Theoretical and Experimental Analysis of the Directional RI Sensing Property of Tilted Fiber Grating

In this article, we have theoretically and experimentally investigated the unique vector refractive index (RI) sensing property of tilted fiber grating (TFG). Due to the orthogonal symmetric grating structure, TFGs would mainly achieve the coupling between the fiber core mode and the two orthogonal polarization LP1m of cladding mode. And the numerical simulation results showed that the coupling coefficient between fundamental core mode to the LP1m cladding mode is higher than the others. In the experiment, we have furthermore observed the cladding mode field distribution of excessively TFG (Ex-TFG) and long period fiber grating (LPFG), which indicated that the evanescent field distribution of cladding mode of TFG shows an asymmetric near field distribution with two lobes oriented along the fast axis of TFG, and the one of LPFG has a circularly symmetric cladding mode field distribution. In addition, by employing side-immersion method, we have measured the azimuth RI sensitivities of Ex-TFG, tilted fiber Bragg grating (TFBG) and LPFG, which exhibited that both Ex-TFG and TFBG have shown a direction-dependency RI sensitivity, and the RI sensitivity with side-immersion along fast axis is almost half of the one along slow axis, and the RI sensitivity of LPFG is azimuth independent. Overall, the experiment results show that the TFGs inherently show unique directional RI sensing property, which could be potentially applied in vector sensing area

Excessively tilted fiber grating sensors

The development of excessively tilted fiber gratings (Ex-TFGs) provides a new type of sensing device with high refractive index (RI) sensitivity, low thermal crosstalk and vector sensing property. Due to the asymmetric grating structure of Ex-TFG, the light in the core is coupled into high order forward-propagating cladding modes and split into two orthogonal polarization states, resulting in dual-peak resonances in the transmission spectrum. The Ex-TFG also exhibits a non-circularly symmetrical near field distribution, which endows an exceptional orientation sensing capability. Benefitting from the unique mode coupling behavior, Ex-TFGs have been studied and developed for many different sensing applications, such as polarization dependent torsion and loading sensors, vector accelerometer and magnetometer, and a variety of low thermal crosstalk bio/chemical sensors. This paper will review the recent study and development of Ex-TFGs in terms of mode coupling mechanism, fabrication method, transmission and sensor characteristics and the novel applications in sensing areas

A Computational Method for Optimizing Experimental Environments for Phellinus igniarius via Genetic Algorithm and BP Neural Network

Flavones, the secondary metabolites of Phellinus igniarius fungus, have the properties of antioxidation and anticancer. Because of the great medicinal value, there are large demands on flavones for medical use and research. Flavones abstracted from natural Phellinus can not meet the medical and research need, since Phellinus in the natural environment is very rare and is hard to be cultivated artificially. The production of flavones is mainly related to the fermentation culture of Phellinus, which made the optimization of culture conditions an important problem. Some researches were made to optimize the fermentation culture conditions, such as the method of response surface methodology, which claimed the optimal flavones production was 1532.83 g/mL. In order to further optimize the fermentation culture conditions for flavones, in this work a hybrid intelligent algorithm with genetic algorithm and BP neural network is proposed. Our method has the intelligent learning ability and can overcome the limitation of large-scale biotic experiments. Through simulations, the optimal culture conditions are obtained and the flavones production is increased to 2200 g/mL

Sensitivity adjustable biosensor based on graphene oxide coated excessively tilted fiber grating

Biosensors play a significant role in biomedical, clinical and disease diagnosis areas. Here, we proposed Langmuir adsorption model to explain sensing mechanism of biosensor based on excessively tilted fiber grating (Ex-TFG) functionalized with graphene oxide (GO). Due to GO containing plenty of six-membered rings and oxygen-containing groups, the biomolecules can be easily adsorbed through π-π interaction and hydrogen bond. The whole interaction process obeys the Langmuir adsorption model in which there always an equilibrium during detecting process, inducing the sensor with adjustable bio-sensitivity and detection range. Three biosensors based on Ex-TFG coated with three different amount of GO were investigated for hemoglobin (Hb) detection experiment, showing pronounced bio-interaction induced resonance shifts. The experiment results indicate that GO coating could enhance the surface biological activity of Ex-TFG, making the Ex-TFG sensitive to the Hb biomolecule solutions. The three GO coated Ex-TFG sensors have the bio-sensitivity of 3.83 nm/(mg/ml), 4.33 nm/(mg/ml), and 8.21 nm/(mg/ml), and the detection range of 0.8 mg/ml, 0.6 mg/ml and 0.4 mg/ml, respectively, which are in good agreement with the prediction from the Langmuir adsorption model. By controlling the amount of the bio-functionalized materials, the bio-sensitivity and detection range of the Ex-TFG based biosensors can be easily adjusted

Optimization to the Culture Conditions for Phellinus Production with Regression Analysis and Gene-Set Based Genetic Algorithm

Phellinus is a kind of fungus and is known as one of the elemental components in drugs to avoid cancers. With the purpose of finding optimized culture conditions for Phellinus production in the laboratory, plenty of experiments focusing on single factor were operated and large scale of experimental data were generated. In this work, we use the data collected from experiments for regression analysis, and then a mathematical model of predicting Phellinus production is achieved. Subsequently, a gene-set based genetic algorithm is developed to optimize the values of parameters involved in culture conditions, including inoculum size, PH value, initial liquid volume, temperature, seed age, fermentation time, and rotation speed. These optimized values of the parameters have accordance with biological experimental results, which indicate that our method has a good predictability for culture conditions optimization

The impact of education/training on nurses caring for patients with stroke: a scoping review

Abstract Background Stroke survivors have complex needs that necessitate the expertise and skill of well-trained healthcare professionals to provide effective rehabilitation and long-term support. Limited knowledge exists regarding the availability of specialized education and training programs specifically designed for nurses caring for stroke patients. Aim This review aims to assess the content and methods of training for nurses caring for stroke patients, examine its impact on both nurses and patients, and identify key facilitators and barriers to its implementation. Methods We conducted a comprehensive scoping review by reviewing multiple databases, including PubMed, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, Embase, Web of Science, Scopus, ProQuest Dissertations and Theses, Google Scholar, and Cochrane databases. Data extraction and narrative synthesis were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. Results Seventeen articles were included in this review. We found that education/training not only enhanced patients' self-care abilities, nursing outcomes, and satisfaction, but also had a positive impact on the knowledge, skills, and practices of nurses. The obstacles to education/training included feasibility and cost-effectiveness, while the driving factors were management support and participation, professional education/training, and controlled environment creation. Conclusions This review highlights the crucial role of education/training in enhancing stroke care provided by nurses. Effective education/training integrates various educational methods and management support to overcome implementation barriers and optimize clinical practice benefits. These findings indicate the necessity of universal and consistent stroke education/training for nurses to further improve patient outcomes in stroke care

Excessively tilted fiber grating-based vector magnetometer

A compact optic-fiber vector magnetometer is proposed and experimentally demonstrated, which is based on an excessively tilted fiber grating (Ex-TFG) assistant with the magnetic fluid (MF). Without any complicated processing, the cladding mode resonances of the bare Ex-TFG packaged by the MF show high sensitivity to slight perturbations by the magnetic field. Due to the excellent magneto-optical properties of the MF and the azimuth-dependent refractive index sensitivity of the Ex-TFG, such a magnetometer can achieve the magnetic field intensity sensitivity of 2.45 nm/mT and the orientation sensitivity of 0.41 nm/ deg. In addition, based on the spectral interrogation, the detection limit of the magnetic field intensity could reach around 8.1 μT at the minimum wavelength measurement accuracy of 0.02 nm