Extra-large-pore zeolites with two-dimensional channels formed by 14 and 12 rings

Stable zeolites that have larger pore apertures and a three-dimensional pore topology are of interest because they could be used to adsorb larger molecules, particularly for application in oil refining. Several large-pore zeolitic materials with channels formed by openings of more than 12 rings are known, but all of them have a one-dimensional channel system that limits their use in catalysis. We report the synthesis and some characterizations of IM-12, a thermally stable germanium-containing zeolite that contains the first two-dimensional channel system with extra-large pores formed by 14- and 12-ring channels.     

Stretch-inactivated ion channels coexist with stretch-activated ion channels

Stretch-activated ion channels of animal, plant, bacterial, and fungal cells are implicated in mechanotransduction and osmoregulation. A new class of channel has now been described that is stretch-inactivated. These channels occur in neurons, where they coexist with stretch-activated channels. Both channels are potassium selective. The differing stretch sensitivities of the two channels minimize potassium conductance over an intermediate range of tension, with the consequence that, over this same range, voltage-gated calcium channels are most readily opened. Thus, by setting the relation between membrane tension and transmembrane calcium fluxes, stretch-sensitive potassium channels may participate in the control of calcium-dependent motility in differentiating, regenerating, or migrating neurons.     

Quantum communication with zero-capacity channels

Communication over a noisy quantum channel introduces errors in the transmission that must be corrected. A fundamental bound on quantum error correction is the quantum capacity, which quantifies the amount of quantum data that can be protected. We show theoretically that two quantum channels, each with a transmission capacity of zero, can have a nonzero capacity when used together. This unveils a rich structure in the theory of quantum communications, implying that the quantum capacity does not completely specify a channel's ability to transmit quantum information.     

微波-氯化钠改性沸石对沼液的吸附处理

【目的】研究不同改性条件对沸石吸附沼液效果的影响,为沼液的高效低耗处理提供理论依据。【方法】以化学需氧量(COD)、氨态氮(NH3-N)、总磷(TP)去除率为测定指标,以天然斜发沸石为对照,采用微波-氯化钠法改性沸石,研究微波功率、微波作用时间、氯化钠质量浓度、温度等改性条件对沸石处理沼液效果的影响。【结果】沸石最佳改性条件为:微波功率476W,微波作用时间9min,氯化钠质量浓度80g/L,搅拌温度25℃。天然斜发沸石对沼液中COD、NH3-N、TP的去除率分别为14.96%,27.54%和18.27%,而在最佳条件下所得的改性沸石对沼液中COD、NH3-N、TP的去除率分别达到32.26%,89.05%,48.33%,明显高于天然斜发沸石。【结论】得到了沸石改性的最优条件,为改性沸石在沼液吸附处理中的应用奠定了基础。     

基于叶片解剖结构的12个杨树无性系抗旱性分析

【目的】基于叶片解剖结构对12个杨树无性系进行抗旱能力评价,为杨树新品种选育和资源利用提供理论依据。【方法】以杨树无性系84K、I-101、107、A23、A39、A50、A54、La、Pa、Qg、Ta和Ti的1年生扦插苗成熟叶片为材料,通过常规石蜡切片法制作切片,Motic光学显微镜下观测角质层厚度、上表皮厚度、下表皮厚度、叶片厚度、主脉厚度、栅栏组织厚度和叶片组织结构紧密度（CTR）等7项抗旱性结构指标,运用单因素方差分析比较各无性系间这7个指标的差异,采用相关性分析评判各指标间的关联程度,运用主成分分析筛选影响抗旱性的主要指标,最后用模糊数学的隶属函数法对 12 个杨树无性系的抗旱性进行综合评价。【结果】12个杨树无性系的7项抗旱性指标之间差异较大,叶片角质层厚度、上表皮厚度、下表皮厚度、叶片厚度、主脉厚度、栅栏组织厚度和CTR分别为1.94~17.07 μm、5.82~26.23 μm、3.28~18.96 μm、39.62~201.59 μm、496.99~1 712.35 μm、25.53~86.94 μm和27%~66%,变异系数分别为40.11%,49.02%,50.08%,39.13%,32.04%,27.87%和59.09%。相关性分析结果显示,除角质层厚度与上表皮厚度、下表皮厚度、主脉厚度、CTR 之间以及下表皮厚度与栅栏组织厚度之间相关性不显著外,其余指标间均呈极显著相关。利用主成分分析筛选出角质层厚度、叶片厚度和 CTR 3个指标为杨树无性系抗旱性评价的主要指标,最后运用隶属函数法得出12个杨树无性系抗旱能力排序为：A50>Qg>Ti>A23>La>107>Ta>A54>I-101>A39>84K>Pa。【结论】叶片解剖结构指标能够较好地反映杨树的抗旱特性,可以作为评价杨树无性系抗旱能力的指标。无性系 A50、Qg、Ti、A23和La抗旱性较强,可作为优良杨树无性系进行推广。     

Potato and oat yield in short-cycle crop rotation with zeolite application

Data are given on the use of the zeolite clinoptilolite when growing potatoes in a short-cycle crop rotation. A positive effect of zeolite in a dose of 2.5 and 5 t/ha locally against the background of N₉₀P₉₀K₉₀ or 10 t/ha with uniform application against a background of N₉₀P₉₀K₉₀ and N₁₂₀P₉₀K₉₀ to the first crop (potatoes) is established. The use of zeolite allows reducing the basic fertilizer dose by 25% and growing annual grasses without fertilizers in the second and third years after its application.     

Precambrian sponges with cellular structures

Sponge remains have been identified in the Early Vendian Doushantuo phosphate deposit in central Guizhou (South China), which has an age of approximately 580 million years ago. Their skeletons consist of siliceous, monaxonal spicules. All are referred to as the Porifera, class Demospongiae. Preserved soft tissues include the epidermis, porocytes, amoebocytes, sclerocytes, and spongocoel. Among thousands of metazoan embryos is a parenchymella-type of sponge larvae having a shoe-shaped morphology and dense peripheral flagella. The presence of possible amphiblastula larva suggests that the calcareous sponges may have an extended history in the Late Precambrian. The fauna indicates that animals lived 40 to 50 million years before the Cambrian Explosion.     

Supertetrahedral sulfide crystals with giant cavities and channels

Although aluminosilicates and metal phosphates can form porous open-framework materials such as zeolites, sulfide analogs usually form high-density phases because of the relatively small tetrahedral angle at sulfur atoms. One strategy to overcome this limitation is to use tetrahedral clusters as the building blocks to achieve porous sulfide-based networks. The preparation and crystal structures of two indium sulfide open frameworks (ASU-31 and ASU-32) built of supertetrahedral clusters around organic template and water guests are described. ASU-31, based on the sodalite-tetrahedrite network, contains cavities 25.6 angstroms in diameter, and ASU-32, based on the tetragonal CrB4 network, contains channels with a minimum diameter of 14.7 angstroms. The organic cations can be completely exchanged with sodium ions in aqueous solution at room temperature without degradation of the crystals.     

平凉市农村城镇化发展水平的多维主成分分析与评价

在建立平凉市农村城镇化评价指标体系的基础上,借助SPSS统计分析软件,运用多维主成分分析法,以平凉32个小城镇(包括6个县镇,26个建制镇)为评价单元,分别求出各小城镇的人口、经济、生活水平、空间城镇化的主成分综合得分值,进而求出32个小城镇城镇化水平综合实力排序。     

番茄秸秆固定化芽孢杆菌M1对3环PAHs污染老化土壤修复效果

为探讨固定化微生物对煤矿区3环PAHs污染老化土壤的修复效果,以番茄秸秆为固定化载体材料,通过“吸附-包埋-交联法”形成了固定化芽孢杆菌微球,并采用土培试验对煤矿区土壤3环PAHs去除进行研究。结果表明,游离芽孢杆菌M1对煤矿区污染老化土壤单体芴（Flu）、菲（Phe）和蒽（Anth）的去除随接菌量的增加先升高后降低。在接菌量为1%、10%、20%（体积质量比）的游离芽孢杆菌处理中,10%处理（B2M1）对土壤Phe的去除率最高,为21.35%。不同接菌量的固定化芽孢杆菌M1微球处理对3种PAHs的去除率显著高于微球基质处理,其中,接菌量20%的固定化芽孢杆菌处理（X3M1）对土壤Flu的去除率最高,达95.25%,比不含M1菌株的番茄秸秆微球基质处理（X3）提高了12.03个百分点。对比分析扣除微球基质后的固定化M1与添加同等菌量的游离M1去除结果看出,经固定化后的菌株M1比游离菌M1显著促进了对煤矿区污染老化土壤3环PAHs的去除,不同接菌量对单体Flu和Anth去除率为72.17%~75.52%和8.97%~28.88%,分别比游离菌增加了64.10~72.31个百分点和8.13~15.24个百分点,单体Phe 1%接菌量处理比游离菌提高了5.07个百分点。从土壤酶活性看,土壤过氧化氢酶活性在固定化M1三种剂量处理下均显著高于微球基质和游离菌M1处理,随剂量增加依次是游离菌处理的1.16、1.23倍和1.20倍,是微球基质处理的1.28、1.19倍和1.16倍,与3环PAHs的去除率规律相一致,而固定化M1处理多酚氧化酶、过氧化物酶和纤维素酶活性相对于游离菌处理有不同程度的降低。综上,固定化芽孢杆菌M1对土壤3环PAHs去除具有显著促进作用,为煤矿区PAHs污染老化土壤原位修复的应用提供了重要技术参数与支撑。     

Imaging and manipulating molecules on a zeolite surface with an atomic force microscope

The adsorption of neutral molecules and ions on the surfaces of zeolites was observed in real time with an atomic force microscope (AFM). Direct imaging of the surface of the zeolite clinoptilolite was possible by using a diluted tert-butyl ammonium chloride solution as a medium. Images of the crystal in different liquids revealed that molecules could be bound to the surface in different ways; neutral molecules of tert-butanol formed an ordered array, whereas tert-butyl ammonium ions formed clusters. These absorbed molecules were not rearranged by the AFM tip when used in an imaging mode. However, when a sufficiently large force was applied, the tip of the AFM could rearrange the tert-butyl ammonium ions on the zeolite surface. This demonstration of molecular manipulation suggests new applications, including biosensors and lithography.     

沸石的载铁改性及除氟性能分析

以天然沸石为基质材料,采用硫酸、氢氧化钠和氯化铁对其改性,对模拟含氟水进行静态吸附试验,研究改性沸石对水中氟离子的吸附性能,探讨并提出了最佳改性条件。对沸石进行比表面积和孔径分布测定,并利用X射线荧光分析沸石改性前后的元素组成及含量变化。结果表明采用氯化铁单独改性效果最好。吸附速率可用拟二级动力学方程描述。氯化铁改性沸石对F^-的吸附符合Langmuir吸附等温模式,饱和吸附量为0.087 mg·g^-1,较未改性沸石有很大提高, 吸附平衡常数为0.28 L·mg^-1。改性后沸石的比表面积减小,Fe元素含量增加,Ca²⁺、Mg²⁺等离子的含量降低,说明氯化铁改性沸石除氟主要基于化学吸附与复杂的离子交换作用。     

树冠空间结构对微气候影响的模拟

随着城市化水平的提高,人们对于健康舒适的公共空间的要求也日益增加。为了更加科学地从空间结构的角度对微气候环境提出改善策略,运用ENVI-met模拟软件,以理想状态下的纯乔木林环境为研究对象,针对南京市的气候条件,分析5种常见的乔木树冠形态（圆柱形、圆球形、倒卵形、三角形和倒三角形）和3种平面布局形式（规则散点式、集中块状式、自然集群式）对微气候环境的温度、湿度及人体热舒适度（PMV指数）的影响。研究表明:树冠形态和布局形式对群落的降温增湿效应具有显著影响（P < 0.05）。“上大下小”型的倒卵形和倒三角形树冠的乔木群落降温增湿强度最高、人体热舒适度体验也最好。集中块状式布局的群落降温增湿强度要明显高于规则散点式和自然集群式,但自然集群式布局时人体热舒适度体验更好。     

IgG from patients with Lambert-Eaton syndrome blocks voltage-dependent calcium channels

Lambert-Eaton syndrome, an autoimmune disorder frequently associated with small-cell carcinoma of the lung, is characterized by impaired evoked release of acetylcholine from the motor nerve terminal. Immunoglobulin G (IgG) antibodies from patients with the syndrome, applied to bovine adrenal chromaffin cells, reduced the voltage-dependent calcium channel currents by about 40 percent. When calcium was administered directly into the cytoplasm, however, the IgG-treated cells exhibited normal exocytotic secretion, as assayed by membrane capacitance measurement. Measurement with the fluorescent calcium indicator fura-2 indicated that the IgG treatment reduced potassium-stimulated increase in free intracellular calcium concentration. The pathogenic IgG modified neither kinetics of calcium channel activation nor elementary channel activity, suggesting that a reduction in the number of functional calcium channels underlies the IgG-induced effect. Therefore, Lambert-Eaton syndrome IgG reacts with voltage-dependent calcium channels and blocks their function, a phenomenon that can account for the presynaptic impairment characteristic of this disorder.     

Carbon structures with three-dimensional periodicity at optical wavelengths

Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials.     

Anti-clogging performance evaluation and parameterized design of emitters with labyrinth channels

The anti-clogging performance of emitters with labyrinth channels is a key factor affecting their long-term service. Considering the limitation of evaluation on emitter's anti-clogging performance at present, a new method using passage rate of particles as the evaluation index was proposed based on stochastic trajectory model in a Lagrangian reference frame. Using orthogonal design, the passage rates of particles of 16 trapezoidal labyrinth channels with various geometries were calculated, where 4 dimensionless parameters were taken as the factors. The results obtained from analysis of range and variance showed that the influence degree on passage rate of particles ranks as follows: α > D/W > S/H > H/D. A mathematic model was established between the particle passage rate and 4 key parameters according to the multivariable regression method, which can be used to predict and compare the anti-clogging performance of trapezoidal labyrinth channels with different geometries.     

An antimony sulfide with a two-dimensional, intersecting system of channels

A novel open antimony sulfide framework of composition [Sb(3)S(5)](-) has been synthesized hydrothermally, in the presence of tetramethyl ammonium ions. Determination of the crystal structure demonstrates that the (Me(4)N)(+) molecules (Me, methyl) occlude a system of intersecting channels at 90 degrees to one another. The three-dimensional framework is assembled from a new building unit, flat s-shaped buckled sheets of edge-linked 4-rings containing Sb(2)S(2) moieties. These are cross-linked in two directions to form the system of channels.     

Direct imaging of transient molecular structures with ultrafast diffraction

Ultrafast electron diffraction (UED) has been developed to study transient structures in complex chemical reactions initiated with femtosecond laser pulses. This direct imaging of reactions was achieved using our third-generation apparatus equipped with an electron pulse (1.07 +/- 0.27 picoseconds) source, a charge-coupled device camera, and a mass spectrometer. Two prototypical gas-phase reactions were studied: the nonconcerted elimination reaction of a haloethane, wherein the structure of the intermediate was determined, and the ring opening of a cyclic hydrocarbon containing no heavy atoms. These results demonstrate the vastly improved sensitivity, resolution, and versatility of UED for studying ultrafast structural dynamics in complex molecular systems.