Novel biodegradable ester-based polymer blends

We have found, within the polyester family, interesting and potentially useful patterns of three-component compatibility. The bacterially produced biodegradable polyester, poly(hydroxybutyrate) (PHB) and its copolymers with hydroxyvalerate (HV) together with polymers such as cellulose acetate butyrate (CAB), polycaprolactone, poly(lactic acid), and a series of high-molecular-weight, non-crystallizable ester-based plasticisers have been identified as possible candidates in the production of blends in which aspects of performance can be varied with a degree of independence of cost. The compatibility ranges can be conveniently represented in the form of triangular graphs, with the relative weight fraction, or percentage, being represented along each of the three axes. The extent to which the modulation of the physical properties in general, but the stability in various environments in particular, is possible by the formation of three-component blends, such as those formed between P(HB-HV), cellulose acetate butyrate and poly(alkylene adipate) plasticisers, is discussed.     

Biocompatibility Study of Curcumin-Loaded Pluronic F127 Nanoformulation (NanoCUR) against the Embryonic Development of Zebrafish (Danio rerio)

Curcumin (CUR) has been studied for its biomedical applications due to its active biological properties. However, CUR has limitations such as poor solubility, low bioavailability, and rapid degradation. Thus, CUR was nanoformulated with the application of polymeric micelle. Previous studies of CUR-loaded Pluronic F127 nanoformulation (NanoCUR) were generally prioritized toward cancer cells and its therapeutic values. There are reports that emphasize the toxicity of CUR, but reports on the toxicity of NanoCUR on embryonic developmental stages is still scarce. The present study aims to investigate the toxicity effects of NanoCUR on the embryonic development of zebrafish (Danio rerio). NanoCUR was synthesized via thin film hydration method and then characterized using DLS, UV-Vis, FTIR, FESEM, and XRD. The toxicity assessment of NanoCUR was conducted using zebrafish embryos, in comparison to native CUR, as well as Pluronic F127 (PF) as the controls, and ROS assay was further carried out. It was revealed that NanoCUR showed an improved toxicity profile compared to native CUR. NanoCUR displayed a delayed toxicity response and showed a concentration- and time-dependent toxicity response. NanoCUR was also observed to generate a significantly low reactive oxygen species (ROS) compared to native CUR in ROS assay. Overall, the results obtained highlight the potential of NanoCUR to be developed in clinical settings due to its improved toxicity profile compared to CUR.     

Group classification and exact solutions of a higher-order Boussinesq equation

Nonlinear Dynamics - We consider a family of sixth-order Boussinesq equations in one space dimension with an arbitrary nonlinearity. The equation was originally derived for a one-dimensional...     

Direct synthesis of tetrazine functionalities on polymer backbones

Tetrazine mediated inverse Electron Demand Diels–Alder Reaction (IEDDA) is an important modification technique due to its high selectivity and super‐fast kinetics. Incorporation of tetrazine moieties on polymer chains requires multistep synthetic pathways and a post‐polymerization step leading to functional polymeric materials. Such approaches involve separate syntheses of polymer and the molecule which will be employed in modification. Herein, we introduce a straightforward synthetic approach for direct synthesis of tetrazine groups on polymers as side chains. As model systems, tetrazine functional poly(N‐isopropylacrylamide)‐and poly(ethylene glycol)‐based polymers from corresponding precursor polymers with nitrile moieties as pendant groups are prepared and IEDDA Click Reaction is achieved with trans‐cyclooctene derivatives. The click reaction is monitored by both NMR and UV–vis spectroscopies. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 673–680     

Determination and interference studies of bismuth by tungsten trap hydride generation atomic absorption spectrometry

The determination of bismuth requires sufficiently sensitive procedures for detection at the μg L⁻¹ level or lower. W-coil was used for on-line trapping of volatile bismuth species using HGAAS (hydride generation atomic absorption spectrometry); atom trapping using a W-coil consists of three steps. Initially BiH₃ gas is formed by hydride generation procedure. The analyte species in vapor form are transported through the W-coil trap held at 289 °C where trapping takes place. Following the preconcentration step, the W-coil is heated to 1348 °C; analyte species are released and transported to flame-heated quartz atom cell where the atomic signal is formed. In our study, interferences have been investigated in detail during Bi determination by hydride generation, both with and without trap in the same HGAAS system. Interferent/analyte (mass/mass) ratio was kept at 1, 10 and 100. Experiments were designed for carrier solutions having 1.0 M HNO₃. Interferents such as Fe, Mn, Zn, Ni, Cu, As, Se, Cd, Pb, Au, Na, Mg, Ca, chloride, sulfate and phosphate were examined. The calibration plot for an 8.0 mL sampling volume was linear between 0.10 μg L⁻¹ and 10.0 μg L⁻¹ of Bi. The detection limit (3 s/m) was 25 ng L⁻¹. The enhancement factor for the characteristic concentration (C_o) was found to be 21 when compared with the regular system without trap, by using peak height values. The validation of the procedure was performed by the analysis of the certified water reference material and the result was found to be in good agreement with the certified values at the 95% confidence level.     

Effect of tilting angles on the performance of reflective and transmitting types of fiber optic-based displacement sensors

The performances of the fiber optic-based displacement sensor with reflective and transmitting techniques were investigated. The effects of axial displacement on the detected voltage were investigated for different tilting angles of the reflective and receiving fibers. Three types of light sources were used, yellow and red He-Ne including a green pointer laser at peak wavelengths of 594, 633, and 533 nm correspondingly. The highest sensitivity and resolution were obtained at 0.0017 mV/μm and 4 μm, respectively with the employment of a 594 nm laser as the light source. These were attributed to the output power and beam quality of the laser which was the highest. The tilting angles didn’t change the sensitivity and resolution of the sensors in both setups. The widest linear range was obtained at 2410 μm with the transmitting technique. The simplicity of the design, high degree of sensitivity, linear range, non-contact measurement and low cost fabrication make it suitable for industrially-orientated applications that include control and micro-displacement in the hazardous region.     

Shape Memory Hydrogel based on a Hydrophobically‐Modified Polyacrylamide (HMPAM)/α‐CD Mixture via a Host‐Guest Approach

A novel thermally sensitive shape memory (SM) hydrogel is prepared by block copoly­merization of a cationic surfactant monomer, dimethylhexadecyl[2‐(dimethylamino)ethylmethacrylate]ammoniumbromide (C₁₆DMAEMA), and acrylamide (AM) in the presence of α‐cyclodextrin (α‐CD) using N,N’‐methylenebisacrylamide (MBA) as a crosslinker. XRD, solid state ¹³C NMR, and DSC measurements show that the crystalline domains, induced by the hydrogen bonds between α‐CDs threaded on the hydrophobic units of the polymer chains through the host‐guest approach, can reversibly melt and crystallize at different temperatures. Rheological measurements show that both the elastic modulus G’ and viscous modulus G’’ drastically change due to the formation and dissolution of the crystalline domains. These thermo‐sensitive crystalline domains serve as reversible physical crosslinks, endowing the hydrogel with excellent SM properties. Cyclic experiments show that the hydrogel can recover to almost 100% of the deformation in each cycle and can be reused several times.

     

Synthesis of Tetradentate Schiff Base Derivatives of Transition Bimetallic Complexes as Antimicrobial Agents

A series of Co(II), Cu(II), Mn(II) and Zn(II) bimetallic complexes have been synthesized with the schiff base ligand 2‐(bis‐2‐hydroxyl phenylidene) diimine (L) derived from the condensation of hydrazine and salicylaldehyde. The synthesized ligand and bimetallic complexes were characterized by different spectroscopic techniques. The characterization of ligand was carried out by FT‐IR, H¹NMR, C¹³NMR and MS while the bimetallic complexes were characterized by FT‐IR and X‐ray crystallographic techniques. The complexes and ligand were employed in vitro for antifungal and antibacterial activities using disc diffusion method. Different fungal strains such as Alternaria Alternate, Aspergillus Flavus and Aspergillus Niger were used to check antifungal activities of bimetallic complexes and ligand. Similarly, the bacterial strains used were Staphylococcus Aureus, Bacillus Subbtilis and Escheria Coli. The biological studies showed that the ligand exhibited lower value of antifungal and antibacterial activities than bimetallic complexes.