Mechanistic Modeling of Size Exclusion Chromatography-Assisted In Vitro Refolding of the Recombinant Biosimilar Teriparatide (PTH-34).

In vitro protein refolding is one of the critical unit operations in manufacturing recombinant peptides expressed using Escherichia coli as host cells. This study is focused on designing size exclusion chromatography-assisted in vitro refolding process for biosimilar recombinant parathyroid hormone. Inclusion bodies (IBs) of recombinant parathyroid hormone were solubilized at higher pH, and in vitro refolding was performed using size exclusion chromatography. In the first part of the investigation, DoE-based empirical optimization was performed to achieve a higher refolding yield for a biosimilar recombinant parathyroid hormone. The effect of solubilized inclusion body (IB) feed volume, concentration of IBs, and residence time on in vitro refolding of recombinant teriparatide was studied using the Box-Behnken design. Size exclusion chromatography (SEC)-assisted in vitro refolding was performed at 8 °C at pH 10.5 by using 20 mM Tris buffer. The maximum refolding yield of 98.12% was achieved at feed volume (12.5% of CV) and 20 mg/mL inclusion body (IB) concentration with a residence time of 50 min and a purity of 66.1% based on densitometric analysis using SDS-PAGE. In the latter part of the investigation, the general rate mechanistic model framework for size exclusion chromatography was developed and validated with the experimental results. The developed model helped in the accurate prediction of the elution volumes and product yield. The developed model also helps to predict the elution performance of a scalable column a priori. Post in vitro refolding, the formation of the native peptide structure was examined using various orthogonal analytical tools to study the protein's primary, secondary, and tertiary structures. The developed hybrid process development approach is a valuable tool toachieve high-yield, scalable refolding conditions for recombinant proteins without disulfide bonds.

Thermo-kinetic Study of Genetically Different Carbon-Source Materials.

A nonisothermal thermogravimetric analysis (TGA) technique was applied to determine the devolatilization kinetic parameters of completely different genesis samples of four groups: coal, biomass, lignite, and petcoke. The physical and chemical characteristics were determined using the proximate and ultimate analysis and the ash composition profile using the X-ray fluorescence method. Heating rates of 10, 15, and 20 °C/min were used in the temperature range of 25-1000 °C during the slow pyrolysis under an inert gas atmosphere. A widely used and proposed first-order Coats-Redfern kinetic model was applied, which showed the highest values of activation energies (Ea) for the petcoke sample from 57.17 to 67.58 kJ/mol at three different heating rates, while the lignite sample represented the lowest Ea values between 12.84 and 16.03 kJ/mol. The thermo-kinetic behavior was explained based on the catalytic effect of the ash composition profile, morphology, and structure of the substances determined using different analytical techniques. For the TGA process, the application of scanning electron microscopy, Fourier-transform infrared spectroscopy, etc., for the physiochemical analysis of the four genetically different carbon-source materials represented the novelty of the present work.

Applied mineralogical investigation on coal gasification ash.

This work aims to perform the applied mineralogical characterization of coal gasification ash (CGA) generated from a commercial fixed bed downdraft gasification plant in eastern India. Analytical and characterization techniques such as stereomicroscopy, optical microscopy, field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) attached, X-ray fluorescence (XRF), energy dispersive x-ray spectrometer associated scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were applied for analyzing the coal and the corresponding gasification ash sample. These analytical techniques illustrate that SiO2 and Al2O3 are the major gasification ash phases, accounting for almost 85% of the entire CGA composition. The dominant mineral phases, such as quartz, mullite, and other aluminosilicates, provide an opportunity for utilization in construction and refractory material manufacturing. Moreover, confirming the presence of rare and valuable earth elements (RVEEs) in the CGA sample with SEM-EDX analysis unearths a new application window in meeting the requirement of the RVEEs starved nation like India, where very few commercial-scale coal gasification units are operational.

Hydrothermal carbonization of household wet waste - characterization of hydrochar and process wastewater stream.

In the present study, household wet waste (HWW) pretreatment was explored using hydrothermal carbonization (HTC) to enhance resource recovery opportunities. The pretreatment was performed at 200 °C for 1-8 h duration in a 2 L high pressure reactor. After HTC, the recovered solid hydrochar (HC) showed high calorific value of âˆ¼ 27 MJ/kg compared to 18 MJ/kg of HWW. Moreover, it contained significant amount of oxygen containing acidic functional groups, hence the waste derived HC may also be utilized as adsorbent in wastewater treatment and soil conditioner. The process wastewater (PW) contained several value-added organics including proteins and furfurals. The HTC reaction kinetics showed the conversion of HWW to primary HC as the fastest step (rate constant = 0.0126 min-1). Moreover, the biochemical methane potential test on PW revealed generation of significant amounts of biogas with 55-75% methane. The total energy production from HC and PW was estimated as âˆ¼ 3.3 MJ/kg of HWW.

Investigation on hydrochar and macromolecules recovery opportunities from food waste after hydrothermal carbonization.

In this paper, the performance of hydrothermal carbonization (HTC) was investigated on real food waste (FW) to improve resource recovery opportunities. The HTC was performed in a high pressure batch reactor (without addition of water) at desired temperatures for different durations to study the properties of solid hydrochar (HC) and process water (PW) produced during the process. The reaction temperature and run time of 200 °C and 1 h, respectively were found suitable to produce the HC (high heating value = ~30 MJ/kg) having properties similar to that of the peat/lignite coal. Moreover, durable pellets could also be prepared from HC without addition of binder. The kinetic constants for HC combustion were also predicted using non-isothermal model-free approach for the data obtained from thermo-gravimetric analysis. In the PW samples recovered after HTC, several value-added compounds like 2,5-hydroxymethyl furfural, humic-like substances (HLS), proteins, carbohydrates and volatile fatty acids could be detected in appreciable quantities. However, longer reaction resulted in further degradation of above macromolecules into VFAs. Based on the observations, a pathway for FW degradation during HTC process is proposed. Moreover, the HLS and proteins mixture recovered from the PW sample exhibited no adverse impact on seed growth. The present study demonstrates that the HTC can be a potential treatment method for FW to recover a variety of useful materials. Further studies should focus on developing cost-effective methods for the recovery of various macromolecules from PW.

Effect of sodium hydrosulphite treatment on the quality of non-centrifugal sugar: Jaggery.

Jaggery is a non-centrifugal sweetener produced by thermo-chemical treatments of sugarcane juice. The traditional practices involved in making jaggery are usually tailored using chemicals to meet consumer requirements. Sodium hydrosulphite (hydros) is a commonly employed chemical in the jaggery industry to improve its colour. This article presents a comparative study of jaggery made with and without hydros treatments. The differences in properties, such as sorption behaviour, colour, polyphenols, flavonoids, minerals, and sulphur dioxide content, were measured. Hydros-treated jaggery was found to be brighter in colour with a lower browning index by 5-10. SO2 content of hydros-treated jaggery was >70 ppm, while minerals, polyphenols, and flavonoids were less abundant compared to control jaggery, thereby compromising overall quality. Based on the experiments carried out, the optimum treatment of hydros can be employed to satisfy consumer demand while producing an acceptable quality of jaggery that conforms to norms.

Effects of acid treatment in jaggery making.

The jaggery-making process involves various thermo-chemical treatments of sugarcane juice. As jaggery making is a traditional practice, knowledge about the use of different chemicals in the process is transferred from generation to generation without much scientific understanding. Phosphoric acid is one of the chemicals commonly used in this process. We have investigated its effect through systematic experiments. The addition of acid causes inversion of sucrose, which beyond a certain point is not desirable for good quality jaggery. In the correct proportions, however, phosphoric acid improves the colour and texture of jaggery and helps in the formation of smaller sized crystals. Reducing sugars formed due to inversion hinder crystal growth, resulting in relatively small crystals. In our experiments, the average crystal size reduced from 22.22 µm to 14.34 µm. Acid-treatedjaggery was found to equilibrate at higher moisture. A comparison with normal jaggery is thus provided for its keeping quality.

A semi-empirical approach towards predicting producer gas composition in biomass gasification.

The paper provides a comparison of five distinct models, often used in thermodynamic equilibrium modeling that allows the study of feedstock effect on gasification process. The five models were thus formulated and solved using MATLAB software. The results were compared with published experimental data. The model based on equilibrium constant derived using methane formation reaction and water gas shift reaction showed comparatively better performance. Once the model was selected, the response surface analysis was employed to predict the parameters, such as reactor temperature and feedstock moisture content, for a maximum heating value of the producer gas. Simulations were performed for 50 different biomass feedstocks and simplified correlations were developed from simulated producer gas composition using multiple linear regression. These correlations may be suited for the quick comparison of different feedstocks in gasification process.

Co-gasification of high ash biomass and high ash coal in downdraft gasifier.

The present work studies gasification of high ash biomass (20-25% w/w), high ash coal (30-35% w/w), and their co-gasification in a downdraft gasifier developed in our earlier study (Siddiqui et al., 2018). TGA studies were performed to examine the change in performance due to the catalytic effect of inorganic content. The effect of biomass ratio (BR) was examined. Higher percentage of biomass increased the conversion to gas on carbon basis, and decreased the conversions to char and tar. The presence of coal enhanced the temperature and hence the rates of the reactions to certain extent. The respective cold gas and thermal efficiencies for BR0 are 33.06% and 49.38%, and for BR1 are 52.22% and 64.15%. BR0.75 gave the best performance with CGE of 57.5% and thermal efficiency of 72.63%. Finally, the clinker formation issue and the preliminary atmospheric emissions measurements are reported for gasifier.

Revamping downdraft gasifier to minimize clinker formation for high-ash garden waste as feedstock.

The conventional downdraft gasifier, when used with garden waste pellets (ash ∼10%) as feedstock, exhibits formation of clinker due to hardening of softened ash, which results in discontinuous flame and intermittent operation. The design and operation protocol of the gasifier was appropriately modified to circumvent this problem. The effects of parameters such as grate movement, equivalence ratio (ER), and ratio of air entering at combustion and drying zones (split ratio) were systematically studied to maximize the lower heating value (LHV) of gas and minimize the amount of clinker. The grate movement of once in 20 min, ER of 0.32, and air split ratio of 0:100 together proved to be the best for garden waste pellets. The producer gas LHV and cold gas efficiency were 3.59 MJ/Nm3 and 62.61%, respectively, and comparable to the producer gas obtained from other biomass resources such as rice husk, wheat straw, and cotton stalks.

CO2 gasification of char from lignocellulosic garden waste: Experimental and kinetic study.

In this study, the dry leaves litter from jackfruit, raintree, mango and eucalyptus trees, lignin, and cellulose were characterized, pyrolysed, and evaluated for their char reactivity towards CO2 gasification using TGA. The differences in char reactivity were attributed to the difference in char morphology and the varying inorganic contents. The mineral analysis of biomass ash showed the presence of alkali minerals some of which could act as catalysts. The adverse effect of high silica content was also evident through the experimental results. The kinetic parameters for gasification reaction were determined using three different reaction models. A modified random pore model was investigated to account for the influence of inorganic content. The effect of external catalyst on CO2 gasification was also studied by adding potassium carbonate to biomass char and pellets. The results obtained from this study can be conveniently used in the design of a gasifier for lignocellulosic garden waste.