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In living cells, molecular motors create activity that enhances the diffusion of particles throughout the cytoplasm, and not just ones attached to the motors. We demonstrate initial steps toward creating artificial cells that mimic this phenomenon. Our system consists of active, Pt-coated Janus particles and passive tracers confined to emulsion droplets. We track the motion of both the active particles and passive tracers in a hydrogen peroxide solution, which serves as the fuel to drive the motion. We first show that correcting for bulk translational and rotational motion of the droplets induced by bubble formation is necessary to accurately track the particles. After drift correction, we find that the active particles show enhanced diffusion in the interior of the droplets and are not captured by the droplet interface. At the particle and hydrogen peroxide concentrations we use, we observe little coupling between the active and passive particles. We discuss the possible reasons for lack of coupling and describe ways to improve the system to more effectively mimic cytoplasmic activity. [ABSTRACT FROM AUTHOR]

Quantum two-level systems interacting with the surroundings are ubiquitous in nature. The interaction suppresses quantum coherence and forces the system towards a steady state. Such dissipative processes are captured by the paradigmatic spin-boson model, describing a two-state particle, the “spin”, interacting with an environment formed by harmonic oscillators. A fundamental question to date is to what extent intense coherent driving impacts a strongly dissipative system. Here we investigate experimentally and theoretically a superconducting qubit strongly coupled to an electromagnetic environment and subjected to a coherent drive. This setup realizes the driven Ohmic spin-boson model. We show that the drive reinforces environmental suppression of quantum coherence, and that a coherent-toincoherent transition can be achieved by tuning the drive amplitude. An out-of-equilibrium detailed balance relation is demonstrated. These results advance fundamental understanding of open quantum systems and bear potential for the design of entangled light-matter states. [ABSTRACT FROM AUTHOR]

The breakthrough capacity of optoacoustics for three-dimensional visualization of dynamic events in real time has been recently showcased. Yet, efficient spectral unmixing for functional imaging of entire volumetric regions is significantly challenged by motion artifacts in concurrent acquisitions at multiple wavelengths. Here, we introduce a method for simultaneous acquisition of multispectral volumetric datasets by introducing a microsecond-level delay between excitation laser pulses at different wavelengths. Robust performance is demonstrated by real-time volumetric visualization of functional blood parametrers in human vasculature with a handheld matrix array optoacoustic probe. This approach can avert image artifacts imposed by velocities greater than 2 m/s, thus, does not only facilitate imaging influenced by respiratory, cardiac or other intrinsic fast movements in living tissues, but can achieve artifact-free imaging in the presence of more significant motion, e.g. abrupt displacements during handheld-mode operation in a clinical environment. [ABSTRACT FROM AUTHOR]

Rationale: Prepulse inhibition (PPI) of the acoustic startle response, a measure of sensorimotor gating, can be enhanced by nicotine. Moreover, the TT genotype of the nicotinic acetylcholine receptor (nAChR) α3-subunit ( CHRNA3) rs1051730 polymorphism has previously been associated with diminished PPI and nicotine dependence. Objectives: We tested whether this CHRNA3 polymorphism also modulates the nicotine-induced enhancement of PPI. Methods: We assessed the effect of nicotine on PPI, startle reactivity, and habituation in 52 healthy nonsmoking volunteers genotyped for CHRNA3 rs1051730 in a double-blind, placebo-controlled, counterbalanced, within-subjects design. Additionally, cotinine plasma levels were measured. Results: Nicotine significantly enhanced PPI in TT homozygotes only and tended to worsen PPI in TC and CC carriers. Additionally, nicotine significantly reduced startle habituation. Conclusions: The present findings imply that the effect of nicotine on sensorimotor gating is modulated by nAChR α3-subunits. Thus, genetic variation in nicotinic receptor genes might be an important connecting link between early attentional processes and smoking behavior. [ABSTRACT FROM AUTHOR]

Acoustical spectroscopy at frequencies up to 10 GHz gives the possibility of the investigation of liquid substances, where the relaxation process observed is caused by energy transfer between translational and vibrational degrees of freedom. The compounds presented in this article belong to this group of liquids. The acoustic investigations in the group of benzene derivatives, particularly research of the dependencies of acoustic parameters and the structure of organic liquids, demonstrated some interesting regularities in the group of these compounds in gas and liquid states. In this article, the results of research on five cyclic liquids: bromo-, chloro-, fluoro-, iodo-, and nitrobenzene as well as toluene and aniline are discussed and compared to benzene. The acoustic relaxation observed in all these compounds was found to result from Kneser's processes (vibrational relaxation). Based on investigations reported in this article, as well as by other authors, and taking into account experimental and literature data concerning a great number of compounds, one can draw a conclusion that almost all acoustic relaxation (Kneser-type) processes in liquids can be described using a single relaxation time. It also seems that all vibrational degrees of freedom of the molecule take part in this process. It is known that the appearance of differences in transition probabilities could be caused by additional attraction in interactions of molecules having dipole moments. Halogen derivatives have higher values of dipole moments than benzene. This difference could be responsible for the difference of transition probabilities and changes in the relaxation times. However, benzene derivatives with amino, nitro, and methyl groups and halides show the other type of relaxation. [ABSTRACT FROM AUTHOR]

The formation of structured films consisting of ensembles of micro- or nanoparticles and possessing preset functional characteristics is studied both experimentally and theoretically. The films are obtained by drying out droplets of colloidal solutions on a solid substrate under the acoustic effect produced by a standing SAW field. [ABSTRACT FROM AUTHOR]

Time-resolved photoacoustic calorimetry (PAC) allows the measurement of lifetimes and energy fractions of molecular nonradiative deactivation processes, as well as structural volume changes associated with such processes. The photoinduced acoustic wave generated by a given photochemical sample, E(t), is the result of the convolution between the heat function H(t), describing the kinetics of the photochemical processes in the sample, and the instrument response given by a calorimetric reference wave, T(t). A relatively simple mathematical description of the T(t) wave parametrized by the rise time, frequencies and damping time of the transducer is presented for transducers of distinct frequencies. This description allows for a non-restrictive analytical solution of the convolution of the T(t) wave with the heat function. Comparison of the analytical solution with the experimental wave E(t) allows the determination of the fractions of excitation energy and lifetimes of the intermediate species. Published photochemical systems with two and three sequential decaying processes were analyzed to validate the efficacy of this method. This new method of analysis, and a software application that simulates E(t), allows a better understanding of the underlying physics through their phenomenological description. [ABSTRACT FROM AUTHOR]

The article discusses the result of the study which determines the impact of argon addition on the dissociation of oxygen molecules in a direct current glow discharge. Preparation of the plasma-generating gas was done by mixing the volumes of argon and oxygen with a purity of 99.9%. Experimental data revealed that an increase in the inert gas content in plasma causes a monotonic growth of the degree of dissociation of oxygen molecules in a discharge current.

Three to four billion pounds of chicken feathers are wasted in the United States annually. These feathers pose an environmental challenge. In order to find a commercial application of these otherwise wasted feathers, composites have been prepared from feathers. Flexural, impact resistance, and sound dampening properties of composites from chicken feather fiber (FF) and High Density Polyethylene/Polypropylene (HDPE/PP) fiber have been investigated and compared with pulverized chicken quill-HDPE/PP, and jute-HDPE/PP composites. Sound dampening by FF composites was 125% higher than jute and similar to quill although mechanical properties were inferior to the latter two. In ground form, FF and jute composite properties were similar except for 34% higher modulus of jute; under the same formulation and processing conditions, ground FF composites had nearly 50% lower mechanical properties compared with ground quill composites. It was found that voids and density of composites have effect on mechanical and sound dampening properties; however, no direct relationship was found between mechanical properties and sound dampening. [ABSTRACT FROM AUTHOR]

The structural, electrical, and magnetic properties of thin R-Fe-Ge (R = Y, La, Sc) films have been studied in relation to preparation conditions (annealing temperature and the action of an external electric field on molecular vapor), film thickness, and the size of the crystallites formed in the amorphous matrix. The resistivity and coercivity of the films have been measured at temperatures from 77 to 500 K,. The results are of practical interest because the films are potentially attractive as soft-magnetic nanocrystalline materials. [ABSTRACT FROM AUTHOR]

Abstract  Effect of weak periodic electromagnetically excited acoustic pulses with a repetition frequency of 100 to 1000 kHz on thermolysis of petroleum residue was studied. It was shown that weak acoustic fields affect the yield and quality of target products (gas, liquid, solid cracking residue). [ABSTRACT FROM AUTHOR]

The term ‘molecular magnet’ generally refers to a molecular entity containing several magnetic ions whose coupled spins generate a collective spin, S (ref. 1). Such complex multi-spin systems provide attractive targets for the study of quantum effects at the mesoscopic scale. In these molecules, the large energy barriers between collective spin states can be crossed by thermal activation or quantum tunnelling, depending on the temperature or an applied magnetic field. There is the hope that these mesoscopic spin states can be harnessed for the realization of quantum bits—‘qubits’, the basic building blocks of a quantum computer—based on molecular magnets. But strong decoherence must be overcome if the envisaged applications are to become practical. Here we report the observation and analysis of Rabi oscillations (quantum oscillations resulting from the coherent absorption and emission of photons driven by an electromagnetic wave) of a molecular magnet in a hybrid system, in which discrete and well-separated magnetic clusters are embedded in a self-organized non-magnetic environment. Each cluster contains 15 antiferromagnetically coupled S = 1/2 spins, leading to an S = 1/2 collective ground state. When this system is placed into a resonant cavity, the microwave field induces oscillatory transitions between the ground and excited collective spin states, indicative of long-lived quantum coherence. The present observation of quantum oscillations suggests that low-dimension self-organized qubit networks having coherence times of the order of 100 μs (at liquid helium temperatures) are a realistic prospect. [ABSTRACT FROM AUTHOR]

The growth and dissolution of the isolated (100) face of a KDP crystal at exposure of the phase boundary to focused acoustic fields have been investigated. Visualization tools have been developed and the scale and dynamics of the arising acoustic flows have been established. A quadratic dependence of the dissolution rate on the sound pressure has been obtained; such a dependence is in agreement with the theoretical concepts about the dependence of the mass exchange rate in the acoustic boundary layer on the field parameters. A significant growth response of the face under study, normally exposed to ultrasound along the acoustic axis in the prefocal and postfocal planes of a spherical concentrator ( f = 1.4 MHz), has been revealed. It is shown that the mechanisms of mass exchange enhancement in these acoustic modes are radically different. The results obtained show a possibility of controlling growth and dissolution of crystals by varying the parameters of an inhomogeneous acoustic field. [ABSTRACT FROM AUTHOR]

Coherent anti-Stokes Raman scattering (CARS) with femtosecond laser pulses has become a widespread method in nonlinear optical spectroscopy and microscopy. As a third-order nonlinear process, femtosecond CARS exhibits high efficiency at low average laser power. High sensitivity to molecular structure enables detection of small quantities of complex molecules and non-invasive biological imaging. Temporal and spectral resolution of CARS is typically limited by the duration of the excitation pulses and their frequency bandwidth, respectively. Broadband femtosecond pulses are advantageous for time-resolved CARS spectroscopy, but offer poor spectral resolution. The latter can be improved by invoking optical or quantum interference at the expense of increasing complexity of instrumentation and susceptibility to noise. Here, we present a new approach to coherent Raman spectroscopy in which high resolution is achieved by means of deliberately introduced noise. The proposed method combines the efficiency of a coherent process with the robustness of incoherent light. It does require averaging over different noise realizations, but no temporal scanning or spectral pulse shaping as commonly used by frequency-resolved spectroscopic methods with ultrashort pulses. [ABSTRACT FROM AUTHOR]

Bond distances, vibrational frequencies, electron affinities, ionization potentials and dissociation energies of the title molecules in neutral, positively and negatively charged ions were studied by use of density functional method. The calculated results were compared with previous theoretical and experimental studies. Ground states for each molecule were assigned. It was found that for some molecules, low-lying state, in which the energy is much close to the ground state, was obtained. In this case, further studies both experimentally and theoretically are necessary in order to find the true global minimum. [ABSTRACT FROM AUTHOR]

The method of Rutherford backscattering spectrometry in combination with channeling is used to study the accumulation of structural defects in silicon at room temperature as a result of irradiation with P+ and F+ atomic ions and also with cluster PF ions ( n = 1, ..., 4) with the energy of 2.1 keV/amu and with identical generation rate of primary defects. The conditions for correct comparison of the results of bombardment with atomic and cluster ions composed of atoms of various types are suggested. It is found that the characteristics of accumulation of structural defects in silicon in the case of bombardment with PF cluster ions differ widely from those under irradiation with both atomic ions that are involved in the cluster ion (P+ and F+) and with atomic heavy ions that have atomic mass close to that of the mass of a PF cluster. It is shown that, with irradiation conditions being the same, cluster ions produce much more radiation defects in the surface region than do atomic ions; i.e., a molecular effect is observed. Plausible mechanisms of this phenomenon are considered. [ABSTRACT FROM AUTHOR]

Specific features of molecules’ pyrolysis in the case of growth of Si1 − x Ge x films from hydrides in vacuum are considered in the context of kinetic approximation on the basis of a growth experiment. The type of solution characteristic of the kinetic problem was studied in relation to the values of the system’s parameters for a scheme of decomposition of monohydrides of Si and Ge with a dominant role of SiH2 and GeH2 radicals in the pyrolysis process. It is shown for the first time that, in the system under consideration, there can exist at least two types of solutions that differ radically from each other in the rate of incorporations of atoms into the growing layer and in the degree of filling of the surface states with products of molecules’ pyrolysis. The type of solution characteristic of the actual experiment is determined from the condition for the segregation-related accumulation of Ge atoms at the growth surface of the Si1 − x Ge x film. Numerical analysis performed in relation to the growth temperature made it possible to estimate the rate of the monohydrides’ decomposition and the values of the factor of incorporation of Si and Ge adatoms into the crystal. The estimate of the characteristic decomposition time for monosilane yields the value of 3–4 s at the growth temperatures of 450–700°C; for monogermane, this value is about 2 s. [ABSTRACT FROM AUTHOR]

The results of numerical simulation of electrical characteristics of silicon-on-insulator MOSFET nanotransistors with two independent gates are reported. The cases of grounded and floating bases with the surface recombination of charge carriers either disregarded or taken into account are considered. It is shown that, at specified design parameters (gate length 50–100 nm, thickness of silicon layer 25–50 nm), one can vary the transistor’s threshold voltage by 0.45 V, reduce the transistor current in the off state by seven orders of magnitude, and decrease the subthreshold slope of the gate characteristics to 60 mV/decade by varying the voltage applied to the second gate. Suppression of the short-channel effects in the transistors under consideration depends on a number of parameters (listed in order of decreasing effect): the gate material, the lifetime of charge carriers (for floating or grounded base), the thickness of the top silicon layer, the voltage applied to the additional gate, and the channel length. [ABSTRACT FROM AUTHOR]

The surface morphology and optical properties of the (In,Ga)As/GaAs(100) multilayer structures with self-organized quantum dots and quantum wires, which were grown by molecular-beam epitaxy, are investigated. It is found that the ordered arrangement of quantum dots in the heterointerface plane starts to form during the growth of the first periods of the multilayer structure. As the number of periods increases, quantum dots line up in series and form wires along the $$[0\bar 11]$$ direction. An increase in the lateral ordering of the structures under consideration correlates with an increase in the optical emission anisotropy governed by relaxation anisotropy of elastic strains and by the shape of nano-objects. A possible mechanism of lateral ordering of quantum dots and wires in multilayer structures, which includes both anisotropy effects of the strain fields and adatom diffusion, as well as the elastic interaction of neighboring quantum dots, is discussed. [ABSTRACT FROM AUTHOR]

Second-harmonic generation in a double-quantum-well nanostructure is analyzed. Optimization of the structure design from the viewpoint of attaining the highest intensity of the second-harmonic wave at the output is considered. Relationships between the quantum-well parameters in a structure satisfying the double-resonance condition are established. The dependence of the optical characteristics of the system on the quantum-well parameters is studied and the problem of optimization of the second-harmonic intensity is solved. It is demonstrated that the highest conversion efficiency is attained under the conditions where the second-harmonic generation coefficient is maximum. [ABSTRACT FROM AUTHOR]

The method of the charge-density functional in the tight-binding approximation is used to study the effect of different types of wall atomic defects in the MoS2 nanotubes on their structural and electronic properties. It is shown that the atomic defects in the walls of the MoS2 nanotubes can be responsible for the semiconductor-metal transitions. [ABSTRACT FROM AUTHOR]

The establishment of stationary solution concentration in a growing or evaporating droplet of an ideal binary solution (binary droplet) placed in a vapor mixture of constituting substances and passive gas is described analytically. Relations defining time dependences of solution concentration in a droplet, the number of molecules of each constituting component, and droplet radius are derived at known parameters of the vapor-gas mixture and the initial composition of a binary droplet. The results of calculations of time dependences of aforementioned values are reported for several variants of the initial composition of a droplet and a vapor mixture. [ABSTRACT FROM AUTHOR]

The architecture and operation of a trace hydrogen cyanide (HCN) gas sensor based on quartz-enhanced photoacoustic spectroscopy and using a λ=1.53 μm telecommunication diode laser are described. The influence of humidity content in the analyzed gas on the sensor performance is investigated. A kinetic model describing the vibrational to translational (V–T) energy transfer following the laser excitation of a HCN molecule is developed. Based on this model and the experimental data, the V–T relaxation time of HCN was found to be (1.91±0.07)10-3 s Torr in collisions with N2 molecules and (2.1±0.2)10-6 s Torr in collisions with H2O molecules. The noise-equivalent concentration of HCN in air at normal indoor conditions was determined to be at the 155-ppbv level with a 1-s sensor time constant. [ABSTRACT FROM AUTHOR]

Shapes and energies of icosahedral fullerenes are studied on an atomically detailed level. The numerical results based on the effective binary carbon-carbon potential are related to the theory of elasticity of crystalline membranes with disclinations. Depending on fullerene size, three regimes are clearly identified, each of them characterized by different geometrical properties of the fullerene shape. For extremely large fullerenes (more than about 500 000 atoms), transition of fullerene shapes to their asymptotic limit is detected, in agreement with previous predictions based on generic elastic description of icosahedral shells. Quantum effects related to delocalized electrons on the fullerene surface are discussed and a simple model introduced to study such effects suggests that the transition survives even in more general circumstances. [ABSTRACT FROM AUTHOR]

The dynamics of a two-dimensional N-bubble static cloud is investigated and shown to be well described by an N-degree of freedom harmonic oscillator model, at least at low enough frequencies. Eigenmodes and eigenfrequencies are calculated and compared with experimental results obtained with an assembly of bubbles caught up under a net in a water tank. Accordance is found to be excellent in the frequency range of validity of the model, the limits of which are discussed. An interpretation of the low-frequency branch of Foldy’s dispersion relation in bubbly liquids is suggested in terms of “bubble waves” in a quasi-incompressible medium. [ABSTRACT FROM AUTHOR]

Biological networks, such as cellular metabolic pathways or networks of corticocortical connections in the brain, are intricately organized, yet remarkably robust toward structural damage. Whereas many studies have investigated specific aspects of robustness, such as molecular mechanisms of repair, this article focuses more generally on how local structural features in networks may give rise to their global stability. In many networks the failure of single connections may be more likely than the extinction of entire nodes, yet no analysis of edge importance (edge vulnerability) has been provided so far for biological networks. We tested several measures for identifying vulnerable edges and compared their prediction performance in biological and artificial networks. Among the tested measures, edge frequency in all shortest paths of a network yielded a particularly high correlation with vulnerability and identified intercluster connections in biological but not in random and scale-free benchmark networks. We discuss different local and global network patterns and the edge vulnerability resulting from them. [ABSTRACT FROM AUTHOR]

A shift of the band envelope of liquid water stretching vibrations in the field of an ultrasonic acoustic pulse is experimentally observed; this shift is indicative of modification of the water cluster structure in the acoustic field. Simple evaluations show that the observed shift can be caused by a change in the average distance between oxygen atoms in a molecular cluster by about 0.05 Å. [ABSTRACT FROM AUTHOR]

The surface tensions σ of nonaqueous solutions of n-propyl acetate in caprylic ( n-octanoic) acid were measured between 273 and 303 K using the Wilhelmy plate method. Complicated concentration dependences were obtained, different from any previously reported. In addition, independent volumetric and acoustic (sound velocity and absorption) methods were applied. The results are interpreted in terms of formation of weak complexes in the bulk as well as at the surface. [ABSTRACT FROM AUTHOR]

Expressions for calculating the directional characteristics of an array of sound receivers positioned in a waveguide with impedance walls are obtained from the solution to the problem on the diffraction of a plane sound wave by the waveguide open end with impedance flanges. The waveguide can be of a finite length, and, in this case, it can be considered as an open cavity in an impedance screen. The solution of the integral equation for the sound pressure distribution over the opening area is reduced to the solution of an infinite system of algebraic equations for the coefficients of the field expansion in normal waveguide waves. Examples of calculated directional characteristics are presented for arrays with receivers positioned at different distances from the opening and for different values of the impedances of the waveguide walls and flanges. [ABSTRACT FROM AUTHOR]

It is shown that for acoustic waves in crystals nonlinear phenomena of a new type, analogous to some degree to Fermi resonance in molecules, can occur. It is demonstrated on the basis of an analysis of the numerical solution of the equations of motion that for propagation of waves with different polarization and with sound velocities in integral ratio, the energy transfer from one wave to another is of the nature of beats with quite low amplitudes and can become chaotic as the amplitudes increase. © 1999 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An expression for the Grüneisen constants of solids is obtained involving only the velocities of propagation of the elastic waves. The new relation is applied for determining the Grüneisen constants of metals, ionic crystals, and ionic-molecular crystals. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Focuses on reports presented at the Saint Petersburg workshop on computational and theoretical acoustics of the Scientific Council on Acoustics of the Russian Academy of Sciences. I.V. Andronov's reports on wave propagation along a narrow crack in an elastic plate in contact with an acoustic medium; A.V. Aref'ev study on the propagation of waves of different origin in smoothly inhomogeneous stratified media.

A study is made of the laws of variation of the acoustic properties of TiNi-based alloys depending on the alloy composition and the temperature. It is demonstrated that, in the temperature range of existence of the B2 phase and the possible strain-induced martensite formation, the vibrations of TiNiMoFe differ from those of conventional materials. Upon excitation of spontaneous vibrations in the M[sub f]≤T≤M[sub d] range, there appears a region of long-term, small-amplitude low-frequency sound vibrations. It is found that free low-frequency vibrations of a sample of TN-10 alloy [1] are characterized by a low level of decrement in the above-indicated temperature range. [ABSTRACT FROM AUTHOR]

The article offers information about an experiment which focuses on fundamentals of quantum mechanics and the rule-of-thumb in electrical engineering. It reveals that single electron in quantum dots can be disturbed by the apparatus which are used to measure them. Also, acoustic interference could negate deleterious effects and bring quantum dots closer to becoming a robust quantum technology.

The article discusses various papers published within the issue which were presented during the 15th Workshop on Photoacoustics and Thermal Wave Methods and the 6th Workshop on Molecular Acoustics, Relaxation and Calorimetric Methods held in Szczyrk, Poland from March 1 to 3, 2010.

Describes the characteristic of the thermoacoustically driven pulse tube refrigerator (TADPTR). Advantage of the system's application; Method used to analyzed the operation and performance of the refrigerator; Composition of the TADPTR.

The article discusses the properties and characteristics of the AI-2 autoinducer. The precursor 4,5-dihydroxy-2,3-pentanedione (DPD) produce AI-2 molecules. The biochemical analysis of the dynamics of the AI-2 was observed using thin-layer chromatography (TLC), mass spectroscopy (MS), and nuclear magnetic resonance.