Relative Response Values Research Articles

In Situ Synthesis of Hierarchical Co(CO3)0.5(OH)·0.11H2O@ZIF-67/WO3 With High Humidity Immunity and Response to H2S Sensing.

H2S gas sensors with facile preparation, low detection limits, and high selectivity are crucial for environmental and human health monitoring. However, it is difficult to maintain a high response of H2S gas sensors under high humidity in practical applications. To face this dilemma, a layer-by-layer growth method is applied to in situ prepare a nanostructured Co(CO3)0.5(OH)·0.11H2O/WO3 coated by a hydrophobic hierarchical ZIF-67 as the H2S sensor. This novel composite exhibits excellent humidity immunity without sacrificing the excellent sensitivity and selectivity of H2S. At a low operating temperature of 90°C, a remarkable response value of 1052.3 to 100ppm H2S has been achieved, which is 779 and 9.36 times higher than that of pure WO3 and Co(CO3)0.5(OH)·0.11H2O/WO3, respectively. More importantly, an 82.2% relative response value remains at a high humidity of 75%RH. The sensing mechanisms are investigated using gas chromatography-mass spectrometry (GC-MS), which revealed that the reaction products are H2O and SO2. The high humidity immunity and fast response of the Co(CO3)0.5(OH)·0.11H2O@ZIF-67/WO3 demonstrate the layer-by-layer in situ synthesis method holds the potential application for the development of high-performance WO3-based H2S sensors.

Detection of NH3 gas using CrVO4 nanoparticles

Nanostructured chromium orthovanadate with an average particle size of 65 nm was prepared by the co-precipitation technique for the chemiresistive sensor. The morphology and particle size distribution of CrVO4 nanoparticles were examined by SEM and TEM. According to XRD, most of the prepared CrVO4 material (crystallites) has a monoclinic structure belonging to the space group C2/m. XPS and UV-Vis absorbance measurements provided additional information on the main phase and the surface. The material has shown reasonable selectivity towards the NH3 gas. The as-prepared CrVO4 nanostructures exhibit a maximum relative response of 32% to 50 ppm NH3. The identical dynamic response profiles during the sequential injections of 50 ppm NH3 evinced the repeatability of the sensor. The limit of detection (LOD) value of the sensor was estimated ca 0.7 ppm using relative response values towards a wide range of NH3 concentrations from 10 ppm to 100 ppm. The sensing mechanism was expressed in terms of the surface band bending phenomenon caused by the adsorption and desorption of the ammonia. The best sensor performance was achieved at 330 °C, where the effects of humidity and moisture can be neglected. The results confirmed that the CrVO4 nanomaterial has the potential to fabricate an affordable, easy-to-make, and reliable gas sensor for NH3 gas.

The extreme wet and large precipitation size increase carbon uptake in Eurasian meadow steppes: Evidence from natural and manipulated precipitation experiments

The distribution of seasonal precipitation would profoundly affect the dynamics of carbon fluxes in terrestrial ecosystems. However, little is known about the impacts of extreme precipitation and size events on ecosystem carbon cycle when compared to the effects of average precipitation amount. The study involved an analysis of carbon fluxes and water exchange using the eddy covariance and chamber based techniques during the growing seasons of 2015–2017 in Bayan, Mongolia and 2019–2021 in Hulunbuir, Inner Mongolia, respectively. The components of carbon fluxes and water exchange at each site were normalized to evaluate of relative response among carbon fluxes and water exchange. The investigation delved into the relationship between carbon fluxes and extreme precipitation over five gradients (control, dry spring, dry summer, wet spring and wet summer) in Hulunbuir meadow steppe and distinct four precipitation sizes (0.1–2, 2–5, 5–10, and 10–25 mm d−1) in Bayan meadow steppe. The wet spring and summer showed the greatest ecosystem respiration (ER) relative response values, 76.2% and 73.5%, respectively, while the dry spring (−16.7%) and dry summer (14.2%) showed the lowest values. Gross primary production (GPP) relative response improved with wet precipitation gradients, and declined with dry precipitation gradients in Hulunbuir meadow steppe. The least value in net ecosystem CO2 exchange (NEE) was found at 10–25 mm d−1 precipitation size in Bayan meadow steppe. Similarly, the ER and GPP increased with size of precipitation events. The structural equation models (SEM) satisfactorily fitted the data (χ2 = 43.03, d.f. = 11, p = 0.215), with interactive linkages among soil microclimate, water exchange and carbon fluxes components regulating NEE. Overall, this study highlighted the importance of extreme precipitation and event size in influencing ecosystem carbon exchange, which is decisive to further understand the carbon cycle in meadow steppes.

Influence of particle characteristics, heating temperature and time on the pyrolysis product distributions of polystyrene micro- and nano-plastics

Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) has been widely used for the detection of micro- and nanoplastics (MNPs) in the environment. However, there is a lack of thorough investigation on the effects of pyrolysis temperature and time, as well as the particle source, size and mass of MNPs on the pyrolysis efficiency and pyrolysis product distribution of MNPs. Herein, taking the common plastics polystyrene (PS) as a model, we systematically evaluated the influences of the above factors on the pyrolysis of PS MNPs. Results showed that pyrolysis temperature and time significantly affect the pyrolysis efficiency. By measuring the relative response values of the indicator compound styrene trimers to styrene monomer, the optimum condition was determined as the temperature of 510 ℃ and pyrolysis time longer than 18 s. Meanwhile, the mass of MNPs also affected the distribution of PS pyrolysis products. The proportions of styrene dimers and trimers increased slightly with PS MNP mass, while the source, particle size of MNPs have little effect on the pyrolysis product distribution. This work proposed a suitable pyrolysis temperature and time for the determination of PS by Py-GC/MS, which would contribute to the accurate analysis of PS MNPs in the environment.

Prediction by statistical overlap theory of fraction of baseline occupied by chromatographic peaks

The average minimum resolution required for separating adjacent single-component peaks (SCPs) in one-dimensional chromatograms is an important metric in statistical overlap theory (SOT). However, its value changes with changing chromatographic conditions in non-intuitive ways, when SOT predicts the average number of peaks (maxima). A more stable and easily understood value of resolution is obtained on making a different prediction. A general equation is derived for the sum of all separated and superposed widths of SCPs in a chromatogram. The equation is a function of the saturation α, a metric of chromatographic crowdedness, and is expressed in dimensionless form by dividing by the duration of the chromatogram. This dimensionless function, f(α), is also the cumulative distribution function of the probability of separating adjacent SCPs. Simulations based on the clustering of line segments representing SCPs verify expressions for f(α) calculated from five functions for the distribution of intervals between adjacent SCPs. Synthetic chromatograms are computed with different saturations, distributions of intervals, and distribution of SCP amplitudes. The chromatograms are analyzed by calculating the sum of the widths of peaks at different relative responses, dividing the sum by the duration of the chromatograms, and graphing the reduced sum against relative response. For small values of relative response, the reduced sum approaches the fraction of baseline that is occupied by chromatographic peaks. This fraction can be identified with f(α), if the saturation α is defined with the average minimum resolution equaling 1.5. The identification is general and is independent of the saturation, the interval distribution, or the amplitude distribution. This constant value of resolution corresponds to baseline resolution, which simplifies the interpretation of SOT.

Discussion on stability of mixed standard application solution by volatilization organic compounds in workplace air

Objective: To discuss the stability of mixed standard application solution by volatilization organic matter (benzene, toluene, xylene, ethylbenzene, acetone, butanone, Ethyl acetate, butyl ester, trichloroethylene) in workplace air. Methods: A total of 11 kinds volatilization organic compounds were separated by capillary chromatographic column, and detected with flame ionization detector. The stability of mixed standard application solution was judged by studying three paratemers during the placement period, such as the linear correlation coefficient of the standard curve, the relative response values of the highest and lowest concentration levels and the accuracy of the measured values of the quality control samples. Results: Within 187 days, the linear correlation coefficient of each compound was ≥0.999. The changes of relative response values at the highest and lowest concentration levels were both <10%; The measured values of toluene were all in the reference range. Conclusion: The mixed standard application solution is stable and reliable within 187 days of storage.

Room temperature high performance ammonia sensor using MoS2/SnO2 nanocomposite

A MoS2/SnO2 composite based ammonia gas sensor working at room temperature has been demonstrated in present work. Structural and vibrational analysis confirmed the formation of MoS2/SnO2 composite. Compared with SnO2 based sensor, the device made from composite showed exceptional selectivity and sensitivity towards ammonia at room temperature. The sensor showed a room temperature relative response of nearly 10% with 50 ppm of ammonia. The corresponding response and recovery times are 35 s and 15 s, respectively, much smaller than value found for SnO2/multi-walled carbon nanotubes based composite sensor at room temperature. The obtained relative response value is larger than the value obtained while using pure SnO2 as ammonia sensing device. The latter, though responds only at high temperature and has poor selectivity towards various gases. These, initial results provides a new direction to improve both room temperature sensitivity as well as selectivity behaviour of sensors based on composite materials derived from transition metal dichalcogenides and SnO2.

Improved Ammonia Sensing by Solution Processed Dodecyl Benzene Sulfonic Acid Doped Polyaniline Nanorod Networks

Dodecyl benzene sulphonic acid (DBSA) doped polyaniline (PANI) nanorods have been synthesized by a templateless route via in-situ emulsion polymerization of aniline in aqueous DBSA solution. XRD patterns, UV-Visible Spectroscopy, and FTIR analysis confirm the formation of PANI and PANI-DBSA, whereas FESEM images revealed their elongated rod shaped morphology. The chloroform dispersion of synthesized PANI-DBSA was spin coated over prefabricated interdigitated Pt patterned glass substrate to realize porous gas sensing active layer. The sensor displays good response in 1–1200 ppm ammonia concentration range and can repeatedly detect 300 ppm of ammonia with response time of 6 s, recovery time of 37 s and relative response value of 9.57. Besides, its response was found to be linear for 1–50 ppm ammonia concentration with relative response per ppm value of 0.01675.

Energy Correction Factors for Silicon Semiconductor Dosimeter in Adult-male Phantom for Accurate Measurement of Organ Doses

Metal oxide semiconductor field effect transistor (MOSFET) dosimeters are used to measure radiation dose in various medical applications and radiation safety. The advantage of the MOSFET dosimeter is that it is very small and provides practically real-time reading. However, given the fact that it is made mainly of silicon and epoxy, which are not ideally tissue equivalent, the MOSFET dosimeter shows some energy dependence for low-energy photons and will overestimate the energy deposition or absorbed dose in tissue when it is used in a phantom, due to the existence of scattered low-energy photons in the phantom. The present study determined, by Monte Carlo simulations with MCNPX, the relative response of the MOSFET dosimeter to the tissue dose, and thereby the energy correction factors, at various dosimeter locations in the ATOM adult-male phantom, in order to be able to accurately measure organ and tissue doses. The calculated values of relative response were 1.0-1.2 and 1.0-1.1 for 0.662 MeV and 1.25 MeV photons, respectively, which shows that if we do not use appropriate correction factors, the measurement of an organ dose could be overestimated by 10-20%, depending on the measurement condition. The result in study also shows that the energy correction factors are not very sensitive to the detailed energy spectrum of the photon field, and that the energy correction factors determined from the 0.662 MeV and 1.25 MeV photons can be used in the radiation fields in nuclear power plants without significant errors.

Fabrication and application of carbohydrate microarray for analyzing human serum antibody–carbohydrate interaction

We introduced a strategy for preparing a carbohydrate microarray and demonstrated its utility for characterizing carbohydrate binding and activities. We isolated the lipopolysaccharide (LPS) components from different bacteria and explored the possibility of immobilizing these glycoconjugates on a high-binding polystyrene plate. Carbohydrate-specific combination was examined by observing the binding of the blood group B analogic LPS O-polysaccharide from Escherichia coli on the high-binding polystyrene plate and anti-B from a broad spectra antibody of human blood serum. Strong binding of antibodies was screened, as it was evident that relative response value is two times higher than control. The hybridization results indicated that this method is a reliable technique for the detection of human intestinal bacteria and is expected to be applied in diagnostics and seroepidemiology.

Phosphorylation-independent Regulation of Metabotropic Glutamate Receptor 1 Signaling Requires G Protein-coupled Receptor Kinase 2 Binding to the Second Intracellular Loop

Metabotropic glutamate receptors (mGluRs) are members of a unique class of G protein-coupled receptors (class III) that include the calcium-sensing and gamma-aminobutyric acid type B receptors. The activity of mGluRs is regulated by second messenger-dependent protein kinases and G protein-coupled receptor kinases (GRKs). The attenuation of both mGluR1a and mGluR1b signaling by GRK2 is phosphorylation- and beta-arrestin-independent and requires the concomitant association of GRK2 with both the receptor and Galpha(q/11). G protein interactions are mediated, in part, by the mGluR1 intracellular second loop, but the domains required for GRK2 binding are unknown. In the present study, we showed that GRK2 binds to the second intracellular loop of mGluR1a and mGluR1b and also to the mGluR1a carboxyl-terminal tail. Alanine scanning mutagenesis revealed a discrete domain within loop 2 that contributes to GRK2 binding, and the mutation of either lysine 691 or 692 to an alanine within this domain resulted in a loss of GRK2 binding to both mGluR1a and mGluR1b. Mutation of either Lys(691) or Lys(692) prevented GRK2-mediated attenuation of mGluR1b signaling, whereas the mutation of only Lys(692) prevented GRK2-mediated inhibition of mGluR1a signaling. Thus, the mGluR1a carboxyl-terminal tail may also be involved in regulating the signaling of the mGluR1a splice variant. Taken together, our findings indicated that kinase binding to an mGluR1 domain involved in G protein-coupling is essential for the phosphorylation-independent attenuation of signaling by GRK2.

Analysis of human serum antibody–carbohydrate interaction using biosensor based on surface plasmon resonance

Surface plasmon resonance (SPR) was used to monitor the interaction of αGal-antibodies from human blood group O serum with linear blood group B-saccharides, employing Galα1-3Galβ1-4GlcNAc-HSA immobilised on a sensor chip surface. Strong binding of antibodies, as evident from high relative response values exceeding 200 RU, was observed. The interaction was influenced by the nature of the oligosaccharide that was added to the antibody sample prior to measurement. For example, the addition of either of the linear B-saccharides Galα1-3Gal and Galα1-3Galβ1-4GlcNAc produced complete inhibition of antibody binding to the sensor surface, whereas the addition of the related but non-specific blood group A saccharide, GalNAcα1-3(Fucα1-2)Gal, had little effect on binding. The technique was used for the rapid monitoring of the removal of αGal-antibodies from human serum by affinity columns, which contained either Galα1-3Gal or Galα1-3Galβ1-4GlcNAc as ligand. The above carbohydrates are currently evaluated as inhibitors or as affinity ligands, in the prevention of hyperacute rejection during xenotransplantation.

The MLC assay as a test for HLA-D region compatibility between patients and unrelated donors: results of a national marrow donor program involving multiple centers.

Mixed lymphocyte culture (MLC) assays from 763 patients and prospective unrelated marrow transplant donors identified through the National Marrow Donor Program (NMDP) were analyzed for their overall utility in measuring HLA-D region compatibility. The assays were performed at 31 different transplant centers (range, 1 to 197; median, 9 assays per center). A total of 325/763 (42.6%) of the tests were judged to be uninterpretable, either due to lack of sufficient control cells included in the assay (89 tests) or to insufficient reactivity by patient and/or donor cells (236 tests). Among the 438 tests that could be interpreted, HLA-Dw phenotyping with HLA-D homozygous cells was performed for a subset of 190. The relative response (RR) values from these 190 tests, however, were not clearly separable into distinct populations; i.e., RR values corresponding to Dw identity versus nonidentity between patient and donor could not be reliably discriminated. The predictive value of a nonreactive MLC for Dw identity was calculated to be 0.91 for RRs of < or = 20%, while the predictive value of a reactive MLC for Dw nonidentity was 0.35 for RRs of > 20%. These results, based on an analysis of data submitted from multiple transplant centers testing patients who had a variety of hematologic disorders, suggest that the MLC assay is a relatively imprecise method for determining HLA-D region compatibility between patient and prospective unrelated marrow donor.

Multisphere Neutron Spectroscopy Measurements at the Los Alamos National Laboratory Plutonium Facility

Multisphere neutron spectroscopy methods are applied to measure representative working fields within the Los Alamos National Laboratory (LANL) Plutonium Facility. This facility hosts dynamic processes, which include the fabrication of {sup 238}Pu heat sources for radioisotope generators used to power space equipment and a variety of plutonium research programs that involve recovery, hydrofluorination, and metal production. Neutron fluence per unit lethargy, as a function of neutron energy measured for locations throughout this facility, are described. Dosimeter/remmeter response functions [e.g., determined for a 22.8-cm-diameter neutron rem detector (NRD), an Anderson/Braun-type neutron ``Snoopy`` monitor, track-etch CR-39, BDI-100 bubble detectors, and Kodak type A nuclear track emulsion film, (NTA)] are folded into these spectra to calculate absolute response values of counts, tracks, or bubbles per unit-dose equivalent. The relative response values per unit- dose equivalent for bare and albedo {sup 6}LiF-based thermoluminescent dosimeters (TLDs) are also calculated to estimate response scenarios encountered with use of the LANL-TLD. These results are further compared to more conventional methods of estimating neutron spectral energies such as the ``9-to-3 ratio`` method.

Correlation between relative responses in mixed lymphocyte culture, HLA-D and DR typing, and graft survival in renal transplantation.

The impact of renal graft survival of a low relative response (RR) in mixed lymphocyte culture (MLC) and HLA-D/DR compatibility was analyzed. Ninety-five recipients and donors of cadaver kidneys and 58 intrafamilial, HLA-haploidentical, recipient-donor pairs in a Stockholm series constituted the case material. The gene frequencies of and the correlation coefficients between the HLA-D/DR assignments were calculated from an extended material of about 400 individuals, all recipients or donors of renal grafts in Stockholm. Close correlation between the D and DR assignments existed. The combined gene frequencies of the detected D/DR antigens were 0.67 and 0.08. The RR values in the MLC tests were widely scattered, but lower medians were found in the better D/DR-matched groups. The 1-year survival of cadaveric grafts was 69% when the RR values in the MLC between recipient and donor were below 55 and 49% when the RR values were above 55%. The difference was statistically significant (P less than 0.05). Also, significantly higher graft survival rates were obtained in transplants groups where the recipient and donors were well matched for the D and DR antigens. In the transplant groups where no D/DR incompatibility existed, the 1-year graft survival was 93 and 89%, respectively, when the RR values in the MLC tests between recipients and donors were below 55%. We concluded that a close correlation existed between cellular and serological HLA-DS typing. A beneficial effect was noted on graft survival of matching for these antigens.

Response of the Flame Ionization Detector to Some Perfluorocarbons

The response of an FID to CF4, C2F6, c-C6F12 and c-C7F14 was determined over a wide range of operating conditions. The high carbon number fluorocarbons showed response values similar to those of the corresponding hydrocarbons and their relative response values were almost independent of operating conditions and near to unity, provided higher H2 flowrates than usual for hydrocarbons were employed. For the light fluorocarbons, in addition to their much lower response, it was difficult to find suitable operating conditions for the FID due to the high dependence upon flowrates, etc. From the data it was also concluded that different mechanisms determining the height of the response were operating. For low carbon numbers and/or low H2 flowrates the main governing factor seemed to be the flame temperature, whereas at high carbon numbers and/or high H2 flowrates, the temperature became of little importance.

LiF response to high energy X-rays and electrons relative to 60Co photons

The energy independence of LiF and its relative response to 60Co photons at high radiation energies have been areas of conflicting reports. Several investigations of LiF relative response based on FeSO 4, have been carried out over the last decade. Data from these have the advantage over similar estimates based on ionometric methods in that they can be readily normalized to same G F c 3+ values. Normalization has been carried out, leading to better agreement and more reliable values of relative response. The normalizing process trimmed off errors of up to 5% in some of the data to reveal a trend: this error is high in relation to the actual decrease in relative response (of the order of 10%). A value of 0.929 ± 0.014 was obtained for high energy X-rays and electrons relative response to 60Co photons for commonly used sizes of LiF (predominantly 1 mm thickness). Only one of the three existing solid cavity expressions (1) for electron beam gives results which agree with this experimental finding. This expression, however, is subject to conceptual and other objections.