Sampling Rate Research Articles

Glutathione‑iron hybrid nanozyme-based colorimetric sensor for specific and stable detection of thiram pesticide on fruit juices

Given the potential dangers of thiram to food safety, constructing a facile sensor is significantly critical. Herein, we presented a colorimetric sensor based on glutathione‑iron hybrid (GSH-Fe) nanozyme for specific and stable detection of thiram. The GSH-Fe nanozyme exhibits good peroxidase-mimicking activity with comparable Michaelis constant (Km = 0.551 mM) to the natural enzyme. Thiram pesticides can specifically limit the catalytic activity of GSH-Fe nanozyme via surface passivation, causing the change of colorimetric signal. It is worth mentioning that the platform was used to prepare a portable hydrogel kit for rapid qualitative monitoring of thiram. Coupling with an image-processing algorithm, the colorimetric image of the hydrogel reactor is converted into the data information for accurate quantification of thiram with a detection limit of 0.3 μg mL−1. The sensing system has good selectivity and high stability, with recovery rates in fruit juice samples ranging from 92.4% to 106.9%.

Experimental Investigation of the Structural Performance of Concrete Containing Cellulose Fibers and the Anti-corrosive Effect of Green Corrosion Inhibitors

This research was aimed to find the structural behaviour of Calotropis procera fibres added concrete and the effect of Azadirachta indica leaf slurry blended to concrete and exposed to seawater. Conventional and fibre reinforced concrete samples fabricated keeping the curing time as 7, 14 and 28 dayswere subjected to compression, split tensile, rebound hammer and ultrasonic pulse velocity test. Increase in curing time increased the structural properties and Calotropis procerafibres added samples produced respectively 19.5%, 15%, 10.3 and 14.5% improvement in the compression, tensile, rebound hammer and ultrasonic pulse velocity values. These fibres reduced the brittleness of the specimen and avoided unprecedented failures. Accelerated corrosion and gravimetric mass loss test conducted to estimate the anti-corrosive property of Azadirachta indica leaf slurry showed decrease in corrosion rate. The corrosion rate of concrete samples without and with inhibitors was 0.0654 ± 0.008 and 0.056 ± 0.011 mm/year respectively evincing the anti-corrosive effects of Azadirachta indica leaves. Thus green materials are compatible with concrete and can be used in making sustainable concrete structures.

Calibration of buried NaI(Tl) scintillator detectors for natural radionuclide measurement based on Monte Carlo modelling

Measurements of naturally occurring concentrations of 40K, and of the decay series of 238U and 232Th, are of interest in the earth sciences in general, and in particular, scintillator-based gamma spectrometers can be used for the low cost determination of burial dose rates in natural geological samples. We are currently developing a robust, portable, wireless detector specifically intended for field measurement of natural radionuclide concentrations and hence, the calculation of dose rates. One of the challenges in developing and applying such an instrument is reliable calibration. Most calibrations of field instruments depend on access to non-finite matrices of known K, U, Th activity concentrations, in either a 4π or 2π geometry; these are only available at a few facilities around the world. Here we investigate an alternative approach, based on the measurement of small samples containing well-known activity concentrations of only K or U or Th, and Monte-Carlo radiation transport modelling to convert the observed spectra into those expected from specific activity concentrations in a non-finite 4π geometry. We first validate our modelling procedure by simulating these observed spectra. The non-finite matrix calibration spectra are then predicted, and least-squares fitted to the spectrum observed at the centre of a 1 m3 of granite chips; the resulting predicted U, Th and K activity concentrations are compared with independently known values.

Adaptive Whitening and Feature Gradient Smoothing-Based Anti-Sample Attack Method for Modulated Signals in Frequency-Hopping Communication

Adaptive Whitening and Feature Gradient Smoothing-Based Anti-Sample Attack Method for Modulated Signals in Frequency-Hopping Communication

Effect of milk protein-galactomannans interaction on meltdown behavior in the aerated frozen model system

The microstructure of ice cream and frozen desserts is known to influence their meltdown behavior. In this study, we hypothesized that the interaction of milk protein and galactomannans, specifically the phase separation often observed between hydrocolloids and protein, along with the interaction of hydrocolloids in the serum phase, affected meltdown behavior in non-fat aerated frozen foam. Ice creams were made with protein contents from 4 to 8%, with the addition of guar gum or locust bean gum. The effect of κ-carrageenan in protein and galactomannans was also studied. Melting characteristics were compared to the rheological and structural characteristics of the ice cream as well as to the phase separation in the mix and drip-through solution. The freezing-melting process inhibited microscopic and macroscopic phase separation in most locust bean gum samples, primarily due to the cryo-gel maintaining structural integrity and altering hydrocolloid-proteins interactions. The cryo-gel structure also led to slow melting rates and stable melted foams in the 4% milk protein system even in the absence of milk fat globules and clusters. Increasing milk protein from 4% to 8% in locust bean gum samples resulted in faster melting and a transition to complete dripping, indicating the disruption of the cryo-gel structure by increased proteins. In contrast, all guar gum samples fully dripped through the mesh with a fast melting rate. A negative trend was found between phase separation and melting rate in the guar gum samples containing κ-carrageenan, indicating that the diminishing interaction between the two immiscible phases accelerated liquid drainage.

Development of a sequential injection analysis method for the automatic speciation of inorganic selenium in water samples

Selenium is an important micronutrient for the human body, but biological concentrations on either side of its narrow nutritional window can lead to serious health impacts. Furthermore, Se(IV) has been reported to be more toxic than Se(VI). Therefore, prudent control and monitoring of Se intake should involve speciation of this element. Herein, the development and validation of an automatic sequential injection analysis (SIA) system and method for the speciation of Se(IV) and Se(VI) in water samples is reported for the first time. This method is based on the starch-iodide reaction using Se(IV) as the oxidant, which subsequently forms a blue compound with starch. Total selenium is determined after an online pre-reduction of Se(VI) to Se(IV) with HCl at 75 °C. The concentration of Se(VI) is then calculated as the difference between the total Se and Se(IV) concentrations. The calibration curves for Se(IV) and total Se are characterised by linear ranges of 0 – 1.5 mg L-1 and 0 – 2.5 mg L-1, limits of detection (LODs) of 0.02 mg L-1 and 0.07 mg L-1, and averaged relative standard deviations (RSDs) (n = 3) of 1.33 % and 2.95 % respectively, with a sampling rate of 10 h−1. The newly developed SIA method has been successfully applied to drinking water samples spiked with both Se species and good recoveries in the range 94 – 109 % have been achieved.

Development of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Coupled with Multivariate Classification Chemometric Model for Routine Screening of Paracetamol, Ibuprofen, and Aspirin Adulteration in Herbal Products

Objective: The objective of this study is to develop and validate a routine screening test for the determination of three common antipyretic-analgesic synthetic drugs (paracetamol, ibuprofen, and aspirin) adulteration in herbal products using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) coupled with chemometric method. Method: ATR-FTIR spectra of sixteen testing sets of herbal product samples for pain and fever indications were used for multivariate chemometrics model construction. Linear Discriminant Analysis (LDA) was selected as a method for model construction with IBM SPSS for statistical analysis. Model development employed feature selection, such as the stepwise method for variable selection. The model with a high %correct classification and cross-validation was selected and was then validated with an independent testing data set with an auto-prediction test, confusion matrix, and Receiver Operating Characteristic (ROC) curve. To validate the developed test for routine use, the result from ATR-FTIR method was compared with the standard HPLC and TLC analyses used for adulteration screening. objective: Creating validated screening tools for herbal products adulterated with three common antipyretic-analgesic synthetic drugs (Paracetamol, Ibuprofen, and Aspirin) using ATR-FTIR couple with chemometric method Results: The selected model's overall %correct classification result was 97.7%, with a cross-validation of 93.8% rate in training set samples. External validation with an independent testing dataset gave an overall correct classification of 93.8%, with an area under the curve of ROC at 0.979. Comparative testing revealed that model performance was comparable with the HPLC and TLC methods, which routinely detect the presence of paracetamol, aspirin, and ibuprofen. The results of testing set samples classification were consistent with training set samples. Conclusion: Against the standard chromatographic methods, the multivariate chemometric model based on ATR-FTIR demonstrates comparable detection capability to determine adulteration of paracetamol, ibuprofen, and aspirin in herbal products.

Li4SiO4-Based Heat Carrier Derived from Different Silica Sources for Thermochemical Energy Storage

Thermochemical energy storage (TCES) is one of the key technologies facilitating the integration of renewable energy sources and mitigating the climate crisis. Recently, Li4SiO4 has been reported to be a promising heat carrier material for TCES applications, owing to its moderate operation temperature and stability. During the synthetic processes, the properties of the Si source used directly influence the performance of derived Li4SiO4 materials; however, the internal relations and effects are not yet clear. Hence, in this work, six kinds of SiO2 sources with different phases, morphology, particle size, and surface area were selected to synthesize a Li4SiO4-based TCES heat carrier. The physicochemical properties of the SiO2 and the corresponding derived Li4SiO4 were characterized, and the comprehensive performance (e.g., heat storage/releasing capacity, rate, and cyclic stability) of the Li4SiO4 samples was systematically tested. It was found that the silica microspheres (SPs), which possess an amorphous phase, uniform micro-scale structure, and small particle size, could generate Li4SiO4 TCES materials with a highest initial capacity of 777.7 kJ/kg at 720 °C/900 °C under pure CO2. As a result, the SP-L showed an excellent cumulative heat storage amount of 5.84 MJ/kg within 10 heat-releasing/storage cycles, which was nearly 1.5 times greater than the value of Li4SiO4 derived from commonly used silicon dioxide. Furthermore, the effects of the utilized Si source on the performance of as-prepared Li4SiO4 and corresponding mechanisms were discussed, which offers guidance for the future selection of Si sources to produce high-performance Li4SiO4-based TCES heat carriers.

Metagenomic next-generation sequencing-based retrospective investigation of the drug resistance sites of Mycoplasma pneumoniae in children

Objective: To analyze the drug-resistant gene loci of Mycoplasma pneumoniae (MP) using metagenomic next-generation sequencing (mNGS). Methods: From November 2022 to October 2023, 697 clinical samples (including sputum, alveolar lavage fluid and blood) of 686 children with Mycoplasma pneumoniae positive detected by mNGS were retrospectively analyzed. Samples were divided into intensive care unit (ICU) group and non-ICU group, Chi-square test was used to compare groups, and Mann-Kendall trend test was used to analyze the change trend of the detection rate of drug resistance gene loci over time. Results: Of the 697 samples, 164 were from the ICU group and 533 were from the non-ICU group. The detection rate of Mycoplasma pneumoniae resistance gene was 44.3% (309/697), and all detected drug-resistant gene loci of MP were A2063G. The detection rate of Mycoplasma pneumoniae in ICU group was 50.0% (82/164), and the detection rates of Mycoplasma pneumoniae resistance gene loci in sputum, alveolus lavage fluid and blood samples were 75.0% (18/24) and 48.4% (62/128), respectively. The detection rate in sputum was higher than alveolus lavage fluid samples (χ2=5.72,P=0.017). The detection rate of Mycoplasma pneumoniae in non-ICU group was 42.6% (227/533), the detection rate of Mycoplasma pneumoniae resistance gene loci in sputum and alveolar lavage fluid was 40.0% (16/40), 44.3% (201/454), and no detection rate in blood samples (0/12). There was no significant difference in the detection rate of alveolar lavage fluid and sputum (χ2=0.27, P=0.602). From November 2022 to October 2023, the detection rate of submitted samples showed an increasing trend month by month (overall: Z=3.99, ICU inspection group: Z=2.93, non-ICU group: Z=3.01, all P<0.01). Among the bacteria commonly detected with Mycoplasma pneumoniae, Streptococcus pneumoniae accounted for the highest proportion, the detection rate was 15.5% (108/697), and Epstein-Barr virus accounted for the highest proportion of 17.6% (123/697). Conclusions: From November 2022 to October 2023, the detection rate of Mycoplasma pneumoniae drug resistance gene loci showed an increasing trend. The detection rate of drug resistance gene loci in sputum samples of ICU group was higher than alveolus lavage fluid. No new drug resistance site were detected.

Affirming Vocal Resonance in Carnatic Singers Using Auditory Perception and Formant Frequency Measures

ABSTRACT This study investigated the impact of Resonant Voice Therapy (RVT) on the perception of vocal resonance, vocal tract formant frequencies, and the Singer’s formant in trained Carnatic classical singers. Twenty-nine vocally healthy Carnatic classical singers (18 females, 11 males) underwent 21 consecutive days of RVT. The study recorded their/a/vowel phonation and singing samples before and after the therapy. Trained judges assessed vocal resonance, and Praat Software was used to analyze formant frequencies and energy distribution in the 2 kHz to 3.5 kHz range. Non-parametric tests compared pre- and post-training data. After RVT, the perception of vocal resonance ratings for phonation samples was significantly improved. Significant differences were observed for all formants in phonation and the first, third, and fourth formants in singing. Singer’s formant manifestation increased post-training, particularly in male singers, with higher peak amplitudes. RVT-induced vocal tract changes, primarily in the pharyngeal cavity, lead to altered formant frequencies post-training. These effects may take time to manifest in overt singing. Furthermore, this study provides evidence for the presence of Singer’s formant in Carnatic singers, confirming the unique vocal characteristics of this music tradition.

An Energy-Efficient 12-Bit VCO-Based Incremental Zoom ADC with Fast Phase-Alignment Scheme for Multi-Channel Biomedical Applications

This paper presents a low-power, energy-efficient, 12-bit incremental zoom analog-to-digital converter (ADC) for multi-channel bio-signal acquisitions. The ADC consists of a 7-stage ring voltage-controlled oscillator (VCO)-based incremental ΔΣ modulator (I-ΔΣM) and an 8-bit successive approximation register (SAR) ADC. The proposed VCO-based I-ΔΣM can provide fast phase-alignment of the ring-VCO to reduce the interval settling time; thereby, the I-ΔΣM can accommodate time-division-multiplexed input signals without phase leakage between consecutive measurements. The SAR ADC also adopts splitting unit capacitors that can support VCM-free tri-level switching and prevent invalid states from the phase frequency detector with minimal logic gates and switches. The proposed ADC has been fabricated in a standard 180 nm standard 1P6M CMOS process, exhibiting a 67-dB peak signal-to-noise ratio, a 74-dB dynamic range, and a Walden figure of merit of 19.12 fJ/c-s, while consuming a power of 3.51 μW with a sampling rate of 100 kS/s.

A First-Order Noise-Shaping SAR ADC with PVT-Insensitive Closed-Loop Dynamic Amplifier and Two CDACs

This paper presents a first-order noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) with a process, (supply) voltage, and temperature (PVT)-insensitive closed-loop integrator and data-weighted averaging (DWA). The use of a cascode floating inverter amplifier (FIA)-type dynamic amplifier with high gain enables an aggressive noise transfer function while minimizing the power consumption associated with the use of an active filter. In the proposed ADC, the residue is generated by a capacitive digital-to-analog converter (CDAC) employing DWA, which is made possible by employing a second CDAC, which operates after the SAR operation is completed. The proposed ADC is designed with a 28 nm CMOS process with 1 V power supply. The simulation results show that the ADC achieves the SNDR of 71.2 dB and power consumption of 228 μW when operated with a sampling rate of 80 MS/s and oversampling ratio (OSR) of 10. The Schreier figure-of-merit (FoM) is 173.6 dB, and Walden FoM is 9.6 fJ/conversion-step.

A self-adaptive correlated multiple sampling technique based on single-slope ADC for low-noise CMOS image sensors

This paper presents a self-adaptive correlated multiple sampling (SACMS) technique for low-noise CMOS image sensors. Compared to the traditional correlated multiple sampling (TCMS), SACMS technique adds a pre-determination stage to determine the brightness of the pixel, reducing the 4 large-range ramps to 3 small-range ramps and 1 large-range ramp when quantizing the signal. For dark pixels, the signal is quantized using small-range ramps with short sampling interval to reduce low-frequency noise. For bright pixels, the CMS operation is turned off and the signal is quantized only once in the large-range ramp to improve the frame rate. Simulation results demonstrate that, for dark pixels, SACMS achieves a minimum readout noise of 84.22μVrms at eight times analog gain, compared to 108.76μVrms with TCMS, representing an approximately 21.7 % improvement in noise suppression. Additionally, the sampling rate of the SSADC employing SACMS technique is 36.36 kHz, while the sampling rate of the SSADC using TCMS technique is 21 kHz.

Simulation method for multichromatic light spots in mosaic aperture telescopes with large image planes during deployment

In optical systems, diffraction limits significantly impact spot simulations. This study addresses this problem by applying the Fourier transform to calculate spots in imaging systems. Typically, a 1 mm image plane suffices; however, mosaic aperture telescopes with notable wavefront discontinuities require an approximately 10 mm simulation image plane. This necessitates high sampling rates for pupils, posing challenges for conventional methods. Our model overcomes this challenge by leveraging an interpolation technique to align multiwavelength spots on a uniform image plane grid, thus effectively analyzing spot translation and spreading in imaging systems with diffraction limits.

A Novel High-Impedance Fault Detection Technique in Smart Active Distribution Systems

Identification of high impedance fault (HIF) is important in smart active distribution systems (SADSs). The existing protection methods fail to detect HIF, as HIFs have peculiar fault current characteristics. However, if HIFs are left undetected, they result in severe fire hazards and arcing. The paper proposes a novel fault detection indicator that utilizes the differential energy associated with the positive sequence current components during faults. IEEE-13 bus and IEEE-34 bus system is used for simulation in Real Time Digital Simulator (RTDS). The results show that proposed technique accurately identify HIFs and perfectly discriminates the transients due to HIFs, non-linear loads and voltage and reactive power compensation devices. Furthermore, it differentiates HIFs from other switching transients like capacitor or load switching events. Other factors, like transformer inrush currents, effect of noise and sampling rate are also considered to ensure the accuracy and reliability of the proposed method. Moreover, the practical feasibility of the proposed method is also experimentally validated.

An energy-efficient reconfigurable 18/12-bit 1 MS/s pipelined-SAR ADC

This paper presents a low-power 18/12-bit 1 MS/s reconfigurable pipelined-successive approximation register analog-to-digital converter (pipelined-SAR ADC). The proposed pipelined-SAR ADC employs a two-stage SAR structure coupled through a residual amplifier, with the forestage performing 12-bit coarse quantization and the poststage handling 7-bit fine quantization, one bit of redundancy is contained in the rear stage. The input signal is sampled by the first stage, SAR ADC, using the upper plate of a capacitor array and is quantized by charge redistribution. This eliminates the need of additional DACs and subtractors, allowing direct acquisition of the residuals. In addition, the residuals can be amplified by reusing the capacitor array as a switching capacitor. To minimize static power consumption, dynamic logic is adopted in each module of the pipelined-SAR ADC. The calibration of comparator offset and capacitor mismatch is carried out using analog front-end calibration techniques. Implemented in a 180 nm CMOS process, the simulation results show an extra-low power consumption of 1.76 mW with 3.3 V supply voltage and 1 MS/s sampling rate, indicating an exceptional Schreier figure of merit (FOMs) at 181.64 dB. By shutting down the modules of the second-stage SAR ADC, the 18-bit ADC can be dynamically configured as a 12-bit ADC with a sampling rate of up to 5 MS/s.

A low crosstalk 768-channel of 14-bit analog to digital converters for high resolution array of detectors

This paper presents the design and measurement results of a 768-channel of a 14-bit analog to digital converters. Each sampling channel is equivalent to a pitch of only 8.5 μm with a possible sampling rate from 40 KS/s up to 100 KS/s. Test results show crosstalk of just +/-1 LSB. The circuit architecture and layout structure make it scalable to an exceptionally large format of detectors beyond 1000 channels. The circuit is designed to be used as a side element for multi-channel readout systems or as an IP for transfer to very dense integrated circuits.

Structural characterization, photothermal effect and biological properties of La/Ga ion co-doped hydroxyapatite coated with polydopamine

Pure hydroxyapatite (HA) and La3+/Ga3+ co-doped HA were made using a straightforward hydrothermal method and later coated with the photothermal agent polydopamine (PDA). In addition to testing the HA of uncoated PDA in an alkaline environment (pH = 13), the influence of doping quantity and pH on the warming of solid/liquid samples was methodically examined and compared. The results show that among the same series of samples, 1La1GaHA13@PDA (pH = 13, doping amount of 1) has the optimal photothermal heating capacity. Enhancing the photothermal efficiency of the specimens is better achieved through co-doping, and the light absorption ability of the dopamine-modified samples is much stronger than that of the unmodified samples. It is estimated that the photothermal conversion efficiency of 1La1GaHA13@PDA is 67.68 %. E. Coli and S. aureus are used to test the photothermal sterilization performance of various samples. Light irradiation dramatically increases the antimicrobial rate of PDA-coated samples, with 1La1GaHA13@PDA being able to achieve more than 99 % against two types of bacteria. The cellular MTT assay showed that 1La1GaHA13@PDA was able to promote the proliferation of MC3T3-E1 osteoblasts at a low concentration of 50 ug/mL, with good biocompatibility.

Variable effects of captivity on microbiomes in populations of IUCN-endangered Blanding's turtles (Emydoidea blandingii).

Microbiome composition is increasingly considered in species reintroduction efforts and may influence survival and reproductive success. Many turtle species are threatened by anthropogenic pressures and are frequently raised in captivity for reintroduction efforts, yet little is known about turtle microbiome composition in either wild or captive settings. Here, we investigated trends in microbiome composition of captive and wild IUCN-endangered Blanding's turtles (Emydoidea blandingii). We amplified and sequenced the V4 region of the 16S rDNA locus from plastron, cloaca, and water samples of wild E. blandingii adults and two populations of captive E. blandingii juveniles being raised for headstarting. Plastron, cloaca, and water-associated microbiomes differed strongly from each other and were highly variable among captive sites and between captive and wild sites. Across plastron, cloaca, and water-associated microbial communities, microbial diversity changed over time, but not in a predictable direction between captive sites. Plastron beta diversity correlated with growth rate in captive samples, indicating that external microbiomes may correlate with individual fitness. Our results indicate that external and internal microbiomes vary between captive and wild turtles and may reflect differences in fitness of captive-raised individuals.

Effect of nitrate-carbonate molten salt flow rate for the 347H corrosion behavior

Molten salts have been widely adopted for solar thermal power stations because of their superior thermophysical properties. However, the corrosive effect on the metal material with molten salt is an important factor for the long-term operation of CSP systems. For the study of the corrosive influence on metallic materials of molten salts in dynamic conditions, the corrosion performance of the 347H sample in molten salts at different flow rates was analyzed by using nitrate-carbonate molten salt as the base salt. The findings revealed a higher corrosion rate of the 347H samples under dynamic conditions, compared to static conditions. Moreover, as the flow velocity for the molten salt increases, 347H sample corrosion rates increase. The morphological analysis of the 347H sample revealed that, under molten salt static conditions, a dense corrosion layer was mainly formed in the 347H sample, while, under molten salt dynamic conditions, a grooved structure was observed in the 347H sample. The main corrosion products of 347H samples in different flow rates are composed of Fe2O3, Fe3O4, NiFe2O4 and NaFeO2. Therefore, for changing the molten salt flow rate, the sample’s corrosion morphology changes but does not affect the sample’s corrosion product type.