Microstructural and Performance Analysis of TP304H/T22 Dissimilar Steel Welded Joints.

In the power plant boiler industry, dissimilar steel welding is widely used in the connection of thermal power generation units. As an important component of the unit, research on the organizational properties of dissimilar steel welded joints has significant guidance for the life design of the joint. For the long-term service state of TP304H/T22 dissimilar steel welded joints, the microstructure's morphological evolution, the microhardness, and the tensile properties of tube samples were analyzed using tests and numerical simulations. The results show that the microstructure of each part of the welded joint was free of damaged features, such as a creep cavity and intergranular cracks. The microhardness of the weld was higher than that of the base metal. In the tensile test, the welded joints broke at the weld metal at room temperature and at the side of the TP304H base metal at a temperature of 550 °C. The tensile fracture morphology demonstrated a change from a ductile fracture to a hybrid fracture when the temperature rose. The fusion zone and base metal on the TP304H side were the stress concentration areas of the welded joint, which easily sprouted cracks. This study holds significant reference value in assessing the safety and reliability of dissimilar steel welded joints in superheater units.

One-step achievement of Fe-doped and interfacial Ru nanoclusters co-engineered Ni(OH)2 electrocatalyst on Ni foam for promoted oxygen evolution reaction.

The creation of inexpensive, high-performance catalysts to reduce the overpotential of the oxygen evolution reaction (OER) process is critical for the electrolysis of water for hydrogen production. Therefore, we applied a one-step hydrothermal method using cation exchange reaction (CER) to prepare Fe-doped and interfacial Ru nanoclusters co-engineered Ni(OH)2 nanosheets directly grafted on Ni foam (Ru@Fe-Ni(OH)2/NF) for OER process. Results of electrochemical tests reveal that Ru@Fe-Ni(OH)2/NF has excellent OER activity, and its overpotential (η) is only 266.4 mV when the current density is 50 mA cm-2 in 1 M KOH solution, even lower than that of commercial OER catalyst RuO2 (355 mV). The Tafel slope also decreases from 133.8 mV dec-1 for pristine Ni(OH)2/NF material to 24.1 mV dec-1 for Ru@Fe-Ni(OH)2/NF, indicating the higher charge transfer rates and fastest kinetics for water oxidation. At an overpotential of 300 mV the optimal turnover frequency (TOF) of 0.062 s-1 for Ru@Fe-Ni(OH)2/NF is achieved compared to that of Ni(OH)2/NF (0.014 s-1, NN), demonstrating the fast reaction kinetics of the as-prepared electrocatcalyst. After 24 h stability test, the catalytic activity of Ru@Fe-Ni(OH)2/NF was only attenuated by 2 %, showing excellent OER stability and durability. Our results show that we have successfully developed an efficient OER catalyst for green and efficient electrocatalytic hydrolysis to produce H2 and O2, providing a promising method for clean H2 production.

Calibration of Arrhenius Constitutive Equation for B4Cp/6063Al Composites in High Temperatures.

Isothermal-compression tests of B4Cp/6063Al composites containing 20 vol.% B4C were performed using a Gleeble-3500 device, at strain rates ranging from 0.001 s-1 to 1 s-1 and deformation temperatures ranging from 723 K to 823 K. The results showed that the high-temperature flow stress of B4Cp/6063Al composites increases with the decrease in deformation temperature or the increase in the strain rate. After friction correction, the friction corrected stress was less than the original experimental stress. At the initial stage of deformation, the difference between the rheological stress after friction correction and the measured rheological stress is small, but with the continuous increase in the strain, the difference between the rheological stress after friction correction and the measured rheological stress is grows. Under the same strain, the difference between the rheological stress before and after friction correction becomes more significant with the decrease in the deformation temperature and the increase in the strain rate. Next, the material constants (i.e., α, ß, Q, A, n) of B4Cp/6063Al composites were calibrated based on the experimental data, and a constitutive equation was established based on Arrhenius theory. The experimental values and predicted values of the stress-strain curves are in good agreement with the stress-strain curves of the finite element simulation, and the validity of the constitutive equation was verified.

Electrical conductivity of nutrient solution influenced photosynthesis, quality, and antioxidant enzyme activity of pakchoi (Brassica campestris L. ssp. Chinensis) in a hydroponic system.

To find an electrical conductivity (EC) in the nutrient solution used for pakchoi (Brassica campestris L. ssp. Chinensis) cultivation that optimizes the plant's physiology, growth, and quality, we conducted an experiment with eight EC treatments (from EC0 to EC9.6) in a hydroponic production system (i.e. soilless culture) under greenhouse condition in Shanghai, China. Plants biomass production, leaf photosynthesis, vegetable quality variables, tissue nitrate and nitrite contents, and antioxidant enzyme activities were measured. The results showed that very high (EC9.6) or low EC (EC0-0.6) treatments clearly decreased plants fresh weight (FW) and dry weight (DW), leaf size, leaf water content, leaf net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and taste score. Nitrite content, and antioxidant enzyme activities were low in medium EC treatments (EC1.8 and EC2.4), but high in very high or low EC treatments. Leaf relative chlorophyll, ascorbic acid, and nitrate contents increased gradually from low EC to high EC treatments, while crude fiber and soluble sugar contents decreased. Based on growth and quality criteria, the optimal EC treatment would be EC1.8 or EC2.4 for pakchoi in the hydroponic production system. Too high or too low EC would induce nutrient stress, enhance plant antioxidant enzyme activities, and suppress pakchoi growth and quality.

Effects of Pesticide Mixtures on Zooplankton Assemblages in Aquatic Microcosms Simulating Rice Paddy Fields.

The individual and combined effects of pesticides (chlorpyrifos, triadimefon and butachlor) on the zooplankton assemblages of microcosms were investigated. Laboratory microcosms were constructed with water and sediment to simulate aquatic conditions in China's rice paddy fields. Results from principal response curves analysis showed that butachlor and triadimefon had no significant impact individually on the population level in zooplankton assemblages. The deleterious effects of pesticide mixtures on the zooplankton were mainly caused by chlorpyrifos. In fact, assemblage succession only occurred in the treatments containing chlorpyrifos. There was no synergy effect on the microcosm from combinations of pesticides on the assemblages. The zooplankton assemblages affected by chlorpyrifos did not recover at the termination of the experiment, i.e., after 56 days.

Phytopathogenic fungal inhibitors from celery seeds.

Extract of celery (Apium graveolens L.) seeds was investigated against phytopathogenic fungi. The light petroleum extract showed promising inhibition activities in the tests against Rhizoctonia solani and Fusarium oxysporum f. sp. vasinfecum. Chromatographic separation of the extract gave 19 fractions, one of which, QCZ-4, possessed significant inhibitory rates of 64.6%, 88.4% and 54.7% at a concentration of 100 ppm against R. solani, F. oxysporium f. sp. vasinfecum and Alternaria alternata, respectively. Major components in the active fraction were identified by GC-MS as p-(2-aminoethyl)phenol (39.7%), 3-(3,4-dimethybenzoyl) propionic acid (32.6%) and p-heptylphenol (26.9%).

Analysis of the GM-CSF and GM-CSF/IL-3/IL-5 receptor common beta chain in a patient with pulmonary alveolar proteinosis.

OBJECTIVE: To investigate the expression of the granulocyte-macrophage colony-stimulating factor (GM-CSF) and GM-CSF/IL-3/IL-5 receptor common beta chain (beta c receptor) in an adult patient with idiopathic pulmonary alveolar proteinosis (PAP), so as to demonstrate the possible association of the GM-CSF and beta c receptor with the pathogenesis of human PAP. METHODS: The GM-CSF levels were measured with a commercial ELISA kit (sensitivity 5 pg/ml) and the beta c receptor expression on the cell surface was detected by flow cytometry analysis. Reverse transcription polymerase chain reaction (RT-PCR) analysis was employed to detect the expression of the GM-CSF mRNA and the beta c receptor mRNA in peripheral blood mononuclear cells and alveolar macrophages. The entire coding regions of the GM-CSF cDNA and the beta c receptor cDNA were sequenced by the Sanger dideoxy-mediated chain termination method to detect possible mutations. RESULTS: The patient with PAP failed to release the GM-CSF protein either from circulating mononuclear cells or from alveolar macrophages. The expression of the GM-CSF mRNA was normal after the stimulation of lipopolysaccharide, whereas a point mutation at position 382 of the GM-CSF cDNA from "T" to "C" was revealed by cDNA sequencing, which caused a change in amino acid 117 of the protein from isoleucine to threonine. The beta c receptor expression on the cell surface was normal, and the beta c receptor mRNA expression and the sequence of the entire coding region of the beta c receptor were also normal. CONCLUSIONS: The decreased GM-CSF production is associated with the pathogenesis of human PAP. A point mutation of the GM-CSF cDNA may contribute to the decreased GM-CSF production in our adult PAP patient. The mutation of the beta c receptor in some of paediatric patients with PAP may not be a common problem in adult patients.

[The observation of local immune response in the lungs from antigen-sensitized and challenged mice].

OBJECTIVE: To evaluate the local immune response after allergic sensitization and challenge in the lungs of mice. METHODS: C57BL/6 mice were sensitized with keyhole limpet hemocyanin (KLH) by intratracheal instillation and challenged 2 approximately 4 weeks later. Bronchoalveolar lavage fluid (BALF) and plasma were collected and cells from the lung-associated lymph node (LALN), the lungs and the spleen were cultured and collected. Anti-KLH IgA, total IgA and albumin levels were measured by ELISA. RESULTS: Intratracheal instillation of KLH induced local BAL antigen-specific IgA response, and further challenge expanded this response. The ratio of anti-KLH IgA/albumin in BALF was significantly higher than that in serum after both sensitization and challenge by KLH. In vitro, cells from the LALN and the lungs released anti-KLH IgA after sensitization and challenge by KLH, but spleen cells released lower levels of anti-KLH IgA compared to the LALN and the lungs. CONCLUSIONS: Allergic sensitization by intratracheal instillation of KLH into the mouse lungs induced a local pulmonary response of specific IgA, and it was amplified by challenge with KLH. The accumulation of anti-KLH IgA in the respiratory lumen was the result of local production but not the result of simple transudation or leakage from the serum. The LALN and the lung lymphocytes were major sources of anti-specific IgA.