Engineering controllable, strongly interacting many-body quantum systems is at the frontier of quantum simulation and quantum information processing. Arrays of laser-cooled neutral atoms in optical ...tweezers have emerged as a promising platform because of their flexibility and the potential for strong interactions via Rydberg states. Existing neutral atom array experiments utilize alkali atoms, but alkaline-earth atoms offer many advantages in terms of coherence and control, and also open the door to new applications in precision measurement and time keeping. In this Letter, we present a technique to trap individual alkaline-earth-like ytterbium (Yb) atoms in optical tweezer arrays. The narrow ^{1}S_{0}-^{3}P_{1} intercombination line is used for both cooling and imaging in a magic-wavelength optical tweezer at 532 nm. The low Doppler temperature allows for imaging near the saturation intensity, resulting in a very high atom detection fidelity. We demonstrate the imaging fidelity concretely by observing rare (<1 in 10^{4} images) spontaneous quantum jumps into and out of a metastable state. We also demonstrate stochastic loading of atoms into a two-dimensional, 144-site tweezer array. This platform will enable advances in quantum information processing, quantum simulation, and precision measurement. The demonstrated narrow-line Doppler imaging may also be applied in tweezer arrays or quantum gas microscopes using other atoms with similar transitions, such as erbium and dysprosium.
Stimuli‐responsive liposomes for drug delivery Lee, Y.; Thompson, D.H.
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology,
September/October 2017, Letnik:
9, Številka:
5
Journal Article
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The ultimate goal of drug delivery is to increase the bioavailability and reduce the toxic side effects of the active pharmaceutical ingredient (API) by releasing them at a specific site of action. ...In the case of antitumor therapy, association of the therapeutic agent with a carrier system can minimize damage to healthy, nontarget tissues, while limit systemic release and promoting long circulation to enhance uptake at the cancerous site due to the enhanced permeation and retention effect (EPR). Stimuli‐responsive systems have become a promising way to deliver and release payloads in a site‐selective manner. Potential carrier systems have been derived from a wide variety of materials, including inorganic nanoparticles, lipids, and polymers that have been imbued with stimuli‐sensitive properties to accomplish triggered release based on an environmental cue. The unique features in the tumor microenvironment can serve as an endogenous stimulus (pH, redox potential, or unique enzymatic activity) or the locus of an applied external stimulus (heat or light) to trigger the controlled release of API. In liposomal carrier systems triggered release is generally based on the principle of membrane destabilization from local defects within bilayer membranes to effect release of liposome‐entrapped drugs. This review focuses on the literature appearing between November 2008–February 2016 that reports new developments in stimuli‐sensitive liposomal drug delivery strategies using pH change, enzyme transformation, redox reactions, and photochemical mechanisms of activation. WIREs Nanomed Nanobiotechnol 2017, 9:e1450. doi: 10.1002/wnan.1450
This article is categorized under:
Therapeutic Approaches and Drug Discovery > Emerging Technologies
Biology-Inspired Nanomaterials > Lipid-Based Structures
Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Controlled drug delivery system using stimuli‐responsive liposomes
Abstract
Executing quantum algorithms on error-corrected logical qubits is a critical step for scalable quantum computing, but the requisite numbers of qubits and physical error rates are demanding ...for current experimental hardware. Recently, the development of error correcting codes tailored to particular physical noise models has helped relax these requirements. In this work, we propose a qubit encoding and gate protocol for
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Yb neutral atom qubits that converts the dominant physical errors into erasures, that is, errors in known locations. The key idea is to encode qubits in a metastable electronic level, such that gate errors predominantly result in transitions to disjoint subspaces whose populations can be continuously monitored via fluorescence. We estimate that 98% of errors can be converted into erasures. We quantify the benefit of this approach via circuit-level simulations of the surface code, finding a threshold increase from 0.937% to 4.15%. We also observe a larger code distance near the threshold, leading to a faster decrease in the logical error rate for the same number of physical qubits, which is important for near-term implementations. Erasure conversion should benefit any error correcting code, and may also be applied to design new gates and encodings in other qubit platforms.
Single atoms and atomlike defects in solids are ideal quantum light sources and memories for quantum networks. However, most atomic transitions are in the ultraviolet-visible portion of the ...electromagnetic spectrum, where propagation losses in optical fibers are prohibitively large. Here, we observe for the first time the emission of single photons from a single Er^{3+} ion in a solid-state host, whose optical transition at 1.5 μm is in the telecom band, allowing for low-loss propagation in optical fiber. This is enabled by integrating Er^{3+} ions with silicon nanophotonic structures, which results in an enhancement of the photon emission rate by a factor of more than 650. Dozens of distinct ions can be addressed in a single device, and the splitting of the lines in a magnetic field confirms that the optical transitions are coupled to the electronic spin of the Er^{3+} ions. These results are a significant step towards long-distance quantum networks and deterministic quantum logic for photons based on a scalable silicon nanophotonics architecture.
•GSH-deficient mouse models have been developed by targeting GCL, the rate-limiting enzyme of GSH biosynthesis.•Liver-specific Gclc knockout mice have 95% depletion of hepatic GSH and develop ...spontaneous steatohepatitis.•Universal Gclm deleted mice have 15% of normal hepatic GSH and are protected from liver injuries induced by hepatic insults.•Animal studies indicate a potential role of hepatic GSH in fine-tuning metabolic and stress responses to liver injuries.
Glutathione (GSH) is the most abundant cellular thiol antioxidant and it exhibits numerous and versatile functions. Disturbances in GSH homeostasis have been associated with liver diseases induced by drugs, alcohol, diet and environmental pollutants. Until recently, our laboratories and others have developed mouse models with genetic deficiencies in glutamate-cysteine ligase (GCL), the rate-limiting enzyme in the GSH biosynthetic pathway. This review focuses on regulation of GSH homeostasis and, specifically, recent studies that have utilized such GSH-deficient mouse models to investigate the role of GSH in liver disease processes. These studies have revealed a differential hepatic response to distinct profiles of hepatic cellular GSH concentration. In particular, mice engineered to not express the catalytic subunit of GCL in hepatocytes Gclc(h/h) mice experience almostcomplete loss of hepatic GSH (to 5% of normal) and develop spontaneous liver pathologies characteristic of various clinical stages of liver injury. In contrast, mice globally engineered to not express the modifier subunit of GCL Gclm(−/−) mice show a less severe hepatic GSH deficit (to ≈15% of normal) and exhibit overall protection against liver injuries induced by a variety of hepatic insults. Collectively, these transgenic mouse models provide interesting new insights regarding pathophysiological functions of GSH in the liver.
Mound Key was once the capital of the Calusa Kingdom, a large Pre-Hispanic polity that controlled much of southern Florida. Mound Key, like other archaeological sites along the southwest Gulf Coast, ...is a large expanse of shell and other anthropogenic sediments. The challenges that these sites pose are largely due to the size and areal extent of the deposits, some of which begin up to a meter below and exceed nine meters above modern sea levels. Additionally, the complex depositional sequences at these sites present difficulties in determining their chronology. Here, we examine the development of Mound Key as an anthropogenic island through systematic coring of the deposits, excavations, and intensive radiocarbon dating. The resulting data, which include the reversals of radiocarbon dates from cores and dates from mound-top features, lend insight into the temporality of site formation. We use these insights to discuss the nature and scale of human activities that worked to form this large island in the context of its dynamic, environmental setting. We present the case that deposits within Mound Key's central area accumulated through complex processes that represent a diversity of human action including midden accumulation and the redeposition of older sediments as mound fill.
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