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Salt solution pool boiling is of great significance in thermal engineering equipment, such as boilers and heat exchangers. Few researchers have been able to draw on systematic research into the impacts of salt concentration on boiling heat transfer coefficients. This experimental work is aimed to understand the role of dissolved salts on pool boiling performance, which is affected by surface wettability and bubble dynamics. Pool boiling experiment was conducted within a broad range of salt concentration. The results show two different tendencies for the two heating surfaces. The heat transfer coefficient is enhanced in the pin–fin heating surface while deteriorated in the bare heating surface as the salt concentration increased. It is indicated that salt solution promotes bubble diameter and nucleate density for ∼13% and 9%, respectively, by strengthening the hydrophobicity of the pin–fin heating surface. Hence, the boiling heat transfer is strengthened. [ABSTRACT FROM AUTHOR]

Adverse effects of methyl tertiary-butyl ether (MTBE) have been noticed at different trophic levels by international researchers. However, there was unclear evidence about its effects on oxidative stress and DNA damage in earthworms. In this study, earthworms were cultivated in various doses of MTBE (0.0 mg/kg, 10.0 mg/kg, 30.0 mg/kg, and 60.0 mg/kg) contaminated agricultural soil for 7 days, 14 days, 21 days, and 28 days, respectively. The result showed that the reactive oxygen species (ROS) content of earthworms significantly increased in MTBE treatment groups compared to the control group. In MTBE treatment groups, the activities of superoxide dismutase, catalase, peroxidase, and glutathione S-transferase were significantly activated at the exposure of 7 days, which increased by 36.3–78.9%, 51.8–97.3%, 36.5–61.9%, and 12.0–54.8%, respectively. Then, the activities of these defense enzymes showed various changes following the changes in exposure times and MTBE concentrations. Especially in the 60.0 mg kg−1 group, both antioxidant enzymes and GST were still significantly activated at the exposure of 14 days and then significantly inhibited at the exposure of 28 days. The analysis of olive tail moment showed significant DNA damage in the 10.0 mg kg−1 group at the exposure of 28 days, and this damage in 30.0 mg/kg and 60.0 mg/kg groups was found at the exposure of 7 days. This result was consistent with the malondialdehyde accumulation in earthworms. Additionally, the analysis of IBRv2 showed the effects of MTBE treatments on earthworms in dose- and time-dependent manners. This study helps better to understand the effects of MTBE on soil invertebrate animals and provide theoretical support for soil protection in governing MTBE application. [ABSTRACT FROM AUTHOR]

An image compression-encryption scheme utilizing the combination of fiber specklegram-based compressive sensing (CS) and double random phase encoding (DRPE) was demonstrated. The original image is compressed and encrypted by CS and then re-encrypted by DRPE. The measurement matrices for CS are constructed from multimode fiber specklegrams resulting from modes excitation and interference, which show better performance compared with those based on Gaussian random variables. Since fiber specklegrams have strong dependence on configuration, such measurement matrix can be constructed either by one specklegram or by specklegrams from different launched wavelengths. The double-encrypted image demonstrated good safety and reliability in several common attacks and presented high key sensitivity, which indicates good performance of the proposed scheme. [ABSTRACT FROM AUTHOR]

Mode excitations in D-shaped multimode fiber are analyzed in detail in terms of the effect of launch offset, polishing depth, and length of the D-shaped section. Based on the analysis, specklegrams from D-shaped multimode fiber structures are proposed to be applied in refractive index sensing. Glycerol solutions with different concentrations were used to study the relationship between the zero-mean normalized cross-correlation coefficient (ZNCC) of fiber output specklegrams and the surrounding refractive index. Responses of different D-shaped fiber structures are investigated and compared. For all of the structures, regular gradual changes of the ZNCC for each specklegram with the refractive index are found in a wide refractive index range of 1.352-1.444, which shows the feasibility of refractive index sensing. A high sensitivity being 10.47 RIU−1 is obtained by the structure with the polishing depth being $18~\mu \text{m}$ and length being 5cm. The proposed refractive sensing scheme is easy to realize with wide measurement range and high flexibility. [ABSTRACT FROM AUTHOR]

Copper (Cu) is one of the most commonly detected heavy metals in livestock manure pollution. Protaetia brevitarsis Lewis larvae are widely used in the decomposition of livestock manure. During decomposition, heavy metals in livestock manure can accumulate in P. brevitarsis larvae and affect normal growth and reproduction. Therefore, this research focused on characterizing the toxic effects of Cu to P. brevitarsis Lewis larvae. Larvae were exposed to Cu concentrations of 0, 100, 200, 400, and 800 mg kg−1 in edible fungi residue for 7, 14, 21, and 28 days. Results showed that the soluble protein content was markedly increased in 200 and 400 mg kg−1 treatment groups on day 28. Compared to the control group, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities were significantly stimulated on day 7 and then decreased as exposure length was increased (e.g., after 14, 21, and 28 days). Catalase (CAT) activity was also significantly increased after 7 days of exposure. Malondialdehyde (MDA) levels were markedly increased in the 100, 200, and 400 mg kg−1 treatment groups on day 7. However, as time and Cu concentration were increased, MDA levels gradually decreased. These results indicate that Cu has biochemical effects on P. brevitarsis Lewis larvae, and both time and dose affect this biochemical response. [ABSTRACT FROM AUTHOR]

The processing technology measures for the spinning of machine picked cotton with new blowing-carding unit were discussed. The technology performance of JWF1213 carding machine and the cotton assorting, processing configuration and processing parameters for Xinjiang machine picked cotton spinning were introduced. The indexes changing situation like neps and short fiber content of half finished product in each process together with the quality indexes of sliver and yarn were analyzed. The technology measures and matters needing attention for the spinning of Xinjiang machine picked cotton with blowing-carding unit were summarized. It is considered that picking process should focus on impurity removal, the drop gauge should be in larger control and the beater speed in each part should all be in smaller control according to the property of Xinjiang machine picked cotton with higher impurity rate. Carding should be moderated for carding machine and focusing on removing more short fibers and tiny impurities. The cotton feeding parameters of blowing-carding unit should be optimized and the function of auto-levelling should be well played to ensure the weight unevenness index of silver after blowing-car ding meeting the spinning requirement. [ABSTRACT FROM AUTHOR]

The accurate and fast calculation of circulating currents between strands for different transposition types is the important premise of the engineering design for stator bars in large turbo-generators. The air gap magnetic field partly enters into the stator slot, also generating circulating currents. However, there is a lack of fast simulation method for calculating the air gap magnetic field entering the stator slot in the existing calculation method for circulating currents. In this paper, the analytical algorithm of calculating circulating currents considering the air gap magnetic field entering stator slots is proposed, in which the equivalent circuit model of transposed strands in stator bars is established based on the superposition principle, the analytical algorithm of calculating the induced electromotive force is proposed based on the discrete integral method, and the analytical algorithm of calculating the air gap magnetic field entering stator slots is proposed based on the conformal mapping method. Then, a 1400-MW turbo-generator is taken as an example, circulating currents between transposed strands in stator bars under no-load and rated condition are calculated by the proposed analytical algorithm. Finally, the proposed analytical algorithm is validated by the two-dimensional finite element method. [ABSTRACT FROM AUTHOR]

Purpose: Understanding the spatial distribution and sources of soil heavy metals (HMs) in a large city helps prevent and control soil pollution. This study aimed to investigate the spatial patterns of soil HMs and identify their main sources in a regional scale.Materials and methods: A total of 110 topsoil samples were collected from Tai’an City, China. Cd, Cr, Cu, Hg, Ni, Pb, and Zn concentrations in each soil sample were determined. Geostatistics, geographic information system (GIS), and positive matrix factorization (PMF) were used to explore the spatial distribution of seven soil HMs and to reveal the main sources of soil HMs in Tai’an City, respectively.Results and discussion: Soil Cd, Cr, Pb, and Zn generally showed slight pollution levels in the study area. However, soil Hg and Cu contents reached moderate to heavy pollution levels in some areas. Soil Hg content increased from north to south across the city, and the highest Hg concentration was detected in Ningyang County. Soil Cd, Cu, and Zn distributions exhibited a similar pattern, and their contents increased from west to east; the highest Cd, Cu, and Zn concentrations were found in Xintai County. The highest soil Ni concentration was obtained in the northeast of Feicheng and Xintai counties. PMF analysis revealed the following four potential sources of agricultural soil HMs in Tai’an City: industrial and mining activities, agricultural activities, residential living activities, and business activities. Soil Hg mainly originated from residential living activities, which accounted for 75.3% of the total source. The main sources of soil Ni were residential living activities, agricultural activities, and industrial and mining activities, which account for 38.2, 27.50, and 25.1% of the total source, respectively. Soil Cu was mainly produced by agricultural activities (36.6%), followed by residential living activities (29.8%) and industrial and mining activities (25.8%).Conclusions: PMF combined with GIS could be effectively applied to determine the main sources of HMs in agricultural soils in a regional scale. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA) is considered a persistent environmental pollutant. The aim of this study was to assess the potential toxicity of PFOA to earthworms ( Eisenia fetida) in artificial soil. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST) as well as the contents of malondialdehyde (MDA) were measured after exposure to 0, 5, 10, 20, and 40 mg kg PFOA in soils for 7, 14, 21, and 28 days. The results showed that SOD activity increased at 14 days and decreased from 21 to 28 days; MDA levels were highest in the treatment with 40 mg kg PFOA after 28 days of exposure. In contrast, CAT and POD activities increased after 14-21 days of exposure and significantly decreased with long-term exposure (28 days). GST activity increased significantly from 14 to 28 days. Our results indicate that PFOA has biochemical effects on E. fetida, thereby contributing to our understanding of the ecological toxicity of PFOA on soil invertebrates. [ABSTRACT FROM AUTHOR]

For cost reduction and process simplification, a homogenous liquid precursor for zirconium carbide (ZrC)-SiC ceramics was prepared by blending Zr(OCH), divinylbenzene, and polycarbosilane (PCS). The mixture was cross-linked at 150 °C, decomposed to ZrO, carbon, and SiC at 800 °C, and then ZrO and carbon reacted with each other via carbo-thermal reaction at 1500 °C to form ZrC-SiC ceramics that contained few ZrO. The ZrO content was reduced either by increasing the temperature from 1500 to 1700 °C, or by extending the holding time from 1 to 2 h. Increasing the content of PCS in the precursor not only benefited the carbo-thermal reaction but also caused the generation of free carbon in the pyrolyzed ceramic products. When the precursor contained the optimal content of PCS, the ceramics fabricated from it had a Si/Zr molar ratio of 1. C/ZrC-SiC composites were successfully fabricated via precursor infiltration and pyrolysis using the precursor. The flexural strength and fracture toughness of the composites were 212 ± 44 MPa and 13.8 ± 1.6 MPa m, respectively. [ABSTRACT FROM AUTHOR]

A field experiment was conducted in 2010-2012 to investigate the effects of different N fertigation regimes on diameter growth (measured as individual tree basal area increment), N uptake and biomass allocation in a triploid Populus tomentosa plantation in the North China Plain. The experiment included six N fertigation treatments (combination of three N application rates [NR: 115 (N), 230 (N) or 345 (N) kg ha year] and two application frequencies [NF: two (F) or four times (F) per year] and a single irrigation control treatment. Diameter at breast height, biomass and N uptake were monitored. N fertigation significantly increased aboveground diameter and N uptake compared with the control. Use of NR above 115 kg N ha year did not result in growth and N uptake benefits. NF showed almost no effect on tree growth, but F resulted in significantly higher N uptake. N fertigation resulted in a shift in biomass allocation from roots to leaves, but had no effect on relative allocation to wood biomass, which was significantly influenced by ontogeny (size effect). Biomass allocation of triploid P. tomentosa can be altered by N fertigation to some extent, but this was also under ontogenic control. Higher NR (N or N) and NF (F) are not necessary to achieve optimum growth, but higher NF is required for optimal N uptake. NF is recommended as the N fertigation regime for triploid P. tomentosa as this results in higher N uptake and optimal growth. [ABSTRACT FROM AUTHOR]

Di- n-butyl phthalates (DBP) are recognized as ubiquitous contaminants in soil and adversely impact the health of organisms. Changes in the activity of antioxidant enzymes and levels of glutathione- S-transferase (GST), glutathione (GSH), and malondialdehyde (MDA) were used as biomarkers to evaluate the impact of DBP on earthworms ( Eisenia fetida) after exposure to DBP for 28 days. DBP was added to artificial soil in the amounts of 0, 5, 10, 50, and 100 mg kg of soil. Earthworm tissues exposed to each treatment were collected on the 7th, 14th, 21st, and 28th day of the treatment. We found that superoxide dismutase (SOD) and catalase (CAT) levels were significantly inhibited in the 100 mg kg treatment group on day 28. After 21 days of treatment, GST activity in 10-50 mg kg treatment groups was markedly stimulated compared to the control group. MDA content in treatment groups was higher than in the control group throughout the exposure time, suggesting that DBP may lead to lipid peroxidation (LPO) in cells. GSH content increased in the treatment group that received 50 mg kg DBP from 7 days of exposure to 28 days. These results suggest that DBP induces serious oxidative damage on earthworms and induce the formation of reactive oxygen species (ROS) in earthworms. However, DBP concentration in current agricultural soil in China will not constitute any threat to the earthworm or other animals in the soil. [ABSTRACT FROM AUTHOR]

The influences of fiber preform structure and thread engagement length on the mechanical properties of Carbon fiber reinforced silicon carbide matrix ( C/SiC) threaded joints were studied. The results show that stacking 3K carbon fiber cloth followed by stitching is a good preform for preparing a C/SiC nut because of its high bearing ability. Stacking 1K carbon fiber cloth followed by stitching is a preferred preform to prepare a C/SiC bolt, and its minimum thread engagement length resulting in bolt rupture instead of thread spalling failure is 4 mm, which is obviously smaller than those of other bolts. [ABSTRACT FROM AUTHOR]

A new method to form helical C/ Si C spring is proposed. Using paraffin mold as a sacrificial core, unidirectional carbon fiber bundles (infiltrated with resin) are wrapped around the mold to form helical spring, and after resin curing, the mold is removed, leaving a preform of C/ Si C spring. Following densification is finished with precursor infiltration and pyrolysis ( PIP) process. The spring constant of C/ Si C spring reaches 7.88 N/mm and could be regulated by varying composite density and carbon fiber content. The spring properties could be improved by twisting the carbon fibers at 35-50 twist/m. The restoration ratio reaches 100%, but energy dissipation happens during unloading process. After oxidation in air at 1200°C for 10 min, the spring has an 82.4% spring constant remaining ratio. [ABSTRACT FROM AUTHOR]

C/SiC composites with three kinds of preforms (carbon fiber stitched cloth, Type S; three-dimensional fine woven pierced felt, Type 3D; carbon fiber needled bulk felt, Type N) were fabricated by precursor infiltration and pyrolysis (PIP) process, and then machined into bolts and nuts with nominal diameter of M8 by lathe and alloy screw tap, respectively. The thread shape and mechanical properties were investigated. The results show that the external thread shapes from Type 3D and Type N are better than that from Type S. The shear strengths of the nuts and the tensile strengths of the bolts from the three preforms are 67.38, 32.47, 48.99, 143.70, 159.20, and 95.90 MPa, respectively. The fracture mode of Type S bolts is external thread spalling, and those of the other two are bolt rupture. Therefore, the composite of Type 3D is a good choice for the bolts, and that of Type S for the nuts. [ABSTRACT FROM AUTHOR]

To provide a theoretical basis for developing intensive cultivation practices for Populus tomentosa plantations, the leaf phenology variation within the canopy and its relationship with transpiration of well-watered P. tomentosa tree in a dense plantation were investigated. The variation in canopy light interception, indicated by the ratio between net radiation under (Rn-u) and above (Rn-a) canopy, with leaf development was also studied. During the growing season, the achievement of maximum leaf number tended to be later in higher parts of the canopy. In the lower and middle canopy, the leaf number maximized earlier in the east-facing side than in the west-facing side, but this difference disappeared in the upper canopy. The Rn-u/Rn-a was stable in May, but declined and then varied steadily until late August. Generally, in May, the crop coefficient (Kcb) of the tree reached its highest level and was not correlated with leaf area (LA) in all layers (p > 0.05). However, it increased linearly (p < 0.001) with LA in the layers above a canopy height of 3 m from June to late August, and most of its variation was explained by LA in the 5–7 m layer. After late August, Kcb decreased linearly with decreasing LA in all layers (p < 0.001). Consequently, a temporal ecological strategy seems to be adopted by P. tomentosa leaves in different layers and azimuthal sides for efficient light acquisition. The contribution of the different canopy layers to tree transpiration can vary, with the leaves in the upper and all layers mainly controlling transpiration in summer and in spring and autumn, respectively. [ABSTRACT FROM AUTHOR]

Late embryogenesis abundant (LEA) genes were confirmed to confer resistance to drought and water deficiency. An LEA gene from Tamarix androssowii (named TaLEA) was transformed into Xiaohei poplar (Populus simonii × P. nigra) via Agrobacterium. Twenty-five independent transgenic lines were obtained that were resistant to kanamycin, and 11 transgenic lines were randomly selected for further analysis. The polymerase chain reaction (PCR) and ribonucleic acid (RNA) gel blot indicated that the TaLEA gene had been integrated into the poplar genome. The height growth rate, malondialdehyde (MDA) content, relative electrolyte leakage and damages due to salt or drought to transgenic and non-transgenic plants were compared under salt and drought stress conditions. The results showed that the constitutive expression of the TaLEA gene in transgenic poplars could induce an increase in height growth rate and a decrease in number and severity of wilted leaves under the salt and drought stresses. The MDA content and relative electrolyte leakage in transgenic lines under salt and drought stresses were significantly lower compared to those in non-transgenic plants, indicating that the TaLEA gene may enhance salt and drought tolerance by protecting cell membranes from damage. Moreover, amongst the lines analyzed for stress tolerance, the transgenic line 11 (T11) showed the highest tolerance levels under both salinity and drought stress conditions. These results indicated that the TaLEA gene could be a salt and drought tolerance candidate gene and could confer a broad spectrum of tolerance under abiotic stresses in poplars. [ABSTRACT FROM AUTHOR]