Magnetic Phase Transitions in a Ni4O4-Cubane-Based Metal–Organic Framework

An unprecedented spin cluster-based network architecture {[Ni^II₂(pdaa)(OH)₂(H₂O)]_n (H₂pdaa=1,4-phenylene diacetic acid)}, comprising 1D linear chains of Ni^II ions crosslinked via Ni₄O₄ cubanes, forms under hydrothermal conditions; this 3D coordination network exhibits magnetic ordering at 23.9 K as well as a second magnetic ordering process at 2.8 K likely associated with a structural phase transition.     

A quasi-crystal model of collagen microstructure based on SHG microscopy

<正>Second harmonic generation(SHG) results from molecules which are polarized by an external electric field often provided by an intense laser beam.The polarizability depends on firstly the intrinsic structural properties of the substance and hence the second-order nonlinear susceptibility,and secondly the intensity and polarization direction of the incident light.The polarization characteristics of the beam are therefore of interest.In this letter,we discuss some considerations in SHG microscopy of collagen when the incoming beam is circularly polarized,and present some supporting results as well as a numerical analysis.We propose a quasi-crystal model of collagen microstructure in an effort to further our understanding on this protein.     

Engineering a material for biomedical applications with electric field assisted processing

In this work, using multiple co-flows we demonstrate in-situ encapsulation of nano-particles, liquids and/or gases in different structural morphologies, which can also be deposited in a designated pattern by a direct write method and surface modification can be controlled to release encapsulated material. The range of possibilities offered by exposing a material solution to an applied electric field can result in a plethora of structures which can accommodate a whole host of biomedical applications from microfluidic devices (microchannels, loaded with various materials), printed 3D structures and patterns, lab-on-a-chip devices to encapsulated materials (capsules, tubes, fibres, dense multi-layered fibrous networks) for drug delivery and tissue engineering. The structures obtained in this way can vary in size from micrometer to the nanometer range and the processing is viable for all states of matter. The work shown demonstrates some novel structures and methodologies for processing a biomaterial.     

Electrospinning versus fibre production methods: from specifics to technological convergence

Academic and industrial research on nanofibres is an area of increasing global interest, as seen in the continuously multiplying number of research papers and patents and the broadening range of chemical, medical, electrical and environmental applications. This in turn expands the size of the market opportunity and is reflected in the significant rise of entrepreneurial activities and investments in the field. Electrospinning is probably the most researched top-down method to form nanofibres from a remarkable range of organic and inorganic materials. It is well known and discussed in many comprehensive studies, so why this review? As we read about yet another "novel" method producing multifunctional nanomaterials in grams or milligrams in the laboratory, there is hardly any research addressing how these methods can be safely, consistently and cost-effectively up-scaled. Despite two decades of governmental and private investment, the productivity of nanofibre forming methods is still struggling to meet the increasing demand. This hinders the further integration of nanofibres into practical large-scale applications and limits current uses to niche-markets. Looking into history, this large gap between supply and demand of synthetic fibres was seen and addressed in conventional textile production a century ago. The remarkable achievement was accomplished via extensive collaborative research between academia and industry, applying ingenious solutions and technological convergence from polymer chemistry, physical chemistry, materials science and engineering disciplines. Looking into the present, current advances in electrospinning and nanofibre production are showing similar interdisciplinary technological convergence, and knowledge of industrial textile processing is being combined with new developments in nanofibre forming methods. Moreover, many important parameters in electrospinning and nanofibre spinning methods overlap parameters extensively studied in industrial fibre processing. Thus, this review combines interdisciplinary knowledge from the academia and industry to facilitate technological convergence and offers insight for upscaling electrospinning and nanofibre production. It will examine advances in electrospinning within a framework of large-scale fibre production as well as alternative nanofibre forming methods, providing a comprehensive comparison of conventional and contemporary fibre forming technologies. This study intends to stimulate interest in addressing the issue of scale-up alongside novel developments and applications in nanofibre research.     

Symbolic Computation for Rankin-Cohen Differential Algebras: A Case Study

Don Zagier defined a “Rankin-Cohen algebra”, motivated by the study of differential operators that send modular forms to modular forms. We devised an algorithm that computes the result of the differentiation given by the modular forms that correspond to higher-order Wronskians over Klein’s quartic curve, which are modular forms of arbitrarily high degree canonically attached to the curve; this tool is potentially useful for finding commutative rings of differential operators.     

Thermosensitive dendrimer formulation for drug delivery at physiologically relevant temperatures

A simple and versatile dendrimer based platform to deliver therapeutic agents at temperatures within the physiological range, is reported. Lipoic acid conjugated at the periphery of the thermosensitive dendrimer formulations undergoes slow and sustained release at 37-42 °C, and rescues the cells from oxidative stress and a pro-inflammatory endotoxic agent.     

Sequence‐Defined Heteromultivalent Precision Glycomacromolecules Bearing Sulfonated/Sulfated Nonglycosidic Moieties Preferentially Bind Galectin‐3 and Delay Wound Healing of a Galectin‐3 Positive Tumor Cell Line in an In Vitro Wound Scratch Assay

Within this work, a new class of sequence‐defined heteromultivalent glycomacromolecules bearing lactose residues and nonglycosidic motifs for probing glycoconjugate recognition in carbohydrate recognition domain (CRD) of galectin‐3 is presented. Galectins, a family of β‐galactoside‐binding proteins, are known to play crucial roles in different signaling pathways involved in tumor biology. Thus, research has focused on the design and synthesis of galectin‐targeting ligands for use as diagnostic markers or potential therapeutics. Heteromultivalent precision glycomacromolecules have the potential to serve as ligands for galectins. In this work, multivalency and the introduction of nonglycosidic motifs bearing either neutral, amine, or sulfonated/sulfated groups are used to better understand binding in the galectin‐3 CRD. Enzyme‐linked immunosorbent assays and surface plasmon resonance studies are performed, revealing a positive impact of the sulfonated/sulfated nonglycosidic motifs on galectin‐3 binding but not on galectin‐1 binding. Selected compounds are then tested with galectin‐3 positive MCF 7 breast cancer cells using an in vitro would scratch assay. Preliminary results demonstrate a differential biological effect on MCF 7 cells with high galectin‐3 expression in comparison to an HEK 293 control with low galectin‐3 expression, indicating the potential for sulfonated/sulfated heteromultivalent glycomacromolecules to serve as preferential ligands for galectin‐3 targeting.     

Numerical solution of the acoustic wave equation using Raviart–Thomas elements

In this paper we discuss the numerical approximation of the displacement form of the acoustic wave equation using mixed finite elements. The mixed formulation allows for approximation of both displacement and pressure at each time step, without the need for post-processing. Lowest-order and next-to-lowest-order Raviart–Thomas elements are used for the spatial discretization, and centered finite differences are used to advance in time. Use of these Raviart–Thomas elements results in a diagonal mass matrix for resolution of pressure, and a mass matrix for the displacement variable that is sparse with a simple structure. Convergence results for a model problem are provided, as are numerical results for a two-dimensional problem with a point source.     

What Difference Does a Methyl Group Make: Pentamethylbenzene?

The crystal structure of pentamethylbenzene has been obtained for the first time with the use of synchrotron radiation, whilst the low‐energy spectrum of lattice dynamics, dominated by the methyl group torsions, was obtained using inelastic neutron scattering. The effect of symmetry lowering by the removal of a single methyl group relative to hexamethylbenzene has been investigated, including the role that this plays in the charge‐transfer characteristics of complexes formed with tetracyanoethylene.