Myo10 tail is crucial for promoting long filopodia.

Filopodia are slender cellular protrusions containing parallel actin bundles involved in environmental sensing and signaling, cell adhesion and migration, and growth cone guidance and extension. Myosin 10 (Myo10), an unconventional actin-based motor protein, was reported to induce filopodial initiation with its motor domain. However, the roles of the multifunctional tail domain of Myo10 in filopodial formation and elongation remain elusive. Herein, we generated several constructs of Myo10-full-length Myo10, Myo10 with a truncated tail (Myo10 HMM), and Myo10 containing four mutations to disrupt its coiled-coil domain (Myo10 CC mutant). We found that the truncation of the tail domain decreased filopodial formation and filopodial length, while four mutations in the coiled-coil domain disrupted the motion of Myo10 toward filopodial tips and the elongation of filopodia. Furthermore, we found that filopodia elongated through multiple elongation cycles, which was supported by the Myo10 tail. These findings suggest that Myo10 tail is crucial for promoting long filopodia.

Lattice relaxation effects on the collective resonance spectra of a finite dipole array.

Dielectric/plasmonic lattice relaxation spectroscopy is theoretically discussed in this work. A lattice relaxation effect generally occurs in nanocrystals, which means that from the bulk phase to the crystal surface, lattice parameters show a gradual shift. Here, lattice relaxation is introduced into finite polarizable point arrays or rod arrays as an adjusting tool, and its effect on lattice resonance extinction spectrum peaks is calculated. DDA (discrete dipole approximation) and FDTD (finite difference time domain) methods are applied. Different from an ideal infinite array, a finite array exhibits a broad, rippled extinction spectral peak. The application of an expanded/contracted lattice relaxation to the finite array can compress the ripple on one shoulder of the peak, as a cost, and the other shoulder of the peak gets more rippled, showing a "ripple transfer" effect. The strategy introduced in this work can contribute to the micro/nano optical measurement, on-chip adjustable optical cavity for OPOs (optical parameter oscillators)/lasers and controlling of fluorescence or hot-electron chemistry.

The simplest Criegee intermediate CH2OO reaction with dimethylamine and trimethylamine: kinetics and atmospheric implications.

We have used the OH laser-induced fluorescence (LIF) method to measure the kinetics of the simplest Criegee intermediate (CH2OO) reacting with two abundant amines in the atmosphere: dimethylamine ((CH3)2NH) and trimethylamine ((CH3)3N). Our experiments were conducted under pseudo-first-order approximation conditions. The rate coefficients we report are (2.15 ± 0.28) × 10-11 cm3 molecule-1 s-1 for (CH3)2NH at 298 K and 10 Torr, and (1.56 ± 0.23) × 10-12 cm3 molecule-1 s-1 for (CH3)3N at 298 K and 25 Torr with Ar as the bath gas. Both reactions exhibit a negative temperature dependence. The activation energy and pre-exponential factors derived from the Arrhenius equation were (-2.03 ± 0.26) kcal mol-1 and (6.89 ± 0.90) × 10-13 cm3 molecule-1 s-1 for (CH3)2NH, and (-1.60 ± 0.24) kcal mol-1 and (1.06 ± 0.16) × 10-13 cm3 molecule-1 s-1 for (CH3)3N. We propose that the electronegativity of the atom in the co-reactant attached to the C atom of CH2OO, in addition to the dissociation energy of the fragile covalent bonds with H atoms (H-X bond), plays an important role in the 1,2-insertion reactions. Under certain circumstances, the title reactions can contribute to the sink of amines and Criegee intermediates and to the formation of secondary organic aerosol (SOA).

Kinetics of the Simplest Criegee Intermediate CH2OO Reaction with tert-Butylamine.

The kinetics of the simplest Criegee intermediate (CH2OO) reaction with tert-butylamine ((CH3)3CNH2) was studied under pseudo-first-order conditions with the OH laser-induced fluorescence (LIF) method at the temperature range of 283-318 K and the pressure range of 5-75 Torr. Our pressure-dependent measurement showed that at 5 Torr─the lowest pressure measured in the current experiment─this reaction was under the high-pressure limit condition. At 298 K, the reaction rate coefficient was measured to be (4.95 ± 0.64) × 10-12 cm3 molecule-1 s-1. The title reaction was observed to be negative temperature-dependent; the activation energy of (-2.82 ± 0.37) kcal mol-1 and the pre-exponential factor of (4.21 ± 0.55) × 10-14 cm3 molecule-1 s-1 were derived from the Arrhenius equation. The rate coefficient of the title reaction is slightly larger than (4.3 ± 0.5) × 10-12 cm3 molecule-1 s-1 of the CH2OO reaction with methylamine; the electron inductive effect and the steric hindrance effect might play a role in contributing to such difference.

High-efficiency, high-repetition-rate cavity-dumped Q-switched Yb:YAG thin-disk laser based on a 72-pass pump module.

We demonstrated a compact cavity-dumped Q-switched Yb:YAG laser based on a 72-pass pump module. A highly stable nanosecond pulse laser with a duration of 18.38 ns was achieved at a repetition rate of 100 kHz, which is pumped by multimode laser diode stacks at 969 nm. The average output power of more than 150 W is delivered in a good output beam characterized by M2 = 1.53. The result shows that the pulse duration derived from simulation agrees well with the one retrieved from the experimental measurements. To the best of our knowledge, the 43.5% optical-optical efficiency is the highest reported to date from a cavity-dumped Q-switched Yb:YAG TDL (thin-disk laser).

Resonators with a continuously variable output coupling rate to enhance output performance of Yb:YAG thin-disk lasers.

Beam quality and average output power are two long-sought parameters of continuous-wave lasers. The operating characteristics of a Yb:YAG thin-disk laser based on a 72-pass pump module using output couplers with continuously variable coupling rates are reported. When the pump power is 450 W, the average power of more than 210 W is obtained, and the corresponding optical-optical efficiency is about 46.67%. The output beam is near diffraction limited with M2=1.20 and 1.18 on the horizontal and vertical directions respectively. The thin-disk laser maintains the beam quality near diffraction limited within the whole pump power range by continuously changing the coupling rate of the output coupler (the combination of thin film polarizer and quarter-wave plate) according to the incident pump power. The experimental results show that by continuously changing the coupling rate, combined with the dynamic change of thermal lens effect, the laser beam quality factor M2 can be reduced from 2.0 to 1.2, and the beam quality can be improved by about 40%. The improvement of and increase of average output power confirm that resonators with continuously variable coupling rate are a promising method for enhancing output performance of thin-disk lasers.

Establishment and evaluation of qPCR and real-time recombinase-aided amplification assays for detection of largemouth bass ranavirus.

Largemouth bass ranavirus disease (LMBVD) caused by largemouth bass ranavirus (LMBV) has resulted in severe economic losses in the largemouth bass (Micropterus salmoides) farming industry in China. Early and accurate diagnosis is the key measure for the prevention and control of LMBVD. In this study, a quantitative polymerase chain reaction (qPCR) and a real-time recombinase-aided amplification (real-time RAA) assay were established for the detection of LMBV. The sensitivity and specificity of these two methods, and the efficacy for detection of LMBV from clinical samples were also evaluated. Results showed that the real-time RAA reaction was completed in <30 min at 39℃ with a detection limit of 58.3 copies, while qPCR reaction required 60 min with a detection limit of 5.8 copies. Both methods were specific for LMBV, where no cross-reactions observed with the other tested fish pathogens. Comparing the amplification results of both assays to the results obtained by virus isolation using 53 clinical tissue samples, results showed that the clinical sensitivity of real-time RAA and qPCR were 93.75% and 100% respectively, and the clinical specificity of both were 100%. Our results showed that qPCR is more suitable for quantitative analysis and accurate detection of LMBV in the laboratory, while real-time RAA is more suitable as a point-of-care diagnostic tool for on-site detection and screening of LMBV under farm conditions and in poorly equipped laboratories.

Simultaneous negative reflection and refraction and reverse-incident right-angle collimation of sound in a solid-fluid phononic crystal.

The square lattice phononic crystal (PnC) has been used extensively to demonstrate metamaterial effects. Here, positive and negative refraction and reflection are observed simultaneously due to the presence of Umklapp scattering of sound at the surface of PnC and square-like equifrequency contours (EFCs). It is found that a shift in the EFC of the third transmission band away from the center of the Brillouin zone results in an effectively inverted EFC. The overlap of the EFC of the second and third band produce quasimomentum-matching conditions that lead to multi-refringence phenomena from a single incident beam without the introduction of defects into the lattice. Additionally, the coupling of a near-normal incident wave to a propagating almost perpendicular Bloch mode is shown to lead to strong right-angle redirection and collimation of the incident acoustic beam. Each effect is demonstrated both numerically and experimentally for scattering of ultrasound at a 10-period PnC slab in water environment.

Potential of bacteriophages as disinfectants to control of Staphylococcus aureus biofilms.

BACKGROUND: Staphylococcus aureus is the causative agent of chronic mastitis, and can form a biofilm that is difficult to completely remove once formed. Disinfectants are effective against S. aureus, but their activity is easily affected by environmental factors and they are corrosive to equipment and chemically toxic to livestock and humans. Therefore, we investigated the potential utility of a bacteriophage as a narrow-spectrum disinfectant against biofilms formed by S. aureus. In this study, we isolated and characterized bacteriophage vB_SauM_SDQ (abbreviated to SDQ) to determine its efficacy in removing S. aureus biofilms. RESULTS: SDQ belongs to the family Myoviridae and consists of a hexagonal head, long neck, and short tail. This phage can sterilize a 109 CFU/mL culture of S. aureus in 12 h and multiply itself 1000-fold in that time. Biofilms formed on polystyrene, milk, and mammary-gland tissue were significantly reduced after SDQ treatment. Fluorescence microscopy and scanning electron microscopy showed that SDQ destroyed the biofilm structure. Moreover, the titer of SDQ remained relatively high after the lysis of the bacteria and the removal of the biofilm, exerting a continuous bacteriostatic effect. SDQ also retained its full activity under conditions that mimic common environments, i.e., in the presence of nonionic detergents, tap water, or organic materials. A nonionic detergent (Triton X-100) enhanced the removal of biofilm by SDQ. CONCLUSIONS: Our results suggest that SDQ, a specific lytic S. aureus phage, can be used to control biofilm infections. SDQ maintains its full activity in the presence of nonionic detergents, tap water, metal chelators, and organic materials, and can be used in combination with detergents. We propose this phage as a narrow-spectrum disinfectant against S. aureus, to augment or supplement the use of broad-spectrum disinfectants in the prevention and control of the mastitis and dairy industry contamination caused by S. aureus.

Ultrasound Imaging by Thermally Tunable Phononic Crystal Lens.

This work demonstrates the detections and mappings of a solid object using a thermally tunable solid-state phononic crystal lens at low frequency for potential use in future long-distance detection. The phononic crystal lens is infiltrated with a polyvinyl alcohol-based poly n-isopropyl acrylamide (PVA-PNIPAm) bulk hydrogel polymer. The hydrogel undergoes a volumetric phase transition due to a temperature change leading to a temperature-dependent sound velocity and density. The temperature variation from 20 °C to 39 °C changes the focal length of the tunable solid-state lens by 1 cm in the axial direction. This thermo-reversible tunable focal length lens was used in a monostatic setup for one- and two-dimensional mapping scans in both frequency domain echo-intensity and temporal domain time-of-flight modes. The experimental results illustrated 1.03 ± 0.15λ and 2.35 ± 0.28λ on the lateral and axial minimum detectable object size. The experiments using the tunable lens demonstrate the capability to detect objects by changing the temperature in water without translating an object, source, or detector. The time-of-flight mode modality using the tunable solid-state phononic lens increases the signal-to-noise ratio compared to a conventional phononic crystal lens.

Propagation of partially coherent four-petal elliptic Gaussian vortex beams in atmospheric turbulence.

The beam spreading and evolution behavior of the intensity profile and coherent vortices of partially coherent, four-petal elliptic Gaussian vortex beams propagating in atmospheric turbulence are studied. The analytical expressions for cross-spectral density function, as well as root mean square (rms) beam width, are derived based on the extended Huygens-Fresnel principle. Results showed that, unlike the partially coherent four-petal Gaussian vortex beams, the partially coherent four-petal elliptic Gaussian vortex beam could change its petal number into six. The dependencies of occurrence, appearance, and transition speed from four- to six-petal profile on the topological charge, the beam order, and the ellipticity factor are illustrated. The far field behaviors of partially coherent four-petal elliptic Gaussian vortex beams propagating in atmospheric turbulence and are compared in free space. Beams with larger topological charge, smaller beam order, and larger ellipticity factor were found to be less influenced by atmospheric turbulence. Further, the ellipticity factor can be used as an additional degree of freedom in controlling the conservation distance of coherence vortices' topological charge.

Energy-Transfer Kinetics for Xe (6p[1/2]0) Atoms in Kr, Ar, Ne, and He.

The kinetic processes for the Xe (6p[1/2]0) atoms in Kr, Ar, Ne, and He buffer gases were studied. We found that Kr, Ar, and Ne atoms can be used to switch the amplified spontaneous emission (ASE) channel from 3408 nm (6p[1/2]0-6s'[1/2]1) to 3680 nm (5d[1/2]1-6p[1/2]1), while Xe and He atoms do not show such a phenomenon. This ASE channel switch is mainly ascribed to the fast transfer of 6p[1/2]0 → 5d[1/2]1. On the basis of the rate equations for two-state coupling (energy-transfer processes between the two states are very rapid), the reason why the ASE channel switch effect normally coincides with a double exponential decay of the spontaneous emission at 828 nm (6p[1/2]0-6s[3/2]1) is explained. The actual situations in Xe, Ar, Ne, and He follow this rule. However, the strictly single exponential decay of the spontaneous emission at 828 nm and strong ASE channel switch effect simultaneously emerge in Kr. This indicates that the transfer of 6p[1/2]0 → 5d[1/2]1 in Kr does not occur via two-state coupling, but via two steps of near-resonance collision through the 5s[3/2]2 (Kr) state as the intermediate state (6p[1/2]0 → 5s[3/2]2 (Kr) → 5d[1/2]1). In addition, we found Xe (6p[1/2]0) atoms strongly tend to reach the 6p[3/2]2, 6p[3/2]1, and 6p[5/2]2 states through the 5s[3/2]2 (Kr) state as the intermediate state in Kr. The 5s[3/2]2 (Kr) state plays a very important role in the energy-transfer kinetics for the Xe (6p[1/2]0) atoms. Kr is probably an excellent buffer gas for laser systems based on Xe.

Method to improve the resolution of a non-parallel Fabry-Perot etalon.

A new method to improve the resolution of a slightly non-parallel solid etalon is proposed. The method is aimed to reduce the spectrum broadening caused by non-parallel surfaces; it contains a theoretical formula for adjusting image distances, and an algorithm for processing the corresponding fringe patterns. Theoretical consideration, computer simulation, experimental results, and application demonstration are given. The fringe patterns captured by a CCD showed good agreement with the computer simulation, and the resolution of a λ/10-wavefront-error etalon was improved from 3.1 GHz to 0.51 GHz. In comparison with other methods, this new method is convenient and economical.

Molten salt oxidation of organic hazardous waste with high salt content.

Organic hazardous waste often contains some salt, owing to the widespread use of alkali salts during industrial manufacturing processes. These salts cause complications during the treatment of this type of waste. Molten salt oxidation is a flameless, robust thermal process, with inherent capability of destroying the organic constituents of wastes, while retaining the inorganic ingredients in the molten salt. In the present study, molten salt oxidation is employed for treating a typical organic hazardous waste with a high content of alkali salts. The hazardous waste derives from the production of thiotriazinone. Molten salt oxidation experiments have been conducted using a lab-scale molten salt oxidation reactor, and the emissions of CO, NO, SO2, HCl and dioxins are studied. Impacts are investigated from the composition of the molten salts, the types of feeding tube, the temperature of molten carbonates and the air factor. Results show that the waste can be oxidised effectively in a molten salt bath. Temperature of molten carbonates plays the most important role. With the temperature rising from 600 °C to 750 °C, the oxidation efficiency increases from 91.1% to 98.3%. Compared with the temperature, air factor has but a minor effect, as well as the composition of the molten salts and the type of feeding tube. The molten carbonates retain chlorine with an efficiency higher than 99.9% and the emissions of dioxins are below 8 pg TEQ g-1 sample. The present study shows that molten salt oxidation is a promising alternative for the disposal of organic hazardous wastes containing a high salt content.

Energy-Transfer Kinetics Driven by Midinfrared Amplified Spontaneous Emission after Two-Photon Excitation from Xe (s0) to the Xe (6p[1/2]0) State.

In optically pumped laser systems, rare gas lasers (RGLs) are a field of great interest for researchers. Gas laser regimes with metastable Ne, Ar, and Kr atoms have been investigated, while studies of RGLs based on metastable Xe are sparse. In this work, when a strong excitation laser (2.92 mJ/pulse, 7.44 × 105 W/cm2) was applied to excite Xe atoms from the ground state to the 6p[1/2]0 state, an interesting phenomenon emerged: An intense fluorescence of 980 nm (6p[1/2]1-6s[3/2]2) was produced. However, when the energy of excitation laser was decreased to 0.50 mJ/pulse (1.27 × 105 W/cm2), the fluorescence of 980 nm became very weak. Besides, lifetime and decay rate constant of the 6p[1/2]0 state under the condition of E = 2.92 mJ are significantly different from either those measured by other groups or those of E = 0.50 mJ. These phenomena indicate that the high energy of excitation laser should trigger some new kinetic mechanisms. Further works identified that the new kinetic mechanism is the MIR ASE of 3408 nm (6p[1/2]0-6s'[1/2]1). The mechanisms are proposed as follows. Substantial 6p[1/2]0 atoms are produced by laser excitation. Then, the ASE of 3408 nm (6p[1/2]0-6s'[1/2]1) is quickly produced to populate substantial 6s'[1/2]1 atoms. The 6s'[1/2]1 atoms can readily arrive at the 6p[1/2]1 states through collision by virtue of the small energy difference (84 cm-1) and high collision rate constant of the transition from the 6s'[1/2]1 state to the 6p[1/2]1 state. As a result, the intense fluorescence of 980 nm is generated.

Phase-interfacial stimulated Raman scattering generated in strongly pumped water.

We have observed unusual blue-shifted radiations in water pumped by a strong 532-nm nanosecond laser. Properties including divergence, polarizations, and pulse shapes of the unusual radiations are measured and compared with those of the regular stimulated Raman scattering (SRS) in water. The unusual radiations are attributed to the parametric anti-Stokes SRS that occurs on the interface of water and ionization plasma (or gas) formed in the laser-induced breakdown of water.

Multi-perturbation stochastic parallel gradient descent method for wavefront correction.

The multi-perturbation stochastic parallel gradient descent (SPGD) method for adaptive optics is presented in this work. The method is based on a new architecture. The incoming beam with distorted wavefront is split into N sub-beams. Each sub-beam is modulated by a wavefront corrector and its performance metric is measured subsequently. Adaptive system based on the multi-perturbation SPGD can operate in two modes - the fast descent mode and the modal basis updating mode. Control methods of the two operation modes are given. Experiments were carried out to prove the effectiveness of the proposed method. Analysis as well as experimental results showed that the two operation modes of the multi-perturbation SPGD enhance the conventional SPGD in different ways. The fast descent mode provides faster convergence than the conventional SPGD. The modal basis updating mode can optimize the modal basis set for SPGD with global coupling.

Research on speed sensorless control strategy of permanent magnet synchronous motor based on fuzzy super-twisting sliding mode observer.

Aiming at the problems of poor adjustment effect, weak anti-disturbance ability, and low robustness of the traditional sliding mode algorithm for permanent magnet synchronous motor speed sensorless, a permanent magnet synchronous motor speed observation method combining super-twisting sliding mode control algorithm and fuzzy control is proposed to accelerate the convergence speed of the system and improve the anti-disturbance ability. Fuzzy rules are used to solve the problem of obtaining the upper bound of the boundary function in the super-twisting algorithm. Moreover, the fuzzy algorithm is used to output the variable sliding mode gain instead of the fixed sliding mode coefficient to improve the system robustness and suppress the jitter. The simulation results show that the overshoot of the control system is 4%, the lag time is not more than 0.003 ms, the speed error is not more than 1%, and the response and adjustment time is not more than 0.02 s. The proposed control strategy improves the tracking accuracy and response speed of the system, suppresses the sliding mode chattering, and enhances the anti-interference ability of the system.

Study of PCDD/Fs distribution in fly ash, ash deposits, and bottom ash from a medical waste incinerator in China.

UNLABELLED: Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9-67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters. IMPLICATIONS: This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33 x 10(-3) ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties.

Activated carbon treatment of municipal solid waste incineration flue gas.

Activated carbon injection is widely used to control dioxins and mercury emissions. Surprisingly little attention has been paid to its modelling. This paper proposes an expansion of the classical Everaerts-Baeyens model, introducing the expression of fraction of free adsorption sites, f (s), and asserting the significant contribution of fly ash to dioxins removal. Moreover, the model monitors dioxins partitioning between vapour and particulate phase, as well as removal efficiency for each congener separately. The effects of the principal parameters affecting adsorption are analysed according to a semi-analytical, semi-empirical model. These parameters include temperature, contact time during entrained-flow, characteristics (grain-size, pore structure, specific surface area) and dosage of activated carbon, lignite cokes or mineral adsorbent, fly ash characteristics and concentration, and type of incinerator plant.