Glass formation and meltability of metal-organic frameworks

Melt-quenched (MQ) glasses derived from metal-organic frameworks (MOFs) have emerged very recently as tunable organic-inorganic hybrid glasses, showing potential applications in gas separation. Zeolitic imidazolate frameworks (ZIFs) are a subclass of MOFs which have shown high meltability. ZIF-62, a mixed-linker ZIF, has been investigated extensively because of its low melting temperature and high thermal stability. Application of glasses formed from MOFs on an industrial scale requires large-scale production of parent crystals. However, in large-scale production of mixed-linker MOFs, both kinetics and thermodynamics of synthesis play significant roles. The importance of both factors originates from a heterogeneous linker distribution in mixed-linker MOFs where each type of linker can form different crystalline phases during synthesis, altering thermal properties and more importantly, the meltability. The parameters which affect the formation of different crystalline polymorphs in ZIF-62, and the methods required to detect such structural heterogeneity in the final material are investigated, while possible phase transformations are also discussed. Among a huge number of crystalline MOFs (over 70,000), only small number of them have shown the ability to melt. Decomposition of the framework prior to its melting transition is an obstacle hindering the transition to the liquid state while heating. Porosity and metal-ligand interactions have been identified as parameters determining meltability of such frameworks. To overcome these constraints, an ionic liquid (IL) containing its sodium salt was incorporated into the cages of ZIF-8, a highly porous, normally non-meltable ZIF. After mechanical amorphization, the structure of the resultant composite and stability of IL molecules in the collapsed pores were examined, and the effect of structural collapse on ionic conduction, as a macroscopic property, was investigated

Ionic liquid facilitated melting of the metal-organic framework ZIF-8.

Hybrid glasses from melt-quenched metal-organic frameworks (MOFs) have been emerging as a new class of materials, which combine the functional properties of crystalline MOFs with the processability of glasses. However, only a handful of the crystalline MOFs are meltable. Porosity and metal-linker interaction strength have both been identified as crucial parameters in the trade-off between thermal decomposition of the organic linker and, more desirably, melting. For example, the inability of the prototypical zeolitic imidazolate framework (ZIF) ZIF-8 to melt, is ascribed to the instability of the organic linker upon dissociation from the metal center. Here, we demonstrate that the incorporation of an ionic liquid (IL) into the porous interior of ZIF-8 provides a means to reduce its melting temperature to below its thermal decomposition temperature. Our structural studies show that the prevention of decomposition, and successful melting, is due to the IL interactions stabilizing the rapidly dissociating ZIF-8 linkers upon heating. This understanding may act as a general guide for extending the range of meltable MOF materials and, hence, the chemical and structural variety of MOF-derived glasses

Tunable broadband photoluminescence from bismuth‐doped calcium aluminum germanate glasses prepared in oxidizing atmosphere

Tunable photoluminescence (PL) from transparent inorganic glass matrices is of interest for applications demanding a semitransparent photoconverter that does not elastically scatter incoming light. For this purpose, bismuth (Bi)‐doped optical materials exhibit unique spectral characteristics in terms of bandwidth and emission tunability. Here, we demonstrate a facile route for preparing such converters from Bi‐doped calcium‐aluminate and calcium‐aluminogermanate glasses. These glasses offer tunable PL across the near violet and visible‐to‐near‐infrared (NIR) spectral range, with an emission lifetime in the range of 300 μs. The addition of GeO 2 exerts a decrease in optical basicity, which in turn enables the stabilization of NIR‐active low‐valence Bi species for broadband NIR PL

Analysis of the sharing economy effect on sustainability in the transportation sector using Fuzzy cognitive mapping

Along with the significant growth of the sharing economy in recent years, its effect on the economy, society, and the environment at the level of governments, academic communities, and researchers has been widely discussed. One of the main debates is identifying the side or negative effects of the sharing economy as well as its positive effects. Studying the cause-effect relationship of the variables affecting sustainability in the sharing economy context can provide valuable results for firms. For this purpose, fuzzy cognitive maps have been used. Based on the literature review, the sharing economy's essential variables that affect sustainability were identified, and using the Fuzzy Delphi method, these variables were localized. Snapp and Tap30 were selected as two of the largest platforms in the Iranian transportation sector. Fuzzy cognitive maps based on aggregated opinions of experts were inputted to the Mental Modeler online software to drawn the cognitive map of this research. The degree of centrality index, i.e., the summation of input and output degree, was used to identify the most relevant sustainability variables. Consequently, the incentives to make a greater use of the platform, the income of drivers, the monopoly power of platforms, the price of services, the higher service quality of platforms, the use of private vehicles by passengers, and the change of traffic in cities were identified as variables with the greatest effect on stability. Four positive loops and one negative loop were identified among these seven variables in the cause-effect analysis. In the final section, some suggestions are presented based on each loop

Sodium Ion Conductivity in Superionic IL-Impregnated Metal-Organic Frameworks: Enhancing Stability Through Structural Disorder

Abstract: Metal-organic frameworks (MOFs) are intriguing host materials in composite electrolytes due to their ability for tailoring host-guest interactions by chemical tuning of the MOF backbone. Here, we introduce particularly high sodium ion conductivity into the zeolitic imidazolate framework ZIF-8 by impregnation with the sodium-salt-containing ionic liquid (IL) (Na0.1EMIM0.9)TFSI. We demonstrate an ionic conductivity exceeding 2 × 10−4 S · cm−1 at room temperature, with an activation energy as low as 0.26 eV, i.e., the highest reported performance for room temperature Na+-related ion conduction in MOF-based composite electrolytes to date. Partial amorphization of the ZIF-backbone by ball-milling results in significant enhancement of the composite stability towards exposure to ambient conditions, up to 20 days. While the introduction of network disorder decelerates IL exudation and interactions with ambient contaminants, the ion conductivity is only marginally affected, decreasing with decreasing crystallinity but still maintaining superionic behavior. This highlights the general importance of 3D networks of interconnected pores for efficient ion conduction in MOF/IL blends, whereas pore symmetry is a less stringent condition

Research Records and Possibilities of the Department of Pharmacology Physiology in Kerman University of Medical Sciences, Iran

Background: The publication of information and possibilities of a university department and the experiences of its faculty members make others aware of these issues and can be regarded as one of the methods of publishing and teaching science. It seems that the report of research experiences, capabilities, and achievements in Department of Pharmacology Physiology, Kerman University of Medical Sciences, Iran, make it easier for further researches of other researchers. Methods: Data were obtained via observing, searching in valuable scientific databases and group archives, and asking the department manager, faculty members, and experts in Department of Pharmacology Physiology, as well as gathering the information in research centers of the university. Results: Department of Physiology and Pharmacology was the first group that initiated postgraduate and doctoral degrees’ courses at Kerman University of Medical Sciences. The annual per capita of paper production in this group was close to 7 with 10 faculty members. Three faculty members were among the first 15 of the university in terms of the H-index. The country, provincial, university, and faculty rankings achieved by the department, variety in research projects, and the collaborative studies in the university were the features of this department. The first and second research centers of the university in terms of history and rank were managed by faculty members of this department. Conclusion: Department of Pharmacology Physiology is one of the successful and high history departments in Kerman University of Medical Sciences. Other researchers can use the experience of these faculty members, and department facilities for their advancement. Keywords Physiology; research; Equipment; Department; Pharmacy facult

Genetic diversity of six isolated populations of the leopard moth, Zeuzera pyrina (Lep: Zeuzeridae)

The leopard moth, Zeuzera pyrina (Lep: Zeuzeridae), is an important pest of a wide range of trees and shrubs including walnut and apple across the world. The natural populations of the leopard moth in different geographical areas of Iran show significant differences in some of their biological characteristics such as time of emergence, generation time and host specificity. So, we hypothesized that these populations may represent different subspecies that move toward a speciation event in their evolutionary route. In this study, we evaluated the genetic diversity of six different geographically isolated populations of the leopard moth using the sequence alignment of cytochrome oxidase c subunit one (COI). A fragment of 642 base pairs was amplified in all six populations and the phylogenetic tree was created based on sequenced fragments. Our results revealed significant differences in the nucleotide sequence of COI gene in these populations. Differences in climatic conditions of these regions seem to be the most powerful force driving this diversity among the studied populations

New records of Iranian bark beetles (Coleoptera: Curculionidae, Scolytinae) and their host plants

Amini, Sudabe, Nozari, Jamasb, Mandelshtam, Michail Yu., Knížek, Miloš, Etemad, Vahid, Faccoli, Massimo (2017): New records of Iranian bark beetles (Coleoptera: Curculionidae, Scolytinae) and their host plants. Zootaxa 4350 (2), DOI: https://doi.org/10.11646/zootaxa.4350.2.1