Fano-type discrete-continuum interaction in perovskites and its manifestation in Raman spectral line shapes

Fano resonance is one of the most significant physical phenomena that correlates microscopic processes with macroscopic manifestations for experimental observations using different spectroscopic techniques. Owing to its importance, a focused study is required to clearly understand the origin of certain modifications in spectral behaviour, the nature of which is different for different materials. This means that a careful understanding of Fano interactions can enhance the understanding of several technologically important materials, including perovskites, which are also important in the area of energy storage and conversion. In semiconductors and nano materials (including 2-D materials), Fano interactions occur due to the intervalence or interconduction band transitions. However, in perovskites, Fano interactions are dominated by the interaction between polar phonons or excitons with electronic continuum. Raman spectroscopy, being a sensitive and non-destructive tool, detects subtle scale phenomena, such as Fano interactions, by analysing the Raman line shape. Herein, different dimensions associated with the identification and thereafter the origin of the Fano resonance in perovskites, which are used in energy related areas, have been highlighted using Raman scattering.

Lipid Horizons: Recent Advances and Future Prospects in LBDDS for Oral Administration of Antihypertensive Agents

The lipid-based drug delivery system (LBDDS) is a well-established technique that is anticipated to bring about comprehensive transformations in the pharmaceutical field, impacting the management and administration of drugs, as well as treatment and diagnosis. Various LBDDSs verified to be an efficacious mechanism for monitoring hypertension systems are SEDDS (self-nano emulsifying drug delivery), nanoemulsion, microemulsions, vesicular systems (transferosomes and liposomes), and solid lipid nanoparticles. LBDDSs overcome the shortcomings that are associated with antihypertensive agents because around fifty percent of the antihypertensive agents experience a few drawbacks including short half-life because of hepatic first-pass metabolism, poor aqueous solubility, low permeation rate, and undesirable side effects. This review emphasizes antihypertensive agents that were encapsulated into the lipid carrier to improve their poor oral bioavailability. Incorporating cutting-edge technologies such as nanotechnology and targeted drug delivery, LBDDS holds promise in addressing the multifactorial nature of hypertension. By fine-tuning drug release profiles and enhancing drug uptake at specific sites, LBDDS can potentially target renin-angiotensin-aldosterone system components, sympathetic nervous system pathways, and endothelial dysfunction, all of which play crucial roles in hypertension pathophysiology. The future of hypertension management using LBDDS is promising, with ongoing reviews focusing on precision medicine approaches, improved biocompatibility, and reduced toxicity. As we delve deeper into understanding the intricate mechanisms underlying hypertension, LBDDS offers a pathway to develop next-generation antihypertensive therapies that are safer, more effective, and tailored to individual patient needs.

Nanoemulsion: An Emerging Novel Technology for Improving the Bioavailability of Drugs

The pharmaceutical sector has made considerable strides recently, emphasizing improving drug delivery methods to increase the bioavailability of various drugs. When used as a medication delivery method, nanoemulsions have multiple benefits. Their small droplet size, which is generally between 20 and 200 nanometers, creates a significant interfacial area for drug dissolution, improving the solubility and bioavailability of drugs that are weakly water-soluble. Additionally, nanoemulsions are a flexible platform for drug administration across various therapeutic areas since they can encapsulate hydrophilic and hydrophobic medicines. Nanoemulsion can be formulated in multiple dosage forms, for example, gels, creams, foams, aerosols, and sprays by using low-cost standard operative processes and also be taken orally, topically, topically, intravenously, intrapulmonary, intranasally, and intraocularly. The article explores nanoemulsion formulation and production methods, emphasizing the role of surfactants and cosurfactants in creating stable formulations. In order to customize nanoemulsions to particular medication delivery requirements, the choice of components and production techniques is crucial in assuring the stability and efficacy of the finished product. Nanoemulsions are a cutting-edge technology with a lot of potential for improving medication bioavailability in a variety of therapeutic contexts. They are a useful tool in the creation of innovative pharmaceutical formulations due to their capacity to enhance drug solubility, stability, and delivery. Nanoemulsions are positioned to play a crucial role in boosting medication delivery and enhancing patient outcomes as this field of study continues to advance.

Macromolecular Crowding Promotes Re-entrant Liquid-Liquid Phase Separation of Human Serum Transferrin and Prevents Surface-Induced Fibrillation

Protein aggregation and inactivation upon surface immobilization are major limiting factors for analytical applications in biotechnology-related fields. Protein immobilization on solid surfaces often requires multi-step surface passivation, which is time-consuming and inefficient. Herein, we have discovered that biomolecular condensates of biologically active human serum transferrin (Tf) can effectively prevent surface-induced fibrillation and preserve the native-like conformation of phase-separated Tf over a period of 30 days. It has been observed that macromolecular crowding promotes homotypic liquid-liquid phase separation (LLPS) of Tf through enthalpically driven multivalent hydrophobic interactions possibly via the involvement of its low-complexity domain (residues 3-20) containing hydrophobic amino acids. The present LLPS of Tf is a rare example of salt-mediated re-entrant phase separation in a broad range of salt concentrations (0-3 M) solely via the involvement of hydrophobic interactions. Notably, no liquid-to-solid-like phase transition has been observed over a period of 30 days, suggesting the intact conformational integrity of phase-separated Tf, as revealed from single droplet Raman, circular dichroism, and Fourier transform infrared spectroscopy measurements. More importantly, we discovered that the phase-separated condensates of Tf completely inhibit the surface-induced fibrillation of Tf, illustrating the protective role of these liquid-like condensates against denaturation and aggregation of biomolecules. The cell mimicking compact aqueous compartments of biomolecular condensates with a substantial amount of interfacial water preserve the structure and functionality of Tf. Our present study highlights an important functional aspect of biologically active protein condensates and may have wide-ranging implications in cell physiology and biotechnological applications.

Interdigitated electrodes-based Au-MoS2hybrid gas sensor for sensing toxic CO and NH3gases at room temperature

In the quest to create effective sensors that operate at room temperature, consume less power and maintain their stability over time for detecting toxic gases in the environment, molybdenum disulfide (MoS₂) and MoS₂-based hybrids have emerged as potent materials. In this context, the current work describes the fabrication of Au-MoS₂hybrid gas sensor fabricated on gold interdigitated electrodes (GIEs) for sensing harmful CO and NH₃gases at room temperature. The GIEs-based Au-MoS₂hybrid sensors are fabricated by decorating MoS₂nanoflowers (MNF) with varying size of Au nanoparticles using an inert gas evaporation technique. It is observed that by varying the size of Au nanoparticles, the crystallinity gets modified, as confirmed by x-ray diffraction and Micro-Raman spectroscopy (μRS). The gas sensing measurements revealed that the best sensing response is found from the Au-MoS₂hybrid (with an average particle size of 10 nm). This particular hybrid shows a 79% response to CO exposure and a 69% response to NH₃exposure. The measurements are about 3.5 and 5 times higher than the bare MoS₂when exposed to CO and NH₃at room temperature, respectively. This enhancement in sensing response is attributed to the modified interfacial interaction between the Au nanoparticles and MNF gets improved, which leads to the formation of a Schottky barrier, as confirmed using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy analysis. This enables the development of efficient gas sensors that respond quickly to changes in the gas around them.

Energy dispersive anti-anharmonic effect in a Fano intervened semiconductor: revealed through temperature and wavelength-dependent Raman scattering

It is always interesting to understand how the interplay between two perturbations, affects any physical process and gets manifested in a semiconductor. Temperature- and wavelength-dependent Raman Spectromicroscopy was performed on heavily-doped Si to reveal an unusual anti-anharmonic effect. Additionally, the energy dispersive behaviour of Fano coupling strength was also studied and its possible interrelation with the observed anti-anharmonic effect was explored. A systematic study revealed that at the different excitation wavelengths, the strength of the Fano interaction was different, where the involved electron-phonon (Fano-Fano-interferon) bound states were counted together with different energies. By understanding how the interplay manifests in terms of the Raman line shape, a method to calculate the Fano-interferon dissociation energy was developed. The slope of the Raman linewidth at different excitation wavelengths with temperature showed a negative temperature coefficient and sign reversal on decreasing the doping concentration. A wavelength-dependent empirical relation is proposed to calculate the required thermal energy, required to dissociate the electron-phonon bound state.

Nonlinear Temperature-Dependent Phonon Decay in Heavily Doped Silicon: Predominant Interferon-Mediated Cold Phonon Annihilation

A nonlinear Fano interaction has been reported here which is manifest in terms of a parabolic temperature-dependent phonon decay process observable in terms of a Raman spectral parameter. Temperature-dependent Raman spectroscopic studies have been carried out on heavily and moderately doped crystalline silicon to investigate the behavior of anharmonic phonon decay in semiconductor systems where Fano interactions are present inherently. Systematic study reveals that in heavily doped systems an interferon-mediated decay route exists for cold phonons present at lower temperatures (<475 K) where Fano coupling is stronger and dominates over the typical multiple-phonon decay process. On the other hand, the anharmonic phonon decay remains the predominant process at higher temperatures irrespective of the doping level. Temperature-dependent phonon self-energy has been calculated using experimentally observed Raman line-shape parameters to validate the fact that the nonlinear decay of phonons through interferon mediation is a thermodynamically favorable process at low temperatures.

Fano-Type Wavelength-Dependent Asymmetric Raman Line Shapes from MoS2 Nanoflakes

Excitation wavelength-dependent Raman spectroscopy has been carried out to study electron-phonon interaction (Fano resonance) in multi-layered bulk 2H-MoS₂ nano-flakes. The electron-phonon coupling is proposed to be caused due to interaction between energy of an excitonic quasi-electronic continuum and the discrete one phonon, first-order Raman modes of MoS₂. It is proposed that an asymmetrically broadened Raman line shape obtained by 633 nm laser excitation is due to electron-phonon interaction whose electronic continuum is provided by the well-known A and B excitons. Typical wavelength-dependent Raman line shape has been observed, which validates and quantifies the Fano interaction present in the samples. The experimentally obtained Raman scattering data show very good agreement with the theoretical Fano-Raman line-shape functions and help in estimating the coupling strength. Values of the electron-phonon interaction parameter obtained, through line-shape fitting, for the two excitation wavelengths have been compared and shown to have generic Fano-type dependence on the excitation wavelength.

Synthesizing Luminescent Carbon from Condensed Tobacco Smoke: Bio-Waste for Possible Bioimaging

Used cigarette filters, a waste material and a major source of land pollution, has been used as a raw material to study the nature of condensed tobacco smoke (tar) using microscopy, optical, IR, photoluminescence and Raman spectroscopy as well as X-ray diffraction and electron & fluorescence microscopy. The tar present in the cigarette filter bud has been used to synthesize luminescent low dimensional carbon using a simple methanol extraction technique. The collected material shows light blue emission under UV excitation with emission peak energy depending strongly on the excitation wavelength. Such excitation energy dependent emission is observed from the extract solution as well as dried film. Careful analysis has been carried out to understand its origin which reveals the presence of giant red-edge effect in the samples. A correlation between room temperature photoluminescence spectroscopy and fluorescence microscopy has also been carried out. Presence of amorphous phase carbon has been established using Raman spectroscopy and a quantum yield of more than 9% has been estimated which is moderately high in comparison with the one shown by carbon dots prepared by using other sources and can be used for bioimaging applications.

Bifunctional Application of Viologen-MoS2-CNT/Polythiophene Device as Electrochromic Diode and Half-Wave Rectifier

A dual purpose solid state electrochromic diode has been fabricated using polythiophene (P3HT) and ethyl Viologen (EV), predoped with multiwalled carbon nanotubes (MWCNTs) and MoS₂. The device has been designed by considering two important aspects, first, the complementary redox activity of P3HT and EV and second, the electron holding properties of MoS₂ and MWCNTs. The latter is found to enhance the electrochromic performance of the solid state device. On the other hand, the complementary redox nature gives the asymmetric diodic I-V characteristic to the device which has been exploited to use the electrochromic device for rectification application. The MoS₂ nanoflower and MWCNTs are synthesized by one-step hydrothermal and pyrolysis techniques and well characterized by scanning electron microscopy (SEM), X-ray analysis (XRD), and Raman spectroscopy. Electrochromic properties of the device have been studied in detail to reveal an improvement in device performance in terms of faster speed and high coloration efficiency and color contrast. In situ bias-dependent Raman spectroscopy has been performed to understand the operation mechanism of the electrochromic diode which reveals (bi-)polaron formation as a result of dynamic doping eventually leading to color change. A half-wave rectifier has been realized from the electrochromic diode which rectifies an AC voltage of frequency 1 Hz or less making it suitable for low frequency operation. The study opens a new possibility to design and fabricate multipurpose frequency selective electrochromic rectifiers.

Parallel or interconnected pores’ formation through etchant selective silicon porosification

The effect of the oxidizer present in the etching solution on the surface morphology and microstructure obtained after porosifying a p-type silicon wafer using metal-assisted chemical etching was studied. The morphologies of Si wafers porosified using two different solutions, HF/H2O2 and HF/KMnO4, were compared to establish how either of the oxidizers (H2O2 or KMnO4) should be chosen depending on the desired application. A comparative study revealed that parallel pores with wire-like structures or interconnected pores with cheese-like structures can be obtained when H2O2 or KMnO4 are chosen, respectively. Careful analysis of the SEM images was carried out using ImageJ to establish that the samples prepared using KMnO4 are more porous due to aggressive etching. Additionally, experimental and theoretical Raman spectroscopic studies have been utilized to study the presence of low-dimensional Si nanostructures, which are a few nanometers in size, at the microscopic level in porosified silicon.

Fuzzy-rough-neural-based f-information for gene selection and sample classification

The greatest restriction in estimating the information measure for microarray data is the continuous nature of gene expression values. The traditional criterion function of f-information discretises the continuous gene expression value for calculating the probability function during gene selection. This leads to loss of biological meaning of microarray data and results in poor classification accuracy. To overcome this difficulty, the concepts of fuzzy and rough set are combined to redefine the criterion functions of f-information and are used to form candidate genes from which informative genes are selected using neural network. The performance of the proposed Fuzzy-Rough-Neural-based f-Information (FRNf-I) is evaluated using ten gene expression datasets. Simulation results show that the proposed approach compute f-information measure easily without discretisation. Statistical analysis of the test result shows that the proposed FRNf-I selects comparatively less number of genes and more classification accuracy than the other approaches reported in the literature.

An Intelligent Operator for Genetic Fuzzy Rule Based System

This paper proposes a modified form of operator based on Particle Swarm Optimization (PSO) for designing Genetic Fuzzy Rule Based System (GFRBS). The usual procedure of velocity updating in PSO is modified by calculating the velocity using chromosome’s individual best value and global best value based on an updating probability without considering the inertia weight, old velocity and constriction factors. This kind of calculation brings intelligent information sharing mechanism and memory capability to Genetic Algorithm (GA) and can be easily implemented along with other genetic operators. The performance of the proposed operator is evaluated using ten publicly available bench mark data sets. Simulation results show that the proposed operator introduces new material into the population, thereby allows faster and more accurate convergence without struck into a local optima. Statistical analysis of the experimental results shows that the proposed operator produces a classifier model with minimum number of rules and higher classification accuracy.

Acclimatory response to hydrogen peroxide and glutathione under salt-boron stress through their impact on mineral nutrition and antioxidant defense system in pigeonpea (Cajanus cajan L.)

Investigations were carried out on a salt tolerant (Manak, H77-216) and a comparatively salt sensitive (ICPL 88039) genotypes of pigeonpea (Cajanus cajan L. Millsp.) under NaCl, B and NaCl + B stress to examine the acclimatory response to H2O2, glutathione and H2O2 + glutathione through their effect on mineral nutrition, morpho-physiological parameters and antioxidant defense system. Both B and NaCl alone and their combinations had deleterious effect on dry biomass of plumule, enhanced relative stress injury (RSI), lipid peroxidation with concomitant increase in Na, Cl and B contents. However it did not bear any correlation with osmotic potential of plumule and K contents. Antioxidative enzymes like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POX) and glutathione reductase (GR) also decreased with salt, B and salt + B treatments. However contents of H2O2 enhanced and that of ascorbate declined under aforementioned treatments. These injurious effects are partially alleviated by exogenous application of H2O2; glutathione (GSH) and H2O2 + GSH treatments. The role of H2O2 and GSH in the present study is suggestive of triggering multifunctional signal transduction in plant defense mechanisms to prevent cellular oxidation, membrane injury, lipid peroxidation and protein enzyme inactivation.

Effect of halides in the electrochemical treatment of distillery effluent

Electrochemical treatment can solve the problems arising due to effluents and offer an effective alternative to the existing methods. An undivided static electrolyser was charged with distillery effluent and the organics were oxidized electrochemically. Anodized graphite plate anodes and graphite cathodes were used for the treatment of distillery effluent. The effect of pH and current density on the treatment was studied. Sodium fluoride, sodium chloride and sodium bromide were chosen as electrolyte and their influence was found out. Complete decolorization has been observed in all cases. A maximum of 93.5% of biological oxygen demand reduction, 85.2% of chemical oxygen demand reduction and 98.0% absorbance reduction were obtained in the presence of sodium chloride as supporting electrolyte. Probable mechanism was also proposed for the oxidation of organics present in the effluent.

Dengue fever outbreaks in two villages of Dharmapuri district in Tamil Nadu

BACKGROUND & OBJECTIVES

Dengue fever is an important public health problem in India. In recent years this disease has extended to rural areas also due to rapid urbanization. In Tamil Nadu, fever outbreaks were reported in two villages of Dharmapuri district during May and September 2001 with clinical symptoms suggestive of dengue fever. Epidemiological, virological and entomological investigations were carried out in these two villages to ascertain the etiology of the outbreaks.

METHODS

Paired serum samples were collected from febrile patients clinically suspected to have dengue and were tested for the presence of IgM antibodies to dengue virus by MAC ELISA. Samples were also tested by Dengue Duo IgM/IgG rapid strip. Surveys of larval and adult Aedes mosquitoes were carried out before and after anti-larval and anti-adult measures were implemented. Female Ae. aegypti mosquitoes collected in Mampatti village were tested individually for the presence of dengue-2 viral antigen by indirect immunofluorescence assay (IIFA). In addition, two pools of female Ae. aegypti mosquitoes were tested for the presence of dengue viral antigen by ELISA and then subjected to Toxo-IFA system for demonstration of dengue virus.

RESULTS

A total of 124 and 267 fever cases with clinical symptoms and signs suggestive of dengue were reported in Kadumuchandiram and Mampatti villages of Dharmapuri district, respectively. Serodiagnosis revealed that 13 of 31 and 14 of 52 patients tested were positive for dengue-2 virus by MAC ELISA in Kadumuchandiram and Mampatti villages respectively. Dengue Duo rapid strip test also detected 14 (of 31 tested) patients positive for dengue virus specific IgM antibodies in Kadumuchandiram village and 8 (of 12 tested) in Mampatti village. Application of temephos and fogging with pyrethrum 2 per cent extract were found to be effective against immatures and adults respectively. Both the pools of Ae. aegypti tested for the presence of dengue viral antigen were positive by ELISA and one mosquito (tested individually) was positive by IIFA. Supernatants of two pools were found to be positive for dengue-2 virus by Toxo-IFA.

INTERPRETATION & CONCLUSION

Virological and serological investigations confirmed that the outbreaks of fever were due to dengue virus infection. High breeding of Ae. aegypti in the study villages, detection of dengue-2 viral antigen and isolation of dengue-2 virus in Ae. aegypti mosquitoes confirmed the etiology.

Lipoprotein(a) and coronary heart disease in Indian population

OBJECTIVE

Present study was undertaken to evaluate the role of lipoprotein(a) in coronary heart disease (CHD) patients and its relationship with other established risk factors.

METHODS

Blood samples of 67 control patients (non-cardiovascular problems) and 222 CHD patients (> or = 4 weeks post myocardial infarction) were analyzed. Lipoprotein(a) was measured in serum samples by enzyme-linked immunosorbent assay utilizing rabbit polyclonal antibodies against purified human Lp(a). Step-wise linear discriminant analysis was used to find the important parameters to discriminate CHD and non-CHD subjects.

RESULTS

The LDL to HDL cholesterol ratio (p < 0.01) and serum level of lipoprotein(a) (p < 0.01) were significantly higher in CHD patients. Levels of lipoprotein(a) were found to be higher in females compared to males (p < 0.01). Positive family history of CHD did not show significant difference in Lp(a) levels. Lp(a) level in CHD patients with positive family history of NIDDM and hypertension was higher than in with negative family history.

CONCLUSION

Clinical significance of serum level of Lp(a) and albumin in determining the risk of CHD has been observed. Lp(a) alone could correctly discriminate a CHD individual from a control subjects by 95%. Estimating of Lp(a) together with albumin provided 99% correct discrimination between control and CHD patients. These results also suggest that Lp(a) together with malnutrition could be responsible for the increased incidence of CHD in Indians. It is also indicated that in females atherothrombogenic potential of lipoprotein(a) remains suppressed before menopause but after this stage women lose this advantage.

Oxidative stress and metabolic control in non-insulin dependent diabetes mellitus

The aim of this study was to evaluate conjugated dienes in subjects with non-insulin-dependent diabetes mellitus (NIDDM) and its metabolic control. To achieve good metabolic control in addition to dietary management oral hypoglycemic agents such as glibenclamide, gliclazide and metformin were given to patients. Human plasma low-density lipoproteins (LDL) were delipidised and triglycerides (LDL-TG) and cholesterol esters (LDL-CE) were separated. Conjugated dienes in LDL-TG and LDL-CE of subjects with NIDDM (n = 90) and normal glucose tolerance (NGT) (n = 30) were measured using second derivative of uv absorption spectrum. Hypoglycemic agents lowered substantially concentration of cis, trans (c, t) and trans, trans (t, t) conjugated dienes in LDL-CE and LDL-TG. The duration of NIDDM has shown significant correlation (p < 0.001) with conjugated dienes in LDL-TG. Concentration of c, t and t, t-conjugated dienes in LDL-CE and LDL-TG were found significantly higher in subjects with NIDDM than NGT (p < 0.001). In conclusion, NIDDM, status of metabolic control and duration of diabetes have strong positive relation with oxidative stress.