Dispersion Turning Attenuation Microfiber for Flowrate Sensing.

We demonstrated a new optical fiber modal interferometer (MI) for airflow sensing; the novelty of the proposed structure is that an MI is fabricated based on a piece of HAF, which makes the sensitive MI itself also a hotwire. The interferometer is made by applying arc-discharge tapering and then flame tapering on a 10 mm length high attenuation fiber (HAF, 2 dB/cm) with both ends spliced to a normal single mode fiber. When the diameter of the fiber in the processing region is reduced to about 2 µm, the near-infrared dispersion turning point (DTP) can be observed in the interferometer's transmission spectrum. Due to the absorption of the HAF, the interferometer will have a large temperature increase under the action of a pump laser. At the same time, the spectrum of the interferometer with a DTP is very sensitive to the change in ambient temperature. Since airflow will significantly affect the temperature around the fiber, this thermosensitive interferometer with an integrated heat source is suitable for airflow sensing. Such an airflow sensor sample with a 31.2 mm length was made and pumped by a 980 nm laser with power up to 200 mW. In the comparative experiment with an electrical anemometer, this sensor exhibits a very high air-flow sensitivity of -2.69 nm/(m/s) at a flowrate of about 1.0 m/s. The sensitivity can be further improved by enlarging the waist length, increasing the pump power, etc. The optical anemometer with an extremely high sensitivity and a compact size has the potential to measure a low flowrate in constrained microfluidic channels.

Demodulation of Fabry-Perot sensors using random speckles.

Random speckles are proposed to demodulate Fabry-Perot (FP) sensors in this study. A piece of multimode fiber is used to interrogate the FP transmission spectrum, and tiny spectral changes lead to significant variations in the generated speckle patterns. In the demonstration experiments, the pressure resolution of 0.001 MPa can be obtained from an open cavity FP sensor based on the convolutional neural network (CNN) demodulation algorithm. It is worth noting that the spectral differences in neighboring orders can be precisely distinguished due to the high sensitivity of speckles. Thus, the fringe-order ambiguity problem is solved and the dynamic measurement range can be greatly improved. The speckle-based demodulation scheme provides a new way to balance resolution, dynamic range, speed, and cost of FP sensors.

FLOW AND GEOMETRICAL ALTERATIONS IN RETINAL MICROVASCULATURE CORRELATED WITH THE OCCURRENCE OF DIABETIC RETINOPATHY: Evidence from a Longitudinal Study.

PURPOSE: To assess the relationship between flow and geometric parameters in optical coherence tomography angiography images and the risk of incident diabetic retinopathy (DR). METHODS: This prospective, observational cohort study recruited patients with Type 2 diabetes without DR in Guangzhou, China, and followed up annually. A commercially available optical coherence tomography angiography device (DRI OCT Triton; Topcon Inc, Tokyo, Japan) was used to obtain a variety of flow (foveal avascular zone area, vessel density, and vessel length density) and geometric (fractal dimension and blood vessel tortuosity) parameters in superficial capillary plexus (SCP) and deep capillary plexus. The odds ratio (OR) and its 95% confidence interval (CI) were calculated per 1-SD increase in each optical coherence tomography angiography parameter. RESULTS: Over a follow-up of 1 year, 182 of 1,698 participants (10.7%) developed incident DR. After adjusting for conventional risk factors and image quality score, the higher risk of DR onset was significantly associated with the reduced parafoveal vessel density of SCP (OR = 0.81; 95% CI: 0.69, 0.96; P = 0.016), reduced parafoveal vessel length density of SCP (OR = 0.73; 95% CI: 0.59, 0.90; P = 0.003), reduced fractal dimension of SCP (OR = 0.73; 95% CI: 0.61, 0.87; P < 0.001), increased blood vessel tortuosity of SCP (OR = 1.39; 95% CI: 1.18, 1.64; P < 0.001), and increased blood vessel tortuosity of deep capillary plexus (OR = 1.19; 95% CI: 1.01, 1.40; P = 0.033). CONCLUSION: Reduced vessel density and impaired vessel geometry posed higher susceptibility for DR onset in patients with Type 2 diabetes, supporting the adoption of optical coherence tomography angiography parameters as early monitoring indicators of the newly incident DR.

Rapid and label free detection of aflatoxin B1 in alcoholic beverages with a microfluid fiber device.

A rapid and label free aflatoxin B1 (AFB1) microfluid sensor was proposed and tested. The device was fabricated with hollow-core photonics crystal fiber infiltrated with the AFB1 solution. The autofluorescence emitting from the AFB1 molecules was detected. The sensor length was optimized. The AFB1 concentration was tested with a 4 cm long sensor. The best limit of detection was achieved as low as 1.34 ng/ml, which meets the test requirement of the national standards for AFB1 in food. The effectiveness of this sensor being applied in beer solution was also verified to be a little more sensitive than in aqueous solution. Compared with traditional AFB1 detection methods, the proposed single-ended device perfectly satisfies the demand of process control in alcoholic beverages manufacture.

Vibration Sensor Based on Hollow Biconical Fiber.

A hollow biconical fiber is proposed and experimentally demonstrated for vibration sensing. It is fabricated by creating an air micro-cavity in single-mode fiber, followed by tapering it. Experimental results show that the device is highly sensitive to bending with a sensitivity of 21.30 dB/m-1. When it is exposed to vibration, its transmission loss is modulated periodically, then based on the measured transmission, the vibration frequency can be demodulated accurately. The acoustic vibration testing results show that the proposed device can detect and demodulate the exciting acoustic frequency accurately and distinguish its sound intensity, and the maximum signal to noise ratio (SNR) achieves up to 59 dB. Moreover, cantilever beam testing proves its performance reliable. Additionally, the sensing head has the advantages of a lightweight, compact size (with a total length of less than 250 µm), and insensitivity of temperature. All these features indicate the proposed sensor has a promising potential in the engineering field.

PDMS-filled Fabry-Perot interferometer-based multipoint temperature measurement using an array-waveguide grating.

In this paper, a multipoint temperature measurement scheme based on Fabry-Perot interferometers (FPIs) multiplexing is proposed. The FPI sensor is constructed as a section of hollow-core fiber (HCF) partially filled with polydimethylsiloxane (PDMS) spliced to a single-mode fiber. An array-waveguide grating with 16 channels is used for the FPI sensors' multiplexing and demultiplexing, and a broadband source is used as the light source. The corresponding theoretical model was built for analysis of the scheme, and the simulation results shown the FPI working principle can be simplified as a dual-beam interference. Two channels connected to two FPI sensors were experimentally tested for the concept verification. The temperature sensitivities of the proposed two sensors are 1.090 dB/°C and 1.210 dB/°C from 30°C to 40°C, respectively. There is no interchannel cross talk observed. Hence, FPI temperature sensors can work simultaneously in this structure, proving the validity of the multipoint temperature measurement concept.

Long-chain Acylcarnitines Reduce Lung Function by Inhibiting Pulmonary Surfactant.

The role of mitochondrial energy metabolism in maintaining lung function is not understood. We previously observed reduced lung function in mice lacking the fatty acid oxidation enzyme long-chain acyl-CoA dehydrogenase (LCAD). Here, we demonstrate that long-chain acylcarnitines, a class of lipids secreted by mitochondria when metabolism is inhibited, accumulate at the air-fluid interface in LCAD(-/-) lungs. Acylcarnitine accumulation is exacerbated by stress such as influenza infection or by dietary supplementation with l-carnitine. Long-chain acylcarnitines co-localize with pulmonary surfactant, a unique film of phospholipids and proteins that reduces surface tension and prevents alveolar collapse during breathing. In vitro, the long-chain species palmitoylcarnitine directly inhibits the surface adsorption of pulmonary surfactant as well as its ability to reduce surface tension. Treatment of LCAD(-/-) mice with mildronate, a drug that inhibits carnitine synthesis, eliminates acylcarnitines and improves lung function. Finally, acylcarnitines are detectable in normal human lavage fluid. Thus, long-chain acylcarnitines may represent a risk factor for lung injury in humans with dysfunctional fatty acid oxidation.

Highly-sensitive gas pressure sensor using twin-core fiber based in-line Mach-Zehnder interferometer.

A Mach-Zehnder interferometer based on a twin-core fiber was proposed and experimentally demonstrated for gas pressure measurements. The in-line Mach-Zehnder interferometer was fabricated by splicing a short section of twin-core fiber between two single mode fibers. A micro-channel was created to form an interferometer arm by use of a femtosecond laser to drill through one core of the twin-core fiber. The other core of the fiber was remained as the reference arm. Such a Mach-Zehnder interferometer exhibited a high gas pressure sensitivity of -9.6 nm/MPa and a low temperature cross-sensitivity of 4.4 KPa/°C. Moreover, ultra-compact device size and all-fiber configuration make it very suitable for highly-sensitive gas pressure sensing in harsh environments.

Acyl-CoA thioesterase-2 facilitates mitochondrial fatty acid oxidation in the liver.

Acyl-CoA thioesterase (Acot)2 localizes to the mitochondrial matrix and hydrolyses long-chain fatty acyl-CoA into free FA and CoASH. Acot2 is expressed in highly oxi-dative tissues and is poised to modulate mitochondrial FA oxidation (FAO), yet its biological role is unknown. Using a model of adenoviral Acot2 overexpression in mouse liver (Ad-Acot2), we show that Acot2 increases the utilization of FA substrate during the daytime in ad libitum-fed mice, but the nighttime switch to carbohydrate oxidation is similar to control mice. In further support of elevated FAO in Acot2 liver, daytime serum ketones were higher in Ad-Acot2 mice, and overnight fasting led to minimal hepatic steatosis as compared with control mice. In liver mitochondria from Ad-Acot2 mice, phosphorylating O2 consumption was higher with lipid substrate, but not with nonlipid substrate. This increase depended on whether FA could be activated on the outer mitochondrial membrane, suggesting that the FA released by Acot2 could be effluxed from mitochondria then taken back up again for oxidation. This circuit would prevent the build-up of inhibitory long-chain fatty acyl-CoA esters. Altogether, our findings indicate that Acot2 can enhance FAO, possibly by mitigating the accumulation of FAO intermediates within the mitochondrial matrix.

A case of diffuse large B-cell lymphoma complicated by hemophagocytic syndrome.

BACKGROUND: Hemophagocytic syndrome (HPS) is a fatal disease and T-cell lymphoma is a common cause of this syndrome. The authors describe a rare case of diffuse large B-cell lymphoma (DLBCL) with HPS. METHODS: Hematologic investigation, bone marrow aspirate and biopsy, cytogenetic analysis and lymph node biopsy were performed. RESULTS: The patient obtained transient complete remission with rituximab and chemotherapy but relapsed soon within the observation period. CONCLUSIONS: More aggressive therapy should be given in order to obtain a better therapeutic effect for the patients of DLBCL with HPS.

Acute pleural and pericardial effusion induced by chemotherapy in treating chronic myelocytic leukemia.

BACKGROUND: Report of a rare and serious complication of chemotherapy with daunorubicin and cytarabine (DA regimen). METHODS: We report a special case of a patient diagnosed chronic myeloid leukemia (CML) with accelerated phase, who simultaneously suffered from acute pleural and pericardial effusion while receiving chemotherapeutic treatment with DA regimen. RESULTS: Following treatment with DA regimen, the patient had the symptoms of chest distress and shortness of breath, followed by respiratory failure and pericardial tamponade. The patient's condition was improved when treated with the puncturation through the pericardium and pleural cavity, coupled with glucocorticosteroid treatment. CONCLUSIONS: Physicians should be made aware of the potential for emergency pleural and pericardial effusion caused by daunorubicin and cytarabine in order to accurately diagnose and treat these conditions and thereby decrease mortality related to chemotherapy.

A dual-mode optical fiber sensor for SERS and fluorescence detection in liquid.

The in vivo detection of biomarkers in a liquid environment is very important for the early diagnosis of diseases. Spectroscopy methods are employed in ultraviolet-visible-infrared wavelengths, fluorescence or Raman spectra are detected for clinical diagnose. The dual-mode image can provide more diagnostic information and has been realized in some research work. However, there is still lacking simple and sensitive dual-mode sensors to satisfy the in vivo detecting demands. In this paper, a dual-mode fiber sensor for Surface-enhanced Raman Scattering (SERS) and fluorescence detection is proposed. The sensor is formed by a tapered optical fiber, half of the fiber tip surface is coated with Ag nanoparticles. In the detection of Rhodamine 6G (R6G) aqueous solution, the minimum detectable concentrations in SERS and fluorescence tests are of the same order of magnitude. By combining the Raman spectral features and the fluorescence intensity, the recognition and quantitation of target molecules were obtained reliably. It is the first time, to our knowledge, that the Raman-fluorescence dual-mode detection is realized in one single fiber, which was manufactured with micro-machinery techniques. It is a label-free, general-purpose fiber sensor, which can be applied for liquid biopsy, helping to diagnose and treat diseases in vivo.

The relationship between renal function and diabetic retinopathy in patients with type 2 diabetes: A three-year prospective study.

Objective: To explore the association of diabetic retinopathy (DR) and diabetic macular edema (DME) with renal function in patients with type 2 diabetes mellitus (T2DM). Design: A prospective cohort study. Methods: This single-centre study included patients with no DR, mild non-proliferative DR (NPDR), and no DME at baseline. DR and DME were assessed using 7-field fundus photography and swept-source OCT (SS-OCT). The baseline renal function assessed included the estimated glomerular filtration rate (eGFR) and microalbuminuria (MAU). Cox regression analyses were used to assess the hazard ratio (HR) of renal function with the progression of DR and the development of DME. Results: A total of 1409 patients with T2DM (1409 eyes) were included. During 3 years of follow-up,143 patients had DR progression, and 54 patients developed DME. Low eGFR levels at baseline were associated with the development of DR (HR, 1.044 per 1-SD decrease; 95% CI, 1.035-1.053; P < 0.001). Compared to the participants with eGFRs >90 mL/min/1.73 m2, the participants with eGFRs of 60-90 mL/min/1.73 m2 (HR, 1.649; 95% CI, 1.094-2.485; P = 0.017) or < 60 mL/min/1.73 m2 (HR, 2.106; 95% CI, 1.039-4.269; P = 0.039) had a higher risk of DR progression. Increasing MAU tertiles were associated with progression of DR (Tertile 2: HR, 2.577; 95% CI, 1.561-4.256; P < 0.001; Tertile 3: HR, 3.135; 95% CI, 1.892-5.194; P < 0.001). No significant relationship was found between renal function and the development of DME (P > 0.05). Conclusions: Abnormal renal profiles (i.e., low levels of eGFR and high levels of MAU) were associated with the progression of DR, but not with the development of DME.

Evolution of drug-resistant viral populations during interruption of antiretroviral therapy.

Analysis of a large number of HIV-1 genomes at multiple time points after antiretroviral treatment (ART) interruption allows determination of the evolution of drug-resistant viruses and viral fitness in vivo in the absence of drug selection pressure. Using a parallel allele-specific sequencing (PASS) assay, potential primary drug-resistant mutations in five individual patients were studied by analyzing over 18,000 viral genomes. A three-phase evolution of drug-resistant viruses was observed after termination of ART. In the first phase, viruses carrying various combinations of multiple-drug-resistant (MDR) mutations predominated with each mutation persisting in relatively stable proportions while the overall number of resistant viruses gradually increased. In the second phase, viruses with linked MDR mutations rapidly became undetectable and single-drug-resistant (SDR) viruses emerged as minority populations while wild-type viruses quickly predominated. In the third phase, low-frequency SDR viruses remained detectable as long as 59 weeks after treatment interruption. Mathematical modeling showed that the loss in relative fitness increased with the number of mutations in each viral genome and that viruses with MDR mutations had lower fitness than viruses with SDR mutations. No single viral genome had seven or more drug resistance mutations, suggesting that such severely mutated viruses were too unfit to be detected or that the resistance gain offered by the seventh mutation did not outweigh its contribution to the overall fitness loss of the virus. These data provide a more comprehensive understanding of evolution and fitness of drug-resistant viruses in vivo and may lead to improved treatment strategies for ART-experienced patients.

Rapid determination of ethanol content based on an optical fiber-device and R6G-indicator.

A rapid method for the determination of ethanol content is proposed and tested. A fluorescence detecting system, with a multimode fiber (MMF) sensing head, is employed. Rhodamine 6G (R6G) is applied as the fluorescent indicator. In the R6G aqueous solution, the molecules aggregate at high concentration, causing fluorescence quenching. Nevertheless, aggregation and quenching rarely occur in ethanol. Taking an ethanol and water mixture as the solvent, the photoluminescence (PL) intensity reflects the aggregation degree and the ethanol content. Based on this phenomenon, the contents of the ethanol-water mixture were measured through PL intensity detection. A limit of detection (LOD) at ∼0.1 vol% level was obtained in the range of 0-100%. Commercial Chinese baijiu and rubbing alcohol were tested and the results obtained were consistent with the label values. The detecting system is compact and of low-cost, and the detecting method is rapid, accurate and repeatable. There is good prospect of applications for the determination of ethanol content on-site.

Macular Choroidal Thickness and the Risk of Referable Diabetic Retinopathy in Type 2 Diabetes: A 2-Year Longitudinal Study.

Purpose: The purpose of this study was to evaluate the associations between choroidal thickness (CT) and the 2-year incidence of referable diabetic retinopathy (RDR). Methods: This was a prospective cohort study. Patients with type 2 diabetes in Guangzhou, China, aged 30 to 80 years underwent comprehensive examinations, including standard 7-field fundus photography. Macular CT was measured using a commercial swept-source optical coherence tomography (SS-OCT) device (DRI OCT Triton; Topcon, Tokyo, Japan). The relative risk (RR) with 95% confidence intervals (CIs) was used to quantify the association between CT and new-onset RDR. The prognostic value of CT was assessed using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Results: A total of 1345 patients with diabetes were included in the study, and 120 (8.92%) of them had newly developed RDR at the 2-year follow-up. After adjusting for other factors, the increased RDR risk was associated with greater HbA1c (RR = 1.35, 95% CI = 1.17-1.55, P < 0.001), higher systolic blood pressure (SBP; RR = 1.02, 95% CI = 1.01-1.03, P = 0.005), lower triglyceride (TG) level (RR = 0.81, 95% CI = 0.69-0.96, P = 0.015), presence of diabetic retinopathy (DR; RR = 8.16, 95% CI = 4.47-14.89, P < 0.001), and thinner average CT (RR = 0.903, 95% CI = 0.871-0.935, P < 0.001). The addition of average CT improved NRI (0.464 ± 0.096, P < 0.001) and IDI (0.0321 ± 0.0068, P < 0.001) for risk of RDR, and it also improved the AUC from 0.708 (95% CI = 0.659-0.757) to 0.761 (95% CI = 0.719-0.804). Conclusions: CT thinning measured by SS-OCT is an early imaging biomarker for the development of RDR, suggesting that alterations in CT play an essential role in DR occurrence.

Fiber-tip micro-cavity for temperature and transverse load sensing.

A low cost fiber-optic micro-cavity interferometric sensor is presented. The micro-cavity is fabricated at the fiber tip by splicing a silica capillary to a single mode fiber and then heating/melting the capillary to form a microsphere with an internal air cavity. Applications of the micro-cavity sensor for temperature and traverse load measurements are demonstrated. The sensor has small size and good mechanical strength, and may be used in high temperature environment.

Protective protein/cathepsin A rescues N-glycosylation defects in neuraminidase-1.

BACKGROUND: Neuraminidase-1 (NEU1) catabolizes the hydrolysis of sialic acids from sialo-glycoconjugates. NEU1 depends on its interaction with the protective protein/cathepsin A (PPCA) for lysosomal compartmentalization and catalytic activation. Murine NEU1 contains 4 N-glycosylation sites, 3 of which are conserved in the human enzyme. The expression of NEU1 gives rise to differentially glycosylated proteins. METHODS: We generated single-point mutations in mouse NEU1 at each of the 4 N-glycosylation sites. Mutant enzymes were expressed in NEU1-deficient cells in the presence and absence of PPCA. RESULTS: All 4 N-glycosylation variants were targeted to the lysosomal/endosomal compartment. All N-glycans, with the exception of the most C-terminal glycan, were important for maintaining stability or catalytic activity. The loss of catalytic activity caused by the deletion of the second N-glycan was rescued by increasing PPCA expression. Similar results were obtained with a human NEU1 N-glycosylation mutant identified in a sialidosis patient. The N-terminal N-glycan of NEU1 is indispensable for its function, whereas the C-terminal N-glycan appears to be non-essential. The omission of the second N-glycan can be compensated for by upregulating the expression of PPCA. GENERAL SIGNIFICANCE: These findings could be relevant for the design of target therapies for patients carrying specific NEU1 mutations.

Structural long period gratings made by drilling micro-holes in photonic crystal fibers with a femtosecond infrared laser.

We present a new method for fabricating structural long-period gratings (LPGs) in photonic-crystal fibers (PCFs). The method is based on periodically drilling holes into the PCF cladding along the length of the fiber by use of a focused femtosecond infrared laser. A very short LPG with only 9 periods and a grating length of < 4 mm exhibited resonance strength of over 20 dB and a polarization dependent loss of 25 dB. The high resonance strength is attributed to the strong modulated mode-field profile caused by the significant perturbation of the fiber geometry. The mechanism of LPG formation is discussed based on coupled local-mode theory.