Antibacterial poly{(4‐vinyl phenylboronic acid)‐co‐[2‐(dimethylamino)ethyl methacrylate]} copolymers and their application in water‐based paints

Herein, we report the synthesis of poly(4‐vinylphenylboronic acid) (PVPBA) and poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) homopolymers, copolymers, and their methyl, pentyl, and octyl quaternized forms as dopant in water‐based permanent antibacterial paints. Both quaternized and nonquaternized forms of P(VPBA‐co‐DMAEMA) copolymers have reflected higher MIC values relative to PDMAEMA homopolymers. High molecular weight copolymers were more active against Escherichia coli ATCC 25922, contrarily, lower molecular weight copolymers showed higher antibacterial activity against Staphylococcus aureus ATCC 25923. The paint films prepared with quaternized PDMAEMA homopolymers with a weight of 10% showed better antibacterial activity in water and airborne tests than the copolymers. However, it has been shown that the inadequate anti‐biofilm properties of homopolymer‐containing paint films are overcome with the VPBA content of the copolymer structure and the most effective antibacterial and anti‐biofilm properties have been obtained with paint films containing P(VPBA‐co‐5QDMAEMA) copolymers. These paint films, which can maintain antibacterial and anti‐biofilm properties for at least 1 year, have the potential to be an alternative to Ag/Cl based solid surfaces which require the active substance to be regenerated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46245.     

Efficacy of multi-mode adhesive systems on dentin wettability and microtensile bond strength of resin composite

Purpose: To evaluate the wetting ability and the microtensile bond strength of adhesive systems in various depths of dentin. Materials and Method: 48 extracted human molars cut in half in buccolingual direction. Buccal and lingual surfaces were used to obtain deep (n = 48) and superficial (n = 48) dentin. Groups were divided into 4 subgroups: Self-etch (CSE), etch&rinse (SB), multi-mode self-etch (SAU) and multimode etch&rinse (EAU) adhesive systems. 3 consecutive contact-angle measurements were obtained: T0- 3 μl drop of distilled water on dentin; T1-Droplet of the adhesive; T2- Distilled water after polymerization of the adhesive. After composite build-ups, microtensile measurements were performed. Contact angle data were analysed with analysis of variance for repeated measures. Bond strength data were analyzed by repeated measures analysis of variance, comparisons were made according to the logarithmic values (p < 0.05). Results: The difference between groups was not significant regardless of dentin depth for all measurements (p < 0.05). All groups except CSE enhanced the wetting ability of the adhesive but reduced the wetting ability of distilled water after application of the adhesive (p < 0.05). Regarding adhesive systems, the groups showed no significant difference between bond strengths to various depths of dentin except SAU (p > 0.05); in SAU, bond strength to deep dentine were significantly higher than superficial dentin (p < 0.05). Regarding adhesives’ bond strength, CSE showed significantly greater values than the other groups (p < 0.05). Conclusion: The cavity depth does not affect the bonding ability for all adhesive systems; self-etch adhesive systems might be a better choice since different adhesives may influence the wetting ability and microtensile bond strength of the dentin substrates.     

Propylene Epoxidation: High-Throughput Screening of Supported Metal Catalysts Combinatorially Prepared by Rapid Sol–Gel Method

The gas phase oxidation of propylene using molecular oxygen was studied on a variety of supported metal catalysts. The most promising PO activity was obtained for Cu supported on high surface area SiO₂ and the multimetallic systems exhibit synergistic effects that increased the desired PO yield by several folds for Ag promoted with Cu on SiO₂ after screening a large number of catalysts by a high throughput testing technique.     

Order-disorder phase transition in NH4AlF4

In this study we calculate the specific heat C_VI for NH₄AlF₄ due to the nearest-neighbor interactions between the NH⁺ ₄ tetrahedra using an Ising model superimposed on an Einstein and/or Debye model. The specific heat C_VI calculated using a power-law formula is in good agreement with the observed C_P for the NH₄AlF₄ system. This is an indication that NH₄AlF₄ undergoes a weak first-order or a nearly second-order phase transition as predicted by our model.     

Donor-acceptor-donor type conjugated polymers for electrochromic applications: benzimidazole as the acceptor unit

Donor-acceptor-donor (DAD) type benzimidazole (BIm) and 3,4 ethylenedioxythiophene (EDOT) bearing monomers were synthesized and electrochemically polymerized. Pendant group at 2-C position of the imidazole ring was functionalized with phenyl (P1), EDOT (P2) and ferrocene (P3) in order to observe substituent effect on electrochemical and electrochromic properties of corresponding polymers. Spectroelectrochemical results showed that different pendant groups resulted in polymers with slightly different optical band gaps (1.75, 1.69 and 1.77 eV respectively) and different number of achievable colored states. Optoelectronic performance and comparison of results with other well known π-accepting benzazole bearing DAD type polymers were reported in detail.     

Chemical,thermal, and mechanical properties and ultraviolet transmittance of novel nano-hydroxyapatite/polyethylene terephthalate milk bottles

Polyethylene terephthalate (PET)/nano-hydroxyapatite (nHAp) composite granules were obtained using twin-screw extruder. Preforms were prepared by injection molding and then PET/nHAp bottles were produced by blow molding. For PET bottles with nHAp, the migration amounts of carboxylic acid (COOH), acetaldehyde (AA), diethylene glycol (DEG), and isophthalic acid (IPA); glass transition temperature (T_g); melting temperature (T_m); and the maximum crystallization temperature (T_cry) were measured. The load-carrying capacity, burst strength, stress cracking, and regional material distribution tests were carried out on the bottles. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and ultraviolet transmittance analyses were conducted to explain the changes in mechanical, chemical, physical properties, and light transmission of bottles. It was found out that the COOH amount increased and the AA content decreased with increasing nHAp amount. On the other hand, no change was observed in the amounts of DEG and IPA. Although the mechanical properties such as load-carrying capacity and burst strength of the bottles have improved, it has been determined that the standard environmental stress crack resistance test procedure cannot be applied to such a composite. Experimental findings indicate that nHAp disrupts the chemical structure of PET and it isolates harmful chemicals such as AA by forming intermolecular bonds. Moreover, with the addition of up to 0.8% nHAp, PET bottles block the light transmission approximately 80% within 400–700 nm wave length zone. The study demonstrates that the PET/nHAp composite bottles can be used in the food industry, particularly in the packaging of milk and milk products which are vulnerable to light exposure.     

Gold and Cobalt Oxide Nanoparticles Modified Poly-Propylene Poly-Ethylene Glycol Membranes in Poly (ε-Caprolactone) Conduits Enhance Nerve Regeneration in the Sciatic Nerve of Healthy Rats

Reconstruction of nerve defects is a clinical challenge. Autologous nerve grafts as the gold standard treatment may result in an incomplete restoration of extremity function. Biosynthetic nerve conduits are studied widely, but still have limitations. Here, we reconstructed a 10 mm sciatic nerve defect in healthy rats and analyzed nerve regeneration in poly (ε-caprolactone) (PCL) conduits longitudinally divided by gold (Au) and gold-cobalt oxide (AuCoO) nanoparticles embedded in poly-propylene poly-ethylene glycol (PPEG) membranes (AuPPEG or AuCoOPPEG) and compared it with unmodified PPEG-membrane and hollow PCL conduits. After 21 days, we detected significantly better axonal outgrowth, together with higher numbers of activated Schwann cells (ATF3-labelled) and higher HSP27 expression, in reconstructed sciatic nerve and in corresponding dorsal root ganglia (DRG) in the AuPPEG and AuCoOPPEG groups; whereas the number of apoptotic Schwann cells (cleaved caspase 3-labelled) was significantly lower. Furthermore, numbers of activated and apoptotic Schwann cells in the regenerative matrix correlated with axonal outgrowth, whereas HSP27 expression in the regenerative matrix and in DRGs did not show any correlation with axonal outgrowth. We conclude that gold and cobalt-oxide nanoparticle modified membranes in conduits improve axonal outgrowth and increase the regenerative performance of conduits after nerve reconstruction.     

Prediction of the colorimetric parameters and mass loss of heat‐treated bamboo: Comparison of multiple linear regression and artificial neural network method

In this study, the colorimetric parameters (L*, a*, b*) and mass loss of heat‐treated bamboo were investigated, and the obtained results were modeled by using two methods: multiple linear regression (MLR) and artificial neural network (ANN). First, bamboo samples were exposed to heat treatment at different temperatures (110°C, 140°C, 170°C, and 200°C) and durations (15, 30, 45, 60, 75, 90, and 115 minutes) in a laboratory oven. Then, the colorimetric parameters (L*, a*, b*) and mass loss of each sample were measured after each period of heat treatment. All data were modeled by using two methods separately for each parameter and the performances of these proposed methods were compared. It was found that color change and mass loss increased with increasing temperature and duration of heat treatment. Mean absolute percentage error (MAPE) values of all obtained MLR ranged from 0.64% to 10.63%, while the all MAPE values of ANN were found to be lower than 1.5%. Based on these results, it can be said that MLR and ANN could be used to evaluate the changes on the selected properties of heat‐treated bamboo samples. On the other hand, it should be emphasized that the ANN gave more accurate results than the MLR method because of its learning capability.     

Performance evaluation of a submerged membrane bioreactor for the treatment of brackish oil and natural gas field produced water

Produced water, which is co-produced during oil and gas manufacturing, represents one of the largest sources of oily wastewaters. Therefore, treatment of this produced water may improve the economic viability and lead to a new source of water for beneficial use. In this study a submerged hollow fiber membrane bioreactor (MBR) has been studied experimentally for the treatment of brackish oil and natural gas field produced water. This type of wastewater is also characterized with relatively moderate to high amount of salt, oil and total petroleum hydrocarbons (TPH). However, the bacteria which are growing in conventional activated sludge and MBR cannot survive at these strict conditions, therefore acclimation of the bacteria is of vital importance. The performance of the biological system, membrane permeability, the rate and extent of TPH biodegradability have been investigated under different sludge age and F/M ratios. The results obtained by gas chromatography analyses showed that the MBR system could be very effective in the removal of TPH from produced water and a significant improvement in the effluent quality was achieved.     

A minisum location problem with regional demand considering farthest Euclidean distances

We consider a continuous multi-facility location-allocation problem that aims to minimize the sum of weighted farthest Euclidean distances between (closed convex) polygonal and/or circular demand regions, and facilities they are assigned to. We show that the single facility version of the problem has a straightforward second-order cone programming formulation and can therefore be efficiently solved to optimality. To solve large size instances, we adapt a multi-dimensional direct search descent algorithm to our problem which is not guaranteed to find the optimal solution. In a special case with circular and rectangular demand regions, this algorithm, if converges, finds the optimal solution. We also apply a simple subgradient method to the problem. Furthermore, we review the algorithms proposed for the problem in the literature and compare all these algorithms in terms of both solution quality and time. Finally, we consider the multi-facility version of the problem and model it as a mixed integer second-order cone programming problem. As this formulation is weak, we use the alternate location-allocation heuristic to solve large size instances.