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Abstract: Historically monitoring of grazing impacts in rangelands has been seriously compromised by the small area, infrequency and variability of field-based sampling plots. Remote sensing of vegetation cover, which can be a surrogate for overall ecosystem condition, permits adequate spatial and temporal monitoring of land condition but can still be compromised by considerable inter and intra-paddock (field) variability. Cross-fence sample pairs control for local clines and patchiness in spatial and temporal variables such as vegetation, landform, soil type, surface-flows, and rainfall. We describe the theory behind a novel monitoring methodology that utilizes cross-fence sample pairs to rank paddocks, whether adjacent or not, using a system of linear equations and field based or preferably remotely-sensed data. This methodology outputs a condition ranking for each paddock in the system, with the aforementioned spatial and temporal variables controlled. Within paddock variability, such as differential grazing distribution, can be readily incorporated as weighting factors when suitable models are developed. This methodology may also be applicable to other grazing, agricultural and natural systems and applications where land management units have distinguishable boundaries. [Copyright &y& Elsevier]

• A dual-functional C-type fiber SPR biosensor for simultaneous DNA hybridization and temperature sensing is proposed. • Dual SPR effects were realized on the open microcavity by coating with a gold film and fillingwith thePDMS. • The sensor exhibits high sensitivity, with a response of 0.11 nm/nM for DNA molecules and −1.97 nm/℃ for temperature. • The limit of detection (LOD) for DNA molecules is 7.9 nM. • This compact sensor offers a promising approach for DNA detection with integrated temperature compensation. In this work, an integrated temperature compensated surface plasmon resonance (SPR) biosensor based on C-type special fiber is proposed and its application to DNA hybridization is demonstrated. Dual SPR effects were realized on the open microcavity by coating the C-type fiber with a gold film and filling the open microcavity with the temperature-sensitive material polydimethylsiloxane (PDMS). One effect occurs at the gold-analyte interface, where the presence of target DNA molecules interacting with the probe DNA immobilized on the fiber surface modulates the SPR response. The other effect occurs at the PDMS-gold interface, where temperature changes cause the change of PDMS refractive index (RI), altering the SPR response. The proposed sensor demonstrates exceptional capabilities. It can simultaneously detect DNA hybridization and temperature with high sensitivity. Specifically, the sensor exhibits a response of 0.11 nm/nM for DNA molecules and a significant response of −1.97 nm/°C for temperature. Additionally, it boasts a low limit of detection (LOD) of 7.9 nM, making it suitable for applications where early detection is crucial. Beyond its impressive performance, the sensor offers the advantages of compactness and ease of fabrication. This combination makes it a promising candidate for integration into portable devices, enabling on-site and real-time DNA detection with integrated temperature compensation. [ABSTRACT FROM AUTHOR]

• An optofluidic DNA biosensor based on suspended core fiber (SCF) whispering gallery mode has been proposed. • The proposed DNA biosensor has a limit of detection of 1.5 nM. • The proposed DNA biosensor provides a label-free method for DNA detection. • This DNA biosensor has great potential for multiplexed detection and realizing disease diagnostics. An optofluidic DNA biosensor based on a suspended core fiber (SCF) has been proposed for the detection of specific DNA sequence fragments. The sensor is formed by coupling a micro/nano tapered optical fiber to the cladding of an SCF, producing a whispering gallery mode (WGM) effect. The WGM resonance is sensitive to samples within the channels of the SCF. The diameter of the SCF is reduced by etching to increase refractive index sensitivity, up to 274 nm/RIU. Biomarkers are captured on the inner surface of the microfluidic channel leading to a change in the local refractive index. The experimental results show that the sensor can quantitatively detect complementary DNA (cDNA) by immobilizing probe DNA (pDNA) on the surface of the microfluidic channel with a limit of detection of 1.5 nM. The proposed DNA biosensor provides a label-free method for DNA detection, which has great potential for multiplexed detection and realizing disease diagnostics. [ABSTRACT FROM AUTHOR]

Nitric oxide plays a crucial role as a messenger in biological systems, but limitations in measurement are restricted due to its relatively low concentration and short half-life time. Here we report a novel approach to sensing nitric oxide by using an exposed core fiber with its core coated with CdTe/CdS core/shell quantum dots. This enables rapid detection and opens up the possibility of monitoring its production within biological systems. The detection mechanism is based on fluorescence quenching of CdTe/CdS quantum dots by nitric oxide, which can coordinate with Cd 2+ directly as a ligand forming transition metal complexes. We demonstrate that CdTe/CdS quantum dots functionlization exposed core optical fibers can respond rapidly to nitric oxide in physiological environments with picomolar sensitivity. [ABSTRACT FROM AUTHOR]

A novel, high sensitivity Sagnac-interferometer biosensor based on exposed core microstructured optical fiber (ECF) has been designed and implemented in this paper. The exposed core fiber has noncircular symmetry and thus exhibits birefringence and can form a sensing element within a Sagnac loop interferometer. The exposed-core fiber design provides direct access to the evanescent field, allowing the measurement of bulk refractive index (RI) with a sensitivity of up to −3137 nm/RIU while maintaining the fiber’s robustness. The sensor can also detect the localized refractive index changes at the fiber core’s surface as the result of a biological binding event. We demonstrate the use of this sensor for label-free sensing of biological molecules by immobilizing biotin onto the fiber core as the probe to capture the target molecule streptavidin. [ABSTRACT FROM AUTHOR]

A fiber Bragg grating was inscribed in an abrupt fiber taper using a femtosecond laser and phase-mask interferometer. The abrupt taper transition allows to excite a broad range of guided modes with different effective refractive indices that are reflected at different wavelengths according to Bragg’s law. The multimode-Bragg reflection expands over 30 nm in the telecom-C-band. This corresponds to a mode-field overlap of up to 30% outside of the fiber, making the device suitable for evanescent field sensing. Refractive index and temperature measurements are performed for different reflection peaks. Temperature independent refractive index measurements are achieved by considering the difference between the wavelength shifts of two measured reflection peaks. A minimum refractive index sensitivity of 16 ± 1 nm/RIU was obtained in a low refractive index regime (1.3475–1.3720) with low influence of temperature (−0.32 ± 0.06 pm/°C). The cross sensitivity for this structure is 2.0 × 10 −5  RIU/°C. The potential for simultaneous measurement of refractive index and temperature is also studied. [ABSTRACT FROM AUTHOR]