Blank Samples Research Articles

Administration study of recombinant erythropoietin on the carriers of variant c.577del in EPO gene.

The issue of misjudgment in recombinant erythropoietin (rEPO) detection caused by the variant c.577del in human EPO gene has been found in recent years. Though the method of analyzing de-N-glycosylated erythropoietins (EPO) in blood samples was developed for identifying both EPO_p.Arg193AspfsTer28 (VAR-EPO) and rEPO, it cannot be applied without the evaluation of excreted samples. For this purpose, five heterozygous carriers of the variant c.577del were recruited in an administration study of rEPO. Urine and blood samples were collected at different times before and after subcutaneous injection with a single-dose of 50 IU/kg. The urine samples were analyzed for intact EPO, while the serum samples were analyzed for both intact and de-N-glycosylated EPO. A typical mixed band was detected in all blank and wash-out urine samples, which all displayed a similar result with rEPO abuse. For the analysis of intact EPO in serum samples, a typical mixed band was detected in the wash-out samples from day 1 to day 3, which could be identified as rEPO directly, while double-band was observed in other samples with inconclusive results. The result of de-N-glycosylated EPO in all serum samples showed two separated bands, and the ratioL/U decreased along with wash-out periods. Also, compared with the intact EPO analysis, a longer detection window without false positive results was obtained when analyzing de-N-glycosylated EPO. Analysis of de-N-glycosylated EPO is not only able to recognize the variant carriers directly but also able to detect rEPO abuse in the blood samples from the variant carriers with higher efficiency than the analysis of intact EPO.

EIS and Amperometric Analysis of Gold Nanoparticle Probes on the Immunosensor Surface

[Introduction]Biosensing systems with integrated nanomaterials have revolutionized technological advancements in recent decades. Gold nanoparticles (AuNPs) in particular have been widely used in electrochemical sensors owing to their stability and unique characteristics. Previously, we developed biosensors that utilize the redox activity of AuNPs. Briefly, antibody-modified AuNPs not only hold secondary antibodies to react with antigens and primary antibodies on the electrode but also supply redox signals. We specially call this biosensing method Gold-Linked Electrochemical ImmunoAssay (GLEIA). In recent years, GLEIA has evolved uniquely in combination with other nanomaterials. However, information regarding the optimal electrochemical measurement conditions and the relationship between the electrode surface and AuNPs remain unknown. In this study, we quantitatively determined kinetic parameters such as the diffusion coefficient and electron transfer rate in the redox reaction of AuNPs on disposable screen-printed electrodes. Furthermore, the relationship between the addition of antibodies and the decrease in the determined parameters could be deduced. This is useful for the determination of the fine balance between the sensitivity and specificity.[Experimental]Electrochemical characteristics of AuNPs were performed using the following method, where 2 µL of AuNPs solution was dropped onto the working electrode and allowed to dry spontaneously. The number of AuNPs on each electrode was calculated from the datasheet (2.6 x 1010 particles/mL, O.D. 520 =1.0), and all nanoparticles were assumed to have dried on the working electrode. To characterize the reduction current, the AuNPs on the electrode underwent a pre-oxidation process, followed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) to evaluate the reduction current. The pre-oxidation condition was set at 1.2 V for 40 s, which was considered optimal for immunoassays. To evaluate the concentration response, 2 µL of the AuNPs solution was diluted with ultrapure water and poured and allowed to dry on the working electrode, pre-oxidized in 2 M KCl solution, and DPV measurements were performed. This experiment was also performed on an antibody-modified electrode, and the differences between the modified and unmodified electrodes were established. The same DPV measurements were performed using antibody-modified AuNPs (Ab-AuNPs).For immunoassay, IgA was reacted with a secondary antibody and incubated dropwise on an electrode. After washing, electrochemical measurements were performed[Results and Discussion]We investigated the influence of the DPV parameters and electrode surface conditions on a biosensor for the redox reaction of AuNPs. CV and classical theory were used to investigate the reduction kinetics of the AuNPs’ reduction after oxidation. The diffusion coefficient and electron transfer rate, which are related to sensor performance, were significantly reduced in the presence of antibodies and blocking agents on the electrode surface. This was due to the interaction between proteins and gold ions, and the effect of the electrode surface on sensitivity was evaluated using electrochemical reaction rates. Next, the influence of the biosensor on sensitivity was examined by focusing on the pulse amplitude of the DPV, and the increase in signal current coupled to increase in pulse amplitude was confirmed. The signal of AuNPs relative to the blank sample was of particular interest. Theoretically, changing the pulse potential above 100 mV does not change the current values obtained; however, in this study, a significant difference was observed between 150 mV and 100 mV. This was presumably due to the detection of nonspecific adsorption of antibodies that could not be detected under conventional conditions, suggesting the use of a more sensitive biosensor. This study provides evidence for fabrication of an IgA sensor with an improved Limit of detection (LOD) by optimizing pulse amplitude.Limits of detection (LOD) were obtained as 5.0 fmol/L (M) for AuNPs on a bare electrode, 0.1 pM for AuNPs on an antibody-modified electrodes, and 9.3 pM for AuNPs after immunoassay, allowing discussion of the given principle limits and actual biosensor performance (Figure). Under optimal conditions, the electrochemical biosensor achieved nearly two-fold signal amplification using a reduction current after AuNPs oxidation. These findings will allow the investigation of the kinetics of AuNPs on electrodes consisting of different materials to further elucidate the framework for improved sensitivity. Figure 1

Achieving high performances of lead-carbon battery with MnO2 positive additive

The development of the related negative additives renders the positive electrode as essential factor limiting the further upgrade of advanced lead-carbon battery. In this study, conductive manganese dioxide (MnO2) materials as functional additives were introduced into the positive electrode of lead-carbon batteries to boost the electrochemical activity. The effect of MnO2 additive on the substances conversion during curing and formation stages were investigated, also the specific capacity, rate and cycling durability. The results reveal that the MnO2 additive could accelerate the charge transfer in the positive electrode and promote the conversion kinetic between PbSO4/PbO2 phases. When the doping amount of MnO2 is 0.1 wt%, the modified lead-carbon batteries delivered an initial specific capacity of 60.74 mAh g−1, which was 24% higher than the blank sample. Besides, the lead-carbon batteries with MnO2 positive additive also display impressive rate capacity and excellent cycle stability, which could retain the capacity retention rate of 89.2 % after 150 cycles under 100 % DOD condition. The excellent performances could be attributed to the fact that MnO2 could facilitate the conversion within the positive active material, reduce the generation of large PbSO4 crystals, and remarkably enhance the utilization rate of positive active materials during the charging/discharging processes.

Enhanced ablation resistance of carbon/phenolic composites based on mesophase pitch reinforced particles

AbstractPhenolic resin (PR)‐based composites are the main materials used in thermal protection system (TPS) at present. However, the low graphitization degree of the char layer formed by PR easily leads to cracks and other defects. In this study, carbon/phenolic composites were modified by mesophase pitch (MP) to improve the structural strength, fracture toughness and crack propagation resistance. The ablation rate was significantly decreased after MP modification compared with the blank sample. With the increase of MP, the size of cracks and char blocks on the ablation center of the composites were reduced, and the surface was flat and dense. The Interlaminar shear strength (ILSS) of carbonized composites (5 wt% MP) were 9.79 MPa, and the flexural strength was 121.5 MPa, which improved 62.9% and 40.8% relative to the pure sample. The flexural strength of 5 wt% MP‐reinforced carbon/phenolic composites reached 525.6 MPa, which was 26.9% higher than that of pure carbon/phenolic composites, mainly due to the particle reinforcement effect of MP distributed between carbon fibers. The above results show that the carbon/phenolic composites modified by MP has great application prospects in the field of aircraft thermal protection.

High-strength, self-reinforcing and recyclable multifunctional lignin-based polyurethanes based on multi-level dynamic cross-linking

The preparation of lignin-based polyurethanes with excellent mechanical properties and recyclability remains extremely challenging because of the poor compatibility of lignin and matrix. Inspired by the multiple structures of spider silk and pearl layers, high-strength, heat-resistant and recyclable lignin-based polyurethanes (LPUs) were prepared by introducing weak hydrogen bonds, strong hydrogen bonds and dynamic silyl ether covalent bonds. Multiple hydrogen bonds provided a large energy dissipation mechanism. The covalent linkage between lignin and matrix promoted their compatibility and formed a robust cross-linking network. Depending on the multi-level dynamic interactions, the prepared elastomer exhibited a mechanical strength of 73 MPa, which was 1.9 times higher than that of the blank sample, with an initial thermal decomposition temperature of 310.5 °C and a good recyclability. Especially, the mechanical strength of LPUs was up to 99 MPa after mechanical training. In addition, the abundant conjugated structure of lignin endowed LPUs with an excellent photothermal conversion ability. Under the irradiation of NIR light with 4000 w m−2, the surface temperature increased to 95 °C within two minutes, exhibiting a stable photothermal performance even after 6 cycles. This work showed the application prospects of LPUs in the fields of high strength engineering materials and photo-induced actuators.

Analysis of the Impact of Rubber Recyclate Addition to the Matrix on the Strength Properties of Epoxy-Glass Composites.

Currently, there is a noticeable trend of modifying new materials by using additives from the recycling of harmful waste. This is to protect the environment by using waste to produce composites and at the same time to reduce the cost of their production. The article presents an analysis of the impact of the use of rubber recyclate obtained from the utilization of car tires as a sandwich layer of epoxy-glass composites and its impact on the strength parameters of the composite. The presented research is an extension of the previously conducted analyses on composite materials modified with the addition of rubber recyclate. The four variants of the materials produced contained the same percentage amount of rubber recyclate, but differed in the way it was distributed and the number of layers. Static tensile tests as well as impact strength and kinetics of damage to samples made with and without the addition of recyclate were carried out. Observation of the structures of the materials with the use of SEM was also performed. A significant influence of the method of distributing the recyclate in layers on the strength parameters of the materials was found. In the case of composites with three and two sandwich layers of recyclate, more favorable results were obtained compared to the blank sample. In addition, the values of the impact strength measurements were subjected to statistical analysis at the significance level of α = 95%. The distributions were tested for normality with the Shapiro-Wilk test, differences between pairs were tested with the Student's t-test for dependent groups, and ANOVA differences were tested for independent groups. Using the Student's t-test, it was confirmed that between the pairs of variables in the configurations reference sample and modified sample, there were significant statistical differences in the distribution of impact strength measurement results for all the analyzed materials. Statistical analysis showed a significant usefulness in the selection of the material with the best strength parameters and a significant role of statistical methods in the study of anisotropic materials.

Influence of crystal-transforming agent on the performance and mechanism of α-high-strength gypsum prepared from FGD gypsum

This paper investigates the impact of flue gas desulfurization (FGD) gypsum's crystal modifier on the characteristics and microcosmic mechanism of α-high strength gypsum. The results demonstrate that all three crystal modifiers can convert FGD gypsum to α-high-strength gypsum. Citric acid (CA) has the most significant influence on α-high-strength gypsum, and the prepared α-high-strength gypsum is short columnar, with an aspect ratio in the range of 1–3, and has a faster setting time, a larger specific surface area, and a smaller standard consistency, higher compressive strength, greater surface hardness, and smaller crystal particle size. The initial setting time of the α-high-strength gypsum manufactured with CA crystal modifier was decreased by 36% compared to the blank sample, the final setting time was lowered by 37.5%, and the water consumption of the standard consistency was reduced by 8%. The maximum strength is 32 MPa after 2 h, the absolute dry compressive strength is up to 38 MPa, and the surface hardness is improved by 24.43%.

Novel Phosphate Conversion Coating with Superior Corrosion Resistance on the Mg-Al-RE Alloy Based on the Introduction of Silane.

A novel chemical conversion method based on an aqueous electrolyte solution containing hydrolyzed silane as a crucial film-forming agent has been developed successfully. An organic/inorganic composite coating with superior corrosion protection was fabricated on the Mg-Al-RE alloy. The micro-morphology and chemical composition of the coating were examined using scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The prepared conversion coating possesses a double-layer structure, with a dense bottom layer and a loose outer layer containing microcracks. In addition, the anti-corrosion capacity of various samples was evaluated using salt spray, hydrogen evolution, and electrochemical tests. The analysis revealed that the samples converted by 3-aminopropyl triethoxysilane (APTES)-phosphate solution possessed a higher corrosion resistance. Compared to the blank sample, a 2 orders of magnitude reduction in icorr (6.678 × 10-7 A/cm2) and a 1.360 V improvement in Ecorr were observed. The MPCC-Si sample exhibited the lowest hydrogen evolution rate, indicating the best corrosion protection. Also, the rust grade could still reach 7 after 72 h of the neutral salt spray test.

The effect of training load stress on salivary cortisol concentrations, health parameters and hematological parameters in horses

The performance of sport horses is conditioned not only by the quality of its gene pool, but also by a large number of external factors. The most dominant being nutrition, quality of breeding, level of zootechnical care and the quality of the sports rider and coach. Important factor is the process of individuals’ adaptation to the training load occurring during the training itself. This study was focused on the analysis of salivary cortisol levels as well as hematological and biochemical blood parameters in relation to load to which the tested horses were subjected. In the study 14 horses of sport breeds were analyzed a all tested horses were in the same (medium) level of training load. Tested horses underwent following stages of workload – transportation, jumping training, parkour competition, treadmill training, riding training, shoeing and lunging of various intensity. Saliva samples were obtained using a tampon on a string which was inserted into horse's oral cavity, chewed by the horse and placed in a sterile tube with a closable lid. Afterwards, the samples were then stored in deep-freezing boxes at temperature of −80 °C. The EIA cortisol kit was used in this study. The absorbance was read at the wavelength of 450 nm against a reference wavelength of 620–630 nm or a blank sample. Blood samples were obtained at the beginning of the experiment, after half a year of running the experiment and at the end of the experiment from v. jugularis. Hematological analysis were carried out using automatic hematologic analyser and multiple parameters were observed. Analysis of biochemical parameters in blood serum were realized using commercial DiaSys kits and semiautomatic biochemical spectrophotometer. Sodium, potassium and chlorides were measured using automatic analyzer EasyLytePlus. In all monitored forms of exercise (transportation, jumping training, parkour competition, treadmill training, riding training, horse shoeing, lunging), an increase in cortisol concentrations immediately after the exercise was recorded, but only spotted statistically significant differences were found during the transportation of monitored horses. The levels of blood parameters were within the reference range during the experiment period. From a comprehensive evaluation of the results, it can be stated that there were no visible health changes to the horses that underwent the experimental load and that manipulation with horses is an important factor that has effect on horses’ stress response. In general, the results of this study show no visible impact of training and/or load on the health status of horses over entire 12-month duration of the experiment.

Development of machine learning techniques in corrosion inhibition evaluation of 5-methyl-1 H-benzotriazole on N80 steel in acidic media

In this study, three machine learning models of data analysis based on multiple linear regression (MLR), multiple nonlinear regression (MNR), and artificial neural network (ANN) has been proposed to model the behavior of 5methyl-1 H-benzotriazole (m-BTA) inhibitor on N80 steel in acidic media at different temperatures and inhibitor concentration. Based on experimental observation, the DC trend removal by Polynomial detrending revealed a suitable trend between electrochemical noise (ECN) measurement data and the results obtained from electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test at m-Factor equals to 3, 4, and 5. The inhibition efficiency (η) of 91% was achieved by using 0.001 M of m-BTA inhibitor. The corrosion rate will increase by increasing the temperature for the blank sample. Still, the m-BTA resulted in corrosion protection for N80 at high temperatures, and ECN resistance (Rn) increases with increased m-BTA concentration. The experimental tests revealed that temperature and m-factor are significant for corrosion inhibition of m-BTA; also, inhibitor concentration is an essential factor. Therefore, these three parameters were chosen as inputs for the Rn of the inhibitor. Removing unnecessary data from the original dataset causes relevant results compatible with experimental observations. The results of the reduced data set showed that R2 for the test of whole and reduced MLR model is 0.41 and 0.69, respectively, which shows that the reduced model is more suitable for modeling the training data than the whole model. The MNR model presents better accuracy than the MLR model, demonstrating that the relation between inputs and output does not follow a linear dependency. Several topologies of the ANN model were constructed, and the number of neurons was changed in one hidden layer. Finally, five neurons in the hidden layer with the Levenberg–Marquardt backpropagation (LMBP) algorithm were selected to develop the optimum ANN model, which has R2 and RMSE values of 0.99 and 17.41.

Determination of cyclic volatile methylsiloxanes in sludge samples collected from To Lich River, Hanoi, Vietnam

Cyclic volatile methylsiloxanes (cVMSs) are synthesis chemicals used widely in consumer products such as building materials, households, electrical and medical devices, and personal care products. Due to being used in many applications, cVMSs are released into various micro-environments. Recently, the pollution level of cVMSs in the environment including sewage sludge has been gradually concerned. In this work, four typical cVMSs: hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylhexasiloxane (D6) were measured in 20 sludge samples collected from a sewage river (To Lich River) in Ha Noi metropolitan by using the gas chromatography-tandem mass spectrometry (GC-MS) method. The method detection limits (MDLs) and the method qualification limits (MQLs) of cVMSs in sewage sludge were a range of (1.20-3.00) ng/g-dw (dry weight) and (3.60-9.00) ng/g-dw, respectively. Recoveries of the surrogate compound (tetrakis-(trimethyl siloxane)-silane: M4Q) in blank and real samples were from (89.4 to 112) % (RSD: 9.2 %). The total concentrations of cVMSs in sewage sludge samples from To Lich River ranged from (260 to 13,800) ng/g-dw. Among the studied cVMSs, D5 was found at the highest levels in a range of (150-6,040) ng/g-dw. To our knowledge, this is the first report on the occurrence of cVMSs in sewage sludge samples in Ha Noi as well as Vietnam. The results indicate that the distribution of cVMSs in environments is significantly high and further studies should be conducted.
 ® 2023 Journal of Science and Technology - NTTU

Using the poly-lactic acid as a fuel additive to enhance the physicochemical properties of aircraft jet fuel grade A1

The combustion quality and energy content of Jet fuel are important to fuel characteristics. There are some essential performance characteristics include density, flash point, freezing point, kinematic viscosity at -20o C, smoke point, and distillation temperatures should be detected and controlled. In this study, an experimental investigation was performed in order to determine the effects of polylactic acid, tetrahydrofuran, and Jet A1 fuel blends on the physical and chemical properties of blends. For this purpose, the fuel blends studied were analyzed using Miniscan IR which is a high speed for the comprehensive and automatic measurement of Jet fuels. From our results, it was found that the maximum flash point enhancement was obtained by S3 (95%Jet A1/5%THF/250ppmPLA) (42.3oC) while it was (38oC) for the blank Jet fuel A1. On the other hand, the decreasing of freezing point was achieved by S6 (95%Jet A1/5%THF/2500ppmPLA) (-65.4oC), while it was (-62.6oC) for the blank Jet fuel. The maximum net heat of combustion value was obtained by S2 (95%Jet A1/5%THF) (56.44 MJ/kg), while it was (55.62 MJ/kg) for the blank sample. Also, the density slightly increased for all Jet blended samples. The net heat of combustion values were enhancement, compared with blank Jet fuel A1.

The effect of hybrid SCMC (BYOD) on foreign language anxiety and learning experience in comparison to pure SCMC and FTF communication.

This study aims to investigate the impact of using synchronized computer-mediated communication (SCMC) in a face-to-face (FTF) classroom on reducing foreign language anxiety (FLA) and enhancing the learning experience. Fifty Chinese college students participated in a learning activity under three modes: normal FTF classroom (the blank sample), pure SCMC, and hybrid SCMC (BYOD). Smartphones, PCs, open internet, and the bring-your-own-device (BYOD) concept were used for SCMC applications. After completing the learning activity, the students completed Foreign Language Classroom Anxiety Scale (FLCAS) questionnaires. The students were also asked to complete perceptual questionnaires to assess their interaction, anxiety, distraction from the internet, and class atmosphere in the three modes. The results showed that the hybrid SCMC (BYOD) resulted in better interaction than the normal FTF classroom mode (the blank sample), while pure SCMC showed no significant improvement. Both SCMC modes reduced FLA compared to the normal FTF classroom mode (the blank sample), but pure SCMC caused a noticeable increase in distraction from the internet and weakened the classroom atmosphere. In contrast, the hybrid SCMC (BYOD) mode slightly increased distraction and improved the classroom atmosphere.

Liquid-liquid microextraction method using a deep eutectic solvent for the determination of total paraben content by fluorescence spectroscopy and second-order calibration

Concerns regarding the potential harm associated with endocrine dysfunction are increasing, particularly in children, due to the immaturity of their metabolic system and skin barrier. In this work, parabens, which are esters widely used as preservatives in cosmetics, were quantified in commercial samples of diaper rash cream. For this purpose, a green and efficient liquid–liquid microextraction (LLME) method was accomplished using a deep eutectic solvent (DES). To enhance recovery rates, the extraction parameters were optimized using a central composite design (CCD) on blank matrix samples spiked. The quantification was based on excitation-emission fluorescence spectroscopy, combined with parallel factor analysis (PARAFAC) decomposition, which proved be an advantageous tool to solve the overlap of uncalibrated constituents in the complex matrix. The PARAFAC modeling strategy provided satisfactory results within a linear range response of 100–1300 ng g−1, with LOD equal to 23 ng g−1. A validation set, with various proportions of methyl, ethyl, propyl, and butyl paraben standards, was used to validate the calibration model, resulting in root mean square error (RMSE) and relative error of prediction (REP) values of 32 ng g−1 and 4.5%, respectively. Moreover, acceptable root mean square error of prediction (RMSEP) and REP values (105 ng g−1 and 15%, respectively) were obtained, when a set of blank matrix samples spiked was applied. The proposed method was successfully applied to quantify total paraben content in commercial samples of diaper rash cream, yielding recoveries ranging from 83% to 125%. The method proved to be sensitive, accurate, and green, as it significantly reduced the consumption of organic solvents. Furthermore, it could serve as an alternative for the determination of preservatives in complex cosmetic samples.

Determination of fungicide residues in soil using QuEChERS coupled with LC-MS/MS, and environmental risk assessment.

Fungicide residues of soil samples taken from Batak Plain of Çanakkale province of Türkiye were assessed. Fungicide residue analyses were performed with the use of QuEChERS method and LC-MS/MS device. Blank samples were spiked at two different limit of quantification (LOQ) levels for method verification. Overall recovery was identified as 85.69% with an RSD of 12.36% (n=360; SD=10.59). A total of 110 soil samples were taken in November 2020. Present analyses revealed that 59.09% of samples contained fungicide residues at different concentrations. Propiconazole had the highest concentration (1736.06 μg/kg) in one sample, taken from the edge of the field where pesticide wastes were found and 26 fungicides were found at different concentrations in the same sample. Azoxystrobin was encountered in majority of the samples (29 samples). The most frequent fungicides were ordered as; boscalid and tebuconazole (22 samples) > metalaxyl (17 samples) > fluopyram (15 samples). Thirteen triazole fungicides were found in soil samples, mostly at moderately hazardous level (Class II). Risk assessments revealed that hazard levels of fungicides for adults and children were low with a hazard quotient (HQ) and hazard index (HI) of <1. Despite the safe nature of fungicides in soil samples, the greatest HQ values were identified for propiconazole (326.52E-08 for adults and 2449.00E-08 for children). The sum of hazard quotients for all fungicides was 86.31E-08 8 for adult and 647.35E-08 for children. In terms of soil pollution, it is important for farmers to apply fungicides with low HQ levels.

Assessment of levels and health risk of Potentially Toxic Elements (PTEs) in selected sachet water packaged from groundwater resources in Ogun State, Nigeria

BackgroundSachet water is a source of affordable drinking water for low-income socioeconomic class. However, contamination by potentially toxic elements (PTEs) could pose severe adverse health risk to consumers. ObjectiveThe present study aimed at assessing the levels and health risk of PTEs in selected sachet water samples packaged from groundwater resources in Ogun State, Nigeria. MethodsA total of 140 bags of selected sachet water brands were purchased and analysed for eleven PTEs (some of which are rarely reported in Nigeria) using inductively coupled plasma - optical emission spectrophotometer. Recovery experiment was conducted to validate the performance of the used analytical instrument. Blank samples were also run to cancel the matrix effect of the analysing reagents, and to calculate the limit of detection. PTE data were evaluated for simple descriptive and inferential statistics using SPSS for Windows. Health risk assessment was conducted for hazard quotient (HQ), hazard index (HI) and cancer risk (CR). ResultsChromium (Cr) was the highest observed PTE in sachet water from Asero (707±1102 µg L−1), Isolu (363±374 µg L−1) and Makun-Shagamu (359±204 µg L−1) sites. The concentrations of Cr were higher than the permissible limit of the World Health Organization in 63% of the sachet water samples. Furthermore, the average contents of lead (Pb) and thallium (Tl) were observed at higher concentrations than the acceptable limits. The HQs exceeding the permissible threshold of 1.0 were observed for silver (Ag), aluminium (Al), arsenic (As), cadmium (Cd), Cr and Tl in 29% of the sachet water consumed by adults and children; indicating adverse health effects. The CRs of Cd and Cr at all the sampling locations, and As at few sites were higher than the acceptable limit of 1 × 10−4; suggesting possible development of cancer by the consumers. ConclusionThe high levels and health risk estimates of PTEs in the sachet water samples suggested unsafe for consumption. Periodic monitoring of PTEs in sachet water from the study area is recommended.

Enhanced H2O2 Upcycling into Hydroxyl Radicals with GO/Ni:FeOOH-Coated Silicon Nanowire Photocatalysts for Wastewater Treatment.

There remains continued interest in improving the advanced water oxidation process [e.g., ultraviolet (UV)/hydrogen peroxide (H2O2)] for more efficient and environmentally friendly wastewater treatment. Here, we report the design, fabrication, and performance of graphene oxide (GO, on top)/nickel-doped iron oxyhydroxide (Ni:FeOOH, shell)/silicon nanowires (SiNWs, core) as a new multifunctional photocatalyst for the degradation of common pollutants like polystyrene and methylene blue through enhancing the hydroxyl radical (•OH) production rate of the UV/H2O2 system. The photocatalyst combines the advantages of a large surface area and light absorption characteristics of SiNWs with heterogeneous photo-Fenton active Ni:FeOOH and photocatalytically active/charge separator GO. In addition, the built-in electric field of GO/Ni:FeOOH/SiNWs facilitates the charge separation of electrons to GO and holes to Ni:FeOOH, thus boosting the photocatalytic performance. Our photocatalyst increases the •OH yield by 5.7 times compared with that of a blank H2O2 solution sample and also extends the light absorption spectrum to include visible light irradiation.

Watershed-scale assessment of environmental background values of soil potential toxic elements from the Caatinga and Atlantic forest ecotone in Brazil

The evaluation of the concentration of a potentially toxic element (PTE) in soils under native vegetation is the base study to obtain the quality reference values (QRVs), and the watershed is the strategic planning unit for decision making. The objective of this study was to determine the natural concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn and to establish QRVs for the Verruga river basin. Soils with no or minimal anthropic intervention from the surface layer (0.0–0.2 m) were collected and processed, and PTEs were extracted according to the USEPA 3051A method and determined by ICP‒OES. The quality of the analyses was checked by blank tests and soil samples certified SRM 2709 - San Joaquin Soil. The data set was subjected to exploratory analysis and multivariate statistics. The mean background concentrations of PTEs in soils showed high variability compared to other locations in Brazil and in the world and were (mg kg−1) Fe (24,300) > Mn (211.10) > Cr (40.98) > Zn (28.28) > Cu (10.68) > Ni (9.44) > Pb (4.95) > Co (4.08) > As (3.48) > Cd (0.09). The QRVs for the PTEs were established based on the 75th percentile, where (mg kg−1) Mn (124.59) > Cr (54.51) > Zn (31.66) > Cu (7.89) > Ni (7.20) > Pb (5.98) > As (4.05) > Co (3.40) > Cd (0.10). The chemical attributes and topography variation along the watershed are very heterogeneous and influence the dynamics of the PTEs. This survey will support future research on the impact of human activities on soil contamination in the watershed. This survey will support future research on environmental monitoring and the impacts caused by increased human activities on soil contamination in the Verruga river watershed, in the state of Bahia, Brazil.

A ratiometric fluorescent probe based on PIM-1 semiconducting polymer dots for turn-off-on sensing and bioimaging

Herein, we report a simple green platform based on a novel type of polymer dots (Pdots) as a sensitive and rapid “off-on” fluorescent probe for ratiometric Fe3+ and Cu2+ detection. The ratiometric probe has been designed using green-emitting PIM-1 Pdots and red-emitting PFTBT Pdots as detecting probes and internal stable standard probes, respectively. The dual-emission characteristics of PIM-1/PFTBT Pdots allowed us to apply ratiometric ion determination based on aggregation-caused quenching (ACQ) of PIM-1 Pdots at 490 nm, while the red emission intensity kept highly stable. The role of porosity and surface carboxylic groups of PIM-1 to achieve high sensitivity and selectivity using quantum-mechanical calculation and cellular imaging was successfully demonstrated so that the detection limit of 7.4 nM for Fe3+ and 14.8 nM for Cu2+ was obtained. The “on” process with excellent selectivity was realized by the introducing of glutathione (GSH) into PIM-1/PFTBT/Cu2+ and Cytochrome c (Cyt c) into PIM-1/PFTBT/Fe3+ with fluorescence recoveries of the blank sample 92 % and 91 %, respectively. The proposed strategy detects GSH and Cyt c with a good linearity ranging from 300 nM to 1800 nM and 10 nM to 120 nM by the limit of detection of 85.3 nM and 0.6 nM, respectively. This combinational off-on strategy provides a promising nanosensing platform for monitoring Fe3+ and Cu2+ in the environmental samples and introduces a sensitive probe with high biocompatibility for intracellular target imaging.

AMAnD: an automated metagenome anomaly detection methodology utilizing DeepSVDD neural networks.

The composition of metagenomic communities within the human body often reflects localized medical conditions such as upper respiratory diseases and gastrointestinal diseases. Fast and accurate computational tools to flag anomalous metagenomic samples from typical samples are desirable to understand different phenotypes, especially in contexts where repeated, long-duration temporal sampling is done. Here, we present Automated Metagenome Anomaly Detection (AMAnD), which utilizes two types of Deep Support Vector Data Description (DeepSVDD) models; one trained on taxonomic feature space output by the Pan-Genomics for Infectious Agents (PanGIA) taxonomy classifier and one trained on kmer frequency counts. AMAnD's semi-supervised one-class approach makes no assumptions about what an anomaly may look like, allowing the flagging of potentially novel anomaly types. Three diverse datasets are profiled. The first dataset is hosted on the National Center for Biotechnology Information's (NCBI) Sequence Read Archive (SRA) and contains nasopharyngeal swabs from healthy and COVID-19-positive patients. The second dataset is also hosted on SRA and contains gut microbiome samples from normal controls and from patients with slow transit constipation (STC). AMAnD can learn a typical healthy nasopharyngeal or gut microbiome profile and reliably flag the anomalous COVID+ or STC samples in both feature spaces. The final dataset is a synthetic metagenome created by the Critical Assessment of Metagenome Annotation Simulator (CAMISIM). A control dataset of 50 well-characterized organisms was submitted to CAMISIM to generate 100 synthetic control class samples. The experimental conditions included 12 different spiked-in contaminants that are taxonomically similar to organisms present in the laboratory blank sample ranging from one strain tree branch taxonomic distance away to one family tree branch taxonomic distance away. This experiment was repeated in triplicate at three different coverage levels to probe the dependence on sample coverage. AMAnD was again able to flag the contaminant inserts as anomalous. AMAnD's assumption-free flagging of metagenomic anomalies, the real-time model training update potential of the deep learning approach, and the strong performance even with lightweight models of low sample cardinality would make AMAnD well-suited to a wide array of applied metagenomics biosurveillance use-cases, from environmental to clinical utility.