Short Time Stability Research Articles

A potentiometric sensor for the determination of potassium in different baby follow–on milk, water, juice and pharmaceutical samples

Potassium is one of the minerals essential for the human body, and its intake is usually provided from foodstuffs. In this study, a novel potassium selective potentiometric sensor was developed to perform potassium analysis in baby follow–on milk, mineral water, drinking water, fruit juice and drug samples. The potassium selective sensor exhibited a low detection limit of 5.88 × 10−6 mol L−1 over a wide linear range from 1.0 × 10−5 to 1.0 × 10−1 mol L−1. The sensor had a very short response time (< 5 s), good selectivity, good repeatability and high potential stability. In addition, the developed sensor was easy to manufacture with low cost, and it worked independently of pH changes in the pH range of 6.0–10.0. The developed sensor was applied to analysis of various food, drug and water samples and potassium ion determination was carried out with very high recoveries.

Diethyl carbonate (DEC) gas sensor based on CeO2 loaded In2O3 hollow spheres for thermal runaway monitoring of Li-ion batteries

In this study, a CeO2-loaded In2O3 hollow sphere gas sensor for diethyl carbonate (DEC) gas detection was designed to predict the thermal runaway of Li-ion batteries. First, pure In2O3 and CeO2-loaded In2O3 hollow spheres were synthesized by a hydrothermal method. Then, the interaction mechanism between the material and DEC gas was proposed. Next, a DEC gas sensing unit was fabricated to test its gas sensing performance. In the atmosphere of 100 ppm DEC gas, it is concluded that the best working temperature of this sensor is 200 °C and the 2 at% CeO2–In2O3 sample has the largest response, which is about 5.2. The responses of all six samples increased with increasing gas concentration. The 2 at% CeO2–In2O3 sample had a response of 1.01–0.1 ppm DEC gas. The sensor also exhibits a short response-recovery time and long-term stability. This sensor holds great promise in predicting the thermal runaway of Li-ion batteries.

Facile synthesis of green and efficient copper-based magnetically recoverable nanocatalyst for the reduction of nitrophenol derivatives

A green and facile preparation of CuO/SiO2@Fe3O4 nanocatalysts (CuO(G)/SiO2@Fe3O4 and CuO(L)/SiO2@Fe3O4) were developed using glucose and lactose as grafting agent to place copper oxide on the surface of the magnetic nanoparticles by hydrothermal method. The structure and morphology of the prepared nanocatalysts were identified using FT-IR. XRD, XPS, BET, VSM, TGA, EDX-Mapping, FE-SEM, HRTEM and ICP-OES analyses. The catalytic activity of nanocatalysts was investigated to reduce 4-nitrophenol, 2-nitrophenol, 3-nitroaniline and 4-nitroaniline compounds using the UV–Vis spectrum. In reducing 4-nitrophenol using CuO(G)/SiO2@Fe3O4 and CuO(L)/SiO2@Fe3O4, the apparent rate constant (Kapp) were obtained 0.38 and 0.28 min−1, and activity factors (k’) were 3251 and 1396 s−1 g−1, respectively. High conversion in a short time and good stability were the advantages of the prepared nanocatalysts. The magnetic nature of the catalysts makes them easily recoverable and easy to use in multiple cycles.

Formulation, optimization and evaluation of fast dissolving tablets of Lamotrigine using natural disintegrant agent

Objective: The present investigative work is aimed for formulating, optimizing and evaluating the Fast Dissolving Tablets (FDT) of Lamotrigine in improving the disintegration time and dissolution rate with Locust bean gum as natural disintegrant agent in combination with Sodium Starch Glycolate (SSG). Methods: Employed 32 full factorial design for optimization of Lamotrigine blend formulations. Concentrations of Locust bean gum (X1) and concentration of SSG (X2) are two factor independent variables. Experiments are conducted to identify their effect on three dependent variables are disintegration time (Y1), drug release in 5 min (Y2), and drug release in 30 min (Y3). Drug interactions between Lamotrigine and Locust bean gum were investigated with FTIR, DSC, XRD compatibility studies. Direct compression method is used for tablet manufacturing. Results: Pre and post compression parameters of Lamotrigine FDT’s are evaluated and found within acceptable limits. Among multiple formulations, LF8 formulation has demonstrated lower disintegration time in 40 ± 3.81sec and wetting time in 38 ± 0.31sec, maximum drug release is 97.88% in 30min. In short time stability studies, no major transformations are identified in physical and chemical properties of Lamotrigine FDT’s. In-vivo studies of Lamotrigine fast dissolving tablets showed faster absorption rate.

Ultrasensitive and multiplex detection of four pathogenic bacteria on a bi-channel lateral flow immunoassay strip with three-dimensional membrane-like SERS nanostickers

A lateral flow immunoassay (LFA) technique for sensitive and multiplexed on-site detection of bacteria remains a challenge. Here, we develop a bi-channel surface-enhanced Raman scattering (SERS)-based LFA by using three-dimensional membrane-like SERS tags as nanostickers (named GO@Au/Ag) for direct and ultrasensitive analysis of multiple pathogens in a single test. The grafting of numerous Ag satellites onto nanosticker significantly increased the relative surface area for bacteria binding and generated efficient SERS hotspots over large area to improve the sensing sensitivity. Antibody-labeled GO@Au/Ag nanostickers can rapidly stick onto the target bacteria and generate superior SERS signals and fluidity on the paper strip, thus conquering the adverse effect of bacteria size and improving the multiplex analysis ability of LFA. The integration of two different Raman reporter molecules into nanostickers allows simultaneous detection of four pathogens on two test lines, which significantly simplifies the reading process of SERS signals. The proposed biosensor can quantitatively detect four different bacteria in real clinical samples with low detection limit (9 cells mL−1 level), short assay time (20 min), high accuracy and excellent stability, indicating its great application potential for on-site detection of pathogens.

Improved Evaluation of BBR and Collisional Frequency Shifts of NIM-Sr2 with 7.2 × 10−18 Total Uncertainty

NIM-Sr2 optical lattice clock has been developed on the Changping campus of National Institute of Metrology (NIM). Considering the limitations in NIM-Sr1, several improved parts have been designed including a differential pumping stage in the vacuum system, a permanent magnet Zeeman slower, water-cooled anti-Helmholtz coils, an extended viewport for Zeeman slower, etc. A clock laser with a short-time stability better than 3 × 10−16 is realized based on a self-designed 30-cm-long ultra-low expansion cavity. The systematic frequency shift has been evaluated to an uncertainty of 7.2 × 10−18, with the uncertainty of BBR shift and the collisional frequency shift being an order of magnitude lower than the last evaluation of NIM-Sr1.

Edge-enriched MoS2 nanosheets modified porous nanosheet-assembled hierarchical In2O3 microflowers for room temperature detection of NO2 with ultrahigh sensitivity and selectivity

Nitrogen dioxide (NO2) is one of the most hazardous toxic pollutants to human health and the environment. However, deficiencies of low sensitivity and poor selectivity at room temperature (RT) restrain the application of NO2 sensors. Herein, the edge-enriched MoS2 nanosheets modified porous nanosheets-assembled three-dimensional (3D) In2O3 microflowers have been synthesized to improve the sensitivity and selectivity of NO2 detection at RT. The results show that the In2O3/MoS2 composite sensor exhibits a response as high as 343.09–5 ppm NO2, which is 309 and 72.5 times higher than the sensors based on the pristine MoS2 and In2O3. The composite sensor also shows short recovery time (37 s), excellent repeatability and long-term stability. Furthermore, the response of the In2O3/MoS2 sensor to NO2 is at least 30 times higher than that of other gases, proving the ultrahigh selectivity of the sensor. The outstanding sensing performance of the In2O3/MoS2 sensor can be attributed to the synergistic effect and abundant active sites originating from the p-n heterojunction, exposed edge structures and the designed 2D/3D hybrid structure. The strategy proposed herein is expected to provide a useful reference for the development of high-performance RT NO2 sensors.

Prediction of Carbon Dioxide Solubility in Polymers Based on Adaptive Particle Swarm Optimization and Least Squares Support Vector Machine

AbstractSolubility is a significant physical and chemical property. The solubility of carbon dioxide(CO2) in polymers is an important application of green chemistry. Aimed at the problem of insufficient precision of the existing prediction model, a solubility prediction model based on the adaptive particle swarm optimization algorithm and the least‐squares support vector machine(APSO‐LSSVM) is proposed. Different from the traditional particle swarm algorithm, APSO algorithm improves the problem of easily falling into local optimal solution. The regularization parameters and kernel function tuning parameters of the LSSVM were optimized by APSO and then use this model to predict the solubility of CO2 in eight polymers within a wide range of temperatures and pressures. APSO‐LSSVM model has great prediction ability, with a good correlation between prediction data and experimental data, high prediction accuracy, short calculation time and strong stability. Compared with back propagation artificial neural network(BP ANN), back propagation‐particle swarm optimization algorithm artificial neural network(BP‐PSO ANN) and LSSVM, APSO‐LSSVM has better comprehensive performance. The average absolute relative deviation(AARD), root mean square error(RMSE), determination coefficient(R2) were respectively 0.2130, 0.0120, 0.9853. In addition, the model has good expansibility and can be applied to other fields such as chemistry and medicine.

Mn4+ non-equivalent doped fluoride phosphors with a short fluorescence decay time for backlighting.

The non-equivalent doping of Mn4+ in red-emitting fluoride phosphors effectively shortens the fluorescence lifetime. Herein, we successfully synthesized Rb2NaInF6:Mn4+ phosphors by an ion-exchange method. The compensation mechanism of Mn4+ local symmetry and charge balance in the phosphor were studied in detail by theoretical calculations based on density functional theory. The phosphor Rb2NaInF6:Mn4+ (5.59 mol%) exhibits intense red emission with a short fluorescence lifetime (1.45 ms). Meanwhile, it has excellent colour stability and thermal quenching stability at elevated temperatures. Using Rb2NaInF6:Mn4+, β-SiAlON:Eu2+ and a blue-emitting GaN chip as red, green, and blue components, the white light-emitting diode (w-LED) exhibits a wide colour gamut of 94.1% of the National Television System Committee (NTSC) standard value. So, this work provides valuable information to investigate novel red-emitting fluoride phosphors for LED backlighting.

Enhanced Transdermal Delivery of Pranoprofen Using a Thermo-Reversible Hydrogel Loaded with Lipid Nanocarriers for the Treatment of Local Inflammation.

A biocompatible topical thermo-reversible hydrogel containing Pranoprofen (PF)-loaded nanostructured lipid carriers (NLCs) was studied as an innovative strategy for the topical treatment of skin inflammatory diseases. The PF-NLCs-F127 hydrogel was characterized physiochemically and short-time stability tests were carried out over 60 days. In vitro release and ex vivo human skin permeation studies were carried out in Franz diffusion cells. In addition, a cytotoxicity assay was studied using the HaCat cell line and in vivo tolerance study was performed in humans by evaluating the biomechanical properties. The anti-inflammatory effect of the PF-NLCs-F127 was evaluated in adult male Sprague Daw-ley® rats using a model of inflammation induced by the topical application of xylol for 1 h. The developed PF-NLCs-F127 exhibited a heterogeneous structure with spherical PF-NLCs in the hydrogel. Furthermore, a thermo-reversible behaviour was determined with a gelling temperature of 32.5 °C, being close to human cutaneous temperature and thus favouring the retention of PF. Furthermore, in the ex vivo study, the amount of PF retained and detected in human skin was high and no systemic effects were observed. The hydrogel was found to be non-cytotoxic, showing cell viability of around 95%. The PF-NLCs-F127 is shown to be well tolerated and no signs of irritancy or alterations of the skin’s biophysical properties were detected. The topical application of PF-NLCs-F127 hydrogel was shown to be efficient in an inflammatory animal model, preventing the loss of stratum corneum and reducing the presence of leukocyte infiltration. The results from this study confirm that the developed hydrogel is a suitable drug delivery carrier for the transdermal delivery of PF, improving its dermal retention, opening the possibility of using it as a promising candidate and safer alternative to topical treatment for local skin inflammation and indicating that it could be useful in the clinical environment.

Lowering detection limits of copper(II)-selective carbon paste electrodes using an SNO- and an SNNS- Schiff base ligands

Interestingly, this work presents two newly designed copper(II)-selective carbon paste electrodes with distinctively low detection limits which is attained utilizing the Schiff base ligands 2-(2-hydroxyphenylimino)carboxythiophene (L1) and 1,2-di(2-carboxythiopheneimino] benzene (L2). The sensors exhibit a Nernstian slope of 29.10 and 29.28 mVdecade−1 for Cu(II) ion over a wide concentration range from 1.18 ​× ​10−7 – 1.00 ​× ​10−2 ​M and 7.91 ​× ​10−8 – 1.00 ​× ​10−2 ​M with the detection limits of 1.00 ​× ​10−7 ​M and 5.28 ​× ​10−8 ​M for L1 and L2 respectively. These sensors exhibit short response time (about 2 ​s) and good stability over the pH range 2.5–5.8. In addition, the present sensors show fairly good selectivity toward copper(II) ion in comparison to other common cations. Furthermore, they were satisfactorily used as indicator electrodes in complexometric titration with EDTA and for determination of copper(II) in water, tea and urine samples.

Chiroptical Switching and Quantitative Chirality Sensing with (Pseudo)halogenated Quinones.

(Pseudo)halogenated quinones react smoothly with chiral amines, amino alcohols, and amino acids toward push-pull conjugates with optical sensing and switching applications. The chiroptically active conjugates serve as redox switches between two reversibly interconverting states with remarkably different UV and CD signatures. Addition of sodium borohydride generates a hydroquinone derivative that is quantitatively re-oxidized to the original quinone upon exposure to air. This chiroptical quinone/hydroquinone redox switch system combines several attractive features such as simple set-up, use of inexpensive chemicals, short response time, and thermal and photochemical stability. A conceptually new sensing approach that is based on integrated chiroptical amplification and redox switching enables on-the-fly deconvolution of otherwise overlapping CD spectra and is used for quantitative er analysis of challenging samples containing constitutional isomers in varying enantiomeric compositions.

Chiroptical Switching and Quantitative Chirality Sensing with (Pseudo)halogenated Quinones

Abstract(Pseudo)halogenated quinones react smoothly with chiral amines, amino alcohols, and amino acids toward push–pull conjugates with optical sensing and switching applications. The chiroptically active conjugates serve as redox switches between two reversibly interconverting states with remarkably different UV and CD signatures. Addition of sodium borohydride generates a hydroquinone derivative that is quantitatively re‐oxidized to the original quinone upon exposure to air. This chiroptical quinone/hydroquinone redox switch system combines several attractive features such as simple set‐up, use of inexpensive chemicals, short response time, and thermal and photochemical stability. A conceptually new sensing approach that is based on integrated chiroptical amplification and redox switching enables on‐the‐fly deconvolution of otherwise overlapping CD spectra and is used for quantitative er analysis of challenging samples containing constitutional isomers in varying enantiomeric compositions.

A study of validity and reliability for Subjective Global Nutritional Assessment in outpatient children with cerebral palsy

ABSTRACT Objectives To investigate the reproducibility, stability, internal consistency and the ability to grade malnutrition of Subjective Global Nutritional Assessment (SGNA) in outpatient children with cerebral palsy. Methods This was a part of a larger, cross-sectional study (ChiCTR2000033869) at the outpatient of a tertiary hospital. The recruitment and data collection of children with Cerebral Palsy aged from 1 to 18 years were from August 2020 to March 2021. The concurrent validity, inter-rater reliability, test–retest reliability and internal consistency of SGNA were tested. To analyze data, specificity, sensitivity, Kendall coefficient, Cohen’s kappa coefficient, Spearman coefficient and Cronbach’s α coefficient were used. Results The agreement between SGNA and anthropometric data was moderate to strong (k = 0.540–0.821). The sensitivity (71.70% to 89.74%) and specificity (77.67% to 91.03%) of SGNA to identify participants with z-score ≤−2 were good. The sensitivity of SGNA to identify participants with weight for age z-score ≤−3 was poor (30.00%). The interrater reliability (k = 0.703) and test–retest reliability (k = 0.779) were good. The item of edema was with poor agreement to SGNA nutritional grades (r s = 0.072), and after deleting it from SGNA, the Cronbach’s α coefficient of SGNA increased from 0.736 to 0.871. Findings SGNA is good at identifying malnourished outpatient children with cerebral palsy, with excellent reproducibility and short-time stability. However, the ability to grade malnutrition is unsatisfactory. For further application in this group, a more appropriate item should be designed to replace the item of edema.

3D printed high-performance spider web-like flexible strain sensors with directional strain recognition based on conductive polymer composites

Inspired by the unique structure of spider web, we designed and prepared a spider web-like strain sensor based on multi-walled carbon nanotubes (MWCNT)/graphene nanoplatelets (GNP)/thermoplastic polyurethane (TPU) conductive polymer composites. Fused filament fabrication (FFF) 3D printing was used to meet the growing demand for flexible electronic devices and overcome limitations with the directional sensitivity of traditional strain sensors. The sensor response exhibited high linearity (R2 = 0.98 at 50% strain), a large strain response range (0–300%), high sensitivity (GF > 10000 at 300% strain), short response time (40 ms), low hysteresis, and good stability (1000 cycles). In addition, due to the special structural design, the sensor identified external forces in different directions. This further expands the application range of the sensor. This work provides valuable guidance for the customized fabrication of flexible strain sensors.

Integrating artificial intelligence and analytics in smart grids: a systematic literature review

PurposeThe purpose of this study is to explore the latest approaches in integrating artificial intelligence and analytics (AIA) in energy smart grid projects. Empirical results are synthesized to highlight their relevance from a technology and project management standpoint, identifying several lessons learned that can be used for planning highly integrated and automated smart grid projects.Design/methodology/approachA systematic literature review leads to selecting 108 research articles dealing with smart grids and AIA applications. Keywords are based on the following research questions: What is the growth trend in Smart Grid projects using intelligent systems and data analytics? What business value is offered when AI-based methods are applied? How do applications of intelligent systems combine with data analytics? What lessons can be learned for Smart Grid and AIA projects?FindingsThe 108 selected articles are classified according to the following four research issues in smart grids project management: AIA integrated applications; AI-focused technologies; analytics-focused technologies; architecture and design methods. A broad set of smart grid functionality is reviewed, seeking to find commonality among several applications, including as follows: dynamic energy management; automation of extract, transform and load for Supervisory Control And Data Acquisition (SCADA) systems data; multi-level representations of data; the relationship between the standard three-phase transforms and modern data analytics; real-time or short-time voltage stability assessment; smart city architecture; home energy management system; building energy consumption; automated fault and disturbance analysis; and power quality control.Originality/valueGiven the diversity of issues reviewed, a more capability-focused research agenda is needed to further synthesize empirical findings for AI-based smart grids. Research may converge toward more focus on business rules systems, that may best support smart grid design, proof development, governance and effectiveness. These AIA technologies must be further integrated with smart grid project management methodologies and enable a greater diversity of renewable and non-renewable production sources.

Bimodal Electrogenerated Chemiluminescence of the Luminol/Dicyclohexylamine (DCHA) System: A Novel and Highly Sensitive Detection of DCHA via ECL-Flow Injection Analysis.

Though luminol is one of the most prominent and extensively studied luminophores in ECL studies, only H2O2 has been widely used as a co-reactant. This limits the variety of applications because of the short-time radical stability and low quantum efficiency. In the present work, we identified dicyclohexylamine (DCHA) as a new and highly efficient anodic co-reactant in ECL for the luminol molecule. The electrochemical and ECL behavior of the luminol/DCHA system was studied on a simple bare GCE surface, which results in two anodic ECL peaks at the potential region of +0.38 and +0.94 V vs Ag/AgCl. The evidence of (DCHA•+) and O2•- generated in the system was detected via flat-cell electron spin resonance (ESR) spectroscopy experiments at ∼20 °C. Using the bimodal ECL system, the highly sensitive detection of luminol was achieved with the detection limit down to 1.5 pM. Further, a homebuilt electrochemiluminescent detector coupled with a flow injection analysis (ECL-FIA) system was adopted to detect the DCHA contaminant in harvested honey, which achieved higher detection and sensitivity under the optimized experimental conditions. DCHA was detected in the range of 10 nM to 100 μM with the detection limit of 2 nM (S/N = 3). The present findings of new luminol/DCHA ECL signals produced a strong ECL emission, which leads to a greater potential to meet the fast-developing analytical application of a luminol-based ECL system.

Subsurface-Regulated PtGa Nanoparticles Confined in Silicalite-1 for Propane Dehydrogenation.

Propane dehydrogenation (PDH) is one of the most promising techniques to produce propylene. Industrial Pt-based catalysts often suffer from short-time stability under high temperature due to serious sintering and coke deposition via undesired side reactions. Detailed reaction mechanism on the surface of Pt-based nanoparticle has been well studied, while the subsurface effect remains mostly unstudied. Herein, supported PtGa nanoparticles with different surface and subsurface composition was evidenced by extended X-ray absorption fine structure (EAXFS) spectra and energy dispersive X-ray spectroscopy (EDS). Theoretical simulation demonstrated subsurface regulation would increase the electron density of surface Pt and thus weaken propylene adsorption. Propylene selectivity on the PtGa-subsurface nanoparticles was up to 98% at 600 °C while that on the Pt-subsurface nanoparticles was only 95%. Furthermore, rational designed PtGa alloy nanoparticles were encapsulated in MFI zeolite to inhibit sintering and coke deposition for enhanced catalytic stability.

Preparation of Nanoemulsions of Mentha piperita Essential Oil and Investigation of Their Cytotoxic Effect on Human Breast Cancer Lines

Breast cancer is the most common cancer among women worldwide. Common disadvantages of chemotherapy, such as drug resistance, nausea, and vomiting, have encouraged researchers to use herbal remedies. In this study, constituents of Mentha piperita essential oil were identified using GC-MS analysis with five major ingredients of menthol (31.0%), menthone (22.1%), camphane (7.0%), menthofuran (6.0%), and iso-menthone (5.8%). The essential oil anticancer activity was evaluated at various incubation periods (24, 48, and 72 h) against three human breast cancer cell lines. After that, nanoemulsions of M. piperita were prepared, and long- and short-time stability tests were also performed. The anticancer effect of the best nanoemulsion with a mean droplet size of 136 ± 2 nm (PDI 0.3 and SPAN 0.8) was significantly better than that of non-formulated essential oil. Interestingly, the obtained effect from nanoemulsion with an exposure time of 24 h was significantly better than essential oil even within 72-h exposure time. M. piperita possesses an antiemetic effect, and by preparation of its nanoemulsion dosage form, its anticancer effect was also improved. Therefore, this green nanoemulsion could be used as an anticancer agent for further investigation.

Monodispersed hollow α-Fe2O3 ellipsoids via [C12mim][PF6]-assistant synthesis and their excellent n-butanol gas-sensing properties

Monodisperse α-Fe2O3 hollow ellipsoids have been assistantly fabricated via small amount of [C12mim][PF6] (IL) addition from a simple one-pot method based on hydrothermal treatment of FeCl3·6H2O, followed by calcination at various temperatures. The phase and microstructure of the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption techniques. Further studies reveal that both calcination temperature and the amounts of IL have a strong effect on the structures. The well known Ostwald ripening process is responsible for the transformation from solid ellipsoids to hollow ellipsoids. The gas sensors based on the as-synthesized hollow α-Fe2O3 ellipsoids calcined at 300 °C exhibited not only high response, short recovery time and good stability to 100 ppm n-butanol at 217 °C, but also low detection limit (0.1 ppm) compared with those under higher calcination temperature and the products obtained without ILs-addition. IL-loading α-Fe2O3 hollow ellipsoids could be a promising candidate for highly sensitive n-butanol gas sensors.