Constant Values Research Articles

NONLINEAR DYNAMICS METHODS APPLICATIONS TO PRODUCT LIFECYCLE MANAGEMENT

The research being carried out is aimed at applying nonlinear dynamics methods in product life cycle management to improve communication between processes and achieve environmental sustainability. The purpose of the article is to create a nonlinear mathematical model for analysing product lifecycle management. Chaotic nonlinear dynamical processes of product lifecycle are deterministic but have the property that even small uncertainties in initial conditions lead to exponentially growing errors in the management that limit long-term forecasts. The emergence of chaotic behaviour in processes of product lifecycle was explored, focusing on fluctuations. The study employed methods such as systems analysis, correlation analysis, nonlinear dynamics, and the Surrogate model of chaotic Lorenz waterwheel. It was identified that sharp technological innovations as the primary drivers of short-term fluctuations impacting fixed efficiency and effectiveness of product life cycle process development. The resulting nonlinear dynamic model allowed for flexible operation, transitioning between equilibrium, periodic, and chaotic states based on coefficient values for asset growth rates and time constants reflecting product life cycle process dynamics. The research results are valuable for companies seeking to reduce their environmental impact and implement circular economy principles.

Control system optimisation of biodiesel-based gas turbine for ship propulsion

<p>Reducing a gas emission of shipping transportations become a main goal of international maritime organization to achieve a clean energy. One of best scenarios to achieve this goal is to shift a fossil fuel to a renewable energy-based fuel of a ship propulsion. This paper studies an optimization of a control system of the renewable-based small gas turbine engine for the ship propulsion. Proposed control system consists of a proportional-integral with engine performance limiters to avoid an engine damage. Proportional-integral gains are tuned by a whale optimization algorithm. A gain scheduling analysis of a step response is performed to obtain a searching area of tuning parameters and values of constant gains. In this step, the gains are modeled as function of plant variables. After the searching area is obtained, the proportional-integral gains are optimized using the whale optimization algorithm while the additional gains are set as constant values. Using this scenario, stable and optimal gains have been successfully achieved. Results show that the proposed method has better performance than that of the previous methods, i.e. gain scheduling and gain scheduling optimized by the whale optimization algorithm. The proposed method has lowest fitness value and does not have an overshoot problem.</p>

Crystal structure, stability, and transport properties of Li2BeAl and Li2BeGa Heusler alloys: a DFT study

In this study, the structural, elastic, electronic, and thermoelectric properties of full Li2BeAl and Li2BeGa Heusler alloys were explored using density functional and the Boltzmann transport theories. The GGA and HSE approximations have been used for the exchange–correlation potential. Results indicated that these two compounds are more energetically stable in the inverse Heusler structure. Additionally, both Li2BeAl and Li2BeGa Heusler alloys were found to be mechanically stable due to the positive values of the elastic constants. Also, the high values of the Young's modulus indicate that these compounds are stiff and exhibit a semi-metallic nature. The band gaps were determined to be 0.13 eV and − 0.22 eV for Li2BeAl and Li2BeGa alloys, respectively, using the GGA approximation. By employing the HSE hybrid functional, however, the band gap for Li2BeAl increased to 0.26 eV, and for Li2BeGa, it decreased to − 0.16 eV. Regarding thermoelectric properties, Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivities, power factor, and the figure of merit have been calculated for both Li2BeAl and Li2BeGa Heusler alloys at different temperatures. Seebeck coefficient in both alloys decreases with increasing the temperature and has the highest value at 300 K. Thermal conductivity and electrical conductivity increase with increasing the temperature, which confirms the intermetallic behavior of the Heusler alloys. The results obtained for both alloys show that n-type doping has better thermoelectric properties than p-type doping. The maximum value of the figure of merit (ZT) was obtained for n-type doping, which was 1.43 at 660 K for Li2BeAl and 0.39 at 1000 K for Li2BeGa alloy. The high values of ZT especially for electron-dopped Li2BeAl suggest the great potential of this material for use in thermoelectric devices. This study suggests that the proposed materials have potential applications in spintronic devices and thermoelectric materials due to their intermetallic character and effective thermoelectric coefficients.

Numerical and Thermodynamic Analysis of the Effect of Operating Temperature in Methane-Fueled SOFC

This study examines the thermodynamic and numerical analyses of a methane-fed solid oxide fuel cell (SOFC) over a temperature range varying between 873 K and 1273 K. These analyses were conducted to investigate and compare the performance of the SOFC under various operating conditions in detail. As part of the thermodynamic analysis, important parameters such as cell voltage, power density, exergy destruction, entropy generation, thermal efficiency, and exergy efficiency were calculated. These calculations were used to conduct energy and exergy analyses of the cell. According to the findings, an increase in operating temperature led to a significant improvement in performance. At the initial conditions where the SOFC operated at a temperature of 1073 K and a current density of 9000 A/m2, it was observed that when the temperature increased by 200 K while keeping the current density constant, the power density increased by a factor of 1.90 compared to the initial state, and the thermal efficiency increased by a factor of 1.45. Under a constant current density, the voltage and power density values were 1.0081 V, 1.0543 V, 2337.13 W/m2, and 2554.72 W/m2 at operating temperatures of 1073 K and 1273 K, respectively. Under a current density of 4500 A/m2, the entropy generation in the cell was determined to be 29.48 kW/K at 973 K and 23.68 kW/K at 1173 K operating temperatures. The maximum exergy efficiency of the SOFC was calculated to be 41.67% at a working temperature of 1273 K and a current density of 1500 A/m2. This study is anticipated to be highly significant, as it examines the impact of temperature variation on exergy analysis in SOFC, validating both numerical and theoretical results, thus providing a crucial roadmap for determining optimized operating conditions.

Elucidating the deformation characteristics of Ti–Ni–Fe based pseudo-binary B2 intermetallics

The room temperature uniaxial compression behavior of homogenized Ti50Ni50-xFex (5≤x ≤ 45) pseudo-binary B2 intermetallics has been investigated. The compressive stress-strain curves of these intermetallics exhibited three different characteristics (a) intermetallics with low Fe content (i.e., Ti50Ni45Fe5 and Ti50Ni40Fe10): exhibited stress induced martensite (SIM) transformation (B2 → B19 ') (marked by a plateau with non-linear elastic regime) followed by significant plastic deformation up to ∼ 40 % strain marked with significant strain hardening, (b) intermetallics with moderate Fe content (Ti50Ni35Fe15) showed no SIM transformation, but a typical smooth elastic-plastic transition with maximum strain to failure of ⁓ 11–12 % was observed, and (c) intermetallics with high Fe content (≥ 25 at. %) displayed a very small strain to failure (≤ 5 %) without visible plastic deformation. The TEM and XRD analysis of the deformed (15 % and 40 % strain) Ti50Ni45Fe5 and Ti50Ni40Fe10 intermetallics indicated the presence of internally twinned martensite variants (MVs) along with severely dislocated banded B2 matrix. The observed contrast in the deformation characteristics has been attributed to the variation in the values of elastic constants (C' and C44) and Zener anisotropy (A) with Fe content. The SIM transformation in Ti50Ni45Fe5 and Ti50Ni40Fe10 occurred at lower values of C' and C44 (due to elastic softening) and relatively low Zener anisotropy A. The significant plastic strain in these two intermetallics was accommodated by the presence and deformation of super intrinsic stacking faults (SISFs) formed by dissociation of 12⟨111⟩ screw super-partials. In contrast, the deformation in the intermetallics with high Fe content (≥ 25 at. %) was governed by the activation of ⟨100⟩ screw dislocations.

Lie group analysis of bingham plastic flow over a straining surface in the presence of magnetohydrodynamic effects and slip conditions

This paper investigates the two-dimensional flow of a Bingham plastic over a straining surface subjected to an externally applied magnetic field and surface slips. The study aims to understand the behavior of such flows and their response to external factors, which has applications in various industrial processes involving complex fluid dynamics. Through Lie group analysis, a new set of similarity transformations are derived to reduce the number of variables in the governing partial differential equations, facilitating a more tractable analysis. These transformations enable the conversion of the partial differential equations into a self-similar system of ordinary differential equations. A high-order, three-stage Lobatto IIIa formula along with appropriate boundary conditions is applied to solve this system. The solutions obtained for various physical parameters lead to several key deductions. It is found that under constant physical parameter values, the velocity layer thickness of the plastic flow is lower compared to the thermal layer thickness, indicating the dominance of the plastic flow behavior. Additionally, an increase in the magnetic field results in a reduction in the thickness of the plastic boundary layer, highlighting the significant influence of magnetic fields on the flow characteristics. These findings provide valuable insights into the control and optimization of processes involving Bingham plastic flows, particularly in the presence of magnetic fields and surface slips.

#406 High ferritin is not needed in hemodialysis patients: a retrospective study of total body iron and oral iron replacement therapy

Abstract Background and Aims In vivo iron levels can be adjusted through intestinal iron absorption to be maintained at a suitable level; however, optimal iron levels in hemodialysis (HD) patients are unclear. Although serum ferritin is useful as an indicator of iron stores, it does not necessarily reflect body iron levels in HD patients with unstable hematopoiesis since iron metabolism is a semi-closed system in vivo. In this study, we investigated total body iron (TBI), new index calculated as the sum of red blood cell (RBC) iron and iron stores, during courses of low-dose oral iron replacement therapy, and evaluated in vivo iron sufficiency and its indicators in HD patients. Method We analyzed data on 105 courses of low-dose iron replacement therapy (50–120 mg of iron daily) administered to 83 patients with serum ferritin <60 ng/mL and Hb <12 g/dL undergoing maintenance hemodialysis at our institution. Low-dose oral iron replacement therapy was initiated between August 2016 and June 2023 and continued for at least seven months. All blood samples were collected at the start of hemodialysis at the beginning of the week. Blood examinations were performed twice a month, and patients were given darbepoetin alfa (DA), long-acting ESAs to maintain Hb at the target level of 10–12 g/dL, in accordance with the guidelines of the Japanese Society for Dialysis Therapy. Iron-related parameters were determined based on blood samples collected once a month, with TSAT calculated from serum iron (Fe) and total iron-binding capacity (TIBC), using the following equation. TSAT=Fe/TIBC × 100. We evaluated changes in TBI, RBC iron, and iron stores from the initiation of treatment to month 7, in two groups of patients, namely, iron-therapy responders and non-responders. Furthermore, we investigated factors associated with steady-state TBI. TBI was regarded as achieving a steady state during the course of therapy when the trend shifted from an increase and the difference from the value at one month was less than or equal to zero. TBI was calculated using the formula proposed by Cable et al (Transfusion. 2016, 56, 2005). Results Mean age was 68.1±12.6 years and median time on hemodialysis was 6.6 years. Of the 105 courses of therapy, 75 were delivered to men and 30 to women, and 66.7% of the patients had diabetic nephropathy. The patients had a mean Hb level of 10.4±0.7 g/dL, a mean serum ferritin level of 27.3±12.5 ng/mL, mean transferrin saturation (TSAT) of 18.1%±5.9%, and a median C-reactive protein level of 0.1 mg/dL at the start of each course. TBI showed significant increases until month 4 and plateaued thereafter in iron-therapy responders, and tended to increase and then reached a similar plateau in non-responders (month 7: 1900±447 vs. 1900±408 mg, Fig. 1). As for RBC iron, iron-therapy responders showed significant monthly increases up to month 3, whereas non-responders showed constant values. Regarding iron stores, iron-therapy responders showed significant monthly increases up to month 5, while non-responders showed a significant increase only at month 1. DA per body weight showed a significant decrease at month 3 and 4 in the effective group, but a slight increase in the non-responder group. Steady-state TBI did not correlate with Hb or serum ferritin, but was strongly correlated with body surface area (BSA) using the Du Bois formula [TBI=−791.914 + 1628.606 × BSA (m2); R2=0.88, p<0.001, Fig. 2]. Conclusion This study showed that hemodialysis patients can increase their body iron levels during oral iron replacement therapy and maintain them at the same level after sufficiency has been achieved, suggesting activation of a “mucosal block.” Furthermore, this result also suggests that determining iron sufficiency based on serum ferritin alone is difficult in HD patients with fluctuations in Hb. However, regression equations using steady-state TBI and BSA showed a high degree of fit. Therefore, BSA might potentially be used in estimations of TBI sufficiency, which may be useful for avoiding excessive iron dosage.

A negative capacitance field effect transistor with a modified gate stack and drain-side cavity for label-free biosensing

Dielectrically modulated (DM) negative capacitance field effect transistor (NCFET)-based label-free biosensors have emerged as promising devices for accurate detection of various biomolecules, where the sensitivity of DM architectures strongly depends on the sensing mechanism as well as on the size of the nanocavity. Therefore, to achieve higher sensitivity along with reduced fabrication complexity, we propose to utilize a pre-existing drain-side spacer region as a nanocavity, in a fully depleted silicon-on-insulator-based NCFET architecture. The ferroelectric (FE) layer in the metal-ferroelectric-insulator-semiconductor configuration meaningfully alters the impact of the drain’s electric field on the source-side electrostatics, which results in higher sensitivity. Having quantified the sensitivity of an FE-dielectric (FE-DE) gate-stack-based NCFET biosensor, we now propose to include a paraelectric (PE) layer between the FE and DE materials, thus modifying the gate stack from FE-DE to FE-PE-DE with an equivalent negative capacitance seen from both stacks; here, a remarkable improvement is seen in the FE-PE-DE gate-stack-based NCFET, with nearly identical linearity performance, as seen from the high Pearson’s coefficient value ( r2⩾ 0.9). Therefore, to illustrate the efficacy of the proposed sensing mechanism and the modified gate stack (FE-PE-DE), DE constant ( kBio ) values in the range of kBio = 4.5 to kBio = 75.99 are considered. Finally, the effect of scaling the channel length ( Lg ) on the sensitivity of the FE-PE-DE NCFET device is shown, and a high value, particularly at lower permittivity, demonstrates the versatility and wide applicability of the proposed NCFET biosensor.

Co-Ni spinel nanoparticles for energy storage applications: Composition, structural parameters and electrical properties

In the ambit of this investigation, we delved into the properties of (Co/Ni)Fe2O4 spinel nanoparticles (CNSNs) with a spectrum of Co/Ni ratios, delineated as Co1-xNixFe2O4, where x adopts values of 0.0, 0.3, 0.5, 0.7 and 1.0. The synthesis of these CNSNs was adeptly executed via the citrate precursor technique. This study meticulously examined the crystal structure and granular morphology by applying X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was unequivocally determined that each specimen exhibited a homogenous phase. The lattice parameters for the synthesized CNSN compounds agreed with the mean ionic radii of the Co2+ and Ni2+ ions, mirroring their respective concentrations within the nanoparticles. Furthermore, an extensive analysis of the alternating current (AC) electrical properties was carried out, encompassing a broad frequency range from 1 kHz to 3 MHz and a wide temperature range from 303 to 423 K. The observed behavior of the electrical properties was thoroughly evaluated and elucidated, considering the chemical composition of each CNSN. The relationship between the frequency dependency of σac, έ and tanδ is congruent with the prevailing literature and theoretical constructs that elucidate the composite materials' conductivity and dielectric constant, comprising grains and grain boundaries. The present CNSN samples do not exhibit maximum peak for tanδ, potentially due to the wider range of frequencies used than the anticipated peak frequency. The samples' measured conductivity and dielectric constant values displayed a high degree of coherence, corroborating each other's findings. Literature corroborates that the escalation in ac-conductivity values with frequency intimates certainly that the prepared samples may herald promise for utilization in energy storage solutions, bolstering the synergistic efficacy observed. Another conceivable application of these CNSN materials could be their integration in microwave technologies, suggesting a broad scope for future technological advancements.

Anytime-valid off-policy Inference for Contextual Bandits

Contextual bandit algorithms are ubiquitous tools for active sequential experimentation in healthcare and the tech industry. They involve online learning algorithms that adaptively learn policies over time to map observed contexts X t to actions A t in an attempt to maximize stochastic rewards R t . This adaptivity raises interesting but hard statistical inference questions, especially counterfactual ones: for example, it is often of interest to estimate the properties of a hypothetical policy that is different from the logging policy that was used to collect the data—a problem known as “off-policy evaluation” (OPE). Using modern martingale techniques, we present a comprehensive framework for OPE inference that relaxes unnecessary conditions made in some past works (such as performing inference at prespecified sample sizes, uniformly bounded importance weights, constant logging policies, and constant policy values, among others), significantly improving on them both theoretically and empirically. Importantly, our methods can be employed while the original experiment is still running (that is, not necessarily post hoc), when the logging policy may be itself changing (due to learning), and even if the context distributions are a highly dependent time series (such as if they are drifting over time). More concretely, we derive confidence sequences for various functionals of interest in OPE. These include doubly robust ones for time-varying off-policy mean reward values, but also confidence bands for the entire cumulative distribution function of the off-policy reward distribution. All of our methods (a) are valid at arbitrary stopping times; (b) only make nonparametric assumptions; (c) do not require importance weights to be uniformly bounded, and if they are, we do not need to know these bounds; and (d) adapt to the empirical variance of our estimators. In summary, our methods enable anytime-valid off-policy inference using adaptively collected contextual bandit data.

Study of the Influence of Heat Flow on the Time to Ignition of Spruce and Beech Wood

Adherence to fire safety regulations for wood is one of the most important tasks in its use in structural and architectural applications. This article deals with determining the influence of heat flux on the ignition process of spruce (Picea abies L. Karst.) and beech wood (Fagus sylvatica L.). The heat flux was generated by an electric radiant panel. The analysed parameters included the ignition time of the spruce and beech wood samples, the influence of wood density, and sample moisture, and the course of sample combustion, both with and without flame, was observed. The heat flux was maintained at constant values, depending on the distance of the examined sample from the panel, along with the specific power of the radiation panel. The power of the radiation panel was set to constant values of 5 kW and 10 kW. The samples were placed at distances of 50, 70, 100, 150, and 200 mm from the heat source, and heat fluxes in the range of 13–92 kW·m−2 were observed. At a power of 5 kW and a heat flux of 64 kW·m−2, neither the sample of beech nor that of spruce wood, placed at the distance of 100 mm from the radiation panel, exhibited flaming combustion. The ignition time for the beech wood was approximately twice that of the spruce wood, likely due to the higher average wood density. It can be stated that wood density, as one of the main factors, significantly influences the ignition phase of burning. The statistical analysis examined variables including wood type, radiant panel output, distance, and heat flux in relation to ignition time. The analysis revealed a significant difference between ignition time and distance (p-value = 0.0000, H = 37.51583) as well as between ignition time and heat flux (p-value = 0.0000, H = 37.69726). Similarly, the time to ignition for all tested beech wood samples was longer than for spruce wood.

Mechanism of Peroxynitrite Interaction with Ferric M. tuberculosis Nitrobindin: A Computational Study.

Nitrobindins (Nbs) are all-β-barrel heme proteins present along the evolutionary ladder. They display a highly solvent-exposed ferric heme group with the iron atom being coordinated by the proximal His residue and a water molecule at the distal position. Ferric nitrobindins (Nb(III)) play a role in the conversion of toxic peroxynitrite (ONOO-) to harmless nitrate, with the value of the second-order rate constant being similar to those of most heme proteins. The value of the second-order rate constant of Nbs increases as the pH decreases; this suggests that Nb(III) preferentially reacts with peroxynitrous acid (ONOOH), although ONOO- is more nucleophilic. In this work, we shed light on the molecular basis of the ONOO- and ONOOH reactivity of ferric Mycobacterium tuberculosis Nb (Mt-Nb(III)) by dissecting the ligand migration toward the active site, the water molecule release, and the ligand binding process by computer simulations. Classical molecular dynamics simulations were performed by employing a steered molecular dynamics approach and the Jarzynski equality to obtain ligand migration free energy profiles for both ONOO- and ONOOH. Our results indicate that ONOO- and ONOOH migration is almost unhindered, consistent with the exposed metal center of Mt-Nb(III). To further analyze the ligand binding process, we computed potential energy profiles for the displacement of the Fe(III)-coordinated water molecule using a hybrid QM/MM scheme at the DFT level and a nudged elastic band approach. These results indicate that ONOO- exhibits a much larger barrier for ligand displacement than ONOOH, suggesting that water displacement is assisted by protonation of the leaving group by the incoming ONOOH.

Rapidly chemical preparation of Mn doped ZnO nanostructures for photocatalysis efficiency based on UV light system and mechanism insights

Through a facile chemical precipitation process, pure zinc oxide (ZnO) and various ratio of Mn-doped zinc oxide (Zn1-xMnxO) nanostructured materials were synthesized. The degradation of an azo dye acid orange 2 (AO-2) solution under UV light was investigated using the synthesized materials as photocatalysts. XRD, FTIR, DLS, FESEM, EDS, PL, BET, magnetic, TGA and UV–vis techniques were used to elucidate the structural, functional, particle, elemental, morphological, and optical aspects of the catalysts. The XRD and FESEM analysis showed the hexagonal ZnO structure and spherical shape of the ZnO nano-photocatalyst, respectively. The crystal sizes of Zn1-xMnxO are 27.40–38.31 nm. The optical band gap energy of Zn1-xMnxO are 2.53–3.10 eV. Under UV irradiation for 60 min, MZ-25 NPs demonstrated better degradation (100.0%) of AO-2 dye. The effect of various factors such as catalyst quantity, and pH of the dye solution on the rate removal was investigated. After 60 min of UV light irradiation, dye removal was obtained under ideal conditions (with catalyst loading of 3 mgL−1, and pH 4). The rate constant values of MZ-25 sample are determined to be 0.0219 min−1. The scavenging test reveals that ∙O2 − and ∙OH are responsible for the photo-degradation of AO-2 dye.

Synthesis, Binding and Docking Studies of Indole‐1,3,4‐Thiadiazole Derivatives As Potent Α‐Amylase and Lox Inhibitors

AbstractSeries of indole‐1,3,4‐thiadiazole compounds (IT 1–7) were synthesized and characterized by FT‐IR, 1H NMR, 13C NMR and ESI‐MS spectral data. Further, the compounds (IT 1–7) were screened for antidiabetic, antioxidant and anti‐inflammatory activities. Most of these compounds exhibited moderate to good antidiabetic, antioxidant and anti‐inflammatory activities against α‐amylase enzyme, ABTS and lipoxygenase enzyme, respectively. Among these, IT‐1 displayed the better activity compared to that of standard drugs. The mechanism of binding of IT‐1, IT‐5 and IT‐6 with a transporter protein, human serum albumin was investigated by fluorescence spectroscopic and circular dichroism studies. These compounds quenched the intrinsic fluorescence intensity of HSA and moderate binding was evident from the values of binding constants which are in the order of 105 M−1. The molecular docking studies of the compounds were performed against human pancreatic alpha‐amylase in complex with montbretin A (PDB ID: 4W93). The studied compounds interacted with amino acid residues (ASP197, GLU240 and TYR151) which were similar to that of the reference drug, acarbose. The ADME properties of designed compounds were studied using SwissADME software. All the compounds obeyed Lipinski's rule of five. All the compounds showed low or non‐toxicity towards different toxicity classes as analyzed using ProTox‐II online tool.

Exploring Dielectric Properties in Atomistic Models of Amorphous Boron Nitride

Abstract We report a theoretical study of dielectric properties of models of amorphous Boron Nitride, using interatomic potentials generated by machine learning. We first perform first-principles simulations on small (about 100 atoms in the periodic cell) sample sizes to explore the emergence of mid-gap states and its correlation with structural features. Next, by using a simplified tight-binding electronic model, we analyse the dielectric functions for complex three dimensional models (containing about 10.000 atoms) embedding varying concentrations of sp1, sp2 and sp3 bonds between B and N atoms. Within the limits of these methodologies, the resulting value of the zero-frequency dielectric constant is shown to be influenced by the population density of such mid-gap states and their localization characteristics. We observe nontrivial correlations between the structure-induced electronic fluctuations and the resulting dielectric constant values. Our findings are however just a first step in the quest of accessing fully accurate dielectric properties of as-grown amorphous BN of relevance for interconnect technologies and beyond.

Synthesis, optical characterization and electrical behavior of chitosan/MgO/Cr2O3 nanocomposite for electrical applications

Magnesium oxide nanoparticles (MgO NPs) are straightforward, cheap, biocompatible, and biodegradable, making them one of the most popular inexpensive and non-toxic nanoparticles. In addition, Nanosized chromic oxide (Cr2O3) is a significant transition metal oxide due to its numerous exceptional attributes, it finds application in several domains. It has good electrical conductivity, excellent thermal and chemical stability. It is utilized in several industries for its ability to resist oxidation at high temperatures, as well as its application in refractory materials and catalysts. In this study, we utilized a laser ablation approach to synthesize a ternary nanocomposite composed of MgO and Cr2O3 nanoparticles as it is considered a clean method for the preparation of nanoparticles. Subsequently, these nanoparticles were integrated into Chitosan (CS) solution to create polymer nanocomposite via casting route. XRD confirmed the formation of Cr2O3 nanocrystals with size of 61 nm dispersed in chitosan/MgO matrix. FTIR verified the interactions between chitosan, MgO, and Cr2O3 nanoparticles. The broadening and shifting of the OH and NH bands with increasing Cr2O3 content confirms the interaction and complexation between Cr2O3 and Chitosan/MgO. UV–Vis analysis revealed that incorporating 7 wt% Cr2O3 reduced optical band gap from 5.59 eV for chitosan to 3.91 eV. The band gap values decreased with increasing Cr2O3 content due to polaronic defects. TGA showed improved thermal stability, with the 7 wt% Cr2O3 nanocomposite exhibiting a residual mass of 47 % at 700 °C compared to 28 % for chitosan. Dielectric studies demonstrated high dielectric constant and conductivity (10−5 S/cm at 10 Hz) values for the 7 wt% Cr2O3 nanocomposite, attributed to interfacial polarization effects and nanocapacitor formation by the conductive nanofillers. The ternary chitosan/MgO/Cr2O3 nanocomposites with tunable optical, thermal and electrical properties show promising potential for electronic applications.

Luminescent Dansyl-Calix[5]arene for the Recognition of Biogenic Amines

Abstract: A luminescent calix[5]arene with a covalently linked dansyl chromophore substituent has been successfully used, both in solution and in the gas phase (ESI-MS), for the recognition of biogenic amines that contain linear alkylammonium structural unit. Binding constant values, determined by fluorescence spectroscopy, revealed a greater affinity for cadaverine, spermidine, and L-lysine, in which the terminal ammonium group allows for additional stabilizing interactions with the dansyl moiety. objective: the recognition of selected biogenic amines both in solution and in the gas phase (ESI-MS), and determining the relative binding constant values by fluorescence spectroscopy

Optoelectronic and transport properties of Lead-Free halide based Na2AgTlZ6 (Z = Cl, Br, I) double perovskites for energy harvesting applications

The bandgap engineering and deliberate band edge manipulation of perovskites make them potential candidates for the photovoltaic industry. Here we theoretically investigate the structure, density of states, and photovoltaic and thermoelectric characteristics of Na2AgTlZ6 (Z = Cl, Br, I) using WIEN2k code. The incorporation of Br and I at the Cl site caused the increase in lattice constant which leads to the decrease in bulk modulus and Debye temperature. The computed values of Poisson (<0.26) and Pugh (<1.75) ratio verified their brittle nature. The bandgap analysis reveals direct bandgap nature and bandgap value lie in the visible region for parent composition and infrared and far infrared when Cl is replaced with Br and I. The density of state plots uncovers the shifting of energy states in valence and conduction bands towards the Fermi level with the increasing number of electrons in the halogens. The increase in the value of dielectric constant, refractive index, and shifting of peaks towards lower energy value is witnessed with atomic number of halogen atoms. The viability of these compositions for thermoelectric devices is further confirmed when electrical conductivity and Seebeck coefficient dependent Figure of merit and power factor are evaluated in the temperature range of 200–800 K. In addition, the anisotropic nature of studied compositions is explored through the computation of the modulus of elasticity including Young’s modulus, Shear modulus in addition to compressibility, and Poisson’s ratio.

Crucial impact of component Allee effect in predator-prey system

Allee effect in models in interacting species of predator prey system has great significance in ecological context. Allee effect plays crucial role in population dynamics in ecology, where it is the challenging fact that per capita population growth rate is positively dependent on the population density of a species. In this paper, we inspect the famous Hastings and Powell (HP) (Hastings and Powell 1991 Ecology 72 896–903) model incorporating component Allee effect on top predator’s reproduction. We analyse the updated model with the help of both analytical and numerical phenomena. Considering cost of Allee effect, half-saturation constant of prey as the key parameters, the Hopf bifurcations are also analysed. The directions of Hopf bifurcations at the critical values of Allee parameter and half-saturation constant of prey are studied theoretically by using normal form theory introduced by Hassard et al (1981 Theory and Applications of Hopf Bifurcation vol 41 (CUP Archive)). The formulated model indicates that the system demonstrates chaotic, periodic and stable dynamics in the variation of key parameters. The chaos can be controlled for proper application of the large values of parameter used as the cost of Allee effect and also for small values of the parameter used as the half saturation constant of prey population. The results of this study are applicable in the field of marine and wild ecosystem dynamics.

Computing Pareto-Optimal and Almost Envy-Free Allocations of Indivisible Goods

We study the problem of fair and efficient allocation of a set of indivisible goods to agents with additive valuations using the popular fairness notions of envy-freeness up to one good (EF1) and equitability up to one good (EQ1) in conjunction with Pareto-optimality (PO). There exists a pseudo-polynomial time algorithm to compute an EF1+PO allocation and a non-constructive proof of the existence of allocations that are both EF1 and fractionally Pareto-optimal (fPO), which is a stronger notion than PO. We present a pseudopolynomial time algorithm to compute an EF1+fPO allocation, thereby improving the earlier results. Our techniques also enable us to show that an EQ1+fPO allocation always exists when the values are positive and that it can be computed in pseudo-polynomial time. We also consider the class of k-ary instances where k is a constant, i.e., each agent has at most k different values for the goods. For such instances, we show that an EF1+fPO allocation can be computed in strongly polynomial time. When all values are positive, we show that an EQ1+fPO allocation for such instances can be computed in strongly polynomial time. Next, we consider instances where the number of agents is constant and show that an EF1+PO (likewise, an EQ1+PO) allocation can be computed in polynomial time. These results significantly extend the polynomial-time computability beyond the known cases of binary or identical valuations. We also design a polynomial-time algorithm that computes a Nash welfare maximizing allocation when there are constantly many agents with constant many different values for the goods. Finally, on the complexity side, we show that the problem of computing an EF1+fPO allocation lies in the complexity class PLS.