Birefringence characterization in a dual-hole microstructured optical fiber using an OFDR method.

The birefringence in a dual-hole microstructured optical fiber is numerically calculated and characterized with an optical frequency domain reflectometry (OFDR) method. Due to the asymmetric dual air holes in the cross-section, the polarized L P01x and L P01y modes propagate with different group velocities and time delays. Through a polarized coherent OFDR system in experiment, the Fresnel reflection peaks for each mode are separated in the frequency domain with their corresponding beat frequency. Thus, the group birefringence -9.68×10-4 is calculated with a beat frequency difference of 50.03 Hz between the L P01x and L P01y modes at a 6.2 m fiber end, which is in good agreement with that of -9.54×10-4 from the theoretical simulation. Our demonstration provides an accurate and flexible method for group birefringence characterization in microstructured optical fibers with complex cross-sectional structures.

Observation and characterization of the high order modes in a six-mode fiber using an OFDR method.

High order modes in a six-mode fiber are separately observed and characterized using an Optical Frequency Domain Reflectometry (OFDR) method. Due to the difference in group refractive index between fundamental mode and the high order modes, Fresnel reflection peaks for each mode can be separated in beat frequency domain with their corresponding time delay. In the experiment, the fundamental mode and high order modes are excited in turn and observed at a 6.6 m six-mode fiber end, which agree with their beat frequency difference in theoretical simulation. The demonstration provides a flexible and feasible method for mode identification and characterization of all kinds of fibers.

Mixed methods research on satisfaction with basic medical insurance for urban and rural residents in China.

BACKGROUND: There have been few studies on satisfaction with integrated basic medical insurance for urban and rural residents (URRBMI), and satisfaction with URRBMI is not very high because of the complexity of its policies and differences among the insured. The aim of the present study was to explore the factors that influence satisfaction with URRBMI in China and to provide scientific suggestions to the government for how to effectively manage and improve the policy. METHODS: An explanatory sequential design of mixed methods research was used. A quantitative research using a three-stage stratified cluster sampling method was used to randomly select the guardians of pupils who participated in URRBMI (n = 1335). The quantitative research was conducted to calculate the latent variables' scores and path coefficients between latent variables using SmartPLS3.0. With public trust, public satisfaction, and perceived quality as the target variables, important-performance analysis (IPA) was used to explore the important but underperforming factors, which were the key elements to improving satisfaction with URRBMI. A purposeful sampling strategy according to satisfaction level was used to obtain qualitative research subjects from among the quantitative research subjects. A qualitative research was conducted using semi-structured interviews, and the thematic analysis method was used to summarize the interview data. RESULTS: The three strongest paths were perceived quality to public satisfaction, with a total effect of 0.737 (t = 41.270, P < 0.001); perceived quality to perceived value, with a total effect of 0.676 (t = 31.964, P < 0.001); and public satisfaction to public trust, with a total effect of 0.634 (t = 31.305, P < 0.001). IPA revealed that public satisfaction and perceived quality were key factors for public trust and that perceived quality was of high importance for public satisfaction but had low performance. The policy quality was a determining factor for perceived quality. The qualitative research results showed that the most unsatisfactory aspect for the insured was the policy quality. CONCLUSIONS: This study found that improving quality is key to improving public satisfaction with and public trust in URRBMI. The government should improve the compensation level by broadening the channel of financing for the URRBMI fund, rationally formulating reimbursement standards, and broadening the scope of the drug catalog and the medical treatment projects. The government should establish a stable financing growth mechanism and effective methods of providing health education to improve public satisfaction and public trust.

Fluorinated Polyimide-Film Based Temperature and Humidity Sensor Utilizing Fiber Bragg Grating.

We propose and demonstrate a temperature and humidity sensor based on a fluorinated polyimide film and fiber Bragg grating. Moisture-induced film expansion or contraction causes an extra strain, which is transferred to the fiber Bragg grating and leads to a humidity-dependent wavelength shift. The hydrophobic fluoride doping in the polyimide film helps to restrain its humidity hysteresis and provides a short moisture breathing time less than 2 min. Additionally, another cascaded fiber Bragg grating is used to exclude its thermal crosstalk, with a temperature accuracy of ±0.5 °C. Experimental monitoring over 9000 min revealed a considerable humidity accuracy better than ±3% relative humidity, due to the sensitized separate film-grating structure. The passive and electromagnetic immune sensor proved itself in field tests and could have sensing applications in the electro-sensitive storage of fuel, explosives, and chemicals.

Numerical Analysis and Recursive Compensation of Position Deviation for a Sub-Millimeter Resolution OFDR.

We analyze the source of the position deviation and propose a demodulation recursive compensation algorithm to ensure a sub-millimeter resolution in improved optical frequency domain reflectometry. The position deviation between the geometric path and optical path changes with the temperature or strain, due to the elastic-optic and thermal-optic effects. It accumulates along the fiber and becomes large enough to affect the spectral correlation between the measured and reference spectra at the fiber end. The proposed algorithm compensates for the position deviation of each measuring point and aligns the measured spectra with its reference. The numerical and experimental results both reveal that the signal-to-noise ratio of the correlation is improved doubly and a sub-millimeter spatial resolution becomes available at a 30 m fiber end. The recursive compensation algorithm helps to restrain the correlation degeneration at the fiber end and promises an effective approach to a sub-millimeter resolution in optical frequency domain reflectometry.

0.5†mm spatial resolution distributed fiber temperature and strain sensor with position-deviation compensation based on OFDR.

We propose and demonstrate a 0.5 mm resolution distributed fiber temperature and strain sensor with position-deviation compensation based on the Optical Frequency Domain Reflectometry. The position-deviation compensation helps maintain the cross-correlation of the Rayleigh spectra, which degenerates at the higher resolution. Experimental results reveal a 0.5 mm strained fiber segment recognized at the end of a 25 m fiber, with 50,000 equivalent measuring points. The temperature repeatability of ± 0.9 °C (12.5 pm) is obtained from 50 °C to 500 °C with an 18 m gold-coated fiber, and the strain accuracy of ± 15 µÉ› is also achieved within ± 2500 µÉ› using a polyimide coated fiber. The small-scale, high spatial-resolution, and electromagnetic-immune distributed optical fiber sensors can be applied to address the test challenges in astronautics, advanced materials, and nuclear facilities, where high temperature, large strain change, space radiation, and complex electromagnetics presents.

[Association rule regarding chronic disease-relevant risk factors for the adults in Haidian District].

OBJECTIVE: To investigate the association patterns of chronic disease-relevant risk factors for the adults in Haidian District.
 Methods: Data for chronic disease-relevant risk factors for 3 219 adults in Haidian District in 2014 were collected and analyzed. SPSS 18.0 was used for statistical description and logistic regression. SPSS Modeler 14.1 was used to explore the association among the chronic disease-relevant risk factors.
 Results: Among men, 5 patterns of chronic disease-relevant risk factors were identified, which suggested that heavy drinking, inadequate intake of fruit and vegetables, and physical inactivity were associated with smoking while inadequate intake of fruit and vegetables and smoking were associated with physical inactivity. Among women, one pattern of chronic disease-relevant risk factor was identified, which suggested that inadequate intake of fruit and vegetables was associated with physical inactivity.
 Conclusion: Chronic disease-relevant risk factors are intercorrelated among the adults in Haidian District. Information on patterns of chronic disease-relevant risk factors could assist interventions targeting multiple behaviors simultaneously.

Generation of linearly polarized orbital angular momentum modes in a side-hole ring fiber with tunable topology numbers.

A refractive index (RI) tunable functional materials infiltrated side-hole ring fiber (SHRF) is proposed to generate 10 LP OAM states with 6 topology numbers. On the basis of perturbation theory, the basis of the SHRF is demonstrated to be the LP modes. After a fixed propagation distance of 0.03 m, 0.009 m and 0.012 m, the phase difference between the odd and even LP11x, LP21x,y, LP31x,y modes in the SHRF accumulate to ± π/2 respectively with na ranging from 1.412 to 1.44. Correspondingly, the output states are OAM ± 1x, OAM ± 2x,y, OAM ± 3x,y with a bandwidth of 380 nm, 100 nm and 80 nm respectively. The proposed fiber is easy to be fabricated with the mature fiber drawing technology and could facilitate the realization of all fiber based OAM system.

Tunable optofluidic microring laser based on a tapered hollow core microstructured optical fiber.

A tunable optofluidic microring dye laser within a tapered hollow core microstructured optical fiber was demonstrated. The fiber core was filled with a microfluidic gain medium plug and axially pumped by a nanosecond pulse laser at 532 nm. Strong radial emission and low-threshold lasing (16 nJ/pulse) were achieved. Lasing was achieved around the surface of the microfluidic plug. Laser emission was tuned by changing the liquid surface location along the tapered fiber. The possibility of developing a tunable laser within the tapered simplified hollow core microstructured optical fiber presents opportunities for developing liquid surface position sensors and biomedical analysis.

Generation and excitation of different orbital angular momentum states in a tunable microstructure optical fiber.

A tunable microstructure optical fiber for different orbital angular momentum states generation is proposed and investigated by simulation. The microstructure optical fiber is composed of a high refractive index ring and a hollow core surrounded by four small air holes. The background material of the microstructure fiber is pure silica. The hollow core and the surrounded four small air holes are infiltrated by optical functional material whose refractive index can be modulated via physical parameters, leading to the conversion between circular polarized fundamental mode and different orbital angular momentum states at tunable operating wavelengths. A theoretical model is established and the coupling mechanism is systematically analyzed and investigated based on coupled mode theory. The fiber length can be designed specifically to reach the maximum coupling efficiency for every OAM mode respectively, and can also be fixed at a certain value for several OAM modes generation under tunable refractive index conditions. The proposed fiber coupler is flexible and compact, making it a good candidate for tunable OAM generation and sensing systems.

Intermodal interferometer with low insertion loss and high extinction ratio composed of a slight offset point and a matching long period grating in two-mode photonic crystal fiber.

An all-fiber modal interferometer based on a long period grating (LPG) inscribed in a two-mode photonic crystal fiber (PCF) and a slight core-offset spliced end is proposed and demonstrated. The LPG is fabricated to realize energy coupling from LP01 core mode to LP11 core mode, and the two core modes will interfere at the slight core-offset spliced end. We analyze the impact of energy coupling efficiencies of the LPG and the output spliced end on the extinction ratio of the interference fringes. With an appropriate energy coupling efficiency matching condition, our modal interferometer can realize lower insertion loss and high extinction ratio. Moreover, the sensitivities of our interferometer to strain and temperature are investigated, and the good stability of this device to external refractive index change is also demonstrated. As an all-fiber interferometer made of pure silica, this device has great potential applications in high temperature sensing fields, especially in harsh conditions.

Microfluidic assistant beat-frequency interferometer based on a single-hole-infiltrated dual-mode microstructured optical fiber.

A microfluidic assistant beat-frequency interferometer based on a single-hole-infiltrated dual-mode microstructured optical fiber (DM-MOF) is proposed and demonstrated. The interferometer is constructed by inserting a piece of fluid-filled DM-MOF into two sections of single-mode fiber with slight core-offset. The mode-mismatch induced interferences with high-frequency dips and low-frequency envelope are observed in the transmission spectrum. Theoretical and experimental investigations reveal that the beat-frequency spectrum works from the interferences between LP(01) core mode and the components of LP(11) core mode with close but different frequencies. The deliberately infiltrated liquid rod in the air hole located at the second ring near the core of the DM-MOF enhances the sensitivity of the envelope to temperature or axial force. However, it shows little impact on the high-frequency dips. The distinguishing sensitivities of -959.22 pm/°C (-70.59 pm/°C) and 24.26 nm/N (-3.14 nm/N) for the envelope (dips) are simultaneously achieved in experiment, allowing for dual parameter measurement in such a compact structure.

Tunable fiber polarizing filter based on a single-hole-infiltrated polarization maintaining photonic crystal fiber.

A tunable fiber polarizing filter based on selectively filling a single hole of a solid-core polarization maintaining photonic crystal fiber with high index liquid are proposed and demonstrated. Two groups of polarization-dependent resonance dips in the transmission spectrum of the single-hole-infiltrated photonic crystal fiber are observed. Theoretical and experimental investigations reveal that these resonant dips result from the couplings between the silica core fundamental mode at x or y polarization and high order modes (TM(01), TE(01) and HE(11)) in the liquid core. Especially, a distinctive characteristic near the strongest resonant point (SRP) is demonstrated and revealed. The transmission loss and spectral shape at the SRP wavelength are extremely sensitive to the filling length and temperature (or Refractive Index, RI), which permits a fiber bandpass or bandstop polarizing filter with a good performance on tunability and controllability. Furthermore, the narrowband dips on both sides of the SRP wavelength have wavelength-dependent tuning velocities, providing a method to achieve flexible and controllable filters as well as two- or multi-parameter sensors with a compact structure.

Multi-component-intermodal-interference mechanism and characteristics of a long period grating assistant fluid-filled photonic crystal fiber interferometer.

A compact in-line modal interferometer based on a long period grating (LPG) inscribed in water-filled photonic crystal fiber (PCF) is proposed and demonstrated. The interferometer works from the interference between fundamental core mode and different vector components of LP(11) core mode. The LPG is especially inscribed to realize the energy exchange between the fundamental core mode and different vector components of LP(11) core mode in the PCF. We build a complete theoretical model and systematically analyze the multi-component-intermodal-interference mechanism of the interferometer based on coupled-mode theory. Due to the asymmetric index distribution over the cross section of the PCF caused by CO(2)-laser side illumination, the dispersion curves and temperature sensitivities referring to different vector components of LP(11) core mode are quite different. Thus the interferometer is polarization-dependent and the adjacent interference fringes according to different components of LP(11) mode show greatly discrimination in sensitivities of temperature and strain, making it a good candidate for multiple physics parameters measurements.

Control and design of fiber birefringence characteristics based on selective-filled hybrid photonic crystal fibers.

We demonstrated a kind of birefringence-controllable hybrid photonic crystal fibers (HPCFs) by selectively infiltrating air holes of PCFs with index-tunable liquids processing higher index than silica background. Detailed theoretical investigations on mode couplings from fundamental core mode to high-index-liquid-rod modes and birefringence properties of several HPCFs were presented. Strong wavelength dependence of phase and group birefringence was found, and HPCFs with different arrangements of high index liquid rods possess distinct birefringence characteristics. Then, the Sagnac interferometers (SIs) based on two typical HPCFs with different liquid-rod arrangements were theoretically and experimentally studied. The results indicated the SIs exhibit different transmission spectra and temperature responses due to the distinct birefringence features of HPCFs. A temperature sensitivity of -45.8 nm/°C at 56.5 °C was achieved using one HPCF, and a sensitivity of -11.6 nm/°C from 65 °C to 85 °C was achieved using the other HPCF. The thermal tunable HPCFs with birefringence-controllable properties will provide great potential for a variety of tunable optical devices and sensors.

The role of fungi in the diagnosis of colorectal cancer.

Colorectal cancer (CRC) is a prevalent tumour with high morbidity rates worldwide, and its incidence among younger populations is rising. Early diagnosis of CRC can help control the associated mortality. Fungi are common microorganisms in nature. Recent studies have shown that fungi may have a similar association with tumours as bacteria do. As an increasing number of tumour-associated fungi are discovered, this provides new ideas for the diagnosis and prognosis of tumours. The relationship between fungi and colorectal tumours has also been recently identified by scientists. Therefore, this paper describes the limitations and prospects of the application of fungi in diagnosing CRC and predicting CRC prognosis.

Effects of dietary copper intake on blood lipids in women of childbearing age and the potential role of gut microbiota.

Background: Copper (Cu) is a vital trace element involved in numerous physiological processes, including glycolysis and lipid metabolism. Imbalances in Cu homeostasis can contribute to various diseases. However, current research on the impact of Cu on lipid metabolism has yielded inconsistent findings. Moreover, studies investigating the effects of dietary Cu intake on blood lipids among women of childbearing age are rare. Understanding of this relationship could enhance lipid management, given that most women obtain Cu through their diet. Additionally, the gut microbiota may play a role in this process. This study aims to investigate the effects of dietary Cu intake on blood lipids in women of childbearing age and to analyze the role of gut microbiota in this process. Methods: This study utilized data from the National Health and Nutrition Examination Survey (NHANES) to conduct a preliminary analysis of the correlation between dietary Cu levels and blood lipid indicators in women of childbearing age. Subsequently, an on-site research was conducted to further investigate this relationship, followed by animal experiments to verify the effect of different Cu doses on blood lipid levels. Multiple linear regression models, ANOVA, XGBOOST were employed to analyze the impact of Cu on blood lipids and the role of intestinal microbiota in this process. Results: In the population study, the NHANES results were consistent with on-site findings. The TG, and TC levels in women with childbearing were increased with higher dietary Cu intake. Animal experiments have shown that as Cu intake increases, TC levels increase. Furthermore, when the Cu intake reached 8 mg/day (the recommended dietary Cu intake limit of China, RDI), the TG levels in the research animals decrease, alongside a reduction in the abundance of Weissella cibaria (probiotics related to lipid metabolism), and the levels of LPS and IL-6 increase. Conclusion: The blood lipid levels of women of childbearing age increase with higher dietary Cu intake. RDI of 8 mg/day for women of childbearing age in China may need to be appropriately reduced. Regulating the gut microbiota, especially by increasing the abundance of Weissella cibaria may be an effective intervention for blood lipids.

Overexpression of ESYT3 improves radioimmune responses through activating cGAS-STING pathway in lung adenocarcinoma.

BACKGROUND: Radiotherapy can modulate systemic antitumor immunity, while immune status in the tumor microenvironment also influences the efficacy of radiotherapy, but relevant molecular mechanisms are poorly understood in lung adenocarcinoma (LUAD). METHODS: In this study, we innovatively proposed a radiotherapy response classification for LUAD, and discovered ESYT3 served as a tumor suppressor and radioimmune response sensitizer. ESYT3 expression was measured both in radioresistant and radiosensitive LUAD tissues and cells. The influence of ESYT3 on radiotherapy sensitivity and resistance was then investigated. Interaction between ESYT3 and STING was evaluated through multiple immunofluorescent staining and coimmunoprecipitation, and downstream molecules were further analyzed. In vivo models were constructed to assess the combination treatment efficacy of ESYT3 overexpression with radiotherapy. RESULTS: We found that radioresistant subtype presented immunosuppressive state and activation of DNA damage repair pathways than radiosensitive subtype. ESYT3 expression was remarkably attenuated both in radioresistant LUAD tissues and cells. Clinically, low ESYT3 expression was linked with radioresistance. Overexpression of ESYT3 enabled to alleviate radioresistance, and sensitize LUAD cells to DNA damage induced by irradiation. Mechanically, ESYT3 directly interacted with STING, and activated cGAS-STING signaling, subsequently increasing the generation of type I IFNs as well as downstream chemokines CCL5 and CXCL10, thus improving radioimmune responses. The combination treatment of ESYT3 overexpression with radiotherapy had a synergistic anticancer effect in vitro and in vivo. CONCLUSIONS: In summary, low ESYT3 expression confers resistance to radiotherapy in LUAD, and its overexpression can improve radioimmune responses through activating cGAS-STING-dependent pathway, thus providing an alternative combination therapeutic strategy for LUAD patients.

Prevalence of depressive tendencies among college students and the influence of attributional styles on depressive tendencies in the post-pandemic era.

Introduction: Depression symptoms are prevalent globally, including China, with a notable impact on college students. This study aims to not only estimate the prevalence of depressive tendencies and attributional styles among college students in the post-pandemic era but also explore the relationship between the two factors. The findings of this study can provide new insights into early intervention and support services for individuals exhibiting tendencies toward depression. Methods: The survey was administered to college students from various academic backgrounds at a specific university in southern Jiangxi Province by employing two scales to investigate depressive tendencies and attributional styles. Depressive tendency was evaluated using the Patient Health Questionnaire-9 (PHQ-9), while the attributional styles were assessed using the Multidimensional-Multiattributional Causality Scale (MMCS). Univariate analysis and multiple logistic regressions were conducted to identify the related factors of depressive tendency. Results: A relatively high (48.9%) prevalence of depression among college students was found in this study. College students with higher grades (OR = 1.574, 95%CI: 1.369-1.810), profession of medicine and allied health sciences (OR = 1.779, 95%CI: 1.203-2.629), experiencing higher study stress (OR = 2.006, 95%CI: 1.601-2.514), and having poor physical condition (OR = 1.527, 95%CI: 1.247-1.869) were identified as risk factors for depressive tendency. The correlation between higher grades and increased learning pressure, coupled with poorer physical condition, heightens the vulnerability of college students to depression. Moreover, the more they attribute these experiences to achievement effort (OR = 0.897, 95%CI: 0.828-0.972), achievement ability (OR = 0.903, 95%CI: 0.838-0.972), and affiliation context (OR = 0.919, 95%CI: 0.860-0.982), the less likely they are to develop depression. Conclusion: In the group of college students, especially those in higher grades, profession of medicine and allied health sciences or experiencing high learning pressure and poor physical condition, emphasizing the significance of their mental well-being becomes crucial. Offering suitable support and assistance is essential. Additionally, fostering the cultivation of positive attributional and coping strategies by attributing difficulties to controllable factors and instilling a belief in their ability to overcome challenges can help reduce the risk of depression.

Highly efficient and stable Cs3Mn0.93Zn0.07Br5@SiO2 for wide color gamut backlight displays.

Mn-based perovskites have become a new candidate material for backlight display applications. However, low efficiency and poor stability are the key problems limiting the application of Mn-based perovskites. In this work, Zn-doped and SiO2-encapsulated Cs3MnBr5, denoted as Cs3Mn0.93Zn0.07Br5@SiO2 (CMZBS), was successfully synthesized to improve the photoluminescence quantum yield (PLQY) and stability. After Zn doping, the PLQY increased from 51% to 72% due to the reduction in the energy transfer between [MnBr4]2-. The PLQY can be further improved to 80% after coating SiO2. Compared with Cs3MnBr5 (CMB), CMZBS showed better stability against thermal, air, light, and polar solvents (ethanol and isopropanol). In addition, a white LED (WLED) device with a CIE of (0.323, 0.325) was fabricated by integrating CMZBS and the red phosphor K2SiF6:Mn4+ on a 465 nm blue GaN chip, which exhibited a high luminous efficiency of 92 lm W-1 and excellent stability, demonstrating its great potential application in wide color gamut displays.