Design theory and experiment of acousto-optical tunable filter by use of flexural waves applied to thin optical fiber

Spectral response of acoustically induced microbending through thin optical fiber is discussed from mode-coupling of core and cladding modes. The thin fiber is analyzed in three-layered structure (core-cladding-air) to gain insights into acousto-optic modulation. We explained the dependence of core and/or cladding diameters on acoustic source parameters from numerical calculations. According to the calculations, we successfully fabricated all-optical tunable filter using this thin fiber that yields an efficient mode-coupling at flexural wave frequencies less than 1MHz. To increase the acousto-optic effect, we used a specially designed thin optical fiber (80 μm of cladding diameter) in the section where flexural wave is produced, and spliced both ends of the thin fiber to the tapered 125 μm fibers. The frequency and voltage tuning of fabricated filter is also confirmed by changing the driven frequency and applied voltage of the PZT, respectively. This result suggests a possibility of fiber-optic device application as all-optical tunable filter at 1.55 μm.     

Fe3O4@NCs/BF0.2: A magnetic bio‐based nanocatalyst for the synthesis of 2,3‐dihydro‐1H‐perimidines

Nanocellulose (NC) materials have some unique properties, which make them attractive as organic or inorganic supports for catalytic applications. Nanocatalysts with diameters of less than 100 nm are difficult to separate from the reaction mixture, therefore, magnetic nanoparticles (MNPs) were used as catalysts to overcome this problem. Fe₃O₄@NCs/BF_0.2 as a green, bio‐based, eco‐friendly, and recyclable catalyst was synthesized and characterized using fourier‐transform infrared spectroscopy (FT‐IR), vibrating sample magnetometer (VSM), X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA) techniques. Fe₃O₄@NCs/BF_0.2 was employed for the synthesis of 2,3‐dihydro‐1H‐perimidine derivatives via a reaction of 1,8‐diaminonaphthalene with various aldehydes at room temperature under solvent‐free conditions. The present procedure offers several advantages including a short reaction time, excellent yields, easy separation of catalyst, and environmental friendliness.     

A survey of interactions in crystal structures of pyrazine‐based compounds

The important role of pyrazine (pz) and its derivatives in fields such as biochemistry and pharmacology, as well as in the study of magnetic properties, is surveyed. Recognition of these properties without extensive investigations into their structural properties is not possible. This review summarizes interactions that exist between these organic compounds by themselves in the solid state, as well as those in coordination polymers with metal ions and in polyoxometalate‐based hybrids. Complexes based on pyrazine ligands can generate metal–organic framework (MOF) structures that bind polyoxometalates (POMs) through covalent and noncovalent interactions. Some biological and magnetic properties involving these compounds are considered and the effect of hydrogen bonding on their supramolecular architectures is highlighted.     

One-pot synthesis of 1-amidoalkyl-2-naphthols catalyzed by nano-BF3·SiO2

1-Amidoalkyl-2-naphthols were prepared via one-pot multi-component reaction of 2-naphthol, aldehydes, and amides in the presence of nano-silica supported boron trifluoride (nano-BF₃·SiO₂) in ethyl acetate at 80 °C. Short reaction times, high yields, scaleup and easy work-up are the advantages of this protocol.     

RKKY interaction in the zigzag-edge silicene-like nanoflake

By considering the Kane-Mele-Hubbard approximation on the honeycomb lattice, we investigate the spin-spin correlation for two magnetic impurities in zigzag edge silicene-like nanoflake (ZSiLF). The dependence of the spatial behaviors of RKKY interaction on the electron-electron (e-e), intrinsic spin-orbit interactions (ISOI) and, electric field are systematically investigated. Generally, the spatial behaviors of the RKKY interaction sensitively change by changing e-e interaction and electric field strengths in the presence of ISOI. The ISOI in a ZSiLF result in long-range in-plane and Ising interactions. Moreover, e-e interaction induces non-zero Dzyaloshinsky-Moriya (DM) term and nearly distance-independent Ising interaction (similar to graphene nanoflake) in the presence of ISOI. Furthermore, with considering e-e interaction, the in-plane DM interaction increases by increasing the strengths of the electric field and ISOI.     

The study of the weibel electromagnetic instability growth rate in the presence of the body stress

Body stress flow can be expected in the fast ignition imploding of the inertial fusion process that strongly damps small‐scale velocity structures. The Weibel instability is one of the plasma instabilities that require anisotropy in the distribution function. The body stress effect was neglected in the calculation of the Weibel instability growth rate. In this article, the propagation condition of impinging waves and the growing modes of the Weibel instability on the plasma density gradient of the fuel fusion with the body stress flow are investigated. Calculations show that the minimum value of the body stress rate threshold in the linear polarization is about 2.96 times greater than that of the circular polarization. Increasing 10 times of the density gradient and decreasing 2 times of the wavelength in the linear polarization and the circular polarization, respectively, lead to about 1.78 × 10⁶ times increment and 0.019 times decrement in the maximum of the Weibel instability growth rate. Also, the Weibel instability growth rate maximum in the circular polarization is about 10⁷ times greater than that of the linear polarization. The body stress flow and the density gradient tend to stabilize the Weibel instability in the circular polarization and act as a destabilizing source in the linear polarization. Therefore, by increasing steps of the density gradient plasma near the relativistic electron beam‐emitting region, in the circular polarization, the Weibel instability occurs at a higher stress flow.     

A combination of molecular docking,receptor-guided QSAR,and molecular dynamics simulation studies of S-trityl-l-cysteine analogues as kinesin Eg5 inhibitors

Structural Chemistry - Kinesin Eg5 plays an essential role in the early stages of mitosis, and it is an interesting drug target for the design of potent inhibitors. In this work, combined molecular...     

Lipid-DNA conjugates for cell membrane modification,analysis, and regulation

ABSTRACT

Lipids and DNAs are two major building blocks of life. Interestingly, by chemically linking these two natural compounds together, synthetic lipid-DNA conjugates exhibit several attractive features for cell membrane studies. These lipid-DNA conjugates are amphiphilic macromolecules combining the cell membrane insertion capability of lipids with the properties of DNAs in precise hybridization and programmability. These supramolecular conjugates have demonstrated exciting applications from generating cell membrane nanopores to transmembrane cargo deliveries, and from analyzing cell membrane events to tissue engineering. In this review, we will discuss the design, structures, and biological applications of lipid-DNA conjugates, with an emphasis on their functions on live cell membranes. We expect, in the near future, significant advancement in our ability to understand, control, and apply these cell membrane-modified lipid-DNA conjugates.     

A Review on Bioengineering Approaches to Insulin Delivery: A Pharmaceutical and Engineering Perspective

Diabetes mellitus (DM) is the most prevalent non‐contagious disease, which has affected a large number of people all over the world. Among all treatments known to have a positive influence in the control of DM, insulin therapy is the most common and effective one. Nowadays, various methods of insulin delivery are under investigation, which are able to reach a plausible bioavailability with ignorable side effects instead of insulin injection. This article presents a comprehensive review of the insulin therapy approach with a focus on modified methods in insulin delivery strategies and current advances in engineered insulin delivery systems.     

Dissipation of carbendazim and its metabolites in cucumber using liquid chromatography tandem mass spectrometry

Currently, there is growing interest in the degradation pathways of organic contaminants such as pesticides. In the case of pesticides, the determination of metabolites in agricultural products and environment is necessary as some of them could present similar toxicity to or even higher toxicity than the parent compound. The development of analytical methodology for the identification and quantification of carbendazim fungicide and its metabolites in cucumber was studied. Cucumber (cucumis sativus) is a global food in terms of economic importance and nutritional quality. Careful optimisation of the liquid chromatography–mass spectrometry (LC-MS)/MS parameters was achieved in order to attain a fast separation with the best sensitivity. The detection was carried out on an Ion-Trap tandem mass spectrometer (MS/MS) by electrospray ionisation in positive ion mode (ESI+) with multiple reaction monitoring (MRM).