Optimization of Culture Conditions and Medium Composition for the Marine Algicidal Bacterium Alteromonas sp. DH46 by Uniform Design

Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.

PREDICTION OF THE AERODYNAMIC PERFORMANCE OF HORIZONTAL AXIS WIND TURBINES IN CONDITION OF UNIFORM WIND

The classical momentum-blade element theory is improved by using the empirical formula while part of rotor blades enters into the turbulent wake state, and the performance of a horizontal-axis wind turbine (HAWT) at all speed ratios can be predicted. By using an improved version of the so-called secant method, the convergent solutions of the system of two-dimensional equations concerning the induced velocity factors a and a' are guaranteed. Besides, a solving method of multiple solutions for a and a' is proposed and discussed. The method provided in this paper can be used for computing the aerodynamic performance of HAWTs both ofrlow solidity and of high solidity. The calculated results coincide well with the experimental data.

A UNIFORMLY DIFFERENCE SCHEME OF SINGULAR PERTURBATION PROBLEM FOR A SEMILINEAR ORDINARY DIFFERENTIAL EQUATION WITH MIXED BOUNDARY VALUE CONDITION

In the poper, the method of separating singularity is applied to study the uniformly difference scheme of a singular perturbation problem for a semilinear ordinary differential equation with mixed boundary value condition. The uniform convergence on small parameter ε of order one for an IVin type difference scheme constructed is proved. At the end of the paper, a numerical example is given. The computing results coincide with the theoretical analysis.

Novel wavelet-homotopy Galerkin technique for analysis of lid-driven cavity flow and heat transfer with non-uniform boundary conditions

In this paper, a brand-new wavelet-homotopy Galerkin technique is developed to solve nonlinear ordinary or partial differential equations. Before this investigation,few studies have been done for handling nonlinear problems with non-uniform boundary conditions by means of the wavelet Galerkin technique, especially in the field of fluid mechanics and heat transfer. The lid-driven cavity flow and heat transfer are illustrated as a typical example to verify the validity and correctness of this proposed technique. The cavity is subject to the upper and lower walls’ motions in the same or opposite directions.The inclined angle of the square cavity is from 0 to π/2. Four different modes including uniform, linear, exponential, and sinusoidal heating are considered on the top and bottom walls, respectively, while the left and right walls are thermally isolated and stationary.A parametric analysis of heating distribution between upper and lower walls including the amplitude ratio from 0 to 1 and the phase deviation from 0 to 2π is conducted. The governing equations are non-dimensionalized in terms of the stream function-vorticity formulation and the temperature distribution function and then solved analytically subject to various boundary conditions. Comparisons with previous publications are given,showing high efficiency and great feasibility of the proposed technique.

Uniform isochronous center of a class of higher degree polynomial differential systems

In this paper,we give the necessary and sufficient conditions for a class of higher degree polynomial systems to have a uniform isochronous center.At the same time,we prove that for this system the composition conjecture is correct.

Effects of UV-B radiation and different light repair conditions on the early development of the tetraspores of Chondrus ocellatus Holm

The effects of exposure to UV-B radiation, 280-315 nm, and dark or dark repair conditions on the early development of Chondrus ocellatus Holm collected from Qingdao coast were studied under the laboratory condition. After being exposed to different doses [0, 36, 72, 108, 144 and 180 J/（m2.d）] of UV-B radiation, one treatment of tetraspores were put back to normal culture condition （PAR）, the other treatment were put into dark condition to repair for 2 h. During the cultivation, the diameter of the tetraspores were recorded every 4 d till the 50th day when vertical branches formed in all treatments. Then at the 50th day, CPDs, phycoerythrin, chlorophyll a and MAAs （Palythine and asterina-330） were measured. The results showed that low doses UV-B radiation could significantly accelerate the growth rate of the rate reduced gradually with UV-B radiation keep on tetraspores of C. ocellatus and the growth increasing. The variation trend of both the phycoerythrin and chlorophyll a concentration reduced significantly （P 〈0.05） once given the UV- B radiation. Under UV-B stress, the CPDs were induced, and the concentrations of CPDs were significant low in dark repair groups. The data of MAAs analyzed by LC/MS in the tetraspores of C. ocellatus suggested that there were two MAAs formed （palythine and asterina-330） after UV-B radiation induced, and low dose of UV-B irradiation could significantly induced the concentration of MAAs. From the growth and development state of the tetraspores, negative effects of UV-B radiation on the dark repair groups were more serious than PAR.

EFFECT OF DEPOSITIONS CONDITION ON THE MICROSTRUCTURE OF C/C MINICOMPOSITE

C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure of C/C minicomposites were investigated. Deposition conditions are as follows: deposition temperature ranging from 870℃ to 1000℃, the flow rate of propylene from 10 to 60 ml/min, and total system pressure from 3 to 16kPa. The results revealed: The deposit distributes non uniformly as increasing the deposition temperature or total system pressure. The effect of the flow rate of propylene on the distribution of deposit observes different principles at different deposition temperatures. If the deposition temperature rises to 900℃, the deposit distributes more non uniformly as increasing the flow rate of propylene. The morphology of deposit varies with deposition condition, such as smooth, droplet like or spike like. Deposition mechanism varies with deposition condition. It can be surface reaction nucleation and growth, heterogeneous nucleation of liquid droplet on carbon fiber or gas borne nuclei growth. With the principle of nuclei growth of crystal and the method of phenomenology, the changes of deposition mechanism and the morphology of pyrolytic carbon with deposition condition were explained successfully. The effect of deposition condition on deposit homogeneity stems from the effect of deposition condition on the CVI kinetics and the deposition mechanism of pyrolytic carbon.

Tribological characteristics of C/C-SiC braking composites under dry and wet conditions

C/C-SiC braking composites,based on reinforcement of carbon fibers and matrices of carbon and silicon carbide,were fabricated by warm compaction and in situ reaction process.The tribological characteristics of C/C-SiC braking composites under dry and wet conditions were investigated by means of MM-1000 type of friction testing machine.The influence of dry and wet conditions on the tribological characteristics of the C/C-SiC composites was ascertained.Under dry condition,C/C-SiC braking composites show superior tribological characteristics,including high coefficient of friction (0.38),good abrasive resistance (thickness loss is 1.10 μm per cycle) and steady breaking.The main wear mechanism is plastic deformation and abrasion caused by plough.Under wet condition,frictional films form on the worn surface.The coefficient of friction (0.35) could maintain mostly,and the thickness loss (0.70 μm per cycle) reduces to a certain extent.Furthermore,braking curves are steady and adhesion and oxidation are the main wear mechanisms.

Sufficient conditions of the various stabilities of the linear time-varying delayed differential equations

Due to the appearance and the study of the ornithopter and flexible-wing micro air vehicles, etc., the time-varying systems become more and more important and ubiquitous in the study of the mechanics. In this letter, the sufficient conditions of the uniform asymptotic stability are first presented for the delayed time-varying linear differential equations with any time delay by employing the Dini derivative, Lozinskii measure and the generalized scalar Halanay delayed differential inequality. They are especially based on the estimation of the arbitrary solutions but not the fundamental solution matrix since their solutions＇ space is infinite-dimensional. Then some sufficient conditions of the stability, asymptotic stability and uniform asymptotic stability of the delayed time-varying linear system with a sufficiently small time delay are reported by employing Taylor expansion and Dini derivative. It implies that these stabilities can be guaranteed by the Lozinskii measure of the matrix composing of the time delay and the coefficient matrices of the system.

Longitudinal dispersion with constant source concentration along unsteady groundwater flow in finite aquifer: analytical solution with pulse type boundary condition

Analytical solution is obtained to predict the contaminant concentration with presence and absence of pollution source in finite aquifer subject to constant point source concentration. A longitudinal dispersion along unsteady groundwater flow in homogeneous and finite aquifer is considered which is initially solute free that is, aquifer is supposed to be clean. The constant source concentration in intermediate portion of the aquifer system is considered with pulse type boundary condition and at the other end of the aquifer, concentration gradient is supposed to be zero. The Laplace Transformation Technique (LTT) is used to obtain the analytical solution of the formulated solute transport model with suitable initial and boundary conditions. The time varying velocities are considered. Analytical solutions are perhaps most useful for benchmarking the numerical codes and models. It may be used as the preliminary predictive tools for groundwater management.

Geochemistry of the Aptian bituminous limestones in Gümuü?hane area,Eastern Black Sea region:new insight into paleogeography and paleoclimate conditions

Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Eastern Pontides).They are well correlated with Aptian bitumen limestone in the other Tethys Reams.They are proposed as episodes of increased organic matter.However,background factors controlling organic matter enrichment are poorly known.In this study,we present new inorganic geochemistry,including trace elements,rare earth elements(REE),redox-sensitive elements(RSE),stable-isotopes(δ~(18)O andδ~(13)C),and total organic carbon(TOC).We integrated new geochemical data with existing stratigraphy,paleontology,and organic chemistry data to provide new insight into the depositional environment and paleoclimate conditions during Aptian.The lacustrine bitumen limestone(LBL)samples have variedδ~(13)C(ave.-1.45‰)andδ~(18)O(ave.-4.50‰).They possess distinct REE patterns,with an average of REE(ave.14.45 ppm)and Y/Ho(ave.35)ratios.In addition,they have variable Nd/YbN(0.28-0.81;ave.0.56)and Ce/Ce*(0.68-0.97;ave.0.86),and relatively high Eu^(*)/Eu(1.23-1.53;ave.1.35).They display seawater signatures with reduced oxygen conditions.The enrichment in RSE(Mo,Cu,Ni,and Zn)and the low Mo/TOC(0.70-3.69;ave.2.41)support a certain degree of water restriction.The high Sr/Ba,Sr/Cu,Ga/Rb,and K/Al records of the LBL facies suggest hot house climatic conditions.The sedimentary environment was probably an isolated basin that is transformed from the marine basin.In addition to depositional conditions,the regional parameters such as the climate,increased run-off period,nutrient levels,alkalinity level,and dominant carbonate producers favored the enrichment in organic matter of LBL facies.Thus,extreme greenhouse palaeoclimate conditions have an important role in organic matter enrichment in the isolated basin.Our results are conformable with the published data from marine,semi-restricted basin,and lacustrine settings in the different parts of the Tethys margin.Thus,this approach provides the first insight into the Aptian greenhouse paleo-climate conditions of the Eastern Black Sea Region,NE Turkey.

Leptin receptor of the hind brain nuclei is involved in the conditioned taste preference of rats

Objective: Conditioned taste preference(CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural pathways of CTP and whether serum leptin level and the leptin receptor(OB-Rb) in the hind brain are involved following CTP formation. Methods: We established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTP. Finally, the OB-Rb m RNA expression was examined by RT-q PCR assay in parabrachial nucleus(PBN) and the nucleus of the solitary tract(NST) of the hind brain. Results: Compared with control group, the level of serum leptin was higher in the CTP group(4.58 ± 0.52 vs 1.67 ± 0.25 μg/L, P<0. 01); increased c-fos positive cells were found in the anterior hypothalamus(AH, 221.75 ± 4.96 vs. 178.50±6.63 cells/mm^2, P<0.05), the basal lateral amygdala(BLA, 70.75±6.17 vs 56.50±3.62 cells/mm^2, P<0.05) and the nucleus of the solitary tract(NST, 41.25±1.32 vs 32.50±1.02 cells/mm^2, P<0.05). But in ventromedial nucleus of the hypothalamus(VMH, 20.75±2.73 vs 38.5±1.54 per 1 mm^2, P<005), PBN(21.50 ±2.24 vs 36.25±1.49 cells/mm^2, P<0.05) and the central nucleus of the amygdala(Ce A, 22.25±1.53 vs 35.50 ±2.11 cells/mm^2, P<0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb m RNA expression in PBN of CTP group rats was higher than that of control group(0.95±0.055 vs 0.57± 0.034, P<0.05), while there was no significant difference of OB-Rb m RNA expression in NST between the two groups. Conclusion: Nuclei AH, BLA, NST, VMH, PBN and Ce A participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.

Fourth-Order Compact Formulation for the Resolution of Heat Transfer in Natural Convection of Water-Cu Nanofluid in a Square Cavity with a Sinusoidal Boundary Thermal Condition

In the present work, we numerically study the laminar natural convection of a nanofluid confined in a square cavity. The vertical walls are assumed to be insulated, non-conducting, and impermeable to mass transfer. The horizontal walls are differentially heated, and the low is maintained at hot condition (sinusoidal) when the high one is cold. The objective of this work is to develop a new height accurate method for solving heat transfer equations. The new method is a Fourth Order Compact (F.O.C). This work aims to show the interest of the method and understand the effect of the presence of nanofluids in closed square systems on the natural convection mechanism. The numerical simulations are performed for Prandtl number ( ), the Rayleigh numbers varying between and for different volume fractions varies between 0% and 10% for the nanofluid (water + Cu).

冷弯薄壁卷边C形不锈钢梁的力学性能试验

为了研究冷弯壁薄卷边C形钢受弯构件的力学性能,以冷弯薄壁不锈钢梁为研究对象,重点研究加载条件、跨度对构件屈曲模式和受弯承载力的影响。结果发现:试件的加载条件和跨度对冷弯薄壁卷边C形钢受弯构件屈曲模式和极限承载力的影响显著,纯弯加载下的短梁极限承载力高达169.1 kN,破坏模式为畸变屈曲,其余试件破坏模式也为畸变屈曲;腹板V型加劲能够有效抑制腹板鼓曲的产生,提高试件的极限承载力。利用现有直接强度法修正公式的计算结果与试验结果进行对比,以验证公式的准确性。

Mesoscale Simulation for Polymer Migration in Confined Uniform Shear Flow

The structure and dynamics of confined single polymer chain in a dilute solution, either in equilibrium or at different shear rates in the uniform shear flow fields, were investigated by means of dissipative particle dynamics simulations. The no-slip boundary condition without density fluctuation near the wall was taken into account to mimic the environment of a nanochannel. The dependences of the radius of gyration, especially in three different di- rections, and the density profile of the chain mass center on the strength of the confinement and the Weissenberg number（Wn） was studied. The effect of the interaction between polymer and solvent on the density profile was also investigated in the cases of moderate and strong Wn. In the high shear flow, the polymer migrates to the center of the channel with increasing Wn. There is only one density profile peak in the channel center in the uniform shear flow, which is in agreement with the results of the experiments and theory.

A UNIFORMLY CONVERGENT FINITE DIFFERENCE METHOD FOR A SINGULARLY PERTURBED INITIAL VALUE PROBLEM

Initial value problem for linear second order ordinary differential equation with small parameter by the first and second derivatives is considered. An exponentially fitted difference scheme with constant fitting factors is developed in a uniform mesh, which gives first_order uniform convergence in the sense of discrete maximum norm. Numerical results are also presented.

More Properties of Semi-Linear Uniform Spaces

In this paper we shall generalize the definition given in [1] for Lipschitz condition and contractions for functions on a non-metrizable space, besides we shall give more properties of semi-linear uniform spaces.

Factors Impacting Corn (<i>Zea mays</i>L.) Establishment and the Role of Uniform Establishment on Yield

Information from actual farm fields can help corn producers understand the value and importance of establishing uniform crop emergence and within-row plant spacing. Thirty-eight fields planted with corn (Zea mays L.) by North Dakota producers were evaluated to determine the effects of uneven plant emergence timing and within-row plant space variability, as well as identifying contributing factors. Rows within a planter’s width with the most variability yielded 6% less than the least variable rows. Individual ear weights decreased as the number of days after normal emergence (date when 50% of plant stand emerged) increased. Ears next to within-row gaps (>30.5 cm) weighed 11% more than the normally spaced plants. Combined ears from both plants situated <5.1 cm apart weighed 36% more than from a single ear from normally spaced plants. Surface residue and planting speed impacted stand establishment variability more often than other factors measured. Producers should assess each field environment individually in order to identify best practices to achieve uniform stand establishment.

Thermal explosion of a reactive gas mixture at constant pressure for non-uniform and uniform temperature systems

In this study,the approximate and exact solutions for the stationary-state of the solids model with neglecting reactant consumption for both non-uniform and uniform temperature systems were applied on gas ignition under a constant pressure condition.The criticality conditions for a slab,an infinite cylinder,and a sphere are determined and discussed using dimensionless temperatures under constant ambient and surface temperatures for a non-uniform temperature system.Exact solution for a Semenov model with convection heat loss was also presented.The solution of the Semenov problem for constant volume or density as a solid and constant pressure were compared.The critical parameterδis calculated and compared with those of Frank-Kamenetskii solution values.The validation of the calculated ignition temperatures with other exact solution and experimental results were offered.The relation between critical parameters form Semenov and F.K.models solution was introduced.

C型料场刮板机取料速度控制方法与系统开发

在C型料场刮板机自动化作业过程中,取料过快经常导致刮板机跳闸故障,取料过慢会导致供料不足、效率低等问题。对此,本文提出一种基于点云模型的C型料场刮板机取料速度控制方法,并在某C型料场现场试验验证,该控制方法步骤:(1)获取料堆点云数据和形状,将其转换为高度灰阶图,并采用一种新型点云过滤算法降低其噪声、提高平滑度;(2)基于刮板机链板恒定条件建立物料流量模型,结合能量转换构建刮板机电流-速度模型,将模型结果实时写入刮板机PLC中,进而实时控制刮板机取料速度。结果表明:使用该模型,料堆点云模型的内存资源降低98.64%,点与点之间形成有效的拓扑关系,计算的复杂度降低,料堆点云模型的平滑度显著提高;刮板机作业时料流的流量波动在8.29%内,刮板机的设备故障率减少5.24%,生产效率提高9.68%。本文提出的取料速度控制方法可用于替代人工调节刮板机的取料速度,减少刮板机的作业故障,提高生产效率,有效提高设备的无人化、智能化水平,并可为各种刮板机取料速度控制与作业稳定性控制提供参考。