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By using the reductive perturbation method, the existence of dust acoustic shock waves is given for a dusty plasma considering the dust size distribution. The effects of both the dust size distribution and the dust charge variation on the characteristics of the shock wave are discussed. It is shown that the amplitude of a shock wave in plasmas considering a dust size distribution is larger than that in the case of a mono-sized dusty plasma, while its width considering the dust size distribution is smaller than that of the mono-sized dusty plasma. The speed of the shock waves also depends on different dust size distributions.

The propagation of dust-acoustic waves in a dusty plasma bounded in finite symmetrical cylindrical geometry has been theoretically investigated. By using the reductive perturbation method, we obtain a quasi-nonlinear Schrodinger equation. It is shown that there is a dark envelope soliton under certain conditions, while its amplitude will decrease with the time. The dependence of both the dispersion relation and group velocity of envelope solitary waves on the radius of cylinder has been given. Moreover, we define the duration time of dark envelope solitons and give the theoretical ones. It is found that the duration time increases as the radius of cylinder increases, while it decreases as the viscosity coefficient of dusty plasmas increases.

By using a Korteweg-deVries-Burgers(KdV-Burgers) equation and considering the dust size distribution, we have studied effects of the dust size distribution on the shock wave in dusty plasma. The dependence of characteristics of the shock wave on different dust size distributions has been given. It is found that the speed and amplitude of a shock wave considering the dust size distribution are larger than that of the dusty plasma with the averaged dust size. However, the width of a shock wave considering the dust size distribution is smaller than that of the dusty plasma with the averaged dust size.

The ergot alkaloids are a class of natural products known for their pharmacologically privileged molecular structure that are used in the treatment of neurological ailments, such as Parkinsonism and dementia. Their synthesis via chemical and biological routes are therefore of industrial relevance, but suffer from several challenges. Current chemical synthesis methods involve long, multi-step reactions with harsh conditions and are not enantioselective; biological methods utilizing ergot fungi, produce an assortment of products that complicate product recovery, and are susceptible to strain degradation. Reconstituting the ergot alkaloid pathway in a strain strongly amenable for liquid fermentation, could potentially resolve these issues. In this work, we report the production of the main ergoline therapeutic precursor, D-lysergic acid, to a titre of 1.7 mg L−1 in a 1 L bioreactor. Our work demonstrates the proof-of-concept for the biological production of ergoline-derived compounds from sugar in an engineered yeast chassis.

High-quality superconducting Ca1−x Na x Fe2As2 single crystals have been successfully grown by the NaAs-flux method, with sodium doping level x = 0.4–0.64. The typical sizes of these crystals are more than 10 mm in ab-plane and ∼ 0.1 mm along c-axis in thickness. X-ray diffraction, resistance and magnetization measurements are carried out to characterize the quality of these crystals. While no signature of magnetic phase transitions is detected in the normal state, bulk superconductivity is found for these samples, with a sharp transition at T c ranging from 19.8 K (x = 0.4) to 34.8 K (x = 0.64). The doping dependences of the c-axis parameter and T c are consistent with previous reports, suggesting a possible connection between the lattice parameters and superconductivity.

Present paper studies the contribution of both the quantum effect and the dust size distribution effect on the shock wave characters. It is concluded that the quantum effect of dust particles is negligible, while the quantum effects of both electrons and ions on the shock wave of a quantum dusty plasma cannot be neglected in certain cases. It is found that the speed and the amplitude of the shock wave, considering the dust size distribution, are larger than that of the quantum dusty plasma with the average dust size of a monosized dust plasma. Furthermore, the speed and the amplitude of the shock wave increase, while the width of the shock wave decreases as the ratios of the maximum dust size to the minimum one increases. The quantum effects may affect both the amplitude and width of the shock wave, while it has no effect on the shock wave speed. The width of the shock wave increases, while its amplitude decreases as $$H_e$$ and $$H_i$$ increase.

Incident wave reflection and transmission caused by the impurity in one-dimensional bead chain are studied. As the number of impurities increases, the energy of the transmitted and reflected waves oscillates periodically. When the number of impurities is so large that its length is greater than the width of the incident wave, the transmission and reflection remain constant. In this paper, the dependence of the energy of transmitted and reflected waves on the number of impurity particles in each segment is studied. It is noted that both the reflection and the transmission depend not only on the numbers and the permutation of the impurity but also on the parameters of the incident wave. This behavior can be used to detect the impurities in the bead chain by measuring the reflection of an incident wave.

Theoretical investigations are carried out for the cylindrical and spherical dust-ion acoustic solitary waves with the kinematic viscosity. By the reductive perturbation technique the damped KdV-Burgers equation is obtained, and an approximate analytical solution is given. Using this solution, the effects of different physical parameters on dust-ion acoustic solitary wave are discussed. The results may have applications in laboratory and space plasmas.

We use ultrafast optical spectroscopy to study the nonequilibrium quasiparticle relaxation dynamics of the iron-based superconductor KCa$_2$Fe$_4$As$_4$F$_2$ with $T_c=33.5$ K. Our results reveal a possible pseudogap ($\Delta_{PG}$ = 2.4 $\pm$ 0.1 meV) below $T^*\approx 50$ K but prior to the opening of a superconducting gap ($\Delta_{SC}$(0) $\approx$ 4.3 $\pm$ 0.1 meV). Measurements under high pump fluence real two distinct, coherent phonon oscillations with 1.95 and 5.51 THz frequencies, respectively. The high-frequency $A_{1g}$(2) mode corresponds to the $c-$axis polarized vibrations of FeAs planes with a nominal electron-phonon coupling constant $\lambda_{A_{1g}(2)}$ = 0.194 $\pm$ 0.02. Our findings suggest that the pseudogap is likely a precursor of superconductivity, and the electron-phonon coupling may play an essential role in the superconducting pairing in KCa$_2$Fe$_4$As$_4$F$_2$., Comment: 6 pages, 3 figure

Theoretical investigations are carried out for the properties of small amplitude dust-acoustic solitary waves in plasmas consisting of extremely massive, high negatively charged inertial dust grains, Boltzmann distributed electrons and trapped ions, for one-dimensional case and three-dimensional case. An energy integral equation involving the Sagdeev potential is derived. The dependence of the critical Mach number corresponding to maximum amplitude on other parameters is obtained. It is observed that the magnitude of the external magnetic field has no effect on the amplitude of the solitary waves.

First principles calculations have been performed to investigate the synergetic effect of H and He impurities with vacancies in Ti3AlC2. The configurations and energetics of Hn–He–VAl complexes (n ≤ 4) and He–He/He–H/H–H interactions have been studied. It is found that the impurity H atom prefers to occupy the tetrahedral interstitial site (Itetr-3), but the He atom prefers to occupy the octahedral interstitial site (Ioct-4) in perfect Ti3AlC2. Within a pre-existing Al vacancy, the most favorable site for a He atom is close to tetr-site, meanwhile the H atom preferentially deviates from the vacancy center with the separation 1.3 A along the 〈001〉 direction. He–H and He–He show a weakly attractive interaction, but weak repulsion occurs in the H–H interaction, which is different from the case of Ti3SiC2. The He–VAl complex plays an important role in the trapping of H atoms. The He–VAl cluster can trap up to three H atoms in the absence of H2 molecules, which leads to the formation of a H–He hybridized bubble. Thus, the He atom can subsequently suppress further aggregation of H atoms and block hydrogen embrittlement and volume swelling.

Amino group surface tailored multi-wall carbon nano-tubes were covalently tethered to the gold disk electrode and Laccase molecules were covalently coupled to nano-tubes to prepare Lac-based electrode. Derivative of 3-ferrocenyl dihydropyrazole (FDPFFP) was proposed to be electron mediator for mediated oxygen reduction reaction. Investigation in electro-chemical behavior and catalytic performance to enzymatic reaction of FDPFFP indicated that it displayed quasi-reversible characteristics of electro-chemical reaction with rapid dynamics of electron shuttle and had apparent catalytic effect in oxygen reduction (onset potential for catalysis at 450 mV vs NHE). This enzymatic catalysis was restrained by the step in diffusion of substrate.

This work investigates the envelope solitary wave (ESW) in magnetized power law distribution dusty plasma consisting of free electrons and nonthermal ions. A (3+1)-dimensional nonlinear Schr $$\ddot{o}$$ dinger equation (NLSE) through the reductive perturbation technique is derived. The nonlinear dispersion relation $$\omega =\omega (k )$$ and coefficients of NLSE are analyzed in detail by the numerical simulation method under the effect of nonthermal ions. It is indicated that the frequency increases as the number density of nonthermal ions increase. It can be seen that the frequency with higher unperturbed ion number density is larger than that with lower case. Moreover, the effects of amplitude and width on ESW are discussed with different plasma parameters. The present results can be important in understanding the characteristics of ESW for a magnetized three component plasma system.

The propagation of q -Gaussian laser beam in a preformed plasma channel is investigated by means of the variational method. A differential equation for the spot size has been obtained by including the effects of relativistic self-focusing, ponderomotive self-channeling and preformed channel focusing. The propagation behaviors and their corresponding physical conditions are identified. The comparison of the propagation between q -Gaussian and Gaussian laser beams is done by theoretical and numerical analysis. It is shown that, in the same channel, the focusing power of q -Gaussian laser beam is lower than that of Gaussian laser beam, i.e., the q -Gaussian laser beam is easier to focus than Gaussian laser beam.

The effects of both the ac and the dc external driving forces on the production of screw dislocations are studied by employing the two-dimensional Frenkel–Kontorova model. The ac force is introduced in the model as a way to describe external periodic disturbances or artificial periodic forces. We find that the appearance of the screw dislocation is influenced by the frequency and amplitude of the ac force. It is shown that the screw dislocation can be easily produced by either the lower frequency or the larger amplitude of the ac force.

Enzymatic electrodes over-coated by thin film of nano-composite made up of polymer and functionalized nano-gold particle was prepared. Glucose/O2 membrane-free enzymatic fuel cell based on nano-composite based electrodes with incorporated glucose oxidase and laccase was assembled. This enzymatic fuel cell exhibited high energy out-put density even when applied in human serum. Catalytic cycle involved in enzymatic fuel cell was limited by oxidation of glucose occurred on bioanode resulting from impact of sophisticated interaction between active site in glucose oxidase and nano-gold particle on configuration of redox center of enzyme molecule which crippled catalytic efficiency of redox protein.

Biofoundries provide an integrated infrastructure to enable the rapid design,construction, and testing of genetically reprogrammed organisms for biotechnologyapplications and research. Many biofoundries are being built and aGlobal Biofoundry Alliance has recently been established to coordinate activitiesworldwide.

An overdamped three-layer model with incommensurate structure consisting of two harmonic chains which both move over the substrate potential is studied in the presence of an external (Formula presented.) driving force. The force is applied only on the upper harmonic chain, and dynamics of the middle layer is examined. The results show that the dynamical mode-locking appears not only in the upper layer but also in the middle one. The behavior of the middle layer is strongly determined by the amplitude and frequency of the ac force, and the phase diagram which presents pinned, dynamical mode-locking and sliding regimes as a function of system parameters are given. Contrary to the standard case, critical depinning force and steps exhibit anomalous behavior. Particles trajectories have been analyzed which showed very different motion of particles from the one which usually appears in systems under (Formula presented.) forces.

A multi-ion dusty plasma containing hot isothermal electrons, ions (both positive and negative ones), extremely and negatively charged dust grains and its corresponding dust negative ion acoustic waves are studied by using the reductive perturbation method in this paper. It is noted that they can be determined by parameters of the dust size distribution and the number densities of the ion and electrons.

Transportation of charges, mass and heat of dust particles in a weakly ionized plasma is studied in the present paper. The dependence of electric conductivity, diffusion coefficient and heat conduction coefficient of dust particles on total number density and temperature of dust particles, number density and mass of neutrals, as well as collision cross section area between dust particles and neutrals are given. Effects of dust size distribution on electric conductivity, diffusion coefficient and heat conduction coefficient of dust particles have also been investigated. It is noted that they increase as the mean value of radius of dust particles increases. They increase as difference between maximum and minimum values of dust particles increases when density of the small grains is smaller than that of large grains. However, they decrease as difference between maximum and minimum values of dust particles increases when density of the small grains is larger than that of large grains.

We use a chain of harmonically interacting atoms confined between two sinusoidal substrate potentials in which the top substrate is driven by the driving force. This system is closely related to physical situations with confined lubricant films. The dependence of the static friction force on the system parameters such as the equilibrium spacing and the strength is presented. It is found that the better lubricant films are materials with larger interatomic interaction strength, and the lubricant structure is in the certain region.

The finite-amplitude circularly polarized Alfven envelope solitary waves are numerically studied in the present paper. It is verified that the left-hand polarized Alfven envelope solitary wave can ...

A general small amplitude wave equations are proposed for the granular material. It is shown that the wave is localized in a certain region which is in agreement with that found in both the analytical and the simulation results. The localization region depends on the wave frequency and the parameters of the granular material such as the bead radius, the magnitude of the initial prestress, the Young’s modulus and the bead mass. Several examples are given which indicate that the attenuation rate of the wave depend on the permutation of the bead. It also depends on whether the wave is longitudinal or tangential.

The combined effect of the cylindrical boundary and the adiabatic variation in dust charges on the spatiotemporal evolution of the overlapping soliton in a dusty plasma is studied in detail. We derive the mathematical expression of the overlapping soliton and investigate the effect of dust charging and the influence of its adiabatic variation on the evolution process of the soliton structure. Numerical results indicate that the basic properties of the merged pulse are partially similar to the recent experimental results reported for the interaction of planar solitons in strongly coupled dusty plasmas by Harvey et al., Phys. Rev. E 81, 057401 (2010) and Sharma et al. Phys. Rev. E 89, 013110 (2014). Moreover, it is found that the soliton amplitude and the occurrence time of its peak value increase with the increase in Rn and RT, and the increasing rate of the peak amplitude decreases with the increase in Rn and increases with the increase in RT. As time t increases, the overlapping soliton moves to the inside-traveling direction (i.e., r → 0); before reaching the peak amplitude, the merged pulse gradually increases its amplitude and decreases its width and traveling velocity; after reaching the peak amplitude, the soliton gradually decreases its amplitude and increases its width and velocity. It is also noted that when dust charge variation is considered, solitons with bigger values of Rn (or RT) experience longer phase delays. Comparatively speaking, Rn has a more remarkable effect on the physical properties of the overlapping soliton.

By the reductive perturbation method, we investigate the Rogue waves in a fluid-filled elastic tube. Based on a nonlinear Schrodinger equation obtained from a fluid-filled elastic tube, the rouge wave solution in the fluid-filled elastic tube is discussed. The characteristics of a single rouge waveare studied for this system. Then, the effects of the system parameters, such as the wave number k, the parameters \begin{document}$\epsilon$\end{document}, the density of the fluid, the thickness of the elastic tube, the Yang's modulus of the elastic tube, and the radius of the elastic tube on the rouge wave are also investigated. Finally, the model is applied to the blood vessels of both animal and the human to ascertain the effects of the rouge wave in different arteries and vessels. The results of the present study may have potential applications in medical science.

The originally published version of this Article contained errors in Fig. 4 that were introduced during the production process. In panel c, the two uppermost labels ‘IgE spleen’ and ‘IgE BM’ incorrectly read ‘IgG1 spleen’ and ‘IgE1 BM’, respectively. These errors have now been corrected in both the PDF and HTML versions of the Article.

The unique differentiation of IgE cells suggests unconventional mechanisms of IgE memory. IgE germinal centre cells are transient, most IgE cells are plasma cells, and high affinity IgE is produced by the switching of IgG1 cells to IgE. Here we investigate the function of subsets of IgG1 memory B cells in IgE production and find that two subsets of IgG1 memory B cells, CD80+CD73+ and CD80−CD73−, contribute distinctively to the repertoires of high affinity pathogenic IgE and low affinity non-pathogenic IgE. Furthermore, repertoire analysis indicates that high affinity IgE and IgG1 plasma cells differentiate from rare CD80+CD73+ high affinity memory clones without undergoing further mutagenesis. By identifying the cellular origin of high affinity IgE and the clonal selection of high affinity memory B cells into the plasma cell fate, our findings provide fundamental insights into the pathogenesis of allergies, and on the mechanisms of antibody production in memory B cell responses., IgE is an important mediator of protective immunity as well as allergic reaction, but how high affinity IgE antibodies are produced in memory responses is not clear. Here the authors show that IgE can be generated via class-switch recombination in IgG1 memory B cells without additional somatic hypermutation.

Environmental pH is a fundamental signal continuously directing the metabolism and behavior of living cells. Programming the precise cellular response toward environmental pH is, therefore, crucial for engineering cells for increasingly sophisticated functions. Herein, we engineer a set of riboswitch-based pH-sensing genetic devices to enable the control of gene expression according to differential environmental pH. We next develop a digital pH-sensing system to utilize the analogue-sensing behavior of these devices for high-resolution recording of host cell exposure to discrete external pH levels. The application of this digital pH-sensing system is demonstrated in a genetic program that autonomously regulated the evolutionary engineering of host cells for improved tolerance to a broad spectrum of organic acids, a valuable phenotype for metabolic engineering and bioremediation applications., Cells are exposed to shifts in environmental pH, which direct their metabolism and behavior. Here the authors design pH-sensing riboswitches to create a gene expression program, digitalize the system to respond to a narrow pH range and apply it to evolve host cells with improved tolerance to a variety of organic acids.

Transition metal (TM) nanostructures, such as one dimensional (1D) nanowires with/without substrates, usually possess drastically different properties from their bulk counterparts, due to their distinct stacking and electronic confinement. Correspondingly, it is of great importance to establish the dominant driving force in forming 1D single-metal-atom-wires (SMAWs). Here, with first-principles calculations, taking the black phosphorene (BP) monolayer as a prototype 2D substrate, we investigate the energetic and kinetic properties of all the 5d-TM atoms on the 2D substrate to reveal the mechanism of formation of SMAWs. In contrast to other 5d- and 4d-TMs, noble metal elements Pd and Pt are found to prefer to grow along the trough in an atom-by-atom manner, self-assembling into SMAWs with a significant magic growth behavior. This is due to distinct binding energies and diffusion barriers along the trough, i.e., zig-zag direction, as compared to other directions of the BP. The present findings are valuable in the fabrication and modulation of 1D nanostructures which can be anticipated to possess desirable functionalities for potential applications such as in nanocatalysis, nanosensors, and related areas.

The effects of $$s$$ -wave scattering length ( $$a_{sc}$$ ) of superfluid Fermi gas and energy bias ( $$\gamma $$ ) between two wells have been investigated on tunneling of superfluid Fermi gas in double wells. Interesting phenomena are observed and the explanations are given. We find that both the scattering length $$a_{sc}$$ and energy bias $$\gamma $$ affect the quantum transition dramatically. At certain regime, the complete population transfer between two modes can be obtained. However, at other regimes, the quantum transition can be completely blocked. Their dependence on $$a_{sc}$$ and $$\gamma $$ are given in this paper.

The monovacancy formation energies of each element Nb, Ge and C in the MAX phase Nb2GeC are obtained by ab initio calculation in the present paper. It is noted that the vacancy of each element has a slight effect on the hybridization bonding. If there is a vacancy of either Ge or C, the hybridization bonding will be slightly reduced. However, if there is a Nb vacancy, the hybridization bonding will be increased between the d-orbital and p-orbital. In contrast, the vacancies can substantially reduce the conductivity of the MAX phase Nb2GeC. It is also noted that if there is a vacancy of either Ge or C, the hardness of the Nb2GeC decreases, while it is increased if there is a Nb vacancy.

The modulational instability of two-component Bose–Einstein condensates (BECs) under an external parabolic potential is discussed. Based on the trapped two-component Gross–Pitaevskill equations, a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis. It is shown that a modulational unstable time scale exists for trapped two-component BECs. The modulational properties—which are determined by the wave number, external trapping parameter, intra- and inter-species atomic interactions—are modified significantly. The analytical results are confirmed by direct numerical simulation. Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.

By considering the dependence of the viscosity on the relative velocity between adjacent beads, the shock wave structure in a one-dimensional nonlinear granular system is studied in the present pap...

In the adiabatic limit, we study Rosen–Zener transition of superfluid Fermi gas in a double well potential. We find that s-wave scattering length of the system can affect the quantum transition dramatically. At certain regime the complete population transfer between two wells is observed. On the contrary, the quantum transition could be completely blocked in other regime. We have derived analytical expressions for the transition probability. We also find that, in the adiabatic limit, the population difference between two modes always oscillates around its corresponding fixed point during Rosen–Zener transition process. The difference between population imbalance and the corresponding fixed point decreases with the adiabatic condition becomes stronger. The numerical simulation show a power law relation between them. It is verified by the Rosen–Zener transition for superfluid Fermi gas in the limited cases of both deep Bose-Einstein condensate regime and unitarity regime.

A nonlinear Schroodinger equation in one-dimensional bead chain is first obtained and an envelope solitary wave of the system is verified numerically in this system. The reflection and the transmission of an incident envelope solitary wave due to impurities has also been investigated. It is found that the magnitudes of both the reflection and the transmission not only depend on the characters of impurity materials, the wave number, the incident wave amplitude, but also on the impurity number. This can be used to detect the character and the number of the impurity materials in the bead chain by measuring the reflection and the transmission of an incident pulse.

This paper presents a small printed monopole antenna of size 10 × 29 × 0.8 mm3. The proposed antenna consists of a rectangular radiating patch on one side and a rectangular ground metal with an inverted L-shaped ground strip on the other side. With this simple structure, the proposed antenna provides an impedance bandwidth ranging from 3.05 to 5.82 GHz, which covers the wireless USB (WUSB) operation band of 3.1–4.85 GHz. Good radiation performance and low gain variation are also obtained using the proposed antenna. Equipping with the advantages of dimension and performance, the proposed antenna appears as a promising candidate for USB dongle application. The detail of the proposed antenna design and experimental results obtained thereafter are presented and discussed in this article.

By means of the multiple-scale expansion method, the coupled nonlinear Schrodinger equations without an explicit external potential are obtained in two-dimensional geometry for a self-attractive Bose–Einstein condensate composed of different hyperfine states. The modulational instability of two-component condensate is investigated by using a simple technique. Based on the discussion about two typical cases, the explicit expression of the growth rate for a purely growing modulational instability and the optimum stable conditions are given and analysed analytically. The results show that the modulational instability of this two-dimensional system is quite different from that in a one-dimensional system.

We study the Landau?Zener tunneling of a nonlinear two-level system by applying a periodic modulation on its energy bias. We find that the two levels are splitting at the zero points of the zero order Bessel function for high-frequency modulation. Moreover, we obtain the effective coupling constant between two levels at the zero points of the zero order Bessel function by calculating the final tunneling probability at these points. It seems that the effective coupling constant can be regarded as the approximation of the higher order Bessel function at these points. For the low-frequency modulation, we find that the final tunneling probability is a function of the interaction strength. For the weak inter-level coupling case, we find that the final tunneling probability is more disordered as the interaction strength becomes larger.

We study the propagation and interaction of ion-acoustic solitary waves in a simple two-dimensional plasma by using the extended Poincare–Lighthill–Kuo perturbation method. We consider the interaction between two ion-acoustic solitary waves with different propagation directions in such a system, and obtain two Korteweg-de Vries equations for small but finite amplitude solitary waves along both ξ and η trajectories. The effects of the ratio of ion temperature σ, the ratio of heat capacity γ and the colliding angle α. on the amplitude, the width of the new nonlinear wave created by the collision between two solitary waves are studied. The effects of these parameters on both the colliding solitary waves are examined as well. It is found that all the above-mentioned parameters have significant effects on the properties of these nonlinear waves.

A one-dimensional (1D) Frenkel–Kontorova (FK) model is studied numerically in this paper, and two new analytical solutions (a supersonic kink and a nonlinear periodic wave) of the Sine–Gordon (SG) equation (continuum limit approximation of the FK model) are obtained by using the Jacobi elliptic function expansion method. Taking these new solutions as initial conditions for the FK model, we numerically find there exist the supersonic kink and the nonlinear periodic wave in these systems and obtain a lot of interesting and significant results. Moreover, we also investigate the subsonic kink and the breather in these systems and obtain some new feature.

This paper investigates the collision between two nonlinear waves with arbitrary angle in two-dimensional nonlinear lattice. By using the extended Poincare–Lighthill–Kuo perturbation method, it obtains two Korteweg–de Vries equations for nonlinear waves in both the ξ and η directions, respectively, and derives the analytical phase shifts after the collision of two nonlinear waves. Finally, the solution of u(υ) up to O(e3) order is given.