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Friction stir processing of squeeze cast A356 with surface compacted graphene nanoplatelets (GNPs) for the synthesis of metal matrix composites
No full textFriction stir processing (FSP) was applied to graphene nanoplatelets (GNPs) physically compacted on the surface of squeeze cast A356 alloy to incorporate GNPs within the matrix and to improve its mechanical properties. Squeeze casting resulted in finer size silicon and intermetallic compounds in cast microstructure, and subsequently FSP further refined the microstructure of squeeze cast A356 alloy, and GNP reinforced A356 alloy. The finer Si particles, intermetallics and graphene dispersed in the matrix increased the yield and ultimate tensile strength of FSP squeeze cast A356 alloy compared to the results reported in prior literature for FSP A356 alloy. Eutectic Si needles have been converted to fine spherical particles during FSP and were uniformly distributed within the nugget zone. The crystallite size of GNPs which were physically adhered to the surface of squeeze cast alloy prior to FSP decreased after FSP as a result of deformation. Thus, a combination of squeeze casting, and friction stir processing and incorporation of GNPs reinforcement in the A356 matrix is a promising route to further improve its mechanical properties
Unity and diversity among viral kinases
No full textViral kinases are known to undergo autophosphorylation and also phosphorylate viral and host substrates. Viral kinases have been implicated in various diseases and are also known to acquire host kinases for mimicking cellular functions and exhibit virulence. Although substantial analyses have been reported in the literature on diversity of viral kinases, there is a gap in the understanding of sequence and structural similarity among kinases from different classes of viruses. In this study, we performed a comprehensive analysis of protein kinases encoded in viral genomes. Homology search methods have been used to identify kinases from 104,282 viral genomic datasets. Serine/threonine and tyrosine kinases are identified only in 390 viral genomes. Out of seven viral classes that are based on nature of genetic material, only viruses having double-stranded DNA and single-stranded RNA retroviruses are found to encode kinases. The 716 identified protein kinases are classified into 63 subfamilies based on their sequence similarity within each cluster, and sequence signatures have been identified for each subfamily. 11 clusters are well represented with at least 10 members in each of these clusters. Kinases from dsDNA viruses, Phycodnaviridae which infect green algae and Herpesvirales that infect vertebrates including human, form a major group. From our analysis, it has been observed that the protein kinases in viruses belonging to same taxonomic lineages form discrete clusters and the kinases encoded in alphaherpesvirus form host-specific clusters. A comprehensive sequence and structure-based analysis enabled us to identify the conserved residues or motifs in kinase catalytic domain regions across all viral kinases. Conserved sequence regions that are specific to a particular viral kinase cluster and the kinases that show close similarity to eukaryotic kinases were identified by using sequence and three-dimensional structural regions of eukaryotic kinases as reference. The regions specific to each viral kinase cluster can be used as signatures in the future in classifying uncharacterized viral kinases. We note that kinases from giant viruses Marseilleviridae have close similarity to viral oncogenes in the functional regions and in putative substrate binding regions indicating their possible role in cancer
Recovery of quantum information from a node failure in a graph
No full textQuantum entanglement is a well-known quantum way of introducing redundancy in quantum error correcting codes. The unitary interactions when modeled using edges of a graph with qubits as nodes give rise to a quantum graph state. Quantum graph states are highly entangled quantum states created using specific unitary interactions between qubits. We consider the problem of failure of a node of the graph. The node failure leads to the loss of one of the qubits of the graph state, resulting in a mixed state. In order to restore the quantum information originally stored in the graph state, we devise a mechanism to purify the mixed state via a unitary operation, followed by measurement. We propose a modification to the existing graph state and call it a modified graph state. This improves the error correction ability of the graph state, and it is able to correct single bit flip errors ensuing after the measurement stage. Using this modified graph state code, our procedure recovers the quantum information in the graph in the event of one node failure
Mn(II) complex of a di-2-pyridyl ketone-N(4)-substituted thiosemicarbazone: Versatile biological properties and naked-eye detection of Fe2+ and Ru3+ ions
No full textA novel manganese(II) complex of a di-2-pyridyl ketone N(4)-phenyl thiosemicarbazone (HL) was synthesized and characterized. Single crystal X-ray diffraction studies revealed that the asymmetric unit of the triclinic unit cell contained two independent Mn(L)2 molecules together with two water molecules of crystallization and a DMF molecule. DNA binding studies of the ligand and its complex were conducted using absorption titrations, fluorescent intercalator displacement assays and viscosity measurements. Both the ligand and the complex were found to show good DNA binding abilities and actively displaced the standard intercalator ethidium bromide. In addition to the DNA binding studies, antimicrobial activities of the compounds were also determined and the complex exhibited higher antibacterial activity compared to the ligand HL. Another interesting property exhibited by the manganese complex was its colorimetric sensing, making it an excellent probe for naked-eye detection of Fe2+ and Ru3+ ions, with a visible color change from yellow to colorless. The recognition ability of the ions by the probe was quantitatively analyzed using a titration ion/complex ratio of 0�2
Optimally allocated nonlinear robust control of a reusable launch vehicle during re-entry
No full textA nonlinear robust control design approach is presented in this paper for a prototype reusable launch vehicle (RLV) during the critical re-entry phase where the margin for error is small. A nominal control is designed following the dynamic inversion philosophy for the reaction control system (RCS) and optimal dynamic inversion philosophy for the aerodynamic control actuation. This nominal controller is augmented next with a barrier Lyapunov function based neuro-adaptive control in the inner loop, which enforces the body rates of the actual system i.e. in presence of uncertainties to track the closed-loop body rates of the nominal plant. A fusion logic is also presented for fusing the RCS and aerodynamic control. The control design approach presented here assures robust tracking of the guidance commands despite the presence of uncertainties in the plant model. Extensive nonlinear six degree-of-freedom (DoF) simulation study, which embeds additional practical constraints such as actuator delay in the aerodynamic control actuation and constraints related to the RCS, shows that the proposed design approach has both good command following as well as robustness characteristics
Differential contributions of pre- And post-EMT tumor cells in breast cancer metastasis
No full textMetastases are responsible for the majority of breast cancer�associated deaths. The contribution of epithelial-to-mesenchymal transition (EMT) in the establishment of metastases is still controversial. To obtain in vivo evidence of EMT in metastasis, we established an EMT lineage tracing (Tri-PyMT) model, in which tumor cells undergoing EMT would irreversibly switch their fluorescent marker from RFPþ to GFPþ due to mesenchymal-specific Cre expression. Surprisingly, we found that lung metastases were predominantly derived from the epithelial compartment of breast tumors. However, concerns were raised on the fidelity and sensitivity of RFP-to-GFP switch of this model in reporting EMT of metastatic tumor cells. Here, we evaluated Tri-PyMT cells at the single-cell level using single-cell RNA-sequencing and found that the Tri-PyMT cells exhibited a spectrum of EMT phenotypes, with EMT-related genes concomitantly expressed with the activation of GFP. The fluorescent color switch in these cells precisely marked an unequivocal change in EMT status, defining the pre-EMT and post-EMT compartments within the tumor. Consistently, the pre-EMT cells played dominant roles in metastasis, while the post-EMT cells were supportive in promoting tumor invasion and angiogenesis. Importantly, the post-EMT (GFPþ) cells in the Tri-PyMT model were not permanently committed to the mesenchymal phenotype; they were still capable of reverting to the epithelial phenotype and giving rise to secondary tumors, suggesting their persistent EMT plasticity. Our study addressed major concerns with the Tri-PyMT EMT lineage tracing model, which provides us with a powerful tool to investigate the dynamic EMT process in tumor biology
Cyclic nucleotides, gut physiology and inflammation
No full textMisregulation of gut function and homeostasis impinges on the overall well-being of the entire organism. Diarrheal disease is the second leading cause of death in children under 5 years of age, and globally, 1.7 billion cases of childhood diarrhea are reported every year. Accompanying diarrheal episodes are a number of secondary effects in gut physiology and structure, such as erosion of the mucosal barrier that lines the gut, facilitating further inflammation of the gut in response to the normal microbiome. Here, we focus on pathogenic bacteria-mediated diarrhea, emphasizing the role of cyclic adenosine 3',5'-monophosphate and cyclic guanosine 3�,5�-monophosphate in driving signaling outputs that result in the secretion of water and ions from the epithelial cells of the gut. We also speculate on how this aberrant efflux and influx of ions could modulate inflammasome signaling, and therefore cell survival and maintenance of gut architecture and function
Certain sequence of arithmetic progressions and a new key sharing method
No full textWe consider a special type of sequence of arithmetic progressions, in which consecutive progressions are related by the property: ithterms ofjth, (j + 1)thprogressions of the sequence are multiplicative inverses of each other modulo(i + 1)thterm ofjthprogression. Such a sequence is uniquely defined for any pair of co-prime numbers. A computational problem, defined in the context of such a sequence and its generalization, is shown to be equivalent to the integer factoring problem. The proof is probabilistic. As an application of the equivalence result, we propose a method for how users securely agree upon secret keys, which are ensured to be random. We compare our method with factoring based public key cryptographic systems: RSA (Rivest et al., ACM 21, 120�126, 1978) and Rabin systems (Rabin 1978). We discuss the advantages of the method, and its potential use-case in the post quantum scenario
In vivo MRS measurement of 2-hydroxyglutarate in patient-derived IDH-mutant xenograft mouse models versus glioma patients
No full textPurpose: To generate a preclinical model of isocitrate dehydrogenase (IDH) mutant gliomas from glioma patients and design a MRS method to test the compatibility of 2-hydroxyglutarate (2HG) production between the preclinical model and patients. Methods: Five patient-derived xenograft (PDX) mice were generated from two glioma patients with IDH1 R132H mutation. A PRESS sequence was tailored at 9.4 T, with computer simulation and phantom analyses, for improving 2HG detection in mice. 2HG and other metabolites in the PDX mice were measured using the optimized MRS at 9.4 T and compared with 3 T MRS measurements of the metabolites in the parental-tumor patients. Spectral fitting was performed with LCModel using in-house basis spectra. Metabolite levels were quantified with reference to water. Results: The PRESS TE was optimized to be 96 ms, at which the 2HG 2.25 ppm signal was narrow and inverted, thereby leading to unequivocal separation of the 2HG resonance from adjacent signals from other metabolites. The optimized MRS provided precise detection of 2HG in mice compared to short-TE MRS at 9.4 T. The 2HG estimates in PDX mice were in excellent agreement with the 2HG measurements in the patients. Conclusion: The similarity of 2HG production between PDX models and parental-tumor patients indicates that PDX tumors retain the parental IDH metabolic fingerprint and can serve as a preclinical model for improving our understanding of the IDH-mutation associated metabolic reprogramming
A solution for the flood cost sharing problem
No full textIn this study, we model and study the flood cost sharing problem on a successive transboundary river shared between n-riparian states. We propose a Sequential Upstream Proportional Allocation (SUPA) solution and axiomatically characterise it. We make use of the Extended Producer Responsibility principle to define a characteristic form game which models cooperative behaviour among riparian states. We show that the proposed sharing rule coincides with the Shapley value of this game. The proposed allocation is also a member of the Core of the game