强化混凝工艺及对去除有机污染物的影响

生态农业和小城镇建设需要优质饮用水 ,水中有机污染物的去除对保证饮用水质至关重要。文章阐述了强化常规混凝工艺不但可以有效地去除水中的有机物 ,而且是目前最为经济有效的手段 ,并通过试验水厂常用混凝剂在不同混凝条件下的混凝效果加以研究。结果表明 ,增加混凝剂投加量和降低 p H值均能有效的去除有机物 ,其中 p H值的影响效果较大。     

Buffer combinations for mammalian cell culture

The growth and metabolism of cultured mammalian cells are markedly affected by the pH variation in ordinary hicarbonate-buffered media (pH 8.0 to 6.9). Those pH swings can be reduced and the pH of the culture can be stabilized as desired in the range pH 6.4 to 8.3 by appropriate combinations of two or three organic buffers, each at 10 to 15 millimolar, in conjunction with phosphate and bicarbonate. The initial alkalinization in sparse cultures is then minimized, and the metabolic acidificatiotn in 24 hours is usually less than 0.4 pH unit except in heavy cultutres.     

有机农业土壤氮素流失与防止措施

根据国外资料,综述了有机农业土壤氮素流失规律与防止措施。综述指出,虽然有机农业生产方式可有效地减少氮素流失,但仍然存在流失的可能性。有机氮肥只有在微生物降解为可溶性氮素后,才能被作物大量吸收。这种降解过程是持续进行的、受诸多因素影响的。可溶性氮素流失的规律与集约农业相似,土壤可储藏氮素的观念是错误的。田间植物对氮素的吸收和合理的氮肥使用技术,可有效地减少氮素淋失。     

A cyclic carbanionic valence isomer of a carbocation: diphosphino analogs of diaminocarbocations

Diaminocarbocations (or amidinium salts) feature a three-center 4pi electron system with an open planar structure. Their 2pi electron three-membered cyclic valence isomers, in which the carbon atom bears a negative charge, are predicted to be about 541 kilojoules per mole higher in energy than the open form. This isomer has not been identified yet. In contrast, the attempted synthesis of a diphosphorus analog of amidinium salts leads to the cyclic carbanionic form. There is no precedent for such a transformation of a carbocationic center into a carbanionic center, but with the help of heavier main-group elements, numerous examples can be imagined. This approach will enable the preparation of many unknown structural moieties that are difficult or even impossible to access in the corresponding carbon and nitrogen series.     

Reversible reduction of oxygen to peroxide facilitated by molecular recognition

Generation of soluble sources of peroxide dianion (O(2)(2-)) is a challenge in dioxygen chemistry. The oxidizing nature of this anion renders its stabilization in organic media difficult. This Report describes the chemically reversible reduction of oxygen (O(2)) to cryptand-encapsulated O(2)(2-). The dianion is stabilized by strong hydrogen bonds to N-H groups from the hexacarboxamide cryptand. Analogous stabilization of peroxide by hydrogen bonding has been invoked recently in crystalline saccharide and protein systems. The present peroxide adducts are stable at room temperature in dimethyl sulfoxide (DMSO) and N,N'-dimethylformamide (DMF). These adducts can be obtained in gram quantities from the cryptand-driven disproportionation reaction of potassium superoxide (KO(2)) at room temperature.     

喂饲-堆腐过程中猪粪磷素的变化研究

采用作物产品养猪,猪粪好气堆腐的方法,研究了喂饲-堆腐过程中猪粪的磷素变化情况。结果表明:喂饲期间,猪对于氮磷的吸收能力不断增加,猪粪中无机磷占总磷的比例不断降低。堆腐期间,堆料中有机碳、有机氮的矿化进程相对稳定,而有机磷的波动较大。有机磷含量与C/P具有很好的相关性。     

Cultivating Erect Milkvetch (Astragalus adsurgens Pall.) (Leguminosae) Improved Soil Properties in Loess Hilly and Gullies in China

Erect milkvetch (Astragalus adsurgens Pall.), a leguminous grass, is a major source of fuel and forage, and has an important role in the restoration of the degraded ecosystems in central and northeastern China. The objective of this work was to investigate how erect milkvetch planting would affect the physical and chemical properties of soil in degraded arable lands. Soil samples at the depths of 0–20 and 20–40 cm were collected from erect milkvetch planting fileds at ages of 0, 1, 2 and 3 yr. Changes in soil bulk density, soil porosity, total N and P, organic matter content, available P, hydrolysable N and available K were measured. The results showed that root biomass and above-ground plant biomass were both significantly increased with plantation age. The significant increase in root nodule biomass was not observed in the first two years. However, it was significantly increased after three years. Root growth of erect milkvetch improved soil structure, and hence, decreased soil bulk density and increased soil porosity. Furthermore, the nitrogen fixation by erect milkvetch and return of erect milkvetch plant to soil increased the soil total N, hydrolysable N and organic matter content of the soil. Low concentrations of P in the soil with erect milkvetch planting could be ascribed to high plant uptakes and possibly to high sequestrations of P in plant biomass. Concentrations of K significantly increased during the first two years of erect milkvetch planting. The high accumulation of K under erect milkvetch cultivation in the first two years could partly be attributed to low plant uptake, and partly to relatively quick recycling within plant-soil systems. Three years after erect milkvetch plantingr, K accumulation at 0–20 cm soil layer was significantly lower than that from non-vegetated field sites, which could be attributed to high plant uptake. These parameters, except for soil bulk density, were all decreased with increasing soil depth. Soil total N, organic matter, porosity and available K in the 20–40 cm layer all showed linear increase trends, and soil bulk density, total P and available P in the depth 0–20 cm layer soil were decreased with increasing planting age. Erect milkvetch establishment could be an effective and applicable measure to improve soil nutrients, and prevent further soil degradation and erosion.     

Controlling the charge state of individual gold adatoms

The nature and control of individual metal atoms on insulators are of great importance in emerging atomic-scale technologies. Individual gold atoms on an ultrathin insulating sodium chloride film supported by a copper surface exhibit two different charge states, which are stabilized by the large ionic polarizability of the film. The charge state and associated physical and chemical properties such as diffusion can be controlled by adding or removing a single electron to or from the adatom with a scanning tunneling microscope tip. The simple physical mechanism behind the charge bistability in this case suggests that this is a common phenomenon for adsorbates on polar insulating films.     

日本高密度培养轮虫的现状与展望

对日本高密度培养轮虫Brachionus spp.的方法、原理和技术进行了综述:1)采用浓缩的淡水小球藻作为新食物以取代微绿球藻和面包酵母;2)培养液中充入氧气以防止缺氧;3)自动添加HCI使pH控制在7左右,以促进总氨解离为NH4 和OH-;4)用尼龙滤板清除过量的悬浮有机质;5)加入去泡剂以减少培养液和轮虫被泡沫吸附而流失.采用这些技术可使轮虫培养密度增加到1～2万个/mL,比传统方法提高100倍以上,并大幅度降低了生产成本.最近,日本采用连续的滤膜装置(CMFU)开发了一种新的流水培养系统,其中NH4 和溶解有机质都被滤除,轮虫密度可达到16万个/mL,成功地开发了轮虫的超高密度培养.     

Mesostructure design with gemini surfactants: supercage formation in a three-dimensional hexagonal array

At low temperatures, liquid crystal-like arrays made up of inorganic-cluster and organic molecular units readily undergo reversible lyotropic transformations. Gemini surfactants, with two quaternary ammonium head groups separated by a methylene chain of variable length and with each head group attached to a hydrophobic tail, can be used to control organic charge sitting relative to the bivariable hydrophobic tail configurations. This approach has led to the synthesis of a mesophase (SBA-2) that has three-dimensional hexagonal (P6(3)/mmc) symmetry, regular supercages that can be dimensionally tailored, and a large inner surface area. This mesostructure analog of a zeolite cage structure does not appear to have a lyotropic surfactant or lipid liquid crystal mesophase counterpart. Through the modification of gemini charge separation and each of the two organic tails, these syntheses can be used to optimize templating effects, including the synthesis of MCM-48 at room temperature.     

长期施肥紫色水稻土磷素累积与迁移特征

【目的】探讨长期不同施肥对钙质紫色水稻土磷素累积与迁移的影响。【方法】以长期肥料定位试验不同施肥处理的土壤为研究对象,试验处理包括不施肥（CK）、氮肥（N）、氮磷肥（NP）、氮磷钾肥（NPK）、有机肥（M,鲜猪粪）、有机肥+氮肥（MN）、有机肥+氮磷肥（MNP）和有机肥+氮磷钾肥（MNPK）8种施肥方式,研究不同施肥处理条件下钙质紫色水稻土磷素平衡、累积和去向状况,以及不同施肥方式对耕层（0-20 cm）土壤全磷、有效磷演变规律及土壤剖面（0-100 cm）全磷、有效磷迁移特征。【结果】钙质紫色水稻土33年不施用磷肥（CK和N）作物籽粒和秸秆磷素携出总量为613.12 kg·hm^-2,种苗、根茬、雨水及灌溉水带入土壤总磷量为106.61 kg·hm^-2,长期不施用磷肥土壤磷素表现出亏缺状况,年亏缺量为15.35 kg·hm^-2,且土壤磷含量随种植年限延续而下降,土壤全磷含量年均减少量为0.0011 g·kg^-1、有效磷含量年均减少量为0.029 mg·kg^-1;33年单施无机磷肥（NP和NPK）土壤磷素投入总量为1 880.03 kg·hm^-2、作物携出磷量为1 275.40 kg·hm^-2,有机肥处理（M和MN）土壤投入磷量为2 532.68 kg·hm^-2、携出磷量为757.50 kg·hm^-2;有机无机磷肥配施（MNP和MNPK）土壤投入和携出磷量分别为4 305.11和1 436.64 kg·hm^-2;不同施肥处理土壤磷素投入量都明显高于作物携出量,导致单施无机磷肥、单施有机磷肥和有机无机磷肥配施处理土壤磷素年盈余量分别为18.32、53.79和86.92 kg·hm^-2,年未知去向磷量分别为4.99、34.96和59.39 kg·hm^-2,土壤全磷含量年增加量分别为0.015、0.0018和0.018 g·kg^-1,有效磷含量年增加量分别为1.13、0.032和1.17 mg·kg^-1。长期不施用磷肥钙质紫色水稻土全磷含量随土层深度增加而降低,土壤有效磷含量则相反;长期施用磷肥土壤全磷和有效磷含量在土壤剖面都呈现出上下层高、中间低的空间分布格局。施用无机磷肥土壤磷素可迁移至60-80 cm土层,施用有机磷肥或有机无机磷肥配施土壤磷素可迁移至100 cm以下;随着磷肥施用年限持续,土壤磷素迁移深度和迁移量将会更大,有机肥的施用促使磷素向土壤下层迁移。【结论】连续数年施用磷肥后,土壤磷含量达到一定水平时应考虑减少磷肥用量,减少因有机肥过量施用导致的磷素快速积累和淋失。     

水葫芦富集水体养分及其农田施用研究

采用自然水体养殖及农田施用试验方法,对水葫芦(Eichhornia crassipes)的N、P、K吸收能力及其在农田施用效果进行了研究.结果表明,在研究试验条件下,水葫芦对N、P、K的富集系数分别达到N6641倍、P16 667倍、K6 560倍,42 d对N、P、K的吸收量可高达40.57、6.95和81.14 g·m~(-2).与常规施肥处理相比,施用水葫芦处理(等量的N、P投入)的土壤速效N除了苗期显著降低外,其他各时期无显著筹异,而速效P和速效K从苗期开始一直表现为不同程度的升高,说明施用水葫芦可促进土壤速效P、K的增加.但要获得较高的产量水平,应适当增加前中期氮肥施用水平.采用水葫芦控制性种养既可实现养分在水体与农田间的循环,还可减少农田化肥的施用量和农业面源污染,是一种良性的循环模式.     

污染土壤中有机质和重金属互相作用的模拟研究

    为了解污染土壤中有机质积累与重金属积累之间的相互影响,在供试土壤中添加不同等级的有机物料和重金属元素Pb与Cu,在培养条件下研究有机物对土壤重金属稳定性的影响及不同重金属添加量对土壤生物呼吸强度和有机质矿化的影响.结果表明,随着重金属添加量的增加,土壤微生物生物量和有机质矿化速率显著下降,添加的有机物料残留增加,促进了土壤有机碳的积累.同时,有机碳的积累又增加了土壤对重金属的吸附固定,增加了土壤中重金属的稳定性,降低了其淋溶性,有利于重金属在土壤中的积聚.分析结果表明,颗粒态有机质中重金属的富集是土壤有机质矿化减弱和重金属稳定性增加的主要原因.由此推断,污染土壤中重金属和有机质可通过形成重金属-颗粒态有机质复合体发生相互促进稳定或积聚的作用.     

Preparation and efficacy evaluation of Paenibacillus polymyxa KM2501-1 microbial organic fertilizer against root-knot nematodes

Root-knot nematodes (RKNs) cause huge yield losses to agricultural crops worldwide.  Meanwhile, livestock manure is often improperly managed by farmers, which leads to serious environmental pollution.  To resolve these two problems, this study developed a procedure for the conversion of chicken manure to organic fertilizer by larvae of Hermetia illucens L. and Bacillus subtilis BSF-CL.  Chicken manure organic fertilizer was then mixed thoroughly with Paenibacillus polymyxa KM2501-1 to a final concentration of 1.5×10⁸ CFU g^–1.  The efficacy of KM2501-1 microbial organic fertilizer in controlling root-knot nematodes was evaluated in pot and field experiments.  In pot experiments, applying KM2501-1 microbial organic fertilizer either as a base fertilizer or as a fumigant at the dose of 40 g/pot suppressed root-knot disease by 61.76 and 69.05% compared to the corresponding control treatments, respectively.  When applied as a fumigant at the dose of 1 kg m^–2 in field experiments, KM2501-1 microbial organic fertilizer enhanced the growth of tomato plants, suppressed root-knot disease by 49.97%, and reduced second stage juveniles of RKN in soil by 88.68%.  KM2501-1 microbial organic fertilizer controlled RKNs better than commercial bio-organic fertilizer in both pot and field experiments.  These results demonstrate that this co-conversion process efficiently transforms chicken manure into high value-added larvae biomass and KM2501-1 microbial organic fertilizer with potential application as a novel nematode control agent.     

不同变种及种源紫苏种子油脂肪酸组成及含量比较

采用化学萃取和GC-MS法,对5个变种11个种源地的17个种质的紫苏种子样品开展了种子油含量及其脂肪酸组成和相对含量的比较和分析。GC-MS结果表明,紫苏油中共发现14种脂肪酸,按相对含量高低划分为6种高含量脂肪酸(＞0.8%)和8种低含量脂肪酸(≤0.2%);其中14-甲基-十六烷酸(C17∶0)、十八碳二烯酸(C18∶2n3)、二十三碳酸(C23∶0)3种低含量脂肪酸为首次在紫苏油脂中被报道;高含量脂肪酸中α-亚麻酸的相对含量最高,达51.92%~62.98%;α-亚麻酸、亚油酸与油酸之间存在一定代谢转化相关性。脂肪酸含量外标法计算结果表明,5个变种中白苏变种的含油率和α-亚麻酸含量较高,作为紫苏油生产原料具有一定优势。      

Calculated phonon spectra of plutonium at high temperatures

We constructed computer-based simulations of the lattice dynamical properties of plutonium using an electronic structure method, which incorporates correlation effects among the f-shell electrons and calculates phonon spectra at arbitrary wavelengths. Our predicted spectrum for the face-centered cubic delta phase agrees well with experiments in the elastic limit and explains unusually large shear anisotropy of this material. The spectrum of the body-centered cubic phase shows an instability at zero temperature over a broad region of the wave vectors, indicating that this phase is highly anharmonic and can be stabilized at high temperatures by its phonon entropy.     

磷素在土壤中的垂直迁移潜力研究

针对磷素在田间条件下是否可以发生垂直迁移存有的疑问，利用模拟土柱研究了渗漏液磷含量的变化特点。结果表明。淹水后土柱渗漏液中总磷、有机磷的变化基本上表现为逐渐升高而后有所降低的趋势；施磷肥和猪粪处理土柱渗漏液中的总磷量高于无磷肥处理；施猪粪处理土柱渗漏液中有机磷量明显高于施无机磷肥的处理。     

N-异辛基吩噻嗪的高效合成与表征

以廉价的吩噻嗪为母体,分别采用一次反应、二次连续反应和二次连续反应加氢化钠三种不同的方法有效地合成了脂溶性异辛基吩噻嗪,并运用傅立叶变换红外光谱、质谱、元素分析、核磁共振谱等手段进行了表征;研究表明采用第三种方法合成产率最高;这为高效合成脂溶性有机中间体进行了有益的探索。     

有机肥活化土壤中磷的微生物学机理

在好气条件下，猪粪和纤维素对两种水稻土中的磷均能起活化作用，嫌气条件下，尽管猪粪和纤维素均能克服因嫌气而使土壤微生物数量的减少，但促进土壤固磷成为主要矛盾，因而显著降低土壤有效磷。通过微生物对难溶性Ｃａ＿３（ＰＯ４）＿２的溶磷量及培养基总酸度的测定，发现这些微生物具有转化难溶性磷为可溶性磷的能力，属溶磷微生物并有致酸作用。经相关分析，土壤中活化的磷量、微生物数量、培养基中的溶磷量和总酸度之间均存在看显著或极显著的相关关系，其中以总酸度与其它变量间的关系最好。因此，在好气条件下有机肥活化土壤中磷的机理可描述为：有机肥促进土壤微生物增长→微生物对其生长的局部位置的土壤起酸化作用→酸溶解难溶性磷为可溶性磷。     

Nanometer resolution and coherent optical dipole coupling of two individual molecules

By performing cryogenic laser spectroscopy under a scanning probe electrode that induces a local electric field, we have resolved two individual fluorescent molecules separated by 12 nanometers in an organic crystal. The two molecules undergo a strong coherent dipole-dipole coupling that produces entangled sub- and superradiant states. Under intense laser illumination, both molecules are excited via a two-photon transition, and the fluorescence from this doubly excited system displays photon bunching. Our experimental scheme can be used to optically resolve molecules at the nanometer scale and to manipulate the degree of entanglement among them.