Hydrogen-bonded multilayer thin films and capsules based on poly(2-n-propyl-2-oxazoline) and tannic acid : investigation on intermolecular forces, stability, and permeability

In recent years, hydrogen-bonded multilayer thin films and capsules based on neutral and nontoxic building blocks have been receiving interest for the design of stimuli-responsive drug delivery systems and for the preparation of thin-film coatings. Capsule systems made of tannic acid (TA), a natural polyphenol, as a hydrogen bonding donor and poly(2-n-propyl-2-oxazoline) (PnPropOx), a polymer with lower critical solution temperature around 25 degrees C, as a hydrogen bonding acceptor are advantageous over other conventional hydrogen-bonded systems because of their high stability in physiological pH range, biocomparibility, good renal clearance, stealth behavior, and stimuli responsiveness for temperature and pH. In this work, investigations on the interactive forces in TA/PnPropOx capsule formation, film thickness, stability, and permeability are reported. The multilayer thin films were assembled on quartz substrates, and the layer-by-layer film growth was investigated by UV-vis spectroscopy, atomic force microscopy, and profilometry. Hollow capsules were fabricated by sequential coating of TA and PnPropOx onto CaCO3 colloidal particles, followed by template dissolution with a 0.2 M ethylenediaminetetraacetic acid solution. The obtained capsules and multilayer thin films were found to be stable over a wide pH range of 2-9. It is found that both hydrogen bonding and hydrophobic interactions are responsible for the enhanced stability of the capsules at higher pH range. Swelling followed by dissolution of the capsules was observed at a pH value lower than 2, while the capsules undergo shrinking at a pH value higher than 8 and finally transform into a particle-like morphology before dissolution. The TA/PnPropOx capsules reported here could be used as a temperature-responsive drug delivery system in controlled drug delivery applications

Counting molecules with a mobile phone camera using plasmonic enhancement

Cataloged from PDF version of article.Plasmonic field enhancement enables the acquisition of Raman spectra at a single molecule level. Here we investigate the detection of surface enhanced Raman signal using the unmodified image sensor of a smart phone, integrated onto a confocal Raman system. The sensitivity of a contemporary smart phone camera is compared to a photomultiplier and a cooled charge-coupled device. The camera displays a remarkably high sensitivity, enabling the observation of the weak unenhanced Raman scattering signal from a silicon surface, as well as from liquids, such as ethanol. Using high performance wide area plasmonic substrates that enhance the Raman signal 10(6) to 10(7) times, blink events typically associated with single molecule motion, are observed on the smart phone camera. Raman spectra can also be collected on the smart phone by converting the camera into a low resolution spectrometer with the inclusion of a collimator and a dispersive optical element in front of the camera. In this way, spectral content of the blink events can be observed on the plasmonic substrate, in real time, at 30 frames per second

The grass is greener on the other side: Comparison of green versus brown corporate bonds

This study compares the yield-to-maturities on green versus brown corporate bonds on their issue dates, after controlling for the market, firm, bond, and currency characteristics of the bonds. Our analyses show that if these characteristics are not addressed, it is possible to find support for the existence of a “greenium” at a magnitude of about 25 basis points. However, when all yield factors are included in the models, the results change and indicate that issuers do not necessarily enjoy any cost advantage when they issue green bonds, instead of brown bonds. Failure to consider these interactions might lead to biased findings

The agency cost of investing in ethical funds: A style analysis approach

This study aims to determine whether ethical funds make portfolio choices in line with their investment mandates. Our results show that during the first half of the sample period, it is much more difficult to distinguish the investment styles of ethical and conventional funds. The potential for ethical fund investors to face agency conflicts from investing in portfolios that are not necessarily in line with their preferences based on environmental, social, and governance (ESG) criteria is higher in the earlier years. In the second half of the sample period, ethical funds appear to invest more in large stocks that have higher ESG ratings than their conventional counterparts. Even though both fund classes have decreased their allocation to ESG-based investment alternatives in recent years, they seem to have slightly more distinct investment styles

Impact of La³⁺ and Y³⁺ ion substitutions on structural, magnetic and microwave properties of Ni<inf>0.3</inf>Cu<inf>0.3</inf>Zn<inf>0.4</inf>Fe<inf>2</inf>O<inf>4</inf> nanospinel ferrites synthesized: Via sonochemical route

In the current study, Ni0.4Cu0.2Zn0.4LaxYxFe2-xO4 (x = 0.00 - 0.10) nanospinel ferrites (NSFs) were fabricated via an ultrasonic irradiation route. The creation of single phase of spinel nanoferrites (NSFs) was investigated by X-ray powder diffractometry (XRD) and selected area diffraction pattern (SAED). The cubic morphology of all samples was confirmed by scanning and transmission electron microscopies (SEM and TEM) respectively. The UV-Vis investigations provided the direct optical energy band gap values in a narrow photon energy interval of 1.87-1.92 eV. The 57Fe Mössbauer spectroscopy analysis explained that the hyperfine magnetic fields of Octahedral (Oh) and Tetrahedral (Td) sites decreased with substitution. The paramagnetic properties of NPs decrease with increase of content of doped ions. Investigations of magnetic properties reveal a superparamagnetic nature at 300 K and soft ferromagnetic trait at 10 K. The Ms (saturation magnetization) and Mr (remanence) decrease and the Hc (coercivity) increases slightly with La3+ and Y3+ substitution. The observed magnetic traits are deeply discussed in relation with the morphology, structure, magnetic moments and cation distributions. The microwave characterization of the prepared NSFs showed that, dissipation (i.e., absorption) of incoming microwave energy occurs at a single frequency, for each sample, lying between 7 and 10.5 GHz. The reflection losses (RL) at these frequencies range from -30 to -40 dB and the mechanism of which is explained in the framework of dipolar relaxation and spin rotation. The best microwave properties were obtained with a LaY concentration of x = 0.08 having an RL of -40 dB @ 10.5 GHz and an absorption bandwidth of 8.4 GHz @ -10 dB. With these high values of RL and absorbing bandwidth, LaY doped NiCuZn NSF products would be promising candidates for radar absorbing materials in the X-band

Impact of Sm³⁺ and Er³⁺ Cations on the Structural, Optical, and Magnetic Traits of Spinel Cobalt Ferrite Nanoparticles: Comparison Investigation

In this study, we investigated a comparison of the structure, morphology, optic, and magnetic (room temperature (RT)) features of Er3+ and Sm3+ codoped CoFe2O4 (CoErSm) nanospinel ferrite (NSFs) (x ≤ 0.05) synthesized via hydrothermal (H-CoErSm NSFs) and sonochemical (S-CoErSm NSFs) approaches. The formation of all products via both synthesis methods has been validated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), along with energy-dispersive X-ray (EDX) and transmission electron microscopy (TEM) techniques. The single phase of the spinel structure (except for the Hyd sample with x = 0.03) was evidenced by XRD analysis. The DXRD (crystallite size) values of H-CoErSm and S-CoErSm NSFs are in the 10-14.7 and 10-16 nm ranges, respectively. TEM analysis presented the cubic morphology of all products. A UV-visible percent diffuse reflectance (DR %) study was performed on all products, and Eg (direct optical energy band gap) values varying in the 1.32-1.48 eV range were projected from the Tauc plots. The data of RT magnetization demonstrated that all prepared samples are ferromagnetic in nature. M-H data revealed that rising the contents of cosubstituent elements (Sm3+ and Er3+ ions) caused an increase in Ms (saturation magnetization) and Hc (coercive field) in comparison to pristine samples. Although concentration dependence is significant (x > 0.02), no strict regularity (roughly fluctuating) has been ruled out in Ms values for doped samples prepared via the hydrothermal method. However, sonochemically prepared samples demonstrated that Ms values increase with increasing x up to x = 0.04 and then decrease with the further rise in cosubstituent Sm3+ and Er3+ ions. The calculated values of Ms and Hc were found to be greater in H-CoErSm NSFs compared to those in S-CoErSm NSFs. The present investigation established that the distribution of cations and the variation in crystallite/particle sizes are efficient to control the intrinsic properties of all samples

On beta-time fractional biological population model with abundant solitary wave structures

Abstract The ongoing study deals with various forms of solutions for the biological population model with a novel beta-time derivative operators. This model is very conducive to explain the enlargement of viruses, parasites and diseases. This configuration of the aforesaid classical scheme is scouted for its new solutions especially in soliton shape via two of the well known analytical strategies, namely: the extended Sinh-Gordon equation expansion method (EShGEEM) and the Expa function method. These soliton solutions suggest that these methods have widened the scope for generating solitary waves and other solutions of fractional differential equations. Different types of soliton solutions will be gained such as dark, bright and singular solitons solutions with certain conditions. Furthermore, the obtained results can also be used in describing the biological population model in some better way. The numerical solution for the model is obtained using the finite difference method. The numerical simulations of some selected results are also given through their physical explanations. To the best of our knowledge, No previous literature discussed this model through the application of the EShGEEM and the Expa function method and supported their new obtained results by numerical analysis

Ajuga postii Briq ve Ajuga relicta P.H.Davis üzerine morfolojik-anatomik bir araştırma

Yapılan çalışma ile Türkiye'de lokal endemik türler olan Ajuga postii ve Ajuga relicta (Lamiaceae)'nın morfolojik ve anatomik özellikleri belirlenmiştir. Buna göre A. postii'nin korollası koyu pembe-mor (kuruyunca morumsu) renkli, üst dudak eksilmiş veya kaybolmuş; A. relicta'nın korollası krem rengi kuruduğunda ise sarımsı-bej rengi, üst dudak 1 mm, tabanda iki dişlidir. Anatomik özellikler çalışılan örneklerin kök, gövde ve yaprak anatomik kesitleri üzerinden verilmiştir. A. relicta'nın gövdesi üzerinde herhangi bir tüy oluşumu görülmezken, A. postii'nin gövdesi üzerinde seyrek olarak örtü tüyleri gözlenmiştir. Çalışılan taksonların kök anatomik kesitlerinde sklerenkima hücreleri korteks tabakasında belirgindir. Yaprak enine kesitlerde salgı tüyleri gözlenmezken, örtü tüyleri gözlenmiştirIn the present study morphological and anatomical features of Ajuga postii and Ajuga relicta (Lamiaceae) which are local endemic for Turkey have been carried out. Corolla of A. postii is dark purple-pink (drying purplish) and upper lip obsolescent or lost; corolla of A. relicta is cream colored when dried yellowish-beige and upper lip 1 mm, bidentate to the base. Anatomical verities have been represented in cross sections of roots, stems, and leaves of the species. A. relicta has been observed without trichomes and A. postii with sparsely non-glandular trichomes on the stems. In root cross sections of the species, sclerenchyma cells have been observed in the cortexes. In the leaf crosssections, glandular trichomes have not been observed, only non-glandular trichomes have been determine

Investment delegation of private foundations

We study how private foundations manage their investments. Using a novel dataset, we show that foundations with financial experts are less likely to delegate their investment to outside portfolio managers whereas an internal investment o cer hire is associated with more frequent use of external investment advisers. However, directors with financial expertise do not substantially alter asset allocation compared with non-outsourcing foundations. In addition, our analysis reveals a local bias in the investment adviser choice by foundations. The local bias is weakened when a foundation has financial experts on their board. Our results suggest that financial expertise improves at least the operational process of investment