Increasing Exposure Time Research Articles

Ion bombardment effect on properties of MoOx thin film under different PEALD plasma exposure time

Molybdenum oxide (MoO x ) films have been prepared by using Mo(CO) 6 precursor and remote oxygen plasma reactant via plasma enhanced atomic layer deposition (PEALD) system. The influence of plasma exposure time on the optical, structural, morphological and chemical composition characteristics of the MoO x thin films have been elaborated systematically. The results show that both the plasma oxidizing reaction and ion bombardment effect exist during the films' deposition. Three kinds of different precursor deposition mechanisms of PEALD-MoO x thin films have been proposed firstly and analyzed in detail under different plasma duration, namely unsaturated reaction, saturated reaction and ion bombardment effect. The film growth rate increased with the increment of plasma exposure time and reached a maximum value at 28 s, which manifested the film growth dominated by the plasma oxidizing reaction in this stage and the transformation from unsaturated reaction to saturated reaction. As the further increase of plasma exposure time from 33 to 38 s, the ion bombardment effect couldn't be ignored and led to the formation of more oxygen vacancy defects along with the decrease of refractive index and growth rate. The clarification of the balance mechanism between oxygen radicals' supply and ion bombardment damage is very important for the achievement of high quality MoO x films. • The effect of plasma exposure time on properties of MoO x film has been explored. • Both oxidizing reaction and ion bombardment effect exist during films'deposition. • Three kinds of precursor deposition mechanism have been proposed firstly.

Tuning the structure, optical, and magnetic properties of nanostructured NiMoO4 by nitrogen plasma treatment

Herein, the nitrogen plasma treatment with different time irradiation (0, 90, 120, and 150 min) is used to tune the structure, optical, and magnetic properties of nanostructured NiMoO4 NMO NPs. The XRD patterns revealed that the crystallinity of NMO samples increases with an increase in the N2 plasma exposure time. The notable reduce in this peak’ intensity for the sample at dose of 120 min may be attributed to the energy dissipated in the defect generation. Also, the crystallite size for NMO samples was found in the range (23.9–26.7) nm. Further, EPR is used to evaluate the impact of the treatment duration on the oxygen vacancy density. The total number of spins rises as plasma irradiation duration increases, revealing that the NMO NPs can be used as a dosimeter for plasma irradiation. The optical bandgap ranged from 2.92 eV to 3.24 eV as the N2 plasma treatment duration changed. The saturation magnetization was enhanced with the rise of plasma treatment time. Furthermore, the Hc increases from 16.67 G for untreated NMO NPs to 128.41 G for N2 plasma-treated NMO NPs for 150 min. The resulted optical and magnetic properties of N2 plasma-treated NMO NPs make it candidate material for photocatalysis applications.

Durability of coral aggregate concrete under coupling action of sulfate, chloride and drying-wetting cycles

This paper investigates the deterioration progress of coral aggregate concrete (CAC) under the coupling action of sulfate, chloride and drying–wetting cycles. Three strength grades (C25, C30, C40) of CAC specimens were designed for experimental analysis. In addition, ordinary aggregate concrete (OAC) specimens were prepared as the reference group. The relative dynamic elastic modulus and the relative compressive strength of CAC increases first and then decreases with increasing exposure time, while the mass loss rate shows the opposite trend. The CAC with high strength grade has strong corrosion resistance, and the corrosion resistance of CAC is obviously lower compared to OAC at same strength grade. The addition of basalt fiber into CAC can delay the cracking and maintain the integrity. With increasing exposure time, the damage depth increases exponentially. The chloride concentration can be divided into two phases: first increase and then decrease. Basalt fiber can significantly reduce the chloride diffusion coefficient of CAC. The erosion products are ettringite and gypsum for OAC and CAC; in addition, Friedel’s salt is also found in CAC.

Effect of short-term exposure to low concentration of tebuconazole: morphological, histometric and functional modifications in Danio rerio liver

Due to its high toxicity and bioaccumulation tendency, tebuconazole (TBZ) is one of the ten substances posing the highest risk of harmful effects in aquatic ecosystems. The liver, a key compartment for xenobiotics detoxification, is also the organ in which TBZ mainly accumulates in fish. Herein, we investigated for the first time the morpho-functional changes induced in zebrafish (Danio rerio) liver after a short-term exposure (48, 96, and 192 hours) to a low, environmentally relevant concentration of TBZ (5 µg/L) to disclose the early effects under a realistic exposure scenario. We revealed that pathological alterations with varying degrees of severity could be detected in all the examined samples. The injuries become intense and irreversible with increased exposure time involving both hepatocytes and vascular components based on the degree of tissue changes. The main morphological alterations were: parenchyma dyschromia, macrophages infiltration, congestion of blood vessels, and sinusoids. TBZ exposure also resulted in a significant decrease in glycogen contents and hepatocyte dimensions, and the modulation of superoxide dismutase, an early indicator of oxidative stress. We demonstrated that even a very low dose of TBZ affects hepatic morphology and function, disrupting liver homeostasis and physiology.

Thermal stability of CVI and MI SiC/SiC composites with Hi-Nicalon™-S fibers

The influence of high-temperature argon heat-treatment on the microstructure and room- temperature in-plane tensile properties of 2D woven CVI and 2D unidirectional MI SiC/SiC composites with Hi-Nicalon™-S SiC fibers was investigated. The 2D woven CVI SiC/SiC composites were heat-treated between 1200 and 1600 °C for 1- and 100-hr, and the 2D unidirectional MI SiC/SiC composites between 1315 and 1400 °C for up to 2000 hr. In addition, the influence of temperature on fast fracture tensile strengths of these composites was also measured in air. Both composites exhibited different degradation behaviors. In 2D woven CVI SiC/SiC composites, the CVI BN interface coating reacted with Hi-Nicalon™-S SiC fibers causing a loss in fast fracture ultimate tensile strengths between 1200 and 1600 °C as well as after 100-hr isothermal heat treatment at temperatures > 1100 °C. In contrast, 2D unidirectional MI SiC/SiC composites showed no significant loss in in-plane tensile properties after the fast fracture tensile tests at 1315 °C. However, after isothermal exposure conditions from 1315° to 1400°C, the in-plane proportional limit stress decreased, and the ultimate tensile fracture strain increased with an increase in exposure time. The mechanisms of strength degradation in both composites are discussed.

Efficacy of microwave irradiation in enhancing the shelf life of groundnut (Arachis hypogaea L.)

This study aimed to investigate the effect of microwave irradiation on quality attributes of groundnut (Arachis hypogaea L.) during the storage period of four months. In this experiment, the groundnut seeds of Devi variety (ICGV-91114) were exposed to power density levels (3 and 5 W/g) and treatment time (60 and 90 s) maintaining the initial moisture content (IMC) at 5 ± 0.1 and 7 ± 0.1% db in packaging materials of low-density polyethylene (LDPE) and polypropylene (PP). With the increase in power level and exposure time, the moisture content and germination percentage were found to decrease. Groundnut kernels at IMC 5% showed lower infestation and samples treated with 3 W/g for 90 s showed a higher percentage of oil yield. The samples treated with 3 W/g for 60–90 s and 5 W/g for 60 s exposure time, stored in PP retained both seed and grain qualities at the end of 4 months. The Principal Component Analysis (PCA) was carried out to define the most appropriate descriptors of quality attributes of the microwave treated groundnut samples during the storage period. The highest significant negative correlation was found between moisture content and oil yield (r = −0.815) as well as between germination capacity and free fatty acid content (r = −0.815) whereas infestation percentage was positively correlated with the moisture content (r = 0.719) of microwave treated groundnut samples during the four months of storage study.

Short-term exposure to silver nano-particles alters the physiology and induces stress-related gene expression in Nelumbo nucifera

Lotus (Nelumbo nucifera) was used as model plant in this study to explore its physiology and molecular response upon short-term exposure to silver nano-particles (AgNPs). Accumulation patterns demonstrated a potential uptake of AgNPs by roots and transport to the leaves as a likely key translocation route in lotus. AgNPs exposure was negatively correlated with lotus growth, including germination rate and petiole length in a concentration-dependent manner. Synthesis of chloroplast pigments in lotus leaves was enhanced by low AgNPs concentration, but were inhibited at high concentration. Hydrogen peroxide (H2O2) was detected in lotus leaves after AgNPs treatment. Proline accumulation in lotus leaves was induced with the increase in AgNPs concentration and exposure time. Antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD) as well as catalase (CAT) were enhanced after the first day of AgNPs exposure, but declined with increased exposure time, indicating a time-dependent toxicity of AgNPs. In addition, real-time PCR revealed that two detoxification-related genes, GSH1 and GST, could be activated on the first day of AgNPs exposure, but down-regulated with prolonged AgNPs treatment. Photosynthesis-related RbcS gene was up-regulated, however, no obvious difference in the expression of RbcL was observed after the first day of AgNPs exposure. Moreover, WRKY70a and WRKY70b transcription factors exhibited similar expression patterns, with the highest induction after a 5 mg/L AgNPs exposure on the first day, which decreased with prolonged exposure time. This study provides useful references for further evaluation of the toxic mechanism of AgNPs and their bio-effects on aquatic plants and ecosystems.

Acute effects of antimony exposure on adult zebrafish (Danio rerio): From an oxidative stress and intestinal microbiota perspective

The rapid development of the textile industry has resulted in a large influx of wastewater production. The “national discharge standards of water pollutants for dyeing and finishing of textile industry (GB4287-2012)” stipulates that the discharge of total Sb from textile industry effluent must be < 0.10 mg/L, but it is difficult to meet the standard at present. Antimony is potentially carcinogenic, and the pathogenic mechanism of antimony is poorly understood. In this study, the acute toxic effects of various concentrations of antimony on adult zebrafish (Danio rerio) were investigated, including effects on oxidative stress, neurotransmitters and intestinal microbiota. The activities of catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), superoxide dismutase (SOD), total antioxidant capacity (T-AOC) and acetylcholinesterase (AChE) were measured in zebrafish muscle and intestine tissue samples. In addition, intestinal microbial community composition and diversity of zebrafish were also analyzed. The results demonstrated that SOD, CAT and GSH-Px activities in the zebrafish gut showed a decreasing and then increasing trend with antimony concentration increasing. SOD, CAT and MDA in zebrafish muscle decreased with increasing exposure time. GSH-Px activities increased with increasing exposure time. T-AOC increased and then decreased. In addition, antimony exposure was neurotoxic to zebrafish, and a significant decrease in AChE activity was found in the intestine with increased exposure time. The neurotoxicity caused by antimony in the high concentration group (40 mg/L) was stronger than that in low concentration groups (10 mg/L and 20 mg/L). Notably, antimony exposure caused increases in the relative abundance of phyla Fusobacteriota and Actinomycetes, but decreases in the relative abundance of the phyla Firmicutes and Proteobacteria in zebrafish intestine. These outcomes will advance our understanding of antimony-induced biotoxicity, environmental problems, and health hazards. In conclusion, this study shows that acute exposure of antimony to zebrafish induces host oxidative stress and neurotoxicity, dysregulates the intestinal microbiota, showing adverse effects on the health and gut microbiota of zebrafish.

Potential of Tomato Pomace Extract as a Multifunction Inhibitor Corrosion of Mild Steel

The aim of this paper is to investigate tomato pomace extract (TPE) as a multifunctional “green” vapor phase corrosion inhibitor for prevention from the atmospheric corrosion of mild steel and as a corrosion inhibitor in neutral media of 0.5 M NaCl solution. TPE would be an effective inhibitor with the efficiency of around 98% in both corrosive conditions. The chemical profile of the TPE was analyzed using gas chromatography mass spectrometry (GC–MS) and high-performance liquid chromatography analysis (HPLC-DAD-MS). The major volatile constituents identified in tomato pomace extract were alcohols (12.5%), fatty acids (23.78%), aldehydes (41.6%), ketones (8.65%), and terpenoids (9.11%). The predominant semi-volatile and high molecular weight chemical components in tomato pomace extract were phenolic acids and flavanols [caffeic acid (2.03 ± 0.3 μg/g), chlorogenic acid (37.23 ± 0.80 μg/g), gallic acid (10.2 ± 0.80 μg/g)]. The corrosion protection properties of the TPE as multifunctional corrosion inhibitor were studied using accelerated corrosion tests (weight loss method) and electrochemical methods [polarization curves and linear polarization technique (LPR)]. The mechanism of steel inhibition by TPE formulations was studied with the help of scanning electron microscopy (SEM) and atomic force microscopy (AFM) observations. TPE acts as a "pro-inhibitor" of the steel corrosion in neutral solution. The analysis confirmed that the growth of inhibitory properties is prolonged and corrosion rate is reduced after 40–48 h of exposure. The inhibition efficiency increases with increasing exposure time and reaches 98% after 48 h. Quantum-chemical calculations were used to predict the adsorption/inhibition properties of some of the main compounds of the extract and compounds formed as a result of chemical conversion. This work to contributes interpretation/explanation and understanding of the mechanism of action of green corrosion inhibitors in neutral solution.

Time dependency and similarity of gas permeability of concrete in simulated environment

It is of great significance to establish the similarity for time-dependent permeability between simulated environment and natural environment for predicting the time-dependent permeability in practical engineering. Based on the exposure test of ordinary concrete in natural tidal environment and simulated environment, the time-dependent intrinsic gas permeability coefficients (Kg) of concrete were analyzed, and the influence of w/c ratio on Kg and age reduction factor of gas permeability coefficient (mg) was studied. According to the relaxation time tracked by the nuclear magnetic resonance (NMR) method, the time-dependent microstructure parameters of concrete in the natural and simulated environments, such as porosity, pore size distribution, capillary pores porosity, critical pore diameter (Dcd) and mean pore diameter (Dmd) were analyzed. Then, the relationship between the time-dependent gas permeability and microstructure parameters was discussed. Results show that Kg decreased with the increasing exposure time and decreasing w/c ratio. The value of mg decreases with the increasing w/c ratio, and for concrete with the same w/c ratio, mg in the simulated environment is larger than that in the natural tidal environment. Porosity, capillary pores porosity and Dcd of concrete all decrease with exposure time, and have good correlations with gas permeability coefficient (KA) of concrete. Meanwhile, ambient environment has little influence on the correlation between gas permeability and Dcd. At last, based on the similarity between Kg and microstructure parameters in the natural and simulated environments, the rationality of calculating the long-term Kg in natural environment from the short-term results in the simulated environment is verified.

More Insights about the Efficacy of Copper Ion Treatment on Mycobacterium avium subsp. paratuberculosis (MAP): A Clue for the Observed Tolerance.

Background: Scientific evidence is scarce for the antimicrobial effect of copper on bacteria characterized as more resistant. Using Mycobacterium avium subsp. paratuberculosis (MAP), a highly resistant microorganism, as a pathogen model, copper ion treatment has shown a significant bactericidal effect; however, the sustainability of MAP against copper toxicity was also reported in several studies. Accordingly, the present study aimed to evaluate the impacts of copper on MAP. Methodology: This study considered physicochemical properties and copper concentration in a buffer since it could modulate MAP response during the application of copper treatment. Results: Despite the efficacy of copper ions in significantly reducing the MAP load in Phosphate Buffered Saline, some MAP cells were able to survive. The copper concentration generated by the copper ion treatment device increased significantly with increasing exposure times. MAP bacterial load decreased significantly when treated with copper ions as the exposure times increased. An increase in pH decreased oxygen consumption, and an increase in conductivity was reported after treatment application. Conclusions: Even with higher concentrations of copper, the efficacy of MAP control was not complete. The concentration of copper must be a key element in achieving control of highly resistant microorganisms.

Neurotoxicity of anthracene and benz[a]anthracene involves oxidative stress-induced neuronal damage, cholinergic dysfunction and disruption of monoaminergic and purinergic enzymes.

In this study, the modulatory effects of anthracene (ANT) and benz[a]anthracene (BEN) on biochemical markers associated with neurodegeneration were assessed in mouse hippocampal neuronal cells (HT-22). Neuronal cells were cultured and exposed to ANT and BEN (25-125µM) for 5days, and the cell viability was determined via MTT assay. Morphological characteristics of the cells were assessed using a compound microscope. Biochemical parameters such as acetylcholinesterase (AChE), monoamine oxidase (MAO) and adenosine deaminase (ADA) activities as well as oxidative stress biomarkers (catalase [CAT], glutathione -S- transferase [GST] activities and Glutathione [GSH] levels) and nitric oxide [NO] levels were assessed after cells were treated with ANT and BEN for two days. The results showed that cell viability reduced with an increase in exposure time. After the fifth day of treatment, BEN and ANT (125µM) reduced percentage viability to 41 and 38.1%, respectively. Light micrographs showed shrinkage of cells, neuronal injury and cell death in cells treated with higher concentrations of BEN and ANT (50 and 125µM). Furthermore, AChE and MAO activities reduced significantly after treatment for 48h with ANT and BEN. A significant decrease in CAT and GST activities and low GSH levels were observed after treatment with BEN and ANT. However, both polycyclic aromatic hydrocarbons caused a significant increase in ADA activity and NO levels. These results suggest that ANT and BEN may induce neurodegeneration in neuronal cells via oxidative stress-induced-neuronal injury, disruption of cholinergic, monoaminergic and purinergic transmission, and increased nitric oxide levels.

The oxidation behavior of nickel‐based alloy Inconel 617 in supercritical water

AbstractThe corrosion behavior of Inconel 617 in supercritical water has been analyzed at 600°C–650°C and 25 MPa for up to 1000 h. The time dependence of the oxidation rate indicated that the oxidation kinetics follows parabolic law. Many fine oxide crystallites were observed at the surface of Inconel 617 while the thickness of the oxide increased with an increase of exposure temperature and time. The Inconel 617 exhibited excellent oxidation resistance due to the formation of Cr2O3. Furthermore, NiFe2O4, NiCr2O4, and CoO were also detected at 600°C while TiO2, NiFe2O4, and NiCr2O4 were detected at 650°C by using X‐ray diffraction, X‐ray photoelectron spectroscopy, and Raman spectroscopy. The formation mechanism of the oxide film is discussed.

Effects of cold work on the corrosion behavior of Alloy 800H exposed to aerated supercritical water

• Cold work reduces the corrosion resistance of Alloy 800H in supercritical water containing 200 ppb oxygen. • At initial corrosion stage, the corrosion behavior of as-received and cold-worked materials is similar. • The formation of a continuous chromia layer reduces the oxygen partial pressure at the oxide scale-matrix interface, which contributes to the later internal oxidation and selective oxidation of the elements. • With the increase of exposure time, the microstructure of the cold worked materials becomes more complicated and is further subdivided into Fe 3 O 4 /Ni x Fe 3- x O 4 /Ni x Fe y Cr 3- x - y O 4 /Cr 2 O 3 / NiO/Fe x Cr 2- x O 4 +pure Ni multi-layer structure. • Through observation of the oxidation process and the calculation of thermodynamic equilibria, the oxide scale differences were explained through the hypothesis that diffusion barriers were created by the prevailing oxides. Revealing the corrosion mechanism of materials in supercritical water (SCW) is a key issue for the development of a supercritical water reactor (SCWR). Considering cold work is inevitable in the construction of nuclear reactors and its effect on the corrosion behavior of materials in SCW is still unclear, the corrosion behavior of solution-annealed (as-received) and 30% cold-worked Alloy 800H were studied at 600 °C in aerated SCW for 1500 h. The microstructure of the oxide scale was studied by a variety of characterization techniques. The results indicate that cold work increases the corrosion rate of the materials, promotes selective oxidation and internal oxidation, and this was attributed to the high diffusion rate of different ions along “short-circuit paths”. The oxide scale composition and structure of the cold-worked material, which is subdivided to Fe 3 O 4 /Ni x Fe 3- x O 4 /Ni x Fe y Cr 3- x - y O 4 /Cr 2 O 3 /NiO/ Fe x Cr 2- x O 4 + pure Ni multi-layer structure, are much more complicated than the as-received material after 1500 h exposure. Combined with the thermo-dynamic equilibrium calculation, the oxidation processes of the as-received and cold-worked materials were analyzed to reveal the effect of cold work on the corrosion behavior of Alloy 800H.

The response of three typical freshwater algae to acute acid stress in water

The effect of acidic pH conditions on the physiological response of three typical freshwater algae, Chlorella vulgaris, Microcystis aeruginosa and Scenedesmus quadricauda, was investigated in this study. The results of the cultivation experiment indicated that the mortality of the three algae in the logarithmic growth phase increased with increasing exposure time and acidity under acute acidic conditions. The tolerance of S. quadricauda was stronger than that of the other two species under long-term (6 h) exposure to the same acidity; in contrast, C. vulgaris exhibited the greatest tolerance under short-term exposure conditions. The decrease in chlorophyll a (Chl a) content indicated that the photosynthesis of algae was inhibited under acid stress and that the algae could not continue to grow normally. This was consistent with the changes in lipid peroxidation and antioxidant enzyme activity, which were reflected by the malondialdehyde (MDA) content and superoxide dismutase (SOD) activity under acid stress, respectively. The results of this study demonstrated that when exposed to acute acidic conditions, the tolerance of three typical freshwater algae to acidity was significantly different. These findings provide valuable information for poorly mixed acidification operations designed to adjust the pH in lakes, reservoirs, or intake pipes of purification plants.

Impact of Replacing Old C-Arms on Reducing Radiation Exposure

AbstractFluoroscopy is increasingly used by gastroenterologists for endoscopic procedures such as endoscopic retrograde cholangiopancreatography. Unfortunately, fluoroscopy exposes patients and staff to ionizing radiation, which can cause DNA damage, cell death, genetic defects, and cancer. These adverse effects are more likely to occur with increased exposure time and higher radiation doses; therefore, all efforts to decrease exposure are helpful. In this study, we investigate the impact that updating the C-Arms in our endoscopy unit will have on radiation exposure by comparing ionizing radiation effects of the OEC 9900 Elite to the newer OEC Elite. After replicating the setup of a typical endoscopic retrograde cholangiopancreatography, ionizing radiation and energy were measured at the bedside and the head of the bed with each machine. At both positions, the newer OEC Elite C-Arm emitted less energy and ionizing radiation than the OEC 9900 Elite. Continuous imaging with OEC 9900 Elite emitted 0.12 mSv/h at the head of the bed and 0.49 mSv/h at the bedside, while the OEC Elite only emitted 0.04 mSv/h and 0.14 mSv/h, respectively. These values are measures of radiation-induced cancer risk, otherwise known as stochastic risk. The differences grow more significant when extrapolated to show radiation differences for an average procedure (approximately 8 minutes of fluoroscopy time) and the procedural volume for an entire year. In an effort to use as little radiation as possible, we see that we can significantly reduce radiation exposure to our staff by upgrading from an OEC 9900 Elite to and OEC Elite.

In vitro antifungal activity of cold atmospheric microwave plasma and synergistic activity against Malassezia pachydermatis when combined with chlorhexidine gluconate

BackgroundThe antifungal efficacy of cold atmospheric microwave plasma (CAMP) against Malassezia pachydermatis has not been to be evaluated.ObjectiveTo examine the antifungal effects of CAMP against M. pachydermatis and its synergistic effects with chlorhexidine gluconate (CHX).MethodsA M. pachydermatis isolate was collected from a dog with otitis externa and Malassezia dermatitis at the Seoul National University Veterinary Medical Teaching Hospital. The antifungal effect was determined by applying CAMP to a M. pachydermatis isolate that was incubated for 3 days at 37°C. After 1, 2, 3 and 5 min of application, the efficacy of the plasma treatment was determined according to the number of colony forming units (CFUs). A mixture consisting of inoculum and CHX was applied to evaluate the synergistic effect of the plasma treatment in the same way.ResultsThe application of CAMP showed significant antifungal effects against M. pachydermatis. The antifungal effect of CAMP was enhanced by an increased exposure time and output power. The application of CAMP with 0.02% and 0.2% CHX resulted in lower survival rates against M. pachydermatis when compared with its sole application at 1 or 2 min.ConclusionsThe study findings demonstrate that CAMP has a potential as a new antifungal option for M. pachydermatis and has synergistic antifungal effects with CHX in vitro. Clinical applications for CAMP are necessary to assess the antifungal efficacy for patients.

Resistance of Lepidopteran Egg Parasitoids, Trichogramma japonicum and Trichogramma chilonis, to Insecticides Used for Control of Rice Planthoppers.

Trichogramma wasps are commonly used as biocontrol agents to manage lepidopteran rice pests in rice fields. However, lepidopteran pests synergistically occur with rice planthoppers which are not targeted by Trichogramma. The use of Trichogramma parasitoids in field-based pest control efforts is greatly affected by the application of insecticides targeting planthoppers. As such, insecticide-resistant strains of Trichogramma are urgently needed for the incorporation of these beneficial natural enemies into integrated pest management programs in rice agroecosystems. In the present study, Trichogramma japonicum Ahmead (Hymenoptera: Trichogrammitidae) and Trichogramma chilonis Ishii (Hymenoptera: Trichogrammitidae) were treated with sublethal doses of four insecticides which target rice planthoppers, to generate tolerant strains in the laboratory. The resistance rate of T. japonicum to imidacloprid was the highest (17.8-folds) after 10 successive treatments and experienced 2.5, 4.72, and 7.41-fold increases in tolerance to thiamethoxam, buprofezin, and nitenpyram, respectively. Tolerance of T. chilonis to imidacloprid, thiamethoxam, buprofezin, and nitenpyram were 8.8, 6.9, 4.43, and 5.67-fold greater, respectively. The emergence and deformity (without spreading wings or short wings) rates of T. japonicum and T. chilonis gradually recovered with an increased exposure time of treatments. The fecundity of T. japonicum treated with thiamethoxam was significantly higher than that of the control and T. chilonis treated with thiamethoxam and nitenpyra. Our results demonstrate that screening for insecticide-tolerant/resistant Trichogramma strains was feasible, especially in the pairing of T. japonicum and imidacloprid, which could provide a valuable biological control tool that can be combined with traditional chemical control strategies for use in IPM of rice agroecosystems.

Preparation and characterization of glucose-conjugated super-paramagnetic iron oxide nanoparticles (G-SPIONs) for removal of Edwardsiella tarda and Aeromonas hydrophila from water.

The present research was conducted to prepare efficient G-SPIONs by co-precipitation to remove Edwardsiella tarda and Aeromonas hydrophila from the aqueous solution. The synthesized G-SPIONs were characterized by UV-Vis spectrophotometer, DLS, FEG-TEM, FT-IR, XRD, and VSM analysis. The results showed that the synthesized G-SPIONs had super-paramagnetic properties (58.31 emu/g) and spherical shape (16 ± 3nm). The antibacterial activity was assessed in sterilized distilled water at different G-SPIONs concentrations viz. 0, 1.5, 3, 6, 12, 24, 48, 120, and 240 mg/L against E. tarda and A. hydrophila with various bacterial loads viz. 1 × 103 , 1 × 104 , 1 × 105 , 1 × 106 , and 1 × 107 CFU/ml at different time intervals 15, 30, 45, and 60 min. At a lower bacterial load of E. tarda and A. hydrophila 1 × 103 -1 × 104 CFU/ml, 100% bacterial load was removed by 15 min exposure with NPs concentration 6-48 mg/L and 1.5-6mg/L, respectively. Cent percent bacterial removal was observed in both the bacterial species even at higher bacterial load (1 × 105 -1 × 107 CFU/ml) by increasing exposure time (15-60 min) and nanoparticle concentration as well (24-240 mg/L). At an initial bacterial load of E. tarda and A. hydrophila (1 × 103 -1 × 107 CFU/ml), the EC50 ranged between 0.01-6.51 mg/L and 0.02-3.84 mg/L, respectively, after 15-60 min exposure. Thus, it is concluded that the antibacterial effect of G-SPIONs depends on concentration and exposure time. Hence, G-SPIONs can be used as an antibacterial/biocidal agent to treat Edwardsiellosis and Aeromonosis disease in aquaculture. HIGHLIGHTS: The glucose-conjugated super-paramagnetic iron oxide nanoparticles (G-SPIONs) synthesized by rapid and high yield co-precipitation method shows bacterial removal efficiency against Edwardsiella tarda and Aeromonas hydrophila The bacterial removal efficiency of G-SPIONs depends on concentration and exposure time to both the bacterial species The 100% bacterial removal efficiency can be achieved even at the highest bacterial load (1 × 107 CFU/ml) against E. tarda and A. hydrophila after 45 and 30 min exposure Due to the high bacterial removal efficiency of G-SPIONs against E. tarda and A. hydrophila, it can be used for the treatment of Edwardsiellosis and Aeromonosis in fish.

Responses of photosynthesis, antioxidant enzymes, and related gene expression to nicosulfuron stress in sweet maize (Zea mays L.).

Weed control in maize (Zea mays L.) crops is usually undertaken using the postemergence herbicide nicosulfuron. The toxicity of nicosulfuron on maize, especially sweet maize, has been widely reported. In order to examine the effect of nicosulfuron on seedling photosynthetic characteristics, chlorophyll fluorescence, reactive oxygen species production, antioxidant enzyme activities, and gene expressions on sweet maize, nicosulfuron-tolerant "HK310" and nicosulfuron-sensitive "HK320" were studied. All experiment samples were subjected to a water or 80mgkg-1 of nicosulfuron treatment when sweet maize seedlings grow to the stage of four leaves. After treatment with nicosulfuron, results for HK301 were significantly higher than those for HK320 for net photosynthetic rate, transpiration rate, stomatal conductance, leaf maximum photochemical efficiency of PSII, photochemical quenching of chlorophyll fluorescence, and the electron transport rate. These results were contrary to nonphotochemical quenching and intercellular CO2 concentration. As exposure time increased, associated effects also increased. Both O2·- and H2O2 detoxification is modulated by antioxidant enzymes. Compared to HK301, SOD, POD, and CAT activities of HK320 were significantly reduced as exposure time increase. Compared to HK320, the gene expression for the majority of SOD genes, except for SOD2, increased due to inducement by nicosulfuron, and it significantly upregulated the gene expression of CAT in HK301. Results from this study indicate that plants can improve photosynthesis, scavenging capabilities of ROS, and protective mechanisms to alleviate phytotoxic effect of nicosulfuron. Future research is needed to further elucidate the important role antioxidant systems and gene regulation play in herbicide detoxification in sweet maize.