Construction of metronidazole capped in gold nanoparticles against Helicobacter pylori: antimicrobial activity improvement

Introduction:Helicobacter pylori is considered a major agent causing gastritis and peptic ulcer disease. Unfortunately, the occurrence of increasing drug resistance to this bacterium would result in some difficulties in its treatment. Therefore, the application of nanotechnology has been suggested to resolve such problems. Nanoparticles usage in medical research has been expanded in recent years. Among nanometals, gold nanoparticles have exclusive features that can be used in such applications. Using nanotechnology in medical science could help mankind to solve this problem in the future. Aim: Our aim in this research was to investigate the antimicrobial effect of gold nanoparticles on H. pylori strains. Materials and methods: Gold nanoparticles were synthesized by the Turkevich method. Then, their size and dispersion were investigated using spectrophotometry, DLS, and TEM microscopy. Subsequently, the combination of metronidazole and gold nanoparticles was obtained by mixing method, and then the anti-helicobacter effects of the two were evaluated according to CLSI. Results: The highest size of gold nanoparticles was between 12 and 9 nm, and the maximum absorbance was 522 nm; however, in conjugated state, the maximum absorbance was 540 nm, which indicated the accumulation of drug-conjugated nanoparticles in the conjugate state. Some changes indicated the binding of metronidazole to gold nanoparticles. Antimicrobial testing of gold nanoparticles and metronidazole did not affect the Helicobacter pylori. Therefore, the combination of gold nanoparticles and metronidazole had a 17-mm growth inhibition zone. Conclusions: The anti-helicobacter effects of metronidazole significantly increased in conjugation with gold nanoparticles.

Quantized charge fractionalization at quantum Hall Y junctions in the disorder dominated regime

Fractionalization is a phenomenon where an elementary excitation partitions into several pieces. This picture explains non-trivial transport through a junction of one-dimensional edge channels defined by topologically distinct quantum Hall states, for example, a hole-conjugate state at Landau-level filling factor ν = 2/3. Here we employ a time-resolved scheme to identify an elementary fractionalization process; injection of charge q from a non-interaction region into an interacting and scattering region of one-dimensional channels results in the formation of a collective excitation with charge (1−r)q by reflecting fractionalized charge rq. The fractionalization factors, r = 0.34 ± 0.03 for ν = 2/3 and r = 0.49 ± 0.03 for ν = 2, are consistent with the quantized values of 1/3 and 1/2, respectively, which are expected in the disorder dominated regime. The scheme can be used for generating and transporting fractionalized charges with a well-defined time course along a well-defined path.

Point control of a differential-difference system with distributed parameters on the graph

The article considers the problem of point control of the differential-difference equation with distributed parameters on the graph in the class of summable functions. The differential- difference system is closely related to the evolutionary differential system and moreover the properties of the differential system are preserved. This connection is established by the universal method of semi-discretization in a time variable for a differential system, which provides an effective tool in order to find conditions for unique solvability and continuity on the initial data for the differential-difference system. For this differential-difference system, a special case of the optimal control problem is studied: the problem of point control action on the controlled differential-difference system is considered by the control, concentrated at all internal nodes of the graph. At the same time, the restrictive set of permissible controls is set by the means of conditions depending on the nature of the applied tasks. In this case, the controls are concentrated at the end points of the edges adjacent to each inner node of the graph. This is a characteristic feature of the study presented, quite often used in practice when building a mechanism for managing the processes of transportation of different kinds of masses over network media. The study essentially uses the conjugate state of the system and the conjugate system for a differential-difference system — obtained ratios that determine optimal point control. The obtained results underlie the analysis of optimal control problems for differential systems with distributed parameters on the graph, which have interesting analogies with multi-phase problems of multidimensional hydrodynamics.

Constructing de Bruijn Sequences Based on a New Necessary Condition

In this paper, we propose a new necessary condition for feedback functions of de Bruijn sequences and discuss its application in constructing de Bruijn sequences. It is shown that a large number of de Bruijn sequences could be easily constructed by precomputing an [Formula: see text]-stage nonlinear feedback shift register (NFSR) with a special cycle structure—that is, if a state [Formula: see text] is on a cycle generated by this NFSR, then all the states with the same Hamming weight as [Formula: see text] are also on this cycle. Moreover, if there are [Formula: see text] different cycles in the state graph of the precomputed NFSR, then we can construct [Formula: see text] de Bruijn sequences by the different choices of conjugate state pairs, where [Formula: see text].

Bubble and conical forms of vortex breakdown in swirling jets

Experimental investigations of laminar swirling jets had revealed a new form of vortex breakdown, named conical vortex breakdown, in addition to the commonly observed bubble form. The present study explores these breakdown states that develop for the Maxworthy profile (a model of swirling jets) at inflow, from streamwise-invariant initial conditions, with direct numerical simulations. For a constant Reynolds number based on jet radius and a centreline velocity of 200, various flow states were observed as the inflow profile’s swirl parameter $S$ (scaled centreline radial derivative of azimuthal velocity) was varied up to 2. At low swirl ($S=1$) a helical mode of azimuthal wavenumber $m=-2$ (co-winding, counter-rotating mode) was observed. A ‘swelling’ appeared at $S=1.38$, and a steady bubble breakdown at $S=1.4$. On further increase to $S=1.5$, a helical, self-excited global mode ($m=+1$, counter-winding and co-rotating) was observed, originating in the bubble’s wake but with little effect on the bubble itself – a bubble vortex breakdown with a spiral tail. Local and global stability analyses revealed this to arise from a linear instability mechanism, distinct from that for the spiral breakdown which has been studied using Grabowski profile (a model of wing-tip vortices). At still higher swirl ($S=1.55$), a pulsating type of bubble breakdown occurred, followed by conical breakdown at 1.6. The latter consists of a large toroidal vortex confined by a radially expanding conical sheet, and a weaker vortex core downstream. For the highest swirls, the sheet was no longer conical, but curved away from the axis as a wide-open breakdown. The applicability of two classical inviscid theories for vortex breakdown – transition to a conjugate state, and the dominance of negative azimuthal vorticity – was assessed for the conical form. As required by the former, the flow transitioned from a supercritical to subcritical state in the vicinity of the stagnation point. The deviations from the predictions of the latter model were considerable.

Asymptotic expansion of a solution for one singularly perturbed optimal control problem with a convex integral quality index depends on slow variables and smooth control constraints

The paper deals with the problem of optimal control with a convex integral quality index depends on slow variables for a linear steady-state control system with a fast and slow variables in the class of piecewise continuous controls with a smooth control constraints x ε = A 11 x ε + A 12 y ε + B 1 u, εy ε = A 21 x ε + A 22 y ε + B 2 u, J ε u ≔φ x ε T + 0 T u(t) 2 dt→ min, t∈ 0, T , x ε0 = x 0 ,u ≤1, y ε0 = y 0 , where x ε ∈Rn , y ε ∈Rm , u∈Rr ; A ij , B i , i, j =1,2, - are constant matrices of the corresponding dimension, and φ(·) - is the strictly convex and cofinite function that is continuously differentiable in Rn in the sense of convex analysis. In the general case, Pontryagin’s maximum principle is a necessary and sufficient optimum condition for the optimization of a such a problem. The initial vector of the conjugate state l ε is the unique vector, thus determining the optimal control. It is proven that in the case of a finite number of control switching points, the asymptotics of the vector l ε has the character of a power series.

Internal hydraulic jumps in two-layer systems

This paper describes a new model of internal hydraulic jumps in two-layer systems that places no restrictions (such as the Boussinesq approximation) on the densities of the two fluids. The model is based on that of Borden and Meiburg (J. Fluid Mech., vol. 276, 2013, R1) for Boussinesq jumps, and has the appropriate behaviour in various limits (single-layer, small amplitude, Boussinesq, infinite depth). The energy flux loss in each layer across the jump is positive for all realistic jumps, reaching a maximum for the jump with maximum speed. Larger-amplitude jumps are possible, with decreasing energy loss, down to the ‘conjugate state’ of zero energy loss. However, it is argued that such states may be difficult to realise in practice, and if formed, will tend to the jump with maximum speed. The energy loss is mostly in the contracting layer unless the density there is small. The two-layer model is extended to incorporate mixing between the layers within the jump, with mixing based on the Richardson number.

Phase-Conjugate-State Pairs in Entangled States

We consider the probability that a bipartite quantum state contains phase-conjugate-state (PCS) pairs and/or identical-state pairs as signatures of quantum entanglement. While the fraction of the PCS pairs directly indicates the property of a maximally entangled state, the fraction of the identical-state pairs negatively determines antisymmetric entangled states such as singlet states. We also consider the physical limits of these probabilities. This imposes fundamental restrictions on the pair appearance of the states with respect to the local access of the physical system. For continuous-variable system, we investigate similar relations by employing the pairs of phase-conjugate coherent states. We also address the role of the PCS pairs for quantum teleportation in both discrete-variable and continuous-variable systems.