Exploiting Supramolecular Interactions from Polymeric Colloids for Strong Anisotropic Adhesion between Solid Surfaces

Adhesion occurs by covalent bonding, as in reactive structural adhesives, or through noncovalent interactions, which are nearly ubiquitous in nature. A classic example of the latter is gecko feet, where hierarchical features enhance friction across the contact area. Biomimicry of such structured adhesion is regularly achieved by top-down lithography, which allows for direction-dependent detachment. However, bottom-up approaches remain elusive given the scarcity of building blocks that yield strong, cohesive, self-assembly across multiple length scales. Herein, an exception is introduced, namely, aqueous dispersions of cellulose nanocrystals (CNCs) that form superstructured, adherent layers between solid surfaces upon confined evaporation-induced self-assembly (C-EISA). The inherently strong CNCs (E_A > 140 GPa) align into rigid, nematically ordered lamellae across multiple length scales as a result of the stresses associated with confined evaporation. This long-range order produces remarkable anisotropic adhesive strength when comparing in-plane (≈7 MPa) and out-of-plane (≤0.08 MPa) directions. These adhesive attributes, resulting from self-assembly, substantially outperform previous biomimetic adhesives obtained by top-down microfabrication (dry adhesives, friction driven), and represent a unique fluid (aqueous)-based system with significant anisotropy of adhesion. By using C-EISA, new emergent properties will be closely tied with the nature of colloids and their hierarchical assemblies.     

Modelling and solving spare parts supply chain network design problems

Spare parts are key operational assets in order to minimise unexpected equipment downtimes that may significantly impact a company’s results. The spare parts supply chain network supports the entire spare parts operations management and it is essential to achieve the planned goals. However, most of the traditional literature on spare parts management has not focused on the underlying supply chain network. Thus, this paper studies the integration of supply chain network design and control with traditional spare parts management. In particular, a generic network optimisation modelling structure is proposed, with simultaneous optimisation of warehouse locations and inventory control decisions, allowing minimising the total costs associated with the spare parts supply chain network. The generic model is specified based on three inventory control policies widely employed in the industry, which are suitable for managing a great variety of spare parts, i.e. (s, Q), (R, s, S) and (S-1, S). Furthermore, a solution approach is proposed based on Generalised Benders Decomposition. Finally, numerical results from a real-world application case in the process industry are shown and discussed.     

Effect of satisfaction with one''s abilities on positive and negative affect among individuals with recently diagnosed rheumatoid arthritis

An improved procedure for the synthesis of 3 beta-hydroxyandrost-5-ene-7,17-dione, a natural metabolite of dehydroepiandrosterone (DHEA) is described. The synthesis and magnetic resonance spectra of several other related steroids are presented. Feeding dehydroepiandrosterone to rats induces enhanced formation of several liver enzymes among which are mitochondrial sn-glycerol 3-phosphate dehydrogenase (GPDH) and cytosolic malic enzyme. The induction of these two enzymes, that complete a thermogenic system in rat liver, was used as an assay to search for derivatives of DHEA that might be more active than the parent steroid. Activity is retained in steroids that are reduced to the corresponding 17 beta-hydroxy derivative, or hydroxylated at 7 alpha or 7 beta, and is considerably enhanced when the 17-hydroxy or 17-carbonyl steroid is converted to the 7-oxo derivative. Several derivatives of DHEA did not induce the thermogenic enzymes whereas the corresponding 7-oxo compounds did. Both short and long chain acyl esters of DHEA and of 7-oxo-DHEA are active inducers of the liver enzymes when fed to rats. 7-Oxo-DHEA-3-sulfate is as active as 7-oxo-DHEA or its 3-acetyl ester, whereas DHEA-3-sulfate is much less active than DHEA. Among many steroids tested, those possessing a carbonyl group at position 3, a methyl group at 7, a hydroxyl group at positions 1, 2, 4, 11, or 19, or a saturated B ring, with or without a 4-5 double bond, were inactive.     

Rapid, quantitative nonisotopic assay for telomerase activity in human tumors

Telomerase is a ribonucleoprotein enzyme that adds TTAGGG repeats onto human telomeres, preventing their shortening. The activation of this enzyme is an important step in cell immortalization and carcinogenesis and seems to represent a new and promising marker in cancer diagnosis and management. Telomerase activity is usually detected in cellular protein extract by the telomeric repeat amplification protocol (TRAP) assay, which can provide only a qualitative (presence/absence) evaluation. Here we present a modification of this method that can provide quantitative information without requiring time-consuming post-PCR procedures such as gel electrophoresis with radioactive materials and autoradiography. The detection and measurement of telomerase activity is performed by evaluating the amount of double-stranded DNA generated in the telomerase reaction and PCR amplification, with the use of the sensitive DNA fluorescent dye PicoGreen. In a subset of tumors, the presence of telomerase activity was confirmed by the conventional TRAP assay. By this method we evaluated telomerase activity in unselected groups of breast (n = 15), ovarian (n = 12), endometrial (n = 12), gastric (n = 20), and renal (n = 12) carcinomas, in meningiomas (n = 8), and in pheochromocitomas (n = 10). The results indicate substantial differences of telomerase activity among cancer groups; however, a large variability among patients of the same group is observed. Kidney, ovarian, and breast carcinomas showed the highest mean values (31.8 +/- 28.9, 29.2 +/- 26.7, and 35.3 +/- 15.9 ng DNA/microg protein, respectively, mean +/- SD), whereas gastric and endometrial cancers had a lower activity (17.2 +/- 8.8 and 13.5 +/- 7.9 ng DNA/microg protein, respectively). Very low or no detectable telomerase activity was found in meningiomas (with the exception of one malignant atypical variant) and pheochromocitomas (9.7 +/- 12.9 and 2.8 +/- 2.1 ng DNA/microg protein, respectively). In conclusion, our method seems to be an accurate and reasonable procedure for measuring telomerase activity in human cancers.     

Structural Evaluation and Strengthening of a Reinforced Concrete Bridge

This paper deals with the structural evaluation and strengthening of a reinforced concrete bridge over the Arno River in Italy. In 1996 truckload tests and finite-element calculations were performed to assess the bridge condition. The structure was found to be inadequate to bear both the first- and the second-class road loads prescribed by the Italian Bridge Recommendations. The choice of its demolition and reconstruction was rejected, however, since it was too expensive and required a lot of time as well as dramatic inconveniences for the traffic and the road network. So a strengthening design was developed to upgrade the structure to a first-class bridge. The restoration work was performed from September 1999 to September 2000 and dealt with the main structural elements. After the completion of the work, the flexural stiffness was about 20% greater than that in the old structure, and the flexural strength at the midspan of the interior span was 70% greater.     

Integrating a collaboration script and group awareness to support group regulation and emotions towards collaborative problem solving

International Journal of Computer-Supported Collaborative Learning - The research landscape displays increasing awareness of the important role of self-regulation and emotions in the process of...     

Two‐Phase Emulgels for Direct Ink Writing of Skin‐Bearing Architectures

Direct ink writing (DIW) provides programmable and customizable platforms to engineer hierarchically organized constructs. However, one‐step, facile synthesis of such architectures via DIW has been challenging. This study introduces inks based on two‐phase emulgels for direct printing and in situ formation of protecting layers enveloping multicomponent cores, mimicking skin‐bearing biological systems. The emulgel consists of a Pickering emulsion with an organic, internal phase containing poly(lactic acid) stabilized by chitin/cellulose nanofibers and a continuous, cross‐linkable hydrogel containing cellulose nanofibers and any of the given solid particles. The shear during ink extrusion through nozzles of low surface energy facilitates the generation of the enveloped structures via fast and spontaneous phase separation of the emulgel. The skin‐bearing architectures enable control of mass transport as a novel configuration for cargo release. As a demonstration, a hydrophilic molecule is loaded in the hydrogel, which is released through the core and skin, enabling regulation of diffusion and permeation phenomena. This 3D‐printed functional material allows independent control of strength owing to the hierarchical construction. The new method of fabrication is proposed as a simple way to achieve protection, regulation, and sensation, taking the example of the functions of skins and cuticles, which are ubiquitous in nature.