Postsynthetic modification of zirconium metal-organic frameworks

Metal-organic frameworks (MOFs) have been in the spotlight for a number of years due to their chemical and topological versatility. As MOF research has progressed, highly functionalised materials have become desirable for specific applications, and in many cases the limitations of direct synthesis have been realised. This has resulted in the search for alternative synthetic routes, with postsynthetic modification (PSM), a term used to collectively describe the functionalisation of pre-synthesised MOFs whilst maintaining their desired characteristics, becoming a topic of interest. Advances in the scope of reactions performed are reported regularly; however reactions requiring harsh conditions can result in degradation of the framework. Zirconium-based MOFs present high chemical, thermal and mechanical stabilities, offering wider opportunities for the scope of reaction conditions that can be tolerated, which has seen a number of successful examples reported. This microreview discusses pertinent examples of PSM resulting in enhanced properties for specific applications, alongside fundamental transformations, which are categorised broadly into covalent modifications, surface transformations, metalations, linker and metal exchange, and cluster modifications

Closing the loop: assisting archival appraisal and information retrieval in one sweep

In this article, we examine the similarities between the concept of appraisal, a process that takes place within the archives, and the concept of relevance judgement, a process fundamental to the evaluation of information retrieval systems. More specifically, we revisit selection criteria proposed as result of archival research, and work within the digital curation communities, and, compare them to relevance criteria as discussed within information retrieval's literature based discovery. We illustrate how closely these criteria relate to each other and discuss how understanding the relationships between the these disciplines could form a basis for proposing automated selection for archival processes and initiating multi-objective learning with respect to information retrieval

Managing Complexity in Modern Farming

Modern farming in Australia is no longer simple. Farms are large, multi-enterprise businesses underpinned by expensive capital investments, changing production technologies, volatile markets and pervasive regulation. The complexity of modern broadacre farming leads to the question: what is the nature of the relationship between farm business complexity and farm profitability? This study uses bioeconomic farm modelling and employs eight measures of complexity to examine the profitability and complexity of a wide range of broadacre farming systems in Australia. Rank order correlations between farm profitability and each measure of complexity show inconsistent relationships, although the most profitable farming systems are found to be reasonably complex on several criteria. Among the set of highly profitable systems are found some characterised by less complexity. Using the farmer’s annual hours worked as a measure of complexity that affects current farm management, the trade-off between profit and this measure of complexity is found not to be large. A case is outlined where the farmer’s annual hours worked could be reduced by 9 percent for a 3 percent reduction in farm profit. If farmers’ workloads are proving problematic now and in the future, then agricultural R&D, service delivery and policy development will need to focus much more on being highly attractive to time-poor farm managers.complexity, farm modelling, management, profitability, Farm Management,

Digital forensics formats: seeking a digital preservation storage format for web archiving

In this paper we discuss archival storage formats from the point of view of digital curation and preservation. Considering established approaches to data management as our jumping off point, we selected seven format attributes which are core to the long term accessibility of digital materials. These we have labeled core preservation attributes. These attributes are then used as evaluation criteria to compare file formats belonging to five common categories: formats for archiving selected content (e.g. tar, WARC), disk image formats that capture data for recovery or installation (partimage, dd raw image), these two types combined with a selected compression algorithm (e.g. tar+gzip), formats that combine packing and compression (e.g. 7-zip), and forensic file formats for data analysis in criminal investigations (e.g. aff, Advanced Forensic File format). We present a general discussion of the file format landscape in terms of the attributes we discuss, and make a direct comparison between the three most promising archival formats: tar, WARC, and aff. We conclude by suggesting the next steps to take the research forward and to validate the observations we have made

The Carbon Challenge for Mixed Enterprise Farms

As part of its climate change policy the Australian government has introduced a Mandatory Renewable Energy Target (MRET) scheme and is also attempting to introduce a Carbon Pollution Reduction Scheme (CPRS). Using as a case study a main agricultural region of Australia, this paper examines how farming systems in this region may be affected by the medium term policy settings of these two schemes. A bio-economic model of the region’s farming systems is developed and used to assess the schemes’ impacts on the nature and profitability of the farming systems. Results show a range of profit and enterprise impacts across the range of farming systems. Farms as providers of biomass for electricity generation and small users of electricity are liable to benefit from the MRET scheme, with the extent of benefit depending on the price offered for biomass. By contrast, the CPRS is liable to more profoundly affect farming systems, especially if agriculture is included in the scheme. The impacts of the CPRS on agriculture are mostly conditional on: the amount of free permits allocated to agriculture, the value of trees as carbon sinks, the extent of pass-through of CPRS-related costs onto agriculture and emission permit prices. Dependent on these factors, farm profits can increase by up to 20 percent or decrease by over 30 percent, relative to the ‘no CPRS’ or ‘business-as-usual’ case. If agriculture is covered by the CPRS, and emission permits and tree growth rates are sufficiently high then optimal farm plans typically involve a combination of reduced livestock numbers, the planting of permanent stands of trees on marginal farmland and other changes to the enterprise mix on farms that reduce emissions.agriculture, greenhouse gases, economic modelling, sequestration, Agricultural and Food Policy, Crop Production/Industries, Environmental Economics and Policy, Institutional and Behavioral Economics, International Relations/Trade, Land Economics/Use,

Dryland Salinity: Spatial Impacts and Farmers' Options

The salinisation of farmland in Australia is a major natural resource management problem. Over the next 20 years a further 1.1 million hectares of broadacre farmland is predicted to become salt-affected. This paper firstly explores the spatial ramifications of the spread of salinity in Australia's agricultural regions. Some of the nation's most profitable grain growing regions will become seriously affected by salinity over the next 20 years. Secondly this paper outlines the nature, uptake and profitability of various salinity management options available to Australian farmers. These options include preventative and containment measures, such as engineering solutions and adoption of deep-rooted perennials, and other options involving adaptation to more saline environments such as commercial use of saline water and salt tolerant fodder plants. Deep-rooted perennial fodder species appear to offer the best short to medium term prospect for managing salinity in most agricultural zones. However, in many situations perennials may not be profitable at the scale required to have a significant impact on the rate of spread of salinity on farmland, or the rate of increase of saltload in rivers and streams.Farm Management,

A problem in optimal search and stop

Problem in optimal search and sto

Crystallographic investigation into the self-assembly, guest binding, and flexibility of urea functionalised metal-organic frameworks

Introduction of hydrogen bond functionality into metal-organic frameworks can enhance guest binding and activation, but a combination of linker flexibility and interligand hydrogen bonding often results in the generation of unwanted structures where the functionality is masked. Herein, we describe the self-assembly of three materials, where Cd2+, Ca2+, and Zn2+ are linked by N,Nʹ-bis(4-carboxyphenyl)urea, and examine the effect of the urea units on structure formation, the generation of unusual secondary building units, structural flexibility, and guest binding. The flexibility of the Zn MOF is probed through single-crystal to single-crystal transformations upon exchange of DMF guests for CS2, showing that the lability of the [Zn4O(RCO2)6] cluster towards solvation enables the urea linkers to adopt distorted conformations as the MOF breathes, even facilitating rotation from the trans/trans to the trans/cis conformation without compromising the overall topology. The results have significant implications in the mechanistic understanding of the hydrolytic stability of MOFs, and in preparing heterogeneous organocatalysts