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Biosurfactants are emerging as a revolutionary substitute for chemical surfactants in various industrial sectors due to their lower toxicity, biodegradable, and environmentally friendly nature. Robust surface activity properties and high emulsification of biosurfactants make them feasible for diverse applications in food industries, such as bakeries, meat and fish processing, heavy metal removal from vegetables, salad dressings, etc. Given the eco-friendliness and safety of biosurfactants, this review focuses on the latest developments in their use in the food business. Nevertheless, it is noteworthy that biosurfactants are not competitively priced with commercial surfactants; consequently, several unique challenges, including the requirement for costly raw substrates and labor-intensive downstream processing, must be addressed to enable the widespread industrial use of biosurfactants. This review recommends further in-depth studies using less expensive, environment-friendly substrates and utilizing state-of-the-art technologies such as genetic engineering and nanotechnologies for biosurfactant production that can overcome the barrier of poor yield and expensive biosurfactant. [ABSTRACT FROM AUTHOR]

Abstract: An internal field induced resonant intensity enhancement of Raman scattering of phonon excitations in InAs nanowires is reported. The experimental observation is in good agreement with the simulated results for the scattering of light under varying incident wavelengths, originating from the enhanced internal electric field in an infinite dielectric cylinder. Our analysis demonstrates the combined effect of the first higher lying direct band gap energy (E 1) and the refractive index of the InAs nanowires in the internal field induced Raman scattering. Furthermore, the difference in the relative contribution of electro-optic effect and deformation potential in Raman scattering of nanowires and bulk InAs over a range of excitation energies is discussed by comparing the intensity ratio of their LO and TO phonon modes. [Copyright &y& Elsevier]

Ge clusters are grown on Si substrate at room temperature (Ge-RT) and also at liquid nitrogen temperature (Ge-LNT) by cluster evaporation technique. These clusters show blue luminescence. Raman measurement demonstrates the increase in strain with annealing in diffused disordered Si at the interface between Ge-LNT clusters and Si substrate. This manifests in strain-relaxation in the clusters as observed by Photoluminescence (PL) measurements. The decrease in PL intensity for Ge-RT with annealing has been attributed to reduction in surface oxide species, which is supported by Raman spectroscopic measurements. The objective of the paper is to understand the effect of thermal annealing on both interfacial strain and interdiffusion of elemental Si at the interface, together with luminescence characteristics of the clusters. [Copyright &y& Elsevier]

Abstract Using first principles calculations we unveil the interfacial strain relaxation in (wurtzite-InAs) n /(zinc-blend-InSb) m multilayer specimens. We have shown that the distribution of strain along the growth direction depends on the relative thickness of the segments of the multilayer. The observed result has been explained in view of the propagation of lattice deformation due to lattice mismatch between InAs and InSb. To the end we have demonstrated that the fine tuning of the strain with the thickness of layers can be exploited to vary the band gap along the length of the multilayer. The modulation of the band gap in a multilayer system finds various applications in designing optoelectronic devices. Highlights • Strain profile in (InAs) n /(InSb) m multilayer systems, using first principles density functional theory calculations, is reported. • The role of relative thickness of the components of the multilayers in strain distribution is discussed. • The modulation of band gap along the length of the multilayer due to the strain distribution has been demonstrated. [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA), the most abundant plasma protein in the human body is known to form fibrils under partial denaturing conditions. Natural polyphenols are known to interact with HSA and some polyphenols have been shown to be potent inhibitors of amyloid fibrillation. (−)-Epigallocatechin gallate (EGCG), the major component of green tea is known to inhibit amyloid fibrillation. In this report, we have investigated the effect of EGCG on native HSA as well as on the fibrillation process of HSA from amide III band analysis of their respective visible Raman spectra. The differential role of the tryptophan (Trp214) residue present in domain II of HSA in the absence and presence of EGCG has been pointed out using fluorescence anisotropy and visible Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: The second-order transverse acoustic mode and amorphous Raman modes, originating from a continuous random network and medium range ordering (MRO), in high energy light ion (HELI) irradiated GaAs are investigated. The change in the phonon density of states of the transverse acoustic mode phonon distinguishes the effect of HELI irradiation on highly resistive undoped and chromium-doped GaAs. The boson mode, originating from the MRO of the system, has been identified and a model based on phonon-fracton scattering has been used for the explanation of this “boson mode”. The spectral dimension, correlation length and the scaling factor, with which the elastic constant varies with length in MRO regions in GaAs, are estimated. [Copyright &y& Elsevier]

Microwave radiations from various electronic devices are of serious health concern. In this article, using spectroscopic measurements, we show that the microwave radiation of strength 22 dBm and frequency 10 GHz facilitates protein fibrillation. However, this adverse effect of low-field radiation can be restricted by the presence of biocompatible citrate-capped gold nanoparticles. The dissipative field by metallic particles is able to disrupt the fibrillar network. We believe that the obtained results paved a way to find a therapeutic measure to combat fibrillation related diseases. [ABSTRACT FROM AUTHOR]

Single crystals of the iron-pnictide compound BaFe 2 (As 1 − x P x) 2 for x ∼ 0.23, with a doping concentration near quantum criticality and enhanced nematic fluctuating state in the doping-temperature phase diagram, have been studied. Transport measurements confirm the presence of a magneto-structural transition at 60 K from the tetragonal to the orthorhombic phase, followed by a superconducting transition below 16 K. Micro-Raman spectra of the compound exhibit a phonon mode at 211 cm−1 and two broad modes (BMs) at 515 cm−1 and 635 cm−1, which corresponds to an energy difference of 15 meV. The temperature dependent Raman measurements reveal that the intensity of these BMs drop over the temperature range between 80 K and 300 K. In the non-superconducting state, strong anisotropic behaviour is observed for these BMs in polarization dependent Raman scattering. Electronic structure calculations for doped and undoped BaFe 2 As 2 show that while Fe d x z and d y z orbitals do not split in the tetragonal phase, the splitting energy is 13.5 meV in the orthorhombic phase of the doped system, which is reasonably close to the experimentally observed value of the energy separation of the BMs. We believe that the reported BMs are consistent with the signature of electronic Raman scattering involving the crystal field levels of d -orbitals of Fe2＋ due to local breaking of the C 4 symmetry in the doped system. • Local symmetry breaking in tetragonal phase of P doped BaFe 2 As 2 near quantum critical point. • Signature of crystal field splitting using temperature dependent micro Raman spectroscopy. • Calculation of Fe d orbitals split energies in local orthorhombic phase using DFT. [ABSTRACT FROM AUTHOR]

In this study, we attempt to find the origin of atypical doping concentration dependant electrical properties of group III element (Al, Ga, In) doped ZnO thin films. The carrier density and mobility of these films are measured and compared for a wide range of doping concentrations. It is found that donor density determines the electrical properties of the films for a low level of doping, whereas lattice defects play a dominant role beyond a certain level of doping concentration. We also demonstrate an interrelationship between the electrical properties and the structural/optical properties of the films. We find 2% as optimum doping concentration for Al-, Ga- or In-doped ZnO for obtaining highest conducting layers and Ga emerges as the most effective dopant among all. [ABSTRACT FROM AUTHOR]

This article reports a comprehensive study on damage evolution in undoped InP due to 100 MeV silver (Ag 7+ ) ion irradiation. Raman and Rutherford back scattering channeling (c-RBS) measurements are employed to bring out two different aspects of disorder in the system. While Raman spectroscopy revealed a monotonic increase in sub-surface strain due to ion irradiation, the later detected heavy damage in the wafer at high fluences. Furthermore, we have estimated the lattice temperature under above irradiation conditions in InP using a unified thermal spike model. The model includes both inelastic thermal spike and elastic collision spike along with the effect of latent heat. This model explains the observed damage evolution of the target. Above experimental techniques in conjunction with the simulation model provides a qualitative explanation of the damage accumulation leading to structural modification in the Ag ion-irradiated InP wafer. [ABSTRACT FROM AUTHOR]

In vitro fibrillation of hen egg white lysozyme (HEWL) causes complete reduction of Cu(II) to Cu(I) at pH 7. Here in the present article, we have shown the presence of both Cu(II) and Cu(I) at pH 11 during fibrillation of HEWL using electron paramagnetic resonance and Raman spectroscopy. Our results suggest the existence of a partially reducing environment during fibrillation of hen egg white lysozyme at pH 11. The fibrillation process is governed by the pH of the solution and maximum fibrillation is found to occur at pH 11. Fibrils formed in the absence of Cu(II) were also found to cause significant hemolysis of RBC. [ABSTRACT FROM AUTHOR]

Abstract: Copper is known to exert diverse effects on the self-association of proteins and has been found in amyloid deposits that are involved in neurodegenerative disease processes. The effects of the metal ion on the protein during fibrillation were investigated by fluorescence, circular dichroism spectroscopy and fluorescence microscopy. We report for the first time, the complete reduction of Cu(II)→Cu(I) in vitro during fibrillation of hen egg white lysozyme at pH 7. This was confirmed by the lack of any signal for Cu(II) in electron paramagnetic resonance spectroscopy and quantification of Cu(I) was achieved by a bathocuproine disulfonate based assay. [Copyright &y& Elsevier]

Abstract: In this article, we discuss metal–protein interactions in the Ag–lysozyme complex by spectroscopic measurements. The analysis of the variation in relative intensities of SERS bands reveals the orientation and the change in conformation of the protein molecules on the Ag surface with time. The interaction kinetics of metal–protein complexes has been analyzed over a period of 3h via Raman measurements. Our analysis indicates that the Ag nanoparticles most likely interact with Trp123 which is in close proximity to Phe34 of the lysozyme molecule. [ABSTRACT FROM AUTHOR]

The phase stability of zirconia (ZrO 2) under external perturbation draws the attention of researchers, as it governs the practical use of this material in technological applications. In this article, the phase transition in zinc oxide (ZnO) doped ZrO 2 is addressed by exploiting complementary methodologies, X-ray diffraction, and Raman spectroscopic measurements. We have observed a pressure-induced partial phase transformation in the doped ZrO 2 system for a compacting pressure of less than 1 GPa. It is noteworthy that the level of compacting pressure used in this study is much lower than the range of pressure, reported in the literature, for observing phase transition in pure and doped ZrO 2 using other high-pressure experiments. To understand the underlying dynamics of low pressure-induced phase transformation, we carried out density functional theory calculations for the doped supercell. We have discussed the local bonding environment around the dopant metal ion (Zn2+ in the present case), which, we believe, leads to the phase evolution in a real system. [ABSTRACT FROM AUTHOR]

Sapphire-supported hBN films of different thicknesses are grown using metalorganic vapour phase epitaxy technique by following a flow modulation scheme. Though these wafer-scale films are potential candidates for real device applications, they exhibit wrinkling. The wrinkles are a key signature of strain distribution in the films. We utilized Raman imaging to study the residual strain distribution in the wrinkled hBN films. An increase in the overall compressive strain in the films with an increase in the layer thickness is observed and explained. An empirical relation is proposed for estimating the wrinkle mediated strain relaxation from the morphology of the films. Furthermore, we show that the residual strain can be partially released by the delamination of the films. [ABSTRACT FROM AUTHOR]