Biosynthesis of AgNPs using aqueous leaf extract of Ipomoea eriocarpa and their anti‐inflammatory effect on carrageenan‐induced paw edema in male Wistar rats

Silver nanoparticles (AgNPs) were synthesised from aqueous Ag nitrate through a simple, competent and eco‐friendly method using the leaf extract of Ipomoea eriocarpa as reducing as well as capping agent. Ultraviolet–visible absorption spectroscopy was used to confirm the formation of AgNPs which displayed the substantiation of surface plasmon bands at 425 nm. The NPs were also characterised using Fourier transformer infrared spectroscopy, X‐ray diffraction method, transmission electron microscope and zeta potential. The characterisation study confirmed the formation of AgNPs, their spherical shape and average diameter of 12.85 ± 8.65 nm. Zeta potential value of −20.5 mV suggested that the AgNPs are stable in the suspension. The aqueous extract and the AgNPs were further screened for in vivo anti‐inflammatory activity using carrageenan‐induced paw edema in male Wistar rats. The study demonstrated that the AgNPs (1 ml kg⁻¹) had a significant (p  < 0.05) anti‐edemic effect and inhibition was observed from the first hour (21.31 ± 1.34) until the sixth hour (52.67 ± 1.41), when the inhibitory effect was greatest and superior to the aqueous extract and the standard, diclofenac.Inspec keywords: silver, nanoparticles, nanofabrication, ultraviolet spectra, visible spectra, absorption coefficients, surface plasmons, Fourier transform infrared spectra, X‐ray diffraction, transmission electron microscopy, suspensions, drugs, nanomedicineOther keywords: biosynthesis, aqueous leaf extract, ipomoea eriocarpa, antiinflammatory effect, carrageenan‐induced paw edema, male Wistar rats, silver nanoparticles, aqueous nitrate, capping agent, ultraviolet‐visible absorption spectroscopy, surface plasmon band, Fourier transformer infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, zeta potential, spherical shape, suspension, aqueous extract, in vivo antiinflammatory activity, antiedemic effect, inhibitory effect, diclofenac, wavelength 425 nm, size 12.85 nm to 8.65 nm, Ag     

Microemulsion synthesis of silver nanoparticles using biosurfactant extracted from Pseudomonas aeruginosa MKVIT3 strain and comparison of their antimicrobial and cytotoxic activities

In the present study, an efficient biosurfactant producing bacterial strain Pseudomonas aeruginosa MKVIT3 was isolated from an oil logging area in Vellore district of Tamil Nadu, India. Liquid chromatography–mass spectrometry (LC‐MS/MS) analysis was performed for the identification of different congeners present in the extracted biosurfactant. The column purified biosurfactant was used to stabilise the formation of silver nanoparticles (NP) using borohydrate reduction in reverse micelles. The silver NP were characterised using UV‐vis absorption spectroscopy, Powder‐XRD TEM analysis and zeta potential. A comparative study of the antimicrobial activity and cytotoxic efficacy was done for the extracted purified biosurfactant and the silver NP. The LC‐MS/MS analysis of the biosurfactant revealed the presence of five rhamnolipid congeners. The synthesised silver NP showed the characteristic absorption peak in UV‐vis at 440 nm. Powder‐XRD and TEM analysis revealed the average particle size of the NP as 17.89 ± 8.74 nm as well as their cubic structure. Zeta potential value of −30.9 mV suggested that the silver NPs are stable in the suspension. Comparative study of the antimicrobial activity revealed that the silver NP are more potent than the biosurfactant in inhibiting the growth of microbes. Cytotoxic activity revealed that the biosurfactant are more effective than the synthesised silver NP.Inspec keywords: microemulsions, silver, nanoparticles, nanomedicine, cellular biophysics, surfactants, microorganisms, chromatography, mass spectroscopic chemical analysis, ultraviolet spectra, visible spectra, antibacterial activityOther keywords: Ag, microemulsion synthesis, silver nanoparticles, Pseudomonas aeruginosa, MKVIT3 strain, antimicrobial activities, cytotoxic activities, biosurfactant producing bacterial strain, oil logging area, Vellore district, Tamil Nadu, India, liquid chromatography–mass spectrometry, LC‐MS/MS analysis, extracted biosurfactant, column purified biosurfactant, borohydrate reduction, reverse micelles, UV‐vis absorption spectroscopy, powder‐XRD TEM analysis, zeta potential, antimicrobial activity, cytotoxic efficacy, extracted purified biosurfactant, rhamnolipid congeners     

Recycling of Bakery Waste as an Alternative Carbon Source for Rhamnolipid Biosurfactant Production

Production of a rhamnolipid biosurfactant (RBS) using discarded mixed bakery waste (BW) employing bacterial strain Pseudomonas aeruginosa strain PG1 (identified by 16 s rDNA sequencing) was investigated for bioconversion of the food waste. Dry and powder form BW was supplemented with mineral salt media (MSM) as a sole carbon source for production of RBS. RBS production was measured based on the drop collapse assay and surface tension (ST) reduction of the culture media. Production of RBS in the culture media was enhanced by optimizing the carbon source (BW) concentration and the proper nitrogen source along with the pH of the MSM. Under optimized culture conditions, 11.56 g L⁻¹ day⁻¹ crude biosurfactant (BS) was achieved. The RBS had the ability to reduce the ST of the optimized MSM from 72.0 to 25.8 mN m⁻¹ during culture, where the critical micelle concentration (CMC) of the biosurfactant was found to be 100 mg L⁻¹. Liquid Chromatography Mass Spectroscopy (LC-MS), Fourier Transform Infrared spectroscopy (FTIR), and scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy (EDS) analyses of the purified BS confirmed that it is of rhamnolipid in nature and it is made up of both monorhamnolipid and dirhamnolipid congeners. Furthermore, the RBS did not express any cytotoxic effect on the cell line of mouse L292 fibroblastic cell indicating the biosafety nature of the high-value biomolecule.     

Antimicrobial activity of silver nanoparticles synthesised by using microbial biosurfactant produced by a newly isolated Bacillus vallismortis MDU6 strain

Microbial biosurfactants has evolved as green molecules and their chemical diversity has gained momentum in recent time not only in the field of environmental and industrial sectors but also in the pharmaceutical sector. In this study, an effort was made for the biosynthesis of silver nanoparticle (AgNPs) having antimicrobial and non‐cytotoxic activities with the help of microbial biosurfactant extracted from a novel Bacillus vallismortis strain MDU6 (Genbank accession no. {"type":"entrez-nucleotide","attrs":{"text":"MH382951","term_id":"1546647362"}}MH382951) from petroleum oil logged soil sample in Dibrugarh, Assam. The isolate shows excellent potential for the production of biosurfactant by reducing the surface tension of diesel supplemented medium up to 56.57% only within 5 days. FTIR spectra of the crude biosurfactant show the presence of ʋ _CH2 (asymmetric stretching), ʋ _CH2 (symmetric stretching), ʋ _C=C (stretch), ʋ _C−C (stretch), ʋ _C−H (bending), ʋ _C−O (stretch) and ʋ _C−H (bending) functional groups and LC‐MS/MS analysis confirms it as a cyclic lipopeptide which is a mixture of surfactin and iturin. The synthesized AgNPs showed excellent antimicrobial activities against Escherichia coli (ATCC no. 25922), Listeria monocytogenes (ATCC No. BAA‐751), Staphylococcus aureus (ATCC No. 9542) and Bacillus subtilis (ATCC no. 6051) and showed no cytotoxicity against primary mouse liver cell lines.Inspec keywords: nanoparticles, molecular biophysics, silver, liver, nanofabrication, microorganisms, petroleum, biotechnology, antibacterial activity, surfactants, cellular biophysics, toxicology, surface tension, nanomedicine, Fourier transform infrared spectraOther keywords: C−H functional groups, bending, synthesised AgNPs, excellent antimicrobial activities, ATCC no, bacillus subtilis, antimicrobial activity, silver nanoparticles, bacillus vallismortis MDU6 strain, microbial biosurfactants, green molecules, chemical diversity, environmental sectors, industrial sectors, pharmaceutical sector, noncytotoxic activities, petroleum oil, soil sample, isolate, surface tension, crude biosurfactant show, asymmetric stretching, symmetric stretching, Genbank accession no. {"type":"entrez-nucleotide","attrs":{"text":"MH382951","term_id":"1546647362"}}MH382951, time 5.0 d, Ag     

GIS-Based Estimation of Soil Loss from Hilly Urban Area Incorporating Hill Cut Factor into RUSLE

Unplanned residential development in hilly areas leads to steep cuts in natural hillslopes, which in turn, results in excessive soil loss. GIS-based Revised Universal Soil Loss Equation (RUSLE), applied in such a case, underestimates soil loss since such near vertical surfaces are not completely projected in orthorectified satellite images. This paper introduces a "hill cut factor (H_f)", which is input into the cover management factor of RUSLE model. Model is validated with observed soil loss data of a mini hilly urban watershed located in Japorigog hill of Guwahati city. GIS-based soil loss estimation has been carried out for two scenarios: with and without consideration of H_f. Results reveal that consideration of H_f in GIS-based RUSLE replicates the picture of erosion more accurately and gives a similar result with observed soil loss data. Without consideration of H_f, RUSLE underestimates annual soil loss from the studied watershed by almost 28% than the observed value. Adequate design of drainage system by using more accurate soil loss information, derived in this way, can lower the urban flood problem caused due to blockage of drains and culverts with sediments brought down from the inhabited hills in a city.     

Formulation development and accelerated stability testing of a novel sunscreen cream for ultraviolet radiation protection in high altitude areas

The present study is aimed at the development of a sunscreen cream for use in high altitude areas which have been found to possess superior sun protection factor (SPF) along with remarkable antioxidant activity. The topical formulation is a standard oil-in-water emulsion of a combination of United States Food and Drug Administration (US FDA) approved ultraviolet filters; along with melatonin and pumpkin seed oil. The in-silico optimized formulation was characterized using established methods and the stability study was carried out as per International Conference on Harmonization guidelines. The formulation was prepared after requisite pre-formulation analysis by Fourier-transform infrared spectroscopy, differential scanning calorimetric and thermogravimetric analyses; followed by characterization based on color, odor, phase separation, spreadability, specific gravity, homogeneicity, centrifugation and sensitivity. For the stability study, a total of three samples from three batches of the finished product were subjected to the stability study. The samples were analyzed for content uniformity, pH, in vitro SPF, rheology, zeta potential, droplet diameter and microbial analysis of the 0th day and also the the end of the storage period. Results obtained from the stability study indicated that the formulation possesses 50+ in vitro SPF value and remained stable for 6?months and 12?months under storage at 40?±?2?°C and 75?±?5% relative humidity; and ?20?°C?±?5?°C respectively.     

Thermoelectric conversion of waste heat from IC engine‐driven vehicles: A review of its application,issues, and solutions

Thermoelectric generator (TEG) is a promising thermoelectric (TE) conversion technology to effectively recover and convert waste heat from vehicle exhaust into useful energy, ie, electricity. Exhaust TEG (ETEG) is a system that is incorporated into the exhaust manifold of a vehicle. Exhaust TEG comprises of a heat exchanger, TEG modules, heat sink, and power conditioning unit. The present work reviews different vehicular ETEGs based on engine type, engine‐rated power, type and number of TEG module, efficiency of ETEG and TEG, exhaust and coolant temperature, and power output of ETEG . In addition to these, the technical issues faced in these ETEGs are addressed under 2 categories, viz., primary (TEG with low ZT TE material and inefficient heat exchanger and heat sink) and secondary issues (low operating temperature TEG modules and installation position of ETEG). In addition to it, effects of vibration and thermal cycling of exhaust system on TEG modules that may arise in ETEG are also discussed. A review of preventive solutions to the issues is also presented. Finally, the economic aspects of an ETEG are also discussed. The review highlights the need of commercialization of TE materials with ZT > 2, high‐temperature operating range, and segmented TEG modules in large volumes so that their practice can be extended in vehicular applications. Heat exchanger modeling using computational fluid dynamics and interfacing with heat transfer theory is essential to maintain temperature uniformity across the TEG modules. Installation of ETEG in the exhaust pipe should be such that it does not affect the performance of the engine. It is also realized that sturdy TEG modules should be developed for long‐term operation to prevent degradation due to mechanical vibration and thermal cycling of the vehicle. Further, ETEG is economically beneficial in vehicles such as trucks owing to availability of high thermal energy in their exhaust stream.     

A Revision of OPTEMP-LS Model for Selecting Optimal EMP Combination for Minimizing Sediment and Water Yield from Hilly Urban Watersheds

Water Resources Management - Hilly watersheds are inherently susceptible to more sediment and water yield. Urban developments in hills cause conversion of the natural sloppy surface to bare steep...     

Achieving the Best Yield in Glycolipid Biosurfactant Preparation by Selecting the Proper Carbon/Nitrogen Ratio

Pseudomonas aeruginosa RS29, the native biosurfactant-producing strain isolated from the oil fields of Assam, India was used to investigate the influence of the carbon nitrogen ratio on production of the biosurfactant. The biosurfactant producing ability of the strain was measured based on surface tension (ST) reduction of the culture medium and the emulsification (E24) index. Production was greatly influenced by the sources of nitrogen and carbon as well as the carbon to nitrogen (C/N) ratio. Sodium nitrate was the best nitrogen source and the water miscible carbon source, glycerol was observed as the best carbon source for maximum biosurfactant production. The C/N ratio 12.5 allowed the maximum production of biosurfactant by the RS29 strain. At this C/N ratio, 55 % ST of the culture medium was reduced by the produced biosurfactant. Concentrations of crude and rhamnolipid biosurfactant obtained at this particular C/N ratio were 5.6 and 0.8 g/l respectively. The RS29 strain was novel as it was able to produce a sufficient amount of biosurfactant utilizing a much lower amount of the water miscible carbon source, glycerol. Extraction of the biosurfactant by a chloroform–methanol (2:1) mixture was the best method to obtain the highest biosurfactant from the culture medium of the strain. The biosurfactant was confirmed as a mixture of mono and di-rhamnolipid congeners, Rha–C₁₀–C₁₀–CH₃ being the most abundant one. The biosurfactant was a good foaming and emulsifying agent.