Minimum Detectable Level Research Articles

Evaluation of Non-Invasive Sampling Techniques for the Molecular Surveillance of Equid Herpesviruses in Yearling Horses.

Equid alphaherpesvirus 1 (EHV-1) is a highly contagious respiratory tract pathogen of horses, and infection may be followed by myeloencephalopathy or abortion. Surveillance and early detection have focused on PCR assays using less tolerated nasal swabs. Here, we assess non-invasive non-contact sampling techniques as surveillance tools in naturally equid gammaherpesvirus 2-shedding horses as surrogates for EHV-1. Horses were individually housed for 10 h periods on 2 consecutive days. Sampling included nasal swabs, nostril wipes, environmental swabs, droplet-catching devices, and air sampling. The latter was completed via two strategies: a combined air sample collected while going from horse to horse and a collective air sample collected at a stationary central point for 6 h. Samples were screened through quantitative PCR and digital PCR. Nine horses on day 1 and 11 horses on day 2 were positive for EHV-1; overall, 90.9% of the nostril wipes, 81.8% of the environmental surfaces, and 90.9% of the droplet-catching devices were found to be positive. Quantitative analysis showed that the mean DNA copies detection per cm2 of nostril wipe sampled concentration (4.3 × 105 per day) was significantly (p < 0.05) comparable to that of nasal swabs (3.6 × 105 per day) followed by environmental swabs (4.3 × 105 per day) and droplet catchers (3.5 × 103 per day), respectively. Overall, 100% of the air samples collected were positive on both qPCR and dPCR. In individual air samples, a mean concentration of 1.0 × 104 copies of DNA were detected in per m3 air sampled per day, while in the collective air samples, the mean concentration was 1.1 × 103. Environmental samples look promising in replacing direct contact sampling. Environmental and air sampling could become efficient surveillance tools at equestrian events; however, it needs threshold calculations for minimum detection levels.

Levels of naturally occurring radioisotopes in local and imported bottled drinking water available in Québec City, Canada

Consumption of local and imported bottled water in Canada has greatly increased during the past three decades. While the presence of natural radioactivity is often overlooked when dealing with the water quality of these bottled products, it could contribute substantially to the uptake of radionuclides especially when sourced from regions with higher radioactivity levels compared to where it is consumed. In this study, the activity of several naturally occurring radionuclides (i.e., 210Po, 226,228Ra, 230,232Th, 234,235,238U) were measured in bottled water available in Québec, Canada after sample pretreatment and analysis by either radiometric or mass spectrometry approaches. 230,232Th and 228Ra concentrations were below minimum detectable activity levels in all samples tested. Analytical results for 234U, 235U, 238U, and 226Ra showed concentrations that ranged from 0.38 to 115 mBq/L, (2.2–313) x 10−2 mBq/L, 0.48–58.4 mBq/L, and 1.1–550 mBq/L, respectively. 210Po was detected in only 5 samples and its activity ranged from 2 to 26 mBq/L. To determine variability in activity within brands, the same brands of bottled water were purchased during two consecutive years and analyzed. The possible radiological impact of the consumption of these types of water was assessed based on different drinking habit scenarios. Some of the imported water brands showed higher activity concentrations than local sources or tap water, suggesting that individuals drinking predominantly imported bottled water would receive a higher radiation dose than those who drink mainly local water.

Ultralow 1/f noise in epigraphene devices

We report the lowest recorded levels of 1/f noise for graphene-based devices, at the level of SV/V2=SI/I2=4.4×10−16 (1/Hz), measured at f = 10 Hz (SV/V2=SI/I2 &amp;lt; 10−16 1/Hz for f &amp;gt; 100 Hz) in large-area epitaxial graphene on silicon carbide (epigraphene) Hall sensors. This performance is made possible through the combination of high material quality, low contact resistance achieved by edge contact fabrication process, homogeneous doping, and stable passivation of the graphene layer. Our study explores the nature of 1/f noise as a function of carrier density and device geometry and includes data from Hall sensors with device area range spanning over six orders of magnitude, with characteristic device length ranging from L = 1 μm to 1 mm. In optimized graphene Hall sensors, we demonstrate arrays to be a viable route to improve further the magnetic field detection: a simple parallel connection of two devices displays record-high magnetic field sensitivity at room temperature, with minimum detectable magnetic field levels down to Bmin = 9.5 nT/√Hz. The remarkable low levels of 1/f noise observed in epigraphene devices hold immense capacity for the design and fabrication of scalable epigraphene-based sensors with exceptional performance.

Comparison of the performance of two thermoluminescent dosimetry systems for the personal dose-equivalent Hp(10) measurement.

The performance of two thermoluminescent dosimetry systems (RGD-3D and RE2000) manufactured in China and Finland was compared. Both of these dosimetry systems demonstrated satisfactory results as their performance met the requirements of the standard. The two dosimetry systems showed similar performance in the energy response. The RGD-3D dosimetry system performed better in nonlinear response, minimum detectable level and blind sample tests, whereas the RE2000 dosimetry system showed better stability.

Analytical Method Development, Validation, and Applications of the HPTLC Densitometric Approach for Simultaneous Quantification of Azelnidipine and Chlorthalidone

For the simultaneous quantification of Azelnidipine and Chlorthalidone in synthetic combination, a high performance thin layer chromatographic method was devised that is quick, accurate, selective, and exact. The mobile phase used in the chromatographic analysis was in the ratio of 5: 4.7: 0.3: 0.1 v/v/v/v, and the stationary phase utilised was silica gel 60 F254 as the precoated stationary phase on aluminium plates. A 10 x 20 cm TLC chamber with a 15-minute saturation period was utilised. Azelnidipine and chlorthalidone were found to have retardation factors (RF) of 0.43 0.03 and 0.30 0.02, respectively. At 242 nm, densitometric analysis was performed. Following the ICH Q2 (R1) standard, a validation study was conducted. The calibration plots' regression data revealed a strong linear association with R2 = 0.999 for the concentration ranges of azelnidipine and chlorthalidone, 400–1200 ng band-1 and 600–1800 ng band-1, respectively. The method's precision, accuracy, and robustness were all validated. For azelnidipine and chlorthalidone, the minimum detectable levels were determined to be 26.71 ng band-1 and 38.39 ng band-1, respectively, and the limits of quantitation were found to be 80.94 ng band-1 and 116.033 ng band-1. Azelnidipine and chlorthalidone can be estimated simultaneously for routine analysis, in drug formulations, and in biological matrices, in short, using the proven analytical approach.

A novel plasmonic metal–semiconductor–insulator–metal (MSIM) color sensor compatible with CMOS technology

Color detection is one of the top interests in both biological and industrial applications. Specifically, the Determination of the light wave characteristics is vital in photonic technology. One of the features in the color sense that should be found out is its wavelength or color. In this work, we propose a structure that can be used to detect RGB colors separately in an efficient way. The proposed detector consists of the plasmonic filter sensing desired wavelength (red, green, and blue) and the PN diode to convert the received photons to the electrical current. At the input intensity of 1 mW × cm−2, the current density for blue, green, and red colors are 27, 35, and 48 µA × cm−2, respectively. It is shown that the intensities needed to obtain the current densities of 0.1 µA × cm−2 are 3.94, 2.98, and 2.25 µW × cm−2 for the blue, green, and red spectra respectively. It should mention that by using high-precision photodetector structures such as PIN diode, the minimum detectable level can be decreased. Simple adjusting for desired wavelength and linear operation for different input intensities are the characteristics of the designed structure. This detector is compatible with CMOS technology and can be easily utilized in numerous applications, such as charge-coupled devices, displays, and cameras.

Characterization of a commercial bioluminescence tomography-guided system for pre-clinical radiation research.

Widely used Cone-beam computed tomography (CBCT)-guided irradiators have limitations in localizing soft tissue targets growing in a low-contrast environment. This hinders small animal irradiators achieving precise focal irradiation. To advance image-guidance for soft tissue targeting, we developed a commercial-grade bioluminescence tomography-guided system (BLT, MuriGlo) for pre-clinical radiation research. We characterized the system performance and demonstrated its capability in target localization. We expect this study can provide a comprehensive guideline for the community in utilizing the BLT system for radiation studies. MuriGlo consists of four mirrors, filters, lens, and charge-coupled device (CCD) camera, enabling a compact imaging platform and multi-projection and multi-spectral BLT. A newly developed mouse bed allows animals imaged in MuriGlo and transferred to a small animal radiation research platform (SARRP) for CBCT imaging and BLT-guided irradiation. Methods and tools were developed to evaluate the CCD response linearity, minimal detectable signal, focusing, spatial resolution, distortion, and uniformity. A transparent polycarbonate plate covering the middle of the mouse bed was used to support and image animals from underneath the bed. We investigated its effect on 2D Bioluminescence images and 3D BLT reconstruction accuracy, and studied its dosimetric impact along with the rest of mouse bed. A method based on pinhole camera model was developed to map multi-projection bioluminescence images to the object surface generated from CBCT image. The mapped bioluminescence images were used as the input data for the optical reconstruction. To account for free space light propagation from object surface to optical detector, a spectral derivative (SD) method was implemented for BLT reconstruction. We assessed the use of the SD data (ratio imaging of adjacent wavelength) in mitigating out of focusing and non-uniformity seen in the images. A mouse phantom was used to validate the data mapping. The phantom and an in vivo glioblastoma model were utilized to demonstrate the accuracy of the BLT target localization. The CCD response shows good linearity with<0.6% residual from a linear fit. The minimal detectable level is 972 counts for 10×10 binning. The focal plane position is within the range of 13-18mm above the mouse bed. The spatial resolution of 2D optical imaging is<0.3mm at Rayleigh criterion. Within the region of interest, the image uniformity is within 5% variation, and image shift due to distortion is within 0.3mm. The transparent plate caused<6% light attenuation. The use of the SD imaging data can effectively mitigate out of focusing, image non-uniformity, and the plate attenuation, to support accurate multi-spectral BLT reconstruction. There is<0.5% attenuation on dose delivery caused by the bed. The accuracy of data mapping from the 2D bioluminescence images to CBCT image is within 0.7mm. Our phantom test shows the BLT system can localize a bioluminescent target within 1mm with an optimal threshold and only 0.2mm deviation was observed for the case with and without a transparent plate. The same localization accuracy can be maintained for the in vivo GBM model. This work is the first systematic study in characterizing the commercial BLT-guided system. The information and methods developed will be useful for the community to utilize the imaging system for image-guided radiation research.

3D printed Fabry-Perot acoustic probe with a glass horn tube

Sensing an incoming acoustic signal is typically associated with absorbing the energy, perturbing the measurement and therefore causing a deformation of the sensing elements, which is mainly related to the acoustic wave pressure. Here, we demonstrated a fiber-tip based Fabry-Perot (FP) acoustic probe sensor, which was directly printed on an optical fiber tip by a two-photon 3D printing technique and assembled by a glass horn structure, which can improve the sensitivity. It showed that the sensor has a −3 dB bandwidth of 366.05 kHz at the first resonant frequency of 467.84 kHz. A low noise-limited minimum detectable pressure level of 4.71 mPa/Hz1/2@100 kHz is obtained. Due to the acoustic wave focusing property of the horn structure, the detected signal intensity can be amplified by 4 times as the sensor located at the bottom position. It demonstrates that 3D printed micro acoustic devices could be used for weak acoustic wave detection in the applications of partial discharge, photoacoustic imaging and non-destructive detection.

The paraglacial adjustment of an Alpine lateral moraine, Bas Glacier d’Arolla, Switzerland

ABSTRACT Within Alpine catchments, glacial landforms are subject to post-depositional reworking during and following deglaciation. Ice-marginal moraines are thought to rapidly stabilise within ~200 years in this topographic context, although ice-proximal slopes are particularly prone to alteration by debris flows and solifluction. This study investigates landform transformation, documenting geomorphological change at the Bas Glacier d’Arolla, Switzerland. Gully development on a moraine slope was assessed using archive image sets obtained in 1977, 1988 and 2009 to derive historical elevation models. Raster differencing suggests that the mean rate of surface lowering on the upper moraine slope was 7.15 ± 1.83 m (± minimum level of detection) over the observation period (1977–2009), a rate of 0.22 m yr−1. The erosion of the landform resulted in an incontiguous moraine crestline. Whilst some landforms may undergo limited transformation upon deglaciation, selected sites are subject to rapid geomorphologic change, involving crestline retreat via the initial dissection by gullies, followed by the removal of inter-gully slopes.

Sensitivity-enhanced Fabry-Perot interferometric fiber-optic microphone using hollow cantilever.

Transducer components are crucial in optimizing the sensitivity of microphones. Cantilever structure is commonly used as a structural optimization technique. Here, we present a novel Fabry-Perot (F-P) interferometric fiber-optic microphone (FOM) using a hollow cantilever structure. The proposed hollow cantilever aims to reduce the effective mass and spring constant of the cantilever, thereby enhancing the sensitivity of the FOM. Experimental results demonstrate that the proposed structure outperforms the original cantilever design in terms of sensitivity. The sensitivity and minimum detectable acoustic pressure level (MDP) can reach 91.40 mV/Pa and 6.20 µPa/Hz at 1.7 kHz, respectively. Notably, the hollow cantilever provides an optimization framework for highly sensitive FOMs.

Evaluating the Integrity of High-Density Polyethylene Storage Tanks

Failure of high-density polyethylene (HDPE) aboveground storage tanks (ASTs) causes numerous environmental, ecological, and economic problems. Therefore, it is necessary to routinely inspect the integrity of ASTs to identify the potential defects and act before a catastrophic failure happens. This study investigated the feasibility of using infrared thermography (IRT) for routine HDPE AST inspections and how weathering impacts the properties of HDPE. Moreover, the factors affecting the IRT’s accuracy for defect detection were researched, and it was attempted to determine the minimum levels of defect detection for each weather circumstance. This study investigated the potential areas for tank failure for close inspection. Results showed that IRT is efficient in detecting shallow defects within the outer half of the wall. The smallest detectable defect size was 2.8 mm, which varied in different measurements depending on the interaction of sample geometry, initial thermal gradient, and defect location.

Detection and localization of F-layer ionospheric irregularities with the back-propagation method along the radio occultation ray path

Abstract. The back-propagation (BP) method consists of diffractive integrals computed over a trajectory path, projecting a signal to different planes. It unwinds the diffraction and multipath, resulting in minimum disturbance to the BP amplitude when the auxiliary plane coincides with the region causing the diffraction. The method has been previously applied in global navigation satellite system (GNSS) radio occultation (RO) measurements to estimate the location of ionospheric irregularities but without complementary data to validate the estimation. In this study, the BP method is applied to a Communications/Navigation Outage Forecasting System (C/NOFS) occultation event containing scintillation signatures caused by an equatorial plasma bubble (EPB), which was parameterized with the aid of collocated data and reproduced in a wave optics propagator (WOP) simulation. In addition, a few more test cases were designed to assess the BP method with regard to the size, intensity, and placement of single- and multiple-irregularity regions. The results show a location estimate accuracy following the resolution at which the method is implemented (single bubble, reference case), whereas a bias is observed in multiple-bubble scenarios. The minimum detectable disturbance level and the estimation accuracy depend on the receiver noise level and, in the case of several bubbles, on the distance between them. These remarks provide insight into the BP results for two Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) occultation events.

GEO-SPATIAL MAPPING OF IRON (FE) AND MANGANESE (MN) PRESENT IN GROUNDWATER OF CLARK, PHILIPPINES

The study covers a comprehensive analysis of Fe and Mn to characterize their distribution and occurrence within the Clark Freeport Zone. 3-year groundwater samples taken from 39 wells/boreholes scattered throughout the study area. Fe was most frequently detected with concentrations near the limits of Philippine National Standards for Drinking Water (PNSDW). 0.42% of the 958 studied samples for Fe had concentration greater than the 1mg/L limit. As for Mn, none of the 909 samples for Mn had concentration greater than the PNSDW. Of those wells that have shown presence higher than the minimum detection level (MDL), 5 have been installed with individual filtration system (DMI-65) to capture Fe and Mn. No correlation has been found between the two parameters. As for seasonality, there is an obvious spike in Fe for all wells during the months of July, September, and October. Mn on the other hand manifested a spike in July for the shallow wells. The QGIS3 software was also used to develop a spatial map and report the distribution presence. From the generated maps, Fe and Mn gradually increase in concentration going north to northeastern directions of CFZ. The produced map can be key in raising awareness of the public and fellow water concessionaires with regards to the possible extent of underground Fe and Mn presence. Information generated here will be valuable as resources, and engineering controls can be applied to give priority to the low probability affected areas.

Radioactive contamination in feral dogs in the Chernobyl exclusion zone: Population body-burden survey and implications for human radiation exposure.

This report describes a two-year effort to survey the internal 137Cs and external β-emitter contamination present in the feral dog population near the Chernobyl nuclear power plant (ChNPP) site, and to understand the potential for human radiation exposure from this contamination. This work was performed as an integral part of the radiation safety and control procedures of an animal welfare oriented trap-neuter-release (TNR) program. The measurement program focused on external contamination surveys using handheld β-sensitive probes, and internal contamination studies using a simple whole-body counter. Internal 137Cs burden was measured non-invasively during post-surgical observation and recovery. External β contamination surveys performed during intake showed that 21/288 animals had significant, removable external contamination, though not enough to pose a large hazard for incidental contact. Measurements with the whole-body counter indicated internal 137Cs body burdens ranging from undetectable (minimum detection level ∼100 Bq/kg in 2017, ∼30 Bq/kg in 2018) to approximately 30,000 Bq/kg. A total of 33 animals had 137Cs body-burdens above 1 kBq/kg, though none posed an external exposure hazard. The large variation in the 137Cs concentration in these animals is not well-understood, could be due to prey selection, access to human food scraps, or extended residence in highly contaminated areas. The small minority of animals with external contamination may pose a contamination risk allowing exposures in excess of regulatory standards.

Ppb-Level Detection Triethylamine Gas Sensor Based on Ag-Doped Nanosheets-Assembled Octahedron Zn2SnO4

The current semiconductor sensors cannot detect the ultra-low concentration of triethylamine (TEA). Therefore, this paper uses the catalytic activation effect of precious metal silver and combined with the unique physical and chemical properties of ternary metal oxides to design the Ag-doped Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> gas sensor to detect the ultra-low concentration of TEA. In this work, spinel-type metal oxides Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> was prepared by one-step hydrothermal method and its functional modification by means of precious metal doping. The countenance and elemental content of the synthesized products were dissected through diverse means. Combined with the characterization data, it is shown that Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> samples all present a fixed octahedral shape and the surface is assembled by a large number of nanoplates. The gas sensing test results show that the gas sensor based on 3at% (atom percent) Ag doped Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> has the best gas sensing performance for TEA. Its response to 100 ppm TEA at 250°C is 273.33. At the same time, the minimum detectable concentration level is 100 ppb. In addition, the material also demonstrates fast response time, good stability and high selectivity. The excellent gas sensing performance is mainly attributed to the synergistic effect of chemical sensitization and electron sensitization of precious metal silver.

Cell-Free DNA (cfDNA)-Based Measurable Residual Disease (MRD) Detection As a Predictor of Relapse Post-Allogeneic Blood or Marrow Transplant (alloBMT) in Patients with Myeloid Malignancies

Background: AlloBMT is the only curative therapy for many patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). With the significant improvement in non-relapse mortality, disease relapse remains the main cause of therapeutic failure. The presence of leukemia-specific somatic mutations provides an attractive strategy for molecular assessment of measurable residual disease (MRD). The level of MRD at the time of complete remission (CR) has been an important predictor of relapse in patients undergoing alloBMT. Widely utilized molecular MRD assays require invasive bone marrow (BM) aspiration to ensure an adequate amount of residual leukemia cells. Circulating tumor DNA (ctDNA) released from malignant cells can be reliably detected in patients' plasma and has been widely used in diagnosis, early detection, and disease burden monitoring in solid tumors. This assay is not widely used in myeloid malignancies as the proper assessment of its technical and clinical utility as an MRD monitoring strategy has not been performed. In the current study, we aimed to determine the differential sensitivity between bone marrow and ctDNA-based MRD and its utility as a minimally invasive diagnostic and disease monitoring tool. Additionally, we evaluated the clinical utility of dynamic ctDNA-based MRD monitoring and its effect on post-alloBMT relapse by using plasma samples from 2 large prospective clinical trials (BMT CTN 0201 and 0402). Methods: The technical validation cohort included 20 consecutive patients with myeloid malignancies undergoing alloBMT at Johns Hopkins. A minimum of 10mL of plasma and bone marrow DNA was collected at the time of remission and at multiple time points after alloBMT. The clinical validation cohort included 90 patients participating in two prospective alloBMT trials (BMT CTN-0201 and 0402). The eligibility criteria included the diagnosis of myeloid malignancy (72 AML, 18 MDS) and the minimum of 2mL of plasma available from day 0 and/or day 90 after alloBMT. Ultra-deep error-corrected targeted sequencing was performed on plasma and bone marrow-derived DNA. The variant allele frequency (VAF) per patient was represented by the maximum VAF of all detected mutations. Results: To measure the exact contribution of hematopoietic tissue to plasma cell-free DNA (cfDNA) we analyzed cfDNA in alloBMT recipients. Using donor and recipient-specific polymorphisms we demonstrated that after full donor hematopoietic reconstitution by standard chimerism assays (day +180), 94.6% (range 93.9-95.3%) of cfDNA was of hematopoietic origin. To determine the differential sensitivity of the cfDNA vs. BM-based MRD we focused only on leukemia-specific mutations found in the diagnostic specimens. The minimum level of detection was 0.03%. Forty leukemia-specific mutations were detected in the technical validation cohort. Out of 31 mutations seen in the BM, only 3 were not detected in cfDNA (3/31, 9.7%). On the contrary, out of 37 mutations in cfDNA, 9 were not seen in BM (9/37, 25%). While we observed a strong positive correlation (rho = 0.8, p<0.0001) at any level of MRD between BM and cfDNA, cfDNA was superior at the lower MRD level (VAF cut-off < 0.26%). The clinical utility of cfDNA MRD was utilized in a separate validation cohort of 90 patients enrolled on 2 BMT CTN trials. The median (Q1, Q3) follow-up was 26 months (25 - 27 months). cfDNA-MRD positivity (VAF cutoff >0.25%) at day +90 was associated with significantly worse relapse-free survival (RFS) (46.2% vs 84.0%, p<0.001) and overall survival (OS) at two years (53.8% vs 87.2%, p=0.0013) after alloBMT. Conclusions: cfDNA-based MRD assessment appears to be a promising, minimally invasive test that provides important prognostic information in patients with myeloid malignancies undergoing alloBMT. The presence of cfDNA MRD at day 90 post alloBMT was associated with significantly worse RFS and OS in patients with myeloid malignancies. The dynamic assessment of MRD by cfDNA may not only provide important prognostic information but may also guide the therapeutic decision-making and timely implementation of post-alloBMT maintenance therapies to improve outcomes of patients with myeloid malignancies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Infrared dual-gas CH4/C2H2 sensor system based on dual-channel off-beam quartz-enhanced photoacoustic spectroscopy and time-division multiplexing technique

Highly sensitive and stable measurement of methane (CH4) and acetylene (C2H2) based on a novel dual-channel off-beam quartz-enhanced photoacoustic spectroscopy and time-division multiplexing technique was realized by a compact 3D-printed gas cell with a size of 3 × 2 × 1 cm3. Two near-infrared distributed feedback diode lasers were employed to target the CH4 absorption line at 6046.9 cm−1 and the C2H2 absorption line at 6521.2 cm−1, respectively. Second-harmonic wavelength modulation spectroscopy method was used for photoacoustic signal recovery. A minimum detection level of ∼ 7.63 parts-per-million in volume (ppmv) for CH4 and a level of ∼ 17.47 ppmv for C2H2 were achieved with a 1 s lock-in integration time, leading to a normalized noise equivalent absorption (NNEA) coefficient of 7.24 × 10-8 cm−1·W·Hz−1 and 3.73 × 10-8 cm−1·W·Hz−1 for CH4 and C2H2, respectively. Allan-Werle deviation analysis was employed to evaluate the stability and the minimum detection limit (MDL) of the developed photoacoustic CH4/C2H2 dual-gas photoacoustic sensor. Owing to the high stability of the developed sensor system, an MDL of ∼ 0.73 ppmv and an MDL of ∼ 1.60 ppmv with a 100 s averaging time were achieved for CH4 and C2H2, respectively.

Patients with Hepatitis C on Direct-Acting Antiviral Agents' Response to the Elimination Program in Dammam City within 2018-2020

Background: Hepatitis C virus (HCV) is a worldwide health challenge that imposes urgent interventions for prevention and control. We aimed to assess the response rate for the direct-acting antiviral agents (DAAs) regimen in HCV-infected patients attending the public health centers/hospitals in the Western region of Saudi Arabia. Methods and Results: A retrospective study was followed, including data from the electronic medical records of HCV-infected adult patients in the period 2018-2020. Patients underwent HCV health education and treatment with DAAs according to the regional protocols. The type of treatment regimens provided to the included patients was recorded with the outcome (respondent vs. non-respondent) after 12 weeks post completion of treatment (SVR12) based on negative results (or less than the minimum detection levels using the specified assay) of HCV-RNA detected by polymerase chain reaction. The SVR12 was used for predicting SVR as it was reported to be applicable as SVR24. All cases with discontinuations, treatment modifications, and/or deaths were excluded. Included were a total of 505 adult patients recorded in 13 primary healthcare units and hepatitis treatment specialty clinics of hospitals in the Eastern region of Saudi Arabia during the specified period of the study. The patients were aged 30–73 years (mean age of 48.1±9.1 years), of which 229(45.3%) were females and 276(54.7%) males. Most patients received sofosbuvir/daclatasvir (86.1%), followed by glecaprevir/pibrentasvir (11.5%), and elbasvir/grazoprevir (2.4%). Overall, the SVR rate was 97.4% in the study population. Sofosbuvir/daclatasvir had an SVR12 of approximately 98.4%, while the rate of glecaprevir/pibrentasvir was 93.1%. Conclusion: The present findings show an overall HCV cure rate of 97.4% of patients with HCV in response to the elimination program with DAAs in the Eastern region of Saudi Arabia, as indicated by high SVR12. This is an example of treating patients with HCV in a structured, supportive setting to help in the HCV elimination program.

On the uncertainty associated with detecting global and local mean sea level drifts on Sentinel-3A and Sentinel-3B altimetry missions

Abstract. An instrumental drift in the point target response (PTR) parameters has been detected on the Copernicus Sentinel-3A altimetry mission. It will affect the accuracy of sea level sensing, which could result in errors in sea level change estimates of a few tenths of a millimeter per year. In order to accurately evaluate this drift, a method for detecting global and regional mean sea level relative drifts between two altimetry missions is implemented. Associated uncertainties are also accurately calculated thanks to a detailed error budget analysis. A drift on both Sentinel-3A (S3A) and Sentinel-3B (S3B) global mean sea level (GMSL) is detected with values significantly higher than expected. For S3A, the relative GMSL drift detected is 1.0 mm yr−1 with Jason-3 and 1.3 mm yr−1 with SARAL/AltiKa. For S3B, the relative GMSL drift detected is −3.4 mm yr−1 with Jason-3 and −2.2 mm yr−1 with SARAL/AltiKa. The drift detected at global level does not show detectable regional variations above the uncertainty level of the proposed method. The investigations led by the altimeter experts can now explain the origin of this drift for S3A and S3B. The ability of the implemented method to detect a sea level drift with respect to the length of the common period is also analyzed. We find that the minimum detectable sea level drift over a 5-year period is 0.3 mm yr−1 at the global scale and 1.5 mm yr−1 at the 2400 km regional scale. However, these levels of uncertainty do not meet the sea level stability requirements for climate change studies.

Application of the prenatal BACs-on-Beads™ assay for rapid prenatal detection of sex chromosome mosaicism

The prenatal BACs-on-Beads™ (BoBs) assay was introduced for rapid detection of abnormalities of chromosomes 13, 18, 21, X, and Y and specific nine significant microdeletion syndromes. The ability of prenatal BoBs to detect mosaicism ranged from 20 to 40%. However, there have been no prenatal studies of sex chromosome mosaicism in prenatal BoBs. Therefore, the present study was performed with an aim to uncover the detection level of sex chromosome mosaicism that application of prenatal BoBs assay, and then to assess the sensitivity of prenatal BoBs assay, thereby improving the prenatal diagnostic accuracy. A total of 31 samples of amniotic fluid (AF) and umbilical cord blood (UCB) for prenatal diagnosis were collected, and the results were confirmed through karyotyping, single nucleotide polymorphism microarray (SNP-array) and copy number variation sequencing (CNV-seq). 23 cases of sex chromosome mosaicism were prompted abnormal by prenatal BoBs, the minimum detection level of mosaicism was about 6% as detected by karyotype. The overall sensitivity of prenatal BoBs in the detection of sex chromosome mosaicism was 74.2% (23/31). This study evaluated the effectiveness of prenatal BoBs for detecting sex chromosome mosaicism in prenatal diagnosis, and the results will provide valuable information for genetic counseling.