Higher and lower supramolecular orders for the design of self-assembled heterochiral tripeptide hydrogel biomaterials

The self-assembly behaviour of the eight stereoisomers of Val\u2013Phe\u2013Phe tripeptides under physiological conditions is assessed by several spectroscopy and microscopy techniques. We report the first examples of self-organised hydrogels from tripeptides in the L\u2013D\u2013L or D\u2013L\u2013D configuration, besides the expected gels with the D\u2013L\u2013L or L\u2013D\u2013D configuration, thus widening the scope for using amino acid chirality as a tool to drive self-assembly. Importantly, the positions of D- and L-amino acids in the gelling tripeptides determine a higher or lower supramolecular order, which translates into macroscopic gels with different rheological properties and thermal behaviours. The more durable hydrogels perform well in cytotoxicity assays, and also as peptides in solution. An appropriate design of the chirality of self-assembling sequences thus allows for the fine-tuning of the properties of the gel biomaterials. In conclusion, this study adds key details of supramolecular organization that will assist in the ex novo design of assembling chiral small molecules for their use as biomaterials

Design of a hydrophobic tripeptide that self-assembles into amphiphilic superstructures forming a hydrogel biomaterial

We report the rational design of a heterochiral hydrophobic tripeptide self-assembling into amphiphilic D-superstructures that yield a self-supportive hydrogel at physiological pH. The material endures cell culture conditions and sustains fibroblast proliferation. Tripeptide superstructures are thoroughly analysed by several techniques

Data-Driven Approaches to Measuring a Social Licence to Operate

Companies in the energy and resources sectors often conduct surveys to understand their acceptance within the community. Such surveys generate rich data, yet sometimes key insights can be missed using conventional plots of average responses for each question. Here, we investigated how multivariate statistics might be used to analyse and communicate information from a Social Impact Assessment of an Australian coal seam gas (LNG) project. The drivers of community acceptance were complex and impacts with the greatest/least average scores were not necessarily those most correlated with acceptance. For example, while housing affordability and availability were consistently seen as negative impacts, individuals’ views on employment and economic opportunities were better correlated with acceptance - even though these were, on average, not seen as positive or negative impacts of development. Consistent with previous statistical (path analysis) assessment of the same data, a perceptual map based on r-mode analyses suggested relational factors such as trust and perceptions of good environmental regulation were the most important drivers of acceptance of the LNG industry. Community response maps created using q-mode analyses represented the diversity of opinions for multiple drivers, highlighting that “the community” is not a uniform entity. For example, although those involved in (non-LNG) industry generally reported greater levels of acceptance and trust than others in the community, there were still some individuals within this group that did not trust or accept the LNG industry. While a SLO can be complex and is likely to constantly change, our study shows multidimensional scaling may be a useful tool for communicating social survey results to engineers and managers in a way that encapsulates some of the important details of a SLO, yet still be intuitive enough to include in reporting dashboards

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The matrix partial orderings considered are: (1) the star ordering and (2) the minus ordering or rank subtractivity, both in the set of m X n complex matrices, and (3) the Lowner ordering, in the set of m X m matrices. The problems discussed are: (1) inheriting certain properties under a given ordering, (2) preserving an ordering under some matrix multiplications, (3) relationships between an ordering among direct (or Kronecker) and Hadamard products and the corresponding orderings between the factors involved, (4) orderings between generalized inverses of a given matrix, and (5) preserving or reversing a given ordering under generalized inversions. Several generalizations of results known in the literature and a number of new results are derived

Djibouti: small state strategy at a crossroads

Geography and politics indicate Djibouti would be a particularly weak and ineffectual ‘small state’. Located on a bridgehead between the poorest parts of Africa and Arabia, it is continental Africa’s smallest state by population and is devoid of natural resources. The text demonstrates that Djibouti has been able to transform weakness and liabilities stemming from its geo-strategic location, sandwiched between large neighbours and key maritime shipping lanes, into a lucrative ‘resource’. This has been achieved via creative diplomacy, fostering ties with a diverse range of states, translating acute dependence into economic and diplomatic capital. The text focusses primarily upon diplomatic strategies, while addressing broader concerns of small states’ energy, infrastructure and development policies

Optimal design of water treatment processes

Predicted water shortages assign water treatment a leading role in improving water resources management. One of the main challenges associated with the processes remains early stage design of techno-economically optimised purification. This work addresses the current gap by undertaking a whole-system approach of flowsheet synthesis for the production of water at desired purity at minimum overall cost. The optimisation problem was formulated as a mixed-integer non-linear programming model. Two case studies were presented which incorporated the most common commercial technologies and the major pollution indicators, such as chemical oxygen demand, dissolved organic carbon, total suspended solids and total dissolved solids. The results were analysed and compared to existing guidelines in order to examine the applicability of the proposed approach

On the Non-Existence of Optimal Solutions and the Occurrence of “Degeneracy” in the CANDECOMP/PARAFAC Model

The CANDECOMP/PARAFAC (CP) model decomposes a three-way array into a prespecified number of R factors and a residual array by minimizing the sum of squares of the latter. It is well known that an optimal solution for CP need not exist. We show that if an optimal CP solution does not exist, then any sequence of CP factors monotonically decreasing the CP criterion value to its infimum will exhibit the features of a so-called “degeneracy”. That is, the parameter matrices become nearly rank deficient and the Euclidean norm of some factors tends to infinity. We also show that the CP criterion function does attain its infimum if one of the parameter matrices is constrained to be column-wise orthonormal

"Nested" cryptic diversity in a widespread marine ecosystem engineer: a challenge for detecting biological invasions

<p>Abstract</p> <p>Background</p> <p>Ecosystem engineers facilitate habitat formation and enhance biodiversity, but when they become invasive, they present a critical threat to native communities because they can drastically alter the receiving habitat. Management of such species thus needs to be a priority, but the poorly resolved taxonomy of many ecosystem engineers represents a major obstacle to correctly identifying them as being either native or introduced. We address this dilemma by studying the sea squirt <it>Pyura stolonifera</it>, an important ecosystem engineer that dominates coastal communities particularly in the southern hemisphere. Using DNA sequence data from four independently evolving loci, we aimed to determine levels of cryptic diversity, the invasive or native status of each regional population, and the most appropriate sampling design for identifying the geographic ranges of each evolutionary unit.</p> <p>Results</p> <p>Extensive sampling in Africa, Australasia and South America revealed the existence of "nested" levels of cryptic diversity, in which at least five distinct species can be further subdivided into smaller-scale genetic lineages. The ranges of several evolutionary units are limited by well-documented biogeographic disjunctions. Evidence for both cryptic native diversity and the existence of invasive populations allows us to considerably refine our view of the native versus introduced status of the evolutionary units within <it>Pyura stolonifera </it>in the different coastal communities they dominate.</p> <p>Conclusions</p> <p>This study illustrates the degree of taxonomic complexity that can exist within widespread species for which there is little taxonomic expertise, and it highlights the challenges involved in distinguishing between indigenous and introduced populations. The fact that multiple genetic lineages can be native to a single geographic region indicates that it is imperative to obtain samples from as many different habitat types and biotic zones as possible when attempting to identify the source region of a putative invader. "Nested" cryptic diversity, and the difficulties in correctly identifying invasive species that arise from it, represent a major challenge for managing biodiversity.</p