Strong Linear Response Research Articles

All-solid-state electrochemical marine sensors based on Na3V2(PO4)3@Na4Zr2Si3O12 solid-state reference electrodes

In this study, Na4Zr2Si3O12 (NZS) solid electrolyte was prepared using an elevated-temperature solid-state method. After heating under supercritical conditions (i.e., 400 °C and 40 MPa), the structure and performance stability of the as-fabricated NZS solid electrolyte were evaluated applying scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). A new all-solid-state reference electrode, combining Na3V2(PO4)3(NVP) with NZS (NVP@NZS), was developed, and its electrochemical properties were investigated. The prepared reference electrode demonstrated steady potential in both simulated seawater and buffer solutions across a range of pH values and different salt solutions. The reference electrode, integrated with an Ir/IrO2 working electrode, was used to construct an all-solid-state potentiometric pH sensor. This sensor demonstrated a strong linear related response when measuring the pH of both aqueous solutions and simulated seawater samples. Additionally, an ion sensor based on anodic stripping voltammetry, constructed with the assembled solid-state reference electrode, a platinum counter electrode, and a gold-mercury working electrode, was utilized to measure Cu2+ and S2− ions in both aqueous solutions and simulated seawater samples. These all-solid-state electrochemical sensors, incorporating the NVP@NZS solid-state reference electrode, demonstrated a small detection threshold, excellent linear correlation (R2 > 0.99), and a broad detection range, making them well-suited for chemical analysis in challenging marine environments.

Nickel-doped tungsten fabricated electrode for electrochemical sensing of amoxicillin

One of the most popular antibiotics used in human medicine is amoxicillin (AML). It is frequently applied to humans and animals to avoid or treat infections caused by bacteria. However, considering its widespread application and excessive use of AML, it could harm the environment and the general world because of the hazardous potential of its pharmaceutical industry effluents. Additionally, some unpleasant compounds might be left behind due to the extensive use of these animals in food production. Hence, AML may be the root cause of several illnesses, including rashes, nausea, vomiting, and colitis linked to antibiotics, if it is present in biological fluids in sufficient quantities. Aquatic habitats where it accumulates can give rise to bacterial species that are susceptible to it. Novel electroanalytical methods with sensitive and quick examination abilities are required to identify and quantify the level of AML in drugs, biological fluids, environmental pollutants, and foods. We have developed a novel sensor that quantitatively detects AML using a modified carbon paste electrode containing nickel-doped tungsten oxide (Ni-WO3). Findings show that Ni-WO3 acts as an electrocatalyst in the oxidation of AML. AML-wide concentration showed a strong linear response from this electrocatalytic oxidation encompassing the range of 0.05 μM to 0.9 μMwith a low detection limit of 8.68 × 10−9 M. As a result, the current electrocatalytic method provides a quick, accurate, and simple method to detect AML in biological medium and pharmaceutical formulations. A sensor with excellent reproducibility, short response times, and outstanding stability has been described as the modified electrode.

Hook-Like DNAzyme-Activated Autocatalytic Biosensor for the Universal Detection of Pathogenic Bacteria.

DNAzyme-based assays have found extensive utility in pathogenic bacteria detection but often suffer from limited sensitivity and specificity. The integration of a signal amplification strategy could address this challenge, while the existing combination methods require extensive modification to accommodate various DNAzymes, limiting the wide-spectrum bacteria detection. We introduced a novel hook-like DNAzyme-activated autocatalytic nucleic acid circuit for universal pathogenic bacteria detection. The hook-like connector DNA was employed to seamlessly integrate the recognition element DNAzyme with the isothermal enzyme-free autocatalytic hybridization chain reaction and catalytic hairpin assembly for robust exponential signal amplification. This innovative autocatalytic circuit substantially amplifies the output signals from the DNAzyme recognition module, effectively overcoming DNAzyme's inherent sensitivity constraints in pathogen identification. The biosensor exhibits a strong linear response within a range of 1.5 × 103 to 3.7 × 107 CFU/mL, achieving a detection limit of 1.3 × 103 CFU/mL. Noted that the sensor's adaptability as a universal detection platform is established by simply modifying the hook-like connector module, enabling the detection of various pathogenic bacteria of considerable public health importance reported by the World Health Organization, including Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Salmonella typhimurium. Additionally, the specificity of DNAzyme in bacterial detection is markedly improved due to the signal amplification process of the autocatalytic circuit. This hook-like DNAzyme-activated autocatalytic platform presents a versatile, sensitive, and specific approach for pathogenic bacteria detection, promising to significantly expand the applications of DNAzyme in bacteria detection.

Hemp Seed Yield Responses to Nitrogen Fertility Rates

Industrial hemp (Cannabis sativa L.) holds promise as a crop for more sustainable supply chains given its potential as a source of high-strength fibers, adsorbents, and nutrient-dense feedstuffs. Developing nutrient management guidelines for hemp will be an important part of optimizing the crop’s sustainability attributes. This study measured hemp seed yield in response to N fertilization rate (0, 60, 120, 180, and 240 kg N ha−1). Treatments were tested with four hemp cultivars (‘Joey’ and ‘Grandi’ in 2020, 2021, and 2022 and ‘NWG 2463’ and ‘NWG 4113’ in 2023) in Virginia. Nitrogen input influenced (p ≤ 0.0177) seed yield in all four experimental years, although the pattern of response varied substantially. In 2020, following delayed seeding, hemp showed a weak quadratic (p = 0.0113) response to N inputs, with peak yield (1640 kg ha−1) occurring with 120 kg N ha−1. In 2021, hemp displayed a strong linear (p < 0.0001) response to N inputs, with the highest seed yield (2510 kg ha−1) at 240 kg N ha−1. In 2022, a season characterized by low precipitation and high weed pressure, a weak, linear (p = 0.0111) response to the N rate was observed. The greatest seed yield (380 kg ha−1) was again observed with 240 kg N ha−1. In 2023, weed pressure remained an issue, but the response to N was strong and linear (p < 0.0001), with the greatest seed yield (831 kg ha−1) again measured at 240 kg N ha−1. These findings indicate hemp can be quite responsive to N inputs but that the magnitude of response is sensitive to other factors such as available soil moisture, weed pressure, and growing period.

Experimental evaluation of electrospun ZnO/WO3/PVA-coated glass nanocomposites for a potential radiation dosimetry application

This research aimed to fabricate a potential radiation dosimeter using electrospun ZnO/WO3/PVA-coated glass nanocomposites. Samples with varying ZnO molarities (2.46, 3.69, 4.91, 5, and 7 M) and 5 wt% of WO3 collected at different times were examined. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX) revealed favorable nanofiber morphology, although certain conditions produced larger nanofibers. The optical properties, analyzed via ultraviolet–visible (UV–Vis) spectroscopy, exhibited varying responses in different samples with changes in nanofiber collection time. The calculated optical energy band gap (Eg) for all samples is lower than Eg of pure ZnO. Moreover, the effective atomic number (Zeff), calculated based on EDX results, did not approach Zeff of human tissues, in all samples in general. Crucially, all samples demonstrated a strong linear response and low energy dependence when subjected to different X-ray exposure settings, closely resembling an Al2O3-based OSL dosimeter. Sample E3, consisting of 7.00 M ZnO and 5 wt% of WO3 collected over 4 h, emerged as the most promising candidate for a radiation dosimeter. Prior studies neglected to examine the influence of different amounts of ZnO on the radiation dosimetry properties of ZnO/WO3/PVA nanofibers. In contrast, this study specifically investigated the radiation dosimetry properties of ZnO/WO3/PVA nanofibers. The exceptional properties of ZnO in response to X-rays, combined with the desired X-ray attenuation capabilities of WO3, make them a distinct option as substitute materials in radiation dosimeters. This research paves the way for an alternative dosimeter solution with robust radiation detection capabilities.

Assessing the Precision of Radon Measurements from Beta-Attenuation Monitors

Atmospheric radon measurements assist in many aspects of climate and meteorological research, notably as an airmass tracer and for modelling boundary layer development, mixing heights and stability. Daughter products from radon decay are sometimes incorporated into the particle pollution measurements of commercially available beta-attenuation monitors (BAM). BAMs incorporating radon measurements are used in air quality monitoring networks and can supplement traditional radon measurements. Here we compare in-situ radon measurements from Thermo Fisher Scientific (Franklin, MA, USA) BAM instruments (Thermo Scientific 5014i, Thermo Scientific 5030 SHARP, Thermo Anderson FH62C14) at two air quality monitoring stations in New South Wales, Australia. Between systems we find strong correlations for hourly measurements (r = 0.97–0.99); daily means (r = 0.97–0.99); hour of the day (r = 0.84–0.98); and month (r = 0.82–0.98). The regression analysis for radon measurements between systems showed strong linear responses, although there are some variations in the slopes of the regressions. This implies that with correction BAM measurements can be comparable to standard measurement techniques, for example, from the Australian Nuclear Science and Technology Organisation (ANSTO) dual flow loop monitors. Our findings imply that BAM derived radon measurements are precise, although their accuracy varies. BAM radon measurements can support studies on boundary layer development or where radon is used as an atmospheric transport tracer.

Prediction of two-dimensional 2H-M2O3 (M = Ti and Zr) with strong linear and non-linear optical response in the infrared range

Single-layer 2H-M2O3 (M = Ti and Zr) is predicted with a strong linear optical and second-harmonic generation response in the infrared range.

Terbium alginate encapsulated CsPbI3@Pb-MOF: a ratiometric fluorescent bead for detection and adsorption of Fe3.

Halide perovskite nanocrystals are innovative luminescent materials for fluorescent probes with high quantum yield and narrow emission bandwidth. However, the limited stability, single-signal response, and separation challenges obstruct their widespread use in water ion detection. Herein, a ratiometric fluorescence sensor based on terbium alginate gel beads (green fluorescent, namely Tb-AG) embedded with powdered CsPbI3@Pb-MOF (red fluorescent) was prepared for fluorescent determination and adsorption of Fe3+. Pb-MOF's protection notably enhances the water stability of CsPbI3, while the energy transfer between CsPbI3@Pb-MOF and Tb3+ elevates the optical performance of CsPbI3@Pb-MOF@Tb-AG. Significantly, Fe3+ markedly suppresses CsPbI3@Pb-MOF red fluorescence at 647 nm, while not noticeably affecting Tb-AG green emission at 528 nm. The sensor exhibited a strong linear response to Fe3+ concentrations ranging from 0 to 90 μM, with a detection limit of 0.44 μM and high selectivity. The CsPbI3@Pb-MOF@Tb-AG-based sensor has been effectively validated through its successful use in detecting Fe3+ in tap and river water samples. Furthermore, CsPbI3@Pb-MOF@Tb-AG demonstrates a notable adsorption capacity of 325.4 mg g-1 Fe3+. Finally, the mechanism of Fe3+ detection and adsorption was determined.

High-Linearity Wireless Passive Temperature Sensor Based on Metamaterial Structure with Rotation-Insensitive Distance-Based Warning Ability.

A wireless passive temperature sensor based on a metamaterial structure is proposed that is capable of measuring the temperature of moving parts. The sensor structure consists of an alumina ceramic substrate with a square metal double split-ring resonator fixed centrally on the ceramic substrate. Since the dielectric constant of the alumina ceramic substrate is temperature sensitive, the resonant frequency of the sensor is altered due to changes in temperature. A wireless antenna is used to detect the change in the resonant frequency of the sensor using a wireless antenna, thereby realizing temperature sensing operation of the sensor. The temperature sensitivity of the sensor is determined to be 205.22 kHz/°C with a strong linear response when tested over the temperature range of 25-135 °C, which is evident from the R2 being 0.995. Additionally, the frequency variation in this sensor is insensitive to the angle of rotation and can be used for temperature measurement of rotating parts. The sensor also has a distance warning functionality, which offers additional safety for the user by providing early warning signals when the heating equipment overheats after operating for extended durations.

Q-switched fiber laser operating at 1560 nm modulated by Cr3C2 film

Chromium carbide (Cr3C2), as a kind of transition metal carbides, has exhibited extraordinary optoelectronic properties and aroused enormous attention. However, few reports have been focused on the nonlinear properties and relevant devices. In this study, we first demonstrated a novel Cr3C2 saturable absorber (SA). Cr3C2 with an average size of 200 nm was prepared through a low temperature salt flux synthetic method. The Cr3C2-film SA exhibited high robustness and strong linear and nonlinear saturable absorption response at 1560 nm. As the Cr3C2 SA was inserted into the Er3+-doped fiber laser cavity, Q-switched pulses were generated with a central wavelength of 1560 nm. To the best of our knowledge, this was the first report on the optical nonlinearity of Cr3C2 as a Q-switcher for the near-infrared fiber laser. Our experimental results verified that the integrated Cr3C2-based device possessed great potential as a nonlinear optical medium for high-performance optical applications.

Stability-indicating RP-HPLC method applied to the quantification of anti-histaminic drug ebastine in its oral suspension dosage form

For the quantification of ebastine in pharmaceutical suspension, a simple, quick, accurate, and exact stability-indicating HPLC approach was developed and validated. The drug was determined using a phase reverse system and the separation was performed in an analytical C18 column (250 mm x 4.6 mm, 5 μm). The mobile phase consists of 0.1% orthophosphoric acid and methanol in a 25:75, v/v ratio. Using a concentration range of 10–90 μg mL-1, the technique demonstrated a strong linear response (r=0.999). Effluents were measured at 262 nm while the flow rate was kept at 1.0 mL min-1. There was a retention time of 3.506 min. The method was statistically validated to determine its accuracy, precision, linearity, ruggedness, robustness, solution stability, selectivity, and forced degradation assessments. The stresses that were used were acid, alkali hydrolysis, water stress, oxidation, photolysis, and heat. Since the degradation products did not affect the capacity to identify ebastine, this technique may be taken as a stability indication. This methodology may be utilized for the analysis of Ebastine in pharmaceutical suspension, since the findings obtained were within the limits set by ICH standards.

Interdecadal to Centennial Climate Variability Surrounding the 8.2 ka Event in North China Revealed Through an Annually Resolved Speleothem Record From Beijing

AbstractThe 8.2 ka event has been extensively studied, whereas its structure is ambiguous in North China. Here we present a high‐resolution (∼1 year) δ18O record from annual laminated speleothem from Beijing to characterize the detailed variability across this event in North China. Our record indicates a dry 8.2 ka event spanning 8.254–8.107 ka BP with a two‐stage structure superimposed by three prominent high δ18O excursions. The identical structure of speleothem δ18O records between North and central China during the event suggests a common forcing/response in East China, whereas the progressively increased offset between their average values may reflect changes in moisture source or rainout effect. A close comparison with the Greenland ice core records suggests a strong linear response of the Asian summer monsoon to the North Atlantic climate changes across the early and middle stages of the event, but a different mechanism in the termination processes.

Sensitivity analysis of designed apodized fiber Bragg grating sensor using artificial neural network and tree-based models

An apodized FBG is designed to eliminate the side lobes from the reflectivity spectrum for the sensitivity measurement of physical parameters including temperature, strain, and pressure. The impact of the proposed apodization function is discussed with several other apodization profiles for the elimination of side lobes from the FBG spectrum. The sensitivity of the measurand is measured by analyzing the changes that occur in the Bragg wavelength, which is sensitive to the physical parameters. A strong linear response has been observed for the sensitivity of temperature, strain, and pressure for the designed apodized FBG. Machine Learning (ML) methods such as Artificial Neural Network (ANN) and Tree-based models are implemented for the predictive analysis of physical parameters and their respective Bragg wavelength shifts for the reliability of the designed apodized FBG sensor to achieve improved sensing outcomes, particularly to work in a hazardous environment for understanding any adverse scenario of a measurand. Decision Tree (DT) and Random Forest (RF) are used as Tree-based models in this work. Different statistical measures are introduced to evaluate the predictive analysis performance of the ML models. It has been observed that the predictive analysis performance of the ANN is better compared to the Tree-based models.

The influence of grass competition and soil moisture on the growth and phenology of Karoo shrubs in the Eastern Upper Karoo

Rainfall in the Nama-Karoo is sporadic and a plant’s ability to access and utilise available soil moisture will determine its ability to persist in the system and to successfully recruit. When summer rainfall in the Eastern Karoo increases, grassiness increases at the expense of shrub canopy cover. This may drive a transition from shrubland toward grassland. The effect of grass–shrub competition on shrub growth and phenology in the Eastern Karoo is not adequately explained by the root–niche separation hypothesis or the succession hypothesis. In an experiment, we measured shrub growth and phenology in the absence (clipping treatment) and presence (control treatment) of grass over the 2017/2018 rainfall season. Grass clipping changed grass species composition over this period, but grass clipping did not benefit shrubs. We found no competitive effect of grasses on shrubs. However, shrub canopy cover showed a strong linear response to soil moisture, as did canopy cover to temperature. Similarly, soil moisture and temperature were important for stem growth and shrub phenology. Patterns of shrub growth and phenology in response to summer and winter rainfall provide important insight for land managers for optimising production while enabling phenological processes that allow recruitment to take place.

Direct Epitaxial Growth of InP Nanowires on MoS2 with Strong Nonlinear Optical Response

Mixed-dimensional van der Waals heterostructures are promising for research and technological advances in photonics and optoelectronics. Here we report vapor–liquid–solid (VLS) method-based van der Waals epitaxy of one-dimensional InP nanowires (NWs) directly on two-dimensional MoS2. With optimized growth parameters (V/III ratio, flow rates of precursors, and growth temperature), we successfully grow high-quality InP NWs on MoS2. The density and vertical yield of NWs on MoS2 are significantly high. Due to the unique properties of both materials, we observe strong linear and nonlinear optical responses from the NW/MoS2 heterostructures. Intriguingly, in addition to strong second and third harmonic responses, the mixed-dimensional heterostructures show odd-order high harmonic generation up to seventh order. Our findings can open new possibilities for advancing attosecond physics on a new platform of mixed-dimensional heterostructures.

A Hybrid Antiperovskite with Strong Linear and Second-Order Nonlinear Optical Responses.

Antiperovskites have been studied since the 1980s because of their rich physical and chemical properties, but their linear and second-order nonlinear optical responses remain largely unknown. Here we report a new polar crystal, Cs3 Cl(HC3 N3 S3 ) (I), which features a quasi-one-dimensional antiperovskite structure composed of ClCs6 polyhedra and A-site [HC3 N3 S3 ]2- rings. To our best knowledge, this kind of antiperovskite structure is reported for the first time. Remarkably, I exhibits a very strong nonlinear optical response up to 11.4 times that of the benchmark KH2 PO4 and exceptionally large birefringence of 0.52. The first-principles calculations and structural analyses reveal that [HC3 N3 S3 ]2- is the "material gene" while the antiperovskite structural feature making it in a favorable arrangement. This work provides a new structural platform for the rational design of integrated optoelectronic materials with linear and second-order nonlinear optical responses.

A direct comparison of the optically stimulated luminescent properties of BeO and Al2O3 for clinical in-vivo dosimetry

Optically stimulated luminescence dosimetry is a relatively recent field of in-vivo dosimetry in clinical radiotherapy, developing over the last 20 years. As a pilot study, this paper presents a direct comparison between the sensitivity variance with use, stability of measurement and linearity of the current clinical standard Al2O3:C and a potential alternative, beryllium oxide. A set of ten optically stimulated luminescence dosimeters (OSLD), including five of each type, were used simultaneously and irradiated on a Versa HD linear accelerator. Having similar sensitivity, while Al2O3:C showed a relatively stable signal response from initial use, BeO was found to have a higher response to the same dose. However, BeO displayed a strong exponential decline from initial signal response following a model of Respons{e}_{BeO}=(0.55pm 0.05){e}^{-left(0.40pm 0.05right)x}+(0.54pm 0.01), reaching stability after approximately 10 irradiation cycles. BeO was shown to have potentially higher accuracy than Al2O3:C, with less variation between individual doses. Both OSLD showed good linearity between 0.2–5.0 Gy. Between these bounds, Al2O3:C demonstrated a strong linear response following the trend Dose_{Al_{2}O_{3}, group(adj)}=(1.00pm 0.09)x-(0.02pm 0.04),{text{Gy}}, however beyond this showed deviation from linearity, resulting in a measured dose of 12.0pm 0.2 Gy at 10.0 Gy dose delivery. BeO showed strong linearity across the full examined range of 0.2–10.0 Gy with following a model of Dos{e}_{BeO, ind}=(0.98pm 0.01)x+(0.04pm 0.01) Gy with a recorded dose at 10.0 Gy delivery as 9.9pm 0.1 Gy. In conclusion, BeO does show large variance in sensitivity between individual OSLD and a considerable initial variance and decline in dose–response, however after pre-conditioning and individual normalisation to offset OSLD specific sensitivity BeO provides not only a viable alternative to Al2O3:C, but potentially provide higher accuracy, precision and reproducibility for in-vivo dosimetry.

Anisotropic optical responses of layered thallium arsenic sulfosalt gillulyite

Multi-element two-dimensional (2D) materials hold great promise in the context of tailoring the physical and chemical properties of the materials via stoichiometric engineering. However, the rational and controllable synthesis of complex 2D materials remains a challenge. Herein, we demonstrate the preparation of large-area thin quaternary 2D material flakes via mechanical exfoliation from a naturally occurring bulk crystal named gillulyite. Furthermore, the anisotropic linear and nonlinear optical properties including anisotropic Raman scattering, linear dichroism, and anisotropic third-harmonic generation (THG) of the exfoliated gillulyite flakes are investigated. The observed highly anisotropic optical properties originate from the reduced in-plane crystal symmetry. Additionally, the third-order nonlinear susceptibility of gillulyite crystal is retrieved from the measured thickness-dependent THG emission. We anticipate that the demonstrated strong anisotropic linear and nonlinear optical responses of gillulyite crystal will facilitate the better understanding of light-matter interaction in quaternary 2D materials and its implications in technological innovations such as photodetectors, frequency modulators, nonlinear optical signal processors, and solar cell applications.

Linear and nonlinear chiroptical response from individual 3D printed plasmonic and dielectric micro-helices.

Sub-wavelength chiral resonators formed from artificial structures exhibit exceedingly large chiroptical responses compared to those observed in natural media. Owing to resonant excitation, chiral near fields can be significantly enhanced for these resonators, holding great promise for developing enantioselective photonic components such as biochemical sensors based on circular dichroism (CD) and spin-dependent nonlinear imaging. In the present work, strong linear and nonlinear chiroptical responses (scattering CD > 0.15 and nonlinear differential CDs > 0.4) at visible and near infrared frequencies are reported for the first time for individual micrometer-scale plasmonic and dielectric helical structures. By leveraging dark-field spectroscopy and nonlinear optical microscopy, the circular-polarization-selective scattering behavior and nonlinear optical responses (e.g., second harmonic generation and two-photon photoluminescence) of 3D printed micro-helices with feature sizes comparable to the wavelength (total length is ∼5λ) are demonstrated. These micro-helices provide potential for readily accessible photonic platforms, facilitating an enantiomeric analysis of chiral materials. One such example is the opportunity to explore ultracompact photonic devices based on single, complex meta-atoms enabled by state-of-the-art 3D fabrication techniques.

Analytical profiling and stability evaluation of liposomal drug delivery systems: A rapid UHPLC-CAD-based approach for phospholipids in research and quality control

Phospholipids and their derivatives represent a broad range of multifunctional substances used as excipients or active ingredients by different industries due to their natural origin and unique properties. A fast and reliable quantification as well as comprehensive stability evaluation are of major importance in the process of development and quality control of lipid-based systems. Therefore, the present study is focused on the development and validation of a rapid ultra-high performance liquid chromatography – charged aerosol detector based (UHPLC-CAD) method for simultaneous detection of a multitude of natural and synthetic lipids, (charged) phospholipids, lipophilic fluorescent markers and their possible degradation products. Twenty-two compounds were characterized by a strong linear response of the detector (R2 > 0.97). Moreover, remarkable limits of detection (≤10 μg mL−1) and limits of quantification (≤25 μg mL−1) associated with a consistent reproducibility were achieved for all tested molecules. The performance of the analytical method was demonstrated by analyzing the lipid composition (after different production stages and photodegradation) of both bupivacaine loaded liposomes and a Doxil®-like formulation. The newly developed method combines a rapid, comprehensive, and efficient quantification with minimal economic effort and ecologic consequences, meeting the requirements of modern analytical processes and offering a broad range of possible applications in various industrial sectors and scientific laboratories.