To ensure accurate DNA replication, a replisome must effectively overcome numerous obstacles on its DNA substrate. After encountering an obstacle, a progressing replisome often aborts DNA synthesis but continues to unwind. However, little is known about how DNA synthesis is resumed downstream of an obstacle. Here, we examine the consequences of a non-replicating replisome collision with a co-directional RNA polymerase (RNAP). Using single-molecule and ensemble methods, we find that T7 helicase interacts strongly with a non-replicating T7 DNA polymerase (DNAP) at a replication fork.

Next-generation, atomically thin devices require in-plane, one-dimensional heterojunctions to electrically connect different two-dimensional (2D) materials. However, the lattice mismatch between most 2D materials leads to unavoidable strain, dislocations, or ripples, which can strongly affect their mechanical, optical, and electronic properties. We have developed an approach to map 2D heterojunction lattice and strain profiles with subpicometer precision and the ability to identify dislocations and out-of-plane ripples.

Weyl fermions are a recently discovered ingredient for correlated states of electronic matter. A key difficulty has been that real materials also contain non-Weyl quasiparticles, and disentangling the experimental signatures has proven challenging. Here we use magnetic fields up to 95 T to drive the Weyl semimetal TaAs far into its quantum limit, where only the purely chiral 0th Landau levels of the Weyl fermions are occupied.

Time reversal and spatial inversion are two key symmetries for conventional Bardeen-Cooper-Schrieffer (BCS) superconductivity1. Breaking inversion symmetry can lead to mixed-parity Cooper pairing and unconventional superconducting properties1-5. Two-dimensional (2D) NbSe2 has emerged as a new non-centrosymmetric superconductor with the unique out-of-plane or Ising spin-orbit coupling (SOC)6-9. Here we report the observation of an unusual continuous paramagnetic-limited superconductor-normal metal transition in 2D NbSe2.

Despite the significant amount of time undergraduate students spend in introductory physics labs, there is little consensus on instructional goals and accepted diagnostic assessments for these labs. In response to these issues, we have developed the Physics Lab Inventory of Critical thinking (PLIC) to assess students' proficiency with critical thinking in a physics lab context. Specifically, the PLIC aims to evaluate students' skills in making sense of data, variability, models, and experimental methods and to assess the effectiveness of lab courses at developing these skills.

Many institutions are changing the focus of their introductory physics labs from verifying physics content towards teaching students about the skills and nature of science. As instruction shifts, so too will the ways students approach and behave in the labs. In this study, we evaluated students' lab notes from an early activity in an experimentation-focused lab course.

(Cell 172, 344–357.e1–e7; January 11, 2018) Our paper reported a mechanism where E. coli transcription-coupled repair factor Mfd utilizes DNA translocation to dynamically regulate transcription. We have identified three minor errors in the manuscript.

As educational technologies become increasingly important in K-12 physics education, it is important to understand why and how teachers choose to adopt certain technologies. We examined 2000 responses from a survey of high school teachers on how they used PhET interactive simulations (mostly in physics) and what value they felt it provided their students. The analysis helps inform what aspects of an educational technology support or hinder its adoption. First, the teachers valued flexibility.

We report in situ time-resolved measurements of the dynamic evolution of the volume fraction of extension twins in polycrystalline pure magnesium and in the AZ31B magnesium alloy, using synchrotron x-ray diffraction during compressive loading at high strain rates. The dynamic evolution of the twinning volume fraction leads to a dynamic evolution of the texture. Although both the pure metal and the alloy had similar initial textures, we observe that the evolution of texture is slower in the alloy.

The optical characteristics of MoS2 monolayers on SiO2/Si substrates with an SiO2 thickness ranging from 40 to 130 nm are investigated. The measured Raman and optical reflection spectra of the MoS2 monolayers vary considerably depending on the SiO2 thickness. The Raman peak intensity of the MoS2 monolayer on the substrate with an 80 nm thick SiO2 layer is four times larger than those in the cases of 40- and 130 nm thick SiO2 layers, indicating a significant difference in the absorption at the excitation wavelength.