Towards polariton blockade of confined exciton-polaritons.

Cavity-polaritons in semiconductor microstructures have emerged as a promising system for exploring non-equilibrium dynamics of many-body systems1. Key advances in this field, including the observation of polariton condensation2, superfluidity3, realization of topological photonic bands4, and dissipative phase transitions5-7, generically allow for a description based on a mean-field Gross-Pitaevskii formalism. Observation of polariton intensity squeezing8,9 and decoherence of a polarization entangled photon pair by a polariton condensate10, on the other hand, demonstrate quantum effects that show up at high polariton occupancy. Going beyond and into the regime of strongly correlated polaritons requires the observation of a photon blockade effect11,12 where interactions are strong enough to suppress double occupancy of a photonic lattice site. Here, we report evidence of quantum correlations between polaritons spatially confined in a fibre cavity. Photon correlation measurements show that careful tuning of the coupled system can lead to a modest reduction of simultaneous two-polariton generation probability by 5%. Concurrently, our experiments allow us to measure the polariton interaction strength, thereby resolving the controversy stemming from recent experimental reports13. Our findings constitute an essential step towards the realization of strongly interacting photonic systems.

Evaluation of Antioxidants' Ability to Enhance Hyaluronic-acid Based Topical Moisturizers.

Background: Hyaluronic acid (HA) is a unique molecule of the extracellular matrix with multiple biological activities. In skin, HA plays an essential role as a humectant, capable of binding up to 1,000 times its mass with water, providing skin with moisture and viscoelastic properties. HA concentration and synthesis decrease significantly in aging skin, due to exogenous and endogenous factors, including photoaging and HA metabolism. A key driver for HA degradation and reduced concentration is mediated via induction of reactive oxygen species (ROS) and other free radicals. Objective: In this study, we evaluate antioxidant ingredients essential in the development of next-generation HA-based topical formulations aimed at leveraging HA's ability to maximize anti-aging properties. Methods: Two antioxidants, glycine saponin (Glycine soja germ extract) and glycyrrhetinic acid (enoxolone), were evaluated for stimulation of endogenous HA production and inhibition of endogenous hyaluronidase activity, respectively. Results: The antioxidant glycine saponin induced endogenous HA synthesis in fibroblasts, while the antioxidant glycyrrhetinic acid decreased the degradation rate of HA by 54 percent. Conclusion: While HA has been included in numerous topical skin products, critical aspects of HA metabolism, especially in aging skin, have often been overlooked, including decreases in HA synthesis with increasing age, and increases in HA degradation mediated by exogenously induced reactive oxygen species and free radicals and increased enzymatic degradation by endogenous hyaluronidases. Here, we describe a unique approach to inclusion of two antioxidants essential for the development of the next generation of antioxidant complex-based topical skin formulations to limit the signs of aging skin.

Resonant Tunneling Diodes: Mid-Infrared Sensing at Room Temperature.

Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2-4 µm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor's electrical response and how they allow controlling the device's sensing abilities.

Interband Cascade Laser Arrays for Simultaneous and Selective Analysis of C1-C5 Hydrocarbons in Petrochemical Industry.

The detection and measurement of hydrocarbons are of high interest for a variety of applications, for example within the oil and gas industry from extraction throughout the complete refining process, as well as for environmental monitoring and for portable safety devices. This paper presents a highly sensitive, selective, and robust tunable laser analyzer that has the capability to analyze several components in a gas sample stream. More specifically, a multi-gas system for simultaneous detection of C1 to iC5 hydrocarbons, using a room temperature distributed feedback interband cascade laser array, emitting in the 3.3 µm band has been realized. It combines all the advantages of the tunable laser spectroscopy method for a fast, sensitive, and selective in-line multicomponent tunable laser analyzer. Capable of continuous and milliseconds fast monitoring of C1-iC5 hydrocarbon compositions in a process stream, the analyzer requires no consumables (e.g., purging, carrier gas) and no in-field calibration, enabling a low cost of ownership for the analyzer. The system was built based on an industrial GasEye series platform and deployed for the first time in field at Preem refinery in Lysekil, Sweden, in autumn 2018. Results of the measurement campaign and comparison with gas chromatography instrumentation are presented.

Damage at the root of cell renewal--UV sensitivity of human epidermal stem cells.

BACKGROUND: The epidermis harbors adult stem cells that reside in the basal layer and ensure the continuous maintenance of tissue homeostasis. Various studies imply that stem cells generally possess specific defense mechanisms against several forms of exogenous stress factors. As sun exposition is the most prevalent impact on human skin, this feature would be of particular importance in terms of sensitivity to UV-induced DNA damage. OBJECTIVE: To investigate whether human epidermal stem cells are susceptible to UV-induced DNA damage and subsequent functional impairment. METHODS: A method to isolate human epidermal stem cells from suction blister epidermis was established and validated. Volunteers were treated with solar-simulated irradiation on test areas of the forearm and stem cells were isolated from suction blister material of this region. DNA damage was analyzed by staining for cyclobutane thymidine dimers. The functional consequences of UV-induced damages were assessed by colony forming efficiency assays and gene expression analyses. RESULTS: Compared to an unirradiated control, stem cells isolated from areas that were exposed to solar-simulated radiation showed significantly more DNA lesions. Although the number of stem cells was not reduced by this treatment, a functional impairment of stem cells could be shown by reduced colony forming efficiency and altered gene expression of stem cell markers. CONCLUSIONS: Despite their essential role in skin maintenance, epidermal stem cells are sensitive to physiological doses of UV irradiation in vivo.