Nonlinear stage of Benjamin-Feir instability in forced/damped deep water waves

We study a three-wave truncation of a recently proposed damped/forced high-order nonlinear Schr\"odinger equation for deep-water gravity waves under the effect of wind and viscosity. The evolution of the norm (wave-action) and spectral mean of the full model are well captured by the reduced dynamics. Three regimes are found for the wind-viscosity balance: we classify them according to the attractor in the phase-plane of the truncated system and to the shift of the spectral mean. A downshift can coexist with both net forcing and damping, i.e., attraction to period-1 or period-2 solutions. Upshift is associated with stronger winds, i.e., to a net forcing where the attractor is always a period-1 solution. The applicability of our classification to experiments in long wave-tanks is verified.Comment: 8 pages, 4 figure

Variational dynamics of open quantum systems in phase space

We present a method to simulate the dynamics of large driven-dissipative many-body open quantum systems using a variational encoding of the Wigner or Husimi-Q quasi-probability distributions. The method relies on Monte-Carlo sampling to maintain a polynomial computational complexity while allowing for several quantities to be estimated efficiently. As a first application, we present a proof of principle investigation into the physics of the driven-dissipative Bose-Hubbard model with weak nonlinearity, providing evidence for the high efficiency of the phase space variational approach.Comment: 7 pages, 5 figure

Comparative study of recent wide-pore materials of different stationary phase morphology, applied for the reversed-phase analysis of recombinant monoclonal antibodies

Various recent wide-pore reversed-phase stationary phases were studied for the analysis of intact monoclonal antibodies (mAbs) of 150kDa and their fragments possessing sizes between 25 and 50kDa. Different types of column technology were evaluated, namely, a prototype silica-based inorganic monolith containing mesopores of ∼250Å and macropores of ∼ 1.1μm, a column packed with 3.6μm wide-pore core-shell particles possessing a wide pore size distribution with an average around 200Å and a column packed with fully porous 1.7μm particles having pore size of ∼300Å. The performance of these wide-pore materials was compared with that of a poly(styrene-divinyl benzene) organic monolithic column, with a macropore size of approximately 1μm but without mesopores (stagnant pores). A systematic investigation was carried out using model IgG1 and IgG2 mAbs, namely rituximab, panitumumab, and bevacizumab. Firstly, the recoveries of intact and reduced mAbs were compared on the two monolithic phases, and it appeared that adsorption was less pronounced on the organic monolith, probably due to the difference in chemistry (C18 versus phenyl) and the absence of mesopores (stagnant zones). Secondly, the kinetic performance was investigated in gradient elution mode for all columns. For this purpose, peak capacities per meter as well as peak capacities per time unit and per pressure unit (PPT) were calculated at various flow rates, to compare performance of columns with different dimensions. In terms of peak capacity per meter, the core-shell 3.6μm and fully porous 1.7μm columns outperformed the two monolithic phases, at a temperature of 60°C. However, when considering the PPT values, the core-shell 3.6μm column remained the best phase while the prototype silica-based monoliths became very interesting, mostly due to a very high permeability compared with the organic monolith. Therefore, these core-shell and silica-based monolith provided the fastest achievable separation. Finally, at the maximal working temperature of each column, the core-shell 3.6μm column was far better than the other one, because it is the only one stable up to 90°C. Lastly, the loading capacity was also measured on these four different phases. It appeared that the organic monolith was the less interesting and rapidly overloaded, due to the absence of mesopores. On the other hand, the loading capacity of prototype silica-based monolith was indeed reasonabl

Reconciling different formulations of viscous water waves and their mass conservation

The viscosity of water induces a vorticity near the free surface boundary. The resulting rotational component of the fluid velocity vector greatly complicates the water wave system. Several approaches to close this system have been proposed. Our analysis compares three common sets of model equations. The first set has a rotational kinematic boundary condition at the surface. In the second set, a gauge choice for the velocity vector is made that cancels the rotational contribution in the kinematic boundary condition, at the cost of rotational velocity in the bulk and a rotational pressure. The third set circumvents the problem by introducing two domains: the irrotational bulk and the vortical boundary layer. This comparison puts forward the link between rotational pressure on the surface and vorticity in the boundary layer, addresses the existence of nonlinear vorticity terms, and shows where approximations have been used in the models. Furthermore, we examine the conservation of mass for the three systems, and how this can be compared to the irrotational case.Comment: 32 pages, 5 figure

Microfluidic ion stripper for removal of trifluoroacetic acid from mobile phases used in HILIC-MS of intact proteins

© 2021, The Author(s).Trifluoroacetic acid (TFA) is commonly used as mobile phase additive to improve retention and peak shape characteristics in hydrophilic interaction liquid chromatography (HILIC) of intact proteins. However, when using electrospray ionization-mass spectrometry (ESI-MS) detection, TFA may cause ionization suppression and adduct formation, leading to reduced analyte sensitivity. To address this, we describe a membrane-based microfluidic chip with multiple parallel channels for the selective post-column removal of TFA anions from HILIC. An anion-exchange membrane was used to physically separate the column effluent from a stripper flow solution comprising acetonitrile, formic acid, and propionic acid. The exchange of ions allowed the post-column removal of TFA used during HILIC separation of model proteins. The multichannel design of the device allows the use of flow rates of 0.2 mL/min without the need for a flow splitter, using mobile phases containing 0.1% TFA (13 mM). Separation selectivity and efficiency were maintained (with minor band broadening effects) while increasing the signal intensity and peak areas by improving ionization and reducing TFA adduct formation. Graphical abstract: [Figure not available: see fulltext.

Advances in ultra-high-pressure and multi-dimensional liquid chromatography instrumentation and workflows

The present contribution discusses recent advances in ultra-high-pressure liquid chromatography (UHPLC) and multi-dimensional liquid chromatography (MDLC) technology. First, new developments in UHPLC column technology and system design are highlighted. The latter includes a description of a novel injector concept enabling method speed-up, emerging detectors, and instrument diagnostics approaches. Next, online MDLC workflows are reviewed and advances in modulation technology are highlighted. Finally, key applications published in 2020 are reviewed

Steady-state quantum chaos in open quantum systems

We introduce the notion of steady-state quantum chaos as a general phenomenon in open quantum many-body systems. Classifying an isolated or open quantum system as integrable or chaotic relies in general on the properties of the equations governing its time evolution. This however may fail in predicting the actual nature of the quantum dynamics, that can be either regular or chaotic depending on the initial state. Chaos and integrability in the steady state of an open quantum system are instead uniquely determined by the spectral structure of the time evolution generator. To characterize steady-state quantum chaos we introduce a spectral analysis based on the spectral statistics of quantum trajectories (SSQT). We test the generality and reliability of the SSQT criterion on several dissipative systems, further showing that an open system with chaotic structure can evolve towards either a chaotic or integrable steady state. We study steady-state chaos in the driven-dissipative Bose-Hubbard model, a paradigmatic example of out-of-equilibrium bosonic system without particle number conservation. This system is widely employed as a building block in state-of-the-art noisy intermediate-scale quantum devices, with applications in quantum computation and sensing. Finally, our analysis shows the existence of an emergent dissipative quantum chaos, where the classical and semi-classical limits display an integrable behaviour. This emergent dissipative quantum chaos arises from the quantum and classical fluctuations associated with the dissipation mechanism. Our work establishes a fundamental understanding of the integrable and chaotic dynamics of open quantum systems and paves the way for the investigation of dissipative quantum chaos and its consequences on quantum technologies.Comment: 23 pages, 12 figure