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Fiber optic oxygen sensors based on fluorescence quenching play an important role in oxygen sensors. They have several advantages over other methods of oxygen sensing—they do not consume oxygen, have a short response time and are of high sensitivity. They are often used in special environments, such as hazardous environments and in vivo. In this paper, a new fiber optic oxygen sensor is introduced, which uses the all-phase fast Fourier transform (apFFT) algorithm, instead of the previous lock-in amplifier, for the phase detection of excitation light and fluorescence. The excitation and fluorescence frequency was 4 KHz, which was conducted between the oxygen-sensitive membrane and the photoelectric conversion module by the optical fiber and specially-designed optical path. The phase difference of the corresponding oxygen concentration was obtained by processing the corresponding electric signals of the excitation light and the fluorescence. At 0%, 5%, 15%, 21% and 50% oxygen concentrations, the experimental results showed that the apFFT had good linearity, precision and resolution—0.999°, 0.05° and 0.0001°, respectively—and the fiber optic oxygen sensor with apFFT had high stability. When the oxygen concentrations were 0%, 5%, 15%, 21% and 50%, the detection errors of the fiber optic oxygen sensor were 0.0447%, 0.1271%, 0.3801%, 1.3426% and 12.6316%, respectively. Therefore, the sensor that we designed has greater accuracy when measuring low oxygen concentrations, compared with high oxygen concentrations.

Rapid spread of coronavirus disease 2019 (COVID-19) in the United States, especially in New York City (NYC), led to a tremendous increase in hospitalizations and mortality. There is very limited data available that associates outcomes during hospitalization in patients with COVID-19. In this retrospective cohort study, we reviewed the health records of patients with COVID-19 who were admitted from March 9-April 9, 2020, to a community hospital in NYC. Subjects with confirmed reverse transcriptase-polymerase chain reaction (RT-PCR) of the nasopharyngeal swab for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) were included. We collected data related to demographics, laboratory results, and outcome of hospitalization. Outcome was measured based on whether the patient was discharged home or died during hospitalization. There were 888 consecutive admissions with COVID-19 during the study period, of which 513 were excluded with pending outcome or incomplete information. We included a total of 375 patients in the study, of whom 215 (57%) survived and 160 (43%) died during hospitalization. The majority of patients were male (63%) and of Hispanic origin (66%) followed by Blacks (25%), and others (9%). Hypertension (60%) stands out to be the most common comorbidity followed by diabetes mellitus (47%), cardiovascular disease (17%), chronic kidney disease (17%), and human immunodeficiency virus/acquired immunodeficiency syndrome (9%). On multiple regression analysis, increasing odds of mortality during hospitalization was associated with older age (odds ratio [OR] 1.04; 95% confidence interval [CI], 1.01-1.06 per year increase; p < 0.0001), admission D-dimer more than 1000 nanograms per milliliter (ng/mL) (OR 3.16; 95% CI, 1.75-5.73; p<0.0001), admission C-reactive protein (CRP) levels of more than 200 milligrams per liter (mg/L) (OR 2.43; 95% CI, 1.36-4.34; p = 0.0028), and admission lymphopenia (OR 2.63; CI, 1.47-4.69; p 0.0010). In this retrospective cohort study originating in NYC, older age, admission levels of D-dimer of more than 1000 ng/mL, CRP of more than 200 mg/L and lymphopenia were associated with mortality in individuals hospitalized for COVID-19. We recommend using these risk factors on admission to triage patients to critical care units or surge units to maximize the use of surge capacity beds.

Nano-kirigami, inspired by the art of paper cutting and folding, offers a promising approach to three-dimensional (3D) nanomanufacturing by simply transforming two-dimensional (2D) precursors into complex 3D architectures. Here we report a profound study on three types of deformation behaviors of silicon-based nano-kirigami structures, including plastic, elastic, and hysteretic deformations. Three-stage bidirectional plastic deformations with double reversals, driven by ion-induced stress gradients, are observed and well explained by developing a torque model, revealing the critical stress competition caused by ion implantation and vacancy distribution during gallium ion irradiations. Fast-recovering elastic deformations are generated under mechanical or electrical stimuli, which can support mechanical response at a 10 nano-Newton level and optical modulation with high repeatability. Extraordinary hysteretic deformations with fast-changing and long-tail recovery periods are observed, which are uncovered by a capacitor-like charge accumulation mechanism. The controllable elastic and hysteretic deformation modes are further employed to demonstrate the applications in dynamic optical information encryption. This work reports a useful methodology to design, fabricate, and manipulate silicon-based nano-kirigami structures with great potential for applications in micro-electromechanical systems (MEMS), nano-opto-electromechanical systems (NOEMS), micro-/nano-machinery and other advanced nanotechnologies. Nano-kirigami is a promising approach to transform 2D precursors into complex 3D architectures. Here, the authors report plastic, elastic, and hysteretic deformations of silicon-based nano-kirigami structures and demonstrate applications in dynamic optical information encryption.

Compared to natural chiral molecules, artificial chiral photonic structures offer stronger chiroptical responses. However, the remarkable optical properties of most chiral structures are fixed upon fabrication, limiting their applications in scenarios where a dynamic response is required. Here, we propose an active optical chirality strategy by nano-kirigami and self-organization method, based on which a dual chiral framework is fabricated with cilia structures and cholesteric liquid crystal (LC). This dual chiral framework allows for a dynamic and wide range of chiroptical responses with nanoscale pixel size, enabling amplification, elimination, and reversal of circular dichroism. Furthermore, a thermally tunable chiroptical metalens based on this cilia-LC framework is constructed to achieve a focusing switch of circularly polarized light. This proposed technique holds great potential in diverse fields, including dynamic imaging, optical encryption, tunable displays, and sensors. The authors present a dual-chiral photonic platform that enables amplification, elimination, and reversal of chiroptical response at visible wavelengths. Using this platform, they demonstrate a switchable metalens for polarized light.