Cellulose Acetate-g-Polycaprolactone Copolymerization Using Diisocyanate Intermediates and the Effect of Polymer Chain Length on Surface,Thermal, and Antibacterial Properties

The need for biodegradable and biocompatible polymers is growing quickly, particularly in the biomedical and environmental industries. Cellulose acetate, a natural polysaccharide, can be taken from plants and modified with polycaprolactone to improve its characteristics for a number of uses, including biomedical applications and food packaging. Cellulose acetate-g-polycaprolactone was prepared by a three-step reaction: First, polymerization of ε-caprolactone via ring-opening polymerization (ROP) reaction using 2-hydroxyethyl methacrylate (HEMA) and functionalization of polycaprolactone(PCL) by introducing NCO on the hydroxyl end of the HEMA-PCL using hexamethyl lenediisocyanate(HDI) were carried out. Then, the NCO–HEMA-PCL was grafted onto cellulose acetate (using the “grafting to” method). The polycaprolactone grafted cellulose acetate was confirmed by FTIR, the thermal characteristics of the copolymers were investigated by DSC and TGA, and the hydrophobicity was analyzed via water CA measurement. Introducing NCO-PCL to cellulose acetate increased the thermal stability. The contact angle of the unreacted PCL was higher than that of cellulose acetate-g-PCL, and it increased when the chain length increased. The CA-g-PCL50, CA-g-PCL100, and CA-g-PCL200 showed very high inhibition zones for all three bacteria tested (E. coli, S. aureus, and P. aeruginosa).     

Development of Ultrahigh Permeance Hollow Fiber Membranes via Simple Surface Coating for CO2/CH4 Separation

Most researchers focused on developing highly selective membranes for CO₂/CH₄ separation, but their developed membranes often suffered from low permeance. In this present work, we aimed to develop an ultrahigh permeance membrane using a simple coating technique to overcome the trade-off between membrane permeance and selectivity. A commercial silicone membrane with superior permeance but low CO₂/CH₄ selectivity (in the range of 2–3) was selected as the host for surface modification. Our results revealed that out of the three silane agents tested, only tetraethyl orthosilicate (TEOS) improved the control membrane’s permeance and selectivity. This can be due to its short structural chain and better compatibility with the silicone substrate. Further investigation revealed that higher CO₂ permeance and selectivity could be attained by coating the membrane with two layers of TEOS. The surface integrity of the TEOS-coated membrane was further improved when an additional polyether block amide (Pebax) layer was established atop the TEOS layer. This additional layer sealed the pin holes of the TEOS layer and enhanced the resultant membrane’s performance, achieving CO₂/CH₄ selectivity of ~19 at CO₂ permeance of ~2.3 × 10⁵ barrer. This performance placed our developed membrane to surpass the 2008 Robeson Upper Boundary.     

Chemical Composition Profiling and Antifungal Activity of Saffron Petal Extract

Numerous fungal plant pathogens can infect fresh fruits and vegetables during transit and storage conditions. The resulting infections were mainly controlled by synthetic fungicides, but their application has many drawbacks associated with the threatened environment and human health. Therefore, the use of natural plants with antimicrobial potential could be a promising alternative to overcome the side effects of fungicides. In this regard, this study aimed at evaluating the antifungal activity potential of saffron petal extract (SPE) against three mains important fungal pathogens: Rhizopus stolonifer, Penicillium digitatum and Botritys cinerea, which cause rot decay on the tomato, orange and apple fruits, respectively. In addition, the organic composition of SPE was characterized by attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy and its biochemical, and gas chromatography-mass spectrometry (GC-MS) analyses were carried out. The obtained results highlighted an increased inhibition rate of the mycelial growth and spore germination of the three pathogenic fungi with increasing SPE concentrations. The mycelial growth and spore germination were completely inhibited at 10% of the SPE for Rhizopus stolonifer and Penicillium digitatum and at 5% for B. cinerea. Interestingly, the in vivo test showed the complete suppression of Rhizopus rot by the SPE at 10%, and a significant reduction of the severity of grey mold disease (37.19%) and green mold, when applied at 5 and 10%, respectively. The FT-IR spectra showed characteristic peaks and a variety of functional groups, which confirmed that SPE contains phenolic and flavonoid components. In addition, The average value of the total phenolic content, flavonoid content and half-maximal inhibitory concentration (IC₅₀) were 3.09 ± 0.012 mg GAE/g DW, 0.92 ± 0.004 mg QE/g DW and 235.15 ± 2.12 µg/mL, respectively. A volatile analysis showed that the most dominant component in the saffron petal is 2(5H)-Furanone (92.10%). Taken together, it was concluded that SPE could be used as an alternative to antioxidant and antifungal compounds for the control of postharvest diseases in fruits.     

Polyphenolic Profile of Callistemon viminalis Aerial Parts: Antioxidant,Anticancer and In Silico 5-LOX Inhibitory Evaluations

Five new compounds viz kaempferol 3-O-(4″-galloyl)-β-d-glucopyranosyl-(1‴→6″)-O-β-d-glucopyranoside (1), kaempferol 3-O-β-d-mannuronopyranoside (2), kaempferol 3-O-β-d-mannopyranoside (3), quercetin 3-O-β-d-mannuronopyranoside (4), 2, 3 (S)- hexahydroxydiphenoyl]-d-glucose (5) along with fifteen known compounds were isolated from 80% aqueous methanol extract (AME) of C. viminalis. AME and compounds exerted similar or better antioxidant activity to ascorbic acid using DPPH, O₂⁻, and NO inhibition methods. In addition, compounds 16, 4, and 7 showed cytotoxic activity against MCF-7 cell lines while 3, 7 and 16 exhibited strong activity against HepG2. An in silico analysis using molecular docking for polyphenolic compounds 2, 3, 7, 16 and 17 against human stable 5-LOX was performed and compared to that of ascorbic acid and quercetin. The binding mode as well as the enzyme-inhibitor interactions were evaluated. All compounds occupied the 5-LOX active site and showed binding affinity greater than ascorbic acid or quercetin. The data herein suggest that AME, a source of polyphenols, could be used against oxidative-stress-related disorders.     

Solving the generalized Burgers–Huxley equation using the Adomian decomposition method

In this paper, a convergence proof of the Adomian decomposition method (ADM) applied to the generalized nonlinear Burgers–Huxley equation is presented. The decomposition scheme obtained from the ADM yields an analytical solution in the form of a rapidly convergent series. The direct symbolic–numeric scheme is shown to be efficient and accurate.     

Electrical conduction and thermodynamic properties of K2NiP2O7

The pyrophosphate K₂NiP₂O₇ has been synthesized by the classic ceramic method and characterized by X-ray diffraction, solid-state ³¹P magic angle spinning (MAS) NMR, and IR and electrical impedance spectroscopy. The solid-state ³¹P MAS NMR, performed at 121.49 MHz, shows two isotropic resonances at ?17.66 and ?19.94 ppm, revealing the existence of two phosphorus environments in the structure. The electrical conductivity and dielectric properties have been investigated in the frequency and the temperature range of 200 Hz–1 MHz and 603–728 K, respectively. The frequency dependence of the conductivity is interpreted using the augmented Jonscher relation. The close values of activation energies obtained from the analysis of hopping frequency and dc conductivity imply that the transport is through ion hopping mechanism. The charge carrier concentration in the investigated sample has been evaluated using the Almond–West formalism and shown to be independent of temperature. Thermodynamic parameters such as the free energy of activation ΔF, the enthalpy ΔH, and the change in entropy ΔS have been calculated.     

Probabilistic approach to homogenization of a non-divergence form semilinear PDE with non-periodic coefficients

We consider a semilinear partial differential equation (PDE) of non-divergence form perturbed by a small parameter. We then study the asymptotic behavior of Sobolev solutions in the case where the coefficients admit limits in C?esaro sense. Neither periodicity nor ergodicity will be needed for the coefficients. In our situation, the limit (or averaged or effective) coefficients may have discontinuity. Our approach combines both probabilistic and PDEs arguments. The probabilistic one uses the weak convergence of solutions of backward stochastic differential equations (BSDE) in the Jakubowski S-topology, while the PDEs argument consists to built a solution, in a suitable Sobolev space, for the PDE limit. We finally show the existence and uniqueness for the associated averaged BSDE, then we deduce the uniqueness of the limit PDE from the uniqueness of the averaged BSDE.     

Asymptotic analysis of equilibrium states for rotating turbulent flows

The equilibrium states of homogeneous turbulence simultaneously subjected to a mean velocity gradient and a rotation are examined by using asymptotic analysis. The present work is concerned with the asymptotic behavior of quantities such as the turbulent kinetic energy and its dissipation rate associated with the fixed point (/kS)=0, whereS is the shear rate. The classical form of the model transport equation for (Hanjalic and Launder, 1972) is used. The present analysis shows that, asymptotically, the turbulent kinetic energy (a) undergoes a power-law decay with time for (P/)<1, (b) is independent of time for (P/)=1, (c) undergoes a power-law growth with time for 1<(P/)<(C ₂–1), and (d) is represented by an exponential law versus time for (P/)=(C ₂–1)/(C ₁–1) and (/kS)>0 whereP is the production rate. For the commonly used second-order models the equilibrium solutions forP/,II, andIII (whereII andIII are respectively the second and third invariants of the anisotropy tensor) depend on the rotation number when (P/kS)=(/kS)=0. The variation of (P/kS) andII versusR given by the second-order model of Yakhot and Orzag are compared with results of Rapid Distortion Theory corrected for decay (Townsend, 1970).     

A New Way to Silicone‐Based Peptide Polymers

We describe a new class of silicone‐containing peptide polymers obtained by a straightforward polymerization in water using tailored chlorodimethylsilyl peptide blocks as monomeric units. This general strategy is applicable to any type of peptide sequences, yielding linear or branched polymer chains composed of well‐defined peptide sequences.