Advanced developments in the field of enzyme technology have increased the use of enzymes in industrial applications, especially in detergents. Enzymes as detergent additives have been extensively ...studied and the demand is considerably increasing due to its distinct properties and potential applications. Enzymes from microorganisms colonized at various geographical locations ranging from extreme hot to cold are explored for compatibility studies as detergent additives. Especially psychrophiles growing at cold conditions have cold-active enzymes with high catalytic activity and their stability under extreme conditions makes it as an appropriate eco-friendly and cost-effective additive in detergents. Adequate number of reports are available on cold-active enzymes such as proteases, lipases, amylases, and cellulases with high efficiency and exceptional features. These enzymes with increased thermostability and alkaline stability have become the premier choice as detergent additives. Modern approaches in genomics and proteomics paved the way to understand the compatibility of cold-active enzymes as detergent additives in broader dimensions. The molecular techniques such as gene coding, amino acid sequencing, and protein engineering studies helped to solve the mysteries related to alkaline stability of these enzymes and their chemical compatibility with oxidizing agents. The present review provides an overview of cold-active enzymes used as detergent additives and molecular approaches that resulted in development of these enzymes as commercial hit in detergent industries. The scope and challenges in using cold-active enzymes as eco-friendly and sustainable detergent additive are also discussed.
Interest in novel uses of biogas has increased recently due to concerns about climate change and greater emphasis on renewable energy sources. Although biogas is frequently used in low-value ...applications such as heating and fuel in engines or even just flared, reforming is an emerging strategy for converting biogas to syngas, which could then be used to obtain high-value-added liquid fuels and chemicals. Interest also exists due to the role of dry, bi-, and tri-reforming in the capture and utilization of CO2. New research efforts have explored efficient and effective reforming catalysts, as specifically applied to biogas. In this paper, we review recent developments in dry, bi-, and tri-reforming, where the CO2 in biogas is used as an oxidant/partial oxidant. The synthesis, characterization, lifetime, deactivation, and regeneration of candidate reforming catalysts are discussed in detail. The thermodynamic limitation and techno-economics of biogas conversion are also discussed.
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Energy Resources; Biocatalysis; Energy Storage
Virtual labs have proven to be very versatile and valuable for providing realistic experience for students in STE (Science, Technology, and Engineering) fields. As we progress from delivery of ...instructional material from classroom to the Internet, there is need to develop laboratory exercises to supplement the theoretical lessons. A Web-based virtual simulation model of an anaerobic digester (AD) using a flexible Javascript-based platform was developed to support courses in process control and process design. The objective was to provide a virtual laboratory experience that could be used on any device capable of accessing the Web (laptops, tablets, or smartphones) to explore multiple facets (design, operation, control, and optimization) associated with a complex biochemical system. A user-friendly interface that allows easy specification and testing of operational parameters is provided. In this article, we discuss how the model and simulation is developed and deployed along with illustrative examples of its use in a training or educational environment.
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•Zeolite shell can be used to control reactant selectivity.•Silicalite-1 shell caused diffusion limitations that vary with hydrocarbon size.•A 50 nm thick shell sufficient to wholly ...prevent reforming of heptane and toluene.•Optimum shell thickness established for hydrocarbons depending on GHSV.
The ability of a zeolite shell to enhance the selective conversion of hydrocarbons through diffusional limitations was investigated using a multi-scale model of a fixed-bed reactor. The impact of shell thickness and molecule/pore size on the catalytic performance of silicalite-1 zeolite encapsulated nickel catalyst pellets for steam reforming of C1-C7 hydrocarbons is reported. A reaction–diffusion model using kinetic expressions established in literature was employed. The model was verified through comparison with reported experimental results for steam reforming data over a temperature range of 748 – 1113 K and pressure of 1 – 10 bar. Comparisons are also made against experimental data for steam reforming in the presence of a zeolite shell. Evaluation of the Weisz-Prater criterion for both the core and encapsulated catalyst confirmed mass transfer limitation induced by the utilization of a zeolite shell. The model was used to suggest an optimal thickness that balances diffusional limitations imposed by the zeolite layer on methane versus that of the heavier hydrocarbons. The optimum thickness varied as a function of hydrocarbon size and shape which determined the diffusion rates. For toluene and heptane, a 50 nm thick shell was sufficient to wholly prevent reaction. Hydrocarbons like propane and butane required a shell 7.5 and 5 μm thick. Increasing the gas-hourly-space-velocity from 10,000 to 60,000 h-1 caused a decrease in the optimum shell thickness. This approach can be modified for application to other mixed hydrocarbon systems to predict optimal catalyst design.
The present study investigated the wound healing activity of Moringa oleifera leaf extract on an infected excision wound model in rats. Infection was induced using methicillin-resistant ...Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. An investigation was also done to study the effect of Moringa extract on the vascular endothelial growth factor (VEGF) and transforming growth factor-beta 1 (TGF-β1) gene expression in vitro using human keratinocytes (HaCaT). The methanol extract of M. oleifera leaves was analyzed for the presence of phytochemicals by LCMS. The antimicrobial activity of the extract was also determined. Wound contraction, days for epithelization, antioxidant enzyme activities, epidermal height, angiogenesis, and collagen deposition were studied. M. oleifera showed an antimicrobial effect and significantly improved wound contraction, reduced epithelization period, increased antioxidant enzymes activity, and reduced capillary density. Effect of the extract was less in wounds infected with P. aeruginosa when compared to MRSA. The VEGF and TGF-β1 gene expression was increased by M. oleifera.
Methicillin-resistant
(MRSA) is one of the leading causes of infection worldwide. Clove oil's ability to inhibit the growth of MRSA was studied through in vitro and in vivo studies. The phytochemical ...components of clove oil were determined through gas chromatography-mass spectrometry (GC-MS) analysis. The antibacterial effects of clove oil and its interaction with imipenem were determined by studying
, MBC, and
indices in vitro. The in vivo wound-healing effect of the clove oil and infection control were determined using excision wound model rats. The GC-MS analysis of clove oil revealed the presence of 16 volatile compounds. Clove oil showed a good antibacterial effect in vitro but no interaction was observed with imipenem. Clove bud oil alone or in combination with imipenem healed wounds faster and reduced the microbial load in wounds. The findings of this study confirmed the antibacterial activity of clove oil in vitro and in vivo and demonstrated its interaction with imipenem.
Lipases are glycerol ester hydrolases that catalyze the hydrolysis of triglycerides to free fatty acids and glycerol. Lipases catalyze esterification, interesterification, acidolysis, alcoholysis and ...aminolysis in addition to the hydrolytic activity on triglycerides. The temperature stability of lipases has regarded as the most important characteristic for use in industry. Psychrophilic lipases have lately attracted attention because of their increasing use in the organic synthesis of chiral intermediates due to their low optimum temperature and high activity at very low temperatures, which are favorable properties for the production of relatively frail compounds. In addition, these enzymes have an advantage under low water conditions due to their inherent greater flexibility, wherein the activity of mesophilic and thermophilic enzymes are severely impaired by an excess of rigidity. Cold-adapted microorganisms are potential source of cold-active lipases and they have been isolated from cold regions and studied. Compared to other lipases, relatively smaller numbers of cold active bacterial lipases were well studied. Lipases isolated from different sources have a wide range of properties depending on their sources with respect to positional specificity, fatty acid specificity, thermostability, pH optimum, etc. Use of industrial enzymes allows the technologist to develop processes that closely approach the gentle, efficient processes in nature. Some of these processes using cold active lipase from
C. antarctica have been patented by pharmaceutical, chemical and food industries. Cold active lipases cover a broad spectrum of biotechnological applications like additives in detergents, additives in food industries, environmental bioremediations, biotransformation, molecular biology applications and heterologous gene expression in psychrophilic hosts to prevent formation of inclusion bodies. Cold active enzymes from psychrotrophic microorganisms showing high catalytic activity at low temperatures can be highly expressed in such recombinant strains. Thus, cold active lipases are today the enzymes of choice for organic chemists, pharmacists, biophysicists, biochemical and process engineers, biotechnologists, microbiologists and biochemists.
TiO2 is one of the most promising candidate materials for clean-energy generation and environmental remediation. However, the larger-than 3.1 eV bandgap of perfectly crystalline TiO2 confines its ...application to the ultraviolet (UV) range. In this study, the electronic and the optical properties of undoped mixed-phase TiO2 nanoparticles were investigated using UV and inverse photoemission, low intensity X-ray photoelectron (XP), and diffused reflectance spectroscopy methods. The facile solution-phase synthesized nanoparticles exhibited a midgap-states-induced energy gap of only ∼2.2 eV. The diffused reflectance spectrum showed sub-bandgap absorption due to the existence of a large Urbach tail at 2.2 eV. The UV photoemission spectrum evidenced the presence of midgap states. The 2.2 eV energy gap enables the nanoparticles to be photoactive in the visible energy range. The gas-phase CO2 photoreduction test with water vapor under visible light illumination was studied in the presence of the synthesized TiO2 nanoparticles which resulted in the production of ∼1357 ppm gr–1 (catalyst) CO and ∼360 ppm gr–1 (catalyst) CH4, as compared to negligible amounts using a standard TiO2 (P25) sample. The synthesized nanoparticles possessed a Brunauer–Emmett–Teller (BET) surface area of ∼131 m2 gr–1, corresponding to a Langmuir surface area of ∼166 m2 gr–1. The determined interplanar distances of atomic planes by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) methods were consistent. A detailed elemental analysis using XPS and inductively coupled plasma mass spectrometry (ICP-MS) demonstrated that the synthesized catalyst is indeed undoped. The catalytic activity of the undoped synthesized nanoparticles in the visible spectrum can be ascribed to the unique electronic structure due to the presence of oxygen vacancy related defects and the high surface area.
The purpose of this study was to analyze the correlation of occupancy ratio (OR) and fatty infiltration (FI) to functional outcome and retear rate following rotator cuff repair by single-row ...technique.
Retrospectively, all the patients (n = 100) with rotator cuff tear were evaluated preoperatively and postoperatively with functional scores (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form ASES, University of California–Los Angeles UCLA shoulder score, Constant score) and magnetic resonance imaging (MRI) for OR and FI. Two observers studied the MRI data separately. Statistical analysis was done using SPSS (version 16), paired t test, Pearson correlation, and intraclass correlation coefficients.
The mean (± standard deviation) follow-up was 16.24 ± 6.39 months, and the mean age was 56.18 ± 7.5 years. There was a significant increase in muscle atrophy (decreased OR) and FI (P < .01). The mean preoperative and postoperative ORs were 0.57 and 0.51, respectively. However, the mean functional scores improved significantly for ASES (55.78 to 82.09), UCLA (19.44 to 28.47), and Constant score (49.73 to 75.07) (P < .001). There was no significant difference in functional outcome among the different stages of FI (ASES P = .341, UCLA P = .839, Constant P = .376). Seven patients had asymptomatic retear during follow-up, of which 2 patients had grade 3, 4 patients had grade 2, and 1 patient had grade 1 FI, preoperatively.
Muscle atrophy and FI are irreversible phenomena and continue even after successful repair; however, they do not have a significant influence on the functional outcome at short-term follow-up after cuff repair. Repairing cuff with higher grades of FI can be performed as they achieve significantly improved functional outcomes.
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•PEI modified inertresins perform well in CO2 separation from biogas.•CO2-amine reaction on resin sorbent is zwitterionic in nature and reversible.•Water promotes CO2 adsorption on ...the PEI impregnated resin-based sorbent.•The sorbent can be regenerated at 100 ⁰C and stable for several working cycle.•Economic feasibility study shows biogas upgrading via this technology is promising.
The separation of CO2 from biogas to achieve vehicle/pipeline grade methane is an expensive step. Recently, PEI (polyethyleneimine) impregnated resins have been proposed and evaluated for CO2 separation from flue gases and air. However, its use in biogas upgrading and evaluation of the economic feasibility of such adsorbents have not been explored in detail. In this work, by modifying an inert polymeric resin (HP2MGL) using PEI, CO2 was separated from biogas. The sorbent exhibited the highest adsorption capacity of 2.7 mmolCO2/gads at 30% PEI loading, increasing to 2.9 mmolCO2/gads in the presence of moisture, and remained stable for up to five adsorption–desorption cycles. In situ DRIFTS studies showed that CO2 adsorption on PEI-impregnated sorbent is consistent with the zwitterion reaction mechanism, and the sorbent could be regenerated completely at 100 °C. The upgrading cost of biogas is primarily dominated by the operating cost of regeneration and the adsorbent cost. The economic feasibility analysis suggests that PEI-impregnated resin sorbent requires less capital and operating costs than conventional biogas upgrading technologies. Therefore, PEI-impregnated polymeric resins are promising for CO2 separation from biogas.
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