Minimal polar swimmer at low Reynolds number

We propose a minimal model for a polar swimmer, consisting of two spheres connected by a rigid slender arm, at low Reynolds number. The propulsive velocity for the proposed model is the maximum for any swimming cycle with the same variations in its two degrees of freedom and its displacement in a cycle is achieved entirely in one step. The stroke averaged flow field generated by the contractile swimmer at large distances is found to be dipolar. In addition, the changing radius of one of the spheres generates the field of a potential doublet centered at its initial position.     

Synthesis and evaluation of pyrazole‐incorporated monocarbonyl curcumin analogues as antiproliferative and antioxidant agents

A series of pyrazole‐incorporated monocarbonyl analogues of curcumin were synthesized via Clasien–Schimidt‐type condensation and subsequently screened for in vitro antiproliferative and antioxidant activity. The analogues 4c, 5d, 5e, 5g, 6e, and 6f showed potential activity against the MDA‐MB‐231 cell line. The synthesized analogues were also screened for their antioxidant activity. Compounds 5a , 5e , 6d, and 6f exhibit comparable radical scavenging activity with respect to the standard drug ascorbic acid. Furthermore, a molecular docking study has been conducted for 5d and 5g and suggests that these compounds have a potential to become lead molecules in drug discovery and process.     

Azadirachta indica leaves mediated green synthesized copper oxide nanoparticles induce apoptosis through activation of TNF-α and caspases signaling pathway against cancer cells

Green nanotechnology elucidates highly prioritized anticancer activity. We synthesized Copper oxide nanoparticles (CuONPs) using leaves of Azadirachta indica (A. indica) plants and studied the molecular mechanism of cancer cell apoptosis. After their synthesis, with the help of expository tools like Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), Dynamic light scattering (DLS) and surface zeta potential we confirmed the successful synthesis of CuONPs. Here, crystalline structure of green synthesized CuONPs of 36?±?8?nm size and spherical shape was able to kill MCF-7 and Hela cells, estimated by MTT assay. Successful internalization of Cu⁺² ions inside the cell was estimated by the atomic absorption study. Cellular uptake of Cu⁺² ions inflicted significant Reactive Oxygen Species (ROS) generation inside the cancer cells, thereby leading to DNA fragmentation as observed by DAPI staining. In in vivo model, CuONPs reduced the breast tumor volume in Balb/C mice and increased the mean survival time through the alteration of pro-inflammatory cytokines level. In case of both in vivo and in vitro models, CuONPs altered the pro-inflammatory cytokine level and pro-apoptotic protein expressions. In future, green synthesized CuONPs might be beneficial for its application as an anticancer drug in in vivo (mice model) and in vitro, though further study is needed on its toxicity.     

Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles

We construct the hydrodynamic equations for suspensions of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions: (i) Nematic SPP suspensions are always absolutely unstable at long wavelengths. (ii) SPP suspensions support novel propagating modes at long wavelengths, coupling orientation, flow, and concentration. (iii) In a wave number regime accessible only in low Reynolds number systems such as bacteria, polar-ordered suspensions are invariably convectively unstable. (iv) The variance in the number N of particles, divided by the mean , diverges as (2/3 ) in polar-ordered SPP suspensions.     

A new unusual iridoid with inhibition of activator protein-1 (AP-1) from the leaves of Morinda citrifolia L

[structure in text] From the leaves of Morinda citrifolia, a new unusual iridoid, named citrifolinoside (1), showing significant inhibition of UVB-induced Activator Protein-1 (AP-1) activity in cell cultures, has been isolated. Its structure was elucidated on the basis of detailed high-field 1D and 2D spectral analysis.     

A comparison of preconditioned Krylov subspace methods for large‐scale nonsymmetric linear systems

Preconditioned Krylov subspace (KSP) methods are widely used for solving large‐scale sparse linear systems arising from numerical solutions of partial differential equations (PDEs). These linear systems are often nonsymmetric due to the nature of the PDEs, boundary or jump conditions, or discretization methods. While implementations of preconditioned KSP methods are usually readily available, it is unclear to users which methods are the best for different classes of problems. In this work, we present a comparison of some KSP methods, including GMRES, TFQMR, BiCGSTAB, and QMRCGSTAB, coupled with three classes of preconditioners, namely, Gauss–Seidel, incomplete LU factorization (including ILUT, ILUTP, and multilevel ILU), and algebraic multigrid (including BoomerAMG and ML). Theoretically, we compare the mathematical formulations and operation counts of these methods. Empirically, we compare the convergence and serial performance for a range of benchmark problems from numerical PDEs in two and three dimensions with up to millions of unknowns and also assess the asymptotic complexity of the methods as the number of unknowns increases. Our results show that GMRES tends to deliver better performance when coupled with an effective multigrid preconditioner, but it is less competitive with an ineffective preconditioner due to restarts. BoomerAMG with a proper choice of coarsening and interpolation techniques typically converges faster than ML, but both may fail for ill‐conditioned or saddle‐point problems, whereas multilevel ILU tends to succeed. We also show that right preconditioning is more desirable. This study helps establish some practical guidelines for choosing preconditioned KSP methods and motivates the development of more effective preconditioners.     

Duration differences in the articulation and acoustics of Swiss German word-initial geminate and singleton stops

Stops in Swiss German contrast only in quantity in all word positions; aspiration and voicing play no role. As in most languages with consonant quantity contrast, geminate stops are produced with significantly longer closure duration (CD) than singletons in an intersonorant context. This holds word medially as well as phrase medially, e.g., [oni tto:s] "without roar" versus [oni to:s] "without can." Since the stops are voiceless, no CD cue distinguishes geminates from singletons phrase initially. Nevertheless, do speakers utilize articulatory means to maintain the contrast? By using electropalatography, the articulatory and acoustic properties of word-initial alveolar stops were investigated in phrase-initial and phrase-medial contexts. The results are threefold. First, as expected, CD and contact duration of the articulators mirror each other within a phrase: Geminates are longer than singletons. Second, phrase initially, the contact data unequivocally establish a quantity distinction. This means that-even without acoustic CD cues for perception-geminates are articulated with substantially longer oral closure than singletons. Third, stops are longer in phrase-initial than phrase-medial position, indicating articulatory strengthening. Nevertheless, the difference between geminates and singletons phrase initially is proportionately less than in phrase-medial position.     

Frustration, area law, and interference in quantum spin models

We study frustrated quantum systems from a quantum information perspective. Within this approach, we find that highly frustrated systems do not follow any general "area law" of block entanglement, while weakly frustrated ones have area laws similar to those of nonfrustrated systems away from criticality. To calculate the block entanglement in systems with degenerate ground states, typical in frustrated systems, we define a "cooling" procedure of the ground state manifold and propose a frustration degree and a method to quantify constructive and destructive interference effects of entanglement.