Dynamics and screening characteristics of a vibrating screen with variable elliptical trace

The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness.A new vibrating screen with variable elliptical trace was proposed.An accurate mechanical model was constructed according to the required structural motion features.Applying multi-degree-of-freedom vibration theory,characteristics of the vibrating screen was analyzed.Kinematics parameters of the vibrating screen which motion traces were linear,circular or elliptical were obtained.The stable solutions of the dynamic equations gave the motions of the vibrating screen by means of computer simulations.Technological parameters,including amplitude,movement velocity and throwing index,of five specific points along the screen surface were gained by theoretical calculation.The results show that the traces of the new designed vibrating screen follow the ideal screening motion.The screening efficiency and processing capacity may thus be effectively improved.

Biological Characteristics of Marssonina coronaria and Its Pesticide Screening in Laboratory

Chaenomeles sinensis spot leaf cast is one of the most serious diseases in production. The biological characteristics of Marssonina coronaria were studied and the suitable pesticides against the pathogen were screened in the paper, to provide a scientific basis for studies on epidemic regularity and control of the disease. The effects of different nutrition and environmental conditions as well as nine pesticides on the mycelial growth of M. coronaria were investigated in this paper. The results indicated that the mycelium grew well on the PDA medium with pH of 7.0, and soluble starch and urea were suitable carbon and nitrogen sources, respec- tively. The lethal temperature was 45 ~C, and the light-dark alternation （12/12h） was benefit for mycelial growth. Among the nine tested pesticides, carbendazim was the most effective agent, with ECs0 of 8.78 mg/L, and its relative inhibition rate was 85 % under the recommended concentration of 1.0 mg/L. Mancozeb was the least effective agent, and its relative inhibition rate was only 40.8% under the recommended concentration of 1.67 mg/L.

Isolation and Screening of Broad-spectrum Antibacterial Substance-producing Lactobacillus Strains

[ Objective ] This study aimed to screen bread-spectrum antibacterial substance-preducing Lactobacillus strains and previde scientific reference for food preservation. [ Method] Using homemade pickles as experimental materials, LactobaciUus strains were preliminarily isolated with BCP culture medium containing bremocresol purple; Lactobacillus supernatant was prepared using MRS medium containing CaCO3 ; subsequently, Lactobacillus strains with antibacterial activity against four indicator bacteria were obtained ; after eliminating the interference of acid and hydrogen peroxide, antibacterial active strains were re-screened by ther- mal stability test and activity persistence test. [ Result ] After preliminary screening and re-screening, five Lactobacillus strains with antibacterial effects against Escherichia coli, Bacillus subtilis, Staphyloccacus aureus and Saccharomyces cerevisiae were obtained. To be specific, LP-6 strain exhibited significant antibacterial activity after eliminating the interference of acid and hydrogen perexide. Results of thermal stability test and activity persistence test indicates that the fermentation supernatant of LP-6 strain still had significant antibacterial activity after heating at 121 ℃ for 15 rain and after preservation for three months. [ Conclusion] LP-6 strain can produce bacteriocin-like antibacterial substances with wide application value in food industry.

Biological Characteristics of Persimmon Anthracnose Pathogen Colletotrichum horii and Screening of Inhibitory Fungicides

This experiment studied the biological characteristics of Colletotrichum horii causing persimmon anthracnose using the crossing method and blood cell counting plate method,and screened inhibitory fungicides via assessing the effects of 16 common fungicides on the mycelial growth and spore germination. The results showed that the most suitable temperature for mycelial growth of C. horri is 25℃,the most suitable temperature for spore germination is 28℃; the suitable p H for mycelial growth of C. horri is 4. 0-6. 0,the most suitable p H for spore germination is 4. 0; the optimal carbon source is glucose and maltose,and the optimal source of nitrogen is beef extract. Among the 16 common fungicides,33. 5% copper quinolate SC,25% bromothalonil EC and 70% Mancozeb WP have the optimal inhibitory effects on the mycelial growth and spore germination of C. horri,and can be used as preferred agent for prevention and control of persimmon anthracnose,followed by70% Polyram WG,400 g/L Flusilazole EC and 50% Thiram WP,which can be used as alternative agents. The results are expected to provide experimental basis for effective control of persimmon anthracnose.

Identification,Characterization,and Probiotic Potentials of Lactobacillus pentosus SF-1

In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.

Screening and degradation characteristics of a tylosin-degrading strain

Antibiotics residues have been accumulating in the environment day by day due to overuse of antibiotics.Recalcitrant antibiotic residues,such as tylosin(TYL),can cause serious environmental problems,which makes it important to eliminate TYL from the environment.It is important to eliminate TYL from the environment.In this study,a strain was isolated and purified from fermentation by-product that came from a TYL production factory.The TYL degrading strain was identified by its morphology,physiological and biochemical reactions and sequencing the PCR-amplified fragments of its 16 S r DNAcoding genes.The temperature,shaking speed,initial TYL concentration,p H and inoculum sizes were investigated under simulated conditions by using single factor tests.The results showed that TYL2,a high efficient strain was isolated and was identified as Brevibacillus borstelensis.The degradation rate of TYL by this strain could reach to 75%with an initial concentration of 25 mg L^-1 within 7 days under conditions of 7%B.borstelensis(v/v,2×108 CFU m L^-1)at p H 7.0 and at 35°C.It is interesting that this strain has a very strong ability to degrade the TYL in natural sewage with the degradation rate of 65%within 7 days.This result could be helpful for the degradation of TYL and provide guidance for the degradation of other antibiotics.

Screening of Bioflocculant-Producing Strains and Characteristics of Microbial Flocculation

A high effective bioflocculant-producing strain named LB1 was isolated and screened from the leachate by routine micro- method. The strain was identified as genus Pseudomonas according to the morphologic and physiological-biochemical characteristics of the strain. The biological characteristics of the microbial flocculants produced by LB1 were investigated. The results show that the optimal production period of microbial flocculant using LB1 is 96 h; and the products, found in the fermentation liquor, comprise the extracellular organic matter （EOM） of LB1 generated during LB1 growth and the secondary metabolites in the anaphase of LB1. Meanwhile, the mycelia can improve the performance of the microbial flocculants. Because heat has a greater influence on the active substance in the microbial flocculants than other factors, the activity of the flocculants decreases with increasing temperature and the time of heating. The flocculants can flocculate mud-containing and melanin-containing wastewater effectively with a flocculation ratio of 85.1% and 92.2%, respectively. The optimal heating temperature varies from 20 to 45 ℃. When flocculating the two wastewater, the flocculating activity of the flocculants is above 57.7% and 70.9%, respectively, in a wide pH range from 3 to 11.

Study on Isolation and Degradation Characteristics of an Aniline-degrading Strain

[Objective] The research aimed to screen out an efficient aniline-degrading strain and study its degradation characteristics. [Method] By domesticated enrichment culture, an efficient aniline-degrading strain named as DA-K was isolated from activated sludge sample collected from a chemical plant in Henan. DA-K could use aniline as the sole carbon and nitrogen sources. The strain was carried out physiological and biochemi- cal identification, and its biological degradation characteristics were studied. [ Result] DA-K strain was G - and red-shaped, and its colony color was off-white. It was initially determined as Acinetobacter sp. By measuring, the optimum growth temperature and pH for DA-K were respectively 30 ~C and 6.0. DA-K strain could grow well in inorganic salt medium with aniline of 2 500 mg/L. After shaking for 96 h under the conditions of pH 6.0, 30 ℃, 180 r/min and 1 000 mg/L of aniline, the degradation rate of the aniline by DA-K could reach nearly 80%. [ Conclusion] The DA-K strain had a higher aniline degradation efficiency and actual treatment capability of the aniline wastewater, which laid foundation for establishing gene engineerincl strain.

蜂粮中Lactobacillus kunkeei的益生特性研究

蜂粮是植物花粉、蜂蜜和蜜蜂唾液的发酵混合物,是营养丰富的天然食材。作者从蜂粮中分离到61株乳酸杆菌,经16S rRNA基因测序,鉴定为Lactobacillus kunkeei。首先,用邻苯二甲醛法对61株L.kunkeei进行胆固醇去除能力检测,其中5株菌胆固醇去除能力均大于15%,菌株B35对胆固醇的去除率达到(29.07±1.30)%。随后,对这5株L.kunkeei进行酸耐受性、胆盐耐受性、抗生素耐药性及抑菌等益生特性进行研究。耐酸实验和耐胆盐实验结果表明,5株L.kunkeei均具有良好的耐酸性和胆盐耐受性。药敏试验结果表明,5株L.kunkeei对4种临床常用抗生素(红霉素、克林霉素、庆大霉素、万古霉素)均敏感。通过琼脂扩散法抑菌实验,发现5株L.kunkeei对大肠埃希氏菌、金黄色葡萄球菌均有一定的抑菌作用。B35菌株的细胞黏附性能良好,对Caco-2细胞的黏附率达到3.32%。从蜂粮中分离到5株具有良好益生特性的菌株,其中菌株B35的益生特性最佳,为益生菌的开发与利用提供了新的菌种资源。

鲈鱼肠道LactobacillussakeiLY1-6对荧光假单胞菌抑制作用研究

目的：从海鱼肠道中筛选对荧光假单胞菌具有较强抑制作用的乳酸菌。方法：采用牛津杯琼脂扩散法筛选菌株，通过生理生化反应和16SrRNA测序进行菌株生物学鉴定，利用蛋白酶、pH和温度等因素对抑菌活性进行分析，采用扫描电镜分析乳酸菌无细胞上清液（CFS）对荧光假单胞菌细胞结构的完整性影响。结果：从鲈鱼肠道中筛选出对荧光假单胞菌具有较强抑制活性的菌株LY1—6，经生理生化和16SrRNA测序鉴定为清酒乳杆菌（Lactobacillus sakei）。菌株LY1—6CFS经胃蛋白酶处理后其抑菌活性完全丧失，经中性蛋白酶、木瓜蛋白酶、胰蛋白酶和碱性蛋白酶处理后其抑菌活性分别丧失了38．22％、38．00％、22．48％和18．46％。在pH2．5—5．0具有抑菌活性，并具有良好的热稳定性，初步结果表明LY1—6CFS中抑菌活性物质可能为细菌素。扫描电镜结果表明经LY1—6CFS处理使荧光假单胞菌细胞结构被破坏并溶解。结论：来自鲈鱼肠道的清酒乳杆菌LY1—6对荧光假单胞菌具有较强抑制作用，其抑菌活性物质为细菌素类，作用机制为破坏细胞的完整性，可作为控制水产品中荧光假单胞菌腐败生物保鲜的出发菌株。

饲用发酵乳酸杆菌(Lactobacillus fermentum)生物学特性的研究

在体外研究了1株仔猪源的发酵乳酸杆菌(Lactobacillusfermentum)的生长曲线、耐热存活率、耐酸存活率、贮藏存活率等生物学特性,采用均匀设计法优化发酵乳酸杆菌的发酵培养基。结果表明,发酵乳酸杆菌的浓度在2h之后从105个数量级迅速上升,到第24h菌体浓度达到最高值,第28h之后,活菌浓度开始缓慢下降到1011数量级以下。pH2.0处理6h的存活率为80.9%,经过1个月贮藏存活率为78.4%,75℃处理15min之后存活率为45.1%。优化的发酵参数为:时间:20h;葡萄糖:10g/L;蔗糖:60g/L;胰蛋白胨:30g/L;酵母浸粉:30g/L;柠檬酸铵:12g/L。研究证明该发酵乳酸杆菌具有良好的生长繁殖性能和较强的抗逆性,在仔猪饲料中可以用作益生素菌种。

植物乳杆菌Lactobacillus plantarum(FJAT-7926)生物学特性研究

分离到1株植物乳杆菌FJAT-7926,并对其进行生物学特征研究,结果表明:该乳酸菌的最适生长温度为37℃,最适pH为6。接种量为3%,培养36h后,pH达到3.98,产乳酸量为25.4g·L-1。应用该菌株发酵大豆豆浆,研究发酵后的植物性乳酸菌饮品特性,结果显示:饮品乳酸菌含量高达1×109cfu·mL-1,感官评价良好。

益生菌Lactobacillus casei Zhang在马乳中发酵特性及人工消化液耐受性研究

将益生菌L．casei Zhang以2．0×10^7cfu／g的接种量接种在马乳中进行发酵，测定其发酵特性及28d贮藏期间人工消化液的耐受性。结果表明，在发酵结束（pH4．5）时，活菌数较接种时增加了1．11个对数单位。在28d贮藏期间，发酵马乳样品pH降低了0．35个单位，滴定酸度增加了16°T，活菌数保持在10^8cfu／g以上。贮藏28d后，发酵马乳样品中L．casei Zhang在pH2．5和2．0人工胃液消化3h后，其存活率分别为100．6％和46．22％，又经人工肠液消化8h后，存活率分别降为74．83％和11．04％。L.casei Zhang保持良好的贮藏稳定性及较好的人工消化液耐受性，显示了其应用于发酵乳制品中良好的潜力。

有抑菌功能的豆奶发酵剂Lactobacillus casei rhamnosus的选育

从15个菌株中筛选出抑菌作用好的Lactobacillus casei rhamnosus LCR 6013,该菌能使豆奶均匀凝乳,在MRS中的培养上清液对金黄色葡萄球菌有极好的抑制作用,抑菌圈直径为25～26 mm。该菌株依次用Nisin溶液、酸溶液和NaCl溶液驯化后,抑菌作用有所增加。驯化后的LCR 719可在豆奶中高密度生长并有良好的稳定性。

Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

In this paper,to better reveal the surface effect and the screening effect as well as the nonlinear multi-field coupling characteristic of the multifunctional piezoelectric semiconductor(PS)nanodevice,and to further improve its working performance,a magneto-mechanical-thermo coupling theoretical model is theoretically established for the extensional analysis of a three-layered magneto-electro-semiconductor coupling laminated nanoplate with the surface effect.Next,by using the current theoretical model,some numerical analyses and discussion about the surface effect,the corresponding critical thickness of the nanoplate,and the distributions of the physical fields(including the electron concentration perturbation,the electric potential,the electric field,the average electric displacement,the effective polarization charge density,and the total charge density)under different initial state electron concentrations,as well as their active manipulation via some external magnetic field,pre-stress,and temperature stimuli,are performed.Utilizing the nonlinear multi-field coupling effect induced by inevitable external stimuli in the device operating environment,this paper not only provides theoretical support for understanding the size-dependent tuning/controlling of carrier transport as well as its screening effect,but also assists the design of a series of multiferroic PS nanodevices.

一株耐酸乳杆菌Lactobacillus acetotolerans FBKL1.0204的筛选鉴定及耐酸、产酸特性

耐酸乳杆菌是浓香型白酒窖池发酵中后期酒醅中的优势菌,此时酒醅酸性较强。采用传统分离纯化法分离酒醅中细菌,经形态学特征和生理生化特性分析,并结合16S rDNA基因序列同源性分析和管家基因pheS和rpoA序列同源性分析及耐酸性筛选,分离鉴定出1株耐酸乳杆菌(Lactobacillus acetotolerans)FBKL1.0204。采用比浊法、电极电位法和高效液相色谱法测定菌株在不同酸胁迫下的生物量、pH和有机酸的变化。耐酸特性研究表明,在乳酸、乙酸和盐酸酸化的酸性发酵环境中,FBKL1.0204能耐受pH 4的酸性环境,极端生存pH值为3;产酸特性研究表明,FBKL1.0204为异型乳酸发酵,主要代谢生成乳酸和乙酸,最终使发酵液pH值降至3.5左右,在乙酸调节pH值为6的MRS培养基中,其代谢生成乳酸和乙酸含量最高,分别为(28.32±0.54)g/L和(2.73±0.52)g/L。由此可见,FBKL1.0204具有优良的耐酸和产酸特性,有利于其在白酒酿造过程中生长繁殖并丰富白酒风味。

益生菌Lactobacillus plantarum4在豆乳中发酵特性的评价

以大豆为原料,利用益生菌Lactobacillus plantarum4发酵豆乳,通过测定豆乳在发酵及贮藏期间酸度、蛋白水解能力、活菌数、脱水收缩性等指标,对L.plantarum 4的发酵特性及贮藏稳定性进行研究,同时比较不同处理方法对大豆抗营养因子(脂肪氧化酶和胰蛋白酶抑制剂)的抑制作用。结果显示,L.plantarum4在豆乳中生长良好,发酵结束时,滴定酸度为68.91°T,活菌数可达到2.33×108 CFU/mL,蛋白水解能力和持水力都显著增加,感官品质较佳;低温贮藏时各指标均无明显变化,贮藏稳定性明显优于室温贮藏;同时得出热磨法是抑制大豆抗营养因子的最佳方法。研究表明L.plantarum4具备益生菌所应有的发酵特性,为其进一步应用于实际生产提供了理论依据。

Age-determined referral criteria of myopia for large-scale vision screening

Background: This study aimed to explore the best screening measure of myopia and its associated optimal referral criteria for children aged between 6 and 16.Methods: After informed consent of cycloplegia was obtained, a total of 6,321 children aged between 6 and 16 from 53 primary or junior middle schools in Jiading District of Shanghai were included in our populationbased study. Receiver operating characteristic(ROC) curve was performed to determine the best cutoff points, sensitivities and specii cities of different screening tests, including uncorrected visual acuity(UCVA), noncycloplegic autorefraction(NCAR) and the combination of these two tests.Results: There was significant difference in prevalence of myopia between boys and girls(χ~2=6.358, P=0.012). Compared with children of low age, the prevalence of older children was significantly higher(χ~2=1,386.404, P<0.001). For the combination of UCVA and NCAR, the best cutoff point was UCVA less than or equal to 0.2 logarithm of minimum angle of resolution(MAR)(20/30) and NCAR spherical equivalent refraction(SER) less than or equal to -0.75 diopters(D), with associated sensitivity and specificity of 75.0% and 85.0%, respectively, which were higher than those of UCVA and NCAR alone. After stratified by age, the best cutof points were varied among children. The accuracy for children aged between 9 and 12 was higher than that for other ages.Conclusions: The best screening measure of myopia was the combination of UCVA and NCAR. The optimal referral criteria of myopia for children should be age-determined.

Study on the Characteristics of Pollutants in Surface Water Source Based on Risk Assessment

Supervision of urban water source area and the safety of drinking water is one of the important tasks in China's current environmental protection work. By reviewing screening methods of characteristic pollutants in urban water source area,screening system of pollutants based on the framework of environmental risk is introduced in detail: establish database of pollutants→determine the evaluation purpose→determine testing end and screening standard→assignment calculation→prioritization. At the same time,the application of health risk assessment and technology in the risk assessment of urban water source area is introduced,so as to provide technical support and theoretical basis for management and protection of urban water source area.

Bionic design and performance test of maize grain cleaning screen through earthworm motion characteristics

The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen,and it is easy to accumulate in the front of the screen,which leads to the decrease of screening efficiency.Based on the reverse engineering technology,using the wavy geometry formed during the earthworm(Pheretima guillelmi)moving as a bionic prototype,a bionic screen was designed to make the maize mixture migrate backward rapidly in the front of the screen.The contour curve of earthworm’s head in an axial contracted state was extracted and fitted to obtain its equation.Based on the difference of concave position of the lower surface’s wavy geometry during the earthworm moving,the motion of the bionic screen was divided into four postures,and the conversion between different postures of the bionic screen was realized by the cam drive mechanism.The kinematics simulation of the bionic screen was carried out through ADAMS,and the displacement and velocity of the bionic screen were analyzed.When the feeding mass of the maize mixture was set at 5 kg/s,6 kg/s and 7 kg/s,the test results showed that the time of the maize mixture migrated(TOMMM)in the front of the bionic screen was shortened by 0.18 s,0.71 s,and 1.36 s,respectively,compared with that of planar reciprocating vibrating screen.The total screening time(TST)of the bionic screen was shortened by 1.28 s,1.33 s,and 1.53 s,respectively.The ability of the maize mixture to be migrated backward was improved.This study can provide a reference for the innovative design of the cleaning screen.