Concentrated suspensions develop an anisotropic microstructure when subjected to deformation, and this anisotropy persists after flow cessation, leading to direction-dependent mechanical properties. We investigate the mechanical response of a concentrated emulsion following an initial shear deformation. We use a circularly polarized shear to probe the material's elasticity in all directions relative to the initial shear. The emulsion softens along the direction of the applied deformation and stiffens in the perpendicular direction. The degree of mechanical anisotropy is found to depend on the amplitude of the initial deformation, with larger deformations leading to more pronounced directional differences in elasticity.

Single-molecule techniques are highly sensitive tools that can reveal reaction intermediates often obscured in experiments involving large ensembles of molecules. Therefore, they provide unprecedented information on the mechanisms that control biomolecular reactions. Currently, one of the most significant single-molecule assays is Magnetic Tweezers (MT), which probes enzymatic reactions at high spatio-temporal resolutions on tens, if not hundreds, of molecules simultaneously. For high-resolution MT experiments, a short double-stranded DNA molecule (less than 2,000 base pairs) is typically attached between a micron-sized superparamagnetic bead and a surface. The fabrication of such a substrate is key for successful single-molecule assays, and several papers have discussed the possibility of improving the fabrication of short DNA constructs. However, reported yields are usually low and require additional time-consuming purification steps (e.g., gel purification). In this paper, we propose the use of a Golden Gate Assembly assay that allows for the production of DNA constructs within minutes (starting from PCR products). We discuss how relevant parameters may affect the yield and offer single-molecule experimentalists a simple yet robust approach to fabricate DNA constructs.

The need to constantly improve the quality and properties of manufactured products leads to the development of hybrid materials that combine different elements, complementing one another. Fiber-reinforced mortar is one of those products, as the fibers are used to improve cementitious materials' flexural weakness. Experimental data on different metallic fibers dispersed in mortar demonstrate the correlation between early-age rheological properties and long-term mechanical strength. Both quantities depend on the ratio of the solid volume fraction of the fiber to a critical solid volume fraction characteristic of the form factors of the fiber. It is demonstrated that both effects arise from the packing stress of the fibers in the mortar when their concentrations are close to their maximum packing fraction. Geometrical arguments are used to explain how this critical volume fraction is related to the fiber form factor. Then, it enables the building of master curves using geometrical arguments.

AbstractMolecular cloning, a routine yet essential technique, relies heavily on efficient ligation, which can be significantly improved using Golden Gate Assembly (GGA). A key component of GGA is the use of type IIS enzymes, which uniquely cleave downstream of their recognition sequences to generate various overhangs, including non-palindromic ones. Recent advancements in GGA include the development of newly engineered enzymes with enhanced activity. Additionally, high-throughput GGA assays, which allow for the simultaneous study of all possible overhangs, have identified optimal GGA substrates with high efficiencies and fidelities, greatly facilitating the design of complex assemblies. Interestingly, these assays reveal unexpected correlations between ligation efficiencies and overhang stabilities. One hypothesis for this observation is that newly hydrolyzed DNA fragments with strong overhangs can readily re-ligate, thereby slowing down the overall process. In this paper, we employ a combination of gel electrophoresis and numerical calculations to test this hypothesis, ultimately determining that it does not hold true under the conditions established by conventional GGA assays. Using an assembly of 10 fragments, we demonstrate that strong overhangs yield higher GGA efficiency, while weak overhangs result in lower efficiency. These findings enable us to propose optimal overhangs for efficient GGA assays, significantly increasing yield.

AbstractSuspension electrospinning allows the environmental‐friendly fabrication of nano‐micro‐fibrous membranes since it is based on the processing of an aqueous particle suspension in which a hydrosoluble template polymer is added to insure the formation of a continuous fiber. Here, the case of polyurethane (PU) aqueous suspensions formulated with poly(ethylene oxide) (PEO) as the template polymer is studied. The effect of several parameters (particle size, PU/PEO ratio, PEO molar mass, and PEO concentration in the continuous phase) on particle‐particle and particle‐template polymer interactions that influence the rheological properties of the formulation and finally the electrospinning and the fiber morphology, is studied. The goal is to process a formulation with the highest particle content as possible. Thanks to a deep rheological investigation and the study of interactions and suspension morphology by zeta potential and diffusing wave spectroscopy, it is shown that regular fibers are efficiently produced when small particles are electrospun under favorable particle‐template polymer interactions and without screening the electrostatic repulsion between particles. Finally, a fibrous membrane is obtained from a formulation with a PU/PEO weight ratio equal to 50 under very stable and efficient production conditions.

The very early age flocculation of a cement based paste, in which cement is partially substituted by a calcined clay, metakaolin, is studied. We use rheological and ultrasonic reflection to monitor the evolution of the elastic properties of the paste with time, and light scattering to follow the change of its relaxation modes at small scales. We show that, at very early ages, of the order of hundreds of seconds after the paste preparation, a network of flocculated particles establishes, which manifests by a slow down of the dynamics of the relaxation modes of the paste at small scale. Then, this network consolidates and the macroscopic elastic modulus of the paste progressively increases with time, leading eventually to the setting of the paste. These observations show that, whatever the degree of replacement of clinker by metakaolin, a connected network establishes at very early times after the paste preparation, although the kinetics of flocculation slows down with clinker replacement.

Quantum emitters in two-dimensional layered hexagonal boron nitride are quickly emerging as a highly promising platform for next-generation quantum technologies. However, precise identification and control of defects are key parameters to achieve the next step in their development. We conducted a comprehensive study by analyzing over 10,000 photoluminescence emission lines, revealing 11 distinct defect families within the 1.6 to 2.2 eV energy range. This challenges hypotheses of a random energy distribution. We also reported averaged defect parameters, including emission linewidths, spatial density, phonon side bands, and the Debye-Waller factors. These findings provide valuable insights to decipher the microscopic origin of emitters in hBN hosts. We also explored the influence of hBN host morphology on defect family formation, demonstrating its crucial impact. By tuning flake size and arrangement we achieve selective control of defect types while maintaining high spatial density. This offers a scalable approach to defect emission control, diverging from costly engineering methods. It highlights the importance of investigating flake morphological control to gain deeper insights into the origins of defects and to expand the spectral tailoring capabilities of defects in hBN.

The aggregation behavior of an attractive colloidal silica suspension under oscillatory flow is studied using rheological measurement. We show that the competition between the aggregation of the particles and the aggregate breakup under external stress leads to a non-monotonous evolution of the elastic modulus with time. Remarkably, under certain conditions, the elasticity is not an increasing function of time but exhibits a maximum. The value of the maximum of the elastic modulus depends on the applied shear amplitude and the ionic strength of the suspension. Scaling laws that describes the evolutions of the elastic modulus as a function of the salinity and of the deformation amplitude are proposed and discussed.

Supplementary Methods from A Ruthenium-Containing Organometallic Compound Reduces Tumor Growth through Induction of the Endoplasmic Reticulum Stress Gene CHOP

The mechanical nonlinear response of dense Brownian suspensions of polymer gel particles is studied experimentally and by means of numerical simulations. It is shown that the response to the application of a constant shear rate depends on the previous history of the suspension. When the flow starts from a suspension at rest, it exhibits an elastic response followed by a stress overshoot and then a plastic flow regime. Conversely, after flow reversal, the stress overshoot does not occur, and the apparent elastic modulus is reduced while numerical simulations reveal that the anisotropy of the local microstructure is delayed relative to the macroscopic stress.

Controlling supramolecular polymerization is of fundamental importance to create advanced materials and devices. Here we show that the thermodynamic equilibrium of Gd3+-bearing supramolecular rod networks is shifted reversibly at room temperature in a static magnetic field of up to 2 T. Our approach opens opportunities to control the structure formation of other supramolecular or coordination polymers that contain paramagnetic ions.

We investigate the flow of a concentrated suspension of colloidal particles at deformation rates higher than the discontinuous shear-thickening transition shear rate. We show that, under its own weight, a jet of a concentrated enough colloidal suspension, simultaneously flows while it sustains tensile stress and transmits transverse waves. This results in a new flow instability of jets of shear-thickening suspensions: the jet is submitted to rapid transverse oscillations, that we characterize.

Understanding and controlling supramolecular polymerization are of fundamental importance to create advanced materials and devices. Many stimuli have been explored in the past decades, but magnetic fields and field gradients have received little attention. This is because magnets do not provide enough magnetic energy to overcome thermal noise at the single molecule level. Here we show that significant changes in network topology of Gd3+-decorated supramolecular polymer rods can nevertheless be observed using magnetic fields of order 1 T at room temperature. The structure of the rod networks is influenced during a slow diffusive process over a timescale of hours by the anisotropy of the demagnetizing field. Our approach opens opportunities to control and tune structure formation of many supramolecular and coordination polymers using a variety of rare earth or other paramagnetic ions.

Ru(bpy)(2)dppz(2+) has been widely used as a probe for exploring the structure of double-stranded DNA (dsDNA). The flexibility change of DNA helix is important in many of its biological functions but not well understood. Here, flexibility change of dsDNA helix caused by intercalation with Ru(bpy)(2)dppz(2+) was investigated using the atomic force microscopy. At first, the interactions between ruthenium complex and dsDNA helix were characterized and the binding site size (p = 2.87 bp) and binding constant (K-a = 5.9* 10(7) M-1) were determined by the relative extension of DNA helix using the equation of McGhee and von Hippel. By measuring intercalator-induced DNA elongation and the mean square of end-to-end distance at different molar ratios of Ru(bpy)(2)dppz(2+ )to dsDNA, the changes of persistence length under different ruthenium concentrations were determined by the worm-like chain model. We found that the persistence length of dsDNA decreased with increasing Ru(bpy)(2)dppz(2+) concentration, demonstrating that the flexibility of dsDNA obviously enhanced due to the intercalation. Especially, the persistence length changed greatly from 54 to 34 nm on changing the molar ratio of ruthenium to dsDNA from 0 to 0.2. We speculated that the intercalation of dsDNA with Ru(bpy)(2)dppz(2+) resulted in local deformation or bending of the DNA duplex. In addition, the thermal dynamic stability of DNA helix was measured with high resolution melting method which revealed the increase in thermal dynamic stability of DNA helix due to the ruthenium intercalation.

Traction Force Microscopy (TFM) computes the forces exerted at the surface of an elastic material by measuring induced deformations in volume. It is used to determine the pattern of the adhesion forces exerted by cells or by cellular assemblies grown onto a soft deformable substrate. Typically, colloidal particles are dispersed in the substrate and their displacement is monitored by fluorescent microscopy. As with any other fluorescent techniques, the accuracy in measuring a particule's position is ultimately limited by the number of evaluated fluorescent photons. Here, we present a TFM technique based on the detection of probe particle displacements by holographic tracking microscopy. We show that nanometer scale resolutions of the particle displacements can be obtained and determine the maximum volume fraction of markers in the substrate. We demonstrate the feasibility of the technique experimentally and measure the three-dimensional force fields exerted by colorectal cancer cells cultivated onto a polyacrylamide gel substrate.

Electrospinning is the process of choice allowing the preparation of nanofibrous materials from a solution usually based on a high molar mass polymer. The solution must bring enough chain entanglements to avoid any breaking or Rayleigh instability of the electrospun jet resulting thus in the deposition of a continuous and regular solid nanofibre. It has been however shown that some few non-polymeric molecules can be electrospun without using a carrier polymer. We demonstrate here the case of tannic acid. Indeed, it was possible to electrospin this molecule solubilised in a mixture of water and ethanol as well as in pure water. Rheology, dynamic light scattering and cryo-TEM highlight the formation of tannic acid aggregates in solution. Above a critical concentration, these aggregates form a supramolecular interconnected network strong enough to allow the electrospinning of a continuous and regular nanofibre. The resulting nanoweb is mechanically stable and can be handled and wrapped. Furthermore, as opposed to the other small molecules for which polymer-free electrospinning was also demonstrated, tannic acid nanowebs can be efficiently cross-linked in water either by oxidative reaction with sodium periodate or, most interestingly, with FeIII by a combination of oxidative reaction and the formation of coordination complexes. The proposed electrospinning and cross-linking strategy is easy, of low cost, and scalable and uses non-toxic solvents as well as biocompatible and biofunctional molecules. Furthermore, thanks to the chelation capacity of tannic acid having the ability to coordinate with a wide variety of metals, hybrid smart nanowebs can be envisaged for diverse applications such as biomedical, catalysis as well as environment.

The time dependent rheological behavior of a concentrated CaCO3 particle suspension is studied. The particles are suspended in a mixture of three industrial products: two resins, composed of styrene monomer, a styrene-butadiene-styrene block copolymer, and an unsaturated polyester oligomer, and one surfactant, acting as a dispersing agent for the particles. For the measurements, a MCR 301 rheometer from Anton Paar is used in the rotational mode, with a Couette geometry. An unusual behavior is observed, in which the low shear-rate viscosity of the suspension depends in a non-monotonous way on the shear rate applied during a previous shear history. The viscosity of the suspension at low shear rate depends both on the value of the prior shear rate, and the time during which it is applied. We found that the phenomenon is more pronounced when the particles volume fraction is increased. We propose an interpretation of the observed phenomenon in which links of different strengths can be formed between the particles and only the weakest links are destroyed by moderate shear rates.

We study the imbibition of a spherical porous aggregate. When the difference in pressure between the inside and the outside of the aggregate is large enough, the imbibition front becomes unstable. This instability leads to the acceleration of the imbibition process. In more complex geometries with non-constant curvatures, the imbibition becomes locally unstable in the regions with the highest curvatures, leading to spatially heterogeneous front velocities.