Optimal Test Conditions Research Articles

Development of an Improved Sulfur-Oxidizing Bacteria-Based Ecotoxicity Test for Simple and Rapid On-Site Application.

Microbial toxicity tests are considered efficient screening tools for the assessment of water contamination. The objective of this study was to develop a sulfur-oxidizing bacteria (SOB)-based ecotoxicity test with high sensitivity and reproducibility for simple and rapid on-site application. To attain this goal, we developed a 25 mL vial-based toxicity kit and improved our earlier SOB toxicity test technique. The current study applied a suspended form of SOB and shortened the processing time to 30 min. Moreover, we optimized the test conditions of the SOB toxicity kit in terms of initial cell density, incubating temperature, and mixing intensity during incubation. We determined that 2 × 105 cells/mL initial cell density, 32 °C incubating temperature, and 120 rpm mixing intensity are the optimal test conditions. Using these test conditions, we performed SOB toxicity tests for heavy metals and petrochemicals, and obtained better detection sensitivity and test reproducibility, compared to earlier SOB tests. Our SOB toxicity kit tests have numerous advantages, including a straightforward test protocol, no requirement of sophisticated laboratory equipment, and no distortion of test results from false readings of end-points and properties of test samples, making it suitable for simple and rapid on-site application.

Catalytic CO2 Methanation: Providing Optimal Test Conditions for Kinetic Investigations

AbstractIn the context of using renewable energies and recycling climate‐changing gases, methanation of CO2 provides one possibility. However, volatile availability of renewable energies for hydrogen production and fluctuating CO2 streams from different sources lead to enhanced demand in investigating the influence of dynamic process operation on the catalyst performance, including detailed kinetic characterization. Reliable kinetic measurements require isothermal temperature control and absence of macrokinetic diffusion limitations. Both were investigated in this work while the determination of steady‐state kinetic parameters is part of ongoing studies. Furthermore, a detailed analysis with respect to the long‐term‐stability of the nickel‐based catalyst was performed.

Simultaneous ion fractionation and concentration by selectrodialysis for saline wastewater valorization

In order to desalinate saline wastewater and achieve energy-efficient recovery of mixed salt (Na2SO4 and NaCl), selectrodialysis (SED) stack with commercial monovalent selective anion exchange membranes (MVA) was utilized in this work. The experiments proved that the final concentration and purity of Na2SO4 in Product could reach 0.84 mol·L−1 and 94.9%, respectively, under the optimal testing conditions (initial concentration of Product solution was 15 wt.% NaCl and the current density of 200 A·m−2). Simultaneously, the concentration and purity of NaCl in Brine achieved 1.90 mol·L−1 and 97.1%, respectively. In order to guide the engineering application, a formula was established to predict the termination time of SED process according to the applied current density. Furthermore, glycerol retention rate of the SED stack in Feed solution could reach more than 95%. And low energy consumption on Na2SO4 and NaCl fractionation/concentration by 0.13–0.15 kWh·kg−1 at 200 A·m−2. Hence, this work illustrated the techno-economic feasibility of using SED for saline wastewater valorization.

Simultaneous removal of SO2, NO and Hg0 using porous carbon/heat-coactivated persulfate system

A novel simultaneous removal technique of SO2, NO, and Hg0 using porous carbon/heat-coactivated persulfate (PS) system was proposed. A series of experiments and theoretical analysis were conducted to explore simultaneous removal process of Hg0, SO2, and NO. Study demonstrates that the developed porous carbon/heat-coactivated PS system gains larger free radical yield and higher pollutants simultaneous removal efficiency than other comparison systems, which are associated with the synergism between porous carbon and heat. High temperature plays a vital role in this co-activation system. Both SO4−· and ·OH play an important role in NO and Hg0 removal, but ·OH is more important for NO removal while SO4−· is more important for Hg0 removal. Both NO and Hg0 removal processes meet pseudo-first-order rapid reaction kinetics, and their removal processes are controlled by mass transfer. Removal efficiencies of NO and Hg0 are increased first and then are decreased with increasing PS concentration, temperature and porous carbon concentration. Increasing pH and concentrations of SO2, NO and Hg0 reduce the NO and Hg0 removal efficiencies. The highest simultaneous removal efficiency of Hg0, SO2, and NO is up to 98.4% for Hg0, 100% for SO2, and 89.3% for NO under an optimized test condition.

Optimization of test condition on DL-EPR test for AL-6XN superaustenitic stainless steel using Taguchi method

The DL-EPR is a reliable technique to evaluate the degree of sensitization (DOS) of stainless steel. This paper proposed an optimal test condition for AL-6XN super-austenitic stainless steel using the Taguchi method. The factors are H2SO4, NaCl, KSCN concentration, and temperature. DL-EPR test was conducted with the L16 orthogonal array (4 levels and 4 factors). The significant factors were NaCl concentration and H2SO4 concentration, but the KSCN concentration and temperature had a relatively low influence, and the optimal condition was found to be 2 M H2SO4, 0.1 M KSCN, 2 M NaCl, and 30 °C. Statistical analysis and regression model were used as validation for optimal test condition.

Investigation on intergranular corrosion susceptibility of a nitrogen-containing austenitic stainless steel QN2109 by optimized DL-EPR tests

PurposeThe purpose of this study is to investigate the intergranular corrosion (IGC) susceptibility of a nitrogen-containing austenitic stainless steel QN2109. The intergranular corrosion (IGC) susceptibility of a nitrogen-containing austenitic stainless steel QN2109 was investigated.Design/methodology/approachThe double-loop electrochemical potentiodynamic reactivation (DL-EPR) tests were carried out. Scanning electron microscopy and atomic force microscopy were used to characterize the microstructure.FindingsThe optimized test condition for QN2109 was 1 M H2SO4 + 0.01 M NH4SCN at 40°C. The nose temperature of the temperature–time–sensitization (TTS) curve of QN2109 plot was approximately 750°C. Moreover, the IGC susceptibility started to appear at approximately 120 min. The Cr-depletion zone of QN2109 was generated by the formation of M23C6 rather than by the addition of nitrogen. The depth–width ratio of the grain boundaries after the DL-EPR tests decreased as the aging temperature increased. The degree of Cr depletion and size of the Cr-depletion zone at the grain boundary were reflected by the degree of sensitization and depth–width ratio, respectively.Originality/valueThe optimized test condition for DL-EPR tests of a nitrogen-containing austenitic stainless steel QN2109 was investigated. The TTS curve of QN2109 was first plotted to avoid IGC failure. The morphology of the Cr-depletion zone was reflected by the depth–width ratio.

Extraction of Ursolic Acid from Apple Peel with Hydrophobic Deep Eutectic Solvents: Comparison between Response Surface Methodology and Artificial Neural Networks.

Extracting ursolic acid (UA) from plant resources using organic solvents is incompatible with food applications. To address this, in this study, 15 edible hydrophobic deep eutectic solvents (HDESs) were prepared to extract UA from apple peel, the extraction conditions were optimized, and the optimization strategies were compared. It was found that the solubility of UA in the HDESs can be 9 times higher than the traditional solvent such as ethanol. The response surface optimization concluded that temperature had the greatest effect on the extraction and the optimized test conditions obtained as follows: temperature of 49 °C, time of 32 min, solid-liquid ratio of 1:16.5 g/mL, respectively. Comparing the response surface methodology (RSM) and artificial neural networks (ANN), it was concluded that ANN has more accurate prediction ability than RSM. Overall, the HDESs are more effective and environmentally friendly than conventional organic solvents to extract UA. The results of this study will facilitate the further exploration of HDES in various food and pharmaceutical applications.

Optimization of HS-SPME-GC-MS for the Determination of Volatile Flavor Compounds in Ningxiang Pork.

This study attempts to explore the suitable conditions for the detection of volatile flavor compounds (VFCs) in Ningxiang pork by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Ningxiang pigs were harvested from a slaughterhouse and a longissimus dorsi sample was collected from each animal. The VFCs of Ningxiang pork can be strongly impacted by the detection conditions (columns, weight of meat samples, heat treatment time, equilibrium conditions, and extraction conditions) that need to be optimized. Our results also provided the optimal test conditions: weighing 5 g of meat samples, grinding for 30 s in a homogenizer, heat treatment at 100 °C for 30 min, equilibration at 70 °C for 30 min, and extraction at 100 °C for 50 min. Furthermore, the feasibility and representativeness of the test method were confirmed based on principal component analysis and a comparison of the three pork VFCs. These findings offer researchers a unified and efficient pretreatment strategy to research pork VFCs.

Spit or Swab? The Diagnostic Accuracy of Saliva-Based Testing as a Sars-Cov-2 Surveillance Tool

Background. Nasopharyngeal swab/oropharyngeal swab (NPS/OPS) qRT-PCR is the gold standard for detecting SARS-CoV-2. However, it has its own limitations including cost and invasiveness. As an alternative, individual qRT-PCR testing of saliva samples was validated and shown to be comparable in sensitivity and specificity with NP-OP qRT-PCR. To further maximize its utility, the researchers wish to explore antigen and pooled testing methods. Objective. The study aimed to evaluate the diagnostic accuracy of detecting SARS-CoV-2 infection using saliva-based pooled qRT-PCR and rapid antigen test compared with individual saliva qRT-PCR. Methodology. In this retrospective cross-sectional study, saliva specimen from individuals aged 18 years old and above from the outpatient specimen collection station at the Philippine Children’s Medical Center were tested individually using qRT-PCR (Mag-bind RNA Extraction Kit/MACURA, Allsheng Extraction Machine, Sansure PCR kit, and MA-600 Sansure Biotech). Non-probability convenience sampling was utilized. Based on the individual results, pools of five (5) individual specimens, which includes one (1) positive sample were tested with qRT-PCR for sensitivity. DNK-2150-1S Dynamiker SARS-CoV-2 Ag Rapid Test (Dynamiker Biotechnology Co., Ltd., Tianjin, China) was also used to test individual saliva specimens. . Out of 196 individual saliva specimens, 73 were detected to have SARS-COV-2 by qRT-PCR, while the remaining 123 were negative. Compared with the individual saliva qRT-PCR, rapid antigen tests done showed sensitivity of 46.58% (95% CI 35.13%, 58.02%), specificity of 86.18% (95% CI 80.08%, 92.28%), positive and negative predictive value of 66.67% (95% CI 53.71%, 79.60%) and 73.10% (95% CI 65.89%, 80.32%) respectively. Based on the results of individual saliva-based qRT-PCR, 62 pools were tested and showed sensitivity of 98.39% (95% CI 91.34%, 99.96%). Conclusion and Recommendation. Pooled saliva-based testing for SARS-CoV-2 is comparable with individual saliva-based rapid antigen testing. The use of rapid antigen testing is less sensitive and less specific compared with qRT-PCR consistent with prior reports. Additional studies are recommended to determine optimal conditions for testing.

Development of an indirect ELISA using a novel linear epitope at the C-terminal region of the VP2 protein to specifically detect antibodies against Senecavirus A

BackgroundSenecavirus A (SVA) is a pathogen that has recently caused porcine idiopathic vesicular disease (PIVD). The clinical signs are similar to those of foot-and-mouth disease, porcine vesicular disease, and vesicular stomatitis. Therefore, identification of SVA as a cause of PIVD is important to eliminate this emerging pathogen.MethodsIn this study, an indirect ELISA based on the VP2 epitope (VP2-epitp-ELISA) was developed to detect antibodies directed against SVA.ResultsA novel linear epitope (271GLRNRFTTGTDEEQ284) was first identified at the C-terminus of the VP2 protein by epitope mapping. The diagnostic performance of VP2-epitp-ELISA was estimated by testing a panel of known background sera from swine. Under the optimum test conditions, when the cutoff value was 37%, the diagnostic sensitivity (Dn) and diagnostic specificity (Dp) of the assay were 91.13% and 91.17%, respectively. The accuracy of VP2-epitp-ELISA was validated and further compared with that of commercial diagnostic kits. The diagnostic results showed that VP2-epitp-ELISA did not cross-react with serum positive for other idiopathic vesicular diseases and had a concordance rate of 90.41% with the Swinecheck® SVA bELISA.ConclusionsThese results indicate that VP2-epitp-ELISA is suitable for specific detection of antibodies against SVA in swine.

Highly selective molecularly imprinted gel-based electrochemical sensor with CuS@COOH-MWCNTs signal amplification for simultaneous detection of vanillin and tartrazine in foods

Herein, we report the successful development of a highly selective molecularly imprinted gel (MIG)-based electrochemical sensor for the simultaneous detection of vanillin (VAN) and tartrazine (TZ) in foods. A glassy carbon electrode (GCE) was first modified with conductive CuS@COOH-MWCNTs, after which the obtained CuS@COOH-MWCNTs/GCE was further functionalized by deposition of a molecularly imprinted chitosan-based gel crosslinked and stabilized using benzidine. The MIG allowed specific recognition of VAN and TZ, whilst the CuS@COOH-MWCNTs component was used for signal amplification. Under optimized testing conditions, the developed MIG-CuS@COOH-MWCNTs/GCE sensor allowed simultaneous detection of VAN and TZ, showing a linear response over the concentration range 0.03–125 μM. Limits of detection were 0.006 μM and 0.005 μM, respectively. Analysis of liqueur and white vinegar samples spiked with VAN and TZ using the developed sensor afforded excellent recoveries (92.2%−109.7%). Further, the sensor was successfully applied to analyze the content of VAN and TZ in two kinds of vanilla ice cream, with results consistent with analyses performed using a national standard method.

Dendritic Silica Nanospheres with Au–Pt Nanoparticles as Nanozymes for Label-Free Colorimetric Hg2+ Detection

Mercury ion (Hg2+) is toxic and can severely damage the environment and human health. Therefore, sensitive and selective Hg2+ detection methods are needed. Here, we synthesized dendritic silica nanospheres (DSN) with central-radial porous structures and immobilized Au and Pt nanoparticles into their pores. The synthesized DSN with Au and Pt nanoparticles (AuPt@DSN) exhibited superior peroxidase-like activity, stability, and dispersibility. We found that AuPt@DSN can specifically reduce Hg2+, leading to the decreased catalytic activity of the nanozymes. Under optimal testing conditions, the AuPt@DSN material was efficiently used for the visual detection of Hg2+. The detection limit was 8.58 pM with a linear range from 0.1 nM to 10 μM. Selectivity toward Hg2+ has also been demonstrated in aqueous solutions in the presence of other metal ions. This strategy is simple to utilize and has a low cost and rapid response. The practicability was further investigated by analyzing complex water samples, which suggests its potential for mercury evaluation in environmental samples.

Effects of antifouling compounds on the growth of macroalgae Undaria pinnatifida

Seaweeds are some of the principal primary producers of marine environments, and they are important ecological elements of coastal ecosystems. The effects of harmful chemicals on seaweeds may adversely affect coastal ecosystems, hence we aimed to develop a new phytotoxicity test using the gametophytes of a common temperate kelp species, Undaria pinnatifida (KU-1630), for the widely used antifouling chemical substances Cybutryne, Diuron, Cu2+, and Zn2+. Toxicity to gametophytes of U. pinnatifida was assessed by comparing the relative growth rate (RGR) at the logarithmic growth phase. Fragmentation method, initial algal biomass, photon irradiance, and adhesive period were investigated for developing optimal test conditions. Cybutryne exposure tests were performed with seven replicates and control, the RGR ranging from 0.17 to 0.19, while mean 7-day EC50 and no observed effect concentration (NOEC) were 5.1 μg/L and 1.8 μg/L, respectively. The 7-day EC50 for other antifoulants was 14 μg/L for Diuron, 17 μg/L for Cu2+, and 1500 μg/L for Zn2+. This test method demonstrated high sensitivity and reproducibility, and it may be added to the routine methods used for toxicity evaluation of hazardous chemicals.

Recovery of carbon and cryolite from spent carbon anode slag of electrolytic aluminum by flotation based on the evaluation of selectivity index.

One of the main electrolytic aluminum production costs is the consumption of carbon anodes, and carbon anode slag is a common hazardous waste in the aluminum industry. In this work, electrolytic aluminum carbon anode slag was separated by flotation. Using the selectivity index (SI) as an indicator, the influencing factors of the carbon slag flotation process were optimized, and the separation performance of carbon and cryolite in the carbon anode slag was investigated. The raw carbon anode slag was ground for 40 min to achieve dissociation of the cryolite from the carbon, the optimized SI value was then used to determine the optimal flotation test conditions. The test results showed that the SI value under the optimal grinding flotation was approximately four times larger than the value of direct flotation. This indicated that carbon anode slag had a better flotation selectivity under the grinding flotation, which significantly improved the flotation performance.

Study on the catalytic degradation of Acid Orange 7 and the potential mechanism by ferrous-percarbonate.

Factors affecting the degradation of Acid Orange 7 (AO7) were evaluated and optimized when ferrous was used to catalyze percarbonate in the present study. The optimized conditions included the initial pH values ranging from 3 to 11 for AO7 solution, the initial level of AO7, sodium percarbonate (SPC), and Fe2+ . Some ions and natural organic materials, which commonly exist in natural water, were also tested to evaluate their potential impacts on the degradation of AO7. The degradation efficiency of AO7 was up to 95% under the optimized test conditions, where the ferrous/percarbonate/AO7 molar ratio was 15/10/1 in the 0.285 mmol/l AO7 aqueous solution. The presence of Cl- , SO4 2- , NO3 - , Na+ , and Mg2+ did not affect the removal of AO7. The addition of HCO3 - significantly inhibited its removal, even when the concentration of HCO3 - was low to 0.6mmol/l. A slight inhibition effect was observed when the added concentration of humic acid ranged from 0.5 to 5mg/l, whereas the residue of AO7 was significantly enhanced when the level of humic acid was continually increased from 50 to 100 mg/l. Hydroxyl radicals (•OH) were the main reactive intermediates controlling the oxidation of AO7 in the present Fe2+ /SPC system. The produced intermediates through the degradation of AO7 were identified to include 2-coumaranone, 2-naphthol, phthalic acid, phthalimide, N-methylnaphthylamine, and 2-methylphenol. The proposed degradation pathways are consistent with the radical formation and the identified intermediates. PRACTITIONER POINTS: The ferrous/percarbonate system can remove 95% of AO7 under the optimized conditions. AO7 removal was inhibited by adding HCO3 - and humic acid, but not affected by Cl- , SO4 2- , NO3 - , Na+ , and Mg2+ . Hydroxylation, ring opening, and mineralization driven by the generated hydroxyl radicals were derived as the major processes for degrading AO7.

Investigation of Fly ash Polymer Composite of Fly ash Polymer Composite

Abstract: Industrial waste like fly-ash which is creating environmental problems, is mainly used as a buildingmaterial due to its low cost and easy availability. But the main disadvantage of these bricks is its low strength. So, a lot of research is going on to increase the strength of these bricks. The presentresearch work is carried out to develop a new systematic procedure to produce fly ash composite bricks which will have higher compressive strength. Here the fly-ash is mixed with Cold setting resin at different proportions and water treated at different temperatures to find out a solution to the brick industry. The compressive strength, Hardness, water absorption, Density and thermal conductivity of the fly ash-resin powder bricks obtained under optimum test conditions are 11.24MPa, 47.37HV, 19.09% 1.68 g/cm3, and 0.055 W/mK respectively. The sliding wear behavior is also investigated. The structure-property correlation of these composites is studied using X-ray diffraction, FTIR analysis and scanning electron microscopy

Effective Optical Image Assessment of Cellulose Paper Immunostrips for Blood Typing.

Novel high-performance biosensing devices, based on a microporous cellulose matrix, have been of great interest due to their high sensitivity, low cost, and simple operation. Herein, we report on the design and testing of portable paper-based immunostrips (IMS) for in-field blood typing in emergencies requiring blood transfusion. Cellulose fibrils of a paper membrane were functionalized with antibodies via supramolecular interactions. The formation of hydrogen bonds between IgM pentamer and cellulose fibers was corroborated using quantum mechanical calculations with a model cellulose chain and a representative amino acid sequence. In the proposed immunostrips, paper with a pore size of 3 µm dia. was used to enable functionalization of its channels with antibody molecules while blocking the red blood cells (RBC) from channel entering. Under the optimized test conditions, all blood types of AB0 and Rh system could be determined by naked eye examination, requiring only a small blood sample (3.5 µL). The durability of IgM immunostrips against storing has been tested. A new method of statistical evaluation of digitized blood agglutination images, compatible with a clinical five-level system, has been proposed. Critical parameters of the agglutination process have been established to enable future development of automatic blood typing with machine vision and digital data processing.

A Study on the Capacity Degradation in Na3.2V1.8Zn0.2(PO4)3 Cathode and Hard Carbon Anode Based Sodium-Ion Cells

In this manuscript, the impact of operating conditions such as voltage window, and operating temperature on electrochemical performance and cycle life of Zn-substituted Na3.2V1.8Zn0.2(PO4)3 (NVZP) vs hard carbon (HC) coin cells filled with 1 mol dm−3 NaBF4 in tetraglyme is presented. Initially, the cells are cycled for 500 times at C/2 charge and 1 C discharge in three different voltage windows (4.20–1.00 V, 4.05–1.00 V and 4.05–1.50 V) and at two temperatures (28 °C and 40 °C) and are subjected to periodic internal resistance and impedance measurements. The elemental composition of the electrodes harvested after cycling reveals that vanadium dissolution with accompanying deposition on the HC electrode and irreversible loss of sodium causes increased cell impedance. The identified degradation mechanisms, which causes severe capacity fade, are found to be accelerated in the cells cycled over wider voltage windows, particularly at elevated temperature. The best cycling performance and lowest impedance are recorded for the cells cycled within 4.05–1.50 V at 28 °C owing to negligible vanadium dissolution. Under these optimized testing conditions, a prototype 18650 cell, shows impressive capacity retention of 77% after 1000 cycles.

Optimization of an rGO-based biosensor for the sensitive detection of bovine serum albumin: Effect of electric field on detection capability.

Despite significant progress in the field of biosensing, the impact of electric field on biosensor detection capability and the feasibility of the biosensor application in wastewater has yet to be investigated. The objective of this study was to develop a low-cost, highly sensitive, and selective reduced graphene oxide (rGO)-based biosensor. The constructed biosensor consists of an in-house prepared GO and a four-terminal Kelvin sensing. Spin-coating was chosen as the deposition technique and results revealed an optimal GO number of layers and concentration of 7 and 2mg/mL, respectively. Experiments to determine the effects of electric field on the performance of the biosensor showed significant changes in the biosensor surface, also presenting a direct impact on the biosensor functionality, such that the biosensor showed an increase in limit of detection (LOD) from 1 to 106fg/mL when the applied voltage was increased from 0.0008 to 0.2V. Furthermore, this study successfully explores a pilot scale setup, mimicking wastewater flow through sewage pipelines. The demonstrated improvements in the detection capability and sensitivity of this biosensor at optimized testing conditions make it a promising candidate for further development and deployment for the detection of protein analytes present at very low concentrations in aqueous solutions. In addition, the application of this biosensor could be extended to the detection of protein analytes of interest (such as the spike protein of SARS-CoV-2) in much more complex solutions, like wastewater.

Intelligent Iterative Experimental Design to Achieve Maximum Model Quality for Phase Change of 22MnB5

Conducting experiments for material modeling is very costly and time-consuming when many parameters are involved, resulting in a large number of test conditions. Therefore, it is expedient to develop algorithms for the iterative identification of optimal test conditions. This method should allow the model to learn automatically so that only a small number of test conditions are selected at the beginning of the model calibration. In order to decide whether further experiments should be carried out and which test conditions need to be investigated, meta-models are generated, and the expected gain score is calculated. The next sample is selected based on the highest score, and this procedure continues until the material models meet a termination criteria. The result from the study shows that the implemented method uses 12 test conditions to generate a phase transformation model for 22MnB5 steel. The material models fitted with the proposed method provide acceptable predictions when compared with experimental data.