Two Calorimetrically Distinct States of Liquid Water Below 150 Kelvin

Vapor-deposited amorphous solid and hyperquenched glassy water were found to irreversibly transform, on compression at 77 kelvin, to a high-density amorphous solid. On heating at atmospheric pressure, this solid became viscous water (water B), with a reversible glass-liquid transition onset at 129 +/- 2 kelvin. A different form of viscous water (water A) was formed by heating the uncompressed vapor-deposited amorphous solid and hyperquenched liquid water. On thermal cycling up to 148 kelvin, water B remained kinetically and thermodynamically distinct from water A. The occurrence of these two states, which do not interconvert, helps explain both the configurational relaxation of water and stress-induced amorphization.     

The structure of confined oxygen in silica xerogels

The microscopic structure of oxygen confined in silica xerogels has been studied as a function of temperature. In large pores, a crystalline solid forms with a structure consistent with that of the bulk. The size of the crystallites is much larger than the pore size, indicating that cooperative effects among pores are important in freezing. As the pore size is decreased, a crossover occurs where solidification results in an amorphous phase in the pores. The resulting amorphous phase is solid but is less ordered than the liquid phase.     

Controlling the morphology of amorphous solid water

The morphology of amorphous solid water grown by vapor deposition was found to depend strongly on the angular distribution of the water molecules incident from the gas phase. Systematic variation of the incident angle during deposition using a collimated beam of water led to the growth of nonporous to highly porous amorphous solid water. The physical and chemical properties of amorphous solid water are of interest because of its presence in astrophysical environments. The ability to control its properties in the laboratory may shed light on some of the outstanding conflicts related to this important material.     

Structural Memory in Pressure-Amorphized AlPO4

Molecular dynamics simulations reveal the mechanism of the structural memory effect in alpha-berlinite (AlPO(4)), where a single crystal transforms to an amorphous solid by compression and then reverts to the original crystalline structure upon release of pressure. The enhanced oxygen coordination around the aluminum atoms in AlPO(4) at high pressure leads to a mechanical instability that causes the phase transformation. The difference in the structural memory behavior between AlPO(4) and isostructural alpha-quartz, for which the pressure-induced amorphized phase is recoverable, can be attributed to the presence of the PO(4) units, which remain essentially four-coordinated even when severely distorted.     

Bond selectivity in silicon film growth

Hydrogen atoms can selectively eliminate strained bonds that form during the growth of amorphous silicon films. By periodically interrupting the growth and exposing the grown material to hydrogen, the film composition can be varied continuously from a non-equilibrium amorphous structure to that of a crystalline solid. Furthermore, by tuning the hydrogen exposure it is possible to discriminate between Si-Si bonds formed on different substrates, thereby allowing substrate-selective growth. The evolution of the film structure during hydrogen exposure is directly observed by scanning tunneling microscopy, and a model describing the role of hydrogen is presented.     

Continuous random network model for amorphous solid water

Continuous random network models representing amorphous solid water have been constructed. The x-ray and neutron scattering predictions for one type of model agree quite well with experimental results.     

西昌邛海青河入湖口水质调查研究

以西昌邛海湖青河为研究对象,通过对青河入湖口水质的pH、化学需氧量（COD）、5日生化需氧量（BOD5）、固体悬浮物（SS）、总氮（TN）、总磷（TP）、溶解氧（DO）的试验检测,根据实际检测数据,对西昌邛海湖东侧入口支流青河入湖口水质进行分析研究。结果表明,青河入湖口水质较好,处于地表水环境质量标准Ⅰ～Ⅱ类。同时,根据研究结果,结合周围环境与社会经济发展状况,以期为青河流域环境保护提供一定的科学依据。     

固体水对苗木作用效应的研究

固体水为干旱、半干旱地区的抗旱造林提供了一种新的途径 .为了有效地指导其在野外造林的应用 ,在温室可控条件下 ,从植物水分状况、土壤含水量变化及微生物数量等方面 ,研究了固体水对北方主要造林树种油松和侧柏苗木生长的影响 .结果表明 ,使用固体水可提高土壤含水量 ,明显改善苗木的水分状况 ,减轻水分胁迫 ,其中效果最佳的是接触面积为 5 0cm2 的纯固体水和 38cm2 的加剂固体水 .根据固体水释水速率和供试苗木的水分状况及生长表现 ,在没有其它水源补充的条件下 ,艾德迈尔固体水至少可以维持油松和侧柏苗木生长 2个月     

固体水对苗木作用效应的研究

固体水为干旱、半干旱地区的抗旱造林提供了一种新的途径.为了有效地指导其在野外造林的应用,在温室可控条件下,从植物水分状况、土壤含水量变化及微生物数量等方面,研究了固体水对北方主要造林树种油松和侧柏苗木生长的影响.结果表明,使用固体水可提高土壤含水量,明显改善苗木的水分状况,减轻水分胁迫,其中效果最佳的是接触面积为50?cm2的纯固体水和38?cm2的加剂固体水.根据固体水释水速率和供试苗木的水分状况及生长表现,在没有其它水源补充的条件下,艾德迈尔固体水至少可以维持油松和侧柏苗木生长2个月.     

生鲜食品导热系数影响因素的试验与分析

采用同步测量法测定了不同品种果蔬的导热系数与其可溶性固形物含量、自由水含量、含水量、密度、硬度等因素的变化规律.结果表明,对于不同种类的果蔬,与其导热系数存在显著线性相关的因素从大到小依次是含水量、可溶性固形物含量、自由水含量和密度,而和果蔬的硬度不存在显著线性相关关系.     

取代酚类极性有机物C_(18)膜/水分配行为的研究

采用C18膜模拟生物体及高效液相色谱分析方法，探讨了极性有机化合物取代酚在C18膜与水相之间的分配规律，研究了pH和盐度对分配的影响，测定厂取代酚的C18膜／水分配系数Ksd。结果表明，取代酚达到分配平衡的时间很短，其C18膜／水分配系数不会因分配时间的延长而增大；随着取代酚的正辛醇／水分配系数的增大，化合物从水中向C18膜转化的比例逐渐增加，其相应的C18膜／水分配系数也随之增加；盐度的增加对极性化合物C18膜／水分配系数的大小没有显著的影响；pH的增大将降低化合物的分配系数。通过C18膜／水分配规律的研究，可以推测生物体或环境介质对取代酚类化合物的积累程度，由此可以较直观地评价该类化合物的环境持久性，以及因脂溶性所产生的生物基线毒性。为取代酚类化合物的生态风险评价和管理提供科学依据。     

紫色丘陵区农林混作模式的土壤抗冲性影响因素

 【目的】研究土壤抗冲性的影响因素。【方法】采用原状土冲刷试验及室内土壤理化性质分析的方法,对紫色丘陵区农林混作模式的土壤抗冲性影响因素进行研究。【结果】（1）容重与土壤抗冲指数呈正相关,总孔隙度与土壤抗冲指数呈负相关。在短历时高强度的冲刷条件下,紫色土的土壤容重越大,孔隙度越小,土壤越紧实,其抗冲性能越强;（2）土壤抗冲指数与细砂粒（0.25～0.05 mm）含量呈显著正相关且表现为指数函数关系,说明较粗颗粒的存在有助于提高土壤抵抗径流冲刷的能力;（3）＞5 mm水稳性团聚体与土壤抗冲指数呈极显著正相关,＞0.25 mm水稳性团聚体与土壤抗冲指数呈显著正相关,大粒径水稳性团聚体含量越高,土壤结构越好,土粒越不易被径流冲散,土壤抗冲性能越强;（4）土壤抗冲指数随稳渗率、初渗率呈线性变化,分别呈极显著正相关和显著正相关;（5）不同径级根系生物量均与土壤抗冲指数呈极显著正相关,根密度与土壤抗冲指数呈显著正相关,＜3 mm根系长度与土壤抗冲指数也呈显著正相关;根系的存在有效地提高了土壤抗冲性。【结论】土壤容重、细砂粒含量、＞5 mm水稳性团聚体含量、稳渗率、＜1 mm根系生物量可用于该地区土壤抗冲性的预测和评价。     

藻类对池塘水环境的影响及水生植物和鲢鳙对水体的净化

利用生态浮床植物和鲢鳙对池塘养殖污染水体净化效果进行了研究。结果表明:藻类代谢对地表水中DO和p H均产生影响。藻类光合作用增加水体中含氧量,吸收二氧化碳影响水中碳酸及碳酸盐浓度平衡,导致水中p H偏向碱性。水体溶解氧增加,促进硝化反应,避免氨氮和亚硝态氮的积累。生态浮床黄花鸢尾长势很好,它的生长有效控制了水体氮磷含量的进一步提高,对水体具有较强的去除氮磷能力。鲢鳙摄食浮游生物等天然饵料,实现了水体氮磷转移,42.67 kg渔获物,提取氮1 207.5 g,剔除水体中氮0.905 mg/L,提取磷88.4 g,剔除水体中磷0.066 mg/L,起到了净化水体作用。试验证明:浮游植物、水生植物和鲢鳙对调控水域生态环境有着十分重要的作用。     

Amorphous solid water: a neutron diffraction study

The structure factor of amorphous solid D(2)O deposited from the vapor at 10 degrees K has been obtained by measuring the neutron diffraction spectrum in the wave vector transfer from 0.8 to 12.3 reciprocal angstroms. The results indicate that the phase investigated is amorphous and has a liquiid-like structure factor. The Fourier-transformed structure e factor yields a real space pair distribution function consistent with local tetrahedral coordination and hydrogen bonding, as in other condensed phases of water. The intramolecular OD separation is 1.00 angstrom; the lack of data for very large wave vector transfer and the expected near equality of the intramolecular DD separation and intermolecular O . . . D separation make it impossible to determine the intramolecular DOD angle with precision. The neutron scattering data presented are complementary to the x-ray diffraction studies of Venkatesh, Rice, antd Narten.     

Importance of surface morphology in interstellar H2 formation

Detailed laboratory experiments on the formation of HD from atom recombination on amorphous solid water films show that this process is extremely efficient in a temperature range of 8 to 20 kelvin, temperatures relevant for H2 formation on dust grain surfaces in the interstellar medium (ISM). The fate of the 4.5 electron volt recombination energy is highly dependent on film morphology. These results suggest that grain morphology, rather than the detailed chemical nature of the grain surface, is most important in determining the energy content of the H2 as it is released from the grain into the ISM.     

11个造林树种在京北荒滩应用固体水效果比较研究

以往研究表明,固体水能够提高造林成活率,特别在困难立地造林应用中已取得较好效果。为进一步选择应用固体水效果较好的树种,为今后困难立地造林树种选择提供参考,于2004年4月在北京市延庆县龙庆峡荒滩进行固体水多树种造林应用试验。通过分析树种成活率和相关生长指标,对比研究固体水多树种应用效果。结果表明,在荒滩造林绿化中,固体水能够提高各供试树种成活率和生长指标;银杏、旱柳、国槐、新疆杨、白榆、侧柏、刺槐、毛白杨和樟子松等9个树种应用固体水效果较好。     

生化处理模式下生猪养殖污水特征分析与水质评价

  目的  研究生化处理模式下的生猪养殖污水特征,找到一种合理、快速的水质评价方法,为猪场及相关监管部门了解污水处理情况提供理论依据。  方法  以浙北一家规模猪场为采样点,于2018年秋至2020年秋对处理后的养殖污水进行随机采样。先采用SPSS软件对样本进行统计特征分析,然后利用逐步多元回归分析方法确定影响污水水质的关键指标,再结合水质指标之间的相关性建立生猪污水最小水质指数评价模型。  结果  ①水质呈现季节性变化特征,春、夏季节水质优于秋、冬季节,尤其是夏季水质最好;②基于电导率和化学需氧量2个关键指标建立的最小水质指数评价模型的决定系数为0.994,该模型的验证结果表明:通过其评价的水质结果与基于氨氮、化学需氧量、总氮、总磷和酸碱度共5个指标的评价结果一致程度可达90%以上。  结论  基于关键指标构建的最小水质指数模型具有准确性和合理性,可用于生化处理模式下生猪养殖污水水质的快速评价。图4表3参28     

不同密度铜锈环棱螺对不同水体指标影响效果的研究

研究了铜锈环棱螺对2种不同水体中CODMn、叶绿素a、NH3-N、NO3-N和TP的去除效果。结果表明：铜锈环棱螺对于水体中的CODMn、叶绿素a、氮、磷等有一定的去除效果,放养密度、水质肥瘦度、培养时间等3个因素对其去除率存在显著性差异。具体表现为：放养铜锈环棱螺密度与其耗氧速率呈正相关;水体中叶绿素a含量呈现同步降低的规律,但在培养后期（7 d后）,2组不同肥瘦度水样中叶绿素含量均下降不明显,即消除率降低;随着培养时间的延长,水样中的COD含量普遍有所增加;NH3-N和NO3-N的去除率在一定条件下与放养密度、水质肥瘦度以及培养时间存在差异性。因此,针对不同肥瘦度的水体,不同的水质指标,应该选择不同的投放密度以达到比较满意的净化效果。     

海南岛中部山区热带天然林生态功能价值分析

对海南中部山区热带天然林改良土壤、固土、保肥、蓄水调水、净化水质、固碳释氧、净化空气、生物多样性保育、生态旅游等生态功能进行价值评估,得到2010年海南中部生态功能保护区热带天然林主要生态功能性综合价值为330.648亿元/a,相当于当年海南省GDP的16.1%。海南中部山区热带天然林对海南的生态安全起着屏障作用。     

Denitrification rates in an island bay in the equatorial pacific ocean

Experimental data show that (15)N-labeled nitrate can be converted to molecular nitrogen in sea water containing little or no oxygen. The process is presumed to be biochemical. No evidence of the reaction was found in the water of the Peru current, which is low in oxygen but high in nitrite.