Tropical dryland agroforestry on clay soils: : Analysis of systems based on Acacia senegal in the Blue Nile region, Sudan

Acacia senegal, the gum arabic producing tree, is the most important component in traditional dryland agroforestry systems in the Blue Nile region, Sudan. The aim of the present study was to provide new knowledge on the potential use of A. senegal in dryland agroforestry systems on clay soils, as well as information on tree/crop interaction, and on silvicultural and management tools, with consideration on system productivity, nutrient cycling and sustainability. Moreover, the aim was also to clarify the intra-specific variation in the performance of A. senegal and, specifically, the adaptation of trees of different origin to the clay soils of the Blue Nile region. In agroforestry systems established at the beginning of the study, tree and crop growth, water use, gum and crop yields, nutrient cycling and system performance were investigated for a period of four years (1999 to 2002). Trees were grown at 5 x 5 m and 10 x 10 m spacing alone or in mixture with sorghum or sesame; crops were also grown in sole culture. The symbiotic biological N2 fixation by A. senegal was estimated using the 15N natural abundance (δ15N) procedure in eight provenances collected from different environments and soil types of the gum arabic belt and grown in clay soil in the Blue Nile region. Balanites aegyptiaca (a non-legume) was used as a non-N-fixing reference tree species, so as to allow 15N-based estimates of the proportion of the nitrogen in trees derived from the atmosphere. In the planted acacia trees, measurements were made on shoot growth, water-use efficiency (as assessed by the δ13C method) and (starting from the third year) gum production. Carbon isotope ratios were obtained from the leaves and branch wood samples. The agroforestry system design caused no statistically significant variation in water use, but the variation was highly significant between years, and the highest water use occurred in the years with high rainfall. No statistically significant differences were found in sorghum or sesame yields when intercropping and sole crop systems were compared (yield averages were 1.54 and 1.54 ha-1 for sorghum and 0.36 and 0.42 t ha-1 for sesame in the intercropped and mono-crop plots, respectively). Thus, at an early stage of agroforestry system management, A. senegal had no detrimental effect on crop yield, but the pattern of resource capture by trees and crops may change as the system matures. Intercropping resulted in taller trees and larger basal and crown diameters as compared to the development of sole trees. It also resulted in a higher land equivalent ratio. When gum yields were analysed it was found that a significant positive relationship existed between the second gum picking and the total gum yield. The second gum picking seems to be a decisive factor in gum production and could be used as an indicator for the total gum yield in a particular year. In trees, the concentrations of N and P were higher in leaves and roots, whereas the levels of K were higher in stems, branches and roots. Soil organic matter, N, P and K contents were highest in the upper soil stratum. There was some indication that the P content slightly increased in the topsoil as the agroforestry plantations aged. At a stocking of 400 trees ha-1 (5 x 5 m spacing), A. senegal accumulated in the biomass a total of 18, 1.21, 7.8 and 972 kg ha-1of N, P, K and OC, respectively. Trees contributed ca. 217 and 1500 kg ha-1 of K and OC, respectively, to the top 25-cm of soil over the first four years of intercropping. Acacia provenances of clay plain origin showed considerable variation in seed weight. They also had the lowest average seed weight as compared to the sandy soil (western) provenances. At the experimental site in the clay soil region, the clay provenances were distinctly superior to the sand provenances in all traits studied but especially in basal diameter and crown width, thus reflecting their adaptation to the environment. Values of δ13C, indicating water use efficiency, were higher in the sand soil group as compared to the clay one, both in leaves and in branch wood. This suggests that the sand provenances (with an average value of -28.07 ) displayed conservative water use and high drought tolerance. Of the clay provenances, the local one (Bout) displayed a highly negative (-29.31 ) value, which indicates less conservative water use that resulted in high productivity at this particular clay-soil site. Water use thus appeared to correspond to the environmental conditions prevailing at the original locations for these provenances. Results suggest that A. senegal provenances from the clay part of the gum belt are adapted for a faster growth rate and higher biomass and gum productivity as compared to provenances from sand regions. A strong negative relationship was found between the per-tree gum yield and water use efficiency, as indicated by δ13C. The differences in water use and gum production were greater among provenance groups than within them, suggesting that selection among rather than within provenances would result in distinct genetic gain in gum yield. The relative δ15N values ( ) were higher in B. aegyptiaca than in the N2-fixing acacia provenances. The amount of Ndfa increased significantly with age in all provenances, indicating that A. senegal is a potentially efficient nitrogen fixer and has an important role in t agroforestry development. The total above-ground contribution of fixed N to foliage growth in 4-year-old A. senegal trees was highest in the Rahad sand-soil provenance (46.7 kg N ha-1) and lowest in the Mazmoom clay-soil provenance (28.7 kg N ha-1). This study represents the first use of the δ15N method for estimating the N input by A. senegal in the gum belt of Sudan. Key words: Acacia senegal, agroforestry, clay plain, δ13C, δ15N, gum arabic, nutrient cycling, Ndfa, Sorghum bicolor, Sesamum indicum

Prediction of individual genetic risk to prostate cancer using a polygenic score

BACKGROUND Polygenic risk scores comprising established susceptibility variants have shown to be informative classifiers for several complex diseases including prostate cancer. For prostate cancer it is unknown if inclusion of genetic markers that have so far not been associated with prostate cancer risk at a genome-wide significant level will improve disease prediction. METHODS We built polygenic risk scores in a large training set comprising over 25,000 individuals. Initially 65 established prostate cancer susceptibility variants were selected. After LD pruning additional variants were prioritized based on their association with prostate cancer. Six-fold cross validation was performed to assess genetic risk scores and optimize the number of additional variants to be included. The final model was evaluated in an independent study population including 1,370 cases and 1,239 controls. RESULTS The polygenic risk score with 65 established susceptibility variants provided an area under the curve (AUC) of 0.67. Adding an additional 68 novel variants significantly increased the AUC to 0.68 (P = 0.0012) and the net reclassification index with 0.21 (P = 8.5E-08). All novel variants were located in genomic regions established as associated with prostate cancer risk. CONCLUSIONS Inclusion of additional genetic variants from established prostate cancer susceptibility regions improves disease prediction. Prostate 75:1467–1474, 2015. © 2015 Wiley Periodicals, Inc.

Crystal structures of a nonapeptide helix containing alpha,alpha-di-n-butylglycine (Dbg), Boc-Gly-Dbg-Ala-Val-Ala-Leu-Aib-Val-Leu-OMe

Two crystals structures of a nonapeptide (anhydrous and hydrated) containing the amino acid residue alpha, alpha-di-n-butylglycyl, reveal a mixed 3(10)/alpha-helical conformation. Residues 1-7 adopt phi, psi values in the helical region, with Val(8) being appreciably distorted. The Dbg residue has phi, psi values of -40, -37 degrees and -46, -40 degrees in two crystals with the two butyl side chains mostly extended in each. Peptide molecules in the crystals pack into helical columns. The crystal parameters are C50H91N9O12, space group P2(1), with a = 9.789(1) Angstrom, b = 20.240(2) Angstrom, c = 15.998(3) Angstrom, beta = 103.27(1); Z = 2, R = 10.3% for 1945 data observed >3 sigma(F) and C50H91N9O12. 3H(2)O, space group P2(1), with a = 9.747(3) Angstrom, b = 21.002(8) Angstrom, c = 15.885(6) Angstrom, beta = 102.22(3)degrees, Z = 2, R = 13.6% for 2535 data observed >3 sigma(F). The observation of a helical conformation at Dbg suggests that the higher homologs in the alpha, alpha-dialkylated glycine series also have a tendency to stabilize peptide helices. (C) Munksgaard 1996.

DLTS analysis of amphoteric interface defects in high-TiO2 MOS structures prepared by sol-gel spin-coating

High-kappa TiO2 thin films have been fabricated from a facile, combined sol-gel spin - coating technique on p and n type silicon substrate. XRD and Raman studies headed the existence of anatase phase of TiO2 with a small grain size of 18 nm. The refractive index `n' quantified from ellipsometry is 2.41. AFM studies suggest a high quality, pore free films with a fairly small surface roughness of 6 angstrom. The presence of Ti in its tetravalent state is confirmed by XPS analysis. The defect parameters observed at the interface of Si/TiO2 were studied by capacitance - voltage (C - V) and deep level transient spectroscopy (DLTS). The flat - band voltage (V-FB) and the density of slow interface states estimated are -0.9, -0.44 V and 5.24x10(10), 1.03x10(11) cm(-2); for the NMOS and PMOS capacitors, respectively. The activation energies, interface state densities and capture cross -sections measured by DLTS are E-V + 0.30, E-C - 0.21 eV; 8.73x10(11), 6.41x10(11) eV(-1) cm(-2) and 5.8x10(-23), 8.11x10(-23) cm(2) for the NMOS and PMOS structures, respectively. A low value of interface state density in both P-and N-MOS structures makes it a suitable alternate dielectric layer for CMOS applications. And also very low value of capture cross section for both the carriers due to the amphoteric nature of defect indicates that the traps are not aggressive recombination centers and possibly can not contribute to the device operation to a large extent. (C) 2015 Author(s).

Efeito da temperatura de secagem de dois tipos de silano e da supressão ou redução do tempo de condicionamento com ácido hidrofluorídrico na resistência de união entre uma cerâmica de dissilicato de lítio e um cimento resinoso

Este estudo avaliou o efeito de diferentes métodos de silanização e aplicação do ácido hidrofluorídrico (HF) sobre a resistência à microtração de uma cerâmica de dissilicato de lítio a um cimento resinoso. Quarenta blocos de IPS e.max Press /Ivoclar Vivadent (5x5x6mm) foram cimentados a blocos de resina Z250/3M ESPE (5x5x6mm) usando o cimento resinoso RelyX ARC/3M ESPE de acordo com os seguintes métodos de tratamento superficial: G1: 20s de ácido fluorídrico (HF) + silano não hidrolisado Primer-Activactor/Dentsply (SNH) seco à temperatura ambiente; G2: 20s HF + silano pré-hidrolisado RelyX Ceramic-Primer/3M ESPE (SPH) seco à temperatura ambiente; G3: 10s HF + SNH seco com ar quente (50oC-2min); G4: 10sHF + SPH seco com ar quente (50oC-2min); G5: sem ácido, SNH seco com ar quente (50oC-2min); G6: sem ácido, SPH seco com ar quente (50oC-2min); G7: sem ácido, SNH seco à temperatura ambiente; G8: sem ácido, SPH seco à temperatura ambiente. Antes de cada método de silanização, os blocos cerâmicos receberam acabamento com lixas de carbeto de silício (220-600) e limpeza com ácido fosfórico 37% (1min). A cimentação foi realizada com carga vertical de 1kg por 10min. Os conjuntos de cerâmica/cimento/resina foram armazenados em água destilada (37C) por 24 horas e depois seccionados em máquina de corte Isomet 1000 a fim de obter palitos (n = 40) de 1mm2 de área da seção transversal, que foram submetidos ao teste de microtração em máquina de ensaio universal Emic (v = 0,5mm/min). O modo de fratura foi avaliado em microscópio eletrônico de varredura. A análise estatística foi realizada utilizando ANOVA / Dunnett (p-valor = 0,000). As médias MPa e desvio padrão foram: G1-21,5 (8,9) BC; G2-30,5 (7,2) A; G3-19.4 (9.1) BC; G4-24,0 (9,0) B; G5-8.1 (3.2) D; G6 -18,0 (6,2) C; G7-7.8 (2,6) D; G8-6.3 (2,5) D. Grupos 2, 3, 4 e 6 não tiveram falhas prematuras dos palitos contra os grupos 1, 5, 7 e 8, que apresentaram 2,2; 44,4; 75,6 e 33,3% de perdas prematuras, respectivamente. O teste de correlação foi realizado apresentando significância estatística, com valor de -0,736 (p-valor = 0,000), mostrando que, a medida que o percentual de perda prematura aumenta, a média da MPa diminui. Quanto ao modo de fratura, observou-se 44,97% de falhas do tipo mista, 51,70% de falhas do tipo adesiva, 3,33% de falhas do tipo coesiva do cimento. Quando é realizada a supressão do condicionamento com HF como pré-tratamento da superfície cerâmica IPS e.max Press, a aplicação de silano SPH, associada ao seu tratamento térmico, deve ser o método de silanização recomendado, embora os valores mais elevados de resistência de união tenham sido os obtidos quando utilizado o condicionamento com HF por 20s. Quando é realizada a redução do tempo de condicionamento com HF para 10s, a aplicação do silano (SPH ou SNH) deve ser sempre associada ao seu tratamento térmico. O SNH só deve ser usado se as superfícies das cerâmicas IPS e.max Press forem tratadas com HF.

无指盘臭蛙皮肤抗感染多肽组学研究

在过去的一个多世纪里，两栖类动物皮肤分泌液作为它们的第一道防御屏障引起了研究者们极大的兴趣，同时也开展了相关的许对研究，到目前为止，已从中分离鉴定出了百余种的活性物质。无指盘臭蛙是我国的一种特有两栖动物，初步的活性检测发现，无指盘臭蛙皮肤分泌液具有很强的抗菌，溶血以及蛋白酶抑制剂活性。 在本论文中，我们利用多肽组学与基因组学的方法对无指盘臭蛙皮肤的抗感染多肽组进行了研究。 通过三步分离纯化过程：一步Sephadex G-50分子筛和两步反相高压液相（RP-HPLC）的方法，从无指盘臭蛙皮肤分泌液中分离纯化得到了21条新的抗菌肽，它们分别属于17个不同的抗菌肽家族，其中8个分别属于已知的5个抗菌肽家族，它们是：Brevinin-1E(2个)、Brevinin-2E（1个）、Esculentin-1（1个）、Esculentin-2（1个）和Nigrocin（3个）抗菌肽家族。另外的13个抗菌肽与已发现的抗菌肽表现出较低的相似性，我们将它们归类到12种新的抗菌肽家族，它们是：Odorranain-A (1个)、Odorranain-B(1个)、 Odorranain-C(1个)、 Odorranain-G (1个)、Odorranain-H (2个)、 Odorranain-J (1个)、Odorranain-L (1个)、Odorranain-M (1个)、 Odorranain-N (1个)、 Odorranain-O (1个)、Odorranain-Q(1个)、 Odorranain-T(1个)。 从单个无指盘臭蛙皮肤里面，我们克隆得到了372条抗菌肽序列，它们编码107条新的抗菌肽，这一发现使得目前发现的两栖类抗菌肽的数目几乎增加了1倍。这也是目前发现的抗菌肽最为丰富的物种。这107条抗菌肽分别属于30个不同的抗菌肽家族，其中有24个为新的抗菌肽家族。这些抗菌肽的多样性可能是通过点突变、碱基的插入或删除、结构域的穿梭以及拼接等多种机制形成的。这些抗菌肽多样性的形成可能与无指盘臭蛙生活环境中微生物的组成有关。30个家族抗菌肽前体序列的SPD区域（包括信号肽和前导肽序列，Signal and Propiece Domain, SPD）非常保守，表明它们可能起源于同一个祖先基因。对7个抗菌肽家族的非同义碱基替代率Dn与同义碱基替代率Ds进行检测发现，它们可能经受着不同选择压力的作用。无指盘臭蛙皮肤抗菌肽在二级结构和功能上都表现出丰富的多样性。在一个两栖类个体里面发现如此丰富的抗菌肽甚是让人惊讶。这一发现也使得我们不得不重新认识先天性免疫在两栖类动物防御系统中的重要性，对两栖类生态环境的分子基础以及那种认为一种两栖类只需要20-30种抗菌肽就足以抵御环境中的微生物的看法重新审视。我们的研究还显示：无指盘臭蛙抗菌肽之间还存在着协同效用。 我们对无指盘臭蛙皮肤抗菌肽的去极化作用进行了研究，发现所检测的7个抗菌肽都可使金黄色葡萄球菌发生去极化，但是它们使细菌发生去极化的能力不同。对12种抗菌肽的抗菌机制研究发现，它们通过多种不同的机制发挥作用：有些在细菌内形成片层样的囊泡状结构，有些导致细胞质壁的分离，有些在细菌的膜上形成穿孔，有些则导致了细菌染色质的固缩。 总之，这些研究为设计新型的抗菌肽提供了有用的参考资料。

六氯苯对水体微型生物群落的影响及其吸附行为

研究了六氯苯(HCB)对微型水生生物群落的影响及其吸附、传递过程。测定了群落的耗氧量和不同粒经颗粒物的生物量及HCB变化。试验结果显示,在6μg/L HCB影响下,群落的呼吸作用受到抑制,生物量减少。试验第1天,30.0%(质量分数,下同)的HCB以溶解态存在,26.3%吸附在0.22～2μm的颗粒物(以细菌为主)上,22.1%吸附在2～8μm的颗粒物(以鞭毛虫和藻类为主)上,21.6%吸附在大于8μm的颗粒物(以藻类和大型原生动物为主)上。48h后,溶解态的HCB逐渐减少,并由食物链低营养级向高营养级传

太平湖水库的浮游藻类与营养型评价

研究了太平湖水库的浮游藻类与营养类型。共发现藻类175种。绿藻门的种类最多(87种),占种类总数的50％。硅藻和蓝藻次之(分别为34和33种),各占19.4％和18.8％。其它5门藻合计21种,仅占种类总数的11.8％。根据营养型分析结果,太平湖目前水质优良,属中营养型水体;但是藻类的优势种类和总氮含量两项指标已达富营养水平,而且微囊藻(Microcystis)水体较多出现,表明该水体已有向富营养化发展的趋势。含磷量较低(总磷0.012mg/L)是浮游藻类进一步大量繁殖的限制因子。为防止水质恶化,除了应控

黄土高原长期种植苜蓿对土壤硫、钙、镁的影响

以22年定位试验为基础,研究黄土高原长期种植紫花苜蓿(Medicago sativaL.)情况下土壤硫、钙、镁组分的变化。结果表明:长期施P使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加9.41%、62.41%、47.51%、30.07%、2.25%、5.38%和17.54%;长期施NPM使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加20.89%、98.31%、68.44%、57.34%、8.07%、12.54%和37.69%。长期施P使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加4.64%、4.27%、11.66%、4.05%和8.59%,但残余态钙含量降低2.21%;长期施NPM使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加8.69%、8.30%、51.59%、6.73%和27.77%,但残余态钙含量降低26.23%。长期施NPM使苜蓿连作耕层土壤全镁、有效镁、水溶态镁、交换态镁、酸溶态镁和残余态镁含量分别增加7.38%、61.98%、63.16%...

DNA、纳米微粒及其相互作用的扫描探针显微学研究

1．采用改进的蒸发液滴中流体毛细流动法，用于展开和固定适于AFM研究的大环状DNA。对长达148.9 kbp的人类基因组3号染色体上一个完整的酵母染色体DNA分子和pB孙22质粒DNA进行了展开固定研究，长度测定显示偏差小于3.5％，结果优于其它展开线性DNA的方法。对其相应的展开机理进行了初步探讨：利用AFM考察了不同长度的DNA分子在云母基底上的分子级分形图案。实验证明DNA分子级的分形图案与DNA的浓度、长度和其它辅助因素相关。我们认为DLA理论或许更适合描述DNA分子在云母基底上形成不同分形图案的体系。2．我们利用阳离子的桥合作用，将质粒DNA固定并展开在云母基底上制得了DNA网络结构。结合实验数据，对质粒DNA形成的机理和可控的参数：离子种类、离子浓度、网孔大小和网孔高度进行了讨论，提出了相应的模型进行解释。我们在半透明的云母基底以及玻璃和蓝宝石等透明基底上构建了不同结构的DNA网络。结合实验数据，讨论了在各种固体基底上形成DNA网络的影响因素，我们认为，固体基底表面的亲水性对于构建DNA网络起重要作用。我们通过控制乙醇的浓度与温度结合原子力显微镜样品定位技术发现，云母基底上形成DNA膜的DNA分子是否移动与处理DNA样品的乙醇浓度有直接关系。对于纯乙醇溶液无论是高温（6O℃）或常温，均未引起DNA分子的移动（无论是吸附在云母基底上的，还是吸附在DNA分子链上的）；如果用混合有水的乙醇溶液（无论其中水的含量多少），不管是高温（60℃）或常温，都会引起DNA膜结构发生变化，即DNA分子发生了移动。热乙醇水溶液对DNA分子的作用比常温情况下更明显1可能是热力学上的因素导致的。3．通过控制银纳米微粒在云母基底上的聚集行为，而非直接通过化学合成的方法，构建了一种新的银结构一纳米银盘。详细阐述了如何得到这种结构的过程，通过原子力显微镜、紫外可见光光谱和X一射线电子能谱技术等工具对其性质也作了相应的表征。这种由纳米粒子组成的银盘与文献报道的单晶纳米银盘相比具有更大的比表面积，在纳米催化等方面有更广阔的应用前景。通过自聚集方式构建纳米银盘结构的方法，对于人们通常认为在溶液中合成的纳米结构与在各种固体基底上表征的纳米结构是一致的观点提出了新的理解。利用戊二醛试剂与发光的纳米微粒萘酰亚胺通过醛胺加成反应形成酰胺键，组装形成二维发光粒子网络。结合原子力显微镜高度形貌图和光谱数据，发现粒子间形成了两种典型的网络结构即，实心六方堆积和空心六方堆积结构。对此我们提出了相应的模型给予解释。4，利用展开的质粒DNA为模板诱导形成了环状的氯化镁纳米结构。原子力显微镜考察表明，这些纳米结构的高度是6.2±1.3-8.2±1.80nm，长度为1.35±0.18到2.93±0.25um。我们以CTAB包裹18nm纳米金和3.5nm纳米银使之形成带正电荷的外壳，利用。NA磷酸骨架带负电荷特性，通过静电自组装方式形成了金属化的纳米网络结构。通过AFM、UV-vis光谱和XPS谱的表征说明，带正电荷外壳的纳米金和纳米银被DNA模板高度地组装形成有序的二维网络结构。5．利用自制的样品定位系统，重复性地对整个基底范围内的样品实行定位，定位的精确度达400nm。这种方法对于样品旋转角度或取出后进行进一步处理都适用。该定位方法依赖于一台个人电脑，一个样品定位仪，一个CCD相机和一套可视光学系统，用于监测透明或半透明基底如，云母、玻璃、蓝宝石、石英和钦酸银等原子力显微镜广泛使用的基底表面或背面特征。作为对这种定位方法的应用，我们用不同的灯M操作模式，不同的针尖对单个的DNA分子、单个的DNA-蛋白质复合物和DNA网络在样品移动或拿出样品台后进行了定位实验。这种方法的精度和分辨率，对于一般的商用或自制SPM（AFM,STM，sNOM）系统都可以适用。

Flying lemurs – The 'flying tree shrews'? Molecular cytogenetic evidence for a Scandentia-Dermoptera sister clade

Background: Flying lemurs or Colugos (order Dermoptera) represent an ancient mammalian lineage that contains only two extant species. Although molecular evidence strongly supports that the orders Dermoptera, Scandentia, Lagomorpha, Rodentia and Primates form a superordinal clade called Supraprimates (or Euarchontoglires), the phylogenetic placement of Dermoptera within Supraprimates remains ambiguous. Results: To search for cytogenetic signatures that could help to clarify the evolutionary affinities within this superordinal group, we have established a genome-wide comparative map between human and the Malayan flying lemur (Galeopterus variegatus) by reciprocal chromosome painting using both human and G. variegatus chromosome-specific probes. The 22 human autosomal paints and the X chromosome paint defined 44 homologous segments in the G. variegatus genome. A putative inversion on GVA 11 was revealed by the hybridization patterns of human chromosome probes 16 and 19. Fifteen associations of human chromosome segments (HSA) were detected in the G. variegatus genome: HSA1/3, 1/10, 2/21, 3/ 21, 4/8, 4/18, 7/15, 7/16, 7/19, 10/16, 12/22 (twice), 14/15, 16/19 (twice). Reverse painting of G. variegatus chromosome-specific paints onto human chromosomes confirmed the above results, and defined the origin of the homologous human chromosomal segments in these associations. In total, G. variegatus paints revealed 49 homologous chromosomal segments in the HSA genome. Conclusion: Comparative analysis of our map with published maps from representative species of other placental orders, including Scandentia, Primates, Lagomorpha and Rodentia, suggests a signature rearrangement (HSA2q/21 association) that links Scandentia and Dermoptera to one sister clade. Our results thus provide new evidence for the hypothesis that Scandentia and Dermoptera have a closer phylogenetic relationship to each other than either of them has to Primates.

典型PPCPs的生态毒理效应与强化处理技术

人类长期且大量的使用药品及个人护理用品（PPCPs），使其持续不断地输入环境，导致它们在环境中的残留浓度日益增加，并对人类和其他生物产生了不良的生态毒理效应。本文以四种典型PPCPs（对乙酰氨基酚、土霉素、三氯生、佳乐麝香）为研究对象，采用常规的毒理学实验方法，研究了它们对小麦种子发芽、根伸长的急性毒性，以及低浓度长期暴露对小麦幼苗叶绿素（CHL）、可溶性蛋白（SP）、过氧化物酶（POD）和超氧化物歧化酶（SOD）等生理生化特性的影响。由于PPCPs具有生态风险性，而传统的水处理工艺却不能有效的将这些物质去除。因此，开发更多的新技术以强化处理PPCPs，使它们在环境中残留的浓度尽可能降低是一项很重要的工作。本研究以零价铁处理有机物的原理为依据，自制铁铜双金属复合物，研究了其对PPCPs溶液的处理效果及影响因素，并对整个过程中的反应机理进行了初探。实验结果表明： 实验浓度下，四种PPCPs与小麦根长及芽长抑制率之间具有良好的剂量-效应关系。根据线性回归方程计算的EC50可知，不同种类的PPCPs对小麦种子发芽的毒性大小不同，而且小麦的芽及根部对不同PPCPs胁迫的敏感部位不同。对乙酰氨基酚、土霉素、三氯生对小麦根长的抑制较芽长显著，它们的EC50分别为668.8 mg/L、34.7 mg/L和147.8mg/L；而佳乐麝香对小麦芽长的抑制更为显著，EC50为143.4 mg/L。实验浓度范围内，四种PPCPs对小麦种子的发芽率均没有显著的抑制作用。四种PPCPs暴露21天后，2.8～22.4 mg/L对乙酰氨基酚、0.15～2.4 mg/L土霉素以及0.2～3.0 mg/L三氯生和佳乐麝香显著抑制小麦叶片/根部中的CHL和SP，而且使POD和SOD酶活性降低或上升，从而打破抗氧化系统的动态平衡；暴露21天内对CHL、SP、POD和SOD等含量在不同PPCPs胁迫下的变化趋势具有各自的特点。 以零价铁降解有机物的原理为依据，自制了铁铜双金属复合体系，以强化处理PPCPs溶液。电子扫描显微镜（SEM）及X-衍射（XRD）分析得出铁铜复合物（FeCu/Cu2O）由Fe、Cu及Cu2O组成。与零价铁相比，FeCu/Cu2O显著提高了对PPCPs的去除效果，主要是由于Cu的存在扩大了反应的电极电位差，即增加了Fe-Cu之间的外加阳极电流，从而加速Fe的阳极溶解，产生更多的高活性物质以更好的去除PPCPs。溶解氧是影响FeCu/Cu2O对PPCPs处理效果的重要因素，它们可以在FeCu/Cu2O表面获得电子后生成O2-，形成类Fenton体系。此外，由于Cu2O的光化学活性，光照也可以强化FeCu/Cu2O对PPCPs的处理效果。不同的反应条件下体系内的pH值及自由基的产生量不同。根据实验现象及相关的经典理论，本文对FeCu/Cu2O处理PPCPs的作用机理进行了初探，认为整个反应过程包括Fe的还原反应、Cu2O的光催化反应、Fe-Cu微电解反应以及絮凝过程等。

河流阶地的形成及其对构造与气候的意义

IEECAS SKLLQG

渭北旱塬冬小麦水·肥·产量关系研究

探讨了不同供水条件下土壤水分与作物产量的关系。[方法]以冬小麦品种长旱58为试材,设肥力和水分2因子高、中、低3水平9个处理组合,通过试验资料分析了不同养分和水分条件下作物的产量响应。利用2006年9月~2007年7月的气象资料研究了冬小麦不同生育期耗水量。[结果]各生育期耗水量占全生育期总耗水量的百分比以孕穗灌浆期最大,达45.6%,其次为拔节期,约21.5%,越冬期最小,约8.4%。底墒对旱作作物产量具有重要影响,施肥量过量会影响农田水分循环过程,使得高产农田的产量随降水量的变化而波动。[结论]提高作物土壤耗水量和土壤底墒利用率是黄土高原旱地农业实现高产稳产的关键。