac cones and the otherwise flat edge states
become tilted. Our simulations show that due to the spatial separation from the
bulk modes the edge modes are robust against disorder.Comment: 6 pages, 5 figure
Role of S gene product of bacteriophage lambda in host cell lysis
Studies with the induced lysogens of λ S +R+, λS-R+, λS+R- and λS-R- phages have shown that while the S gene product is essential for the action of intracellular R gene product to release the periplasmic alkaline phosphatase in the presence of EDTA, the latter gene product can bring about this effect while acting on Escherichia coli cells from outside, in the absence of functional S gene product; chloroform, could help the intracellular R gene product in effecting bacterial lysis in the absence of S gene product. These result support the premise that the S gene product facilitates the R gene product in crossing the cytoplasmic membrane into the periplasmic space such that the latter can act on the peptidoglycan layer of the host cell thus causing both the release of alkaline phosphatase and cell lysis
Iron leaching from China clay with oxalic acid: effect of different physico-chemical parameters
China clay is an important mineral, which is used in the manufacture of ceramics and refractory, as also in other industries.
Mined China clay contains iron oxides and silicates as impurity; if present in excess of a threshold level, the impurities affect the
commercial value of the products. Currently available processes for lowering the iron content in China clay to the desired level
( < 0.8%) are energy- and cost-intensive, not sufficiently flexible, and may cause environmental pollution. An alternative
approach for iron removal consists in the development of a biotechnological process which is expected to be cost-effective, less
complex and eco-friendly. We reported earlier that several fungi, especially Aspergillus niger, and their culture filtrates could
leach sufficient amount of iron from a China clay sample; oxalic acid was found to be the most active component of the culture
filtrate (Trans. Indian Inst. Met. 55 (2002) 1). We now report the rates of iron leaching from another China clay sample by
oxalic acid and by the culture filtrate of A. niger NCIM 548 that was found to be the most active strain in our previous study
(Trans. Indian Inst. Met. 55 (2002) 1). The iron-leaching rates increased with temperature (T) and followed biphasic kinetics.
The effect of oxalic acid concentration (C), pH (H), solids concentration or pulp density ( P), time and mode of agitation on the
rate of iron leaching is described. The rate of leaching with oxalic acid (Rox) can be calculated theoretically from the following
relationship: Roxf(C)0.76(T)1.76(H)0.80( P)0.20 under the specified set of conditions. Using the same concentration of oxalic acid
in A. niger culture filtrate, the relationship of the rate differed; this may be due to the influence of other metabolites present in
the culture filtrate on the rate
PTEN negatively regulates mTORC2 formation and signaling in grade IV glioma via Rictor hyperphosphorylation at Thr1135 and direct the mode of action of an mTORC1/2 inhibitor
To investigate the role of PTEN (phosphatase and tensin homolog) in mammalian target of rapamycin complex 2 (mTORC2)
signaling in glioblastoma multiforme (GBM), we found higher activation of mTORC2 in PTENmu cells, as evidenced by enhanced
phosphorylation of mTOR (Ser2481), AKT (Ser473) and glycogen synthase kinase 3 beta (GSK3β) (Ser9) as compared with PTENwt
cells. In addition, PTENwt cells upon PTEN depletion showed mTORC2 activation. The reduced mTORC2 signaling in PTENwt cells was
related to higher Rictor phosphorylation at Thr1135 residue. Phosphorylation of Rictor at Thr1135 inhibited its association with
mTORC and thus there was a reduction in mTORC2 complex formation. In addition, PTENwt cells expressing mutated Rictor in which
Thr1135 was substituted with alanine, showed enhanced mTORC2 formation and signaling. This enhanced mTORC2 signaling
promoted inactivation of GSK3β. Thus, we established the reciprocal activation of mTORC2 and GSK3β in GBM. To the best of our
knowledge, this is the first report describing role of PTEN in mTORC2 formation by promoting Rictor phosphorylation (Thr1135) in
GBM. Furthermore, the drug sensitivity of mTORC2 was evaluated. A newly identified carbazole alkaloid, mahanine, showed
cytotoxicity in both PTENmu and PTENwt cells. It inhibited both mTORC1/2 and AKT completely in PTENmu cells, whereas it inhibited
only mTORC1 in PTENwt cells. Cytotoxity and AKT-inhibitory activity of the mTORC1/2 inhibitor was increased either by depleting
PTEN or in combination with phosphatidylinositol 3 kinase inhibitors in PTENwt cells. In contrast, depletion of Rictor decreased the
cytotoxicity of the mTORC1/2 inhibitor in PTENmu cells. Thus, PTEN has an important role in mTORC2 formation and also influences
the effectiveness of an mTORC1/2 inhibitor in GBM
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