Influence of the water molecules (n?=?1–6) on the interaction between Li+, Na+, K+ cations and indole molecule as tryptophan amino acid residue

Influence of the addition of water molecules (n = 1–6) on the interaction energy between Li⁺, Na⁺, K⁺ cations and indole molecule as tryptophan amino acid residue is considered at MP2(FULL)/6-311++G(d,p)//B3LYP/6-311++G(d,p) levels of theory. The calculations suggest that the size of cation and the number of water molecules are two important factors that affect the interaction energy between the hydrated metal cation and indole molecule. The strength of cation–π interactions get substantially reduced when the metal ion is solvated or the size of metal cation increases. Quantum theory of atoms in molecules analysis of cation–π interaction indicates that there is a correlation between the electron density (ρ(r)) in the cage critical points generated upon complexation and the distance between metal cation and centroid of phenyl ring in indole molecule.     

Tetrabutylammonium bromide media aza-Michael addition of 1,2,3,6-tetrahydrophthalimide to symmetrical fumaric esters and acrylic esters under solvent-free conditions

The aza-Michael addition of 1,2,3,6-tetrahydrophthalimide with symmetrical fumaric esters has been performed efficiently in a solvent-free system at 100 °C and using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a base in the presence of tetrabutylammonium bromide (TBAB). The products were obtained in good to high yields within 2.5-7.0 h. This reaction worked well on linear alkyl fumarates and was not effective with nonlinear alkyl fumarates. Although the reaction was also applicable to acrylates such as n-butyl acrylate, methacrylates and crotonates were not suitable Michael acceptors for this reaction.     

Effects of silicon nanowires length on solar cells photovoltaic properties

Silicon nanowires (SiNWs) were produced by an electroless method on FZ-Si (100) wafer, in HF/AgNO₃ solution. The influence of etching time and temperature on SiNWs morphology were studied using FESEM images. Optical properties were also investigated by optical absorption spectroscopy and low-temperature photoluminescence at 4.2?K. Considering their role as active regions, photovoltaic properties of SiNWs solar cells were studied for their different lengths. Photovoltaic measurements were taken in 1 sun condition under AM 1.5 illumination supplied by a solar simulator. Measurements indicated a reduction in efficiency as SiNWs length increased, which might be attributed to increased dangling states on nanowires surfaces.     

Influence of population and radius of cavity bubbles on size of sodium chloride crystals in ultrasound ablation

Crystal size distribution as a function of power in ultrasound ablation is simulated by using a theoretical method based on population and radius of bubbles. In this method, population and radius of bubbles are related to ultrasound power and Debye temperature of crystals. The best power for production of crystals with uniform size is obtained from the theory. In addition, it is shown that the population of bubbles effects the radius of the productions and the radius of bubbles influences the population of products. Results from the theory are supported by experimental results.     

Static and dynamic stability modeling of a capacitive FGM micro-beam in presence of temperature changes

Stability of a functionally graded (FG) micro-beam, based on modified couple stress theory (MCST), subjected to nonlinear electrostatic pressure and thermal changes regarding convection and radiation, is the main purpose of this paper. It is assumed that the functionally graded beam, made of metal and ceramic, follows the volume fraction definition and law of mixtures, and its properties change as an exponential function through its thickness. By changing the ceramic constituent percent of the bottom surface, five different types of the micro-beams are investigated. The static pull-in voltages in presence of temperature changes are obtained by using step-by-step linearization method (SSLM) and, by adapting Runge–Kutta approach, the dynamic pull-in voltages are obtained numerically. Though the temperature distribution through the thickness of FG micro-beam (due to its too small measurement) is considered uniform, owing to the different thermal expansions of layers, temperature changes cause deflection in the micro-beam, and consequently affect pull-in values. Hence the profound effects of different material constituent over the pull-in voltages are illustrated and it is graphically displayed that how in some cases neglecting components of the couple stress leads to inaccurate results.     

Efficient Synthesis and Antibacterial Activities of Some Novel 1,2,3‐Triazoles Prepared from Propargylic Alcohols and Benzyl Azides

A simple and effective procedure for regioselective preparation of 1,2,3‐triazoles from benzyl azides and propargylic alcohols is described using CuSO₄.5H₂O and sodium ascorbate. To screen the antibacterial activity of some newly synthesized triazole derivatives, minimum inhibitory concentration of 3d and 3k was evaluated against gram positive Staphylococcus aureus and Bacillus subtilis and gram negative Escherichia coli and Pseudomonas aeruginosa.     

A General Strategy for Site‐Directed Enzyme Immobilization by Using NiO Nanoparticle Decorated Mesoporous Silica

Mesoporous materials have recently gained much attention owing to their large surface area, narrow pore size distribution, and superior pore structure. These materials have been demonstrated as excellent solid supports for immobilization of a variety of proteins and enzymes for their potential applications as biocatalysts in the chemical and pharmaceutical industries. However, the lack of efficient and reproducible methods for immobilization has limited the activity and recyclability of these biocatalysts. Furthermore, the biocatalysts are usually not robust owing to their rapid denaturation in bulk solvents. To solve these problems, we designed a novel hybrid material system, mesoporous silica immobilized with NiO nanoparticles (SBA‐NiO), wherein enzyme immobilization is directed to specific sites on the pore surface of the material. This yielded the biocatalytic species with higher activity than free enzyme in solution. These biocatalytic species are recyclable with minimal loss of activity after several cycles, demonstrating an advantage over free enzymes.     

Monolithic molecularly imprinted cryogel for lysozyme recognition

The application of molecularly imprinted polymers in the selective adsorption of macromolecules such as proteins by monolithic protein‐imprinted columns requires a macroporous structure, which can be provided by cryogelation at low temperature in which the formation of ice crystals gives a porous structure to the molecularly imprinted polymer. In this study, we applied this technique to synthesize lysozyme‐imprinted polyacrylamide cryogels containing 8% w/v of total monomers and 0.3% w/v of lysozyme. The synthesized cryogel was sponge‐like and elastic with very fast swelling and reshaping properties, showing a swelling ratio of 24.5 ± 3 and gel fraction yield of about 72%. It showed an imprinting effect of 1.58 and a separation factor of 1.37 for cytochrome c as the competing protein. Adsorption studies on the cryogel revealed that it follows the Langmuir isotherm, with a maximum theoretical adsorption capacity of 36.3 mg lysozyme per gram of cryogel. Additionally, it was shown that a salt‐free rebinding solution at low flow rate and pH = 7.0 is favorable for lysozyme rebinding. This kind of monolithic column promises a wide range of application in separation of various biomolecules due to its preparation simplicity, good rebinding characteristics, and macroporosity.     

Design Strategies and Applications of Tissue Bioadhesives

In the past two decades tissue adhesives and sealants have revolutionized bleeding control and wound healing. This paper focuses on existing tissue adhesive design, their structure, functioning mechanism, and their pros and cons in wound management. It also includes the latest advances in the development of new tissue adhesives as well as the emerging applications in regenerative medicine. We expect that this paper will provide insightful discussion on tissue bioadhesive design and lead to innovations for the development of the next generation of tissue bioadhesives and their related biomedical applications.

     

Production, nano-purification, radiolabeling and biodistribution study of [140Nd] 5,10,15,20-tetraphenylporphyrin complex as a possible imaging agent

[¹⁴⁰Nd] labeled 5,10,15,20-tetraphenylporphyrin ([¹⁴⁰Nd]-TPP) as a tumor–avid complex with a β-emitting radionuclide for evaluating its potential for target tumor therapy is reported. This complex was prepared using freshly prepared [¹⁴⁰Nd] NdCl₃ (purified by amino functionalized MCM-41 nano resin and commercial cation exchanger resins) and 5,10,15,20-tetraphenylporphyrin (H₂TPP).Stability of the complex was investigated in final formulation and human serum for 24 h and the partition coefficient was calculated. The biodistribution of the labeled compound in vital organs of Swiss mice bearing fibro sarcoma tumor was studied using scarification studies and positron emission tomography imaging up to 4 h.