Biodegradable latexes from animal-derived waste: Biosynthesis and characterization of mcl-PHA accumulated by Ps. citronellolis

Backgroundmcl-PHA biosynthesis by Pseudomonas citronellolis from tallow-based biodiesel as inexpensive carbon feed stock was accomplished. Fermentation protocols, kinetic analysis, an efficient product recovery strategy, and a detailed product characterization are presented.ResultsA maximum specific growth rate, μ_max. of 0.10 and 0.08 h^?1, respectively, was achieved in two different fermentation set-ups. Volumetric productivity for mcl-PHA amounted to 0.036 g/L h and 0.050 g/L h, final intracellular PHA contents calculated from the sum of active biomass and PHA to 20.1 and 26.6 wt.%, respectively. GC-FID analysis showed that the obtained biopolyester predominantly consists of 3-hydroxyoctanoate and 3-hydroxydecanoate, and, to a minor extent, 3-hydroxydodecanoate, 3-hydroxynonanoate, 3-hydroxyhexanoate, and 3-hydroxyheptanoate monomers. This was confirmed by ¹H- and ¹³C NMR, also evidencing the occurrence of low quantities of unsaturated and 3-hydroxyvalerate building blocks. High purity of the recovered materials was proofed by elemental analysis. Regarding the results from thermogravimetric analysis, differential scanning calorimetry and molecular mass determination, results were in a range typical for this type of PHA (1st fermentation: decomposition temperature T_d = 296 °C, peak of melting range T_m = 48.6 °C; glass transition temperature T_g = ?46.9 °C, degree of crystallinity X_c = 12.3%, M_w = 66,000, M_n = 35,000, dispersity index P_i = 1.9; 2nd fermentation: T_d = 295 °C, T_m = 53.6 °C, T_g = -43.5 °C, X_c = 10.4%, M_w = 78,000, M_n = 196,000, P_i = 2.5).     

The first example of extended structure constructed from Knoth-type sandwich POMs and coordination fragments

A novel compound [P₂W₁₈M₃O₆₈][Cu(en)₂]₄·7H₂O·2OH^? (M = 0.5W + 0.5Cu) 1 which contains the first example of extended structure constructed from Knoth-type sandwich polyoxoanions and transition metal coordination complexes has been hydrothermally synthesized and characterized by elemental analysis, IR spectrum, UV–Vis spectrum and single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, space group, P-1, a = 13.2718(7) Å, b = 13.6432(8) Å, c = 25.7307(15) Å, α = 104.7340(10)°, β = 96.7630(10)°, γ = 90.0330(10)°, V = 4472.2(4) Å³, Z = 2. Structure solution and refinement based on 1090 parameters gave R1 (wR2) = 0.0409 (0.0993).     

Development of asymmetric BTDA-TDI/MDI (P84) copolyimide flat sheet and hollow fiber membranes for ultrafiltration: Morphology transition and membrane performance

In this paper, the effects of γ-butyrolactone (GBL) weight ratio (w_GBL) and membrane thickness on the formation of asymmetric flat sheet membranes prepared with P84 (BTDA-TDI/MDI co-polyimide)/N-methyl-2-pyrrolidone (NMP)/GBL casting solutions are investigated. With the increase of membrane thickness, the transition of membrane morphology from sponge-like to finger-like structure occurs at critical structure-transition thickness L_c. L_c and the general sponge-like structure thickness (L_gs) increase with w_GBL. For 20 wt.% P84/NMP/GBL casting solution, the membrane morphology changes from finger-like to sponge-like structure at the critical weight ratio of GBL (w^? = 0.69). The membrane morphology and performance of hollow fibers spun with various w_GBL are observed. Compared with the hollow fiber membranes made of 18 wt.% P84/NMP/GBL dope solution with w_GBL = 0.75, the hollow fiber membranes spun with w_GBL = 0.25 present a higher permeation flux and a larger MWCO. As w_GBL increases from 0.25 to 0.75, the membrane morphology transfers from finger-like to sponge-like structure. An increase in shear rate shifts the rejection curves towards left, and lowers the MWCO of hollow fiber membranes. For hollow fiber membranes spun with w_GBL = 0.75, a relatively high permeation flux and a large MWCO are obtained by the wet spinning process.     

Photocatalytic degradation of acetic acid on spinel ferrites MFe2O4 (M = Mg,Zn, and Cd)

Spinel ferrites MFe₂O₄(M = Mg, Zn, and Cd) with Fe(III) in a d⁵ electron configuration were prepared via a conventional solid-state reaction. The amount of CO₂ generated by the photocatalytic degradation of acetic acid on these ferrites was measured under irradiation by a xenon lamp with a power of 300 W. Photocatalytic degradation was observed for all the compounds, and the results revealed that MgFe₂O₄ exhibited the highest degradation, i.e., 196 μmol/g/h. The degradation in the presence of MFe₂O₄(M = Mg, Zn, and Cd) increased with increasing heating condition.     

Influence of A- and B-site doping on the properties of the system La2CoO4±δ

In the present paper the compounds LaSrCo_0.5M_0.5O_4±δ (M = Co, Fe, Mn, Ni) and La_1.4Sr_0.6Co_0.5M_0.5O_4±δ (M = Co, Ni) were prepared and characterised in order to elucidate the influence of strontium doping on A-site as well as doping with transition metals on B-site of the mixed conductor La₂CoO_4±δ. All the prepared oxides of this paper possessed the K₂NiF₄ structure, exhibited high electrical conductivity (>100 S/cm) and adequately low linear thermal expansion coefficient. Therefore, they are very promising materials for high temperature electrochemical applications.     

Microsphere pressure sensitive adhesives—acrylic polymer/montmorillonite clay nanocomposite materials

In this study, the synthesis and characterization of acrylic polymer/montmorillonite (MMT) clay nanocomposite pressure sensitive adhesives (PSA) are presented. Different types and amounts of modified and unmodified montmorillonite clays were dispersed in ethyl acrylate (EA)/2-ethylhexyl acrylate (2-EHA) monomer mixture, which was then polymerized using a suspension polymerization technique. Polymerization was monitored in-line using attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy. The adhesion properties of the synthesized nanocomposite materials were determined using standard measurements of tack, peel and shear strength. Viscoelastic properties of dried adhesive films were analyzed using dynamic mechanical analysis (DMA). The results showed that the kinetics of suspension polymerization was independent of the addition of MMT clays. On the other hand, adhesive properties were strongly influenced by the type and the amount of MMT clay added. While peel strength and tack gradually decreased with higher amount of modified MMT clay, a substantial increase in shear strength was determined with a maximal value at 1 wt% of added MMT clay. Moderate influence on tack, peel and shear strength was observed when the unmodified type of MMT clay was used. DMA analysis showed an increase in storage modulus (G′) for adhesives synthesized with MMT clay addition, but no significant differences were determined between particular types of MMT clays. A decrease in tan δ value for adhesives with 1 wt% of added MMT clay was observed, which also concurs with higher shear strength and implies to the improved cohesion of adhesive.     

Large-scale microwave-assisted ring-opening polymerization of ɛ-caprolactone

To probe into the industrialization possibility of microwave-assisted ring-opening polymerization (ROP) of ?-caprolactone (?-CL), it was performed with monomer mass from 750 to 2450 g using a self-designed industrial microwave oven (6000 W) catalyzed by stannous octanoate (Sn(Oct)₂) (M/Cat = 1000). The large-scale ROP of ?-CL proceeded smoothly at various microwave power levels (850, 1700, and 2550 W) and produced poly(?-caprolactone) (PCL) with weight-average molar mass (M_w) from 66,000 to 12,2000 g/mol within 40 min in a yield over 93%. The structure of PCL was characterized by ¹H and ¹³C NMR, FT-IR, DSC and WAXD. We propose that the microwave ROP of ?-CL is a potential technology to prepare PCL commercially.     

Investigation of oil palm based Kraft and auto-catalyzed organosolv lignin susceptibility as a green wood adhesives

The aim of this study is to highlight the application and potentiality of oil palm based lignins in the synthesis of green phenolic resins. The delignification processes were conducted using Kraft and auto-catalyzed ethanol–water pulping processes. The extracted lignins were characterized using elemental analysis, Fourier transform-infrared, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, molecular weight distribution (M_n, M_w and polydispersity), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The obtained FTIR results revealed that the Kraft lignin contained substantial amounts of guaiacyl units with smaller amounts of syringyl units. The molecular weight of Kraft lignin was 1564 g mol⁻¹ which is higher than organosolv lignin at 1231 g mol⁻¹. The activated free ring position (2.99%) of Kraft lignin was comparatively higher than that of organosolv lignin (2.06%) which was measured using Mannich reactivity analysis. Thermal analysis of Kraft lignin showed higher thermal stability compared to organosolv lignin. The structural and thermal characteristics implied that Kraft lignin had higher potential for the production of green phenolic resins when compared with organosolv lignin.     

First 3D coordination polymer built from Ho(III) and 2-aminoterephthalate ligand

Novel three-dimensional (3D) coordination polymer {[Ho₂(μ₃-ATA)₂(μ₄-ATA)(H₂O)₄]·2DMF·1/2H₂O}_n (1), built from Ho(III) cations and 2-aminoterephthalate anionic ligands (ATA^2 −) was prepared and studied. The compound 1 contains 1D structural channels with the size 4.1 × 6.8 Å², which propagate along b crystallographic axis. The channels are filled with the solvent molecules. The Ho(III) atom is eight-coordinated with distorted square anti-prismatic geometry. Complex was characterized by single crystal X-ray diffraction, thermogravimetry coupled with simultaneous evolved gas analysis using mass spectrometry (TG/DTG–DTA–EGA), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), solid-state UV–VIS spectroscopy and nitrogen adsorption at 77 K. After the desolvation the 1D structural channels collapse. The process is accompanied by structure transformation, however, according to the TG–DTA–EGA results, the Ho–ATA polymeric framework is stable up to 450 °C.     

Competition between 3d metals(II) and palladium(II) in the reaction of heterobimetallic complexes Pd(μ-OOCMe)4M(OH2) (M = Ni,Co, Mn) with azobenzene

The reaction of Pd^II(μ-OOCMe)₄M^II(OH₂) (M = Ni, Co, Mn) with azobenzene under mild conditions produces the homonuclear complex with ortho-metallated azobenzene (PhN = NC₆H₄)₂Pd₂(μ-OOCMe)₂ (4) in higher than 90 % yield as the sole Pd-containing reaction product, while the co-metals are recovered as the corresponding M^II acetates.     

Polymer-assisted precipitation of ZnO nanoparticles with narrow particle size distribution

Zinc oxide nanoparticles were produced by aqueous precipitation in mild hydrothermal conditions (90 °C). Well crystallized regular roundish particles were obtained, with a very narrow size distribution. The influence of soft templates (organic species) to control size and size distribution in the final product was investigated. No effect was observed with polyvinylpyrrolidone (PVP M_w 8000 and 40,000), (d?)fructose and hydroxypropylmethylcellulose (HPMC). A significant decrease of the particle size towards 100 nm, while conserving a very narrow size distribution was observed for poly(acrylic acid) (PAA M_w 2000), Dispex A40 (commercial PAA from CIBA M_w ～10,000), and sodium dodecylsulfate (SDS). The influence of the pH was also investigated with PAA. By increasing the pH from slightly acidic to basic conditions, the morphology was spectacularly modified from roundish nanoparticles to micronic branched flower-like particles, with an elongated primary crystal morphology.     

Structural,thermal, dielectric and ac conductivity properties of lithium fluoro-borate optical glasses

Transparent and stable glasses in the chemical composition of Li₂O–LiF–B₂O₃–MO (M = Zn and Cd) have been prepared by a conventional melt quenching method. For these glasses, absorption spectra, structural (XRD, FT-IR, and Raman spectra), thermal (TG–DTA and DSC), dielectric (?′, ?″, tan δ), ac conductivity (σ_ac), and electric modulus (M′ and M″) have been investigated. Amorphous nature of these glasses has been confirmed from their XRD profiles. The LFB glasses with the presence of ZnO or CdO an extended UV-transmission ability has been achieved. The measured FT-IR and Raman spectra have exhibited the vibrational bands of B–O from [BO₃] and [BO₄] units and Li–O. The dielectric properties (tan δ, dielectric constant (?′), dielectric loss (?″)), electrical modulus and electrical conductivity (σ_ac) of these glasses have also been studied from 100 Hz to 1 MHz at the room temperature. Based on the trends noticed in the ac conductivities, the present glasses could be found useful as battery cathode materials.     

Chloride-induced corrosion of steel in cracked concrete—Part II: Corrosion rate prediction models

Chloride-induced corrosion rate (i_corr) prediction models for RC structures in the marine tidal zone that incorporate the influence of crack width (w_cr), cover (c) and concrete quality are proposed. Parallel corrosion experiments were carried out for 2¼ years by exposing one half of 210 beam specimens (120 × 130 × 375 mm long) to accelerated laboratory corrosion (cyclic wetting and drying) while the other half underwent natural corrosion in the tidal zone. Experimental variables were w_cr (0, incipient crack, 0.4, 0.7 mm), c (20, 40 mm), binder type (PC, PC/GGBS, PC/FA) and w/b ratio (0.40, 0.55). The two proposed models (one each for accelerated and natural i_corr) can aid not only in quantifying the propagation phase, but also provide a novel way to select c, w_cr and concrete quality.     

Synthesis and characterization of polymeric resins with aliphatic and aromatic amino ligands and their sorption behavior towards gold from ammonium hydroxide solutions

The functional resins with amino ligands are synthesized by the modification of lightly crosslinked poly(vinylbenzyl chloride–divinylbenzene) matrix with the following amines: 1-methylpiperazine, ethylenediamine, dipropylamine, 1-methylimidazole, 2-mercapto-1-methylimidazole, 1,2-dimethylimidazole and 1-(3-aminopropyl) imidazole. Two methods of the modification reactions were employed, the first one is the traditional heating of the polymer with either neat amine or amine solution in an appropriate solvent, the second method is heating of the reaction mixture in a microwave reactor. The resultant resins show different degrees of modification depending on the applied method and contain 1.61–3.68 mmol of ligand/g. The 1-methylimidazole resin displays the highest affinity towards gold from ammonium buffer (100 g/dm³ NH₃ · H₂O, 50 g/dm³ (NH₄)₂SO₄). For this resin, the sorption is as high as 15.5 mg/g and log K_d (distribution coefficient) value is 2.94. All resins are highly selective and they do not sorb copper amino complexes.These polymeric materials were characterized using nitrogen, sulfur and chlorine elemental analysis and FTIR spectroscopy.     

AGET ATRP of methyl methacrylate catalyzed by FeCl3/iminodiacetic acid in the presence of air

The recently developed living free-radical polymerization system, atom transfer radical polymerization using activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), was used for methyl methacrylate (MMA) polymerization in the presence of a limited amount of air, using a novel catalyst system based on iron (FeCl₃) complexes with iminodiacetic acid (IDA) and using ascorbic acid (VC) as a reducing agent. The kinetics of AGET ATRPs of MMA with different amounts of VC in the presence of air was investigated. The results of the polymerizations demonstrated the features of “living”/controlled free-radical polymerization such as the number-average molecular weights increasing linearly with monomer conversion and narrow molecular weight distributions (M_w/M_n = 1.31–1.44).     

Suprarmolecular hydrogels driven by the dual host–guest interactions between α-cyclodextrin and ferrocene-modified poly(ethylene glycol) with low-molecular-weight

In general, α-cyclodextrin (α-CD) and low-molecular weight poly(ethylene glycol) (low-MW PEG) (M_w = 400–10,000) cannot construct supramolecular hydrogels but easily form crystalline precipitates. In this study, low-MW PEG (M_n = 2000, PEG-2000) was functionalized by ferrocene as mono-end-group. The obtained ferrocene-modified PEG-2000 (FcPEG-2000) further self-assembled into supramolecular hydrogel with α-CD even at low concentration (C_FcPEG-2000 = 17 mg/ml), driven by dual host–guest interaction between α-CD and FcPEG-2000. Interestingly, the hydrogel was still observed even when hydrophobic Fc group was oxidized to hydrophilic ferrocenium (Fc⁺) or included into the cavity of β-CD. In the former case, the existence of Fc⁺ end groups is considered to decrease the probability of PEG de-penetration from α-CD cavity, so that α-CDs have more location and opportunities to aggregate into more channel-type crystalline domains as physical cross-linking points. While in the later case, the synergistic effect of host–guest interaction between β-CD and ferrocenyl groups and host–guest interaction between α-CD and PEG chains are considered to be the main reason. The resultant FcPEG-2000 based hydrogels showed the property of shear-thinning.     

Phase behavior for the poly(dimethylsiloxane) in supercritical fluid solvents

In this work, cloud-point and bubble-point phase behavior data are reported for the poly(dimethylsiloxane) [PDMSA] in supercritical carbon dioxide, propane, propylene, butane, 1-butene and dimethyl ether (DME). The static-type method, using a variable-volume view cell, was employed to obtain the experimental data at the temperature range for (315.2–454.9) K and pressure up to 55.52 MPa. PDMS (M_w = 38,900) + C₄ cloud-point curves are ～10 MPa lower than the PDMS + C₃ curves at constant temperature of 423 K. Cloud-point curves for the PDMS + solvents system show the lower critical solution temperature (LCST) region.     

Synthesis and characterization of alkyd resins based on Camelina sativa oil and polyglycerol

A one pot synthesis of alkyd resins based on the Camelina sativa oil as a new renewable raw material and on polyglycerols as polyols was carried out. The oligomerization of glycerol was conducted in the presence of LiOH (0.1 wt%) at 245 °C. The total content of diglycerol reached its maximum (about 33.5 wt%) after 7 h. The oligomerization product with no additional treatment was subjected to the alcoholysis reaction with purified camelina oil. The alkyd resin was obtained after polycondensation of the alcoholysis products with phthalic and maleic anhydrides at 230–250 °C. A real possibility was determined for the synthesis of alkyd resins with some properties similar to those which can be found in equivalent products manufactured on the basis of semi drying oil and pentaerythritol like flexibility and drying time.     

Microwave dielectric properties of (Zn1/3B2/3)0.5(Ti0.8M0.2)0.5O2 (B = Nb5+, Ta5+, M = Sn4+, Ge4+) ceramics

Dielectric properties of (Zn_1/3Nb_(2?x)/3Ta_x/3)_0.5(Ti_0.8Sn_0.1Ge_0.1)_0.5O₂ (x = 0, 1, 2) and/or (Zn_1/3Nb_1/3Ta_l/3)_0.5(Ti_0.8Sn_0.2(l?y)Ge_0.2y)_0.5O₂ (y = 0, 0.5, 1) were investigated at the microwave frequencies. For the compositions with single phase of rutile structure, the dielectric constant (K) of specimens was not only dependent on the dielectric polarizabilities, but also on the bond length ratio of apical bond (d_apical) to equatorial bond (d_equatorial) of oxygen octahedron in the unit cell. Temperature coefficients of the resonant frequencies (TCF) of the specimens with B = Nb⁵⁺ and/or M = Sn⁴⁺ was larger than those with B = Ta⁵⁺ and/or M = Ge⁴⁺. These results could be attributed to the changes of the degree of oxygen octahedral distortion. Quality factors (Qf) of the specimens with B = Ta⁵⁺ and/or M = Sn⁴⁺ were larger than those with B = Nb⁵⁺ and/or M = Ge⁴⁺.