Solution of preemptive multi-objective network design problems applying Benders decomposition method

This paper deals with preemptive priority based multi-objective network design problems in which construction times together with travel costs are taken into account. These cost and time objective functions are ordered lexicographically with respect to manager’s strategies in order to decrease total cost and total construction time of the network. To solve this preemptive problem, instead of the standard sequential approach, a modified Benders decomposition algorithm is developed. It is proved that this algorithm decreases the (expected) number of computations and so this algorithm is efficient for large-scale network design problems.     

Pressure‐Tuneable Visible‐Range Band Gap in the Ionic Spinel Tin Nitride

The application of pressure allows systematic tuning of the charge density of a material cleanly, that is, without changes to the chemical composition via dopants, and exploratory high‐pressure experiments can inform the design of bulk syntheses of materials that benefit from their properties under compression. The electronic and structural response of semiconducting tin nitride Sn₃N₄ under compression is now reported. A continuous opening of the optical band gap was observed from 1.3 eV to 3.0 eV over a range of 100 GPa, a 540 nm blue‐shift spanning the entire visible spectrum. The pressure‐mediated band gap opening is general to this material across numerous high‐density polymorphs, implicating the predominant ionic bonding in the material as the cause. The rate of decompression to ambient conditions permits access to recoverable metastable states with varying band gaps energies, opening the possibility of pressure‐tuneable electronic properties for future applications.     

Targeted Delivery of Anticancer Drug Loaded Charged PLGA Polymeric Nanoparticles Using Electrostatic Field

Pure positive electrostatic charges (PPECs) show suppressive effect on the proliferation and metabolism of invasive cancer cells without affecting normal tissues. PPECs are used for the delivery of drug-loaded polymeric nanoparticles (DLNs) capped with negatively charged poly(lactide-co-glycolide) (PLGA) and Poly(vinyl-alcohol) PVA into the tumor site of mouse models. The charged patch is installed on top of the skin in the mouse models' tumor region, and the controlled selective release of the drug is assayed by biochemical, radiological, and histological experiments on both tumorized models and normal rats' livers. It is found that DLNs synthesized by PLGA show great attraction to PPECs due to their stable negative charges, which would not degrade immediately in blood. The burst and drug release after less than 48h of this synthesized DLNs are 10% and 50%, respectively. These compounds can deliver the loaded-drug into the tumor site with the assistance of PPECs, and the targeted-retarded release will take place. Hence, local therapy can be achieved with much lower drug concentration (conventional chemotherapy [2 mg kg⁻¹] versus DLNs-based chemotherapy [0.75 mg kg⁻¹]) with negligible side effects in non-targeted organs. PPECs have many potential clinical applications for advanced-targeted chemotherapy with the lowest discernible side effects.     

Graphene‐Functionalized 3D‐Carbon Fiber Electrodes – Preparation and Electrochemical Characterization

Graphene nanosheets were produced on the surface of carbon fibers by in situ electrochemical procedure including oxidative and reductive steps to yield first graphene oxide, later converted to graphene. The electrode material composed of graphene‐functionalized carbon fibers was characterized by scanning electron microscopy (SEM) and cyclic voltammery demonstrating superior electrochemical kinetics comparing with the original carbon paper. The interfacial electron transfer rate for the reversible redox process of [Fe(CN)₆]^3?/4? was found ca. 4.5‐fold higher after the electrode modification with the graphene nanosheets. The novel electrode material is suggested as a promising conducting interface for bioelectrocatalytic electrodes used in various electrochemical biosensors and biofuel cells, particularly operating in vivo.     

Supercontinuum generation with femtosecond optical pulse compression in silicon photonic crystal fibers at 2500 nm

In this paper, femtosecond optical pulses compression and supercontinuum generation in a triangular silicon photonic crystal fiber at 2500 nm are investigated. A region of large minimum anomalous group velocity dispersion, negligible higher order dispersions and unique nonlinearity of silicon are used to demonstrate compression of 100 fs initial input optical pulses to 2.5 fs and ultra-broadband supercontinuum generation with very low input pulse energy over short distances of the fiber.     

Structure of polymeric carbon dioxide CO2-V

The structure of polymeric carbon dioxide (CO2-V) has been solved using synchrotron x-ray powder diffraction, and its evolution followed from 8 to 65 GPa. We compare the experimental results obtained for a 100% CO2 sample and a 1 mol?% CO2/He sample. The latter allows us to produce the polymer in a pure form and study its compressibility under hydrostatic conditions. The high quality of the x-ray data enables us to solve the structure directly from experiments. The latter is isomorphic to the β-cristobalite phase of SiO2 with the space group I42d. Carbon and oxygen atoms are arranged in CO4 tetrahedral units linked by oxygen atoms at the corners. The bulk modulus determined under hydrostatic conditions, B0=136(10) GPa, is much smaller than previously reported. The comparison of our experimental findings with theoretical calculations performed in the present and previous studies shows that density functional theory very well describes polymeric CO2.     

Regiocontrolled synthesis of the trimeric quinone framework of conocurvone

[reaction: see text] The trimeric quinone framework of conocurvone is crucial for its potent anti-HIV activity. A new synthesis of trimeric quinones based on stepwise substitution of the halogens in 2,3-dihaloquinones by hydroxyquinone anions is described. Chlorinated biquinones are key intermediates that undergo regiospecific substitution reactions to yield trimeric quinone monomethyl ethers.     

On the Stress Field of a Nonlinear Elastic Solid Torus with a Toroidal Inclusion

Standard measures of local deformation such as deformation gradient, strain, elastic deformation, and plastic deformation are dimensionless. However, many macroscopic and submacroscopic geometrical changes observed in continuous bodies result in the formation of zones across whose boundaries significant changes in geometry can occur. In order to predict the sizes of such zones and their influence on material response, theories of elasticity and plasticity have been employed in which second gradients of deformation, gradients of strain, as well as gradients of elastic or of plastic deformation are taken into account. The theory of structured deformations provides additive decompositions of first deformation gradient and of second deformation gradient, valid for large deformations of any material, in which each term has a multiscale geometrical interpretation corresponding to the presence or absence of submacroscopic disarrangements (non-smooth geometrical changes such as slips and void formation). This article provides a field theory that broadens the earlier field theory, elasticity with disarrangements, by including energetic contributions from submacroscopic “gradient-disarrangements” (limits of averages of jumps in gradients of approximating deformations) and by treating particular kinematical conditions as internal constraints. An explicit formula is obtained showing the manner in which submacroscopic gradient-disarrangements determine a defectiveness density analogous to the dislocation density in theories of plasticity. A version of the new field theory incorporates this defectiveness density to obtain a counterpart of strain-gradient plasticity, while another instance of elasticity with gradient-disarrangements recovers an instance of strain-gradient elasticity with symmetric Cauchy stress. All versions of the new theory included here are compatible with the Second Law of Thermodynamics.     

Reducing negative effects of quadratic norm regularization on image reconstruction in electrical impedance tomography

Employing the conventional quadratic norm to regularize the inverse problem in electrical impedance tomography often stabilizes the solution at the expense of imposing some smoothness on the reconstructed image. This study proposes a novel multi-regularized approach in order for quadratic norm regularization to reduce its deleterious effects on the reconstructed image. The amounts of regularization exerted on the finite elements over the mesh are not kept constant, but are changed depending on either the sensitivity of the boundary measurements to the finite elements, or the anomaly positioning. The results show that the proposed schemes appreciably improve the image with regard to spatial resolution, artifact, and shape preservation. These schemes considerably reduce the unappealing sensitivity of the inverse solution to the regularization parameter changes as well.     

Finite-element simulation of ultrasound brain surgery: effects of frequency, focal pressure, and scanning path in bone-heating reduction

In this paper, the finite-element method (FEM) simulation of ultrasound brain surgery is presented. The overheating problem of the post-target bone, which is one of the limiting factors for a successful ultrasound brain surgery, is considered. In order to decrease bone heating, precise choices of frequency, focal pressure, and scanning path are needed. The effect of variations in the mentioned scanning parameters is studied by means of the FEM. The resulting pressure and temperature distributions of a transdural ultrasound brain surgery are simulated by employing the FEM for solving the Helmholtz and bioheat equations in the context of a two-dimensional MRI-based brain model. Our results show that for a suitable value of the frequency, an increase in focal pressure leads to a decrease in the required duration of the treatment and is associated with less heating of the surrounding normal tissue. In addition, it is shown that at a threshold focal pressure, the target temperature reaches toxic levels whereas the temperature rise in the bone is minimal. Wave reflections from sinus cavities, which result in constructive interference with the incoming waves, are one of the reasons for overheating of the bone and can be avoided by choosing a suitable scanning path.