Drop Capturing Based on Patterned Substrate in Space

In this work, we introduced a method for capturing aqueous drop based on a patterned substrate in space. Through the manipulation test of a colloidal drop, it could be verified that this patterned substrate had excellent control ability for aqueous drop in microgravity condition. The confinement mechanism of this substrate was clarified, which showed that drops with different volume could be pinned and attracted at a given area on the substrate. The confinement capability was related to the gravity effect, and the patterned substrate could confine aqueous drops with larger volume under microgravity than in normal gravity. With advantages of simple operation and strong capability to control large drops, this technique exhibited the wide application prospect in the fields of fluid management, biosensing, and pharmacy in microgravity condition in the future

Intermetallic phases and secondary austenite precipitation at the multipass welding HAZ of duplex stainless steels.

Os aços inoxidáveis duplex (AIDs) são materiais com um excelente desempenho tanto mecânico como à corrosão. Inúmeras pesquisas tem sido desenvolvidas para aprimorar a soldabilidade destas ligas. Algumas transformações de fase, que são passíveis de ocorrer durante o processo de soldagem, podem prejudicar seriamente o desempenho das juntas. Foram simuladas microestruturas da região da zona afetada pelo calor submetida a temperaturas elevadas (ZACTE), utilizando um modelo proposto de fluxo de calor. Abordaram-se aspectos fundamentais da precipitação de austenita secundária, de nitreto de cromo e as suas interações na ZACTE de soldas multipasse. Finalmente, foram realizados testes de tenacidade e de resistência à corrosão para avaliar o efeito das transformações de fase estudadas no desempenho das juntas soldadas. Os tratamento térmicos e simulações da ZACTE foram realizadas num equipamento GleebleÒ. As microestruturas foram analisadas mediante microscopia ótica e eletrônica de varredura e de transmissão. Junto com a microscopia eletrônica foram realizadas microanálises químicas das fases estudadas. Baseando-se nos resultados obtidos, verificou-se que nem todos os AIDs são susceptíveis de ferritizar. Este fato tem uma grande influência no comportamento metalúrgico e na soldabilidade destes aços. Quanto aos aspectos fundamentais da metalurgia destes aços, observou-se uma estreita interação entre a precipitação da austenita secundária e os nitretos de cromo, chegando-se a propor um mecanismo de nucleação da austenita secundária intragranular a partir dos nitretos. Por último, foi constatado que o efeito deletério da austenita secundária intragranular na resistência à corrosão pode ser evitado mediante a adequada elaboração do procedimento de soldagem.Duplex stainless steels (DSS) have excellent mechanical and corrosion properties. Many researches have been developed regarding the weldability of these alloys. There are some phase transformations that take place during the welding process, which may impair the welded joint behavior. High temperature heat-affected zone (HTHAZ) microstructures were simulated using a proposed heat flow model. Fundamental aspects of the secondary austenite and chromium nitride precipitation, and its interactions in the HTHAZ of multipass welds, were studied. In addition, toughness and corrosion tests were done to evaluate the influence of the studied phase transformations on the weld behavior. A GleebleÒ system was used to do the heat treatments and HTHAZ simulations. The microstructures were analyzed by means of optic and electron microscopy. Along with the electron microscopy it was done chemical microanalysis of the studied phases. Based on results, it was verified that not all DSSs can be ferritized. This fact has a strong influence on metallurgical behavior and weldability of these alloys. Regarding to the metallurgical fundamental aspects of these steels, it was observed a remarkable interaction between secondary austenite and chromium nitride precipitation. Thus, it was proposed a mechanism of intragranular secondary austenite precipitation from chromium nitrides. It was also verified, how the deleterious effect of intragranular secondary austenite in the corrosion resistance can be avoided by means of appropriate welding procedures

Shock wave generation and propagation in dissipative and nonlocal nonlinear Rydberg media

We investigate the generation of optical shock waves in strongly interacting Rydberg atomic gases with a spatially homogeneous dissipative potential. The Rydberg atom interaction induces an optical nonlocal nonlinarity. We focus on local nonlinear ($R_b\ll R_0$) and nonlocal nonlinear ($R_b\sim R_0$) regimes, where $R_b$ and $R_0$ are the characteristic length of the Rydberg nonlinearity and beam width, respectively. In the local regime, we show spatial width and contrast of the shock wave change monotonically when increasing strength of the dissipative potential and optical intensity. In the nonlocal regime, the characteristic quantity of the shock wave depend on $R_b/R_0$ and dissipative potential nontrivially and on the intensity monotonically. We find that formation of shock waves dominantly takes place when $R_b$ is smaller than $R_0$, while the propagation dynamics is largely linear when $R_b$ is comparable to or larger than $R_0$. Our results reveal nontrivial roles played by dissipation and nonlocality in the generation of shock waves, and provide a route to manipulate their profiles and stability. Our study furthermore opens new avenues to explore non-Hermitian physics, and nonlinear wave generation and propagation by controlling dissipation and nonlocality in the Rydberg media

Application of ¹H DOSY for Facile Measurement of Polymer Molecular Weights

To address the practical issues of polymer molecular weight determination, the first accurate polymer weight-average molecular weight determination method in diverse living/controlled polymerization via DOSY (diffusion-ordered NMR spectroscopy) is reported. Based on the linear correlation between the logarithm of diffusion coefficient (log <i>D</i>) and the molecular weights (log <i>M</i>_w), external calibration curves were created to give predictions of molecular weights of narrowly dispersed polymers. This method was successfully applied to atom transfer radical polymerization (ATRP), reversible addition–fragmentation chain transfer (RAFT), and ring-opening metathesis polymerization (ROMP), with weight-average molecular weights given by this method closely correlated to those obtained from GPC measurement

Chiral Lithium Diamides Derived from Linked <i>N</i>‑Isopropyl Valinol or Alaninol

Four different chiral diamino diethers synthesized from <i>N</i>-isopropyl valinol or <i>N</i>-isopropyl alaninol were lithiated with <i>n</i>-butyllithium in tetrahydrofuran or diethyl ether. Crystal structures of the dilithiated diamino diethers were determined by X-ray diffraction. Three dilithiated diamino diethers including (2<i>S</i>,2′<i>S</i>)-1,1′-(butane-1,4-diylbis­(oxy))­bis­(<i>N</i>-isopropylpropan-2-amine) <b>7</b>, (2<i>S</i>,2′<i>S</i>)-1,1′-(pentane-1,5-diylbis­(oxy))­bis­(<i>N</i>-isopropylpropan-2-amine) <b>8</b>, and (2<i>S</i>,2′<i>S</i>)-1,1′-(heptane-1,7-diylbis­(oxy))­bis­(<i>N</i>-isopropyl-3-methylbutan-2-amine) <b>9</b> are dimers, whereas dilithiated (2<i>S</i>,2′<i>S</i>)-1,1′-(pentane-1,5-diylbis­(oxy))­bis­(<i>N</i>-isopropyl-3-methylbutan-2-amine) <b>10</b> is a monomer. The lithium atoms in all crystal structures adopt a nonequivalent coordination protocol and exist in two different environments in which one of the lithium atoms is tetra-coordinated while the other one is tri-coordinated. The solution structures of the dilithiated diamino diethers are also characterized by a variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula (D-FW) weight correlation analyses and other one- and two-dimensional NMR techniques

Diffusion Coefficient−Formula Weight Correlation Analysis via Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy (DOSY NMR) To Examine Acylglycerol Mixtures and Biodiesel Production

Biodiesel, fatty acid methyl esters derived from vegetable oils, is a well-established alternative to petroleum diesel. We have developed a rapid ¹H diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY NMR) method to resolve mixtures of mono-, di-, and triacyglycerols along with their methyl esters. Because of the differences in diffusion coefficients between the starting materials (triglycerides), intermediates (mono- and diglycerols), and products (methyl esters), we were able to accurately predict the formula weights of these species in solution. This technique was used to monitor transesterification reactions of virgin and waste vegetable oils. In addition to proving its utility to assess conversion of starting materials, we found that 1,3-diacylglycerol is the major intermediate formed during alkali-catalyzed biodiesel production

Emergence and control of complex behaviors in driven systems of interacting qubits with dissipation

Progress in the creation of large scale, artificial quantum coherent structures demands the investigation of their nonequilibrium dynamics when strong interactions, even between remote parts, are non-perturbative. Analysis of multiparticle quantum correlations in a large system in the presence of decoherence and external driving is especially topical. Still, the scaling behaviour of dynamics and related emergent phenomena are not yet well understood. We investigate how the dynamics of a driven system of several quantum elements (e.g., qubits or Rydberg atoms) changes with increasing number of elements. Surprisingly, a two-element system exhibits chaotic behaviours. For larger system sizes a highly stochastic, far from equilibrium, hyperchaotic regime emerges. Its complexity systematically scales with the size of the system, proportionally to the number of elements. Finally, we demonstrate that these chaotic dynamics can be efficiently controlled by a periodic driving field. The insights provided by our result indicate the possibility of a reduced description for the behaviour of a large quantum system in terms of the transitions between its qualitatively different dynamical regimes. These transitions are controlled by a relatively small number of parameters, which may prove useful in the design, characterization and control of large artificial quantum structures

Chaos and hyperchaos in the chain of quantum coherent elements

We study the chain of coupled quantum coherent systems with energy pumping and dissipation. Examples of such systems include the coupled Rydberg atoms with laser driving and spontaneous emission or electromagnetically driven artificial qubits with decoherence and dissipation. We found out that such system is able to demonstrate spontaneous onset of chaotic and even hyperchaotic oscillations, which are characterized by one or several positive Lyapunov exponents. Remarkably, the number of the positive Lyapunov exponents grows with the number of the chain elements. Hence a large chain is able to demonstrate highly irregular behavior. We investigate transition from regular to chaotic behavior and reveal the related instabilities

Conformational Polymorphism of Lithium Pinacolone Enolate

A metastable, polymorphic hexameric crystal structure of lithium pinacolone enolate (LiOPin) is reported along with three preparation methods. NMR-based structural characterization implies that the lithium pinacolate hexamer deaggregates to a tetramer in toluene but retains mainly the hexameric structure in nonaromatic hydrocarbon solvents such as cyclohexane. Moreover, the presence of a small amount of lithium aldolate (LiOA) dramatically influences the aggregation state of LiOPin by forming a mixed aggregate with a 3:1 ratio (LiOPin₃·LiOA)

Data_Sheet_1_Responses of Woody Plant Functional Traits to Nitrogen Addition: A Meta-Analysis of Leaf Economics, Gas Exchange, and Hydraulic Traits.PDF

<p>Atmospheric nitrogen (N) deposition has been found to significantly affect plant growth and physiological performance in terrestrial ecosystems. Many individual studies have investigated how N addition influences plant functional traits, however these investigations have usually been limited to a single species, and thereby do not allow derivation of general patterns or underlying mechanisms. We synthesized data from 56 papers and conducted a meta-analysis to assess the general responses of 15 variables related to leaf economics, gas exchange, and hydraulic traits to N addition among 61 woody plant species, primarily from temperate and subtropical regions. Results showed that under N addition, leaf area index (+10.3%), foliar N content (+7.3%), intrinsic water-use efficiency (+3.1%) and net photosynthetic rate (+16.1%) significantly increased, while specific leaf area, stomatal conductance, and transpiration rate did not change. For plant hydraulics, N addition significantly increased vessel diameter (+7.0%), hydraulic conductance in stems/shoots (+6.7%), and water potential corresponding to 50% loss of hydraulic conductivity (P₅₀, +21.5%; i.e., P₅₀ became less negative), while water potential in leaves (−6.7%) decreased (became more negative). N addition had little effect on vessel density, hydraulic conductance in leaves and roots, or water potential in stems/shoots. N addition had greater effects on gymnosperms than angiosperms and ammonium nitrate fertilization had larger effects than fertilization with urea, and high levels of N addition affected more traits than low levels. Our results demonstrate that N addition has coupled effects on both carbon and water dynamics of woody plants. Increased leaf N, likely fixed in photosynthetic enzymes and pigments leads to higher photosynthesis and water use efficiency, which may increase leaf growth, as reflected in LAI results. These changes appear to have downstream effects on hydraulic function through increases in vessel diameter, which leads to higher hydraulic conductance, but lower water potential and increased vulnerability to embolism. Overall, our results suggest that N addition will shift plant function along a tradeoff between C and hydraulic economies by enhancing C uptake while simultaneously increasing the risk of hydraulic dysfunction.</p