The role of plants in channel-dyke and field irrigation systems for domestic wastewater treatment in an integrated eco-engineering system

Eight kinds of plants were tested in channel-dyke and field irrigation systems. The removal rates of TP, phosphate, TN, ammonia, CODcr and BOD, in the channel-dyke system with napiergrass (Pennisetum purpurem Schumach, x Pennisetum alopecuroides (L.) Spreng American) were 83.2, 82.3, 76.3, 96.2, 73.5 and 85.8%, respectively. The field irrigation systems with rice I-yuanyou No.1(88-132) (Oryza sativa L.) and rice II- suakoko8 (Oryza glaberrima) had high efficiency for N removal; the removal rate were 84.7 and 84.3%, respectively. The mass balance data revealed that napiergrass, rice I and II were the most important nutrient sinks, assimilating more than 50% of TP and TN. Plant uptake of N and P as percentage of total removal from wastewater correlated with biomass yield of and planting mode. (C) 2000 Elsevier Science B.V. All rights reserved.

Dynamic P-I and P-V Curves for Semiconductor Lasers and Modulators

In this paper, we propose the dynamic P-V curve for modulator and P-I curve for laser diode, and present a simple approach to deriving the curves from the small-signal frequency responses measured using a microwave network analyzer. The linear response range, modulation efficiency, optimal driving conditions at different frequency can, therefore, be determined. It is demonstrated that the large-signal performance of electro-absorption (EA) modulator and the directly modulated semiconductor lasers can be predicted from the dynamic curved surface. Experiments show a good agreement between the evaluated characteristics and the measured large-signal performance.

I 蓖麻油聚氨酯/聚甲基丙烯酸甲酯AB交联聚合物的研究 II 双阳原油热处理中加入降凝剂的研究

用蓖麻油与TDI反应生成端异氰酸酯基预聚物，再与HEA反应，生成端乙烯基预聚物，以不同比例的MMA与端乙烯基预聚物共聚交联，得到一组组成和交联密度各不相同的ABCP样品；为了分别观察组成和交联密度对材料性能的影响，在交联共聚过程中，以二乙烯基苯作交联点调节剂 ，得到固定组成，交联密度变化和固定交联密度组成变化的两组样品；此外，在固化过程中加入不同含量的丙烯酸（<10%），得到另一组样品，以观察氢键对该体系的影响。反应过程中用化学分析、NMR、IR及平衡溶胀等方法测定反应程度、分子量及交联网的交联密度；同时用动态粘弹谱仪和介电损耗仪测定样品的动态力学性能，转变与松弛及相容性；用材料试验机测试样品的力学性能；通过透射电子显微镜观察材料的形态结构。结果表明：copu/PMMA ABCP是个半相容体系，随硬段含量的增加和交联密度的减小相容性变差。形态结构呈不规则形状，相区尺寸由几A变至几百A，材料的力学性能和阻尼性能明显优子构成它们的均聚物。材料的阻尼值主要受交联密度的影响，玻璃化转变温度则主要受组成控制。氢键对该体系的形态结构有明显影响，丙烯酸含量为7.5%时相容性最差，5%和10%时最好。以双阳昌10号井原油为研究对象选用EVA作原料，以马来酸酐接枝改性，合成ET-6降凝剂。采取在热处理中加入降凝剂的综合处理方法，考察了降凝剂合成的最佳反应条件和降凝剂用量及热处理温度对原油结晶状态及流动性的影响。结果表明，热处理中加入ET-6降凝剂可使蜡的结晶形态发生明显变化，降凝剂用量仅100-500 ppm即可使双阳原油的凝固点由原来的30-31 ℃降至7-9 ℃，原油的低温流动性大为改观。

共生固氮放线菌Frankia的细胞化学分类I、Frankia菌全细胞可溶性蛋白图谱分析II、Frankia菌同功酶图谱分析

本文利用单向SDS-PAGE方法对十八株Frankia菌的全细胞可溶性蛋白进行了图谱分析。Frankia菌蛋白图谱不受菌令的影响。不同交叉接种组的Frankia菌具有不同的蛋白图谱，同一交叉接种组内的菌株也有所羞。十八株菌分为三大类七个亚类，第I类包括赤场、杨梅香蕨木和美洲茶内生菌；第II类包括木麻黄内生菌，第III类包括胡颓子和沙棘内生菌。利用同功酶图谱的差异性对Frankia菌进行分类识别是一种非常有效的方法，不同的Frankia菌株具有不同的同功酶（过氧化物酶和酯酶）图谱。根据图谱之间的相似性，可以将二十株Frankia菌分成三组；即赤杨组，木麻黄组和胡颓子组，这与其它分类结果基本符合，只是细枝木麻黄菌株CcO1的过氧化物酶图谱与其它菌株完全不同。从同种根瘤中分离的内生菌具有不同的同功酶图谱，进一步证实了遗传结构不完全相同的菌株可以同时共生于同种根瘤内，同时根据二种同功酶的电泳分布率，说明了Frankia菌株遗传信息的广泛分布性。

Ab initio study on the physical properties of CoN3 and RhN3 with skutterudite structure

The elastic and electronic properties of hypothetical CoN3 and RhN3 with cubic skutterudite structure were studied by first principles calculations based on density functional theory. By choosing different initial geometries, two local minima or modifications were located on the potential energy surface, termed as modifications I and II. Both compounds are mechanically stable. For each compound, modification I is lower in energy than II. Thermodynamically stable phases can be achieved by applying pressures. Modification II is lower in energy than I at above 50 GPa for both compounds.

Synthesis of bis(amine anhydride)s for novel high T(g)s and organosoluble poly(amine imide)s by palladium-catalyzed amination of 4-chlorophthalide anhydride

Two novel bis(amine anhydride)s, NN-bis(3,4-dicarboxyphenyl)aniline dianhydride (I) and N,N-bis(3,4-dicarboxyphenyl)-p-tert-butylaniline (II), were synthesized from the palladium-catalyzed amination reaction of N-methyl-protected 4-chlorophthalic anhydride with arylamines, followed by alkaline hydrolysis of the intermediate bis(amine-phthalimide)s and subsequent dehydration of the resulting tetraacids. The X-ray structures of anhydride I and II were determined. The obtained dianhydride monomers were reacted with various aromatic diamines to produce a series of novel polyimides. Because of the incorporation of bulky, propeller-shaped triphenylamine units along the polymer backbone, all polyimides exhibited good solubility in many aprotic solvents while maintaining their high thermal properties. These polymers had glass transition temperatures in the range of 298-408 degrees C. Thermogravimetric analysis showed that all polymers were stable, with 10% weight loss recorded above 525 degrees C in nitrogen.The tough polymer films, obtained by casting from solution, had tensile strength, elongation at break, and tensile modulus values in the range of 95-164 MPa, 8.8-15.7%, and 1.3-2.2 GPa, respectively.

Isochiral form II of syndiotactic polypropylene produced by epitaxial crystallization

Epitaxial crystallization of syndiotactic polypropylene (sPP) on 2-quinoxalinol (2-Quin) yields, in the lower part of the crystallization range, the less common and metastable form II based on the packing of isochiral helices, rather than the stable antichiral form I. The contact plane is (110)(II). Form II exits only as a thin layer (< 50 nm) near the substrate surface. During further growth away from the surface, a transition takes place to the disordered form I, observed in "conventional" thin film growth. The epitaxial relationship rests only partly on dimensional matching with the chain axis repeat distance (which would be valid for both forms I and II) and on interchain distances. Whereas a better dimensional match would be achieved with form I, selection of the isochiral form II results from better correspondence of the surface topographies of the deposit (110)(II) sPP and substrate 2-Quin (001) contact faces.

Crystal structure and its transition for poly(aryl ether ketone ketone)s .1.

Poly(aryl ether ketone ketone)s (PEKK) was a high-performance engineering plastics, By means of Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC) methods, PEKK samples crystallized in solvent induction, from glass state and from melting state were studied, Crystal forms I and II for PEKK were found, The formation of crystal form II was dependent on thermal history and solvent induction, and this form II had melting point 10 degrees C or so lower than that of form I crystallized from glass state, All PEKK samples had low melting peaks which were relevant to the polarization of PEKK molecular chain, while they had nothing to do with thermal history, The heat of fusion for PEKK low melting peaks accounted for,percentage of 2 to 10 or so of the whole heat of fusion, And PEKK has its equilibrium melting point of 409 degrees C.

Effect of dentin tubules on the mechanical properties of dentin - part III: Numerical, analysis

Imitating a real tooth and the periodontal supporting tissues, we have established a 2D finite element model and carried out a numerical analysis based on the inhomogeneous and anisotropic (IA) stress-strain relation and strength model of dentin proposed in the preceding Parts I and II, and the conventional homogeneous and isotropic (III) model, respectively. Quite a few cases of loadings for a non-defected and a defected tooth are considered. The numerical results show that the stress level predicted by the IA model is remarkably higher than that by the III model, revealing that the effect of the dentin tubules should be taken into a serious consideration from the viewpoint of biomechanics.

Fatigue crack-growth rate in ferrite martensite dual-phase steel

An empirical study is made on the fatigue crack growth rate in ferrite-martensite dual-phase (FMDP) steel. Particular attention is given to the effect of ferrite content in the range of 24.2% to 41.5% where good fatigue resistance was found at 33.8%. Variations in ferrite content did not affect the crack growth rate itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si1.gif" border="0" alt="View the MathML source" title="View the MathML source" width="53" height="18" />when plotted against the effective stress intensity factor range itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si2.gif" border="0" alt="View the MathML source" title="View the MathML source" width="39" height="14" /> which was assumed to follow a linear relation with the crack tip stress intensity factor range ΔK. A high itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si4.gif" border="0" alt="View the MathML source" title="View the MathML source" width="39" height="14" /> corresponds to uniformly distributed small size ferrite and martensite. No other appreciable correlation could be ralated to the microstructure morphology of the FMDP steel. The closure stress intensity factor itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si5.gif" border="0" alt="View the MathML source" title="View the MathML source" width="21" height="13" />, however, is affected by the ferrite content with itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si6.gif" border="0" alt="View the MathML source" title="View the MathML source" width="64" height="17" /> reaching a maximum value of 0.7. In general, crack growth followed the interphase between the martensite and ferrite.

Dividing the fatigue crack growth process into Stage I and II where the former would be highly sensitive to changes in ΔK and the latter would increase with ΔK depending on the itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si9.gif" border="0" alt="View the MathML source" title="View the MathML source" width="115" height="18" /> ratio. The same data when correlated with the strain energy density factor range ΔS showed negligible dependence on mean stress or R ratio for Stage I crack growth. A parameter α involving the ratio of ultimate stress to yield stress, percent reduction of area and R is introduced for Stage II crack growth so that the itle="View the MathML source" class="mathImg"><img style="border: 0px; margin: 0px; padding: 0px; vertical-align: bottom; display: inline; max-width: 600px" class="imgLazyJSB" src="http://ars.els-cdn.com/content/image/1-s2.0-016784429190028I-si13.gif" border="0" alt="View the MathML source" title="View the MathML source" width="53" height="18" /> data for different R would collapse onto a single curve with a narrow scatter band when plotted against αΔS.

Mixed-mode fracture mechanisms near the fatigue threshold of aisi-316 stainless-steel

Near threshold, mixed mode (I and II), fatigue crack growth occurs mainly by two mechanisms, coplanar (or shear) mode and branch (or tensile) mode. For a constant ratio of ΔK_I/ΔK_II the shear mode growth shows a self-arrest character and it would only start again when ΔK_I and ΔK_II are increased. Both shear crack growth and the early stages of tensile crack growth, are of a crystallographic nature; the fatigue crack proceeds along slip planes or grain boundaries. The appearance of the fracture surfaces suggest that the mechanism of crack extension is by developing slip band microcracks which join up to form a macrocrack. This process is thought to be assisted by the nature of the plastic deformation within the reversed plastic zone where high back stresses are set up by dislocation pile-ups against grain boundaries. The interaction of the crack tip stress field with that of the dislocation pile-ups leads to the formation of slip band microcracks and subsequent crack extension. The change from shear mode to tensile mode growth probably occurs when the maximum tensile stress and the microcrack density in the maximum tensile plane direction attain critical values.

Identification of protein superfamily from structure-based sequence motif

The structure-based sequence motif of the distant proteins in evolution, protein tyrosine phosphatases (PTP) I and II superfamilies, as an example, has been defined by the structural comparison, structure-based sequence alignment and analyses on substitut

Physiological advantages may contribute to successful invasion of the exotic Cyprinus carpio into the Xingyun Lake, China

Feeding and growth traits of Cyprinus carpio and Cyprinus pellegrini (both at age-0) were compared in three experiment, in an attempt to analyze potential causes for the displacement of the native C. pellegrini in the Xingyun Lake, Yuxi, Yunan, China. Experiment I was conducted in water which fluctuated between 15 and 20 degrees C. Experiment II and III were conducted in a laboratory and water temperature was maintained between 20 degrees C and 25 degrees C, respectively. Three common trends were noted for all three experiments: (1) feeding rate of C. carpio was lower than that of C. pellegrini, and this difference was found to be significant in experiment I; (2) growth rate of C. carpio was higher than C. pellegrini, and the difference was found to be significant in experiment II; (3) food conversion efficiency and energy retention efficiency for C. carpio were higher than those of C. pellegrini, and significant differences were noted in experiment I and II. Since the growth period for fish in the Xingyun Lake generally occurs when water temperatures are between 15 and 25 degrees C, it can be suggested that C. carpio has advantages over C. pellegrini in growth and food utilization efficiency, and lower food consumption than C. pellegrini. These physiological traits of C. carpio might allow this species to be more resistant to food shortage and predation, and may be partially responsible for the displacement of C. pellegrini by C. carpio.