Adsorption, Segregation and Magnetization of a Single Mn Adatom on the GaAs (110) Surface

Density functional calculations with a large unit cell have been conducted to investigate adsorption, segregation and magnetization of Mn monomer on GaAs(110). The Mn adatom is rather mobile along the trench on GaAs(110), with an energy barrier of 0.56 eV. The energy barrier for segregation across the trenches is nevertheless very high, 1.67 eV. The plots of density of states display a wide gap in the majority spin channel, but show plenty of metal-induced gap states in the minority spin channel. The Mn atoms might be invisibl in scanning tunneling microscope (STM) images taken with small biases, due to the directional p-d hybridization. For example, one will more likely see two bright spots on Mn/GaAs(110), despite the fact that there is only one Mn adatom in the system

On delayed genetic regulatory networks with polytopic uncertainties: Robust stability analysis

Copyright [2008] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this paper, we investigate the robust asymptotic stability problem of genetic regulatory networks with time-varying delays and polytopic parameter uncertainties. Both cases of differentiable and nondifferentiable time-delays are considered, and the convex polytopic description is utilized to characterize the genetic network model uncertainties. By using a Lyapunov functional approach and linear matrix inequality (LMI) techniques, the stability criteria for the uncertain delayed genetic networks are established in the form of LMIs, which can be readily verified by using standard numerical software. An important feature of the results reported here is that all the stability conditions are dependent on the upper and lower bounds of the delays, which is made possible by using up-to-date techniques for achieving delay dependence. Another feature of the results lies in that a novel Lyapunov functional dependent on the uncertain parameters is utilized, which renders the results to be potentially less conservative than those obtained via a fixed Lyapunov functional for the entire uncertainty domain. A genetic network example is employed to illustrate the applicability and usefulness of the developed theoretical results

Valosin-containing protein regulates the proteasome-mediated degradation of DNA-PKcs in glioma cells.

DNA-dependent protein kinase (DNA-PK) has an important role in the repair of DNA damage and regulates the radiation sensitivity of glioblastoma cells. The VCP (valosine-containing protein), a chaperone protein that regulates ubiquitin-dependent protein degradation, is phosphorylated by DNA-PK and recruited to DNA double-strand break sites to regulate DNA damage repair. However, it is not clear whether VCP is involved in DNA-PKcs (DNA-PK catalytic subunit) degradation or whether it regulates the radiosensitivity of glioblastoma. Our data demonstrated that DNA-PKcs was ubiquitinated and bound to VCP. VCP knockdown resulted in the accumulation of the DNA-PKcs protein in glioblastoma cells, and the proteasome inhibitor MG132 synergised this increase. As expected, this increase promoted the efficiency of DNA repair in several glioblastoma cell lines; in turn, this enhanced activity decreased the radiation sensitivity and prolonged the survival fraction of glioblastoma cells in vitro. Moreover, the VCP knockdown in glioblastoma cells reduced the survival time of the xenografted mice with radiation treatment relative to the control xenografted glioblastoma mice. In addition, the VCP protein was also downregulated in ~25% of GBM tissues from patients (WHO, grade IV astrocytoma), and the VCP protein level was correlated with patient survival (R(2)=0.5222, P<0.05). These findings demonstrated that VCP regulates DNA-PKcs degradation and increases the sensitivity of GBM cells to radiation

Immunomodulation with Probiotics Against Aeromonas veronii in Grass Carp (Ctenopharyngodon idellus)

Aeromonas comprisea wide range of opportunistic bacteria that cause septicemia (blood poisoning)in fish.Withexpandingaquaculture, myriad methods have been used to combat these pathologiesincludingprobiotics and plant extracts which canpotentiallyaddress these diseases without harmingthe environment. Inthis study, four strains of opportunistic pathogens were isolated from diseased fish, thenmolecular identification of 16SrDNA was performed. Results identifiedthe four strains asAeromonas veronii, Shewanella sp., Bacillus cereus, and Aeromonas salmonicida. Experimental trialsrevealed that A.veroniiwas the primary strain. Multiple virulence-related factors were discovered, includingaerolysin (Aer), cytotoxic enterotoxin (Act), and the outer membrane protein (OmpAII).Thesewere foundonly in A.veronii. LC50 in grass carp was 3.6×104CFU/mLover 96 h, whereas the safe concentration was 9.11×103CFU/mL.Grass carp were challenged with 3 differentconcentrations of A.veronii. Following a 48h incubation period they were treated for 24 h, 48 h, and 72 h with 8.1×106CFU/mLconcentrations.The expression ofInterleukin-8(IL-8)andTumor Necrosis Factor-α(TNF-α)was up-regulated in the kidney, liver, spleen, and heart using qRT-PCR. Simultaneously, enzyme activity involving Pyruvate Kinase(PK),Alkaline Phosphatase(AKP), Alanine aminotransferase (ALT),Succinate Dehydrogenase (SDH), and Lysozyme (Lsz)inserum and liver tissues was significantly up-regulated.We found that probiotics enhancedgrowth of grass carp, improvedhealth status,and was beneficial in reducing the prevalence of this disease. Subsequent to feeding mixed probiotics,IL-8 and TNF-α geneexpression was significantly lower (p>0.05)than inthe infected group,at 16 and 31 days. Expression of these genes in the liver, spleen, and intestines of healthy grass carp fed probiotics wassignificantly up-regulated in contrast to grass carp fed a basal diet (p<0.05).Our results suggestthat use of probiotics as immune stimulator may improve the control of fish diseases in aquaculture