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Modern kernels are large, complex, and plagued with bugs. Unfortunately, their large size and complexity make kernel failures very challenging for developers to diagnose since failures encountered in deployment are often notoriously difficult to reproduce. Although record-replay techniques provide the powerful ability to accurately record a failed execution and deterministically replay it, enabling advanced manual and automated analysis techniques, they are inefficient and do not scale with modern I/O-intensive, concurrent workloads. This paper introduces KRR, a kernel record-replay framework that provides a highly efficient execution recording mechanism by narrowing the scope of the record and replay boundary to the kernel. Unlike previous record-replay wholestack approaches, KRR adopts a split-recorder design that employs the guest and the host to jointly record the kernel execution. Our evaluation demonstrates that KRR scales efficiently up to 8 cores, across a range of different workloads, including kernel compilation, RocksDB, and Nginx. When recording 8-core VMs that run RocksDB and kernel compilation, KRR incurs only a 1.52× ∼ 2.79× slowdown compared to native execution, while traditional whole-VM RR suffers from 8.97× ∼ 29.94× slowdown. We validate that KRR is practical and has a broad recording scope by reproducing 17 bugs across different Linux versions, including 6 non-deterministic bugs and 5 high-risk CVEs; KRR was able to record and reproduce all but one non-deterministic bug. 

Through a combined approach of experiment and simulation, this study quantifies the role of entanglements in determining the mechanical properties of glassy polymer blends. Uniaxial extension experiments on 100-nm films containing a bidisperse mixture of polystyrene enable quantitative comparison with molecular dynamics (MD) simulations of a coarse-grained model for polymer glasses, where the bidisperse blends allow us to systematically tune the entanglement density of both systems. In the MD simulations, we demonstrate that not all entanglements carry substantial load at large deformation, and our analysis allows the development of a model to describe the number of effective, load-bearing entanglements per chain as a function of blend ratio. The film strength measured experimentally and the simulated film toughness are quantitatively described by a model that only accounts for load-bearing entanglements. 

Naturally occurring nanocomposites like nacre owe their exceptional mechanical properties to high loadings of platelets that are bridged by small volume fractions of polymers. Polymer infiltration into dense assemblies of nanoparticles provides a powerful and potentially scalable approach to manufacture bio-inspired nanocomposites that mimic nacre's architecture. Solvent-driven infiltration of polymers (SIP) into nanoparticle packings formed on top of glassy polymer films is induced via capillary condensation of a solvent in the interstitial voids between nanoparticles (NP), followed by plasticization and transport of polymers into the liquid-filled pores, leading to the formation of the nanocomposite structure. To understand the effect of polymer–nanoparticle interactions on the dynamics of polymer infiltration in SIP, we perform molecular dynamics simulations. The mechanism of polymer infiltration and the influence of interactions between polymer and NPs on the dynamics of the process are investigated. Depending on the strength of interaction, polymer infiltration either follows (a) dissolution-dominated infiltration where plasticized polymer chains remain solvated in the pores and rapidly diffuse into the packing or (b) adhesion-dominated transport where the chains adsorb onto the nanoparticle surface and move slowly through the nanoparticle film as a well-defined front. A non-monotonic trend emerges as the adhesion strength is increased; the infiltration of chains becomes faster with the co-operative effect of adhesion and dissolution as adhesion increases but eventually slows down when the polymer–nanoparticle adhesion dominates. 

Abstract Thermoresponsive resilin‐like polypeptides (RLPs) of various lengths were genetically fused to two different computationally designed coiled coil‐forming peptides with distinct thermal stability, to develop new strategies to assemble coiled coil peptides via temperature‐triggered phase separation of the RLP units. Their successful production in bacterial expression hosts was verified via gel electrophoresis, mass spectrometry, and amino acid analysis. Circular dichroism (CD) spectroscopy, ultraviolet‐visible (UV/Vis) turbidimetry, and dynamic light scattering (DLS) measurements confirmed the stability of the coiled coils and showed that the thermosensitive phase behavior of the RLPs was preserved in the genetically fused hybrid polypeptides. Cryogenic‐transmission electron microscopy and coarse‐grained modeling revealed that functionalizing the coiled coils with thermoresponsive RLPs leads to their thermally triggered noncovalent assembly into nanofibrillar assemblies.