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The analytical expressions for corona discharge currents are usually represented by the mathematic models based on curve fitting method. For the complex mechanisms, none of these currently models can describe a measured corona current with arbitrary waveforms. A novel curve fitting method using BP neural network (BPNN) technique is applied to describe the mathematic model of the corona currents in time domain. The analytical expressions for the currents can be established via extracting the weights and thresholds parameters of the trained BPNN. The expressions all have the same structure which has only four types of parameters, and the structure is independent of the corona current waveforms. The curve fitting for the measured corona currents with arbitrary waveforms by different models was carried out, and the results were analyzed, which indicate that the BPNN method performs best. Compared with the current expressions fitted by the double exponential function and Gaussian function, the expressions by BPNN can fit the current waveforms with the lowest mean square error (MSE) in time domain and the highest accuracy to spectra of the currents in frequency domain. The proposed method is suitable for establishing a unified analytical expressions model for corona currents with arbitrary shapes. [ABSTRACT FROM AUTHOR]

There are very few studies about the effects of relatively higher CO2 concentration (e.g., 1000 μmol·mol−1) or plus N fertilization on woody plants. In this study, Schima superba seedings were exposed to ambient or eCO2 (550, 750, and 1000 μmol·mol−1) and N fertilization (0 and 10 g·m−2·yr−1, hereafter: low N, high N, respectively) for one growth season to explore the potential responses in a subtropical site with low soil N availability. N fertilization strongly increased leaf mass-based N by 118.38%, 116.68%, 106.78%, and 138.95%, respectively, in different CO2 treatments and decreased starch, with a half reduction in leaf C:N ratio. Leaf N was significantly decreased by eCO2 in both low N and high N treatments, and N fertilization stimulated the decrease of leaf N and mitigated the increase of leaf C:N by eCO2. In low N treatments, photosynthetic rate (Pn) was maximized at 733 μmol·mol−1 CO2 in August and September, while, in high N treatments, Pn was continuously increased with elevation of CO2. N fertilization significantly increased plant biomass especially at highly elevated CO2, although no response of biomass to eCO2 alone. These findings indicated that N fertilization would modify the response of S. superba to eCO2. [ABSTRACT FROM AUTHOR]

Sucrose is a commonly utilized nutritive sweetener in food and beverages due to its abundance in nature and low production costs. However, excessive intake of sucrose increases the risk of metabolic disorders, including diabetes and obesity. Therefore, there is a growing demand for the development of nonnutritive sweeteners with almost no calories. d-Allulose is an ultra-low-calorie, rare six-carbon monosaccharide with high sweetness, making it an ideal alternative to sucrose. In this study, we developed a cell factory for d-allulose production from sucrose using Escherichia coli JM109 (DE3) as a chassis host. The genes cscA, cscB, cscK, alsE, and a6PP were co-expressed for the construction of the synthesis pathway. Then, the introduction of ptsG-F and knockout of ptsG, fruA, ptsI, and ptsH to reprogram sugar transport pathways resulted in an improvement in substrate utilization. Next, the carbon fluxes of the Embden-Meyerhof-Parnas and the pentose phosphate pathways were regulated by the inactivation of pfkA and zwf, achieving an increase in d-allulose titer and yield of 154.2% and 161.1%, respectively. Finally, scaled-up fermentation was performed in a 5 L fermenter. The titer of d-allulose reached 11.15 g/L, with a yield of 0.208 g/g on sucrose., (© 2024 Wiley Periodicals LLC.)

Although many studies have reported the negative effects of elevated O 3 on plant physiological characteristics, the influence of elevated O 3 on below-ground processes and soil microbial functioning is less studied. In this study, we examined the effects of elevated O 3 on soil properties, soil microbial biomass, as well as microbial community composition using high-throughput sequencing. Throughout one growing season, one-year old seedlings of two important endemic trees in subtropical China: Taxus chinensis (Pilger) Rehd. var. chinensis, and Machilus ichangensis Rehd. Et Wils, were exposed to charcoal-filtered air (CF as control), 100 nl l -1 (E100) or 150 nl l -1 (E150) O 3 -enriched air, in open top chambers (OTCs). We found that only higher O 3 exposure (E150) significantly decreased soil microbial biomass carbon and nitrogen in M. ichangensis, and the contents of organic matter were significantly decreased by E150 in both tree species. Although both levels of O 3 exposure decreased NO 3 -N in T. chinensis, only E150 increased NO 3 -N in M. ichangensis, and there were no effects of O 3 on NH 4 -N. Moreover, elevated O 3 elicited changes in soil microbial community structure and decreased fungal diversity in both M. ichangensis and T. chinensis. However, even though O 3 exposure reduced bacterial diversity in M. ichangensis, no effect of O 3 exposure on bacterial diversity was detected in soil grown with T. chinensis. Our results showed that elevated O 3 altered the abundance of bacteria and fungi in general, and in particular reduced nitrifiers and increased the relative abundance of some fungal taxa capable of denitrification, which may stimulate N 2 O emissions. Overall, our findings indicate that elevated O 3 not only impacts the soil microbial community structure, but may also exert an influence on the functioning of microbial communities., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Numerous studies have documented the negative effects of ozone (O 3 ) on tree species in growing season, however, little is done in non-growing season. Three evergreen tree species, Phoebe bournei (Hemsl.) Yang (P. bournei), Machilus pauhoi Kanehira (M. pauhoi) and Taxus chinensis (Pilger) Rehd (T. chinensis), were exposed to non-filtered air, 100 nmol mol -1 O 3 air (E1) and 150 nmol mol -1 O 3 air (E2) in open-top chambers in subtropical China. In the entire period of experiment, O 3 fumigation decreased net photosynthesis rate (Pn) through stomatal limitation during the transition period from growing to non-growing season (TGN), and through non-stomatal limitation during the period of non-growing season (NGS) in all species tested. Meanwhile, O 3 fumigation reduced and delayed the resilience of Pn in all species tested during the transition period from non-growing to growing season (TNG). O 3 fumigation significantly decreased chlorophyll contents during NGS, whereas no obvious injury symptoms were observed till the end of experiment. O 3 fumigation induced increases in levels of malondialdehyde, superoxide dismutase, total phenolics and reduced ascorbic acid, and changes in four plant endogenous hormones as well in all species tested during NGS. During NGS, E1 and E2 reduced Pn by an average of 80.11% in P. bournei, 94.56% in M. pauhoi and 12.57% in T. chinensis, indicating that the O 3 sensitivity was in an order of M. pauhoi > P. bournei > T. chinensis. Overall, O 3 fumigation inhibited carbon fixation in all species tested during NGS. Furthermore, O 3 -induced physiological activities also consumed the dry matter. All these suggested that elevated O 3 , which is likely to come true during NGS in the future, will adversely affect the accumulation of dry matter and the resilience of Pn during TNG in evergreen tree species, and further inhibit their growth and development in the upcoming growing season., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Numerous studies have demonstrated the negative effects of elevated O 3 on leaf photosynthesis. Within trees, a portion of respired CO 2 is assimilated by woody tissue photosynthesis, but its response to elevated O 3 remains unclear. Saplings of two evergreen tree species, EuCahetus dunnii Maiden (E. dunnii) and Osmanthus fragrans (Thunb.) Lour. (O. fragrans), were exposed to non-filtered air (NF), 100 nmol mol -1 O 3 air (E1) and 150 nmol mol -1 O 3 air (E2) in open-top chambers from May 5 to September 5, 2016 (8 h a day; 7 days a week) in subtropical China. In this study, O 3 fumigation significantly reduced leaf net photosynthesis rate in both two tree species on most measurements. However, compared with leaf net photosynthesis rate, woody tissue gross photosynthesis rate showed less negative response to O 3 fumigation and was even stimulated to increase. Refixation rate reflects the utilization efficiency of the respired CO 2 by woody tissue photosynthesis. During the experiment period, E1 and E2 both increased refixation rate in O. fragrans compared with NF. Whereas for E. dunnii, E1 increased refixation rate until 81 days after starting of fumigation and then decreased it, and E2 decreased it all the time. Refixation rate had a significant positive correlation with woody tissue chlorophyll contents, indicating that the response of refixation rate to elevated O 3 may relate to chlorophyll contents. All these suggested that under O 3 fumigation, when atmospheric CO 2 uptake and fixation by leaf is limited, woody tissue photosynthesis can contribute more to the total carbon assimilation in trees. The findings help to understand the significance of woody tissue photosynthesis under elevated O 3 conditions.

Considerable researches have documented the negative effects of ozone on woody species in North America and Europe; however, little is known about how woody tree species respond to elevated O 3 in subtropical China, and most of the previous studies were conducted using pot experiment. In the present study, Machilus ichangensis Rehd. et Wils (M. ichangensis) and Taxus chinensis (Pilger) Rehd. (T. chinensis), evergreen tree species in subtropical China, were exposed to non-filtered air (NF), 100 nmol mol -1 O 3 (E1) and 150 nmol mol -1 O 3 (E2), in open-top chambers under field conditions from 21st March to 2nd November 2015. In this study, O 3 fumigation significantly reduced net photosynthesis rate (Pn) in M. ichangensis in the three measurements and in T. chinensis in the last measurement. Also, non-stomatal factors should be primarily responsible for the decreased Pn. O 3 fumigation-induced increase in malondialdehyde, superoxide dismutase, and reduced ascorbic acid levels indicated that antioxidant defense mechanism had been stimulated to prevent O 3 stress and repair the oxidative damage. Yet, the increase of antioxidant ability was not enough to counteract the harm of O 3 fumigation. Because of the decrease in CO 2 assimilation, the growth of the two tree species was restrained ultimately. The sensitivity of the two tree species to O 3 can be determined: M. ichangensis > T. chinensis. It suggests a close link between the rising O 3 concentrations and the health risk of some tree species in subtropics in the near future.

The use of sewage sludge compost(SSC)as fertilizer may cause increased leaching due to its high content of heavy metals and thus pose a threat to groundwater quality. The effect of SSC application on heavy metals leaching in calcareous soils has been studied in field trials, which provides basis for determining heavy metals environmental capacity and preventing metal pollution in farmland soil scientifically. The results indicated that the contents of Cu, Zn elevated obviously with the increase of the age and the dosage of SSC utilization in the topsoil(0-15 cm) under 4-year continuous application of SSC. Under higher levels of the compost treatment, the heavy metals Cu and Zn were found to migrate into the 15-30 cm soil and 60-90 cm soil under the experimental condition. Nevertheless, the majority of Cu and Zn from SSC accumulated in topsoil and the highest accumulation rates could reach 75.3% for Cu and 85.9% for Zn. The contents of Cd, Pb increased significantly in topsoil after 4-year continuous application of SSC, and their increases could reach 57.2%-165.2% for Cd and 13%-34% for Pb compared with CK. At 60-90 cm soil, the contents of Cr, As and Pb were also significantly higher than those in CK treatment. Application of SSC not only caused accumulation of some heavy metals in topsoil but also leached heavy metals located in the subsurface soil down in this experiment. Continuous utilization of SSC increased Zn concentration of wheat grain, and the increase could reach 13.3%-47.9%. For the concentrations of Cr and Pb in wheat grain, the values exceeded the national food and healthy standards value (GB 2762-2012) in part of compost treatments. The cumulative ratio of heavy metals carried out by wheat were all below 10% after 4-year experiment, wheat grain carried much more Cu, Zn out than wheat straw, but it was opposite for Cr, As, Cd, Pb. The cumulative ratio of heavy metals carried by wheat decreased with the increasing level of SSC utilization. The amounts of heavy metals migrated to deeper soil should be considered when determining the environmental capacity of heavy metals in farmland soil.

Soil incubation experiments were conducted with different sources of manures containing heavy metals to evaluate the bioavailability of heavy metals (Cu and Zn) and their form transformation in different soils. This study may assist in developing strategies to ascertain the loads of heavy metals which entered into soils together with manures, and promote policies to evaluate the ecological risk in agriculture soils. The results showed that, during the six months of soil incubation, the pH value of acidic soil increased and the pH value of calcareous soil reduced. After adding chicken manures, the contents of available Cu in both calcareous and acid soils were significant lower than those in the equivalent inorganic salt treatments, but there was no significant difference between the treatments in the contents of available Zn in both calcareous and acid soils. Furthermore, there were also no significant differences between pig matures and the equivalent inorganic salt treatments in the contents of available Cu and Zn in both calcareous and acid soils. The results of form tendency showed that the main forms of Cu and Zn in both calcareous and acid soils, which entered into soils together with manures, were exchangeable, carbonate, Fe-Mn oxides, and organic. And the proportions of different heavy metals species in calcareous and acid soils were different with different manures sources. After six months of incubation, the contents of exchangeable and Fe-Mn oxides Cu, Zn were lower than those in the equivalent inorganic salt treatments, the contents of organics Cu and Zn were higher than those in the equivalent inorganic salt treatments, and other Cu and Zn forms in soils showed no difference with inorganic salt treatments.

This study was initiated to explore the effects of dynamic ozone (O3) exposure on soil microbial biomass and phospholipid fatty acids (PLFAs) under potted rice. A pulse-chase labeling experiment was designed to expose potted rice with 13CO2 for 6 h after one and two months, the rice were fumigated by elevated O3 concentration with an 8 h mean of 110 nL · L(-1) (O3). The allocation of the assimilated 13C to soil microorganisms was estimated by analyzing the 13C profile of microbial phospholipid fatty acids (PLFAs). After one month O3 exposure, the soil microbial biomass carbon was not affected, while the 13C-microbial biomass was significantly decreased with elevated O3. Both the total and 13C microbial biomass carbon was remarkably lower than that of control treatment after two months O3 exposure. Principal components analysis of 13C-PLFA data showed that elevated O3 significantly changed soil microbial structure after two month exposures, while there was no difference of 13C-PLFA structure between control and elevated O3 treatments after one month exposure. Δδ13C per hundred thousand of individual PLFA was significantly affected by O3 after both one and two month exposures. Only did ozone change the relative abundance of individual 13C-PLFA (13C%) of bacterial fatty acids after one month exposure, while after two month exposures, the 13C% of fungal and actinomycetic fatty acids were markedly changed by elevated O3.

Study the serum level of HGF, Cys C and TGF-beta1 in type 2 diabetic nephropathy (DN), the infect of Pingshen decoction on those index. Selected 69 cases of 2 type DN and randomly divided into therapy group (36 cases) and control group (33 cases). The therapy group were treated with Pingshen decoction 1 dose/d, bid po. The control group were treated with NephritisShu tablet, 6 tablet, tid po. 8 weeks was a course. Before and after treatment, we examine the serum level of HGF, Cys C and TGF-beta1 by ELISA and immunonephelometry, and compare with 30 cases of healthy control group. The study demonstrates that before treatment, the serum level of HGF in both groups were significantly lower than healthy control group (P < 0.01), but Cys C, TGF-beta1 were significantly higher (P < 0.01). After treatment, the serum level of HGF of both groups were increased. The serum level of HGF of therapy group were significantly higher than of control group (P < 0.01), but the serum level of Cys C and TGF-beta1 were significantly lower than control group (P < 0.01). The serum level of HGF was correlated negatively with Cys C,TGF-beta1. In control group, the UAER, urine beta2-MG and quantity of 24-hour urine protein were significantly decreased after treatment (P < 0.01). The index of urine of therapy group were significantly lower than control group (P < 0.01). Results indicate that test of serum level of HGF and Cys C,TGF-beta1 of diabetic nephropathy have important clinical significance. Pingshen decoction can effectively intervene in the serum level of HGF and Cys C, TGF-beta1 and index of urine.