• Volume 38,Issue 3,2017 Table of Contents
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    • Cloning and sequence analysis of mRNA and promoter of pig FAM213B gene

      2017, 38(3):1-8. DOI: 10.7671/j.issn.1001-411X.2017.03.001

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      Abstract:【Objective】To obtain the complete mRNA and promoter sequences of pig FAM213B gene, and provide a basis for studying the mechanism of the FAM213B gene in regulating gestation establishment and embryo development of female pigs.【Method】The complete mRNA sequence of the FAM213B gene was obtained using 5′ and 3′RACE methods.The amino acid sequence similarities of different species were analyzed. The gene promoter was cloned, and its transcription activity was detected by the dual luciferase report system in porcine endometrial cells.【Result】The mRNA of pig FAM213Bgene was 808 bp in full length, including the 5′UTR, CDS and 3′UTR of 67, 609 (including the termination codon) and 132 bp (excluding poly A), respectively. A thioredoxin fold domain was predicted from the 17th to 106th amino acid residues. The obtained transcript and the other two computed transcripts all contained the thioredoxin fold domains, but the tertiary structures of three proteins were highly different. The amino acid sequence of pig FAM213B showed 94.03%, 93.03% and 91.54% similarities with those of goat, cattle and sheep, respectively. The cloned promoter sequence (-2 231/+30) of the FAM213B gene was linked with the dual luciferase report vector, and transfected into the endometrial cells. The promoter fragment could drive the expression of the downstream report gene. There were potential binding sites of transcription factors such as NFκB within the promoter. 【Conclusion】The complete sequence of the transcript of pig FAM213B gene is 808 bp. The FAM213B protein contains a thioredoxin fold domain. The FAM213B promoter (-2 231/+30) has strong transcription activity in porcine endometrial cells.

    • Effect of high-fat diet on mammary gland development of pubertal mice and the molecular mechanism

      2017, 38(3):9-14. DOI: 10.7671/j.issn.1001-411X.2017.03.002

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      Abstract:【Objective】 To investigate the effect of high-fat diet (HFD) on mammary gland development of pubertal mice and explore the possible underlying mechanisms.【Method】 Twenty 4-week-old Kunming female mice were randomly divided into control group and HFD group. The trial lasted for four weeks. The body weight and feed intake were recorded weekly. At the end of the trial, mammary glands were collected and weighed. The morphology and number of ducts were observed by using whole-mount and HE staining. Western blot was used to analyze the expressions of insulin-like growth factor 1 (IGF-1), proliferation related signaling pathway proteins such as protein kinase B (Akt) and extracellular regulated protein kinases (ErK), as well as inflammation related signaling pathway proteins, including toll-like receptor 4 (TLR4), c-Jun N-terminal kinase (JNK) and inhibitor of nuclear factor kappa-B kinase (IKK) in the mammary glands.【Result】 The feed intake of the HFD group was significantly lower than that of control group(P<0.05), There was no significant difference in energy intakes between two groups. The body weight gain of HFD group was significantly higher than that of control group (P<0.05). In addition, HFD significantly increased mammary gland weight and the ratio of mammary gland weight to body weight (P<0.01). The results of whole-mount and HE staining demonstrated that the mammary gland development of HFD group mice were markedly inhibited, with significantly decreased duct number, duct density and number of terminal end buds (P<0.01). HFD significantly inhibited IGF-1 expression and the phosphorylation of Akt, Erk and IKK in mammary glands (P<0.01 or 0.05), while significantly promoted TLR4 expression (P<0.01) and JNK phosphorylation (P<0.05). 【Conclusion】 HFD can suppress mammary gland development of pubertal mice, which might result from the inhibiton of proliferative signals and stimulation of inflammatory signals.

    • Establishment and application of visual RT-LAMP technology for detecting bovine ephemeral fever virus

      2017, 38(3):15-20. DOI: 10.7671/j.issn.1001-411X.2017.03.003

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      Abstract:【Objective】To develop a rapid, convenient and visual molecular assay for detecting bovine ephemeral fever virus (BEFV). 【Method】Two pairs of primers based on six conserved regions in G protein gene of BEFV were designed, and the visual reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for detecting BEFV was developed. The reaction conditions of RT-LAMP assay were optimized, and the assay was compared with PCR.【Result】 The reaction ladder bands from the RTLAMP assay were most obvious when the RT-LAMP reaction system contained 3 mmol·L-1 Mg2+,0.4 mol·L-1 betaine and 1.2 μmol·L-1 dNTPs mix, the ratio of inner to outer primers was 8∶1, and the reaction temperature was 63 ℃. Clear reaction ladder bands were observed after 40 min of reaction. The established RT-LAMP assay had excellent specificity with only BEFV being amplified. The sensitivity was 10 times higher than that of ordinary PCR.【Conclusion】The visual RT-LAMP assay is easy to operate and highly specific, and the results can be conveniently determined. This method can be used for the rapid detection of bovine epidemic fever.

    • Influence of substituent groups on the antibacterial effect of pleuromutilin derivatives with thiadiazole moiety against Mycoplasma gallisepticum

      2017, 38(3):21-25. DOI: 10.7671/j.issn.1001-411X.2017.03.004

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      Abstract:【Objective】 To provide experimental data for the research and development of new antibacterials against Mycoplasma gallisepticum.【Method】Eighteen analogues of pleuromutilin possessing thiadiazole moieties at the C14 chains were synthesized. High resolution mass spectrometry was used to verify the structures of the synthesized compounds. Influence of substituted benzene on the antibacterial effects of these pleuromutilin derivatives against M. gallisepticum were investigated by in vitro drug sensitivity tests.【Result】The obtained MIC values revealed that analogues 12, 15 and 17 exhibited potential antibacterial activities against M. gallisepticum S6 strain with MIC of 0.125 0 μg·mL-1. Analogue 18 and Tiamulin (control) showed the most potent antibacterial activities against S6 strain in vitro with MIC of 0.015 6μg·mL-1. Analogue 17, which was the product from benzoylation of the amino group of analogue 18, had lower antibacterial activity compared with analogue 18.【Conclusion】 Analogue 18 can be used as a candidate compound for further development of antibacterials against M. gallisepticum.

    • Effects of application dosages of bacterial manure with chemical fertilizer on soil fertility

      2017, 38(3):26-31. DOI: 10.7671/j.issn.1001-411X.2017.03.005

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      Abstract:【Objective】 To find a suitable ratio of bacterial manure and chemical fertilizer, and guide fertilizing in tobacco field in Nanxiong area, Guangdong Province.【Method】Bacterial manure was prepared by fermenting organic manure with beneficial microbial strains including nitrogen fixation and phosphate solubilizing bacteria (Azotobacter sp. x34), potassium dissolving bacteria(Bacillus sp. jb21)and photosynthetic bacteria (Rubrivivax gelatinosus sbg11). Treatments with different dosages of bacterial manure, including CK (water), T1 (chemical fertilizer), T2 (low dosage of bacterial manure + chemical fertilizer), T3 (medium dosage of bacterial manure + chemical fertilizer) and T4 (high dosage of bacterial manure + chemical fertilizer), were applied to the tobacco field. The ratio of base manure to topdressing for each plant was 1∶1. Low, medium and high dosages of bacterial manure were corresponding to 10, 20 and 40 g of base manure per plant respectively. All treatments were the same in their total nitrogen, phosphorus and potassium contents.【Result】Under the field condition, the treatments with both bacterial manure and chemical fertilizer effectively increased the soil organic matter contents, significantly increased the contents of alkali-hydrolysable nitrogen, available phosphorus and available potassium in soil, improved soil respiration intensity, effectively increased the number of bacteria and actinomycetes in soil, and reduced the number of fungi.【Conclusion】The medium dosage (20 g base manure and 20 g topdressing ) of bacterial manure applied in the T3 treatment has the best effects, which is the recommended dosage of the bacterial manure.

    • Genetic diversity analysis of main agronomic traits in Ricinus communis germplasm resources

      2017, 38(3):32-38. DOI: 10.7671/j.issn.1001-411X.2017.03.006

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      Abstract:【Objective】To study the genetic diversity of castor (Ricinus communis)germplasm resources, reveal the characteristic and distribution of excellent germplasm, and provide a theoretical basis for castor germplasm resources innovation and breed improvement.【Method】Fourty castor germplasm resources from China and abroad were used as material, and 20 traits were assessed by the clustering method and principal component analysis. The effects of castor quantitative characters on yield per plant were analayzed.【Result】The results of cluster analysis showed 40 germplasm resources belonged to five groups (I-V). Group I was the parents of progenies with large raceme, group II was the parents of progenies with large seed size and high yield potential, group III was the parents of progenies with small seed size, more branch and capsule, group IV was the parents of progenies with high yield, and group V was the parents of progenies with both large raceme and seed size. According to the results of principal component analysis, thirteen quantitative traits were classified to five major factors, namely bearing height of primary raceme, effective capsule number, capsule number of primary raceme, hundred-grain weight and effective raceme number of single plant. The cumulative contribution was about 87.06%, and the bearing height of primary raceme was the essential factor.【Conclusion】Fourty germplasm resources possess rich germplasm types and different traits, and might be used as excellent germplasm materials for breeding in future.

    • SSR analysis on genetic diversity of peach cultivars and comparison of different genetic similarity coefficients

      2017, 38(3):39-45. DOI: 10.7671/j.issn.1001-411X.2017.03.007

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      Abstract:【Objective】 To develop SSR primers based on peach ESTs in NCBI database, analyze genetic diversity of the major peach cultivars in Chengdu plain, investigate the applicability of different genetic similarity coefficients in SSR analysis of peach, and provide references for research on peach germplasm resources. 【Method】In total 100 pairs of SSR primers selected from NCBI-EST database were used in PCR amplification for 12 peach cultivars with various morphology. Twenty primers which had high polymorphism and stability, and evenly distributed in eight linkage groups were selected for PCR amplification of 40 peach cultivars. Five genetic similarity coefficients were used to analyze the amplification results. 【Result】Using 20 SSR primers, 68 polymorphic alleles were detected. The number of alleles per locus ranged from 2 to 5, with an average of 3.4. The polymorphism information content ranged from 0.36 to 0.73, and with an average of 0.54. The Jaccard genetic similarity coefficient ranged from 0.106 to 1.000. The Cophenetic correlation coefficient (rc) of Jaccard coefficient was the highest being 0.772, followed by Dice coefficient being 0.719. The consistency of consensus trees between Dice and Jaccard coefficients were the highest with CIc being 1.000. Nei’s gene diversity index was 0.603 and 0.374 respectively at the species level and the level of different classified groups, the corresponding Shannon’s information index was 1.041 and 0.591 respectively. The 40 peach cultivars were firstly divided into two major categories which were ornamental peach and edible peach, and then subdivided into different types of groups. The clustering result basically coincided with the traditional pedigree. 【Conclusion】The SSR primers developed based on peach ESTs in NCBI database have high polymorphism and can be used for SSR analysis of peach. Jaccard and Dice coefficients are the most appropriate for SSR analysis of peach. In general, the genetic diversity of peach is abundant, but variation of the honey peach group is relatively low, and germplasm innovation of this group needs to be improved.

    • Isolation, identification and characterization of two strains of Bacillus subtilis

      2017, 38(3):46-51. DOI: 10.7671/j.issn.1001-411X.2017.03.008

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      Abstract:【Objective】 To explore potential probiotics in order to develop microecological agents for aquiculture.【Method】Bacillus stains were isolated from the pond sediment and healthy carp (Carassius auratus) intestine. The strains were identified by the morphological, physiological and biochemical characteristics and 16S rRNA sequence analysis. The safety, high temperature tolerance, pH tolerance, antagonistic effects and enzyme production of the strains were studied.【Result】Two Bacillus strains were isolated and named B1 and B2. They were identified as B. subtilis by morphology, physiological and biochemical characteristics and 16S rRNA sequence analysis. The B1 and B2 strains had good safety, high temperature tolerance and strong tolerance of acid. They had good antibacterial activity against pathogenic Escherichia coli, Staphylococcus aureus, Aeromonas hydrophila and A. sobria in vitro, and had the ability to produce lipase, amylase, protease and cellulase. 【Conclusion】Two B. subtilis strains were isolated, and both can be used as candidates for developing microecological agents for aquiculture.

    • RFLP analysis of the ribosomal DNA ITS regions of four physiological races of Fusarium oxysporum f. sp. cubense

      2017, 38(3):52-56. DOI: 10.7671/j.issn.1001-411X.2017.03.009

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      Abstract:【Objective】 To clarify the phylogenetic relationship of four physiological races of Fusarium oxysporum f. sp. cubense (Foc), the causal agent of fusarial wilt of banana.【Method】The ribosomal DNA internal transcribed spacer (ITS) regions of the four physiological races of Foc were first amplified using PCR technique, and then RFLP analysis of the ITS products of these races were performed using three restriction endonucleases including AIu I, Hpa IIandTaq I.【Result】A single 568 bp ITS fragment was amplified specifically from eight strains belonging to four races, respectively, but there was no obvious polymorphism among these races. RFLP analysis of the ITS products from these races showed that the differences among races were very small. 【Conclusion】 PCR-RFLP technique was unsuitable to be used as the identification basis for the physiological races of Foc.

    • Effect of pendimethalin on soil enzyme activities in cotton field

      2017, 38(3):57-63. DOI: 10.7671/j.issn.1001-411X.2017.03.010

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      Abstract:【Objective】To study the effects of pendimethalin on soil enzyme activities in cotton field.【Method】Pendimethalin at different concentrations (0,2 700, 4 050, 5 400 g·hm-2) were applied to cotton field. Changes in soil enzyme activities at different soil depth and treatment time were investigated.【Result】After treating with pendimethalin,alkaline phosphatase activity was substantially inhibited, and was inhibited the most at the soil depth of 5-10 cm 40 days after treatment.The inhibition rates of 2 700, 4 050 and 5 400 g·hm-2 treatments were 93.79%, 90.77% and 87.43% respectively. Urease activity had been continuously activated. Sucrase and dehydrogenase activities increased with the concentration of pendimethalin increasing, and the enhancements of the soil surface were significantly stronger than those at the soil depth of 10-20 cm. Catalase at the soil depth of 0-10 cm was firstly inhibited and then activated with the treatment time increasing.【Conclusion】Pendimethalin can activate urease and catalase, inhibit alkaline phosphatase, and reduce the soil available phosphorus content in cotton field. Longterm application of pendimethalin can cause soil nutrient imbalance.

    • Study on the metabolites of a mangrove endophytic fungus Fusarium sp.

      2017, 38(3):64-69. DOI: 10.7671/j.issn.1001-411X.2017.03.011

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      Abstract:【Objective】 To study the metabolites of a mangrove fungus Fusarium sp. R5. 【Method】The fermented filtrate of R5 fungus was isolated by silica gel column chromatography. The structures of the metabolites were characterized by spectral analyses. The antifungal activities were investigated using the paper disc-agar diffusion method. 【Result】Ten compounds were isolated and identified as 5-hydroxymethyl-2-furaldehyde (compound 1), (3R,4R)-cis-4-hydroxymellein (compound 2), (3R,4R)-cis-4,7dihydroxymellein (compound 3), clavatol (compound 4), flazine (compound 5), ergosta-4, 6, 8(14), 22-tetraen-3-one (compound 6), β-sitosterol (compound 7), 3β-cholest-5-en-3-ol (compound 8), butanedioic acid and maleic acid. At the concentration of 250 μg·mL-1, compound 5 showed high inhibitory activity against Colletotrichum musae (Berk.&M. A. Curtis) Arx., compounds 5 and 6 showed moderate inhibitory activity against F. oxysporum and F. graminearum Schw.【Conclusion】Compounds 1~8 are isolated from Fusarium sp. and among them, compounds 5 and 6 could be used as the lead compounds in antifungal agents.

    • Effects of habitats on photosynthesis characteristics of Cyclobalanopsis gilva

      2017, 38(3):70-78. DOI: 10.7671/j.issn.1001-411X.2017.03.012

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      Abstract:【Objective】 To analyze the photosynthetic adaptations of Cyclobalanopsis gilva to different habitats, and provide theoretical and data supports for scientific breeding and cultivation.【Method】Three natural populations of C. gilva in different habitats were studied. Diurnal changes in photosynthetic parameters of C. gilva under natural condition were measured using LI-6400 portable photosynthesis system. The light response curves were obtained.【Result】Under different habitats, net photosynthetic rate(Pn) and transpiration rate(Tr) of C. gilva had similar changing patterns, both reached peak at 10:00 and 14:00, and were lowest at 13:00. Leaf temperature (θL), photosynthetically active radiation(PAR), and stomatal conductance(Gs) were all strongly positively correlated with Pn. The ability of using light for C. gilva was influenced by habitat as shown by the light response curves; C. gilva grown on flat between mountains had the best ability of using light, followed by C. gilva grown on southern slope of mountain, and then northern slope of mountain. Light compensation points (Lcp) were low in all three habitats. Lcp was the lowest (2.257 mol·m-2·s-1) for C. gilva grown on northern slope of mountain, and around 51 mol·m-2·s-1 for C. gilva grown on flat between mountains and southern slope of mountain. Light saturation point (Lsp) was the highest for C. gilva grown on flat between mountains, followed by C. gilva grown on southern slope of mountain, and then northern slope of mountain.【Conclusion】C. gilva had strong adaptability to all three habitats. C. gilva grown on flat between mountains and southern slope of mountain have adapted to longer light duration and higher light intensity, and have strong photosynthetic capacity and ability of using hight light intensity. C. gilva grown on southern slope of mountain have the ability of using weak light intensity. Long adaptation to different habitats was the main cause of photosynthetic capacity differences of C. gilva.

    • Adaptability evaluations of Eucalyptus clones at six stand conditions in Southern China

      2017, 38(3):79-86. DOI: 10.7671/j.issn.1001-411X.2017.03.013

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      Abstract:【Objective】To evaluate scientifically the resistance and adaptability of Eucalyptus clones at different stand conditions, and provide a scientific basis for planting proper trees at different areas. 【Method】The adaptability of ten eucalyptus clones were compared at six sites in Guangdong and Guangxi Provinces. The survival rates, tree heights, diameters at breast height, incidence of disease, wind damage rates and volumes were studied.【Result】Hybrid Eucalyptus clones kept excellent characteristics of strong adaptability, and the survival rates were above 95% except for LH9224(93.7%). There were large differences in disease resistance among clones at different sites. LH9224 had the highest incidence of disease (averaged over 6.7%), while LH9211 had the highest disease resistance with no diseased plant. The incidence of disease was the highest (3.63%) under heavy clay soil condition, and 0 under light sandy soil condition. There were significant differences in wind resistance among clones. Under the average wind speed of nine grade, the wind damage rates for the 1.5-year-old young forests ranged from 5% to 64%, DH3327 and DH3226 had the poorest wind resistance with above 60% wind damage rates, and LH9211, LH9224 and Sh1 had the highest wind resistance with below 10% wind damage rates. For the 6-year-old forests, M1 and DH2012 had the poorest wind resistance with above 12% windthrow rates under the 11-grade wind. There were highly significant differences in growth speed among clones, and the mean annual increments(MAI)for the 8.5-year-old forests ranged from 17.19 to 38.87 m3·hm-2·a-1. DH3213 at Qinlian had the fastest growth, while U6 at Qinlian had the least growth. The average MAI from six sites ranged from 12.24 to 26.97 m3·hm-2·a-1 for ten Eucalyptus clones. 【Conclusion】In typhoon-prone areas, LH9224 clone with strong wind resistance is suggested to be planted, while DH3213 and DH3327 clones are the desired strains for the inland areas with little wind damage. In Tangjia area with the lowest survival rate and the highest incidence of disease, we suggest planting M1 with the highest survival rate and LH9211 with the highest disease resistance, and for Wuchuan and Suixi areas with low volume production, the best choice is DH3213 with the fastest growth rate.

    • Effects of light intensity and container size on growth of one-year-old seedlings of Quercus nuttallii

      2017, 38(3):87-92. DOI: 10.7671/j.issn.1001-411X.2017.03.014

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      Abstract:【Objective】 To study the growth rhythm of Nuttall oak (Quercus nuttallii) seedlings under different light intensities, find out the appropriate light intensity and container size for seedling growth, and provide a theoretical basis and guidance for cultivation and management of container seedlings in the future. 【Method】Single factor experiments were used to study the effects of light intensities (50%,75% and 100%)and container sizes(8 cm×10 cm,10 cm×15 cm and 15 cm×20 cm)on seedling growth. Logistic equations were used to fit the growth of seedling height and ground diameter under different light intensities. 【Result】At the early stage of growth (before June 26), shading clearly promoted growth of seedling height. By the end of the growth season, the increments of seedling height were not significantly different among light treatments. Throughout the growth season, ground diameter was significantly enhanced by shading with the optimal light intensity being 75%. The growth rhythms of seedling height and ground diameter were generally consistent. Shading shifted the initial and final stages of linear growth of seedling height to earlier time. The linear growth days (LGD) of 50% light was 21 days shorter compared to 100% light, and the LGD of 75% and 100% light were not significantly different, while the LGD of ground diameter of 50% and 100% light were longer 19 days and 16 days than that of 75% light, respectively. LGD of seedlings height was substantially longer than that of ground diameter,indicating that when seedling height growth stopped, the ground diameter continued to grow. Container size significantly influenced seedling height, ground diameter and the ratio of height to diameter. Seedling height and ground diameter significantly increased by larger containers, and both were the highest (98.83 cm and 11.68 mm) in the 15 cm×20 cm container. 【Conclusion】 Larger container (15 cm×20 cm) should be used to cultivate high quality seedlings of Q. nuttallii. Considering seedling height and ground diameter, we should use 50% light at the early stage of growth, then 75% light during the linear growth stage, and full light starting from Fall. At the late stage, ground diameter should be used as the index for detecting the ending of growth.

    • Calibration of discrete element model parameters for cohesive soil considering the cohesion between particles

      2017, 38(3):93-98. DOI: 10.7671/j.issn.1001-411X.2017.03.015

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      Abstract:【Objective】 To calibrate contact parameters and contact model parameters for the cohesive soil discrete element model. 【Method】The Hertz-Mindlin with JKR contact model which consider the cohesion between particles was employed for the repose angle simulation test. The simulation test was based on the results of physical test for angle of repose. The key parameters including JKR surface energy, coefficient of restitution, coefficient of static friction and coefficient of rolling friction were obtained from the GEMM (Generic EDEM material model) database. A Box-Behnken design was then used to perform the simulation test for repose angle in above value ranges. 【Result】The regression model for repose angle was acquired from the test results by multiple regression analysis. Analysis of variance showed that the model was extremely significant, and the relationship between experimental factors and repose angle was fitted to a quadratic polynomial with complex liner and quadratic interactions. The optimized solution was acquired by using 40.45° as the target of repose angle. The optimized solution was as follow, JKR surface energy was 7.91 J·m-2, coefficient of restitution was 0.66, coefficient of static friction was 0.83, and coefficient of rolling friction was 0.25. The optimized solution was then used for simulation test and the obtained repose angle was 39.73°. The simulation test was highly matched with physical test on both angle and shape of repose. 【Conclusion】 For the soil sample used in this research, the optimized parameters can be used for further simulation of kinematics and dynamics between cohesive soil and soil contact components, and for providing the motion characteristics of cohesive soil under the actions of soil contact components.

    • Design and test of a contact mechanics model for papaya picking

      2017, 38(3):99-105. DOI: 10.7671/j.issn.1001-411X.2017.03.016

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      Abstract:【Objective】 For stably picking papaya without damage.【Method】 A clamping plan of papaya was designed by means of three-finger clamping symmetrically and wringing,and the equilibrium equation of contact force was constructed. On the basis of force screw theory, the clamping stability was analyzed. The picking contact mechanics model was formulated, and a picking test for papaya was conducted. 【Result】 There were no obvious deformation, crack or indentation on the surfaces of papaya samples. The pulp at the clamping position had no obvious color change or bruise after leaving for 24 hours at room temperature. The maximum clamping force was far less than the pressure limit on the transverse diameter of ripe papaya at the elastic deformation stage. Papaya mass and torque moment were correlated closely with transverse diameter, vertical diameter, stalk length and diameter of the twisted stalk. Mass multiple linear regression analysis achieved extremely significant level, and twist torque linear regression analysis reached significant level. There were good trend consistency between theoretical clamping forces and the measured clamping forces. The measured clamping forces were higher than theoretical values, but the maximum deviation was less than 20%. 【Conclusion】 The picking scheme can stably clamp papaya without mechanical damage. The papaya picking contact mechanics model is correct and practical. The research can provide a basis for designing papaya picking end-effector and controlling clamping force.

    • Finite element analysis of mechanical properties of Artemisia selengensis stalk

      2017, 38(3):106-111. DOI: 10.7671/j.issn.1001-411X.2017.03.017

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      Abstract:【Objective】 To establish a stalk flexible model of Artemisia selengensis.【Method】Based on the physical parameters of the stalk of A. selengensis, the finite element model of stalk was established by using the ANSYS software. The axial and radial mechanical properties of A. selengensis stalk at different growth positions under compression were studied. The model calculation value and experimental value were analyzed and compared.【Result】The maximum deviation of model calculation value and experimental value was 14.46%. A. selengensis stalk had anisotropic characteristics with its axial compression mechanical properties being much better compared to the radial. At three different positions, the stem breakage occurred on the edges of both ends of the loading surface under radial compression,while under axial compression, the stem breakage occurred on the loading surface, and the stress gradually receded from close to the loading area to surroundings. 【Conclusion】The mechanical properties of A. selengensis stalk can be analyzed by model simulation, and the results can provide theoretical references for reducing mechanical damage during harvesting, transportation, processing and storage of A. selengensis and for designing A. selengensis harvest machine.

    • Water purification effects and improvement tests of automatic aerators

      2017, 38(3):112-117. DOI: 10.7671/j.issn.1001-411X.2017.03.018

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      Abstract:【Objective】To provide solutions for sealing and installation inconvenience of the automatic aerator during breeding of mandarin fish. 【Method】Through the whole cycle of mandarin fish breeding starting from July to November in 2014, fishponds tests were performed to study the cleaning cycle, measuring accuracy and controlling reliability of the automatic aerator. The impacts on aquaculture water quality and electricity consumption were evaluated. The sizes of the O-shape sealing ring and the triangle slot were changed to improve the sealing and installation convenience of the dissolved oxygen (DO) sensor. The sizes of the upper and lower chamfers were also changed to improve the installation convenience of the DO sensor. 【Result】During the whole breeding cycle, the average cleaning cycle of the automatic aerator was not significantly different compared with the Denmark OxyGuard DO monitor. The error of measured temperature was ±0.8 ℃, the error of measured DO content was ±0.6 mg·L-1, and the DO content of the controlled fishpond was higher than the set lower limit of 4 mg·L-1. Compared with manual control, the DO content of the controlled fishpond using the automatic aerator was higher with a peak value of 7 mg·L-1, the average ammonia nitrogen content in water was 35.9% lower, the average nitrite content was 50.7% lower, and the electricity was saved by 29.5%.【Conclusion】The automatic aerator is highly resistant to stain, can be conveniently cleaned, improves water quality and saves electricity during long-term use, meeting the requirements of the fishpond management. The automatic aerator has good sealing and can be conveniently installed, thus it is recommended for large-scale popularization.

    • Design of a farm product traceability system with QR code based on mobile internet

      2017, 38(3):118-124. DOI: 10.7671/j.issn.1001-411X.2017.03.019

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      Abstract:【Objective】 To establish a farm product traceability system using two-dimension code (QR code) based on mobile internet.【Method】The logical and physical structure of the farm product traceability system was studied. The principles of error collection code(ECC) based on Reed-Solomon(RS) code and the encoding algorithm of QR code were analyzed. The stained QR code was preprocessed by compressed sensing (CS) algorithm, and the result was compared with those from traditional denoising methods such as Gaussian, Disk, and Log algorithms. The relationship between QR code capacity and error correction, and the relationship between scanning pixels, staining position and image identifiablility have been studied. The parameters of mobile phone were identified.【Result】The lowest pixel of mobile phone scanning was two million, and CS was able to solve the staining problem of QR code effectively. The error bit rate (EBR) of CS was 0.040 1 when signal noise rate (SNR) was 10.7 dBm, which was lower than the result of Log method (0.042 5). The EBR of CS was 0.011 3 when SNR was 11.7 dBm, which was lower than the result of Gaussian method (0.014 7). The peak signal to noise ratio (PSNR) of QR code images processed by CS were all higher than 10 dBm. The mask area had a major impact on position region, and the average accuracy rates of recognition at position region and encoding region were 87.68% and 91.24% respectively. 【Conclusion】 The farm product traceability system enables integrity and traceability of the target information, solves the problem of information delay in planting, processing,circulation and sale of agricultural products.