The founding in 1965 of what is now called the Cambridge Structural Database (CSD) has reaped dividends in numerous and diverse areas of chemical research. Each of the million or so crystal ...structures in the database was solved for its own particular reason, but collected together, the structures can be reused to address a multitude of new problems. In this Review, which is focused mainly on the last 10 years, we chronicle the contribution of the CSD to research into molecular geometries, molecular interactions, and molecular assemblies and demonstrate its value in the design of biologically active molecules and the solid forms in which they are delivered. Its potential in other commercially relevant areas is described, including gas storage and delivery, thin films, and (opto)electronics. The CSD also aids the solution of new crystal structures. Because no scientific instrument is without shortcomings, the limitations of CSD research are assessed. We emphasize the importance of maintaining database quality: notwithstanding the arrival of big data and machine learning, it remains perilous to ignore the principle of garbage in, garbage out. Finally, we explain why the CSD must evolve with the world around it to ensure it remains fit for purpose in the years ahead.
The program Mercury, developed at the Cambridge Crystallographic Data Centre, was originally designed primarily as a crystal structure visualization tool. Over the years the fields and scientific ...communities of chemical crystallography and crystal engineering have developed to require more advanced structural analysis software. Mercury has evolved alongside these scientific communities and is now a powerful analysis, design and prediction platform which goes a lot further than simple structure visualization.
An overview of Mercury 4.0, an analysis, design and prediction platform that acts as a hub for the entire Cambridge Structural Database software suite, is presented.
Salivary concentrations of unconjugated steroids reflect those for free steroids in serum although concentrations may differ because of salivary gland metabolism. Samples for salivary steroid ...analysis are stable for up to 7 days at room temperature, one month or more at 4 degrees C and three months or more at -20 degrees C. When assessed against strict criteria, the evidence shows that salivary cortisol in evening samples or following dexamethasone suppression provides a reliable and effective screen for Cushing's syndrome. Sequential salivary cortisol measurements are also extremely helpful for the investigation of suspected cyclical Cushing's syndrome. There is potential for the identification of adrenal insufficiency when used with Synacthen stimulation. Salivary 17-hydroxyprogesterone and androstenedione assays are valued as non-invasive tests for the home-monitoring of hydrocortisone replacement therapy in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. The diagnostic value of salivary oestradiol, progesterone, testosterone, dehydroepiandrosterone and aldosterone testing is compromised by rapid fluctuations in salivary concentrations of these steroids. Multiple samples are required to obtain reliable information, and at present the introduction of these assays into routine laboratory testing is not justified.
We report the generation and characterization of the most complete collection of metal–organic frameworks (MOFs) maintained and updated, for the first time, by the Cambridge Crystallographic Data ...Centre (CCDC). To set up this subset, we asked the question “what is a MOF?” and implemented a number of “look-for-MOF” criteria embedded within a bespoke Cambridge Structural Database (CSD) Python API workflow to identify and extract information on 69 666 MOF materials. The CSD MOF subset is updated regularly with subsequent MOF additions to the CSD, bringing a unique record for all researchers working in the area of porous materials around the world, whether to perform high-throughput computational screening for materials discovery or to have a global view over the existing structures in a single resource. Using this resource, we then developed and used an array of computational tools to remove residual solvent molecules from the framework pores of all the MOFs identified and went on to analyze geometrical and physical properties of nondisordered structures.
We introduce a new generation of PARSEC-COLIBRI stellar isochrones that includes a detailed treatment of the thermally pulsing asymptotic giant branch (TP-AGB) phase, covering a wide range of initial ...metallicities (0.0001 < Zi < 0.06). Compared to previous releases, the main novelties and improvements are use of new TP-AGB tracks and related atmosphere models and spectra for M and C-type stars; inclusion of the surface H+He+CNO abundances in the isochrone tables, accounting for the effects of diffusion, dredge-up episodes and hot-bottom burning; inclusion of complete thermal pulse cycles, with a complete description of the in-cycle changes in the stellar parameters; new pulsation models to describe the long-period variability in the fundamental and first-overtone modes; and new dust models that follow the growth of the grains during the AGB evolution, in combination with radiative transfer calculations for the reprocessing of the photospheric emission. Overall, these improvements are expected to lead to a more consistent and detailed description of properties of TP-AGB stars expected in resolved stellar populations, especially in regard to their mean photometric properties from optical to mid-infrared wavelengths. We illustrate the expected numbers of TP-AGB stars of different types in stellar populations covering a wide range of ages and initial metallicities, providing further details on the "C-star island" that appears at intermediate values of age and metallicity, and about the AGB-boosting effect that occurs at ages close to 1.6-Gyr for populations of all metallicities. The isochrones are available through a new dedicated web server.
Contemporary cities are thick with infrastructure. In recognition of this fact a great deal of recent work within urban studies and urban geography has focused on transformations in the governance ...and ownership of infrastructural elements within cities. Less attention has been paid to the practices through which urban infrastructures are inhabited by urban dwellers. Yet in all sorts of ways infrastructures are realised through their use and inhabitation. This paper argues for the importance of attending to the ways that infrastructures are reinterpreted through use. Focusing on a case study of commuter cyclists in London, it explores the ways in which cyclists accommodate themselves to (and are in turn accommodated by) the infrastructural orderings of London's streets. Confronted by the obduracy of a road infrastructure designed primarily for motorised traffic, cyclists show a diverse range of approaches to negotiating movement through the city on bikes. The paper describes how this negotiation can be understood in terms of the more or less skilful processes of navigation, rule following, rule making, and rule bending. This involves a polymorphous mix of practices, some common to driving, others to walking, and yet others unique to cycling. In conclusion, the paper suggests that transformations of infrastructures found within cities need to be understood as much through emergent changes between their elements, and that close attention to how infrastructures come to be inhabited offers productive avenues for thinking about ways to improve them.
Large-scale targeted exploration of metal-organic frameworks (MOFs) with characteristics such as specific surface chemistry or metal-cluster family has not been investigated so far. These definitions ...are particularly important because they can define the way MOFs interact with specific molecules (
e.g.
their hydrophilic/phobic character) or their physicochemical stability. We report here the development of algorithms to break down the overarching family of MOFs into a number of subgroups according to some of their key chemical and physical features. Available within the Cambridge Crystallographic Data Centre's (CCDC) software, we introduce new approaches to allow researchers to browse and efficiently look for targeted MOF families based on some of the most well-known secondary building units. We then classify them in terms of their crystalline properties: metal-cluster, network and pore dimensionality, surface chemistry (
i.e.
functional groups) and chirality. This dynamic database and family of algorithms allow experimentalists and computational users to benefit from the developed criteria to look for specific classes of MOFs but also enable users - and encourage them - to develop additional MOF queries based on desired chemistries. These tools are backed-up by an interactive web-based data explorer containing all the data obtained. We also demonstrate the usefulness of these tools with a high-throughput screening for hydrogen storage at room temperature. This toolbox, integrated in the CCDC software, will guide future exploration of MOFs and similar materials, as well as their design and development for an ever-increasing range of potential applications.
Large-scale targeted exploration of metal-organic frameworks (MOFs) with characteristics such as specific surface chemistry or metal-cluster family has not been investigated so far.
Period-luminosity (PL) sequences of long-period variables (LPVs) are commonly interpreted as different pulsation modes, but there is disagreement on the modal assignment. Here, we re-examine the ...observed PL sequences in the Large Magellanic Cloud, including the sequence of long secondary periods (LSPs), and their associated pulsation modes. First, we theoretically model the sequences using linear, radial, nonadiabatic pulsation models and a population synthesis model of the LMC red giants. Then, we use a semi-empirical approach to assign modes to the pulsation sequences by exploiting observed multi-mode pulsators. As a result of the combined approaches, we consistently find that sequences B and C′ both correspond to first overtone pulsation, although there are some fundamental mode pulsators at low luminosities on both sequences. The masses of these fundamental mode pulsators are larger at a given luminosity than the mass of the first overtone pulsators. These two sequences, B and C′, are separated by a small period interval in which large amplitude pulsation in a long secondary period (sequence D variability) occurs, meaning that the first overtone pulsation is not seen as the primary mode of pulsation. Observationally, this leads to the splitting of the first overtone pulsation sequence into the two observed sequences, B and C′. Our two independent examinations also show that sequences A′, A, and C correspond to third overtone, second overtone, and fundamental mode pulsation, respectively.
Over the years, the β-glucan of oats and barley has been the subject of study either because of the importance of the cholesterol-lowering potential to health claims (FDA 1997, 2005) or, in the case ...of barley, because of the role of β-glucan and β-glucan-rich endosperm cell walls in malting and brewing. β-Glucan is also present in rye and in much lesser amounts in wheat. The most striking difference in these latter two sources is the difficulty in extractability; alkali rather than water is required for significant release from the cell walls. This review will discuss physicochemical properties of oat and rye β-glucan and, where information allows, relate these to physiological effects. Viscosity, or more generally rheology, plays a central role in discussions of cereal β-glucan functionality and physiological effects and will be the focus of this review.
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