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• A new type optical fiber immunosensor for detecting carcinoembryonic antigen. • As a biometric recognition molecule, nanobody exhibits superior characteristics compared to traditional antibody. • Two types of sensors were designed using graphene oxide and gold nanoparticles for comparison. • The optical fiber immunosensor shows a high specificity, stability, fast response and good reproducibility. We engineered two highly specific, label-free optical fiber immunosensors incorporating innovative nanobodies as biological probes. These sensors, named the graphene oxide (GO) immunosensor and gold nanoparticles (GNP) immunosensor, leverage GO and GNP as bio-sensitive materials for the unlabeled detection of carcinoembryonic antigen (CEA). By employing a layer-by-layer self-assembly technique, we precisely coated the sensitive material onto the optical fiber microstructure, subsequently adsorbing nanobodies onto the coated surface. The detection mechanism hinges on monitoring refractive index changes induced by CEA adsorption onto nanobodies, distinguishing them from changes induced by other analytes. Experimental results showcase the sensitivities of the GO immunosensor and GNP immunosensor at 15.1 nm/nM and 20.2 nm/nM, respectively, with corresponding lower detection limits of 0.05 nM and 0.02 nM. Notably, both biosensors exhibit outstanding specificity, operate label-free, and enable rapid detection of low concentrations of CEA. This proposed optical immunosensor holds significant promise as a biophotonic platform for clinical diagnostics, offering advancements in medical applications. [ABSTRACT FROM AUTHOR]

• A novel optical immunosensor for the label-free detection of carcinoembryonic antigen. • Gold nanoparticles/graphene oxide composite film functionalized S fiber taper sensor. • As a biomolecular probe, nanobody exhibits superior characteristics compared to monoclonal antibody. • The sensor shows a high specificity, stability, sensibility and good reproducibility. We present an S-tapered fiber (STF) immunosensor featuring a gold nanoparticle/graphene oxide (GNP/GO) composite membrane for specific and label-free detection of carcinoembryonic antigen (CEA). Through spectral monitoring and calculation, we have developed a highly specific and sensitive immunosensor with a sensitivity of 27.9 nm/nM (R2 = 0.996) and a detection limit of 0.01 nM. Moreover, this biosensor demonstrates label-free operation and rapid detection of low concentrations of CEA. The proposed optical biosensor holds significant potential as a biophotonic platform for applications in clinical diagnostics, medical settings, and biomedical research. [ABSTRACT FROM AUTHOR]

During air bending of sheet metals, the correction of punch stroke for springback control is always implemented through repeated trial bending until achieving the forming accuracy of bending parts. In this study, a modelling method for correction of punch stroke is presented for guiding trial bending based on a data-driven technique. Firstly, the big data for the model are mainly generated from a large number of finite element simulations, considering many variables, e.g., material parameters, dimensions of V-dies and blanks, and processing parameters. Based on the big data, two punch stroke correction models are developed via neural network and dimensional analysis, respectively. The analytic comparison shows that the neural network model is more suitable for guiding trial bending of sheet metals than the dimensional analysis model, which has mechanical significance. The actual trial bending tests prove that the neural-network-based punch stroke correction model presents great versatility and accuracy in the guidance of trial bending, leading to a reduction in the number of trial bends and an improvement in the production efficiency of air bending. [ABSTRACT FROM AUTHOR]

Abstract: A simple method for adjusting a chirped fiber Bragg gratings (CFBGs) with an external heater is proposed and demonstrated in experimental. A fiber grating is set in the heater that is composed with a series of resistance coils. Uniform or gradient temperature field around the grating is implement by designing the radius of resistance coils fixed or varied along the heater. The properties of the grating can be accurately tuned when varying the voltage applied to the resistance coils. In particular, the chirp and the central wavelength of the grating that is set in two different heaters can be adjusted separately by controlling the voltage in each of these heaters. The group delay of the CFBG is measured. [Copyright &y& Elsevier]

• Direct femtosecond laser writing chalcogenide glass infrared fiber Bragg gratings of high reflectivity and narrow bandwidth. • Discussions and solutions to current problems in chalcogenide glass fiber's fabrication using direct femtosecond laser writing. • Foundation for fabricating FBG with arbitrary periods in ChG fibers obtained. Chalcogenide glass (ChG) fiber Bragg grating (FBG) is one of the key components in monolithic infrared fiber lasers and sensors. However, its effective fabrication using direct femtosecond laser writing is still seldom reported, owing to complications attributable to ChG. In this study, a double-D shaped ChG fiber was used to fabricate FBGs with high reflectivity (a 20.5 dB dip in the transmittance) and narrow 3-dB bandwidth (164 pm) using direct femtosecond laser writing. The high sensitivity to laser powers of the direct writing of the ChG FBG was revealed and understood from the perspective of the low laser-induced damage threshold of ChGs. Lower-order reflectance of the directly written FBGs at the mid-infrared wavelength region were quantitively predicted to have higher reflectivity. These results provide a robust method of writing FBGs with arbitrary periods in ChG fibers, establishing a solid foundation for the development of infrared fiber lasers and fiber sensors. [ABSTRACT FROM AUTHOR]

• The external laser based on femtosecond-written birefringent fiber Bragg grating (FBG) achieves excellent linewidth characteristics. • The hybrid laser based on ridge waveguide emission gain chip and femtosecond-written birefringent FBG attains high integration and low cost. • Linear polarization output is realized by the orthogonal polarization eigenmode and effective external cavity mode selection of the birefringent FBG. We demonstrate an external-cavity semiconductor laser (ECSL) with linear polarization and a narrow linewidth. A birefringent Bragg grating prepared by a femtosecond laser point-by-point technique in a polarization-maintaining fiber (PMF) is used to provide external-cavity feedback, and its polarization-dependent characteristics enable selection of the main polarization mode and linewidth narrowing of the ridge waveguide emission gain chip (GC). This compact and robust ECSL achieves an output power of > 60 mW and a polarization extinction ratio (PER) of > 30 dB. We simulate and calculate the linewidth and injection current, while a Lorentz linewidth of 2.58 kHz is obtained based on delayed self-heterodyne beat frequency measurement. This flexible and cost-effective solution allows realization of a compact ECSL with linear polarization and a narrow linewidth. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the ultrathin membranes of poly(sodium-p-styrenesulfonate) (PSS) and poly-dimethyl diallyl ammonium chloride (PDDA) are assembled on the surface of long period fiber gratings (LPFGs). The experiments indicate that the transmission spectra characteristics of LPFGs have greater change when bilayer number changed from 75 to 130. The action of sodium nitrite on the LPFGs is researched. The LPFGs without assembled films are not able to distinguish the concentrations of sodium nitrite solutions in the range of 0.001–0.2mol/L. However, LPFGs assembled polyelectrolyte films of 130bilayers have a higher distinguishability for these concentrations of sodium nitrite. With the increase of sodium nitrite concentrations, the center wavelengths of attenuation bands gradually shift towards the longer wavelength and represent a good linear relationship with concentrations. The method has the advantages such as low cost, no toxin, fast speed, no time limit. It is hopeful to be applied in real-time and on-line monitoring of sodium nitrite. [Copyright &y& Elsevier]

In this letter a simple method for fabricating tunable sampled nonlinearly chirped fiber Bragg gratings (SNCFBGs) is demonstrated experimentally. A SNCFBG is formed when tension is applied to an etched sampled fiber Bragg grating (SFBG), whose cross-section area's reciprocal varies along the length of the SFBG. The chirp of the grating period and the sampled period can be tuned by adjusting the strain gradients, and the dispersion and dispersion slope can also be compensated. [ABSTRACT FROM AUTHOR]

Background: Two-dimensional speckle-tracking echocardiography (2D-STE) enables objective assessment of left atrial (LA) deformation through the analysis of myocardial strain, which can be measured by different speckle-tracking software. The aim of this study was to compare the consistency of 3 different commercially available software, which include vendor-specific software for measuring left ventricle (VSSLV), vendor-independent software packages for measuring LV strain (VISLV) and vendor-independent software packages for measuring LA strain (VISLA).Methods: Sixty-four subjects (mean age: 44 ± 16 years, 50% males) underwent conventional echocardiograms using a GE Vivid 9 (GE Ultrasound, Horten, Norway) cardiac ultrasound system. Standard apical 4 and 2 chamber views of the left atrium were obtained in each subject with a frame-rate range of 40-71 frames/s. LA strain during the contraction phase (Sct), conduit phase (Scd), reservoir phase (Sr = Sct + Scd) were analyzed by 2 independent observers and 3 different software.Results: Sct, Scd, Sr were, respectively, - 11.26 ± 2.45%, - 16.77 ± 7.06%, and 28.03 ± 7.58% with VSSLV, - 14.77 ± 3.59%, - 23.17 ± 10.33%, and 38.23 ± 10.99% with VISLV, and - 14.80 ± 3.88%, - 23.94 ± 10.48%, and 38.73 ± 11.56% when VISLA was used. A comparison of strain measurements between VSSLV and VIS (VISLV and VISLA) showed VIS had significantly smaller mean differences and narrower limits of agreement. Similar results were observed in the coefficient of variation (CV) for measurements between VSSLV and VIS (VISLV and VISLA). Comparison of the intra-class correlation coefficients (ICCs) indicated that measurement reliability was weaker with VSSLV (ICC < 0.6) than with VIS (VISLV and VISLA) (ICC > 0.9). For intra-observer ICCs, VISLA > VSSLV = VISLV. For inter-observer ICCs, VSSLV > VISLA > VISLV.Conclusions: Software measurement results of LA strain vary considerably. We recommended not measuring LA strain across vendor platforms. [ABSTRACT FROM AUTHOR]