Structural and Thermal Investigations of Biomimetically Grown Casein–Soy Hybrid Protein Fibers

A hybrid protein fiber from different protein sources such as casein and soybean using wet-spinning technique was prepared. The casein/soybean hybrid fibers were synthesized at different weight ratios such as 100/0 (casein), 75/25, 50/50, 25/75, and 0/100 (soy) and characterized. Electron microscopic analysis confirmed the growth of pure and hybrid fibers and shows an increased surface roughness as the soy concentration increases in the hybrid fibers. Infrared spectra did not exhibit any significant changes in the functional groups between pure and hybrid fibers. X-ray diffraction pattern indicates slight increase in the diffraction peak values of hybrid fibers compared with the neat fibers. Thermal analyses show a moderate increase in the thermal stability of hybrid fibers when compared with the pure fibers. These results implicitly indicate that the casein and soy proteins are homogeneous in the hybrid fiber form. It has been demonstrated that the hybrid fiber with ≥50 wt.% casein content exhibits better morphology and increased thermal stability, which has scope for application in technical and medical industries.     

Sonochemically prepared platinum-ruthenium bimetallic nanoparticles

Colloidal bimetallic nanoparticles of Pt-Ru have been synthesized by sonochemical reduction of Pt(II) and Ru(III) in aqueous solutions. Transmission electron microscope (TEM) images indicate that sequential reduction of the Pt(II) followed by the Ru(III) produces particles with a core shell (Pt@Ru) morphology. In the presence of sodium dodecyl sulfate, SDS, as a stabilizer, the particles have diameters between 5 and 10 nm. When polyvinyl-2-pyrrolidone, PVP, is used as the stabilizer, the rate of reduction is much faster, giving ultrasmall bimetallic particles of approximately 5 nm diameter.     

Determination of temperatures within acoustically generated bubbles in aqueous solutions at different ultrasound frequencies

Mean acoustic bubble temperatures have been measured using a methyl radical recombination (MRR) method, at three ultrasound frequencies (20, 355, and 1056 kHz) in aqueous tert-butyl alcohol solutions (0-0.5 M). The method is based on yield measurements of some of the hydrocarbon products formed from the recombination of methyl radicals that are thermally generated within collapsing bubbles containing tert-butyl alcohol vapor. The mean bubble temperatures were found to decrease substantially with increasing tert-butyl alcohol concentration at 355 and 1056 kHz but only to a small extent at 20 kHz. Extrapolating the mean temperatures measured to zero concentration of tert-butyl alcohol, at a bulk solution temperature of 20 degrees C, gave the order 355 kHz (4300 +/- 200 K) > 1056 kHz (3700 +/- 200 K) > 20 kHz (3400 +/- 200 K). It is also concluded that the temperature derived from the MRR method is a useful diagnostic parameter for sensing the thermal conditions within an active acoustic bubble. However, attention must be given to the fact that the temperature derived from the MRR method is not theoretically well defined.     

The influence of acoustic power on multibubble sonoluminescence in aqueous solution containing organic solutes

The effect of varying the applied acoustic power on the extent to which the addition of water-soluble solutes affect the intensity of aqueous multibubble sonoluminescence (MBSL) has been investigated. Under most of the experimental conditions used, the addition of aliphatic alcohols to aqueous solutions was found to suppress the MBSL intensity, although an enhancement of the MBSL intensity was also observed under certain conditions. In contrast, the presence of an anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solutions generally enhanced the observed MBSL intensity. For a series of aliphatic alcohols and SDS, a strong dependence of the MBSL intensity on the applied acoustic power (in the range of 0.78-1.61 W/cm(2)) at 358 kHz was observed. The relative SL quenching was significantly higher at higher acoustic powers for the alcohol solutions, whereas the relative SL enhancement was lower at higher acoustic powers in SDS solutions. These observations have been interpreted in terms of a combination of material evaporation into the bubble, rectified diffusion, bubble clustering and bubble-bubble coalescence.     

A comparison between multibubble sonoluminescence intensity and the temperature within cavitation bubbles

Cavitation bubble temperatures have been measured using a methyl radical recombination method and compared with the changes in the sonoluminescence intensity in aqueous ethanol solutions over a range of concentrations. Whereas the sonoluminescence intensity was decreased by more than 90% at low ethanol concentrations (<0.1 M), the measured bubble temperatures seem to be unaffected at this level of additive. The cavitation bubble temperatures were noticeably decreased at substantially higher ethanol concentrations (0.5 M). It has been concluded that the methyl radical recombination method does not report on the true sonoluminescence temperatures. However, it does report on the average bubble temperatures at which sonochemical reactions occur.     

One-pot ultrasonic synthesis of multifunctional microbubbles and microcapsules using synthetic thiolated macromolecules

A one-pot ultrasonic procedure has been developed as a versatile route for synthesizing polymer-coated microspheres that have potential application as drug delivery vehicles. The use of synthetic thiolated poly(methacrylic acid) macromolecules as the shell material offers control over size, morphology and functionality of the microspheres.     

Design and divergent synthesis of aza nucleosides from a chiral imino sugar

Several novel nucleoside analogues as potential inhibitors of glycosidases and purine nucleoside phosphorylase (PNP) have been synthesized via selective coupling of an appropriate nucleobase at different positions of an orthogonally protected imino sugar as a common precursor. This synthetic strategy offers a straightforward protocol for the assembly of imino sugar containing nucleosides, establishing a new repertoire of molecules as potential therapeutics.     

Ultrasonic enhancement of the supercritical extraction from ginger

This work examines the concurrent use of power ultrasound during the extraction of pungent compounds from a typical herb (ginger) with supercritical CO₂. A power ultrasonic transducer with an operating frequency of 20 kHz is connected to an extraction vessel and the extraction of gingerols from freeze-dried ginger particles (4–8 mm) is monitored. In the presence of ultrasound, we find that both the extraction rate and the yield increase. The higher extraction rate is attributed to disruption of the cell structures and an increase in the accessibility of the solvent to the internal particle structure, which enhances the intra-particle diffusivity. While cavitation would readily account for such enhancement in ambient processes, the absence of phase boundaries should exclude such phenomena above the critical point. Possible alternate mechanisms for the cell structure damage are discussed.     

The Role of Antimicrobial Peptides as Antimicrobial and Antibiofilm Agents in Tackling the Silent Pandemic of Antimicrobial Resistance

Just over a million people died globally in 2019 due to antibiotic resistance caused by ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). The World Health Organization (WHO) also lists antibiotic-resistant Campylobacter and Helicobacter as bacteria that pose the greatest threat to human health. As it is becoming increasingly difficult to discover new antibiotics, new alternatives are needed to solve the crisis of antimicrobial resistance (AMR). Bacteria commonly found in complex communities enclosed within self-produced matrices called biofilms are difficult to eradicate and develop increased stress and antimicrobial tolerance. This review summarises the role of antimicrobial peptides (AMPs) in combating the silent pandemic of AMR and their application in clinical medicine, focusing on both the advantages and disadvantages of AMPs as antibiofilm agents. It is known that many AMPs display broad-spectrum antimicrobial activities, but in a variety of organisms AMPs are not stable (short half-life) or have some toxic side effects. Hence, it is also important to develop new AMP analogues for their potential use as drug candidates. The use of one health approach along with developing novel therapies using phages and breakthroughs in novel antimicrobial peptide synthesis can help us in tackling the problem of AMR.     

Derepressed 2-deoxyglucose-resistant mutants of Aspergillus niger with altered hexokinase and acid phosphatase activity in hyperproduction of β-fructofuranosidase

Aspergillus niger NRRL330 produces extracellular β-fructofuranosidase (Ffase), and its production is subject to repression by hexoses in the medium. After ultraviolet mutagenization and selection, seven derepressed mutants resistant to 2-deoxyglucose (2-DG) were isolated on Czapek’s minimal medium containing glycerol. One of the mutants, designated DGRA-1, produced higher levels of Ffase. A considerable difference occurred in the mutants with reference to hexokinase and intracellular acid phosphatase activities. The hexokinase activity of the mutant DGRA-1 (0.69 U/mg) was 1.8-fold higher than the wild type (0.38U/mg). Intracellular acid phosphatase activity of the mutant DGRA-1 (0.83 U/g of mycelia) was twofold higher than that of the wild type (0.42U/g of mycelia), suggesting that phosphorylation and dephosphorylation steps could attribute to the 2-DG resistance of A. niger. However, additional mutations could account for the increased production of Ffase in the mutant DGRA-1.