Accelerated cellular senescence in solid tumor therapy

Accelerated cellular senescence (ACS) is an emerging concept that implicates sustained, telomere-independent cell cycle arrest of neoplastic cells in response to chemotherapeutic agents, ionizing radiation, oxidative stress, or the presence of selective oncogenic stimuli. Recent evidence suggests that a subset of tumor cells induced in a state of reversible ACS can escape cell cycle arrest and resume proliferation accounting for cancer progression. The purpose of this review is to describe our current understanding of ACS including signaling pathways of senescence escape, role of senescence biomarkers, and rationale for senescence-based therapy. This article is part of a Special Issue entitled “Apoptosis: Four Decades Later”

Extracellular secretion of Carocin S1 in Pectobacterium carotovorum subsp. carotovorum occurs via the type III secretion system integral to the bacterial flagellum

Background: Pectobacterium carotovorum subsp. carotovorum is a phytopathogenic enterobacterium responsible for soft rot, a disease characterized by extensive maceration of the affected plant tissue. This species also produces two or more antibacterial substances called bacteriocins, which enhance its competitiveness against related rival species. However, the secretion mechanism for low-molecular-weight bacteriocin is still unknown. Results: A mutant (flhC::Tn5) that did not secrete the low-molecular-weight bacteriocin (LMWB), Carocin S1, was generated by Tn5 insertional mutagenesis. Sequence analysis indicated that this insertion disrupted open reading frame 2 (ORF2) and ORF3 of this strain. Deletion and rescue experiments indicated that ORF2 and ORF3 were both required for extracellular LMWB secretion. The ORF2 and ORF3 sequences showed high homology with the flhD and flhC gene sequences of Pectobacterium carotovorum subsp. atroseptica, Serratia marcescens, Yersinia enterocolitica, and Escherichia coli, indicating that they likely encoded key regulatory components of the type III flagella secretion system. Conclusion: Thus, the extracellular export of Carocin S1 by Pectobacterium carotovorum subsp. carotovorum appears to utilize the type III secretion system integral to bacterial flagella

Precision boson-jet azimuthal decorrelation at hadron colliders

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Comparative analysis of full genomic sequences among different genotypes of dengue virus type 3

<p>Abstract</p> <p>Background</p> <p>Although the previous study demonstrated the envelope protein of dengue viruses is under purifying selection pressure, little is known about the genetic differences of full-length viral genomes of DENV-3. In our study, complete genomic sequencing of DENV-3 strains collected from different geographical locations and isolation years were determined and the sequence diversity as well as selection pressure sites in the DENV genome other than within the E gene were also analyzed.</p> <p>Results</p> <p>Using maximum likelihood and Bayesian approaches, our phylogenetic analysis revealed that the Taiwan's indigenous DENV-3 isolated from 1994 and 1998 dengue/DHF epidemics and one 1999 sporadic case were of the three different genotypes – I, II, and III, each associated with DENV-3 circulating in Indonesia, Thailand and Sri Lanka, respectively. Sequence diversity and selection pressure of different genomic regions among DENV-3 different genotypes was further examined to understand the global DENV-3 evolution. The highest nucleotide sequence diversity among the fully sequenced DENV-3 strains was found in the nonstructural protein 2A (mean ± SD: 5.84 ± 0.54) and envelope protein gene regions (mean ± SD: 5.04 ± 0.32). Further analysis found that positive selection pressure of DENV-3 may occur in the non-structural protein 1 gene region and the positive selection site was detected at position 178 of the NS1 gene.</p> <p>Conclusion</p> <p>Our study confirmed that the envelope protein is under purifying selection pressure although it presented higher sequence diversity. The detection of positive selection pressure in the non-structural protein along genotype II indicated that DENV-3 originated from Southeast Asia needs to monitor the emergence of DENV strains with epidemic potential for better epidemic prevention and vaccine development.</p

From graphene and topological insulators to Weyl semimetals

Here we present a short introduction into physics of Dirac materials. In particular we review main physical properties of various two-dimensional crystals such as graphene, sil- icene, germanene and others.We comment on the origin of their buckled two-dimensional shape, and address the issues created by Mermin-Wagner theorem prohibiting the exis- tence of strictly two-dimensional, at crystals. Then we describe main ideas which were leading to the discovery of two and three-dimensional topological insulators and Weyl fermions. We describe some of their outstanding electronic properties which have been originating due to the existence of the Dirac gapless spectrum. We also compare simplest devices made of Dirac materials. Analogies and di erences between Dirac materials and optics are also discussed

Superconducting properties of RuSr2GdCu2O8 studied by SQUID magnetometry

For polycrystalline RuSr2GdCu2O8 (Ru-1212), distinct peaks have been reported in d.c. magnetization in the superconducting state of the sample. Sr2GdRuO6 (Sr-2116), the precursor for the preparation of Ru-1212, shows similar peaks in the same temperature regime. Based on measurements performed on both bulk and powdered samples of Ru-1212 and Sr-2116, we exclude the possibility, that the observed behavior of the magnetization of Ru-1212 is due to Sr-2116 impurities. The effect is related to the superconductivity of Ru-1212, but it is not an intrinsic property of this compound. We provide evidence that the observation of magnetization peaks in the superconducting state of Ru-1212 is due to flux motion generated by the movement of the sample in an inhomogeneous field, during the measurement in the SQUID magnetometer. We propose several tests, that help to decide, whether the features observed in a SQUID magnetization measurement of Ru-1212 represent a property of the compound or not.Comment: 22 pages, 9 figure

Local disorder and optical properties in V-shaped quantum wires : towards one-dimensional exciton systems

The exciton localization is studied in GaAs/GaAlAs V-shaped quantum wires (QWRs) by high spatial resolution spectroscopy. Scanning optical imaging of different generations of samples shows that the localization length has been enhanced as the growth techniques were improved. In the best samples, excitons are delocalized in islands of length of the order of 1 micron, and form a continuum of 1D states in each of them, as evidenced by the sqrt(T) dependence of the radiative lifetime. On the opposite, in the previous generation of QWRs, the localization length is typically 50 nm and the QWR behaves as a collection of quantum boxes. These localization properties are compared to structural properties and related to the progresses of the growth techniques. The presence of residual disorder is evidenced in the best samples and explained by the separation of electrons and holes due to the large in-built piezo-electric field present in the structure.Comment: 8 figure

Bonding mechanism from the impact of thermally sprayed solid particles

Power particles are mainly in solid state prior to impact on substrates from high velocity oxy-fuel (HVOF) thermal spraying. The bonding between particles and substrates is critical to ensure the quality of coating. Finite element analysis (FEA) models are developed to simulate the impingement process of solid particle impact on substrates. This numerical study examines the bonding mechanism between particles and substrates and establishes the critical particle impact parameters for bonding. Considering the morphology of particles, the shear-instability–based method is applied to all the particles, and the energy-based method is employed only for spherical particles. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results confirm that in the HVOF process, the kinetic energy of the particle prior to impact plays the most dominant role in particle stress localization and melting of the interfacial contact region. The critical impact parameters, such as particle velocity and temperature, are shown to be affected by the shape of particles, while higher impact velocity is required for highly nonspherical powder

Phonon-drag effects on thermoelectric power

We carry out a calculation of the phonon-drag contribution $S_g$ to the thermoelectric power of bulk semiconductors and quantum well structures for the first time using the balance equation transport theory extended to the weakly nonuniform systems. Introducing wavevector and phonon-mode dependent relaxation times due to phonon-phonon interactions, the formula obtained can be used not only at low temperatures where the phonon mean free path is determined by boundary scattering, but also at high temperatures. In the linear transport limit, $S_g$ is equivalent to the result obtained from the Boltzmann equation with a relaxation time approximation. The theory is applied to experiments and agreement is found between the theoretical predictions and experimental results. The role of hot-electron effects in $S_g$ is discussed. The importance of the contribution of $S_g$ to thermoelectric power in the hot-electron transport condition is emphasized.Comment: 8 pages, REVTEX 3.0, 7 figures avilable upon reques