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The Second Oil Production Plant of Xinjiang Oilfield produces a large amount of highly emulsified crude oil, which has a serious impact on the subsequent oil–water separation. At present, the concentration of demulsifier has increased to 2000 mg/L, but the demulsification effect is still poor. In this paper, the source and physical properties of highly emulsified crude oil are investigated firstly. The results show that highly emulsified crude oil is composed of three kinds of liquid: (1) conventional water flooding (WF); (2) chemical flooding (CF); (3) fracturing backflow fluid (FB). Among them, high zeta potential, low density difference, high viscosity, and small emulsion particles are responsible for the difficulty in the demulsification of the WF emulsion, while the high pH value is the reason why the CF emulsion is difficult to demulsify. Therefore, systematic experiments were implemented to investigate the optimal demulsification approach towards the three liquids above. As for the WF emulsion, it was necessary to raise the temperature to 70 °C and the concentration of the demulsifier to 200 mg/L. Moreover, it was only necessary to add 200 mg/L of demulsifier to break the CF emulsion after adjusting the pH value to 7, while no extra treatments were needed to break the FB emulsion. We hope this study can provide a new insight for the treatment of emulsions in the later stage of oilfield development. [ABSTRACT FROM AUTHOR]

In order to put forward an efficient and eco-friendly approach to degrade dye-containing industrial effluents, an n-Fe3O4/ACF nanocomposite was synthesized using the facile precipitation method and applied as a functional cathode for a heterogeneous electro-Fenton (E-Fenton) process. In particular, optimal initial pH value, current density, pole plate spacing, and electrode area were confirmed through systematical experiments as 5.73, 30 mA/cm2, 3 cm, and 2 × 2 cm2, respectively. Under such optimal reaction conditions, 98% of the methylene blue (MB) was degraded by n-Fe3O4/ACF after 2 h of E-Fenton treatment. In addition, n-Fe3O4/ACF could still decolor about 90% of the methylene blue (MB) for five rounds with some reductions in efficiency. Furthermore, results of electrochemical impedance spectroscopy and heterogeneous E-Fenton performance tests indicated that the loading of metal material Fe3O4 could enhance the overall electron transport capacity, which could accelerate the whole degradation processes. Moreover, the rich pores and large specific surface area of n-Fe3O4/ACF provided many active sites, which could greatly improve the efficiency of O2 reduction, promote the generation of H2O2, and shorten the reaction length between •OH and the pollutant groups. [ABSTRACT FROM AUTHOR]

It is generally impossible to maintain tight focusing over a long distance because of diffraction; this so-called Rayleigh's curse may be broken for a femtosecond laser if the wavefront curvature varies with laser wavelength. This paper reports on a nonlinear technique to produce a wavelength-dependent wavefront. We reveal a wavelength-dependent wavefront mechanism that is induced in optical parametric chirped-pulse amplification (OPCPA) where the crystal effect of group-velocity mismatch (GVM) dominates. Both analytical and numerical investigations show that the sign of the produced wavefront can be changed by GVM, and the magnitude can be enhanced by multistage OPCPA. The results suggest that the Rayleigh range at a fixed beam waist size can be significantly increased by the OPCPA-induced wavelength-dependent wavefront. [ABSTRACT FROM AUTHOR]

In order to improve the photocatalytic activity of TiO2, we successfully loaded nano-CuO on the TiO2 nanomeshes as CuO-TiO2 nanocomposites through a facile electrodeposition method. The optimized calcined temperature after Cu electrodeposition is confirmed as 450 °C, which could furthest assist the crystallization of anatase TiO2 and guarantee the high photocatalytic activity of CuO-TiO2 nanocomposites. Comparing with pure TiO2 nanomeshes, CuO-TiO2 nanocomposites showed better degradability of methylene blue, and the degradation efficiency reached to 35% after 120 min irradiation. Additionally, CuO-TiO2 nanocomposites exhibit much stronger absorption intensity within the visible light scope, more than two times than that of pure TiO2 nanomeshes, which indicates that the loading of nano-CuO could promote photocatalytic efficiency by the strong visible light absorption. Additionally, CuO-TiO2 nanocomposites show faster photocurrent response and lower charge transfer resistance than that of pure TiO2 nanomeshes, which implies that the recombination rate of photogenerated electron-hole pairs was reduced after nano-CuO loading. [ABSTRACT FROM AUTHOR]

Ultrafast mid-infrared (mid-IR) lasers with a high pulse repetition rate are in great demand in various fields, including attosecond science and strong-field physics. Due to the lack of suitable mid-IR laser gain medium, optical parametric amplifiers (OPAs) are used to generate an ultrafast mid-IR laser. However, the efficiency of OPA is sensitive to phase mismatches induced by wavelength and temperature deviations from the preset points, which thus limits the pulse duration and the average power of the mid-IR laser. Here, we exploited a noncollinear phase-matching configuration to achieve simultaneously wavelength- and temperature-insensitive mid-IR OPA with a LiGaS2 crystal. The noncollinearity can cancel the first-order dependence of phase matching on both wavelength and temperature. Benefitting from the thermal property of the LiGaS2 crystal, some collinear phase-matching solutions derived from the first-order and even third-order wavelength insensitivity have comparatively large temperature bandwidths and can be regarded as approximate solutions with simultaneous wavelength and temperature insensitivity. These simultaneously wavelength- and temperature-insensitive phase-matching designs are verified through numerical simulations in order to generate few-cycle, high-power mid-IR pulses. [ABSTRACT FROM AUTHOR]

Optical parametric chirped-pulse amplification is inevitably subject to high-order spatial chirp, particularly under the condition of saturated amplification and a Gaussian pump; this corresponds to an irreversible spatiotemporal distortion and consequently degrades the maximum attainable focused intensity. In this paper, we reveal that such spatial chirp distortion can be significantly mitigated in quasi-parametric chirped-pulse amplification (QPCPA) with idler absorption. Simulation results show that the quality of focused intensity in saturated QPCPA is nearly ideal, with a spatiotemporal Strehl ratio higher than 0.98. As the seed bandwidth increases, the idler absorption spectrum may not be uniform, but the Strehl ratio in QPCPA can be still high enough due to stronger idler absorption. [ABSTRACT FROM AUTHOR]

Indium selenide (InSe) film, an emerging two-dimensional chalcogenide semiconductor, has recently attracted growing interests in optoelectronics. However, its nonlinear characteristics and application potentials in mid-infrared (IR) region remain open, which is a very attractive but undeveloped spectral region currently. In this work, it is demonstrated that InSe film possesses excellent nonlinear absorption properties in 3- to 4-μm band. Saturable absorption measurements of InSe film at 2.8 and 3.5 μm show very low saturation energy fluences and moderate modulation depths. Pump–probe measurements at 3 and 4 μm indicate that InSe film has ultrafast responses in mid-IR region. Furthermore, the application of InSe film in mid-IR pulsed laser is demonstrated, and stable Q-switching operation of fiber laser at 2.8 μm is realized. These results show that InSe film is a promising saturable absorber for mid-IR pulsed laser. [ABSTRACT FROM AUTHOR]

Ultrafast lasers with both high peak-power and high average-power will open new avenues for many applications. While conventional technologies of Ti:sapphire laser amplification and optical parametric amplification can achieve several tens of watts of average-power, scaling to a higher average-power is challenging due to thermal limitations. Here, we demonstrate that the quasi-parametric chirped-pulse amplification (QPCPA) can break this average-power barrier. QPCPA is proven robust against the thermal dephasing by obstructing the back-conversion effect. Numerical simulations show that QPCPA based on a Sm:YCOB crystal can support peak powers of 3 TW at 5 kHz and 13.5 PW at 1 Hz, with average powers exceeding 150 W in both cases. We also discuss the prospects of QPCPA with the recently proposed configuration of temperature-insensitive phase matching, which is promising to simultaneously achieve higher peak-power and higher average-power. [ABSTRACT FROM AUTHOR]

A novel 2D alloy, free-standing few-layer SnSb nanosheets, is fabricated via a liquid-phase exfoliation approach. The resultant few-layer SnSb possesses ultrathin features (1–4 nm), large aspect ratio, largely exposed surfaces and a precise stoichiometric ratio between Sn and Sb (1 : 1). These few-layer SnSb nanosheets are systematically investigated for lithium storage, and exhibit a high reversible capacity of 694 mA h g−1, high rate capability and good cycling performance, as we expected. [ABSTRACT FROM AUTHOR]

In this work, a facile dealloying strategy was developed for the large scale fabrication of 2D stanene nanosheets under ambient conditions. The obtained stanene nanosheets exhibited typical 2D structure with a thickness of 4 nm and a lateral size of several micrometers. Furthermore, the 2D stanene nanosheets displayed outstanding performance in potassium storage. [ABSTRACT FROM AUTHOR]

Abstract: Noise is a fundamental and ubiquitous problem in optics, and only those out of the signal bandwidth can be filtrated away by traditional spectral filters. This paper presents an in‐band noise filtering scheme where the ultrafast signal is controlled by spatio‐spectral coupling such that the signal and its in‐band noise can be separated in the spatio‐spectral domain. As an example of its impact on ultra‐intense lasers, this filter is applied to show that the noise produced in chirped‐pulse amplification can be efficiently filtrated within the signal bandwidth. Near‐noiseless amplification of pulses with contrast as high as 1011 is demonstrated in a high‐gain optical parametric chirped‐pulse amplifier, resulting in approximately 40 times enhancement in output contrast. The simplicity, efficiency, and direct compatibility with existing techniques for short‐pulse generation will make in‐band filtering attractive to a wide range of applications in ultrafast optics and time‐resolved spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: High‐charge optical vortices, every photon of which carries an orbital angular momentum with a large quantum number, are ideal sources for testing macroscopic quantum entanglements. Also, they show great potential in angular remote sensing and precise spatial measurements. The optical vortices generated directly from laser, which are eigensolutions of laser cavity equation (Helmholtz equation), are naturally of ideal quality. So far, many attempts have been made to generate optical vortices directly from lasers, but the topological charge remains low (<10th order). Here, the generation of optical vortices with high topological charge directly from laser is reported. By laser inscribing round patterns on the surface of the cavity mirror, optical vortices with topological charges up to the 288th order are generated. A theoretical design criterion is proposed for generating arbitrary‐charge optical vortices directly from laser, and even generation of over the 1000th‐order vortex is feasible with this method. It is also experimentally demonstrated that the generated vortices from the laser are transmission stable and have a significant advantage over the vortices generated by phase elements. This work may open up application prospects of optical vortices in quantum optics and precise metrology. [ABSTRACT FROM AUTHOR]

We report on a passively Q-switched fiber laser with black phosphorus as saturable absorber. By employing the sol-gel fabricated large-mode-area Tm-doped fiber as gain medium, a high-energy Q-switched fiber laser has been demonstrated which delivers the maximum pulse energy of 11.72 μJ with the pulse width of 660 ns at the wavelength of 1954 nm. Our experimental results indicate that BP Q-switched large-mode-area Tm-doped fiber laser is an effective and reliable approach to generate high-energy pulses at 2 μm. [ABSTRACT FROM AUTHOR]

Metallic antimony (Sb) with gray allotrope has rarely been considered from the viewpoint of two-dimension layered system is actually a graphite-like material, in which Sb layers consist of fused, ruffled, and six-membered rings. Given that metallic Sb nanosheets can be played like graphene, it would be anticipated to obtain a new anode material with superior electrochemical performances for sodium storage. In this work, we propose an efficient strategy to fabricate free-standing metallic Sb nanosheets via liquid-phase exfoliation of gray Sb powder in an ios-propyle alcohol (IPA) solution with a constant concentration of sodium hydroxide. As a proof of the concept, several hybrid films composed of metallic Sb nanosheets and graphene with tunable densities are achieved, in which the notorious volume change of metallic Sb can be efficiently alleviated with the aid of the good flexible graphene, and the whole density of electrode films can be significantly improved by harnessing the high density of Sb nanosheets. As a consequence, the optimized metallic Sb nanosheets-graphene (SbNS-G) film displays a high volumetric capacity of 1226 mAh cm-3, high-rate capability and good cycle performance for sodium storage. [ABSTRACT FROM AUTHOR]

Both femtosecond and dual-wavelength picosecond operations of Nd,La:SrF2 disordered crystal laser have been demonstrated for the first time. In femtosecond operation, the laser generated mode-locked pulses with pulse duration of 156 fs, which is an average power of 90 mW, and a repetition rate of 108 MHz at the central wavelength of 1057 nm. In dual-wavelength picosecond operation, the laser generated synchronously mode-locked pulses with an average power of 500 mW and pulse duration of 9.9 ps. The mode-locked spectrum clearly shows two peaks at 1050.8 and 1059.0 nm, respectively. A periodic beat frequency of 2.2 THz is observed from the intensity autocorrelation trace, indicating the synchronous dual-wavelength mode-locking. Our experimental results show that Nd,La:SrF2 disordered crystal is an excellent laser material for femtosecond and dual-wavelength lasers near 1 μm wavelength. [ABSTRACT FROM PUBLISHER]

Intense long‐wave infrared (LWIR) femtosecond pulses within the 8−14 µm atmospheric window present an array of applications, such as in strong‐field physics, ultrafast nonlinear spectroscopy, and self‐guided atmospheric propagation. However, the realization of an LWIR source capable of delivering millijoule‐class energy, few‐cycle duration, and kHz repetition rate concurrently remains challenging. Here, such an LWIR source via the combination of different nonlinear parametric processes is reported, driven by a 1 kHz Yb:YAG thin‐disk laser. The system comprises two parallel multi‐cycle optical parametric chirped‐pulse amplifiers (OPCPAs) operating at 2.3 and 3.1 µm, respectively, alongside a stage of ZnGeP2‐crystal‐based difference‐frequency generation (DFG). The resulting 9 µm DFG pulses have a record energy of 0.21 mJ, a 3‐cycle duration, a 1 kHz repetition rate, and long‐term energy stability. The simultaneous output of three synchronized intense lasers at short‐wave infrared (2.3 µm), mid‐wave infrared (3.1 µm), and LWIR (9 µm) renders the source particularly appealing for multicolor ultrafast applications. [ABSTRACT FROM AUTHOR]

Summary: The IκB kinase complex (IKK) is a key regulator of immune responses, inflammation, cell survival, and tumorigenesis. The prosurvival function of IKK centers on activation of the transcription factor NF-κB, whose target gene products inhibit caspases and prevent prolonged JNK activation. Here, we report that inactivation of the BH3-only protein BAD by IKK independently of NF-κB activation suppresses TNFα-induced apoptosis. TNFα-treated Ikkβ −/− mouse embryonic fibroblasts (MEFs) undergo apoptosis significantly faster than MEFs deficient in both RelA and cRel due to lack of inhibition of BAD by IKK. IKK phosphorylates BAD at serine-26 (Ser26) and primes it for inactivation. Elimination of Ser26 phosphorylation promotes BAD proapoptotic activity, thereby accelerating TNFα-induced apoptosis in cultured cells and increasing mortality in animals. Our results reveal that IKK inhibits TNFα-induced apoptosis through two distinct but cooperative mechanisms: activation of the survival factor NF-κB and inactivation of the proapoptotic BH3-only BAD protein. [ABSTRACT FROM AUTHOR]