Convex Modeling of Interactions With Strong Heredity

We consider the task of fitting a regression model involving interactions among a potentially large set of covariates, in which we wish to enforce strong heredity. We propose FAMILY, a very general framework for this task. Our proposal is a generalization of several existing methods, such as VANISH, hierNet, the all-pairs lasso, and the lasso using only main effects. It can be formulated as the solution to a convex optimization problem, which we solve using an efficient alternating directions method of multipliers (ADMM) algorithm. This algorithm has guaranteed convergence to the global optimum, can be easily specialized to any convex penalty function of interest, and allows for a straightforward extension to the setting of generalized linear models. We derive an unbiased estimator of the degrees of freedom of FAMILY, and explore its performance in a simulation study and on an HIV sequence dataset. Supplementary materials for this article are available online.     

Environmental corporate responsibility for investments evaluation: an alternative multi-objective programming model

The manufacturer who is a supplier of trade credit may face non-payment risk from customers and a capital shortage problem simultaneously. Trade credit insurance, as one of the most important risk management tools, has been widely used in companies’ daily operation. In this study, the manufacturer who allows customers to delay payment for goods already delivered purchases trade credit insurance to transfer and reduce non-payment risk and borrows money from a bank to accommodate the capital constraint problem. The Stackelberg game and loss-averse theory are used to establish a newsboy model including trade credit insurance, and the optimal insurance coverage and total sales of the manufacturer are thereby investigated. Subsequently, the interest rate decision of the bank under different risk-averse situations is also characterized. We find that the interest rate set by a loss-averse bank is equal to or greater than that given by a risk-neutral bank. The use of trade credit insurance can help the manufacturer expand sales and dramatically reduce its default risk. Both the bank and the manufacturer are better off due to the use of trade credit insurance, but contrary to what one might expect, the bank prefers giving a higher interest rate to the manufacturer when the premium rate is in a reasonable region, which indicates that the manufacturer cannot use the insurance to negotiate better financing terms.     

Biomedical application of responsive ‘smart’ electrospun nanofibers in drug delivery system: A minireview

Electrospinning is a versatile method for producing continuous nanofibers. It has since become an easy and cost-effective technique in the manufacturing process and drawn keen interests in most biomedical field applications. Nanofibers have garnered great attention in nanomedicine due to their resemblance with the extracellular matrix (ECM). Like nanoparticles, its unique characteristics of higher surface-to-volume ratio and the tunability of the polymers utilizing nanofiber have increased the efficiency in encapsulation and drug-loading capabilities. Smart or “stimuli-responsive” polymers have shown particular fascination in controlled release, where their ability to react to minor changes in the environment, such as temperature, pH, electric field, light, or magnetic field, distinguishes them as intelligent. Polymers are a popular material for the design of drug delivery carriers; consequently, various types of drugs, including antiviral, proteins, antibiotics, DNA and RNA, are successfully encapsulated in the pH-dependent nanofibers with smart polymers which is a polymer that can respond to change such as pH change, temperature. In this minireview, we discuss applications of smart electrospun pH-responsive nanofibers in the emerging biomedical developments which includes cancer drug targeting, oral controlled release, wound healing and vaginal drug delivery.     

Green biocomposites of chitosan dispersed in natural rubber matrices,and their urea controlled-release application

A green biocomposite comprising chitosan dispersed in partially cross-linked natural rubber matricesd was prepared. The starting materials and biocomposites were characterized by means of Fourier transform–infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Chitosan was found well dispersed in partially cross-linked natural rubber matrices indicating that natural rubber latex is successfully stabilized by sodium dodecyl sulfate. The swelling study of the biocomposites was carried out in several solvents. The biocomposites were used for the controlled-release of urea. The release behavior was found consistent, controlled, and prolonged over a period of 72 h. The Korsmeyer–Peppas model was applied to the experimental data and the possible release mechanism was found Fickian diffusion, which indicates that the polymer relaxation time is much greater than the characteristic solvent diffusion time.     

Temperature stability of the interfacial structure between a sulfonated crystalline alkyl side-chain polymer and a soft adhesive

The fracture toughness of interfaces between a sulfonated alkyl side-chain graft copolymer and a soft acrylic random copolymer containing acrylic acid monomers was investigated with a probe test method. Interfaces between a thin (100 nm) layer of the block copolymer and a thick (100 microm) layer of the acrylic copolymer were prepared at room temperature and subsequently annealed for 7 h at different temperatures. After the annealing step, the interface was quenched to room temperature and tested, a strategy that provides the advantage of keeping constant the mechanical properties of the materials on both sides of the interface so that any major difference in adhesive behavior can only be attributed to a change in the interfacial structure. For annealing temperatures below the crystalline to liquid crystalline transition temperature (86 degrees C), the adhesion energy remained very low and failure occurred by interfacial crack propagation. However when the interface was annealed above that temperature, a much higher adhesion energy was observed at room temperature because of the formation of a fibrillar structure upon debonding. The results indicate that the crystalline order at low temperature is very stable presumably because of the strong interactions between the sulfone groups in the side chains. However, when these interactions weaken and the side chains become liquid crystalline, the surface reconstruction mechanism cannot be prevented and strong interactions formed between the polar parts of the copolymer and the acrylic acid. These strong interactions remain during the cooling step, and a mechanism of surface reconstruction is proposed.     

Physical Properties of III-Antiminodes --- a First Principles Study

A comprehensive first principles study of III-Antimonide binary compounds ishardly found in literature. We report a broad study of structural and electronicproperties of boron antimonide (BSb), aluminium antimonide (AlSb), galliumantimonide (GaSb) and indium antimonide (InSb) in zincblende phase based on density functional theory (DFT). Our calculations are based onFull-Potential Linearized Augmented Plane wave plus local orbitals(FP-L(APW+lo)) method. Different forms of exchange-correlation energyfunctional and corresponding potential are employed for structural andelectronic properties. Our computed results for lattice parameters, bulkmoduli, their pressure derivatives, and cohesive energy are consistent withthe available experimental data. Boron antimonide is found to be the hardestcompound of this group. For band structure calculations, in addition to LDAand GGA, we used GGA-EV, an approximation employed by Engel and Vosko. The band gap results with GGA-EV are of significant improvement over the earlier work.     

The effect of stereotomy on the shape of the thrust-line and the minimum thickness of semicircular masonry arches

More than a century ago, the Serbian engineer and astronomer Milutin Milankovitch presented a remarkable formulation for the thrust-line of arches that do not sustain tension, and by taking radial cuts and a polar coordinate system, he published for the first time the correct and complete solution for the theoretical minimum thickness, t, of a monolithic semicircular arch with radius R. This paper shows that Milankovitch’s solution, t/R = 0.1075, is not unique and that it depends on the stereotomy exercised. The adoption of vertical cuts which are associated with a cartesian coordinate system yields a neighboring thrust-line and a different, slightly higher value for the minimum thickness (t/R = 0.1095) than the value computed by Milankovitch. This result has been obtained in this paper with a geometric and a variational formulation. The Milankovitch minimum thrust-line derived with radial stereotomy and our minimum thrust-line derived with vertical stereotomy are two distinguishable, physically admissible thrust-lines which do not coincide with R. Hooke’s catenary that meets the extrados of the arch at the three extreme points. Furthermore, the paper shows that the catenary (the “hanging chain”) is not a physically admissible minimum thrust-line of the semicircular arch, although it is a neighboring line to the aforementioned physically admissible thrust-lines. The minimum thickness of a semicircular arch that is needed to accommodate the catenary curve is t/R = 0.1117—a value that is even higher than the enhanced minimum thickness t/R = 0.1095 computed in this paper after adopting a cartesian coordinate system; therefore, it works toward the safety of the arch.     

Stokes Shift in Inorganic Lead Halide Perovskites: Current Status and Perspective

Inorganic metal halide perovskite system is considered as a promising candidate for applications from display to biomedical industry. Intrinsic inorganic lead halides possess small Stokes shift or self-absorption, providing negative impact for both photo voltaic and biomedical applications. Therefore, the development of an inorganic halide perovskite system with large Stokes shift is a significant venture. This review aims to provide an updated survey of the Stokes shift phenomena in the inorganic lead halide perovskites. The first section focuses about the mechanism, the second section gives different approaches in preparing inorganic perovskites with distinct Stokes shift, while the third section highlights the potential applications in both photovoltaic and biomedical areas. This review provides deep insight about the importance and usefulness of such phenomena in inorganic lead halides, essential for various applications.     

Sinkhole Attacks in Wireless Sensor Networks: A Survey

Wireless Personal Communications - Wireless sensor networks (WSNs) consist of a large number of nodes, communicating sensor readings to the base stations through other nodes. Due to their energy...     

Comparison of Li+‐ion conductivity in linear and crosslinked poly(ethylene oxide)

Polymer electrolytes are of tremendous importance for applications in modern lithium‐ion (Li⁺‐ion) batteries due to their satisfactory ion conductivity, low toxicity, reduced flammability, as well as good mechanical and thermal stability. In this study, the Li⁺‐ion conductivity of well‐defined poly(ethylene oxide) (PEO) networks synthesized via copper(I)‐catalyzed azide–alkyne cycloaddition is investigated by electrochemical impedance spectroscopy after addition of different lithium salts. The ion conductivity of the network electrolytes increases with increasing molar mass of the PEO chains between the junction points which is completely opposite to the behavior of their respective uncrosslinked linear precursors. Obviously, this effect is directly related to the segmental mobility of the PEO chains. Furthermore, the ion conductivity of the network electrolytes under investigation increases also with increasing size of the anion of the added lithium salt due to a weaker anti‐plasticizing effect of the more bulky anions. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 21–28