Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks.

Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes.

[Shrimp community structure and its relationships with environmental factors in the Yellow Sea in summer].

Based on the data collected from the bottom trawl survey in Yellow Sea, August, 2014, the community structure of shrimp assemblage and its relationships with environmental factors in summer was examined by using index of relative importance, ecological diversity indices and multivariate statistical analysis. A total of 20 shrimp species were captured, belonging to 3 orders, 10 families, 16 genera. The relative abundance of shrimp of all stations ranged from 13 to 45047 g · h(-1) and its mean value was 6838 g · h(-1). The dominant species was Crangon affinis, and the common species was Eualus sinensis. The rare species were Metapenaeopsis dalei, Palaemon gravieri and Oratosquilla oratoria. The ranges of Shannon diversity index (H) , Pielou' s evenness index (J) and the Margalef' s species richness index (D) of all stations of the shrimp community structure were 0.007-1.538, 0.101-1.138 and 0.006-0.947, respectively, and the mean values of H, Jand D were 0.391, 0.374 and 0.298, respectively. MDS and Cluster analyses revealed that two clusters of Group I named cold water mass group and Group II named coastal group, which were bounded by the 45 m isobaths, were identified for all the sampling stations. Significant difference was detected by ANOSIM analysis between Group I and Group II. BIOENV analysis indicated that bottom temperature and bottom salinity were the most important environmental factors for structuring the spatial distribution of the shrimp assemblage. Cold water mass group accounted for absolute advantage and Yellow Sea cold mass had a decisive influence on the distribution pattern of the shrimp community in the Yellow Sea in summer.

Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, 27Al/29Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications.

One-pot Solvothermal Synthesis of Well-ordered Layered Sodium Aluminoalcoholate Complex: A Useful Precursor for the Preparation of Porous Al2O3 Particles.

One-pot solvothermal synthesis of a robust tetranuclear sodium hexakis(glycolato)tris(methanolato)aluminate complex Na3[Al4(OCH3)3(OCH2CH2O)6] via a modified yet rigorous base-catalyzed transesterification mechanism is presented here. Single crystal X-ray diffraction (SCXRD) studies indicate that this unique Al complex contains three penta-coordinate Al3+ ions, each bound to two bidentate ethylene glycolate chelators and one monodentate methanolate ligand. The remaining fourth Al3+ ion is octahedrally coordinated to one oxygen atom from each of the six surrounding glycolate chelators, effectively stitching the three penta-coordinate Al moieties together into a novel tetranuclear Al complex. This aluminate complex is periodically self-assembled into well-ordered layers normal to the [110] axis with the intra-/inter-layer bindings involving extensive ionic bonds from the three charge-counterbalancing Na+ cations rather than the more typical hydrogen bonding interactions as a result of the fewer free hydroxyl groups present in its structure. It can also serve as a valuable precursor toward the facile synthesis of high-surface-area alumina powders using a very efficient rapid pyrolysis technique.

Designed single-step synthesis, structure, and derivative textural properties of well-ordered layered penta-coordinate silicon alcoholate complexes.

The controllable synthesis of well-ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5-coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction-quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self-assemble into a dimeric asymmetric secondary BU via strong Na(+)-O(2-) ionic bonds. The designed one-pot synthesis is straightforward, robust, and efficient, leading to a well-ordered (10i)-parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na(+) counter-ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7 m(2) g(-1) for the pyrolyzed intrinsic and B-assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal-organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.

[Ecological carrying capacity of Chinese shrimp stock enhancement in Laizhou Bay of East China based on Ecopath model].

Stock enhancement is an important way of fishery resources conservation, which can increase the high quality fishery resources and improve the fish population structure. The study of ecological carrying capacity is the premise for the scientific implementation of stock enhancement. Based on the survey data of the fishery resources and ecological environment in Laizhou Bay from 2009 to 2010, an Ecopath mass-balance model of the Laizhou Bay ecosystem consisted of 26 functional groups was constructed, and applied to analyze the overall characteristics of the ecosystem, the trophic interrelationships, and the keystone species, and to calculate the ecological carrying capacity of Chinese shrimp enhancement. As for the overall characteristics of the ecosystem, the total primary production/total respiration (TPP/TR) was 1. 53, total primary production/total biomass (TPP/B) was 24.54, Finn' s cycling index was lower (0.07), surplus production was higher (434. 41 t km-2 a-1 ), and system connectance index was lower (0. 29), indicating that this ecosystem was at an early development stage. The analysis on the keystone species showed that Chinese shrimp was not a keystone species of this ecosystem. At present, the biomass of Chinese shrimp in the ecosystem was 0. 1143 t km-2, with a greater potential of continued enhancement. It did not exceed the ecological carrying capacity of 2. 9489 t km-2 when the biomass of the Chinese shrimp was increased by 25. 8 times.

[Ecological niche breadth and niche overlap of dominant species of fish assemblage in Yangtze river estuary and its adjacent waters].

Based on the fishery resources data from the bottom trawl surveys conducted on the R/V Beidou in the Yangtze River estuary and its adjacent waters in June, August and October of 2006, the index of relative importance (IRI) was measured to determine the dominant species of fish assemblage, and the niche indicators and their seasonal variations of the dominant species were analyzed. A total of 10 dominant species in the 3 survey cruises were recorded, which were divided into two groups by the Bray-curtis similarity clustering and non-metric multidimensional scaling (MDS) analysis, with a significant seasonal variation of niche breadth and niche overlap. One group included Engraulis japonicus, Champsodon capensis, and Acropoma japonicum, whose niche breadth and niche overlap were larger in summer than in autumn, with a migration from the Yangtze River estuary and its adjacent waters to outer deeper waters, while the other group included Trichiurus haumela, Chaeturichthys stigmatias, Apogon lineatus, Larimichthys polyactis, Psenopsis anomala, Argyrosomus argentatus, and Benthosema pterotum, whose niche breadth and niche overlap were larger in autumn than in summer, with a reverse migration from southern Yellow Sea and northern East China Sea to the Yangtze River estuary and its adjacent waters. The different migration direction of the two groups was related to their ecological habits and environmental factors.

[Spatial distribution of wintering Engraulis japonicus and its relationship with the inter-annual variations of water temperature in central and southern Yellow Sea].

Abstract: This paper studied the inter-annual variations in the spatial distribution of wintering anchovy (Engraulis japonicus) in central and southern Yellow Sea, based on the 1986-2010 bottom trawl survey data and related sea surface temperature (SST) data obtained by remote sensing, and approached the relationships between the inter-annual variations in the spatial distribution of the wintering anchovy and the SST, by using GIS technique, spatial analysis and correlation analysis. In 1986-2010, the wintering anchovy in the study area had apparent inter-annual variations in spatial distribution, with its abundance dropped to the lowest level and its distribution moved shoreward in 2004, and the abundance rebounded and centralized in the eastern waters in 2010. The centralized distribution regions of the anchovy's capture locations and stock density in longitudinal and latitudinal directions also had apparent inter-annual variations. There was a significant correlation between the latitude of the anchovy's stock density center and the mean latitude of the representative isotherms, suggesting that the variations in water temperature had effects on the latitudinal distribution of the wintering anchovy, and whether the anchovy distributed shoreward or not was determined by the inter-annual variations of Yellow Sea Warm Current. Among the factors affecting the anchovy distribution, fishing pressure was the main factor affecting the changes in anchovy abundance, and water temperature mainly determined the changes in anchovy spatial distribution.