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The possibility to design composites with superior properties by incorporation of nanoscale reinforcing material still remains to be fulfilled. In the current study, bisphenol A diglycidyl ether-based epoxy resin has been successfully modified with polyhedral oligomeric silsesquioxane (POSS) nanoparticles to give epoxy/POSS nanocomposites. Carbon fiber reinforced composites with different fiber orientations are processed via vacuum bagging technique using this composite as the matrix. Scanning electron microscopy indicated that POSS nanofillers homogeneously distributed in the matrix. As proved by the tensile, flexural, and interlaminar shear strength tests, the inclusion of POSS nanofillers in the polymer matrix has promoted significant improvements in the mechanical properties of the carbon fiber reinforced POSS/epoxy hybrid composites compared to the analogues with neat epoxy matrix. Thus, hybrid composites with exceptional properties are obtained via a straightforward modification in the matrix and a novel paradigm without using any expensive compound has been added to the library of nanocomposite formulations.

We investigate the impact of the magnitude of current sales changes on asymmetric cost behavior. We expect that managers are likely to consider small (large) current sales decreases as temporary (permanent). Therefore, they will be less (more) likely to cut costs for small (large) current sales decreases. Accordingly, we predict and find that, conditional on a prior sales increase, cost stickiness is greater for small current sales changes than for large current sales changes. In addition, prior research suggests that, conditional on a prior sales decrease, slack resources retained from the prior period might lead to cost anti-stickiness. We expect that slack resources retained from the prior period will have a greater (smaller) impact on cost behavior for small (large) current sales changes. Accordingly, we predict and find that, conditional on a prior sales decrease, cost anti-stickiness is greater for small current sales changes than for large current sales changes. JEL Classifications: M41; M46; G12.

A new polymerization mechanistic transformation strategy, combining two different controlled polymerization techniques of different modes, atom transfer radical polymerization (ATRP) and photoinduced radical oxidation/addition/deactivation (PROAD), is successfully applied for the synthesis of block copolymers. Thus, mono- or bi- bromide functional polystyrenes (PS-Br or Br-PS-Br) synthesized by light induced ATRP were used as macroinitiator for the living cationic polymerization of isobutyl vinyl ether via PROAD process to give the corresponding block copolymers. In this way, depending on the structure of the macroinitiator, AB or ABA type block copolymers (PS-b-PIBVE or PIBVE-b-PS-b-PIBVE) were formed. The final polymers and precursor polymers were characterized by spectral and chromatographic analyses.

In the present study, homogeneous mixtures of halloysite nanotubes (HNTs)-epoxy nanocomposites are prepared through chemical treatments. Naturally present halloysite nanotubes (HNT) are primarily modified by 3-(glycidyloxypropyl)trimethoxysilane and subsequently utilized as nanofillers in a mixture of bisphenol A diglycidyl ether and trimethylolpropane triglycidyl ether by varying weight % of modified HNT from 0 to 8%. Photoinitiated cationic crosslinking polymerization of this mixture facilitates the in-situ preparation of HNT/thermoset nanocomposites at room temperature. The covalent attachment of HNT in the thermoset matrix has been confirmed by monitoring the characteristic signals of the mixture, nanofiller, neat thermoset, and final nanocomposite using fourier transformed infrared (FT-IR) spectroscopy. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses proved the existence and distribution of HNT in the thermoset nanocomposites. Indeed, a combination of agglomerated/non-agglomerated HNTs in the thermoset matrix is also determined. On the other hand, mechanical properties of nanocomposites are significantly improved with increase in HNT loading up to 4% ratio. Adding 4% of modified HNT into epoxy increased its tensile strength and elasticity modulus by 6.9 times and 2.3 times than the corresponding neat epoxy thermoset, respectively, without scarifying thermal stability. Therefore, the HNT/epoxy thermoset nanocomposites are suitable candidates for various applications as an alternative of expensive carbon nanotube containing analogues.

We investigate the relationship between cost stickiness and management earnings forecasts. Prior research suggests that earnings are more volatile for sticky cost firms resulting in greater earnings forecast errors. The greater forecast errors might increase investors' demand for information and induce managers to issue earnings forecasts. Alternatively, managers might refrain from issuing earnings forecasts for sticky cost firms because greater forecast errors might damage managers' credibility and adversely affect their job security. We find that cost stickiness is positively associated with management earnings forecast issuance, suggesting that the benefits outweigh the costs. Prior research also suggests that cost stickiness has negative implications for earnings. We find a positive association between cost stickiness and management earnings forecast errors, suggesting that managers do not fully incorporate the negative implications of cost stickiness into their forecasts. Finally, we find that analysts' forecast errors for sticky cost firms are greater than managers'. JEL Classifications: M41; M46; G12.

Current food date marking tools fail to take into account variables that impact shelf life, leading to food waste and posing human health risks. Herein, we develop a polydiacetylene/zinc oxide (PDA/ZnO) colorimetric sensor that can indicate milk freshness in real time. The PDA/ZnO system is engineered to indicate the freshness of full cream milk by monitoring its pH based on lactic acid concentration, an indicator of bacterial spoilage. The sensitivity is tuned by selection of the diacetylene monomers from which it is composed. Designs constructed from shorter chain diacetylenes are found to undergo chromatic transitions at a lower lactic acid concentration. Two new methods to tune PDA/ZnO sensitivity to lactic acid are explored, including relocation of the diacetylene functional group and lipid doping. A system constructed from 5,7-hexadecadiynoic acid (HDDA) and ZnO can discriminate between fresh (pH 6.8-6.0), spoiling (pH 6.0-4.5), and spoiled milk (pH 4.5-4.0) by a respective blue to purple to red color change. The chromatic stability of the PDA/ZnO sensor in food is studied as previous reports have shown the system to be unstable. We present a new method that stabilizes the nanocomposite by pre-exposure to the food matrix prior to photopolymerization.

Synthesis of amphiphilic polysulfone graft copolymers by ‘‘Click’’ chemistry is described. First, a commercial PSU was chloromethylated to give chloro-funtional PSU (PSU-Cl). Subsequently, chloride groups were converted into azide moieties by nucleophilic substitution. Hydrophilic poly(N,Ndimethylacrylamide) (PDMA) side chains were then attached via a “grafting to” approach by using coppercatalyzed azide–alkyne cycloaddition (CuAAC). Precursor polymer and the final amphiphilic copolymers were characterized by proton nuclear magnetic resonance ( 1H NMR), fourier-transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC) and contact angle measurements.

Linear poly(hydroxyethyl methacrylate-co-methyl methacrylate) P(HEMA-co-MMA) and poly(dimehylaminoethyl methacrylate-co-methyl methacrylate) P(DMAEMA-co-MMA) and their corresponding hyperbranched copolymers were synthesized by conventional photoinitiated free radical polymerization and self-condensing vinyl polymerization (SCVP) using Type I and Type II photoinitiators, respectively. Then, the polymers were processed by electrospraying in N, N-dimethylformamide. The surface of the resulting electrospray coatings was examined by SEM, XPS, and WCA then compared with those prepared by drop casting. Regardless of the structural nature of the polymers, electrospraying allows the preparation of rough surface that shows more hydrophobic behavior. Electrospray coatings with linear and hyperbranched copolymers exhibited WCA as ∼150° and ∼130°, respectively, indicating that branching reduces the WCA., Istanbul Technical University; Scientific and Technological Research Council of Turkey (TUBITAK)

A novel polymerization mechanism transformation strategy, combining ring-opening metathesis polymerization (ROMP) and visible light induced cationic polymerization, is successfully applied for the synthesis of polyethylene-graft-poly(cyclohexene oxide) (PE-g-PCHO). First, cis-cyclooctene (COE) was polymerized via ROMP in the presence of a chain transfer agent and quantitatively hydrobrominated to give bromo functional polyethylene (PE-Br). Subsequent irradiation of PE-Br in the visible range using dimanganese decacarbonyl (Mn-2(CO)(10)) and diphenyl iodonium hexafluorophosphate (Ph2I+PF6) as radical generator and oxidant, respectively, initiated cationic polymerization of cyclohexene oxide (CHO) resulting in the formation of PE-g-PCHO. The effect of irradiation time and Mn-2(CO)(10) concentration on the grafting density and efficiency was evaluated. Both the precursor polymers and the corresponding graft copolymers were characterized by H-1 NMR and Fourier transform infrared (FT-IR) spectroscopy, gel-permeation chromatography (GPC), and differential scanning calorimetric (DSC) analyses.

Recent work in management accounting offers several novel insights into firms' cost behavior. This study explores whether financial analysts appropriately incorporate information on two types of cost behavior in predicting earnings—cost variability and cost stickiness. Since analysts' utilization of information is not directly observable, we model the process of earnings prediction to generate empirically testable hypotheses. The results indicate that analysts “converge to the average” in recognizing both cost variability and cost stickiness, resulting in substantial and systematic earnings forecast errors. Particularly, we find a clear pattern—inappropriate incorporation of available information on cost behavior in earnings forecasts leads to larger errors in unfavorable scenarios than in favorable ones. Overall, enhancing analysts' awareness of the expense side is likely to improve their earnings forecasts, mainly when sales turn to the worse. JEL Classifications: M41; M46; G12.

In the present study, two amphiphilic star-hyperbranched copolymers based on poly(methyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PMMA-b-PHEMA), with different hydrophilic PHEMA segment contents (PMMA-b-PHEMA-1, and PMMA-b-PHEMA-2), were synthesized, and their drug loading and release profiles were examined using Paclitaxel (PTX) as a model drug. The drug loading capacities and encapsulation efficiencies were found to be similar in both polymers. The encapsulation efficiencies were found to be prominent at 98% and 98.5% for PMMA-b-PHEMA-1 and PMMA-b-PHEMA-2, respectively. On the other hand, the drug release behaviors varied in favor of the block copolymer comprising shorter PHEMA chains (PMMA-b-PHEMA-1). Additionally, to assess the biological effects of PTX-loaded polymers, human non-small cell lung carcinoma (A549) cells were used. Cell viability and cell cycle analysis showed that both polymers were non-toxic to cells. The cytotoxic effect of PTX-loaded PMMA-b-PHEMA-1 on A 549 cells was greater (66.49% cell viability at 5.0 ng mL(-1) PTX) than that of PMMA-b-PHEMA-2 (72.47% cell viability at 5.0 ng mL(-1) PTX), consistent with the drug release experiments.

A simple approach for the preparation of a clickable poly(ethylene glycol)-based hydrogel as a polymeric support for protein immobilization via photoinitiated free radical polymerization of poly(ethylene glycol) diacrylate and propargyl acrylate is established. Bioconjugation to the obtained gels was achieved by azide–alkyne click reaction with azido-functionalized anti-immunoglobulin G (anti-IgG) and anti-His tag antibodies. Evaluation of the affinities of the PEG hydrogels to the corresponding substrates (IgG and His-tagged YFP, respectively) indicates their specific binding capability.

A facile synthesis method for the preparation of clickable hydrogels and linear polymers is described. The strategy pertains to the photochemical generation of initiating radicals by hydrogen abstraction of excited camphorquinone from acetylenic alcohol followed by free radical polymerization. For hydrogels, poly(ethylene glycol) methyl ether methacrylate and poly(ethylene glycol) diacrylate were used in the system as monomer and crosslinker, respectively. Fluorescent pyrene groups were anchored onto the hydrogels through copper-catalyzed Huisgen 1,3-dipolar azide/alkyne click reaction by using 2-azidomethyl pyrene as evidenced by Fourier transform infrared and fluorescence spectroscopy. The applicability of the method for macromolecular synthesis is also demonstrated. For this purpose, poly(methyl methacrylate) with alkyne terminal groups was prepared by photoinitiated free radical polymerization of methyl methacrylate using camphorquinone and 3-(trimethylsilyl)propargyl alcohol as sensitizer and hydrogen donor, respectively. After deprotection, the click reaction with azido polystyrene obtained by atom transfer radical polymerization followed by azidation resulted in the formation of polystyrene-b-poly(methyl methacrylate). The intermediates at various stages and the final block copolymer were characterized by spectral analysis and gel permeation chromatography. © 2014 Society of Chemical Industry

Recent achievements and future opportunities for the design of 2D, 3D, and 4D materials using photochemical reactions are summarized. Light is an attractive stimulus for material design due to its outstanding spatiotemporal control, and its ability to mediate rapid polymerization under moderate reaction temperatures. These features have been significantly enhanced by major advances in light generation/manipulation with light-emitting diodes and optical fiber technologies which now allows for a broad range of cost-effective fabrication protocols. This combination is driving the preparation of sophisticated 2D, 3D, and 4D materials at the nano-, micro-, and macrosize scales. Looking ahead, future challenges and opportunities that will significantly impact the field and help shape the future of light as a versatile and tunable design tool are highlighted.

Recent research documents the empirical phenomenon of “sticky costs” and attributes it to a theory of deliberate managerial decisions in the presence of adjustment costs. We refine this theoretical explanation and show that it gives rise to a more complex pattern of asymmetric cost behavior that combines two opposing processes: cost stickiness conditional on a prior sales increase, and cost anti-stickiness conditional on a prior sales decrease. These predictions reflect the structure of optimal decisions with adjustment costs and the impact of prior sales changes on managers' expectations about future sales changes. Empirical estimates for Compustat data support our hypotheses. We further verify our predictions using additional proxies for managers' expectations, and show that our model offers important new insights. JEL Classifications: D24; M41.

The recently developed photoinitiated atom transfer radical polymerization has been implemented in the inverse microemulsion polymerization of oligo(ethylene glycol) monomethyl ether methacrylate. Two different mechanisms including a simultaneous reverse and normal initiated ATRP and a combination of activators generated by electron transfer and initiators for continuous activator regeneration ATRP are investigated under UV light. The effects of various reaction parameters on the resulting particles have been systematically investigated, and it has been demonstrated that the particle size can be tuned based on UV light, initial stoichiometry, and aqueous phase fraction. The formed particles contained well-defined water-soluble polymers with relatively narrow molecular weight distribution (M-w/M-n < 1.4).

This paper investigates whether future excess returns to R&D-intensive firms documented in prior literature is due to mispricing or compensation for additional risk. Prior research provides evidence consistent with the explanation that the positive association is compensation for additional risk associated with R&D (Chambers et al. 2002). I investigate another possibility: The future excess returns to R&D are correction for undervaluation in the prior periods. I first investigate financial analysts’ behavior about future benefits of R&D-intensive firms because financial analysts are one of the most important information intermediaries between investors and managers. Moreover, investor dependence on analyst information is greater in R&D-intensive firms (Barth et al., 2001). I find that analysts underestimate earnings long term growth in R&D-intensive firms and correct their underestimation in following years. I also find that investors are not aware of analysts’ underestimation of future benefits of R&D suggesting that investors are mislead by analysts long term forecasts.

A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin alpha(v)beta(3) receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin alpha(v)beta(3) receptor expressing tumor cells.