Advances in Optical Based Turbidity Sensing Using LED Photometry (PEDD)

Turbidity is one of the primary metrics to determine water quality in terms of health and environmental concerns, however analysis typically takes place in centralized facilities, with samples periodically collected and transported there. Large scale autonomous deployments (WSNs) are impeded by both initial and per measurement costs. In this study we employ a Paired Emitter-Detector Diode (PEDD) technique to quantitatively measure turbidity using analytical grade calibration standards. Our PEDD approach compares favorably against more conventional photodiode-LED arrangements in terms of spectral sensitivity, cost, power use, sensitivity, limit of detection, and physical arrangement as per the ISO 7027 turbidity sensing standard. The findings show that the PEDD technique was superior in all aforementioned aspects. It is therefore more ideal for low-cost, low-power, IoT deployed sensors. The significance of these findings can lead to environmental deployments that greatly lower the device and per-measurement costs.

Systematically Measuring Ultra-diffuse Galaxies (SMUDGes). II. Expanded Survey Description and the Stripe 82 Catalog

We present 226 large ultra-diffuse galaxy (UDG) candidates (r e > 5.″3, μ 0,g > 24 mag arcsec−2) in the SDSS Stripe 82 region recovered using our improved procedure developed in anticipation of processing the entire Legacy Surveys footprint. The advancements include less constrained structural parameter fitting, expanded wavelet filtering criteria, consideration of Galactic dust, estimates of parameter uncertainties and completeness based on simulated sources, and refinements of our automated candidate classification. We have a sensitivity ∼1 mag fainter in μ 0,g than the largest published catalog of this region. Using our completeness-corrected sample, we find that (1) there is no significant decline in the number of UDG candidates as a function of μ 0,g to the limit of our survey (∼26.5 mag arcsec−2); (2) bluer candidates have smaller Sérsic n; (3) most blue (g–r < 0.45 mag) candidates have μ 0,g ≲ 25 mag arcsec−2 and will fade to populate the UDG red sequence we observe to ∼26.5 mag arcsec−2; (4) any red UDGs that exist significantly below our μ 0,g sensitivity limit are not descendent from blue UDGs in our sample; and (5) candidates with lower μ 0,g tend to smaller n. We anticipate that the final SMUDGes sample will contain ∼30 × as many candidates.

The Development of Digital Image Colorimetric Quantitative Analysis of Multi-Explosives Using Polymer Gel Sensors

Polymer gel sensors on 96-well plates were successfully used to detect four different multi-explosives, including 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), nitrite, and perchlorate. The products of reactions between the explosives and the polymer gel sensors were digitally captured, and the images were analyzed by a developed Red–Green–Blue (RGB) analyzer program on a notebook computer. RGB color analysis provided the basic color data of the reaction products for the quantification of the explosives. The results provided good linear range, sensitivity, limit of detection, limit of quantitation, specificity, interference tolerance, and recovery. The method demonstrated great potential to detect explosives by colorimetric analysis of digital images of samples on 96-well plates. It is possible to apply the proposed method for quantitative on-site field screening of multi-explosives.

Noise factor and reception bandwidth in optoacoustical GW antenna

An expression has extracted from the OGRAN project theory, which provides connection between numerical values of noise factor F and achieved displacement resolution and antenna’s threshold signal in metric variations. Noise factor and “reception bandwidth” connects across displacement resolution. There is defined analytical expression and numerical value for design displacement resolution (sensitivity) on the base intention F = 1. It has appeared that the extracted analytical expression for readout resolution does not correspond to applied Pound-Drever-Hall technique and AURIGA circuitry. This requires an improvement in theoretical design. The achieved resolution value 2·10−15 cm/Hz1/2 is matched to the value for metric sensitivity in pulse hmin ≃ 10−18, which is 15 dB higher than the thermal sensitivity limit.

Search for and Identification of Young Compact Galactic Supernova Remnants Using THOR

Young Supernova remnants (SNRs) with smaller angular sizes are likely missing from existing radio SNR catalogues, caused by observational constraints and selection effects. In order to find new compact radio SNR candidates, we searched the high angular resolution (25″) THOR radio survey of the first quadrant of the galaxy. We selected sources with non-thermal radio spectra. HI absorption spectra and channel maps were used to identify which sources are galactic and to estimate their distances. Two new compact SNRs were found: G31.299-0.493 and G18.760-0.072, of which the latter was a previously suggested SNR candidate. The distances to these SNRs are 5.0±0.3 kpc and 4.7±0.2 kpc, respectively. Based on the SN rate in the galaxy or on the statistics of known SNRs, we estimate that there are 15–20 not-yet detected compact SNRs in the galaxy and that the THOR survey area should contain three or four. Our detection of two SNRs (half the expected number) is consistent with the THOR sensitivity limit compared with the distribution of integrated flux densities of SNRs.

Ti3C2 MXene-Based Nanobiosensors for Detection of Cancer Biomarkers

This chapter provides information about basic properties of MXenes (2D nanomaterials) that are attractive for a design of various types of nanobiosensors. The second part of the chapter discusses MXene synthesis and various protocols for modification of MXene making it a suitable matrix for immobilization of bioreceptors such as antibodies, DNA aptamers or DNA molecules. The final part of the chapter summarizes examples of MXene-based nanobiosensors developed using optical, electrochemical and nanomechanical transducing schemes. Operational characteristics of such devices such as sensitivity, limit of detection, assay time, assay reproducibility and potential for multiplexing are provided. In particular MXene-based nanobiosensors for detection of a number of cancer biomarkers are shown here.

Sensitivity limit investigation of a Sagnac gyroscope through linear regression analysis

The sensitivity to angular rotation of the top class Sagnac gyroscope GINGERINO is carefully investigated with standard statistical means, using 103 days of continuous operation and the available geodesic measurements of the Earth angular rotation rate. All features of the Earth rotation rate are correctly reproduced. The unprecedented sensitivity of fractions of frad/s is attained for long term runs. This excellent sensitivity and stability put Sagnac gyroscopes at the forefront for fundamental physics, in particular for tests of general relativity and Lorentz violation, where the sensitivity plays the key role to provide reliable data for deeper theoretical investigations.

Erratum to: Sensitivity limit investigation of a Sagnac gyroscope through linear regression analysis

A Correction to this paper has been published: https://doi.org/10.1140/epjc/s10052-021-09199-1

Spectrophotometic Determination of Caffeine and Vitamin B6 in Selected Beverages, Energy/Soft Drinks and Herbal Products

In this study, a simple, sensitive and reproducible spectrophotometric technique has been developed and validated for the determination of caffeine and vitamin B6 in beverages, energy/soft drinks and herbal products. The determination of caffeine and vitamin B6 in the respective samples were carried out at maximum (λmax) absorbance of 272 and 290 nm respectively. The method was validated in terms of linearity, sensitivity (limit of Detection (LOD) and limit of Quantification (LOQ), accuracy (% Recovery), precision (relative standard deviation). The method was linear from (4-20 µg/ml and 50 - 250 µg/ml with r 2 of 0.9991 and 0.9996 for vitamin B6 and caffeine respectively. The accuracy of the method ranged from 99.48 - 101.42% for caffeine and 99.94% - 102.35% for vitamin B6. The detection limit and quantification limit were 0.192 µg/ml and 0.640 µg/ml for vitamin B6 while 0.0155 µg/ml and 0.0518 µg/ml was obtained for caffeine. The method for the two analytes was found to be precise as the percentage relative standard deviation was below 5%. Therefore, the method proposed in this study is rapid, suitable and can be used as a quality control index for caffeine and vitamin B6 in beverages, energy/soft drinks and herbal products in industries. Keywords: Caffeine, Vitamin B6, Beverages, Energy/Soft drinks, Herbal products, Spectrophotometry

An Optimized Extraction Procedure for Determining Acaricide Residues in Foundation Sheets of Beeswax by Using Gas Chromatography-Mass Spectrometry

Pesticides can be found in beehives for several reasons, including contamination from surrounding cultivars; yet one of the most pertinent is related to the fact that beekeepers employ acaricides to control various types of mites, which may accumulate in beeswax due to their lipophilic nature. In the present study, foundation sheets of different origins, collected over a period of three years, were analyzed to detect the residues of seven acaricides (atrazine, chlorpyrifos, chlorfenvinphos, alpha-endosulfan, bromopropylate, coumaphos, tau-fluvalinate) by gas chromatography with mass spectrometric detection. An efficient sample treatment (recoveries between 90% and 108%) is proposed, involving solvent extraction with 1% acetic acid in acetonitrile mixture followed by dispersive solid-phase extraction (enhanced matrix removal lipid) and a polishing step. An evaluation was made of the analytical performance of the proposed method. It was shown to be selective, linear from a limit of quantification to 5000 µg/kg, precise (relative standard deviation values were below 6%), and with a goo sensitivity (limit of quantification ranging from 5 to 10 µg/kg). Finally, results showed that a large majority of the sheets analyzed (>90%) contained residues of at least one of these compounds. Coumaphos and tau-fluvalinate residues were the most common, with chlorpyrifos and chlorfenvinphos detected to a lesser extent.