VACCUM DRYING CHARACTERISTICS OF COCONUT

The drying characteristics of shredded coconut under vacuum and at atmospheric pressure have been studied. It was found that a decrease in the absolute pressure within the drying compartment retarded the drying rate of coconut. A model for drying of coconut is proposed on the assumption that the surface of coconut is partially covered with layers of moisture and oil. It was found that oil seepage to surface was responsible for lower drying rates at low absolute vacuum pressures within the dryer.     

Electrochemical and <Emphasis Type="Italic">in situ</Emphasis> spectroelectrochemical studies of gold nanoparticles immobilized Nafion matrix modified electrode

Electrochemical and in situ spectroelectrochemical behaviours of phenosafranine (PS⁺) were studied at the gold nanoparticles (Au_Nps) immobilized Nafion (Nf) film coated glassy carbon (GC) and indium tin oxide (ITO) electrodes. Cyclic voltammetric studies showed that the PS⁺ molecules strongly interact with the Au_Nps immobilized in the Nf matrix through the electrostatic interaction. The presence of Au_Nps in the Nf film improved the electrochemical characteristics of the incorporated dye molecules. The emission spectra of Nf-Au_Nps-PS⁺ films showed that the incorporated PS⁺ was quenched by Au_Nps and it could be explained based on the electronic interaction between the Au_Nps and PS⁺ molecules. The in situ spectroelectrochemical study showed an improved electrochemical characteristic of the incorporated PS⁺ molecules at the ITO/Nf-Au_Nps electrode when compared to the ITO/Nf electrode.     

Structural, optical, and magnetic characterization of Co and N co-doped ZnO nanopowders

Co and N co-doped ZnO nanopowders with Co and N concentration 4, 6, and 8 mol% were synthesized by sol–gel method. Powder X-ray diffraction reveals that Co and N co-doped ZnO crystallize in wurtzite structure having space group C _6v . Photo-luminescence studies show the reduction in band gap with increase in concentration of dopants. Micro Raman studies show the red shift for 1LO phonon peak with increase in doping, generally credited to the stress caused by lattice mismatch due to N doping in ZnO. X-ray absorption spectroscopy reveals that Co replaces the Zn atoms and N replace the O atoms in the host ZnO lattice. Magnetic studies show that Co and N co-doped ZnO nanopowders exhibit ferromagnetic character at room temperature.     

Synthesis and Pyrolysis-Field Ionization Mass Spectrometric Study of an Aromatic Polyamide Having Azo Group in the Main Chain

The reductive coupling of p-nitrobenzoic acid with glucose solution gave 4,4′-azodibenzoic acid and was converted to 4,4′-azodibenzoylchloride using thionyl chloride. This aromatic diacid chloride was condensed with 4,4′-Diaminodiphenyl ether by two different techniques to yield aromatic polyamide. The low temperature polymerization method resulted in comparatively high molecular weight polymer as evidenced by intrinsic viscosity values. The structure of the material was confirmed by IR studies. Detailed pyrolysis-field ionization mass spectral studies carried out indicated two major degradations. In the temperature region (180–200°C), the mass spectrum showed intense peaks at m/z = 166 and 149 which can be explained from the fragmentation of azodicarboxylic acid formed from the polymer. The mass spectrum recorded at 465°C gave clear proof for the structure of the polyamide and also enough evidence was noted for the hydrogenation of the azo group during pyrolysis.     

Color Kinetics During Ripening of Indian Mangoes

During ripening of mangoes, color change kinetics were studied with Alphonso, Banganapalli, and Neelam varieties. The internal and external color change was recorded using CIE-Lab color coordinates. L, a, b, and total color difference (ΔE) values were measured for internal pulp and external peel during the ripening period. Four kinetic models viz. zero order, first order, fractional conversion, and logistic models were used for modeling using MATLAB. Among the explored models, the logistic model was found to be more suitable to predict the changes in all external color coordinates in all the three varieties. Internal color coordinates of different varieties were exhibited contrasting behavior. So different kinetic models were proposed to predict the internal color change for different variety. The fractional conversion model was found to be not suitable in color change kinetics during ripening of mango.     

INVESTIGATION ON MAMMOGRAPHIC IMAGE COMPRESSION AND MICROCALCIFICATION ANALYSIS USING MULTIWAVELETS AND NEURAL NETWORKS

In digital mammography, the resulting electronic image is very large in size, which poses a significant challenge to the transmission, storage, and manipulation of images. Microcalcification is one of the earliest signs of breast cancer, and it tends to appear in small-sized, low-contrast radiopacities in the high-frequency spectrum of a mammographic image. Scalar wavelets excel multiwavelets in terms of peak-signal-to-noise ratio (PSNR), but fail to capture high-frequency information. This study proposes mammographic image compression and microcalcification detection in original and compressed reconstructed images using multiwavelets and neural networks. It also details the classification results obtained through the multiwavelet-based scheme in comparison with the existing scalar wavelet-based scheme. For a testing sample of 30 images, the proposed classification scheme outperforms the scalar wavelet-based classification by a sensitivity of 2.23% and specificity of 3.4% for original (uncompressed) images. Also, it increases the sensitivity by 2.72% and specificity by 8.4% for compressed reconstructed images. This increase in sensitivity and specificity demonstrates a better performance of the proposed detection scheme.     

Green synthesis of metal nanoparticles loaded ultrasonic‐assisted Spirulina platensis using algal extract and their antimicrobial activity

The synthesis of metal nanoparticles (NPs) loaded on the ultrasonic‐assisted Spirulina platensis (MNPs/UASP) was investigated using the green synthesis method. The S. platensis algal extract was taken as a reducing agent. The formations of metal NPs were characterised using UV–visible spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The antimicrobial activity of different metal NPs demonstrated various inhibitory activities against one gram‐positive bacteria (Staphylocicus aureus), four gram‐negative bacteria (Klebsiella pneumonia, Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli) and one fungus (Aspergillus niger). Both CrNPs/UASP and ZnNPs/UASP show good antimicrobial activity when compared with other MNPs/UASP against microorganisms. This MNPs/UASP is effective in preventing and treating the microbial infection and water pollution in the environment.Inspec keywords: antibacterial activity, nanoparticles, nanomedicine, ultraviolet spectra, visible spectra, microorganisms, Fourier transform infrared spectraOther keywords: metal nanoparticles loaded ultrasonic‐assisted Spirulina platensis, algal extract, antimicrobial activity, green synthesis method, UV–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, gram‐positive bacteria, Staphylocicus aureus, Klebsiella pneumonia, Proteus vulgaris, Pseudomonas aeruginosa, Escherichia coli, Aspergillus niger, fungus, microorganisms, microbial infection, water pollution     

Pretreatment of second and third generation feedstock for enhanced biohythane production: Challenges,recent trends and perspectives

In the context of biofuel production and achieving sustainable bioeconomy, the use of lignocellulosic and algae biomass in anaerobic fermentation processes yields biohythane that has a typical composition of 10–15% H₂, 50–55% CH₄ and 30–40% CO₂. Using organic biomass-based substrates has been shown to minimize environmental impacts due to the versatile production of high-value products under normal operating conditions that are practically achievable. However, the biohythane yield depends on different factors such as the biomass type, the organic loading rate, soluble metabolic products formed, the type of fermentation (single/dual stage) and the pretreatment strategy adopted for the biomass. Different pretreatment strategies based on physical, chemical and biological processes have been proposed in the literature. In this review, improvements in biohythane yield as a result of these pretreatment strategies, the need/effect of inoculum enrichment, the effects of pH, temperature, trace element addition and organic loading rate has been reviewed. Finally, the major developments of improving biohythane yield due to the addition of co-substrates and the current trends are discussed.     

STUDIES ON STIFLING AND DRYING OF COCOONS FOR LONGER STORAGE

ABSTRACT

Long term storage of stifled cocoons is an important problem during unfavourable seasonal conditions. Cocoons could be stifled within 20 minutes by using steam al 90°C. The shade drying of steam stifled cocoons in thin layers reduced the moisture content from 228 per cent (db) to 3 1.7 per cent (db) within 10 days. By hot air conditioning method the cocoons could be stifled and dried simultaneously. Using hot air at 90°C the cocoons could be stifled within 10 minutes, and dried to the equilibrium moisture content within 2 hours. The cocoons stifled by the hot air conditioning method could be reeled even just after stifling.     

Innovative multi‐processed N‐doped carbon and Fe3O4 cathode for enhanced bioelectro‐Fenton microbial fuel cell performance

A novel bioelectro‐Fenton microbial fuel cell (BEF‐MFC) cathode has been fabricated by modification of electrode using multi‐processing of nitrogen‐doped carbon (NDC)/nano‐Fe₃O₄ method with the aims of cost‐effectiveness, high oxygen reduction reaction (ORR) efficiency, and power performance enhancement. In this study, BEF‐MFC with carbon cloth (CC) cathode pyrolyzed with NDC‐M100/Fe₃O₄ at 700°C achieved higher ORR activity compared with the commercial Pt/C under same operational conditions. It also exhibited excellent crystalline structure according to high‐resolution transmission electron microscope (HRTEM) analysis. Moreover, using NDCN/Fe₃O₄ can facilitate further Fenton‐like reaction for the treatment of wastewater. Chemical oxygen demand (COD) removal efficiency of the reactor was 78% with maximum power density of 1.57 W/m³ in 216 hours. Thus, an innovative multi‐processing method with feasibility for enhanced wastewater treatment and improved power performance of the MFC was investigated. This can be effectively applied in related alternative energy production techniques and bio‐electrochemical systems in the future.