Screening and optimization through response surface methodology for synthesis of pH,temperature and salt‐sensitive Aloe vera–acrylic acid‐based biodegradable hydrogel: Its evaluation as dye adsorbent

A pH‐, temperature‐, and salt‐sensitive hydrogel was synthesized using acrylic acid (AA) as monomer, natural polysaccharide Aloe vera as backbone, ammonium persulfate–N,N‐methylene‐bis‐acrylamide as an initiator–crosslinker system via free‐radical grafting method. Different parameters such as treatment time, temperature, amount of solvent, pH, concentration of initiator, crosslinker and monomer were screened using Plackett–Burman design (PBD). The PBD showed that pH, monomer, and crosslinker were taken as the most important variables, which highly impact the swelling behavior of the synthesized hydrogel as compared to the rest of the variables. The half normality plot was used to find the significant parameters regarding the swelling capacity of the hydrogel. The center composite design was used for further optimizing the important variables like pH, monomer, and crosslinker. The pH and monomer interaction on percentage swelling (Ps) was studied through the analysis of variance model. Synthesized hydrogel Av‐cl‐poly(AA) was characterized by different techniques such as Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction, and scanning electron microscopy (SEM). The effect of different chloride salt solutions like KCl, NaCl, BaCl₂, FeCl₃, and CoCl₃·6H₂O on Ps of synthesized Av‐cl‐poly(AA)‐based hydrogel was also studied. Biodegradation studies of the synthesized polymer were also carried out using soil burial and vermicompositing methods. Biodegradation of semi interpenetrating polymer network (SIPN) was confirmed by SEM and FTIR techniques. Synthesized SIPN was also used as a device for the removal of dye and was found very effective as an adsorbent. POLYM. ENG. SCI., 59:2323–2334, 2019. © 2019 Society of Plastics Engineers     

Single drop behaviour in a high shear granulator

The wet granulation process starts when a liquid drop makes contact with the powder bed. In a powder bed, drops are subjected to centripetal and gravitational forces. These forces may affect the size and shape of the drop as it is incorporated into the bed. The majority of experiments studying droplet behaviour have been performed on static bed surfaces. This paper seeks to demonstrate droplet behaviour during the initial contact stage with a dynamic powder bed representative of that occurring during high shear granulation. Particle image velocimetry (PIV) is used to determine droplet and powder bed surface velocities. Due to inclination of powder bed part of drop de-accelerate slowly moved downward while other parts remain attached to powder bed this result in their deformation and breakage. Amount of deformation of drop and span of area where it occurred was increased as drop was added farther from the outer edge of the mixer. This paper shows that the binder drop may deform or break in high shear granulator depending on its initial impact position. This will affect size distribution and other properties of nuclei.     

Attainable regions of reactive distillation. Part II: Single reactant azeotropic systems

In reactive distillation (RD) one can conveniently manipulate the concentration profiles on the reactive stages by exploiting the difference in volatility of the various components. This property of RD can be advantageously used to improve the selectivity toward the desired product in case of series or series parallel reactions, and obtain a performance superior to the network of conventional reactors. In the previous work [Agarwal, V., et al., 2008. Attainable regions of reactive distillation—Part I. Single reactant non-azeotropic systems. Chemical Engineering Science, submitted for publication], we introduced representative unit models of RD to obtain the attainable regions of RD for non-azeotropic systems. In this work, we extend the approach to a system involving single binary azeotrope. Design guidelines have been formulated based on the residue curve maps, to obtain the improved attainable region with the help of these representative RD models either alone or in the form of their network.     

Combined Therapy Using Human Corneal Stromal Stem Cells and Quiescent Keratocytes to Prevent Corneal Scarring after Injury

Corneal blindness due to scarring is conventionally treated by corneal transplantation, but the shortage of donor materials has been a major issue affecting the global success of treatment. Pre-clinical and clinical studies have shown that cell-based therapies using either corneal stromal stem cells (CSSC) or corneal stromal keratocytes (CSK) suppress corneal scarring at lower levels. Further treatments or strategies are required to improve the treatment efficacy. This study examined a combined cell-based treatment using CSSC and CSK in a mouse model of anterior stromal injury. We hypothesize that the immuno-regulatory nature of CSSC is effective to control tissue inflammation and delay the onset of fibrosis, and a subsequent intrastromal CSK treatment deposited collagens and stromal specific proteoglycans to recover a native stromal matrix. Using optimized cell doses, our results showed that the effect of CSSC treatment for suppressing corneal opacities was augmented by an additional intrastromal CSK injection, resulting in better corneal clarity. These in vivo effects were substantiated by a further downregulated expression of stromal fibrosis genes and the restoration of stromal fibrillar organization and regularity. Hence, a combined treatment of CSSC and CSK could achieve a higher clinical efficacy and restore corneal transparency, when compared to a single CSSC treatment.     

Comparative study of electrocoagulation and electrochemical Fenton treatment of aqueous solution of benzoic acid (BA): Optimization of process and sludge analysis

Benzoic acid containing synthetic solution was pretreated by acid precipitation at various pH (1-3) and temperature (15-60 °C). Pre-treated solution was further treated by electrocoagulation (EC) and electrochemical Fenton (EF) processes using iron anode and graphite cathode. Optimization of independent operating parameters, namely, initial pH: (3-11), current density (A/m²): (15.24-76.21), electrolyte concentration (mol/L): (0.03-0.07) and electrolysis time (min): (15-95) for EC process and pH: (1-5), current density (A/m²): (15.24-76.21), H₂O₂ concentration (mg/L): (100-500) and electrolysis time (min): (15-95) for EF process, was performed using central composite design (CCD) in response surface methodology (RSM). Maximum removal efficiencies of BA- 76.83%, 88.50%; chemical oxygen demand (COD) - 69.23%, 82.21% and energy consumption (kWh/kg COD removed) - 30.86, 21.15 were achieved by EC and EF processes, respectively, at optimum operating conditions. It was found that EF process is more efficient than EC process based on removal of BA and COD with lower energy consumption. The sludge obtained after EC and EF treatments was analyzed by XRD, FTIR, DTA/TGA and SEM/EDX techniques.     

Influence of organic and inorganic compounds on oxidoreductive decolorization of sulfonated azo dye C.I. Reactive Orange 16

An isolated bacterial strain is placed in the branch of the Bacillus genus on the basis of 16S rRNA sequence and biochemical characteristics. It decolorized an individual and mixture of dyes, including reactive, disperse and direct. Bacillus sp. ADR showed 88% decolorization of sulfonated azo dye C.I. Reactive Orange 16 (100 mg L⁻¹) with 2.62 mg of dye decolorized g⁻¹ dry cells h⁻¹ as specific decolorization rate along with 50% reduction in COD under static condition. The optimum pH and temperature for the decolorization was 7–8 and 30–40 °C, respectively. It was found to tolerate the sulfonated azo dye concentration up to 1.0 g L⁻¹. Significant induction in the activity of an extracellular phenol oxidase and NADH–DCIP reductase enzymes during decolorization of C.I. Reactive Orange 16 suggest their involvement in the decolorization. The metal salt (CaCl₂), stabilizers (3,4-dimethoxy benzyl alcohol and o-tolidine) and electron donors (sodium acetate, sodium formate, sodium succinate, sodium citrate and sodium pyruvate) enhanced the C.I. Reactive Orange 16 decolorization rate of Bacillus sp. ADR. The 6-nitroso naphthol and dihydroperoxy benzene were final products obtained after decolorization of C.I. Reactive Orange 16 as characterized using FTIR and GC–MS.     

Pd/Fe3O4 supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C–C coupling and electrocatalytic application

The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supported-palladium nanoparticles enriched magnetic nanocatalyst (Pd/Fe₃O₄@C) using a simple multi-step process under aerobic conditions. Under mild reaction conditions, the Pd/Fe₃O₄@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates. Also, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction. Also, we explored the use of Pd/Fe₃O₄@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction. Interestingly, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite (Fe₃O₄ nanoparticles) with an overpotential of 293 mV at a current density of 10 mA·cm^–2.     

A Rapid,Micro FAME Preparation Method for Vegetable Oil Fatty Acid Analysis by Gas Chromatography

A 30-min, micro-base-catalyzed method for vegetable oil fatty acid methyl ester (FAME) preparation was developed using only 1 mg of oil sample by limiting the solvent volumes used. This method was primarily developed to quickly analyze fatty acid composition of CLA-rich soy oil but can be further applicable to pure vegetable oils. Existing base-catalyzed FAME preparation methods are not appropriate to use because they are either rapid but not micro, or micro but not rapid, or are rapid and micro but use acidification in the final step of FAME preparation, which would isomerize oils containing conjugated fatty acids. Serial dilutions of a mixed commercial FAME reference standard were prepared and analyzed by GC with a flame ionization detector (FID) with maximum instrument sensitivity. The novel method was also used to prepare soy oil FAMEs for GC-FID analysis. There were no statistically significant differences (P < 0.05) in fatty acid data from the FAME reference standard dilutions. Similarly, there was no statistical significant difference (P < 0.05) between results obtained for all the soy oil dilutions and the control method. This technique is a rapid method for preparing small pure oil samples as FAMEs for GC-FID analysis.     

Three-dimensional printing of triply periodic minimal surface structured scaffolds for load-bearing bone defects

The porous and cellular architecture of scaffolds plays a significant role in mechanical strength and bone regeneration during the healing of fractured bones. In this present study, triply periodic minimal surface (TPMS)-based gyroid and primitive lattice structures were used to design the cellular porous biomimetic scaffolds with different unit cell sizes (4, 5, and 6). The fused filament fabrication-based 3D printing technology was used for the fabrication of polylactic acid scaffolds. The surface morphology and mechanical compressive strength of differently structured scaffolds were observed using scanning electron microscopy and a universal testing machine. The unit cell size of 4 showed higher compressive strength in both gyroid and primitive structured scaffolds compared to unit cell sizes 5 and 6. Moreover, the gyroid structured scaffolds have higher compressive strengths as compared to primitive structured scaffolds due to the higher bonding surface area at the intercalated layers of the scaffold. Hence, the mechanical strength of scaffolds can be tailored by varying the unit cell size and cellular structures to avoid stress shielding and ensure implant safety. These TPMS-based scaffolds are promising and can be used as bone substitute materials in tissue engineering and orthopedic applications.