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16,017 articles from ScienceNOW

A phage-encoded anti-CRISPR enables complete evasion of type VI-A CRISPR-Cas immunity

The CRISPR RNA (crRNA)–guided nuclease Cas13 recognizes complementary viral transcripts to trigger the degradation of both host and viral RNA during the type VI CRISPR-Cas antiviral response. However, how viruses can counteract this immunity is not known. We describe a listeriaphage (LS46) encoding an anti-CRISPR protein (AcrVIA1) that inactivates the type VI-A CRISPR system of Listeria...

A piperidinium salt stabilizes efficient metal-halide perovskite solar cells

Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidinium-based ionic compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the bandgap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances...

An ideal Josephson junction in an ultracold two-dimensional Fermi gas

The role of reduced dimensionality in high-temperature superconductors is still under debate. Recently, ultracold atoms have emerged as an ideal model system to study such strongly correlated two-dimensional (2D) systems. Here, we report on the realization of a Josephson junction in an ultracold 2D Fermi gas. We measure the frequency of Josephson oscillations as a function of the phase difference...

C(sp3)-H functionalizations of light hydrocarbons using decatungstate photocatalysis in flow

Direct activation of gaseous hydrocarbons remains a major challenge for the chemistry community. Because of the intrinsic inertness of these compounds, harsh reaction conditions are typically required to enable C(sp3)–H bond cleavage, barring potential applications in synthetic organic chemistry. Here, we report a general and mild strategy to activate C(sp3)–H bonds in methane, ethane,...

Cell position fates and collective fountain flow in bacterial biofilms revealed by light-sheet microscopy

Bacterial biofilms represent a basic form of multicellular organization that confers survival advantages to constituent cells. The sequential stages of cell ordering during biofilm development have been studied in the pathogen and model biofilm-former Vibrio cholerae. It is unknown how spatial trajectories of individual cells and the collective motions of many cells drive biofilm expansion. We...

Development of an inactivated vaccine candidate for SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented public health crisis. Because of the novelty of the virus, there are currently no SARS-CoV-2–specific treatments or vaccines available. Therefore, rapid development of effective vaccines against SARS-CoV-2 are urgently needed. Here, we...

Feasibility of blood testing combined with PET-CT to screen for cancer and guide intervention

Cancer treatments are often more successful when the disease is detected early. We evaluated the feasibility and safety of multicancer blood testing coupled with positron emission tomography–computed tomography (PET-CT) imaging to detect cancer in a prospective, interventional study of 10,006 women not previously known to have cancer. Positive blood tests were independently confirmed by a...