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Serotonin is an important biogenic monoamine neurotransmitter that has major influences on mental health disorders; its structural and conformational changes have important roles in the biological functions of the human body. The decreased serotonin levels in the human body are majorly attributed to the causes of anxiety, depressive disorders, mood disorders, etc. Therefore, the quantification of serotonin in our bodies is of utmost importance in unearthing the origin of such physiological disorders. In this study, Terahertz-Time Domain Spectroscopy (THz-TDS) is employed to characterize the unique THz fingerprint of serotonin in the frequency range 0-3 THz. The characteristic THz absorption peaks of serotonin are observed at 0.54, 0.84, and 1.10 THz. In addition, Density Functional Theory (DFT) calculations are performed to investigate the vibrational properties of serotonin. For the vibrational assignment of modes, we have used Potential Energy Distribution (PED) analysis. Furthermore, studies have been conducted on the variation of serotonin concentration in a polyethylene (PE) host medium. The effect of the serotonin concentration in the PE host is studied using the complex refractive index (CRI) model. The sensitivity of detection of serotonin concentration is 0.015 for an increment of 2% concentration in PE medium. This work maps the spectral features of serotonin in the THz range, suggesting that THz-TDS can be used to understand and treat the physiological disorders related to serotonergic systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Aeromonas spp. are normal inhabitants of aquatic environments and are emerging foodborne bacterial pathogens. Aeromonas spp. contamination is frequent in ready-to-eat (RTE) seafood and can also occur in products prepared from milk or meat. The study determined the enterotoxin and antimicrobial susceptibility profiles of Aeromonas spp. isolates recovered from RTE milk products (n = 105), RTE meat/fish products (n = 40) and drinking water (n = 60) samples collected from tourist places in Himachal Pradesh, India, in northwestern Himalayas. 7.3 % (16/220) samples were found contaminated with Aeromonas spp. These isolates were identified as A. hydrophila (31.3 %), A. schubertii (25.0 %), A. sobria (25.0 %) and A. veronii (18.8 %). Aeromonas spp. contamination was significantly higher (14.3 %, 15/105, p = 0.0001) in RTE milk products. The contamination levels for water samples were 1.7 % whereas none of the tested RTE meat or fish products yielded Aeromonas spp. Among RTE milk products, contamination was significantly higher in paneer (South Asian soft cheese) (26.1 %, p = 0.0027) and cream (25.0 %, p = 0.046) based RTE foods. All isolates carried alt (361 bp), encoding a cytotonic heat-labile enterotoxin. Ampicillin resistance was 100 % and high levels (>30 %) of resistance were recorded for amoxicillin/clavulanic acid, amikacin, cefotaxime and ceftazidime. Six (37.5 %) isolates were multi drug resistant (MDR), showing resistance to aminoglycosides, cephams and penicillins. Isolation of alt carrying MDR isolates from RTE foods indicates that Aeromonas spp. can be potential foodborne public health threat in northwestern Himalayas., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Two self-healing-type supramolecular Ni(II)-metallogels are achieved. The choice of proper low-molecular-weight organic gelators such as trans -butenedioic acid ( i.e. , trans -BDA) and cis -butenedioic acid ( i.e. , cis -BDA) and triethylamine in N , N '-dimethylformamide solvent facilitates the metallogelation process. Through rheological investigations the mechanical robustness and viscoelastic properties of synthesized metallogels are explored. An in-depth exploration of thixotropic behavior also supports their self-healing features. Notably, distinct variations in morphologies of metallogels are also ascertained through field emission scanning electron microscopy studies. Furthermore, the existence of versatile noncovalent supramolecular interactions operating throughout the metallogel network is clearly revealed via Fourier transform infrared spectroscopy. Electrospray ionization-mass studies also explore the construction protocol of individual Ni(II)-metallogels. The Z-scan measurements with a 532 nm continuous wave laser were employed to unveil the nonlinear thermo-optical response of two synthesized self-healing metallogels, i.e. , trans -BDA-TEA@Ni(II) and cis -BDA-TEA@Ni(II). Crucial parameters like the nonlinear refractive index, nonlinear absorption coefficient, thermo-optical coefficient, and third-order susceptibility of these metallogels are obtained. Metallogels show negative signs for the nonlinear refractive index and the nonlinear absorption coefficient. The real parts of the third-order susceptibility for these metallogels are much greater than the imaginary parts ( i.e. , χ R (3) > χ I (3) ), making such metallogels very promising for all optical-switching applications.

Indolamines (e.g., serotonin and melatonin) are tryptophan-derived class of neurotransmitters and neuromodulators that play crucial roles in mood regulation, sleep-wake cycles, and gastrointestinal functions. These biogenic amines exert their effects by binding to specific receptors in the central nervous system, influencing neuronal activity and signalling cascades. Indolamines are vital in maintaining homeostasis, and imbalances in their levels have been implicated in various neurological and psychiatric disorders. Hence, in the present study, we have investigated the nonlinear properties of indolamines under a continuous wave (CW) and pulsed laser excitation using the closed-aperture (CA) Z-scan technique. The CA Z-scan is a cost-effective and sensitive analytical tool for investigating nonlinear properties. It is observed that indolamines show negative refractive and positive absorptive nonlinearity under in vitro physiological conditions. The origin of nonlinearity is ascribed to the thermo-optical effect governed by the saturated atomic absorption and molecular orientation mechanisms under CW and pulsed laser excitation, respectively. The strength of nonlinearity is found to vary linearly with the concentration of indolamines. Overall, serotonin possesses stronger nonlinearity than melatonin. The maximum nonlinearity (refractive index (n 2 ) & absorption coefficient (β)) for melatonin under CW and pulsed laser excitations are (-1.266 × 10 -12 m 2 W -1 and -1.883 × 10 -17 m 2 W -1 ) & (8.046 × 10 -8  mW -1 and 1.516 × 10 -13  mW -1 ), respectively. Meanwhile, the maximum n 2 and β under pulsed laser excitation for serotonin are obtained as -3.195 × 10 -17 m 2 W -1 and 6.149 × 10 -12  mW -1 , respectively. The outcome of the results may be utilized in understanding processes mediated by indolamines and designing therapeutic interventions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hematin anhydride (β-hematin), the synthetic analogue of the malaria pigment, "hemozoin", is a heme dimer produced by reciprocal covalent bonds among carboxylic acid groups on the protoporphyrin-IX ring and the iron atom present in the two adjacent heme molecules. Hemozoin is a disposal product formed from the digestion of hemoglobin present in the red blood cells infected with hematophagous malaria parasites. Besides, as the parasites invade red blood cells, hemozoin crystals are eventually released into the bloodstream, where they accumulate over time in tissues. Severe malaria infection leads to significant dysfunction in vital organs such as the liver, spleen, and brain in part due to the autoimmune response to the excessive accumulation of hemozoin in these tissues. Also, the amount of these crystals in the vasculature correlates with disease progression. Thus, hemozoin is a unique indicator of infection used as a malaria biomarker and hence, used as a target for the development of antimalarial drugs. Hence, exploring various properties of hemozoin is extremely useful in the direction of diagnosis and cure. The present study focuses on finding one of the unknown properties of β-hematin in physiological conditions by using the Z-scan technique, which is simple, sensitive, and economical. It is observed that hemozoin possesses one of the unique material properties, i.e., nonlinearity with a detection limit of ∼ 15 µM. The self-defocusing action causes β-hematin to exhibit negative refractive nonlinearity. The observed data is analyzed with a thermal lensing model. We strongly believe that our simple and reliable approach to probing the nonlinearity of β-hematin will provide fresh opportunities for malaria diagnostics & cure in the near future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The generation of solvent-directed self-healing supramolecular Ni(II) metallogels of glutaric acid (i.e., Ni-Glu-DMF and Ni-Glu-DMSO ) is described in this article. Polar aprotic solvents like N , N '-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) are separately entrapped into the Ni(II)-acetate salt and glutaric acid-mediated networks to attain the semisolid flexible scaffolds. The gel nature of the fabricated materials is experimentally proven through different rheological tests such as amplitude sweep, frequency sweep, and thixotropic (time sweep) measurements. The self-repairing strategy and load-bearing features of the synthesized metallogel are studied in this work. The different supramolecular noncovalent interactions working within the soft scaffold are clearly explored. The formation strategy and the microstructural features of these synthesized metallogels are scrutinized through a Fourier transform infrared (FT-IR) spectroscopy study and field-emission scanning electron microscopy (FESEM) morphological analyses. The FT-IR spectroscopy observation displays a considerable amount of shifting of the infrared (IR) peaks of the xerogel samples of both the metallogels Ni-Glu-DMF and Ni-Glu-DMSO . The electrospray ionization (ESI)-mass spectroscopy result demonstrates the plausible construction of the metallogel network. In order to examine the nonlinear optical characteristics of the two synthesized self-healing metallogels Ni-Glu-DMSO and Ni-Glu-DMF , Z-scan measurements are carried out with a continuous wave (CW) diode-pumped solid-state (DPSS) laser at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, thermo-optical coefficient, and third-order susceptibility of these metallogels were evaluated by analyzing the experimental data from the Sheik-Bahae formalism. The nonlinear thermo-optical study reveals that these solvent-dependent metallogels show negative signs of nonlinear refractive index and nonlinear absorption coefficient. The figure of merit calculated for these compounds shows good agreement for their use in nonlinear photonic devices.

Phase encoding in quantum key distribution (QKD) enables long-distance information-theoretic secure communication in optical fibers. We present a novel theoretical model characterizing errors from various sources in practical phase encoding-based QKD systems, namely the laser linewidth, detector dark counts, and channel dispersion. This model provides optimized optical pulse parameters and less distortion in pulses, which eliminates system imperfections and leads to a reduced quantum bit error rate (QBER) for practical QKD scenario. This analysis is applicable to various fiber-based phase and time encoding protocols. In particular, we implement this to a differential phase shift (DPS) QKD scheme operating at a 2.5 GHz clock, which produces a secure key rate of 193 bits/s at a fiber length of 265 km and an unprecedented QBER < 1[Formula: see text] up to 225 km length with standard telecom components. We show that by adjusting the quantum efficiency and dark count rates of detectors, proposed system can establish secure keys up to 380 km distance using standard telecom grade fiber with a QBER of 1.48%. Moreover, the system is compatible with existing optical fiber networks and capable of establishing a secure key exchange between two cities 432 km apart using ultra-low-loss (ULL) specialty fiber., (© 2023. Springer Nature Limited.)

Dopamine (DA) is a widely researched catecholamine best known for its role in motor, motivation, addiction, and reward. Disruption in dopamine homeostasis and signaling within the central nervous system (CNS) can lead to disorders such as attention deficit hyperactivity disorder (ADHD), schizophrenia, Parkinson's disease, and obsessive-compulsive disorder. In the periphery, circulating DA is stored in blood platelets, and its disruption correlates with pathological conditions such as head and neck paragangliomas, Huntington's chorea, and schizophrenia. Various methods to sensitively and selectively detect dopamine have been reported, but sparse attempts have been made to exploit its intrinsic properties. Previously, we have harnessed dopamine's natural mid-ultraviolet auto-fluorescence to carry out its label-free imaging in live brain tissues. Recently, we used the closed-aperture (CA) Z-scan method to provide the first line of evidence on the existence of dopamine nonlinearity. Here, we utilized this simple, sensitive, and straightforward CA Z-scan technique and coupled this with theoretical simulations to further investigate the nonlinear photophysical properties of DA under physiological conditions. Our combined approach revealed that the nonlinear property of dopamine is governed by the thermo-optical effects, and the CA Z-scan profiles can be modulated by parameters such as phase-shift, orders of absorption, and time dependency. Simple and physiologically relevant systems, such as the platelets, are amenable to Z-scan analysis, thereby empowering us to scrutinize in the future if nonlinearity and its alterations, if any, have a direct bearing on DA homeostasis and associated diseases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: Intentional pesticide poisoning is a major clinical and public health problem in agricultural communities in low and middle income countries like Nepal. Bans of highly hazardous pesticides (HHP) reduce the number of suicides. We aimed to identify these pesticides by reviewing data from major hospitals across the country and from forensic toxicology laboratories., Methods: We retrospectively reviewed medical records of 10 hospitals for pesticide poisoned patients and two forensic laboratories of Nepal from April 2017 to February 2020. The poison was identified from the history, referral note, and clinical toxidrome in the hospitals and from gas chromatography analysis in the laboratories. Data on demographics, poison, and patient outcome were recorded on a data collection sheet. Simple descriptive analysis was performed., Results: Among hospital cases ( n  = 4148), the commonest form of poisoning was self-poisoning (95.8%) while occupation poisoning was rare (0.03%). Case fatality was 5.3% ( n  = 62). Aluminum phosphide ( n  = 38/62, 61.3%) was the most commonly identified lethal pesticide for deaths. Forensic toxicology laboratories reported 2535 deaths positive for pesticides, with the compounds most commonly identified being organophosphorus (OP) insecticides ( n  = 1463/2535; 57.7%), phosphine gas ( n  = 653/2535; 25.7%; both aluminum [11.8%] and zinc [0.4%] phosphide) and organochlorine insecticides ( n  = 241/2535; 9.5%). The OP insecticide most commonly identified was dichlorvos ( n  = 273/450, 60.6%)., Conclusion: The data held in the routine hospital medical records were incomplete but suggested that case fatality in hospitals was relatively low. The pesticides identified as causing most deaths were dichlorvos and aluminum phosphide. Since this study was completed, dichlorvos has been banned and the most toxic formulation of aluminum phosphide removed from sale. Improving the medical record system and working with forensic toxicology laboratories will allow problematic HHPs to be identified and the effects of the bans in reducing deaths monitored.

Norepinephrine (NE), a crucial modulatory neurotransmitter, plays a significant role in human physiology. Here, we use the Z-scan technique to investigate the nonlinear properties of NE at physiological conditions. Results reveal that NE exhibits thermo-optical nonlinearity. Outcomes can be utilized to investigate noradrenergic processes in correlation with various diseases.

The natural abundance of aluminum is far better than those of noble metals like silver and gold. Its plasmonic properties have not been explored in detail, as they generally lie in the ultraviolet region of the electromagnetic (EM) spectrum. Nevertheless, recent advanced research work in the literature predicts aluminum to be the next and best plasmonic material suitable for exciting cost-effective applications. Inspired by this, we have analyzed the optical properties of aluminum metal nanoshells using semi-analytical and numerical finite difference time domain models. In the semi-analytical model, we have discussed an electrostatic approach for nanoshell geometry and derived the exact Frolich condition and corresponding plasmon resonance peak position. These plasmonic peaks and their tunability in different regimes of the electromagnetic spectrum via the shell thickness are the main thrust of this work. For proof of concept, we have compared simulated and modeled results in different parameter domains and observed that both sets of results are in agreement with each other. We have also visualized the distribution of the electric field intensity near the aluminum nanoshell surface under SPR conditions, which covers a broad range of applications.

A toxicological study was performed in albino mice and rat with methanolic extract and isolated alkaloid of Taxus baccata Linn. (family: Taxaceae). LD(50) study showed the higher toxic activity in stem (TXA-1,2,3) as compared with leaf (TXB-1,2,3) extract. As the extract were further fractionated into crude alkaloids and purified by chromatography the toxicity of these fractions were found to be in increasing order as follows: methanolic extract (1) < crude alkaloidal fraction (2) < purified alkaloidal fraction (3). The effects of leaf and stem extract of T. baccata were studied on certain biochemical and haematological parameters of mice and rat after 10, 20 and 30 days of exposure. Among the parameters examined, the exposed animal exhibited significant decrease in total leukocyte count (TLC), lymphocytes and cholesterol level (mg/dl), whereas increase was observed in serum transminases (SGOT, SGPT) and alkaline phosphatase (AP) of TXA-1 and TXB-1 treated groups indicating toxic conditions associated due to liver involvement.

Lapachol, a naphthaquinone isolated from the roots of Tectona grandis given at a dose of 5 mg kg-1 p.o. twice daily for 3 days was found to have an anti-ulcerogenic effect on subsequently induced experimental gastric and duodenal ulcers in rats and guinea-pigs. Its action appears to be associated with an effect on the protein content of gastric juice, and it reversed aspirin-induced changes in peptic activity, protein and sialic acid.