Phase retardation measurement of an arbitrary wave plate based on magneto-optical modulating and residue detecting of the base frequency component of the signal.

Wave plates (WPs) are key components in optical polarization systems whose phase retardations should be measured accurately. The key point of most light extinction methods focuses on how to precisely judge the system's extinction state and then confirm corresponding angle positions of the optical components. Usually the extinction state of a measurement system is judged by detecting residue of outgoing light intensity. In this Letter, a method of measuring the phase retardation of an arbitrary WP based on magneto-optical modulation is proposed. A magneto-optical modulator is placed between the standard quarter-WP and the second polarizer on the basis of the traditional optical path. The measurement signal is obtained after the outgoing light passing through a band-pass filter whose center frequency is the same as the frequency of the magneto-optic modulator's driving voltage. This method detects the base frequency component instead of the whole intensity of the outgoing light, so as to get better judgement accuracy of the system's extinction state. The arbitrary WP's phase retardation can be accurately derived by detecting the residue of the base frequency component of the outgoing light signal and then judging the angle position of the second polarizer when the system is in the state of extinction. The corresponding theoretical formulas are deduced by the Jones matrix, and the WP measuring system is established. The error analysis shows that the system measurement uncertainty is about 4.5' if the experiment temperature varies in the range of 0.1°C. Experiment results on half-WPs and quarter-WPs show that the presented method is in good agreement with other methods. The measurement repeatability is also good, with the standard deviation about 2'.

Humidity coefficient correction in the calculation equations of air refractive index by He-Ne laser based on phase step interferometry.

The refractive index of air (RIA) is an important parameter in precision measurement. The revisions to Edlen's equations by Boensch and Potulski [Metrologia 35, 133 (1998)] are mostly used to calculate the RIA at present. Since the humidity correction coefficients in the formulas were performed with four wavelengths of a Cd(114) lamp (644.0, 508.7, 480.1, and 467.9 nm) and at the temperature range of 19.6°C-20.1°C, the application is restricted when an He-Ne laser is used as the light source, which is mostly applied in optical precision measurement, and the environmental temperature is far away from 20°C as well. To solve this problem, a measurement system based on phase step interferometry for measuring the effect of the humidity to the RIA is presented, and a corresponding humidity correction equation is derived. The analysis and comparison results show that the uncertainty of the presented equation is better than that of Boensch and Potulski's. It is more suitable in present precision measurements by He-Ne laser, and the application temperature range extends to 14.6°C-24.0°C as well.

Anthropogenic-induced ecological risks on marine ecosystems indicated by characterizing emerging pollutants in Pearl River Estuary, China.

Anthropogenic Contaminants of Emerging Concern (CECs) in marine environments have raised significant concerns. Yet, analyses detailing their origins, fate, and environmental effects are limited. This study employs an integrated non-target screening methodology to elucidate CECs existence across 46 sampling sites in the Pearl River Estuary (PRE) of the South China Sea. Assisted by advanced liquid chromatography-high resolution mass spectrometry, we discovered 208 chemicals in six usage categories, with pesticides (33 %) and pharmaceuticals (29 %) predominating. Several CECs drew attention for their consistent detections, profound abundance, and significant ecotoxicities. The wide detection of them at offshore sites further implies that anthropogenic activities may contribute to large-scale contamination. Meanwhile, distinct distribution patterns of CECs across PRE are evident in semi-quantitative results, indicating regional anthropogenic influences. Identified transformation products may establish a novel and non-negligible negative contribution to ecology through elevated environmental toxicities, exemplified by HMMM and atrazine. Based on the ecological risks, we compiled a prioritized list of 21 CECs warranting intensified scrutiny. Our findings indicate the introduction of various CECs into the South China Sea via PRE, emphasizing the urgent necessity for ongoing surveillance of discharged CECs at estuary areas and assessment of their marine ecological consequences.

Integrating data dependent and data independent non-target screening methods for monitoring emerging contaminants in the Pearl River of Guangdong Province, China.

The occurrence of Contaminants of Emerging Concern (CECs) in the Pearl River of Guandong province, China, was characterized using a nontarget screening (NTS) strategy combining both data dependent and data independent acquisition techniques. Our analysis identified 620 unique compounds, including pharmaceuticals (137), pesticides (124), industrial materials (68), personal care products (32), veterinary drugs (27), plasticizers or flame retardants (11), etc. Out of these compounds, 40 CECs were found with a detection frequency of over 60 %, including diazepam, a well-known drug to treat anxiety, insomnia, convulsion, etc., which had the highest detection rate at 98 %. Risk quotients (RQs) were calculated for CECs identified with high confidence (Level 1, confirmed with authentic standards), and it was found that 12 CECs had RQs > 1, with notable concern for pretilachlor (detection frequency: 48 %; 0.8-19.0 ng/L), bensulfuron-methyl (86 %, 3.1-56.2 ng/L), imidacloprid (80 %, 5.3-62.8 ng/L) and thiamethoxam (86 %, 9.1-99.9 ng/L), which exhibited RQs exceeding the threshold of concern (RQ > 1) at 46-80 % of sampling sites. Additionally, tentative identification of potential structurally related compounds provided valuable insight into the parent-product relationships in complex samples. This study highlights the importance and urgency of using NTS for CECs in the environment and presents a novel data sharing approach, which facilitates other scientists to assess, investigate further, and perform retrospective analyses.

Measurement of air refractive index based on surface plasmon resonance and phase detection.

A method for refractive index of air measurement is presented based on surface plasmon resonance (SPR) and phase detection using a dual-frequency laser interferometer. Theoretical analyses indicate that the phase-difference variation of the measurement signal versus the reference signal is linear with refractive index of air (RIA) fluctuation, and the calculation formula of RIA is derived. The structure design of the self-adaptive SPR sensor greatly reduces the measurement error resulting from the incident angle shift and improves the sensitivity. The experiments show that measurement uncertainty of 10(-6) order has been achieved when phase detection precision is 0.1°. The phenomenon of sudden phase variation during air pumping and air filling, which is caused by temperature fluctuation, is discussed.

Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths.

A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited.

Resonant effects in nonlinear photon absorption during femtosecond laser ablation of Nd-doped silicate glass.

This study investigates the resonant effects in nonlinear photon absorption in femtosecond laser ablation of Nd-doped silicate glass (Nd:glass). During the femtosecond laser ablation process, the resonant ablation threshold fluence is decreased by up to 40% compared with that of ordinary ablation. However, it is found that the resonant effect is closely related with laser intensity, and lower laser intensities are required to achieve a significant enhancement. When the intensity is lower than 2.28×10(14) W/cm(2) at which multiphoton ionization dominates, resonant effect is enhanced by a factor of 1.4 to 4.4. When the intensity is higher than 2.28×10(14) W/cm(2), at which intensity tunnel ionization dominates, the resonant effect becomes weak and gradually fades away. It is shown that the resonant effect is still important for multiphoton ionization yet insignificant for tunnel ionization.

Simulation and optimization of polymer-coated microsphere resonators in chemical vapor sensing.

This study presents a chemical vapor sensor based on polymer-coated microsphere resonators. A theoretical simulation of the sensor response is performed, and optimization of the polymer layer thickness is investigated. Results show that the sensor exhibits a good linearity and a low detection limit of the refractive index change. Especially at the thermostable thickness of the polymer layer, the refractive index detection limit of the wavelength around 780 nm can be as low as ~2×10⁻8 refractive index unit for a spectral resolution of 10 fm, without any temperature control. Because of the good sensing performance and simple manipulation, the proposed sensor is a very promising platform for chemical vapor detections.

Comprehensive Analysis of Differential Immunocyte Infiltration and Potential ceRNA Networks Involved in the Development of Atrial Fibrillation.

This study is aimed at identifying potential molecular mechanisms and candidate biomarkers in the left atrial regions for the diagnosis and treatment of valvular atrial fibrillation (VAF). Multibioinformatics methods, including linear models for microarray analysis (LIMMA), an SVA algorithm, CIBERSORT immune infiltration, and DNA methylation analysis, were employed. In addition, the protein-protein interaction (PPI) network, Gene Ontology (GO), and molecular pathways of differentially expressed genes (DEGs) or differential methylation regions were constructed. In all, compared with the normal rhythm group, 243 different mRNAs (29 downregulated and 214 upregulated) and 26 different lncRNAs (3 downregulated and 23 upregulated) were detected in the left atrium (LA) of atrial fibrillation (AF) patients, and the neutrophil and CD8+ T cell were infiltrated. Additionally, 199 different methylation sites (107 downregulated and 92 upregulated) were also identified based on DNA methylation analysis. After integration, ELOVL2, CCR2, and WEE1 were detected for differentially methylated and differentially transcribed genes. Among them, WEE1 was also a core gene identified by the competing endogenous RNA (ceRNA) network that included WEE1-KRBOX1-AS1-hsa-miR-17-5p, in VAF left atrial tissue. We combined the DNA methylation and transcriptional expression differential analysis and found that WEE1 (cg13365543) may well be a candidate gene regulated by DNA methylation modification. Moreover, KRBOX1-AS1 and WEE1 can compete endogenously and may mediate myocardial tissue infiltration into CD8+ T cells and participate in the AF process.

Signet-ring cell carcinoma of the ampulla of Vater.

Signet-ring cell carcinoma (SRCC) of the alimentary canal is a variant of adenocarcinoma that has a poor clinical prognosis. SRCC of the ampulla of Vater is extremely uncommon with < 12 cases reported in the literature. SRCC of the ampulla of Vater occurs in an older age group (mean age 60 yr) when compared to SRCC of the stomach (under 45 yr), but is similar to SRCC of the large intestine. We report a case of SRCC of the ampulla of Vater with unusual histopathologic features in a 56-yr-old woman who presented with a small tumor at the orifice of the ampulla, associated with extensive lymphovascular invasion and multiple regional lymph node involvement.

Sarcomatoid renal cell carcinoma with divergent sarcomatoid growth patterns: a case report and review of the literature.

A 71-year-old woman who presented with left abdominal pain was found to have a noncalcified renal mass with a perisplenic extension on imaging studies. Histologically, the tumor showed predominantly malignant spindle cells with extensive osteoid and chondroid matrix production. Various growth patterns resembling rhabdomyosarcoma, malignant fibrous histiocytoma, and fibrosarcoma were also observed. Immunohistochemistry showed positive staining of the neoplastic cells for cytokeratin and focally positive staining for CD10 and CD117 (c-Kit). Electron microscopic examination revealed a poorly differentiated neoplasm with both mesenchymal and epithelial features. The tumor was diagnosed as a sarcomatoid renal cell carcinoma with overgrowth of the sarcomatoid component (World Health Organization: renal cell carcinoma, unclassified). To our knowledge, sarcomatoid renal cell carcinoma with such a broad morphologic phenotype in a single case has not been documented. Furthermore, the CD117 expression in a sarcomatoid renal cell carcinoma that was observed in this case merits further investigation.

Nondestructive measurement of an optical fiber refractive-index profile by a transmitted-light differential interference contact microscope.

A novel transmitted-light differential interference contrast (DIC) system is used for nondestructive measurement of the refractive-index profile (RIP) of an optical fiber. By means of this system the phase of a measured light beam can be modulated with an analyzer, and the phase distribution of a fiber is obtained by calculation of the various interference patterns. The measurement theory and structure and some typical applications of this system are demonstrated. The results of measuring RIPs in graded-index fiber are presented. Both the experimental results and theoretical analysis show that the system takes the advantage of high index resolution and of sufficient measurement accuracy for measuring the refractive index of the optical fiber. The system has strong ability to overcome environmental disturbance because of its common-path design. Moreover, one can use the system to measure the RIP along the fiber axis and acquire an image of the three-dimensional RIP of the fiber.