How can China achieve its goal of peaking carbon emissions at minimal cost? A research perspective from shadow price and optimal allocation of carbon emissions.

The Chinese government has declared a determination at the 75th United Nations General Assembly that China will improve its independent contribution and adopt more powerful measures to peak the carbon emissions before 2030. However, such strict implementation of carbon reduction policies is bound to bring the cost of sacrificing economic development. In such a context, this paper tries to use shadow price to measure the average social cost of emission reduction, marginal abatement cost to depict the pressure to reduce carbon emissions based on non-radial distance function, and provides an optimal scheme for provincial emission reduction to minimize the national cost of emission reduction based on variable-coefficient model. Results show that: First, the average value of shadow price is 15.91 and varies widely among regions, which means on average reducing one unit of carbon emissions will sacrifice 15.914 yuan RMB of economic output, and there exists possibility of carbon transactions across regions; Second, on the one hand, marginal abatement cost of carbon emission for most regions presents an upward tendency over time, which means greater economic costs have to be sacrificed with economic development in the future; On the other hand, marginal abatement cost is much higher in regions with high economic level than that in the economically undeveloped areas, which indicates reducing carbon emissions is becoming increasingly difficult and would pay more economical cost in economically developed regions; Third, the optional allocation scheme of CO2 reduction derived from this research is better than administrative ways of Grandfathering and Benchmarking in terms of minimizing emission reduction cost. Results of this paper indicate that larger carbon trading market can be implemented in China to economically fulfill the commitment of peaking carbon emissions.

Isolation, identification, and pathogenicity of Lelliottia amnigena causing soft rot of potato tuber in China.

Potato (Solanum tuberosum L.) is regarded as the fourth most important food crop because of its economic and nutritional benefits. This crop suffers significant annual losses due to a variety of phytopathogens. Bacterial soft rot disease is one of the most serious diseases that cause significant losses in potato yield all over the world. Therefore, identification of a soft rot pathogen is critical for easy control, as each pathogen has distinct ways of being controlled. Lelliottia amnigena is a subgroup of the genus Enterobacter with many species associated with crop plants, making its classification difficult and complex. Therefore, this study focused on the isolation and identification of a newly L. amnigena from rotten potato tuber obtained from the field after harvest, Lanzhou City, China. Four strains designated as PC2, PC3, PC4 and PC5 were isolated from the same rotting potato tuber. Pathogenicity test showed that strain PC3 induced soft rot symptoms on healthy potato tubers. Koch's postulates were confirmed by re-isolating the strain PC3 in the inoculated tubers. Strain PC3 showed a convex, oval and smooth colony, measuring 0.9-1.3 1.8-3.6 µm under the microscopic observation. Phylogenetic analysis based on 16S rRNA, rpoB and atpD genes showed that strain PC3 species was 99.44%, 97.24%, and 100%, closely related to L. amnigena with accession numbers 240-a-etp (MN208158.1), FDAARGOS (CP023529.1) and R-6 (MN658356.1), respectively. The bacterial strain (PC3) was deposited in the Genbank with the accession number SUB10508072 PC3 OK447935. To the best of our knowledge, this is the first report of L. amnigena causing soft rot on potato tubers in China.

Potential of an endophytic bacteria Bacillus amyloliquefaciens 3-5 as biocontrol agent against potato scab.

To obtain a potential biocontrol agent for potato scab, 75 endophytic bacteria were isolated from the healthy potato tubers and strain 3-5 was selected as an optimal antagonistic bacterium against Streptomyces griseoplanus (Streptacidiphilus griseoplanus) causing potato scab. Strain 3-5 was identified as Bacillus amyloliquefaciens based on its morphological characteristics, 16S rDNA and gyrB gene sequence analysis. B. amyloliquefaciens 3-5 has biological functions of indole-3-acetic acid (IAA) production and nitrogen fixation. Polymerase chain reaction (PCR) detection revealed that B. amyloliquefaciens 3-5 had 6 diverse antibacterial substance synthesis genes, named bacD, bacAB, ituD, ituC, sfP and albF, which resulted in the production of bacilysin, iturin, surfactin and subtilosin. Field efficacy evaluation revealed that B. amyloliquefaciens 3-5 (solid fermentation) was successful in controlling potato scab with a 38.90 ± 3.2140% efficiency which is higher than other chemical bactericides except zhongshengmycin·oligosaccharins and kasugamycin·zhongshengmycin. The endophytic bacterium B. amyloliquefaciens 3-5 could be used as a biocontrol agent against potato scab due its control efficacy and environmental safety.

Identification and biological characterization of a new pathogen that causes potato scab in Gansu Province, China.

Potato scab caused by pathogenic Streptomyces is a serious soil-borne disease on potato. In this study, a new Streptomyces strain 5A-1 was isolated from potato samples in China. Based on morphological characteristics, 16S rDNA gene sequence analyses, it was identified as Streptomyces griseoplanus (Streptacidiphilus griseoplanus), pathogenicity of which was measured by the methods of small potato chips, radish slices and potato pot trial inoculation. Moreover, the pathogenic genes txtAB and tomA from the Streptomyces pathogenicity island (PAI) were detected. Determination of biological characteristics showed that the optimal temperature for the growth of S. griseoplanus strain 5A-1 was 25 °C, the optimal light condition was darkness, the optimal pH value was 8.5 and the most preferred carbon source and nitrogen source is glucose and aspartate, respectively. To our knowledge, it is the first report for S. griseoplanus, as a new pathogen, to cause potato scab.

First report of Boeremia exigua var. exigua causing branch blight on walnut in China.

Walnut (Juglans sinensis L.) is an important economic tree. Its fruit are rich in omega-3 essential fatty acids, which are valuable nutritionally (Cheon et al, 2013). In March 2019, severe branch blight of walnuts (cv. Qingxiang) were observed in two fields in Ganquan Town, Gansu Province, China (N 33°56'/E105°44'). The incidence was about 3% among 10,000 walnuts. Disease symptoms included fusiform or oval black lesions gradually expanded on the branches, blight and dieback of branches, reddish brown dead branch bark with lots of black small spots (pycnidia), and defoliation. To isolate pathogen, 30 diseased tissues collected from different trees were disinfected with 0.1% HgCl solution for 1 min, rinsed in sterilized water 3 times, and placed on potato dextrose agar (PDA) at 25℃ in the dark. About three days later, 4 fungal isolates (3-3, 3-6, 3-9 and H3) with similar morphological characteristics were obtained. Their colonies, with regular margin on OA, 6.1~6.8 cm diam. after 7 days, were loose, greenish olivaceous to olivaceous grey, velvety, floccose to woolly. The conidia (n=60) were 4.77 to 8.84 µm long (mean = 6.88 µm; SD ± 0.91 µm) × 1.71 to 3.89 µm wide (mean = 2.81 µm; SD ± 0.53 µm), cylindrical, ellipsoidal to oblong, hyaline and aseptate. Pycnidia (n=25) were 76.66 ~ 132.86µm diam. (mean = 102.93 µm; SD ± 12.15 µm), variable in shape and size, mostly globose to subglobose. These characteristics were similar to B. exigua var. exigua (Boeremia et al, 2004). Pathogenicity tests of four isolates were performed 3 times on 5 healthy 2-3 years old walnuts (cv. Qingxiang). Plants were wounded by insect needle No.6 and inoculated with 5 mm mycelium block grew on PDA medium or PDA medium as control and kept moist in climatic cabinet (> 85% RH, 25°C). After 3 days, oval black lesions were occurred on branches and gradually expanded, but control was asymptomatic. And original isolates were re-isolated from these diseased shoots. Genomic DNA of four isolates were extracted, and the internal transcribed spacer (ITS), ß-tubulin (tub2) and RNA polymerase II second largest subunit (rpb2) gene were amplified and sequenced using the primers ITS1/ITS4, Btub2Fd/Btub4Rd and RPB2-5F2/fRPB2-7CR (White et al, 1990; Woudenberg et al, 2009; Chen et al, 2015), respectively. Sequences were deposited in GenBank (accession no. ITS: MT154621, MT154622, MT154623, MT154624; tub2: MT223481, MT223482, MT223483, MT223484; rpb2: MW448152, MW448153, MW459982, MW459983), and compared with available sequences in NCBI. Results showed that ITS of four isolates have 100% sequence identity to Boeremia spp., tub2 and rpb2 have 100% sequence identity to B. exigua var. exigua (GenBank accession no. MN983734, MN983315) and B. exigua var. linicola (GenBank accession no. MN983785, MT920619). According to host specificity (Boeremia et al, 1976). A 106 conidium/mL spore suspension of four isolates or sterile water were inoculated on stem base of two-month old flax seedlings, placed in climatic cabinet (> 85% RH, 25°C) for moisturing and repeated three times. After two weeks, all inoculated plants still were asymptomatic, indicated that four isolates aren't B. exigua var. linicola. Therefore, they were identified as B. exigua var. exigua based on morphological characteristics, molecular analysis and pathogenicity tests. To our knowledge, this is the first report of B. exigua var. exigua causing walnut branch blight worldwide, which will provide further guidance for prevention and control of walnut branch blight.

First Report of Fusarium equiseti Causing Fusarium Wilt on Potato (Solanum tuberosum) in China.

Potato (Solanum tuberosum) is one of the most economically important crops in China, containing carbohydrates, protein, fiber, numerous vitamins and minerals, and is a heart healthy food (Raidl, 2020). Potato infected by Fusarium spp. exhibits quality and yield decline, and even death. In infected plants, the upper leaves exhibit chlorosis, the lower leaves wither and the vascular bundles of stems and tubers turn yellow, and then tan to brown. In August 2018, symptomatic potato stems and roots were collected from Zhangye city, Gansu province, China. Diseased stem tissues were surface sterilized with 75% alcohol for 30 s, and then rinsed in sterile water. The tissue pieces were placed on potato dextrose agar (PDA) and incubated at 25°C in darkness. Fusarium-like colonies were consistently isolated and three monoconidial isolates were obtained. Isolate 3SMJ-2 was selected as a representative for morphological characterization, molecular analysis, and pathogenicity tests. 3SMJ-2 was inoculated in PDA liquid medium, grown on a shaker for 7 days at 25℃ to obtain a mix suspension of hypha fragments and spores (107 spores/mL). Healthy potato plants, named "Xin Daping" and were planted in pots (17 cm diameter by 12 cm) filled with 2L of sterile soil per pot. After 8 weeks, the plants were inoculated with the inoculum or distilled water. Then they were incubated in growth chambers at 25°C under a 12-h/12-h day/night potato period with 90% relative humidity for 24 h. For each treatment, 3 pots were inoculated. After 50 days, 100% of the inoculated potato plants exhibited wilt symptoms similar to those in the field but the control plants were symptomless. A Fusarium identical to strain 3SMJ-2 was re-isolated from symptomatic potato plants to fulfilling Koch's postulates. Morphological characteristics of the re-isolated strain were identical to the original isolate, which confirmed pathogenicity of strain 3SMJ-2 originally isolated from the potatoes. Colonies of 3SMJ-2 were white with short conidiophores, a few microconidia and sickle-shaped macroconidia (25.2 to 42.9× 3.1 to 4.6 µm) (n = 60) with 4~7 septa, and mostly 5 septa, after cultivated on PDA in an incubator at 25℃ for 14 days. Spherical terminal or intercalary chlamydospores were observed on the mycelium. Strain 3SMJ-2 was identified preliminarily as Fusarium sp. based on morphological characteristics (Leslie et al., 2006). Genomic DNA was extracted from 3SMJ-2 using the OMEGA Fungal DNA kit according to the manufacturer's protocol. The internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF) and RNA polymerase II second largest subunit (RPB2) were amplified using ITS1/ITS4 (White et al., 1990), Ef728M/Tef1R (Stepien et al., 2012) and 5F2 /7cR (O'Donnell et al., 2007), respectively. After sequencing by Beijing TSINGKE Biological Technology Co., Ltd., 3 fragments of approximately 519 bp, 587 bp and 1059 bp from the strain 3SMJ-2 were deposited in GenBank as MN420681, MW561963 and MW561964. The ITS, TEF and RPB2 sequences were 100%, 100% and 99.8% identical to those of F.equiseti (KY365589, KF499577, and MH582110). Based on the pathogenicity tests, morphological characteristics and molecular analyses, we identified the strain 3SMJ-2 as F. equiseti, the pathogen causing Fusarium wilt on potato in Zhangye City. Although, F. equiseti has been reported to cause root rot of cowpea (Li et al., 2017) and sugar beet (Cao et al., 2018) in China. To our knowledge, this is the first report confirming F. equiseti causing potato wilt in China. Potato is an economically important crop in Gansu and the occurrence of the new disease caused by F. equiseti on potato needs to be properly managed to reduce yield loss.

Nonoxidative Microwave Radiation Roasting of Bastnasite Concentrate and Kinetics of Hydrochloric Acid Leaching Process.

Herein, a new clean extraction technology for the decomposition of bastnasite concentrate by utilizing the microwave radiation is proposed, which prevented Ce(III) from being oxidized to its tetravalent form. The process includes microwave radiation roasting to nonoxidatively decompose the bastnasite concentrate, mechanism analysis of Ce(III) not being oxidized to Ce(IV), hydrochloric acid leaching of the nonoxidative roasted ore, and kinetics analysis of the leaching process. The experiments were carried out concentrating on the effect of roasting temperature and holding time on the decomposition rate of the bastnasite concentrate and the oxidation rate of cerium and the effect of acidity, liquid-solid ratio, leaching temperature, and stirring rate on the leaching kinetics of the nonoxidative roasting ore. When the roasting temperature is 1100 °C, the holding time is 20 min, and the m(C)/m(REFCO3) ratio is 0.2, the results show that the leaching efficiency of rare earths can reach 85.45% under the conditions 3 mol/L HCl, 90 °C, 60 min, 9 mL/g liquid-solid ratio, and 300 rpm stirring rate. The X-ray diffraction and scanning electron microscopy analyses of the samples before and after acid leaching show that the rare earth oxides were completely leached and Ce(III) was not oxidized to its tetravalent form. The apparent activation energies of leaching rare earths were calculated as 14.326 kJ/mol, and the HCl leaching process can be described by a new variant of the shrinking-core model, in which both the interfacial transfer and the diffusion through the product layer influenced the reaction rate. Furthermore, a semiempirical rate equation was created to describe the leaching process of the nonoxidative roasted ore.

Synthesis of superamphiphobic breathable membranes utilizing SiO2 nanoparticles decorated fluorinated polyurethane nanofibers.

Superamphiphobic nanofibrous membranes exhibiting robust water/oil proof and breathable performances were prepared by the combination of a novel synthesized fluorinated polyurethane (FPU) containing a terminal perfluoroalkane segment and incorporated SiO(2) nanoparticles (SiO(2) NPs). By employing the FPU/SiO(2) NPs incorporation, the hybrid membranes possess superhydrophobicity with a water contact angle of 165° and superoleophobicity with an oil contact angle of 151°. Surface morphological studies have indicated that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. The quantitative hierarchical roughness analysis using N(2) adsorption method has confirmed a major contribution of SiO(2) NPs on enhancing the porous structure, and a detailed correlation between the fractal dimension and amphiphobicity is proposed. Furthermore, a designed concept test shows that the as-prepared membranes could load 1.5 kg water or oil at the same time maintained an extremely high air permeability of 2 L min(-1), suggesting their use as promising materials for a variety of potential applications in protective clothing, bioseparation, water purification, tissue engineering, microfluidic systems, etc., and also provided new insight into the design and development of functional hybrid membranes based on FPU.